| 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/syscalls.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/sched.h> |
| 14 | #include <linux/smp_lock.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/kernel.h> |
| 17 | #include <linux/acct.h> |
| 18 | #include <linux/capability.h> |
| 19 | #include <linux/cpumask.h> |
| 20 | #include <linux/module.h> |
| 21 | #include <linux/sysfs.h> |
| 22 | #include <linux/seq_file.h> |
| 23 | #include <linux/mnt_namespace.h> |
| 24 | #include <linux/namei.h> |
| 25 | #include <linux/security.h> |
| 26 | #include <linux/mount.h> |
| 27 | #include <linux/ramfs.h> |
| 28 | #include <linux/log2.h> |
| 29 | #include <linux/idr.h> |
| 30 | #include <linux/fs_struct.h> |
| 31 | #include <asm/uaccess.h> |
| 32 | #include <asm/unistd.h> |
| 33 | #include "pnode.h" |
| 34 | #include "internal.h" |
| 35 | |
| 36 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
| 37 | #define HASH_SIZE (1UL << HASH_SHIFT) |
| 38 | |
| 39 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ |
| 40 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
| 41 | |
| 42 | static int event; |
| 43 | static DEFINE_IDA(mnt_id_ida); |
| 44 | static DEFINE_IDA(mnt_group_ida); |
| 45 | |
| 46 | static struct list_head *mount_hashtable __read_mostly; |
| 47 | static struct kmem_cache *mnt_cache __read_mostly; |
| 48 | static struct rw_semaphore namespace_sem; |
| 49 | |
| 50 | /* /sys/fs */ |
| 51 | struct kobject *fs_kobj; |
| 52 | EXPORT_SYMBOL_GPL(fs_kobj); |
| 53 | |
| 54 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
| 55 | { |
| 56 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 57 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
| 58 | tmp = tmp + (tmp >> HASH_SHIFT); |
| 59 | return tmp & (HASH_SIZE - 1); |
| 60 | } |
| 61 | |
| 62 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
| 63 | |
| 64 | /* allocation is serialized by namespace_sem */ |
| 65 | static int mnt_alloc_id(struct vfsmount *mnt) |
| 66 | { |
| 67 | int res; |
| 68 | |
| 69 | retry: |
| 70 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); |
| 71 | spin_lock(&vfsmount_lock); |
| 72 | res = ida_get_new(&mnt_id_ida, &mnt->mnt_id); |
| 73 | spin_unlock(&vfsmount_lock); |
| 74 | if (res == -EAGAIN) |
| 75 | goto retry; |
| 76 | |
| 77 | return res; |
| 78 | } |
| 79 | |
| 80 | static void mnt_free_id(struct vfsmount *mnt) |
| 81 | { |
| 82 | spin_lock(&vfsmount_lock); |
| 83 | ida_remove(&mnt_id_ida, mnt->mnt_id); |
| 84 | spin_unlock(&vfsmount_lock); |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Allocate a new peer group ID |
| 89 | * |
| 90 | * mnt_group_ida is protected by namespace_sem |
| 91 | */ |
| 92 | static int mnt_alloc_group_id(struct vfsmount *mnt) |
| 93 | { |
| 94 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
| 95 | return -ENOMEM; |
| 96 | |
| 97 | return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id); |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | * Release a peer group ID |
| 102 | */ |
| 103 | void mnt_release_group_id(struct vfsmount *mnt) |
| 104 | { |
| 105 | ida_remove(&mnt_group_ida, mnt->mnt_group_id); |
| 106 | mnt->mnt_group_id = 0; |
| 107 | } |
| 108 | |
| 109 | struct vfsmount *alloc_vfsmnt(const char *name) |
| 110 | { |
| 111 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
| 112 | if (mnt) { |
| 113 | int err; |
| 114 | |
| 115 | err = mnt_alloc_id(mnt); |
| 116 | if (err) |
| 117 | goto out_free_cache; |
| 118 | |
| 119 | if (name) { |
| 120 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); |
| 121 | if (!mnt->mnt_devname) |
| 122 | goto out_free_id; |
| 123 | } |
| 124 | |
| 125 | atomic_set(&mnt->mnt_count, 1); |
| 126 | INIT_LIST_HEAD(&mnt->mnt_hash); |
| 127 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 128 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 129 | INIT_LIST_HEAD(&mnt->mnt_list); |
| 130 | INIT_LIST_HEAD(&mnt->mnt_expire); |
| 131 | INIT_LIST_HEAD(&mnt->mnt_share); |
| 132 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 133 | INIT_LIST_HEAD(&mnt->mnt_slave); |
| 134 | #ifdef CONFIG_SMP |
| 135 | mnt->mnt_writers = alloc_percpu(int); |
| 136 | if (!mnt->mnt_writers) |
| 137 | goto out_free_devname; |
| 138 | #else |
| 139 | mnt->mnt_writers = 0; |
| 140 | #endif |
| 141 | } |
| 142 | return mnt; |
| 143 | |
| 144 | #ifdef CONFIG_SMP |
| 145 | out_free_devname: |
| 146 | kfree(mnt->mnt_devname); |
| 147 | #endif |
| 148 | out_free_id: |
| 149 | mnt_free_id(mnt); |
| 150 | out_free_cache: |
| 151 | kmem_cache_free(mnt_cache, mnt); |
| 152 | return NULL; |
| 153 | } |
| 154 | |
| 155 | /* |
| 156 | * Most r/o checks on a fs are for operations that take |
| 157 | * discrete amounts of time, like a write() or unlink(). |
| 158 | * We must keep track of when those operations start |
| 159 | * (for permission checks) and when they end, so that |
| 160 | * we can determine when writes are able to occur to |
| 161 | * a filesystem. |
| 162 | */ |
| 163 | /* |
| 164 | * __mnt_is_readonly: check whether a mount is read-only |
| 165 | * @mnt: the mount to check for its write status |
| 166 | * |
| 167 | * This shouldn't be used directly ouside of the VFS. |
| 168 | * It does not guarantee that the filesystem will stay |
| 169 | * r/w, just that it is right *now*. This can not and |
| 170 | * should not be used in place of IS_RDONLY(inode). |
| 171 | * mnt_want/drop_write() will _keep_ the filesystem |
| 172 | * r/w. |
| 173 | */ |
| 174 | int __mnt_is_readonly(struct vfsmount *mnt) |
| 175 | { |
| 176 | if (mnt->mnt_flags & MNT_READONLY) |
| 177 | return 1; |
| 178 | if (mnt->mnt_sb->s_flags & MS_RDONLY) |
| 179 | return 1; |
| 180 | return 0; |
| 181 | } |
| 182 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 183 | |
| 184 | static inline void inc_mnt_writers(struct vfsmount *mnt) |
| 185 | { |
| 186 | #ifdef CONFIG_SMP |
| 187 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++; |
| 188 | #else |
| 189 | mnt->mnt_writers++; |
| 190 | #endif |
| 191 | } |
| 192 | |
| 193 | static inline void dec_mnt_writers(struct vfsmount *mnt) |
| 194 | { |
| 195 | #ifdef CONFIG_SMP |
| 196 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--; |
| 197 | #else |
| 198 | mnt->mnt_writers--; |
| 199 | #endif |
| 200 | } |
| 201 | |
| 202 | static unsigned int count_mnt_writers(struct vfsmount *mnt) |
| 203 | { |
| 204 | #ifdef CONFIG_SMP |
| 205 | unsigned int count = 0; |
| 206 | int cpu; |
| 207 | |
| 208 | for_each_possible_cpu(cpu) { |
| 209 | count += *per_cpu_ptr(mnt->mnt_writers, cpu); |
| 210 | } |
| 211 | |
| 212 | return count; |
| 213 | #else |
| 214 | return mnt->mnt_writers; |
| 215 | #endif |
| 216 | } |
| 217 | |
| 218 | /* |
| 219 | * Most r/o checks on a fs are for operations that take |
| 220 | * discrete amounts of time, like a write() or unlink(). |
| 221 | * We must keep track of when those operations start |
| 222 | * (for permission checks) and when they end, so that |
| 223 | * we can determine when writes are able to occur to |
| 224 | * a filesystem. |
| 225 | */ |
| 226 | /** |
| 227 | * mnt_want_write - get write access to a mount |
| 228 | * @mnt: the mount on which to take a write |
| 229 | * |
| 230 | * This tells the low-level filesystem that a write is |
| 231 | * about to be performed to it, and makes sure that |
| 232 | * writes are allowed before returning success. When |
| 233 | * the write operation is finished, mnt_drop_write() |
| 234 | * must be called. This is effectively a refcount. |
| 235 | */ |
| 236 | int mnt_want_write(struct vfsmount *mnt) |
| 237 | { |
| 238 | int ret = 0; |
| 239 | |
| 240 | preempt_disable(); |
| 241 | inc_mnt_writers(mnt); |
| 242 | /* |
| 243 | * The store to inc_mnt_writers must be visible before we pass |
| 244 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 245 | * incremented count after it has set MNT_WRITE_HOLD. |
| 246 | */ |
| 247 | smp_mb(); |
| 248 | while (mnt->mnt_flags & MNT_WRITE_HOLD) |
| 249 | cpu_relax(); |
| 250 | /* |
| 251 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will |
| 252 | * be set to match its requirements. So we must not load that until |
| 253 | * MNT_WRITE_HOLD is cleared. |
| 254 | */ |
| 255 | smp_rmb(); |
| 256 | if (__mnt_is_readonly(mnt)) { |
| 257 | dec_mnt_writers(mnt); |
| 258 | ret = -EROFS; |
| 259 | goto out; |
| 260 | } |
| 261 | out: |
| 262 | preempt_enable(); |
| 263 | return ret; |
| 264 | } |
| 265 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 266 | |
| 267 | /** |
| 268 | * mnt_drop_write - give up write access to a mount |
| 269 | * @mnt: the mount on which to give up write access |
| 270 | * |
| 271 | * Tells the low-level filesystem that we are done |
| 272 | * performing writes to it. Must be matched with |
| 273 | * mnt_want_write() call above. |
| 274 | */ |
| 275 | void mnt_drop_write(struct vfsmount *mnt) |
| 276 | { |
| 277 | preempt_disable(); |
| 278 | dec_mnt_writers(mnt); |
| 279 | preempt_enable(); |
| 280 | } |
| 281 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 282 | |
| 283 | static int mnt_make_readonly(struct vfsmount *mnt) |
| 284 | { |
| 285 | int ret = 0; |
| 286 | |
| 287 | spin_lock(&vfsmount_lock); |
| 288 | mnt->mnt_flags |= MNT_WRITE_HOLD; |
| 289 | /* |
| 290 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 291 | * should be visible before we do. |
| 292 | */ |
