Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 1 | #include <linux/mount.h> |
| 2 | #include <linux/file.h> |
| 3 | #include <linux/fs.h> |
| 4 | #include <linux/proc_ns.h> |
| 5 | #include <linux/magic.h> |
| 6 | #include <linux/ktime.h> |
Eric W. Biederman | 75509fd | 2015-05-24 12:49:04 -0500 | [diff] [blame] | 7 | #include <linux/seq_file.h> |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 8 | #include <linux/user_namespace.h> |
| 9 | #include <linux/nsfs.h> |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 10 | |
| 11 | static struct vfsmount *nsfs_mnt; |
| 12 | |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 13 | static long ns_ioctl(struct file *filp, unsigned int ioctl, |
| 14 | unsigned long arg); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 15 | static const struct file_operations ns_file_operations = { |
| 16 | .llseek = no_llseek, |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 17 | .unlocked_ioctl = ns_ioctl, |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 18 | }; |
| 19 | |
| 20 | static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) |
| 21 | { |
David Howells | 75c3cfa | 2015-03-17 22:26:12 +0000 | [diff] [blame] | 22 | struct inode *inode = d_inode(dentry); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 23 | const struct proc_ns_operations *ns_ops = dentry->d_fsdata; |
| 24 | |
| 25 | return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]", |
| 26 | ns_ops->name, inode->i_ino); |
| 27 | } |
| 28 | |
| 29 | static void ns_prune_dentry(struct dentry *dentry) |
| 30 | { |
David Howells | 75c3cfa | 2015-03-17 22:26:12 +0000 | [diff] [blame] | 31 | struct inode *inode = d_inode(dentry); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 32 | if (inode) { |
| 33 | struct ns_common *ns = inode->i_private; |
| 34 | atomic_long_set(&ns->stashed, 0); |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | const struct dentry_operations ns_dentry_operations = |
| 39 | { |
| 40 | .d_prune = ns_prune_dentry, |
| 41 | .d_delete = always_delete_dentry, |
| 42 | .d_dname = ns_dname, |
| 43 | }; |
| 44 | |
| 45 | static void nsfs_evict(struct inode *inode) |
| 46 | { |
| 47 | struct ns_common *ns = inode->i_private; |
| 48 | clear_inode(inode); |
| 49 | ns->ops->put(ns); |
| 50 | } |
| 51 | |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 52 | static void *__ns_get_path(struct path *path, struct ns_common *ns) |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 53 | { |
| 54 | struct vfsmount *mnt = mntget(nsfs_mnt); |
| 55 | struct qstr qname = { .name = "", }; |
| 56 | struct dentry *dentry; |
| 57 | struct inode *inode; |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 58 | unsigned long d; |
| 59 | |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 60 | rcu_read_lock(); |
| 61 | d = atomic_long_read(&ns->stashed); |
| 62 | if (!d) |
| 63 | goto slow; |
| 64 | dentry = (struct dentry *)d; |
| 65 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
| 66 | goto slow; |
| 67 | rcu_read_unlock(); |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 68 | ns->ops->put(ns); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 69 | got_it: |
| 70 | path->mnt = mnt; |
| 71 | path->dentry = dentry; |
| 72 | return NULL; |
| 73 | slow: |
| 74 | rcu_read_unlock(); |
| 75 | inode = new_inode_pseudo(mnt->mnt_sb); |
| 76 | if (!inode) { |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 77 | ns->ops->put(ns); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 78 | mntput(mnt); |
| 79 | return ERR_PTR(-ENOMEM); |
| 80 | } |
| 81 | inode->i_ino = ns->inum; |
| 82 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
| 83 | inode->i_flags |= S_IMMUTABLE; |
| 84 | inode->i_mode = S_IFREG | S_IRUGO; |
| 85 | inode->i_fop = &ns_file_operations; |
| 86 | inode->i_private = ns; |
| 87 | |
| 88 | dentry = d_alloc_pseudo(mnt->mnt_sb, &qname); |
| 89 | if (!dentry) { |
| 90 | iput(inode); |
| 91 | mntput(mnt); |
| 92 | return ERR_PTR(-ENOMEM); |
| 93 | } |
| 94 | d_instantiate(dentry, inode); |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 95 | dentry->d_fsdata = (void *)ns->ops; |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 96 | d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry); |
| 97 | if (d) { |
| 98 | d_delete(dentry); /* make sure ->d_prune() does nothing */ |
| 99 | dput(dentry); |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 100 | mntput(mnt); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 101 | cpu_relax(); |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 102 | return ERR_PTR(-EAGAIN); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 103 | } |
