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vfs: renumber DCACHE_xyz flags, remove some stale ones
[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
EP		 38#include "internal.h"
39
1da177e4
LT		 40/* [Feb-1997 T. Schoebel-Theuer]
41 * Fundamental changes in the pathname lookup mechanisms (namei)
42 * were necessary because of omirr. The reason is that omirr needs
43 * to know the _real_ pathname, not the user-supplied one, in case
44 * of symlinks (and also when transname replacements occur).
45 *
46 * The new code replaces the old recursive symlink resolution with
47 * an iterative one (in case of non-nested symlink chains). It does
48 * this with calls to <fs>_follow_link().
49 * As a side effect, dir_namei(), _namei() and follow_link() are now
50 * replaced with a single function lookup_dentry() that can handle all
51 * the special cases of the former code.
52 *
53 * With the new dcache, the pathname is stored at each inode, at least as
54 * long as the refcount of the inode is positive. As a side effect, the
55 * size of the dcache depends on the inode cache and thus is dynamic.
56 *
57 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
58 * resolution to correspond with current state of the code.
59 *
60 * Note that the symlink resolution is not *completely* iterative.
61 * There is still a significant amount of tail- and mid- recursion in
62 * the algorithm. Also, note that <fs>_readlink() is not used in
63 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
64 * may return different results than <fs>_follow_link(). Many virtual
65 * filesystems (including /proc) exhibit this behavior.
66 */
67
68/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
69 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
70 * and the name already exists in form of a symlink, try to create the new
71 * name indicated by the symlink. The old code always complained that the
72 * name already exists, due to not following the symlink even if its target
73 * is nonexistent. The new semantics affects also mknod() and link() when
25985edc 74 * the name is a symlink pointing to a non-existent name.
1da177e4
LT		 75 *
76 * I don't know which semantics is the right one, since I have no access
77 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
78 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
79 * "old" one. Personally, I think the new semantics is much more logical.
80 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
81 * file does succeed in both HP-UX and SunOs, but not in Solaris
82 * and in the old Linux semantics.
83 */
84
85/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
86 * semantics. See the comments in "open_namei" and "do_link" below.
87 *
88 * [10-Sep-98 Alan Modra] Another symlink change.
89 */
90
91/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
92 * inside the path - always follow.
93 * in the last component in creation/removal/renaming - never follow.
94 * if LOOKUP_FOLLOW passed - follow.
95 * if the pathname has trailing slashes - follow.
96 * otherwise - don't follow.
97 * (applied in that order).
98 *
99 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
100 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
101 * During the 2.4 we need to fix the userland stuff depending on it -
102 * hopefully we will be able to get rid of that wart in 2.5. So far only
103 * XEmacs seems to be relying on it...
104 */
105/*
106 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
a11f3a05 107 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
1da177e4
LT		 108 * any extra contention...
109 */
110
111/* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
114 *
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
117 */
858119e1 118static int do_getname(const char __user *filename, char *page)
1da177e4
LT		 119{
120 int retval;
121 unsigned long len = PATH_MAX;
122
123 if (!segment_eq(get_fs(), KERNEL_DS)) {
124 if ((unsigned long) filename >= TASK_SIZE)
125 return -EFAULT;
126 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
127 len = TASK_SIZE - (unsigned long) filename;
128 }
129
130 retval = strncpy_from_user(page, filename, len);
131 if (retval > 0) {
132 if (retval < len)
133 return 0;
134 return -ENAMETOOLONG;
135 } else if (!retval)
136 retval = -ENOENT;
137 return retval;
138}
139
f52e0c11 140static char *getname_flags(const char __user * filename, int flags)
1da177e4
LT		 141{
142 char *tmp, *result;
143
144 result = ERR_PTR(-ENOMEM);
145 tmp = __getname();
146 if (tmp) {
147 int retval = do_getname(filename, tmp);
148
149 result = tmp;
150 if (retval < 0) {
f52e0c11
AV		 151 if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
152 __putname(tmp);
153 result = ERR_PTR(retval);
154 }
1da177e4
LT		 155 }
156 }
157 audit_getname(result);
158 return result;
159}
160
f52e0c11
AV		 161char *getname(const char __user * filename)
162{
163 return getname_flags(filename, 0);
164}
165
1da177e4
LT		 166#ifdef CONFIG_AUDITSYSCALL
167void putname(const char *name)
168{
5ac3a9c2 169 if (unlikely(!audit_dummy_context()))
1da177e4
LT		 170 audit_putname(name);
171 else
172 __putname(name);
173}
174EXPORT_SYMBOL(putname);
175#endif
176
e77819e5
LT		 177static int check_acl(struct inode *inode, int mask)
178{
84635d68 179#ifdef CONFIG_FS_POSIX_ACL
e77819e5
LT		 180 struct posix_acl *acl;
181
e77819e5 182 if (mask & MAY_NOT_BLOCK) {
3567866b
AV		 183 acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
184 if (!acl)
e77819e5 185 return -EAGAIN;
3567866b
AV		 186 /* no ->get_acl() calls in RCU mode... */
187 if (acl == ACL_NOT_CACHED)
188 return -ECHILD;
189 return posix_acl_permission(inode, acl, mask);
e77819e5
LT		 190 }
191
192 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
193
194 /*
4e34e719
CH		 195 * A filesystem can force a ACL callback by just never filling the
196 * ACL cache. But normally you'd fill the cache either at inode
197 * instantiation time, or on the first ->get_acl call.
e77819e5 198 *
4e34e719
CH		 199 * If the filesystem doesn't have a get_acl() function at all, we'll
200 * just create the negative cache entry.
e77819e5
LT		 201 */
202 if (acl == ACL_NOT_CACHED) {
4e34e719
CH		 203 if (inode->i_op->get_acl) {
204 acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
205 if (IS_ERR(acl))
206 return PTR_ERR(acl);
207 } else {
208 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
209 return -EAGAIN;
210 }
e77819e5
LT		 211 }
212
213 if (acl) {
214 int error = posix_acl_permission(inode, acl, mask);
215 posix_acl_release(acl);
216 return error;
217 }
84635d68 218#endif
e77819e5
LT		 219
220 return -EAGAIN;
221}
222
5909ccaa
LT		 223/*
224 * This does basic POSIX ACL permission checking
1da177e4 225 */
7e40145e 226static int acl_permission_check(struct inode *inode, int mask)
1da177e4 227{
26cf46be 228 unsigned int mode = inode->i_mode;
1da177e4 229
9c2c7039 230 mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
e6305c43 231
e795b717
SH		 232 if (current_user_ns() != inode_userns(inode))
233 goto other_perms;
234
14067ff5 235 if (likely(current_fsuid() == inode->i_uid))
1da177e4
LT		 236 mode >>= 6;
237 else {
e77819e5 238 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
7e40145e 239 int error = check_acl(inode, mask);
b74c79e9
NP		 240 if (error != -EAGAIN)
241 return error;
1da177e4
LT		 242 }
243
244 if (in_group_p(inode->i_gid))
245 mode >>= 3;
246 }
247
e795b717 248other_perms:
1da177e4
LT		 249 /*
250 * If the DACs are ok we don't need any capability check.
251 */
9c2c7039 252 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
1da177e4 253 return 0;
5909ccaa
LT		 254 return -EACCES;
255}
256
257/**
b74c79e9 258 * generic_permission - check for access rights on a Posix-like filesystem
5909ccaa
LT		 259 * @inode: inode to check access rights for
260 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
5909ccaa
LT		 261 *
262 * Used to check for read/write/execute permissions on a file.
263 * We use "fsuid" for this, letting us set arbitrary permissions
264 * for filesystem access without changing the "normal" uids which
b74c79e9
NP		 265 * are used for other things.
266 *
267 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
268 * request cannot be satisfied (eg. requires blocking or too much complexity).
269 * It would then be called again in ref-walk mode.
5909ccaa 270 */
2830ba7f 271int generic_permission(struct inode *inode, int mask)
5909ccaa
LT		 272{
273 int ret;
274
275 /*
276 * Do the basic POSIX ACL permission checks.
277 */
7e40145e 278 ret = acl_permission_check(inode, mask);
5909ccaa
LT		 279 if (ret != -EACCES)
280 return ret;
1da177e4 281
d594e7ec
AV		 282 if (S_ISDIR(inode->i_mode)) {
283 /* DACs are overridable for directories */
284 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
285 return 0;
286 if (!(mask & MAY_WRITE))
287 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
288 return 0;
289 return -EACCES;
290 }
1da177e4
LT		 291 /*
292 * Read/write DACs are always overridable.
d594e7ec
AV		 293 * Executable DACs are overridable when there is
294 * at least one exec bit set.
1da177e4 295 */
d594e7ec 296 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
e795b717 297 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
1da177e4
LT		 298 return 0;
299
300 /*
301 * Searching includes executable on directories, else just read.
302 */
7ea66001 303 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
d594e7ec 304 if (mask == MAY_READ)
e795b717 305 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
1da177e4
LT		 306 return 0;
307
308 return -EACCES;
309}
310
cb23beb5
CH		 311/**
312 * inode_permission - check for access rights to a given inode
313 * @inode: inode to check permission on
314 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
315 *
316 * Used to check for read/write/execute permissions on an inode.
317 * We use "fsuid" for this, letting us set arbitrary permissions
318 * for filesystem access without changing the "normal" uids which
319 * are used for other things.
320 */
f419a2e3 321int inode_permission(struct inode *inode, int mask)
1da177e4 322{
e6305c43 323 int retval;
1da177e4
LT		 324
325 if (mask & MAY_WRITE) {
22590e41 326 umode_t mode = inode->i_mode;
1da177e4
LT		 327
328 /*
329 * Nobody gets write access to a read-only fs.
330 */
331 if (IS_RDONLY(inode) &&
332 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
333 return -EROFS;
334
335 /*
336 * Nobody gets write access to an immutable file.
337 */
338 if (IS_IMMUTABLE(inode))
339 return -EACCES;
340 }
341
acfa4380 342 if (inode->i_op->permission)
10556cb2 343 retval = inode->i_op->permission(inode, mask);
f696a365 344 else
2830ba7f 345 retval = generic_permission(inode, mask);
f696a365 346
1da177e4
LT		 347 if (retval)
348 return retval;
349
08ce5f16
SH		 350 retval = devcgroup_inode_permission(inode, mask);
351 if (retval)
352 return retval;
353
d09ca739 354 return security_inode_permission(inode, mask);
1da177e4
LT		 355}
356
5dd784d0
JB		 357/**
358 * path_get - get a reference to a path
359 * @path: path to get the reference to
360 *
361 * Given a path increment the reference count to the dentry and the vfsmount.
362 */
363void path_get(struct path *path)
364{
365 mntget(path->mnt);
366 dget(path->dentry);
367}
368EXPORT_SYMBOL(path_get);
369
1d957f9b
JB		 370/**
371 * path_put - put a reference to a path
372 * @path: path to put the reference to
373 *
374 * Given a path decrement the reference count to the dentry and the vfsmount.
375 */
376void path_put(struct path *path)
1da177e4 377{
1d957f9b
JB		 378 dput(path->dentry);
379 mntput(path->mnt);
1da177e4 380}
1d957f9b 381EXPORT_SYMBOL(path_put);
1da177e4 382
19660af7 383/*
31e6b01f 384 * Path walking has 2 modes, rcu-walk and ref-walk (see
19660af7
AV		 385 * Documentation/filesystems/path-lookup.txt). In situations when we can't
386 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
387 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
388 * mode. Refcounts are grabbed at the last known good point before rcu-walk
389 * got stuck, so ref-walk may continue from there. If this is not successful
390 * (eg. a seqcount has changed), then failure is returned and it's up to caller
391 * to restart the path walk from the beginning in ref-walk mode.
31e6b01f 392 */
31e6b01f
NP		 393
394/**
19660af7
AV		 395 * unlazy_walk - try to switch to ref-walk mode.
396 * @nd: nameidata pathwalk data
397 * @dentry: child of nd->path.dentry or NULL
39191628 398 * Returns: 0 on success, -ECHILD on failure
31e6b01f 399 *
19660af7
AV		 400 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
401 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
402 * @nd or NULL. Must be called from rcu-walk context.
31e6b01f 403 */
19660af7 404static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
31e6b01f
NP		 405{
406 struct fs_struct *fs = current->fs;
407 struct dentry *parent = nd->path.dentry;
5b6ca027 408 int want_root = 0;
31e6b01f
NP		 409
410 BUG_ON(!(nd->flags & LOOKUP_RCU));
5b6ca027
AV		 411 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
412 want_root = 1;
31e6b01f
NP		 413 spin_lock(&fs->lock);
414 if (nd->root.mnt != fs->root.mnt ||
415 nd->root.dentry != fs->root.dentry)
416 goto err_root;
417 }
418 spin_lock(&parent->d_lock);
19660af7
AV		 419 if (!dentry) {
420 if (!__d_rcu_to_refcount(parent, nd->seq))
421 goto err_parent;
422 BUG_ON(nd->inode != parent->d_inode);
423 } else {
94c0d4ec
AV		 424 if (dentry->d_parent != parent)
425 goto err_parent;
19660af7
AV		 426 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
427 if (!__d_rcu_to_refcount(dentry, nd->seq))
428 goto err_child;
429 /*
430 * If the sequence check on the child dentry passed, then
431 * the child has not been removed from its parent. This
432 * means the parent dentry must be valid and able to take
433 * a reference at this point.
434 */
435 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
436 BUG_ON(!parent->d_count);
437 parent->d_count++;
438 spin_unlock(&dentry->d_lock);
439 }
31e6b01f 440 spin_unlock(&parent->d_lock);
5b6ca027 441 if (want_root) {
31e6b01f
NP		 442 path_get(&nd->root);
443 spin_unlock(&fs->lock);
444 }
445 mntget(nd->path.mnt);
446
447 rcu_read_unlock();
448 br_read_unlock(vfsmount_lock);
449 nd->flags &= ~LOOKUP_RCU;
450 return 0;
19660af7
AV		 451
452err_child:
31e6b01f 453 spin_unlock(&dentry->d_lock);
19660af7 454err_parent:
31e6b01f
NP		 455 spin_unlock(&parent->d_lock);
456err_root:
5b6ca027 457 if (want_root)
31e6b01f
NP		 458 spin_unlock(&fs->lock);
459 return -ECHILD;
460}
461
834f2a4a
TM		 462/**
463 * release_open_intent - free up open intent resources
464 * @nd: pointer to nameidata
465 */
466void release_open_intent(struct nameidata *nd)
467{
2dab5974
LT		 468 struct file *file = nd->intent.open.file;
469
470 if (file && !IS_ERR(file)) {
471 if (file->f_path.dentry == NULL)
472 put_filp(file);
473 else
474 fput(file);
475 }
834f2a4a
TM		 476}
477
f60aef7e 478static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
34286d66 479{
f60aef7e 480 return dentry->d_op->d_revalidate(dentry, nd);
34286d66
NP		 481}
482
9f1fafee
AV		 483/**
484 * complete_walk - successful completion of path walk
485 * @nd: pointer nameidata
39159de2 486 *
9f1fafee
AV		 487 * If we had been in RCU mode, drop out of it and legitimize nd->path.
