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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>
630d9c47 18#include <linux/export.h>
44696908 19#include <linux/kernel.h>
1da177e4
LT
20#include <linux/slab.h>
21#include <linux/fs.h>
22#include <linux/namei.h>
1da177e4 23#include <linux/pagemap.h>
0eeca283 24#include <linux/fsnotify.h>
1da177e4
LT
25#include <linux/personality.h>
26#include <linux/security.h>
6146f0d5 27#include <linux/ima.h>
1da177e4
LT
28#include <linux/syscalls.h>
29#include <linux/mount.h>
30#include <linux/audit.h>
16f7e0fe 31#include <linux/capability.h>
834f2a4a 32#include <linux/file.h>
5590ff0d 33#include <linux/fcntl.h>
08ce5f16 34#include <linux/device_cgroup.h>
5ad4e53b 35#include <linux/fs_struct.h>
e77819e5 36#include <linux/posix_acl.h>
99d263d4 37#include <linux/hash.h>
2a18da7a 38#include <linux/bitops.h>
aeaa4a79 39#include <linux/init_task.h>
1da177e4
LT
40#include <asm/uaccess.h>
41
e81e3f4d 42#include "internal.h"
c7105365 43#include "mount.h"
e81e3f4d 44
1da177e4
LT
45/* [Feb-1997 T. Schoebel-Theuer]
46 * Fundamental changes in the pathname lookup mechanisms (namei)
47 * were necessary because of omirr. The reason is that omirr needs
48 * to know the _real_ pathname, not the user-supplied one, in case
49 * of symlinks (and also when transname replacements occur).
50 *
51 * The new code replaces the old recursive symlink resolution with
52 * an iterative one (in case of non-nested symlink chains). It does
53 * this with calls to <fs>_follow_link().
54 * As a side effect, dir_namei(), _namei() and follow_link() are now
55 * replaced with a single function lookup_dentry() that can handle all
56 * the special cases of the former code.
57 *
58 * With the new dcache, the pathname is stored at each inode, at least as
59 * long as the refcount of the inode is positive. As a side effect, the
60 * size of the dcache depends on the inode cache and thus is dynamic.
61 *
62 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
63 * resolution to correspond with current state of the code.
64 *
65 * Note that the symlink resolution is not *completely* iterative.
66 * There is still a significant amount of tail- and mid- recursion in
67 * the algorithm. Also, note that <fs>_readlink() is not used in
68 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
69 * may return different results than <fs>_follow_link(). Many virtual
70 * filesystems (including /proc) exhibit this behavior.
71 */
72
73/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
74 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
75 * and the name already exists in form of a symlink, try to create the new
76 * name indicated by the symlink. The old code always complained that the
77 * name already exists, due to not following the symlink even if its target
78 * is nonexistent. The new semantics affects also mknod() and link() when
25985edc 79 * the name is a symlink pointing to a non-existent name.
1da177e4
LT
80 *
81 * I don't know which semantics is the right one, since I have no access
82 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
83 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
84 * "old" one. Personally, I think the new semantics is much more logical.
85 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
86 * file does succeed in both HP-UX and SunOs, but not in Solaris
87 * and in the old Linux semantics.
88 */
89
90/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
91 * semantics. See the comments in "open_namei" and "do_link" below.
92 *
93 * [10-Sep-98 Alan Modra] Another symlink change.
94 */
95
96/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
97 * inside the path - always follow.
98 * in the last component in creation/removal/renaming - never follow.
99 * if LOOKUP_FOLLOW passed - follow.
100 * if the pathname has trailing slashes - follow.
101 * otherwise - don't follow.
102 * (applied in that order).
103 *
104 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
105 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
106 * During the 2.4 we need to fix the userland stuff depending on it -
107 * hopefully we will be able to get rid of that wart in 2.5. So far only
108 * XEmacs seems to be relying on it...
109 */
110/*
111 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
a11f3a05 112 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
1da177e4
LT
113 * any extra contention...
114 */
115
116/* In order to reduce some races, while at the same time doing additional
117 * checking and hopefully speeding things up, we copy filenames to the
118 * kernel data space before using them..
119 *
120 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
121 * PATH_MAX includes the nul terminator --RR.
122 */
91a27b2a 123
fd2f7cb5 124#define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
7950e385 125
51f39a1f 126struct filename *
91a27b2a
JL
127getname_flags(const char __user *filename, int flags, int *empty)
128{
94b5d262 129 struct filename *result;
7950e385 130 char *kname;
94b5d262 131 int len;
4043cde8 132
7ac86265
JL
133 result = audit_reusename(filename);
134 if (result)
135 return result;
136
7950e385 137 result = __getname();
3f9f0aa6 138 if (unlikely(!result))
4043cde8
EP
139 return ERR_PTR(-ENOMEM);
140
7950e385
JL
141 /*
142 * First, try to embed the struct filename inside the names_cache
143 * allocation
144 */
fd2f7cb5 145 kname = (char *)result->iname;
91a27b2a 146 result->name = kname;
7950e385 147
94b5d262 148 len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
91a27b2a 149 if (unlikely(len < 0)) {
94b5d262
AV
150 __putname(result);
151 return ERR_PTR(len);
91a27b2a 152 }
3f9f0aa6 153
7950e385
JL
154 /*
155 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
156 * separate struct filename so we can dedicate the entire
157 * names_cache allocation for the pathname, and re-do the copy from
158 * userland.
159 */
94b5d262 160 if (unlikely(len == EMBEDDED_NAME_MAX)) {
fd2f7cb5 161 const size_t size = offsetof(struct filename, iname[1]);
7950e385
JL
162 kname = (char *)result;
163
fd2f7cb5
AV
164 /*
165 * size is chosen that way we to guarantee that
166 * result->iname[0] is within the same object and that
167 * kname can't be equal to result->iname, no matter what.
168 */
169 result = kzalloc(size, GFP_KERNEL);
94b5d262
AV
170 if (unlikely(!result)) {
171 __putname(kname);
172 return ERR_PTR(-ENOMEM);
7950e385
JL
173 }
174 result->name = kname;
94b5d262
AV
175 len = strncpy_from_user(kname, filename, PATH_MAX);
176 if (unlikely(len < 0)) {
177 __putname(kname);
178 kfree(result);
179 return ERR_PTR(len);
180 }
181 if (unlikely(len == PATH_MAX)) {
182 __putname(kname);
183 kfree(result);
184 return ERR_PTR(-ENAMETOOLONG);
185 }
7950e385
JL
186 }
187
94b5d262 188 result->refcnt = 1;
3f9f0aa6
LT
189 /* The empty path is special. */
190 if (unlikely(!len)) {
191 if (empty)
4043cde8 192 *empty = 1;
94b5d262
AV
193 if (!(flags & LOOKUP_EMPTY)) {
194 putname(result);
195 return ERR_PTR(-ENOENT);
196 }
1da177e4 197 }
3f9f0aa6 198
7950e385 199 result->uptr = filename;
c4ad8f98 200 result->aname = NULL;
7950e385
JL
201 audit_getname(result);
202 return result;
1da177e4
LT
203}
204
91a27b2a
JL
205struct filename *
206getname(const char __user * filename)
f52e0c11 207{
f7493e5d 208 return getname_flags(filename, 0, NULL);
f52e0c11
AV
209}
210
c4ad8f98
LT
211struct filename *
212getname_kernel(const char * filename)
213{
214 struct filename *result;
08518549 215 int len = strlen(filename) + 1;
c4ad8f98
LT
216
217 result = __getname();
218 if (unlikely(!result))
219 return ERR_PTR(-ENOMEM);
220
08518549 221 if (len <= EMBEDDED_NAME_MAX) {
fd2f7cb5 222 result->name = (char *)result->iname;
08518549
PM
223 } else if (len <= PATH_MAX) {
224 struct filename *tmp;
225
226 tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
227 if (unlikely(!tmp)) {
228 __putname(result);
229 return ERR_PTR(-ENOMEM);
230 }
231 tmp->name = (char *)result;
08518549
PM
232 result = tmp;
233 } else {
234 __putname(result);
235 return ERR_PTR(-ENAMETOOLONG);
236 }
237 memcpy((char *)result->name, filename, len);
c4ad8f98
LT
238 result->uptr = NULL;
239 result->aname = NULL;
55422d0b 240 result->refcnt = 1;
fd3522fd 241 audit_getname(result);
c4ad8f98 242
c4ad8f98
LT
243 return result;
244}
245
91a27b2a 246void putname(struct filename *name)
1da177e4 247{
55422d0b
PM
248 BUG_ON(name->refcnt <= 0);
249
250 if (--name->refcnt > 0)
251 return;
252
fd2f7cb5 253 if (name->name != name->iname) {
55422d0b
PM
254 __putname(name->name);
255 kfree(name);
256 } else
257 __putname(name);
1da177e4 258}
1da177e4 259
e77819e5
LT
260static int check_acl(struct inode *inode, int mask)
261{
84635d68 262#ifdef CONFIG_FS_POSIX_ACL
e77819e5
LT
263 struct posix_acl *acl;
264
e77819e5 265 if (mask & MAY_NOT_BLOCK) {
3567866b
AV
266 acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
267 if (!acl)
e77819e5 268 return -EAGAIN;
3567866b 269 /* no ->get_acl() calls in RCU mode... */
b8a7a3a6 270 if (is_uncached_acl(acl))
3567866b 271 return -ECHILD;
206b1d09 272 return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
e77819e5
LT
273 }
274
2982baa2
CH
275 acl = get_acl(inode, ACL_TYPE_ACCESS);
276 if (IS_ERR(acl))
277 return PTR_ERR(acl);
e77819e5
LT
278 if (acl) {
279 int error = posix_acl_permission(inode, acl, mask);
280 posix_acl_release(acl);
281 return error;
282 }
84635d68 283#endif
e77819e5
LT
284
285 return -EAGAIN;
286}
287
5909ccaa 288/*
948409c7 289 * This does the basic permission checking
1da177e4 290 */
7e40145e 291static int acl_permission_check(struct inode *inode, int mask)
1da177e4 292{
26cf46be 293 unsigned int mode = inode->i_mode;
1da177e4 294
8e96e3b7 295 if (likely(uid_eq(current_fsuid(), inode->i_uid)))
1da177e4
LT
296 mode >>= 6;
297 else {
e77819e5 298 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
7e40145e 299 int error = check_acl(inode, mask);
b74c79e9
NP
300 if (error != -EAGAIN)
301 return error;
1da177e4
LT
302 }
303
304 if (in_group_p(inode->i_gid))
305 mode >>= 3;
306 }
307
308 /*
309 * If the DACs are ok we don't need any capability check.
310 */
9c2c7039 311 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
1da177e4 312 return 0;
5909ccaa
LT
313 return -EACCES;
314}
315
316/**
b74c79e9 317 * generic_permission - check for access rights on a Posix-like filesystem
5909ccaa 318 * @inode: inode to check access rights for
8fd90c8d 319 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
5909ccaa
LT
320 *
321 * Used to check for read/write/execute permissions on a file.
322 * We use "fsuid" for this, letting us set arbitrary permissions
323 * for filesystem access without changing the "normal" uids which
b74c79e9
NP
324 * are used for other things.
325 *
326 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
327 * request cannot be satisfied (eg. requires blocking or too much complexity).
328 * It would then be called again in ref-walk mode.
5909ccaa 329 */
2830ba7f 330int generic_permission(struct inode *inode, int mask)
5909ccaa
LT
331{
332 int ret;
333
334 /*
948409c7 335 * Do the basic permission checks.
5909ccaa 336 */
7e40145e 337 ret = acl_permission_check(inode, mask);
5909ccaa
LT
338 if (ret != -EACCES)
339 return ret;
1da177e4 340
d594e7ec
AV
341 if (S_ISDIR(inode->i_mode)) {
342 /* DACs are overridable for directories */
23adbe12 343 if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
d594e7ec
AV
344 return 0;
345 if (!(mask & MAY_WRITE))
23adbe12
AL
346 if (capable_wrt_inode_uidgid(inode,
347 CAP_DAC_READ_SEARCH))
d594e7ec
AV
348 return 0;
349 return -EACCES;
350 }
1da177e4
LT
351 /*
352 * Read/write DACs are always overridable.
d594e7ec
AV
353 * Executable DACs are overridable when there is
354 * at least one exec bit set.
1da177e4 355 */
d594e7ec 356 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
23adbe12 357 if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
1da177e4
LT
358 return 0;
359
360 /*
361 * Searching includes executable on directories, else just read.
362 */
7ea66001 363 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
d594e7ec 364 if (mask == MAY_READ)
23adbe12 365 if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
1da177e4
LT
366 return 0;
367
368 return -EACCES;
369}
4d359507 370EXPORT_SYMBOL(generic_permission);
1da177e4 371
3ddcd056
LT
372/*
373 * We _really_ want to just do "generic_permission()" without
374 * even looking at the inode->i_op values. So we keep a cache
375 * flag in inode->i_opflags, that says "this has not special
376 * permission function, use the fast case".
377 */
378static inline int do_inode_permission(struct inode *inode, int mask)
379{
380 if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
381 if (likely(inode->i_op->permission))
382 return inode->i_op->permission(inode, mask);
383
384 /* This gets set once for the inode lifetime */
385 spin_lock(&inode->i_lock);
386 inode->i_opflags |= IOP_FASTPERM;
387 spin_unlock(&inode->i_lock);
388 }
389 return generic_permission(inode, mask);
390}
391
cb23beb5 392/**
0bdaea90
DH
393 * __inode_permission - Check for access rights to a given inode
394 * @inode: Inode to check permission on
395 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
cb23beb5 396 *
0bdaea90 397 * Check for read/write/execute permissions on an inode.
948409c7
AG
398 *
399 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
0bdaea90
DH
400 *
401 * This does not check for a read-only file system. You probably want
402 * inode_permission().
cb23beb5 403 */
0bdaea90 404int __inode_permission(struct inode *inode, int mask)
1da177e4 405{
e6305c43 406 int retval;
1da177e4 407
3ddcd056 408 if (unlikely(mask & MAY_WRITE)) {
1da177e4
LT
409 /*
410 * Nobody gets write access to an immutable file.
411 */
412 if (IS_IMMUTABLE(inode))
337684a1 413 return -EPERM;
0bd23d09
EB
414
415 /*
416 * Updating mtime will likely cause i_uid and i_gid to be
417 * written back improperly if their true value is unknown
418 * to the vfs.
419 */
420 if (HAS_UNMAPPED_ID(inode))
421 return -EACCES;
1da177e4
LT
422 }
423
3ddcd056 424 retval = do_inode_permission(inode, mask);
1da177e4
LT
425 if (retval)
426 return retval;
427
08ce5f16
SH
428 retval = devcgroup_inode_permission(inode, mask);
429 if (retval)
430 return retval;
431
d09ca739 432 return security_inode_permission(inode, mask);
1da177e4 433}
bd5d0856 434EXPORT_SYMBOL(__inode_permission);
1da177e4 435
0bdaea90
DH
436/**
437 * sb_permission - Check superblock-level permissions
438 * @sb: Superblock of inode to check permission on
55852635 439 * @inode: Inode to check permission on
0bdaea90
DH
440 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
441 *
442 * Separate out file-system wide checks from inode-specific permission checks.
443 */
444static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
445{
446 if (unlikely(mask & MAY_WRITE)) {
447 umode_t mode = inode->i_mode;
448
449 /* Nobody gets write access to a read-only fs. */
450 if ((sb->s_flags & MS_RDONLY) &&
451 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
452 return -EROFS;
453 }
454 return 0;
455}
456
457/**
458 * inode_permission - Check for access rights to a given inode
459 * @inode: Inode to check permission on
460 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
461 *
462 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
463 * this, letting us set arbitrary permissions for filesystem access without
464 * changing the "normal" UIDs which are used for other things.
465 *
466 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
467 */
468int inode_permission(struct inode *inode, int mask)
469{
470 int retval;
471
472 retval = sb_permission(inode->i_sb, inode, mask);
473 if (retval)
474 return retval;
475 return __inode_permission(inode, mask);
476}
4d359507 477EXPORT_SYMBOL(inode_permission);
0bdaea90 478
5dd784d0
JB
479/**
480 * path_get - get a reference to a path
481 * @path: path to get the reference to
482 *
483 * Given a path increment the reference count to the dentry and the vfsmount.
484 */
dcf787f3 485void path_get(const struct path *path)
5dd784d0
JB
486{
487 mntget(path->mnt);
488 dget(path->dentry);
489}
490EXPORT_SYMBOL(path_get);
491
1d957f9b
JB
492/**
493 * path_put - put a reference to a path
494 * @path: path to put the reference to
495 *
496 * Given a path decrement the reference count to the dentry and the vfsmount.
497 */
dcf787f3 498void path_put(const struct path *path)
1da177e4 499{
1d957f9b
JB
500 dput(path->dentry);
501 mntput(path->mnt);
1da177e4 502}
1d957f9b 503EXPORT_SYMBOL(path_put);
1da177e4 504
894bc8c4 505#define EMBEDDED_LEVELS 2
1f55a6ec
AV
506struct nameidata {
507 struct path path;
1cf2665b 508 struct qstr last;
1f55a6ec
AV
509 struct path root;
510 struct inode *inode; /* path.dentry.d_inode */
511 unsigned int flags;
9883d185 512 unsigned seq, m_seq;
1f55a6ec
AV
513 int last_type;
514 unsigned depth;
756daf26 515 int total_link_count;
697fc6ca
AV
516 struct saved {
517 struct path link;
fceef393 518 struct delayed_call done;
697fc6ca 519 const char *name;
0450b2d1 520 unsigned seq;
894bc8c4 521 } *stack, internal[EMBEDDED_LEVELS];
9883d185
AV
522 struct filename *name;
523 struct nameidata *saved;
fceef393 524 struct inode *link_inode;
9883d185
AV
525 unsigned root_seq;
526 int dfd;
1f55a6ec
AV
527};
528
9883d185 529static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
894bc8c4 530{
756daf26
N
531 struct nameidata *old = current->nameidata;
532 p->stack = p->internal;
c8a53ee5
AV
533 p->dfd = dfd;
534 p->name = name;
756daf26 535 p->total_link_count = old ? old->total_link_count : 0;
9883d185 536 p->saved = old;
756daf26 537 current->nameidata = p;
894bc8c4
AV
538}
539
9883d185 540static void restore_nameidata(void)
894bc8c4 541{
9883d185 542 struct nameidata *now = current->nameidata, *old = now->saved;
756daf26
N
543
544 current->nameidata = old;
545 if (old)
546 old->total_link_count = now->total_link_count;
e1a63bbc 547 if (now->stack != now->internal)
756daf26 548 kfree(now->stack);
894bc8c4
AV
549}
550
551static int __nd_alloc_stack(struct nameidata *nd)
552{
bc40aee0
AV
553 struct saved *p;
554
555 if (nd->flags & LOOKUP_RCU) {
556 p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
557 GFP_ATOMIC);
558 if (unlikely(!p))
559 return -ECHILD;
560 } else {
561 p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
894bc8c4 562 GFP_KERNEL);
bc40aee0
AV
563 if (unlikely(!p))
564 return -ENOMEM;
565 }
894bc8c4
AV
566 memcpy(p, nd->internal, sizeof(nd->internal));
567 nd->stack = p;
568 return 0;
569}
570
397d425d
EB
571/**
572 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
573 * @path: nameidate to verify
574 *
575 * Rename can sometimes move a file or directory outside of a bind
576 * mount, path_connected allows those cases to be detected.
