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 | |
| 11 | #include <linux/config.h> |
| 12 | #include <linux/syscalls.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/sched.h> |
| 15 | #include <linux/smp_lock.h> |
| 16 | #include <linux/init.h> |
| 17 | #include <linux/quotaops.h> |
| 18 | #include <linux/acct.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 19 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | #include <linux/module.h> |
| 21 | #include <linux/seq_file.h> |
| 22 | #include <linux/namespace.h> |
| 23 | #include <linux/namei.h> |
| 24 | #include <linux/security.h> |
| 25 | #include <linux/mount.h> |
| 26 | #include <asm/uaccess.h> |
| 27 | #include <asm/unistd.h> |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 28 | #include "pnode.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | |
| 30 | extern int __init init_rootfs(void); |
| 31 | |
| 32 | #ifdef CONFIG_SYSFS |
| 33 | extern int __init sysfs_init(void); |
| 34 | #else |
| 35 | static inline int sysfs_init(void) |
| 36 | { |
| 37 | return 0; |
| 38 | } |
| 39 | #endif |
| 40 | |
| 41 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 42 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
| 43 | |
| 44 | static int event; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
| 46 | static struct list_head *mount_hashtable; |
Ravikiran G Thirumalai | 6c231b7 | 2005-09-06 15:17:45 -0700 | [diff] [blame] | 47 | static int hash_mask __read_mostly, hash_bits __read_mostly; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 48 | static kmem_cache_t *mnt_cache; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 49 | static struct rw_semaphore namespace_sem; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 51 | /* /sys/fs */ |
| 52 | decl_subsys(fs, NULL, NULL); |
| 53 | EXPORT_SYMBOL_GPL(fs_subsys); |
| 54 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
| 56 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 57 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 58 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | tmp = tmp + (tmp >> hash_bits); |
| 60 | return tmp & hash_mask; |
| 61 | } |
| 62 | |
| 63 | struct vfsmount *alloc_vfsmnt(const char *name) |
| 64 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 65 | struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | if (mnt) { |
| 67 | memset(mnt, 0, sizeof(struct vfsmount)); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 68 | atomic_set(&mnt->mnt_count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | INIT_LIST_HEAD(&mnt->mnt_hash); |
| 70 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 71 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 72 | INIT_LIST_HEAD(&mnt->mnt_list); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 73 | INIT_LIST_HEAD(&mnt->mnt_expire); |
Ram Pai | 03e06e6 | 2005-11-07 17:19:33 -0500 | [diff] [blame] | 74 | INIT_LIST_HEAD(&mnt->mnt_share); |
Ram Pai | a58b0eb | 2005-11-07 17:20:48 -0500 | [diff] [blame] | 75 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 76 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 77 | if (name) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 78 | int size = strlen(name) + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 79 | char *newname = kmalloc(size, GFP_KERNEL); |
| 80 | if (newname) { |
| 81 | memcpy(newname, name, size); |
| 82 | mnt->mnt_devname = newname; |
| 83 | } |
| 84 | } |
| 85 | } |
| 86 | return mnt; |
| 87 | } |
| 88 | |
| 89 | void free_vfsmnt(struct vfsmount *mnt) |
| 90 | { |
| 91 | kfree(mnt->mnt_devname); |
| 92 | kmem_cache_free(mnt_cache, mnt); |
| 93 | } |
| 94 | |
| 95 | /* |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 96 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
| 97 | * @dir. If @dir is set return the first mount else return the last mount. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 99 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
| 100 | int dir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 102 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
| 103 | struct list_head *tmp = head; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 104 | struct vfsmount *p, *found = NULL; |
| 105 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | for (;;) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 107 | tmp = dir ? tmp->next : tmp->prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | p = NULL; |
| 109 | if (tmp == head) |
| 110 | break; |
| 111 | p = list_entry(tmp, struct vfsmount, mnt_hash); |
| 112 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 113 | found = p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | break; |
| 115 | } |
| 116 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 117 | return found; |
| 118 | } |
| 119 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 120 | /* |
| 121 | * lookup_mnt increments the ref count before returning |
| 122 | * the vfsmount struct. |
| 123 | */ |
| 124 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
| 125 | { |
| 126 | struct vfsmount *child_mnt; |
| 127 | spin_lock(&vfsmount_lock); |
| 128 | if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) |
| 129 | mntget(child_mnt); |
| 130 | spin_unlock(&vfsmount_lock); |
| 131 | return child_mnt; |
| 132 | } |
| 133 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | static inline int check_mnt(struct vfsmount *mnt) |
| 135 | { |
| 136 | return mnt->mnt_namespace == current->namespace; |
| 137 | } |
| 138 | |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 139 | static void touch_namespace(struct namespace *ns) |
| 140 | { |
| 141 | if (ns) { |
| 142 | ns->event = ++event; |
| 143 | wake_up_interruptible(&ns->poll); |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | static void __touch_namespace(struct namespace *ns) |
| 148 | { |
| 149 | if (ns && ns->event != event) { |
| 150 | ns->event = event; |
| 151 | wake_up_interruptible(&ns->poll); |
| 152 | } |
| 153 | } |
| 154 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) |
| 156 | { |
| 157 | old_nd->dentry = mnt->mnt_mountpoint; |
| 158 | old_nd->mnt = mnt->mnt_parent; |
| 159 | mnt->mnt_parent = mnt; |
| 160 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 161 | list_del_init(&mnt->mnt_child); |
| 162 | list_del_init(&mnt->mnt_hash); |
| 163 | old_nd->dentry->d_mounted--; |
| 164 | } |
| 165 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 166 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
| 167 | struct vfsmount *child_mnt) |
| 168 | { |
| 169 | child_mnt->mnt_parent = mntget(mnt); |
| 170 | child_mnt->mnt_mountpoint = dget(dentry); |
| 171 | dentry->d_mounted++; |
| 172 | } |
| 173 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 174 | static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) |
| 175 | { |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 176 | mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); |
| 177 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 178 | hash(nd->mnt, nd->dentry)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 179 | list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 180 | } |
| 181 | |
| 182 | /* |
| 183 | * the caller must hold vfsmount_lock |
| 184 | */ |
| 185 | static void commit_tree(struct vfsmount *mnt) |
| 186 | { |
| 187 | struct vfsmount *parent = mnt->mnt_parent; |
| 188 | struct vfsmount *m; |
| 189 | LIST_HEAD(head); |
| 190 | struct namespace *n = parent->mnt_namespace; |
| 191 | |
| 192 | BUG_ON(parent == mnt); |
| 193 | |
| 194 | list_add_tail(&head, &mnt->mnt_list); |
| 195 | list_for_each_entry(m, &head, mnt_list) |
| 196 | m->mnt_namespace = n; |
| 197 | list_splice(&head, n->list.prev); |
| 198 | |
| 199 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 200 | hash(parent, mnt->mnt_mountpoint)); |
| 201 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 202 | touch_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | } |
| 204 | |
| 205 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) |
| 206 | { |
| 207 | struct list_head *next = p->mnt_mounts.next; |
| 208 | if (next == &p->mnt_mounts) { |
| 209 | while (1) { |
| 210 | if (p == root) |
| 211 | return NULL; |
| 212 | next = p->mnt_child.next; |
| 213 | if (next != &p->mnt_parent->mnt_mounts) |
| 214 | break; |
| 215 | p = p->mnt_parent; |
| 216 | } |
| 217 | } |
| 218 | return list_entry(next, struct vfsmount, mnt_child); |
| 219 | } |
| 220 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 221 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
| 222 | { |
| 223 | struct list_head *prev = p->mnt_mounts.prev; |
| 224 | while (prev != &p->mnt_mounts) { |
| 225 | p = list_entry(prev, struct vfsmount, mnt_child); |
| 226 | prev = p->mnt_mounts.prev; |
| 227 | } |
| 228 | return p; |
| 229 | } |
| 230 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 231 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
| 232 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | { |
| 234 | struct super_block *sb = old->mnt_sb; |