488 * Revalidate the final result, unless we'd already done that during
489 * the path walk or the filesystem doesn't ask for it. Return 0 on
490 * success, -error on failure. In case of failure caller does not
491 * need to drop nd->path.
39159de2 492 */
9f1fafee 493static int complete_walk(struct nameidata *nd)
39159de2 494{
16c2cd71 495 struct dentry *dentry = nd->path.dentry;
39159de2 496 int status;
39159de2 497
9f1fafee
AV		 498 if (nd->flags & LOOKUP_RCU) {
499 nd->flags &= ~LOOKUP_RCU;
500 if (!(nd->flags & LOOKUP_ROOT))
501 nd->root.mnt = NULL;
502 spin_lock(&dentry->d_lock);
503 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
504 spin_unlock(&dentry->d_lock);
505 rcu_read_unlock();
506 br_read_unlock(vfsmount_lock);
507 return -ECHILD;
508 }
509 BUG_ON(nd->inode != dentry->d_inode);
510 spin_unlock(&dentry->d_lock);
511 mntget(nd->path.mnt);
512 rcu_read_unlock();
513 br_read_unlock(vfsmount_lock);
514 }
515
16c2cd71
AV		 516 if (likely(!(nd->flags & LOOKUP_JUMPED)))
517 return 0;
518
519 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
39159de2
JL		 520 return 0;
521
16c2cd71
AV		 522 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
523 return 0;
524
525 /* Note: we do not d_invalidate() */
34286d66 526 status = d_revalidate(dentry, nd);
39159de2
JL		 527 if (status > 0)
528 return 0;
529
16c2cd71 530 if (!status)
39159de2 531 status = -ESTALE;
16c2cd71 532
9f1fafee 533 path_put(&nd->path);
39159de2
JL		 534 return status;
535}
536
2a737871
AV		 537static __always_inline void set_root(struct nameidata *nd)
538{
f7ad3c6b
MS		 539 if (!nd->root.mnt)
540 get_fs_root(current->fs, &nd->root);
2a737871
AV		 541}
542
6de88d72
AV		 543static int link_path_walk(const char *, struct nameidata *);
544
31e6b01f
NP		 545static __always_inline void set_root_rcu(struct nameidata *nd)
546{
547 if (!nd->root.mnt) {
548 struct fs_struct *fs = current->fs;
c28cc364
NP		 549 unsigned seq;
550
551 do {
552 seq = read_seqcount_begin(&fs->seq);
553 nd->root = fs->root;
c1530019 554 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
c28cc364 555 } while (read_seqcount_retry(&fs->seq, seq));
31e6b01f
NP		 556 }
557}
558
f1662356 559static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
1da177e4 560{
31e6b01f
NP		 561 int ret;
562
1da177e4
LT		 563 if (IS_ERR(link))
564 goto fail;
565
566 if (*link == '/') {
2a737871 567 set_root(nd);
1d957f9b 568 path_put(&nd->path);
2a737871
AV		 569 nd->path = nd->root;
570 path_get(&nd->root);
16c2cd71 571 nd->flags |= LOOKUP_JUMPED;
1da177e4 572 }
31e6b01f 573 nd->inode = nd->path.dentry->d_inode;
b4091d5f 574
31e6b01f
NP		 575 ret = link_path_walk(link, nd);
576 return ret;
1da177e4 577fail:
1d957f9b 578 path_put(&nd->path);
1da177e4
LT		 579 return PTR_ERR(link);
580}
581
1d957f9b 582static void path_put_conditional(struct path *path, struct nameidata *nd)
051d3812
IK		 583{
584 dput(path->dentry);
4ac91378 585 if (path->mnt != nd->path.mnt)
051d3812
IK		 586 mntput(path->mnt);
587}
588
7b9337aa
NP		 589static inline void path_to_nameidata(const struct path *path,
590 struct nameidata *nd)
051d3812 591{
31e6b01f
NP		 592 if (!(nd->flags & LOOKUP_RCU)) {
593 dput(nd->path.dentry);
594 if (nd->path.mnt != path->mnt)
595 mntput(nd->path.mnt);
9a229683 596 }
31e6b01f 597 nd->path.mnt = path->mnt;
4ac91378 598 nd->path.dentry = path->dentry;
051d3812
IK		 599}
600
574197e0
AV		 601static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
602{
603 struct inode *inode = link->dentry->d_inode;
604 if (!IS_ERR(cookie) && inode->i_op->put_link)
605 inode->i_op->put_link(link->dentry, nd, cookie);
606 path_put(link);
607}
608
def4af30 609static __always_inline int
574197e0 610follow_link(struct path *link, struct nameidata *nd, void **p)
1da177e4
LT		 611{
612 int error;
7b9337aa 613 struct dentry *dentry = link->dentry;
1da177e4 614
844a3917
AV		 615 BUG_ON(nd->flags & LOOKUP_RCU);
616
0e794589
AV		 617 if (link->mnt == nd->path.mnt)
618 mntget(link->mnt);
619
574197e0
AV		 620 if (unlikely(current->total_link_count >= 40)) {
621 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
574197e0
AV		 622 path_put(&nd->path);
623 return -ELOOP;
624 }
625 cond_resched();
626 current->total_link_count++;
627
7b9337aa 628 touch_atime(link->mnt, dentry);
1da177e4 629 nd_set_link(nd, NULL);
cd4e91d3 630
36f3b4f6
AV		 631 error = security_inode_follow_link(link->dentry, nd);
632 if (error) {
633 *p = ERR_PTR(error); /* no ->put_link(), please */
634 path_put(&nd->path);
635 return error;
636 }
637
86acdca1 638 nd->last_type = LAST_BIND;
def4af30
AV		 639 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
640 error = PTR_ERR(*p);
641 if (!IS_ERR(*p)) {
1da177e4 642 char *s = nd_get_link(nd);
cc314eef 643 error = 0;
1da177e4
LT		 644 if (s)
645 error = __vfs_follow_link(nd, s);
bcda7652 646 else if (nd->last_type == LAST_BIND) {
16c2cd71 647 nd->flags |= LOOKUP_JUMPED;
b21041d0
AV		 648 nd->inode = nd->path.dentry->d_inode;
649 if (nd->inode->i_op->follow_link) {
bcda7652
AV		 650 /* stepped on a _really_ weird one */
651 path_put(&nd->path);
652 error = -ELOOP;
653 }
654 }
1da177e4 655 }
1da177e4
LT		 656 return error;
657}
658
31e6b01f
NP		 659static int follow_up_rcu(struct path *path)
660{
661 struct vfsmount *parent;
662 struct dentry *mountpoint;
663
664 parent = path->mnt->mnt_parent;
665 if (parent == path->mnt)
666 return 0;
667 mountpoint = path->mnt->mnt_mountpoint;
668 path->dentry = mountpoint;
669 path->mnt = parent;
670 return 1;
671}
672
bab77ebf 673int follow_up(struct path *path)
1da177e4
LT		 674{
675 struct vfsmount *parent;
676 struct dentry *mountpoint;
99b7db7b
NP		 677
678 br_read_lock(vfsmount_lock);
bab77ebf
AV		 679 parent = path->mnt->mnt_parent;
680 if (parent == path->mnt) {
99b7db7b 681 br_read_unlock(vfsmount_lock);
1da177e4
LT		 682 return 0;
683 }
684 mntget(parent);
bab77ebf 685 mountpoint = dget(path->mnt->mnt_mountpoint);
99b7db7b 686 br_read_unlock(vfsmount_lock);
bab77ebf
AV		 687 dput(path->dentry);
688 path->dentry = mountpoint;
689 mntput(path->mnt);
690 path->mnt = parent;
1da177e4
LT		 691 return 1;
692}
693
b5c84bf6 694/*
9875cf80
DH		 695 * Perform an automount
696 * - return -EISDIR to tell follow_managed() to stop and return the path we
697 * were called with.
1da177e4 698 */
9875cf80
DH		 699static int follow_automount(struct path *path, unsigned flags,
700 bool *need_mntput)
31e6b01f 701{
9875cf80 702 struct vfsmount *mnt;
ea5b778a 703 int err;
9875cf80
DH		 704
705 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
706 return -EREMOTE;
707
6f45b656
DH		 708 /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT
709 * and this is the terminal part of the path.
710 */
49084c3b 711 if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
6f45b656
DH		 712 return -EISDIR; /* we actually want to stop here */
713
5a30d8a2 714 /*
9875cf80
DH		 715 * We don't want to mount if someone's just doing a stat and they've
716 * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
717 * appended a '/' to the name.
718 */
5a30d8a2
DH		 719 if (!(flags & LOOKUP_FOLLOW)) {
720 /* We do, however, want to mount if someone wants to open or
721 * create a file of any type under the mountpoint, wants to
722 * traverse through the mountpoint or wants to open the mounted
723 * directory.
724 * Also, autofs may mark negative dentries as being automount
725 * points. These will need the attentions of the daemon to
726 * instantiate them before they can be used.
727 */
728 if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
729 LOOKUP_OPEN | LOOKUP_CREATE)) &&
730 path->dentry->d_inode)
731 return -EISDIR;
732 }
9875cf80
DH		 733 current->total_link_count++;
734 if (current->total_link_count >= 40)
735 return -ELOOP;
736
737 mnt = path->dentry->d_op->d_automount(path);
738 if (IS_ERR(mnt)) {
739 /*
740 * The filesystem is allowed to return -EISDIR here to indicate
741 * it doesn't want to automount. For instance, autofs would do
742 * this so that its userspace daemon can mount on this dentry.
743 *
744 * However, we can only permit this if it's a terminal point in
745 * the path being looked up; if it wasn't then the remainder of
746 * the path is inaccessible and we should say so.
747 */
49084c3b 748 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
9875cf80
DH		 749 return -EREMOTE;
750 return PTR_ERR(mnt);
31e6b01f 751 }
ea5b778a 752
9875cf80
DH		 753 if (!mnt) /* mount collision */
754 return 0;
31e6b01f 755
8aef1884
AV		 756 if (!*need_mntput) {
757 /* lock_mount() may release path->mnt on error */
758 mntget(path->mnt);
759 *need_mntput = true;
760 }
19a167af 761 err = finish_automount(mnt, path);
9875cf80 762
ea5b778a
DH		 763 switch (err) {
764 case -EBUSY:
765 /* Someone else made a mount here whilst we were busy */
19a167af 766 return 0;
ea5b778a 767 case 0:
8aef1884 768 path_put(path);
ea5b778a
DH		 769 path->mnt = mnt;
770 path->dentry = dget(mnt->mnt_root);
ea5b778a 771 return 0;
19a167af
AV		 772 default:
773 return err;
ea5b778a 774 }
19a167af 775
463ffb2e
AV		 776}
777
9875cf80
DH		 778/*
779 * Handle a dentry that is managed in some way.
cc53ce53 780 * - Flagged for transit management (autofs)
9875cf80
DH		 781 * - Flagged as mountpoint
782 * - Flagged as automount point
783 *
784 * This may only be called in refwalk mode.
785 *
786 * Serialization is taken care of in namespace.c
787 */
788static int follow_managed(struct path *path, unsigned flags)
1da177e4 789{
8aef1884 790 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
9875cf80
DH		 791 unsigned managed;
792 bool need_mntput = false;
8aef1884 793 int ret = 0;
9875cf80
DH		 794
795 /* Given that we're not holding a lock here, we retain the value in a
796 * local variable for each dentry as we look at it so that we don't see
797 * the components of that value change under us */
798 while (managed = ACCESS_ONCE(path->dentry->d_flags),
799 managed &= DCACHE_MANAGED_DENTRY,
800 unlikely(managed != 0)) {
cc53ce53
DH		 801 /* Allow the filesystem to manage the transit without i_mutex
802 * being held. */
803 if (managed & DCACHE_MANAGE_TRANSIT) {
804 BUG_ON(!path->dentry->d_op);
805 BUG_ON(!path->dentry->d_op->d_manage);
1aed3e42 806 ret = path->dentry->d_op->d_manage(path->dentry, false);
cc53ce53 807 if (ret < 0)
8aef1884 808 break;
cc53ce53
DH		 809 }
810
9875cf80
DH		 811 /* Transit to a mounted filesystem. */
812 if (managed & DCACHE_MOUNTED) {
813 struct vfsmount *mounted = lookup_mnt(path);
814 if (mounted) {
815 dput(path->dentry);
816 if (need_mntput)
817 mntput(path->mnt);
818 path->mnt = mounted;
819 path->dentry = dget(mounted->mnt_root);
820 need_mntput = true;
821 continue;
822 }
823
824 /* Something is mounted on this dentry in another
825 * namespace and/or whatever was mounted there in this
826 * namespace got unmounted before we managed to get the
827 * vfsmount_lock */
828 }
829
830 /* Handle an automount point */
831 if (managed & DCACHE_NEED_AUTOMOUNT) {
832 ret = follow_automount(path, flags, &need_mntput);
833 if (ret < 0)
8aef1884 834 break;
9875cf80
DH		 835 continue;
836 }
837
838 /* We didn't change the current path point */
839 break;
1da177e4 840 }
8aef1884
AV		 841
842 if (need_mntput && path->mnt == mnt)
843 mntput(path->mnt);
844 if (ret == -EISDIR)
845 ret = 0;
846 return ret;
1da177e4
LT		 847}
848
cc53ce53 849int follow_down_one(struct path *path)
1da177e4
LT		 850{
851 struct vfsmount *mounted;
852
1c755af4 853 mounted = lookup_mnt(path);
1da177e4 854 if (mounted) {
9393bd07
AV		 855 dput(path->dentry);
856 mntput(path->mnt);
857 path->mnt = mounted;
858 path->dentry = dget(mounted->mnt_root);
1da177e4
LT		 859 return 1;
860 }
861 return 0;
862}
863
62a7375e
IK		 864static inline bool managed_dentry_might_block(struct dentry *dentry)
865{
866 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
867 dentry->d_op->d_manage(dentry, true) < 0);
868}
869
9875cf80 870/*
287548e4
AV		 871 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
872 * we meet a managed dentry that would need blocking.
9875cf80
DH		 873 */
874static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
287548e4 875 struct inode **inode)
9875cf80 876{
62a7375e 877 for (;;) {
9875cf80 878 struct vfsmount *mounted;
62a7375e
IK		 879 /*
880 * Don't forget we might have a non-mountpoint managed dentry
881 * that wants to block transit.
882 */
287548e4 883 if (unlikely(managed_dentry_might_block(path->dentry)))
ab90911f 884 return false;
62a7375e
IK		 885
886 if (!d_mountpoint(path->dentry))
887 break;
888
9875cf80
DH		 889 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
890 if (!mounted)
891 break;
892 path->mnt = mounted;
893 path->dentry = mounted->mnt_root;
894 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
59430262
LT		 895 /*
896 * Update the inode too. We don't need to re-check the
897 * dentry sequence number here after this d_inode read,
898 * because a mount-point is always pinned.