577 */
578static bool path_connected(const struct path *path)
579{
580 struct vfsmount *mnt = path->mnt;
581
582 /* Only bind mounts can have disconnected paths */
583 if (mnt->mnt_root == mnt->mnt_sb->s_root)
584 return true;
585
586 return is_subdir(path->dentry, mnt->mnt_root);
587}
588
894bc8c4
AV
589static inline int nd_alloc_stack(struct nameidata *nd)
590{
da4e0be0 591 if (likely(nd->depth != EMBEDDED_LEVELS))
894bc8c4
AV
592 return 0;
593 if (likely(nd->stack != nd->internal))
594 return 0;
595 return __nd_alloc_stack(nd);
596}
597
7973387a
AV
598static void drop_links(struct nameidata *nd)
599{
600 int i = nd->depth;
601 while (i--) {
602 struct saved *last = nd->stack + i;
fceef393
AV
603 do_delayed_call(&last->done);
604 clear_delayed_call(&last->done);
7973387a
AV
605 }
606}
607
608static void terminate_walk(struct nameidata *nd)
609{
610 drop_links(nd);
611 if (!(nd->flags & LOOKUP_RCU)) {
612 int i;
613 path_put(&nd->path);
614 for (i = 0; i < nd->depth; i++)
615 path_put(&nd->stack[i].link);
102b8af2
AV
616 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
617 path_put(&nd->root);
618 nd->root.mnt = NULL;
619 }
7973387a
AV
620 } else {
621 nd->flags &= ~LOOKUP_RCU;
622 if (!(nd->flags & LOOKUP_ROOT))
623 nd->root.mnt = NULL;
624 rcu_read_unlock();
625 }
626 nd->depth = 0;
627}
628
629/* path_put is needed afterwards regardless of success or failure */
630static bool legitimize_path(struct nameidata *nd,
631 struct path *path, unsigned seq)
632{
633 int res = __legitimize_mnt(path->mnt, nd->m_seq);
634 if (unlikely(res)) {
635 if (res > 0)
636 path->mnt = NULL;
637 path->dentry = NULL;
638 return false;
639 }
640 if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
641 path->dentry = NULL;
642 return false;
643 }
644 return !read_seqcount_retry(&path->dentry->d_seq, seq);
645}
646
647static bool legitimize_links(struct nameidata *nd)
648{
649 int i;
650 for (i = 0; i < nd->depth; i++) {
651 struct saved *last = nd->stack + i;
652 if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
653 drop_links(nd);
654 nd->depth = i + 1;
655 return false;
656 }
657 }
658 return true;
659}
660
19660af7 661/*
31e6b01f 662 * Path walking has 2 modes, rcu-walk and ref-walk (see
19660af7
AV
663 * Documentation/filesystems/path-lookup.txt). In situations when we can't
664 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
57e3715c 665 * normal reference counts on dentries and vfsmounts to transition to ref-walk
19660af7
AV
666 * mode. Refcounts are grabbed at the last known good point before rcu-walk
667 * got stuck, so ref-walk may continue from there. If this is not successful
668 * (eg. a seqcount has changed), then failure is returned and it's up to caller
669 * to restart the path walk from the beginning in ref-walk mode.
31e6b01f 670 */
31e6b01f
NP
671
672/**
19660af7
AV
673 * unlazy_walk - try to switch to ref-walk mode.
674 * @nd: nameidata pathwalk data
675 * @dentry: child of nd->path.dentry or NULL
6e9918b7 676 * @seq: seq number to check dentry against
39191628 677 * Returns: 0 on success, -ECHILD on failure
31e6b01f 678 *
19660af7
AV
679 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
680 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
681 * @nd or NULL. Must be called from rcu-walk context.
7973387a
AV
682 * Nothing should touch nameidata between unlazy_walk() failure and
683 * terminate_walk().
31e6b01f 684 */
6e9918b7 685static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq)
31e6b01f 686{
31e6b01f
NP
687 struct dentry *parent = nd->path.dentry;
688
689 BUG_ON(!(nd->flags & LOOKUP_RCU));
e5c832d5 690
e5c832d5 691 nd->flags &= ~LOOKUP_RCU;
7973387a
AV
692 if (unlikely(!legitimize_links(nd)))
693 goto out2;
694 if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
695 goto out2;
696 if (unlikely(!lockref_get_not_dead(&parent->d_lockref)))
697 goto out1;
48a066e7 698
15570086
LT
699 /*
700 * For a negative lookup, the lookup sequence point is the parents
701 * sequence point, and it only needs to revalidate the parent dentry.
702 *
703 * For a positive lookup, we need to move both the parent and the
704 * dentry from the RCU domain to be properly refcounted. And the
705 * sequence number in the dentry validates *both* dentry counters,
706 * since we checked the sequence number of the parent after we got
707 * the child sequence number. So we know the parent must still
708 * be valid if the child sequence number is still valid.
709 */
19660af7 710 if (!dentry) {
e5c832d5
LT
711 if (read_seqcount_retry(&parent->d_seq, nd->seq))
712 goto out;
19660af7
AV
713 BUG_ON(nd->inode != parent->d_inode);
714 } else {
e5c832d5
LT
715 if (!lockref_get_not_dead(&dentry->d_lockref))
716 goto out;
6e9918b7 717 if (read_seqcount_retry(&dentry->d_seq, seq))
e5c832d5 718 goto drop_dentry;
19660af7 719 }
e5c832d5
LT
720
721 /*
722 * Sequence counts matched. Now make sure that the root is
723 * still valid and get it if required.
724 */
725 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
5a8d87e8
AV
726 if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) {
727 rcu_read_unlock();
728 dput(dentry);
729 return -ECHILD;
7973387a 730 }
31e6b01f 731 }
31e6b01f 732
8b61e74f 733 rcu_read_unlock();
31e6b01f 734 return 0;
19660af7 735
e5c832d5 736drop_dentry:
8b61e74f 737 rcu_read_unlock();
15570086 738 dput(dentry);
d0d27277 739 goto drop_root_mnt;
7973387a
AV
740out2:
741 nd->path.mnt = NULL;
742out1:
743 nd->path.dentry = NULL;
e5c832d5 744out:
8b61e74f 745 rcu_read_unlock();
d0d27277
LT
746drop_root_mnt:
747 if (!(nd->flags & LOOKUP_ROOT))
748 nd->root.mnt = NULL;
31e6b01f
NP
749 return -ECHILD;
750}
751
7973387a
AV
752static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq)
753{
754 if (unlikely(!legitimize_path(nd, link, seq))) {
755 drop_links(nd);
756 nd->depth = 0;
757 nd->flags &= ~LOOKUP_RCU;
758 nd->path.mnt = NULL;
759 nd->path.dentry = NULL;
760 if (!(nd->flags & LOOKUP_ROOT))
761 nd->root.mnt = NULL;
762 rcu_read_unlock();
763 } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) {
764 return 0;
765 }
766 path_put(link);
767 return -ECHILD;
768}
769
4ce16ef3 770static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
34286d66 771{
4ce16ef3 772 return dentry->d_op->d_revalidate(dentry, flags);
34286d66
NP
773}
774
9f1fafee
AV
775/**
776 * complete_walk - successful completion of path walk
777 * @nd: pointer nameidata
39159de2 778 *
9f1fafee
AV
779 * If we had been in RCU mode, drop out of it and legitimize nd->path.
780 * Revalidate the final result, unless we'd already done that during
781 * the path walk or the filesystem doesn't ask for it. Return 0 on
782 * success, -error on failure. In case of failure caller does not
783 * need to drop nd->path.
39159de2 784 */
9f1fafee 785static int complete_walk(struct nameidata *nd)
39159de2 786{
16c2cd71 787 struct dentry *dentry = nd->path.dentry;
39159de2 788 int status;
39159de2 789
9f1fafee 790 if (nd->flags & LOOKUP_RCU) {
9f1fafee
AV
791 if (!(nd->flags & LOOKUP_ROOT))
792 nd->root.mnt = NULL;
6e9918b7 793 if (unlikely(unlazy_walk(nd, NULL, 0)))
9f1fafee 794 return -ECHILD;
9f1fafee
AV
795 }
796
16c2cd71
AV
797 if (likely(!(nd->flags & LOOKUP_JUMPED)))
798 return 0;
799
ecf3d1f1 800 if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
39159de2
JL
801 return 0;
802
ecf3d1f1 803 status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
39159de2
JL
804 if (status > 0)
805 return 0;
806
16c2cd71 807 if (!status)
39159de2 808 status = -ESTALE;
16c2cd71 809
39159de2
JL
810 return status;
811}
812
18d8c860 813static void set_root(struct nameidata *nd)
31e6b01f 814{
7bd88377 815 struct fs_struct *fs = current->fs;
c28cc364 816
9e6697e2
AV
817 if (nd->flags & LOOKUP_RCU) {
818 unsigned seq;
819
820 do {
821 seq = read_seqcount_begin(&fs->seq);
822 nd->root = fs->root;
823 nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
824 } while (read_seqcount_retry(&fs->seq, seq));
825 } else {
826 get_fs_root(fs, &nd->root);
827 }
31e6b01f
NP
828}
829
1d957f9b 830static void path_put_conditional(struct path *path, struct nameidata *nd)
051d3812
IK
831{
832 dput(path->dentry);
4ac91378 833 if (path->mnt != nd->path.mnt)
051d3812
IK
834 mntput(path->mnt);
835}
836
7b9337aa
NP
837static inline void path_to_nameidata(const struct path *path,
838 struct nameidata *nd)
051d3812 839{
31e6b01f
NP
840 if (!(nd->flags & LOOKUP_RCU)) {
841 dput(nd->path.dentry);
842 if (nd->path.mnt != path->mnt)
843 mntput(nd->path.mnt);
9a229683 844 }
31e6b01f 845 nd->path.mnt = path->mnt;
4ac91378 846 nd->path.dentry = path->dentry;
051d3812
IK
847}
848
248fb5b9
AV
849static int nd_jump_root(struct nameidata *nd)
850{
851 if (nd->flags & LOOKUP_RCU) {
852 struct dentry *d;
853 nd->path = nd->root;
854 d = nd->path.dentry;
855 nd->inode = d->d_inode;
856 nd->seq = nd->root_seq;
857 if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
858 return -ECHILD;
859 } else {
860 path_put(&nd->path);
861 nd->path = nd->root;
862 path_get(&nd->path);
863 nd->inode = nd->path.dentry->d_inode;
864 }
865 nd->flags |= LOOKUP_JUMPED;
866 return 0;
867}
868
b5fb63c1 869/*
6b255391 870 * Helper to directly jump to a known parsed path from ->get_link,
b5fb63c1
CH
871 * caller must have taken a reference to path beforehand.
872 */
6e77137b 873void nd_jump_link(struct path *path)
b5fb63c1 874{
6e77137b 875 struct nameidata *nd = current->nameidata;
b5fb63c1
CH
876 path_put(&nd->path);
877
878 nd->path = *path;
879 nd->inode = nd->path.dentry->d_inode;
880 nd->flags |= LOOKUP_JUMPED;
b5fb63c1
CH
881}
882
b9ff4429 883static inline void put_link(struct nameidata *nd)
574197e0 884{
21c3003d 885 struct saved *last = nd->stack + --nd->depth;
fceef393 886 do_delayed_call(&last->done);
6548fae2
AV
887 if (!(nd->flags & LOOKUP_RCU))
888 path_put(&last->link);
574197e0
AV
889}
890
561ec64a
LT
891int sysctl_protected_symlinks __read_mostly = 0;
892int sysctl_protected_hardlinks __read_mostly = 0;
800179c9
KC
893
894/**
895 * may_follow_link - Check symlink following for unsafe situations
55852635 896 * @nd: nameidata pathwalk data
800179c9
KC
897 *
898 * In the case of the sysctl_protected_symlinks sysctl being enabled,
899 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
900 * in a sticky world-writable directory. This is to protect privileged
901 * processes from failing races against path names that may change out
902 * from under them by way of other users creating malicious symlinks.
903 * It will permit symlinks to be followed only when outside a sticky
904 * world-writable directory, or when the uid of the symlink and follower
905 * match, or when the directory owner matches the symlink's owner.
906 *
907 * Returns 0 if following the symlink is allowed, -ve on error.
908 */
fec2fa24 909static inline int may_follow_link(struct nameidata *nd)
800179c9
KC
910{
911 const struct inode *inode;
912 const struct inode *parent;
2d7f9e2a 913 kuid_t puid;
800179c9
KC
914
915 if (!sysctl_protected_symlinks)
916 return 0;
917
918 /* Allowed if owner and follower match. */
fceef393 919 inode = nd->link_inode;
81abe27b 920 if (uid_eq(current_cred()->fsuid, inode->i_uid))
800179c9
KC
921 return 0;
922
923 /* Allowed if parent directory not sticky and world-writable. */
aa65fa35 924 parent = nd->inode;
800179c9
KC
925 if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
926 return 0;
927
928 /* Allowed if parent directory and link owner match. */
2d7f9e2a
SF
929 puid = parent->i_uid;
930 if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
800179c9
KC
931 return 0;
932
31956502
AV
933 if (nd->flags & LOOKUP_RCU)
934 return -ECHILD;
935
1cf2665b 936 audit_log_link_denied("follow_link", &nd->stack[0].link);
800179c9
KC
937 return -EACCES;
938}
939
940/**
941 * safe_hardlink_source - Check for safe hardlink conditions
942 * @inode: the source inode to hardlink from
943 *
944 * Return false if at least one of the following conditions:
945 * - inode is not a regular file
946 * - inode is setuid
947 * - inode is setgid and group-exec
948 * - access failure for read and write
949 *
950 * Otherwise returns true.
951 */
952static bool safe_hardlink_source(struct inode *inode)
953{
954 umode_t mode = inode->i_mode;
955
956 /* Special files should not get pinned to the filesystem. */
957 if (!S_ISREG(mode))
958 return false;
959
960 /* Setuid files should not get pinned to the filesystem. */
961 if (mode & S_ISUID)
962 return false;
963
964 /* Executable setgid files should not get pinned to the filesystem. */
965 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
966 return false;
967
968 /* Hardlinking to unreadable or unwritable sources is dangerous. */
969 if (inode_permission(inode, MAY_READ | MAY_WRITE))
970 return false;
971
972 return true;
973}
974
975/**
976 * may_linkat - Check permissions for creating a hardlink
977 * @link: the source to hardlink from
978 *
979 * Block hardlink when all of:
980 * - sysctl_protected_hardlinks enabled
981 * - fsuid does not match inode
982 * - hardlink source is unsafe (see safe_hardlink_source() above)
f2ca3796 983 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
800179c9
KC
984 *
985 * Returns 0 if successful, -ve on error.
986 */
987static int may_linkat(struct path *link)
988{
800179c9
KC
989 struct inode *inode;
990
991 if (!sysctl_protected_hardlinks)
992 return 0;
993
800179c9
KC
994 inode = link->dentry->d_inode;
995
996 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
997 * otherwise, it must be a safe source.
998 */
f2ca3796 999 if (inode_owner_or_capable(inode) || safe_hardlink_source(inode))
800179c9
KC
1000 return 0;
1001
a51d9eaa 1002 audit_log_link_denied("linkat", link);
800179c9
KC
1003 return -EPERM;
1004}
1005
3b2e7f75
AV
1006static __always_inline
1007const char *get_link(struct nameidata *nd)
1da177e4 1008{
ab104923 1009 struct saved *last = nd->stack + nd->depth - 1;
1cf2665b 1010 struct dentry *dentry = last->link.dentry;
fceef393 1011 struct inode *inode = nd->link_inode;
6d7b5aae 1012 int error;
0a959df5 1013 const char *res;
1da177e4 1014
8fa9dd24
N
1015 if (!(nd->flags & LOOKUP_RCU)) {
1016 touch_atime(&last->link);
1017 cond_resched();
598e3c8f 1018 } else if (atime_needs_update_rcu(&last->link, inode)) {
bc40aee0
AV
1019 if (unlikely(unlazy_walk(nd, NULL, 0)))
1020 return ERR_PTR(-ECHILD);
8fa9dd24 1021 touch_atime(&last->link);
bc40aee0 1022 }
574197e0 1023
bda0be7a
N
1024 error = security_inode_follow_link(dentry, inode,
1025 nd->flags & LOOKUP_RCU);
1026 if (unlikely(error))
6920a440 1027 return ERR_PTR(error);
36f3b4f6 1028
86acdca1 1029 nd->last_type = LAST_BIND;
d4dee48b
AV
1030 res = inode->i_link;
1031 if (!res) {
fceef393
AV
1032 const char * (*get)(struct dentry *, struct inode *,
1033 struct delayed_call *);
1034 get = inode->i_op->get_link;
8c1b4566 1035 if (nd->flags & LOOKUP_RCU) {
fceef393 1036 res = get(NULL, inode, &last->done);
6b255391
AV
1037 if (res == ERR_PTR(-ECHILD)) {
1038 if (unlikely(unlazy_walk(nd, NULL, 0)))
1039 return ERR_PTR(-ECHILD);
fceef393 1040 res = get(dentry, inode, &last->done);
6b255391
AV
1041 }
1042 } else {
fceef393 1043 res = get(dentry, inode, &last->done);
8c1b4566 1044 }
fceef393 1045 if (IS_ERR_OR_NULL(res))
fab51e8a 1046 return res;
fab51e8a
AV
1047 }
1048 if (*res == '/') {
9e6697e2
AV
1049 if (!nd->root.mnt)
1050 set_root(nd);
248fb5b9
AV
1051 if (unlikely(nd_jump_root(nd)))
1052 return ERR_PTR(-ECHILD);
fab51e8a
AV
1053 while (unlikely(*++res == '/'))
1054 ;
1da177e4 1055 }
fab51e8a
AV
1056 if (!*res)
1057 res = NULL;
0a959df5
AV
1058 return res;
1059}
6d7b5aae 1060
f015f126
DH
1061/*
1062 * follow_up - Find the mountpoint of path's vfsmount
1063 *
1064 * Given a path, find the mountpoint of its source file system.
