Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/fs/namespace.c |
| 3 | * |
| 4 | * (C) Copyright Al Viro 2000, 2001 |
| 5 | * Released under GPL v2. |
| 6 | * |
| 7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. |
| 8 | * Heavily rewritten. |
| 9 | */ |
| 10 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/syscalls.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 12 | #include <linux/export.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 13 | #include <linux/capability.h> |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 14 | #include <linux/mnt_namespace.h> |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 15 | #include <linux/user_namespace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/namei.h> |
| 17 | #include <linux/security.h> |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 18 | #include <linux/idr.h> |
Rob Landley | 57f150a | 2013-09-11 14:26:10 -0700 | [diff] [blame] | 19 | #include <linux/init.h> /* init_rootfs */ |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 20 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
| 21 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ |
| 22 | #include <linux/uaccess.h> |
David Howells | 0bb80f2 | 2013-04-12 01:50:06 +0100 | [diff] [blame] | 23 | #include <linux/proc_ns.h> |
Linus Torvalds | 20b4fb4 | 2013-05-01 17:51:54 -0700 | [diff] [blame] | 24 | #include <linux/magic.h> |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 25 | #include <linux/bootmem.h> |
Al Viro | 9ea459e | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 26 | #include <linux/task_work.h> |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 27 | #include "pnode.h" |
Adrian Bunk | 948730b | 2007-07-15 23:41:25 -0700 | [diff] [blame] | 28 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 30 | /* Maximum number of mounts in a mount namespace */ |
| 31 | unsigned int sysctl_mount_max __read_mostly = 100000; |
| 32 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 33 | static unsigned int m_hash_mask __read_mostly; |
| 34 | static unsigned int m_hash_shift __read_mostly; |
| 35 | static unsigned int mp_hash_mask __read_mostly; |
| 36 | static unsigned int mp_hash_shift __read_mostly; |
| 37 | |
| 38 | static __initdata unsigned long mhash_entries; |
| 39 | static int __init set_mhash_entries(char *str) |
| 40 | { |
| 41 | if (!str) |
| 42 | return 0; |
| 43 | mhash_entries = simple_strtoul(str, &str, 0); |
| 44 | return 1; |
| 45 | } |
| 46 | __setup("mhash_entries=", set_mhash_entries); |
| 47 | |
| 48 | static __initdata unsigned long mphash_entries; |
| 49 | static int __init set_mphash_entries(char *str) |
| 50 | { |
| 51 | if (!str) |
| 52 | return 0; |
| 53 | mphash_entries = simple_strtoul(str, &str, 0); |
| 54 | return 1; |
| 55 | } |
| 56 | __setup("mphash_entries=", set_mphash_entries); |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 57 | |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 58 | static u64 event; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 59 | static DEFINE_IDA(mnt_id_ida); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 60 | static DEFINE_IDA(mnt_group_ida); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 61 | static DEFINE_SPINLOCK(mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 62 | static int mnt_id_start = 0; |
| 63 | static int mnt_group_start = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 65 | static struct hlist_head *mount_hashtable __read_mostly; |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 66 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 67 | static struct kmem_cache *mnt_cache __read_mostly; |
Al Viro | 59aa0da | 2013-09-16 21:34:53 -0400 | [diff] [blame] | 68 | static DECLARE_RWSEM(namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 70 | /* /sys/fs */ |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 71 | struct kobject *fs_kobj; |
| 72 | EXPORT_SYMBOL_GPL(fs_kobj); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 73 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 74 | /* |
| 75 | * vfsmount lock may be taken for read to prevent changes to the |
| 76 | * vfsmount hash, ie. during mountpoint lookups or walking back |
| 77 | * up the tree. |
| 78 | * |
| 79 | * It should be taken for write in all cases where the vfsmount |
| 80 | * tree or hash is modified or when a vfsmount structure is modified. |
| 81 | */ |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 82 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 83 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 84 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 86 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 87 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 88 | tmp = tmp + (tmp >> m_hash_shift); |
| 89 | return &mount_hashtable[tmp & m_hash_mask]; |
| 90 | } |
| 91 | |
| 92 | static inline struct hlist_head *mp_hash(struct dentry *dentry) |
| 93 | { |
| 94 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); |
| 95 | tmp = tmp + (tmp >> mp_hash_shift); |
| 96 | return &mountpoint_hashtable[tmp & mp_hash_mask]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 97 | } |
| 98 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 99 | /* |
| 100 | * allocation is serialized by namespace_sem, but we need the spinlock to |
| 101 | * serialize with freeing. |
| 102 | */ |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 103 | static int mnt_alloc_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 104 | { |
| 105 | int res; |
| 106 | |
| 107 | retry: |
| 108 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 109 | spin_lock(&mnt_id_lock); |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 110 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 111 | if (!res) |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 112 | mnt_id_start = mnt->mnt_id + 1; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 113 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 114 | if (res == -EAGAIN) |
| 115 | goto retry; |
| 116 | |
| 117 | return res; |
| 118 | } |
| 119 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 120 | static void mnt_free_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 121 | { |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 122 | int id = mnt->mnt_id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 123 | spin_lock(&mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 124 | ida_remove(&mnt_id_ida, id); |
| 125 | if (mnt_id_start > id) |
| 126 | mnt_id_start = id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 127 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 128 | } |
| 129 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 130 | /* |
| 131 | * Allocate a new peer group ID |
| 132 | * |
| 133 | * mnt_group_ida is protected by namespace_sem |
| 134 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 135 | static int mnt_alloc_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 136 | { |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 137 | int res; |
| 138 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 139 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
| 140 | return -ENOMEM; |
| 141 | |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 142 | res = ida_get_new_above(&mnt_group_ida, |
| 143 | mnt_group_start, |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 144 | &mnt->mnt_group_id); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 145 | if (!res) |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 146 | mnt_group_start = mnt->mnt_group_id + 1; |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 147 | |
| 148 | return res; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 149 | } |
| 150 | |
| 151 | /* |
| 152 | * Release a peer group ID |
| 153 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 154 | void mnt_release_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 155 | { |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 156 | int id = mnt->mnt_group_id; |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 157 | ida_remove(&mnt_group_ida, id); |
| 158 | if (mnt_group_start > id) |
| 159 | mnt_group_start = id; |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 160 | mnt->mnt_group_id = 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 161 | } |
| 162 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 163 | /* |
| 164 | * vfsmount lock must be held for read |
| 165 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 166 | static inline void mnt_add_count(struct mount *mnt, int n) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 167 | { |
| 168 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 169 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 170 | #else |
| 171 | preempt_disable(); |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 172 | mnt->mnt_count += n; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 173 | preempt_enable(); |
| 174 | #endif |
| 175 | } |
| 176 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 177 | /* |
| 178 | * vfsmount lock must be held for write |
| 179 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 180 | unsigned int mnt_get_count(struct mount *mnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 181 | { |
| 182 | #ifdef CONFIG_SMP |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 183 | unsigned int count = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 184 | int cpu; |
| 185 | |
| 186 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 187 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 188 | } |
| 189 | |
| 190 | return count; |
| 191 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 192 | return mnt->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 193 | #endif |
| 194 | } |
| 195 | |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 196 | static void drop_mountpoint(struct fs_pin *p) |
| 197 | { |
| 198 | struct mount *m = container_of(p, struct mount, mnt_umount); |
| 199 | dput(m->mnt_ex_mountpoint); |
| 200 | pin_remove(p); |
| 201 | mntput(&m->mnt); |
| 202 | } |
| 203 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 204 | static struct mount *alloc_vfsmnt(const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 205 | { |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 206 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
| 207 | if (mnt) { |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 208 | int err; |
| 209 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 210 | err = mnt_alloc_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 211 | if (err) |
| 212 | goto out_free_cache; |
| 213 | |
| 214 | if (name) { |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 215 | mnt->mnt_devname = kstrdup_const(name, GFP_KERNEL); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 216 | if (!mnt->mnt_devname) |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 217 | goto out_free_id; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 218 | } |
| 219 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 220 | #ifdef CONFIG_SMP |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 221 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
| 222 | if (!mnt->mnt_pcp) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 223 | goto out_free_devname; |
| 224 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 225 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 226 | #else |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 227 | mnt->mnt_count = 1; |
| 228 | mnt->mnt_writers = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 229 | #endif |
| 230 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 231 | INIT_HLIST_NODE(&mnt->mnt_hash); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 232 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 233 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 234 | INIT_LIST_HEAD(&mnt->mnt_list); |
| 235 | INIT_LIST_HEAD(&mnt->mnt_expire); |
| 236 | INIT_LIST_HEAD(&mnt->mnt_share); |
| 237 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 238 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 239 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
Eric W. Biederman | bb4fbf0 | 2016-10-24 16:16:13 -0500 | [diff] [blame] | 240 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
Andreas Gruenbacher | 2504c5d | 2009-12-17 21:24:27 -0500 | [diff] [blame] | 241 | #ifdef CONFIG_FSNOTIFY |
| 242 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); |
| 243 | #endif |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 244 | init_fs_pin(&mnt->mnt_umount, drop_mountpoint); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 245 | } |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 246 | return mnt; |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 247 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 248 | #ifdef CONFIG_SMP |
| 249 | out_free_devname: |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 250 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 251 | #endif |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 252 | out_free_id: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 253 | mnt_free_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 254 | out_free_cache: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 255 | kmem_cache_free(mnt_cache, mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 256 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | } |
| 258 | |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 259 | /* |
| 260 | * Most r/o checks on a fs are for operations that take |
| 261 | * discrete amounts of time, like a write() or unlink(). |
| 262 | * We must keep track of when those operations start |
| 263 | * (for permission checks) and when they end, so that |
| 264 | * we can determine when writes are able to occur to |
| 265 | * a filesystem. |
| 266 | */ |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 267 | /* |
| 268 | * __mnt_is_readonly: check whether a mount is read-only |
| 269 | * @mnt: the mount to check for its write status |
| 270 | * |
| 271 | * This shouldn't be used directly ouside of the VFS. |
| 272 | * It does not guarantee that the filesystem will stay |
| 273 | * r/w, just that it is right *now*. This can not and |
| 274 | * should not be used in place of IS_RDONLY(inode). |
| 275 | * mnt_want/drop_write() will _keep_ the filesystem |
| 276 | * r/w. |
| 277 | */ |
| 278 | int __mnt_is_readonly(struct vfsmount *mnt) |
| 279 | { |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 280 | if (mnt->mnt_flags & MNT_READONLY) |
| 281 | return 1; |
| 282 | if (mnt->mnt_sb->s_flags & MS_RDONLY) |
| 283 | return 1; |
| 284 | return 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 285 | } |
| 286 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 287 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 288 | static inline void mnt_inc_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 289 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 290 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 291 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 292 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 293 | mnt->mnt_writers++; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 294 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 295 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 296 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 297 | static inline void mnt_dec_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 298 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 299 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 300 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 301 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 302 | mnt->mnt_writers--; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 303 | #endif |
| 304 | } |
| 305 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 306 | static unsigned int mnt_get_writers(struct mount *mnt) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 307 | { |
| 308 | #ifdef CONFIG_SMP |
| 309 | unsigned int count = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 310 | int cpu; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 311 | |
| 312 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 313 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 314 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 315 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 316 | return count; |
| 317 | #else |
| 318 | return mnt->mnt_writers; |
| 319 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 320 | } |
| 321 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 322 | static int mnt_is_readonly(struct vfsmount *mnt) |
| 323 | { |
| 324 | if (mnt->mnt_sb->s_readonly_remount) |
| 325 | return 1; |
| 326 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ |
| 327 | smp_rmb(); |
| 328 | return __mnt_is_readonly(mnt); |
| 329 | } |
| 330 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 331 | /* |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 332 | * Most r/o & frozen checks on a fs are for operations that take discrete |
| 333 | * amounts of time, like a write() or unlink(). We must keep track of when |
| 334 | * those operations start (for permission checks) and when they end, so that we |
| 335 | * can determine when writes are able to occur to a filesystem. |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 336 | */ |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 337 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 338 | * __mnt_want_write - get write access to a mount without freeze protection |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 339 | * @m: the mount on which to take a write |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 340 | * |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 341 | * This tells the low-level filesystem that a write is about to be performed to |
| 342 | * it, and makes sure that writes are allowed (mnt it read-write) before |
| 343 | * returning success. This operation does not protect against filesystem being |
| 344 | * frozen. When the write operation is finished, __mnt_drop_write() must be |
| 345 | * called. This is effectively a refcount. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 346 | */ |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 347 | int __mnt_want_write(struct vfsmount *m) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 348 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 349 | struct mount *mnt = real_mount(m); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 350 | int ret = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 351 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 352 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 353 | mnt_inc_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 354 | /* |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 355 | * The store to mnt_inc_writers must be visible before we pass |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 356 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 357 | * incremented count after it has set MNT_WRITE_HOLD. |
| 358 | */ |
| 359 | smp_mb(); |
Miao Xie | 1e75529 | 2012-11-16 17:23:50 +0800 | [diff] [blame] | 360 | while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 361 | cpu_relax(); |
| 362 | /* |
| 363 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will |
| 364 | * be set to match its requirements. So we must not load that until |
| 365 | * MNT_WRITE_HOLD is cleared. |
| 366 | */ |
| 367 | smp_rmb(); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 368 | if (mnt_is_readonly(m)) { |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 369 | mnt_dec_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 370 | ret = -EROFS; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 371 | } |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 372 | preempt_enable(); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 373 | |
| 374 | return ret; |
| 375 | } |
| 376 | |
| 377 | /** |
| 378 | * mnt_want_write - get write access to a mount |
| 379 | * @m: the mount on which to take a write |
| 380 | * |
| 381 | * This tells the low-level filesystem that a write is about to be performed to |
| 382 | * it, and makes sure that writes are allowed (mount is read-write, filesystem |
| 383 | * is not frozen) before returning success. When the write operation is |
| 384 | * finished, mnt_drop_write() must be called. This is effectively a refcount. |
| 385 | */ |
| 386 | int mnt_want_write(struct vfsmount *m) |
| 387 | { |
| 388 | int ret; |
| 389 | |
| 390 | sb_start_write(m->mnt_sb); |
| 391 | ret = __mnt_want_write(m); |
| 392 | if (ret) |
| 393 | sb_end_write(m->mnt_sb); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 394 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 395 | } |
| 396 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 397 | |
| 398 | /** |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 399 | * mnt_clone_write - get write access to a mount |
| 400 | * @mnt: the mount on which to take a write |
| 401 | * |
| 402 | * This is effectively like mnt_want_write, except |
| 403 | * it must only be used to take an extra write reference |
| 404 | * on a mountpoint that we already know has a write reference |
| 405 | * on it. This allows some optimisation. |
| 406 | * |
| 407 | * After finished, mnt_drop_write must be called as usual to |
| 408 | * drop the reference. |
| 409 | */ |
| 410 | int mnt_clone_write(struct vfsmount *mnt) |
| 411 | { |
| 412 | /* superblock may be r/o */ |
| 413 | if (__mnt_is_readonly(mnt)) |
| 414 | return -EROFS; |
| 415 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 416 | mnt_inc_writers(real_mount(mnt)); |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 417 | preempt_enable(); |
| 418 | return 0; |
| 419 | } |
| 420 | EXPORT_SYMBOL_GPL(mnt_clone_write); |
| 421 | |
| 422 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 423 | * __mnt_want_write_file - get write access to a file's mount |
| 424 | * @file: the file who's mount on which to take a write |
| 425 | * |
| 426 | * This is like __mnt_want_write, but it takes a file and can |
| 427 | * do some optimisations if the file is open for write already |
| 428 | */ |
| 429 | int __mnt_want_write_file(struct file *file) |
| 430 | { |
Al Viro | 83f936c | 2014-03-14 12:02:47 -0400 | [diff] [blame] | 431 | if (!(file->f_mode & FMODE_WRITER)) |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 432 | return __mnt_want_write(file->f_path.mnt); |
| 433 | else |
| 434 | return mnt_clone_write(file->f_path.mnt); |
| 435 | } |
| 436 | |
| 437 | /** |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 438 | * mnt_want_write_file - get write access to a file's mount |
| 439 | * @file: the file who's mount on which to take a write |
| 440 | * |
| 441 | * This is like mnt_want_write, but it takes a file and can |
| 442 | * do some optimisations if the file is open for write already |
| 443 | */ |
| 444 | int mnt_want_write_file(struct file *file) |