899 */
900 *inode = path->dentry->d_inode;
9875cf80 901 }
9875cf80
DH		 902 return true;
903}
904
dea39376 905static void follow_mount_rcu(struct nameidata *nd)
287548e4 906{
dea39376 907 while (d_mountpoint(nd->path.dentry)) {
287548e4 908 struct vfsmount *mounted;
dea39376 909 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
287548e4
AV		 910 if (!mounted)
911 break;
dea39376
AV		 912 nd->path.mnt = mounted;
913 nd->path.dentry = mounted->mnt_root;
914 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
287548e4
AV		 915 }
916}
917
31e6b01f
NP		 918static int follow_dotdot_rcu(struct nameidata *nd)
919{
31e6b01f
NP		 920 set_root_rcu(nd);
921
9875cf80 922 while (1) {
31e6b01f
NP		 923 if (nd->path.dentry == nd->root.dentry &&
924 nd->path.mnt == nd->root.mnt) {
925 break;
926 }
927 if (nd->path.dentry != nd->path.mnt->mnt_root) {
928 struct dentry *old = nd->path.dentry;
929 struct dentry *parent = old->d_parent;
930 unsigned seq;
931
932 seq = read_seqcount_begin(&parent->d_seq);
933 if (read_seqcount_retry(&old->d_seq, nd->seq))
ef7562d5 934 goto failed;
31e6b01f
NP		 935 nd->path.dentry = parent;
936 nd->seq = seq;
937 break;
938 }
939 if (!follow_up_rcu(&nd->path))
940 break;
941 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
31e6b01f 942 }
dea39376
AV		 943 follow_mount_rcu(nd);
944 nd->inode = nd->path.dentry->d_inode;
31e6b01f 945 return 0;
ef7562d5
AV		 946
947failed:
948 nd->flags &= ~LOOKUP_RCU;
5b6ca027
AV		 949 if (!(nd->flags & LOOKUP_ROOT))
950 nd->root.mnt = NULL;
ef7562d5
AV		 951 rcu_read_unlock();
952 br_read_unlock(vfsmount_lock);
953 return -ECHILD;
31e6b01f
NP		 954}
955
cc53ce53
DH		 956/*
957 * Follow down to the covering mount currently visible to userspace. At each
958 * point, the filesystem owning that dentry may be queried as to whether the
959 * caller is permitted to proceed or not.
cc53ce53 960 */
7cc90cc3 961int follow_down(struct path *path)
cc53ce53
DH		 962{
963 unsigned managed;
964 int ret;
965
966 while (managed = ACCESS_ONCE(path->dentry->d_flags),
967 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
968 /* Allow the filesystem to manage the transit without i_mutex
969 * being held.
970 *
971 * We indicate to the filesystem if someone is trying to mount
972 * something here. This gives autofs the chance to deny anyone
973 * other than its daemon the right to mount on its
974 * superstructure.
975 *
976 * The filesystem may sleep at this point.
977 */
978 if (managed & DCACHE_MANAGE_TRANSIT) {
979 BUG_ON(!path->dentry->d_op);
980 BUG_ON(!path->dentry->d_op->d_manage);
ab90911f 981 ret = path->dentry->d_op->d_manage(
1aed3e42 982 path->dentry, false);
cc53ce53
DH		 983 if (ret < 0)
984 return ret == -EISDIR ? 0 : ret;
985 }
986
987 /* Transit to a mounted filesystem. */
988 if (managed & DCACHE_MOUNTED) {
989 struct vfsmount *mounted = lookup_mnt(path);
990 if (!mounted)
991 break;
992 dput(path->dentry);
993 mntput(path->mnt);
994 path->mnt = mounted;
995 path->dentry = dget(mounted->mnt_root);
996 continue;
997 }
998
999 /* Don't handle automount points here */
1000 break;
1001 }
1002 return 0;
1003}
1004
9875cf80
DH		 1005/*
1006 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1007 */
1008static void follow_mount(struct path *path)
1009{
1010 while (d_mountpoint(path->dentry)) {
1011 struct vfsmount *mounted = lookup_mnt(path);
1012 if (!mounted)
1013 break;
1014 dput(path->dentry);
1015 mntput(path->mnt);
1016 path->mnt = mounted;
1017 path->dentry = dget(mounted->mnt_root);
1018 }
1019}
1020
31e6b01f 1021static void follow_dotdot(struct nameidata *nd)
1da177e4 1022{
2a737871 1023 set_root(nd);
e518ddb7 1024
1da177e4 1025 while(1) {
4ac91378 1026 struct dentry *old = nd->path.dentry;
1da177e4 1027
2a737871
AV		 1028 if (nd->path.dentry == nd->root.dentry &&
1029 nd->path.mnt == nd->root.mnt) {
1da177e4
LT		 1030 break;
1031 }
4ac91378 1032 if (nd->path.dentry != nd->path.mnt->mnt_root) {
3088dd70
AV		 1033 /* rare case of legitimate dget_parent()... */
1034 nd->path.dentry = dget_parent(nd->path.dentry);
1da177e4
LT		 1035 dput(old);
1036 break;
1037 }
3088dd70 1038 if (!follow_up(&nd->path))
1da177e4 1039 break;
1da177e4 1040 }
79ed0226 1041 follow_mount(&nd->path);
31e6b01f 1042 nd->inode = nd->path.dentry->d_inode;
1da177e4
LT		 1043}
1044
baa03890
NP		 1045/*
1046 * Allocate a dentry with name and parent, and perform a parent
1047 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
1048 * on error. parent->d_inode->i_mutex must be held. d_lookup must
1049 * have verified that no child exists while under i_mutex.
1050 */
1051static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1052 struct qstr *name, struct nameidata *nd)
1053{
1054 struct inode *inode = parent->d_inode;
1055 struct dentry *dentry;
1056 struct dentry *old;
1057
1058 /* Don't create child dentry for a dead directory. */
1059 if (unlikely(IS_DEADDIR(inode)))
1060 return ERR_PTR(-ENOENT);
1061
1062 dentry = d_alloc(parent, name);
1063 if (unlikely(!dentry))
1064 return ERR_PTR(-ENOMEM);
1065
1066 old = inode->i_op->lookup(inode, dentry, nd);
1067 if (unlikely(old)) {
1068 dput(dentry);
1069 dentry = old;
1070 }
1071 return dentry;
1072}
1073
44396f4b
JB		 1074/*
1075 * We already have a dentry, but require a lookup to be performed on the parent
1076 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1077 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1078 * child exists while under i_mutex.
1079 */
1080static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1081 struct nameidata *nd)
1082{
1083 struct inode *inode = parent->d_inode;
1084 struct dentry *old;
1085
1086 /* Don't create child dentry for a dead directory. */
1087 if (unlikely(IS_DEADDIR(inode)))
1088 return ERR_PTR(-ENOENT);
1089
1090 old = inode->i_op->lookup(inode, dentry, nd);
1091 if (unlikely(old)) {
1092 dput(dentry);
1093 dentry = old;
1094 }
1095 return dentry;
1096}
1097
1da177e4
LT		 1098/*
1099 * It's more convoluted than I'd like it to be, but... it's still fairly
1100 * small and for now I'd prefer to have fast path as straight as possible.
1101 * It _is_ time-critical.
1102 */
1103static int do_lookup(struct nameidata *nd, struct qstr *name,
31e6b01f 1104 struct path *path, struct inode **inode)
1da177e4 1105{
4ac91378 1106 struct vfsmount *mnt = nd->path.mnt;
31e6b01f 1107 struct dentry *dentry, *parent = nd->path.dentry;
5a18fff2
AV		 1108 int need_reval = 1;
1109 int status = 1;
9875cf80
DH		 1110 int err;
1111
b04f784e
NP		 1112 /*
1113 * Rename seqlock is not required here because in the off chance
1114 * of a false negative due to a concurrent rename, we're going to
1115 * do the non-racy lookup, below.
1116 */
31e6b01f
NP		 1117 if (nd->flags & LOOKUP_RCU) {
1118 unsigned seq;
31e6b01f
NP		 1119 *inode = nd->inode;
1120 dentry = __d_lookup_rcu(parent, name, &seq, inode);
5a18fff2
AV		 1121 if (!dentry)
1122 goto unlazy;
1123
31e6b01f
NP		 1124 /* Memory barrier in read_seqcount_begin of child is enough */
1125 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1126 return -ECHILD;
31e6b01f 1127 nd->seq = seq;
5a18fff2 1128
24643087 1129 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
5a18fff2
AV		 1130 status = d_revalidate(dentry, nd);
1131 if (unlikely(status <= 0)) {
1132 if (status != -ECHILD)
1133 need_reval = 0;
1134 goto unlazy;
1135 }
24643087 1136 }
44396f4b
JB		 1137 if (unlikely(d_need_lookup(dentry)))
1138 goto unlazy;
31e6b01f
NP		 1139 path->mnt = mnt;
1140 path->dentry = dentry;
d6e9bd25
AV		 1141 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1142 goto unlazy;
1143 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1144 goto unlazy;
1145 return 0;
5a18fff2 1146unlazy:
19660af7
AV		 1147 if (unlazy_walk(nd, dentry))
1148 return -ECHILD;
5a18fff2
AV		 1149 } else {
1150 dentry = __d_lookup(parent, name);
9875cf80 1151 }
5a18fff2 1152
44396f4b
JB		 1153 if (dentry && unlikely(d_need_lookup(dentry))) {
1154 dput(dentry);
1155 dentry = NULL;
1156 }
5a18fff2
AV		 1157retry:
1158 if (unlikely(!dentry)) {
1159 struct inode *dir = parent->d_inode;
1160 BUG_ON(nd->inode != dir);
1161
1162 mutex_lock(&dir->i_mutex);
1163 dentry = d_lookup(parent, name);
1164 if (likely(!dentry)) {
1165 dentry = d_alloc_and_lookup(parent, name, nd);
1166 if (IS_ERR(dentry)) {
1167 mutex_unlock(&dir->i_mutex);
1168 return PTR_ERR(dentry);
1169 }
1170 /* known good */
1171 need_reval = 0;
1172 status = 1;
44396f4b
JB		 1173 } else if (unlikely(d_need_lookup(dentry))) {
1174 dentry = d_inode_lookup(parent, dentry, nd);
1175 if (IS_ERR(dentry)) {
1176 mutex_unlock(&dir->i_mutex);
1177 return PTR_ERR(dentry);
1178 }
1179 /* known good */
1180 need_reval = 0;
1181 status = 1;
5a18fff2
AV		 1182 }
1183 mutex_unlock(&dir->i_mutex);
1184 }
1185 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1186 status = d_revalidate(dentry, nd);
1187 if (unlikely(status <= 0)) {
1188 if (status < 0) {
1189 dput(dentry);
1190 return status;
1191 }
1192 if (!d_invalidate(dentry)) {
1193 dput(dentry);
1194 dentry = NULL;
1195 need_reval = 1;
1196 goto retry;
1197 }
24643087 1198 }
5a18fff2 1199
9875cf80
DH		 1200 path->mnt = mnt;
1201 path->dentry = dentry;
1202 err = follow_managed(path, nd->flags);
89312214
IK		 1203 if (unlikely(err < 0)) {
1204 path_put_conditional(path, nd);
9875cf80 1205 return err;
89312214 1206 }
9875cf80 1207 *inode = path->dentry->d_inode;
1da177e4 1208 return 0;
1da177e4
LT		 1209}
1210
52094c8a
AV		 1211static inline int may_lookup(struct nameidata *nd)
1212{
1213 if (nd->flags & LOOKUP_RCU) {
4ad5abb3 1214 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
52094c8a
AV		 1215 if (err != -ECHILD)
1216 return err;
19660af7 1217 if (unlazy_walk(nd, NULL))
52094c8a
AV		 1218 return -ECHILD;
1219 }
4ad5abb3 1220 return inode_permission(nd->inode, MAY_EXEC);
52094c8a
AV		 1221}
1222
9856fa1b
AV		 1223static inline int handle_dots(struct nameidata *nd, int type)
1224{
1225 if (type == LAST_DOTDOT) {
1226 if (nd->flags & LOOKUP_RCU) {
1227 if (follow_dotdot_rcu(nd))
1228 return -ECHILD;
1229 } else
1230 follow_dotdot(nd);
1231 }
1232 return 0;
1233}
1234
951361f9
AV		 1235static void terminate_walk(struct nameidata *nd)
1236{
1237 if (!(nd->flags & LOOKUP_RCU)) {
1238 path_put(&nd->path);
1239 } else {
1240 nd->flags &= ~LOOKUP_RCU;
5b6ca027
AV		 1241 if (!(nd->flags & LOOKUP_ROOT))
1242 nd->root.mnt = NULL;
951361f9
AV		 1243 rcu_read_unlock();
1244 br_read_unlock(vfsmount_lock);
1245 }
1246}
1247
ce57dfc1
AV		 1248static inline int walk_component(struct nameidata *nd, struct path *path,
1249 struct qstr *name, int type, int follow)
1250{
1251 struct inode *inode;
1252 int err;
1253 /*
1254 * "." and ".." are special - ".." especially so because it has
1255 * to be able to know about the current root directory and
1256 * parent relationships.
1257 */
1258 if (unlikely(type != LAST_NORM))
1259 return handle_dots(nd, type);
1260 err = do_lookup(nd, name, path, &inode);
1261 if (unlikely(err)) {
1262 terminate_walk(nd);
1263 return err;
1264 }
1265 if (!inode) {
1266 path_to_nameidata(path, nd);
1267 terminate_walk(nd);
1268 return -ENOENT;
1269 }
1270 if (unlikely(inode->i_op->follow_link) && follow) {
19660af7
AV		 1271 if (nd->flags & LOOKUP_RCU) {
1272 if (unlikely(unlazy_walk(nd, path->dentry))) {
1273 terminate_walk(nd);
1274 return -ECHILD;
1275 }
1276 }
ce57dfc1
AV		 1277 BUG_ON(inode != path->dentry->d_inode);
1278 return 1;
1279 }
1280 path_to_nameidata(path, nd);
1281 nd->inode = inode;
1282 return 0;
1283}
1284
b356379a
AV		 1285/*
1286 * This limits recursive symlink follows to 8, while
1287 * limiting consecutive symlinks to 40.
1288 *
1289 * Without that kind of total limit, nasty chains of consecutive
1290 * symlinks can cause almost arbitrarily long lookups.
1291 */
1292static inline int nested_symlink(struct path *path, struct nameidata *nd)
1293{
1294 int res;
1295
b356379a
AV		 1296 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1297 path_put_conditional(path, nd);
1298 path_put(&nd->path);
1299 return -ELOOP;
1300 }
1a4022f8 1301 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
b356379a
AV		 1302
1303 nd->depth++;
1304 current->link_count++;
1305
1306 do {
1307 struct path link = *path;
1308 void *cookie;
574197e0
AV		 1309
1310 res = follow_link(&link, nd, &cookie);
b356379a
AV		 1311 if (!res)
1312 res = walk_component(nd, path, &nd->last,
1313 nd->last_type, LOOKUP_FOLLOW);
574197e0 1314 put_link(nd, &link, cookie);
b356379a
AV		 1315 } while (res > 0);
1316
1317 current->link_count--;
1318 nd->depth--;
1319 return res;
1320}
1321
1da177e4
LT		 1322/*
1323 * Name resolution.
ea3834d9
PM		 1324 * This is the basic name resolution function, turning a pathname into
1325 * the final dentry. We expect 'base' to be positive and a directory.