1065 * Replace @path with the path of the mountpoint in the parent mount.
1066 * Up is towards /.
1067 *
1068 * Return 1 if we went up a level and 0 if we were already at the
1069 * root.
1070 */
bab77ebf 1071int follow_up(struct path *path)
1da177e4 1072{
0714a533
AV
1073 struct mount *mnt = real_mount(path->mnt);
1074 struct mount *parent;
1da177e4 1075 struct dentry *mountpoint;
99b7db7b 1076
48a066e7 1077 read_seqlock_excl(&mount_lock);
0714a533 1078 parent = mnt->mnt_parent;
3c0a6163 1079 if (parent == mnt) {
48a066e7 1080 read_sequnlock_excl(&mount_lock);
1da177e4
LT
1081 return 0;
1082 }
0714a533 1083 mntget(&parent->mnt);
a73324da 1084 mountpoint = dget(mnt->mnt_mountpoint);
48a066e7 1085 read_sequnlock_excl(&mount_lock);
bab77ebf
AV
1086 dput(path->dentry);
1087 path->dentry = mountpoint;
1088 mntput(path->mnt);
0714a533 1089 path->mnt = &parent->mnt;
1da177e4
LT
1090 return 1;
1091}
4d359507 1092EXPORT_SYMBOL(follow_up);
1da177e4 1093
b5c84bf6 1094/*
9875cf80
DH
1095 * Perform an automount
1096 * - return -EISDIR to tell follow_managed() to stop and return the path we
1097 * were called with.
1da177e4 1098 */
756daf26 1099static int follow_automount(struct path *path, struct nameidata *nd,
9875cf80 1100 bool *need_mntput)
31e6b01f 1101{
9875cf80 1102 struct vfsmount *mnt;
aeaa4a79 1103 const struct cred *old_cred;
ea5b778a 1104 int err;
9875cf80
DH
1105
1106 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
1107 return -EREMOTE;
1108
0ec26fd0
MS
1109 /* We don't want to mount if someone's just doing a stat -
1110 * unless they're stat'ing a directory and appended a '/' to
1111 * the name.
1112 *
1113 * We do, however, want to mount if someone wants to open or
1114 * create a file of any type under the mountpoint, wants to
1115 * traverse through the mountpoint or wants to open the
1116 * mounted directory. Also, autofs may mark negative dentries
1117 * as being automount points. These will need the attentions
1118 * of the daemon to instantiate them before they can be used.
9875cf80 1119 */
756daf26
N
1120 if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
1121 LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
0ec26fd0
MS
1122 path->dentry->d_inode)
1123 return -EISDIR;
1124
aeaa4a79
EB
1125 if (path->dentry->d_sb->s_user_ns != &init_user_ns)
1126 return -EACCES;
1127
756daf26
N
1128 nd->total_link_count++;
1129 if (nd->total_link_count >= 40)
9875cf80
DH
1130 return -ELOOP;
1131
aeaa4a79 1132 old_cred = override_creds(&init_cred);
9875cf80 1133 mnt = path->dentry->d_op->d_automount(path);
aeaa4a79 1134 revert_creds(old_cred);
9875cf80
DH
1135 if (IS_ERR(mnt)) {
1136 /*
1137 * The filesystem is allowed to return -EISDIR here to indicate
1138 * it doesn't want to automount. For instance, autofs would do
1139 * this so that its userspace daemon can mount on this dentry.
1140 *
1141 * However, we can only permit this if it's a terminal point in
1142 * the path being looked up; if it wasn't then the remainder of
1143 * the path is inaccessible and we should say so.
1144 */
756daf26 1145 if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT))
9875cf80
DH
1146 return -EREMOTE;
1147 return PTR_ERR(mnt);
31e6b01f 1148 }
ea5b778a 1149
9875cf80
DH
1150 if (!mnt) /* mount collision */
1151 return 0;
31e6b01f 1152
8aef1884
AV
1153 if (!*need_mntput) {
1154 /* lock_mount() may release path->mnt on error */
1155 mntget(path->mnt);
1156 *need_mntput = true;
1157 }
19a167af 1158 err = finish_automount(mnt, path);
9875cf80 1159
ea5b778a
DH
1160 switch (err) {
1161 case -EBUSY:
1162 /* Someone else made a mount here whilst we were busy */
19a167af 1163 return 0;
ea5b778a 1164 case 0:
8aef1884 1165 path_put(path);
ea5b778a
DH
1166 path->mnt = mnt;
1167 path->dentry = dget(mnt->mnt_root);
ea5b778a 1168 return 0;
19a167af
AV
1169 default:
1170 return err;
ea5b778a 1171 }
19a167af 1172
463ffb2e
AV
1173}
1174
9875cf80
DH
1175/*
1176 * Handle a dentry that is managed in some way.
cc53ce53 1177 * - Flagged for transit management (autofs)
9875cf80
DH
1178 * - Flagged as mountpoint
1179 * - Flagged as automount point
1180 *
1181 * This may only be called in refwalk mode.
1182 *
1183 * Serialization is taken care of in namespace.c
1184 */
756daf26 1185static int follow_managed(struct path *path, struct nameidata *nd)
1da177e4 1186{
8aef1884 1187 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
9875cf80
DH
1188 unsigned managed;
1189 bool need_mntput = false;
8aef1884 1190 int ret = 0;
9875cf80
DH
1191
1192 /* Given that we're not holding a lock here, we retain the value in a
1193 * local variable for each dentry as we look at it so that we don't see
1194 * the components of that value change under us */
1195 while (managed = ACCESS_ONCE(path->dentry->d_flags),
1196 managed &= DCACHE_MANAGED_DENTRY,
1197 unlikely(managed != 0)) {
cc53ce53
DH
1198 /* Allow the filesystem to manage the transit without i_mutex
1199 * being held. */
1200 if (managed & DCACHE_MANAGE_TRANSIT) {
1201 BUG_ON(!path->dentry->d_op);
1202 BUG_ON(!path->dentry->d_op->d_manage);
1aed3e42 1203 ret = path->dentry->d_op->d_manage(path->dentry, false);
cc53ce53 1204 if (ret < 0)
8aef1884 1205 break;
cc53ce53
DH
1206 }
1207
9875cf80
DH
1208 /* Transit to a mounted filesystem. */
1209 if (managed & DCACHE_MOUNTED) {
1210 struct vfsmount *mounted = lookup_mnt(path);
1211 if (mounted) {
1212 dput(path->dentry);
1213 if (need_mntput)
1214 mntput(path->mnt);
1215 path->mnt = mounted;
1216 path->dentry = dget(mounted->mnt_root);
1217 need_mntput = true;
1218 continue;
1219 }
1220
1221 /* Something is mounted on this dentry in another
1222 * namespace and/or whatever was mounted there in this
48a066e7
AV
1223 * namespace got unmounted before lookup_mnt() could
1224 * get it */
9875cf80
DH
1225 }
1226
1227 /* Handle an automount point */
1228 if (managed & DCACHE_NEED_AUTOMOUNT) {
756daf26 1229 ret = follow_automount(path, nd, &need_mntput);
9875cf80 1230 if (ret < 0)
8aef1884 1231 break;
9875cf80
DH
1232 continue;
1233 }
1234
1235 /* We didn't change the current path point */
1236 break;
1da177e4 1237 }
8aef1884
AV
1238
1239 if (need_mntput && path->mnt == mnt)
1240 mntput(path->mnt);
e9742b53
AV
1241 if (ret == -EISDIR || !ret)
1242 ret = 1;
8402752e
AV
1243 if (need_mntput)
1244 nd->flags |= LOOKUP_JUMPED;
1245 if (unlikely(ret < 0))
1246 path_put_conditional(path, nd);
1247 return ret;
1da177e4
LT
1248}
1249
cc53ce53 1250int follow_down_one(struct path *path)
1da177e4
LT
1251{
1252 struct vfsmount *mounted;
1253
1c755af4 1254 mounted = lookup_mnt(path);
1da177e4 1255 if (mounted) {
9393bd07
AV
1256 dput(path->dentry);
1257 mntput(path->mnt);
1258 path->mnt = mounted;
1259 path->dentry = dget(mounted->mnt_root);
1da177e4
LT
1260 return 1;
1261 }
1262 return 0;
1263}
4d359507 1264EXPORT_SYMBOL(follow_down_one);
1da177e4 1265
b8faf035 1266static inline int managed_dentry_rcu(struct dentry *dentry)
62a7375e 1267{
b8faf035
N
1268 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
1269 dentry->d_op->d_manage(dentry, true) : 0;
62a7375e
IK
1270}
1271
9875cf80 1272/*
287548e4
AV
1273 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1274 * we meet a managed dentry that would need blocking.
9875cf80
DH
1275 */
1276static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
254cf582 1277 struct inode **inode, unsigned *seqp)
9875cf80 1278{
62a7375e 1279 for (;;) {
c7105365 1280 struct mount *mounted;
62a7375e
IK
1281 /*
1282 * Don't forget we might have a non-mountpoint managed dentry
1283 * that wants to block transit.
1284 */
b8faf035
N
1285 switch (managed_dentry_rcu(path->dentry)) {
1286 case -ECHILD:
1287 default:
ab90911f 1288 return false;
b8faf035
N
1289 case -EISDIR:
1290 return true;
1291 case 0:
1292 break;
1293 }
62a7375e
IK
1294
1295 if (!d_mountpoint(path->dentry))
b8faf035 1296 return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
62a7375e 1297
474279dc 1298 mounted = __lookup_mnt(path->mnt, path->dentry);
9875cf80
DH
1299 if (!mounted)
1300 break;
c7105365
AV
1301 path->mnt = &mounted->mnt;
1302 path->dentry = mounted->mnt.mnt_root;
a3fbbde7 1303 nd->flags |= LOOKUP_JUMPED;
254cf582 1304 *seqp = read_seqcount_begin(&path->dentry->d_seq);
59430262
LT
1305 /*
1306 * Update the inode too. We don't need to re-check the
1307 * dentry sequence number here after this d_inode read,
1308 * because a mount-point is always pinned.
1309 */
1310 *inode = path->dentry->d_inode;
9875cf80 1311 }
f5be3e29 1312 return !read_seqretry(&mount_lock, nd->m_seq) &&
b8faf035 1313 !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
287548e4
AV
1314}
1315
31e6b01f
NP
1316static int follow_dotdot_rcu(struct nameidata *nd)
1317{
4023bfc9 1318 struct inode *inode = nd->inode;
31e6b01f 1319
9875cf80 1320 while (1) {
aed434ad 1321 if (path_equal(&nd->path, &nd->root))
31e6b01f 1322 break;
31e6b01f
NP
1323 if (nd->path.dentry != nd->path.mnt->mnt_root) {
1324 struct dentry *old = nd->path.dentry;
1325 struct dentry *parent = old->d_parent;
1326 unsigned seq;
1327
4023bfc9 1328 inode = parent->d_inode;
31e6b01f 1329 seq = read_seqcount_begin(&parent->d_seq);
aed434ad
AV
1330 if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
1331 return -ECHILD;
31e6b01f
NP
1332 nd->path.dentry = parent;
1333 nd->seq = seq;
397d425d
EB
1334 if (unlikely(!path_connected(&nd->path)))
1335 return -ENOENT;
31e6b01f 1336 break;
aed434ad
AV
1337 } else {
1338 struct mount *mnt = real_mount(nd->path.mnt);
1339 struct mount *mparent = mnt->mnt_parent;
1340 struct dentry *mountpoint = mnt->mnt_mountpoint;
1341 struct inode *inode2 = mountpoint->d_inode;
1342 unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
1343 if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
1344 return -ECHILD;
1345 if (&mparent->mnt == nd->path.mnt)
1346 break;
1347 /* we know that mountpoint was pinned */
1348 nd->path.dentry = mountpoint;
1349 nd->path.mnt = &mparent->mnt;
1350 inode = inode2;
1351 nd->seq = seq;
31e6b01f 1352 }
31e6b01f 1353 }
aed434ad 1354 while (unlikely(d_mountpoint(nd->path.dentry))) {
b37199e6
AV
1355 struct mount *mounted;
1356 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
aed434ad
AV
1357 if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
1358 return -ECHILD;
b37199e6
AV
1359 if (!mounted)
1360 break;
1361 nd->path.mnt = &mounted->mnt;
1362 nd->path.dentry = mounted->mnt.mnt_root;
4023bfc9 1363 inode = nd->path.dentry->d_inode;
b37199e6 1364 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
b37199e6 1365 }
4023bfc9 1366 nd->inode = inode;
31e6b01f
NP
1367 return 0;
1368}
1369
cc53ce53
DH
1370/*
1371 * Follow down to the covering mount currently visible to userspace. At each
1372 * point, the filesystem owning that dentry may be queried as to whether the
1373 * caller is permitted to proceed or not.
cc53ce53 1374 */
7cc90cc3 1375int follow_down(struct path *path)
cc53ce53
DH
1376{
1377 unsigned managed;
1378 int ret;
1379
1380 while (managed = ACCESS_ONCE(path->dentry->d_flags),
1381 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
1382 /* Allow the filesystem to manage the transit without i_mutex
1383 * being held.
1384 *
1385 * We indicate to the filesystem if someone is trying to mount
1386 * something here. This gives autofs the chance to deny anyone
1387 * other than its daemon the right to mount on its
1388 * superstructure.
1389 *
1390 * The filesystem may sleep at this point.
1391 */
1392 if (managed & DCACHE_MANAGE_TRANSIT) {
1393 BUG_ON(!path->dentry->d_op);
1394 BUG_ON(!path->dentry->d_op->d_manage);
ab90911f 1395 ret = path->dentry->d_op->d_manage(
1aed3e42 1396 path->dentry, false);
cc53ce53
DH
1397 if (ret < 0)
1398 return ret == -EISDIR ? 0 : ret;
1399 }
1400
1401 /* Transit to a mounted filesystem. */
1402 if (managed & DCACHE_MOUNTED) {
1403 struct vfsmount *mounted = lookup_mnt(path);
1404 if (!mounted)
1405 break;
1406 dput(path->dentry);
1407 mntput(path->mnt);
1408 path->mnt = mounted;
1409 path->dentry = dget(mounted->mnt_root);
1410 continue;
1411 }
1412
1413 /* Don't handle automount points here */
1414 break;
1415 }
1416 return 0;
1417}
4d359507 1418EXPORT_SYMBOL(follow_down);
cc53ce53 1419
9875cf80
DH
1420/*
1421 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1422 */
1423static void follow_mount(struct path *path)
1424{
1425 while (d_mountpoint(path->dentry)) {
1426 struct vfsmount *mounted = lookup_mnt(path);
1427 if (!mounted)
1428 break;
1429 dput(path->dentry);
1430 mntput(path->mnt);
1431 path->mnt = mounted;
1432 path->dentry = dget(mounted->mnt_root);
1433 }
1434}
1435
eedf265a
EB
1436static int path_parent_directory(struct path *path)
1437{
1438 struct dentry *old = path->dentry;
1439 /* rare case of legitimate dget_parent()... */
1440 path->dentry = dget_parent(path->dentry);
1441 dput(old);
1442 if (unlikely(!path_connected(path)))
1443 return -ENOENT;
1444 return 0;
1445}
1446
397d425d 1447static int follow_dotdot(struct nameidata *nd)
1da177e4
LT
1448{
1449 while(1) {
2a737871
AV
1450 if (nd->path.dentry == nd->root.dentry &&
1451 nd->path.mnt == nd->root.mnt) {
1da177e4
LT
1452 break;
1453 }
4ac91378 1454 if (nd->path.dentry != nd->path.mnt->mnt_root) {
eedf265a
EB
1455 int ret = path_parent_directory(&nd->path);
1456 if (ret)
1457 return ret;
1da177e4
LT
1458 break;
1459 }
3088dd70 1460 if (!follow_up(&nd->path))
1da177e4 1461 break;
1da177e4 1462 }
79ed0226 1463 follow_mount(&nd->path);
31e6b01f 1464 nd->inode = nd->path.dentry->d_inode;
397d425d 1465 return 0;
1da177e4
LT
1466}
1467
baa03890 1468/*
f4fdace9
OD
1469 * This looks up the name in dcache and possibly revalidates the found dentry.
1470 * NULL is returned if the dentry does not exist in the cache.
baa03890 1471 */
e3c13928
AV
1472static struct dentry *lookup_dcache(const struct qstr *name,
1473 struct dentry *dir,
6c51e513 1474 unsigned int flags)
baa03890 1475{
baa03890 1476 struct dentry *dentry;
bad61189 1477 int error;
baa03890 1478
bad61189
MS
1479 dentry = d_lookup(dir, name);
1480 if (dentry) {
39e3c955 1481 if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
201f956e 1482 error = d_revalidate(dentry, flags);
bad61189 1483 if (unlikely(error <= 0)) {
74ff0ffc 1484 if (!error)
5542aa2f 1485 d_invalidate(dentry);
74ff0ffc
AV
1486 dput(dentry);
1487 return ERR_PTR(error);
bad61189
MS
1488 }
1489 }
1490 }
baa03890
NP
1491 return dentry;
1492}
1493
44396f4b 1494/*
13a2c3be
BF
1495 * Call i_op->lookup on the dentry. The dentry must be negative and
1496 * unhashed.
bad61189
MS
1497 *
1498 * dir->d_inode->i_mutex must be held
44396f4b 1499 */
bad61189 1500static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
72bd866a 1501 unsigned int flags)
44396f4b 1502{
44396f4b
JB
1503 struct dentry *old;
1504
1505 /* Don't create child dentry for a dead directory. */
bad61189 1506 if (unlikely(IS_DEADDIR(dir))) {
e188dc02 1507 dput(dentry);
44396f4b 1508 return ERR_PTR(-ENOENT);
e188dc02 1509 }
44396f4b 1510
72bd866a 1511 old = dir->i_op->lookup(dir, dentry, flags);
44396f4b
JB
1512 if (unlikely(old)) {
1513 dput(dentry);
1514 dentry = old;
1515 }
1516 return dentry;
1517}
1518
e3c13928 1519static struct dentry *__lookup_hash(const struct qstr *name,
72bd866a 1520 struct dentry *base, unsigned int flags)
a3255546 1521{
6c51e513 1522 struct dentry *dentry = lookup_dcache(name, base, flags);
a3255546 1523
6c51e513 1524 if (dentry)
bad61189 1525 return dentry;
a3255546 1526
6c51e513
AV
1527 dentry = d_alloc(base, name);
1528 if (unlikely(!dentry))
1529 return ERR_PTR(-ENOMEM);
1530
72bd866a 1531 return lookup_real(base->d_inode, dentry, flags);
a3255546
AV
1532}
1533
e97cdc87 1534static int lookup_fast(struct nameidata *nd,
254cf582
AV
1535 struct path *path, struct inode **inode,
1536 unsigned *seqp)
1da177e4 1537{
4ac91378 1538 struct vfsmount *mnt = nd->path.mnt;
31e6b01f 1539 struct dentry *dentry, *parent = nd->path.dentry;
5a18fff2 1540 int status = 1;
9875cf80
DH
1541 int err;
1542
b04f784e
NP
1543 /*
1544 * Rename seqlock is not required here because in the off chance
5d0f49c1
AV
1545 * of a false negative due to a concurrent rename, the caller is
1546 * going to fall back to non-racy lookup.
b04f784e 1547 */
31e6b01f
NP
1548 if (nd->flags & LOOKUP_RCU) {
1549 unsigned seq;
766c4cbf 1550 bool negative;
da53be12 1551 dentry = __d_lookup_rcu(parent, &nd->last, &seq);
5d0f49c1
AV
1552 if (unlikely(!dentry)) {
1553 if (unlazy_walk(nd, NULL, 0))
1554 return -ECHILD;
e9742b53 1555 return 0;
5d0f49c1 1556 }
5a18fff2 1557
12f8ad4b
LT
1558 /*
1559 * This sequence count validates that the inode matches
1560 * the dentry name information from lookup.
