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vfs: tidy up fs/namei.c byte-repeat word constants
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / namei.c
CommitLineData
1da177e4
LT		 1/*
2 * linux/fs/namei.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * Some corrections by tytso.
9 */
10
11/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
12 * lookup logic.
13 */
14/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
15 */
16
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/slab.h>
20#include <linux/fs.h>
21#include <linux/namei.h>
1da177e4 22#include <linux/pagemap.h>
0eeca283 23#include <linux/fsnotify.h>
1da177e4
LT		 24#include <linux/personality.h>
25#include <linux/security.h>
6146f0d5 26#include <linux/ima.h>
1da177e4
LT		 27#include <linux/syscalls.h>
28#include <linux/mount.h>
29#include <linux/audit.h>
16f7e0fe 30#include <linux/capability.h>
834f2a4a 31#include <linux/file.h>
5590ff0d 32#include <linux/fcntl.h>
08ce5f16 33#include <linux/device_cgroup.h>
5ad4e53b 34#include <linux/fs_struct.h>
e77819e5 35#include <linux/posix_acl.h>
1da177e4
LT		 36#include <asm/uaccess.h>
37
e81e3f4d 38#include "internal.h"
c7105365 39#include "mount.h"
e81e3f4d 40
1da177e4
LT		 41/* [Feb-1997 T. Schoebel-Theuer]
42 * Fundamental changes in the pathname lookup mechanisms (namei)
43 * were necessary because of omirr. The reason is that omirr needs
44 * to know the _real_ pathname, not the user-supplied one, in case
45 * of symlinks (and also when transname replacements occur).
46 *
47 * The new code replaces the old recursive symlink resolution with
48 * an iterative one (in case of non-nested symlink chains). It does
49 * this with calls to <fs>_follow_link().
50 * As a side effect, dir_namei(), _namei() and follow_link() are now
51 * replaced with a single function lookup_dentry() that can handle all
52 * the special cases of the former code.
53 *
54 * With the new dcache, the pathname is stored at each inode, at least as
55 * long as the refcount of the inode is positive. As a side effect, the
56 * size of the dcache depends on the inode cache and thus is dynamic.
57 *
58 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
59 * resolution to correspond with current state of the code.
60 *
61 * Note that the symlink resolution is not *completely* iterative.
62 * There is still a significant amount of tail- and mid- recursion in
63 * the algorithm. Also, note that <fs>_readlink() is not used in
64 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
65 * may return different results than <fs>_follow_link(). Many virtual
66 * filesystems (including /proc) exhibit this behavior.
67 */
68
69/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
70 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
71 * and the name already exists in form of a symlink, try to create the new
72 * name indicated by the symlink. The old code always complained that the
73 * name already exists, due to not following the symlink even if its target
74 * is nonexistent. The new semantics affects also mknod() and link() when
25985edc 75 * the name is a symlink pointing to a non-existent name.
1da177e4
LT		 76 *
77 * I don't know which semantics is the right one, since I have no access
78 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
79 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
80 * "old" one. Personally, I think the new semantics is much more logical.
81 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
82 * file does succeed in both HP-UX and SunOs, but not in Solaris
83 * and in the old Linux semantics.
84 */
85
86/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
87 * semantics. See the comments in "open_namei" and "do_link" below.
88 *
89 * [10-Sep-98 Alan Modra] Another symlink change.
90 */
91
92/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
93 * inside the path - always follow.
94 * in the last component in creation/removal/renaming - never follow.
95 * if LOOKUP_FOLLOW passed - follow.
96 * if the pathname has trailing slashes - follow.
97 * otherwise - don't follow.
98 * (applied in that order).
99 *
100 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
101 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
102 * During the 2.4 we need to fix the userland stuff depending on it -
103 * hopefully we will be able to get rid of that wart in 2.5. So far only
104 * XEmacs seems to be relying on it...
105 */
106/*
107 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
a11f3a05 108 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
1da177e4
LT		 109 * any extra contention...
110 */
111
112/* In order to reduce some races, while at the same time doing additional
113 * checking and hopefully speeding things up, we copy filenames to the
114 * kernel data space before using them..
115 *
116 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
117 * PATH_MAX includes the nul terminator --RR.
118 */
858119e1 119static int do_getname(const char __user *filename, char *page)
1da177e4
LT		 120{
121 int retval;
122 unsigned long len = PATH_MAX;
123
124 if (!segment_eq(get_fs(), KERNEL_DS)) {
125 if ((unsigned long) filename >= TASK_SIZE)
126 return -EFAULT;
127 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
128 len = TASK_SIZE - (unsigned long) filename;
129 }
130
131 retval = strncpy_from_user(page, filename, len);
132 if (retval > 0) {
133 if (retval < len)
134 return 0;
135 return -ENAMETOOLONG;
136 } else if (!retval)
137 retval = -ENOENT;
138 return retval;
139}
140
1fa1e7f6 141static char *getname_flags(const char __user *filename, int flags, int *empty)
1da177e4 142{
4043cde8
EP		 143 char *result = __getname();
144 int retval;
145
146 if (!result)
147 return ERR_PTR(-ENOMEM);
148
149 retval = do_getname(filename, result);
150 if (retval < 0) {
151 if (retval == -ENOENT && empty)
152 *empty = 1;
153 if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
154 __putname(result);
155 return ERR_PTR(retval);
1da177e4
LT		 156 }
157 }
158 audit_getname(result);
159 return result;
160}
161
f52e0c11
AV		 162char *getname(const char __user * filename)
163{
1fa1e7f6 164 return getname_flags(filename, 0, 0);
f52e0c11
AV		 165}
166
1da177e4
LT		 167#ifdef CONFIG_AUDITSYSCALL
168void putname(const char *name)
169{
5ac3a9c2 170 if (unlikely(!audit_dummy_context()))
1da177e4
LT		 171 audit_putname(name);
172 else
173 __putname(name);
174}
175EXPORT_SYMBOL(putname);
176#endif
177
e77819e5
LT		 178static int check_acl(struct inode *inode, int mask)
179{
84635d68 180#ifdef CONFIG_FS_POSIX_ACL
e77819e5
LT		 181 struct posix_acl *acl;
182
e77819e5 183 if (mask & MAY_NOT_BLOCK) {
3567866b
AV		 184 acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
185 if (!acl)
e77819e5 186 return -EAGAIN;
3567866b
AV		 187 /* no ->get_acl() calls in RCU mode... */
188 if (acl == ACL_NOT_CACHED)
189 return -ECHILD;
206b1d09 190 return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
e77819e5
LT		 191 }
192
193 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
194
195 /*
4e34e719
CH		 196 * A filesystem can force a ACL callback by just never filling the
197 * ACL cache. But normally you'd fill the cache either at inode
198 * instantiation time, or on the first ->get_acl call.
e77819e5 199 *
4e34e719
CH		 200 * If the filesystem doesn't have a get_acl() function at all, we'll
201 * just create the negative cache entry.
e77819e5
LT		 202 */
203 if (acl == ACL_NOT_CACHED) {
4e34e719
CH		 204 if (inode->i_op->get_acl) {
205 acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
206 if (IS_ERR(acl))
207 return PTR_ERR(acl);
208 } else {
209 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
210 return -EAGAIN;
211 }
e77819e5
LT		 212 }
213
214 if (acl) {
215 int error = posix_acl_permission(inode, acl, mask);
216 posix_acl_release(acl);
217 return error;
218 }
84635d68 219#endif
e77819e5
LT		 220
221 return -EAGAIN;
222}
223
5909ccaa 224/*
948409c7 225 * This does the basic permission checking
1da177e4 226 */
7e40145e 227static int acl_permission_check(struct inode *inode, int mask)
1da177e4 228{
26cf46be 229 unsigned int mode = inode->i_mode;
1da177e4 230
e795b717
SH		 231 if (current_user_ns() != inode_userns(inode))
232 goto other_perms;
233
14067ff5 234 if (likely(current_fsuid() == inode->i_uid))
1da177e4
LT		 235 mode >>= 6;
236 else {
e77819e5 237 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
7e40145e 238 int error = check_acl(inode, mask);
b74c79e9
NP		 239 if (error != -EAGAIN)
240 return error;
1da177e4
LT		 241 }
242
243 if (in_group_p(inode->i_gid))
244 mode >>= 3;
245 }
246
e795b717 247other_perms:
1da177e4
LT		 248 /*
249 * If the DACs are ok we don't need any capability check.
250 */
9c2c7039 251 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
1da177e4 252 return 0;
5909ccaa
LT		 253 return -EACCES;
254}
255
256/**
b74c79e9 257 * generic_permission - check for access rights on a Posix-like filesystem
5909ccaa 258 * @inode: inode to check access rights for
8fd90c8d 259 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
5909ccaa
LT		 260 *
261 * Used to check for read/write/execute permissions on a file.
262 * We use "fsuid" for this, letting us set arbitrary permissions
263 * for filesystem access without changing the "normal" uids which
b74c79e9
NP		 264 * are used for other things.
265 *
266 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
267 * request cannot be satisfied (eg. requires blocking or too much complexity).
268 * It would then be called again in ref-walk mode.
5909ccaa 269 */
2830ba7f 270int generic_permission(struct inode *inode, int mask)
5909ccaa
LT		 271{
272 int ret;
273
274 /*
948409c7 275 * Do the basic permission checks.
5909ccaa 276 */
7e40145e 277 ret = acl_permission_check(inode, mask);
5909ccaa
LT		 278 if (ret != -EACCES)
279 return ret;
1da177e4 280
d594e7ec
AV		 281 if (S_ISDIR(inode->i_mode)) {
282 /* DACs are overridable for directories */
283 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
284 return 0;
285 if (!(mask & MAY_WRITE))
286 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
287 return 0;
288 return -EACCES;
289 }
1da177e4
LT		 290 /*
291 * Read/write DACs are always overridable.
d594e7ec
AV		 292 * Executable DACs are overridable when there is
293 * at least one exec bit set.
1da177e4 294 */
d594e7ec 295 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
e795b717 296 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
1da177e4
LT		 297 return 0;
298
299 /*
300 * Searching includes executable on directories, else just read.
301 */
7ea66001 302 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
d594e7ec 303 if (mask == MAY_READ)
e795b717 304 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
1da177e4
LT		 305 return 0;
306
307 return -EACCES;
308}
309
3ddcd056
LT		 310/*
311 * We _really_ want to just do "generic_permission()" without
312 * even looking at the inode->i_op values. So we keep a cache
313 * flag in inode->i_opflags, that says "this has not special
314 * permission function, use the fast case".
315 */
316static inline int do_inode_permission(struct inode *inode, int mask)
317{
318 if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
319 if (likely(inode->i_op->permission))
320 return inode->i_op->permission(inode, mask);
321
322 /* This gets set once for the inode lifetime */
323 spin_lock(&inode->i_lock);
324 inode->i_opflags |= IOP_FASTPERM;
325 spin_unlock(&inode->i_lock);
326 }
327 return generic_permission(inode, mask);
328}
329
cb23beb5
CH		 330/**
331 * inode_permission - check for access rights to a given inode
332 * @inode: inode to check permission on
8fd90c8d 333 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
cb23beb5
CH		 334 *
335 * Used to check for read/write/execute permissions on an inode.
336 * We use "fsuid" for this, letting us set arbitrary permissions
337 * for filesystem access without changing the "normal" uids which
338 * are used for other things.
948409c7
AG		 339 *
340 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
cb23beb5 341 */
f419a2e3 342int inode_permission(struct inode *inode, int mask)
1da177e4 343{
e6305c43 344 int retval;
1da177e4 345
3ddcd056 346 if (unlikely(mask & MAY_WRITE)) {
22590e41 347 umode_t mode = inode->i_mode;
1da177e4
LT		 348
349 /*
350 * Nobody gets write access to a read-only fs.
351 */
352 if (IS_RDONLY(inode) &&
353 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
354 return -EROFS;
355
356 /*
357 * Nobody gets write access to an immutable file.
358 */
359 if (IS_IMMUTABLE(inode))
360 return -EACCES;
361 }
362
3ddcd056 363 retval = do_inode_permission(inode, mask);
1da177e4
LT		 364 if (retval)
365 return retval;
366
08ce5f16
SH		 367 retval = devcgroup_inode_permission(inode, mask);
368 if (retval)
369 return retval;
370
d09ca739 371 return security_inode_permission(inode, mask);
1da177e4
LT		 372}
373
5dd784d0
JB		 374/**
375 * path_get - get a reference to a path
376 * @path: path to get the reference to
377 *
378 * Given a path increment the reference count to the dentry and the vfsmount.
379 */
380void path_get(struct path *path)
381{
382 mntget(path->mnt);
383 dget(path->dentry);
384}
385EXPORT_SYMBOL(path_get);
386
1d957f9b
JB		 387/**
388 * path_put - put a reference to a path
389 * @path: path to put the reference to
390 *
391 * Given a path decrement the reference count to the dentry and the vfsmount.
392 */
393void path_put(struct path *path)
1da177e4 394{
1d957f9b
JB		 395 dput(path->dentry);
396 mntput(path->mnt);
1da177e4 397}
1d957f9b 398EXPORT_SYMBOL(path_put);
1da177e4 399
19660af7 400/*
31e6b01f 401 * Path walking has 2 modes, rcu-walk and ref-walk (see
19660af7
AV		 402 * Documentation/filesystems/path-lookup.txt). In situations when we can't
403 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
404 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
405 * mode. Refcounts are grabbed at the last known good point before rcu-walk
406 * got stuck, so ref-walk may continue from there. If this is not successful
407 * (eg. a seqcount has changed), then failure is returned and it's up to caller
408 * to restart the path walk from the beginning in ref-walk mode.
31e6b01f 409 */
31e6b01f
NP		 410
411/**
19660af7
AV		 412 * unlazy_walk - try to switch to ref-walk mode.
413 * @nd: nameidata pathwalk data
414 * @dentry: child of nd->path.dentry or NULL
39191628 415 * Returns: 0 on success, -ECHILD on failure
31e6b01f 416 *
19660af7
AV		 417 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
418 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
419 * @nd or NULL. Must be called from rcu-walk context.
31e6b01f 420 */
19660af7 421static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
31e6b01f
NP		 422{
423 struct fs_struct *fs = current->fs;
424 struct dentry *parent = nd->path.dentry;
5b6ca027 425 int want_root = 0;
31e6b01f
NP		 426
427 BUG_ON(!(nd->flags & LOOKUP_RCU));
5b6ca027
AV		 428 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
429 want_root = 1;
31e6b01f
NP		 430 spin_lock(&fs->lock);
431 if (nd->root.mnt != fs->root.mnt ||
432 nd->root.dentry != fs->root.dentry)
433 goto err_root;
434 }
435 spin_lock(&parent->d_lock);
19660af7
AV		 436 if (!dentry) {
437 if (!__d_rcu_to_refcount(parent, nd->seq))
438 goto err_parent;
439 BUG_ON(nd->inode != parent->d_inode);
440 } else {
94c0d4ec
AV		 441 if (dentry->d_parent != parent)
442 goto err_parent;
19660af7
AV		 443 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
444 if (!__d_rcu_to_refcount(dentry, nd->seq))
445 goto err_child;
446 /*
447 * If the sequence check on the child dentry passed, then
448 * the child has not been removed from its parent. This
449 * means the parent dentry must be valid and able to take
450 * a reference at this point.
451 */
452 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
453 BUG_ON(!parent->d_count);
454 parent->d_count++;
455 spin_unlock(&dentry->d_lock);
456 }
31e6b01f 457 spin_unlock(&parent->d_lock);
5b6ca027 458 if (want_root) {
31e6b01f
NP		 459 path_get(&nd->root);
460 spin_unlock(&fs->lock);
461 }
462 mntget(nd->path.mnt);
463
464 rcu_read_unlock();
465 br_read_unlock(vfsmount_lock);
466 nd->flags &= ~LOOKUP_RCU;
467 return 0;
19660af7
AV		 468
469err_child:
31e6b01f 470 spin_unlock(&dentry->d_lock);
19660af7 471err_parent:
31e6b01f
NP		 472 spin_unlock(&parent->d_lock);
473err_root:
5b6ca027 474 if (want_root)
31e6b01f
NP		 475 spin_unlock(&fs->lock);
476 return -ECHILD;
477}
478
834f2a4a
TM		 479/**
480 * release_open_intent - free up open intent resources
481 * @nd: pointer to nameidata
482 */
483void release_open_intent(struct nameidata *nd)
484{
2dab5974
LT		 485 struct file *file = nd->intent.open.file;
486
487 if (file && !IS_ERR(file)) {
488 if (file->f_path.dentry == NULL)
489 put_filp(file);
490 else
491 fput(file);
492 }
834f2a4a
TM		 493}
494
f60aef7e 495static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
34286d66 496{
f60aef7e 497 return dentry->d_op->d_revalidate(dentry, nd);
34286d66
NP		 498}
499
9f1fafee
AV		 500/**
501 * complete_walk - successful completion of path walk
502 * @nd: pointer nameidata
39159de2 503 *
9f1fafee
AV		 504 * If we had been in RCU mode, drop out of it and legitimize nd->path.
