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> |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/seq_file.h> |
| 21 | #include <linux/namespace.h> |
| 22 | #include <linux/namei.h> |
| 23 | #include <linux/security.h> |
| 24 | #include <linux/mount.h> |
| 25 | #include <asm/uaccess.h> |
| 26 | #include <asm/unistd.h> |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 27 | #include "pnode.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 28 | |
| 29 | extern int __init init_rootfs(void); |
| 30 | |
| 31 | #ifdef CONFIG_SYSFS |
| 32 | extern int __init sysfs_init(void); |
| 33 | #else |
| 34 | static inline int sysfs_init(void) |
| 35 | { |
| 36 | return 0; |
| 37 | } |
| 38 | #endif |
| 39 | |
| 40 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 41 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
| 42 | |
| 43 | static int event; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | |
| 45 | static struct list_head *mount_hashtable; |
Ravikiran G Thirumalai | 6c231b7 | 2005-09-06 15:17:45 -0700 | [diff] [blame] | 46 | static int hash_mask __read_mostly, hash_bits __read_mostly; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 47 | static kmem_cache_t *mnt_cache; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 48 | static struct rw_semaphore namespace_sem; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | |
| 50 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
| 51 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 52 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 53 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | tmp = tmp + (tmp >> hash_bits); |
| 55 | return tmp & hash_mask; |
| 56 | } |
| 57 | |
| 58 | struct vfsmount *alloc_vfsmnt(const char *name) |
| 59 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 60 | struct vfsmount *mnt = kmem_cache_alloc(mnt_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | if (mnt) { |
| 62 | memset(mnt, 0, sizeof(struct vfsmount)); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 63 | atomic_set(&mnt->mnt_count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | INIT_LIST_HEAD(&mnt->mnt_hash); |
| 65 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 66 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 67 | INIT_LIST_HEAD(&mnt->mnt_list); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 68 | INIT_LIST_HEAD(&mnt->mnt_expire); |
Ram Pai | 03e06e6 | 2005-11-07 17:19:33 -0500 | [diff] [blame] | 69 | INIT_LIST_HEAD(&mnt->mnt_share); |
Ram Pai | a58b0eb | 2005-11-07 17:20:48 -0500 | [diff] [blame^] | 70 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 71 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | if (name) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 73 | int size = strlen(name) + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | char *newname = kmalloc(size, GFP_KERNEL); |
| 75 | if (newname) { |
| 76 | memcpy(newname, name, size); |
| 77 | mnt->mnt_devname = newname; |
| 78 | } |
| 79 | } |
| 80 | } |
| 81 | return mnt; |
| 82 | } |
| 83 | |
| 84 | void free_vfsmnt(struct vfsmount *mnt) |
| 85 | { |
| 86 | kfree(mnt->mnt_devname); |
| 87 | kmem_cache_free(mnt_cache, mnt); |
| 88 | } |
| 89 | |
| 90 | /* |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 91 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
| 92 | * @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] | 93 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 94 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
| 95 | int dir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 97 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
| 98 | struct list_head *tmp = head; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | struct vfsmount *p, *found = NULL; |
| 100 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | for (;;) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 102 | tmp = dir ? tmp->next : tmp->prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | p = NULL; |
| 104 | if (tmp == head) |
| 105 | break; |
| 106 | p = list_entry(tmp, struct vfsmount, mnt_hash); |
| 107 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 108 | found = p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | break; |
| 110 | } |
| 111 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | return found; |
| 113 | } |
| 114 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 115 | /* |
| 116 | * lookup_mnt increments the ref count before returning |
| 117 | * the vfsmount struct. |
| 118 | */ |
| 119 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
| 120 | { |
| 121 | struct vfsmount *child_mnt; |
| 122 | spin_lock(&vfsmount_lock); |
| 123 | if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) |
| 124 | mntget(child_mnt); |
| 125 | spin_unlock(&vfsmount_lock); |
| 126 | return child_mnt; |
| 127 | } |
| 128 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | static inline int check_mnt(struct vfsmount *mnt) |
| 130 | { |
| 131 | return mnt->mnt_namespace == current->namespace; |
| 132 | } |
| 133 | |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 134 | static void touch_namespace(struct namespace *ns) |
| 135 | { |
| 136 | if (ns) { |
| 137 | ns->event = ++event; |
| 138 | wake_up_interruptible(&ns->poll); |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | static void __touch_namespace(struct namespace *ns) |
| 143 | { |
| 144 | if (ns && ns->event != event) { |
| 145 | ns->event = event; |
| 146 | wake_up_interruptible(&ns->poll); |
| 147 | } |
| 148 | } |
| 149 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 150 | static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) |
| 151 | { |
| 152 | old_nd->dentry = mnt->mnt_mountpoint; |
| 153 | old_nd->mnt = mnt->mnt_parent; |
| 154 | mnt->mnt_parent = mnt; |
| 155 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 156 | list_del_init(&mnt->mnt_child); |
| 157 | list_del_init(&mnt->mnt_hash); |
| 158 | old_nd->dentry->d_mounted--; |
| 159 | } |
| 160 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 161 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
| 162 | struct vfsmount *child_mnt) |
| 163 | { |
| 164 | child_mnt->mnt_parent = mntget(mnt); |
| 165 | child_mnt->mnt_mountpoint = dget(dentry); |
| 166 | dentry->d_mounted++; |
| 167 | } |
| 168 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) |
| 170 | { |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 171 | mnt_set_mountpoint(nd->mnt, nd->dentry, mnt); |
| 172 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 173 | hash(nd->mnt, nd->dentry)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 174 | list_add_tail(&mnt->mnt_child, &nd->mnt->mnt_mounts); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 175 | } |
| 176 | |
| 177 | /* |
| 178 | * the caller must hold vfsmount_lock |
| 179 | */ |
| 180 | static void commit_tree(struct vfsmount *mnt) |
| 181 | { |
| 182 | struct vfsmount *parent = mnt->mnt_parent; |
| 183 | struct vfsmount *m; |
| 184 | LIST_HEAD(head); |
| 185 | struct namespace *n = parent->mnt_namespace; |
| 186 | |
| 187 | BUG_ON(parent == mnt); |
| 188 | |
| 189 | list_add_tail(&head, &mnt->mnt_list); |
| 190 | list_for_each_entry(m, &head, mnt_list) |
| 191 | m->mnt_namespace = n; |
| 192 | list_splice(&head, n->list.prev); |
| 193 | |
| 194 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 195 | hash(parent, mnt->mnt_mountpoint)); |
| 196 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 197 | touch_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | } |
| 199 | |
| 200 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) |
| 201 | { |
| 202 | struct list_head *next = p->mnt_mounts.next; |
| 203 | if (next == &p->mnt_mounts) { |
| 204 | while (1) { |
| 205 | if (p == root) |
| 206 | return NULL; |
| 207 | next = p->mnt_child.next; |
| 208 | if (next != &p->mnt_parent->mnt_mounts) |
| 209 | break; |
| 210 | p = p->mnt_parent; |
| 211 | } |
| 212 | } |
| 213 | return list_entry(next, struct vfsmount, mnt_child); |
| 214 | } |
| 215 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 216 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
| 217 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | { |
| 219 | struct super_block *sb = old->mnt_sb; |
| 220 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); |
| 221 | |
| 222 | if (mnt) { |
| 223 | mnt->mnt_flags = old->mnt_flags; |
| 224 | atomic_inc(&sb->s_active); |
| 225 | mnt->mnt_sb = sb; |