1da177e4 1326 *
ea3834d9
PM		 1327 * Returns 0 and nd will have valid dentry and mnt on success.
1328 * Returns error and drops reference to input namei data on failure.
1da177e4 1329 */
6de88d72 1330static int link_path_walk(const char *name, struct nameidata *nd)
1da177e4
LT		 1331{
1332 struct path next;
1da177e4 1333 int err;
1da177e4
LT		 1334
1335 while (*name=='/')
1336 name++;
1337 if (!*name)
086e183a 1338 return 0;
1da177e4 1339
1da177e4
LT		 1340 /* At this point we know we have a real path component. */
1341 for(;;) {
1342 unsigned long hash;
1343 struct qstr this;
1344 unsigned int c;
fe479a58 1345 int type;
1da177e4 1346
52094c8a 1347 err = may_lookup(nd);
1da177e4
LT		 1348 if (err)
1349 break;
1350
1351 this.name = name;
1352 c = *(const unsigned char *)name;
1353
1354 hash = init_name_hash();
1355 do {
1356 name++;
1357 hash = partial_name_hash(c, hash);
1358 c = *(const unsigned char *)name;
1359 } while (c && (c != '/'));
1360 this.len = name - (const char *) this.name;
1361 this.hash = end_name_hash(hash);
1362
fe479a58
AV		 1363 type = LAST_NORM;
1364 if (this.name[0] == '.') switch (this.len) {
1365 case 2:
16c2cd71 1366 if (this.name[1] == '.') {
fe479a58 1367 type = LAST_DOTDOT;
16c2cd71
AV		 1368 nd->flags |= LOOKUP_JUMPED;
1369 }
fe479a58
AV		 1370 break;
1371 case 1:
1372 type = LAST_DOT;
1373 }
5a202bcd
AV		 1374 if (likely(type == LAST_NORM)) {
1375 struct dentry *parent = nd->path.dentry;
16c2cd71 1376 nd->flags &= ~LOOKUP_JUMPED;
5a202bcd
AV		 1377 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1378 err = parent->d_op->d_hash(parent, nd->inode,
1379 &this);
1380 if (err < 0)
1381 break;
1382 }
1383 }
fe479a58 1384
1da177e4
LT		 1385 /* remove trailing slashes? */
1386 if (!c)
1387 goto last_component;
1388 while (*++name == '/');
1389 if (!*name)
b356379a 1390 goto last_component;
1da177e4 1391
ce57dfc1
AV		 1392 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1393 if (err < 0)
1394 return err;
1da177e4 1395
ce57dfc1 1396 if (err) {
b356379a 1397 err = nested_symlink(&next, nd);
1da177e4 1398 if (err)
a7472bab 1399 return err;
31e6b01f 1400 }
1da177e4 1401 err = -ENOTDIR;
31e6b01f 1402 if (!nd->inode->i_op->lookup)
1da177e4
LT		 1403 break;
1404 continue;
1405 /* here ends the main loop */
1406
1da177e4 1407last_component:
b356379a
AV		 1408 nd->last = this;
1409 nd->last_type = type;
086e183a 1410 return 0;
1da177e4 1411 }
951361f9 1412 terminate_walk(nd);
1da177e4
LT		 1413 return err;
1414}
1415
70e9b357
AV		 1416static int path_init(int dfd, const char *name, unsigned int flags,
1417 struct nameidata *nd, struct file **fp)
31e6b01f
NP		 1418{
1419 int retval = 0;
1420 int fput_needed;
1421 struct file *file;
1422
1423 nd->last_type = LAST_ROOT; /* if there are only slashes... */
16c2cd71 1424 nd->flags = flags | LOOKUP_JUMPED;
31e6b01f 1425 nd->depth = 0;
5b6ca027
AV		 1426 if (flags & LOOKUP_ROOT) {
1427 struct inode *inode = nd->root.dentry->d_inode;
73d049a4
AV		 1428 if (*name) {
1429 if (!inode->i_op->lookup)
1430 return -ENOTDIR;
1431 retval = inode_permission(inode, MAY_EXEC);
1432 if (retval)
1433 return retval;
1434 }
5b6ca027
AV		 1435 nd->path = nd->root;
1436 nd->inode = inode;
1437 if (flags & LOOKUP_RCU) {
1438 br_read_lock(vfsmount_lock);
1439 rcu_read_lock();
1440 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1441 } else {
1442 path_get(&nd->path);
1443 }
1444 return 0;
1445 }
1446
31e6b01f 1447 nd->root.mnt = NULL;
31e6b01f
NP		 1448
1449 if (*name=='/') {
e41f7d4e
AV		 1450 if (flags & LOOKUP_RCU) {
1451 br_read_lock(vfsmount_lock);
1452 rcu_read_lock();
1453 set_root_rcu(nd);
1454 } else {
1455 set_root(nd);
1456 path_get(&nd->root);
1457 }
1458 nd->path = nd->root;
31e6b01f 1459 } else if (dfd == AT_FDCWD) {
e41f7d4e
AV		 1460 if (flags & LOOKUP_RCU) {
1461 struct fs_struct *fs = current->fs;
1462 unsigned seq;
31e6b01f 1463
e41f7d4e
AV		 1464 br_read_lock(vfsmount_lock);
1465 rcu_read_lock();
c28cc364 1466
e41f7d4e
AV		 1467 do {
1468 seq = read_seqcount_begin(&fs->seq);
1469 nd->path = fs->pwd;
1470 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1471 } while (read_seqcount_retry(&fs->seq, seq));
1472 } else {
1473 get_fs_pwd(current->fs, &nd->path);
1474 }
31e6b01f
NP		 1475 } else {
1476 struct dentry *dentry;
1477
1abf0c71 1478 file = fget_raw_light(dfd, &fput_needed);
31e6b01f
NP		 1479 retval = -EBADF;
1480 if (!file)
1481 goto out_fail;
1482
1483 dentry = file->f_path.dentry;
1484
f52e0c11
AV		 1485 if (*name) {
1486 retval = -ENOTDIR;
1487 if (!S_ISDIR(dentry->d_inode->i_mode))
1488 goto fput_fail;
31e6b01f 1489
4ad5abb3 1490 retval = inode_permission(dentry->d_inode, MAY_EXEC);
f52e0c11
AV		 1491 if (retval)
1492 goto fput_fail;
1493 }
31e6b01f
NP		 1494
1495 nd->path = file->f_path;
e41f7d4e
AV		 1496 if (flags & LOOKUP_RCU) {
1497 if (fput_needed)
70e9b357 1498 *fp = file;
e41f7d4e
AV		 1499 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1500 br_read_lock(vfsmount_lock);
1501 rcu_read_lock();
1502 } else {
1503 path_get(&file->f_path);
1504 fput_light(file, fput_needed);
1505 }
31e6b01f 1506 }
31e6b01f 1507
31e6b01f 1508 nd->inode = nd->path.dentry->d_inode;
9b4a9b14 1509 return 0;
2dfdd266 1510
9b4a9b14
AV		 1511fput_fail:
1512 fput_light(file, fput_needed);
1513out_fail:
1514 return retval;
1515}
1516
bd92d7fe
AV		 1517static inline int lookup_last(struct nameidata *nd, struct path *path)
1518{
1519 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1520 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1521
1522 nd->flags &= ~LOOKUP_PARENT;
1523 return walk_component(nd, path, &nd->last, nd->last_type,
1524 nd->flags & LOOKUP_FOLLOW);
1525}
1526
9b4a9b14 1527/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
ee0827cd 1528static int path_lookupat(int dfd, const char *name,
9b4a9b14
AV		 1529 unsigned int flags, struct nameidata *nd)
1530{
70e9b357 1531 struct file *base = NULL;
bd92d7fe
AV		 1532 struct path path;
1533 int err;
31e6b01f
NP		 1534
1535 /*
1536 * Path walking is largely split up into 2 different synchronisation
1537 * schemes, rcu-walk and ref-walk (explained in
1538 * Documentation/filesystems/path-lookup.txt). These share much of the
1539 * path walk code, but some things particularly setup, cleanup, and
1540 * following mounts are sufficiently divergent that functions are
1541 * duplicated. Typically there is a function foo(), and its RCU
1542 * analogue, foo_rcu().
1543 *
1544 * -ECHILD is the error number of choice (just to avoid clashes) that
1545 * is returned if some aspect of an rcu-walk fails. Such an error must
1546 * be handled by restarting a traditional ref-walk (which will always
1547 * be able to complete).
1548 */
bd92d7fe 1549 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
ee0827cd 1550
bd92d7fe
AV		 1551 if (unlikely(err))
1552 return err;
ee0827cd
AV		 1553
1554 current->total_link_count = 0;
bd92d7fe
AV		 1555 err = link_path_walk(name, nd);
1556
1557 if (!err && !(flags & LOOKUP_PARENT)) {
bd92d7fe
AV		 1558 err = lookup_last(nd, &path);
1559 while (err > 0) {
1560 void *cookie;
1561 struct path link = path;
bd92d7fe 1562 nd->flags |= LOOKUP_PARENT;
574197e0 1563 err = follow_link(&link, nd, &cookie);
bd92d7fe
AV		 1564 if (!err)
1565 err = lookup_last(nd, &path);
574197e0 1566 put_link(nd, &link, cookie);
bd92d7fe
AV		 1567 }
1568 }
ee0827cd 1569
9f1fafee
AV		 1570 if (!err)
1571 err = complete_walk(nd);
bd92d7fe
AV		 1572
1573 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1574 if (!nd->inode->i_op->lookup) {
1575 path_put(&nd->path);
bd23a539 1576 err = -ENOTDIR;
bd92d7fe
AV		 1577 }
1578 }
16c2cd71 1579
70e9b357
AV		 1580 if (base)
1581 fput(base);
ee0827cd 1582
5b6ca027 1583 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
2a737871
AV		 1584 path_put(&nd->root);
1585 nd->root.mnt = NULL;
1586 }
bd92d7fe 1587 return err;
ee0827cd 1588}
31e6b01f 1589
ee0827cd
AV		 1590static int do_path_lookup(int dfd, const char *name,
1591 unsigned int flags, struct nameidata *nd)
1592{
1593 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1594 if (unlikely(retval == -ECHILD))
1595 retval = path_lookupat(dfd, name, flags, nd);
1596 if (unlikely(retval == -ESTALE))
1597 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
31e6b01f
NP		 1598
1599 if (likely(!retval)) {
1600 if (unlikely(!audit_dummy_context())) {
1601 if (nd->path.dentry && nd->inode)
1602 audit_inode(name, nd->path.dentry);
1603 }
1604 }
170aa3d0 1605 return retval;
1da177e4
LT		 1606}
1607
c9c6cac0 1608int kern_path_parent(const char *name, struct nameidata *nd)
5590ff0d 1609{
c9c6cac0 1610 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
5590ff0d
UD		 1611}
1612
d1811465
AV		 1613int kern_path(const char *name, unsigned int flags, struct path *path)
1614{
1615 struct nameidata nd;
1616 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1617 if (!res)
1618 *path = nd.path;
1619 return res;
1620}
1621
16f18200
JJS		 1622/**
1623 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1624 * @dentry: pointer to dentry of the base directory
1625 * @mnt: pointer to vfs mount of the base directory
1626 * @name: pointer to file name
1627 * @flags: lookup flags
e0a01249 1628 * @path: pointer to struct path to fill
16f18200
JJS		 1629 */
1630int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1631 const char *name, unsigned int flags,
e0a01249 1632 struct path *path)
16f18200 1633{
e0a01249
AV		 1634 struct nameidata nd;
1635 int err;
1636 nd.root.dentry = dentry;
1637 nd.root.mnt = mnt;
1638 BUG_ON(flags & LOOKUP_PARENT);
5b6ca027 1639 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
e0a01249
AV		 1640 err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
1641 if (!err)
1642 *path = nd.path;
1643 return err;
16f18200
JJS		 1644}
1645
eead1911
CH		 1646static struct dentry *__lookup_hash(struct qstr *name,
1647 struct dentry *base, struct nameidata *nd)
1da177e4 1648{
81fca444 1649 struct inode *inode = base->d_inode;
057f6c01 1650 struct dentry *dentry;
1da177e4
LT		 1651 int err;
1652
4ad5abb3 1653 err = inode_permission(inode, MAY_EXEC);
81fca444
CH		 1654 if (err)
1655 return ERR_PTR(err);
1da177e4 1656
b04f784e
NP		 1657 /*
1658 * Don't bother with __d_lookup: callers are for creat as
1659 * well as unlink, so a lot of the time it would cost
1660 * a double lookup.
6e6b1bd1 1661 */
b04f784e 1662 dentry = d_lookup(base, name);
6e6b1bd1 1663
44396f4b
JB		 1664 if (dentry && d_need_lookup(dentry)) {
1665 /*
1666 * __lookup_hash is called with the parent dir's i_mutex already
1667 * held, so we are good to go here.
1668 */
1669 dentry = d_inode_lookup(base, dentry, nd);
1670 if (IS_ERR(dentry))
1671 return dentry;
1672 }
1673
d2d9e9fb
AV		 1674 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1675 int status = d_revalidate(dentry, nd);
1676 if (unlikely(status <= 0)) {
1677 /*
1678 * The dentry failed validation.
1679 * If d_revalidate returned 0 attempt to invalidate
1680 * the dentry otherwise d_revalidate is asking us
1681 * to return a fail status.
1682 */
1683 if (status < 0) {
1684 dput(dentry);
1685 return ERR_PTR(status);
1686 } else if (!d_invalidate(dentry)) {
1687 dput(dentry);
1688 dentry = NULL;
1689 }
1690 }
1691 }
6e6b1bd1 1692
baa03890
NP		 1693 if (!dentry)
1694 dentry = d_alloc_and_lookup(base, name, nd);
5a202bcd 1695
1da177e4
LT		 1696 return dentry;
1697}
1698
057f6c01
JM		 1699/*
1700 * Restricted form of lookup. Doesn't follow links, single-component only,
1701 * needs parent already locked. Doesn't follow mounts.
1702 * SMP-safe.
1703 */
eead1911 1704static struct dentry *lookup_hash(struct nameidata *nd)
057f6c01 1705{
4ac91378 1706 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1da177e4
LT		 1707}
1708
eead1911 1709/**
a6b91919 1710 * lookup_one_len - filesystem helper to lookup single pathname component
eead1911
CH		 1711 * @name: pathname component to lookup
1712 * @base: base directory to lookup from
1713 * @len: maximum length @len should be interpreted to
1714 *
a6b91919
RD		 1715 * Note that this routine is purely a helper for filesystem usage and should
1716 * not be called by generic code. Also note that by using this function the
eead1911
CH		 1717 * nameidata argument is passed to the filesystem methods and a filesystem
1718 * using this helper needs to be prepared for that.