505 * Revalidate the final result, unless we'd already done that during
506 * the path walk or the filesystem doesn't ask for it. Return 0 on
507 * success, -error on failure. In case of failure caller does not
508 * need to drop nd->path.
39159de2 509 */
9f1fafee 510static int complete_walk(struct nameidata *nd)
39159de2 511{
16c2cd71 512 struct dentry *dentry = nd->path.dentry;
39159de2 513 int status;
39159de2 514
9f1fafee
AV		 515 if (nd->flags & LOOKUP_RCU) {
516 nd->flags &= ~LOOKUP_RCU;
517 if (!(nd->flags & LOOKUP_ROOT))
518 nd->root.mnt = NULL;
519 spin_lock(&dentry->d_lock);
520 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
521 spin_unlock(&dentry->d_lock);
522 rcu_read_unlock();
523 br_read_unlock(vfsmount_lock);
524 return -ECHILD;
525 }
526 BUG_ON(nd->inode != dentry->d_inode);
527 spin_unlock(&dentry->d_lock);
528 mntget(nd->path.mnt);
529 rcu_read_unlock();
530 br_read_unlock(vfsmount_lock);
531 }
532
16c2cd71
AV		 533 if (likely(!(nd->flags & LOOKUP_JUMPED)))
534 return 0;
535
536 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
39159de2
JL		 537 return 0;
538
16c2cd71
AV		 539 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
540 return 0;
541
542 /* Note: we do not d_invalidate() */
34286d66 543 status = d_revalidate(dentry, nd);
39159de2
JL		 544 if (status > 0)
545 return 0;
546
16c2cd71 547 if (!status)
39159de2 548 status = -ESTALE;
16c2cd71 549
9f1fafee 550 path_put(&nd->path);
39159de2
JL		 551 return status;
552}
553
2a737871
AV		 554static __always_inline void set_root(struct nameidata *nd)
555{
f7ad3c6b
MS		 556 if (!nd->root.mnt)
557 get_fs_root(current->fs, &nd->root);
2a737871
AV		 558}
559
6de88d72
AV		 560static int link_path_walk(const char *, struct nameidata *);
561
31e6b01f
NP		 562static __always_inline void set_root_rcu(struct nameidata *nd)
563{
564 if (!nd->root.mnt) {
565 struct fs_struct *fs = current->fs;
c28cc364
NP		 566 unsigned seq;
567
568 do {
569 seq = read_seqcount_begin(&fs->seq);
570 nd->root = fs->root;
c1530019 571 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
c28cc364 572 } while (read_seqcount_retry(&fs->seq, seq));
31e6b01f
NP		 573 }
574}
575
f1662356 576static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
1da177e4 577{
31e6b01f
NP		 578 int ret;
579
1da177e4
LT		 580 if (IS_ERR(link))
581 goto fail;
582
583 if (*link == '/') {
2a737871 584 set_root(nd);
1d957f9b 585 path_put(&nd->path);
2a737871
AV		 586 nd->path = nd->root;
587 path_get(&nd->root);
16c2cd71 588 nd->flags |= LOOKUP_JUMPED;
1da177e4 589 }
31e6b01f 590 nd->inode = nd->path.dentry->d_inode;
b4091d5f 591
31e6b01f
NP		 592 ret = link_path_walk(link, nd);
593 return ret;
1da177e4 594fail:
1d957f9b 595 path_put(&nd->path);
1da177e4
LT		 596 return PTR_ERR(link);
597}
598
1d957f9b 599static void path_put_conditional(struct path *path, struct nameidata *nd)
051d3812
IK		 600{
601 dput(path->dentry);
4ac91378 602 if (path->mnt != nd->path.mnt)
051d3812
IK		 603 mntput(path->mnt);
604}
605
7b9337aa
NP		 606static inline void path_to_nameidata(const struct path *path,
607 struct nameidata *nd)
051d3812 608{
31e6b01f
NP		 609 if (!(nd->flags & LOOKUP_RCU)) {
610 dput(nd->path.dentry);
611 if (nd->path.mnt != path->mnt)
612 mntput(nd->path.mnt);
9a229683 613 }
31e6b01f 614 nd->path.mnt = path->mnt;
4ac91378 615 nd->path.dentry = path->dentry;
051d3812
IK		 616}
617
574197e0
AV		 618static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
619{
620 struct inode *inode = link->dentry->d_inode;
621 if (!IS_ERR(cookie) && inode->i_op->put_link)
622 inode->i_op->put_link(link->dentry, nd, cookie);
623 path_put(link);
624}
625
def4af30 626static __always_inline int
574197e0 627follow_link(struct path *link, struct nameidata *nd, void **p)
1da177e4
LT		 628{
629 int error;
7b9337aa 630 struct dentry *dentry = link->dentry;
1da177e4 631
844a3917
AV		 632 BUG_ON(nd->flags & LOOKUP_RCU);
633
0e794589
AV		 634 if (link->mnt == nd->path.mnt)
635 mntget(link->mnt);
636
574197e0
AV		 637 if (unlikely(current->total_link_count >= 40)) {
638 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
574197e0
AV		 639 path_put(&nd->path);
640 return -ELOOP;
641 }
642 cond_resched();
643 current->total_link_count++;
644
68ac1234 645 touch_atime(link);
1da177e4 646 nd_set_link(nd, NULL);
cd4e91d3 647
36f3b4f6
AV		 648 error = security_inode_follow_link(link->dentry, nd);
649 if (error) {
650 *p = ERR_PTR(error); /* no ->put_link(), please */
651 path_put(&nd->path);
652 return error;
653 }
654
86acdca1 655 nd->last_type = LAST_BIND;
def4af30
AV		 656 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
657 error = PTR_ERR(*p);
658 if (!IS_ERR(*p)) {
1da177e4 659 char *s = nd_get_link(nd);
cc314eef 660 error = 0;
1da177e4
LT		 661 if (s)
662 error = __vfs_follow_link(nd, s);
bcda7652 663 else if (nd->last_type == LAST_BIND) {
16c2cd71 664 nd->flags |= LOOKUP_JUMPED;
b21041d0
AV		 665 nd->inode = nd->path.dentry->d_inode;
666 if (nd->inode->i_op->follow_link) {
bcda7652
AV		 667 /* stepped on a _really_ weird one */
668 path_put(&nd->path);
669 error = -ELOOP;
670 }
671 }
1da177e4 672 }
1da177e4
LT		 673 return error;
674}
675
31e6b01f
NP		 676static int follow_up_rcu(struct path *path)
677{
0714a533
AV		 678 struct mount *mnt = real_mount(path->mnt);
679 struct mount *parent;
31e6b01f
NP		 680 struct dentry *mountpoint;
681
0714a533
AV		 682 parent = mnt->mnt_parent;
683 if (&parent->mnt == path->mnt)
31e6b01f 684 return 0;
a73324da 685 mountpoint = mnt->mnt_mountpoint;
31e6b01f 686 path->dentry = mountpoint;
0714a533 687 path->mnt = &parent->mnt;
31e6b01f
NP		 688 return 1;
689}
690
bab77ebf 691int follow_up(struct path *path)
1da177e4 692{
0714a533
AV		 693 struct mount *mnt = real_mount(path->mnt);
694 struct mount *parent;
1da177e4 695 struct dentry *mountpoint;
99b7db7b
NP		 696
697 br_read_lock(vfsmount_lock);
0714a533
AV		 698 parent = mnt->mnt_parent;
699 if (&parent->mnt == path->mnt) {
99b7db7b 700 br_read_unlock(vfsmount_lock);
1da177e4
LT		 701 return 0;
702 }
0714a533 703 mntget(&parent->mnt);
a73324da 704 mountpoint = dget(mnt->mnt_mountpoint);
99b7db7b 705 br_read_unlock(vfsmount_lock);
bab77ebf
AV		 706 dput(path->dentry);
707 path->dentry = mountpoint;
708 mntput(path->mnt);
0714a533 709 path->mnt = &parent->mnt;
1da177e4
LT		 710 return 1;
711}
712
b5c84bf6 713/*
9875cf80
DH		 714 * Perform an automount
715 * - return -EISDIR to tell follow_managed() to stop and return the path we
716 * were called with.
1da177e4 717 */
9875cf80
DH		 718static int follow_automount(struct path *path, unsigned flags,
719 bool *need_mntput)
31e6b01f 720{
9875cf80 721 struct vfsmount *mnt;
ea5b778a 722 int err;
9875cf80
DH		 723
724 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
725 return -EREMOTE;
726
0ec26fd0
MS		 727 /* We don't want to mount if someone's just doing a stat -
728 * unless they're stat'ing a directory and appended a '/' to
729 * the name.
730 *
731 * We do, however, want to mount if someone wants to open or
732 * create a file of any type under the mountpoint, wants to
733 * traverse through the mountpoint or wants to open the
734 * mounted directory. Also, autofs may mark negative dentries
735 * as being automount points. These will need the attentions
736 * of the daemon to instantiate them before they can be used.
9875cf80 737 */
0ec26fd0 738 if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
d94c177b 739 LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
0ec26fd0
MS		 740 path->dentry->d_inode)
741 return -EISDIR;
742
9875cf80
DH		 743 current->total_link_count++;
744 if (current->total_link_count >= 40)
745 return -ELOOP;
746
747 mnt = path->dentry->d_op->d_automount(path);
748 if (IS_ERR(mnt)) {
749 /*
750 * The filesystem is allowed to return -EISDIR here to indicate
751 * it doesn't want to automount. For instance, autofs would do
752 * this so that its userspace daemon can mount on this dentry.
753 *
754 * However, we can only permit this if it's a terminal point in
755 * the path being looked up; if it wasn't then the remainder of
756 * the path is inaccessible and we should say so.
757 */
49084c3b 758 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
9875cf80
DH		 759 return -EREMOTE;
760 return PTR_ERR(mnt);
31e6b01f 761 }
ea5b778a 762
9875cf80
DH		 763 if (!mnt) /* mount collision */
764 return 0;
31e6b01f 765
8aef1884
AV		 766 if (!*need_mntput) {
767 /* lock_mount() may release path->mnt on error */
768 mntget(path->mnt);
769 *need_mntput = true;
770 }
19a167af 771 err = finish_automount(mnt, path);
9875cf80 772
ea5b778a
DH		 773 switch (err) {
774 case -EBUSY:
775 /* Someone else made a mount here whilst we were busy */
19a167af 776 return 0;
ea5b778a 777 case 0:
8aef1884 778 path_put(path);
ea5b778a
DH		 779 path->mnt = mnt;
780 path->dentry = dget(mnt->mnt_root);
ea5b778a 781 return 0;
19a167af
AV		 782 default:
783 return err;
ea5b778a 784 }
19a167af 785
463ffb2e
AV		 786}
787
9875cf80
DH		 788/*
789 * Handle a dentry that is managed in some way.
cc53ce53 790 * - Flagged for transit management (autofs)
9875cf80
DH		 791 * - Flagged as mountpoint
792 * - Flagged as automount point
793 *
794 * This may only be called in refwalk mode.
795 *
796 * Serialization is taken care of in namespace.c
797 */
798static int follow_managed(struct path *path, unsigned flags)
1da177e4 799{
8aef1884 800 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
9875cf80
DH		 801 unsigned managed;
802 bool need_mntput = false;
8aef1884 803 int ret = 0;
9875cf80
DH		 804
805 /* Given that we're not holding a lock here, we retain the value in a
806 * local variable for each dentry as we look at it so that we don't see
807 * the components of that value change under us */
808 while (managed = ACCESS_ONCE(path->dentry->d_flags),
809 managed &= DCACHE_MANAGED_DENTRY,
810 unlikely(managed != 0)) {
cc53ce53
DH		 811 /* Allow the filesystem to manage the transit without i_mutex
812 * being held. */
813 if (managed & DCACHE_MANAGE_TRANSIT) {
814 BUG_ON(!path->dentry->d_op);
815 BUG_ON(!path->dentry->d_op->d_manage);
1aed3e42 816 ret = path->dentry->d_op->d_manage(path->dentry, false);
cc53ce53 817 if (ret < 0)
8aef1884 818 break;
cc53ce53
DH		 819 }
820
9875cf80
DH		 821 /* Transit to a mounted filesystem. */
822 if (managed & DCACHE_MOUNTED) {
823 struct vfsmount *mounted = lookup_mnt(path);
824 if (mounted) {
825 dput(path->dentry);
826 if (need_mntput)
827 mntput(path->mnt);
828 path->mnt = mounted;
829 path->dentry = dget(mounted->mnt_root);
830 need_mntput = true;
831 continue;
832 }
833
834 /* Something is mounted on this dentry in another
835 * namespace and/or whatever was mounted there in this
836 * namespace got unmounted before we managed to get the
837 * vfsmount_lock */
838 }
839
840 /* Handle an automount point */
841 if (managed & DCACHE_NEED_AUTOMOUNT) {
842 ret = follow_automount(path, flags, &need_mntput);
843 if (ret < 0)
8aef1884 844 break;
9875cf80
DH		 845 continue;
846 }
847
848 /* We didn't change the current path point */
849 break;
1da177e4 850 }
8aef1884
AV		 851
852 if (need_mntput && path->mnt == mnt)
853 mntput(path->mnt);
854 if (ret == -EISDIR)
855 ret = 0;
a3fbbde7 856 return ret < 0 ? ret : need_mntput;
1da177e4
LT		 857}
858
cc53ce53 859int follow_down_one(struct path *path)
1da177e4
LT		 860{
861 struct vfsmount *mounted;
862
1c755af4 863 mounted = lookup_mnt(path);
1da177e4 864 if (mounted) {
9393bd07
AV		 865 dput(path->dentry);
866 mntput(path->mnt);
867 path->mnt = mounted;
868 path->dentry = dget(mounted->mnt_root);
1da177e4
LT		 869 return 1;
870 }
871 return 0;
872}
873
62a7375e
IK		 874static inline bool managed_dentry_might_block(struct dentry *dentry)
875{
876 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
877 dentry->d_op->d_manage(dentry, true) < 0);
878}
879
9875cf80 880/*
287548e4
AV		 881 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
882 * we meet a managed dentry that would need blocking.
9875cf80
DH		 883 */
884static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
287548e4 885 struct inode **inode)
9875cf80 886{
62a7375e 887 for (;;) {
c7105365 888 struct mount *mounted;
62a7375e
IK		 889 /*
890 * Don't forget we might have a non-mountpoint managed dentry
891 * that wants to block transit.
892 */
287548e4 893 if (unlikely(managed_dentry_might_block(path->dentry)))
ab90911f 894 return false;
62a7375e
IK		 895
896 if (!d_mountpoint(path->dentry))
897 break;
898
9875cf80
DH		 899 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
900 if (!mounted)
901 break;
c7105365
AV		 902 path->mnt = &mounted->mnt;
903 path->dentry = mounted->mnt.mnt_root;
a3fbbde7 904 nd->flags |= LOOKUP_JUMPED;
9875cf80 905 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
59430262
LT		 906 /*
907 * Update the inode too. We don't need to re-check the
908 * dentry sequence number here after this d_inode read,
909 * because a mount-point is always pinned.