1561 */
63afdfc7 1562 *inode = d_backing_inode(dentry);
766c4cbf 1563 negative = d_is_negative(dentry);
5d0f49c1 1564 if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
12f8ad4b
LT
1565 return -ECHILD;
1566
1567 /*
1568 * This sequence count validates that the parent had no
1569 * changes while we did the lookup of the dentry above.
1570 *
1571 * The memory barrier in read_seqcount_begin of child is
1572 * enough, we can use __read_seqcount_retry here.
1573 */
5d0f49c1 1574 if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
31e6b01f 1575 return -ECHILD;
5a18fff2 1576
254cf582 1577 *seqp = seq;
5d0f49c1 1578 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
4ce16ef3 1579 status = d_revalidate(dentry, nd->flags);
5d0f49c1
AV
1580 if (unlikely(status <= 0)) {
1581 if (unlazy_walk(nd, dentry, seq))
1582 return -ECHILD;
1583 if (status == -ECHILD)
1584 status = d_revalidate(dentry, nd->flags);
1585 } else {
1586 /*
1587 * Note: do negative dentry check after revalidation in
1588 * case that drops it.
1589 */
1590 if (unlikely(negative))
1591 return -ENOENT;
1592 path->mnt = mnt;
1593 path->dentry = dentry;
1594 if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
e9742b53 1595 return 1;
5d0f49c1
AV
1596 if (unlazy_walk(nd, dentry, seq))
1597 return -ECHILD;
24643087 1598 }
5a18fff2 1599 } else {
e97cdc87 1600 dentry = __d_lookup(parent, &nd->last);
5d0f49c1 1601 if (unlikely(!dentry))
e9742b53 1602 return 0;
5d0f49c1
AV
1603 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
1604 status = d_revalidate(dentry, nd->flags);
9875cf80 1605 }
5a18fff2 1606 if (unlikely(status <= 0)) {
e9742b53 1607 if (!status)
5d0f49c1 1608 d_invalidate(dentry);
5542aa2f 1609 dput(dentry);
5d0f49c1 1610 return status;
24643087 1611 }
766c4cbf
AV
1612 if (unlikely(d_is_negative(dentry))) {
1613 dput(dentry);
1614 return -ENOENT;
1615 }
5d0f49c1 1616
9875cf80
DH
1617 path->mnt = mnt;
1618 path->dentry = dentry;
756daf26 1619 err = follow_managed(path, nd);
e9742b53 1620 if (likely(err > 0))
63afdfc7 1621 *inode = d_backing_inode(path->dentry);
8402752e 1622 return err;
697f514d
MS
1623}
1624
1625/* Fast lookup failed, do it the slow way */
e3c13928
AV
1626static struct dentry *lookup_slow(const struct qstr *name,
1627 struct dentry *dir,
1628 unsigned int flags)
697f514d 1629{
94bdd655 1630 struct dentry *dentry = ERR_PTR(-ENOENT), *old;
1936386e 1631 struct inode *inode = dir->d_inode;
d9171b93 1632 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1936386e 1633
9902af79 1634 inode_lock_shared(inode);
1936386e 1635 /* Don't go there if it's already dead */
94bdd655
AV
1636 if (unlikely(IS_DEADDIR(inode)))
1637 goto out;
1638again:
d9171b93 1639 dentry = d_alloc_parallel(dir, name, &wq);
94bdd655
AV
1640 if (IS_ERR(dentry))
1641 goto out;
1642 if (unlikely(!d_in_lookup(dentry))) {
949a852e
AV
1643 if ((dentry->d_flags & DCACHE_OP_REVALIDATE) &&
1644 !(flags & LOOKUP_NO_REVAL)) {
1645 int error = d_revalidate(dentry, flags);
1646 if (unlikely(error <= 0)) {
94bdd655 1647 if (!error) {
949a852e 1648 d_invalidate(dentry);
94bdd655
AV
1649 dput(dentry);
1650 goto again;
1651 }
949a852e
AV
1652 dput(dentry);
1653 dentry = ERR_PTR(error);
1654 }
1655 }
94bdd655
AV
1656 } else {
1657 old = inode->i_op->lookup(inode, dentry, flags);
1658 d_lookup_done(dentry);
1659 if (unlikely(old)) {
1660 dput(dentry);
1661 dentry = old;
949a852e
AV
1662 }
1663 }
94bdd655 1664out:
9902af79 1665 inode_unlock_shared(inode);
e3c13928 1666 return dentry;
1da177e4
LT
1667}
1668
52094c8a
AV
1669static inline int may_lookup(struct nameidata *nd)
1670{
1671 if (nd->flags & LOOKUP_RCU) {
4ad5abb3 1672 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
52094c8a
AV
1673 if (err != -ECHILD)
1674 return err;
6e9918b7 1675 if (unlazy_walk(nd, NULL, 0))
52094c8a
AV
1676 return -ECHILD;
1677 }
4ad5abb3 1678 return inode_permission(nd->inode, MAY_EXEC);
52094c8a
AV
1679}
1680
9856fa1b
AV
1681static inline int handle_dots(struct nameidata *nd, int type)
1682{
1683 if (type == LAST_DOTDOT) {
9e6697e2
AV
1684 if (!nd->root.mnt)
1685 set_root(nd);
9856fa1b 1686 if (nd->flags & LOOKUP_RCU) {
70291aec 1687 return follow_dotdot_rcu(nd);
9856fa1b 1688 } else
397d425d 1689 return follow_dotdot(nd);
9856fa1b
AV
1690 }
1691 return 0;
1692}
1693
181548c0
AV
1694static int pick_link(struct nameidata *nd, struct path *link,
1695 struct inode *inode, unsigned seq)
d63ff28f 1696{
626de996 1697 int error;
1cf2665b 1698 struct saved *last;
756daf26 1699 if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
626de996
AV
1700 path_to_nameidata(link, nd);
1701 return -ELOOP;
1702 }
bc40aee0 1703 if (!(nd->flags & LOOKUP_RCU)) {
7973387a
AV
1704 if (link->mnt == nd->path.mnt)
1705 mntget(link->mnt);
d63ff28f 1706 }
626de996
AV
1707 error = nd_alloc_stack(nd);
1708 if (unlikely(error)) {
bc40aee0
AV
1709 if (error == -ECHILD) {
1710 if (unlikely(unlazy_link(nd, link, seq)))
1711 return -ECHILD;
1712 error = nd_alloc_stack(nd);
1713 }
1714 if (error) {
1715 path_put(link);
1716 return error;
1717 }
626de996
AV
1718 }
1719
ab104923 1720 last = nd->stack + nd->depth++;
1cf2665b 1721 last->link = *link;
fceef393
AV
1722 clear_delayed_call(&last->done);
1723 nd->link_inode = inode;
0450b2d1 1724 last->seq = seq;
d63ff28f
AV
1725 return 1;
1726}
1727
3ddcd056
LT
1728/*
1729 * Do we need to follow links? We _really_ want to be able
1730 * to do this check without having to look at inode->i_op,
1731 * so we keep a cache of "no, this doesn't need follow_link"
1732 * for the common case.
1733 */
254cf582 1734static inline int should_follow_link(struct nameidata *nd, struct path *link,
181548c0
AV
1735 int follow,
1736 struct inode *inode, unsigned seq)
3ddcd056 1737{
d63ff28f
AV
1738 if (likely(!d_is_symlink(link->dentry)))
1739 return 0;
1740 if (!follow)
1741 return 0;
a7f77542
AV
1742 /* make sure that d_is_symlink above matches inode */
1743 if (nd->flags & LOOKUP_RCU) {
1744 if (read_seqcount_retry(&link->dentry->d_seq, seq))
1745 return -ECHILD;
1746 }
181548c0 1747 return pick_link(nd, link, inode, seq);
3ddcd056
LT
1748}
1749
4693a547
AV
1750enum {WALK_GET = 1, WALK_PUT = 2};
1751
1752static int walk_component(struct nameidata *nd, int flags)
ce57dfc1 1753{
caa85634 1754 struct path path;
ce57dfc1 1755 struct inode *inode;
254cf582 1756 unsigned seq;
ce57dfc1
AV
1757 int err;
1758 /*
1759 * "." and ".." are special - ".." especially so because it has
1760 * to be able to know about the current root directory and
1761 * parent relationships.
1762 */
4693a547
AV
1763 if (unlikely(nd->last_type != LAST_NORM)) {
1764 err = handle_dots(nd, nd->last_type);
1765 if (flags & WALK_PUT)
1766 put_link(nd);
1767 return err;
1768 }
254cf582 1769 err = lookup_fast(nd, &path, &inode, &seq);
e9742b53 1770 if (unlikely(err <= 0)) {
697f514d 1771 if (err < 0)
f0a9ba70 1772 return err;
e3c13928
AV
1773 path.dentry = lookup_slow(&nd->last, nd->path.dentry,
1774 nd->flags);
1775 if (IS_ERR(path.dentry))
1776 return PTR_ERR(path.dentry);
7500c38a 1777
e3c13928
AV
1778 path.mnt = nd->path.mnt;
1779 err = follow_managed(&path, nd);
1780 if (unlikely(err < 0))
f0a9ba70 1781 return err;
697f514d 1782
7500c38a
AV
1783 if (unlikely(d_is_negative(path.dentry))) {
1784 path_to_nameidata(&path, nd);
1785 return -ENOENT;
1786 }
1787
254cf582 1788 seq = 0; /* we are already out of RCU mode */
d4565649 1789 inode = d_backing_inode(path.dentry);
ce57dfc1 1790 }
697f514d 1791
4693a547
AV
1792 if (flags & WALK_PUT)
1793 put_link(nd);
181548c0 1794 err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq);
d63ff28f
AV
1795 if (unlikely(err))
1796 return err;
caa85634 1797 path_to_nameidata(&path, nd);
ce57dfc1 1798 nd->inode = inode;
254cf582 1799 nd->seq = seq;
ce57dfc1
AV
1800 return 0;
1801}
1802
bfcfaa77
LT
1803/*
1804 * We can do the critical dentry name comparison and hashing
1805 * operations one word at a time, but we are limited to:
1806 *
1807 * - Architectures with fast unaligned word accesses. We could
1808 * do a "get_unaligned()" if this helps and is sufficiently
1809 * fast.
1810 *
bfcfaa77
LT
1811 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1812 * do not trap on the (extremely unlikely) case of a page
1813 * crossing operation.
1814 *
1815 * - Furthermore, we need an efficient 64-bit compile for the
1816 * 64-bit case in order to generate the "number of bytes in
1817 * the final mask". Again, that could be replaced with a
1818 * efficient population count instruction or similar.
1819 */
1820#ifdef CONFIG_DCACHE_WORD_ACCESS
1821
f68e556e 1822#include <asm/word-at-a-time.h>
bfcfaa77 1823
468a9428 1824#ifdef HASH_MIX
bfcfaa77 1825
468a9428 1826/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
bfcfaa77 1827
468a9428 1828#elif defined(CONFIG_64BIT)
0fed3ac8 1829/*
2a18da7a
GS
1830 * Register pressure in the mixing function is an issue, particularly
1831 * on 32-bit x86, but almost any function requires one state value and
1832 * one temporary. Instead, use a function designed for two state values
1833 * and no temporaries.
1834 *
1835 * This function cannot create a collision in only two iterations, so
1836 * we have two iterations to achieve avalanche. In those two iterations,
1837 * we have six layers of mixing, which is enough to spread one bit's
1838 * influence out to 2^6 = 64 state bits.
1839 *
1840 * Rotate constants are scored by considering either 64 one-bit input
1841 * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
1842 * probability of that delta causing a change to each of the 128 output
1843 * bits, using a sample of random initial states.
1844 *
1845 * The Shannon entropy of the computed probabilities is then summed
1846 * to produce a score. Ideally, any input change has a 50% chance of
1847 * toggling any given output bit.
1848 *
1849 * Mixing scores (in bits) for (12,45):
1850 * Input delta: 1-bit 2-bit
1851 * 1 round: 713.3 42542.6
1852 * 2 rounds: 2753.7 140389.8
1853 * 3 rounds: 5954.1 233458.2
1854 * 4 rounds: 7862.6 256672.2
1855 * Perfect: 8192 258048
1856 * (64*128) (64*63/2 * 128)
0fed3ac8 1857 */
2a18da7a
GS
1858#define HASH_MIX(x, y, a) \
1859 ( x ^= (a), \
1860 y ^= x, x = rol64(x,12),\
1861 x += y, y = rol64(y,45),\
1862 y *= 9 )
bfcfaa77 1863
0fed3ac8 1864/*
2a18da7a
GS
1865 * Fold two longs into one 32-bit hash value. This must be fast, but
1866 * latency isn't quite as critical, as there is a fair bit of additional
1867 * work done before the hash value is used.
0fed3ac8 1868 */
2a18da7a 1869static inline unsigned int fold_hash(unsigned long x, unsigned long y)
0fed3ac8 1870{
2a18da7a
GS
1871 y ^= x * GOLDEN_RATIO_64;
1872 y *= GOLDEN_RATIO_64;
1873 return y >> 32;
0fed3ac8
GS
1874}
1875
bfcfaa77
LT
1876#else /* 32-bit case */
1877
2a18da7a
GS
1878/*
1879 * Mixing scores (in bits) for (7,20):
1880 * Input delta: 1-bit 2-bit
1881 * 1 round: 330.3 9201.6
1882 * 2 rounds: 1246.4 25475.4
1883 * 3 rounds: 1907.1 31295.1
1884 * 4 rounds: 2042.3 31718.6
1885 * Perfect: 2048 31744
1886 * (32*64) (32*31/2 * 64)
1887 */
1888#define HASH_MIX(x, y, a) \
1889 ( x ^= (a), \
1890 y ^= x, x = rol32(x, 7),\
1891 x += y, y = rol32(y,20),\
1892 y *= 9 )
bfcfaa77 1893
2a18da7a 1894static inline unsigned int fold_hash(unsigned long x, unsigned long y)
0fed3ac8 1895{
2a18da7a
GS
1896 /* Use arch-optimized multiply if one exists */
1897 return __hash_32(y ^ __hash_32(x));
0fed3ac8
GS
1898}
1899
bfcfaa77
LT
1900#endif
1901
2a18da7a
GS
1902/*
1903 * Return the hash of a string of known length. This is carfully
1904 * designed to match hash_name(), which is the more critical function.
1905 * In particular, we must end by hashing a final word containing 0..7
1906 * payload bytes, to match the way that hash_name() iterates until it
1907 * finds the delimiter after the name.
1908 */
8387ff25 1909unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
bfcfaa77 1910{
8387ff25 1911 unsigned long a, x = 0, y = (unsigned long)salt;
bfcfaa77
LT
1912
1913 for (;;) {
fcfd2fbf
GS
1914 if (!len)
1915 goto done;
e419b4cc 1916 a = load_unaligned_zeropad(name);
bfcfaa77
LT
1917 if (len < sizeof(unsigned long))
1918 break;
2a18da7a 1919 HASH_MIX(x, y, a);
bfcfaa77
LT
1920 name += sizeof(unsigned long);
1921 len -= sizeof(unsigned long);
bfcfaa77 1922 }
2a18da7a 1923 x ^= a & bytemask_from_count(len);
bfcfaa77 1924done:
2a18da7a 1925 return fold_hash(x, y);
bfcfaa77
LT
1926}
1927EXPORT_SYMBOL(full_name_hash);
1928
fcfd2fbf 1929/* Return the "hash_len" (hash and length) of a null-terminated string */
8387ff25 1930u64 hashlen_string(const void *salt, const char *name)
fcfd2fbf 1931{
8387ff25
LT
1932 unsigned long a = 0, x = 0, y = (unsigned long)salt;
1933 unsigned long adata, mask, len;
fcfd2fbf
GS
1934 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
1935
8387ff25
LT
1936 len = 0;
1937 goto inside;
1938
fcfd2fbf 1939 do {
2a18da7a 1940 HASH_MIX(x, y, a);
fcfd2fbf 1941 len += sizeof(unsigned long);
8387ff25 1942inside:
fcfd2fbf
GS
1943 a = load_unaligned_zeropad(name+len);
1944 } while (!has_zero(a, &adata, &constants));
1945
1946 adata = prep_zero_mask(a, adata, &constants);
1947 mask = create_zero_mask(adata);
2a18da7a 1948 x ^= a & zero_bytemask(mask);
fcfd2fbf 1949
2a18da7a 1950 return hashlen_create(fold_hash(x, y), len + find_zero(mask));
fcfd2fbf
GS
1951}
1952EXPORT_SYMBOL(hashlen_string);
1953
bfcfaa77
LT
1954/*
1955 * Calculate the length and hash of the path component, and
d6bb3e90 1956 * return the "hash_len" as the result.
bfcfaa77 1957 */
8387ff25 1958static inline u64 hash_name(const void *salt, const char *name)
bfcfaa77 1959{
8387ff25
LT
1960 unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
1961 unsigned long adata, bdata, mask, len;
36126f8f 1962 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
bfcfaa77 1963
8387ff25
LT
1964 len = 0;
1965 goto inside;
1966
bfcfaa77 1967 do {
2a18da7a 1968 HASH_MIX(x, y, a);
bfcfaa77 1969 len += sizeof(unsigned long);
8387ff25 1970inside:
e419b4cc 1971 a = load_unaligned_zeropad(name+len);
36126f8f
LT
1972 b = a ^ REPEAT_BYTE('/');
1973 } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
1974
1975 adata = prep_zero_mask(a, adata, &constants);
1976 bdata = prep_zero_mask(b, bdata, &constants);
36126f8f 1977 mask = create_zero_mask(adata | bdata);
2a18da7a 1978 x ^= a & zero_bytemask(mask);
36126f8f 1979
2a18da7a 1980 return hashlen_create(fold_hash(x, y), len + find_zero(mask));
bfcfaa77
LT
1981}
1982
2a18da7a 1983#else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
bfcfaa77 1984
fcfd2fbf 1985/* Return the hash of a string of known length */
8387ff25 1986unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
0145acc2 1987{
8387ff25 1988 unsigned long hash = init_name_hash(salt);
0145acc2 1989 while (len--)
fcfd2fbf 1990 hash = partial_name_hash((unsigned char)*name++, hash);
0145acc2
LT
1991 return end_name_hash(hash);
1992}
ae942ae7 1993EXPORT_SYMBOL(full_name_hash);
0145acc2 1994
fcfd2fbf 1995/* Return the "hash_len" (hash and length) of a null-terminated string */
8387ff25 1996u64 hashlen_string(const void *salt, const char *name)
fcfd2fbf 1997{
8387ff25 1998 unsigned long hash = init_name_hash(salt);
fcfd2fbf
GS
1999 unsigned long len = 0, c;
2000
2001 c = (unsigned char)*name;
e0ab7af9 2002 while (c) {
fcfd2fbf
GS
2003 len++;
2004 hash = partial_name_hash(c, hash);
2005 c = (unsigned char)name[len];
e0ab7af9 2006 }
fcfd2fbf
GS
2007 return hashlen_create(end_name_hash(hash), len);
2008}
f2a031b6 2009EXPORT_SYMBOL(hashlen_string);
fcfd2fbf 2010
200e9ef7
LT
2011/*
2012 * We know there's a real path component here of at least
2013 * one character.