| 445 | { |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 446 | int ret; |
| 447 | |
| 448 | sb_start_write(file->f_path.mnt->mnt_sb); |
| 449 | ret = __mnt_want_write_file(file); |
| 450 | if (ret) |
| 451 | sb_end_write(file->f_path.mnt->mnt_sb); |
| 452 | return ret; |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 453 | } |
| 454 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
| 455 | |
| 456 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 457 | * __mnt_drop_write - give up write access to a mount |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 458 | * @mnt: the mount on which to give up write access |
| 459 | * |
| 460 | * Tells the low-level filesystem that we are done |
| 461 | * performing writes to it. Must be matched with |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 462 | * __mnt_want_write() call above. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 463 | */ |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 464 | void __mnt_drop_write(struct vfsmount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 465 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 466 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 467 | mnt_dec_writers(real_mount(mnt)); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 468 | preempt_enable(); |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 469 | } |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 470 | |
| 471 | /** |
| 472 | * mnt_drop_write - give up write access to a mount |
| 473 | * @mnt: the mount on which to give up write access |
| 474 | * |
| 475 | * Tells the low-level filesystem that we are done performing writes to it and |
| 476 | * also allows filesystem to be frozen again. Must be matched with |
| 477 | * mnt_want_write() call above. |
| 478 | */ |
| 479 | void mnt_drop_write(struct vfsmount *mnt) |
| 480 | { |
| 481 | __mnt_drop_write(mnt); |
| 482 | sb_end_write(mnt->mnt_sb); |
| 483 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 484 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 485 | |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 486 | void __mnt_drop_write_file(struct file *file) |
| 487 | { |
| 488 | __mnt_drop_write(file->f_path.mnt); |
| 489 | } |
| 490 | |
Al Viro | 2a79f17 | 2011-12-09 08:06:57 -0500 | [diff] [blame] | 491 | void mnt_drop_write_file(struct file *file) |
| 492 | { |
| 493 | mnt_drop_write(file->f_path.mnt); |
| 494 | } |
| 495 | EXPORT_SYMBOL(mnt_drop_write_file); |
| 496 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 497 | static int mnt_make_readonly(struct mount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 498 | { |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 499 | int ret = 0; |
| 500 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 501 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 502 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 503 | /* |
| 504 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 505 | * should be visible before we do. |
| 506 | */ |
| 507 | smp_mb(); |
| 508 | |
| 509 | /* |
| 510 | * With writers on hold, if this value is zero, then there are |
| 511 | * definitely no active writers (although held writers may subsequently |
| 512 | * increment the count, they'll have to wait, and decrement it after |
| 513 | * seeing MNT_READONLY). |
| 514 | * |
| 515 | * It is OK to have counter incremented on one CPU and decremented on |
| 516 | * another: the sum will add up correctly. The danger would be when we |
| 517 | * sum up each counter, if we read a counter before it is incremented, |
| 518 | * but then read another CPU's count which it has been subsequently |
| 519 | * decremented from -- we would see more decrements than we should. |
| 520 | * MNT_WRITE_HOLD protects against this scenario, because |
| 521 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 522 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 523 | * we're counting up here. |
| 524 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 525 | if (mnt_get_writers(mnt) > 0) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 526 | ret = -EBUSY; |
| 527 | else |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 528 | mnt->mnt.mnt_flags |= MNT_READONLY; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 529 | /* |
| 530 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 531 | * that become unheld will see MNT_READONLY. |
| 532 | */ |
| 533 | smp_wmb(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 534 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 535 | unlock_mount_hash(); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 536 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 537 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 538 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 539 | static void __mnt_unmake_readonly(struct mount *mnt) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 540 | { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 541 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 542 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 543 | unlock_mount_hash(); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 544 | } |
| 545 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 546 | int sb_prepare_remount_readonly(struct super_block *sb) |
| 547 | { |
| 548 | struct mount *mnt; |
| 549 | int err = 0; |
| 550 | |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 551 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
| 552 | if (atomic_long_read(&sb->s_remove_count)) |
| 553 | return -EBUSY; |
| 554 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 555 | lock_mount_hash(); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 556 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 557 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { |
| 558 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
| 559 | smp_mb(); |
| 560 | if (mnt_get_writers(mnt) > 0) { |
| 561 | err = -EBUSY; |
| 562 | break; |
| 563 | } |
| 564 | } |
| 565 | } |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 566 | if (!err && atomic_long_read(&sb->s_remove_count)) |
| 567 | err = -EBUSY; |
| 568 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 569 | if (!err) { |
| 570 | sb->s_readonly_remount = 1; |
| 571 | smp_wmb(); |
| 572 | } |
| 573 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 574 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
| 575 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
| 576 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 577 | unlock_mount_hash(); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 578 | |
| 579 | return err; |
| 580 | } |
| 581 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 582 | static void free_vfsmnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 583 | { |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 584 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 585 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 586 | free_percpu(mnt->mnt_pcp); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 587 | #endif |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 588 | kmem_cache_free(mnt_cache, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 589 | } |
| 590 | |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 591 | static void delayed_free_vfsmnt(struct rcu_head *head) |
| 592 | { |
| 593 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); |
| 594 | } |
| 595 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 596 | /* call under rcu_read_lock */ |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 597 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 598 | { |
| 599 | struct mount *mnt; |
| 600 | if (read_seqretry(&mount_lock, seq)) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 601 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 602 | if (bastard == NULL) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 603 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 604 | mnt = real_mount(bastard); |
| 605 | mnt_add_count(mnt, 1); |
| 606 | if (likely(!read_seqretry(&mount_lock, seq))) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 607 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 608 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
| 609 | mnt_add_count(mnt, -1); |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 610 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 611 | } |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 612 | return -1; |
| 613 | } |
| 614 | |
| 615 | /* call under rcu_read_lock */ |
| 616 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
| 617 | { |
| 618 | int res = __legitimize_mnt(bastard, seq); |
| 619 | if (likely(!res)) |
| 620 | return true; |
| 621 | if (unlikely(res < 0)) { |
| 622 | rcu_read_unlock(); |
| 623 | mntput(bastard); |
| 624 | rcu_read_lock(); |
| 625 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 626 | return false; |
| 627 | } |
| 628 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | /* |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 630 | * find the first mount at @dentry on vfsmount @mnt. |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 631 | * call under rcu_read_lock() |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 632 | */ |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 633 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 634 | { |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 635 | struct hlist_head *head = m_hash(mnt, dentry); |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 636 | struct mount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 637 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 638 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 639 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
| 640 | return p; |
| 641 | return NULL; |
| 642 | } |
| 643 | |
| 644 | /* |
David Howells | f015f126 | 2012-06-25 12:55:28 +0100 | [diff] [blame] | 645 | * lookup_mnt - Return the first child mount mounted at path |
| 646 | * |
| 647 | * "First" means first mounted chronologically. If you create the |
| 648 | * following mounts: |
| 649 | * |
| 650 | * mount /dev/sda1 /mnt |
| 651 | * mount /dev/sda2 /mnt |
| 652 | * mount /dev/sda3 /mnt |
| 653 | * |
| 654 | * Then lookup_mnt() on the base /mnt dentry in the root mount will |
| 655 | * return successively the root dentry and vfsmount of /dev/sda1, then |
| 656 | * /dev/sda2, then /dev/sda3, then NULL. |
| 657 | * |
| 658 | * lookup_mnt takes a reference to the found vfsmount. |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 659 | */ |
Al Viro | 1c755af | 2009-04-18 14:06:57 -0400 | [diff] [blame] | 660 | struct vfsmount *lookup_mnt(struct path *path) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 661 | { |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 662 | struct mount *child_mnt; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 663 | struct vfsmount *m; |
| 664 | unsigned seq; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 665 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 666 | rcu_read_lock(); |
| 667 | do { |
| 668 | seq = read_seqbegin(&mount_lock); |
| 669 | child_mnt = __lookup_mnt(path->mnt, path->dentry); |
| 670 | m = child_mnt ? &child_mnt->mnt : NULL; |
| 671 | } while (!legitimize_mnt(m, seq)); |
| 672 | rcu_read_unlock(); |
| 673 | return m; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 674 | } |
| 675 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 676 | /* |
| 677 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the |
| 678 | * current mount namespace. |
| 679 | * |
| 680 | * The common case is dentries are not mountpoints at all and that |
| 681 | * test is handled inline. For the slow case when we are actually |
| 682 | * dealing with a mountpoint of some kind, walk through all of the |
| 683 | * mounts in the current mount namespace and test to see if the dentry |
| 684 | * is a mountpoint. |
| 685 | * |
| 686 | * The mount_hashtable is not usable in the context because we |
| 687 | * need to identify all mounts that may be in the current mount |
| 688 | * namespace not just a mount that happens to have some specified |
| 689 | * parent mount. |
| 690 | */ |
| 691 | bool __is_local_mountpoint(struct dentry *dentry) |
| 692 | { |
| 693 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 694 | struct mount *mnt; |
| 695 | bool is_covered = false; |
| 696 | |
| 697 | if (!d_mountpoint(dentry)) |
| 698 | goto out; |
| 699 | |
| 700 | down_read(&namespace_sem); |
| 701 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
| 702 | is_covered = (mnt->mnt_mountpoint == dentry); |
| 703 | if (is_covered) |
| 704 | break; |
| 705 | } |
| 706 | up_read(&namespace_sem); |
| 707 | out: |
| 708 | return is_covered; |
| 709 | } |
| 710 | |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 711 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 712 | { |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 713 | struct hlist_head *chain = mp_hash(dentry); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 714 | struct mountpoint *mp; |
| 715 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 716 | hlist_for_each_entry(mp, chain, m_hash) { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 717 | if (mp->m_dentry == dentry) { |
| 718 | /* might be worth a WARN_ON() */ |
| 719 | if (d_unlinked(dentry)) |
| 720 | return ERR_PTR(-ENOENT); |
| 721 | mp->m_count++; |
| 722 | return mp; |
| 723 | } |
| 724 | } |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 725 | return NULL; |
| 726 | } |
| 727 | |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 728 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 729 | { |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 730 | struct mountpoint *mp, *new = NULL; |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 731 | int ret; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 732 | |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 733 | if (d_mountpoint(dentry)) { |
| 734 | mountpoint: |
| 735 | read_seqlock_excl(&mount_lock); |
| 736 | mp = lookup_mountpoint(dentry); |
| 737 | read_sequnlock_excl(&mount_lock); |
| 738 | if (mp) |
| 739 | goto done; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 740 | } |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 741 | |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 742 | if (!new) |
| 743 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); |
| 744 | if (!new) |
| 745 | return ERR_PTR(-ENOMEM); |
| 746 | |
| 747 | |
| 748 | /* Exactly one processes may set d_mounted */ |
| 749 | ret = d_set_mounted(dentry); |
| 750 | |
| 751 | /* Someone else set d_mounted? */ |
| 752 | if (ret == -EBUSY) |
| 753 | goto mountpoint; |
| 754 | |
| 755 | /* The dentry is not available as a mountpoint? */ |
| 756 | mp = ERR_PTR(ret); |
| 757 | if (ret) |
| 758 | goto done; |
| 759 | |
| 760 | /* Add the new mountpoint to the hash table */ |
| 761 | read_seqlock_excl(&mount_lock); |
| 762 | new->m_dentry = dentry; |
| 763 | new->m_count = 1; |
| 764 | hlist_add_head(&new->m_hash, mp_hash(dentry)); |
| 765 | INIT_HLIST_HEAD(&new->m_list); |
| 766 | read_sequnlock_excl(&mount_lock); |
| 767 | |
| 768 | mp = new; |
| 769 | new = NULL; |
| 770 | done: |
| 771 | kfree(new); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 772 | return mp; |
| 773 | } |
| 774 | |
| 775 | static void put_mountpoint(struct mountpoint *mp) |
| 776 | { |
| 777 | if (!--mp->m_count) { |
| 778 | struct dentry *dentry = mp->m_dentry; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 779 | BUG_ON(!hlist_empty(&mp->m_list)); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 780 | spin_lock(&dentry->d_lock); |
| 781 | dentry->d_flags &= ~DCACHE_MOUNTED; |
| 782 | spin_unlock(&dentry->d_lock); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 783 | hlist_del(&mp->m_hash); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 784 | kfree(mp); |
| 785 | } |
| 786 | } |
| 787 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 788 | static inline int check_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 789 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 790 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 791 | } |
| 792 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 793 | /* |
| 794 | * vfsmount lock must be held for write |
| 795 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 796 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 797 | { |
| 798 | if (ns) { |
| 799 | ns->event = ++event; |
| 800 | wake_up_interruptible(&ns->poll); |
| 801 | } |
| 802 | } |
| 803 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 804 | /* |
| 805 | * vfsmount lock must be held for write |
| 806 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 807 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 808 | { |
| 809 | if (ns && ns->event != event) { |
| 810 | ns->event = event; |
| 811 | wake_up_interruptible(&ns->poll); |
| 812 | } |
| 813 | } |
| 814 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 815 | /* |
| 816 | * vfsmount lock must be held for write |
| 817 | */ |
Eric W. Biederman | 7bdb11d | 2014-12-29 13:03:41 -0600 | [diff] [blame] | 818 | static void unhash_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 819 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 820 | mnt->mnt_parent = mnt; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 821 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 822 | list_del_init(&mnt->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 823 | hlist_del_init_rcu(&mnt->mnt_hash); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 824 | hlist_del_init(&mnt->mnt_mp_list); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 825 | put_mountpoint(mnt->mnt_mp); |
| 826 | mnt->mnt_mp = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 827 | } |
| 828 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 829 | /* |
| 830 | * vfsmount lock must be held for write |
| 831 | */ |
Eric W. Biederman | 7bdb11d | 2014-12-29 13:03:41 -0600 | [diff] [blame] | 832 | static void detach_mnt(struct mount *mnt, struct path *old_path) |
| 833 | { |
| 834 | old_path->dentry = mnt->mnt_mountpoint; |
| 835 | old_path->mnt = &mnt->mnt_parent->mnt; |
| 836 | unhash_mnt(mnt); |
| 837 | } |
| 838 | |
| 839 | /* |
| 840 | * vfsmount lock must be held for write |
| 841 | */ |
Eric W. Biederman | 6a46c57 | 2015-01-15 22:58:33 -0600 | [diff] [blame] | 842 | static void umount_mnt(struct mount *mnt) |
| 843 | { |
| 844 | /* old mountpoint will be dropped when we can do that */ |
| 845 | mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint; |
| 846 | unhash_mnt(mnt); |
| 847 | } |
| 848 | |
| 849 | /* |
| 850 | * vfsmount lock must be held for write |
| 851 | */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 852 | void mnt_set_mountpoint(struct mount *mnt, |
| 853 | struct mountpoint *mp, |
Al Viro | 44d964d6 | 2011-11-24 21:28:22 -0500 | [diff] [blame] | 854 | struct mount *child_mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 855 | { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 856 | mp->m_count++; |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 857 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 858 | child_mnt->mnt_mountpoint = dget(mp->m_dentry); |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 859 | child_mnt->mnt_parent = mnt; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 860 | child_mnt->mnt_mp = mp; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 861 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 862 | } |
| 863 | |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 864 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
| 865 | { |
| 866 | hlist_add_head_rcu(&mnt->mnt_hash, |
| 867 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); |
| 868 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 869 | } |
| 870 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 871 | /* |
| 872 | * vfsmount lock must be held for write |
| 873 | */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 874 | static void attach_mnt(struct mount *mnt, |
| 875 | struct mount *parent, |
| 876 | struct mountpoint *mp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 877 | { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 878 | mnt_set_mountpoint(parent, mp, mnt); |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 879 | __attach_mnt(mnt, parent); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 880 | } |
| 881 | |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 882 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 883 | { |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 884 | struct mountpoint *old_mp = mnt->mnt_mp; |
| 885 | struct dentry *old_mountpoint = mnt->mnt_mountpoint; |
| 886 | struct mount *old_parent = mnt->mnt_parent; |
| 887 | |
| 888 | list_del_init(&mnt->mnt_child); |
| 889 | hlist_del_init(&mnt->mnt_mp_list); |
| 890 | hlist_del_init_rcu(&mnt->mnt_hash); |
| 891 | |
| 892 | attach_mnt(mnt, parent, mp); |
| 893 | |
| 894 | put_mountpoint(old_mp); |
| 895 | |
| 896 | /* |
| 897 | * Safely avoid even the suggestion this code might sleep or |
| 898 | * lock the mount hash by taking advantage of the knowledge that |
| 899 | * mnt_change_mountpoint will not release the final reference |
| 900 | * to a mountpoint. |
| 901 | * |
| 902 | * During mounting, the mount passed in as the parent mount will |
| 903 | * continue to use the old mountpoint and during unmounting, the |
| 904 | * old mountpoint will continue to exist until namespace_unlock, |
| 905 | * which happens well after mnt_change_mountpoint. |
| 906 | */ |
| 907 | spin_lock(&old_mountpoint->d_lock); |
| 908 | old_mountpoint->d_lockref.count--; |
| 909 | spin_unlock(&old_mountpoint->d_lock); |
| 910 | |
| 911 | mnt_add_count(old_parent, -1); |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 912 | } |
| 913 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 914 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 915 | * vfsmount lock must be held for write |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 916 | */ |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 917 | static void commit_tree(struct mount *mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 918 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 919 | struct mount *parent = mnt->mnt_parent; |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 920 | struct mount *m; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 921 | LIST_HEAD(head); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 922 | struct mnt_namespace *n = parent->mnt_ns; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 923 | |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 924 | BUG_ON(parent == mnt); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 925 | |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 926 | list_add_tail(&head, &mnt->mnt_list); |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 927 | list_for_each_entry(m, &head, mnt_list) |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 928 | m->mnt_ns = n; |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 929 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 930 | list_splice(&head, n->list.prev); |