| 226 | mnt->mnt_root = dget(root); |
| 227 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 228 | mnt->mnt_parent = mnt; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 229 | |
| 230 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) |
| 231 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 232 | if (flag & CL_MAKE_SHARED) |
| 233 | set_mnt_shared(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 234 | |
| 235 | /* stick the duplicate mount on the same expiry list |
| 236 | * as the original if that was on one */ |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 237 | if (flag & CL_EXPIRE) { |
| 238 | spin_lock(&vfsmount_lock); |
| 239 | if (!list_empty(&old->mnt_expire)) |
| 240 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 241 | spin_unlock(&vfsmount_lock); |
| 242 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 243 | } |
| 244 | return mnt; |
| 245 | } |
| 246 | |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 247 | static inline void __mntput(struct vfsmount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 248 | { |
| 249 | struct super_block *sb = mnt->mnt_sb; |
| 250 | dput(mnt->mnt_root); |
| 251 | free_vfsmnt(mnt); |
| 252 | deactivate_super(sb); |
| 253 | } |
| 254 | |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 255 | void mntput_no_expire(struct vfsmount *mnt) |
| 256 | { |
| 257 | repeat: |
| 258 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { |
| 259 | if (likely(!mnt->mnt_pinned)) { |
| 260 | spin_unlock(&vfsmount_lock); |
| 261 | __mntput(mnt); |
| 262 | return; |
| 263 | } |
| 264 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); |
| 265 | mnt->mnt_pinned = 0; |
| 266 | spin_unlock(&vfsmount_lock); |
| 267 | acct_auto_close_mnt(mnt); |
| 268 | security_sb_umount_close(mnt); |
| 269 | goto repeat; |
| 270 | } |
| 271 | } |
| 272 | |
| 273 | EXPORT_SYMBOL(mntput_no_expire); |
| 274 | |
| 275 | void mnt_pin(struct vfsmount *mnt) |
| 276 | { |
| 277 | spin_lock(&vfsmount_lock); |
| 278 | mnt->mnt_pinned++; |
| 279 | spin_unlock(&vfsmount_lock); |
| 280 | } |
| 281 | |
| 282 | EXPORT_SYMBOL(mnt_pin); |
| 283 | |
| 284 | void mnt_unpin(struct vfsmount *mnt) |
| 285 | { |
| 286 | spin_lock(&vfsmount_lock); |
| 287 | if (mnt->mnt_pinned) { |
| 288 | atomic_inc(&mnt->mnt_count); |
| 289 | mnt->mnt_pinned--; |
| 290 | } |
| 291 | spin_unlock(&vfsmount_lock); |
| 292 | } |
| 293 | |
| 294 | EXPORT_SYMBOL(mnt_unpin); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | |
| 296 | /* iterator */ |
| 297 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 298 | { |
| 299 | struct namespace *n = m->private; |
| 300 | struct list_head *p; |
| 301 | loff_t l = *pos; |
| 302 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 303 | down_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 304 | list_for_each(p, &n->list) |
| 305 | if (!l--) |
| 306 | return list_entry(p, struct vfsmount, mnt_list); |
| 307 | return NULL; |
| 308 | } |
| 309 | |
| 310 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 311 | { |
| 312 | struct namespace *n = m->private; |
| 313 | struct list_head *p = ((struct vfsmount *)v)->mnt_list.next; |
| 314 | (*pos)++; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 315 | return p == &n->list ? NULL : list_entry(p, struct vfsmount, mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 316 | } |
| 317 | |
| 318 | static void m_stop(struct seq_file *m, void *v) |
| 319 | { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 320 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 321 | } |
| 322 | |
| 323 | static inline void mangle(struct seq_file *m, const char *s) |
| 324 | { |
| 325 | seq_escape(m, s, " \t\n\\"); |
| 326 | } |
| 327 | |
| 328 | static int show_vfsmnt(struct seq_file *m, void *v) |
| 329 | { |
| 330 | struct vfsmount *mnt = v; |
| 331 | int err = 0; |
| 332 | static struct proc_fs_info { |
| 333 | int flag; |
| 334 | char *str; |
| 335 | } fs_info[] = { |
| 336 | { MS_SYNCHRONOUS, ",sync" }, |
| 337 | { MS_DIRSYNC, ",dirsync" }, |
| 338 | { MS_MANDLOCK, ",mand" }, |
| 339 | { MS_NOATIME, ",noatime" }, |
| 340 | { MS_NODIRATIME, ",nodiratime" }, |
| 341 | { 0, NULL } |
| 342 | }; |
| 343 | static struct proc_fs_info mnt_info[] = { |
| 344 | { MNT_NOSUID, ",nosuid" }, |
| 345 | { MNT_NODEV, ",nodev" }, |
| 346 | { MNT_NOEXEC, ",noexec" }, |
| 347 | { 0, NULL } |
| 348 | }; |
| 349 | struct proc_fs_info *fs_infop; |
| 350 | |
| 351 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 352 | seq_putc(m, ' '); |
| 353 | seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); |
| 354 | seq_putc(m, ' '); |
| 355 | mangle(m, mnt->mnt_sb->s_type->name); |
| 356 | seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
| 357 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { |
| 358 | if (mnt->mnt_sb->s_flags & fs_infop->flag) |
| 359 | seq_puts(m, fs_infop->str); |
| 360 | } |
| 361 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { |
| 362 | if (mnt->mnt_flags & fs_infop->flag) |
| 363 | seq_puts(m, fs_infop->str); |
| 364 | } |
| 365 | if (mnt->mnt_sb->s_op->show_options) |
| 366 | err = mnt->mnt_sb->s_op->show_options(m, mnt); |
| 367 | seq_puts(m, " 0 0\n"); |
| 368 | return err; |
| 369 | } |
| 370 | |
| 371 | struct seq_operations mounts_op = { |
| 372 | .start = m_start, |
| 373 | .next = m_next, |
| 374 | .stop = m_stop, |
| 375 | .show = show_vfsmnt |
| 376 | }; |
| 377 | |
| 378 | /** |
| 379 | * may_umount_tree - check if a mount tree is busy |
| 380 | * @mnt: root of mount tree |
| 381 | * |
| 382 | * This is called to check if a tree of mounts has any |
| 383 | * open files, pwds, chroots or sub mounts that are |
| 384 | * busy. |
| 385 | */ |
| 386 | int may_umount_tree(struct vfsmount *mnt) |
| 387 | { |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 388 | int actual_refs = 0; |
| 389 | int minimum_refs = 0; |
| 390 | struct vfsmount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 391 | |
| 392 | spin_lock(&vfsmount_lock); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 393 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 394 | actual_refs += atomic_read(&p->mnt_count); |
| 395 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 396 | } |
| 397 | spin_unlock(&vfsmount_lock); |
| 398 | |
| 399 | if (actual_refs > minimum_refs) |
| 400 | return -EBUSY; |
| 401 | |
| 402 | return 0; |
| 403 | } |
| 404 | |
| 405 | EXPORT_SYMBOL(may_umount_tree); |
| 406 | |
| 407 | /** |
| 408 | * may_umount - check if a mount point is busy |
| 409 | * @mnt: root of mount |
| 410 | * |
| 411 | * This is called to check if a mount point has any |
| 412 | * open files, pwds, chroots or sub mounts. If the |
| 413 | * mount has sub mounts this will return busy |
| 414 | * regardless of whether the sub mounts are busy. |
| 415 | * |
| 416 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 417 | * give false negatives. The main reason why it's here is that we need |
| 418 | * a non-destructive way to look for easily umountable filesystems. |
| 419 | */ |
| 420 | int may_umount(struct vfsmount *mnt) |
| 421 | { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 422 | int ret = 0; |
| 423 | spin_lock(&vfsmount_lock); |
| 424 | if (propagate_mount_busy(mnt, 2)) |
| 425 | ret = -EBUSY; |
| 426 | spin_unlock(&vfsmount_lock); |
| 427 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 428 | } |
| 429 | |
| 430 | EXPORT_SYMBOL(may_umount); |
| 431 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 432 | void release_mounts(struct list_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 433 | { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 434 | struct vfsmount *mnt; |
| 435 | while(!list_empty(head)) { |
| 436 | mnt = list_entry(head->next, struct vfsmount, mnt_hash); |
| 437 | list_del_init(&mnt->mnt_hash); |
| 438 | if (mnt->mnt_parent != mnt) { |
| 439 | struct dentry *dentry; |
| 440 | struct vfsmount *m; |
| 441 | spin_lock(&vfsmount_lock); |
| 442 | dentry = mnt->mnt_mountpoint; |
| 443 | m = mnt->mnt_parent; |
| 444 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 445 | mnt->mnt_parent = mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 446 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 447 | dput(dentry); |
| 448 | mntput(m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 449 | } |
| 450 | mntput(mnt); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 451 | } |
| 452 | } |