2014 */
8387ff25 2015static inline u64 hash_name(const void *salt, const char *name)
200e9ef7 2016{
8387ff25 2017 unsigned long hash = init_name_hash(salt);
200e9ef7
LT
2018 unsigned long len = 0, c;
2019
2020 c = (unsigned char)*name;
2021 do {
2022 len++;
2023 hash = partial_name_hash(c, hash);
2024 c = (unsigned char)name[len];
2025 } while (c && c != '/');
d6bb3e90 2026 return hashlen_create(end_name_hash(hash), len);
200e9ef7
LT
2027}
2028
bfcfaa77
LT
2029#endif
2030
1da177e4
LT
2031/*
2032 * Name resolution.
ea3834d9
PM
2033 * This is the basic name resolution function, turning a pathname into
2034 * the final dentry. We expect 'base' to be positive and a directory.
1da177e4 2035 *
ea3834d9
PM
2036 * Returns 0 and nd will have valid dentry and mnt on success.
2037 * Returns error and drops reference to input namei data on failure.
1da177e4 2038 */
6de88d72 2039static int link_path_walk(const char *name, struct nameidata *nd)
1da177e4 2040{
1da177e4 2041 int err;
32cd7468 2042
1da177e4
LT
2043 while (*name=='/')
2044 name++;
2045 if (!*name)
9e18f10a 2046 return 0;
1da177e4 2047
1da177e4
LT
2048 /* At this point we know we have a real path component. */
2049 for(;;) {
d6bb3e90 2050 u64 hash_len;
fe479a58 2051 int type;
1da177e4 2052
52094c8a 2053 err = may_lookup(nd);
2a18da7a 2054 if (err)
3595e234 2055 return err;
1da177e4 2056
8387ff25 2057 hash_len = hash_name(nd->path.dentry, name);
1da177e4 2058
fe479a58 2059 type = LAST_NORM;
d6bb3e90 2060 if (name[0] == '.') switch (hashlen_len(hash_len)) {
fe479a58 2061 case 2:
200e9ef7 2062 if (name[1] == '.') {
fe479a58 2063 type = LAST_DOTDOT;
16c2cd71
AV
2064 nd->flags |= LOOKUP_JUMPED;
2065 }
fe479a58
AV
2066 break;
2067 case 1:
2068 type = LAST_DOT;
2069 }
5a202bcd
AV
2070 if (likely(type == LAST_NORM)) {
2071 struct dentry *parent = nd->path.dentry;
16c2cd71 2072 nd->flags &= ~LOOKUP_JUMPED;
5a202bcd 2073 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
a060dc50 2074 struct qstr this = { { .hash_len = hash_len }, .name = name };
da53be12 2075 err = parent->d_op->d_hash(parent, &this);
5a202bcd 2076 if (err < 0)
3595e234 2077 return err;
d6bb3e90
LT
2078 hash_len = this.hash_len;
2079 name = this.name;
5a202bcd
AV
2080 }
2081 }
fe479a58 2082
d6bb3e90
LT
2083 nd->last.hash_len = hash_len;
2084 nd->last.name = name;
5f4a6a69
AV
2085 nd->last_type = type;
2086
d6bb3e90
LT
2087 name += hashlen_len(hash_len);
2088 if (!*name)
bdf6cbf1 2089 goto OK;
200e9ef7
LT
2090 /*
2091 * If it wasn't NUL, we know it was '/'. Skip that
2092 * slash, and continue until no more slashes.
2093 */
2094 do {
d6bb3e90
LT
2095 name++;
2096 } while (unlikely(*name == '/'));
8620c238
AV
2097 if (unlikely(!*name)) {
2098OK:
368ee9ba 2099 /* pathname body, done */
8620c238
AV
2100 if (!nd->depth)
2101 return 0;
2102 name = nd->stack[nd->depth - 1].name;
368ee9ba 2103 /* trailing symlink, done */
8620c238
AV
2104 if (!name)
2105 return 0;
2106 /* last component of nested symlink */
4693a547 2107 err = walk_component(nd, WALK_GET | WALK_PUT);
8620c238 2108 } else {
4693a547 2109 err = walk_component(nd, WALK_GET);
8620c238 2110 }
ce57dfc1 2111 if (err < 0)
3595e234 2112 return err;
1da177e4 2113
ce57dfc1 2114 if (err) {
626de996 2115 const char *s = get_link(nd);
5a460275 2116
a1c83681 2117 if (IS_ERR(s))
3595e234 2118 return PTR_ERR(s);
d40bcc09
AV
2119 err = 0;
2120 if (unlikely(!s)) {
2121 /* jumped */
b9ff4429 2122 put_link(nd);
d40bcc09 2123 } else {
fab51e8a
AV
2124 nd->stack[nd->depth - 1].name = name;
2125 name = s;
2126 continue;
d40bcc09 2127 }
31e6b01f 2128 }
97242f99
AV
2129 if (unlikely(!d_can_lookup(nd->path.dentry))) {
2130 if (nd->flags & LOOKUP_RCU) {
2131 if (unlazy_walk(nd, NULL, 0))
2132 return -ECHILD;
2133 }
3595e234 2134 return -ENOTDIR;
97242f99 2135 }
1da177e4 2136 }
1da177e4
LT
2137}
2138
c8a53ee5 2139static const char *path_init(struct nameidata *nd, unsigned flags)
31e6b01f
NP
2140{
2141 int retval = 0;
c8a53ee5 2142 const char *s = nd->name->name;
31e6b01f
NP
2143
2144 nd->last_type = LAST_ROOT; /* if there are only slashes... */
980f3ea2 2145 nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
31e6b01f 2146 nd->depth = 0;
5b6ca027 2147 if (flags & LOOKUP_ROOT) {
b18825a7
DH
2148 struct dentry *root = nd->root.dentry;
2149 struct inode *inode = root->d_inode;
fd2f7cb5 2150 if (*s) {
44b1d530 2151 if (!d_can_lookup(root))
368ee9ba 2152 return ERR_PTR(-ENOTDIR);
73d049a4
AV
2153 retval = inode_permission(inode, MAY_EXEC);
2154 if (retval)
368ee9ba 2155 return ERR_PTR(retval);
73d049a4 2156 }
5b6ca027
AV
2157 nd->path = nd->root;
2158 nd->inode = inode;
2159 if (flags & LOOKUP_RCU) {
8b61e74f 2160 rcu_read_lock();
5b6ca027 2161 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
8f47a016 2162 nd->root_seq = nd->seq;
48a066e7 2163 nd->m_seq = read_seqbegin(&mount_lock);
5b6ca027
AV
2164 } else {
2165 path_get(&nd->path);
2166 }
368ee9ba 2167 return s;
5b6ca027
AV
2168 }
2169
31e6b01f 2170 nd->root.mnt = NULL;
248fb5b9
AV
2171 nd->path.mnt = NULL;
2172 nd->path.dentry = NULL;
31e6b01f 2173
48a066e7 2174 nd->m_seq = read_seqbegin(&mount_lock);
fd2f7cb5 2175 if (*s == '/') {
9e6697e2 2176 if (flags & LOOKUP_RCU)
8b61e74f 2177 rcu_read_lock();
9e6697e2 2178 set_root(nd);
248fb5b9 2179 if (likely(!nd_jump_root(nd)))
ef55d917 2180 return s;
248fb5b9 2181 nd->root.mnt = NULL;
ef55d917
AV
2182 rcu_read_unlock();
2183 return ERR_PTR(-ECHILD);
c8a53ee5 2184 } else if (nd->dfd == AT_FDCWD) {
e41f7d4e
AV
2185 if (flags & LOOKUP_RCU) {
2186 struct fs_struct *fs = current->fs;
2187 unsigned seq;
31e6b01f 2188
8b61e74f 2189 rcu_read_lock();
c28cc364 2190
e41f7d4e
AV
2191 do {
2192 seq = read_seqcount_begin(&fs->seq);
2193 nd->path = fs->pwd;
ef55d917 2194 nd->inode = nd->path.dentry->d_inode;
e41f7d4e
AV
2195 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
2196 } while (read_seqcount_retry(&fs->seq, seq));
2197 } else {
2198 get_fs_pwd(current->fs, &nd->path);
ef55d917 2199 nd->inode = nd->path.dentry->d_inode;
e41f7d4e 2200 }
ef55d917 2201 return s;
31e6b01f 2202 } else {
582aa64a 2203 /* Caller must check execute permissions on the starting path component */
c8a53ee5 2204 struct fd f = fdget_raw(nd->dfd);
31e6b01f
NP
2205 struct dentry *dentry;
2206
2903ff01 2207 if (!f.file)
368ee9ba 2208 return ERR_PTR(-EBADF);
31e6b01f 2209
2903ff01 2210 dentry = f.file->f_path.dentry;
31e6b01f 2211
fd2f7cb5 2212 if (*s) {
44b1d530 2213 if (!d_can_lookup(dentry)) {
2903ff01 2214 fdput(f);
368ee9ba 2215 return ERR_PTR(-ENOTDIR);
2903ff01 2216 }
f52e0c11 2217 }
31e6b01f 2218
2903ff01 2219 nd->path = f.file->f_path;
e41f7d4e 2220 if (flags & LOOKUP_RCU) {
8b61e74f 2221 rcu_read_lock();
34a26b99
AV
2222 nd->inode = nd->path.dentry->d_inode;
2223 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
e41f7d4e 2224 } else {
2903ff01 2225 path_get(&nd->path);
34a26b99 2226 nd->inode = nd->path.dentry->d_inode;
e41f7d4e 2227 }
34a26b99 2228 fdput(f);
368ee9ba 2229 return s;
31e6b01f 2230 }
9b4a9b14
AV
2231}
2232
3bdba28b 2233static const char *trailing_symlink(struct nameidata *nd)
95fa25d9
AV
2234{
2235 const char *s;
fec2fa24 2236 int error = may_follow_link(nd);
deb106c6 2237 if (unlikely(error))
3bdba28b 2238 return ERR_PTR(error);
95fa25d9 2239 nd->flags |= LOOKUP_PARENT;
fab51e8a 2240 nd->stack[0].name = NULL;
3b2e7f75 2241 s = get_link(nd);
deb106c6 2242 return s ? s : "";
95fa25d9
AV
2243}
2244
caa85634 2245static inline int lookup_last(struct nameidata *nd)
bd92d7fe
AV
2246{
2247 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
2248 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2249
2250 nd->flags &= ~LOOKUP_PARENT;
deb106c6 2251 return walk_component(nd,
4693a547
AV
2252 nd->flags & LOOKUP_FOLLOW
2253 ? nd->depth
2254 ? WALK_PUT | WALK_GET
2255 : WALK_GET
2256 : 0);
bd92d7fe
AV
2257}
2258
9b4a9b14 2259/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
c8a53ee5 2260static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
9b4a9b14 2261{
c8a53ee5 2262 const char *s = path_init(nd, flags);
bd92d7fe 2263 int err;
31e6b01f 2264
368ee9ba
AV
2265 if (IS_ERR(s))
2266 return PTR_ERR(s);
3bdba28b
AV
2267 while (!(err = link_path_walk(s, nd))
2268 && ((err = lookup_last(nd)) > 0)) {
2269 s = trailing_symlink(nd);
2270 if (IS_ERR(s)) {
2271 err = PTR_ERR(s);
2272 break;
bd92d7fe
AV
2273 }
2274 }
9f1fafee
AV
2275 if (!err)
2276 err = complete_walk(nd);
bd92d7fe 2277
deb106c6
AV
2278 if (!err && nd->flags & LOOKUP_DIRECTORY)
2279 if (!d_can_lookup(nd->path.dentry))
bd23a539 2280 err = -ENOTDIR;
625b6d10
AV
2281 if (!err) {
2282 *path = nd->path;
2283 nd->path.mnt = NULL;
2284 nd->path.dentry = NULL;
2285 }
2286 terminate_walk(nd);
bd92d7fe 2287 return err;
ee0827cd 2288}
31e6b01f 2289
625b6d10 2290static int filename_lookup(int dfd, struct filename *name, unsigned flags,
9ad1aaa6 2291 struct path *path, struct path *root)
ee0827cd 2292{
894bc8c4 2293 int retval;
9883d185 2294 struct nameidata nd;
abc9f5be
AV
2295 if (IS_ERR(name))
2296 return PTR_ERR(name);
9ad1aaa6
AV
2297 if (unlikely(root)) {
2298 nd.root = *root;
2299 flags |= LOOKUP_ROOT;
2300 }
9883d185 2301 set_nameidata(&nd, dfd, name);
c8a53ee5 2302 retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
ee0827cd 2303 if (unlikely(retval == -ECHILD))
c8a53ee5 2304 retval = path_lookupat(&nd, flags, path);
ee0827cd 2305 if (unlikely(retval == -ESTALE))
c8a53ee5 2306 retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);
31e6b01f 2307
f78570dd 2308 if (likely(!retval))
625b6d10 2309 audit_inode(name, path->dentry, flags & LOOKUP_PARENT);
9883d185 2310 restore_nameidata();
e4bd1c1a 2311 putname(name);
170aa3d0 2312 return retval;
1da177e4
LT
2313}
2314
8bcb77fa 2315/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
c8a53ee5 2316static int path_parentat(struct nameidata *nd, unsigned flags,
391172c4 2317 struct path *parent)
8bcb77fa 2318{
c8a53ee5 2319 const char *s = path_init(nd, flags);
368ee9ba
AV
2320 int err;
2321 if (IS_ERR(s))
2322 return PTR_ERR(s);
2323 err = link_path_walk(s, nd);
8bcb77fa
AV
2324 if (!err)
2325 err = complete_walk(nd);
391172c4
AV
2326 if (!err) {
2327 *parent = nd->path;
2328 nd->path.mnt = NULL;
2329 nd->path.dentry = NULL;
2330 }
2331 terminate_walk(nd);
8bcb77fa
AV
2332 return err;
2333}
2334
5c31b6ce 2335static struct filename *filename_parentat(int dfd, struct filename *name,
391172c4
AV
2336 unsigned int flags, struct path *parent,
2337 struct qstr *last, int *type)
8bcb77fa
AV
2338{
2339 int retval;
9883d185 2340 struct nameidata nd;
8bcb77fa 2341
5c31b6ce
AV
2342 if (IS_ERR(name))
2343 return name;
9883d185 2344 set_nameidata(&nd, dfd, name);
c8a53ee5 2345 retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
8bcb77fa 2346 if (unlikely(retval == -ECHILD))
c8a53ee5 2347 retval = path_parentat(&nd, flags, parent);
8bcb77fa 2348 if (unlikely(retval == -ESTALE))
c8a53ee5 2349 retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent);
391172c4
AV
2350 if (likely(!retval)) {
2351 *last = nd.last;
2352 *type = nd.last_type;
2353 audit_inode(name, parent->dentry, LOOKUP_PARENT);
5c31b6ce
AV
2354 } else {
2355 putname(name);
2356 name = ERR_PTR(retval);
391172c4 2357 }
9883d185 2358 restore_nameidata();
5c31b6ce 2359 return name;
8bcb77fa
AV
2360}
2361
79714f72
AV
2362/* does lookup, returns the object with parent locked */
2363struct dentry *kern_path_locked(const char *name, struct path *path)
5590ff0d 2364{
5c31b6ce
AV
2365 struct filename *filename;
2366 struct dentry *d;
391172c4
AV
2367 struct qstr last;
2368 int type;
51689104 2369
5c31b6ce
AV
2370 filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
2371 &last, &type);
51689104
PM
2372 if (IS_ERR(filename))
2373 return ERR_CAST(filename);
5c31b6ce 2374 if (unlikely(type != LAST_NORM)) {
391172c4 2375 path_put(path);
5c31b6ce
AV
2376 putname(filename);
2377 return ERR_PTR(-EINVAL);
79714f72 2378 }
5955102c 2379 inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
391172c4 2380 d = __lookup_hash(&last, path->dentry, 0);
79714f72 2381 if (IS_ERR(d)) {
5955102c 2382 inode_unlock(path->dentry->d_inode);
391172c4 2383 path_put(path);
79714f72 2384 }
51689104 2385 putname(filename);
79714f72 2386 return d;
5590ff0d
UD
2387}
2388
d1811465
AV
2389int kern_path(const char *name, unsigned int flags, struct path *path)
2390{
abc9f5be
AV
2391 return filename_lookup(AT_FDCWD, getname_kernel(name),
2392 flags, path, NULL);
d1811465 2393}
4d359507 2394EXPORT_SYMBOL(kern_path);
d1811465 2395
16f18200
JJS
2396/**
2397 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2398 * @dentry: pointer to dentry of the base directory
2399 * @mnt: pointer to vfs mount of the base directory
2400 * @name: pointer to file name
2401 * @flags: lookup flags
e0a01249 2402 * @path: pointer to struct path to fill
16f18200
JJS
2403 */
2404int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
2405 const char *name, unsigned int flags,
e0a01249 2406 struct path *path)
16f18200 2407{
9ad1aaa6 2408 struct path root = {.mnt = mnt, .dentry = dentry};
9ad1aaa6 2409 /* the first argument of filename_lookup() is ignored with root */
abc9f5be
AV
2410 return filename_lookup(AT_FDCWD, getname_kernel(name),
2411 flags , path, &root);
16f18200 2412}
4d359507 2413EXPORT_SYMBOL(vfs_path_lookup);
16f18200 2414
eead1911 2415/**
a6b91919 2416 * lookup_one_len - filesystem helper to lookup single pathname component
eead1911
CH
2417 * @name: pathname component to lookup
2418 * @base: base directory to lookup from
2419 * @len: maximum length @len should be interpreted to
2420 *
a6b91919 2421 * Note that this routine is purely a helper for filesystem usage and should
9e7543e9 2422 * not be called by generic code.
bbddca8e
N
2423 *
2424 * The caller must hold base->i_mutex.
eead1911 2425 */
057f6c01
JM
2426struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
2427{
057f6c01 2428 struct qstr this;
6a96ba54 2429 unsigned int c;
cda309de 2430 int err;
057f6c01 2431
5955102c 2432 WARN_ON_ONCE(!inode_is_locked(base->d_inode));
2f9092e1 2433
6a96ba54
AV
2434 this.name = name;
2435 this.len = len;
8387ff25 2436 this.hash = full_name_hash(base, name, len);
6a96ba54
AV
2437 if (!len)
2438 return ERR_PTR(-EACCES);
2439
21d8a15a
AV
2440 if (unlikely(name[0] == '.')) {
2441 if (len < 2 || (len == 2 && name[1] == '.'))