1719 */
057f6c01
JM		 1720struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1721{
057f6c01 1722 struct qstr this;
6a96ba54
AV		 1723 unsigned long hash;
1724 unsigned int c;
057f6c01 1725
2f9092e1
DW		 1726 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1727
6a96ba54
AV		 1728 this.name = name;
1729 this.len = len;
1730 if (!len)
1731 return ERR_PTR(-EACCES);
1732
1733 hash = init_name_hash();
1734 while (len--) {
1735 c = *(const unsigned char *)name++;
1736 if (c == '/' || c == '\0')
1737 return ERR_PTR(-EACCES);
1738 hash = partial_name_hash(c, hash);
1739 }
1740 this.hash = end_name_hash(hash);
5a202bcd
AV		 1741 /*
1742 * See if the low-level filesystem might want
1743 * to use its own hash..
1744 */
1745 if (base->d_flags & DCACHE_OP_HASH) {
1746 int err = base->d_op->d_hash(base, base->d_inode, &this);
1747 if (err < 0)
1748 return ERR_PTR(err);
1749 }
eead1911 1750
49705b77 1751 return __lookup_hash(&this, base, NULL);
057f6c01
JM		 1752}
1753
2d8f3038
AV		 1754int user_path_at(int dfd, const char __user *name, unsigned flags,
1755 struct path *path)
1da177e4 1756{
2d8f3038 1757 struct nameidata nd;
f52e0c11 1758 char *tmp = getname_flags(name, flags);
1da177e4 1759 int err = PTR_ERR(tmp);
1da177e4 1760 if (!IS_ERR(tmp)) {
2d8f3038
AV		 1761
1762 BUG_ON(flags & LOOKUP_PARENT);
1763
1764 err = do_path_lookup(dfd, tmp, flags, &nd);
1da177e4 1765 putname(tmp);
2d8f3038
AV		 1766 if (!err)
1767 *path = nd.path;
1da177e4
LT		 1768 }
1769 return err;
1770}
1771
2ad94ae6
AV		 1772static int user_path_parent(int dfd, const char __user *path,
1773 struct nameidata *nd, char **name)
1774{
1775 char *s = getname(path);
1776 int error;
1777
1778 if (IS_ERR(s))
1779 return PTR_ERR(s);
1780
1781 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1782 if (error)
1783 putname(s);
1784 else
1785 *name = s;
1786
1787 return error;
1788}
1789
1da177e4
LT		 1790/*
1791 * It's inline, so penalty for filesystems that don't use sticky bit is
1792 * minimal.
1793 */
1794static inline int check_sticky(struct inode *dir, struct inode *inode)
1795{
da9592ed
DH		 1796 uid_t fsuid = current_fsuid();
1797
1da177e4
LT		 1798 if (!(dir->i_mode & S_ISVTX))
1799 return 0;
e795b717
SH		 1800 if (current_user_ns() != inode_userns(inode))
1801 goto other_userns;
da9592ed 1802 if (inode->i_uid == fsuid)
1da177e4 1803 return 0;
da9592ed 1804 if (dir->i_uid == fsuid)
1da177e4 1805 return 0;
e795b717
SH		 1806
1807other_userns:
1808 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1da177e4
LT		 1809}
1810
1811/*
1812 * Check whether we can remove a link victim from directory dir, check
1813 * whether the type of victim is right.
1814 * 1. We can't do it if dir is read-only (done in permission())
1815 * 2. We should have write and exec permissions on dir
1816 * 3. We can't remove anything from append-only dir
1817 * 4. We can't do anything with immutable dir (done in permission())
1818 * 5. If the sticky bit on dir is set we should either
1819 * a. be owner of dir, or
1820 * b. be owner of victim, or
1821 * c. have CAP_FOWNER capability
1822 * 6. If the victim is append-only or immutable we can't do antyhing with
1823 * links pointing to it.
1824 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1825 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1826 * 9. We can't remove a root or mountpoint.
1827 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1828 * nfs_async_unlink().
1829 */
858119e1 1830static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1da177e4
LT		 1831{
1832 int error;
1833
1834 if (!victim->d_inode)
1835 return -ENOENT;
1836
1837 BUG_ON(victim->d_parent->d_inode != dir);
cccc6bba 1838 audit_inode_child(victim, dir);
1da177e4 1839
f419a2e3 1840 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT		 1841 if (error)
1842 return error;
1843 if (IS_APPEND(dir))
1844 return -EPERM;
1845 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
f9454548 1846 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1da177e4
LT		 1847 return -EPERM;
1848 if (isdir) {
1849 if (!S_ISDIR(victim->d_inode->i_mode))
1850 return -ENOTDIR;
1851 if (IS_ROOT(victim))
1852 return -EBUSY;
1853 } else if (S_ISDIR(victim->d_inode->i_mode))
1854 return -EISDIR;
1855 if (IS_DEADDIR(dir))
1856 return -ENOENT;
1857 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1858 return -EBUSY;
1859 return 0;
1860}
1861
1862/* Check whether we can create an object with dentry child in directory
1863 * dir.
1864 * 1. We can't do it if child already exists (open has special treatment for
1865 * this case, but since we are inlined it's OK)
1866 * 2. We can't do it if dir is read-only (done in permission())
1867 * 3. We should have write and exec permissions on dir
1868 * 4. We can't do it if dir is immutable (done in permission())
1869 */
a95164d9 1870static inline int may_create(struct inode *dir, struct dentry *child)
1da177e4
LT		 1871{
1872 if (child->d_inode)
1873 return -EEXIST;
1874 if (IS_DEADDIR(dir))
1875 return -ENOENT;
f419a2e3 1876 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT		 1877}
1878
1da177e4
LT		 1879/*
1880 * p1 and p2 should be directories on the same fs.
1881 */
1882struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1883{
1884 struct dentry *p;
1885
1886 if (p1 == p2) {
f2eace23 1887 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1da177e4
LT		 1888 return NULL;
1889 }
1890
a11f3a05 1891 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1da177e4 1892
e2761a11
OH		 1893 p = d_ancestor(p2, p1);
1894 if (p) {
1895 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1896 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1897 return p;
1da177e4
LT		 1898 }
1899
e2761a11
OH		 1900 p = d_ancestor(p1, p2);
1901 if (p) {
1902 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1903 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1904 return p;
1da177e4
LT		 1905 }
1906
f2eace23
IM		 1907 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1908 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1da177e4
LT		 1909 return NULL;
1910}
1911
1912void unlock_rename(struct dentry *p1, struct dentry *p2)
1913{
1b1dcc1b 1914 mutex_unlock(&p1->d_inode->i_mutex);
1da177e4 1915 if (p1 != p2) {
1b1dcc1b 1916 mutex_unlock(&p2->d_inode->i_mutex);
a11f3a05 1917 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1da177e4
LT		 1918 }
1919}
1920
1921int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1922 struct nameidata *nd)
1923{
a95164d9 1924 int error = may_create(dir, dentry);
1da177e4
LT		 1925
1926 if (error)
1927 return error;
1928
acfa4380 1929 if (!dir->i_op->create)
1da177e4
LT		 1930 return -EACCES; /* shouldn't it be ENOSYS? */
1931 mode &= S_IALLUGO;
1932 mode |= S_IFREG;
1933 error = security_inode_create(dir, dentry, mode);
1934 if (error)
1935 return error;
1da177e4 1936 error = dir->i_op->create(dir, dentry, mode, nd);
a74574aa 1937 if (!error)
f38aa942 1938 fsnotify_create(dir, dentry);
1da177e4
LT		 1939 return error;
1940}
1941
73d049a4 1942static int may_open(struct path *path, int acc_mode, int flag)
1da177e4 1943{
3fb64190 1944 struct dentry *dentry = path->dentry;
1da177e4
LT		 1945 struct inode *inode = dentry->d_inode;
1946 int error;
1947
bcda7652
AV		 1948 /* O_PATH? */
1949 if (!acc_mode)
1950 return 0;
1951
1da177e4
LT		 1952 if (!inode)
1953 return -ENOENT;
1954
c8fe8f30
CH		 1955 switch (inode->i_mode & S_IFMT) {
1956 case S_IFLNK:
1da177e4 1957 return -ELOOP;
c8fe8f30
CH		 1958 case S_IFDIR:
1959 if (acc_mode & MAY_WRITE)
1960 return -EISDIR;
1961 break;
1962 case S_IFBLK:
1963 case S_IFCHR:
3fb64190 1964 if (path->mnt->mnt_flags & MNT_NODEV)
1da177e4 1965 return -EACCES;
c8fe8f30
CH		 1966 /*FALLTHRU*/
1967 case S_IFIFO:
1968 case S_IFSOCK:
1da177e4 1969 flag &= ~O_TRUNC;
c8fe8f30 1970 break;
4a3fd211 1971 }
b41572e9 1972
3fb64190 1973 error = inode_permission(inode, acc_mode);
b41572e9
DH		 1974 if (error)
1975 return error;
6146f0d5 1976
1da177e4
LT		 1977 /*
1978 * An append-only file must be opened in append mode for writing.
1979 */
1980 if (IS_APPEND(inode)) {
8737c930 1981 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
7715b521 1982 return -EPERM;
1da177e4 1983 if (flag & O_TRUNC)
7715b521 1984 return -EPERM;
1da177e4
LT		 1985 }
1986
1987 /* O_NOATIME can only be set by the owner or superuser */
2e149670 1988 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
7715b521 1989 return -EPERM;
1da177e4
LT		 1990
1991 /*
1992 * Ensure there are no outstanding leases on the file.
1993 */
b65a9cfc 1994 return break_lease(inode, flag);
7715b521 1995}
1da177e4 1996
e1181ee6 1997static int handle_truncate(struct file *filp)
7715b521 1998{
e1181ee6 1999 struct path *path = &filp->f_path;
7715b521
AV		 2000 struct inode *inode = path->dentry->d_inode;
2001 int error = get_write_access(inode);
2002 if (error)
2003 return error;
2004 /*
2005 * Refuse to truncate files with mandatory locks held on them.
2006 */
2007 error = locks_verify_locked(inode);
2008 if (!error)
ea0d3ab2 2009 error = security_path_truncate(path);
7715b521
AV		 2010 if (!error) {
2011 error = do_truncate(path->dentry, 0,
2012 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
e1181ee6 2013 filp);
7715b521
AV		 2014 }
2015 put_write_access(inode);
acd0c935 2016 return error;
1da177e4
LT		 2017}
2018
d57999e1
DH		 2019static inline int open_to_namei_flags(int flag)
2020{
8a5e929d
AV		 2021 if ((flag & O_ACCMODE) == 3)
2022 flag--;
d57999e1
DH		 2023 return flag;
2024}
2025
31e6b01f 2026/*
fe2d35ff 2027 * Handle the last step of open()
31e6b01f 2028 */
fb1cc555 2029static struct file *do_last(struct nameidata *nd, struct path *path,
c3e380b0 2030 const struct open_flags *op, const char *pathname)
fb1cc555 2031{
a1e28038 2032 struct dentry *dir = nd->path.dentry;
6c0d46c4 2033 struct dentry *dentry;
ca344a89 2034 int open_flag = op->open_flag;
6c0d46c4 2035 int will_truncate = open_flag & O_TRUNC;
ca344a89 2036 int want_write = 0;
bcda7652 2037 int acc_mode = op->acc_mode;
fb1cc555 2038 struct file *filp;
16c2cd71 2039 int error;
1f36f774 2040
c3e380b0
AV		 2041 nd->flags &= ~LOOKUP_PARENT;
2042 nd->flags |= op->intent;
2043
1f36f774
AV		 2044 switch (nd->last_type) {
2045 case LAST_DOTDOT:
176306f5 2046 case LAST_DOT:
fe2d35ff
AV		 2047 error = handle_dots(nd, nd->last_type);
2048 if (error)
2049 return ERR_PTR(error);
1f36f774 2050 /* fallthrough */
1f36f774 2051 case LAST_ROOT:
9f1fafee 2052 error = complete_walk(nd);
16c2cd71 2053 if (error)
9f1fafee 2054 return ERR_PTR(error);
fe2d35ff 2055 audit_inode(pathname, nd->path.dentry);
ca344a89 2056 if (open_flag & O_CREAT) {
fe2d35ff
AV		 2057 error = -EISDIR;
2058 goto exit;
2059 }
2060 goto ok;
1f36f774 2061 case LAST_BIND:
9f1fafee 2062 error = complete_walk(nd);
16c2cd71 2063 if (error)
9f1fafee 2064 return ERR_PTR(error);
1f36f774 2065 audit_inode(pathname, dir);
67ee3ad2 2066 goto ok;
1f36f774 2067 }
67ee3ad2 2068
ca344a89 2069 if (!(open_flag & O_CREAT)) {
bcda7652 2070 int symlink_ok = 0;
fe2d35ff
AV		 2071 if (nd->last.name[nd->last.len])
2072 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
bcda7652
AV		 2073 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2074 symlink_ok = 1;
fe2d35ff 2075 /* we _can_ be in RCU mode here */
ce57dfc1
AV		 2076 error = walk_component(nd, path, &nd->last, LAST_NORM,
2077 !symlink_ok);
2078 if (error < 0)
fe2d35ff 2079 return ERR_PTR(error);
ce57dfc1 2080 if (error) /* symlink */
fe2d35ff 2081 return NULL;
fe2d35ff 2082 /* sayonara */
9f1fafee
AV		 2083 error = complete_walk(nd);
2084 if (error)
2085 return ERR_PTR(-ECHILD);
fe2d35ff
AV		 2086
2087 error = -ENOTDIR;
2088 if (nd->flags & LOOKUP_DIRECTORY) {
ce57dfc1 2089 if (!nd->inode->i_op->lookup)
fe2d35ff
AV		 2090 goto exit;
2091 }
2092 audit_inode(pathname, nd->path.dentry);
2093 goto ok;
2094 }
2095
2096 /* create side of things */
9f1fafee
AV		 2097 error = complete_walk(nd);
2098 if (error)
2099 return ERR_PTR(error);
fe2d35ff
AV		 2100
2101 audit_inode(pathname, dir);
16c2cd71 2102 error = -EISDIR;
1f36f774 2103 /* trailing slashes? */
31e6b01f
NP		 2104 if (nd->last.name[nd->last.len])
2105 goto exit;
a2c36b45 2106
a1e28038
AV		 2107 mutex_lock(&dir->d_inode->i_mutex);
2108
6c0d46c4
AV		 2109 dentry = lookup_hash(nd);
2110 error = PTR_ERR(dentry);
2111 if (IS_ERR(dentry)) {
fb1cc555
AV		 2112 mutex_unlock(&dir->d_inode->i_mutex);
2113 goto exit;
2114 }
2115
6c0d46c4
AV		 2116 path->dentry = dentry;
2117 path->mnt = nd->path.mnt;
2118
fb1cc555 2119 /* Negative dentry, just create the file */
6c0d46c4
AV		 2120 if (!dentry->d_inode) {
2121 int mode = op->mode;
2122 if (!IS_POSIXACL(dir->d_inode))
2123 mode &= ~current_umask();
fb1cc555
AV		 2124 /*
2125 * This write is needed to ensure that a
6c0d46c4 2126 * rw->ro transition does not occur between
fb1cc555
AV		 2127 * the time when the file is created and when
2128 * a permanent write count is taken through
2129 * the 'struct file' in nameidata_to_filp().