| 453 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 454 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 455 | { |
| 456 | struct vfsmount *p; |
| 457 | |
| 458 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 459 | list_del(&p->mnt_hash); |
| 460 | list_add(&p->mnt_hash, kill); |
| 461 | } |
| 462 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 463 | if (propagate) |
| 464 | propagate_umount(kill); |
| 465 | |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 466 | list_for_each_entry(p, kill, mnt_hash) { |
| 467 | list_del_init(&p->mnt_expire); |
| 468 | list_del_init(&p->mnt_list); |
| 469 | __touch_namespace(p->mnt_namespace); |
| 470 | p->mnt_namespace = NULL; |
| 471 | list_del_init(&p->mnt_child); |
| 472 | if (p->mnt_parent != p) |
| 473 | mnt->mnt_mountpoint->d_mounted--; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 474 | change_mnt_propagation(p, MS_PRIVATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 475 | } |
| 476 | } |
| 477 | |
| 478 | static int do_umount(struct vfsmount *mnt, int flags) |
| 479 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 480 | struct super_block *sb = mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 481 | int retval; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 482 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 483 | |
| 484 | retval = security_sb_umount(mnt, flags); |
| 485 | if (retval) |
| 486 | return retval; |
| 487 | |
| 488 | /* |
| 489 | * Allow userspace to request a mountpoint be expired rather than |
| 490 | * unmounting unconditionally. Unmount only happens if: |
| 491 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 492 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 493 | */ |
| 494 | if (flags & MNT_EXPIRE) { |
| 495 | if (mnt == current->fs->rootmnt || |
| 496 | flags & (MNT_FORCE | MNT_DETACH)) |
| 497 | return -EINVAL; |
| 498 | |
| 499 | if (atomic_read(&mnt->mnt_count) != 2) |
| 500 | return -EBUSY; |
| 501 | |
| 502 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
| 503 | return -EAGAIN; |
| 504 | } |
| 505 | |
| 506 | /* |
| 507 | * If we may have to abort operations to get out of this |
| 508 | * mount, and they will themselves hold resources we must |
| 509 | * allow the fs to do things. In the Unix tradition of |
| 510 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 511 | * might fail to complete on the first run through as other tasks |
| 512 | * must return, and the like. Thats for the mount program to worry |
| 513 | * about for the moment. |
| 514 | */ |
| 515 | |
| 516 | lock_kernel(); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 517 | if ((flags & MNT_FORCE) && sb->s_op->umount_begin) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 518 | sb->s_op->umount_begin(sb); |
| 519 | unlock_kernel(); |
| 520 | |
| 521 | /* |
| 522 | * No sense to grab the lock for this test, but test itself looks |
| 523 | * somewhat bogus. Suggestions for better replacement? |
| 524 | * Ho-hum... In principle, we might treat that as umount + switch |
| 525 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 526 | * Actually it makes sense, especially if rootfs would contain a |
| 527 | * /reboot - static binary that would close all descriptors and |
| 528 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 529 | */ |
| 530 | if (mnt == current->fs->rootmnt && !(flags & MNT_DETACH)) { |
| 531 | /* |
| 532 | * Special case for "unmounting" root ... |
| 533 | * we just try to remount it readonly. |
| 534 | */ |
| 535 | down_write(&sb->s_umount); |
| 536 | if (!(sb->s_flags & MS_RDONLY)) { |
| 537 | lock_kernel(); |
| 538 | DQUOT_OFF(sb); |
| 539 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
| 540 | unlock_kernel(); |
| 541 | } |
| 542 | up_write(&sb->s_umount); |
| 543 | return retval; |
| 544 | } |
| 545 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 546 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 547 | spin_lock(&vfsmount_lock); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 548 | event++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 550 | retval = -EBUSY; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 551 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 552 | if (!list_empty(&mnt->mnt_list)) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 553 | umount_tree(mnt, 1, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 554 | retval = 0; |
| 555 | } |
| 556 | spin_unlock(&vfsmount_lock); |
| 557 | if (retval) |
| 558 | security_sb_umount_busy(mnt); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 559 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 560 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 561 | return retval; |
| 562 | } |
| 563 | |
| 564 | /* |
| 565 | * Now umount can handle mount points as well as block devices. |
| 566 | * This is important for filesystems which use unnamed block devices. |
| 567 | * |
| 568 | * We now support a flag for forced unmount like the other 'big iron' |
| 569 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 570 | */ |
| 571 | |
| 572 | asmlinkage long sys_umount(char __user * name, int flags) |
| 573 | { |
| 574 | struct nameidata nd; |
| 575 | int retval; |
| 576 | |
| 577 | retval = __user_walk(name, LOOKUP_FOLLOW, &nd); |
| 578 | if (retval) |
| 579 | goto out; |
| 580 | retval = -EINVAL; |
| 581 | if (nd.dentry != nd.mnt->mnt_root) |
| 582 | goto dput_and_out; |
| 583 | if (!check_mnt(nd.mnt)) |
| 584 | goto dput_and_out; |
| 585 | |
| 586 | retval = -EPERM; |
| 587 | if (!capable(CAP_SYS_ADMIN)) |
| 588 | goto dput_and_out; |
| 589 | |
| 590 | retval = do_umount(nd.mnt, flags); |
| 591 | dput_and_out: |
| 592 | path_release_on_umount(&nd); |
| 593 | out: |
| 594 | return retval; |
| 595 | } |
| 596 | |
| 597 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 598 | |
| 599 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 600 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 601 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 602 | asmlinkage long sys_oldumount(char __user * name) |
| 603 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 604 | return sys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 605 | } |
| 606 | |
| 607 | #endif |
| 608 | |
| 609 | static int mount_is_safe(struct nameidata *nd) |
| 610 | { |
| 611 | if (capable(CAP_SYS_ADMIN)) |
| 612 | return 0; |
| 613 | return -EPERM; |
| 614 | #ifdef notyet |
| 615 | if (S_ISLNK(nd->dentry->d_inode->i_mode)) |
| 616 | return -EPERM; |
| 617 | if (nd->dentry->d_inode->i_mode & S_ISVTX) { |
| 618 | if (current->uid != nd->dentry->d_inode->i_uid) |
| 619 | return -EPERM; |
| 620 | } |
| 621 | if (permission(nd->dentry->d_inode, MAY_WRITE, nd)) |
| 622 | return -EPERM; |
| 623 | return 0; |
| 624 | #endif |
| 625 | } |
| 626 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 627 | 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] | 628 | { |
| 629 | while (1) { |
| 630 | if (d == dentry) |
| 631 | return 1; |
| 632 | if (d == NULL || d == d->d_parent) |
| 633 | return 0; |
| 634 | d = d->d_parent; |
| 635 | } |
| 636 | } |
| 637 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 638 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 639 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 640 | { |
| 641 | struct vfsmount *res, *p, *q, *r, *s; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 642 | struct nameidata nd; |
| 643 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 644 | res = q = clone_mnt(mnt, dentry, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 645 | if (!q) |
| 646 | goto Enomem; |
| 647 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
| 648 | |
| 649 | p = mnt; |
Domen Puncer | fdadd65 | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 650 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 651 | if (!lives_below_in_same_fs(r->mnt_mountpoint, dentry)) |
| 652 | continue; |
| 653 | |
| 654 | for (s = r; s; s = next_mnt(s, r)) { |
| 655 | while (p != s->mnt_parent) { |
| 656 | p = p->mnt_parent; |
| 657 | q = q->mnt_parent; |
| 658 | } |
| 659 | p = s; |
| 660 | nd.mnt = q; |
| 661 | nd.dentry = p->mnt_mountpoint; |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 662 | q = clone_mnt(p, p->mnt_root, flag); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 663 | if (!q) |
| 664 | goto Enomem; |
| 665 | spin_lock(&vfsmount_lock); |
| 666 | list_add_tail(&q->mnt_list, &res->mnt_list); |
| 667 | attach_mnt(q, &nd); |