2442 return ERR_PTR(-EACCES);
2443 }
2444
6a96ba54
AV
2445 while (len--) {
2446 c = *(const unsigned char *)name++;
2447 if (c == '/' || c == '\0')
2448 return ERR_PTR(-EACCES);
6a96ba54 2449 }
5a202bcd
AV
2450 /*
2451 * See if the low-level filesystem might want
2452 * to use its own hash..
2453 */
2454 if (base->d_flags & DCACHE_OP_HASH) {
da53be12 2455 int err = base->d_op->d_hash(base, &this);
5a202bcd
AV
2456 if (err < 0)
2457 return ERR_PTR(err);
2458 }
eead1911 2459
cda309de
MS
2460 err = inode_permission(base->d_inode, MAY_EXEC);
2461 if (err)
2462 return ERR_PTR(err);
2463
72bd866a 2464 return __lookup_hash(&this, base, 0);
057f6c01 2465}
4d359507 2466EXPORT_SYMBOL(lookup_one_len);
057f6c01 2467
bbddca8e
N
2468/**
2469 * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
2470 * @name: pathname component to lookup
2471 * @base: base directory to lookup from
2472 * @len: maximum length @len should be interpreted to
2473 *
2474 * Note that this routine is purely a helper for filesystem usage and should
2475 * not be called by generic code.
2476 *
2477 * Unlike lookup_one_len, it should be called without the parent
2478 * i_mutex held, and will take the i_mutex itself if necessary.
2479 */
2480struct dentry *lookup_one_len_unlocked(const char *name,
2481 struct dentry *base, int len)
2482{
2483 struct qstr this;
2484 unsigned int c;
2485 int err;
20d00ee8 2486 struct dentry *ret;
bbddca8e
N
2487
2488 this.name = name;
2489 this.len = len;
8387ff25 2490 this.hash = full_name_hash(base, name, len);
bbddca8e
N
2491 if (!len)
2492 return ERR_PTR(-EACCES);
2493
2494 if (unlikely(name[0] == '.')) {
2495 if (len < 2 || (len == 2 && name[1] == '.'))
2496 return ERR_PTR(-EACCES);
2497 }
2498
2499 while (len--) {
2500 c = *(const unsigned char *)name++;
2501 if (c == '/' || c == '\0')
2502 return ERR_PTR(-EACCES);
2503 }
2504 /*
2505 * See if the low-level filesystem might want
2506 * to use its own hash..
2507 */
2508 if (base->d_flags & DCACHE_OP_HASH) {
2509 int err = base->d_op->d_hash(base, &this);
2510 if (err < 0)
2511 return ERR_PTR(err);
2512 }
2513
2514 err = inode_permission(base->d_inode, MAY_EXEC);
2515 if (err)
2516 return ERR_PTR(err);
2517
20d00ee8
LT
2518 ret = lookup_dcache(&this, base, 0);
2519 if (!ret)
2520 ret = lookup_slow(&this, base, 0);
2521 return ret;
bbddca8e
N
2522}
2523EXPORT_SYMBOL(lookup_one_len_unlocked);
2524
eedf265a
EB
2525#ifdef CONFIG_UNIX98_PTYS
2526int path_pts(struct path *path)
2527{
2528 /* Find something mounted on "pts" in the same directory as
2529 * the input path.
2530 */
2531 struct dentry *child, *parent;
2532 struct qstr this;
2533 int ret;
2534
2535 ret = path_parent_directory(path);
2536 if (ret)
2537 return ret;
2538
2539 parent = path->dentry;
2540 this.name = "pts";
2541 this.len = 3;
2542 child = d_hash_and_lookup(parent, &this);
2543 if (!child)
2544 return -ENOENT;
2545
2546 path->dentry = child;
2547 dput(parent);
2548 follow_mount(path);
2549 return 0;
2550}
2551#endif
2552
1fa1e7f6
AW
2553int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
2554 struct path *path, int *empty)
1da177e4 2555{
abc9f5be
AV
2556 return filename_lookup(dfd, getname_flags(name, flags, empty),
2557 flags, path, NULL);
1da177e4 2558}
b853a161 2559EXPORT_SYMBOL(user_path_at_empty);
1fa1e7f6 2560
873f1eed
JL
2561/*
2562 * NB: most callers don't do anything directly with the reference to the
2563 * to struct filename, but the nd->last pointer points into the name string
2564 * allocated by getname. So we must hold the reference to it until all
2565 * path-walking is complete.
2566 */
a2ec4a2d 2567static inline struct filename *
f5beed75
AV
2568user_path_parent(int dfd, const char __user *path,
2569 struct path *parent,
2570 struct qstr *last,
2571 int *type,
9e790bd6 2572 unsigned int flags)
2ad94ae6 2573{
9e790bd6 2574 /* only LOOKUP_REVAL is allowed in extra flags */
5c31b6ce
AV
2575 return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL,
2576 parent, last, type);
2ad94ae6
AV
2577}
2578
8033426e 2579/**
197df04c 2580 * mountpoint_last - look up last component for umount
8033426e
JL
2581 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2582 * @path: pointer to container for result
2583 *
2584 * This is a special lookup_last function just for umount. In this case, we
2585 * need to resolve the path without doing any revalidation.
2586 *
2587 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2588 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2589 * in almost all cases, this lookup will be served out of the dcache. The only
2590 * cases where it won't are if nd->last refers to a symlink or the path is
2591 * bogus and it doesn't exist.
2592 *
2593 * Returns:
2594 * -error: if there was an error during lookup. This includes -ENOENT if the
2595 * lookup found a negative dentry. The nd->path reference will also be
2596 * put in this case.
2597 *
2598 * 0: if we successfully resolved nd->path and found it to not to be a
2599 * symlink that needs to be followed. "path" will also be populated.
2600 * The nd->path reference will also be put.
2601 *
2602 * 1: if we successfully resolved nd->last and found it to be a symlink
2603 * that needs to be followed. "path" will be populated with the path
2604 * to the link, and nd->path will *not* be put.
2605 */
2606static int
197df04c 2607mountpoint_last(struct nameidata *nd, struct path *path)
8033426e
JL
2608{
2609 int error = 0;
2610 struct dentry *dentry;
2611 struct dentry *dir = nd->path.dentry;
2612
35759521
AV
2613 /* If we're in rcuwalk, drop out of it to handle last component */
2614 if (nd->flags & LOOKUP_RCU) {
6e9918b7 2615 if (unlazy_walk(nd, NULL, 0))
deb106c6 2616 return -ECHILD;
8033426e
JL
2617 }
2618
2619 nd->flags &= ~LOOKUP_PARENT;
2620
2621 if (unlikely(nd->last_type != LAST_NORM)) {
2622 error = handle_dots(nd, nd->last_type);
35759521 2623 if (error)
deb106c6 2624 return error;
35759521 2625 dentry = dget(nd->path.dentry);
949a852e
AV
2626 } else {
2627 dentry = d_lookup(dir, &nd->last);
8033426e 2628 if (!dentry) {
949a852e
AV
2629 /*
2630 * No cached dentry. Mounted dentries are pinned in the
2631 * cache, so that means that this dentry is probably
2632 * a symlink or the path doesn't actually point
2633 * to a mounted dentry.
2634 */
2635 dentry = lookup_slow(&nd->last, dir,
2636 nd->flags | LOOKUP_NO_REVAL);
2637 if (IS_ERR(dentry))
2638 return PTR_ERR(dentry);
bcceeeba 2639 }
8033426e 2640 }
698934df 2641 if (d_is_negative(dentry)) {
35759521 2642 dput(dentry);
deb106c6 2643 return -ENOENT;
8033426e 2644 }
191d7f73
AV
2645 if (nd->depth)
2646 put_link(nd);
35759521 2647 path->dentry = dentry;
295dc39d 2648 path->mnt = nd->path.mnt;
181548c0
AV
2649 error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW,
2650 d_backing_inode(dentry), 0);
deb106c6 2651 if (unlikely(error))
d63ff28f 2652 return error;
295dc39d 2653 mntget(path->mnt);
35759521 2654 follow_mount(path);
deb106c6 2655 return 0;
8033426e
JL
2656}
2657
2658/**
197df04c 2659 * path_mountpoint - look up a path to be umounted
2a78b857 2660 * @nd: lookup context
8033426e 2661 * @flags: lookup flags
c8a53ee5 2662 * @path: pointer to container for result
8033426e
JL
2663 *
2664 * Look up the given name, but don't attempt to revalidate the last component.
606d6fe3 2665 * Returns 0 and "path" will be valid on success; Returns error otherwise.
8033426e
JL
2666 */
2667static int
c8a53ee5 2668path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
8033426e 2669{
c8a53ee5 2670 const char *s = path_init(nd, flags);
368ee9ba
AV
2671 int err;
2672 if (IS_ERR(s))
2673 return PTR_ERR(s);
3bdba28b
AV
2674 while (!(err = link_path_walk(s, nd)) &&
2675 (err = mountpoint_last(nd, path)) > 0) {
2676 s = trailing_symlink(nd);
2677 if (IS_ERR(s)) {
2678 err = PTR_ERR(s);
8033426e 2679 break;
3bdba28b 2680 }
8033426e 2681 }
deb106c6 2682 terminate_walk(nd);
8033426e
JL
2683 return err;
2684}
2685
2d864651 2686static int
668696dc 2687filename_mountpoint(int dfd, struct filename *name, struct path *path,
2d864651
AV
2688 unsigned int flags)
2689{
9883d185 2690 struct nameidata nd;
cbaab2db 2691 int error;
668696dc
AV
2692 if (IS_ERR(name))
2693 return PTR_ERR(name);
9883d185 2694 set_nameidata(&nd, dfd, name);
c8a53ee5 2695 error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
2d864651 2696 if (unlikely(error == -ECHILD))
c8a53ee5 2697 error = path_mountpoint(&nd, flags, path);
2d864651 2698 if (unlikely(error == -ESTALE))
c8a53ee5 2699 error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
2d864651 2700 if (likely(!error))
668696dc 2701 audit_inode(name, path->dentry, 0);
9883d185 2702 restore_nameidata();
668696dc 2703 putname(name);
2d864651
AV
2704 return error;
2705}
2706
8033426e 2707/**
197df04c 2708 * user_path_mountpoint_at - lookup a path from userland in order to umount it
8033426e
JL
2709 * @dfd: directory file descriptor
2710 * @name: pathname from userland
2711 * @flags: lookup flags
2712 * @path: pointer to container to hold result
2713 *
2714 * A umount is a special case for path walking. We're not actually interested
2715 * in the inode in this situation, and ESTALE errors can be a problem. We
2716 * simply want track down the dentry and vfsmount attached at the mountpoint
2717 * and avoid revalidating the last component.
2718 *
2719 * Returns 0 and populates "path" on success.
2720 */
2721int
197df04c 2722user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
8033426e
JL
2723 struct path *path)
2724{
cbaab2db 2725 return filename_mountpoint(dfd, getname(name), path, flags);
8033426e
JL
2726}
2727
2d864651
AV
2728int
2729kern_path_mountpoint(int dfd, const char *name, struct path *path,
2730 unsigned int flags)
2731{
cbaab2db 2732 return filename_mountpoint(dfd, getname_kernel(name), path, flags);
2d864651
AV
2733}
2734EXPORT_SYMBOL(kern_path_mountpoint);
2735
cbdf35bc 2736int __check_sticky(struct inode *dir, struct inode *inode)
1da177e4 2737{
8e96e3b7 2738 kuid_t fsuid = current_fsuid();
da9592ed 2739
8e96e3b7 2740 if (uid_eq(inode->i_uid, fsuid))
1da177e4 2741 return 0;
8e96e3b7 2742 if (uid_eq(dir->i_uid, fsuid))
1da177e4 2743 return 0;
23adbe12 2744 return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
1da177e4 2745}
cbdf35bc 2746EXPORT_SYMBOL(__check_sticky);
1da177e4
LT
2747
2748/*
2749 * Check whether we can remove a link victim from directory dir, check
2750 * whether the type of victim is right.
2751 * 1. We can't do it if dir is read-only (done in permission())
2752 * 2. We should have write and exec permissions on dir
2753 * 3. We can't remove anything from append-only dir
2754 * 4. We can't do anything with immutable dir (done in permission())
2755 * 5. If the sticky bit on dir is set we should either
2756 * a. be owner of dir, or
2757 * b. be owner of victim, or
2758 * c. have CAP_FOWNER capability
2759 * 6. If the victim is append-only or immutable we can't do antyhing with
2760 * links pointing to it.
0bd23d09
EB
2761 * 7. If the victim has an unknown uid or gid we can't change the inode.
2762 * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2763 * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2764 * 10. We can't remove a root or mountpoint.
2765 * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
1da177e4
LT
2766 * nfs_async_unlink().
2767 */
b18825a7 2768static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
1da177e4 2769{
63afdfc7 2770 struct inode *inode = d_backing_inode(victim);
1da177e4
LT
2771 int error;
2772
b18825a7 2773 if (d_is_negative(victim))
1da177e4 2774 return -ENOENT;
b18825a7 2775 BUG_ON(!inode);
1da177e4
LT
2776
2777 BUG_ON(victim->d_parent->d_inode != dir);
4fa6b5ec 2778 audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
1da177e4 2779
f419a2e3 2780 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT
2781 if (error)
2782 return error;
2783 if (IS_APPEND(dir))
2784 return -EPERM;
b18825a7
DH
2785
2786 if (check_sticky(dir, inode) || IS_APPEND(inode) ||
0bd23d09 2787 IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode))
1da177e4
LT
2788 return -EPERM;
2789 if (isdir) {
44b1d530 2790 if (!d_is_dir(victim))
1da177e4
LT
2791 return -ENOTDIR;
2792 if (IS_ROOT(victim))
2793 return -EBUSY;
44b1d530 2794 } else if (d_is_dir(victim))
1da177e4
LT
2795 return -EISDIR;
2796 if (IS_DEADDIR(dir))
2797 return -ENOENT;
2798 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
2799 return -EBUSY;
2800 return 0;
2801}
2802
2803/* Check whether we can create an object with dentry child in directory
2804 * dir.
2805 * 1. We can't do it if child already exists (open has special treatment for
2806 * this case, but since we are inlined it's OK)
2807 * 2. We can't do it if dir is read-only (done in permission())
036d5236
EB
2808 * 3. We can't do it if the fs can't represent the fsuid or fsgid.
2809 * 4. We should have write and exec permissions on dir
2810 * 5. We can't do it if dir is immutable (done in permission())
1da177e4 2811 */
a95164d9 2812static inline int may_create(struct inode *dir, struct dentry *child)
1da177e4 2813{
036d5236 2814 struct user_namespace *s_user_ns;
14e972b4 2815 audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
1da177e4
LT
2816 if (child->d_inode)
2817 return -EEXIST;
2818 if (IS_DEADDIR(dir))
2819 return -ENOENT;
036d5236
EB
2820 s_user_ns = dir->i_sb->s_user_ns;
2821 if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
2822 !kgid_has_mapping(s_user_ns, current_fsgid()))
2823 return -EOVERFLOW;
f419a2e3 2824 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1da177e4
LT
2825}
2826
1da177e4
LT
2827/*
2828 * p1 and p2 should be directories on the same fs.