| 293 | smp_mb(); |
| 294 | |
| 295 | /* |
| 296 | * With writers on hold, if this value is zero, then there are |
| 297 | * definitely no active writers (although held writers may subsequently |
| 298 | * increment the count, they'll have to wait, and decrement it after |
| 299 | * seeing MNT_READONLY). |
| 300 | * |
| 301 | * It is OK to have counter incremented on one CPU and decremented on |
| 302 | * another: the sum will add up correctly. The danger would be when we |
| 303 | * sum up each counter, if we read a counter before it is incremented, |
| 304 | * but then read another CPU's count which it has been subsequently |
| 305 | * decremented from -- we would see more decrements than we should. |
| 306 | * MNT_WRITE_HOLD protects against this scenario, because |
| 307 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 308 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 309 | * we're counting up here. |
| 310 | */ |
| 311 | if (count_mnt_writers(mnt) > 0) |
| 312 | ret = -EBUSY; |
| 313 | else |
| 314 | mnt->mnt_flags |= MNT_READONLY; |
| 315 | /* |
| 316 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 317 | * that become unheld will see MNT_READONLY. |
| 318 | */ |
| 319 | smp_wmb(); |
| 320 | mnt->mnt_flags &= ~MNT_WRITE_HOLD; |
| 321 | spin_unlock(&vfsmount_lock); |
| 322 | return ret; |
| 323 | } |
| 324 | |
| 325 | static void __mnt_unmake_readonly(struct vfsmount *mnt) |
| 326 | { |
| 327 | spin_lock(&vfsmount_lock); |
| 328 | mnt->mnt_flags &= ~MNT_READONLY; |
| 329 | spin_unlock(&vfsmount_lock); |
| 330 | } |
| 331 | |
| 332 | void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
| 333 | { |
| 334 | mnt->mnt_sb = sb; |
| 335 | mnt->mnt_root = dget(sb->s_root); |
| 336 | } |
| 337 | |
| 338 | EXPORT_SYMBOL(simple_set_mnt); |
| 339 | |
| 340 | void free_vfsmnt(struct vfsmount *mnt) |
| 341 | { |
| 342 | kfree(mnt->mnt_devname); |
| 343 | mnt_free_id(mnt); |
| 344 | #ifdef CONFIG_SMP |
| 345 | free_percpu(mnt->mnt_writers); |
| 346 | #endif |
| 347 | kmem_cache_free(mnt_cache, mnt); |
| 348 | } |
| 349 | |
| 350 | /* |
| 351 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
| 352 | * @dir. If @dir is set return the first mount else return the last mount. |
| 353 | */ |
| 354 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
| 355 | int dir) |
| 356 | { |
| 357 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
| 358 | struct list_head *tmp = head; |
| 359 | struct vfsmount *p, *found = NULL; |
| 360 | |
| 361 | for (;;) { |
| 362 | tmp = dir ? tmp->next : tmp->prev; |
| 363 | p = NULL; |
| 364 | if (tmp == head) |
| 365 | break; |
| 366 | p = list_entry(tmp, struct vfsmount, mnt_hash); |
| 367 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { |
| 368 | found = p; |
| 369 | break; |
| 370 | } |
| 371 | } |
| 372 | return found; |
| 373 | } |
| 374 | |
| 375 | /* |
| 376 | * lookup_mnt increments the ref count before returning |
| 377 | * the vfsmount struct. |
| 378 | */ |
| 379 | struct vfsmount *lookup_mnt(struct path *path) |
| 380 | { |
| 381 | struct vfsmount *child_mnt; |
| 382 | spin_lock(&vfsmount_lock); |
| 383 | if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) |
| 384 | mntget(child_mnt); |
| 385 | spin_unlock(&vfsmount_lock); |
| 386 | return child_mnt; |
| 387 | } |
| 388 | |
| 389 | static inline int check_mnt(struct vfsmount *mnt) |
| 390 | { |
| 391 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
| 392 | } |
| 393 | |
| 394 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
| 395 | { |
| 396 | if (ns) { |
| 397 | ns->event = ++event; |
| 398 | wake_up_interruptible(&ns->poll); |
| 399 | } |
| 400 | } |
| 401 | |
| 402 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
| 403 | { |
| 404 | if (ns && ns->event != event) { |
| 405 | ns->event = event; |
| 406 | wake_up_interruptible(&ns->poll); |
| 407 | } |
| 408 | } |
| 409 | |
| 410 | static void detach_mnt(struct vfsmount *mnt, struct path *old_path) |
| 411 | { |
| 412 | old_path->dentry = mnt->mnt_mountpoint; |
| 413 | old_path->mnt = mnt->mnt_parent; |
| 414 | mnt->mnt_parent = mnt; |
| 415 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 416 | list_del_init(&mnt->mnt_child); |
| 417 | list_del_init(&mnt->mnt_hash); |
| 418 | old_path->dentry->d_mounted--; |
| 419 | } |
| 420 | |
| 421 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
| 422 | struct vfsmount *child_mnt) |
| 423 | { |
| 424 | child_mnt->mnt_parent = mntget(mnt); |
| 425 | child_mnt->mnt_mountpoint = dget(dentry); |
| 426 | dentry->d_mounted++; |
| 427 | } |
| 428 | |
| 429 | static void attach_mnt(struct vfsmount *mnt, struct path *path) |
| 430 | { |
| 431 | mnt_set_mountpoint(path->mnt, path->dentry, mnt); |
| 432 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 433 | hash(path->mnt, path->dentry)); |
| 434 | list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); |
| 435 | } |
| 436 | |
| 437 | /* |
| 438 | * the caller must hold vfsmount_lock |
| 439 | */ |
| 440 | static void commit_tree(struct vfsmount *mnt) |
| 441 | { |
| 442 | struct vfsmount *parent = mnt->mnt_parent; |
| 443 | struct vfsmount *m; |
| 444 | LIST_HEAD(head); |
| 445 | struct mnt_namespace *n = parent->mnt_ns; |
| 446 | |
| 447 | BUG_ON(parent == mnt); |
| 448 | |
| 449 | list_add_tail(&head, &mnt->mnt_list); |
| 450 | list_for_each_entry(m, &head, mnt_list) |
| 451 | m->mnt_ns = n; |
| 452 | list_splice(&head, n->list.prev); |
| 453 | |
| 454 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
| 455 | hash(parent, mnt->mnt_mountpoint)); |
| 456 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 457 | touch_mnt_namespace(n); |
| 458 | } |
| 459 | |
| 460 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) |
| 461 | { |
| 462 | struct list_head *next = p->mnt_mounts.next; |
| 463 | if (next == &p->mnt_mounts) { |
| 464 | while (1) { |
| 465 | if (p == root) |
| 466 | return NULL; |
| 467 | next = p->mnt_child.next; |
| 468 | if (next != &p->mnt_parent->mnt_mounts) |
| 469 | break; |
| 470 | p = p->mnt_parent; |
| 471 | } |
| 472 | } |
| 473 | return list_entry(next, struct vfsmount, mnt_child); |
| 474 | } |
| 475 | |
| 476 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
| 477 | { |
| 478 | struct list_head *prev = p->mnt_mounts.prev; |
| 479 | while (prev != &p->mnt_mounts) { |
| 480 | p = list_entry(prev, struct vfsmount, mnt_child); |
| 481 | prev = p->mnt_mounts.prev; |
| 482 | } |
| 483 | return p; |
| 484 | } |
| 485 | |
| 486 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
| 487 | int flag) |
| 488 | { |
| 489 | struct super_block *sb = old->mnt_sb; |
| 490 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); |
| 491 | |
| 492 | if (mnt) { |
| 493 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
| 494 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 495 | else |
| 496 | mnt->mnt_group_id = old->mnt_group_id; |
| 497 | |
| 498 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 499 | int err = mnt_alloc_group_id(mnt); |
| 500 | if (err) |
| 501 | goto out_free; |
| 502 | } |
| 503 | |
| 504 | mnt->mnt_flags = old->mnt_flags; |
| 505 | atomic_inc(&sb->s_active); |
| 506 | mnt->mnt_sb = sb; |
| 507 | mnt->mnt_root = dget(root); |
| 508 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 509 | mnt->mnt_parent = mnt; |
| 510 | |
| 511 | if (flag & CL_SLAVE) { |
| 512 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 513 | mnt->mnt_master = old; |
| 514 | CLEAR_MNT_SHARED(mnt); |
| 515 | } else if (!(flag & CL_PRIVATE)) { |
| 516 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) |
| 517 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 518 | if (IS_MNT_SLAVE(old)) |
| 519 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 520 | mnt->mnt_master = old->mnt_master; |
| 521 | } |
| 522 | if (flag & CL_MAKE_SHARED) |
| 523 | set_mnt_shared(mnt); |
| 524 | |
| 525 | /* stick the duplicate mount on the same expiry list |
| 526 | * as the original if that was on one */ |
| 527 | if (flag & CL_EXPIRE) { |
| 528 | if (!list_empty(&old->mnt_expire)) |
| 529 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 530 | } |
| 531 | } |
| 532 | return mnt; |
| 533 | |
| 534 | out_free: |
| 535 | free_vfsmnt(mnt); |
| 536 | return NULL; |
| 537 | } |
| 538 | |
| 539 | static inline void __mntput(struct vfsmount *mnt) |
| 540 | { |
| 541 | struct super_block *sb = mnt->mnt_sb; |
| 542 | /* |
| 543 | * This probably indicates that somebody messed |
| 544 | * up a mnt_want/drop_write() pair. If this |
| 545 | * happens, the filesystem was probably unable |
| 546 | * to make r/w->r/o transitions. |
| 547 | */ |
| 548 | /* |
| 549 | * atomic_dec_and_lock() used to deal with ->mnt_count decrements |
| 550 | * provides barriers, so count_mnt_writers() below is safe. AV |
| 551 | */ |
| 552 | WARN_ON(count_mnt_writers(mnt)); |
| 553 | dput(mnt->mnt_root); |
| 554 | free_vfsmnt(mnt); |
| 555 | deactivate_super(sb); |
| 556 | } |
| 557 | |
| 558 | void mntput_no_expire(struct vfsmount *mnt) |
| 559 | { |
| 560 | repeat: |
| 561 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { |
| 562 | if (likely(!mnt->mnt_pinned)) { |
| 563 | spin_unlock(&vfsmount_lock); |
| 564 | __mntput(mnt); |
| 565 | return; |
| 566 | } |
| 567 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); |
| 568 | mnt->mnt_pinned = 0; |
| 569 | spin_unlock(&vfsmount_lock); |