| 931 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 932 | n->mounts += n->pending_mounts; |
| 933 | n->pending_mounts = 0; |
| 934 | |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 935 | __attach_mnt(mnt, parent); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 936 | touch_mnt_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 937 | } |
| 938 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 939 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 940 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 941 | struct list_head *next = p->mnt_mounts.next; |
| 942 | if (next == &p->mnt_mounts) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 943 | while (1) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 944 | if (p == root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 945 | return NULL; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 946 | next = p->mnt_child.next; |
| 947 | if (next != &p->mnt_parent->mnt_mounts) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | break; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 949 | p = p->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 950 | } |
| 951 | } |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 952 | return list_entry(next, struct mount, mnt_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 953 | } |
| 954 | |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 955 | static struct mount *skip_mnt_tree(struct mount *p) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 956 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 957 | struct list_head *prev = p->mnt_mounts.prev; |
| 958 | while (prev != &p->mnt_mounts) { |
| 959 | p = list_entry(prev, struct mount, mnt_child); |
| 960 | prev = p->mnt_mounts.prev; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 961 | } |
| 962 | return p; |
| 963 | } |
| 964 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 965 | struct vfsmount * |
| 966 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
| 967 | { |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 968 | struct mount *mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 969 | struct dentry *root; |
| 970 | |
| 971 | if (!type) |
| 972 | return ERR_PTR(-ENODEV); |
| 973 | |
| 974 | mnt = alloc_vfsmnt(name); |
| 975 | if (!mnt) |
| 976 | return ERR_PTR(-ENOMEM); |
| 977 | |
| 978 | if (flags & MS_KERNMOUNT) |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 979 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 980 | |
| 981 | root = mount_fs(type, flags, name, data); |
| 982 | if (IS_ERR(root)) { |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 983 | mnt_free_id(mnt); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 984 | free_vfsmnt(mnt); |
| 985 | return ERR_CAST(root); |
| 986 | } |
| 987 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 988 | mnt->mnt.mnt_root = root; |
| 989 | mnt->mnt.mnt_sb = root->d_sb; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 990 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 991 | mnt->mnt_parent = mnt; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 992 | lock_mount_hash(); |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 993 | list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 994 | unlock_mount_hash(); |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 995 | return &mnt->mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 996 | } |
| 997 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
| 998 | |
Eric W. Biederman | d3381fa | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 999 | struct vfsmount * |
| 1000 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, |
| 1001 | const char *name, void *data) |
| 1002 | { |
| 1003 | /* Until it is worked out how to pass the user namespace |
| 1004 | * through from the parent mount to the submount don't support |
| 1005 | * unprivileged mounts with submounts. |
| 1006 | */ |
| 1007 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) |
| 1008 | return ERR_PTR(-EPERM); |
| 1009 | |
| 1010 | return vfs_kern_mount(type, MS_SUBMOUNT, name, data); |
| 1011 | } |
| 1012 | EXPORT_SYMBOL_GPL(vfs_submount); |
| 1013 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1014 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1015 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1016 | { |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1017 | struct super_block *sb = old->mnt.mnt_sb; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1018 | struct mount *mnt; |
| 1019 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1020 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1021 | mnt = alloc_vfsmnt(old->mnt_devname); |
| 1022 | if (!mnt) |
| 1023 | return ERR_PTR(-ENOMEM); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1024 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1025 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1026 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 1027 | else |
| 1028 | mnt->mnt_group_id = old->mnt_group_id; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1029 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1030 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 1031 | err = mnt_alloc_group_id(mnt); |
| 1032 | if (err) |
| 1033 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1034 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1035 | |
Al Viro | 3f68e22e | 2018-04-19 22:03:08 -0400 | [diff] [blame] | 1036 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
| 1037 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); |
Eric W. Biederman | 132c94e | 2013-03-22 04:08:05 -0700 | [diff] [blame] | 1038 | /* Don't allow unprivileged users to change mount flags */ |
Eric W. Biederman | 9566d67 | 2014-07-28 17:26:07 -0700 | [diff] [blame] | 1039 | if (flag & CL_UNPRIVILEGED) { |
| 1040 | mnt->mnt.mnt_flags |= MNT_LOCK_ATIME; |
| 1041 | |
| 1042 | if (mnt->mnt.mnt_flags & MNT_READONLY) |
| 1043 | mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; |
| 1044 | |
| 1045 | if (mnt->mnt.mnt_flags & MNT_NODEV) |
| 1046 | mnt->mnt.mnt_flags |= MNT_LOCK_NODEV; |
| 1047 | |
| 1048 | if (mnt->mnt.mnt_flags & MNT_NOSUID) |
| 1049 | mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID; |
| 1050 | |
| 1051 | if (mnt->mnt.mnt_flags & MNT_NOEXEC) |
| 1052 | mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC; |
| 1053 | } |
Eric W. Biederman | 132c94e | 2013-03-22 04:08:05 -0700 | [diff] [blame] | 1054 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 1055 | /* Don't allow unprivileged users to reveal what is under a mount */ |
Eric W. Biederman | 381cacb | 2014-10-07 17:11:46 -0700 | [diff] [blame] | 1056 | if ((flag & CL_UNPRIVILEGED) && |
| 1057 | (!(flag & CL_EXPIRE) || list_empty(&old->mnt_expire))) |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 1058 | mnt->mnt.mnt_flags |= MNT_LOCKED; |
| 1059 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1060 | atomic_inc(&sb->s_active); |
| 1061 | mnt->mnt.mnt_sb = sb; |
| 1062 | mnt->mnt.mnt_root = dget(root); |
| 1063 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 1064 | mnt->mnt_parent = mnt; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1065 | lock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1066 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1067 | unlock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1068 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1069 | if ((flag & CL_SLAVE) || |
| 1070 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1071 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 1072 | mnt->mnt_master = old; |
| 1073 | CLEAR_MNT_SHARED(mnt); |
| 1074 | } else if (!(flag & CL_PRIVATE)) { |
| 1075 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
| 1076 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 1077 | if (IS_MNT_SLAVE(old)) |
| 1078 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 1079 | mnt->mnt_master = old->mnt_master; |
| 1080 | } |
| 1081 | if (flag & CL_MAKE_SHARED) |
| 1082 | set_mnt_shared(mnt); |
| 1083 | |
| 1084 | /* stick the duplicate mount on the same expiry list |
| 1085 | * as the original if that was on one */ |
| 1086 | if (flag & CL_EXPIRE) { |
| 1087 | if (!list_empty(&old->mnt_expire)) |
| 1088 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 1089 | } |
| 1090 | |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1091 | return mnt; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1092 | |
| 1093 | out_free: |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 1094 | mnt_free_id(mnt); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1095 | free_vfsmnt(mnt); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1096 | return ERR_PTR(err); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1097 | } |
| 1098 | |
Al Viro | 9ea459e | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1099 | static void cleanup_mnt(struct mount *mnt) |
| 1100 | { |
| 1101 | /* |
| 1102 | * This probably indicates that somebody messed |
| 1103 | * up a mnt_want/drop_write() pair. If this |
| 1104 | * happens, the filesystem was probably unable |
| 1105 | * to make r/w->r/o transitions. |
| 1106 | */ |
| 1107 | /* |
| 1108 | * The locking used to deal with mnt_count decrement provides barriers, |
| 1109 | * so mnt_get_writers() below is safe. |
| 1110 | */ |
| 1111 | WARN_ON(mnt_get_writers(mnt)); |
| 1112 | if (unlikely(mnt->mnt_pins.first)) |
| 1113 | mnt_pin_kill(mnt); |
| 1114 | fsnotify_vfsmount_delete(&mnt->mnt); |
| 1115 | dput(mnt->mnt.mnt_root); |
| 1116 | deactivate_super(mnt->mnt.mnt_sb); |
| 1117 | mnt_free_id(mnt); |
| 1118 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); |
| 1119 | } |
| 1120 | |
| 1121 | static void __cleanup_mnt(struct rcu_head *head) |
| 1122 | { |
| 1123 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); |
| 1124 | } |
| 1125 | |
| 1126 | static LLIST_HEAD(delayed_mntput_list); |
| 1127 | static void delayed_mntput(struct work_struct *unused) |
| 1128 | { |
| 1129 | struct llist_node *node = llist_del_all(&delayed_mntput_list); |
| 1130 | struct llist_node *next; |
| 1131 | |
| 1132 | for (; node; node = next) { |
| 1133 | next = llist_next(node); |
| 1134 | cleanup_mnt(llist_entry(node, struct mount, mnt_llist)); |
| 1135 | } |
| 1136 | } |
| 1137 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); |
| 1138 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1139 | static void mntput_no_expire(struct mount *mnt) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1140 | { |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1141 | rcu_read_lock(); |
| 1142 | mnt_add_count(mnt, -1); |
| 1143 | if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */ |
| 1144 | rcu_read_unlock(); |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 1145 | return; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1146 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1147 | lock_mount_hash(); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1148 | if (mnt_get_count(mnt)) { |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1149 | rcu_read_unlock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1150 | unlock_mount_hash(); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1151 | return; |
| 1152 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1153 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
| 1154 | rcu_read_unlock(); |
| 1155 | unlock_mount_hash(); |
| 1156 | return; |
| 1157 | } |
| 1158 | mnt->mnt.mnt_flags |= MNT_DOOMED; |
| 1159 | rcu_read_unlock(); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1160 | |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 1161 | list_del(&mnt->mnt_instance); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1162 | |
| 1163 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { |
| 1164 | struct mount *p, *tmp; |
| 1165 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { |
| 1166 | umount_mnt(p); |
| 1167 | } |
| 1168 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1169 | unlock_mount_hash(); |
Al Viro | 649a795 | 2013-09-28 12:41:25 -0400 | [diff] [blame] | 1170 | |
Al Viro | 9ea459e | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1171 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
| 1172 | struct task_struct *task = current; |
| 1173 | if (likely(!(task->flags & PF_KTHREAD))) { |
| 1174 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); |
| 1175 | if (!task_work_add(task, &mnt->mnt_rcu, true)) |
| 1176 | return; |
| 1177 | } |
| 1178 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) |
| 1179 | schedule_delayed_work(&delayed_mntput_work, 1); |
| 1180 | return; |
| 1181 | } |
| 1182 | cleanup_mnt(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1183 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1184 | |
| 1185 | void mntput(struct vfsmount *mnt) |
| 1186 | { |
| 1187 | if (mnt) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1188 | struct mount *m = real_mount(mnt); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1189 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1190 | if (unlikely(m->mnt_expiry_mark)) |
| 1191 | m->mnt_expiry_mark = 0; |
| 1192 | mntput_no_expire(m); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1193 | } |
| 1194 | } |
| 1195 | EXPORT_SYMBOL(mntput); |
| 1196 | |
| 1197 | struct vfsmount *mntget(struct vfsmount *mnt) |
| 1198 | { |
| 1199 | if (mnt) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1200 | mnt_add_count(real_mount(mnt), 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1201 | return mnt; |
| 1202 | } |
| 1203 | EXPORT_SYMBOL(mntget); |
| 1204 | |
Al Viro | 3064c35 | 2014-08-07 09:12:31 -0400 | [diff] [blame] | 1205 | struct vfsmount *mnt_clone_internal(struct path *path) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1206 | { |
Al Viro | 3064c35 | 2014-08-07 09:12:31 -0400 | [diff] [blame] | 1207 | struct mount *p; |
| 1208 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); |
| 1209 | if (IS_ERR(p)) |
| 1210 | return ERR_CAST(p); |
| 1211 | p->mnt.mnt_flags |= MNT_INTERNAL; |
| 1212 | return &p->mnt; |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1213 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1214 | |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 1215 | static inline void mangle(struct seq_file *m, const char *s) |
| 1216 | { |
| 1217 | seq_escape(m, s, " \t\n\\"); |
| 1218 | } |
| 1219 | |
| 1220 | /* |
| 1221 | * Simple .show_options callback for filesystems which don't want to |
| 1222 | * implement more complex mount option showing. |
| 1223 | * |
| 1224 | * See also save_mount_options(). |
| 1225 | */ |
Al Viro | 34c80b1 | 2011-12-08 21:32:45 -0500 | [diff] [blame] | 1226 | int generic_show_options(struct seq_file *m, struct dentry *root) |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 1227 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 1228 | const char *options; |
| 1229 | |
| 1230 | rcu_read_lock(); |
Al Viro | 34c80b1 | 2011-12-08 21:32:45 -0500 | [diff] [blame] | 1231 | options = rcu_dereference(root->d_sb->s_options); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 1232 | |
| 1233 | if (options != NULL && options[0]) { |
| 1234 | seq_putc(m, ','); |
| 1235 | mangle(m, options); |
| 1236 | } |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 1237 | rcu_read_unlock(); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 1238 | |
| 1239 | return 0; |
| 1240 | } |
| 1241 | EXPORT_SYMBOL(generic_show_options); |
| 1242 | |
| 1243 | /* |
| 1244 | * If filesystem uses generic_show_options(), this function should be |
| 1245 | * called from the fill_super() callback. |
| 1246 | * |
| 1247 | * The .remount_fs callback usually needs to be handled in a special |
| 1248 | * way, to make sure, that previous options are not overwritten if the |
| 1249 | * remount fails. |
| 1250 | * |
| 1251 | * Also note, that if the filesystem's .remount_fs function doesn't |
| 1252 | * reset all options to their default value, but changes only newly |
| 1253 | * given options, then the displayed options will not reflect reality |
| 1254 | * any more. |
| 1255 | */ |
| 1256 | void save_mount_options(struct super_block *sb, char *options) |
| 1257 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 1258 | BUG_ON(sb->s_options); |
| 1259 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 1260 | } |
| 1261 | EXPORT_SYMBOL(save_mount_options); |
| 1262 | |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 1263 | void replace_mount_options(struct super_block *sb, char *options) |
| 1264 | { |
| 1265 | char *old = sb->s_options; |
| 1266 | rcu_assign_pointer(sb->s_options, options); |
| 1267 | if (old) { |
| 1268 | synchronize_rcu(); |
| 1269 | kfree(old); |
| 1270 | } |
| 1271 | } |
| 1272 | EXPORT_SYMBOL(replace_mount_options); |
| 1273 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1274 | #ifdef CONFIG_PROC_FS |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1275 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1276 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 1277 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1278 | struct proc_mounts *p = m->private; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1279 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1280 | down_read(&namespace_sem); |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 1281 | if (p->cached_event == p->ns->event) { |
| 1282 | void *v = p->cached_mount; |
| 1283 | if (*pos == p->cached_index) |
| 1284 | return v; |
| 1285 | if (*pos == p->cached_index + 1) { |
| 1286 | v = seq_list_next(v, &p->ns->list, &p->cached_index); |
| 1287 | return p->cached_mount = v; |
| 1288 | } |
| 1289 | } |
| 1290 | |
| 1291 | p->cached_event = p->ns->event; |
| 1292 | p->cached_mount = seq_list_start(&p->ns->list, *pos); |
| 1293 | p->cached_index = *pos; |
| 1294 | return p->cached_mount; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1295 | } |
| 1296 | |
| 1297 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 1298 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1299 | struct proc_mounts *p = m->private; |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 1300 | |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 1301 | p->cached_mount = seq_list_next(v, &p->ns->list, pos); |
| 1302 | p->cached_index = *pos; |
| 1303 | return p->cached_mount; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1304 | } |
| 1305 | |
| 1306 | static void m_stop(struct seq_file *m, void *v) |
| 1307 | { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1308 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1309 | } |
| 1310 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1311 | static int m_show(struct seq_file *m, void *v) |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 1312 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1313 | struct proc_mounts *p = m->private; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1314 | struct mount *r = list_entry(v, struct mount, mnt_list); |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1315 | return p->show(m, &r->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1316 | } |
| 1317 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1318 | const struct seq_operations mounts_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1319 | .start = m_start, |
| 1320 | .next = m_next, |
| 1321 | .stop = m_stop, |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1322 | .show = m_show, |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1323 | }; |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1324 | #endif /* CONFIG_PROC_FS */ |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1325 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1326 | /** |
| 1327 | * may_umount_tree - check if a mount tree is busy |
| 1328 | * @mnt: root of mount tree |
| 1329 | * |
| 1330 | * This is called to check if a tree of mounts has any |
| 1331 | * open files, pwds, chroots or sub mounts that are |
| 1332 | * busy. |
| 1333 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1334 | int may_umount_tree(struct vfsmount *m) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1335 | { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1336 | struct mount *mnt = real_mount(m); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1337 | int actual_refs = 0; |
| 1338 | int minimum_refs = 0; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1339 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1340 | BUG_ON(!m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1341 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1342 | /* write lock needed for mnt_get_count */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1343 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1344 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1345 | actual_refs += mnt_get_count(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1346 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1347 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1348 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1349 | |
| 1350 | if (actual_refs > minimum_refs) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1351 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1353 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1354 | } |
| 1355 | |
| 1356 | EXPORT_SYMBOL(may_umount_tree); |
| 1357 | |
| 1358 | /** |
| 1359 | * may_umount - check if a mount point is busy |
| 1360 | * @mnt: root of mount |
| 1361 | * |
| 1362 | * This is called to check if a mount point has any |
| 1363 | * open files, pwds, chroots or sub mounts. If the |
| 1364 | * mount has sub mounts this will return busy |
| 1365 | * regardless of whether the sub mounts are busy. |
| 1366 | * |
| 1367 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 1368 | * give false negatives. The main reason why it's here is that we need |
| 1369 | * a non-destructive way to look for easily umountable filesystems. |
| 1370 | */ |
| 1371 | int may_umount(struct vfsmount *mnt) |
| 1372 | { |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1373 | int ret = 1; |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1374 | down_read(&namespace_sem); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1375 | lock_mount_hash(); |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1376 | if (propagate_mount_busy(real_mount(mnt), 2)) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1377 | ret = 0; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1378 | unlock_mount_hash(); |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1379 | up_read(&namespace_sem); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1380 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1381 | } |
| 1382 | |
| 1383 | EXPORT_SYMBOL(may_umount); |