2130 */
2131 error = mnt_want_write(nd->path.mnt);
2132 if (error)
2133 goto exit_mutex_unlock;
ca344a89 2134 want_write = 1;
9b44f1b3 2135 /* Don't check for write permission, don't truncate */
ca344a89 2136 open_flag &= ~O_TRUNC;
6c0d46c4 2137 will_truncate = 0;
bcda7652 2138 acc_mode = MAY_OPEN;
6c0d46c4
AV		 2139 error = security_path_mknod(&nd->path, dentry, mode, 0);
2140 if (error)
2141 goto exit_mutex_unlock;
2142 error = vfs_create(dir->d_inode, dentry, mode, nd);
2143 if (error)
2144 goto exit_mutex_unlock;
2145 mutex_unlock(&dir->d_inode->i_mutex);
2146 dput(nd->path.dentry);
2147 nd->path.dentry = dentry;
ca344a89 2148 goto common;
fb1cc555
AV		 2149 }
2150
2151 /*
2152 * It already exists.
2153 */
2154 mutex_unlock(&dir->d_inode->i_mutex);
2155 audit_inode(pathname, path->dentry);
2156
2157 error = -EEXIST;
ca344a89 2158 if (open_flag & O_EXCL)
fb1cc555
AV		 2159 goto exit_dput;
2160
9875cf80
DH		 2161 error = follow_managed(path, nd->flags);
2162 if (error < 0)
2163 goto exit_dput;
fb1cc555
AV		 2164
2165 error = -ENOENT;
2166 if (!path->dentry->d_inode)
2167 goto exit_dput;
9e67f361
AV		 2168
2169 if (path->dentry->d_inode->i_op->follow_link)
fb1cc555 2170 return NULL;
fb1cc555
AV		 2171
2172 path_to_nameidata(path, nd);
31e6b01f 2173 nd->inode = path->dentry->d_inode;
fb1cc555 2174 error = -EISDIR;
31e6b01f 2175 if (S_ISDIR(nd->inode->i_mode))
fb1cc555 2176 goto exit;
67ee3ad2 2177ok:
6c0d46c4
AV		 2178 if (!S_ISREG(nd->inode->i_mode))
2179 will_truncate = 0;
2180
0f9d1a10
AV		 2181 if (will_truncate) {
2182 error = mnt_want_write(nd->path.mnt);
2183 if (error)
2184 goto exit;
ca344a89 2185 want_write = 1;
0f9d1a10 2186 }
ca344a89 2187common:
bcda7652 2188 error = may_open(&nd->path, acc_mode, open_flag);
ca344a89 2189 if (error)
0f9d1a10 2190 goto exit;
0f9d1a10
AV		 2191 filp = nameidata_to_filp(nd);
2192 if (!IS_ERR(filp)) {
2193 error = ima_file_check(filp, op->acc_mode);
2194 if (error) {
2195 fput(filp);
2196 filp = ERR_PTR(error);
2197 }
2198 }
2199 if (!IS_ERR(filp)) {
2200 if (will_truncate) {
2201 error = handle_truncate(filp);
2202 if (error) {
2203 fput(filp);
2204 filp = ERR_PTR(error);
2205 }
2206 }
2207 }
ca344a89
AV		 2208out:
2209 if (want_write)
0f9d1a10
AV		 2210 mnt_drop_write(nd->path.mnt);
2211 path_put(&nd->path);
fb1cc555
AV		 2212 return filp;
2213
2214exit_mutex_unlock:
2215 mutex_unlock(&dir->d_inode->i_mutex);
2216exit_dput:
2217 path_put_conditional(path, nd);
2218exit:
ca344a89
AV		 2219 filp = ERR_PTR(error);
2220 goto out;
fb1cc555
AV		 2221}
2222
13aab428 2223static struct file *path_openat(int dfd, const char *pathname,
73d049a4 2224 struct nameidata *nd, const struct open_flags *op, int flags)
1da177e4 2225{
fe2d35ff 2226 struct file *base = NULL;
4a3fd211 2227 struct file *filp;
9850c056 2228 struct path path;
13aab428 2229 int error;
31e6b01f
NP		 2230
2231 filp = get_empty_filp();
2232 if (!filp)
2233 return ERR_PTR(-ENFILE);
2234
47c805dc 2235 filp->f_flags = op->open_flag;
73d049a4
AV		 2236 nd->intent.open.file = filp;
2237 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2238 nd->intent.open.create_mode = op->mode;
31e6b01f 2239
73d049a4 2240 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
31e6b01f 2241 if (unlikely(error))
13aab428 2242 goto out_filp;
31e6b01f 2243
fe2d35ff 2244 current->total_link_count = 0;
73d049a4 2245 error = link_path_walk(pathname, nd);
31e6b01f
NP		 2246 if (unlikely(error))
2247 goto out_filp;
1da177e4 2248
73d049a4 2249 filp = do_last(nd, &path, op, pathname);
806b681c 2250 while (unlikely(!filp)) { /* trailing symlink */
7b9337aa 2251 struct path link = path;
def4af30 2252 void *cookie;
574197e0 2253 if (!(nd->flags & LOOKUP_FOLLOW)) {
73d049a4
AV		 2254 path_put_conditional(&path, nd);
2255 path_put(&nd->path);
40b39136
AV		 2256 filp = ERR_PTR(-ELOOP);
2257 break;
2258 }
73d049a4
AV		 2259 nd->flags |= LOOKUP_PARENT;
2260 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
574197e0 2261 error = follow_link(&link, nd, &cookie);
c3e380b0 2262 if (unlikely(error))
f1afe9ef 2263 filp = ERR_PTR(error);
c3e380b0 2264 else
73d049a4 2265 filp = do_last(nd, &path, op, pathname);
574197e0 2266 put_link(nd, &link, cookie);
806b681c 2267 }
10fa8e62 2268out:
73d049a4
AV		 2269 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2270 path_put(&nd->root);
fe2d35ff
AV		 2271 if (base)
2272 fput(base);
73d049a4 2273 release_open_intent(nd);
10fa8e62 2274 return filp;
1da177e4 2275
31e6b01f 2276out_filp:
806b681c 2277 filp = ERR_PTR(error);
10fa8e62 2278 goto out;
1da177e4
LT		 2279}
2280
13aab428
AV		 2281struct file *do_filp_open(int dfd, const char *pathname,
2282 const struct open_flags *op, int flags)
2283{
73d049a4 2284 struct nameidata nd;
13aab428
AV		 2285 struct file *filp;
2286
73d049a4 2287 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
13aab428 2288 if (unlikely(filp == ERR_PTR(-ECHILD)))
73d049a4 2289 filp = path_openat(dfd, pathname, &nd, op, flags);
13aab428 2290 if (unlikely(filp == ERR_PTR(-ESTALE)))
73d049a4 2291 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
13aab428
AV		 2292 return filp;
2293}
2294
73d049a4
AV		 2295struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2296 const char *name, const struct open_flags *op, int flags)
2297{
2298 struct nameidata nd;
2299 struct file *file;
2300
2301 nd.root.mnt = mnt;
2302 nd.root.dentry = dentry;
2303
2304 flags |= LOOKUP_ROOT;
2305
bcda7652 2306 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
73d049a4
AV		 2307 return ERR_PTR(-ELOOP);
2308
2309 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2310 if (unlikely(file == ERR_PTR(-ECHILD)))
2311 file = path_openat(-1, name, &nd, op, flags);
2312 if (unlikely(file == ERR_PTR(-ESTALE)))
2313 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2314 return file;
2315}
2316
ed75e95d 2317struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
1da177e4 2318{
c663e5d8 2319 struct dentry *dentry = ERR_PTR(-EEXIST);
ed75e95d
AV		 2320 struct nameidata nd;
2321 int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
2322 if (error)
2323 return ERR_PTR(error);
1da177e4 2324
c663e5d8
CH		 2325 /*
2326 * Yucky last component or no last component at all?
2327 * (foo/., foo/.., /////)
2328 */
ed75e95d
AV		 2329 if (nd.last_type != LAST_NORM)
2330 goto out;
2331 nd.flags &= ~LOOKUP_PARENT;
2332 nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2333 nd.intent.open.flags = O_EXCL;
c663e5d8
CH		 2334
2335 /*
2336 * Do the final lookup.
2337 */
ed75e95d
AV		 2338 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2339 dentry = lookup_hash(&nd);
1da177e4
LT		 2340 if (IS_ERR(dentry))
2341 goto fail;
c663e5d8 2342
e9baf6e5
AV		 2343 if (dentry->d_inode)
2344 goto eexist;
c663e5d8
CH		 2345 /*
2346 * Special case - lookup gave negative, but... we had foo/bar/
2347 * From the vfs_mknod() POV we just have a negative dentry -
2348 * all is fine. Let's be bastards - you had / on the end, you've
2349 * been asking for (non-existent) directory. -ENOENT for you.
2350 */
ed75e95d 2351 if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
e9baf6e5
AV		 2352 dput(dentry);
2353 dentry = ERR_PTR(-ENOENT);
ed75e95d 2354 goto fail;
e9baf6e5 2355 }
ed75e95d 2356 *path = nd.path;
1da177e4 2357 return dentry;
e9baf6e5 2358eexist:
1da177e4 2359 dput(dentry);
e9baf6e5 2360 dentry = ERR_PTR(-EEXIST);
1da177e4 2361fail:
ed75e95d
AV		 2362 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2363out:
2364 path_put(&nd.path);
1da177e4
LT		 2365 return dentry;
2366}
dae6ad8f
AV		 2367EXPORT_SYMBOL(kern_path_create);
2368
2369struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
2370{
2371 char *tmp = getname(pathname);
2372 struct dentry *res;
2373 if (IS_ERR(tmp))
2374 return ERR_CAST(tmp);
2375 res = kern_path_create(dfd, tmp, path, is_dir);
2376 putname(tmp);
2377 return res;
2378}
2379EXPORT_SYMBOL(user_path_create);
2380
1da177e4
LT		 2381int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2382{
a95164d9 2383 int error = may_create(dir, dentry);
1da177e4
LT		 2384
2385 if (error)
2386 return error;
2387
e795b717
SH		 2388 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2389 !ns_capable(inode_userns(dir), CAP_MKNOD))
1da177e4
LT		 2390 return -EPERM;
2391
acfa4380 2392 if (!dir->i_op->mknod)
1da177e4
LT		 2393 return -EPERM;
2394
08ce5f16
SH		 2395 error = devcgroup_inode_mknod(mode, dev);
2396 if (error)
2397 return error;
2398
1da177e4
LT		 2399 error = security_inode_mknod(dir, dentry, mode, dev);
2400 if (error)
2401 return error;
2402
1da177e4 2403 error = dir->i_op->mknod(dir, dentry, mode, dev);
a74574aa 2404 if (!error)
f38aa942 2405 fsnotify_create(dir, dentry);
1da177e4
LT		 2406 return error;
2407}
2408
463c3197
DH		 2409static int may_mknod(mode_t mode)
2410{
2411 switch (mode & S_IFMT) {
2412 case S_IFREG:
2413 case S_IFCHR:
2414 case S_IFBLK:
2415 case S_IFIFO:
2416 case S_IFSOCK:
2417 case 0: /* zero mode translates to S_IFREG */
2418 return 0;
2419 case S_IFDIR:
2420 return -EPERM;
2421 default:
2422 return -EINVAL;
2423 }
2424}
2425
2e4d0924
HC		 2426SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2427 unsigned, dev)
1da177e4 2428{
2ad94ae6 2429 struct dentry *dentry;
dae6ad8f
AV		 2430 struct path path;
2431 int error;
1da177e4
LT		 2432
2433 if (S_ISDIR(mode))
2434 return -EPERM;
1da177e4 2435
dae6ad8f
AV		 2436 dentry = user_path_create(dfd, filename, &path, 0);
2437 if (IS_ERR(dentry))
2438 return PTR_ERR(dentry);
2ad94ae6 2439
dae6ad8f 2440 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 2441 mode &= ~current_umask();
463c3197
DH		 2442 error = may_mknod(mode);
2443 if (error)
2444 goto out_dput;
dae6ad8f 2445 error = mnt_want_write(path.mnt);
463c3197
DH		 2446 if (error)
2447 goto out_dput;
dae6ad8f 2448 error = security_path_mknod(&path, dentry, mode, dev);
be6d3e56
KT		 2449 if (error)
2450 goto out_drop_write;
463c3197 2451 switch (mode & S_IFMT) {
1da177e4 2452 case 0: case S_IFREG:
dae6ad8f 2453 error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
1da177e4
LT		 2454 break;
2455 case S_IFCHR: case S_IFBLK:
dae6ad8f 2456 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
1da177e4
LT		 2457 new_decode_dev(dev));
2458 break;
2459 case S_IFIFO: case S_IFSOCK:
dae6ad8f 2460 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
1da177e4 2461 break;
1da177e4 2462 }
be6d3e56 2463out_drop_write:
dae6ad8f 2464 mnt_drop_write(path.mnt);
463c3197
DH		 2465out_dput:
2466 dput(dentry);
dae6ad8f
AV		 2467 mutex_unlock(&path.dentry->d_inode->i_mutex);
2468 path_put(&path);
1da177e4
LT		 2469
2470 return error;
2471}
2472
3480b257 2473SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
5590ff0d
UD		 2474{
2475 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2476}
2477
1da177e4
LT		 2478int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2479{
a95164d9 2480 int error = may_create(dir, dentry);
1da177e4
LT		 2481
2482 if (error)
2483 return error;
2484
acfa4380 2485 if (!dir->i_op->mkdir)
1da177e4
LT		 2486 return -EPERM;
2487
2488 mode &= (S_IRWXUGO|S_ISVTX);
2489 error = security_inode_mkdir(dir, dentry, mode);
2490 if (error)
2491 return error;
2492
1da177e4 2493 error = dir->i_op->mkdir(dir, dentry, mode);
a74574aa 2494 if (!error)
f38aa942 2495 fsnotify_mkdir(dir, dentry);
1da177e4
LT		 2496 return error;
2497}
2498
2e4d0924 2499SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
1da177e4 2500{
6902d925 2501 struct dentry *dentry;
dae6ad8f
AV		 2502 struct path path;
2503 int error;
1da177e4 2504
dae6ad8f 2505 dentry = user_path_create(dfd, pathname, &path, 1);
6902d925 2506 if (IS_ERR(dentry))
dae6ad8f 2507 return PTR_ERR(dentry);
1da177e4 2508
dae6ad8f 2509 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 2510 mode &= ~current_umask();
dae6ad8f 2511 error = mnt_want_write(path.mnt);
463c3197
DH		 2512 if (error)
2513 goto out_dput;
dae6ad8f 2514 error = security_path_mkdir(&path, dentry, mode);
be6d3e56
KT		 2515 if (error)
2516 goto out_drop_write;
dae6ad8f 2517 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
be6d3e56 2518out_drop_write:
dae6ad8f 2519 mnt_drop_write(path.mnt);
463c3197 2520out_dput:
6902d925 2521 dput(dentry);
dae6ad8f
AV		 2522 mutex_unlock(&path.dentry->d_inode->i_mutex);
2523 path_put(&path);
1da177e4
LT		 2524 return error;
2525}
2526
3cdad428 2527SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
5590ff0d
UD		 2528{
2529 return sys_mkdirat(AT_FDCWD, pathname, mode);
2530}
2531
1da177e4 2532/*
a71905f0
SW		 2533 * The dentry_unhash() helper will try to drop the dentry early: we
2534 * should have a usage count of 2 if we're the only user of this
2535 * dentry, and if that is true (possibly after pruning the dcache),
2536 * then we drop the dentry now.