910 */
911 *inode = path->dentry->d_inode;
9875cf80 912 }
9875cf80
DH		 913 return true;
914}
915
dea39376 916static void follow_mount_rcu(struct nameidata *nd)
287548e4 917{
dea39376 918 while (d_mountpoint(nd->path.dentry)) {
c7105365 919 struct mount *mounted;
dea39376 920 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
287548e4
AV		 921 if (!mounted)
922 break;
c7105365
AV		 923 nd->path.mnt = &mounted->mnt;
924 nd->path.dentry = mounted->mnt.mnt_root;
dea39376 925 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
287548e4
AV		 926 }
927}
928
31e6b01f
NP		 929static int follow_dotdot_rcu(struct nameidata *nd)
930{
31e6b01f
NP		 931 set_root_rcu(nd);
932
9875cf80 933 while (1) {
31e6b01f
NP		 934 if (nd->path.dentry == nd->root.dentry &&
935 nd->path.mnt == nd->root.mnt) {
936 break;
937 }
938 if (nd->path.dentry != nd->path.mnt->mnt_root) {
939 struct dentry *old = nd->path.dentry;
940 struct dentry *parent = old->d_parent;
941 unsigned seq;
942
943 seq = read_seqcount_begin(&parent->d_seq);
944 if (read_seqcount_retry(&old->d_seq, nd->seq))
ef7562d5 945 goto failed;
31e6b01f
NP		 946 nd->path.dentry = parent;
947 nd->seq = seq;
948 break;
949 }
950 if (!follow_up_rcu(&nd->path))
951 break;
952 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
31e6b01f 953 }
dea39376
AV		 954 follow_mount_rcu(nd);
955 nd->inode = nd->path.dentry->d_inode;
31e6b01f 956 return 0;
ef7562d5
AV		 957
958failed:
959 nd->flags &= ~LOOKUP_RCU;
5b6ca027
AV		 960 if (!(nd->flags & LOOKUP_ROOT))
961 nd->root.mnt = NULL;
ef7562d5
AV		 962 rcu_read_unlock();
963 br_read_unlock(vfsmount_lock);
964 return -ECHILD;
31e6b01f
NP		 965}
966
cc53ce53
DH		 967/*
968 * Follow down to the covering mount currently visible to userspace. At each
969 * point, the filesystem owning that dentry may be queried as to whether the
970 * caller is permitted to proceed or not.
cc53ce53 971 */
7cc90cc3 972int follow_down(struct path *path)
cc53ce53
DH		 973{
974 unsigned managed;
975 int ret;
976
977 while (managed = ACCESS_ONCE(path->dentry->d_flags),
978 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
979 /* Allow the filesystem to manage the transit without i_mutex
980 * being held.
981 *
982 * We indicate to the filesystem if someone is trying to mount
983 * something here. This gives autofs the chance to deny anyone
984 * other than its daemon the right to mount on its
985 * superstructure.
986 *
987 * The filesystem may sleep at this point.
988 */
989 if (managed & DCACHE_MANAGE_TRANSIT) {
990 BUG_ON(!path->dentry->d_op);
991 BUG_ON(!path->dentry->d_op->d_manage);
ab90911f 992 ret = path->dentry->d_op->d_manage(
1aed3e42 993 path->dentry, false);
cc53ce53
DH		 994 if (ret < 0)
995 return ret == -EISDIR ? 0 : ret;
996 }
997
998 /* Transit to a mounted filesystem. */
999 if (managed & DCACHE_MOUNTED) {
1000 struct vfsmount *mounted = lookup_mnt(path);
1001 if (!mounted)
1002 break;
1003 dput(path->dentry);
1004 mntput(path->mnt);
1005 path->mnt = mounted;
1006 path->dentry = dget(mounted->mnt_root);
1007 continue;
1008 }
1009
1010 /* Don't handle automount points here */
1011 break;
1012 }
1013 return 0;
1014}
1015
9875cf80
DH		 1016/*
1017 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1018 */
1019static void follow_mount(struct path *path)
1020{
1021 while (d_mountpoint(path->dentry)) {
1022 struct vfsmount *mounted = lookup_mnt(path);
1023 if (!mounted)
1024 break;
1025 dput(path->dentry);
1026 mntput(path->mnt);
1027 path->mnt = mounted;
1028 path->dentry = dget(mounted->mnt_root);
1029 }
1030}
1031
31e6b01f 1032static void follow_dotdot(struct nameidata *nd)
1da177e4 1033{
2a737871 1034 set_root(nd);
e518ddb7 1035
1da177e4 1036 while(1) {
4ac91378 1037 struct dentry *old = nd->path.dentry;
1da177e4 1038
2a737871
AV		 1039 if (nd->path.dentry == nd->root.dentry &&
1040 nd->path.mnt == nd->root.mnt) {
1da177e4
LT		 1041 break;
1042 }
4ac91378 1043 if (nd->path.dentry != nd->path.mnt->mnt_root) {
3088dd70
AV		 1044 /* rare case of legitimate dget_parent()... */
1045 nd->path.dentry = dget_parent(nd->path.dentry);
1da177e4
LT		 1046 dput(old);
1047 break;
1048 }
3088dd70 1049 if (!follow_up(&nd->path))
1da177e4 1050 break;
1da177e4 1051 }
79ed0226 1052 follow_mount(&nd->path);
31e6b01f 1053 nd->inode = nd->path.dentry->d_inode;
1da177e4
LT		 1054}
1055
baa03890
NP		 1056/*
1057 * Allocate a dentry with name and parent, and perform a parent
1058 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
1059 * on error. parent->d_inode->i_mutex must be held. d_lookup must
1060 * have verified that no child exists while under i_mutex.
1061 */
1062static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1063 struct qstr *name, struct nameidata *nd)
1064{
1065 struct inode *inode = parent->d_inode;
1066 struct dentry *dentry;
1067 struct dentry *old;
1068
1069 /* Don't create child dentry for a dead directory. */
1070 if (unlikely(IS_DEADDIR(inode)))
1071 return ERR_PTR(-ENOENT);
1072
1073 dentry = d_alloc(parent, name);
1074 if (unlikely(!dentry))
1075 return ERR_PTR(-ENOMEM);
1076
1077 old = inode->i_op->lookup(inode, dentry, nd);
1078 if (unlikely(old)) {
1079 dput(dentry);
1080 dentry = old;
1081 }
1082 return dentry;
1083}
1084
44396f4b
JB		 1085/*
1086 * We already have a dentry, but require a lookup to be performed on the parent
1087 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1088 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1089 * child exists while under i_mutex.
1090 */
1091static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1092 struct nameidata *nd)
1093{
1094 struct inode *inode = parent->d_inode;
1095 struct dentry *old;
1096
1097 /* Don't create child dentry for a dead directory. */
e188dc02
MS		 1098 if (unlikely(IS_DEADDIR(inode))) {
1099 dput(dentry);
44396f4b 1100 return ERR_PTR(-ENOENT);
e188dc02 1101 }
44396f4b
JB		 1102
1103 old = inode->i_op->lookup(inode, dentry, nd);
1104 if (unlikely(old)) {
1105 dput(dentry);
1106 dentry = old;
1107 }
1108 return dentry;
1109}
1110
1da177e4
LT		 1111/*
1112 * It's more convoluted than I'd like it to be, but... it's still fairly
1113 * small and for now I'd prefer to have fast path as straight as possible.
1114 * It _is_ time-critical.
1115 */
1116static int do_lookup(struct nameidata *nd, struct qstr *name,
31e6b01f 1117 struct path *path, struct inode **inode)
1da177e4 1118{
4ac91378 1119 struct vfsmount *mnt = nd->path.mnt;
31e6b01f 1120 struct dentry *dentry, *parent = nd->path.dentry;
5a18fff2
AV		 1121 int need_reval = 1;
1122 int status = 1;
9875cf80
DH		 1123 int err;
1124
b04f784e
NP		 1125 /*
1126 * Rename seqlock is not required here because in the off chance
1127 * of a false negative due to a concurrent rename, we're going to
1128 * do the non-racy lookup, below.
1129 */
31e6b01f
NP		 1130 if (nd->flags & LOOKUP_RCU) {
1131 unsigned seq;
31e6b01f
NP		 1132 *inode = nd->inode;
1133 dentry = __d_lookup_rcu(parent, name, &seq, inode);
5a18fff2
AV		 1134 if (!dentry)
1135 goto unlazy;
1136
31e6b01f
NP		 1137 /* Memory barrier in read_seqcount_begin of child is enough */
1138 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1139 return -ECHILD;
31e6b01f 1140 nd->seq = seq;
5a18fff2 1141
24643087 1142 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
5a18fff2
AV		 1143 status = d_revalidate(dentry, nd);
1144 if (unlikely(status <= 0)) {
1145 if (status != -ECHILD)
1146 need_reval = 0;
1147 goto unlazy;
1148 }
24643087 1149 }
44396f4b
JB		 1150 if (unlikely(d_need_lookup(dentry)))
1151 goto unlazy;
31e6b01f
NP		 1152 path->mnt = mnt;
1153 path->dentry = dentry;
d6e9bd25
AV		 1154 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1155 goto unlazy;
1156 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1157 goto unlazy;
1158 return 0;
5a18fff2 1159unlazy:
19660af7
AV		 1160 if (unlazy_walk(nd, dentry))
1161 return -ECHILD;
5a18fff2
AV		 1162 } else {
1163 dentry = __d_lookup(parent, name);
9875cf80 1164 }
5a18fff2 1165
44396f4b
JB		 1166 if (dentry && unlikely(d_need_lookup(dentry))) {
1167 dput(dentry);
1168 dentry = NULL;
1169 }
5a18fff2
AV		 1170retry:
1171 if (unlikely(!dentry)) {
1172 struct inode *dir = parent->d_inode;
1173 BUG_ON(nd->inode != dir);
1174
1175 mutex_lock(&dir->i_mutex);
1176 dentry = d_lookup(parent, name);
1177 if (likely(!dentry)) {
1178 dentry = d_alloc_and_lookup(parent, name, nd);
1179 if (IS_ERR(dentry)) {
1180 mutex_unlock(&dir->i_mutex);
1181 return PTR_ERR(dentry);
1182 }
1183 /* known good */
1184 need_reval = 0;
1185 status = 1;
44396f4b
JB		 1186 } else if (unlikely(d_need_lookup(dentry))) {
1187 dentry = d_inode_lookup(parent, dentry, nd);
1188 if (IS_ERR(dentry)) {
1189 mutex_unlock(&dir->i_mutex);
1190 return PTR_ERR(dentry);
1191 }
1192 /* known good */
1193 need_reval = 0;
1194 status = 1;
5a18fff2
AV		 1195 }
1196 mutex_unlock(&dir->i_mutex);
1197 }
1198 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1199 status = d_revalidate(dentry, nd);
1200 if (unlikely(status <= 0)) {
1201 if (status < 0) {
1202 dput(dentry);
1203 return status;
1204 }
1205 if (!d_invalidate(dentry)) {
1206 dput(dentry);
1207 dentry = NULL;
1208 need_reval = 1;
1209 goto retry;
1210 }
24643087 1211 }
5a18fff2 1212
9875cf80
DH		 1213 path->mnt = mnt;
1214 path->dentry = dentry;
1215 err = follow_managed(path, nd->flags);
89312214
IK		 1216 if (unlikely(err < 0)) {
1217 path_put_conditional(path, nd);
9875cf80 1218 return err;
89312214 1219 }
a3fbbde7
AV		 1220 if (err)
1221 nd->flags |= LOOKUP_JUMPED;
9875cf80 1222 *inode = path->dentry->d_inode;
1da177e4 1223 return 0;
1da177e4
LT		 1224}
1225
52094c8a
AV		 1226static inline int may_lookup(struct nameidata *nd)
1227{
1228 if (nd->flags & LOOKUP_RCU) {
4ad5abb3 1229 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
52094c8a
AV		 1230 if (err != -ECHILD)
1231 return err;
19660af7 1232 if (unlazy_walk(nd, NULL))
52094c8a
AV		 1233 return -ECHILD;
1234 }
4ad5abb3 1235 return inode_permission(nd->inode, MAY_EXEC);
52094c8a
AV		 1236}
1237
9856fa1b
AV		 1238static inline int handle_dots(struct nameidata *nd, int type)
1239{
1240 if (type == LAST_DOTDOT) {
1241 if (nd->flags & LOOKUP_RCU) {
1242 if (follow_dotdot_rcu(nd))
1243 return -ECHILD;
1244 } else
1245 follow_dotdot(nd);
1246 }
1247 return 0;
1248}
1249
951361f9
AV		 1250static void terminate_walk(struct nameidata *nd)
1251{
1252 if (!(nd->flags & LOOKUP_RCU)) {
1253 path_put(&nd->path);
1254 } else {
1255 nd->flags &= ~LOOKUP_RCU;
5b6ca027
AV		 1256 if (!(nd->flags & LOOKUP_ROOT))
1257 nd->root.mnt = NULL;
951361f9
AV		 1258 rcu_read_unlock();
1259 br_read_unlock(vfsmount_lock);
1260 }
1261}
1262
3ddcd056
LT		 1263/*
1264 * Do we need to follow links? We _really_ want to be able
1265 * to do this check without having to look at inode->i_op,
1266 * so we keep a cache of "no, this doesn't need follow_link"
1267 * for the common case.
1268 */
7813b94a 1269static inline int should_follow_link(struct inode *inode, int follow)
3ddcd056
LT		 1270{
1271 if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
1272 if (likely(inode->i_op->follow_link))
1273 return follow;
1274
1275 /* This gets set once for the inode lifetime */
1276 spin_lock(&inode->i_lock);
1277 inode->i_opflags |= IOP_NOFOLLOW;
1278 spin_unlock(&inode->i_lock);
1279 }
1280 return 0;
1281}
1282
ce57dfc1
AV		 1283static inline int walk_component(struct nameidata *nd, struct path *path,
1284 struct qstr *name, int type, int follow)
1285{
1286 struct inode *inode;
1287 int err;
1288 /*
1289 * "." and ".." are special - ".." especially so because it has
1290 * to be able to know about the current root directory and
1291 * parent relationships.
1292 */
1293 if (unlikely(type != LAST_NORM))
1294 return handle_dots(nd, type);
1295 err = do_lookup(nd, name, path, &inode);
1296 if (unlikely(err)) {
1297 terminate_walk(nd);
1298 return err;
1299 }
1300 if (!inode) {
1301 path_to_nameidata(path, nd);
1302 terminate_walk(nd);
1303 return -ENOENT;
1304 }
7813b94a 1305 if (should_follow_link(inode, follow)) {
19660af7
AV		 1306 if (nd->flags & LOOKUP_RCU) {
1307 if (unlikely(unlazy_walk(nd, path->dentry))) {
1308 terminate_walk(nd);
1309 return -ECHILD;
1310 }
1311 }
ce57dfc1
AV		 1312 BUG_ON(inode != path->dentry->d_inode);
1313 return 1;
1314 }
1315 path_to_nameidata(path, nd);
1316 nd->inode = inode;
1317 return 0;
1318}
1319
b356379a
AV		 1320/*
1321 * This limits recursive symlink follows to 8, while
1322 * limiting consecutive symlinks to 40.
1323 *
1324 * Without that kind of total limit, nasty chains of consecutive
1325 * symlinks can cause almost arbitrarily long lookups.
1326 */
1327static inline int nested_symlink(struct path *path, struct nameidata *nd)
1328{
1329 int res;
1330
b356379a
AV		 1331 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1332 path_put_conditional(path, nd);
1333 path_put(&nd->path);
1334 return -ELOOP;
1335 }
1a4022f8 1336 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
b356379a
AV		 1337
1338 nd->depth++;
1339 current->link_count++;
1340
1341 do {
1342 struct path link = *path;
1343 void *cookie;
574197e0
AV		 1344
1345 res = follow_link(&link, nd, &cookie);
b356379a
AV		 1346 if (!res)
1347 res = walk_component(nd, path, &nd->last,
1348 nd->last_type, LOOKUP_FOLLOW);
574197e0 1349 put_link(nd, &link, cookie);
b356379a
AV		 1350 } while (res > 0);
1351
1352 current->link_count--;
1353 nd->depth--;
1354 return res;
1355}
1356
3ddcd056
LT		 1357/*
1358 * We really don't want to look at inode->i_op->lookup
1359 * when we don't have to. So we keep a cache bit in
1360 * the inode ->i_opflags field that says "yes, we can
1361 * do lookup on this inode".
1362 */
1363static inline int can_lookup(struct inode *inode)
1364{
1365 if (likely(inode->i_opflags & IOP_LOOKUP))
1366 return 1;
1367 if (likely(!inode->i_op->lookup))
1368 return 0;
1369
1370 /* We do this once for the lifetime of the inode */
1371 spin_lock(&inode->i_lock);
1372 inode->i_opflags |= IOP_LOOKUP;
1373 spin_unlock(&inode->i_lock);
1374 return 1;
1375}
1376
bfcfaa77
LT		 1377/*
1378 * We can do the critical dentry name comparison and hashing
1379 * operations one word at a time, but we are limited to:
1380 *
1381 * - Architectures with fast unaligned word accesses. We could
1382 * do a "get_unaligned()" if this helps and is sufficiently
1383 * fast.