| 1384 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1385 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1386 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1387 | static void namespace_unlock(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1388 | { |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1389 | struct hlist_head head; |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1390 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1391 | hlist_move_list(&unmounted, &head); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1392 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1393 | up_write(&namespace_sem); |
| 1394 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1395 | if (likely(hlist_empty(&head))) |
| 1396 | return; |
| 1397 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1398 | synchronize_rcu(); |
| 1399 | |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 1400 | group_pin_kill(&head); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1401 | } |
| 1402 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1403 | static inline void namespace_lock(void) |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1404 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1405 | down_write(&namespace_sem); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1406 | } |
| 1407 | |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1408 | enum umount_tree_flags { |
| 1409 | UMOUNT_SYNC = 1, |
| 1410 | UMOUNT_PROPAGATE = 2, |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1411 | UMOUNT_CONNECTED = 4, |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1412 | }; |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1413 | |
| 1414 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) |
| 1415 | { |
| 1416 | /* Leaving mounts connected is only valid for lazy umounts */ |
| 1417 | if (how & UMOUNT_SYNC) |
| 1418 | return true; |
| 1419 | |
| 1420 | /* A mount without a parent has nothing to be connected to */ |
| 1421 | if (!mnt_has_parent(mnt)) |
| 1422 | return true; |
| 1423 | |
| 1424 | /* Because the reference counting rules change when mounts are |
| 1425 | * unmounted and connected, umounted mounts may not be |
| 1426 | * connected to mounted mounts. |
| 1427 | */ |
| 1428 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) |
| 1429 | return true; |
| 1430 | |
| 1431 | /* Has it been requested that the mount remain connected? */ |
| 1432 | if (how & UMOUNT_CONNECTED) |
| 1433 | return false; |
| 1434 | |
| 1435 | /* Is the mount locked such that it needs to remain connected? */ |
| 1436 | if (IS_MNT_LOCKED(mnt)) |
| 1437 | return false; |
| 1438 | |
| 1439 | /* By default disconnect the mount */ |
| 1440 | return true; |
| 1441 | } |
| 1442 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1443 | /* |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1444 | * mount_lock must be held |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1445 | * namespace_sem must be held for write |
| 1446 | */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1447 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1448 | { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1449 | LIST_HEAD(tmp_list); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1450 | struct mount *p; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1451 | |
Eric W. Biederman | 5d88457 | 2015-01-03 05:39:35 -0600 | [diff] [blame] | 1452 | if (how & UMOUNT_PROPAGATE) |
| 1453 | propagate_mount_unlock(mnt); |
| 1454 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1455 | /* Gather the mounts to umount */ |
Eric W. Biederman | 590ce4b | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1456 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1457 | p->mnt.mnt_flags |= MNT_UMOUNT; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1458 | list_move(&p->mnt_list, &tmp_list); |
Eric W. Biederman | 590ce4b | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1459 | } |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1460 | |
Eric W. Biederman | 411a938b | 2014-12-22 19:12:07 -0600 | [diff] [blame] | 1461 | /* Hide the mounts from mnt_mounts */ |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1462 | list_for_each_entry(p, &tmp_list, mnt_list) { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1463 | list_del_init(&p->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1464 | } |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1465 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1466 | /* Add propogated mounts to the tmp_list */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1467 | if (how & UMOUNT_PROPAGATE) |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1468 | propagate_umount(&tmp_list); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1469 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1470 | while (!list_empty(&tmp_list)) { |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1471 | struct mnt_namespace *ns; |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1472 | bool disconnect; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1473 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1474 | list_del_init(&p->mnt_expire); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1475 | list_del_init(&p->mnt_list); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1476 | ns = p->mnt_ns; |
| 1477 | if (ns) { |
| 1478 | ns->mounts--; |
| 1479 | __touch_mnt_namespace(ns); |
| 1480 | } |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1481 | p->mnt_ns = NULL; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1482 | if (how & UMOUNT_SYNC) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1483 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 1484 | |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1485 | disconnect = disconnect_mount(p, how); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1486 | |
| 1487 | pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, |
| 1488 | disconnect ? &unmounted : NULL); |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1489 | if (mnt_has_parent(p)) { |
Al Viro | 81b6b06 | 2014-08-30 18:32:05 -0400 | [diff] [blame] | 1490 | mnt_add_count(p->mnt_parent, -1); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1491 | if (!disconnect) { |
| 1492 | /* Don't forget about p */ |
| 1493 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); |
| 1494 | } else { |
| 1495 | umount_mnt(p); |
| 1496 | } |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1497 | } |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1498 | change_mnt_propagation(p, MS_PRIVATE); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1499 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1500 | } |
| 1501 | |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 1502 | static void shrink_submounts(struct mount *mnt); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1503 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1504 | static int do_umount(struct mount *mnt, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1505 | { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1506 | struct super_block *sb = mnt->mnt.mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1507 | int retval; |
| 1508 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1509 | retval = security_sb_umount(&mnt->mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1510 | if (retval) |
| 1511 | return retval; |
| 1512 | |
| 1513 | /* |
| 1514 | * Allow userspace to request a mountpoint be expired rather than |
| 1515 | * unmounting unconditionally. Unmount only happens if: |
| 1516 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 1517 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 1518 | */ |
| 1519 | if (flags & MNT_EXPIRE) { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1520 | if (&mnt->mnt == current->fs->root.mnt || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1521 | flags & (MNT_FORCE | MNT_DETACH)) |
| 1522 | return -EINVAL; |
| 1523 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1524 | /* |
| 1525 | * probably don't strictly need the lock here if we examined |
| 1526 | * all race cases, but it's a slowpath. |
| 1527 | */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1528 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1529 | if (mnt_get_count(mnt) != 2) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1530 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1531 | return -EBUSY; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1532 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1533 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1534 | |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1535 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1536 | return -EAGAIN; |
| 1537 | } |
| 1538 | |
| 1539 | /* |
| 1540 | * If we may have to abort operations to get out of this |
| 1541 | * mount, and they will themselves hold resources we must |
| 1542 | * allow the fs to do things. In the Unix tradition of |
| 1543 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 1544 | * might fail to complete on the first run through as other tasks |
| 1545 | * must return, and the like. Thats for the mount program to worry |
| 1546 | * about for the moment. |
| 1547 | */ |
| 1548 | |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1549 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1550 | sb->s_op->umount_begin(sb); |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1551 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1552 | |
| 1553 | /* |
| 1554 | * No sense to grab the lock for this test, but test itself looks |
| 1555 | * somewhat bogus. Suggestions for better replacement? |
| 1556 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1557 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1558 | * Actually it makes sense, especially if rootfs would contain a |
| 1559 | * /reboot - static binary that would close all descriptors and |
| 1560 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1561 | */ |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1562 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1563 | /* |
| 1564 | * Special case for "unmounting" root ... |
| 1565 | * we just try to remount it readonly. |
| 1566 | */ |
Andy Lutomirski | a1480dc | 2014-10-08 12:32:47 -0700 | [diff] [blame] | 1567 | if (!capable(CAP_SYS_ADMIN)) |
| 1568 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1569 | down_write(&sb->s_umount); |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 1570 | if (!(sb->s_flags & MS_RDONLY)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1571 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1572 | up_write(&sb->s_umount); |
| 1573 | return retval; |
| 1574 | } |
| 1575 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1576 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1577 | lock_mount_hash(); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1578 | event++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1579 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1580 | if (flags & MNT_DETACH) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1581 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1582 | umount_tree(mnt, UMOUNT_PROPAGATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1583 | retval = 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1584 | } else { |
| 1585 | shrink_submounts(mnt); |
| 1586 | retval = -EBUSY; |
| 1587 | if (!propagate_mount_busy(mnt, 2)) { |
| 1588 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1589 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1590 | retval = 0; |
| 1591 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1592 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1593 | unlock_mount_hash(); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1594 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1595 | return retval; |
| 1596 | } |
| 1597 | |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1598 | /* |
| 1599 | * __detach_mounts - lazily unmount all mounts on the specified dentry |
| 1600 | * |
| 1601 | * During unlink, rmdir, and d_drop it is possible to loose the path |
| 1602 | * to an existing mountpoint, and wind up leaking the mount. |
| 1603 | * detach_mounts allows lazily unmounting those mounts instead of |
| 1604 | * leaking them. |
| 1605 | * |
| 1606 | * The caller may hold dentry->d_inode->i_mutex. |
| 1607 | */ |
| 1608 | void __detach_mounts(struct dentry *dentry) |
| 1609 | { |
| 1610 | struct mountpoint *mp; |
| 1611 | struct mount *mnt; |
| 1612 | |
| 1613 | namespace_lock(); |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1614 | lock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1615 | mp = lookup_mountpoint(dentry); |
Eric W. Biederman | f53e579 | 2015-01-19 11:48:45 -0600 | [diff] [blame] | 1616 | if (IS_ERR_OR_NULL(mp)) |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1617 | goto out_unlock; |
| 1618 | |
Andrey Ulanov | e06b933 | 2016-04-15 14:24:41 -0700 | [diff] [blame] | 1619 | event++; |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1620 | while (!hlist_empty(&mp->m_list)) { |
| 1621 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1622 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
Eric W. Biederman | fe78fcc | 2015-07-17 14:54:27 -0500 | [diff] [blame] | 1623 | hlist_add_head(&mnt->mnt_umount.s_list, &unmounted); |
| 1624 | umount_mnt(mnt); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1625 | } |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1626 | else umount_tree(mnt, UMOUNT_CONNECTED); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1627 | } |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1628 | put_mountpoint(mp); |
| 1629 | out_unlock: |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1630 | unlock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1631 | namespace_unlock(); |
| 1632 | } |
| 1633 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1634 | /* |
| 1635 | * Is the caller allowed to modify his namespace? |
| 1636 | */ |
| 1637 | static inline bool may_mount(void) |
| 1638 | { |
| 1639 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); |
| 1640 | } |
| 1641 | |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1642 | static inline bool may_mandlock(void) |
| 1643 | { |
| 1644 | #ifndef CONFIG_MANDATORY_FILE_LOCKING |
| 1645 | return false; |
| 1646 | #endif |
Eric W. Biederman | 95ace75 | 2015-11-11 17:22:33 -0600 | [diff] [blame] | 1647 | return capable(CAP_SYS_ADMIN); |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1648 | } |
| 1649 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1650 | /* |
| 1651 | * Now umount can handle mount points as well as block devices. |
| 1652 | * This is important for filesystems which use unnamed block devices. |
| 1653 | * |
| 1654 | * We now support a flag for forced unmount like the other 'big iron' |
| 1655 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 1656 | */ |
| 1657 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1658 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1660 | struct path path; |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1661 | struct mount *mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1662 | int retval; |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1663 | int lookup_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1664 | |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1665 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
| 1666 | return -EINVAL; |
| 1667 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1668 | if (!may_mount()) |
| 1669 | return -EPERM; |
| 1670 | |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1671 | if (!(flags & UMOUNT_NOFOLLOW)) |
| 1672 | lookup_flags |= LOOKUP_FOLLOW; |
| 1673 | |
Al Viro | 197df04 | 2013-09-08 14:03:27 -0400 | [diff] [blame] | 1674 | retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1675 | if (retval) |
| 1676 | goto out; |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1677 | mnt = real_mount(path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1678 | retval = -EINVAL; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1679 | if (path.dentry != path.mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1680 | goto dput_and_out; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1681 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1682 | goto dput_and_out; |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 1683 | if (mnt->mnt.mnt_flags & MNT_LOCKED) |
| 1684 | goto dput_and_out; |
Eric W. Biederman | b2f5d4d | 2014-10-04 14:44:03 -0700 | [diff] [blame] | 1685 | retval = -EPERM; |
| 1686 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
| 1687 | goto dput_and_out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1688 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1689 | retval = do_umount(mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1690 | dput_and_out: |
Jan Blunck | 429731b | 2008-02-14 19:34:31 -0800 | [diff] [blame] | 1691 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1692 | dput(path.dentry); |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1693 | mntput_no_expire(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1694 | out: |
| 1695 | return retval; |
| 1696 | } |
| 1697 | |
| 1698 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1699 | |
| 1700 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1701 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1702 | */ |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1703 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1704 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1705 | return sys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1706 | } |
| 1707 | |
| 1708 | #endif |
| 1709 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1710 | static bool is_mnt_ns_file(struct dentry *dentry) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1711 | { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1712 | /* Is this a proxy for a mount namespace? */ |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 1713 | return dentry->d_op == &ns_dentry_operations && |
| 1714 | dentry->d_fsdata == &mntns_operations; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1715 | } |
| 1716 | |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 1717 | struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
| 1718 | { |
| 1719 | return container_of(ns, struct mnt_namespace, ns); |
| 1720 | } |
| 1721 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1722 | static bool mnt_ns_loop(struct dentry *dentry) |
| 1723 | { |
| 1724 | /* Could bind mounting the mount namespace inode cause a |
| 1725 | * mount namespace loop? |
| 1726 | */ |
| 1727 | struct mnt_namespace *mnt_ns; |
| 1728 | if (!is_mnt_ns_file(dentry)) |
| 1729 | return false; |
| 1730 | |
Al Viro | f77c801 | 2014-11-01 03:13:17 -0400 | [diff] [blame] | 1731 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1732 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
| 1733 | } |
| 1734 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1735 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1736 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1737 | { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1738 | struct mount *res, *p, *q, *r, *parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1739 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1740 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
| 1741 | return ERR_PTR(-EINVAL); |
| 1742 | |
| 1743 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1744 | return ERR_PTR(-EINVAL); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1745 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1746 | res = q = clone_mnt(mnt, dentry, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1747 | if (IS_ERR(q)) |
| 1748 | return q; |
| 1749 | |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1750 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1751 | |
| 1752 | p = mnt; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1753 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1754 | struct mount *s; |
Jan Blunck | 7ec02ef | 2008-04-29 00:59:40 -0700 | [diff] [blame] | 1755 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1756 | continue; |
| 1757 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1758 | for (s = r; s; s = next_mnt(s, r)) { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1759 | if (!(flag & CL_COPY_UNBINDABLE) && |
| 1760 | IS_MNT_UNBINDABLE(s)) { |
| 1761 | s = skip_mnt_tree(s); |
| 1762 | continue; |
| 1763 | } |
| 1764 | if (!(flag & CL_COPY_MNT_NS_FILE) && |
| 1765 | is_mnt_ns_file(s->mnt.mnt_root)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1766 | s = skip_mnt_tree(s); |
| 1767 | continue; |
| 1768 | } |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1769 | while (p != s->mnt_parent) { |
| 1770 | p = p->mnt_parent; |
| 1771 | q = q->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1772 | } |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1773 | p = s; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1774 | parent = q; |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1775 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1776 | if (IS_ERR(q)) |
| 1777 | goto out; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1778 | lock_mount_hash(); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1779 | list_add_tail(&q->mnt_list, &res->mnt_list); |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1780 | attach_mnt(q, parent, p->mnt_mp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1781 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1782 | } |
| 1783 | } |
| 1784 | return res; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1785 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1786 | if (res) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1787 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1788 | umount_tree(res, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1789 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1790 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1791 | return q; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1792 | } |
| 1793 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1794 | /* Caller should check returned pointer for errors */ |
| 1795 | |
Al Viro | 589ff87 | 2009-04-18 03:28:19 -0400 | [diff] [blame] | 1796 | struct vfsmount *collect_mounts(struct path *path) |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1797 | { |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1798 | struct mount *tree; |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1799 | namespace_lock(); |
Eric W. Biederman | cd4a401 | 2015-01-07 14:28:26 -0600 | [diff] [blame] | 1800 | if (!check_mnt(real_mount(path->mnt))) |
| 1801 | tree = ERR_PTR(-EINVAL); |
| 1802 | else |
| 1803 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
| 1804 | CL_COPY_ALL | CL_PRIVATE); |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 1805 | namespace_unlock(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1806 | if (IS_ERR(tree)) |