2829 */
2830struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
2831{
2832 struct dentry *p;
2833
2834 if (p1 == p2) {
5955102c 2835 inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
1da177e4
LT
2836 return NULL;
2837 }
2838
fc64005c 2839 mutex_lock(&p1->d_sb->s_vfs_rename_mutex);
1da177e4 2840
e2761a11
OH
2841 p = d_ancestor(p2, p1);
2842 if (p) {
5955102c
AV
2843 inode_lock_nested(p2->d_inode, I_MUTEX_PARENT);
2844 inode_lock_nested(p1->d_inode, I_MUTEX_CHILD);
e2761a11 2845 return p;
1da177e4
LT
2846 }
2847
e2761a11
OH
2848 p = d_ancestor(p1, p2);
2849 if (p) {
5955102c
AV
2850 inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
2851 inode_lock_nested(p2->d_inode, I_MUTEX_CHILD);
e2761a11 2852 return p;
1da177e4
LT
2853 }
2854
5955102c
AV
2855 inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
2856 inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2);
1da177e4
LT
2857 return NULL;
2858}
4d359507 2859EXPORT_SYMBOL(lock_rename);
1da177e4
LT
2860
2861void unlock_rename(struct dentry *p1, struct dentry *p2)
2862{
5955102c 2863 inode_unlock(p1->d_inode);
1da177e4 2864 if (p1 != p2) {
5955102c 2865 inode_unlock(p2->d_inode);
fc64005c 2866 mutex_unlock(&p1->d_sb->s_vfs_rename_mutex);
1da177e4
LT
2867 }
2868}
4d359507 2869EXPORT_SYMBOL(unlock_rename);
1da177e4 2870
4acdaf27 2871int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
312b63fb 2872 bool want_excl)
1da177e4 2873{
a95164d9 2874 int error = may_create(dir, dentry);
1da177e4
LT
2875 if (error)
2876 return error;
2877
acfa4380 2878 if (!dir->i_op->create)
1da177e4
LT
2879 return -EACCES; /* shouldn't it be ENOSYS? */
2880 mode &= S_IALLUGO;
2881 mode |= S_IFREG;
2882 error = security_inode_create(dir, dentry, mode);
2883 if (error)
2884 return error;
312b63fb 2885 error = dir->i_op->create(dir, dentry, mode, want_excl);
a74574aa 2886 if (!error)
f38aa942 2887 fsnotify_create(dir, dentry);
1da177e4
LT
2888 return error;
2889}
4d359507 2890EXPORT_SYMBOL(vfs_create);
1da177e4 2891
a2982cc9
EB
2892bool may_open_dev(const struct path *path)
2893{
2894 return !(path->mnt->mnt_flags & MNT_NODEV) &&
2895 !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
2896}
2897
73d049a4 2898static int may_open(struct path *path, int acc_mode, int flag)
1da177e4 2899{
3fb64190 2900 struct dentry *dentry = path->dentry;
1da177e4
LT
2901 struct inode *inode = dentry->d_inode;
2902 int error;
2903
2904 if (!inode)
2905 return -ENOENT;
2906
c8fe8f30
CH
2907 switch (inode->i_mode & S_IFMT) {
2908 case S_IFLNK:
1da177e4 2909 return -ELOOP;
c8fe8f30
CH
2910 case S_IFDIR:
2911 if (acc_mode & MAY_WRITE)
2912 return -EISDIR;
2913 break;
2914 case S_IFBLK:
2915 case S_IFCHR:
a2982cc9 2916 if (!may_open_dev(path))
1da177e4 2917 return -EACCES;
c8fe8f30
CH
2918 /*FALLTHRU*/
2919 case S_IFIFO:
2920 case S_IFSOCK:
1da177e4 2921 flag &= ~O_TRUNC;
c8fe8f30 2922 break;
4a3fd211 2923 }
b41572e9 2924
62fb4a15 2925 error = inode_permission(inode, MAY_OPEN | acc_mode);
b41572e9
DH
2926 if (error)
2927 return error;
6146f0d5 2928
1da177e4
LT
2929 /*
2930 * An append-only file must be opened in append mode for writing.
2931 */
2932 if (IS_APPEND(inode)) {
8737c930 2933 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
7715b521 2934 return -EPERM;
1da177e4 2935 if (flag & O_TRUNC)
7715b521 2936 return -EPERM;
1da177e4
LT
2937 }
2938
2939 /* O_NOATIME can only be set by the owner or superuser */
2e149670 2940 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
7715b521 2941 return -EPERM;
1da177e4 2942
f3c7691e 2943 return 0;
7715b521 2944}
1da177e4 2945
e1181ee6 2946static int handle_truncate(struct file *filp)
7715b521 2947{
e1181ee6 2948 struct path *path = &filp->f_path;
7715b521
AV
2949 struct inode *inode = path->dentry->d_inode;
2950 int error = get_write_access(inode);
2951 if (error)
2952 return error;
2953 /*
2954 * Refuse to truncate files with mandatory locks held on them.
2955 */
d7a06983 2956 error = locks_verify_locked(filp);
7715b521 2957 if (!error)
ea0d3ab2 2958 error = security_path_truncate(path);
7715b521
AV
2959 if (!error) {
2960 error = do_truncate(path->dentry, 0,
2961 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
e1181ee6 2962 filp);
7715b521
AV
2963 }
2964 put_write_access(inode);
acd0c935 2965 return error;
1da177e4
LT
2966}
2967
d57999e1
DH
2968static inline int open_to_namei_flags(int flag)
2969{
8a5e929d
AV
2970 if ((flag & O_ACCMODE) == 3)
2971 flag--;
d57999e1
DH
2972 return flag;
2973}
2974
d3607752 2975static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
d18e9008
MS
2976{
2977 int error = security_path_mknod(dir, dentry, mode, 0);
2978 if (error)
2979 return error;
2980
2981 error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
2982 if (error)
2983 return error;
2984
2985 return security_inode_create(dir->dentry->d_inode, dentry, mode);
2986}
2987
1acf0af9
DH
2988/*
2989 * Attempt to atomically look up, create and open a file from a negative
2990 * dentry.
2991 *
2992 * Returns 0 if successful. The file will have been created and attached to
2993 * @file by the filesystem calling finish_open().
2994 *
2995 * Returns 1 if the file was looked up only or didn't need creating. The
2996 * caller will need to perform the open themselves. @path will have been
2997 * updated to point to the new dentry. This may be negative.
2998 *
2999 * Returns an error code otherwise.
3000 */
2675a4eb
AV
3001static int atomic_open(struct nameidata *nd, struct dentry *dentry,
3002 struct path *path, struct file *file,
3003 const struct open_flags *op,
1643b43f 3004 int open_flag, umode_t mode,
2675a4eb 3005 int *opened)
d18e9008 3006{
384f26e2 3007 struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
d18e9008 3008 struct inode *dir = nd->path.dentry->d_inode;
d18e9008 3009 int error;
d18e9008 3010
384f26e2 3011 if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */
d18e9008 3012 open_flag &= ~O_TRUNC;
d18e9008 3013
d18e9008
MS
3014 if (nd->flags & LOOKUP_DIRECTORY)
3015 open_flag |= O_DIRECTORY;
3016
30d90494
AV
3017 file->f_path.dentry = DENTRY_NOT_SET;
3018 file->f_path.mnt = nd->path.mnt;
0fb1ea09
AV
3019 error = dir->i_op->atomic_open(dir, dentry, file,
3020 open_to_namei_flags(open_flag),
3021 mode, opened);
6fbd0714 3022 d_lookup_done(dentry);
384f26e2
AV
3023 if (!error) {
3024 /*
3025 * We didn't have the inode before the open, so check open
3026 * permission here.
3027 */
3028 int acc_mode = op->acc_mode;
3029 if (*opened & FILE_CREATED) {
3030 WARN_ON(!(open_flag & O_CREAT));
3031 fsnotify_create(dir, dentry);
3032 acc_mode = 0;
3033 }
3034 error = may_open(&file->f_path, acc_mode, open_flag);
3035 if (WARN_ON(error > 0))
3036 error = -EINVAL;
3037 } else if (error > 0) {
30d90494 3038 if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
2675a4eb 3039 error = -EIO;
03da633a 3040 } else {
384f26e2
AV
3041 if (file->f_path.dentry) {
3042 dput(dentry);
3043 dentry = file->f_path.dentry;
03da633a 3044 }
384f26e2
AV
3045 if (*opened & FILE_CREATED)
3046 fsnotify_create(dir, dentry);
a01e718f
AV
3047 if (unlikely(d_is_negative(dentry))) {
3048 error = -ENOENT;
3049 } else {
3050 path->dentry = dentry;
3051 path->mnt = nd->path.mnt;
3052 return 1;
3053 }
62b2ce96 3054 }
d18e9008 3055 }
d18e9008 3056 dput(dentry);
2675a4eb 3057 return error;
d18e9008
MS
3058}
3059
d58ffd35 3060/*
1acf0af9 3061 * Look up and maybe create and open the last component.
d58ffd35
MS
3062 *
3063 * Must be called with i_mutex held on parent.
3064 *
1acf0af9
DH
3065 * Returns 0 if the file was successfully atomically created (if necessary) and
3066 * opened. In this case the file will be returned attached to @file.
3067 *
3068 * Returns 1 if the file was not completely opened at this time, though lookups
3069 * and creations will have been performed and the dentry returned in @path will
3070 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
3071 * specified then a negative dentry may be returned.
3072 *
3073 * An error code is returned otherwise.
3074 *
3075 * FILE_CREATE will be set in @*opened if the dentry was created and will be
3076 * cleared otherwise prior to returning.
d58ffd35 3077 */
2675a4eb
AV
3078static int lookup_open(struct nameidata *nd, struct path *path,
3079 struct file *file,
3080 const struct open_flags *op,
64894cf8 3081 bool got_write, int *opened)
d58ffd35
MS
3082{
3083 struct dentry *dir = nd->path.dentry;
54ef4872 3084 struct inode *dir_inode = dir->d_inode;
1643b43f 3085 int open_flag = op->open_flag;
d58ffd35 3086 struct dentry *dentry;
1643b43f 3087 int error, create_error = 0;
1643b43f 3088 umode_t mode = op->mode;
6fbd0714 3089 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
d58ffd35 3090
ce8644fc
AV
3091 if (unlikely(IS_DEADDIR(dir_inode)))
3092 return -ENOENT;
d58ffd35 3093
47237687 3094 *opened &= ~FILE_CREATED;
6fbd0714
AV
3095 dentry = d_lookup(dir, &nd->last);
3096 for (;;) {
3097 if (!dentry) {
3098 dentry = d_alloc_parallel(dir, &nd->last, &wq);
3099 if (IS_ERR(dentry))
3100 return PTR_ERR(dentry);
3101 }
3102 if (d_in_lookup(dentry))
3103 break;
d58ffd35 3104
6fbd0714
AV
3105 if (!(dentry->d_flags & DCACHE_OP_REVALIDATE))
3106 break;
3107
3108 error = d_revalidate(dentry, nd->flags);
3109 if (likely(error > 0))
3110 break;
3111 if (error)
3112 goto out_dput;
3113 d_invalidate(dentry);
3114 dput(dentry);
3115 dentry = NULL;
3116 }
3117 if (dentry->d_inode) {
6c51e513 3118 /* Cached positive dentry: will open in f_op->open */
d18e9008 3119 goto out_no_open;
6c51e513 3120 }
d18e9008 3121
1643b43f
AV
3122 /*
3123 * Checking write permission is tricky, bacuse we don't know if we are
3124 * going to actually need it: O_CREAT opens should work as long as the
3125 * file exists. But checking existence breaks atomicity. The trick is
3126 * to check access and if not granted clear O_CREAT from the flags.
3127 *
3128 * Another problem is returing the "right" error value (e.g. for an
3129 * O_EXCL open we want to return EEXIST not EROFS).
3130 */
3131 if (open_flag & O_CREAT) {
3132 if (!IS_POSIXACL(dir->d_inode))
3133 mode &= ~current_umask();
3134 if (unlikely(!got_write)) {
3135 create_error = -EROFS;
3136 open_flag &= ~O_CREAT;
3137 if (open_flag & (O_EXCL | O_TRUNC))
3138 goto no_open;
3139 /* No side effects, safe to clear O_CREAT */
3140 } else {
3141 create_error = may_o_create(&nd->path, dentry, mode);
3142 if (create_error) {
3143 open_flag &= ~O_CREAT;
3144 if (open_flag & O_EXCL)
3145 goto no_open;
3146 }
3147 }
3148 } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
3149 unlikely(!got_write)) {
3150 /*
3151 * No O_CREATE -> atomicity not a requirement -> fall
3152 * back to lookup + open
3153 */
3154 goto no_open;
d18e9008
MS
3155 }
3156
6ac08709 3157 if (dir_inode->i_op->atomic_open) {
1643b43f
AV
3158 error = atomic_open(nd, dentry, path, file, op, open_flag,
3159 mode, opened);
3160 if (unlikely(error == -ENOENT) && create_error)
3161 error = create_error;
3162 return error;
d18e9008 3163 }
54ef4872 3164
1643b43f 3165no_open:
6fbd0714 3166 if (d_in_lookup(dentry)) {
12fa5e24
AV
3167 struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
3168 nd->flags);
6fbd0714 3169 d_lookup_done(dentry);
12fa5e24
AV
3170 if (unlikely(res)) {
3171 if (IS_ERR(res)) {
3172 error = PTR_ERR(res);
3173 goto out_dput;
3174 }
3175 dput(dentry);
3176 dentry = res;
3177 }
54ef4872
MS
3178 }
3179
d58ffd35 3180 /* Negative dentry, just create the file */
1643b43f 3181 if (!dentry->d_inode && (open_flag & O_CREAT)) {
47237687 3182 *opened |= FILE_CREATED;
ce8644fc 3183 audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
ce8644fc
AV
3184 if (!dir_inode->i_op->create) {
3185 error = -EACCES;
d58ffd35 3186 goto out_dput;
ce8644fc
AV
3187 }
3188 error = dir_inode->i_op->create(dir_inode, dentry, mode,
1643b43f 3189 open_flag & O_EXCL);
d58ffd35
MS
3190 if (error)
3191 goto out_dput;
ce8644fc 3192 fsnotify_create(dir_inode, dentry);
d58ffd35 3193 }
1643b43f
AV
3194 if (unlikely(create_error) && !dentry->d_inode) {
3195 error = create_error;
3196 goto out_dput;
d58ffd35 3197 }
d18e9008 3198out_no_open:
d58ffd35
MS
3199 path->dentry = dentry;
3200 path->mnt = nd->path.mnt;
2675a4eb 3201 return 1;
d58ffd35
MS
3202
3203out_dput:
3204 dput(dentry);
2675a4eb 3205 return error;
d58ffd35
MS
3206}
3207
31e6b01f 3208/*
fe2d35ff 3209 * Handle the last step of open()
31e6b01f 3210 */
896475d5 3211static int do_last(struct nameidata *nd,
2675a4eb 3212 struct file *file, const struct open_flags *op,
76ae2a5a 3213 int *opened)
fb1cc555 3214{
a1e28038 3215 struct dentry *dir = nd->path.dentry;
ca344a89 3216 int open_flag = op->open_flag;
77d660a8 3217 bool will_truncate = (open_flag & O_TRUNC) != 0;
64894cf8 3218 bool got_write = false;
bcda7652 3219 int acc_mode = op->acc_mode;
254cf582 3220 unsigned seq;
a1eb3315 3221 struct inode *inode;
896475d5 3222 struct path path;
16c2cd71 3223 int error;
1f36f774 3224
c3e380b0
AV
3225 nd->flags &= ~LOOKUP_PARENT;
3226 nd->flags |= op->intent;
3227
bc77daa7 3228 if (nd->last_type != LAST_NORM) {
fe2d35ff 3229 error = handle_dots(nd, nd->last_type);
deb106c6 3230 if (unlikely(error))
2675a4eb 3231 return error;
e83db167 3232 goto finish_open;
1f36f774 3233 }
67ee3ad2 3234
ca344a89 3235 if (!(open_flag & O_CREAT)) {
fe2d35ff
AV
3236 if (nd->last.name[nd->last.len])
3237 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
3238 /* we _can_ be in RCU mode here */
254cf582 3239 error = lookup_fast(nd, &path, &inode, &seq);
e9742b53 3240 if (likely(error > 0))
71574865
MS
3241 goto finish_lookup;
3242
3243 if (error < 0)
deb106c6 3244 return error;
71574865
MS
3245
3246 BUG_ON(nd->inode != dir->d_inode);
6583fe22 3247 BUG_ON(nd->flags & LOOKUP_RCU);
b6183df7
MS
3248 } else {
3249 /* create side of things */
3250 /*
3251 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3252 * has been cleared when we got to the last component we are
3253 * about to look up
3254 */
3255 error = complete_walk(nd);
e8bb73df 3256 if (error)
2675a4eb 3257 return error;
fe2d35ff 3258
76ae2a5a 3259 audit_inode(nd->name, dir, LOOKUP_PARENT);
b6183df7 3260 /* trailing slashes? */
deb106c6
AV
3261 if (unlikely(nd->last.name[nd->last.len]))
3262 return -EISDIR;
b6183df7 3263 }
a2c36b45 3264
9cf843e3 3265 if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
64894cf8
AV
3266 error = mnt_want_write(nd->path.mnt);
3267 if (!error)
3268 got_write = true;
3269 /*
3270 * do _not_ fail yet - we might not need that or fail with
3271 * a different error; let lookup_open() decide; we'll be
3272 * dropping this one anyway.
3273 */
3274 }
9cf843e3
AV
3275 if (open_flag & O_CREAT)
3276 inode_lock(dir->d_inode);
3277 else
3278 inode_lock_shared(dir->d_inode);
896475d5 3279 error = lookup_open(nd, &path, file, op, got_write, opened);
9cf843e3
AV
3280 if (open_flag & O_CREAT)
3281 inode_unlock(dir->d_inode);
3282 else
3283 inode_unlock_shared(dir->d_inode);
a1e28038 3284
2675a4eb
AV
3285 if (error <= 0) {
3286 if (error)
d18e9008
MS
3287 goto out;
3288
47237687 3289 if ((*opened & FILE_CREATED) ||
496ad9aa 3290 !S_ISREG(file_inode(file)->i_mode))
77d660a8 3291 will_truncate = false;
d18e9008 3292
76ae2a5a 3293 audit_inode(nd->name, file->f_path.dentry, 0);
d18e9008
MS
3294 goto opened;
3295 }
fb1cc555 3296
47237687 3297 if (*opened & FILE_CREATED) {
9b44f1b3 3298 /* Don't check for write permission, don't truncate */
ca344a89 3299 open_flag &= ~O_TRUNC;
77d660a8 3300 will_truncate = false;
62fb4a15 3301 acc_mode = 0;
896475d5 3302 path_to_nameidata(&path, nd);
e83db167 3303 goto finish_open_created;
fb1cc555
AV
3304 }
3305
d18e9008
MS
3306 /*
3307 * If atomic_open() acquired write access it is dropped now due to
3308 * possible mount and symlink following (this might be optimized away if
3309 * necessary...)
3310 */
64894cf8 3311 if (got_write) {
d18e9008 3312 mnt_drop_write(nd->path.mnt);
64894cf8 3313 got_write = false;
d18e9008
MS
3314 }
3315
e6ec03a2
AV
3316 error = follow_managed(&path, nd);
3317 if (unlikely(error < 0))
3318 return error;
3319
6583fe22
AV
3320 if (unlikely(d_is_negative(path.dentry))) {
3321 path_to_nameidata(&path, nd);
3322 return -ENOENT;
3323 }
3324
3325 /*
3326 * create/update audit record if it already exists.