| 668 | spin_unlock(&vfsmount_lock); |
| 669 | } |
| 670 | } |
| 671 | return res; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 672 | Enomem: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 673 | if (res) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 674 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 675 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 676 | umount_tree(res, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 677 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 678 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 679 | } |
| 680 | return NULL; |
| 681 | } |
| 682 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 683 | /* |
| 684 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 685 | * @nd : place the mount tree @source_mnt is attached |
| 686 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 687 | * store the parent mount and mountpoint dentry. |
| 688 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 689 | * |
| 690 | * NOTE: in the table below explains the semantics when a source mount |
| 691 | * of a given type is attached to a destination mount of a given type. |
| 692 | * --------------------------------------------- |
| 693 | * | BIND MOUNT OPERATION | |
| 694 | * |******************************************** |
| 695 | * | source-->| shared | private | |
| 696 | * | dest | | | |
| 697 | * | | | | | |
| 698 | * | v | | | |
| 699 | * |******************************************** |
| 700 | * | shared | shared (++) | shared (+) | |
| 701 | * | | | | |
| 702 | * |non-shared| shared (+) | private | |
| 703 | * ********************************************* |
| 704 | * A bind operation clones the source mount and mounts the clone on the |
| 705 | * destination mount. |
| 706 | * |
| 707 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 708 | * tree of the destination mount and the cloned mount is added to |
| 709 | * the peer group of the source mount. |
| 710 | * (+) the cloned mount is created under the destination mount and is marked |
| 711 | * as shared. The cloned mount is added to the peer group of the source |
| 712 | * mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 713 | * --------------------------------------------- |
| 714 | * | MOVE MOUNT OPERATION | |
| 715 | * |******************************************** |
| 716 | * | source-->| shared | private | |
| 717 | * | dest | | | |
| 718 | * | | | | | |
| 719 | * | v | | | |
| 720 | * |******************************************** |
| 721 | * | shared | shared (+) | shared (+) | |
| 722 | * | | | | |
| 723 | * |non-shared| shared (+*) | private | |
| 724 | * ********************************************* |
| 725 | * (+) the mount is moved to the destination. And is then propagated to all |
| 726 | * the mounts in the propagation tree of the destination mount. |
| 727 | * (+*) the mount is moved to the destination. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 728 | * |
| 729 | * if the source mount is a tree, the operations explained above is |
| 730 | * applied to each mount in the tree. |
| 731 | * Must be called without spinlocks held, since this function can sleep |
| 732 | * in allocations. |
| 733 | */ |
| 734 | static int attach_recursive_mnt(struct vfsmount *source_mnt, |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 735 | struct nameidata *nd, struct nameidata *parent_nd) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 736 | { |
| 737 | LIST_HEAD(tree_list); |
| 738 | struct vfsmount *dest_mnt = nd->mnt; |
| 739 | struct dentry *dest_dentry = nd->dentry; |
| 740 | struct vfsmount *child, *p; |
| 741 | |
| 742 | if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) |
| 743 | return -EINVAL; |
| 744 | |
| 745 | if (IS_MNT_SHARED(dest_mnt)) { |
| 746 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
| 747 | set_mnt_shared(p); |
| 748 | } |
| 749 | |
| 750 | spin_lock(&vfsmount_lock); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 751 | if (parent_nd) { |
| 752 | detach_mnt(source_mnt, parent_nd); |
| 753 | attach_mnt(source_mnt, nd); |
| 754 | touch_namespace(current->namespace); |
| 755 | } else { |
| 756 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
| 757 | commit_tree(source_mnt); |
| 758 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 759 | |
| 760 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
| 761 | list_del_init(&child->mnt_hash); |
| 762 | commit_tree(child); |
| 763 | } |
| 764 | spin_unlock(&vfsmount_lock); |
| 765 | return 0; |
| 766 | } |
| 767 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 768 | static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) |
| 769 | { |
| 770 | int err; |
| 771 | if (mnt->mnt_sb->s_flags & MS_NOUSER) |
| 772 | return -EINVAL; |
| 773 | |
| 774 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != |
| 775 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
| 776 | return -ENOTDIR; |
| 777 | |
| 778 | err = -ENOENT; |
| 779 | down(&nd->dentry->d_inode->i_sem); |
| 780 | if (IS_DEADDIR(nd->dentry->d_inode)) |
| 781 | goto out_unlock; |
| 782 | |
| 783 | err = security_sb_check_sb(mnt, nd); |
| 784 | if (err) |
| 785 | goto out_unlock; |
| 786 | |
| 787 | err = -ENOENT; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 788 | if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 789 | err = attach_recursive_mnt(mnt, nd, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 790 | out_unlock: |
| 791 | up(&nd->dentry->d_inode->i_sem); |
| 792 | if (!err) |
| 793 | security_sb_post_addmount(mnt, nd); |
| 794 | return err; |
| 795 | } |
| 796 | |
| 797 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 798 | * recursively change the type of the mountpoint. |
| 799 | */ |
| 800 | static int do_change_type(struct nameidata *nd, int flag) |
| 801 | { |
| 802 | struct vfsmount *m, *mnt = nd->mnt; |
| 803 | int recurse = flag & MS_REC; |
| 804 | int type = flag & ~MS_REC; |
| 805 | |
| 806 | if (nd->dentry != nd->mnt->mnt_root) |
| 807 | return -EINVAL; |
| 808 | |
| 809 | down_write(&namespace_sem); |
| 810 | spin_lock(&vfsmount_lock); |
| 811 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
| 812 | change_mnt_propagation(m, type); |
| 813 | spin_unlock(&vfsmount_lock); |
| 814 | up_write(&namespace_sem); |
| 815 | return 0; |
| 816 | } |
| 817 | |
| 818 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 819 | * do loopback mount. |
| 820 | */ |
| 821 | static int do_loopback(struct nameidata *nd, char *old_name, int recurse) |
| 822 | { |
| 823 | struct nameidata old_nd; |
| 824 | struct vfsmount *mnt = NULL; |
| 825 | int err = mount_is_safe(nd); |
| 826 | if (err) |
| 827 | return err; |
| 828 | if (!old_name || !*old_name) |
| 829 | return -EINVAL; |
| 830 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); |
| 831 | if (err) |
| 832 | return err; |
| 833 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 834 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 835 | err = -EINVAL; |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 836 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
| 837 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 838 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 839 | err = -ENOMEM; |
| 840 | if (recurse) |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 841 | mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 842 | else |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 843 | mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 844 | |
| 845 | if (!mnt) |
| 846 | goto out; |
| 847 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 848 | err = graft_tree(mnt, nd); |
| 849 | if (err) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 850 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 851 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 852 | umount_tree(mnt, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 853 | spin_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 854 | release_mounts(&umount_list); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 855 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 856 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 857 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 858 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 859 | path_release(&old_nd); |
| 860 | return err; |
| 861 | } |
| 862 | |
| 863 | /* |
| 864 | * change filesystem flags. dir should be a physical root of filesystem. |