| 235 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); |
| 236 | |
| 237 | if (mnt) { |
| 238 | mnt->mnt_flags = old->mnt_flags; |
| 239 | atomic_inc(&sb->s_active); |
| 240 | mnt->mnt_sb = sb; |
| 241 | mnt->mnt_root = dget(root); |
| 242 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 243 | mnt->mnt_parent = mnt; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 244 | |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 245 | if (flag & CL_SLAVE) { |
| 246 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 247 | mnt->mnt_master = old; |
| 248 | CLEAR_MNT_SHARED(mnt); |
| 249 | } else { |
| 250 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) |
| 251 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 252 | if (IS_MNT_SLAVE(old)) |
| 253 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 254 | mnt->mnt_master = old->mnt_master; |
| 255 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 256 | if (flag & CL_MAKE_SHARED) |
| 257 | set_mnt_shared(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | |
| 259 | /* stick the duplicate mount on the same expiry list |
| 260 | * as the original if that was on one */ |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 261 | if (flag & CL_EXPIRE) { |
| 262 | spin_lock(&vfsmount_lock); |
| 263 | if (!list_empty(&old->mnt_expire)) |
| 264 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 265 | spin_unlock(&vfsmount_lock); |
| 266 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | } |
| 268 | return mnt; |
| 269 | } |
| 270 | |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 271 | static inline void __mntput(struct vfsmount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 272 | { |
| 273 | struct super_block *sb = mnt->mnt_sb; |
| 274 | dput(mnt->mnt_root); |
| 275 | free_vfsmnt(mnt); |
| 276 | deactivate_super(sb); |
| 277 | } |
| 278 | |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 279 | void mntput_no_expire(struct vfsmount *mnt) |
| 280 | { |
| 281 | repeat: |
| 282 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { |
| 283 | if (likely(!mnt->mnt_pinned)) { |
| 284 | spin_unlock(&vfsmount_lock); |
| 285 | __mntput(mnt); |
| 286 | return; |
| 287 | } |
| 288 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); |
| 289 | mnt->mnt_pinned = 0; |
| 290 | spin_unlock(&vfsmount_lock); |
| 291 | acct_auto_close_mnt(mnt); |
| 292 | security_sb_umount_close(mnt); |
| 293 | goto repeat; |
| 294 | } |
| 295 | } |
| 296 | |
| 297 | EXPORT_SYMBOL(mntput_no_expire); |
| 298 | |
| 299 | void mnt_pin(struct vfsmount *mnt) |
| 300 | { |
| 301 | spin_lock(&vfsmount_lock); |
| 302 | mnt->mnt_pinned++; |
| 303 | spin_unlock(&vfsmount_lock); |
| 304 | } |
| 305 | |
| 306 | EXPORT_SYMBOL(mnt_pin); |
| 307 | |
| 308 | void mnt_unpin(struct vfsmount *mnt) |
| 309 | { |
| 310 | spin_lock(&vfsmount_lock); |
| 311 | if (mnt->mnt_pinned) { |
| 312 | atomic_inc(&mnt->mnt_count); |
| 313 | mnt->mnt_pinned--; |
| 314 | } |
| 315 | spin_unlock(&vfsmount_lock); |
| 316 | } |
| 317 | |
| 318 | EXPORT_SYMBOL(mnt_unpin); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 319 | |
| 320 | /* iterator */ |
| 321 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 322 | { |
| 323 | struct namespace *n = m->private; |
| 324 | struct list_head *p; |
| 325 | loff_t l = *pos; |
| 326 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 327 | down_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 328 | list_for_each(p, &n->list) |
| 329 | if (!l--) |
| 330 | return list_entry(p, struct vfsmount, mnt_list); |
| 331 | return NULL; |
| 332 | } |
| 333 | |
| 334 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 335 | { |
| 336 | struct namespace *n = m->private; |
| 337 | struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; |
| 338 | (*pos)++; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 339 | return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 340 | } |
| 341 | |
| 342 | static void m_stop(struct seq_file *m, void *v) |
| 343 | { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 344 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 345 | } |
| 346 | |
| 347 | static inline void mangle(struct seq_file *m, const char *s) |
| 348 | { |
| 349 | seq_escape(m, s, " \t\n\\"); |
| 350 | } |
| 351 | |
| 352 | static int show_vfsmnt(struct seq_file *m, void *v) |
| 353 | { |
| 354 | struct vfsmount *mnt = v; |
| 355 | int err = 0; |
| 356 | static struct proc_fs_info { |
| 357 | int flag; |
| 358 | char *str; |
| 359 | } fs_info[] = { |
| 360 | { MS_SYNCHRONOUS, ",sync" }, |
| 361 | { MS_DIRSYNC, ",dirsync" }, |
| 362 | { MS_MANDLOCK, ",mand" }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 363 | { 0, NULL } |
| 364 | }; |
| 365 | static struct proc_fs_info mnt_info[] = { |
| 366 | { MNT_NOSUID, ",nosuid" }, |
| 367 | { MNT_NODEV, ",nodev" }, |
| 368 | { MNT_NOEXEC, ",noexec" }, |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 369 | { MNT_NOATIME, ",noatime" }, |
| 370 | { MNT_NODIRATIME, ",nodiratime" }, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 371 | { 0, NULL } |
| 372 | }; |
| 373 | struct proc_fs_info *fs_infop; |
| 374 | |
| 375 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 376 | seq_putc(m, ' '); |
| 377 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); |
| 378 | seq_putc(m, ' '); |
| 379 | mangle(m, mnt->mnt_sb->s_type->name); |
| 380 | seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
| 381 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { |
| 382 | if (mnt->mnt_sb->s_flags & fs_infop->flag) |
| 383 | seq_puts(m, fs_infop->str); |
| 384 | } |
| 385 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { |
| 386 | if (mnt->mnt_flags & fs_infop->flag) |
| 387 | seq_puts(m, fs_infop->str); |
| 388 | } |
| 389 | if (mnt->mnt_sb->s_op->show_options) |
| 390 | err = mnt->mnt_sb->s_op->show_options(m, mnt); |
| 391 | seq_puts(m, " 0 0\n"); |
| 392 | return err; |
| 393 | } |
| 394 | |
| 395 | struct seq_operations mounts_op = { |
| 396 | .start = m_start, |
| 397 | .next = m_next, |
| 398 | .stop = m_stop, |
| 399 | .show = show_vfsmnt |
| 400 | }; |
| 401 | |
| 402 | /** |
| 403 | * may_umount_tree - check if a mount tree is busy |
| 404 | * @mnt: root of mount tree |
| 405 | * |
| 406 | * This is called to check if a tree of mounts has any |
| 407 | * open files, pwds, chroots or sub mounts that are |
| 408 | * busy. |
| 409 | */ |
| 410 | int may_umount_tree(struct vfsmount *mnt) |
| 411 | { |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 412 | int actual_refs = 0; |
| 413 | int minimum_refs = 0; |
| 414 | struct vfsmount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 415 | |
| 416 | spin_lock(&vfsmount_lock); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 417 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 418 | actual_refs += atomic_read(&p->mnt_count); |
| 419 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 420 | } |
| 421 | spin_unlock(&vfsmount_lock); |
| 422 | |
| 423 | if (actual_refs > minimum_refs) |
| 424 | return -EBUSY; |
| 425 | |
| 426 | return 0; |
| 427 | } |
| 428 | |
| 429 | EXPORT_SYMBOL(may_umount_tree); |
| 430 | |
| 431 | /** |
| 432 | * may_umount - check if a mount point is busy |
| 433 | * @mnt: root of mount |
| 434 | * |
| 435 | * This is called to check if a mount point has any |
| 436 | * open files, pwds, chroots or sub mounts. If the |
| 437 | * mount has sub mounts this will return busy |
| 438 | * regardless of whether the sub mounts are busy. |
| 439 | * |
| 440 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 441 | * give false negatives. The main reason why it's here is that we need |
| 442 | * a non-destructive way to look for easily umountable filesystems. |
| 443 | */ |
| 444 | int may_umount(struct vfsmount *mnt) |
| 445 | { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 446 | int ret = 0; |
| 447 | spin_lock(&vfsmount_lock); |
| 448 | if (propagate_mount_busy(mnt, 2)) |
| 449 | ret = -EBUSY; |
| 450 | spin_unlock(&vfsmount_lock); |
| 451 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 452 | } |
| 453 | |
| 454 | EXPORT_SYMBOL(may_umount); |
| 455 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 456 | void release_mounts(struct list_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 457 | { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 458 | struct vfsmount *mnt; |
Miklos Szeredi | bf066c7 | 2006-01-08 01:03:19 -0800 | [diff] [blame] | 459 | while (!list_empty(head)) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 460 | mnt = list_entry(head->next, struct vfsmount, mnt_hash); |
| 461 | list_del_init(&mnt->mnt_hash); |
| 462 | if (mnt->mnt_parent != mnt) { |
| 463 | struct dentry *dentry; |
| 464 | struct vfsmount *m; |
| 465 | spin_lock(&vfsmount_lock); |
| 466 | dentry = mnt->mnt_mountpoint; |
| 467 | m = mnt->mnt_parent; |
| 468 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 469 | mnt->mnt_parent = mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 470 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 471 | dput(dentry); |