| 570 | acct_auto_close_mnt(mnt); |
| 571 | security_sb_umount_close(mnt); |
| 572 | goto repeat; |
| 573 | } |
| 574 | } |
| 575 | |
| 576 | EXPORT_SYMBOL(mntput_no_expire); |
| 577 | |
| 578 | void mnt_pin(struct vfsmount *mnt) |
| 579 | { |
| 580 | spin_lock(&vfsmount_lock); |
| 581 | mnt->mnt_pinned++; |
| 582 | spin_unlock(&vfsmount_lock); |
| 583 | } |
| 584 | |
| 585 | EXPORT_SYMBOL(mnt_pin); |
| 586 | |
| 587 | void mnt_unpin(struct vfsmount *mnt) |
| 588 | { |
| 589 | spin_lock(&vfsmount_lock); |
| 590 | if (mnt->mnt_pinned) { |
| 591 | atomic_inc(&mnt->mnt_count); |
| 592 | mnt->mnt_pinned--; |
| 593 | } |
| 594 | spin_unlock(&vfsmount_lock); |
| 595 | } |
| 596 | |
| 597 | EXPORT_SYMBOL(mnt_unpin); |
| 598 | |
| 599 | static inline void mangle(struct seq_file *m, const char *s) |
| 600 | { |
| 601 | seq_escape(m, s, " \t\n\\"); |
| 602 | } |
| 603 | |
| 604 | /* |
| 605 | * Simple .show_options callback for filesystems which don't want to |
| 606 | * implement more complex mount option showing. |
| 607 | * |
| 608 | * See also save_mount_options(). |
| 609 | */ |
| 610 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) |
| 611 | { |
| 612 | const char *options; |
| 613 | |
| 614 | rcu_read_lock(); |
| 615 | options = rcu_dereference(mnt->mnt_sb->s_options); |
| 616 | |
| 617 | if (options != NULL && options[0]) { |
| 618 | seq_putc(m, ','); |
| 619 | mangle(m, options); |
| 620 | } |
| 621 | rcu_read_unlock(); |
| 622 | |
| 623 | return 0; |
| 624 | } |
| 625 | EXPORT_SYMBOL(generic_show_options); |
| 626 | |
| 627 | /* |
| 628 | * If filesystem uses generic_show_options(), this function should be |
| 629 | * called from the fill_super() callback. |
| 630 | * |
| 631 | * The .remount_fs callback usually needs to be handled in a special |
| 632 | * way, to make sure, that previous options are not overwritten if the |
| 633 | * remount fails. |
| 634 | * |
| 635 | * Also note, that if the filesystem's .remount_fs function doesn't |
| 636 | * reset all options to their default value, but changes only newly |
| 637 | * given options, then the displayed options will not reflect reality |
| 638 | * any more. |
| 639 | */ |
| 640 | void save_mount_options(struct super_block *sb, char *options) |
| 641 | { |
| 642 | BUG_ON(sb->s_options); |
| 643 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); |
| 644 | } |
| 645 | EXPORT_SYMBOL(save_mount_options); |
| 646 | |
| 647 | void replace_mount_options(struct super_block *sb, char *options) |
| 648 | { |
| 649 | char *old = sb->s_options; |
| 650 | rcu_assign_pointer(sb->s_options, options); |
| 651 | if (old) { |
| 652 | synchronize_rcu(); |
| 653 | kfree(old); |
| 654 | } |
| 655 | } |
| 656 | EXPORT_SYMBOL(replace_mount_options); |
| 657 | |
| 658 | #ifdef CONFIG_PROC_FS |
| 659 | /* iterator */ |
| 660 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 661 | { |
| 662 | struct proc_mounts *p = m->private; |
| 663 | |
| 664 | down_read(&namespace_sem); |
| 665 | return seq_list_start(&p->ns->list, *pos); |
| 666 | } |
| 667 | |
| 668 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 669 | { |
| 670 | struct proc_mounts *p = m->private; |
| 671 | |
| 672 | return seq_list_next(v, &p->ns->list, pos); |
| 673 | } |
| 674 | |
| 675 | static void m_stop(struct seq_file *m, void *v) |
| 676 | { |
| 677 | up_read(&namespace_sem); |
| 678 | } |
| 679 | |
| 680 | struct proc_fs_info { |
| 681 | int flag; |
| 682 | const char *str; |
| 683 | }; |
| 684 | |
| 685 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
| 686 | { |
| 687 | static const struct proc_fs_info fs_info[] = { |
| 688 | { MS_SYNCHRONOUS, ",sync" }, |
| 689 | { MS_DIRSYNC, ",dirsync" }, |
| 690 | { MS_MANDLOCK, ",mand" }, |
| 691 | { 0, NULL } |
| 692 | }; |
| 693 | const struct proc_fs_info *fs_infop; |
| 694 | |
| 695 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { |
| 696 | if (sb->s_flags & fs_infop->flag) |
| 697 | seq_puts(m, fs_infop->str); |
| 698 | } |
| 699 | |
| 700 | return security_sb_show_options(m, sb); |
| 701 | } |
| 702 | |
| 703 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) |
| 704 | { |
| 705 | static const struct proc_fs_info mnt_info[] = { |
| 706 | { MNT_NOSUID, ",nosuid" }, |
| 707 | { MNT_NODEV, ",nodev" }, |
| 708 | { MNT_NOEXEC, ",noexec" }, |
| 709 | { MNT_NOATIME, ",noatime" }, |
| 710 | { MNT_NODIRATIME, ",nodiratime" }, |
| 711 | { MNT_RELATIME, ",relatime" }, |
| 712 | { MNT_STRICTATIME, ",strictatime" }, |
| 713 | { 0, NULL } |
| 714 | }; |
| 715 | const struct proc_fs_info *fs_infop; |
| 716 | |
| 717 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { |
| 718 | if (mnt->mnt_flags & fs_infop->flag) |
| 719 | seq_puts(m, fs_infop->str); |
| 720 | } |
| 721 | } |
| 722 | |
| 723 | static void show_type(struct seq_file *m, struct super_block *sb) |
| 724 | { |
| 725 | mangle(m, sb->s_type->name); |
| 726 | if (sb->s_subtype && sb->s_subtype[0]) { |
| 727 | seq_putc(m, '.'); |
| 728 | mangle(m, sb->s_subtype); |
| 729 | } |
| 730 | } |
| 731 | |
| 732 | static int show_vfsmnt(struct seq_file *m, void *v) |
| 733 | { |
| 734 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
| 735 | int err = 0; |
| 736 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
| 737 | |
| 738 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 739 | seq_putc(m, ' '); |
| 740 | seq_path(m, &mnt_path, " \t\n\\"); |
| 741 | seq_putc(m, ' '); |
| 742 | show_type(m, mnt->mnt_sb); |
| 743 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
| 744 | err = show_sb_opts(m, mnt->mnt_sb); |
| 745 | if (err) |
| 746 | goto out; |
| 747 | show_mnt_opts(m, mnt); |
| 748 | if (mnt->mnt_sb->s_op->show_options) |
| 749 | err = mnt->mnt_sb->s_op->show_options(m, mnt); |
| 750 | seq_puts(m, " 0 0\n"); |
| 751 | out: |
| 752 | return err; |
| 753 | } |
| 754 | |
| 755 | const struct seq_operations mounts_op = { |
| 756 | .start = m_start, |
| 757 | .next = m_next, |
| 758 | .stop = m_stop, |
| 759 | .show = show_vfsmnt |
| 760 | }; |
| 761 | |
| 762 | static int show_mountinfo(struct seq_file *m, void *v) |
| 763 | { |
| 764 | struct proc_mounts *p = m->private; |
| 765 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
| 766 | struct super_block *sb = mnt->mnt_sb; |
| 767 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
| 768 | struct path root = p->root; |
| 769 | int err = 0; |
| 770 | |
| 771 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, |
| 772 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); |
| 773 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); |
| 774 | seq_putc(m, ' '); |
| 775 | seq_path_root(m, &mnt_path, &root, " \t\n\\"); |
| 776 | if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { |
| 777 | /* |
| 778 | * Mountpoint is outside root, discard that one. Ugly, |
| 779 | * but less so than trying to do that in iterator in a |
| 780 | * race-free way (due to renames). |
| 781 | */ |
| 782 | return SEQ_SKIP; |
| 783 | } |
| 784 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); |
| 785 | show_mnt_opts(m, mnt); |
| 786 | |
| 787 | /* Tagged fields ("foo:X" or "bar") */ |
| 788 | if (IS_MNT_SHARED(mnt)) |
| 789 | seq_printf(m, " shared:%i", mnt->mnt_group_id); |
| 790 | if (IS_MNT_SLAVE(mnt)) { |
| 791 | int master = mnt->mnt_master->mnt_group_id; |
| 792 | int dom = get_dominating_id(mnt, &p->root); |
| 793 | seq_printf(m, " master:%i", master); |
| 794 | if (dom && dom != master) |
| 795 | seq_printf(m, " propagate_from:%i", dom); |
| 796 | } |
| 797 | if (IS_MNT_UNBINDABLE(mnt)) |
| 798 | seq_puts(m, " unbindable"); |
| 799 | |
| 800 | /* Filesystem specific data */ |
| 801 | seq_puts(m, " - "); |
| 802 | show_type(m, sb); |
| 803 | seq_putc(m, ' '); |
| 804 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); |
| 805 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
| 806 | err = show_sb_opts(m, sb); |
| 807 | if (err) |
| 808 | goto out; |
| 809 | if (sb->s_op->show_options) |
| 810 | err = sb->s_op->show_options(m, mnt); |
| 811 | seq_putc(m, '\n'); |
| 812 | out: |
| 813 | return err; |
| 814 | } |
| 815 | |
| 816 | const struct seq_operations mountinfo_op = { |
| 817 | .start = m_start, |
| 818 | .next = m_next, |
| 819 | .stop = m_stop, |
| 820 | .show = show_mountinfo, |
| 821 | }; |
| 822 | |
| 823 | static int show_vfsstat(struct seq_file *m, void *v) |
| 824 | { |
| 825 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
| 826 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
| 827 | int err = 0; |
| 828 | |
| 829 | /* device */ |
| 830 | if (mnt->mnt_devname) { |
| 831 | seq_puts(m, "device "); |
| 832 | mangle(m, mnt->mnt_devname); |
| 833 | } else |
| 834 | seq_puts(m, "no device"); |
| 835 | |
| 836 | /* mount point */ |
| 837 | seq_puts(m, " mounted on "); |
| 838 | seq_path(m, &mnt_path, " \t\n\\"); |
| 839 | seq_putc(m, ' '); |
| 840 | |
| 841 | /* file system type */ |
| 842 | seq_puts(m, "with fstype "); |
| 843 | show_type(m, mnt->mnt_sb); |
| 844 | |
| 845 | /* optional statistics */ |
| 846 | if (mnt->mnt_sb->s_op->show_stats) { |
| 847 | seq_putc(m, ' '); |
| 848 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); |
| 849 | } |
| 850 | |
| 851 | seq_putc(m, '\n'); |
| 852 | return err; |
| 853 | } |
| 854 | |
| 855 | const struct seq_operations mountstats_op = { |
| 856 | .start = m_start, |
| 857 | .next = m_next, |