Dan Carpenter | 52e220d | 2013-08-14 12:44:39 +0300 | [diff] [blame] | 1807 | return ERR_CAST(tree); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1808 | return &tree->mnt; |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1809 | } |
| 1810 | |
| 1811 | void drop_collected_mounts(struct vfsmount *mnt) |
| 1812 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1813 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1814 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1815 | umount_tree(real_mount(mnt), UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1816 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 1817 | namespace_unlock(); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1818 | } |
| 1819 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1820 | /** |
| 1821 | * clone_private_mount - create a private clone of a path |
| 1822 | * |
| 1823 | * This creates a new vfsmount, which will be the clone of @path. The new will |
| 1824 | * not be attached anywhere in the namespace and will be private (i.e. changes |
| 1825 | * to the originating mount won't be propagated into this). |
| 1826 | * |
| 1827 | * Release with mntput(). |
| 1828 | */ |
| 1829 | struct vfsmount *clone_private_mount(struct path *path) |
| 1830 | { |
| 1831 | struct mount *old_mnt = real_mount(path->mnt); |
| 1832 | struct mount *new_mnt; |
| 1833 | |
| 1834 | if (IS_MNT_UNBINDABLE(old_mnt)) |
| 1835 | return ERR_PTR(-EINVAL); |
| 1836 | |
| 1837 | down_read(&namespace_sem); |
| 1838 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
| 1839 | up_read(&namespace_sem); |
| 1840 | if (IS_ERR(new_mnt)) |
| 1841 | return ERR_CAST(new_mnt); |
| 1842 | |
| 1843 | return &new_mnt->mnt; |
| 1844 | } |
| 1845 | EXPORT_SYMBOL_GPL(clone_private_mount); |
| 1846 | |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1847 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
| 1848 | struct vfsmount *root) |
| 1849 | { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1850 | struct mount *mnt; |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1851 | int res = f(root, arg); |
| 1852 | if (res) |
| 1853 | return res; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1854 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
| 1855 | res = f(&mnt->mnt, arg); |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1856 | if (res) |
| 1857 | return res; |
| 1858 | } |
| 1859 | return 0; |
| 1860 | } |
| 1861 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1862 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1863 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1864 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1865 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1866 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1867 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1868 | mnt_release_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1869 | } |
| 1870 | } |
| 1871 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1872 | static int invent_group_ids(struct mount *mnt, bool recurse) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1873 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1874 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1875 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1876 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1877 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1878 | int err = mnt_alloc_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1879 | if (err) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1880 | cleanup_group_ids(mnt, p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1881 | return err; |
| 1882 | } |
| 1883 | } |
| 1884 | } |
| 1885 | |
| 1886 | return 0; |
| 1887 | } |
| 1888 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1889 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
| 1890 | { |
| 1891 | unsigned int max = READ_ONCE(sysctl_mount_max); |
| 1892 | unsigned int mounts = 0, old, pending, sum; |
| 1893 | struct mount *p; |
| 1894 | |
| 1895 | for (p = mnt; p; p = next_mnt(p, mnt)) |
| 1896 | mounts++; |
| 1897 | |
| 1898 | old = ns->mounts; |
| 1899 | pending = ns->pending_mounts; |
| 1900 | sum = old + pending; |
| 1901 | if ((old > sum) || |
| 1902 | (pending > sum) || |
| 1903 | (max < sum) || |
| 1904 | (mounts > (max - sum))) |
| 1905 | return -ENOSPC; |
| 1906 | |
| 1907 | ns->pending_mounts = pending + mounts; |
| 1908 | return 0; |
| 1909 | } |
| 1910 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1911 | /* |
| 1912 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1913 | * @nd : place the mount tree @source_mnt is attached |
| 1914 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 1915 | * store the parent mount and mountpoint dentry. |
| 1916 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1917 | * |
| 1918 | * NOTE: in the table below explains the semantics when a source mount |
| 1919 | * of a given type is attached to a destination mount of a given type. |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1920 | * --------------------------------------------------------------------------- |
| 1921 | * | BIND MOUNT OPERATION | |
| 1922 | * |************************************************************************** |
| 1923 | * | source-->| shared | private | slave | unbindable | |
| 1924 | * | dest | | | | | |
| 1925 | * | | | | | | | |
| 1926 | * | v | | | | | |
| 1927 | * |************************************************************************** |
| 1928 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 1929 | * | | | | | | |
| 1930 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 1931 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1932 | * A bind operation clones the source mount and mounts the clone on the |
| 1933 | * destination mount. |
| 1934 | * |
| 1935 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 1936 | * tree of the destination mount and the cloned mount is added to |
| 1937 | * the peer group of the source mount. |
| 1938 | * (+) the cloned mount is created under the destination mount and is marked |
| 1939 | * as shared. The cloned mount is added to the peer group of the source |
| 1940 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1941 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 1942 | * of the destination mount and the cloned mount is made slave |
| 1943 | * of the same master as that of the source mount. The cloned mount |
| 1944 | * is marked as 'shared and slave'. |
| 1945 | * (*) the cloned mount is made a slave of the same master as that of the |
| 1946 | * source mount. |
| 1947 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1948 | * --------------------------------------------------------------------------- |
| 1949 | * | MOVE MOUNT OPERATION | |
| 1950 | * |************************************************************************** |
| 1951 | * | source-->| shared | private | slave | unbindable | |
| 1952 | * | dest | | | | | |
| 1953 | * | | | | | | | |
| 1954 | * | v | | | | | |
| 1955 | * |************************************************************************** |
| 1956 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 1957 | * | | | | | | |
| 1958 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 1959 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1960 | * |
| 1961 | * (+) the mount is moved to the destination. And is then propagated to |
| 1962 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1963 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1964 | * (+++) the mount is moved to the destination and is then propagated to |
| 1965 | * all the mounts belonging to the destination mount's propagation tree. |
| 1966 | * the mount is marked as 'shared and slave'. |
| 1967 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1968 | * |
| 1969 | * if the source mount is a tree, the operations explained above is |
| 1970 | * applied to each mount in the tree. |
| 1971 | * Must be called without spinlocks held, since this function can sleep |
| 1972 | * in allocations. |
| 1973 | */ |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1974 | static int attach_recursive_mnt(struct mount *source_mnt, |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1975 | struct mount *dest_mnt, |
| 1976 | struct mountpoint *dest_mp, |
| 1977 | struct path *parent_path) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1978 | { |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1979 | HLIST_HEAD(tree_list); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1980 | struct mnt_namespace *ns = dest_mnt->mnt_ns; |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1981 | struct mountpoint *smp; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1982 | struct mount *child, *p; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1983 | struct hlist_node *n; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1984 | int err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1985 | |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1986 | /* Preallocate a mountpoint in case the new mounts need |
| 1987 | * to be tucked under other mounts. |
| 1988 | */ |
| 1989 | smp = get_mountpoint(source_mnt->mnt.mnt_root); |
| 1990 | if (IS_ERR(smp)) |
| 1991 | return PTR_ERR(smp); |
| 1992 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1993 | /* Is there space to add these mounts to the mount namespace? */ |
| 1994 | if (!parent_path) { |
| 1995 | err = count_mounts(ns, source_mnt); |
| 1996 | if (err) |
| 1997 | goto out; |
| 1998 | } |
| 1999 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2000 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2001 | err = invent_group_ids(source_mnt, true); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2002 | if (err) |
| 2003 | goto out; |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2004 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2005 | lock_mount_hash(); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2006 | if (err) |
| 2007 | goto out_cleanup_ids; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2008 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2009 | set_mnt_shared(p); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2010 | } else { |
| 2011 | lock_mount_hash(); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2012 | } |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 2013 | if (parent_path) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2014 | detach_mnt(source_mnt, parent_path); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2015 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2016 | touch_mnt_namespace(source_mnt->mnt_ns); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2017 | } else { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2018 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2019 | commit_tree(source_mnt); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2020 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2021 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2022 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
Al Viro | 1d6a32a | 2014-03-20 20:34:43 -0400 | [diff] [blame] | 2023 | struct mount *q; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2024 | hlist_del_init(&child->mnt_hash); |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2025 | q = __lookup_mnt(&child->mnt_parent->mnt, |
| 2026 | child->mnt_mountpoint); |
| 2027 | if (q) |
| 2028 | mnt_change_mountpoint(child, smp, q); |
| 2029 | commit_tree(child); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2030 | } |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2031 | put_mountpoint(smp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2032 | unlock_mount_hash(); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2033 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2034 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2035 | |
| 2036 | out_cleanup_ids: |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2037 | while (!hlist_empty(&tree_list)) { |
| 2038 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2039 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2040 | umount_tree(child, UMOUNT_SYNC); |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2041 | } |
| 2042 | unlock_mount_hash(); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2043 | cleanup_group_ids(source_mnt, NULL); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2044 | out: |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2045 | ns->pending_mounts = 0; |
Eric W. Biederman | 808e83e | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2046 | |
| 2047 | read_seqlock_excl(&mount_lock); |
| 2048 | put_mountpoint(smp); |
| 2049 | read_sequnlock_excl(&mount_lock); |
| 2050 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2051 | return err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2052 | } |
| 2053 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2054 | static struct mountpoint *lock_mount(struct path *path) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2055 | { |
| 2056 | struct vfsmount *mnt; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2057 | struct dentry *dentry = path->dentry; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2058 | retry: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2059 | inode_lock(dentry->d_inode); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2060 | if (unlikely(cant_mount(dentry))) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2061 | inode_unlock(dentry->d_inode); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2062 | return ERR_PTR(-ENOENT); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2063 | } |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2064 | namespace_lock(); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2065 | mnt = lookup_mnt(path); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2066 | if (likely(!mnt)) { |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2067 | struct mountpoint *mp = get_mountpoint(dentry); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2068 | if (IS_ERR(mp)) { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2069 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2070 | inode_unlock(dentry->d_inode); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2071 | return mp; |
| 2072 | } |
| 2073 | return mp; |
| 2074 | } |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2075 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2076 | inode_unlock(path->dentry->d_inode); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2077 | path_put(path); |
| 2078 | path->mnt = mnt; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2079 | dentry = path->dentry = dget(mnt->mnt_root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2080 | goto retry; |
| 2081 | } |
| 2082 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2083 | static void unlock_mount(struct mountpoint *where) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2084 | { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2085 | struct dentry *dentry = where->m_dentry; |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2086 | |
| 2087 | read_seqlock_excl(&mount_lock); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2088 | put_mountpoint(where); |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2089 | read_sequnlock_excl(&mount_lock); |
| 2090 | |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2091 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2092 | inode_unlock(dentry->d_inode); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2093 | } |
| 2094 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2095 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2096 | { |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2097 | if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2098 | return -EINVAL; |
| 2099 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2100 | if (d_is_dir(mp->m_dentry) != |
| 2101 | d_is_dir(mnt->mnt.mnt_root)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2102 | return -ENOTDIR; |
| 2103 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2104 | return attach_recursive_mnt(mnt, p, mp, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2105 | } |
| 2106 | |
| 2107 | /* |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2108 | * Sanity check the flags to change_mnt_propagation. |
| 2109 | */ |
| 2110 | |
| 2111 | static int flags_to_propagation_type(int flags) |
| 2112 | { |
Roman Borisov | 7c6e984 | 2011-05-25 16:26:48 -0700 | [diff] [blame] | 2113 | int type = flags & ~(MS_REC | MS_SILENT); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2114 | |
| 2115 | /* Fail if any non-propagation flags are set */ |
| 2116 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 2117 | return 0; |
| 2118 | /* Only one propagation flag should be set */ |
| 2119 | if (!is_power_of_2(type)) |
| 2120 | return 0; |
| 2121 | return type; |
| 2122 | } |
| 2123 | |
| 2124 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2125 | * recursively change the type of the mountpoint. |
| 2126 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 2127 | static int do_change_type(struct path *path, int flag) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2128 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2129 | struct mount *m; |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2130 | struct mount *mnt = real_mount(path->mnt); |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2131 | int recurse = flag & MS_REC; |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2132 | int type; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2133 | int err = 0; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2134 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2135 | if (path->dentry != path->mnt->mnt_root) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2136 | return -EINVAL; |
| 2137 | |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2138 | type = flags_to_propagation_type(flag); |
| 2139 | if (!type) |
| 2140 | return -EINVAL; |
| 2141 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2142 | namespace_lock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2143 | if (type == MS_SHARED) { |
| 2144 | err = invent_group_ids(mnt, recurse); |
| 2145 | if (err) |
| 2146 | goto out_unlock; |
| 2147 | } |
| 2148 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2149 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2150 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2151 | change_mnt_propagation(m, type); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2152 | unlock_mount_hash(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2153 | |
| 2154 | out_unlock: |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2155 | namespace_unlock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2156 | return err; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2157 | } |
| 2158 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 2159 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
| 2160 | { |
| 2161 | struct mount *child; |
| 2162 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 2163 | if (!is_subdir(child->mnt_mountpoint, dentry)) |
| 2164 | continue; |
| 2165 | |
| 2166 | if (child->mnt.mnt_flags & MNT_LOCKED) |
| 2167 | return true; |
| 2168 | } |
| 2169 | return false; |
| 2170 | } |
| 2171 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2172 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2173 | * do loopback mount. |
| 2174 | */ |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2175 | static int do_loopback(struct path *path, const char *old_name, |
Eric Sandeen | 2dafe1c | 2008-02-08 04:22:12 -0800 | [diff] [blame] | 2176 | int recurse) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2177 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2178 | struct path old_path; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2179 | struct mount *mnt = NULL, *old, *parent; |
| 2180 | struct mountpoint *mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2181 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2182 | if (!old_name || !*old_name) |
| 2183 | return -EINVAL; |
Trond Myklebust | 815d405 | 2011-09-26 20:36:09 -0400 | [diff] [blame] | 2184 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2185 | if (err) |
| 2186 | return err; |
| 2187 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2188 | err = -EINVAL; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2189 | if (mnt_ns_loop(old_path.dentry)) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2190 | goto out; |
| 2191 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2192 | mp = lock_mount(path); |
| 2193 | err = PTR_ERR(mp); |
| 2194 | if (IS_ERR(mp)) |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2195 | goto out; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2196 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 2197 | old = real_mount(old_path.mnt); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2198 | parent = real_mount(path->mnt); |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 2199 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2200 | err = -EINVAL; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2201 | if (IS_MNT_UNBINDABLE(old)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2202 | goto out2; |
| 2203 | |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 2204 | if (!check_mnt(parent)) |
| 2205 | goto out2; |
| 2206 | |
| 2207 | if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2208 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2209 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 2210 | if (!recurse && has_locked_children(old, old_path.dentry)) |
| 2211 | goto out2; |
| 2212 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2213 | if (recurse) |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2214 | mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2215 | else |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 2216 | mnt = clone_mnt(old, old_path.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2217 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2218 | if (IS_ERR(mnt)) { |
| 2219 | err = PTR_ERR(mnt); |
Andrey Vagin | e9c5d8a | 2013-04-09 17:33:29 +0400 | [diff] [blame] | 2220 | goto out2; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2221 | } |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2222 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 2223 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 2224 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2225 | err = graft_tree(mnt, parent, mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2226 | if (err) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2227 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2228 | umount_tree(mnt, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2229 | unlock_mount_hash(); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 2230 | } |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2231 | out2: |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2232 | unlock_mount(mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2233 | out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2234 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2235 | return err; |