| 472 | mntput(m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 473 | } |
| 474 | mntput(mnt); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 475 | } |
| 476 | } |
| 477 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 478 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 479 | { |
| 480 | struct vfsmount *p; |
| 481 | |
| 482 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 483 | list_del(&p->mnt_hash); |
| 484 | list_add(&p->mnt_hash, kill); |
| 485 | } |
| 486 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 487 | if (propagate) |
| 488 | propagate_umount(kill); |
| 489 | |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 490 | list_for_each_entry(p, kill, mnt_hash) { |
| 491 | list_del_init(&p->mnt_expire); |
| 492 | list_del_init(&p->mnt_list); |
| 493 | __touch_namespace(p->mnt_namespace); |
| 494 | p->mnt_namespace = NULL; |
| 495 | list_del_init(&p->mnt_child); |
| 496 | if (p->mnt_parent != p) |
| 497 | mnt->mnt_mountpoint->d_mounted--; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 498 | change_mnt_propagation(p, MS_PRIVATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | } |
| 500 | } |
| 501 | |
| 502 | static int do_umount(struct vfsmount *mnt, int flags) |
| 503 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 504 | struct super_block *sb = mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 505 | int retval; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 506 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | |
| 508 | retval = security_sb_umount(mnt, flags); |
| 509 | if (retval) |
| 510 | return retval; |
| 511 | |
| 512 | /* |
| 513 | * Allow userspace to request a mountpoint be expired rather than |
| 514 | * unmounting unconditionally. Unmount only happens if: |
| 515 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 516 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 517 | */ |
| 518 | if (flags & MNT_EXPIRE) { |
| 519 | if (mnt == current->fs->rootmnt || |
| 520 | flags & (MNT_FORCE | MNT_DETACH)) |
| 521 | return -EINVAL; |
| 522 | |
| 523 | if (atomic_read(&mnt->mnt_count) != 2) |
| 524 | return -EBUSY; |
| 525 | |
| 526 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
| 527 | return -EAGAIN; |
| 528 | } |
| 529 | |
| 530 | /* |
| 531 | * If we may have to abort operations to get out of this |
| 532 | * mount, and they will themselves hold resources we must |
| 533 | * allow the fs to do things. In the Unix tradition of |
| 534 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 535 | * might fail to complete on the first run through as other tasks |
| 536 | * must return, and the like. Thats for the mount program to worry |
| 537 | * about for the moment. |
| 538 | */ |
| 539 | |
| 540 | lock_kernel(); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 541 | if ((flags & MNT_FORCE) && sb->s_op->umount_begin) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 542 | sb->s_op->umount_begin(sb); |
| 543 | unlock_kernel(); |
| 544 | |
| 545 | /* |
| 546 | * No sense to grab the lock for this test, but test itself looks |
| 547 | * somewhat bogus. Suggestions for better replacement? |
| 548 | * Ho-hum... In principle, we might treat that as umount + switch |
| 549 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 550 | * Actually it makes sense, especially if rootfs would contain a |
| 551 | * /reboot - static binary that would close all descriptors and |
| 552 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 553 | */ |
| 554 | if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { |
| 555 | /* |
| 556 | * Special case for "unmounting" root ... |
| 557 | * we just try to remount it readonly. |
| 558 | */ |
| 559 | down_write(&sb->s_umount); |
| 560 | if (!(sb->s_flags & MS_RDONLY)) { |
| 561 | lock_kernel(); |
| 562 | DQUOT_OFF(sb); |
| 563 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
| 564 | unlock_kernel(); |
| 565 | } |
| 566 | up_write(&sb->s_umount); |
| 567 | return retval; |
| 568 | } |
| 569 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 570 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 571 | spin_lock(&vfsmount_lock); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 572 | event++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 573 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 574 | retval = -EBUSY; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 575 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 576 | if (!list_empty(&mnt->mnt_list)) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 577 | umount_tree(mnt, 1, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 578 | retval = 0; |
| 579 | } |
| 580 | spin_unlock(&vfsmount_lock); |
| 581 | if (retval) |
| 582 | security_sb_umount_busy(mnt); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 583 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 584 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 585 | return retval; |
| 586 | } |
| 587 | |
| 588 | /* |
| 589 | * Now umount can handle mount points as well as block devices. |
| 590 | * This is important for filesystems which use unnamed block devices. |
| 591 | * |
| 592 | * We now support a flag for forced unmount like the other 'big iron' |
| 593 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 594 | */ |
| 595 | |
| 596 | asmlinkage long sys_umount(char __user * name, int flags) |
| 597 | { |
| 598 | struct nameidata nd; |
| 599 | int retval; |
| 600 | |
| 601 | retval = __user_walk(name, LOOKUP_FOLLOW, &nd); |
| 602 | if (retval) |
| 603 | goto out; |
| 604 | retval = -EINVAL; |
| 605 | if (nd.dentry != nd.mnt->mnt_root) |
| 606 | goto dput_and_out; |
| 607 | if (!check_mnt(nd.mnt)) |
| 608 | goto dput_and_out; |
| 609 | |
| 610 | retval = -EPERM; |
| 611 | if (!capable(CAP_SYS_ADMIN)) |
| 612 | goto dput_and_out; |
| 613 | |
| 614 | retval = do_umount(nd.mnt, flags); |
| 615 | dput_and_out: |
| 616 | path_release_on_umount(&nd); |
| 617 | out: |
| 618 | return retval; |
| 619 | } |
| 620 | |
| 621 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 622 | |
| 623 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 624 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 625 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 626 | asmlinkage long sys_oldumount(char __user * name) |
| 627 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 628 | return sys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | } |
| 630 | |
| 631 | #endif |
| 632 | |
| 633 | static int mount_is_safe(struct nameidata *nd) |
| 634 | { |
| 635 | if (capable(CAP_SYS_ADMIN)) |
| 636 | return 0; |
| 637 | return -EPERM; |
| 638 | #ifdef notyet |
| 639 | if (S_ISLNK(nd->dentry->d_inode->i_mode)) |
| 640 | return -EPERM; |
| 641 | if (nd->dentry->d_inode->i_mode & S_ISVTX) { |
| 642 | if (current->uid != nd->dentry->d_inode->i_uid) |
| 643 | return -EPERM; |
| 644 | } |
Christoph Hellwig | e4543ed | 2005-11-08 21:35:04 -0800 | [diff] [blame] | 645 | if (vfs_permission(nd, MAY_WRITE)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 646 | return -EPERM; |
| 647 | return 0; |
| 648 | #endif |
| 649 | } |
| 650 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 651 | static int lives_below_in_same_fs(struct dentry *d, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 652 | { |
| 653 | while (1) { |
| 654 | if (d == dentry) |
| 655 | return 1; |
| 656 | if (d == NULL || d == d->d_parent) |
| 657 | return 0; |
| 658 | d = d->d_parent; |
| 659 | } |
| 660 | } |
| 661 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 662 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 663 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 664 | { |
| 665 | struct vfsmount *res, *p, *q, *r, *s; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 666 | struct nameidata nd; |
| 667 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 668 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
| 669 | return NULL; |
| 670 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 671 | res = q = clone_mnt(mnt, dentry, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 672 | if (!q) |
| 673 | goto Enomem; |
| 674 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
| 675 | |
| 676 | p = mnt; |
Domen Puncer | fdadd65 | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 677 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 678 | if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) |
| 679 | continue; |
| 680 | |
| 681 | for (s = r; s; s = next_mnt(s, r)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 682 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
| 683 | s = skip_mnt_tree(s); |
| 684 | continue; |
| 685 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 686 | while (p != s->mnt_parent) { |
| 687 | p = p->mnt_parent; |
| 688 | q = q->mnt_parent; |
| 689 | } |
| 690 | p = s; |
| 691 | nd.mnt = q; |