1da177e4
LT		 2537 *
2538 * A low-level filesystem can, if it choses, legally
2539 * do a
2540 *
2541 * if (!d_unhashed(dentry))
2542 * return -EBUSY;
2543 *
2544 * if it cannot handle the case of removing a directory
2545 * that is still in use by something else..
2546 */
2547void dentry_unhash(struct dentry *dentry)
2548{
dc168427 2549 shrink_dcache_parent(dentry);
1da177e4 2550 spin_lock(&dentry->d_lock);
64252c75 2551 if (dentry->d_count == 1)
1da177e4
LT		 2552 __d_drop(dentry);
2553 spin_unlock(&dentry->d_lock);
1da177e4
LT		 2554}
2555
2556int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2557{
2558 int error = may_delete(dir, dentry, 1);
2559
2560 if (error)
2561 return error;
2562
acfa4380 2563 if (!dir->i_op->rmdir)
1da177e4
LT		 2564 return -EPERM;
2565
1b1dcc1b 2566 mutex_lock(&dentry->d_inode->i_mutex);
912dbc15
SW		 2567
2568 error = -EBUSY;
1da177e4 2569 if (d_mountpoint(dentry))
912dbc15
SW		 2570 goto out;
2571
2572 error = security_inode_rmdir(dir, dentry);
2573 if (error)
2574 goto out;
2575
3cebde24 2576 shrink_dcache_parent(dentry);
912dbc15
SW		 2577 error = dir->i_op->rmdir(dir, dentry);
2578 if (error)
2579 goto out;
2580
2581 dentry->d_inode->i_flags |= S_DEAD;
2582 dont_mount(dentry);
2583
2584out:
1b1dcc1b 2585 mutex_unlock(&dentry->d_inode->i_mutex);
912dbc15 2586 if (!error)
1da177e4 2587 d_delete(dentry);
1da177e4
LT		 2588 return error;
2589}
2590
5590ff0d 2591static long do_rmdir(int dfd, const char __user *pathname)
1da177e4
LT		 2592{
2593 int error = 0;
2594 char * name;
2595 struct dentry *dentry;
2596 struct nameidata nd;
2597
2ad94ae6 2598 error = user_path_parent(dfd, pathname, &nd, &name);
1da177e4 2599 if (error)
2ad94ae6 2600 return error;
1da177e4
LT		 2601
2602 switch(nd.last_type) {
0612d9fb
OH		 2603 case LAST_DOTDOT:
2604 error = -ENOTEMPTY;
2605 goto exit1;
2606 case LAST_DOT:
2607 error = -EINVAL;
2608 goto exit1;
2609 case LAST_ROOT:
2610 error = -EBUSY;
2611 goto exit1;
1da177e4 2612 }
0612d9fb
OH		 2613
2614 nd.flags &= ~LOOKUP_PARENT;
2615
4ac91378 2616 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
49705b77 2617 dentry = lookup_hash(&nd);
1da177e4 2618 error = PTR_ERR(dentry);
6902d925
DH		 2619 if (IS_ERR(dentry))
2620 goto exit2;
e6bc45d6
TT		 2621 if (!dentry->d_inode) {
2622 error = -ENOENT;
2623 goto exit3;
2624 }
0622753b
DH		 2625 error = mnt_want_write(nd.path.mnt);
2626 if (error)
2627 goto exit3;
be6d3e56
KT		 2628 error = security_path_rmdir(&nd.path, dentry);
2629 if (error)
2630 goto exit4;
4ac91378 2631 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
be6d3e56 2632exit4:
0622753b
DH		 2633 mnt_drop_write(nd.path.mnt);
2634exit3:
6902d925
DH		 2635 dput(dentry);
2636exit2:
4ac91378 2637 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
1da177e4 2638exit1:
1d957f9b 2639 path_put(&nd.path);
1da177e4
LT		 2640 putname(name);
2641 return error;
2642}
2643
3cdad428 2644SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
5590ff0d
UD		 2645{
2646 return do_rmdir(AT_FDCWD, pathname);
2647}
2648
1da177e4
LT		 2649int vfs_unlink(struct inode *dir, struct dentry *dentry)
2650{
2651 int error = may_delete(dir, dentry, 0);
2652
2653 if (error)
2654 return error;
2655
acfa4380 2656 if (!dir->i_op->unlink)
1da177e4
LT		 2657 return -EPERM;
2658
1b1dcc1b 2659 mutex_lock(&dentry->d_inode->i_mutex);
1da177e4
LT		 2660 if (d_mountpoint(dentry))
2661 error = -EBUSY;
2662 else {
2663 error = security_inode_unlink(dir, dentry);
bec1052e 2664 if (!error) {
1da177e4 2665 error = dir->i_op->unlink(dir, dentry);
bec1052e 2666 if (!error)
d83c49f3 2667 dont_mount(dentry);
bec1052e 2668 }
1da177e4 2669 }
1b1dcc1b 2670 mutex_unlock(&dentry->d_inode->i_mutex);
1da177e4
LT		 2671
2672 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2673 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
ece95912 2674 fsnotify_link_count(dentry->d_inode);
e234f35c 2675 d_delete(dentry);
1da177e4 2676 }
0eeca283 2677
1da177e4
LT		 2678 return error;
2679}
2680
2681/*
2682 * Make sure that the actual truncation of the file will occur outside its
1b1dcc1b 2683 * directory's i_mutex. Truncate can take a long time if there is a lot of
1da177e4
LT		 2684 * writeout happening, and we don't want to prevent access to the directory
2685 * while waiting on the I/O.
2686 */
5590ff0d 2687static long do_unlinkat(int dfd, const char __user *pathname)
1da177e4 2688{
2ad94ae6
AV		 2689 int error;
2690 char *name;
1da177e4
LT		 2691 struct dentry *dentry;
2692 struct nameidata nd;
2693 struct inode *inode = NULL;
2694
2ad94ae6 2695 error = user_path_parent(dfd, pathname, &nd, &name);
1da177e4 2696 if (error)
2ad94ae6
AV		 2697 return error;
2698
1da177e4
LT		 2699 error = -EISDIR;
2700 if (nd.last_type != LAST_NORM)
2701 goto exit1;
0612d9fb
OH		 2702
2703 nd.flags &= ~LOOKUP_PARENT;
2704
4ac91378 2705 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
49705b77 2706 dentry = lookup_hash(&nd);
1da177e4
LT		 2707 error = PTR_ERR(dentry);
2708 if (!IS_ERR(dentry)) {
2709 /* Why not before? Because we want correct error value */
50338b88
TE		 2710 if (nd.last.name[nd.last.len])
2711 goto slashes;
1da177e4 2712 inode = dentry->d_inode;
50338b88 2713 if (!inode)
e6bc45d6
TT		 2714 goto slashes;
2715 ihold(inode);
0622753b
DH		 2716 error = mnt_want_write(nd.path.mnt);
2717 if (error)
2718 goto exit2;
be6d3e56
KT		 2719 error = security_path_unlink(&nd.path, dentry);
2720 if (error)
2721 goto exit3;
4ac91378 2722 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
be6d3e56 2723exit3:
0622753b 2724 mnt_drop_write(nd.path.mnt);
1da177e4
LT		 2725 exit2:
2726 dput(dentry);
2727 }
4ac91378 2728 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
1da177e4
LT		 2729 if (inode)
2730 iput(inode); /* truncate the inode here */
2731exit1:
1d957f9b 2732 path_put(&nd.path);
1da177e4
LT		 2733 putname(name);
2734 return error;
2735
2736slashes:
2737 error = !dentry->d_inode ? -ENOENT :
2738 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2739 goto exit2;
2740}
2741
2e4d0924 2742SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
5590ff0d
UD		 2743{
2744 if ((flag & ~AT_REMOVEDIR) != 0)
2745 return -EINVAL;
2746
2747 if (flag & AT_REMOVEDIR)
2748 return do_rmdir(dfd, pathname);
2749
2750 return do_unlinkat(dfd, pathname);
2751}
2752
3480b257 2753SYSCALL_DEFINE1(unlink, const char __user *, pathname)
5590ff0d
UD		 2754{
2755 return do_unlinkat(AT_FDCWD, pathname);
2756}
2757
db2e747b 2758int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
1da177e4 2759{
a95164d9 2760 int error = may_create(dir, dentry);
1da177e4
LT		 2761
2762 if (error)
2763 return error;
2764
acfa4380 2765 if (!dir->i_op->symlink)
1da177e4
LT		 2766 return -EPERM;
2767
2768 error = security_inode_symlink(dir, dentry, oldname);
2769 if (error)
2770 return error;
2771
1da177e4 2772 error = dir->i_op->symlink(dir, dentry, oldname);
a74574aa 2773 if (!error)
f38aa942 2774 fsnotify_create(dir, dentry);
1da177e4
LT		 2775 return error;
2776}
2777
2e4d0924
HC		 2778SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2779 int, newdfd, const char __user *, newname)
1da177e4 2780{
2ad94ae6
AV		 2781 int error;
2782 char *from;
6902d925 2783 struct dentry *dentry;
dae6ad8f 2784 struct path path;
1da177e4
LT		 2785
2786 from = getname(oldname);
2ad94ae6 2787 if (IS_ERR(from))
1da177e4 2788 return PTR_ERR(from);
1da177e4 2789
dae6ad8f 2790 dentry = user_path_create(newdfd, newname, &path, 0);
6902d925
DH		 2791 error = PTR_ERR(dentry);
2792 if (IS_ERR(dentry))
dae6ad8f 2793 goto out_putname;
6902d925 2794
dae6ad8f 2795 error = mnt_want_write(path.mnt);
75c3f29d
DH		 2796 if (error)
2797 goto out_dput;
dae6ad8f 2798 error = security_path_symlink(&path, dentry, from);
be6d3e56
KT		 2799 if (error)
2800 goto out_drop_write;
dae6ad8f 2801 error = vfs_symlink(path.dentry->d_inode, dentry, from);
be6d3e56 2802out_drop_write:
dae6ad8f 2803 mnt_drop_write(path.mnt);
75c3f29d 2804out_dput:
6902d925 2805 dput(dentry);
dae6ad8f
AV		 2806 mutex_unlock(&path.dentry->d_inode->i_mutex);
2807 path_put(&path);
6902d925 2808out_putname:
1da177e4
LT		 2809 putname(from);
2810 return error;
2811}
2812
3480b257 2813SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
5590ff0d
UD		 2814{
2815 return sys_symlinkat(oldname, AT_FDCWD, newname);
2816}
2817
1da177e4
LT		 2818int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2819{
2820 struct inode *inode = old_dentry->d_inode;
2821 int error;
2822
2823 if (!inode)
2824 return -ENOENT;
2825
a95164d9 2826 error = may_create(dir, new_dentry);
1da177e4
LT		 2827 if (error)
2828 return error;
2829
2830 if (dir->i_sb != inode->i_sb)
2831 return -EXDEV;
2832
2833 /*
2834 * A link to an append-only or immutable file cannot be created.
2835 */
2836 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2837 return -EPERM;
acfa4380 2838 if (!dir->i_op->link)
1da177e4 2839 return -EPERM;
7e79eedb 2840 if (S_ISDIR(inode->i_mode))
1da177e4
LT		 2841 return -EPERM;
2842
2843 error = security_inode_link(old_dentry, dir, new_dentry);
2844 if (error)
2845 return error;
2846
7e79eedb 2847 mutex_lock(&inode->i_mutex);
aae8a97d
AK		 2848 /* Make sure we don't allow creating hardlink to an unlinked file */
2849 if (inode->i_nlink == 0)
2850 error = -ENOENT;
2851 else
2852 error = dir->i_op->link(old_dentry, dir, new_dentry);
7e79eedb 2853 mutex_unlock(&inode->i_mutex);
e31e14ec 2854 if (!error)
7e79eedb 2855 fsnotify_link(dir, inode, new_dentry);
1da177e4
LT		 2856 return error;
2857}
2858
2859/*
2860 * Hardlinks are often used in delicate situations. We avoid
2861 * security-related surprises by not following symlinks on the
2862 * newname. --KAB
2863 *
2864 * We don't follow them on the oldname either to be compatible
2865 * with linux 2.0, and to avoid hard-linking to directories
2866 * and other special files. --ADM
2867 */
2e4d0924
HC		 2868SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2869 int, newdfd, const char __user *, newname, int, flags)
1da177e4
LT		 2870{
2871 struct dentry *new_dentry;
dae6ad8f 2872 struct path old_path, new_path;
11a7b371 2873 int how = 0;
1da177e4 2874 int error;
1da177e4 2875
11a7b371 2876 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
c04030e1 2877 return -EINVAL;
11a7b371
AK		 2878 /*
2879 * To use null names we require CAP_DAC_READ_SEARCH
2880 * This ensures that not everyone will be able to create
2881 * handlink using the passed filedescriptor.
2882 */
2883 if (flags & AT_EMPTY_PATH) {
2884 if (!capable(CAP_DAC_READ_SEARCH))
2885 return -ENOENT;
2886 how = LOOKUP_EMPTY;
2887 }
2888
2889 if (flags & AT_SYMLINK_FOLLOW)
2890 how |= LOOKUP_FOLLOW;
c04030e1 2891
11a7b371 2892 error = user_path_at(olddfd, oldname, how, &old_path);
1da177e4 2893 if (error)
2ad94ae6
AV		 2894 return error;
2895
dae6ad8f 2896 new_dentry = user_path_create(newdfd, newname, &new_path, 0);
1da177e4 2897 error = PTR_ERR(new_dentry);
6902d925 2898 if (IS_ERR(new_dentry))
dae6ad8f
AV		 2899 goto out;
2900
2901 error = -EXDEV;
2902 if (old_path.mnt != new_path.mnt)
2903 goto out_dput;
2904 error = mnt_want_write(new_path.mnt);
75c3f29d
DH		 2905 if (error)
2906 goto out_dput;
dae6ad8f 2907 error = security_path_link(old_path.dentry, &new_path, new_dentry);
be6d3e56
KT		 2908 if (error)
2909 goto out_drop_write;
dae6ad8f 2910 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
be6d3e56 2911out_drop_write:
dae6ad8f 2912 mnt_drop_write(new_path.mnt);
75c3f29d 2913out_dput:
6902d925 2914 dput(new_dentry);
dae6ad8f
AV		 2915 mutex_unlock(&new_path.dentry->d_inode->i_mutex);
2916 path_put(&new_path);
1da177e4 2917out:
2d8f3038 2918 path_put(&old_path);
1da177e4
LT		 2919
2920 return error;
2921}
2922
3480b257 2923SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
5590ff0d 2924{
c04030e1 2925 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
5590ff0d
UD		 2926}
2927
1da177e4
LT		 2928/*
2929 * The worst of all namespace operations - renaming directory. "Perverted"
2930 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2931 * Problems:
2932 * a) we can get into loop creation. Check is done in is_subdir().
2933 * b) race potential - two innocent renames can create a loop together.