1384 *
1385 * - Little-endian machines (so that we can generate the mask
1386 * of low bytes efficiently). Again, we *could* do a byte
1387 * swapping load on big-endian architectures if that is not
1388 * expensive enough to make the optimization worthless.
1389 *
1390 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1391 * do not trap on the (extremely unlikely) case of a page
1392 * crossing operation.
1393 *
1394 * - Furthermore, we need an efficient 64-bit compile for the
1395 * 64-bit case in order to generate the "number of bytes in
1396 * the final mask". Again, that could be replaced with a
1397 * efficient population count instruction or similar.
1398 */
1399#ifdef CONFIG_DCACHE_WORD_ACCESS
1400
1401#ifdef CONFIG_64BIT
1402
1403/*
1404 * Jan Achrenius on G+: microoptimized version of
1405 * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
1406 * that works for the bytemasks without having to
1407 * mask them first.
1408 */
1409static inline long count_masked_bytes(unsigned long mask)
1410{
1411 return mask*0x0001020304050608 >> 56;
1412}
1413
1414static inline unsigned int fold_hash(unsigned long hash)
1415{
1416 hash += hash >> (8*sizeof(int));
1417 return hash;
1418}
1419
1420#else /* 32-bit case */
1421
1422/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
1423static inline long count_masked_bytes(long mask)
1424{
1425 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
1426 long a = (0x0ff0001+mask) >> 23;
1427 /* Fix the 1 for 00 case */
1428 return a & mask;
1429}
1430
1431#define fold_hash(x) (x)
1432
1433#endif
1434
1435unsigned int full_name_hash(const unsigned char *name, unsigned int len)
1436{
1437 unsigned long a, mask;
1438 unsigned long hash = 0;
1439
1440 for (;;) {
1441 a = *(unsigned long *)name;
bfcfaa77
LT		 1442 if (len < sizeof(unsigned long))
1443 break;
1444 hash += a;
f132c5be 1445 hash *= 9;
bfcfaa77
LT		 1446 name += sizeof(unsigned long);
1447 len -= sizeof(unsigned long);
1448 if (!len)
1449 goto done;
1450 }
1451 mask = ~(~0ul << len*8);
1452 hash += mask & a;
1453done:
1454 return fold_hash(hash);
1455}
1456EXPORT_SYMBOL(full_name_hash);
1457
989412bb
LT		 1458#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
1459#define ONEBYTES REPEAT_BYTE(0x01)
1460#define SLASHBYTES REPEAT_BYTE('/')
1461#define HIGHBITS REPEAT_BYTE(0x80)
bfcfaa77
LT		 1462
1463/* Return the high bit set in the first byte that is a zero */
1464static inline unsigned long has_zero(unsigned long a)
1465{
1466 return ((a - ONEBYTES) & ~a) & HIGHBITS;
1467}
1468
1469/*
1470 * Calculate the length and hash of the path component, and
1471 * return the length of the component;
1472 */
1473static inline unsigned long hash_name(const char *name, unsigned int *hashp)
1474{
1475 unsigned long a, mask, hash, len;
1476
1477 hash = a = 0;
1478 len = -sizeof(unsigned long);
1479 do {
1480 hash = (hash + a) * 9;
1481 len += sizeof(unsigned long);
1482 a = *(unsigned long *)(name+len);
1483 /* Do we have any NUL or '/' bytes in this word? */
1484 mask = has_zero(a) | has_zero(a ^ SLASHBYTES);
1485 } while (!mask);
1486
1487 /* The mask *below* the first high bit set */
1488 mask = (mask - 1) & ~mask;
1489 mask >>= 7;
1490 hash += a & mask;
1491 *hashp = fold_hash(hash);
1492
1493 return len + count_masked_bytes(mask);
1494}
1495
1496#else
1497
0145acc2
LT		 1498unsigned int full_name_hash(const unsigned char *name, unsigned int len)
1499{
1500 unsigned long hash = init_name_hash();
1501 while (len--)
1502 hash = partial_name_hash(*name++, hash);
1503 return end_name_hash(hash);
1504}
ae942ae7 1505EXPORT_SYMBOL(full_name_hash);
0145acc2 1506
200e9ef7
LT		 1507/*
1508 * We know there's a real path component here of at least
1509 * one character.
1510 */
1511static inline unsigned long hash_name(const char *name, unsigned int *hashp)
1512{
1513 unsigned long hash = init_name_hash();
1514 unsigned long len = 0, c;
1515
1516 c = (unsigned char)*name;
1517 do {
1518 len++;
1519 hash = partial_name_hash(c, hash);
1520 c = (unsigned char)name[len];
1521 } while (c && c != '/');
1522 *hashp = end_name_hash(hash);
1523 return len;
1524}
1525
bfcfaa77
LT		 1526#endif
1527
1da177e4
LT		 1528/*
1529 * Name resolution.
ea3834d9
PM		 1530 * This is the basic name resolution function, turning a pathname into
1531 * the final dentry. We expect 'base' to be positive and a directory.
1da177e4 1532 *
ea3834d9
PM		 1533 * Returns 0 and nd will have valid dentry and mnt on success.
1534 * Returns error and drops reference to input namei data on failure.
1da177e4 1535 */
6de88d72 1536static int link_path_walk(const char *name, struct nameidata *nd)
1da177e4
LT		 1537{
1538 struct path next;
1da177e4 1539 int err;
1da177e4
LT		 1540
1541 while (*name=='/')
1542 name++;
1543 if (!*name)
086e183a 1544 return 0;
1da177e4 1545
1da177e4
LT		 1546 /* At this point we know we have a real path component. */
1547 for(;;) {
1da177e4 1548 struct qstr this;
200e9ef7 1549 long len;
fe479a58 1550 int type;
1da177e4 1551
52094c8a 1552 err = may_lookup(nd);
1da177e4
LT		 1553 if (err)
1554 break;
1555
200e9ef7 1556 len = hash_name(name, &this.hash);
1da177e4 1557 this.name = name;
200e9ef7 1558 this.len = len;
1da177e4 1559
fe479a58 1560 type = LAST_NORM;
200e9ef7 1561 if (name[0] == '.') switch (len) {
fe479a58 1562 case 2:
200e9ef7 1563 if (name[1] == '.') {
fe479a58 1564 type = LAST_DOTDOT;
16c2cd71
AV		 1565 nd->flags |= LOOKUP_JUMPED;
1566 }
fe479a58
AV		 1567 break;
1568 case 1:
1569 type = LAST_DOT;
1570 }
5a202bcd
AV		 1571 if (likely(type == LAST_NORM)) {
1572 struct dentry *parent = nd->path.dentry;
16c2cd71 1573 nd->flags &= ~LOOKUP_JUMPED;
5a202bcd
AV		 1574 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1575 err = parent->d_op->d_hash(parent, nd->inode,
1576 &this);
1577 if (err < 0)
1578 break;
1579 }
1580 }
fe479a58 1581
200e9ef7 1582 if (!name[len])
1da177e4 1583 goto last_component;
200e9ef7
LT		 1584 /*
1585 * If it wasn't NUL, we know it was '/'. Skip that
1586 * slash, and continue until no more slashes.
1587 */
1588 do {
1589 len++;
1590 } while (unlikely(name[len] == '/'));
1591 if (!name[len])
b356379a 1592 goto last_component;
200e9ef7 1593 name += len;
1da177e4 1594
ce57dfc1
AV		 1595 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1596 if (err < 0)
1597 return err;
1da177e4 1598
ce57dfc1 1599 if (err) {
b356379a 1600 err = nested_symlink(&next, nd);
1da177e4 1601 if (err)
a7472bab 1602 return err;
31e6b01f 1603 }
3ddcd056
LT		 1604 if (can_lookup(nd->inode))
1605 continue;
1da177e4 1606 err = -ENOTDIR;
3ddcd056 1607 break;
1da177e4
LT		 1608 /* here ends the main loop */
1609
1da177e4 1610last_component:
b356379a
AV		 1611 nd->last = this;
1612 nd->last_type = type;
086e183a 1613 return 0;
1da177e4 1614 }
951361f9 1615 terminate_walk(nd);
1da177e4
LT		 1616 return err;
1617}
1618
70e9b357
AV		 1619static int path_init(int dfd, const char *name, unsigned int flags,
1620 struct nameidata *nd, struct file **fp)
31e6b01f
NP		 1621{
1622 int retval = 0;
1623 int fput_needed;
1624 struct file *file;
1625
1626 nd->last_type = LAST_ROOT; /* if there are only slashes... */
16c2cd71 1627 nd->flags = flags | LOOKUP_JUMPED;
31e6b01f 1628 nd->depth = 0;
5b6ca027
AV		 1629 if (flags & LOOKUP_ROOT) {
1630 struct inode *inode = nd->root.dentry->d_inode;
73d049a4
AV		 1631 if (*name) {
1632 if (!inode->i_op->lookup)
1633 return -ENOTDIR;
1634 retval = inode_permission(inode, MAY_EXEC);
1635 if (retval)
1636 return retval;
1637 }
5b6ca027
AV		 1638 nd->path = nd->root;
1639 nd->inode = inode;
1640 if (flags & LOOKUP_RCU) {
1641 br_read_lock(vfsmount_lock);
1642 rcu_read_lock();
1643 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1644 } else {
1645 path_get(&nd->path);
1646 }
1647 return 0;
1648 }
1649
31e6b01f 1650 nd->root.mnt = NULL;
31e6b01f
NP		 1651
1652 if (*name=='/') {
e41f7d4e
AV		 1653 if (flags & LOOKUP_RCU) {
1654 br_read_lock(vfsmount_lock);
1655 rcu_read_lock();
1656 set_root_rcu(nd);
1657 } else {
1658 set_root(nd);
1659 path_get(&nd->root);
1660 }
1661 nd->path = nd->root;
31e6b01f 1662 } else if (dfd == AT_FDCWD) {
e41f7d4e
AV		 1663 if (flags & LOOKUP_RCU) {
1664 struct fs_struct *fs = current->fs;
1665 unsigned seq;
31e6b01f 1666
e41f7d4e
AV		 1667 br_read_lock(vfsmount_lock);
1668 rcu_read_lock();
c28cc364 1669
e41f7d4e
AV		 1670 do {
1671 seq = read_seqcount_begin(&fs->seq);
1672 nd->path = fs->pwd;
1673 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1674 } while (read_seqcount_retry(&fs->seq, seq));
1675 } else {
1676 get_fs_pwd(current->fs, &nd->path);
1677 }
31e6b01f
NP		 1678 } else {
1679 struct dentry *dentry;
1680
1abf0c71 1681 file = fget_raw_light(dfd, &fput_needed);
31e6b01f
NP		 1682 retval = -EBADF;
1683 if (!file)
1684 goto out_fail;
1685
1686 dentry = file->f_path.dentry;
1687
f52e0c11
AV		 1688 if (*name) {
1689 retval = -ENOTDIR;
1690 if (!S_ISDIR(dentry->d_inode->i_mode))
1691 goto fput_fail;
31e6b01f 1692
4ad5abb3 1693 retval = inode_permission(dentry->d_inode, MAY_EXEC);
f52e0c11
AV		 1694 if (retval)
1695 goto fput_fail;
1696 }
31e6b01f
NP		 1697
1698 nd->path = file->f_path;
e41f7d4e
AV		 1699 if (flags & LOOKUP_RCU) {
1700 if (fput_needed)
70e9b357 1701 *fp = file;
e41f7d4e
AV		 1702 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1703 br_read_lock(vfsmount_lock);
1704 rcu_read_lock();
1705 } else {
1706 path_get(&file->f_path);
1707 fput_light(file, fput_needed);
1708 }
31e6b01f 1709 }
31e6b01f 1710
31e6b01f 1711 nd->inode = nd->path.dentry->d_inode;
9b4a9b14 1712 return 0;
2dfdd266 1713
9b4a9b14
AV		 1714fput_fail:
1715 fput_light(file, fput_needed);
1716out_fail:
1717 return retval;
1718}
1719
bd92d7fe
AV		 1720static inline int lookup_last(struct nameidata *nd, struct path *path)
1721{
1722 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1723 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1724
1725 nd->flags &= ~LOOKUP_PARENT;
1726 return walk_component(nd, path, &nd->last, nd->last_type,
1727 nd->flags & LOOKUP_FOLLOW);
1728}
1729
9b4a9b14 1730/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
ee0827cd 1731static int path_lookupat(int dfd, const char *name,
9b4a9b14
AV		 1732 unsigned int flags, struct nameidata *nd)
1733{
70e9b357 1734 struct file *base = NULL;
bd92d7fe
AV		 1735 struct path path;
1736 int err;
31e6b01f
NP		 1737
1738 /*
1739 * Path walking is largely split up into 2 different synchronisation
1740 * schemes, rcu-walk and ref-walk (explained in
1741 * Documentation/filesystems/path-lookup.txt). These share much of the
1742 * path walk code, but some things particularly setup, cleanup, and
1743 * following mounts are sufficiently divergent that functions are
1744 * duplicated. Typically there is a function foo(), and its RCU
1745 * analogue, foo_rcu().
1746 *
1747 * -ECHILD is the error number of choice (just to avoid clashes) that
1748 * is returned if some aspect of an rcu-walk fails. Such an error must
1749 * be handled by restarting a traditional ref-walk (which will always
1750 * be able to complete).
1751 */
bd92d7fe 1752 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
ee0827cd 1753
bd92d7fe
AV		 1754 if (unlikely(err))
1755 return err;
ee0827cd
AV		 1756
1757 current->total_link_count = 0;
bd92d7fe
AV		 1758 err = link_path_walk(name, nd);
1759
1760 if (!err && !(flags & LOOKUP_PARENT)) {
bd92d7fe
AV		 1761 err = lookup_last(nd, &path);
1762 while (err > 0) {
1763 void *cookie;
1764 struct path link = path;
bd92d7fe 1765 nd->flags |= LOOKUP_PARENT;
574197e0 1766 err = follow_link(&link, nd, &cookie);
bd92d7fe
AV		 1767 if (!err)
1768 err = lookup_last(nd, &path);
574197e0 1769 put_link(nd, &link, cookie);
bd92d7fe
AV		 1770 }
1771 }
ee0827cd 1772
9f1fafee
AV		 1773 if (!err)
1774 err = complete_walk(nd);
bd92d7fe
AV		 1775
1776 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1777 if (!nd->inode->i_op->lookup) {
1778 path_put(&nd->path);
bd23a539 1779 err = -ENOTDIR;
bd92d7fe
AV		 1780 }
1781 }
16c2cd71 1782
70e9b357
AV		 1783 if (base)
1784 fput(base);
ee0827cd 1785
5b6ca027 1786 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
2a737871
AV		 1787 path_put(&nd->root);
1788 nd->root.mnt = NULL;
1789 }
bd92d7fe 1790 return err;
ee0827cd 1791}
31e6b01f 1792
ee0827cd
AV		 1793static int do_path_lookup(int dfd, const char *name,
1794 unsigned int flags, struct nameidata *nd)
1795{
1796 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1797 if (unlikely(retval == -ECHILD))
1798 retval = path_lookupat(dfd, name, flags, nd);
1799 if (unlikely(retval == -ESTALE))
1800 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
31e6b01f
NP		 1801
1802 if (likely(!retval)) {
1803 if (unlikely(!audit_dummy_context())) {
1804 if (nd->path.dentry && nd->inode)
1805 audit_inode(name, nd->path.dentry);
1806 }
1807 }
170aa3d0 1808 return retval;
1da177e4
LT		 1809}
1810
c9c6cac0 1811int kern_path_parent(const char *name, struct nameidata *nd)
5590ff0d 1812{
c9c6cac0 1813 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
5590ff0d
UD		 1814}
1815
d1811465
AV		 1816int kern_path(const char *name, unsigned int flags, struct path *path)
1817{
1818 struct nameidata nd;
1819 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1820 if (!res)
1821 *path = nd.path;
1822 return res;
1823}
1824
16f18200
JJS		 1825/**
1826 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1827 * @dentry: pointer to dentry of the base directory
1828 * @mnt: pointer to vfs mount of the base directory
1829 * @name: pointer to file name
1830 * @flags: lookup flags
e0a01249 1831 * @path: pointer to struct path to fill
16f18200
JJS		 1832 */
1833int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1834 const char *name, unsigned int flags,
e0a01249 1835 struct path *path)
16f18200 1836{
e0a01249
AV		 1837 struct nameidata nd;
1838 int err;
1839 nd.root.dentry = dentry;
1840 nd.root.mnt = mnt;
1841 BUG_ON(flags & LOOKUP_PARENT);
5b6ca027 1842 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
e0a01249
AV		 1843 err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
1844 if (!err)
1845 *path = nd.path;
1846 return err;
16f18200
JJS		 1847}
1848
eead1911
CH		 1849static struct dentry *__lookup_hash(struct qstr *name,
1850 struct dentry *base, struct nameidata *nd)
1da177e4 1851{
81fca444 1852 struct inode *inode = base->d_inode;
057f6c01 1853 struct dentry *dentry;
1da177e4
LT		 1854 int err;
1855
4ad5abb3 1856 err = inode_permission(inode, MAY_EXEC);
81fca444
CH		 1857 if (err)
1858 return ERR_PTR(err);
1da177e4 1859
b04f784e
NP		 1860 /*
1861 * Don't bother with __d_lookup: callers are for creat as
1862 * well as unlink, so a lot of the time it would cost
1863 * a double lookup.