| 858 | .stop = m_stop, |
| 859 | .show = show_vfsstat, |
| 860 | }; |
| 861 | #endif /* CONFIG_PROC_FS */ |
| 862 | |
| 863 | /** |
| 864 | * may_umount_tree - check if a mount tree is busy |
| 865 | * @mnt: root of mount tree |
| 866 | * |
| 867 | * This is called to check if a tree of mounts has any |
| 868 | * open files, pwds, chroots or sub mounts that are |
| 869 | * busy. |
| 870 | */ |
| 871 | int may_umount_tree(struct vfsmount *mnt) |
| 872 | { |
| 873 | int actual_refs = 0; |
| 874 | int minimum_refs = 0; |
| 875 | struct vfsmount *p; |
| 876 | |
| 877 | spin_lock(&vfsmount_lock); |
| 878 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 879 | actual_refs += atomic_read(&p->mnt_count); |
| 880 | minimum_refs += 2; |
| 881 | } |
| 882 | spin_unlock(&vfsmount_lock); |
| 883 | |
| 884 | if (actual_refs > minimum_refs) |
| 885 | return 0; |
| 886 | |
| 887 | return 1; |
| 888 | } |
| 889 | |
| 890 | EXPORT_SYMBOL(may_umount_tree); |
| 891 | |
| 892 | /** |
| 893 | * may_umount - check if a mount point is busy |
| 894 | * @mnt: root of mount |
| 895 | * |
| 896 | * This is called to check if a mount point has any |
| 897 | * open files, pwds, chroots or sub mounts. If the |
| 898 | * mount has sub mounts this will return busy |
| 899 | * regardless of whether the sub mounts are busy. |
| 900 | * |
| 901 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 902 | * give false negatives. The main reason why it's here is that we need |
| 903 | * a non-destructive way to look for easily umountable filesystems. |
| 904 | */ |
| 905 | int may_umount(struct vfsmount *mnt) |
| 906 | { |
| 907 | int ret = 1; |
| 908 | spin_lock(&vfsmount_lock); |
| 909 | if (propagate_mount_busy(mnt, 2)) |
| 910 | ret = 0; |
| 911 | spin_unlock(&vfsmount_lock); |
| 912 | return ret; |
| 913 | } |
| 914 | |
| 915 | EXPORT_SYMBOL(may_umount); |
| 916 | |
| 917 | void release_mounts(struct list_head *head) |
| 918 | { |
| 919 | struct vfsmount *mnt; |
| 920 | while (!list_empty(head)) { |
| 921 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
| 922 | list_del_init(&mnt->mnt_hash); |
| 923 | if (mnt->mnt_parent != mnt) { |
| 924 | struct dentry *dentry; |
| 925 | struct vfsmount *m; |
| 926 | spin_lock(&vfsmount_lock); |
| 927 | dentry = mnt->mnt_mountpoint; |
| 928 | m = mnt->mnt_parent; |
| 929 | mnt->mnt_mountpoint = mnt->mnt_root; |
| 930 | mnt->mnt_parent = mnt; |
| 931 | m->mnt_ghosts--; |
| 932 | spin_unlock(&vfsmount_lock); |
| 933 | dput(dentry); |
| 934 | mntput(m); |
| 935 | } |
| 936 | mntput(mnt); |
| 937 | } |
| 938 | } |
| 939 | |
| 940 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
| 941 | { |
| 942 | struct vfsmount *p; |
| 943 | |
| 944 | for (p = mnt; p; p = next_mnt(p, mnt)) |
| 945 | list_move(&p->mnt_hash, kill); |
| 946 | |
| 947 | if (propagate) |
| 948 | propagate_umount(kill); |
| 949 | |
| 950 | list_for_each_entry(p, kill, mnt_hash) { |
| 951 | list_del_init(&p->mnt_expire); |
| 952 | list_del_init(&p->mnt_list); |
| 953 | __touch_mnt_namespace(p->mnt_ns); |
| 954 | p->mnt_ns = NULL; |
| 955 | list_del_init(&p->mnt_child); |
| 956 | if (p->mnt_parent != p) { |
| 957 | p->mnt_parent->mnt_ghosts++; |
| 958 | p->mnt_mountpoint->d_mounted--; |
| 959 | } |
| 960 | change_mnt_propagation(p, MS_PRIVATE); |
| 961 | } |
| 962 | } |
| 963 | |
| 964 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); |
| 965 | |
| 966 | static int do_umount(struct vfsmount *mnt, int flags) |
| 967 | { |
| 968 | struct super_block *sb = mnt->mnt_sb; |
| 969 | int retval; |
| 970 | LIST_HEAD(umount_list); |
| 971 | |
| 972 | retval = security_sb_umount(mnt, flags); |
| 973 | if (retval) |
| 974 | return retval; |
| 975 | |
| 976 | /* |
| 977 | * Allow userspace to request a mountpoint be expired rather than |
| 978 | * unmounting unconditionally. Unmount only happens if: |
| 979 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 980 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 981 | */ |
| 982 | if (flags & MNT_EXPIRE) { |
| 983 | if (mnt == current->fs->root.mnt || |
| 984 | flags & (MNT_FORCE | MNT_DETACH)) |
| 985 | return -EINVAL; |
| 986 | |
| 987 | if (atomic_read(&mnt->mnt_count) != 2) |
| 988 | return -EBUSY; |
| 989 | |
| 990 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
| 991 | return -EAGAIN; |
| 992 | } |
| 993 | |
| 994 | /* |
| 995 | * If we may have to abort operations to get out of this |
| 996 | * mount, and they will themselves hold resources we must |
| 997 | * allow the fs to do things. In the Unix tradition of |
| 998 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 999 | * might fail to complete on the first run through as other tasks |
| 1000 | * must return, and the like. Thats for the mount program to worry |
| 1001 | * about for the moment. |
| 1002 | */ |
| 1003 | |
| 1004 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
| 1005 | sb->s_op->umount_begin(sb); |
| 1006 | } |
| 1007 | |
| 1008 | /* |
| 1009 | * No sense to grab the lock for this test, but test itself looks |
| 1010 | * somewhat bogus. Suggestions for better replacement? |
| 1011 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1012 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1013 | * Actually it makes sense, especially if rootfs would contain a |
| 1014 | * /reboot - static binary that would close all descriptors and |
| 1015 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1016 | */ |
| 1017 | if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
| 1018 | /* |
| 1019 | * Special case for "unmounting" root ... |
| 1020 | * we just try to remount it readonly. |
| 1021 | */ |
| 1022 | down_write(&sb->s_umount); |
| 1023 | if (!(sb->s_flags & MS_RDONLY)) { |
| 1024 | lock_kernel(); |
| 1025 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
| 1026 | unlock_kernel(); |
| 1027 | } |
| 1028 | up_write(&sb->s_umount); |
| 1029 | return retval; |
| 1030 | } |
| 1031 | |
| 1032 | down_write(&namespace_sem); |
| 1033 | spin_lock(&vfsmount_lock); |
| 1034 | event++; |
| 1035 | |
| 1036 | if (!(flags & MNT_DETACH)) |
| 1037 | shrink_submounts(mnt, &umount_list); |
| 1038 | |
| 1039 | retval = -EBUSY; |
| 1040 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
| 1041 | if (!list_empty(&mnt->mnt_list)) |
| 1042 | umount_tree(mnt, 1, &umount_list); |
| 1043 | retval = 0; |
| 1044 | } |
| 1045 | spin_unlock(&vfsmount_lock); |
| 1046 | if (retval) |
| 1047 | security_sb_umount_busy(mnt); |
| 1048 | up_write(&namespace_sem); |
| 1049 | release_mounts(&umount_list); |
| 1050 | return retval; |
| 1051 | } |
| 1052 | |
| 1053 | /* |
| 1054 | * Now umount can handle mount points as well as block devices. |
| 1055 | * This is important for filesystems which use unnamed block devices. |
| 1056 | * |
| 1057 | * We now support a flag for forced unmount like the other 'big iron' |
| 1058 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 1059 | */ |
| 1060 | |
| 1061 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
| 1062 | { |
| 1063 | struct path path; |
| 1064 | int retval; |
| 1065 | |
| 1066 | retval = user_path(name, &path); |
| 1067 | if (retval) |
| 1068 | goto out; |
| 1069 | retval = -EINVAL; |
| 1070 | if (path.dentry != path.mnt->mnt_root) |
| 1071 | goto dput_and_out; |
| 1072 | if (!check_mnt(path.mnt)) |
| 1073 | goto dput_and_out; |
| 1074 | |
| 1075 | retval = -EPERM; |
| 1076 | if (!capable(CAP_SYS_ADMIN)) |
| 1077 | goto dput_and_out; |
| 1078 | |
| 1079 | retval = do_umount(path.mnt, flags); |
| 1080 | dput_and_out: |
| 1081 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
| 1082 | dput(path.dentry); |
| 1083 | mntput_no_expire(path.mnt); |
| 1084 | out: |
| 1085 | return retval; |
| 1086 | } |
| 1087 | |
| 1088 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1089 | |
| 1090 | /* |
| 1091 | * The 2.0 compatible umount. No flags. |
| 1092 | */ |
| 1093 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
| 1094 | { |
| 1095 | return sys_umount(name, 0); |
| 1096 | } |
| 1097 | |
| 1098 | #endif |
| 1099 | |
| 1100 | static int mount_is_safe(struct path *path) |
| 1101 | { |
| 1102 | if (capable(CAP_SYS_ADMIN)) |
| 1103 | return 0; |
| 1104 | return -EPERM; |
| 1105 | #ifdef notyet |
| 1106 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
| 1107 | return -EPERM; |
| 1108 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
| 1109 | if (current_uid() != path->dentry->d_inode->i_uid) |
| 1110 | return -EPERM; |
| 1111 | } |
| 1112 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
| 1113 | return -EPERM; |
| 1114 | return 0; |
| 1115 | #endif |
| 1116 | } |
| 1117 | |
| 1118 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
| 1119 | int flag) |
| 1120 | { |
| 1121 | struct vfsmount *res, *p, *q, *r, *s; |
| 1122 | struct path path; |
| 1123 | |
| 1124 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
| 1125 | return NULL; |
| 1126 | |
| 1127 | res = q = clone_mnt(mnt, dentry, flag); |
| 1128 | if (!q) |
| 1129 | goto Enomem; |
| 1130 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
| 1131 | |
| 1132 | p = mnt; |
| 1133 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
| 1134 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
| 1135 | continue; |
| 1136 | |
| 1137 | for (s = r; s; s = next_mnt(s, r)) { |
| 1138 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
| 1139 | s = skip_mnt_tree(s); |