2934 * That's where 4.4 screws up. Current fix: serialization on
a11f3a05 2935 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
1da177e4
LT		 2936 * story.
2937 * c) we have to lock _three_ objects - parents and victim (if it exists).
1b1dcc1b 2938 * And that - after we got ->i_mutex on parents (until then we don't know
1da177e4
LT		 2939 * whether the target exists). Solution: try to be smart with locking
2940 * order for inodes. We rely on the fact that tree topology may change
a11f3a05 2941 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
1da177e4
LT		 2942 * move will be locked. Thus we can rank directories by the tree
2943 * (ancestors first) and rank all non-directories after them.
2944 * That works since everybody except rename does "lock parent, lookup,
a11f3a05 2945 * lock child" and rename is under ->s_vfs_rename_mutex.
1da177e4
LT		 2946 * HOWEVER, it relies on the assumption that any object with ->lookup()
2947 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2948 * we'd better make sure that there's no link(2) for them.
e4eaac06 2949 * d) conversion from fhandle to dentry may come in the wrong moment - when
1b1dcc1b 2950 * we are removing the target. Solution: we will have to grab ->i_mutex
1da177e4 2951 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
c41b20e7 2952 * ->i_mutex on parents, which works but leads to some truly excessive
1da177e4
LT		 2953 * locking].
2954 */
75c96f85
AB		 2955static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2956 struct inode *new_dir, struct dentry *new_dentry)
1da177e4
LT		 2957{
2958 int error = 0;
9055cba7 2959 struct inode *target = new_dentry->d_inode;
1da177e4
LT		 2960
2961 /*
2962 * If we are going to change the parent - check write permissions,
2963 * we'll need to flip '..'.
2964 */
2965 if (new_dir != old_dir) {
f419a2e3 2966 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
1da177e4
LT		 2967 if (error)
2968 return error;
2969 }
2970
2971 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2972 if (error)
2973 return error;
2974
d83c49f3 2975 if (target)
1b1dcc1b 2976 mutex_lock(&target->i_mutex);
9055cba7
SW		 2977
2978 error = -EBUSY;
2979 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
2980 goto out;
2981
3cebde24
SW		 2982 if (target)
2983 shrink_dcache_parent(new_dentry);
9055cba7
SW		 2984 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2985 if (error)
2986 goto out;
2987
1da177e4 2988 if (target) {
9055cba7
SW		 2989 target->i_flags |= S_DEAD;
2990 dont_mount(new_dentry);
1da177e4 2991 }
9055cba7
SW		 2992out:
2993 if (target)
2994 mutex_unlock(&target->i_mutex);
e31e14ec 2995 if (!error)
349457cc
MF		 2996 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2997 d_move(old_dentry,new_dentry);
1da177e4
LT		 2998 return error;
2999}
3000
75c96f85
AB		 3001static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
3002 struct inode *new_dir, struct dentry *new_dentry)
1da177e4 3003{
51892bbb 3004 struct inode *target = new_dentry->d_inode;
1da177e4
LT		 3005 int error;
3006
3007 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3008 if (error)
3009 return error;
3010
3011 dget(new_dentry);
1da177e4 3012 if (target)
1b1dcc1b 3013 mutex_lock(&target->i_mutex);
51892bbb
SW		 3014
3015 error = -EBUSY;
1da177e4 3016 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
51892bbb
SW		 3017 goto out;
3018
3019 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3020 if (error)
3021 goto out;
3022
3023 if (target)
3024 dont_mount(new_dentry);
3025 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3026 d_move(old_dentry, new_dentry);
3027out:
1da177e4 3028 if (target)
1b1dcc1b 3029 mutex_unlock(&target->i_mutex);
1da177e4
LT		 3030 dput(new_dentry);
3031 return error;
3032}
3033
3034int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3035 struct inode *new_dir, struct dentry *new_dentry)
3036{
3037 int error;
3038 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
59b0df21 3039 const unsigned char *old_name;
1da177e4
LT		 3040
3041 if (old_dentry->d_inode == new_dentry->d_inode)
3042 return 0;
3043
3044 error = may_delete(old_dir, old_dentry, is_dir);
3045 if (error)
3046 return error;
3047
3048 if (!new_dentry->d_inode)
a95164d9 3049 error = may_create(new_dir, new_dentry);
1da177e4
LT		 3050 else
3051 error = may_delete(new_dir, new_dentry, is_dir);
3052 if (error)
3053 return error;
3054
acfa4380 3055 if (!old_dir->i_op->rename)
1da177e4
LT		 3056 return -EPERM;
3057
0eeca283
RL		 3058 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3059
1da177e4
LT		 3060 if (is_dir)
3061 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3062 else
3063 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
123df294
AV		 3064 if (!error)
3065 fsnotify_move(old_dir, new_dir, old_name, is_dir,
5a190ae6 3066 new_dentry->d_inode, old_dentry);
0eeca283
RL		 3067 fsnotify_oldname_free(old_name);
3068
1da177e4
LT		 3069 return error;
3070}
3071
2e4d0924
HC		 3072SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3073 int, newdfd, const char __user *, newname)
1da177e4 3074{
2ad94ae6
AV		 3075 struct dentry *old_dir, *new_dir;
3076 struct dentry *old_dentry, *new_dentry;
3077 struct dentry *trap;
1da177e4 3078 struct nameidata oldnd, newnd;
2ad94ae6
AV		 3079 char *from;
3080 char *to;
3081 int error;
1da177e4 3082
2ad94ae6 3083 error = user_path_parent(olddfd, oldname, &oldnd, &from);
1da177e4
LT		 3084 if (error)
3085 goto exit;
3086
2ad94ae6 3087 error = user_path_parent(newdfd, newname, &newnd, &to);
1da177e4
LT		 3088 if (error)
3089 goto exit1;
3090
3091 error = -EXDEV;
4ac91378 3092 if (oldnd.path.mnt != newnd.path.mnt)
1da177e4
LT		 3093 goto exit2;
3094
4ac91378 3095 old_dir = oldnd.path.dentry;
1da177e4
LT		 3096 error = -EBUSY;
3097 if (oldnd.last_type != LAST_NORM)
3098 goto exit2;
3099
4ac91378 3100 new_dir = newnd.path.dentry;
1da177e4
LT		 3101 if (newnd.last_type != LAST_NORM)
3102 goto exit2;
3103
0612d9fb
OH		 3104 oldnd.flags &= ~LOOKUP_PARENT;
3105 newnd.flags &= ~LOOKUP_PARENT;
4e9ed2f8 3106 newnd.flags |= LOOKUP_RENAME_TARGET;
0612d9fb 3107
1da177e4
LT		 3108 trap = lock_rename(new_dir, old_dir);
3109
49705b77 3110 old_dentry = lookup_hash(&oldnd);
1da177e4
LT		 3111 error = PTR_ERR(old_dentry);
3112 if (IS_ERR(old_dentry))
3113 goto exit3;
3114 /* source must exist */
3115 error = -ENOENT;
3116 if (!old_dentry->d_inode)
3117 goto exit4;
3118 /* unless the source is a directory trailing slashes give -ENOTDIR */
3119 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3120 error = -ENOTDIR;
3121 if (oldnd.last.name[oldnd.last.len])
3122 goto exit4;
3123 if (newnd.last.name[newnd.last.len])
3124 goto exit4;
3125 }
3126 /* source should not be ancestor of target */
3127 error = -EINVAL;
3128 if (old_dentry == trap)
3129 goto exit4;
49705b77 3130 new_dentry = lookup_hash(&newnd);
1da177e4
LT		 3131 error = PTR_ERR(new_dentry);
3132 if (IS_ERR(new_dentry))
3133 goto exit4;
3134 /* target should not be an ancestor of source */
3135 error = -ENOTEMPTY;
3136 if (new_dentry == trap)
3137 goto exit5;
3138
9079b1eb
DH		 3139 error = mnt_want_write(oldnd.path.mnt);
3140 if (error)
3141 goto exit5;
be6d3e56
KT		 3142 error = security_path_rename(&oldnd.path, old_dentry,
3143 &newnd.path, new_dentry);
3144 if (error)
3145 goto exit6;
1da177e4
LT		 3146 error = vfs_rename(old_dir->d_inode, old_dentry,
3147 new_dir->d_inode, new_dentry);
be6d3e56 3148exit6:
9079b1eb 3149 mnt_drop_write(oldnd.path.mnt);
1da177e4
LT		 3150exit5:
3151 dput(new_dentry);
3152exit4:
3153 dput(old_dentry);
3154exit3:
3155 unlock_rename(new_dir, old_dir);
3156exit2:
1d957f9b 3157 path_put(&newnd.path);
2ad94ae6 3158 putname(to);
1da177e4 3159exit1:
1d957f9b 3160 path_put(&oldnd.path);
1da177e4 3161 putname(from);
2ad94ae6 3162exit:
1da177e4
LT		 3163 return error;
3164}
3165
a26eab24 3166SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
5590ff0d
UD		 3167{
3168 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3169}
3170
1da177e4
LT		 3171int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3172{
3173 int len;
3174
3175 len = PTR_ERR(link);
3176 if (IS_ERR(link))
3177 goto out;
3178
3179 len = strlen(link);
3180 if (len > (unsigned) buflen)
3181 len = buflen;
3182 if (copy_to_user(buffer, link, len))
3183 len = -EFAULT;
3184out:
3185 return len;
3186}
3187
3188/*
3189 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3190 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3191 * using) it for any given inode is up to filesystem.
3192 */
3193int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3194{
3195 struct nameidata nd;
cc314eef 3196 void *cookie;
694a1764 3197 int res;
cc314eef 3198
1da177e4 3199 nd.depth = 0;
cc314eef 3200 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
694a1764
MS		 3201 if (IS_ERR(cookie))
3202 return PTR_ERR(cookie);
3203
3204 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3205 if (dentry->d_inode->i_op->put_link)
3206 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3207 return res;
1da177e4
LT		 3208}
3209
3210int vfs_follow_link(struct nameidata *nd, const char *link)
3211{
3212 return __vfs_follow_link(nd, link);
3213}
3214
3215/* get the link contents into pagecache */
3216static char *page_getlink(struct dentry * dentry, struct page **ppage)
3217{
ebd09abb
DG		 3218 char *kaddr;
3219 struct page *page;
1da177e4 3220 struct address_space *mapping = dentry->d_inode->i_mapping;
090d2b18 3221 page = read_mapping_page(mapping, 0, NULL);
1da177e4 3222 if (IS_ERR(page))
6fe6900e 3223 return (char*)page;
1da177e4 3224 *ppage = page;
ebd09abb
DG		 3225 kaddr = kmap(page);
3226 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3227 return kaddr;
1da177e4
LT		 3228}
3229
3230int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3231{
3232 struct page *page = NULL;
3233 char *s = page_getlink(dentry, &page);
3234 int res = vfs_readlink(dentry,buffer,buflen,s);
3235 if (page) {
3236 kunmap(page);
3237 page_cache_release(page);
3238 }
3239 return res;
3240}
3241
cc314eef 3242void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
1da177e4 3243{
cc314eef 3244 struct page *page = NULL;
1da177e4 3245 nd_set_link(nd, page_getlink(dentry, &page));
cc314eef 3246 return page;
1da177e4
LT		 3247}
3248
cc314eef 3249void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1da177e4 3250{
cc314eef
LT		 3251 struct page *page = cookie;
3252
3253 if (page) {
1da177e4
LT		 3254 kunmap(page);
3255 page_cache_release(page);
1da177e4
LT		 3256 }
3257}
3258
54566b2c
NP		 3259/*
3260 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3261 */
3262int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
1da177e4
LT		 3263{
3264 struct address_space *mapping = inode->i_mapping;
0adb25d2 3265 struct page *page;
afddba49 3266 void *fsdata;
beb497ab 3267 int err;
1da177e4 3268 char *kaddr;
54566b2c
NP		 3269 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3270 if (nofs)
3271 flags |= AOP_FLAG_NOFS;
1da177e4 3272
7e53cac4 3273retry:
afddba49 3274 err = pagecache_write_begin(NULL, mapping, 0, len-1,
54566b2c 3275 flags, &page, &fsdata);
1da177e4 3276 if (err)
afddba49
NP		 3277 goto fail;
3278
1da177e4
LT		 3279 kaddr = kmap_atomic(page, KM_USER0);
3280 memcpy(kaddr, symname, len-1);
3281 kunmap_atomic(kaddr, KM_USER0);
afddba49
NP		 3282
3283 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3284 page, fsdata);
1da177e4
LT		 3285 if (err < 0)
3286 goto fail;
afddba49
NP		 3287 if (err < len-1)
3288 goto retry;
3289
1da177e4
LT		 3290 mark_inode_dirty(inode);
3291 return 0;
1da177e4
LT		 3292fail:
3293 return err;
3294}
3295
0adb25d2
KK		 3296int page_symlink(struct inode *inode, const char *symname, int len)
3297{
3298 return __page_symlink(inode, symname, len,
54566b2c 3299 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
0adb25d2
KK		 3300}
3301
92e1d5be 3302const struct inode_operations page_symlink_inode_operations = {
1da177e4
LT		 3303 .readlink = generic_readlink,
3304 .follow_link = page_follow_link_light,
3305 .put_link = page_put_link,
3306};
3307
2d8f3038 3308EXPORT_SYMBOL(user_path_at);
cc53ce53 3309EXPORT_SYMBOL(follow_down_one);
1da177e4
LT		 3310EXPORT_SYMBOL(follow_down);
3311EXPORT_SYMBOL(follow_up);
3312EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3313EXPORT_SYMBOL(getname);
3314EXPORT_SYMBOL(lock_rename);
1da177e4
LT		 3315EXPORT_SYMBOL(lookup_one_len);
3316EXPORT_SYMBOL(page_follow_link_light);
3317EXPORT_SYMBOL(page_put_link);
3318EXPORT_SYMBOL(page_readlink);
0adb25d2 3319EXPORT_SYMBOL(__page_symlink);
1da177e4
LT		 3320EXPORT_SYMBOL(page_symlink);
3321EXPORT_SYMBOL(page_symlink_inode_operations);
d1811465 3322EXPORT_SYMBOL(kern_path);
16f18200 3323EXPORT_SYMBOL(vfs_path_lookup);
f419a2e3 3324EXPORT_SYMBOL(inode_permission);
1da177e4
LT		 3325EXPORT_SYMBOL(unlock_rename);
3326EXPORT_SYMBOL(vfs_create);
3327EXPORT_SYMBOL(vfs_follow_link);
3328EXPORT_SYMBOL(vfs_link);
3329EXPORT_SYMBOL(vfs_mkdir);
3330EXPORT_SYMBOL(vfs_mknod);
3331EXPORT_SYMBOL(generic_permission);
3332EXPORT_SYMBOL(vfs_readlink);
3333EXPORT_SYMBOL(vfs_rename);
3334EXPORT_SYMBOL(vfs_rmdir);
3335EXPORT_SYMBOL(vfs_symlink);
3336EXPORT_SYMBOL(vfs_unlink);
3337EXPORT_SYMBOL(dentry_unhash);
3338EXPORT_SYMBOL(generic_readlink);
kernel source for telekom puls (alcatel/mediatek)