| 2236 | } |
| 2237 | |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2238 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
| 2239 | { |
| 2240 | int error = 0; |
| 2241 | int readonly_request = 0; |
| 2242 | |
| 2243 | if (ms_flags & MS_RDONLY) |
| 2244 | readonly_request = 1; |
| 2245 | if (readonly_request == __mnt_is_readonly(mnt)) |
| 2246 | return 0; |
| 2247 | |
| 2248 | if (readonly_request) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 2249 | error = mnt_make_readonly(real_mount(mnt)); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2250 | else |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 2251 | __mnt_unmake_readonly(real_mount(mnt)); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2252 | return error; |
| 2253 | } |
| 2254 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2255 | /* |
| 2256 | * change filesystem flags. dir should be a physical root of filesystem. |
| 2257 | * If you've mounted a non-root directory somewhere and want to do remount |
| 2258 | * on it - tough luck. |
| 2259 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 2260 | static int do_remount(struct path *path, int flags, int mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2261 | void *data) |
| 2262 | { |
| 2263 | int err; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2264 | struct super_block *sb = path->mnt->mnt_sb; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2265 | struct mount *mnt = real_mount(path->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2266 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2267 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2268 | return -EINVAL; |
| 2269 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2270 | if (path->dentry != path->mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2271 | return -EINVAL; |
| 2272 | |
Eric W. Biederman | 07b6455 | 2014-07-28 17:10:56 -0700 | [diff] [blame] | 2273 | /* Don't allow changing of locked mnt flags. |
| 2274 | * |
| 2275 | * No locks need to be held here while testing the various |
| 2276 | * MNT_LOCK flags because those flags can never be cleared |
| 2277 | * once they are set. |
| 2278 | */ |
| 2279 | if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && |
| 2280 | !(mnt_flags & MNT_READONLY)) { |
| 2281 | return -EPERM; |
| 2282 | } |
Eric W. Biederman | 9566d67 | 2014-07-28 17:26:07 -0700 | [diff] [blame] | 2283 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && |
| 2284 | !(mnt_flags & MNT_NODEV)) { |
Eric W. Biederman | 67690f9 | 2016-05-18 13:50:06 -0500 | [diff] [blame] | 2285 | return -EPERM; |
Eric W. Biederman | 9566d67 | 2014-07-28 17:26:07 -0700 | [diff] [blame] | 2286 | } |
| 2287 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && |
| 2288 | !(mnt_flags & MNT_NOSUID)) { |
| 2289 | return -EPERM; |
| 2290 | } |
| 2291 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) && |
| 2292 | !(mnt_flags & MNT_NOEXEC)) { |
| 2293 | return -EPERM; |
| 2294 | } |
| 2295 | if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && |
| 2296 | ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) { |
| 2297 | return -EPERM; |
| 2298 | } |
| 2299 | |
Eric Paris | ff36fe2 | 2011-03-03 16:09:14 -0500 | [diff] [blame] | 2300 | err = security_sb_remount(sb, data); |
| 2301 | if (err) |
| 2302 | return err; |
| 2303 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2304 | down_write(&sb->s_umount); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2305 | if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2306 | err = change_mount_flags(path->mnt, flags); |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2307 | else if (!capable(CAP_SYS_ADMIN)) |
| 2308 | err = -EPERM; |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 2309 | else |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2310 | err = do_remount_sb(sb, flags, data, 0); |
Al Viro | 7b43a79 | 2010-01-16 13:01:26 -0500 | [diff] [blame] | 2311 | if (!err) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2312 | lock_mount_hash(); |
Eric W. Biederman | a6138db | 2014-07-28 16:26:53 -0700 | [diff] [blame] | 2313 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2314 | mnt->mnt.mnt_flags = mnt_flags; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2315 | touch_mnt_namespace(mnt->mnt_ns); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2316 | unlock_mount_hash(); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 2317 | } |
Al Viro | 6339dab | 2013-09-16 22:41:01 -0400 | [diff] [blame] | 2318 | up_write(&sb->s_umount); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2319 | return err; |
| 2320 | } |
| 2321 | |
Al Viro | cbbe362 | 2011-11-24 20:01:19 -0500 | [diff] [blame] | 2322 | static inline int tree_contains_unbindable(struct mount *mnt) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2323 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2324 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2325 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2326 | if (IS_MNT_UNBINDABLE(p)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2327 | return 1; |
| 2328 | } |
| 2329 | return 0; |
| 2330 | } |
| 2331 | |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2332 | static int do_move_mount(struct path *path, const char *old_name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2333 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2334 | struct path old_path, parent_path; |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2335 | struct mount *p; |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2336 | struct mount *old; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2337 | struct mountpoint *mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2338 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2339 | if (!old_name || !*old_name) |
| 2340 | return -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2341 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2342 | if (err) |
| 2343 | return err; |
| 2344 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2345 | mp = lock_mount(path); |
| 2346 | err = PTR_ERR(mp); |
| 2347 | if (IS_ERR(mp)) |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 2348 | goto out; |
| 2349 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2350 | old = real_mount(old_path.mnt); |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2351 | p = real_mount(path->mnt); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2352 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2353 | err = -EINVAL; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2354 | if (!check_mnt(p) || !check_mnt(old)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2355 | goto out1; |
| 2356 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 2357 | if (old->mnt.mnt_flags & MNT_LOCKED) |
| 2358 | goto out1; |
| 2359 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2360 | err = -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2361 | if (old_path.dentry != old_path.mnt->mnt_root) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2362 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2363 | |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2364 | if (!mnt_has_parent(old)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2365 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2366 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2367 | if (d_is_dir(path->dentry) != |
| 2368 | d_is_dir(old_path.dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2369 | goto out1; |
| 2370 | /* |
| 2371 | * Don't move a mount residing in a shared parent. |
| 2372 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2373 | if (IS_MNT_SHARED(old->mnt_parent)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2374 | goto out1; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2375 | /* |
| 2376 | * Don't move a mount tree containing unbindable mounts to a destination |
| 2377 | * mount which is shared. |
| 2378 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2379 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2380 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2381 | err = -ELOOP; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2382 | for (; mnt_has_parent(p); p = p->mnt_parent) |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2383 | if (p == old) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2384 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2385 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2386 | err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2387 | if (err) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2388 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2389 | |
| 2390 | /* if the mount is moved, it should no longer be expire |
| 2391 | * automatically */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2392 | list_del_init(&old->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2393 | out1: |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2394 | unlock_mount(mp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2395 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2396 | if (!err) |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 2397 | path_put(&parent_path); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2398 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2399 | return err; |
| 2400 | } |
| 2401 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2402 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
| 2403 | { |
| 2404 | int err; |
| 2405 | const char *subtype = strchr(fstype, '.'); |
| 2406 | if (subtype) { |
| 2407 | subtype++; |
| 2408 | err = -EINVAL; |
| 2409 | if (!subtype[0]) |
| 2410 | goto err; |
| 2411 | } else |
| 2412 | subtype = ""; |
| 2413 | |
| 2414 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); |
| 2415 | err = -ENOMEM; |
| 2416 | if (!mnt->mnt_sb->s_subtype) |
| 2417 | goto err; |
| 2418 | return mnt; |
| 2419 | |
| 2420 | err: |
| 2421 | mntput(mnt); |
| 2422 | return ERR_PTR(err); |
| 2423 | } |
| 2424 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2425 | /* |
| 2426 | * add a mount into a namespace's mount tree |
| 2427 | */ |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2428 | static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2429 | { |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2430 | struct mountpoint *mp; |
| 2431 | struct mount *parent; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2432 | int err; |
| 2433 | |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2434 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2435 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2436 | mp = lock_mount(path); |
| 2437 | if (IS_ERR(mp)) |
| 2438 | return PTR_ERR(mp); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2439 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2440 | parent = real_mount(path->mnt); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2441 | err = -EINVAL; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2442 | if (unlikely(!check_mnt(parent))) { |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 2443 | /* that's acceptable only for automounts done in private ns */ |
| 2444 | if (!(mnt_flags & MNT_SHRINKABLE)) |
| 2445 | goto unlock; |
| 2446 | /* ... and for those we'd better have mountpoint still alive */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2447 | if (!parent->mnt_ns) |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 2448 | goto unlock; |
| 2449 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2450 | |
| 2451 | /* Refuse the same filesystem on the same mount point */ |
| 2452 | err = -EBUSY; |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2453 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2454 | path->mnt->mnt_root == path->dentry) |
| 2455 | goto unlock; |
| 2456 | |
| 2457 | err = -EINVAL; |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2458 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2459 | goto unlock; |
| 2460 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2461 | newmnt->mnt.mnt_flags = mnt_flags; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2462 | err = graft_tree(newmnt, parent, mp); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2463 | |
| 2464 | unlock: |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2465 | unlock_mount(mp); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2466 | return err; |
| 2467 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2468 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 2469 | static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags); |
Eric W. Biederman | 1b852bc | 2015-05-08 23:22:29 -0500 | [diff] [blame] | 2470 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2471 | /* |
| 2472 | * create a new mount for userspace and request it to be added into the |
| 2473 | * namespace's tree |
| 2474 | */ |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2475 | static int do_new_mount(struct path *path, const char *fstype, int flags, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2476 | int mnt_flags, const char *name, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2477 | { |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2478 | struct file_system_type *type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2479 | struct vfsmount *mnt; |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 2480 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2481 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2482 | if (!fstype) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2483 | return -EINVAL; |
| 2484 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2485 | type = get_fs_type(fstype); |
| 2486 | if (!type) |
| 2487 | return -ENODEV; |
| 2488 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2489 | mnt = vfs_kern_mount(type, flags, name, data); |
| 2490 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
| 2491 | !mnt->mnt_sb->s_subtype) |
| 2492 | mnt = fs_set_subtype(mnt, fstype); |
| 2493 | |
| 2494 | put_filesystem(type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2495 | if (IS_ERR(mnt)) |
| 2496 | return PTR_ERR(mnt); |
| 2497 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 2498 | if (mount_too_revealing(mnt, &mnt_flags)) { |
| 2499 | mntput(mnt); |
| 2500 | return -EPERM; |
| 2501 | } |
| 2502 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2503 | err = do_add_mount(real_mount(mnt), path, mnt_flags); |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 2504 | if (err) |
| 2505 | mntput(mnt); |
| 2506 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2507 | } |
| 2508 | |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2509 | int finish_automount(struct vfsmount *m, struct path *path) |
| 2510 | { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2511 | struct mount *mnt = real_mount(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2512 | int err; |
| 2513 | /* The new mount record should have at least 2 refs to prevent it being |
| 2514 | * expired before we get a chance to add it |
| 2515 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2516 | BUG_ON(mnt_get_count(mnt) < 2); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2517 | |
| 2518 | if (m->mnt_sb == path->mnt->mnt_sb && |
| 2519 | m->mnt_root == path->dentry) { |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2520 | err = -ELOOP; |
| 2521 | goto fail; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2522 | } |
| 2523 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2524 | err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2525 | if (!err) |
| 2526 | return 0; |
| 2527 | fail: |
| 2528 | /* remove m from any expiration list it may be on */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2529 | if (!list_empty(&mnt->mnt_expire)) { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2530 | namespace_lock(); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2531 | list_del_init(&mnt->mnt_expire); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2532 | namespace_unlock(); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2533 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2534 | mntput(m); |
| 2535 | mntput(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2536 | return err; |
| 2537 | } |
| 2538 | |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2539 | /** |
| 2540 | * mnt_set_expiry - Put a mount on an expiration list |
| 2541 | * @mnt: The mount to list. |
| 2542 | * @expiry_list: The list to add the mount to. |
| 2543 | */ |
| 2544 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) |
| 2545 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2546 | namespace_lock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2547 | |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2548 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2549 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2550 | namespace_unlock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2551 | } |
| 2552 | EXPORT_SYMBOL(mnt_set_expiry); |
| 2553 | |
| 2554 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2555 | * process a list of expirable mountpoints with the intent of discarding any |
| 2556 | * mountpoints that aren't in use and haven't been touched since last we came |
| 2557 | * here |
| 2558 | */ |
| 2559 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 2560 | { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2561 | struct mount *mnt, *next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2562 | LIST_HEAD(graveyard); |
| 2563 | |
| 2564 | if (list_empty(mounts)) |
| 2565 | return; |
| 2566 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2567 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2568 | lock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2569 | |
| 2570 | /* extract from the expiration list every vfsmount that matches the |
| 2571 | * following criteria: |
| 2572 | * - only referenced by its parent vfsmount |
| 2573 | * - still marked for expiry (marked on the last call here; marks are |
| 2574 | * cleared by mntput()) |
| 2575 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2576 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 2577 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 2578 | propagate_mount_busy(mnt, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2579 | continue; |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2580 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2581 | } |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2582 | while (!list_empty(&graveyard)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2583 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2584 | touch_mnt_namespace(mnt->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2585 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2586 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2587 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 2588 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2589 | } |
| 2590 | |
| 2591 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 2592 | |
| 2593 | /* |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2594 | * Ripoff of 'select_parent()' |
| 2595 | * |
| 2596 | * search the list of submounts for a given mountpoint, and move any |
| 2597 | * shrinkable submounts to the 'graveyard' list. |
| 2598 | */ |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2599 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2600 | { |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2601 | struct mount *this_parent = parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2602 | struct list_head *next; |
| 2603 | int found = 0; |
| 2604 | |
| 2605 | repeat: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2606 | next = this_parent->mnt_mounts.next; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2607 | resume: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2608 | while (next != &this_parent->mnt_mounts) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2609 | struct list_head *tmp = next; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2610 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2611 | |
| 2612 | next = tmp->next; |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2613 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2614 | continue; |
| 2615 | /* |
| 2616 | * Descend a level if the d_mounts list is non-empty. |
| 2617 | */ |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2618 | if (!list_empty(&mnt->mnt_mounts)) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2619 | this_parent = mnt; |
| 2620 | goto repeat; |
| 2621 | } |
| 2622 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 2623 | if (!propagate_mount_busy(mnt, 1)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2624 | list_move_tail(&mnt->mnt_expire, graveyard); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2625 | found++; |
| 2626 | } |
| 2627 | } |
| 2628 | /* |
| 2629 | * All done at this level ... ascend and resume the search |
| 2630 | */ |
| 2631 | if (this_parent != parent) { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2632 | next = this_parent->mnt_child.next; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 2633 | this_parent = this_parent->mnt_parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2634 | goto resume; |
| 2635 | } |
| 2636 | return found; |
| 2637 | } |
| 2638 | |
| 2639 | /* |
| 2640 | * process a list of expirable mountpoints with the intent of discarding any |
| 2641 | * submounts of a specific parent mountpoint |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2642 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2643 | * mount_lock must be held for write |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2644 | */ |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 2645 | static void shrink_submounts(struct mount *mnt) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2646 | { |
| 2647 | LIST_HEAD(graveyard); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2648 | struct mount *m; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2649 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2650 | /* extract submounts of 'mountpoint' from the expiration list */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2651 | while (select_submounts(mnt, &graveyard)) { |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2652 | while (!list_empty(&graveyard)) { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2653 | m = list_first_entry(&graveyard, struct mount, |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2654 | mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2655 | touch_mnt_namespace(m->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2656 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2657 | } |
| 2658 | } |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2659 | } |