| 1140 | continue; |
| 1141 | } |
| 1142 | while (p != s->mnt_parent) { |
| 1143 | p = p->mnt_parent; |
| 1144 | q = q->mnt_parent; |
| 1145 | } |
| 1146 | p = s; |
| 1147 | path.mnt = q; |
| 1148 | path.dentry = p->mnt_mountpoint; |
| 1149 | q = clone_mnt(p, p->mnt_root, flag); |
| 1150 | if (!q) |
| 1151 | goto Enomem; |
| 1152 | spin_lock(&vfsmount_lock); |
| 1153 | list_add_tail(&q->mnt_list, &res->mnt_list); |
| 1154 | attach_mnt(q, &path); |
| 1155 | spin_unlock(&vfsmount_lock); |
| 1156 | } |
| 1157 | } |
| 1158 | return res; |
| 1159 | Enomem: |
| 1160 | if (res) { |
| 1161 | LIST_HEAD(umount_list); |
| 1162 | spin_lock(&vfsmount_lock); |
| 1163 | umount_tree(res, 0, &umount_list); |
| 1164 | spin_unlock(&vfsmount_lock); |
| 1165 | release_mounts(&umount_list); |
| 1166 | } |
| 1167 | return NULL; |
| 1168 | } |
| 1169 | |
| 1170 | struct vfsmount *collect_mounts(struct path *path) |
| 1171 | { |
| 1172 | struct vfsmount *tree; |
| 1173 | down_write(&namespace_sem); |
| 1174 | tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); |
| 1175 | up_write(&namespace_sem); |
| 1176 | return tree; |
| 1177 | } |
| 1178 | |
| 1179 | void drop_collected_mounts(struct vfsmount *mnt) |
| 1180 | { |
| 1181 | LIST_HEAD(umount_list); |
| 1182 | down_write(&namespace_sem); |
| 1183 | spin_lock(&vfsmount_lock); |
| 1184 | umount_tree(mnt, 0, &umount_list); |
| 1185 | spin_unlock(&vfsmount_lock); |
| 1186 | up_write(&namespace_sem); |
| 1187 | release_mounts(&umount_list); |
| 1188 | } |
| 1189 | |
| 1190 | static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) |
| 1191 | { |
| 1192 | struct vfsmount *p; |
| 1193 | |
| 1194 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
| 1195 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
| 1196 | mnt_release_group_id(p); |
| 1197 | } |
| 1198 | } |
| 1199 | |
| 1200 | static int invent_group_ids(struct vfsmount *mnt, bool recurse) |
| 1201 | { |
| 1202 | struct vfsmount *p; |
| 1203 | |
| 1204 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
| 1205 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
| 1206 | int err = mnt_alloc_group_id(p); |
| 1207 | if (err) { |
| 1208 | cleanup_group_ids(mnt, p); |
| 1209 | return err; |
| 1210 | } |
| 1211 | } |
| 1212 | } |
| 1213 | |
| 1214 | return 0; |
| 1215 | } |
| 1216 | |
| 1217 | /* |
| 1218 | * @source_mnt : mount tree to be attached |
| 1219 | * @nd : place the mount tree @source_mnt is attached |
| 1220 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 1221 | * store the parent mount and mountpoint dentry. |
| 1222 | * (done when source_mnt is moved) |
| 1223 | * |
| 1224 | * NOTE: in the table below explains the semantics when a source mount |
| 1225 | * of a given type is attached to a destination mount of a given type. |
| 1226 | * --------------------------------------------------------------------------- |
| 1227 | * | BIND MOUNT OPERATION | |
| 1228 | * |************************************************************************** |
| 1229 | * | source-->| shared | private | slave | unbindable | |
| 1230 | * | dest | | | | | |
| 1231 | * | | | | | | | |
| 1232 | * | v | | | | | |
| 1233 | * |************************************************************************** |
| 1234 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 1235 | * | | | | | | |
| 1236 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 1237 | * *************************************************************************** |
| 1238 | * A bind operation clones the source mount and mounts the clone on the |
| 1239 | * destination mount. |
| 1240 | * |
| 1241 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 1242 | * tree of the destination mount and the cloned mount is added to |
| 1243 | * the peer group of the source mount. |
| 1244 | * (+) the cloned mount is created under the destination mount and is marked |
| 1245 | * as shared. The cloned mount is added to the peer group of the source |
| 1246 | * mount. |
| 1247 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 1248 | * of the destination mount and the cloned mount is made slave |
| 1249 | * of the same master as that of the source mount. The cloned mount |
| 1250 | * is marked as 'shared and slave'. |
| 1251 | * (*) the cloned mount is made a slave of the same master as that of the |
| 1252 | * source mount. |
| 1253 | * |
| 1254 | * --------------------------------------------------------------------------- |
| 1255 | * | MOVE MOUNT OPERATION | |
| 1256 | * |************************************************************************** |
| 1257 | * | source-->| shared | private | slave | unbindable | |
| 1258 | * | dest | | | | | |
| 1259 | * | | | | | | | |
| 1260 | * | v | | | | | |
| 1261 | * |************************************************************************** |
| 1262 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 1263 | * | | | | | | |
| 1264 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 1265 | * *************************************************************************** |
| 1266 | * |
| 1267 | * (+) the mount is moved to the destination. And is then propagated to |
| 1268 | * all the mounts in the propagation tree of the destination mount. |
| 1269 | * (+*) the mount is moved to the destination. |
| 1270 | * (+++) the mount is moved to the destination and is then propagated to |
| 1271 | * all the mounts belonging to the destination mount's propagation tree. |
| 1272 | * the mount is marked as 'shared and slave'. |
| 1273 | * (*) the mount continues to be a slave at the new location. |
| 1274 | * |
| 1275 | * if the source mount is a tree, the operations explained above is |
| 1276 | * applied to each mount in the tree. |
| 1277 | * Must be called without spinlocks held, since this function can sleep |
| 1278 | * in allocations. |
| 1279 | */ |
| 1280 | static int attach_recursive_mnt(struct vfsmount *source_mnt, |
| 1281 | struct path *path, struct path *parent_path) |
| 1282 | { |
| 1283 | LIST_HEAD(tree_list); |
| 1284 | struct vfsmount *dest_mnt = path->mnt; |
| 1285 | struct dentry *dest_dentry = path->dentry; |
| 1286 | struct vfsmount *child, *p; |
| 1287 | int err; |
| 1288 | |
| 1289 | if (IS_MNT_SHARED(dest_mnt)) { |
| 1290 | err = invent_group_ids(source_mnt, true); |
| 1291 | if (err) |
| 1292 | goto out; |
| 1293 | } |
| 1294 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); |
| 1295 | if (err) |
| 1296 | goto out_cleanup_ids; |
| 1297 | |
| 1298 | if (IS_MNT_SHARED(dest_mnt)) { |
| 1299 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
| 1300 | set_mnt_shared(p); |
| 1301 | } |
| 1302 | |
| 1303 | spin_lock(&vfsmount_lock); |
| 1304 | if (parent_path) { |
| 1305 | detach_mnt(source_mnt, parent_path); |
| 1306 | attach_mnt(source_mnt, path); |
| 1307 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
| 1308 | } else { |
| 1309 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
| 1310 | commit_tree(source_mnt); |
| 1311 | } |
| 1312 | |
| 1313 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
| 1314 | list_del_init(&child->mnt_hash); |
| 1315 | commit_tree(child); |
| 1316 | } |
| 1317 | spin_unlock(&vfsmount_lock); |
| 1318 | return 0; |
| 1319 | |
| 1320 | out_cleanup_ids: |
| 1321 | if (IS_MNT_SHARED(dest_mnt)) |
| 1322 | cleanup_group_ids(source_mnt, NULL); |
| 1323 | out: |
| 1324 | return err; |
| 1325 | } |
| 1326 | |
| 1327 | static int graft_tree(struct vfsmount *mnt, struct path *path) |
| 1328 | { |
| 1329 | int err; |
| 1330 | if (mnt->mnt_sb->s_flags & MS_NOUSER) |
| 1331 | return -EINVAL; |
| 1332 | |
| 1333 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
| 1334 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
| 1335 | return -ENOTDIR; |
| 1336 | |
| 1337 | err = -ENOENT; |
| 1338 | mutex_lock(&path->dentry->d_inode->i_mutex); |
| 1339 | if (IS_DEADDIR(path->dentry->d_inode)) |
| 1340 | goto out_unlock; |
| 1341 | |
| 1342 | err = security_sb_check_sb(mnt, path); |
| 1343 | if (err) |
| 1344 | goto out_unlock; |
| 1345 | |
| 1346 | err = -ENOENT; |
| 1347 | if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry)) |
| 1348 | err = attach_recursive_mnt(mnt, path, NULL); |
| 1349 | out_unlock: |
| 1350 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
| 1351 | if (!err) |
| 1352 | security_sb_post_addmount(mnt, path); |
| 1353 | return err; |
| 1354 | } |
| 1355 | |
| 1356 | /* |
| 1357 | * recursively change the type of the mountpoint. |
| 1358 | */ |
| 1359 | static int do_change_type(struct path *path, int flag) |
| 1360 | { |
| 1361 | struct vfsmount *m, *mnt = path->mnt; |
| 1362 | int recurse = flag & MS_REC; |
| 1363 | int type = flag & ~MS_REC; |
| 1364 | int err = 0; |
| 1365 | |
| 1366 | if (!capable(CAP_SYS_ADMIN)) |
| 1367 | return -EPERM; |
| 1368 | |
| 1369 | if (path->dentry != path->mnt->mnt_root) |
| 1370 | return -EINVAL; |
| 1371 | |
| 1372 | down_write(&namespace_sem); |
| 1373 | if (type == MS_SHARED) { |
| 1374 | err = invent_group_ids(mnt, recurse); |
| 1375 | if (err) |
| 1376 | goto out_unlock; |
| 1377 | } |
| 1378 | |
| 1379 | spin_lock(&vfsmount_lock); |
| 1380 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
| 1381 | change_mnt_propagation(m, type); |
| 1382 | spin_unlock(&vfsmount_lock); |
| 1383 | |
| 1384 | out_unlock: |
| 1385 | up_write(&namespace_sem); |
| 1386 | return err; |