| 865 | * If you've mounted a non-root directory somewhere and want to do remount |
| 866 | * on it - tough luck. |
| 867 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 868 | static int do_remount(struct nameidata *nd, int flags, int mnt_flags, |
| 869 | void *data) |
| 870 | { |
| 871 | int err; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 872 | struct super_block *sb = nd->mnt->mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 873 | |
| 874 | if (!capable(CAP_SYS_ADMIN)) |
| 875 | return -EPERM; |
| 876 | |
| 877 | if (!check_mnt(nd->mnt)) |
| 878 | return -EINVAL; |
| 879 | |
| 880 | if (nd->dentry != nd->mnt->mnt_root) |
| 881 | return -EINVAL; |
| 882 | |
| 883 | down_write(&sb->s_umount); |
| 884 | err = do_remount_sb(sb, flags, data, 0); |
| 885 | if (!err) |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 886 | nd->mnt->mnt_flags = mnt_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 887 | up_write(&sb->s_umount); |
| 888 | if (!err) |
| 889 | security_sb_post_remount(nd->mnt, flags, data); |
| 890 | return err; |
| 891 | } |
| 892 | |
| 893 | static int do_move_mount(struct nameidata *nd, char *old_name) |
| 894 | { |
| 895 | struct nameidata old_nd, parent_nd; |
| 896 | struct vfsmount *p; |
| 897 | int err = 0; |
| 898 | if (!capable(CAP_SYS_ADMIN)) |
| 899 | return -EPERM; |
| 900 | if (!old_name || !*old_name) |
| 901 | return -EINVAL; |
| 902 | err = path_lookup(old_name, LOOKUP_FOLLOW, &old_nd); |
| 903 | if (err) |
| 904 | return err; |
| 905 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 906 | down_write(&namespace_sem); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 907 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 908 | ; |
| 909 | err = -EINVAL; |
| 910 | if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt)) |
| 911 | goto out; |
| 912 | |
| 913 | err = -ENOENT; |
| 914 | down(&nd->dentry->d_inode->i_sem); |
| 915 | if (IS_DEADDIR(nd->dentry->d_inode)) |
| 916 | goto out1; |
| 917 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 918 | if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 919 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 920 | |
| 921 | err = -EINVAL; |
| 922 | if (old_nd.dentry != old_nd.mnt->mnt_root) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 923 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 924 | |
| 925 | if (old_nd.mnt == old_nd.mnt->mnt_parent) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 926 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 927 | |
| 928 | if (S_ISDIR(nd->dentry->d_inode->i_mode) != |
| 929 | S_ISDIR(old_nd.dentry->d_inode->i_mode)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 930 | goto out1; |
| 931 | /* |
| 932 | * Don't move a mount residing in a shared parent. |
| 933 | */ |
| 934 | if (old_nd.mnt->mnt_parent && IS_MNT_SHARED(old_nd.mnt->mnt_parent)) |
| 935 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 936 | err = -ELOOP; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 937 | for (p = nd->mnt; p->mnt_parent != p; p = p->mnt_parent) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 938 | if (p == old_nd.mnt) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 939 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 940 | |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 941 | if ((err = attach_recursive_mnt(old_nd.mnt, nd, &parent_nd))) |
| 942 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 943 | |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 944 | spin_lock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 945 | /* if the mount is moved, it should no longer be expire |
| 946 | * automatically */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 947 | list_del_init(&old_nd.mnt->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | spin_unlock(&vfsmount_lock); |
| 949 | out1: |
| 950 | up(&nd->dentry->d_inode->i_sem); |
| 951 | out: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 952 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 953 | if (!err) |
| 954 | path_release(&parent_nd); |
| 955 | path_release(&old_nd); |
| 956 | return err; |
| 957 | } |
| 958 | |
| 959 | /* |
| 960 | * create a new mount for userspace and request it to be added into the |
| 961 | * namespace's tree |
| 962 | */ |
| 963 | static int do_new_mount(struct nameidata *nd, char *type, int flags, |
| 964 | int mnt_flags, char *name, void *data) |
| 965 | { |
| 966 | struct vfsmount *mnt; |
| 967 | |
| 968 | if (!type || !memchr(type, 0, PAGE_SIZE)) |
| 969 | return -EINVAL; |
| 970 | |
| 971 | /* we need capabilities... */ |
| 972 | if (!capable(CAP_SYS_ADMIN)) |
| 973 | return -EPERM; |
| 974 | |
| 975 | mnt = do_kern_mount(type, flags, name, data); |
| 976 | if (IS_ERR(mnt)) |
| 977 | return PTR_ERR(mnt); |
| 978 | |
| 979 | return do_add_mount(mnt, nd, mnt_flags, NULL); |
| 980 | } |
| 981 | |
| 982 | /* |
| 983 | * add a mount into a namespace's mount tree |
| 984 | * - provide the option of adding the new mount to an expiration list |
| 985 | */ |
| 986 | int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, |
| 987 | int mnt_flags, struct list_head *fslist) |
| 988 | { |
| 989 | int err; |
| 990 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 991 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 992 | /* Something was mounted here while we slept */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 993 | while (d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 994 | ; |
| 995 | err = -EINVAL; |
| 996 | if (!check_mnt(nd->mnt)) |
| 997 | goto unlock; |
| 998 | |
| 999 | /* Refuse the same filesystem on the same mount point */ |
| 1000 | err = -EBUSY; |
| 1001 | if (nd->mnt->mnt_sb == newmnt->mnt_sb && |
| 1002 | nd->mnt->mnt_root == nd->dentry) |
| 1003 | goto unlock; |
| 1004 | |
| 1005 | err = -EINVAL; |
| 1006 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) |
| 1007 | goto unlock; |
| 1008 | |
| 1009 | newmnt->mnt_flags = mnt_flags; |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1010 | if ((err = graft_tree(newmnt, nd))) |
| 1011 | goto unlock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1012 | |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1013 | if (fslist) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1014 | /* add to the specified expiration list */ |
| 1015 | spin_lock(&vfsmount_lock); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1016 | list_add_tail(&newmnt->mnt_expire, fslist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1017 | spin_unlock(&vfsmount_lock); |
| 1018 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1019 | up_write(&namespace_sem); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1020 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1021 | |
| 1022 | unlock: |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1023 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1024 | mntput(newmnt); |
| 1025 | return err; |
| 1026 | } |
| 1027 | |
| 1028 | EXPORT_SYMBOL_GPL(do_add_mount); |
| 1029 | |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1030 | static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, |
| 1031 | struct list_head *umounts) |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1032 | { |
| 1033 | spin_lock(&vfsmount_lock); |
| 1034 | |
| 1035 | /* |
Miklos Szeredi | ed42c87 | 2005-07-07 17:57:26 -0700 | [diff] [blame] | 1036 | * Check if mount is still attached, if not, let whoever holds it deal |
| 1037 | * with the sucker |
| 1038 | */ |
| 1039 | if (mnt->mnt_parent == mnt) { |
| 1040 | spin_unlock(&vfsmount_lock); |
| 1041 | return; |
| 1042 | } |
| 1043 | |
| 1044 | /* |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1045 | * Check that it is still dead: the count should now be 2 - as |
| 1046 | * contributed by the vfsmount parent and the mntget above |
| 1047 | */ |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1048 | if (!propagate_mount_busy(mnt, 2)) { |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1049 | /* delete from the namespace */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1050 | touch_namespace(mnt->mnt_namespace); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1051 | list_del_init(&mnt->mnt_list); |
Miklos Szeredi | ac08115 | 2005-07-07 17:57:27 -0700 | [diff] [blame] | 1052 | mnt->mnt_namespace = NULL; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1053 | umount_tree(mnt, 1, umounts); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1054 | spin_unlock(&vfsmount_lock); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1055 | } else { |