6e6b1bd1 1864 */
b04f784e 1865 dentry = d_lookup(base, name);
6e6b1bd1 1866
44396f4b
JB		 1867 if (dentry && d_need_lookup(dentry)) {
1868 /*
1869 * __lookup_hash is called with the parent dir's i_mutex already
1870 * held, so we are good to go here.
1871 */
1872 dentry = d_inode_lookup(base, dentry, nd);
1873 if (IS_ERR(dentry))
1874 return dentry;
1875 }
1876
d2d9e9fb
AV		 1877 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1878 int status = d_revalidate(dentry, nd);
1879 if (unlikely(status <= 0)) {
1880 /*
1881 * The dentry failed validation.
1882 * If d_revalidate returned 0 attempt to invalidate
1883 * the dentry otherwise d_revalidate is asking us
1884 * to return a fail status.
1885 */
1886 if (status < 0) {
1887 dput(dentry);
1888 return ERR_PTR(status);
1889 } else if (!d_invalidate(dentry)) {
1890 dput(dentry);
1891 dentry = NULL;
1892 }
1893 }
1894 }
6e6b1bd1 1895
baa03890
NP		 1896 if (!dentry)
1897 dentry = d_alloc_and_lookup(base, name, nd);
5a202bcd 1898
1da177e4
LT		 1899 return dentry;
1900}
1901
057f6c01
JM		 1902/*
1903 * Restricted form of lookup. Doesn't follow links, single-component only,
1904 * needs parent already locked. Doesn't follow mounts.
1905 * SMP-safe.
1906 */
eead1911 1907static struct dentry *lookup_hash(struct nameidata *nd)
057f6c01 1908{
4ac91378 1909 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1da177e4
LT		 1910}
1911
eead1911 1912/**
a6b91919 1913 * lookup_one_len - filesystem helper to lookup single pathname component
eead1911
CH		 1914 * @name: pathname component to lookup
1915 * @base: base directory to lookup from
1916 * @len: maximum length @len should be interpreted to
1917 *
a6b91919
RD		 1918 * Note that this routine is purely a helper for filesystem usage and should
1919 * not be called by generic code. Also note that by using this function the
eead1911
CH		 1920 * nameidata argument is passed to the filesystem methods and a filesystem
1921 * using this helper needs to be prepared for that.
1922 */
057f6c01
JM		 1923struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1924{
057f6c01 1925 struct qstr this;
6a96ba54 1926 unsigned int c;
057f6c01 1927
2f9092e1
DW		 1928 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1929
6a96ba54
AV		 1930 this.name = name;
1931 this.len = len;
0145acc2 1932 this.hash = full_name_hash(name, len);
6a96ba54
AV		 1933 if (!len)
1934 return ERR_PTR(-EACCES);
1935
6a96ba54
AV		 1936 while (len--) {
1937 c = *(const unsigned char *)name++;
1938 if (c == '/' || c == '\0')
1939 return ERR_PTR(-EACCES);
6a96ba54 1940 }
5a202bcd
AV		 1941 /*
1942 * See if the low-level filesystem might want
1943 * to use its own hash..
1944 */
1945 if (base->d_flags & DCACHE_OP_HASH) {
1946 int err = base->d_op->d_hash(base, base->d_inode, &this);
1947 if (err < 0)
1948 return ERR_PTR(err);
1949 }
eead1911 1950
49705b77 1951 return __lookup_hash(&this, base, NULL);
057f6c01
JM		 1952}
1953
1fa1e7f6
AW		 1954int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
1955 struct path *path, int *empty)
1da177e4 1956{
2d8f3038 1957 struct nameidata nd;
1fa1e7f6 1958 char *tmp = getname_flags(name, flags, empty);
1da177e4 1959 int err = PTR_ERR(tmp);
1da177e4 1960 if (!IS_ERR(tmp)) {
2d8f3038
AV		 1961
1962 BUG_ON(flags & LOOKUP_PARENT);
1963
1964 err = do_path_lookup(dfd, tmp, flags, &nd);
1da177e4 1965 putname(tmp);
2d8f3038
AV		 1966 if (!err)
1967 *path = nd.path;
1da177e4
LT		 1968 }
1969 return err;
1970}
1971
1fa1e7f6
AW		 1972int user_path_at(int dfd, const char __user *name, unsigned flags,
1973 struct path *path)
1974{
1975 return user_path_at_empty(dfd, name, flags, path, 0);
1976}
1977
2ad94ae6
AV		 1978static int user_path_parent(int dfd, const char __user *path,
1979 struct nameidata *nd, char **name)
1980{
1981 char *s = getname(path);
1982 int error;
1983
1984 if (IS_ERR(s))
1985 return PTR_ERR(s);
1986
1987 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1988 if (error)
1989 putname(s);
1990 else
1991 *name = s;
1992
1993 return error;
1994}
1995
1da177e4
LT		 1996/*
1997 * It's inline, so penalty for filesystems that don't use sticky bit is
1998 * minimal.
1999 */
2000static inline int check_sticky(struct inode *dir, struct inode *inode)
2001{
da9592ed
DH		 2002 uid_t fsuid = current_fsuid();
2003
1da177e4
LT		 2004 if (!(dir->i_mode & S_ISVTX))
2005 return 0;
e795b717
SH		 2006 if (current_user_ns() != inode_userns(inode))
2007 goto other_userns;
da9592ed 2008 if (inode->i_uid == fsuid)
1da177e4 2009 return 0;
da9592ed 2010 if (dir->i_uid == fsuid)
1da177e4 2011 return 0;
e795b717
SH		 2012
2013other_userns:
2014 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1da177e4
LT		 2015}
2016
2017/*
2018 * Check whether we can remove a link victim from directory dir, check
2019 * whether the type of victim is right.
2020 * 1. We can't do it if dir is read-only (done in permission())
2021 * 2. We should have write and exec permissions on dir
2022 * 3. We can't remove anything from append-only dir
2023 * 4. We can't do anything with immutable dir (done in permission())
2024 * 5. If the sticky bit on dir is set we should either
2025 * a. be owner of dir, or
2026 * b. be owner of victim, or
2027 * c. have CAP_FOWNER capability
2028 * 6. If the victim is append-only or immutable we can't do antyhing with
2029 * links pointing to it.
2030 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2031 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2032 * 9. We can't remove a root or mountpoint.
2033 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2034 * nfs_async_unlink().
2035 */
858119e1 2036static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1da177e4
LT		 2037{
2038 int error;
2039
2040 if (!victim->d_inode)
2041 return -ENOENT;
2042
2043 BUG_ON(victim->d_parent->d_inode != dir);
cccc6bba 2044 audit_inode_child(victim, dir);
1da177e4 2045
f419a2e3 2046 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT		 2047 if (error)
2048 return error;
2049 if (IS_APPEND(dir))
2050 return -EPERM;
2051 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
f9454548 2052 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1da177e4
LT		 2053 return -EPERM;
2054 if (isdir) {
2055 if (!S_ISDIR(victim->d_inode->i_mode))
2056 return -ENOTDIR;
2057 if (IS_ROOT(victim))
2058 return -EBUSY;
2059 } else if (S_ISDIR(victim->d_inode->i_mode))
2060 return -EISDIR;
2061 if (IS_DEADDIR(dir))
2062 return -ENOENT;
2063 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
2064 return -EBUSY;
2065 return 0;
2066}
2067
2068/* Check whether we can create an object with dentry child in directory
2069 * dir.
2070 * 1. We can't do it if child already exists (open has special treatment for
2071 * this case, but since we are inlined it's OK)
2072 * 2. We can't do it if dir is read-only (done in permission())
2073 * 3. We should have write and exec permissions on dir
2074 * 4. We can't do it if dir is immutable (done in permission())
2075 */
a95164d9 2076static inline int may_create(struct inode *dir, struct dentry *child)
1da177e4
LT		 2077{
2078 if (child->d_inode)
2079 return -EEXIST;
2080 if (IS_DEADDIR(dir))
2081 return -ENOENT;
f419a2e3 2082 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT		 2083}
2084
1da177e4
LT		 2085/*
2086 * p1 and p2 should be directories on the same fs.
2087 */
2088struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
2089{
2090 struct dentry *p;
2091
2092 if (p1 == p2) {
f2eace23 2093 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1da177e4
LT		 2094 return NULL;
2095 }
2096
a11f3a05 2097 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1da177e4 2098
e2761a11
OH		 2099 p = d_ancestor(p2, p1);
2100 if (p) {
2101 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
2102 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
2103 return p;
1da177e4
LT		 2104 }
2105
e2761a11
OH		 2106 p = d_ancestor(p1, p2);
2107 if (p) {
2108 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
2109 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
2110 return p;
1da177e4
LT		 2111 }
2112
f2eace23
IM		 2113 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
2114 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1da177e4
LT		 2115 return NULL;
2116}
2117
2118void unlock_rename(struct dentry *p1, struct dentry *p2)
2119{
1b1dcc1b 2120 mutex_unlock(&p1->d_inode->i_mutex);
1da177e4 2121 if (p1 != p2) {
1b1dcc1b 2122 mutex_unlock(&p2->d_inode->i_mutex);
a11f3a05 2123 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1da177e4
LT		 2124 }
2125}
2126
4acdaf27 2127int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
1da177e4
LT		 2128 struct nameidata *nd)
2129{
a95164d9 2130 int error = may_create(dir, dentry);
1da177e4
LT		 2131
2132 if (error)
2133 return error;
2134
acfa4380 2135 if (!dir->i_op->create)
1da177e4
LT		 2136 return -EACCES; /* shouldn't it be ENOSYS? */
2137 mode &= S_IALLUGO;
2138 mode |= S_IFREG;
2139 error = security_inode_create(dir, dentry, mode);
2140 if (error)
2141 return error;
1da177e4 2142 error = dir->i_op->create(dir, dentry, mode, nd);
a74574aa 2143 if (!error)
f38aa942 2144 fsnotify_create(dir, dentry);
1da177e4
LT		 2145 return error;
2146}
2147
73d049a4 2148static int may_open(struct path *path, int acc_mode, int flag)
1da177e4 2149{
3fb64190 2150 struct dentry *dentry = path->dentry;
1da177e4
LT		 2151 struct inode *inode = dentry->d_inode;
2152 int error;
2153
bcda7652
AV		 2154 /* O_PATH? */
2155 if (!acc_mode)
2156 return 0;
2157
1da177e4
LT		 2158 if (!inode)
2159 return -ENOENT;
2160
c8fe8f30
CH		 2161 switch (inode->i_mode & S_IFMT) {
2162 case S_IFLNK:
1da177e4 2163 return -ELOOP;
c8fe8f30
CH		 2164 case S_IFDIR:
2165 if (acc_mode & MAY_WRITE)
2166 return -EISDIR;
2167 break;
2168 case S_IFBLK:
2169 case S_IFCHR:
3fb64190 2170 if (path->mnt->mnt_flags & MNT_NODEV)
1da177e4 2171 return -EACCES;
c8fe8f30
CH		 2172 /*FALLTHRU*/
2173 case S_IFIFO:
2174 case S_IFSOCK:
1da177e4 2175 flag &= ~O_TRUNC;
c8fe8f30 2176 break;
4a3fd211 2177 }
b41572e9 2178
3fb64190 2179 error = inode_permission(inode, acc_mode);
b41572e9
DH		 2180 if (error)
2181 return error;
6146f0d5 2182
1da177e4
LT		 2183 /*
2184 * An append-only file must be opened in append mode for writing.
2185 */
2186 if (IS_APPEND(inode)) {
8737c930 2187 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
7715b521 2188 return -EPERM;
1da177e4 2189 if (flag & O_TRUNC)
7715b521 2190 return -EPERM;
1da177e4
LT		 2191 }
2192
2193 /* O_NOATIME can only be set by the owner or superuser */
2e149670 2194 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
7715b521 2195 return -EPERM;
1da177e4 2196
f3c7691e 2197 return 0;
7715b521 2198}
1da177e4 2199
e1181ee6 2200static int handle_truncate(struct file *filp)
7715b521 2201{
e1181ee6 2202 struct path *path = &filp->f_path;
7715b521
AV		 2203 struct inode *inode = path->dentry->d_inode;
2204 int error = get_write_access(inode);
2205 if (error)
2206 return error;
2207 /*
2208 * Refuse to truncate files with mandatory locks held on them.
2209 */
2210 error = locks_verify_locked(inode);
2211 if (!error)
ea0d3ab2 2212 error = security_path_truncate(path);
7715b521
AV		 2213 if (!error) {
2214 error = do_truncate(path->dentry, 0,
2215 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
e1181ee6 2216 filp);
7715b521
AV		 2217 }
2218 put_write_access(inode);
acd0c935 2219 return error;
1da177e4
LT		 2220}
2221
d57999e1
DH		 2222static inline int open_to_namei_flags(int flag)
2223{
8a5e929d
AV		 2224 if ((flag & O_ACCMODE) == 3)
2225 flag--;
d57999e1
DH		 2226 return flag;
2227}
2228
31e6b01f 2229/*
fe2d35ff 2230 * Handle the last step of open()
31e6b01f 2231 */
fb1cc555 2232static struct file *do_last(struct nameidata *nd, struct path *path,
c3e380b0 2233 const struct open_flags *op, const char *pathname)
fb1cc555 2234{
a1e28038 2235 struct dentry *dir = nd->path.dentry;
6c0d46c4 2236 struct dentry *dentry;
ca344a89 2237 int open_flag = op->open_flag;
6c0d46c4 2238 int will_truncate = open_flag & O_TRUNC;
ca344a89 2239 int want_write = 0;
bcda7652 2240 int acc_mode = op->acc_mode;
fb1cc555 2241 struct file *filp;
16c2cd71 2242 int error;
1f36f774 2243
c3e380b0
AV		 2244 nd->flags &= ~LOOKUP_PARENT;
2245 nd->flags |= op->intent;
2246
1f36f774
AV		 2247 switch (nd->last_type) {
2248 case LAST_DOTDOT:
176306f5 2249 case LAST_DOT:
fe2d35ff
AV		 2250 error = handle_dots(nd, nd->last_type);
2251 if (error)
2252 return ERR_PTR(error);
1f36f774 2253 /* fallthrough */
1f36f774 2254 case LAST_ROOT:
9f1fafee 2255 error = complete_walk(nd);
16c2cd71 2256 if (error)
9f1fafee 2257 return ERR_PTR(error);
fe2d35ff 2258 audit_inode(pathname, nd->path.dentry);
ca344a89 2259 if (open_flag & O_CREAT) {
fe2d35ff
AV		 2260 error = -EISDIR;
2261 goto exit;
2262 }
2263 goto ok;
1f36f774 2264 case LAST_BIND:
9f1fafee 2265 error = complete_walk(nd);
16c2cd71 2266 if (error)
9f1fafee 2267 return ERR_PTR(error);
1f36f774 2268 audit_inode(pathname, dir);
67ee3ad2 2269 goto ok;
1f36f774 2270 }
67ee3ad2 2271
ca344a89 2272 if (!(open_flag & O_CREAT)) {
bcda7652 2273 int symlink_ok = 0;
fe2d35ff
AV		 2274 if (nd->last.name[nd->last.len])
2275 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
bcda7652
AV		 2276 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2277 symlink_ok = 1;
fe2d35ff 2278 /* we _can_ be in RCU mode here */
ce57dfc1
AV		 2279 error = walk_component(nd, path, &nd->last, LAST_NORM,
2280 !symlink_ok);
2281 if (error < 0)
fe2d35ff 2282 return ERR_PTR(error);
ce57dfc1 2283 if (error) /* symlink */
fe2d35ff 2284 return NULL;
fe2d35ff 2285 /* sayonara */
9f1fafee
AV		 2286 error = complete_walk(nd);
2287 if (error)
7f6c7e62 2288 return ERR_PTR(error);
fe2d35ff
AV		 2289
2290 error = -ENOTDIR;
2291 if (nd->flags & LOOKUP_DIRECTORY) {
ce57dfc1 2292 if (!nd->inode->i_op->lookup)
fe2d35ff
AV		 2293 goto exit;
2294 }
2295 audit_inode(pathname, nd->path.dentry);
2296 goto ok;
2297 }
2298
2299 /* create side of things */
a3fbbde7
AV		 2300 /*
2301 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been
2302 * cleared when we got to the last component we are about to look up
2303 */
9f1fafee
AV		 2304 error = complete_walk(nd);
2305 if (error)
2306 return ERR_PTR(error);
fe2d35ff
AV		 2307
2308 audit_inode(pathname, dir);
16c2cd71 2309 error = -EISDIR;
1f36f774 2310 /* trailing slashes? */
31e6b01f
NP		 2311 if (nd->last.name[nd->last.len])
2312 goto exit;
a2c36b45 2313
a1e28038
AV		 2314 mutex_lock(&dir->d_inode->i_mutex);
2315
6c0d46c4
AV		 2316 dentry = lookup_hash(nd);
2317 error = PTR_ERR(dentry);
2318 if (IS_ERR(dentry)) {
fb1cc555
AV		 2319 mutex_unlock(&dir->d_inode->i_mutex);
2320 goto exit;
2321 }
2322
6c0d46c4
AV		 2323 path->dentry = dentry;
2324 path->mnt = nd->path.mnt;
2325
fb1cc555 2326 /* Negative dentry, just create the file */
6c0d46c4 2327 if (!dentry->d_inode) {
a218d0fd 2328 umode_t mode = op->mode;
6c0d46c4
AV		 2329 if (!IS_POSIXACL(dir->d_inode))
2330 mode &= ~current_umask();
fb1cc555
AV		 2331 /*
2332 * This write is needed to ensure that a
6c0d46c4 2333 * rw->ro transition does not occur between
fb1cc555
AV		 2334 * the time when the file is created and when
2335 * a permanent write count is taken through
2336 * the 'struct file' in nameidata_to_filp().