| 692 | nd.dentry = p->mnt_mountpoint; |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 693 | q = clone_mnt(p, p->mnt_root, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 694 | if (!q) |
| 695 | goto Enomem; |
| 696 | spin_lock(&vfsmount_lock); |
| 697 | list_add_tail(&q->mnt_list, &res->mnt_list); |
| 698 | attach_mnt(q, &nd); |
| 699 | spin_unlock(&vfsmount_lock); |
| 700 | } |
| 701 | } |
| 702 | return res; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 703 | Enomem: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 704 | if (res) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 705 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 706 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 707 | umount_tree(res, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 708 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 709 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 710 | } |
| 711 | return NULL; |
| 712 | } |
| 713 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 714 | /* |
| 715 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 716 | * @nd : place the mount tree @source_mnt is attached |
| 717 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 718 | * store the parent mount and mountpoint dentry. |
| 719 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 720 | * |
| 721 | * NOTE: in the table below explains the semantics when a source mount |
| 722 | * 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] | 723 | * --------------------------------------------------------------------------- |
| 724 | * | BIND MOUNT OPERATION | |
| 725 | * |************************************************************************** |
| 726 | * | source-->| shared | private | slave | unbindable | |
| 727 | * | dest | | | | | |
| 728 | * | | | | | | | |
| 729 | * | v | | | | | |
| 730 | * |************************************************************************** |
| 731 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 732 | * | | | | | | |
| 733 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 734 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 735 | * A bind operation clones the source mount and mounts the clone on the |
| 736 | * destination mount. |
| 737 | * |
| 738 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 739 | * tree of the destination mount and the cloned mount is added to |
| 740 | * the peer group of the source mount. |
| 741 | * (+) the cloned mount is created under the destination mount and is marked |
| 742 | * as shared. The cloned mount is added to the peer group of the source |
| 743 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 744 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 745 | * of the destination mount and the cloned mount is made slave |
| 746 | * of the same master as that of the source mount. The cloned mount |
| 747 | * is marked as 'shared and slave'. |
| 748 | * (*) the cloned mount is made a slave of the same master as that of the |
| 749 | * source mount. |
| 750 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 751 | * --------------------------------------------------------------------------- |
| 752 | * | MOVE MOUNT OPERATION | |
| 753 | * |************************************************************************** |
| 754 | * | source-->| shared | private | slave | unbindable | |
| 755 | * | dest | | | | | |
| 756 | * | | | | | | | |
| 757 | * | v | | | | | |
| 758 | * |************************************************************************** |
| 759 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 760 | * | | | | | | |
| 761 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 762 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 763 | * |
| 764 | * (+) the mount is moved to the destination. And is then propagated to |
| 765 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 766 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 767 | * (+++) the mount is moved to the destination and is then propagated to |
| 768 | * all the mounts belonging to the destination mount's propagation tree. |
| 769 | * the mount is marked as 'shared and slave'. |
| 770 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 771 | * |
| 772 | * if the source mount is a tree, the operations explained above is |
| 773 | * applied to each mount in the tree. |
| 774 | * Must be called without spinlocks held, since this function can sleep |
| 775 | * in allocations. |
| 776 | */ |
| 777 | static int attach_recursive_mnt(struct vfsmount *source_mnt, |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 778 | struct nameidata *nd, struct nameidata *parent_nd) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 779 | { |
| 780 | LIST_HEAD(tree_list); |
| 781 | struct vfsmount *dest_mnt = nd->mnt; |
| 782 | struct dentry *dest_dentry = nd->dentry; |
| 783 | struct vfsmount *child, *p; |
| 784 | |
| 785 | if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) |
| 786 | return -EINVAL; |
| 787 | |
| 788 | if (IS_MNT_SHARED(dest_mnt)) { |
| 789 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
| 790 | set_mnt_shared(p); |
| 791 | } |
| 792 | |
| 793 | spin_lock(&vfsmount_lock); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 794 | if (parent_nd) { |
| 795 | detach_mnt(source_mnt, parent_nd); |
| 796 | attach_mnt(source_mnt, nd); |
| 797 | touch_namespace(current->namespace); |
| 798 | } else { |
| 799 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
| 800 | commit_tree(source_mnt); |
| 801 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 802 | |
| 803 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
| 804 | list_del_init(&child->mnt_hash); |
| 805 | commit_tree(child); |
| 806 | } |
| 807 | spin_unlock(&vfsmount_lock); |
| 808 | return 0; |
| 809 | } |
| 810 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 811 | static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) |
| 812 | { |
| 813 | int err; |
| 814 | if (mnt->mnt_sb->s_flags & MS_NOUSER) |
| 815 | return -EINVAL; |
| 816 | |
| 817 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != |
| 818 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
| 819 | return -ENOTDIR; |
| 820 | |
| 821 | err = -ENOENT; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 822 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 823 | if (IS_DEADDIR(nd->dentry->d_inode)) |
| 824 | goto out_unlock; |
| 825 | |
| 826 | err = security_sb_check_sb(mnt, nd); |
| 827 | if (err) |
| 828 | goto out_unlock; |
| 829 | |
| 830 | err = -ENOENT; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 831 | if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 832 | err = attach_recursive_mnt(mnt, nd, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 833 | out_unlock: |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 834 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 835 | if (!err) |
| 836 | security_sb_post_addmount(mnt, nd); |
| 837 | return err; |
| 838 | } |
| 839 | |
| 840 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 841 | * recursively change the type of the mountpoint. |
| 842 | */ |
| 843 | static int do_change_type(struct nameidata *nd, int flag) |
| 844 | { |
| 845 | struct vfsmount *m, *mnt = nd->mnt; |
| 846 | int recurse = flag & MS_REC; |
| 847 | int type = flag & ~MS_REC; |
| 848 | |
| 849 | if (nd->dentry != nd->mnt->mnt_root) |
| 850 | return -EINVAL; |
| 851 | |
| 852 | down_write(&namespace_sem); |
| 853 | spin_lock(&vfsmount_lock); |
| 854 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
| 855 | change_mnt_propagation(m, type); |
| 856 | spin_unlock(&vfsmount_lock); |
| 857 | up_write(&namespace_sem); |
| 858 | return 0; |
| 859 | } |
| 860 | |
| 861 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 862 | * do loopback mount. |
| 863 | */ |
| 864 | static int do_loopback(struct nameidata *nd, char *old_name, int recurse) |
| 865 | { |
| 866 | struct nameidata old_nd; |
| 867 | struct vfsmount *mnt = NULL; |
| 868 | int err = mount_is_safe(nd); |
| 869 | if (err) |
| 870 | return err; |
| 871 | if (!old_name || !*old_name) |
| 872 | return -EINVAL; |
| 873 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); |
| 874 | if (err) |
| 875 | return err; |
| 876 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 877 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 878 | err = -EINVAL; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 879 | if (IS_MNT_UNBINDABLE(old_nd.mnt)) |
| 880 | goto out; |
| 881 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 882 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
| 883 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 884 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 885 | err = -ENOMEM; |
| 886 | if (recurse) |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 887 | mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 888 | else |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 889 | mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 890 | |
| 891 | if (!mnt) |