| 1056 | /* |
| 1057 | * Someone brought it back to life whilst we didn't have any |
| 1058 | * locks held so return it to the expiration list |
| 1059 | */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1060 | list_add_tail(&mnt->mnt_expire, mounts); |
Miklos Szeredi | 24ca2af | 2005-07-07 17:57:25 -0700 | [diff] [blame] | 1061 | spin_unlock(&vfsmount_lock); |
| 1062 | } |
| 1063 | } |
| 1064 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1065 | /* |
| 1066 | * process a list of expirable mountpoints with the intent of discarding any |
| 1067 | * mountpoints that aren't in use and haven't been touched since last we came |
| 1068 | * here |
| 1069 | */ |
| 1070 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 1071 | { |
| 1072 | struct namespace *namespace; |
| 1073 | struct vfsmount *mnt, *next; |
| 1074 | LIST_HEAD(graveyard); |
| 1075 | |
| 1076 | if (list_empty(mounts)) |
| 1077 | return; |
| 1078 | |
| 1079 | spin_lock(&vfsmount_lock); |
| 1080 | |
| 1081 | /* extract from the expiration list every vfsmount that matches the |
| 1082 | * following criteria: |
| 1083 | * - only referenced by its parent vfsmount |
| 1084 | * - still marked for expiry (marked on the last call here; marks are |
| 1085 | * cleared by mntput()) |
| 1086 | */ |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1087 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1088 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
| 1089 | atomic_read(&mnt->mnt_count) != 1) |
| 1090 | continue; |
| 1091 | |
| 1092 | mntget(mnt); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1093 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1094 | } |
| 1095 | |
| 1096 | /* |
| 1097 | * go through the vfsmounts we've just consigned to the graveyard to |
| 1098 | * - check that they're still dead |
| 1099 | * - delete the vfsmount from the appropriate namespace under lock |
| 1100 | * - dispose of the corpse |
| 1101 | */ |
| 1102 | while (!list_empty(&graveyard)) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1103 | LIST_HEAD(umounts); |
Miklos Szeredi | 55e700b | 2005-07-07 17:57:30 -0700 | [diff] [blame] | 1104 | mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire); |
| 1105 | list_del_init(&mnt->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1106 | |
| 1107 | /* don't do anything if the namespace is dead - all the |
| 1108 | * vfsmounts from it are going away anyway */ |
| 1109 | namespace = mnt->mnt_namespace; |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1110 | if (!namespace || !namespace->root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1111 | continue; |
| 1112 | get_namespace(namespace); |
| 1113 | |
| 1114 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1115 | down_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1116 | expire_mount(mnt, mounts, &umounts); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1117 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1118 | release_mounts(&umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1119 | mntput(mnt); |
| 1120 | put_namespace(namespace); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1121 | spin_lock(&vfsmount_lock); |
| 1122 | } |
| 1123 | |
| 1124 | spin_unlock(&vfsmount_lock); |
| 1125 | } |
| 1126 | |
| 1127 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 1128 | |
| 1129 | /* |
| 1130 | * Some copy_from_user() implementations do not return the exact number of |
| 1131 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 1132 | * Note that this function differs from copy_from_user() in that it will oops |
| 1133 | * on bad values of `to', rather than returning a short copy. |
| 1134 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1135 | static long exact_copy_from_user(void *to, const void __user * from, |
| 1136 | unsigned long n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1137 | { |
| 1138 | char *t = to; |
| 1139 | const char __user *f = from; |
| 1140 | char c; |
| 1141 | |
| 1142 | if (!access_ok(VERIFY_READ, from, n)) |
| 1143 | return n; |
| 1144 | |
| 1145 | while (n) { |
| 1146 | if (__get_user(c, f)) { |
| 1147 | memset(t, 0, n); |
| 1148 | break; |
| 1149 | } |
| 1150 | *t++ = c; |
| 1151 | f++; |
| 1152 | n--; |
| 1153 | } |
| 1154 | return n; |
| 1155 | } |
| 1156 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1157 | int copy_mount_options(const void __user * data, unsigned long *where) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1158 | { |
| 1159 | int i; |
| 1160 | unsigned long page; |
| 1161 | unsigned long size; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1162 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1163 | *where = 0; |
| 1164 | if (!data) |
| 1165 | return 0; |
| 1166 | |
| 1167 | if (!(page = __get_free_page(GFP_KERNEL))) |
| 1168 | return -ENOMEM; |
| 1169 | |
| 1170 | /* We only care that *some* data at the address the user |
| 1171 | * gave us is valid. Just in case, we'll zero |
| 1172 | * the remainder of the page. |
| 1173 | */ |
| 1174 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 1175 | size = TASK_SIZE - (unsigned long)data; |
| 1176 | if (size > PAGE_SIZE) |
| 1177 | size = PAGE_SIZE; |
| 1178 | |
| 1179 | i = size - exact_copy_from_user((void *)page, data, size); |
| 1180 | if (!i) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1181 | free_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1182 | return -EFAULT; |
| 1183 | } |
| 1184 | if (i != PAGE_SIZE) |
| 1185 | memset((char *)page + i, 0, PAGE_SIZE - i); |
| 1186 | *where = page; |
| 1187 | return 0; |
| 1188 | } |
| 1189 | |
| 1190 | /* |
| 1191 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 1192 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 1193 | * |
| 1194 | * data is a (void *) that can point to any structure up to |
| 1195 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 1196 | * information (or be NULL). |
| 1197 | * |
| 1198 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 1199 | * When the flags word was introduced its top half was required |
| 1200 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 1201 | * Therefore, if this magic number is present, it carries no information |
| 1202 | * and must be discarded. |
| 1203 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1204 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1205 | unsigned long flags, void *data_page) |
| 1206 | { |
| 1207 | struct nameidata nd; |
| 1208 | int retval = 0; |
| 1209 | int mnt_flags = 0; |
| 1210 | |
| 1211 | /* Discard magic */ |
| 1212 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 1213 | flags &= ~MS_MGC_MSK; |
| 1214 | |
| 1215 | /* Basic sanity checks */ |
| 1216 | |
| 1217 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) |
| 1218 | return -EINVAL; |
| 1219 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) |
| 1220 | return -EINVAL; |
| 1221 | |
| 1222 | if (data_page) |
| 1223 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 1224 | |
| 1225 | /* Separate the per-mountpoint flags */ |
| 1226 | if (flags & MS_NOSUID) |
| 1227 | mnt_flags |= MNT_NOSUID; |
| 1228 | if (flags & MS_NODEV) |
| 1229 | mnt_flags |= MNT_NODEV; |
| 1230 | if (flags & MS_NOEXEC) |
| 1231 | mnt_flags |= MNT_NOEXEC; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1232 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1233 | |
| 1234 | /* ... and get the mountpoint */ |
| 1235 | retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd); |
| 1236 | if (retval) |
| 1237 | return retval; |
| 1238 | |
| 1239 | retval = security_sb_mount(dev_name, &nd, type_page, flags, data_page); |
| 1240 | if (retval) |
| 1241 | goto dput_out; |
| 1242 | |
| 1243 | if (flags & MS_REMOUNT) |
| 1244 | retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, |
| 1245 | data_page); |
| 1246 | else if (flags & MS_BIND) |
| 1247 | retval = do_loopback(&nd, dev_name, flags & MS_REC); |
Ram Pai | a58b0eb | 2005-11-07 17:20:48 -0500 | [diff] [blame^] | 1248 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE)) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1249 | retval = do_change_type(&nd, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1250 | else if (flags & MS_MOVE) |
| 1251 | retval = do_move_mount(&nd, dev_name); |
| 1252 | else |