2337 */
2338 error = mnt_want_write(nd->path.mnt);
2339 if (error)
2340 goto exit_mutex_unlock;
ca344a89 2341 want_write = 1;
9b44f1b3 2342 /* Don't check for write permission, don't truncate */
ca344a89 2343 open_flag &= ~O_TRUNC;
6c0d46c4 2344 will_truncate = 0;
bcda7652 2345 acc_mode = MAY_OPEN;
6c0d46c4
AV		 2346 error = security_path_mknod(&nd->path, dentry, mode, 0);
2347 if (error)
2348 goto exit_mutex_unlock;
2349 error = vfs_create(dir->d_inode, dentry, mode, nd);
2350 if (error)
2351 goto exit_mutex_unlock;
2352 mutex_unlock(&dir->d_inode->i_mutex);
2353 dput(nd->path.dentry);
2354 nd->path.dentry = dentry;
ca344a89 2355 goto common;
fb1cc555
AV		 2356 }
2357
2358 /*
2359 * It already exists.
2360 */
2361 mutex_unlock(&dir->d_inode->i_mutex);
2362 audit_inode(pathname, path->dentry);
2363
2364 error = -EEXIST;
ca344a89 2365 if (open_flag & O_EXCL)
fb1cc555
AV		 2366 goto exit_dput;
2367
9875cf80
DH		 2368 error = follow_managed(path, nd->flags);
2369 if (error < 0)
2370 goto exit_dput;
fb1cc555 2371
a3fbbde7
AV		 2372 if (error)
2373 nd->flags |= LOOKUP_JUMPED;
2374
fb1cc555
AV		 2375 error = -ENOENT;
2376 if (!path->dentry->d_inode)
2377 goto exit_dput;
9e67f361
AV		 2378
2379 if (path->dentry->d_inode->i_op->follow_link)
fb1cc555 2380 return NULL;
fb1cc555
AV		 2381
2382 path_to_nameidata(path, nd);
31e6b01f 2383 nd->inode = path->dentry->d_inode;
a3fbbde7
AV		 2384 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
2385 error = complete_walk(nd);
2386 if (error)
097b180c 2387 return ERR_PTR(error);
fb1cc555 2388 error = -EISDIR;
31e6b01f 2389 if (S_ISDIR(nd->inode->i_mode))
fb1cc555 2390 goto exit;
67ee3ad2 2391ok:
6c0d46c4
AV		 2392 if (!S_ISREG(nd->inode->i_mode))
2393 will_truncate = 0;
2394
0f9d1a10
AV		 2395 if (will_truncate) {
2396 error = mnt_want_write(nd->path.mnt);
2397 if (error)
2398 goto exit;
ca344a89 2399 want_write = 1;
0f9d1a10 2400 }
ca344a89 2401common:
bcda7652 2402 error = may_open(&nd->path, acc_mode, open_flag);
ca344a89 2403 if (error)
0f9d1a10 2404 goto exit;
0f9d1a10
AV		 2405 filp = nameidata_to_filp(nd);
2406 if (!IS_ERR(filp)) {
2407 error = ima_file_check(filp, op->acc_mode);
2408 if (error) {
2409 fput(filp);
2410 filp = ERR_PTR(error);
2411 }
2412 }
2413 if (!IS_ERR(filp)) {
2414 if (will_truncate) {
2415 error = handle_truncate(filp);
2416 if (error) {
2417 fput(filp);
2418 filp = ERR_PTR(error);
2419 }
2420 }
2421 }
ca344a89
AV		 2422out:
2423 if (want_write)
0f9d1a10
AV		 2424 mnt_drop_write(nd->path.mnt);
2425 path_put(&nd->path);
fb1cc555
AV		 2426 return filp;
2427
2428exit_mutex_unlock:
2429 mutex_unlock(&dir->d_inode->i_mutex);
2430exit_dput:
2431 path_put_conditional(path, nd);
2432exit:
ca344a89
AV		 2433 filp = ERR_PTR(error);
2434 goto out;
fb1cc555
AV		 2435}
2436
13aab428 2437static struct file *path_openat(int dfd, const char *pathname,
73d049a4 2438 struct nameidata *nd, const struct open_flags *op, int flags)
1da177e4 2439{
fe2d35ff 2440 struct file *base = NULL;
4a3fd211 2441 struct file *filp;
9850c056 2442 struct path path;
13aab428 2443 int error;
31e6b01f
NP		 2444
2445 filp = get_empty_filp();
2446 if (!filp)
2447 return ERR_PTR(-ENFILE);
2448
47c805dc 2449 filp->f_flags = op->open_flag;
73d049a4
AV		 2450 nd->intent.open.file = filp;
2451 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2452 nd->intent.open.create_mode = op->mode;
31e6b01f 2453
73d049a4 2454 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
31e6b01f 2455 if (unlikely(error))
13aab428 2456 goto out_filp;
31e6b01f 2457
fe2d35ff 2458 current->total_link_count = 0;
73d049a4 2459 error = link_path_walk(pathname, nd);
31e6b01f
NP		 2460 if (unlikely(error))
2461 goto out_filp;
1da177e4 2462
73d049a4 2463 filp = do_last(nd, &path, op, pathname);
806b681c 2464 while (unlikely(!filp)) { /* trailing symlink */
7b9337aa 2465 struct path link = path;
def4af30 2466 void *cookie;
574197e0 2467 if (!(nd->flags & LOOKUP_FOLLOW)) {
73d049a4
AV		 2468 path_put_conditional(&path, nd);
2469 path_put(&nd->path);
40b39136
AV		 2470 filp = ERR_PTR(-ELOOP);
2471 break;
2472 }
73d049a4
AV		 2473 nd->flags |= LOOKUP_PARENT;
2474 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
574197e0 2475 error = follow_link(&link, nd, &cookie);
c3e380b0 2476 if (unlikely(error))
f1afe9ef 2477 filp = ERR_PTR(error);
c3e380b0 2478 else
73d049a4 2479 filp = do_last(nd, &path, op, pathname);
574197e0 2480 put_link(nd, &link, cookie);
806b681c 2481 }
10fa8e62 2482out:
73d049a4
AV		 2483 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2484 path_put(&nd->root);
fe2d35ff
AV		 2485 if (base)
2486 fput(base);
73d049a4 2487 release_open_intent(nd);
10fa8e62 2488 return filp;
1da177e4 2489
31e6b01f 2490out_filp:
806b681c 2491 filp = ERR_PTR(error);
10fa8e62 2492 goto out;
1da177e4
LT		 2493}
2494
13aab428
AV		 2495struct file *do_filp_open(int dfd, const char *pathname,
2496 const struct open_flags *op, int flags)
2497{
73d049a4 2498 struct nameidata nd;
13aab428
AV		 2499 struct file *filp;
2500
73d049a4 2501 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
13aab428 2502 if (unlikely(filp == ERR_PTR(-ECHILD)))
73d049a4 2503 filp = path_openat(dfd, pathname, &nd, op, flags);
13aab428 2504 if (unlikely(filp == ERR_PTR(-ESTALE)))
73d049a4 2505 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
13aab428
AV		 2506 return filp;
2507}
2508
73d049a4
AV		 2509struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2510 const char *name, const struct open_flags *op, int flags)
2511{
2512 struct nameidata nd;
2513 struct file *file;
2514
2515 nd.root.mnt = mnt;
2516 nd.root.dentry = dentry;
2517
2518 flags |= LOOKUP_ROOT;
2519
bcda7652 2520 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
73d049a4
AV		 2521 return ERR_PTR(-ELOOP);
2522
2523 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2524 if (unlikely(file == ERR_PTR(-ECHILD)))
2525 file = path_openat(-1, name, &nd, op, flags);
2526 if (unlikely(file == ERR_PTR(-ESTALE)))
2527 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2528 return file;
2529}
2530
ed75e95d 2531struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
1da177e4 2532{
c663e5d8 2533 struct dentry *dentry = ERR_PTR(-EEXIST);
ed75e95d
AV		 2534 struct nameidata nd;
2535 int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
2536 if (error)
2537 return ERR_PTR(error);
1da177e4 2538
c663e5d8
CH		 2539 /*
2540 * Yucky last component or no last component at all?
2541 * (foo/., foo/.., /////)
2542 */
ed75e95d
AV		 2543 if (nd.last_type != LAST_NORM)
2544 goto out;
2545 nd.flags &= ~LOOKUP_PARENT;
2546 nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2547 nd.intent.open.flags = O_EXCL;
c663e5d8
CH		 2548
2549 /*
2550 * Do the final lookup.
2551 */
ed75e95d
AV		 2552 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2553 dentry = lookup_hash(&nd);
1da177e4
LT		 2554 if (IS_ERR(dentry))
2555 goto fail;
c663e5d8 2556
e9baf6e5
AV		 2557 if (dentry->d_inode)
2558 goto eexist;
c663e5d8
CH		 2559 /*
2560 * Special case - lookup gave negative, but... we had foo/bar/
2561 * From the vfs_mknod() POV we just have a negative dentry -
2562 * all is fine. Let's be bastards - you had / on the end, you've
2563 * been asking for (non-existent) directory. -ENOENT for you.
2564 */
ed75e95d 2565 if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
e9baf6e5
AV		 2566 dput(dentry);
2567 dentry = ERR_PTR(-ENOENT);
ed75e95d 2568 goto fail;
e9baf6e5 2569 }
ed75e95d 2570 *path = nd.path;
1da177e4 2571 return dentry;
e9baf6e5 2572eexist:
1da177e4 2573 dput(dentry);
e9baf6e5 2574 dentry = ERR_PTR(-EEXIST);
1da177e4 2575fail:
ed75e95d
AV		 2576 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2577out:
2578 path_put(&nd.path);
1da177e4
LT		 2579 return dentry;
2580}
dae6ad8f
AV		 2581EXPORT_SYMBOL(kern_path_create);
2582
2583struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
2584{
2585 char *tmp = getname(pathname);
2586 struct dentry *res;
2587 if (IS_ERR(tmp))
2588 return ERR_CAST(tmp);
2589 res = kern_path_create(dfd, tmp, path, is_dir);
2590 putname(tmp);
2591 return res;
2592}
2593EXPORT_SYMBOL(user_path_create);
2594
1a67aafb 2595int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1da177e4 2596{
a95164d9 2597 int error = may_create(dir, dentry);
1da177e4
LT		 2598
2599 if (error)
2600 return error;
2601
e795b717
SH		 2602 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2603 !ns_capable(inode_userns(dir), CAP_MKNOD))
1da177e4
LT		 2604 return -EPERM;
2605
acfa4380 2606 if (!dir->i_op->mknod)
1da177e4
LT		 2607 return -EPERM;
2608
08ce5f16
SH		 2609 error = devcgroup_inode_mknod(mode, dev);
2610 if (error)
2611 return error;
2612
1da177e4
LT		 2613 error = security_inode_mknod(dir, dentry, mode, dev);
2614 if (error)
2615 return error;
2616
1da177e4 2617 error = dir->i_op->mknod(dir, dentry, mode, dev);
a74574aa 2618 if (!error)
f38aa942 2619 fsnotify_create(dir, dentry);
1da177e4
LT		 2620 return error;
2621}
2622
f69aac00 2623static int may_mknod(umode_t mode)
463c3197
DH		 2624{
2625 switch (mode & S_IFMT) {
2626 case S_IFREG:
2627 case S_IFCHR:
2628 case S_IFBLK:
2629 case S_IFIFO:
2630 case S_IFSOCK:
2631 case 0: /* zero mode translates to S_IFREG */
2632 return 0;
2633 case S_IFDIR:
2634 return -EPERM;
2635 default:
2636 return -EINVAL;
2637 }
2638}
2639
8208a22b 2640SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
2e4d0924 2641 unsigned, dev)
1da177e4 2642{
2ad94ae6 2643 struct dentry *dentry;
dae6ad8f
AV		 2644 struct path path;
2645 int error;
1da177e4
LT		 2646
2647 if (S_ISDIR(mode))
2648 return -EPERM;
1da177e4 2649
dae6ad8f
AV		 2650 dentry = user_path_create(dfd, filename, &path, 0);
2651 if (IS_ERR(dentry))
2652 return PTR_ERR(dentry);
2ad94ae6 2653
dae6ad8f 2654 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 2655 mode &= ~current_umask();
463c3197
DH		 2656 error = may_mknod(mode);
2657 if (error)
2658 goto out_dput;
dae6ad8f 2659 error = mnt_want_write(path.mnt);
463c3197
DH		 2660 if (error)
2661 goto out_dput;
dae6ad8f 2662 error = security_path_mknod(&path, dentry, mode, dev);
be6d3e56
KT		 2663 if (error)
2664 goto out_drop_write;
463c3197 2665 switch (mode & S_IFMT) {
1da177e4 2666 case 0: case S_IFREG:
dae6ad8f 2667 error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
1da177e4
LT		 2668 break;
2669 case S_IFCHR: case S_IFBLK:
dae6ad8f 2670 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
1da177e4
LT		 2671 new_decode_dev(dev));
2672 break;
2673 case S_IFIFO: case S_IFSOCK:
dae6ad8f 2674 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
1da177e4 2675 break;
1da177e4 2676 }
be6d3e56 2677out_drop_write:
dae6ad8f 2678 mnt_drop_write(path.mnt);
463c3197
DH		 2679out_dput:
2680 dput(dentry);
dae6ad8f
AV		 2681 mutex_unlock(&path.dentry->d_inode->i_mutex);
2682 path_put(&path);
1da177e4
LT		 2683
2684 return error;
2685}
2686
8208a22b 2687SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
5590ff0d
UD		 2688{
2689 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2690}
2691
18bb1db3 2692int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1da177e4 2693{
a95164d9 2694 int error = may_create(dir, dentry);
8de52778 2695 unsigned max_links = dir->i_sb->s_max_links;
1da177e4
LT		 2696
2697 if (error)
2698 return error;
2699
acfa4380 2700 if (!dir->i_op->mkdir)
1da177e4
LT		 2701 return -EPERM;
2702
2703 mode &= (S_IRWXUGO|S_ISVTX);
2704 error = security_inode_mkdir(dir, dentry, mode);
2705 if (error)
2706 return error;
2707
8de52778
AV		 2708 if (max_links && dir->i_nlink >= max_links)
2709 return -EMLINK;
2710
1da177e4 2711 error = dir->i_op->mkdir(dir, dentry, mode);
a74574aa 2712 if (!error)
f38aa942 2713 fsnotify_mkdir(dir, dentry);
1da177e4
LT		 2714 return error;
2715}
2716
a218d0fd 2717SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
1da177e4 2718{
6902d925 2719 struct dentry *dentry;
dae6ad8f
AV		 2720 struct path path;
2721 int error;
1da177e4 2722
dae6ad8f 2723 dentry = user_path_create(dfd, pathname, &path, 1);
6902d925 2724 if (IS_ERR(dentry))
dae6ad8f 2725 return PTR_ERR(dentry);
1da177e4 2726
dae6ad8f 2727 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 2728 mode &= ~current_umask();
dae6ad8f 2729 error = mnt_want_write(path.mnt);
463c3197
DH		 2730 if (error)
2731 goto out_dput;
dae6ad8f 2732 error = security_path_mkdir(&path, dentry, mode);
be6d3e56
KT		 2733 if (error)
2734 goto out_drop_write;
dae6ad8f 2735 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
be6d3e56 2736out_drop_write:
dae6ad8f 2737 mnt_drop_write(path.mnt);
463c3197 2738out_dput:
6902d925 2739 dput(dentry);
dae6ad8f
AV		 2740 mutex_unlock(&path.dentry->d_inode->i_mutex);
2741 path_put(&path);
1da177e4
LT		 2742 return error;
2743}
2744
a218d0fd 2745SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
5590ff0d
UD		 2746{
2747 return sys_mkdirat(AT_FDCWD, pathname, mode);
2748}
2749
1da177e4 2750/*
a71905f0
SW		 2751 * The dentry_unhash() helper will try to drop the dentry early: we
2752 * should have a usage count of 2 if we're the only user of this
2753 * dentry, and if that is true (possibly after pruning the dcache),
2754 * then we drop the dentry now.