| 2660 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2661 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2662 | * Some copy_from_user() implementations do not return the exact number of |
| 2663 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 2664 | * Note that this function differs from copy_from_user() in that it will oops |
| 2665 | * on bad values of `to', rather than returning a short copy. |
| 2666 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2667 | static long exact_copy_from_user(void *to, const void __user * from, |
| 2668 | unsigned long n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2669 | { |
| 2670 | char *t = to; |
| 2671 | const char __user *f = from; |
| 2672 | char c; |
| 2673 | |
| 2674 | if (!access_ok(VERIFY_READ, from, n)) |
| 2675 | return n; |
| 2676 | |
| 2677 | while (n) { |
| 2678 | if (__get_user(c, f)) { |
| 2679 | memset(t, 0, n); |
| 2680 | break; |
| 2681 | } |
| 2682 | *t++ = c; |
| 2683 | f++; |
| 2684 | n--; |
| 2685 | } |
| 2686 | return n; |
| 2687 | } |
| 2688 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2689 | void *copy_mount_options(const void __user * data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2690 | { |
| 2691 | int i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2692 | unsigned long size; |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2693 | char *copy; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2694 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2695 | if (!data) |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2696 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2697 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2698 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| 2699 | if (!copy) |
| 2700 | return ERR_PTR(-ENOMEM); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2701 | |
| 2702 | /* We only care that *some* data at the address the user |
| 2703 | * gave us is valid. Just in case, we'll zero |
| 2704 | * the remainder of the page. |
| 2705 | */ |
| 2706 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 2707 | size = TASK_SIZE - (unsigned long)data; |
| 2708 | if (size > PAGE_SIZE) |
| 2709 | size = PAGE_SIZE; |
| 2710 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2711 | i = size - exact_copy_from_user(copy, data, size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2712 | if (!i) { |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2713 | kfree(copy); |
| 2714 | return ERR_PTR(-EFAULT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2715 | } |
| 2716 | if (i != PAGE_SIZE) |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 2717 | memset(copy + i, 0, PAGE_SIZE - i); |
| 2718 | return copy; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2719 | } |
| 2720 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 2721 | char *copy_mount_string(const void __user *data) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2722 | { |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 2723 | return data ? strndup_user(data, PAGE_SIZE) : NULL; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2724 | } |
| 2725 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2726 | /* |
| 2727 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 2728 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 2729 | * |
| 2730 | * data is a (void *) that can point to any structure up to |
| 2731 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 2732 | * information (or be NULL). |
| 2733 | * |
| 2734 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 2735 | * When the flags word was introduced its top half was required |
| 2736 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 2737 | * Therefore, if this magic number is present, it carries no information |
| 2738 | * and must be discarded. |
| 2739 | */ |
Seunghun Lee | 5e6123f | 2014-09-14 22:15:10 +0900 | [diff] [blame] | 2740 | long do_mount(const char *dev_name, const char __user *dir_name, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2741 | const char *type_page, unsigned long flags, void *data_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2742 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2743 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2744 | int retval = 0; |
| 2745 | int mnt_flags = 0; |
| 2746 | |
| 2747 | /* Discard magic */ |
| 2748 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 2749 | flags &= ~MS_MGC_MSK; |
| 2750 | |
| 2751 | /* Basic sanity checks */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2752 | if (data_page) |
| 2753 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 2754 | |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 2755 | /* ... and get the mountpoint */ |
Seunghun Lee | 5e6123f | 2014-09-14 22:15:10 +0900 | [diff] [blame] | 2756 | retval = user_path(dir_name, &path); |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 2757 | if (retval) |
| 2758 | return retval; |
| 2759 | |
| 2760 | retval = security_sb_mount(dev_name, &path, |
| 2761 | type_page, flags, data_page); |
Al Viro | 0d5cadb | 2013-05-04 14:40:51 -0400 | [diff] [blame] | 2762 | if (!retval && !may_mount()) |
| 2763 | retval = -EPERM; |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 2764 | if (!retval && (flags & MS_MANDLOCK) && !may_mandlock()) |
| 2765 | retval = -EPERM; |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 2766 | if (retval) |
| 2767 | goto dput_out; |
| 2768 | |
Andi Kleen | 613cbe3 | 2009-04-19 18:40:43 +0200 | [diff] [blame] | 2769 | /* Default to relatime unless overriden */ |
| 2770 | if (!(flags & MS_NOATIME)) |
| 2771 | mnt_flags |= MNT_RELATIME; |
Matthew Garrett | 0a1c01c | 2009-03-26 17:53:14 +0000 | [diff] [blame] | 2772 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2773 | /* Separate the per-mountpoint flags */ |
| 2774 | if (flags & MS_NOSUID) |
| 2775 | mnt_flags |= MNT_NOSUID; |
| 2776 | if (flags & MS_NODEV) |
| 2777 | mnt_flags |= MNT_NODEV; |
| 2778 | if (flags & MS_NOEXEC) |
| 2779 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2780 | if (flags & MS_NOATIME) |
| 2781 | mnt_flags |= MNT_NOATIME; |
| 2782 | if (flags & MS_NODIRATIME) |
| 2783 | mnt_flags |= MNT_NODIRATIME; |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2784 | if (flags & MS_STRICTATIME) |
| 2785 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2786 | if (flags & MS_RDONLY) |
| 2787 | mnt_flags |= MNT_READONLY; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2788 | |
Eric W. Biederman | ffbc6f0 | 2014-07-28 17:36:04 -0700 | [diff] [blame] | 2789 | /* The default atime for remount is preservation */ |
| 2790 | if ((flags & MS_REMOUNT) && |
| 2791 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | |
| 2792 | MS_STRICTATIME)) == 0)) { |
| 2793 | mnt_flags &= ~MNT_ATIME_MASK; |
| 2794 | mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; |
| 2795 | } |
| 2796 | |
Al Viro | 7a4dec5 | 2010-08-09 12:05:43 -0400 | [diff] [blame] | 2797 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2798 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
Eric W. Biederman | d3381fa | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 2799 | MS_STRICTATIME | MS_NOREMOTELOCK | MS_SUBMOUNT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2800 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2801 | if (flags & MS_REMOUNT) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2802 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2803 | data_page); |
| 2804 | else if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2805 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2806 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2807 | retval = do_change_type(&path, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2808 | else if (flags & MS_MOVE) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2809 | retval = do_move_mount(&path, dev_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2810 | else |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2811 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2812 | dev_name, data_page); |
| 2813 | dput_out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2814 | path_put(&path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2815 | return retval; |
| 2816 | } |
| 2817 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2818 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
| 2819 | { |
| 2820 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); |
| 2821 | } |
| 2822 | |
| 2823 | static void dec_mnt_namespaces(struct ucounts *ucounts) |
| 2824 | { |
| 2825 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); |
| 2826 | } |
| 2827 | |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2828 | static void free_mnt_ns(struct mnt_namespace *ns) |
| 2829 | { |
Al Viro | 6344c43 | 2014-11-01 00:45:45 -0400 | [diff] [blame] | 2830 | ns_free_inum(&ns->ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2831 | dec_mnt_namespaces(ns->ucounts); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2832 | put_user_ns(ns->user_ns); |
| 2833 | kfree(ns); |
| 2834 | } |
| 2835 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2836 | /* |
| 2837 | * Assign a sequence number so we can detect when we attempt to bind |
| 2838 | * mount a reference to an older mount namespace into the current |
| 2839 | * mount namespace, preventing reference counting loops. A 64bit |
| 2840 | * number incrementing at 10Ghz will take 12,427 years to wrap which |
| 2841 | * is effectively never, so we can ignore the possibility. |
| 2842 | */ |
| 2843 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); |
| 2844 | |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2845 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2846 | { |
| 2847 | struct mnt_namespace *new_ns; |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2848 | struct ucounts *ucounts; |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 2849 | int ret; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2850 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2851 | ucounts = inc_mnt_namespaces(user_ns); |
| 2852 | if (!ucounts) |
Eric W. Biederman | df75e77 | 2016-09-22 13:08:36 -0500 | [diff] [blame] | 2853 | return ERR_PTR(-ENOSPC); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2854 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2855 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2856 | if (!new_ns) { |
| 2857 | dec_mnt_namespaces(ucounts); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2858 | return ERR_PTR(-ENOMEM); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2859 | } |
Al Viro | 6344c43 | 2014-11-01 00:45:45 -0400 | [diff] [blame] | 2860 | ret = ns_alloc_inum(&new_ns->ns); |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 2861 | if (ret) { |
| 2862 | kfree(new_ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2863 | dec_mnt_namespaces(ucounts); |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 2864 | return ERR_PTR(ret); |
| 2865 | } |
Al Viro | 33c4294 | 2014-11-01 02:32:53 -0400 | [diff] [blame] | 2866 | new_ns->ns.ops = &mntns_operations; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2867 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2868 | atomic_set(&new_ns->count, 1); |
| 2869 | new_ns->root = NULL; |
| 2870 | INIT_LIST_HEAD(&new_ns->list); |
| 2871 | init_waitqueue_head(&new_ns->poll); |
| 2872 | new_ns->event = 0; |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2873 | new_ns->user_ns = get_user_ns(user_ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 2874 | new_ns->ucounts = ucounts; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2875 | new_ns->mounts = 0; |
| 2876 | new_ns->pending_mounts = 0; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2877 | return new_ns; |
| 2878 | } |
| 2879 | |
Emese Revfy | 0766f78 | 2016-06-20 20:42:34 +0200 | [diff] [blame] | 2880 | __latent_entropy |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2881 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
| 2882 | struct user_namespace *user_ns, struct fs_struct *new_fs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2883 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2884 | struct mnt_namespace *new_ns; |
Al Viro | 7f2da1e | 2008-05-10 20:44:54 -0400 | [diff] [blame] | 2885 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2886 | struct mount *p, *q; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2887 | struct mount *old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 2888 | struct mount *new; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 2889 | int copy_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2890 | |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2891 | BUG_ON(!ns); |
| 2892 | |
| 2893 | if (likely(!(flags & CLONE_NEWNS))) { |
| 2894 | get_mnt_ns(ns); |
| 2895 | return ns; |
| 2896 | } |
| 2897 | |
| 2898 | old = ns->root; |
| 2899 | |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2900 | new_ns = alloc_mnt_ns(user_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2901 | if (IS_ERR(new_ns)) |
| 2902 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2903 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2904 | namespace_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2905 | /* First pass: copy the tree topology */ |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2906 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2907 | if (user_ns != ns->user_ns) |
Eric W. Biederman | 132c94e | 2013-03-22 04:08:05 -0700 | [diff] [blame] | 2908 | copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 2909 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2910 | if (IS_ERR(new)) { |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2911 | namespace_unlock(); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2912 | free_mnt_ns(new_ns); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2913 | return ERR_CAST(new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2914 | } |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2915 | new_ns->root = new; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2916 | list_add_tail(&new_ns->list, &new->mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2917 | |
| 2918 | /* |
| 2919 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 2920 | * as belonging to new namespace. We have already acquired a private |
| 2921 | * fs_struct, so tsk->fs->lock is not needed. |
| 2922 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2923 | p = old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 2924 | q = new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2925 | while (p) { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2926 | q->mnt_ns = new_ns; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2927 | new_ns->mounts++; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2928 | if (new_fs) { |
| 2929 | if (&p->mnt == new_fs->root.mnt) { |
| 2930 | new_fs->root.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2931 | rootmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2932 | } |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 2933 | if (&p->mnt == new_fs->pwd.mnt) { |
| 2934 | new_fs->pwd.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2935 | pwdmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2936 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2937 | } |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2938 | p = next_mnt(p, old); |
| 2939 | q = next_mnt(q, new); |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2940 | if (!q) |
| 2941 | break; |
| 2942 | while (p->mnt.mnt_root != q->mnt.mnt_root) |
| 2943 | p = next_mnt(p, old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2944 | } |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2945 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2946 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2947 | if (rootmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 2948 | mntput(rootmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2949 | if (pwdmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 2950 | mntput(pwdmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2951 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2952 | return new_ns; |
| 2953 | } |
| 2954 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2955 | /** |
| 2956 | * create_mnt_ns - creates a private namespace and adds a root filesystem |
| 2957 | * @mnt: pointer to the new root filesystem mountpoint |
| 2958 | */ |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2959 | static struct mnt_namespace *create_mnt_ns(struct vfsmount *m) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2960 | { |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 2961 | struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2962 | if (!IS_ERR(new_ns)) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2963 | struct mount *mnt = real_mount(m); |
| 2964 | mnt->mnt_ns = new_ns; |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2965 | new_ns->root = mnt; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2966 | new_ns->mounts++; |
Al Viro | b1983cd | 2013-05-04 15:18:53 -0400 | [diff] [blame] | 2967 | list_add(&mnt->mnt_list, &new_ns->list); |
Al Viro | c133449 | 2011-11-16 16:12:14 -0500 | [diff] [blame] | 2968 | } else { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2969 | mntput(m); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2970 | } |
| 2971 | return new_ns; |
| 2972 | } |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2973 | |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2974 | struct dentry *mount_subtree(struct vfsmount *mnt, const char *name) |
| 2975 | { |
| 2976 | struct mnt_namespace *ns; |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2977 | struct super_block *s; |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2978 | struct path path; |
| 2979 | int err; |
| 2980 | |
| 2981 | ns = create_mnt_ns(mnt); |
| 2982 | if (IS_ERR(ns)) |
| 2983 | return ERR_CAST(ns); |
| 2984 | |
| 2985 | err = vfs_path_lookup(mnt->mnt_root, mnt, |
| 2986 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
| 2987 | |
| 2988 | put_mnt_ns(ns); |
| 2989 | |
| 2990 | if (err) |
| 2991 | return ERR_PTR(err); |
| 2992 | |
| 2993 | /* trade a vfsmount reference for active sb one */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2994 | s = path.mnt->mnt_sb; |
| 2995 | atomic_inc(&s->s_active); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2996 | mntput(path.mnt); |
| 2997 | /* lock the sucker */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2998 | down_write(&s->s_umount); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2999 | /* ... and return the root of (sub)tree on it */ |
| 3000 | return path.dentry; |
| 3001 | } |
| 3002 | EXPORT_SYMBOL(mount_subtree); |
| 3003 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 3004 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 3005 | char __user *, type, unsigned long, flags, void __user *, data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3006 | { |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3007 | int ret; |
| 3008 | char *kernel_type; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3009 | char *kernel_dev; |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3010 | void *options; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3011 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3012 | kernel_type = copy_mount_string(type); |
| 3013 | ret = PTR_ERR(kernel_type); |
| 3014 | if (IS_ERR(kernel_type)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3015 | goto out_type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3016 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3017 | kernel_dev = copy_mount_string(dev_name); |
| 3018 | ret = PTR_ERR(kernel_dev); |
| 3019 | if (IS_ERR(kernel_dev)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3020 | goto out_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3021 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3022 | options = copy_mount_options(data); |
| 3023 | ret = PTR_ERR(options); |
| 3024 | if (IS_ERR(options)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3025 | goto out_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3026 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3027 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3028 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3029 | kfree(options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3030 | out_data: |
| 3031 | kfree(kernel_dev); |
| 3032 | out_dev: |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3033 | kfree(kernel_type); |
| 3034 | out_type: |
| 3035 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3036 | } |
| 3037 | |
| 3038 | /* |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3039 | * Return true if path is reachable from root |
| 3040 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3041 | * namespace_sem or mount_lock is held |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3042 | */ |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3043 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3044 | const struct path *root) |
| 3045 | { |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3046 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 3047 | dentry = mnt->mnt_mountpoint; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 3048 | mnt = mnt->mnt_parent; |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3049 | } |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3050 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3051 | } |
| 3052 | |
Yaowei Bai | 25ab4c9 | 2015-11-17 14:40:10 +0800 | [diff] [blame] | 3053 | bool path_is_under(struct path *path1, struct path *path2) |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3054 | { |
Yaowei Bai | 25ab4c9 | 2015-11-17 14:40:10 +0800 | [diff] [blame] | 3055 | bool res; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3056 | read_seqlock_excl(&mount_lock); |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3057 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3058 | read_sequnlock_excl(&mount_lock); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3059 | return res; |
| 3060 | } |
| 3061 | EXPORT_SYMBOL(path_is_under); |
| 3062 | |
| 3063 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3064 | * pivot_root Semantics: |
| 3065 | * Moves the root file system of the current process to the directory put_old, |
| 3066 | * makes new_root as the new root file system of the current process, and sets |
| 3067 | * root/cwd of all processes which had them on the current root to new_root. |
| 3068 | * |
| 3069 | * Restrictions: |
| 3070 | * The new_root and put_old must be directories, and must not be on the |
| 3071 | * same file system as the current process root. The put_old must be |
| 3072 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 3073 | * pointed to by put_old must yield the same directory as new_root. No other |
| 3074 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 3075 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 3076 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