| 104 | goto got_it; |
| 105 | } |
| 106 | |
Andrey Vagin | 6786741 | 2016-09-06 00:47:14 -0700 | [diff] [blame^] | 107 | void *ns_get_path(struct path *path, struct task_struct *task, |
| 108 | const struct proc_ns_operations *ns_ops) |
| 109 | { |
| 110 | struct ns_common *ns; |
| 111 | void *ret; |
| 112 | |
| 113 | again: |
| 114 | ns = ns_ops->get(task); |
| 115 | if (!ns) |
| 116 | return ERR_PTR(-ENOENT); |
| 117 | |
| 118 | ret = __ns_get_path(path, ns); |
| 119 | if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN) |
| 120 | goto again; |
| 121 | return ret; |
| 122 | } |
| 123 | |
| 124 | static int open_related_ns(struct ns_common *ns, |
| 125 | struct ns_common *(*get_ns)(struct ns_common *ns)) |
| 126 | { |
| 127 | struct path path = {}; |
| 128 | struct file *f; |
| 129 | void *err; |
| 130 | int fd; |
| 131 | |
| 132 | fd = get_unused_fd_flags(O_CLOEXEC); |
| 133 | if (fd < 0) |
| 134 | return fd; |
| 135 | |
| 136 | while (1) { |
| 137 | struct ns_common *relative; |
| 138 | |
| 139 | relative = get_ns(ns); |
| 140 | if (IS_ERR(relative)) { |
| 141 | put_unused_fd(fd); |
| 142 | return PTR_ERR(relative); |
| 143 | } |
| 144 | |
| 145 | err = __ns_get_path(&path, relative); |
| 146 | if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN) |
| 147 | continue; |
| 148 | break; |
| 149 | } |
| 150 | if (IS_ERR(err)) { |
| 151 | put_unused_fd(fd); |
| 152 | return PTR_ERR(err); |
| 153 | } |
| 154 | |
| 155 | f = dentry_open(&path, O_RDONLY, current_cred()); |
| 156 | path_put(&path); |
| 157 | if (IS_ERR(f)) { |
| 158 | put_unused_fd(fd); |
| 159 | fd = PTR_ERR(f); |
| 160 | } else |
| 161 | fd_install(fd, f); |
| 162 | |
| 163 | return fd; |
| 164 | } |
| 165 | |
| 166 | static long ns_ioctl(struct file *filp, unsigned int ioctl, |
| 167 | unsigned long arg) |
| 168 | { |
| 169 | struct ns_common *ns = get_proc_ns(file_inode(filp)); |
| 170 | |
| 171 | switch (ioctl) { |
| 172 | case NS_GET_USERNS: |
| 173 | return open_related_ns(ns, ns_get_owner); |
| 174 | default: |
| 175 | return -ENOTTY; |
| 176 | } |
| 177 | } |
| 178 | |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 179 | int ns_get_name(char *buf, size_t size, struct task_struct *task, |
| 180 | const struct proc_ns_operations *ns_ops) |
| 181 | { |
| 182 | struct ns_common *ns; |
| 183 | int res = -ENOENT; |
| 184 | ns = ns_ops->get(task); |
| 185 | if (ns) { |
| 186 | res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum); |
| 187 | ns_ops->put(ns); |
| 188 | } |
| 189 | return res; |
| 190 | } |
| 191 | |
| 192 | struct file *proc_ns_fget(int fd) |
| 193 | { |
| 194 | struct file *file; |
| 195 | |
| 196 | file = fget(fd); |
| 197 | if (!file) |
| 198 | return ERR_PTR(-EBADF); |
| 199 | |
| 200 | if (file->f_op != &ns_file_operations) |
| 201 | goto out_invalid; |
| 202 | |
| 203 | return file; |
| 204 | |
| 205 | out_invalid: |
| 206 | fput(file); |
| 207 | return ERR_PTR(-EINVAL); |
| 208 | } |
| 209 | |
Eric W. Biederman | 75509fd | 2015-05-24 12:49:04 -0500 | [diff] [blame] | 210 | static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry) |
| 211 | { |
| 212 | struct inode *inode = d_inode(dentry); |
| 213 | const struct proc_ns_operations *ns_ops = dentry->d_fsdata; |
| 214 | |
Joe Perches | 6798a8c | 2015-09-11 13:07:48 -0700 | [diff] [blame] | 215 | seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino); |
| 216 | return 0; |
Eric W. Biederman | 75509fd | 2015-05-24 12:49:04 -0500 | [diff] [blame] | 217 | } |
| 218 | |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 219 | static const struct super_operations nsfs_ops = { |
| 220 | .statfs = simple_statfs, |
| 221 | .evict_inode = nsfs_evict, |
Eric W. Biederman | 75509fd | 2015-05-24 12:49:04 -0500 | [diff] [blame] | 222 | .show_path = nsfs_show_path, |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 223 | }; |
| 224 | static struct dentry *nsfs_mount(struct file_system_type *fs_type, |
| 225 | int flags, const char *dev_name, void *data) |
| 226 | { |
| 227 | return mount_pseudo(fs_type, "nsfs:", &nsfs_ops, |
| 228 | &ns_dentry_operations, NSFS_MAGIC); |
| 229 | } |
| 230 | static struct file_system_type nsfs = { |
| 231 | .name = "nsfs", |
| 232 | .mount = nsfs_mount, |
| 233 | .kill_sb = kill_anon_super, |
| 234 | }; |
| 235 | |
| 236 | void __init nsfs_init(void) |
| 237 | { |
| 238 | nsfs_mnt = kern_mount(&nsfs); |
| 239 | if (IS_ERR(nsfs_mnt)) |
| 240 | panic("can't set nsfs up\n"); |
| 241 | nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER; |
| 242 | } |