1da177e4
LT		 2755 *
2756 * A low-level filesystem can, if it choses, legally
2757 * do a
2758 *
2759 * if (!d_unhashed(dentry))
2760 * return -EBUSY;
2761 *
2762 * if it cannot handle the case of removing a directory
2763 * that is still in use by something else..
2764 */
2765void dentry_unhash(struct dentry *dentry)
2766{
dc168427 2767 shrink_dcache_parent(dentry);
1da177e4 2768 spin_lock(&dentry->d_lock);
64252c75 2769 if (dentry->d_count == 1)
1da177e4
LT		 2770 __d_drop(dentry);
2771 spin_unlock(&dentry->d_lock);
1da177e4
LT		 2772}
2773
2774int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2775{
2776 int error = may_delete(dir, dentry, 1);
2777
2778 if (error)
2779 return error;
2780
acfa4380 2781 if (!dir->i_op->rmdir)
1da177e4
LT		 2782 return -EPERM;
2783
1d2ef590 2784 dget(dentry);
1b1dcc1b 2785 mutex_lock(&dentry->d_inode->i_mutex);
912dbc15
SW		 2786
2787 error = -EBUSY;
1da177e4 2788 if (d_mountpoint(dentry))
912dbc15
SW		 2789 goto out;
2790
2791 error = security_inode_rmdir(dir, dentry);
2792 if (error)
2793 goto out;
2794
3cebde24 2795 shrink_dcache_parent(dentry);
912dbc15
SW		 2796 error = dir->i_op->rmdir(dir, dentry);
2797 if (error)
2798 goto out;
2799
2800 dentry->d_inode->i_flags |= S_DEAD;
2801 dont_mount(dentry);
2802
2803out:
1b1dcc1b 2804 mutex_unlock(&dentry->d_inode->i_mutex);
1d2ef590 2805 dput(dentry);
912dbc15 2806 if (!error)
1da177e4 2807 d_delete(dentry);
1da177e4
LT		 2808 return error;
2809}
2810
5590ff0d 2811static long do_rmdir(int dfd, const char __user *pathname)
1da177e4
LT		 2812{
2813 int error = 0;
2814 char * name;
2815 struct dentry *dentry;
2816 struct nameidata nd;
2817
2ad94ae6 2818 error = user_path_parent(dfd, pathname, &nd, &name);
1da177e4 2819 if (error)
2ad94ae6 2820 return error;
1da177e4
LT		 2821
2822 switch(nd.last_type) {
0612d9fb
OH		 2823 case LAST_DOTDOT:
2824 error = -ENOTEMPTY;
2825 goto exit1;
2826 case LAST_DOT:
2827 error = -EINVAL;
2828 goto exit1;
2829 case LAST_ROOT:
2830 error = -EBUSY;
2831 goto exit1;
1da177e4 2832 }
0612d9fb
OH		 2833
2834 nd.flags &= ~LOOKUP_PARENT;
2835
4ac91378 2836 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
49705b77 2837 dentry = lookup_hash(&nd);
1da177e4 2838 error = PTR_ERR(dentry);
6902d925
DH		 2839 if (IS_ERR(dentry))
2840 goto exit2;
e6bc45d6
TT		 2841 if (!dentry->d_inode) {
2842 error = -ENOENT;
2843 goto exit3;
2844 }
0622753b
DH		 2845 error = mnt_want_write(nd.path.mnt);
2846 if (error)
2847 goto exit3;
be6d3e56
KT		 2848 error = security_path_rmdir(&nd.path, dentry);
2849 if (error)
2850 goto exit4;
4ac91378 2851 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
be6d3e56 2852exit4:
0622753b
DH		 2853 mnt_drop_write(nd.path.mnt);
2854exit3:
6902d925
DH		 2855 dput(dentry);
2856exit2:
4ac91378 2857 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
1da177e4 2858exit1:
1d957f9b 2859 path_put(&nd.path);
1da177e4
LT		 2860 putname(name);
2861 return error;
2862}
2863
3cdad428 2864SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
5590ff0d
UD		 2865{
2866 return do_rmdir(AT_FDCWD, pathname);
2867}
2868
1da177e4
LT		 2869int vfs_unlink(struct inode *dir, struct dentry *dentry)
2870{
2871 int error = may_delete(dir, dentry, 0);
2872
2873 if (error)
2874 return error;
2875
acfa4380 2876 if (!dir->i_op->unlink)
1da177e4
LT		 2877 return -EPERM;
2878
1b1dcc1b 2879 mutex_lock(&dentry->d_inode->i_mutex);
1da177e4
LT		 2880 if (d_mountpoint(dentry))
2881 error = -EBUSY;
2882 else {
2883 error = security_inode_unlink(dir, dentry);
bec1052e 2884 if (!error) {
1da177e4 2885 error = dir->i_op->unlink(dir, dentry);
bec1052e 2886 if (!error)
d83c49f3 2887 dont_mount(dentry);
bec1052e 2888 }
1da177e4 2889 }
1b1dcc1b 2890 mutex_unlock(&dentry->d_inode->i_mutex);
1da177e4
LT		 2891
2892 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2893 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
ece95912 2894 fsnotify_link_count(dentry->d_inode);
e234f35c 2895 d_delete(dentry);
1da177e4 2896 }
0eeca283 2897
1da177e4
LT		 2898 return error;
2899}
2900
2901/*
2902 * Make sure that the actual truncation of the file will occur outside its
1b1dcc1b 2903 * directory's i_mutex. Truncate can take a long time if there is a lot of
1da177e4
LT		 2904 * writeout happening, and we don't want to prevent access to the directory
2905 * while waiting on the I/O.
2906 */
5590ff0d 2907static long do_unlinkat(int dfd, const char __user *pathname)
1da177e4 2908{
2ad94ae6
AV		 2909 int error;
2910 char *name;
1da177e4
LT		 2911 struct dentry *dentry;
2912 struct nameidata nd;
2913 struct inode *inode = NULL;
2914
2ad94ae6 2915 error = user_path_parent(dfd, pathname, &nd, &name);
1da177e4 2916 if (error)
2ad94ae6
AV		 2917 return error;
2918
1da177e4
LT		 2919 error = -EISDIR;
2920 if (nd.last_type != LAST_NORM)
2921 goto exit1;
0612d9fb
OH		 2922
2923 nd.flags &= ~LOOKUP_PARENT;
2924
4ac91378 2925 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
49705b77 2926 dentry = lookup_hash(&nd);
1da177e4
LT		 2927 error = PTR_ERR(dentry);
2928 if (!IS_ERR(dentry)) {
2929 /* Why not before? Because we want correct error value */
50338b88
TE		 2930 if (nd.last.name[nd.last.len])
2931 goto slashes;
1da177e4 2932 inode = dentry->d_inode;
50338b88 2933 if (!inode)
e6bc45d6
TT		 2934 goto slashes;
2935 ihold(inode);
0622753b
DH		 2936 error = mnt_want_write(nd.path.mnt);
2937 if (error)
2938 goto exit2;
be6d3e56
KT		 2939 error = security_path_unlink(&nd.path, dentry);
2940 if (error)
2941 goto exit3;
4ac91378 2942 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
be6d3e56 2943exit3:
0622753b 2944 mnt_drop_write(nd.path.mnt);
1da177e4
LT		 2945 exit2:
2946 dput(dentry);
2947 }
4ac91378 2948 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
1da177e4
LT		 2949 if (inode)
2950 iput(inode); /* truncate the inode here */
2951exit1:
1d957f9b 2952 path_put(&nd.path);
1da177e4
LT		 2953 putname(name);
2954 return error;
2955
2956slashes:
2957 error = !dentry->d_inode ? -ENOENT :
2958 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2959 goto exit2;
2960}
2961
2e4d0924 2962SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
5590ff0d
UD		 2963{
2964 if ((flag & ~AT_REMOVEDIR) != 0)
2965 return -EINVAL;
2966
2967 if (flag & AT_REMOVEDIR)
2968 return do_rmdir(dfd, pathname);
2969
2970 return do_unlinkat(dfd, pathname);
2971}
2972
3480b257 2973SYSCALL_DEFINE1(unlink, const char __user *, pathname)
5590ff0d
UD		 2974{
2975 return do_unlinkat(AT_FDCWD, pathname);
2976}
2977
db2e747b 2978int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
1da177e4 2979{
a95164d9 2980 int error = may_create(dir, dentry);
1da177e4
LT		 2981
2982 if (error)
2983 return error;
2984
acfa4380 2985 if (!dir->i_op->symlink)
1da177e4
LT		 2986 return -EPERM;
2987
2988 error = security_inode_symlink(dir, dentry, oldname);
2989 if (error)
2990 return error;
2991
1da177e4 2992 error = dir->i_op->symlink(dir, dentry, oldname);
a74574aa 2993 if (!error)
f38aa942 2994 fsnotify_create(dir, dentry);
1da177e4
LT		 2995 return error;
2996}
2997
2e4d0924
HC		 2998SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2999 int, newdfd, const char __user *, newname)
1da177e4 3000{
2ad94ae6
AV		 3001 int error;
3002 char *from;
6902d925 3003 struct dentry *dentry;
dae6ad8f 3004 struct path path;
1da177e4
LT		 3005
3006 from = getname(oldname);
2ad94ae6 3007 if (IS_ERR(from))
1da177e4 3008 return PTR_ERR(from);
1da177e4 3009
dae6ad8f 3010 dentry = user_path_create(newdfd, newname, &path, 0);
6902d925
DH		 3011 error = PTR_ERR(dentry);
3012 if (IS_ERR(dentry))
dae6ad8f 3013 goto out_putname;
6902d925 3014
dae6ad8f 3015 error = mnt_want_write(path.mnt);
75c3f29d
DH		 3016 if (error)
3017 goto out_dput;
dae6ad8f 3018 error = security_path_symlink(&path, dentry, from);
be6d3e56
KT		 3019 if (error)
3020 goto out_drop_write;
dae6ad8f 3021 error = vfs_symlink(path.dentry->d_inode, dentry, from);
be6d3e56 3022out_drop_write:
dae6ad8f 3023 mnt_drop_write(path.mnt);
75c3f29d 3024out_dput:
6902d925 3025 dput(dentry);
dae6ad8f
AV		 3026 mutex_unlock(&path.dentry->d_inode->i_mutex);
3027 path_put(&path);
6902d925 3028out_putname:
1da177e4
LT		 3029 putname(from);
3030 return error;
3031}
3032
3480b257 3033SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
5590ff0d
UD		 3034{
3035 return sys_symlinkat(oldname, AT_FDCWD, newname);
3036}
3037
1da177e4
LT		 3038int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
3039{
3040 struct inode *inode = old_dentry->d_inode;
8de52778 3041 unsigned max_links = dir->i_sb->s_max_links;
1da177e4
LT		 3042 int error;
3043
3044 if (!inode)
3045 return -ENOENT;
3046
a95164d9 3047 error = may_create(dir, new_dentry);
1da177e4
LT		 3048 if (error)
3049 return error;
3050
3051 if (dir->i_sb != inode->i_sb)
3052 return -EXDEV;
3053
3054 /*
3055 * A link to an append-only or immutable file cannot be created.
3056 */
3057 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
3058 return -EPERM;
acfa4380 3059 if (!dir->i_op->link)
1da177e4 3060 return -EPERM;
7e79eedb 3061 if (S_ISDIR(inode->i_mode))
1da177e4
LT		 3062 return -EPERM;
3063
3064 error = security_inode_link(old_dentry, dir, new_dentry);
3065 if (error)
3066 return error;
3067
7e79eedb 3068 mutex_lock(&inode->i_mutex);
aae8a97d
AK		 3069 /* Make sure we don't allow creating hardlink to an unlinked file */
3070 if (inode->i_nlink == 0)
3071 error = -ENOENT;
8de52778
AV		 3072 else if (max_links && inode->i_nlink >= max_links)
3073 error = -EMLINK;
aae8a97d
AK		 3074 else
3075 error = dir->i_op->link(old_dentry, dir, new_dentry);
7e79eedb 3076 mutex_unlock(&inode->i_mutex);
e31e14ec 3077 if (!error)
7e79eedb 3078 fsnotify_link(dir, inode, new_dentry);
1da177e4
LT		 3079 return error;
3080}
3081
3082/*
3083 * Hardlinks are often used in delicate situations. We avoid
3084 * security-related surprises by not following symlinks on the
3085 * newname. --KAB
3086 *
3087 * We don't follow them on the oldname either to be compatible
3088 * with linux 2.0, and to avoid hard-linking to directories
3089 * and other special files. --ADM
3090 */
2e4d0924
HC		 3091SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
3092 int, newdfd, const char __user *, newname, int, flags)
1da177e4
LT		 3093{
3094 struct dentry *new_dentry;
dae6ad8f 3095 struct path old_path, new_path;
11a7b371 3096 int how = 0;
1da177e4 3097 int error;
1da177e4 3098
11a7b371 3099 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
c04030e1 3100 return -EINVAL;
11a7b371
AK		 3101 /*
3102 * To use null names we require CAP_DAC_READ_SEARCH
3103 * This ensures that not everyone will be able to create
3104 * handlink using the passed filedescriptor.
3105 */
3106 if (flags & AT_EMPTY_PATH) {
3107 if (!capable(CAP_DAC_READ_SEARCH))
3108 return -ENOENT;
3109 how = LOOKUP_EMPTY;
3110 }
3111
3112 if (flags & AT_SYMLINK_FOLLOW)
3113 how |= LOOKUP_FOLLOW;
c04030e1 3114
11a7b371 3115 error = user_path_at(olddfd, oldname, how, &old_path);
1da177e4 3116 if (error)
2ad94ae6
AV		 3117 return error;
3118
dae6ad8f 3119 new_dentry = user_path_create(newdfd, newname, &new_path, 0);
1da177e4 3120 error = PTR_ERR(new_dentry);
6902d925 3121 if (IS_ERR(new_dentry))
dae6ad8f
AV		 3122 goto out;
3123
3124 error = -EXDEV;
3125 if (old_path.mnt != new_path.mnt)
3126 goto out_dput;
3127 error = mnt_want_write(new_path.mnt);
75c3f29d
DH		 3128 if (error)
3129 goto out_dput;
dae6ad8f 3130 error = security_path_link(old_path.dentry, &new_path, new_dentry);
be6d3e56
KT		 3131 if (error)
3132 goto out_drop_write;
dae6ad8f 3133 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
be6d3e56 3134out_drop_write:
dae6ad8f 3135 mnt_drop_write(new_path.mnt);
75c3f29d 3136out_dput:
6902d925 3137 dput(new_dentry);
dae6ad8f
AV		 3138 mutex_unlock(&new_path.dentry->d_inode->i_mutex);
3139 path_put(&new_path);
1da177e4 3140out:
2d8f3038 3141 path_put(&old_path);
1da177e4
LT		 3142
3143 return error;
3144}
3145
3480b257 3146SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
5590ff0d 3147{
c04030e1 3148 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
5590ff0d
UD		 3149}
3150
1da177e4
LT		 3151/*
3152 * The worst of all namespace operations - renaming directory. "Perverted"
3153 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
3154 * Problems:
3155 * a) we can get into loop creation. Check is done in is_subdir().