| 1387 | } |
| 1388 | |
| 1389 | /* |
| 1390 | * do loopback mount. |
| 1391 | */ |
| 1392 | static int do_loopback(struct path *path, char *old_name, |
| 1393 | int recurse) |
| 1394 | { |
| 1395 | struct path old_path; |
| 1396 | struct vfsmount *mnt = NULL; |
| 1397 | int err = mount_is_safe(path); |
| 1398 | if (err) |
| 1399 | return err; |
| 1400 | if (!old_name || !*old_name) |
| 1401 | return -EINVAL; |
| 1402 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
| 1403 | if (err) |
| 1404 | return err; |
| 1405 | |
| 1406 | down_write(&namespace_sem); |
| 1407 | err = -EINVAL; |
| 1408 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
| 1409 | goto out; |
| 1410 | |
| 1411 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
| 1412 | goto out; |
| 1413 | |
| 1414 | err = -ENOMEM; |
| 1415 | if (recurse) |
| 1416 | mnt = copy_tree(old_path.mnt, old_path.dentry, 0); |
| 1417 | else |
| 1418 | mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); |
| 1419 | |
| 1420 | if (!mnt) |
| 1421 | goto out; |
| 1422 | |
| 1423 | err = graft_tree(mnt, path); |
| 1424 | if (err) { |
| 1425 | LIST_HEAD(umount_list); |
| 1426 | spin_lock(&vfsmount_lock); |
| 1427 | umount_tree(mnt, 0, &umount_list); |
| 1428 | spin_unlock(&vfsmount_lock); |
| 1429 | release_mounts(&umount_list); |
| 1430 | } |
| 1431 | |
| 1432 | out: |
| 1433 | up_write(&namespace_sem); |
| 1434 | path_put(&old_path); |
| 1435 | return err; |
| 1436 | } |
| 1437 | |
| 1438 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
| 1439 | { |
| 1440 | int error = 0; |
| 1441 | int readonly_request = 0; |
| 1442 | |
| 1443 | if (ms_flags & MS_RDONLY) |
| 1444 | readonly_request = 1; |
| 1445 | if (readonly_request == __mnt_is_readonly(mnt)) |
| 1446 | return 0; |
| 1447 | |
| 1448 | if (readonly_request) |
| 1449 | error = mnt_make_readonly(mnt); |
| 1450 | else |
| 1451 | __mnt_unmake_readonly(mnt); |
| 1452 | return error; |
| 1453 | } |
| 1454 | |
| 1455 | /* |
| 1456 | * change filesystem flags. dir should be a physical root of filesystem. |
| 1457 | * If you've mounted a non-root directory somewhere and want to do remount |
| 1458 | * on it - tough luck. |
| 1459 | */ |
| 1460 | static int do_remount(struct path *path, int flags, int mnt_flags, |
| 1461 | void *data) |
| 1462 | { |
| 1463 | int err; |
| 1464 | struct super_block *sb = path->mnt->mnt_sb; |
| 1465 | |
| 1466 | if (!capable(CAP_SYS_ADMIN)) |
| 1467 | return -EPERM; |
| 1468 | |
| 1469 | if (!check_mnt(path->mnt)) |
| 1470 | return -EINVAL; |
| 1471 | |
| 1472 | if (path->dentry != path->mnt->mnt_root) |
| 1473 | return -EINVAL; |
| 1474 | |
| 1475 | down_write(&sb->s_umount); |
| 1476 | if (flags & MS_BIND) |
| 1477 | err = change_mount_flags(path->mnt, flags); |
| 1478 | else |
| 1479 | err = do_remount_sb(sb, flags, data, 0); |
| 1480 | if (!err) |
| 1481 | path->mnt->mnt_flags = mnt_flags; |
| 1482 | up_write(&sb->s_umount); |
| 1483 | if (!err) { |
| 1484 | security_sb_post_remount(path->mnt, flags, data); |
| 1485 | |
| 1486 | spin_lock(&vfsmount_lock); |
| 1487 | touch_mnt_namespace(path->mnt->mnt_ns); |
| 1488 | spin_unlock(&vfsmount_lock); |
| 1489 | } |
| 1490 | return err; |
| 1491 | } |
| 1492 | |
| 1493 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
| 1494 | { |
| 1495 | struct vfsmount *p; |
| 1496 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1497 | if (IS_MNT_UNBINDABLE(p)) |
| 1498 | return 1; |
| 1499 | } |
| 1500 | return 0; |
| 1501 | } |
| 1502 | |
| 1503 | static int do_move_mount(struct path *path, char *old_name) |
| 1504 | { |
| 1505 | struct path old_path, parent_path; |
| 1506 | struct vfsmount *p; |
| 1507 | int err = 0; |
| 1508 | if (!capable(CAP_SYS_ADMIN)) |
| 1509 | return -EPERM; |
| 1510 | if (!old_name || !*old_name) |
| 1511 | return -EINVAL; |
| 1512 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
| 1513 | if (err) |
| 1514 | return err; |
| 1515 | |
| 1516 | down_write(&namespace_sem); |
| 1517 | while (d_mountpoint(path->dentry) && |
| 1518 | follow_down(path)) |
| 1519 | ; |
| 1520 | err = -EINVAL; |
| 1521 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
| 1522 | goto out; |
| 1523 | |
| 1524 | err = -ENOENT; |
| 1525 | mutex_lock(&path->dentry->d_inode->i_mutex); |
| 1526 | if (IS_DEADDIR(path->dentry->d_inode)) |
| 1527 | goto out1; |
| 1528 | |
| 1529 | if (!IS_ROOT(path->dentry) && d_unhashed(path->dentry)) |
| 1530 | goto out1; |
| 1531 | |
| 1532 | err = -EINVAL; |
| 1533 | if (old_path.dentry != old_path.mnt->mnt_root) |
| 1534 | goto out1; |
| 1535 | |
| 1536 | if (old_path.mnt == old_path.mnt->mnt_parent) |
| 1537 | goto out1; |
| 1538 | |
| 1539 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
| 1540 | S_ISDIR(old_path.dentry->d_inode->i_mode)) |
| 1541 | goto out1; |
| 1542 | /* |
| 1543 | * Don't move a mount residing in a shared parent. |
| 1544 | */ |
| 1545 | if (old_path.mnt->mnt_parent && |
| 1546 | IS_MNT_SHARED(old_path.mnt->mnt_parent)) |
| 1547 | goto out1; |
| 1548 | /* |
| 1549 | * Don't move a mount tree containing unbindable mounts to a destination |
| 1550 | * mount which is shared. |
| 1551 | */ |
| 1552 | if (IS_MNT_SHARED(path->mnt) && |
| 1553 | tree_contains_unbindable(old_path.mnt)) |
| 1554 | goto out1; |
| 1555 | err = -ELOOP; |
| 1556 | for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) |
| 1557 | if (p == old_path.mnt) |
| 1558 | goto out1; |
| 1559 | |
| 1560 | err = attach_recursive_mnt(old_path.mnt, path, &parent_path); |
| 1561 | if (err) |
| 1562 | goto out1; |
| 1563 | |
| 1564 | /* if the mount is moved, it should no longer be expire |
| 1565 | * automatically */ |
| 1566 | list_del_init(&old_path.mnt->mnt_expire); |
| 1567 | out1: |
| 1568 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
| 1569 | out: |
| 1570 | up_write(&namespace_sem); |
| 1571 | if (!err) |
| 1572 | path_put(&parent_path); |
| 1573 | path_put(&old_path); |
| 1574 | return err; |
| 1575 | } |
| 1576 | |
| 1577 | /* |
| 1578 | * create a new mount for userspace and request it to be added into the |
| 1579 | * namespace's tree |
| 1580 | */ |
| 1581 | static int do_new_mount(struct path *path, char *type, int flags, |
| 1582 | int mnt_flags, char *name, void *data) |
| 1583 | { |
| 1584 | struct vfsmount *mnt; |
| 1585 | |
| 1586 | if (!type || !memchr(type, 0, PAGE_SIZE)) |
| 1587 | return -EINVAL; |
| 1588 | |
| 1589 | /* we need capabilities... */ |
| 1590 | if (!capable(CAP_SYS_ADMIN)) |
| 1591 | return -EPERM; |
| 1592 | |
| 1593 | mnt = do_kern_mount(type, flags, name, data); |
| 1594 | if (IS_ERR(mnt)) |
| 1595 | return PTR_ERR(mnt); |
| 1596 | |
| 1597 | return do_add_mount(mnt, path, mnt_flags, NULL); |
| 1598 | } |
| 1599 | |
| 1600 | /* |
| 1601 | * add a mount into a namespace's mount tree |
| 1602 | * - provide the option of adding the new mount to an expiration list |
| 1603 | */ |
| 1604 | int do_add_mount(struct vfsmount *newmnt, struct path *path, |
| 1605 | int mnt_flags, struct list_head *fslist) |
| 1606 | { |
| 1607 | int err; |
| 1608 | |
| 1609 | down_write(&namespace_sem); |
| 1610 | /* Something was mounted here while we slept */ |
| 1611 | while (d_mountpoint(path->dentry) && |
| 1612 | follow_down(path)) |
| 1613 | ; |
| 1614 | err = -EINVAL; |
| 1615 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) |
| 1616 | goto unlock; |
| 1617 | |
| 1618 | /* Refuse the same filesystem on the same mount point */ |
| 1619 | err = -EBUSY; |
| 1620 | if (path->mnt->mnt_sb == newmnt->mnt_sb && |
| 1621 | path->mnt->mnt_root == path->dentry) |
| 1622 | goto unlock; |
| 1623 | |
| 1624 | err = -EINVAL; |
| 1625 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) |
| 1626 | goto unlock; |
| 1627 | |
| 1628 | newmnt->mnt_flags = mnt_flags; |
| 1629 | if ((err = graft_tree(newmnt, path))) |
| 1630 | goto unlock; |
| 1631 | |
| 1632 | if (fslist) /* add to the specified expiration list */ |
| 1633 | list_add_tail(&newmnt->mnt_expire, fslist); |
| 1634 | |
| 1635 | up_write(&namespace_sem); |
| 1636 | return 0; |
| 1637 | |
| 1638 | unlock: |
| 1639 | up_write(&namespace_sem); |
| 1640 | mntput(newmnt); |
| 1641 | return err; |
| 1642 | } |
| 1643 | |
| 1644 | EXPORT_SYMBOL_GPL(do_add_mount); |
| 1645 | |
| 1646 | /* |
| 1647 | * process a list of expirable mountpoints with the intent of discarding any |
| 1648 | * mountpoints that aren't in use and haven't been touched since last we came |
| 1649 | * here |
| 1650 | */ |
| 1651 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 1652 | { |
| 1653 | struct vfsmount *mnt, *next; |
| 1654 | LIST_HEAD(graveyard); |
| 1655 | LIST_HEAD(umounts); |
| 1656 | |
| 1657 | if (list_empty(mounts)) |
| 1658 | return; |
| 1659 | |
| 1660 | down_write(&namespace_sem); |
| 1661 | spin_lock(&vfsmount_lock); |
| 1662 | |
| 1663 | /* extract from the expiration list every vfsmount that matches the |
| 1664 | * following criteria: |
| 1665 | * - only referenced by its parent vfsmount |
| 1666 | * - still marked for expiry (marked on the last call here; marks are |
| 1667 | * cleared by mntput()) |
| 1668 | */ |
| 1669 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
| 1670 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
| 1671 | propagate_mount_busy(mnt, 1)) |
| 1672 | continue; |
| 1673 | list_move(&mnt->mnt_expire, &graveyard); |
| 1674 | } |
| 1675 | while (!list_empty(&graveyard)) { |