| 892 | goto out; |
| 893 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 894 | err = graft_tree(mnt, nd); |
| 895 | if (err) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 896 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 897 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 898 | umount_tree(mnt, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 899 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 900 | release_mounts(&umount_list); |
Ram Pai | 5b83d2c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 901 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 902 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 903 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 904 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 905 | path_release(&old_nd); |
| 906 | return err; |
| 907 | } |
| 908 | |
| 909 | /* |
| 910 | * change filesystem flags. dir should be a physical root of filesystem. |
| 911 | * If you've mounted a non-root directory somewhere and want to do remount |
| 912 | * on it - tough luck. |
| 913 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 914 | static int do_remount(struct nameidata *nd, int flags, int mnt_flags, |
| 915 | void *data) |
| 916 | { |
| 917 | int err; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 918 | struct super_block *sb = nd->mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 919 | |
| 920 | if (!capable(CAP_SYS_ADMIN)) |
| 921 | return -EPERM; |
| 922 | |
| 923 | if (!check_mnt(nd->mnt)) |
| 924 | return -EINVAL; |
| 925 | |
| 926 | if (nd->dentry != nd->mnt->mnt_root) |
| 927 | return -EINVAL; |
| 928 | |
| 929 | down_write(&sb->s_umount); |
| 930 | err = do_remount_sb(sb, flags, data, 0); |
| 931 | if (!err) |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 932 | nd->mnt->mnt_flags = mnt_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 933 | up_write(&sb->s_umount); |
| 934 | if (!err) |
| 935 | security_sb_post_remount(nd->mnt, flags, data); |
| 936 | return err; |
| 937 | } |
| 938 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 939 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
| 940 | { |
| 941 | struct vfsmount *p; |
| 942 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 943 | if (IS_MNT_UNBINDABLE(p)) |
| 944 | return 1; |
| 945 | } |
| 946 | return 0; |
| 947 | } |
| 948 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 949 | static int do_move_mount(struct nameidata *nd, char *old_name) |
| 950 | { |
| 951 | struct nameidata old_nd, parent_nd; |
| 952 | struct vfsmount *p; |
| 953 | int err = 0; |
| 954 | if (!capable(CAP_SYS_ADMIN)) |
| 955 | return -EPERM; |
| 956 | if (!old_name || !*old_name) |
| 957 | return -EINVAL; |
| 958 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); |
| 959 | if (err) |
| 960 | return err; |
| 961 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 962 | down_write(&namespace_sem); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 963 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 964 | ; |
| 965 | err = -EINVAL; |
| 966 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
| 967 | goto out; |
| 968 | |
| 969 | err = -ENOENT; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 970 | mutex_lock(&nd->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 971 | if (IS_DEADDIR(nd->dentry->d_inode)) |
| 972 | goto out1; |
| 973 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 974 | if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 975 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 976 | |
| 977 | err = -EINVAL; |
| 978 | if (old_nd.dentry != old_nd.mnt->mnt_root) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 979 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 980 | |
| 981 | if (old_nd.mnt == old_nd.mnt->mnt_parent) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 982 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 983 | |
| 984 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != |
| 985 | S_ISDIR(old_nd.dentry->d_inode->i_mode)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 986 | goto out1; |
| 987 | /* |
| 988 | * Don't move a mount residing in a shared parent. |
| 989 | */ |
| 990 | if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) |
| 991 | goto out1; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 992 | /* |
| 993 | * Don't move a mount tree containing unbindable mounts to a destination |
| 994 | * mount which is shared. |
| 995 | */ |
| 996 | if (IS_MNT_SHARED(nd->mnt) && tree_contains_unbindable(old_nd.mnt)) |
| 997 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 998 | err = -ELOOP; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 999 | for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1000 | if (p == old_nd.mnt) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1001 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1002 | |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1003 | if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) |
| 1004 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1005 | |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1006 | spin_lock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1007 | /* if the mount is moved, it should no longer be expire |
| 1008 | * automatically */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1009 | list_del_init(&old_nd.mnt->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1010 | spin_unlock(&vfsmount_lock); |
| 1011 | out1: |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1012 | mutex_unlock(&nd->dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1013 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1014 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1015 | if (!err) |
| 1016 | path_release(&parent_nd); |
| 1017 | path_release(&old_nd); |
| 1018 | return err; |
| 1019 | } |
| 1020 | |
| 1021 | /* |
| 1022 | * create a new mount for userspace and request it to be added into the |
| 1023 | * namespace's tree |
| 1024 | */ |
| 1025 | static int do_new_mount(struct nameidata *nd, char *type, int flags, |
| 1026 | int mnt_flags, char *name, void *data) |
| 1027 | { |
| 1028 | struct vfsmount *mnt; |
| 1029 | |
| 1030 | if (!type || !memchr(type, 0, PAGE_SIZE)) |
| 1031 | return -EINVAL; |
| 1032 | |
| 1033 | /* we need capabilities... */ |
| 1034 | if (!capable(CAP_SYS_ADMIN)) |
| 1035 | return -EPERM; |
| 1036 | |
| 1037 | mnt = do_kern_mount(type, flags, name, data); |
| 1038 | if (IS_ERR(mnt)) |
| 1039 | return PTR_ERR(mnt); |
| 1040 | |
| 1041 | return do_add_mount(mnt, nd, mnt_flags, NULL); |
| 1042 | } |
| 1043 | |
| 1044 | /* |
| 1045 | * add a mount into a namespace's mount tree |
| 1046 | * - provide the option of adding the new mount to an expiration list |
| 1047 | */ |
| 1048 | int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, |
| 1049 | int mnt_flags, struct list_head *fslist) |
| 1050 | { |
| 1051 | int err; |
| 1052 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1053 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1054 | /* Something was mounted here while we slept */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1055 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1056 | ; |
| 1057 | err = -EINVAL; |
| 1058 | if (!check_mnt(nd->mnt)) |
| 1059 | goto unlock; |
| 1060 | |
| 1061 | /* Refuse the same filesystem on the same mount point */ |
| 1062 | err = -EBUSY; |
| 1063 | if (nd->mnt->mnt_sb == newmnt->mnt_sb && |
| 1064 | nd->mnt->mnt_root == nd->dentry) |
| 1065 | goto unlock; |
| 1066 | |
| 1067 | err = -EINVAL; |
| 1068 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) |
| 1069 | goto unlock; |
| 1070 | |
| 1071 | newmnt->mnt_flags = mnt_flags; |
Ram Pai | 5b83d2c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1072 | if ((err = graft_tree(newmnt, nd))) |
| 1073 | goto unlock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1074 | |
Ram Pai | 5b83d2c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1075 | if (fslist) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1076 | /* add to the specified expiration list */ |
| 1077 | spin_lock(&vfsmount_lock); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1078 | list_add_tail(&newmnt->mnt_expire, fslist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1079 | spin_unlock(&vfsmount_lock); |
| 1080 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1081 | up_write(&namespace_sem); |
Ram Pai | 5b83d2c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1082 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1083 | |
| 1084 | unlock: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1085 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1086 | mntput(newmnt); |
| 1087 | return err; |
| 1088 | } |
| 1089 | |
| 1090 | EXPORT_SYMBOL_GPL(do_add_mount); |
| 1091 | |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1092 | static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, |
| 1093 | struct list_head *umounts) |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1094 | { |