3156 * b) race potential - two innocent renames can create a loop together.
3157 * That's where 4.4 screws up. Current fix: serialization on
a11f3a05 3158 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
1da177e4
LT		 3159 * story.
3160 * c) we have to lock _three_ objects - parents and victim (if it exists).
1b1dcc1b 3161 * And that - after we got ->i_mutex on parents (until then we don't know
1da177e4
LT		 3162 * whether the target exists). Solution: try to be smart with locking
3163 * order for inodes. We rely on the fact that tree topology may change
a11f3a05 3164 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
1da177e4
LT		 3165 * move will be locked. Thus we can rank directories by the tree
3166 * (ancestors first) and rank all non-directories after them.
3167 * That works since everybody except rename does "lock parent, lookup,
a11f3a05 3168 * lock child" and rename is under ->s_vfs_rename_mutex.
1da177e4
LT		 3169 * HOWEVER, it relies on the assumption that any object with ->lookup()
3170 * has no more than 1 dentry. If "hybrid" objects will ever appear,
3171 * we'd better make sure that there's no link(2) for them.
e4eaac06 3172 * d) conversion from fhandle to dentry may come in the wrong moment - when
1b1dcc1b 3173 * we are removing the target. Solution: we will have to grab ->i_mutex
1da177e4 3174 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
c41b20e7 3175 * ->i_mutex on parents, which works but leads to some truly excessive
1da177e4
LT		 3176 * locking].
3177 */
75c96f85
AB		 3178static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
3179 struct inode *new_dir, struct dentry *new_dentry)
1da177e4
LT		 3180{
3181 int error = 0;
9055cba7 3182 struct inode *target = new_dentry->d_inode;
8de52778 3183 unsigned max_links = new_dir->i_sb->s_max_links;
1da177e4
LT		 3184
3185 /*
3186 * If we are going to change the parent - check write permissions,
3187 * we'll need to flip '..'.
3188 */
3189 if (new_dir != old_dir) {
f419a2e3 3190 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
1da177e4
LT		 3191 if (error)
3192 return error;
3193 }
3194
3195 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3196 if (error)
3197 return error;
3198
1d2ef590 3199 dget(new_dentry);
d83c49f3 3200 if (target)
1b1dcc1b 3201 mutex_lock(&target->i_mutex);
9055cba7
SW		 3202
3203 error = -EBUSY;
3204 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
3205 goto out;
3206
8de52778
AV		 3207 error = -EMLINK;
3208 if (max_links && !target && new_dir != old_dir &&
3209 new_dir->i_nlink >= max_links)
3210 goto out;
3211
3cebde24
SW		 3212 if (target)
3213 shrink_dcache_parent(new_dentry);
9055cba7
SW		 3214 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3215 if (error)
3216 goto out;
3217
1da177e4 3218 if (target) {
9055cba7
SW		 3219 target->i_flags |= S_DEAD;
3220 dont_mount(new_dentry);
1da177e4 3221 }
9055cba7
SW		 3222out:
3223 if (target)
3224 mutex_unlock(&target->i_mutex);
1d2ef590 3225 dput(new_dentry);
e31e14ec 3226 if (!error)
349457cc
MF		 3227 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3228 d_move(old_dentry,new_dentry);
1da177e4
LT		 3229 return error;
3230}
3231
75c96f85
AB		 3232static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
3233 struct inode *new_dir, struct dentry *new_dentry)
1da177e4 3234{
51892bbb 3235 struct inode *target = new_dentry->d_inode;
1da177e4
LT		 3236 int error;
3237
3238 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3239 if (error)
3240 return error;
3241
3242 dget(new_dentry);
1da177e4 3243 if (target)
1b1dcc1b 3244 mutex_lock(&target->i_mutex);
51892bbb
SW		 3245
3246 error = -EBUSY;
1da177e4 3247 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
51892bbb
SW		 3248 goto out;
3249
3250 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3251 if (error)
3252 goto out;
3253
3254 if (target)
3255 dont_mount(new_dentry);
3256 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3257 d_move(old_dentry, new_dentry);
3258out:
1da177e4 3259 if (target)
1b1dcc1b 3260 mutex_unlock(&target->i_mutex);
1da177e4
LT		 3261 dput(new_dentry);
3262 return error;
3263}
3264
3265int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3266 struct inode *new_dir, struct dentry *new_dentry)
3267{
3268 int error;
3269 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
59b0df21 3270 const unsigned char *old_name;
1da177e4
LT		 3271
3272 if (old_dentry->d_inode == new_dentry->d_inode)
3273 return 0;
3274
3275 error = may_delete(old_dir, old_dentry, is_dir);
3276 if (error)
3277 return error;
3278
3279 if (!new_dentry->d_inode)
a95164d9 3280 error = may_create(new_dir, new_dentry);
1da177e4
LT		 3281 else
3282 error = may_delete(new_dir, new_dentry, is_dir);
3283 if (error)
3284 return error;
3285
acfa4380 3286 if (!old_dir->i_op->rename)
1da177e4
LT		 3287 return -EPERM;
3288
0eeca283
RL		 3289 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3290
1da177e4
LT		 3291 if (is_dir)
3292 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3293 else
3294 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
123df294
AV		 3295 if (!error)
3296 fsnotify_move(old_dir, new_dir, old_name, is_dir,
5a190ae6 3297 new_dentry->d_inode, old_dentry);
0eeca283
RL		 3298 fsnotify_oldname_free(old_name);
3299
1da177e4
LT		 3300 return error;
3301}
3302
2e4d0924
HC		 3303SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3304 int, newdfd, const char __user *, newname)
1da177e4 3305{
2ad94ae6
AV		 3306 struct dentry *old_dir, *new_dir;
3307 struct dentry *old_dentry, *new_dentry;
3308 struct dentry *trap;
1da177e4 3309 struct nameidata oldnd, newnd;
2ad94ae6
AV		 3310 char *from;
3311 char *to;
3312 int error;
1da177e4 3313
2ad94ae6 3314 error = user_path_parent(olddfd, oldname, &oldnd, &from);
1da177e4
LT		 3315 if (error)
3316 goto exit;
3317
2ad94ae6 3318 error = user_path_parent(newdfd, newname, &newnd, &to);
1da177e4
LT		 3319 if (error)
3320 goto exit1;
3321
3322 error = -EXDEV;
4ac91378 3323 if (oldnd.path.mnt != newnd.path.mnt)
1da177e4
LT		 3324 goto exit2;
3325
4ac91378 3326 old_dir = oldnd.path.dentry;
1da177e4
LT		 3327 error = -EBUSY;
3328 if (oldnd.last_type != LAST_NORM)
3329 goto exit2;
3330
4ac91378 3331 new_dir = newnd.path.dentry;
1da177e4
LT		 3332 if (newnd.last_type != LAST_NORM)
3333 goto exit2;
3334
0612d9fb
OH		 3335 oldnd.flags &= ~LOOKUP_PARENT;
3336 newnd.flags &= ~LOOKUP_PARENT;
4e9ed2f8 3337 newnd.flags |= LOOKUP_RENAME_TARGET;
0612d9fb 3338
1da177e4
LT		 3339 trap = lock_rename(new_dir, old_dir);
3340
49705b77 3341 old_dentry = lookup_hash(&oldnd);
1da177e4
LT		 3342 error = PTR_ERR(old_dentry);
3343 if (IS_ERR(old_dentry))
3344 goto exit3;
3345 /* source must exist */
3346 error = -ENOENT;
3347 if (!old_dentry->d_inode)
3348 goto exit4;
3349 /* unless the source is a directory trailing slashes give -ENOTDIR */
3350 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3351 error = -ENOTDIR;
3352 if (oldnd.last.name[oldnd.last.len])
3353 goto exit4;
3354 if (newnd.last.name[newnd.last.len])
3355 goto exit4;
3356 }
3357 /* source should not be ancestor of target */
3358 error = -EINVAL;
3359 if (old_dentry == trap)
3360 goto exit4;
49705b77 3361 new_dentry = lookup_hash(&newnd);
1da177e4
LT		 3362 error = PTR_ERR(new_dentry);
3363 if (IS_ERR(new_dentry))
3364 goto exit4;
3365 /* target should not be an ancestor of source */
3366 error = -ENOTEMPTY;
3367 if (new_dentry == trap)
3368 goto exit5;
3369
9079b1eb
DH		 3370 error = mnt_want_write(oldnd.path.mnt);
3371 if (error)
3372 goto exit5;
be6d3e56
KT		 3373 error = security_path_rename(&oldnd.path, old_dentry,
3374 &newnd.path, new_dentry);
3375 if (error)
3376 goto exit6;
1da177e4
LT		 3377 error = vfs_rename(old_dir->d_inode, old_dentry,
3378 new_dir->d_inode, new_dentry);
be6d3e56 3379exit6:
9079b1eb 3380 mnt_drop_write(oldnd.path.mnt);
1da177e4
LT		 3381exit5:
3382 dput(new_dentry);
3383exit4:
3384 dput(old_dentry);
3385exit3:
3386 unlock_rename(new_dir, old_dir);
3387exit2:
1d957f9b 3388 path_put(&newnd.path);
2ad94ae6 3389 putname(to);
1da177e4 3390exit1:
1d957f9b 3391 path_put(&oldnd.path);
1da177e4 3392 putname(from);
2ad94ae6 3393exit:
1da177e4
LT		 3394 return error;
3395}
3396
a26eab24 3397SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
5590ff0d
UD		 3398{
3399 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3400}
3401
1da177e4
LT		 3402int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3403{
3404 int len;
3405
3406 len = PTR_ERR(link);
3407 if (IS_ERR(link))
3408 goto out;
3409
3410 len = strlen(link);
3411 if (len > (unsigned) buflen)
3412 len = buflen;
3413 if (copy_to_user(buffer, link, len))
3414 len = -EFAULT;
3415out:
3416 return len;
3417}
3418
3419/*
3420 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3421 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3422 * using) it for any given inode is up to filesystem.
3423 */
3424int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3425{
3426 struct nameidata nd;
cc314eef 3427 void *cookie;
694a1764 3428 int res;
cc314eef 3429
1da177e4 3430 nd.depth = 0;
cc314eef 3431 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
694a1764
MS		 3432 if (IS_ERR(cookie))
3433 return PTR_ERR(cookie);
3434
3435 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3436 if (dentry->d_inode->i_op->put_link)
3437 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3438 return res;
1da177e4
LT		 3439}
3440
3441int vfs_follow_link(struct nameidata *nd, const char *link)
3442{
3443 return __vfs_follow_link(nd, link);
3444}
3445
3446/* get the link contents into pagecache */
3447static char *page_getlink(struct dentry * dentry, struct page **ppage)
3448{
ebd09abb
DG		 3449 char *kaddr;
3450 struct page *page;
1da177e4 3451 struct address_space *mapping = dentry->d_inode->i_mapping;
090d2b18 3452 page = read_mapping_page(mapping, 0, NULL);
1da177e4 3453 if (IS_ERR(page))
6fe6900e 3454 return (char*)page;
1da177e4 3455 *ppage = page;
ebd09abb
DG		 3456 kaddr = kmap(page);
3457 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3458 return kaddr;
1da177e4
LT		 3459}
3460
3461int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3462{
3463 struct page *page = NULL;
3464 char *s = page_getlink(dentry, &page);
3465 int res = vfs_readlink(dentry,buffer,buflen,s);
3466 if (page) {
3467 kunmap(page);
3468 page_cache_release(page);
3469 }
3470 return res;
3471}
3472
cc314eef 3473void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
1da177e4 3474{
cc314eef 3475 struct page *page = NULL;
1da177e4 3476 nd_set_link(nd, page_getlink(dentry, &page));
cc314eef 3477 return page;
1da177e4
LT		 3478}
3479
cc314eef 3480void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1da177e4 3481{
cc314eef
LT		 3482 struct page *page = cookie;
3483
3484 if (page) {
1da177e4
LT		 3485 kunmap(page);
3486 page_cache_release(page);
1da177e4
LT		 3487 }
3488}
3489
54566b2c
NP		 3490/*
3491 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3492 */
3493int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
1da177e4
LT		 3494{
3495 struct address_space *mapping = inode->i_mapping;
0adb25d2 3496 struct page *page;
afddba49 3497 void *fsdata;
beb497ab 3498 int err;
1da177e4 3499 char *kaddr;
54566b2c
NP		 3500 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3501 if (nofs)
3502 flags |= AOP_FLAG_NOFS;
1da177e4 3503
7e53cac4 3504retry:
afddba49 3505 err = pagecache_write_begin(NULL, mapping, 0, len-1,
54566b2c 3506 flags, &page, &fsdata);
1da177e4 3507 if (err)
afddba49
NP		 3508 goto fail;
3509
e8e3c3d6 3510 kaddr = kmap_atomic(page);
1da177e4 3511 memcpy(kaddr, symname, len-1);
e8e3c3d6 3512 kunmap_atomic(kaddr);
afddba49
NP		 3513
3514 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3515 page, fsdata);
1da177e4
LT		 3516 if (err < 0)
3517 goto fail;
afddba49
NP		 3518 if (err < len-1)
3519 goto retry;
3520
1da177e4
LT		 3521 mark_inode_dirty(inode);
3522 return 0;
1da177e4
LT		 3523fail:
3524 return err;
3525}
3526
0adb25d2
KK		 3527int page_symlink(struct inode *inode, const char *symname, int len)
3528{
3529 return __page_symlink(inode, symname, len,
54566b2c 3530 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
0adb25d2
KK		 3531}
3532
92e1d5be 3533const struct inode_operations page_symlink_inode_operations = {
1da177e4
LT		 3534 .readlink = generic_readlink,
3535 .follow_link = page_follow_link_light,
3536 .put_link = page_put_link,
3537};
3538
2d8f3038 3539EXPORT_SYMBOL(user_path_at);
cc53ce53 3540EXPORT_SYMBOL(follow_down_one);
1da177e4
LT		 3541EXPORT_SYMBOL(follow_down);
3542EXPORT_SYMBOL(follow_up);
3543EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3544EXPORT_SYMBOL(getname);
3545EXPORT_SYMBOL(lock_rename);
1da177e4
LT		 3546EXPORT_SYMBOL(lookup_one_len);
3547EXPORT_SYMBOL(page_follow_link_light);
3548EXPORT_SYMBOL(page_put_link);
3549EXPORT_SYMBOL(page_readlink);
0adb25d2 3550EXPORT_SYMBOL(__page_symlink);
1da177e4
LT		 3551EXPORT_SYMBOL(page_symlink);
3552EXPORT_SYMBOL(page_symlink_inode_operations);
d1811465 3553EXPORT_SYMBOL(kern_path);
16f18200 3554EXPORT_SYMBOL(vfs_path_lookup);
f419a2e3 3555EXPORT_SYMBOL(inode_permission);
1da177e4
LT		 3556EXPORT_SYMBOL(unlock_rename);
3557EXPORT_SYMBOL(vfs_create);
3558EXPORT_SYMBOL(vfs_follow_link);
3559EXPORT_SYMBOL(vfs_link);
3560EXPORT_SYMBOL(vfs_mkdir);
3561EXPORT_SYMBOL(vfs_mknod);
3562EXPORT_SYMBOL(generic_permission);
3563EXPORT_SYMBOL(vfs_readlink);
3564EXPORT_SYMBOL(vfs_rename);
3565EXPORT_SYMBOL(vfs_rmdir);
3566EXPORT_SYMBOL(vfs_symlink);
3567EXPORT_SYMBOL(vfs_unlink);
3568EXPORT_SYMBOL(dentry_unhash);
3569EXPORT_SYMBOL(generic_readlink);
kernel source for telekom puls (alcatel/mediatek)