| 1253 | retval = do_new_mount(&nd, type_page, flags, mnt_flags, |
| 1254 | dev_name, data_page); |
| 1255 | dput_out: |
| 1256 | path_release(&nd); |
| 1257 | return retval; |
| 1258 | } |
| 1259 | |
| 1260 | int copy_namespace(int flags, struct task_struct *tsk) |
| 1261 | { |
| 1262 | struct namespace *namespace = tsk->namespace; |
| 1263 | struct namespace *new_ns; |
| 1264 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL; |
| 1265 | struct fs_struct *fs = tsk->fs; |
| 1266 | struct vfsmount *p, *q; |
| 1267 | |
| 1268 | if (!namespace) |
| 1269 | return 0; |
| 1270 | |
| 1271 | get_namespace(namespace); |
| 1272 | |
| 1273 | if (!(flags & CLONE_NEWNS)) |
| 1274 | return 0; |
| 1275 | |
| 1276 | if (!capable(CAP_SYS_ADMIN)) { |
| 1277 | put_namespace(namespace); |
| 1278 | return -EPERM; |
| 1279 | } |
| 1280 | |
| 1281 | new_ns = kmalloc(sizeof(struct namespace), GFP_KERNEL); |
| 1282 | if (!new_ns) |
| 1283 | goto out; |
| 1284 | |
| 1285 | atomic_set(&new_ns->count, 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1286 | INIT_LIST_HEAD(&new_ns->list); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1287 | init_waitqueue_head(&new_ns->poll); |
| 1288 | new_ns->event = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1289 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1290 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1291 | /* First pass: copy the tree topology */ |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1292 | new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root, |
| 1293 | CL_EXPIRE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1294 | if (!new_ns->root) { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1295 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1296 | kfree(new_ns); |
| 1297 | goto out; |
| 1298 | } |
| 1299 | spin_lock(&vfsmount_lock); |
| 1300 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
| 1301 | spin_unlock(&vfsmount_lock); |
| 1302 | |
| 1303 | /* |
| 1304 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 1305 | * as belonging to new namespace. We have already acquired a private |
| 1306 | * fs_struct, so tsk->fs->lock is not needed. |
| 1307 | */ |
| 1308 | p = namespace->root; |
| 1309 | q = new_ns->root; |
| 1310 | while (p) { |
| 1311 | q->mnt_namespace = new_ns; |
| 1312 | if (fs) { |
| 1313 | if (p == fs->rootmnt) { |
| 1314 | rootmnt = p; |
| 1315 | fs->rootmnt = mntget(q); |
| 1316 | } |
| 1317 | if (p == fs->pwdmnt) { |
| 1318 | pwdmnt = p; |
| 1319 | fs->pwdmnt = mntget(q); |
| 1320 | } |
| 1321 | if (p == fs->altrootmnt) { |
| 1322 | altrootmnt = p; |
| 1323 | fs->altrootmnt = mntget(q); |
| 1324 | } |
| 1325 | } |
| 1326 | p = next_mnt(p, namespace->root); |
| 1327 | q = next_mnt(q, new_ns->root); |
| 1328 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1329 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1330 | |
| 1331 | tsk->namespace = new_ns; |
| 1332 | |
| 1333 | if (rootmnt) |
| 1334 | mntput(rootmnt); |
| 1335 | if (pwdmnt) |
| 1336 | mntput(pwdmnt); |
| 1337 | if (altrootmnt) |
| 1338 | mntput(altrootmnt); |
| 1339 | |
| 1340 | put_namespace(namespace); |
| 1341 | return 0; |
| 1342 | |
| 1343 | out: |
| 1344 | put_namespace(namespace); |
| 1345 | return -ENOMEM; |
| 1346 | } |
| 1347 | |
| 1348 | asmlinkage long sys_mount(char __user * dev_name, char __user * dir_name, |
| 1349 | char __user * type, unsigned long flags, |
| 1350 | void __user * data) |
| 1351 | { |
| 1352 | int retval; |
| 1353 | unsigned long data_page; |
| 1354 | unsigned long type_page; |
| 1355 | unsigned long dev_page; |
| 1356 | char *dir_page; |
| 1357 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1358 | retval = copy_mount_options(type, &type_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1359 | if (retval < 0) |
| 1360 | return retval; |
| 1361 | |
| 1362 | dir_page = getname(dir_name); |
| 1363 | retval = PTR_ERR(dir_page); |
| 1364 | if (IS_ERR(dir_page)) |
| 1365 | goto out1; |
| 1366 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1367 | retval = copy_mount_options(dev_name, &dev_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1368 | if (retval < 0) |
| 1369 | goto out2; |
| 1370 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1371 | retval = copy_mount_options(data, &data_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1372 | if (retval < 0) |
| 1373 | goto out3; |
| 1374 | |
| 1375 | lock_kernel(); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1376 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
| 1377 | flags, (void *)data_page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1378 | unlock_kernel(); |
| 1379 | free_page(data_page); |
| 1380 | |
| 1381 | out3: |
| 1382 | free_page(dev_page); |
| 1383 | out2: |
| 1384 | putname(dir_page); |
| 1385 | out1: |
| 1386 | free_page(type_page); |
| 1387 | return retval; |
| 1388 | } |
| 1389 | |
| 1390 | /* |
| 1391 | * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. |
| 1392 | * It can block. Requires the big lock held. |
| 1393 | */ |
| 1394 | void set_fs_root(struct fs_struct *fs, struct vfsmount *mnt, |
| 1395 | struct dentry *dentry) |
| 1396 | { |
| 1397 | struct dentry *old_root; |
| 1398 | struct vfsmount *old_rootmnt; |
| 1399 | write_lock(&fs->lock); |
| 1400 | old_root = fs->root; |
| 1401 | old_rootmnt = fs->rootmnt; |
| 1402 | fs->rootmnt = mntget(mnt); |
| 1403 | fs->root = dget(dentry); |
| 1404 | write_unlock(&fs->lock); |
| 1405 | if (old_root) { |
| 1406 | dput(old_root); |
| 1407 | mntput(old_rootmnt); |
| 1408 | } |
| 1409 | } |
| 1410 | |
| 1411 | /* |
| 1412 | * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. |
| 1413 | * It can block. Requires the big lock held. |
| 1414 | */ |
| 1415 | void set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt, |
| 1416 | struct dentry *dentry) |
| 1417 | { |
| 1418 | struct dentry *old_pwd; |
| 1419 | struct vfsmount *old_pwdmnt; |
| 1420 | |
| 1421 | write_lock(&fs->lock); |
| 1422 | old_pwd = fs->pwd; |
| 1423 | old_pwdmnt = fs->pwdmnt; |
| 1424 | fs->pwdmnt = mntget(mnt); |
| 1425 | fs->pwd = dget(dentry); |
| 1426 | write_unlock(&fs->lock); |
| 1427 | |
| 1428 | if (old_pwd) { |
| 1429 | dput(old_pwd); |
| 1430 | mntput(old_pwdmnt); |
| 1431 | } |
| 1432 | } |
| 1433 | |
| 1434 | static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) |
| 1435 | { |
| 1436 | struct task_struct *g, *p; |
| 1437 | struct fs_struct *fs; |
| 1438 | |
| 1439 | read_lock(&tasklist_lock); |
| 1440 | do_each_thread(g, p) { |
| 1441 | task_lock(p); |
| 1442 | fs = p->fs; |
| 1443 | if (fs) { |
| 1444 | atomic_inc(&fs->count); |
| 1445 | task_unlock(p); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1446 | if (fs->root == old_nd->dentry |
| 1447 | && fs->rootmnt == old_nd->mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1448 | set_fs_root(fs, new_nd->mnt, new_nd->dentry); |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1449 | if (fs->pwd == old_nd->dentry |
| 1450 | && fs->pwdmnt == old_nd->mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1451 | set_fs_pwd(fs, new_nd->mnt, new_nd->dentry); |
| 1452 | put_fs_struct(fs); |
| 1453 | } else |
| 1454 | task_unlock(p); |
| 1455 | } while_each_thread(g, p); |
| 1456 | read_unlock(&tasklist_lock); |
| 1457 | } |
| 1458 | |
| 1459 | /* |
| 1460 | * pivot_root Semantics: |
| 1461 | * Moves the root file system of the current process to the directory put_old, |
| 1462 | * makes new_root as the new root file system of the current process, and sets |
| 1463 | * root/cwd of all processes which had them on the current root to new_root. |
| 1464 | * |
| 1465 | * Restrictions: |
| 1466 | * The new_root and put_old must be directories, and must not be on the |
| 1467 | * same file system as the current process root. The put_old must be |
| 1468 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 1469 | * pointed to by put_old must yield the same directory as new_root. No other |
| 1470 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 1471 | * |
| 1472 | * Notes: |
| 1473 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 1474 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 1475 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 1476 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 1477 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 1478 | * first. |
| 1479 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1480 | asmlinkage long sys_pivot_root(const char __user * new_root, |