| 1676 | mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); |
| 1677 | touch_mnt_namespace(mnt->mnt_ns); |
| 1678 | umount_tree(mnt, 1, &umounts); |
| 1679 | } |
| 1680 | spin_unlock(&vfsmount_lock); |
| 1681 | up_write(&namespace_sem); |
| 1682 | |
| 1683 | release_mounts(&umounts); |
| 1684 | } |
| 1685 | |
| 1686 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 1687 | |
| 1688 | /* |
| 1689 | * Ripoff of 'select_parent()' |
| 1690 | * |
| 1691 | * search the list of submounts for a given mountpoint, and move any |
| 1692 | * shrinkable submounts to the 'graveyard' list. |
| 1693 | */ |
| 1694 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) |
| 1695 | { |
| 1696 | struct vfsmount *this_parent = parent; |
| 1697 | struct list_head *next; |
| 1698 | int found = 0; |
| 1699 | |
| 1700 | repeat: |
| 1701 | next = this_parent->mnt_mounts.next; |
| 1702 | resume: |
| 1703 | while (next != &this_parent->mnt_mounts) { |
| 1704 | struct list_head *tmp = next; |
| 1705 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); |
| 1706 | |
| 1707 | next = tmp->next; |
| 1708 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) |
| 1709 | continue; |
| 1710 | /* |
| 1711 | * Descend a level if the d_mounts list is non-empty. |
| 1712 | */ |
| 1713 | if (!list_empty(&mnt->mnt_mounts)) { |
| 1714 | this_parent = mnt; |
| 1715 | goto repeat; |
| 1716 | } |
| 1717 | |
| 1718 | if (!propagate_mount_busy(mnt, 1)) { |
| 1719 | list_move_tail(&mnt->mnt_expire, graveyard); |
| 1720 | found++; |
| 1721 | } |
| 1722 | } |
| 1723 | /* |
| 1724 | * All done at this level ... ascend and resume the search |
| 1725 | */ |
| 1726 | if (this_parent != parent) { |
| 1727 | next = this_parent->mnt_child.next; |
| 1728 | this_parent = this_parent->mnt_parent; |
| 1729 | goto resume; |
| 1730 | } |
| 1731 | return found; |
| 1732 | } |
| 1733 | |
| 1734 | /* |
| 1735 | * process a list of expirable mountpoints with the intent of discarding any |
| 1736 | * submounts of a specific parent mountpoint |
| 1737 | */ |
| 1738 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) |
| 1739 | { |
| 1740 | LIST_HEAD(graveyard); |
| 1741 | struct vfsmount *m; |
| 1742 | |
| 1743 | /* extract submounts of 'mountpoint' from the expiration list */ |
| 1744 | while (select_submounts(mnt, &graveyard)) { |
| 1745 | while (!list_empty(&graveyard)) { |
| 1746 | m = list_first_entry(&graveyard, struct vfsmount, |
| 1747 | mnt_expire); |
| 1748 | touch_mnt_namespace(m->mnt_ns); |
| 1749 | umount_tree(m, 1, umounts); |
| 1750 | } |
| 1751 | } |
| 1752 | } |
| 1753 | |
| 1754 | /* |
| 1755 | * Some copy_from_user() implementations do not return the exact number of |
| 1756 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 1757 | * Note that this function differs from copy_from_user() in that it will oops |
| 1758 | * on bad values of `to', rather than returning a short copy. |
| 1759 | */ |
| 1760 | static long exact_copy_from_user(void *to, const void __user * from, |
| 1761 | unsigned long n) |
| 1762 | { |
| 1763 | char *t = to; |
| 1764 | const char __user *f = from; |
| 1765 | char c; |
| 1766 | |
| 1767 | if (!access_ok(VERIFY_READ, from, n)) |
| 1768 | return n; |
| 1769 | |
| 1770 | while (n) { |
| 1771 | if (__get_user(c, f)) { |
| 1772 | memset(t, 0, n); |
| 1773 | break; |
| 1774 | } |
| 1775 | *t++ = c; |
| 1776 | f++; |
| 1777 | n--; |
| 1778 | } |
| 1779 | return n; |
| 1780 | } |
| 1781 | |
| 1782 | int copy_mount_options(const void __user * data, unsigned long *where) |
| 1783 | { |
| 1784 | int i; |
| 1785 | unsigned long page; |
| 1786 | unsigned long size; |
| 1787 | |
| 1788 | *where = 0; |
| 1789 | if (!data) |
| 1790 | return 0; |
| 1791 | |
| 1792 | if (!(page = __get_free_page(GFP_KERNEL))) |
| 1793 | return -ENOMEM; |
| 1794 | |
| 1795 | /* We only care that *some* data at the address the user |
| 1796 | * gave us is valid. Just in case, we'll zero |
| 1797 | * the remainder of the page. |
| 1798 | */ |
| 1799 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 1800 | size = TASK_SIZE - (unsigned long)data; |
| 1801 | if (size > PAGE_SIZE) |
| 1802 | size = PAGE_SIZE; |
| 1803 | |
| 1804 | i = size - exact_copy_from_user((void *)page, data, size); |
| 1805 | if (!i) { |
| 1806 | free_page(page); |
| 1807 | return -EFAULT; |
| 1808 | } |
| 1809 | if (i != PAGE_SIZE) |
| 1810 | memset((char *)page + i, 0, PAGE_SIZE - i); |
| 1811 | *where = page; |
| 1812 | return 0; |
| 1813 | } |
| 1814 | |
| 1815 | /* |
| 1816 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 1817 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 1818 | * |
| 1819 | * data is a (void *) that can point to any structure up to |
| 1820 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 1821 | * information (or be NULL). |
| 1822 | * |
| 1823 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 1824 | * When the flags word was introduced its top half was required |
| 1825 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 1826 | * Therefore, if this magic number is present, it carries no information |
| 1827 | * and must be discarded. |
| 1828 | */ |
| 1829 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
| 1830 | unsigned long flags, void *data_page) |
| 1831 | { |
| 1832 | struct path path; |
| 1833 | int retval = 0; |
| 1834 | int mnt_flags = 0; |
| 1835 | |
| 1836 | /* Discard magic */ |
| 1837 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 1838 | flags &= ~MS_MGC_MSK; |
| 1839 | |
| 1840 | /* Basic sanity checks */ |
| 1841 | |
| 1842 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) |
| 1843 | return -EINVAL; |
| 1844 | if (dev_name && !memchr(dev_name, 0, PAGE_SIZE)) |
| 1845 | return -EINVAL; |
| 1846 | |
| 1847 | if (data_page) |
| 1848 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 1849 | |
| 1850 | /* Default to relatime unless overriden */ |
| 1851 | if (!(flags & MS_NOATIME)) |
| 1852 | mnt_flags |= MNT_RELATIME; |
| 1853 | |
| 1854 | /* Separate the per-mountpoint flags */ |
| 1855 | if (flags & MS_NOSUID) |
| 1856 | mnt_flags |= MNT_NOSUID; |
| 1857 | if (flags & MS_NODEV) |
| 1858 | mnt_flags |= MNT_NODEV; |
| 1859 | if (flags & MS_NOEXEC) |
| 1860 | mnt_flags |= MNT_NOEXEC; |
| 1861 | if (flags & MS_NOATIME) |
| 1862 | mnt_flags |= MNT_NOATIME; |
| 1863 | if (flags & MS_NODIRATIME) |
| 1864 | mnt_flags |= MNT_NODIRATIME; |
| 1865 | if (flags & MS_STRICTATIME) |
| 1866 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
| 1867 | if (flags & MS_RDONLY) |
| 1868 | mnt_flags |= MNT_READONLY; |
| 1869 | |
| 1870 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | |
| 1871 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
| 1872 | MS_STRICTATIME); |
| 1873 | |
| 1874 | /* ... and get the mountpoint */ |
| 1875 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); |
| 1876 | if (retval) |
| 1877 | return retval; |
| 1878 | |
| 1879 | retval = security_sb_mount(dev_name, &path, |
| 1880 | type_page, flags, data_page); |
| 1881 | if (retval) |
| 1882 | goto dput_out; |
| 1883 | |
| 1884 | if (flags & MS_REMOUNT) |
| 1885 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
| 1886 | data_page); |
| 1887 | else if (flags & MS_BIND) |
| 1888 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
| 1889 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 1890 | retval = do_change_type(&path, flags); |
| 1891 | else if (flags & MS_MOVE) |
| 1892 | retval = do_move_mount(&path, dev_name); |
| 1893 | else |
| 1894 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
| 1895 | dev_name, data_page); |
| 1896 | dput_out: |
| 1897 | path_put(&path); |
| 1898 | return retval; |
| 1899 | } |
| 1900 | |
| 1901 | /* |
| 1902 | * Allocate a new namespace structure and populate it with contents |
| 1903 | * copied from the namespace of the passed in task structure. |
| 1904 | */ |
| 1905 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
| 1906 | struct fs_struct *fs) |
| 1907 | { |
| 1908 | struct mnt_namespace *new_ns; |
| 1909 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
| 1910 | struct vfsmount *p, *q; |
| 1911 | |
| 1912 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
| 1913 | if (!new_ns) |
| 1914 | return ERR_PTR(-ENOMEM); |
| 1915 | |
| 1916 | atomic_set(&new_ns->count, 1); |
| 1917 | INIT_LIST_HEAD(&new_ns->list); |
| 1918 | init_waitqueue_head(&new_ns->poll); |
| 1919 | new_ns->event = 0; |
| 1920 | |
| 1921 | down_write(&namespace_sem); |
| 1922 | /* First pass: copy the tree topology */ |
| 1923 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
| 1924 | CL_COPY_ALL | CL_EXPIRE); |
| 1925 | if (!new_ns->root) { |
| 1926 | up_write(&namespace_sem); |
| 1927 | kfree(new_ns); |
| 1928 | return ERR_PTR(-ENOMEM); |
| 1929 | } |
| 1930 | spin_lock(&vfsmount_lock); |
| 1931 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
| 1932 | spin_unlock(&vfsmount_lock); |
| 1933 | |
| 1934 | /* |
| 1935 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 1936 | * as belonging to new namespace. We have already acquired a private |
| 1937 | * fs_struct, so tsk->fs->lock is not needed. |
| 1938 | */ |
| 1939 | p = mnt_ns->root; |
| 1940 | q = new_ns->root; |
| 1941 | while (p) { |
| 1942 | q->mnt_ns = new_ns; |
| 1943 | if (fs) { |
| 1944 | if (p == fs->root.mnt) { |
| 1945 | rootmnt = p; |
| 1946 | fs->root.mnt = mntget(q); |