| 1095 | spin_lock(&vfsmount_lock); |
| 1096 | |
| 1097 | /* |
Miklos Szeredi | ed42c87 | 2005-07-07 17:57:26 -0700 | [diff] [blame] | 1098 | * Check if mount is still attached, if not, let whoever holds it deal |
| 1099 | * with the sucker |
| 1100 | */ |
| 1101 | if (mnt->mnt_parent == mnt) { |
| 1102 | spin_unlock(&vfsmount_lock); |
| 1103 | return; |
| 1104 | } |
| 1105 | |
| 1106 | /* |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1107 | * Check that it is still dead: the count should now be 2 - as |
| 1108 | * contributed by the vfsmount parent and the mntget above |
| 1109 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1110 | if (!propagate_mount_busy(mnt, 2)) { |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1111 | /* delete from the namespace */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1112 | touch_namespace(mnt->mnt_namespace); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1113 | list_del_init(&mnt->mnt_list); |
Miklos Szeredi | ac08115 | 2005-07-07 17:57:27 -0700 | [diff] [blame] | 1114 | mnt->mnt_namespace = NULL; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1115 | umount_tree(mnt, 1, umounts); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1116 | spin_unlock(&vfsmount_lock); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1117 | } else { |
| 1118 | /* |
| 1119 | * Someone brought it back to life whilst we didn't have any |
| 1120 | * locks held so return it to the expiration list |
| 1121 | */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1122 | list_add_tail(&mnt->mnt_expire, mounts); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1123 | spin_unlock(&vfsmount_lock); |
| 1124 | } |
| 1125 | } |
| 1126 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1127 | /* |
| 1128 | * process a list of expirable mountpoints with the intent of discarding any |
| 1129 | * mountpoints that aren't in use and haven't been touched since last we came |
| 1130 | * here |
| 1131 | */ |
| 1132 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 1133 | { |
| 1134 | struct namespace *namespace; |
| 1135 | struct vfsmount *mnt, *next; |
| 1136 | LIST_HEAD(graveyard); |
| 1137 | |
| 1138 | if (list_empty(mounts)) |
| 1139 | return; |
| 1140 | |
| 1141 | spin_lock(&vfsmount_lock); |
| 1142 | |
| 1143 | /* extract from the expiration list every vfsmount that matches the |
| 1144 | * following criteria: |
| 1145 | * - only referenced by its parent vfsmount |
| 1146 | * - still marked for expiry (marked on the last call here; marks are |
| 1147 | * cleared by mntput()) |
| 1148 | */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1149 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1150 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
| 1151 | atomic_read(&mnt->mnt_count) != 1) |
| 1152 | continue; |
| 1153 | |
| 1154 | mntget(mnt); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1155 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1156 | } |
| 1157 | |
| 1158 | /* |
| 1159 | * go through the vfsmounts we've just consigned to the graveyard to |
| 1160 | * - check that they're still dead |
| 1161 | * - delete the vfsmount from the appropriate namespace under lock |
| 1162 | * - dispose of the corpse |
| 1163 | */ |
| 1164 | while (!list_empty(&graveyard)) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1165 | LIST_HEAD(umounts); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1166 | mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); |
| 1167 | list_del_init(&mnt->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1168 | |
| 1169 | /* don't do anything if the namespace is dead - all the |
| 1170 | * vfsmounts from it are going away anyway */ |
| 1171 | namespace = mnt->mnt_namespace; |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1172 | if (!namespace || !namespace->root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1173 | continue; |
| 1174 | get_namespace(namespace); |
| 1175 | |
| 1176 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1177 | down_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1178 | expire_mount(mnt, mounts, &umounts); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1179 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1180 | release_mounts(&umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1181 | mntput(mnt); |
| 1182 | put_namespace(namespace); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1183 | spin_lock(&vfsmount_lock); |
| 1184 | } |
| 1185 | |
| 1186 | spin_unlock(&vfsmount_lock); |
| 1187 | } |
| 1188 | |
| 1189 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 1190 | |
| 1191 | /* |
| 1192 | * Some copy_from_user() implementations do not return the exact number of |
| 1193 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 1194 | * Note that this function differs from copy_from_user() in that it will oops |
| 1195 | * on bad values of `to', rather than returning a short copy. |
| 1196 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1197 | static long exact_copy_from_user(void *to, const void __user * from, |
| 1198 | unsigned long n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1199 | { |
| 1200 | char *t = to; |
| 1201 | const char __user *f = from; |
| 1202 | char c; |
| 1203 | |
| 1204 | if (!access_ok(VERIFY_READ, from, n)) |
| 1205 | return n; |
| 1206 | |
| 1207 | while (n) { |
| 1208 | if (__get_user(c, f)) { |
| 1209 | memset(t, 0, n); |
| 1210 | break; |
| 1211 | } |
| 1212 | *t++ = c; |
| 1213 | f++; |
| 1214 | n--; |
| 1215 | } |
| 1216 | return n; |
| 1217 | } |
| 1218 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1219 | int copy_mount_options(const void __user * data, unsigned long *where) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1220 | { |
| 1221 | int i; |
| 1222 | unsigned long page; |
| 1223 | unsigned long size; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1224 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1225 | *where = 0; |
| 1226 | if (!data) |
| 1227 | return 0; |
| 1228 | |
| 1229 | if (!(page = __get_free_page(GFP_KERNEL))) |
| 1230 | return -ENOMEM; |
| 1231 | |
| 1232 | /* We only care that *some* data at the address the user |
| 1233 | * gave us is valid. Just in case, we'll zero |
| 1234 | * the remainder of the page. |
| 1235 | */ |
| 1236 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 1237 | size = TASK_SIZE - (unsigned long)data; |
| 1238 | if (size > PAGE_SIZE) |
| 1239 | size = PAGE_SIZE; |
| 1240 | |
| 1241 | i = size - exact_copy_from_user((void *)page, data, size); |
| 1242 | if (!i) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1243 | free_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1244 | return -EFAULT; |
| 1245 | } |
| 1246 | if (i != PAGE_SIZE) |
| 1247 | memset((char *)page + i, 0, PAGE_SIZE - i); |
| 1248 | *where = page; |
| 1249 | return 0; |
| 1250 | } |
| 1251 | |
| 1252 | /* |
| 1253 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 1254 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 1255 | * |
| 1256 | * data is a (void *) that can point to any structure up to |
| 1257 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 1258 | * information (or be NULL). |
| 1259 | * |
| 1260 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 1261 | * When the flags word was introduced its top half was required |
| 1262 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 1263 | * Therefore, if this magic number is present, it carries no information |
| 1264 | * and must be discarded. |
| 1265 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1266 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1267 | unsigned long flags, void *data_page) |
| 1268 | { |
| 1269 | struct nameidata nd; |
| 1270 | int retval = 0; |
| 1271 | int mnt_flags = 0; |
| 1272 | |
| 1273 | /* Discard magic */ |
| 1274 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 1275 | flags &= ~MS_MGC_MSK; |
| 1276 | |
| 1277 | /* Basic sanity checks */ |
| 1278 | |
| 1279 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) |
| 1280 | return -EINVAL; |
| 1281 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) |
| 1282 | return -EINVAL; |
| 1283 | |
| 1284 | if (data_page) |
| 1285 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 1286 | |
| 1287 | /* Separate the per-mountpoint flags */ |
| 1288 | if (flags & MS_NOSUID) |
| 1289 | mnt_flags |= MNT_NOSUID; |
| 1290 | if (flags & MS_NODEV) |
| 1291 | mnt_flags |= MNT_NODEV; |
| 1292 | if (flags & MS_NOEXEC) |
| 1293 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 1294 | if (flags & MS_NOATIME) |
| 1295 | mnt_flags |= MNT_NOATIME; |
| 1296 | if (flags & MS_NODIRATIME) |
| 1297 | mnt_flags |= MNT_NODIRATIME; |
| 1298 | |
| 1299 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | |
| 1300 | MS_NOATIME | MS_NODIRATIME); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1301 | |
| 1302 | /* ... and get the mountpoint */ |
| 1303 | retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); |