| 1481 | const char __user * put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1482 | { |
| 1483 | struct vfsmount *tmp; |
| 1484 | struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; |
| 1485 | int error; |
| 1486 | |
| 1487 | if (!capable(CAP_SYS_ADMIN)) |
| 1488 | return -EPERM; |
| 1489 | |
| 1490 | lock_kernel(); |
| 1491 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1492 | error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, |
| 1493 | &new_nd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1494 | if (error) |
| 1495 | goto out0; |
| 1496 | error = -EINVAL; |
| 1497 | if (!check_mnt(new_nd.mnt)) |
| 1498 | goto out1; |
| 1499 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1500 | error = __user_walk(put_old, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old_nd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1501 | if (error) |
| 1502 | goto out1; |
| 1503 | |
| 1504 | error = security_sb_pivotroot(&old_nd, &new_nd); |
| 1505 | if (error) { |
| 1506 | path_release(&old_nd); |
| 1507 | goto out1; |
| 1508 | } |
| 1509 | |
| 1510 | read_lock(¤t->fs->lock); |
| 1511 | user_nd.mnt = mntget(current->fs->rootmnt); |
| 1512 | user_nd.dentry = dget(current->fs->root); |
| 1513 | read_unlock(¤t->fs->lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1514 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1515 | down(&old_nd.dentry->d_inode->i_sem); |
| 1516 | error = -EINVAL; |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1517 | if (IS_MNT_SHARED(old_nd.mnt) || |
| 1518 | IS_MNT_SHARED(new_nd.mnt->mnt_parent) || |
| 1519 | IS_MNT_SHARED(user_nd.mnt->mnt_parent)) |
| 1520 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1521 | if (!check_mnt(user_nd.mnt)) |
| 1522 | goto out2; |
| 1523 | error = -ENOENT; |
| 1524 | if (IS_DEADDIR(new_nd.dentry->d_inode)) |
| 1525 | goto out2; |
| 1526 | if (d_unhashed(new_nd.dentry) && !IS_ROOT(new_nd.dentry)) |
| 1527 | goto out2; |
| 1528 | if (d_unhashed(old_nd.dentry) && !IS_ROOT(old_nd.dentry)) |
| 1529 | goto out2; |
| 1530 | error = -EBUSY; |
| 1531 | if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt) |
| 1532 | goto out2; /* loop, on the same file system */ |
| 1533 | error = -EINVAL; |
| 1534 | if (user_nd.mnt->mnt_root != user_nd.dentry) |
| 1535 | goto out2; /* not a mountpoint */ |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 1536 | if (user_nd.mnt->mnt_parent == user_nd.mnt) |
| 1537 | goto out2; /* not attached */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1538 | if (new_nd.mnt->mnt_root != new_nd.dentry) |
| 1539 | goto out2; /* not a mountpoint */ |
Miklos Szeredi | 0bb6fcc | 2005-09-06 15:19:36 -0700 | [diff] [blame] | 1540 | if (new_nd.mnt->mnt_parent == new_nd.mnt) |
| 1541 | goto out2; /* not attached */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1542 | tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */ |
| 1543 | spin_lock(&vfsmount_lock); |
| 1544 | if (tmp != new_nd.mnt) { |
| 1545 | for (;;) { |
| 1546 | if (tmp->mnt_parent == tmp) |
| 1547 | goto out3; /* already mounted on put_old */ |
| 1548 | if (tmp->mnt_parent == new_nd.mnt) |
| 1549 | break; |
| 1550 | tmp = tmp->mnt_parent; |
| 1551 | } |
| 1552 | if (!is_subdir(tmp->mnt_mountpoint, new_nd.dentry)) |
| 1553 | goto out3; |
| 1554 | } else if (!is_subdir(old_nd.dentry, new_nd.dentry)) |
| 1555 | goto out3; |
| 1556 | detach_mnt(new_nd.mnt, &parent_nd); |
| 1557 | detach_mnt(user_nd.mnt, &root_parent); |
| 1558 | attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ |
| 1559 | attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1560 | touch_namespace(current->namespace); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1561 | spin_unlock(&vfsmount_lock); |
| 1562 | chroot_fs_refs(&user_nd, &new_nd); |
| 1563 | security_sb_post_pivotroot(&user_nd, &new_nd); |
| 1564 | error = 0; |
| 1565 | path_release(&root_parent); |
| 1566 | path_release(&parent_nd); |
| 1567 | out2: |
| 1568 | up(&old_nd.dentry->d_inode->i_sem); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1569 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1570 | path_release(&user_nd); |
| 1571 | path_release(&old_nd); |
| 1572 | out1: |
| 1573 | path_release(&new_nd); |
| 1574 | out0: |
| 1575 | unlock_kernel(); |
| 1576 | return error; |
| 1577 | out3: |
| 1578 | spin_unlock(&vfsmount_lock); |
| 1579 | goto out2; |
| 1580 | } |
| 1581 | |
| 1582 | static void __init init_mount_tree(void) |
| 1583 | { |
| 1584 | struct vfsmount *mnt; |
| 1585 | struct namespace *namespace; |
| 1586 | struct task_struct *g, *p; |
| 1587 | |
| 1588 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); |
| 1589 | if (IS_ERR(mnt)) |
| 1590 | panic("Can't create rootfs"); |
| 1591 | namespace = kmalloc(sizeof(*namespace), GFP_KERNEL); |
| 1592 | if (!namespace) |
| 1593 | panic("Can't allocate initial namespace"); |
| 1594 | atomic_set(&namespace->count, 1); |
| 1595 | INIT_LIST_HEAD(&namespace->list); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1596 | init_waitqueue_head(&namespace->poll); |
| 1597 | namespace->event = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1598 | list_add(&mnt->mnt_list, &namespace->list); |
| 1599 | namespace->root = mnt; |
| 1600 | mnt->mnt_namespace = namespace; |
| 1601 | |
| 1602 | init_task.namespace = namespace; |
| 1603 | read_lock(&tasklist_lock); |
| 1604 | do_each_thread(g, p) { |
| 1605 | get_namespace(namespace); |
| 1606 | p->namespace = namespace; |
| 1607 | } while_each_thread(g, p); |
| 1608 | read_unlock(&tasklist_lock); |
| 1609 | |
| 1610 | set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root); |
| 1611 | set_fs_root(current->fs, namespace->root, namespace->root->mnt_root); |
| 1612 | } |
| 1613 | |
| 1614 | void __init mnt_init(unsigned long mempages) |
| 1615 | { |
| 1616 | struct list_head *d; |
| 1617 | unsigned int nr_hash; |
| 1618 | int i; |
| 1619 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1620 | init_rwsem(&namespace_sem); |
| 1621 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1622 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1623 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1624 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1625 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1626 | |
| 1627 | if (!mount_hashtable) |
| 1628 | panic("Failed to allocate mount hash table\n"); |
| 1629 | |
| 1630 | /* |
| 1631 | * Find the power-of-two list-heads that can fit into the allocation.. |
| 1632 | * We don't guarantee that "sizeof(struct list_head)" is necessarily |
| 1633 | * a power-of-two. |
| 1634 | */ |
| 1635 | nr_hash = PAGE_SIZE / sizeof(struct list_head); |
| 1636 | hash_bits = 0; |
| 1637 | do { |
| 1638 | hash_bits++; |
| 1639 | } while ((nr_hash >> hash_bits) != 0); |
| 1640 | hash_bits--; |
| 1641 | |
| 1642 | /* |
| 1643 | * Re-calculate the actual number of entries and the mask |
| 1644 | * from the number of bits we can fit. |
| 1645 | */ |
| 1646 | nr_hash = 1UL << hash_bits; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1647 | hash_mask = nr_hash - 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1648 | |
| 1649 | printk("Mount-cache hash table entries: %d\n", nr_hash); |
| 1650 | |
| 1651 | /* And initialize the newly allocated array */ |
| 1652 | d = mount_hashtable; |
| 1653 | i = nr_hash; |
| 1654 | do { |
| 1655 | INIT_LIST_HEAD(d); |
| 1656 | d++; |
| 1657 | i--; |
| 1658 | } while (i); |
| 1659 | sysfs_init(); |
| 1660 | init_rootfs(); |
| 1661 | init_mount_tree(); |
| 1662 | } |
| 1663 | |
| 1664 | void __put_namespace(struct namespace *namespace) |
| 1665 | { |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1666 | struct vfsmount *root = namespace->root; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1667 | LIST_HEAD(umount_list); |
Miklos Szeredi | 1ce88cf | 2005-07-07 17:57:24 -0700 | [diff] [blame] | 1668 | namespace->root = NULL; |
| 1669 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1670 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1671 | spin_lock(&vfsmount_lock); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1672 | umount_tree(root, 0, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1673 | spin_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1674 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1675 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1676 | kfree(namespace); |
| 1677 | } |