| 1947 | } |
| 1948 | if (p == fs->pwd.mnt) { |
| 1949 | pwdmnt = p; |
| 1950 | fs->pwd.mnt = mntget(q); |
| 1951 | } |
| 1952 | } |
| 1953 | p = next_mnt(p, mnt_ns->root); |
| 1954 | q = next_mnt(q, new_ns->root); |
| 1955 | } |
| 1956 | up_write(&namespace_sem); |
| 1957 | |
| 1958 | if (rootmnt) |
| 1959 | mntput(rootmnt); |
| 1960 | if (pwdmnt) |
| 1961 | mntput(pwdmnt); |
| 1962 | |
| 1963 | return new_ns; |
| 1964 | } |
| 1965 | |
| 1966 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
| 1967 | struct fs_struct *new_fs) |
| 1968 | { |
| 1969 | struct mnt_namespace *new_ns; |
| 1970 | |
| 1971 | BUG_ON(!ns); |
| 1972 | get_mnt_ns(ns); |
| 1973 | |
| 1974 | if (!(flags & CLONE_NEWNS)) |
| 1975 | return ns; |
| 1976 | |
| 1977 | new_ns = dup_mnt_ns(ns, new_fs); |
| 1978 | |
| 1979 | put_mnt_ns(ns); |
| 1980 | return new_ns; |
| 1981 | } |
| 1982 | |
| 1983 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 1984 | char __user *, type, unsigned long, flags, void __user *, data) |
| 1985 | { |
| 1986 | int retval; |
| 1987 | unsigned long data_page; |
| 1988 | unsigned long type_page; |
| 1989 | unsigned long dev_page; |
| 1990 | char *dir_page; |
| 1991 | |
| 1992 | retval = copy_mount_options(type, &type_page); |
| 1993 | if (retval < 0) |
| 1994 | return retval; |
| 1995 | |
| 1996 | dir_page = getname(dir_name); |
| 1997 | retval = PTR_ERR(dir_page); |
| 1998 | if (IS_ERR(dir_page)) |
| 1999 | goto out1; |
| 2000 | |
| 2001 | retval = copy_mount_options(dev_name, &dev_page); |
| 2002 | if (retval < 0) |
| 2003 | goto out2; |
| 2004 | |
| 2005 | retval = copy_mount_options(data, &data_page); |
| 2006 | if (retval < 0) |
| 2007 | goto out3; |
| 2008 | |
| 2009 | lock_kernel(); |
| 2010 | retval = do_mount((char *)dev_page, dir_page, (char *)type_page, |
| 2011 | flags, (void *)data_page); |
| 2012 | unlock_kernel(); |
| 2013 | free_page(data_page); |
| 2014 | |
| 2015 | out3: |
| 2016 | free_page(dev_page); |
| 2017 | out2: |
| 2018 | putname(dir_page); |
| 2019 | out1: |
| 2020 | free_page(type_page); |
| 2021 | return retval; |
| 2022 | } |
| 2023 | |
| 2024 | /* |
| 2025 | * pivot_root Semantics: |
| 2026 | * Moves the root file system of the current process to the directory put_old, |
| 2027 | * makes new_root as the new root file system of the current process, and sets |
| 2028 | * root/cwd of all processes which had them on the current root to new_root. |
| 2029 | * |
| 2030 | * Restrictions: |
| 2031 | * The new_root and put_old must be directories, and must not be on the |
| 2032 | * same file system as the current process root. The put_old must be |
| 2033 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 2034 | * pointed to by put_old must yield the same directory as new_root. No other |
| 2035 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 2036 | * |
| 2037 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
| 2038 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives |
| 2039 | * in this situation. |
| 2040 | * |
| 2041 | * Notes: |
| 2042 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 2043 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 2044 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 2045 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 2046 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 2047 | * first. |
| 2048 | */ |
| 2049 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 2050 | const char __user *, put_old) |
| 2051 | { |
| 2052 | struct vfsmount *tmp; |
| 2053 | struct path new, old, parent_path, root_parent, root; |
| 2054 | int error; |
| 2055 | |
| 2056 | if (!capable(CAP_SYS_ADMIN)) |
| 2057 | return -EPERM; |
| 2058 | |
| 2059 | error = user_path_dir(new_root, &new); |
| 2060 | if (error) |
| 2061 | goto out0; |
| 2062 | error = -EINVAL; |
| 2063 | if (!check_mnt(new.mnt)) |
| 2064 | goto out1; |
| 2065 | |
| 2066 | error = user_path_dir(put_old, &old); |
| 2067 | if (error) |
| 2068 | goto out1; |
| 2069 | |
| 2070 | error = security_sb_pivotroot(&old, &new); |
| 2071 | if (error) { |
| 2072 | path_put(&old); |
| 2073 | goto out1; |
| 2074 | } |
| 2075 | |
| 2076 | read_lock(¤t->fs->lock); |
| 2077 | root = current->fs->root; |
| 2078 | path_get(¤t->fs->root); |
| 2079 | read_unlock(¤t->fs->lock); |
| 2080 | down_write(&namespace_sem); |
| 2081 | mutex_lock(&old.dentry->d_inode->i_mutex); |
| 2082 | error = -EINVAL; |
| 2083 | if (IS_MNT_SHARED(old.mnt) || |
| 2084 | IS_MNT_SHARED(new.mnt->mnt_parent) || |
| 2085 | IS_MNT_SHARED(root.mnt->mnt_parent)) |
| 2086 | goto out2; |
| 2087 | if (!check_mnt(root.mnt)) |
| 2088 | goto out2; |
| 2089 | error = -ENOENT; |
| 2090 | if (IS_DEADDIR(new.dentry->d_inode)) |
| 2091 | goto out2; |
| 2092 | if (d_unhashed(new.dentry) && !IS_ROOT(new.dentry)) |
| 2093 | goto out2; |
| 2094 | if (d_unhashed(old.dentry) && !IS_ROOT(old.dentry)) |
| 2095 | goto out2; |
| 2096 | error = -EBUSY; |
| 2097 | if (new.mnt == root.mnt || |
| 2098 | old.mnt == root.mnt) |
| 2099 | goto out2; /* loop, on the same file system */ |
| 2100 | error = -EINVAL; |
| 2101 | if (root.mnt->mnt_root != root.dentry) |
| 2102 | goto out2; /* not a mountpoint */ |
| 2103 | if (root.mnt->mnt_parent == root.mnt) |
| 2104 | goto out2; /* not attached */ |
| 2105 | if (new.mnt->mnt_root != new.dentry) |
| 2106 | goto out2; /* not a mountpoint */ |
| 2107 | if (new.mnt->mnt_parent == new.mnt) |
| 2108 | goto out2; /* not attached */ |
| 2109 | /* make sure we can reach put_old from new_root */ |
| 2110 | tmp = old.mnt; |
| 2111 | spin_lock(&vfsmount_lock); |
| 2112 | if (tmp != new.mnt) { |
| 2113 | for (;;) { |
| 2114 | if (tmp->mnt_parent == tmp) |
| 2115 | goto out3; /* already mounted on put_old */ |
| 2116 | if (tmp->mnt_parent == new.mnt) |
| 2117 | break; |
| 2118 | tmp = tmp->mnt_parent; |
| 2119 | } |
| 2120 | if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) |
| 2121 | goto out3; |
| 2122 | } else if (!is_subdir(old.dentry, new.dentry)) |
| 2123 | goto out3; |
| 2124 | detach_mnt(new.mnt, &parent_path); |
| 2125 | detach_mnt(root.mnt, &root_parent); |
| 2126 | /* mount old root on put_old */ |
| 2127 | attach_mnt(root.mnt, &old); |
| 2128 | /* mount new_root on / */ |
| 2129 | attach_mnt(new.mnt, &root_parent); |
| 2130 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
| 2131 | spin_unlock(&vfsmount_lock); |
| 2132 | chroot_fs_refs(&root, &new); |
| 2133 | security_sb_post_pivotroot(&root, &new); |
| 2134 | error = 0; |
| 2135 | path_put(&root_parent); |
| 2136 | path_put(&parent_path); |
| 2137 | out2: |
| 2138 | mutex_unlock(&old.dentry->d_inode->i_mutex); |
| 2139 | up_write(&namespace_sem); |
| 2140 | path_put(&root); |
| 2141 | path_put(&old); |
| 2142 | out1: |
| 2143 | path_put(&new); |
| 2144 | out0: |
| 2145 | return error; |
| 2146 | out3: |
| 2147 | spin_unlock(&vfsmount_lock); |
| 2148 | goto out2; |
| 2149 | } |
| 2150 | |
| 2151 | static void __init init_mount_tree(void) |
| 2152 | { |
| 2153 | struct vfsmount *mnt; |
| 2154 | struct mnt_namespace *ns; |
| 2155 | struct path root; |
| 2156 | |
| 2157 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); |
| 2158 | if (IS_ERR(mnt)) |
| 2159 | panic("Can't create rootfs"); |
| 2160 | ns = kmalloc(sizeof(*ns), GFP_KERNEL); |
| 2161 | if (!ns) |
| 2162 | panic("Can't allocate initial namespace"); |
| 2163 | atomic_set(&ns->count, 1); |
| 2164 | INIT_LIST_HEAD(&ns->list); |
| 2165 | init_waitqueue_head(&ns->poll); |
| 2166 | ns->event = 0; |
| 2167 | list_add(&mnt->mnt_list, &ns->list); |
| 2168 | ns->root = mnt; |
| 2169 | mnt->mnt_ns = ns; |
| 2170 | |
| 2171 | init_task.nsproxy->mnt_ns = ns; |
| 2172 | get_mnt_ns(ns); |
| 2173 | |
| 2174 | root.mnt = ns->root; |
| 2175 | root.dentry = ns->root->mnt_root; |
| 2176 | |
| 2177 | set_fs_pwd(current->fs, &root); |
| 2178 | set_fs_root(current->fs, &root); |
| 2179 | } |
| 2180 | |
| 2181 | void __init mnt_init(void) |
| 2182 | { |
| 2183 | unsigned u; |
| 2184 | int err; |
| 2185 | |
| 2186 | init_rwsem(&namespace_sem); |
| 2187 | |
| 2188 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
| 2189 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
| 2190 | |
| 2191 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
| 2192 | |
| 2193 | if (!mount_hashtable) |
| 2194 | panic("Failed to allocate mount hash table\n"); |
| 2195 | |
| 2196 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
| 2197 | |
| 2198 | for (u = 0; u < HASH_SIZE; u++) |
| 2199 | INIT_LIST_HEAD(&mount_hashtable[u]); |
| 2200 | |
| 2201 | err = sysfs_init(); |
| 2202 | if (err) |
| 2203 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
| 2204 | __func__, err); |
| 2205 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 2206 | if (!fs_kobj) |
| 2207 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
| 2208 | init_rootfs(); |
| 2209 | init_mount_tree(); |
| 2210 | } |
| 2211 | |
| 2212 | void __put_mnt_ns(struct mnt_namespace *ns) |
| 2213 | { |
| 2214 | struct vfsmount *root = ns->root; |
| 2215 | LIST_HEAD(umount_list); |
| 2216 | ns->root = NULL; |
| 2217 | spin_unlock(&vfsmount_lock); |
| 2218 | down_write(&namespace_sem); |
| 2219 | spin_lock(&vfsmount_lock); |
| 2220 | umount_tree(root, 0, &umount_list); |
| 2221 | spin_unlock(&vfsmount_lock); |
| 2222 | up_write(&namespace_sem); |
| 2223 | release_mounts(&umount_list); |
| 2224 | kfree(ns); |
| 2225 | } |