| 1304 | if (retval) |
| 1305 | return retval; |
| 1306 | |
| 1307 | retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); |
| 1308 | if (retval) |
| 1309 | goto dput_out; |
| 1310 | |
| 1311 | if (flags & MS_REMOUNT) |
| 1312 | retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, |
| 1313 | data_page); |
| 1314 | else if (flags & MS_BIND) |
| 1315 | retval = do_loopback(&nd, dev_name, flags & MS_REC); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1316 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1317 | retval = do_change_type(&nd, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1318 | else if (flags & MS_MOVE) |
| 1319 | retval = do_move_mount(&nd, dev_name); |
| 1320 | else |
| 1321 | retval = do_new_mount(&nd, type_page, flags, mnt_flags, |
| 1322 | dev_name, data_page); |
| 1323 | dput_out: |
| 1324 | path_release(&nd); |
| 1325 | return retval; |
| 1326 | } |
| 1327 | |
| 1328 | int copy_namespace(int flags, struct task_struct *tsk) |
| 1329 | { |
| 1330 | struct namespace *namespace = tsk->namespace; |
| 1331 | struct namespace *new_ns; |
| 1332 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; |
| 1333 | struct fs_struct *fs = tsk->fs; |
| 1334 | struct vfsmount *p, *q; |
| 1335 | |
| 1336 | if (!namespace) |
| 1337 | return 0; |
| 1338 | |
| 1339 | get_namespace(namespace); |
| 1340 | |
| 1341 | if (!(flags & CLONE_NEWNS)) |
| 1342 | return 0; |
| 1343 | |
| 1344 | if (!capable(CAP_SYS_ADMIN)) { |
| 1345 | put_namespace(namespace); |
| 1346 | return -EPERM; |
| 1347 | } |
| 1348 | |
| 1349 | new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); |
| 1350 | if (!new_ns) |
| 1351 | goto out; |
| 1352 | |
| 1353 | atomic_set(&new_ns->count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1354 | INIT_LIST_HEAD(&new_ns->list); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1355 | init_waitqueue_head(&new_ns->poll); |
| 1356 | new_ns->event = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1357 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1358 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1359 | /* First pass: copy the tree topology */ |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1360 | new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1361 | CL_COPY_ALL | CL_EXPIRE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1362 | if (!new_ns->root) { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1363 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | kfree(new_ns); |
| 1365 | goto out; |
| 1366 | } |
| 1367 | spin_lock(&vfsmount_lock); |
| 1368 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
| 1369 | spin_unlock(&vfsmount_lock); |
| 1370 | |
| 1371 | /* |
| 1372 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 1373 | * as belonging to new namespace. We have already acquired a private |
| 1374 | * fs_struct, so tsk->fs->lock is not needed. |
| 1375 | */ |
| 1376 | p = namespace->root; |
| 1377 | q = new_ns->root; |
| 1378 | while (p) { |
| 1379 | q->mnt_namespace = new_ns; |
| 1380 | if (fs) { |
| 1381 | if (p == fs->rootmnt) { |
| 1382 | rootmnt = p; |
| 1383 | fs->rootmnt = mntget(q); |
| 1384 | } |
| 1385 | if (p == fs->pwdmnt) { |
| 1386 | pwdmnt = p; |
| 1387 | fs->pwdmnt = mntget(q); |
| 1388 | } |
| 1389 | if (p == fs->altrootmnt) { |
| 1390 | altrootmnt = p; |
| 1391 | fs->altrootmnt = mntget(q); |
| 1392 | } |
| 1393 | } |
| 1394 | p = next_mnt(p, namespace->root); |
| 1395 | q = next_mnt(q, new_ns->root); |
| 1396 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1397 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1398 | |
| 1399 | tsk->namespace = new_ns; |
| 1400 | |
| 1401 | if (rootmnt) |
| 1402 | mntput(rootmnt); |
| 1403 | if (pwdmnt) |
| 1404 | mntput(pwdmnt); |
| 1405 | if (altrootmnt) |
| 1406 | mntput(altrootmnt); |
| 1407 | |
| 1408 | put_namespace(namespace); |
| 1409 | return 0; |
| 1410 | |
| 1411 | out: |
| 1412 | put_namespace(namespace); |
| 1413 | return -ENOMEM; |
| 1414 | } |
| 1415 | |
| 1416 | asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, |
| 1417 | char __user * type, unsigned long flags, |
| 1418 | void __user * data) |
| 1419 | { |
| 1420 | int retval; |
| 1421 | unsigned long data_page; |
| 1422 | unsigned long type_page; |
| 1423 | unsigned long dev_page; |
| 1424 | char *dir_page; |
| 1425 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1426 | retval = copy_mount_options(type, &type_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1427 | if (retval < 0) |
| 1428 | return retval; |
| 1429 | |
| 1430 | dir_page = getname(dir_name); |
| 1431 | retval = PTR_ERR(dir_page); |
| 1432 | if (IS_ERR(dir_page)) |
| 1433 | goto out1; |
| 1434 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1435 | retval = copy_mount_options(dev_name, &dev_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1436 | if (retval < 0) |
| 1437 | goto out2; |
| 1438 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1439 | retval = copy_mount_options(data, &data_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1440 | if (retval < 0) |
| 1441 | goto out3; |
| 1442 | |
| 1443 | lock_kernel(); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1444 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
| 1445 | flags, (void *)data_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1446 | unlock_kernel(); |
| 1447 | free_page(data_page); |
| 1448 | |
| 1449 | out3: |
| 1450 | free_page(dev_page); |
| 1451 | out2: |
| 1452 | putname(dir_page); |
| 1453 | out1: |
| 1454 | free_page(type_page); |
| 1455 | return retval; |
| 1456 | } |
| 1457 | |
| 1458 | /* |
| 1459 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. |
| 1460 | * It can block. Requires the big lock held. |
| 1461 | */ |
| 1462 | void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, |
| 1463 | struct dentry *dentry) |
| 1464 | { |
| 1465 | struct dentry *old_root; |
| 1466 | struct vfsmount *old_rootmnt; |
| 1467 | write_lock(&fs->lock); |
| 1468 | old_root = fs->root; |
| 1469 | old_rootmnt = fs->rootmnt; |
| 1470 | fs->rootmnt = mntget(mnt); |
| 1471 | fs->root = dget(dentry); |
| 1472 | write_unlock(&fs->lock); |
| 1473 | if (old_root) { |
| 1474 | dput(old_root); |
| 1475 | mntput(old_rootmnt); |
| 1476 | } |
| 1477 | } |
| 1478 | |
| 1479 | /* |
| 1480 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. |
| 1481 | * It can block. Requires the big lock held. |
| 1482 | */ |
| 1483 | void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, |
| 1484 | struct dentry *dentry) |
| 1485 | { |
| 1486 | struct dentry *old_pwd; |
| 1487 | struct vfsmount *old_pwdmnt; |
| 1488 | |
| 1489 | write_lock(&fs->lock); |
| 1490 | old_pwd = fs->pwd; |
| 1491 | old_pwdmnt = fs->pwdmnt; |
| 1492 | fs->pwdmnt = mntget(mnt); |
| 1493 | fs->pwd = dget(dentry); |
| 1494 | write_unlock(&fs->lock); |
| 1495 | |
| 1496 | if (old_pwd) { |
| 1497 | dput(old_pwd); |
| 1498 | mntput(old_pwdmnt); |
| 1499 | } |
| 1500 | } |
| 1501 | |
| 1502 | static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) |
| 1503 | { |
| 1504 | struct task_struct *g, *p; |
| 1505 | struct fs_struct *fs; |
| 1506 | |
| 1507 | read_lock(&tasklist_lock); |
| 1508 | do_each_thread(g, p) { |
| 1509 | task_lock(p); |
| 1510 | fs = p->fs; |
| 1511 | if (fs) { |
| 1512 | atomic_inc(&fs->count); |
| 1513 | task_unlock(p); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1514 | if (fs->root == old_nd->dentry |
| 1515 | && fs->rootmnt == old_nd->mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1516 | set_fs_root(fs, new_nd->mnt, new_nd->dentry); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1517 | if (fs->pwd == old_nd->dentry |
| 1518 | && fs->pwdmnt == old_nd->mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1519 | set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); |
| 1520 | put_fs_struct(fs); |
| 1521 | } else |
| 1522 | task_unlock(p); |
| 1523 | } while_each_thread(g, p); |
| 1524 | read_unlock(&tasklist_lock); |
| 1525 | } |
| 1526 | |
| 1527 | /* |
| 1528 | * pivot_root Semantics: |
| 1529 | * Moves the root file system of the current process to the directory put_old, |
| 1530 | * makes new_root as the new root file system of the current process, and sets |
| 1531 | * root/cwd of all processes which had them on the current root to new_root. |
| 1532 | * |
| 1533 | * Restrictions: |
| 1534 | * The new_root and put_old must be directories, and must not be on the |
| 1535 | * same file system as the current process root. The put_old must be |
| 1536 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 1537 | * pointed to by put_old must yield the same directory as new_root. No other |
| 1538 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 1539 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 1540 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
| 1541 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives |
| 1542 | * in this situation. |
| 1543 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1544 | * Notes: |