| 3077 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives |
| 3078 | * in this situation. |
| 3079 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3080 | * Notes: |
| 3081 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 3082 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 3083 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 3084 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 3085 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 3086 | * first. |
| 3087 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 3088 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 3089 | const char __user *, put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3090 | { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3091 | struct path new, old, parent_path, root_parent, root; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3092 | struct mount *new_mnt, *root_mnt, *old_mnt; |
| 3093 | struct mountpoint *old_mp, *root_mp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3094 | int error; |
| 3095 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 3096 | if (!may_mount()) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3097 | return -EPERM; |
| 3098 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3099 | error = user_path_dir(new_root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3100 | if (error) |
| 3101 | goto out0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3102 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3103 | error = user_path_dir(put_old, &old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3104 | if (error) |
| 3105 | goto out1; |
| 3106 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3107 | error = security_sb_pivotroot(&old, &new); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3108 | if (error) |
| 3109 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3110 | |
Miklos Szeredi | f7ad3c6 | 2010-08-10 11:41:36 +0200 | [diff] [blame] | 3111 | get_fs_root(current->fs, &root); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3112 | old_mp = lock_mount(&old); |
| 3113 | error = PTR_ERR(old_mp); |
| 3114 | if (IS_ERR(old_mp)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3115 | goto out3; |
| 3116 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3117 | error = -EINVAL; |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 3118 | new_mnt = real_mount(new.mnt); |
| 3119 | root_mnt = real_mount(root.mnt); |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3120 | old_mnt = real_mount(old.mnt); |
| 3121 | if (IS_MNT_SHARED(old_mnt) || |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 3122 | IS_MNT_SHARED(new_mnt->mnt_parent) || |
| 3123 | IS_MNT_SHARED(root_mnt->mnt_parent)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3124 | goto out4; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3125 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3126 | goto out4; |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 3127 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
| 3128 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3129 | error = -ENOENT; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 3130 | if (d_unlinked(new.dentry)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3131 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3132 | error = -EBUSY; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3133 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3134 | goto out4; /* loop, on the same file system */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3135 | error = -EINVAL; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 3136 | if (root.mnt->mnt_root != root.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3137 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3138 | if (!mnt_has_parent(root_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3139 | goto out4; /* not attached */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3140 | root_mp = root_mnt->mnt_mp; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3141 | if (new.mnt->mnt_root != new.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3142 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3143 | if (!mnt_has_parent(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3144 | goto out4; /* not attached */ |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3145 | /* make sure we can reach put_old from new_root */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3146 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3147 | goto out4; |
Eric W. Biederman | 0d08260 | 2014-10-08 10:42:27 -0700 | [diff] [blame] | 3148 | /* make certain new is below the root */ |
| 3149 | if (!is_path_reachable(new_mnt, new.dentry, &root)) |
| 3150 | goto out4; |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3151 | root_mp->m_count++; /* pin it so it won't go away */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3152 | lock_mount_hash(); |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 3153 | detach_mnt(new_mnt, &parent_path); |
| 3154 | detach_mnt(root_mnt, &root_parent); |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 3155 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
| 3156 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; |
| 3157 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 3158 | } |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3159 | /* mount old root on put_old */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3160 | attach_mnt(root_mnt, old_mnt, old_mp); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3161 | /* mount new_root on / */ |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3162 | attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3163 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
Eric W. Biederman | 4fed655 | 2014-10-08 10:42:57 -0700 | [diff] [blame] | 3164 | /* A moved mount should not expire automatically */ |
| 3165 | list_del_init(&new_mnt->mnt_expire); |
Eric W. Biederman | 1a62a0f | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 3166 | put_mountpoint(root_mp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3167 | unlock_mount_hash(); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3168 | chroot_fs_refs(&root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3169 | error = 0; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3170 | out4: |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3171 | unlock_mount(old_mp); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3172 | if (!error) { |
| 3173 | path_put(&root_parent); |
| 3174 | path_put(&parent_path); |
| 3175 | } |
| 3176 | out3: |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 3177 | path_put(&root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3178 | out2: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3179 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3180 | out1: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3181 | path_put(&new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3182 | out0: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3183 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3184 | } |
| 3185 | |
| 3186 | static void __init init_mount_tree(void) |
| 3187 | { |
| 3188 | struct vfsmount *mnt; |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3189 | struct mnt_namespace *ns; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 3190 | struct path root; |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3191 | struct file_system_type *type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3192 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3193 | type = get_fs_type("rootfs"); |
| 3194 | if (!type) |
| 3195 | panic("Can't find rootfs type"); |
| 3196 | mnt = vfs_kern_mount(type, 0, "rootfs", NULL); |
| 3197 | put_filesystem(type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3198 | if (IS_ERR(mnt)) |
| 3199 | panic("Can't create rootfs"); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 3200 | |
Trond Myklebust | 3b22edc | 2009-06-23 17:29:49 -0400 | [diff] [blame] | 3201 | ns = create_mnt_ns(mnt); |
| 3202 | if (IS_ERR(ns)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3203 | panic("Can't allocate initial namespace"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3204 | |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3205 | init_task.nsproxy->mnt_ns = ns; |
| 3206 | get_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3207 | |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 3208 | root.mnt = mnt; |
| 3209 | root.dentry = mnt->mnt_root; |
Eric W. Biederman | da362b0 | 2014-10-07 12:19:53 -0700 | [diff] [blame] | 3210 | mnt->mnt_flags |= MNT_LOCKED; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 3211 | |
| 3212 | set_fs_pwd(current->fs, &root); |
| 3213 | set_fs_root(current->fs, &root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3214 | } |
| 3215 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3216 | void __init mnt_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3217 | { |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 3218 | unsigned u; |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 3219 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3220 | |
Al Viro | 7d6fec4 | 2011-11-23 12:14:10 -0500 | [diff] [blame] | 3221 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 3222 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3223 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3224 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 3225 | sizeof(struct hlist_head), |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3226 | mhash_entries, 19, |
| 3227 | 0, |
| 3228 | &m_hash_shift, &m_hash_mask, 0, 0); |
| 3229 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", |
| 3230 | sizeof(struct hlist_head), |
| 3231 | mphash_entries, 19, |
| 3232 | 0, |
| 3233 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3234 | |
Al Viro | 84d1719 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3235 | if (!mount_hashtable || !mountpoint_hashtable) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3236 | panic("Failed to allocate mount hash table\n"); |
| 3237 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3238 | for (u = 0; u <= m_hash_mask; u++) |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 3239 | INIT_HLIST_HEAD(&mount_hashtable[u]); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3240 | for (u = 0; u <= mp_hash_mask; u++) |
| 3241 | INIT_HLIST_HEAD(&mountpoint_hashtable[u]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3242 | |
Tejun Heo | 4b93dc9 | 2013-11-28 14:54:43 -0500 | [diff] [blame] | 3243 | kernfs_init(); |
| 3244 | |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 3245 | err = sysfs_init(); |
| 3246 | if (err) |
| 3247 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 3248 | __func__, err); |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 3249 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 3250 | if (!fs_kobj) |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 3251 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3252 | init_rootfs(); |
| 3253 | init_mount_tree(); |
| 3254 | } |
| 3255 | |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3256 | void put_mnt_ns(struct mnt_namespace *ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3257 | { |
Al Viro | d498b25 | 2010-02-05 02:21:06 -0500 | [diff] [blame] | 3258 | if (!atomic_dec_and_test(&ns->count)) |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3259 | return; |
Al Viro | 7b00ed6 | 2013-09-16 21:19:20 -0400 | [diff] [blame] | 3260 | drop_collected_mounts(&ns->root->mnt); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3261 | free_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3262 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3263 | |
| 3264 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
| 3265 | { |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3266 | struct vfsmount *mnt; |
| 3267 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
| 3268 | if (!IS_ERR(mnt)) { |
| 3269 | /* |
| 3270 | * it is a longterm mount, don't release mnt until |
| 3271 | * we unmount before file sys is unregistered |
| 3272 | */ |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 3273 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3274 | } |
| 3275 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3276 | } |
| 3277 | EXPORT_SYMBOL_GPL(kern_mount_data); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3278 | |
| 3279 | void kern_unmount(struct vfsmount *mnt) |
| 3280 | { |
| 3281 | /* release long term mount so mount point can be released */ |
| 3282 | if (!IS_ERR_OR_NULL(mnt)) { |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 3283 | real_mount(mnt)->mnt_ns = NULL; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3284 | synchronize_rcu(); /* yecchhh... */ |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3285 | mntput(mnt); |
| 3286 | } |
| 3287 | } |
| 3288 | EXPORT_SYMBOL(kern_unmount); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3289 | |
| 3290 | bool our_mnt(struct vfsmount *mnt) |
| 3291 | { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3292 | return check_mnt(real_mount(mnt)); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3293 | } |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3294 | |
Eric W. Biederman | 3151527 | 2013-03-15 01:45:51 -0700 | [diff] [blame] | 3295 | bool current_chrooted(void) |
| 3296 | { |
| 3297 | /* Does the current process have a non-standard root */ |
| 3298 | struct path ns_root; |
| 3299 | struct path fs_root; |
| 3300 | bool chrooted; |
| 3301 | |
| 3302 | /* Find the namespace root */ |
| 3303 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; |
| 3304 | ns_root.dentry = ns_root.mnt->mnt_root; |
| 3305 | path_get(&ns_root); |
| 3306 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) |
| 3307 | ; |
| 3308 | |
| 3309 | get_fs_root(current->fs, &fs_root); |
| 3310 | |
| 3311 | chrooted = !path_equal(&fs_root, &ns_root); |
| 3312 | |
| 3313 | path_put(&fs_root); |
| 3314 | path_put(&ns_root); |
| 3315 | |
| 3316 | return chrooted; |
| 3317 | } |
| 3318 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3319 | static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, |
| 3320 | int *new_mnt_flags) |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3321 | { |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3322 | int new_flags = *new_mnt_flags; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3323 | struct mount *mnt; |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3324 | bool visible = false; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3325 | |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 3326 | down_read(&namespace_sem); |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3327 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3328 | struct mount *child; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3329 | int mnt_flags; |
| 3330 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3331 | if (mnt->mnt.mnt_sb->s_type != new->mnt_sb->s_type) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3332 | continue; |
| 3333 | |
Eric W. Biederman | 7e96c1b | 2015-05-08 16:36:50 -0500 | [diff] [blame] | 3334 | /* This mount is not fully visible if it's root directory |
| 3335 | * is not the root directory of the filesystem. |
| 3336 | */ |
| 3337 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) |
| 3338 | continue; |
| 3339 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 3340 | /* A local view of the mount flags */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3341 | mnt_flags = mnt->mnt.mnt_flags; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3342 | |
Eric W. Biederman | 695e9df | 2016-06-10 12:21:40 -0500 | [diff] [blame] | 3343 | /* Don't miss readonly hidden in the superblock flags */ |
| 3344 | if (mnt->mnt.mnt_sb->s_flags & MS_RDONLY) |
| 3345 | mnt_flags |= MNT_LOCK_READONLY; |
| 3346 | |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3347 | /* Verify the mount flags are equal to or more permissive |
| 3348 | * than the proposed new mount. |
| 3349 | */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3350 | if ((mnt_flags & MNT_LOCK_READONLY) && |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3351 | !(new_flags & MNT_READONLY)) |
| 3352 | continue; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3353 | if ((mnt_flags & MNT_LOCK_ATIME) && |
| 3354 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3355 | continue; |
| 3356 | |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3357 | /* This mount is not fully visible if there are any |
| 3358 | * locked child mounts that cover anything except for |
| 3359 | * empty directories. |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3360 | */ |
| 3361 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 3362 | struct inode *inode = child->mnt_mountpoint->d_inode; |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3363 | /* Only worry about locked mounts */ |
Eric W. Biederman | d71ed6c | 2016-05-27 14:50:05 -0500 | [diff] [blame] | 3364 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3365 | continue; |
Eric W. Biederman | 7236c85 | 2015-05-13 20:51:09 -0500 | [diff] [blame] | 3366 | /* Is the directory permanetly empty? */ |
| 3367 | if (!is_empty_dir_inode(inode)) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3368 | goto next; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3369 | } |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3370 | /* Preserve the locked attributes */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3371 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3372 | MNT_LOCK_ATIME); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3373 | visible = true; |
| 3374 | goto found; |
| 3375 | next: ; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3376 | } |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3377 | found: |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 3378 | up_read(&namespace_sem); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3379 | return visible; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3380 | } |
| 3381 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3382 | static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags) |
| 3383 | { |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 3384 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3385 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 3386 | unsigned long s_iflags; |
| 3387 | |
| 3388 | if (ns->user_ns == &init_user_ns) |
| 3389 | return false; |
| 3390 | |
| 3391 | /* Can this filesystem be too revealing? */ |
| 3392 | s_iflags = mnt->mnt_sb->s_iflags; |
| 3393 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
| 3394 | return false; |
| 3395 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 3396 | if ((s_iflags & required_iflags) != required_iflags) { |
| 3397 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", |
| 3398 | required_iflags); |
| 3399 | return true; |
| 3400 | } |
| 3401 | |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3402 | return !mnt_already_visible(ns, mnt, new_mnt_flags); |
| 3403 | } |
| 3404 | |
Andy Lutomirski | 380cf5b | 2016-06-23 16:41:05 -0500 | [diff] [blame] | 3405 | bool mnt_may_suid(struct vfsmount *mnt) |
| 3406 | { |
| 3407 | /* |
| 3408 | * Foreign mounts (accessed via fchdir or through /proc |
| 3409 | * symlinks) are always treated as if they are nosuid. This |
| 3410 | * prevents namespaces from trusting potentially unsafe |
| 3411 | * suid/sgid bits, file caps, or security labels that originate |
| 3412 | * in other namespaces. |
| 3413 | */ |
| 3414 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && |
| 3415 | current_in_userns(mnt->mnt_sb->s_user_ns); |
| 3416 | } |
| 3417 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 3418 | static struct ns_common *mntns_get(struct task_struct *task) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3419 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 3420 | struct ns_common *ns = NULL; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3421 | struct nsproxy *nsproxy; |
| 3422 | |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 3423 | task_lock(task); |
| 3424 | nsproxy = task->nsproxy; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3425 | if (nsproxy) { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 3426 | ns = &nsproxy->mnt_ns->ns; |
| 3427 | get_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3428 | } |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 3429 | task_unlock(task); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3430 | |
| 3431 | return ns; |
| 3432 | } |
| 3433 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 3434 | static void mntns_put(struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3435 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 3436 | put_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3437 | } |
| 3438 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 3439 | static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3440 | { |
| 3441 | struct fs_struct *fs = current->fs; |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 3442 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3443 | struct path root; |
| 3444 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3445 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
Eric W. Biederman | c7b96ac | 2013-03-20 12:49:49 -0700 | [diff] [blame] | 3446 | !ns_capable(current_user_ns(), CAP_SYS_CHROOT) || |
| 3447 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) |
Zhao Hongjiang | ae11e0f | 2012-09-13 16:38:03 +0800 | [diff] [blame] | 3448 | return -EPERM; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3449 | |
| 3450 | if (fs->users != 1) |
| 3451 | return -EINVAL; |
| 3452 | |
| 3453 | get_mnt_ns(mnt_ns); |
| 3454 | put_mnt_ns(nsproxy->mnt_ns); |
| 3455 | nsproxy->mnt_ns = mnt_ns; |
| 3456 | |
| 3457 | /* Find the root */ |
| 3458 | root.mnt = &mnt_ns->root->mnt; |
| 3459 | root.dentry = mnt_ns->root->mnt.mnt_root; |
| 3460 | path_get(&root); |
| 3461 | while(d_mountpoint(root.dentry) && follow_down_one(&root)) |
| 3462 | ; |
| 3463 | |
| 3464 | /* Update the pwd and root */ |
| 3465 | set_fs_pwd(fs, &root); |
| 3466 | set_fs_root(fs, &root); |
| 3467 | |
| 3468 | path_put(&root); |
| 3469 | return 0; |
| 3470 | } |
| 3471 | |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 3472 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
| 3473 | { |
| 3474 | return to_mnt_ns(ns)->user_ns; |
| 3475 | } |
| 3476 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3477 | const struct proc_ns_operations mntns_operations = { |
| 3478 | .name = "mnt", |
| 3479 | .type = CLONE_NEWNS, |
| 3480 | .get = mntns_get, |
| 3481 | .put = mntns_put, |
| 3482 | .install = mntns_install, |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 3483 | .owner = mntns_owner, |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3484 | }; |