| 1545 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 1546 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 1547 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 1548 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 1549 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 1550 | * first. |
| 1551 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1552 | asmlinkage long sys_pivot_root(const char __user * new_root, |
| 1553 | const char __user * put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1554 | { |
| 1555 | struct vfsmount *tmp; |
| 1556 | struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; |
| 1557 | int error; |
| 1558 | |
| 1559 | if (!capable(CAP_SYS_ADMIN)) |
| 1560 | return -EPERM; |
| 1561 | |
| 1562 | lock_kernel(); |
| 1563 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1564 | error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, |
| 1565 | &new_nd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1566 | if (error) |
| 1567 | goto out0; |
| 1568 | error = -EINVAL; |
| 1569 | if (!check_mnt(new_nd.mnt)) |
| 1570 | goto out1; |
| 1571 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1572 | error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1573 | if (error) |
| 1574 | goto out1; |
| 1575 | |
| 1576 | error = security_sb_pivotroot(&old_nd, &new_nd); |
| 1577 | if (error) { |
| 1578 | path_release(&old_nd); |
| 1579 | goto out1; |
| 1580 | } |
| 1581 | |
| 1582 | read_lock(¤t->fs->lock); |
| 1583 | user_nd.mnt = mntget(current->fs->rootmnt); |
| 1584 | user_nd.dentry = dget(current->fs->root); |
| 1585 | read_unlock(¤t->fs->lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1586 | down_write(&namespace_sem); |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1587 | mutex_lock(&old_nd.dentry->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1588 | error = -EINVAL; |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1589 | if (IS_MNT_SHARED(old_nd.mnt) || |
| 1590 | IS_MNT_SHARED(new_nd.mnt->mnt_parent) || |
| 1591 | IS_MNT_SHARED(user_nd.mnt->mnt_parent)) |
| 1592 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1593 | if (!check_mnt(user_nd.mnt)) |
| 1594 | goto out2; |
| 1595 | error = -ENOENT; |
| 1596 | if (IS_DEADDIR(new_nd.dentry->d_inode)) |
| 1597 | goto out2; |
| 1598 | if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) |
| 1599 | goto out2; |
| 1600 | if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) |
| 1601 | goto out2; |
| 1602 | error = -EBUSY; |
| 1603 | if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) |
| 1604 | goto out2; /* loop, on the same file system */ |
| 1605 | error = -EINVAL; |
| 1606 | if (user_nd.mnt->mnt_root != user_nd.dentry) |
| 1607 | goto out2; /* not a mountpoint */ |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 1608 | if (user_nd.mnt->mnt_parent == user_nd.mnt) |
| 1609 | goto out2; /* not attached */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1610 | if (new_nd.mnt->mnt_root != new_nd.dentry) |
| 1611 | goto out2; /* not a mountpoint */ |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 1612 | if (new_nd.mnt->mnt_parent == new_nd.mnt) |
| 1613 | goto out2; /* not attached */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1614 | tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ |
| 1615 | spin_lock(&vfsmount_lock); |
| 1616 | if (tmp != new_nd.mnt) { |
| 1617 | for (;;) { |
| 1618 | if (tmp->mnt_parent == tmp) |
| 1619 | goto out3; /* already mounted on put_old */ |
| 1620 | if (tmp->mnt_parent == new_nd.mnt) |
| 1621 | break; |
| 1622 | tmp = tmp->mnt_parent; |
| 1623 | } |
| 1624 | if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) |
| 1625 | goto out3; |
| 1626 | } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) |
| 1627 | goto out3; |
| 1628 | detach_mnt(new_nd.mnt, &parent_nd); |
| 1629 | detach_mnt(user_nd.mnt, &root_parent); |
| 1630 | attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ |
| 1631 | attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1632 | touch_namespace(current->namespace); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1633 | spin_unlock(&vfsmount_lock); |
| 1634 | chroot_fs_refs(&user_nd, &new_nd); |
| 1635 | security_sb_post_pivotroot(&user_nd, &new_nd); |
| 1636 | error = 0; |
| 1637 | path_release(&root_parent); |
| 1638 | path_release(&parent_nd); |
| 1639 | out2: |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 1640 | mutex_unlock(&old_nd.dentry->d_inode->i_mutex); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1641 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1642 | path_release(&user_nd); |
| 1643 | path_release(&old_nd); |
| 1644 | out1: |
| 1645 | path_release(&new_nd); |
| 1646 | out0: |
| 1647 | unlock_kernel(); |
| 1648 | return error; |
| 1649 | out3: |
| 1650 | spin_unlock(&vfsmount_lock); |
| 1651 | goto out2; |
| 1652 | } |
| 1653 | |
| 1654 | static void __init init_mount_tree(void) |
| 1655 | { |
| 1656 | struct vfsmount *mnt; |
| 1657 | struct namespace *namespace; |
| 1658 | struct task_struct *g, *p; |
| 1659 | |
| 1660 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); |
| 1661 | if (IS_ERR(mnt)) |
| 1662 | panic("Can't create rootfs"); |
| 1663 | namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); |
| 1664 | if (!namespace) |
| 1665 | panic("Can't allocate initial namespace"); |
| 1666 | atomic_set(&namespace->count, 1); |
| 1667 | INIT_LIST_HEAD(&namespace->list); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1668 | init_waitqueue_head(&namespace->poll); |
| 1669 | namespace->event = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1670 | list_add(&mnt->mnt_list, &namespace->list); |
| 1671 | namespace->root = mnt; |
| 1672 | mnt->mnt_namespace = namespace; |
| 1673 | |
| 1674 | init_task.namespace = namespace; |
| 1675 | read_lock(&tasklist_lock); |
| 1676 | do_each_thread(g, p) { |
| 1677 | get_namespace(namespace); |
| 1678 | p->namespace = namespace; |
| 1679 | } while_each_thread(g, p); |
| 1680 | read_unlock(&tasklist_lock); |
| 1681 | |
| 1682 | set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); |
| 1683 | set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); |
| 1684 | } |
| 1685 | |
| 1686 | void __init mnt_init(unsigned long mempages) |
| 1687 | { |
| 1688 | struct list_head *d; |
| 1689 | unsigned int nr_hash; |
| 1690 | int i; |
| 1691 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1692 | init_rwsem(&namespace_sem); |
| 1693 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1694 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1695 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1696 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1697 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1698 | |
| 1699 | if (!mount_hashtable) |
| 1700 | panic("Failed to allocate mount hash table\n"); |
| 1701 | |
| 1702 | /* |
| 1703 | * Find the power-of-two list-heads that can fit into the allocation.. |
| 1704 | * We don't guarantee that "sizeof(struct list_head)" is necessarily |
| 1705 | * a power-of-two. |
| 1706 | */ |
| 1707 | nr_hash = PAGE_SIZE / sizeof(struct list_head); |
| 1708 | hash_bits = 0; |
| 1709 | do { |
| 1710 | hash_bits++; |
| 1711 | } while ((nr_hash >> hash_bits) != 0); |
| 1712 | hash_bits--; |
| 1713 | |
| 1714 | /* |
| 1715 | * Re-calculate the actual number of entries and the mask |
| 1716 | * from the number of bits we can fit. |
| 1717 | */ |
| 1718 | nr_hash = 1UL << hash_bits; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1719 | hash_mask = nr_hash - 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1720 | |
| 1721 | printk("Mount-cache hash table entries: %d\n", nr_hash); |
| 1722 | |
| 1723 | /* And initialize the newly allocated array */ |
| 1724 | d = mount_hashtable; |
| 1725 | i = nr_hash; |
| 1726 | do { |
| 1727 | INIT_LIST_HEAD(d); |
| 1728 | d++; |
| 1729 | i--; |
| 1730 | } while (i); |
| 1731 | sysfs_init(); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 1732 | subsystem_register(&fs_subsys); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1733 | init_rootfs(); |
| 1734 | init_mount_tree(); |
| 1735 | } |
| 1736 | |
| 1737 | void __put_namespace(struct namespace *namespace) |
| 1738 | { |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1739 | struct vfsmount *root = namespace->root; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1740 | LIST_HEAD(umount_list); |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1741 | namespace->root = NULL; |
| 1742 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1743 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1744 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1745 | umount_tree(root, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1746 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1747 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1748 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1749 | kfree(namespace); |
| 1750 | } |