3327 */
3328 audit_inode(nd->name, path.dentry, 0);
3329
deb106c6
AV
3330 if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {
3331 path_to_nameidata(&path, nd);
3332 return -EEXIST;
3333 }
fb1cc555 3334
254cf582 3335 seq = 0; /* out of RCU mode, so the value doesn't matter */
d4565649 3336 inode = d_backing_inode(path.dentry);
766c4cbf 3337finish_lookup:
d63ff28f
AV
3338 if (nd->depth)
3339 put_link(nd);
181548c0
AV
3340 error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW,
3341 inode, seq);
deb106c6 3342 if (unlikely(error))
d63ff28f 3343 return error;
fb1cc555 3344
fac7d191 3345 path_to_nameidata(&path, nd);
decf3400 3346 nd->inode = inode;
254cf582 3347 nd->seq = seq;
a3fbbde7 3348 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
bc77daa7 3349finish_open:
a3fbbde7 3350 error = complete_walk(nd);
fac7d191 3351 if (error)
2675a4eb 3352 return error;
76ae2a5a 3353 audit_inode(nd->name, nd->path.dentry, 0);
fb1cc555 3354 error = -EISDIR;
44b1d530 3355 if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
2675a4eb 3356 goto out;
af2f5542 3357 error = -ENOTDIR;
44b1d530 3358 if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
2675a4eb 3359 goto out;
4bbcbd3b 3360 if (!d_is_reg(nd->path.dentry))
77d660a8 3361 will_truncate = false;
6c0d46c4 3362
0f9d1a10
AV
3363 if (will_truncate) {
3364 error = mnt_want_write(nd->path.mnt);
3365 if (error)
2675a4eb 3366 goto out;
64894cf8 3367 got_write = true;
0f9d1a10 3368 }
e83db167 3369finish_open_created:
6ac08709
AV
3370 error = may_open(&nd->path, acc_mode, open_flag);
3371 if (error)
3372 goto out;
4aa7c634
MS
3373 BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
3374 error = vfs_open(&nd->path, file, current_cred());
fac7d191 3375 if (error)
015c3bbc 3376 goto out;
fac7d191 3377 *opened |= FILE_OPENED;
a8277b9b 3378opened:
2675a4eb 3379 error = open_check_o_direct(file);
fe9ec829
AV
3380 if (!error)
3381 error = ima_file_check(file, op->acc_mode, *opened);
3382 if (!error && will_truncate)
2675a4eb 3383 error = handle_truncate(file);
ca344a89 3384out:
fe9ec829
AV
3385 if (unlikely(error) && (*opened & FILE_OPENED))
3386 fput(file);
c80567c8
AV
3387 if (unlikely(error > 0)) {
3388 WARN_ON(1);
3389 error = -EINVAL;
3390 }
64894cf8 3391 if (got_write)
0f9d1a10 3392 mnt_drop_write(nd->path.mnt);
2675a4eb 3393 return error;
fb1cc555
AV
3394}
3395
c8a53ee5 3396static int do_tmpfile(struct nameidata *nd, unsigned flags,
60545d0d
AV
3397 const struct open_flags *op,
3398 struct file *file, int *opened)
3399{
3400 static const struct qstr name = QSTR_INIT("/", 1);
625b6d10 3401 struct dentry *child;
60545d0d 3402 struct inode *dir;
625b6d10 3403 struct path path;
c8a53ee5 3404 int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
60545d0d
AV
3405 if (unlikely(error))
3406 return error;
625b6d10 3407 error = mnt_want_write(path.mnt);
60545d0d
AV
3408 if (unlikely(error))
3409 goto out;
625b6d10 3410 dir = path.dentry->d_inode;
60545d0d 3411 /* we want directory to be writable */
625b6d10 3412 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
60545d0d
AV
3413 if (error)
3414 goto out2;
60545d0d
AV
3415 if (!dir->i_op->tmpfile) {
3416 error = -EOPNOTSUPP;
3417 goto out2;
3418 }
625b6d10 3419 child = d_alloc(path.dentry, &name);
60545d0d
AV
3420 if (unlikely(!child)) {
3421 error = -ENOMEM;
3422 goto out2;
3423 }
625b6d10
AV
3424 dput(path.dentry);
3425 path.dentry = child;
3426 error = dir->i_op->tmpfile(dir, child, op->mode);
60545d0d
AV
3427 if (error)
3428 goto out2;
c8a53ee5 3429 audit_inode(nd->name, child, 0);
69a91c23 3430 /* Don't check for other permissions, the inode was just created */
62fb4a15 3431 error = may_open(&path, 0, op->open_flag);
60545d0d
AV
3432 if (error)
3433 goto out2;
625b6d10
AV
3434 file->f_path.mnt = path.mnt;
3435 error = finish_open(file, child, NULL, opened);
60545d0d
AV
3436 if (error)
3437 goto out2;
3438 error = open_check_o_direct(file);
f4e0c30c 3439 if (error) {
60545d0d 3440 fput(file);
f4e0c30c
AV
3441 } else if (!(op->open_flag & O_EXCL)) {
3442 struct inode *inode = file_inode(file);
3443 spin_lock(&inode->i_lock);
3444 inode->i_state |= I_LINKABLE;
3445 spin_unlock(&inode->i_lock);
3446 }
60545d0d 3447out2:
625b6d10 3448 mnt_drop_write(path.mnt);
60545d0d 3449out:
625b6d10 3450 path_put(&path);
60545d0d
AV
3451 return error;
3452}
3453
6ac08709
AV
3454static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
3455{
3456 struct path path;
3457 int error = path_lookupat(nd, flags, &path);
3458 if (!error) {
3459 audit_inode(nd->name, path.dentry, 0);
3460 error = vfs_open(&path, file, current_cred());
3461 path_put(&path);
3462 }
3463 return error;
3464}
3465
c8a53ee5
AV
3466static struct file *path_openat(struct nameidata *nd,
3467 const struct open_flags *op, unsigned flags)
1da177e4 3468{
368ee9ba 3469 const char *s;
30d90494 3470 struct file *file;
47237687 3471 int opened = 0;
13aab428 3472 int error;
31e6b01f 3473
30d90494 3474 file = get_empty_filp();
1afc99be
AV
3475 if (IS_ERR(file))
3476 return file;
31e6b01f 3477
30d90494 3478 file->f_flags = op->open_flag;
31e6b01f 3479
bb458c64 3480 if (unlikely(file->f_flags & __O_TMPFILE)) {
c8a53ee5 3481 error = do_tmpfile(nd, flags, op, file, &opened);
f15133df 3482 goto out2;
60545d0d
AV
3483 }
3484
6ac08709
AV
3485 if (unlikely(file->f_flags & O_PATH)) {
3486 error = do_o_path(nd, flags, file);
3487 if (!error)
3488 opened |= FILE_OPENED;
3489 goto out2;
3490 }
3491
c8a53ee5 3492 s = path_init(nd, flags);
368ee9ba
AV
3493 if (IS_ERR(s)) {
3494 put_filp(file);
3495 return ERR_CAST(s);
3496 }
3bdba28b 3497 while (!(error = link_path_walk(s, nd)) &&
76ae2a5a 3498 (error = do_last(nd, file, op, &opened)) > 0) {
73d049a4 3499 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
3bdba28b
AV
3500 s = trailing_symlink(nd);
3501 if (IS_ERR(s)) {
3502 error = PTR_ERR(s);
2675a4eb 3503 break;
3bdba28b 3504 }
806b681c 3505 }
deb106c6 3506 terminate_walk(nd);
f15133df 3507out2:
2675a4eb
AV
3508 if (!(opened & FILE_OPENED)) {
3509 BUG_ON(!error);
30d90494 3510 put_filp(file);
16b1c1cd 3511 }
2675a4eb
AV
3512 if (unlikely(error)) {
3513 if (error == -EOPENSTALE) {
3514 if (flags & LOOKUP_RCU)
3515 error = -ECHILD;
3516 else
3517 error = -ESTALE;
3518 }
3519 file = ERR_PTR(error);
3520 }
3521 return file;
1da177e4
LT
3522}
3523
669abf4e 3524struct file *do_filp_open(int dfd, struct filename *pathname,
f9652e10 3525 const struct open_flags *op)
13aab428 3526{
9883d185 3527 struct nameidata nd;
f9652e10 3528 int flags = op->lookup_flags;
13aab428
AV
3529 struct file *filp;
3530
9883d185 3531 set_nameidata(&nd, dfd, pathname);
c8a53ee5 3532 filp = path_openat(&nd, op, flags | LOOKUP_RCU);
13aab428 3533 if (unlikely(filp == ERR_PTR(-ECHILD)))
c8a53ee5 3534 filp = path_openat(&nd, op, flags);
13aab428 3535 if (unlikely(filp == ERR_PTR(-ESTALE)))
c8a53ee5 3536 filp = path_openat(&nd, op, flags | LOOKUP_REVAL);
9883d185 3537 restore_nameidata();
13aab428
AV
3538 return filp;
3539}
3540
73d049a4 3541struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
f9652e10 3542 const char *name, const struct open_flags *op)
73d049a4 3543{
9883d185 3544 struct nameidata nd;
73d049a4 3545 struct file *file;
51689104 3546 struct filename *filename;
f9652e10 3547 int flags = op->lookup_flags | LOOKUP_ROOT;
73d049a4
AV
3548
3549 nd.root.mnt = mnt;
3550 nd.root.dentry = dentry;
3551
b18825a7 3552 if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
73d049a4
AV
3553 return ERR_PTR(-ELOOP);
3554
51689104 3555 filename = getname_kernel(name);
a1c83681 3556 if (IS_ERR(filename))
51689104
PM
3557 return ERR_CAST(filename);
3558
9883d185 3559 set_nameidata(&nd, -1, filename);
c8a53ee5 3560 file = path_openat(&nd, op, flags | LOOKUP_RCU);
73d049a4 3561 if (unlikely(file == ERR_PTR(-ECHILD)))
c8a53ee5 3562 file = path_openat(&nd, op, flags);
73d049a4 3563 if (unlikely(file == ERR_PTR(-ESTALE)))
c8a53ee5 3564 file = path_openat(&nd, op, flags | LOOKUP_REVAL);
9883d185 3565 restore_nameidata();
51689104 3566 putname(filename);
73d049a4
AV
3567 return file;
3568}
3569
fa14a0b8 3570static struct dentry *filename_create(int dfd, struct filename *name,
1ac12b4b 3571 struct path *path, unsigned int lookup_flags)
1da177e4 3572{
c663e5d8 3573 struct dentry *dentry = ERR_PTR(-EEXIST);
391172c4
AV
3574 struct qstr last;
3575 int type;
c30dabfe 3576 int err2;
1ac12b4b
JL
3577 int error;
3578 bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
3579
3580 /*
3581 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3582 * other flags passed in are ignored!
3583 */
3584 lookup_flags &= LOOKUP_REVAL;
3585
5c31b6ce
AV
3586 name = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
3587 if (IS_ERR(name))
3588 return ERR_CAST(name);
1da177e4 3589
c663e5d8
CH
3590 /*
3591 * Yucky last component or no last component at all?
3592 * (foo/., foo/.., /////)
3593 */
5c31b6ce 3594 if (unlikely(type != LAST_NORM))
ed75e95d 3595 goto out;
c663e5d8 3596
c30dabfe 3597 /* don't fail immediately if it's r/o, at least try to report other errors */
391172c4 3598 err2 = mnt_want_write(path->mnt);
c663e5d8
CH
3599 /*
3600 * Do the final lookup.
3601 */
391172c4 3602 lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
5955102c 3603 inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
391172c4 3604 dentry = __lookup_hash(&last, path->dentry, lookup_flags);
1da177e4 3605 if (IS_ERR(dentry))
a8104a9f 3606 goto unlock;
c663e5d8 3607
a8104a9f 3608 error = -EEXIST;
b18825a7 3609 if (d_is_positive(dentry))
a8104a9f 3610 goto fail;
b18825a7 3611
c663e5d8
CH
3612 /*
3613 * Special case - lookup gave negative, but... we had foo/bar/
3614 * From the vfs_mknod() POV we just have a negative dentry -
3615 * all is fine. Let's be bastards - you had / on the end, you've
3616 * been asking for (non-existent) directory. -ENOENT for you.
3617 */
391172c4 3618 if (unlikely(!is_dir && last.name[last.len])) {
a8104a9f 3619 error = -ENOENT;
ed75e95d 3620 goto fail;
e9baf6e5 3621 }
c30dabfe
JK
3622 if (unlikely(err2)) {
3623 error = err2;
a8104a9f 3624 goto fail;
c30dabfe 3625 }
181c37b6 3626 putname(name);
1da177e4 3627 return dentry;
1da177e4 3628fail:
a8104a9f
AV
3629 dput(dentry);
3630 dentry = ERR_PTR(error);
3631unlock:
5955102c 3632 inode_unlock(path->dentry->d_inode);
c30dabfe 3633 if (!err2)
391172c4 3634 mnt_drop_write(path->mnt);
ed75e95d 3635out:
391172c4 3636 path_put(path);
181c37b6 3637 putname(name);
1da177e4
LT
3638 return dentry;
3639}
fa14a0b8
AV
3640
3641struct dentry *kern_path_create(int dfd, const char *pathname,
3642 struct path *path, unsigned int lookup_flags)
3643{
181c37b6
AV
3644 return filename_create(dfd, getname_kernel(pathname),
3645 path, lookup_flags);
fa14a0b8 3646}
dae6ad8f
AV
3647EXPORT_SYMBOL(kern_path_create);
3648
921a1650
AV
3649void done_path_create(struct path *path, struct dentry *dentry)
3650{
3651 dput(dentry);
5955102c 3652 inode_unlock(path->dentry->d_inode);
a8104a9f 3653 mnt_drop_write(path->mnt);
921a1650
AV
3654 path_put(path);
3655}
3656EXPORT_SYMBOL(done_path_create);
3657
520ae687 3658inline struct dentry *user_path_create(int dfd, const char __user *pathname,
1ac12b4b 3659 struct path *path, unsigned int lookup_flags)
dae6ad8f 3660{
181c37b6 3661 return filename_create(dfd, getname(pathname), path, lookup_flags);
dae6ad8f
AV
3662}
3663EXPORT_SYMBOL(user_path_create);
3664
1a67aafb 3665int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1da177e4 3666{
a95164d9 3667 int error = may_create(dir, dentry);
1da177e4
LT
3668
3669 if (error)
3670 return error;
3671
975d6b39 3672 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1da177e4
LT
3673 return -EPERM;
3674
acfa4380 3675 if (!dir->i_op->mknod)
1da177e4
LT
3676 return -EPERM;
3677
08ce5f16
SH
3678 error = devcgroup_inode_mknod(mode, dev);
3679 if (error)
3680 return error;
3681
1da177e4
LT
3682 error = security_inode_mknod(dir, dentry, mode, dev);
3683 if (error)
3684 return error;
3685
1da177e4 3686 error = dir->i_op->mknod(dir, dentry, mode, dev);
a74574aa 3687 if (!error)
f38aa942 3688 fsnotify_create(dir, dentry);
1da177e4
LT
3689 return error;
3690}
4d359507 3691EXPORT_SYMBOL(vfs_mknod);
1da177e4 3692
f69aac00 3693static int may_mknod(umode_t mode)
463c3197
DH
3694{
3695 switch (mode & S_IFMT) {
3696 case S_IFREG:
3697 case S_IFCHR:
3698 case S_IFBLK:
3699 case S_IFIFO:
3700 case S_IFSOCK:
3701 case 0: /* zero mode translates to S_IFREG */
3702 return 0;
3703 case S_IFDIR:
3704 return -EPERM;
3705 default:
3706 return -EINVAL;
3707 }
3708}
3709
8208a22b 3710SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
2e4d0924 3711 unsigned, dev)
1da177e4 3712{
2ad94ae6 3713 struct dentry *dentry;
dae6ad8f
AV
3714 struct path path;
3715 int error;
972567f1 3716 unsigned int lookup_flags = 0;
1da177e4 3717
8e4bfca1
AV
3718 error = may_mknod(mode);
3719 if (error)
3720 return error;
972567f1
JL
3721retry:
3722 dentry = user_path_create(dfd, filename, &path, lookup_flags);
dae6ad8f
AV
3723 if (IS_ERR(dentry))
3724 return PTR_ERR(dentry);
2ad94ae6 3725
dae6ad8f 3726 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 3727 mode &= ~current_umask();
dae6ad8f 3728 error = security_path_mknod(&path, dentry, mode, dev);
be6d3e56 3729 if (error)
a8104a9f 3730 goto out;
463c3197 3731 switch (mode & S_IFMT) {
1da177e4 3732 case 0: case S_IFREG:
312b63fb 3733 error = vfs_create(path.dentry->d_inode,dentry,mode,true);
05d1a717
MZ
3734 if (!error)
3735 ima_post_path_mknod(dentry);
1da177e4
LT
3736 break;
3737 case S_IFCHR: case S_IFBLK:
dae6ad8f 3738 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
1da177e4
LT
3739 new_decode_dev(dev));
3740 break;
3741 case S_IFIFO: case S_IFSOCK:
dae6ad8f 3742 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
1da177e4 3743 break;
1da177e4 3744 }
a8104a9f 3745out:
921a1650 3746 done_path_create(&path, dentry);
972567f1
JL
3747 if (retry_estale(error, lookup_flags)) {
3748 lookup_flags |= LOOKUP_REVAL;
3749 goto retry;
3750 }
1da177e4
LT
3751 return error;
3752}
3753
8208a22b 3754SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
5590ff0d
UD
3755{
3756 return sys_mknodat(AT_FDCWD, filename, mode, dev);
3757}
3758
18bb1db3 3759int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1da177e4 3760{
a95164d9 3761 int error = may_create(dir, dentry);
8de52778 3762 unsigned max_links = dir->i_sb->s_max_links;
1da177e4
LT
3763
3764 if (error)
3765 return error;
3766
acfa4380 3767 if (!dir->i_op->mkdir)
1da177e4
LT
3768 return -EPERM;
3769
3770 mode &= (S_IRWXUGO|S_ISVTX);
3771 error = security_inode_mkdir(dir, dentry, mode);
3772 if (error)
3773 return error;
3774
8de52778
AV
3775 if (max_links && dir->i_nlink >= max_links)
3776 return -EMLINK;
3777
1da177e4 3778 error = dir->i_op->mkdir(dir, dentry, mode);
a74574aa 3779 if (!error)
f38aa942 3780 fsnotify_mkdir(dir, dentry);
1da177e4
LT
3781 return error;
3782}
4d359507 3783EXPORT_SYMBOL(vfs_mkdir);
1da177e4 3784
a218d0fd 3785SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
1da177e4 3786{
6902d925 3787 struct dentry *dentry;
dae6ad8f
AV
3788 struct path path;
3789 int error;
b76d8b82 3790 unsigned int lookup_flags = LOOKUP_DIRECTORY;
1da177e4 3791
b76d8b82
JL
3792retry:
3793 dentry = user_path_create(dfd, pathname, &path, lookup_flags);
6902d925 3794 if (IS_ERR(dentry))
dae6ad8f 3795 return PTR_ERR(dentry);
1da177e4 3796
dae6ad8f 3797 if (!IS_POSIXACL(path.dentry->d_inode))
ce3b0f8d 3798 mode &= ~current_umask();
dae6ad8f 3799 error = security_path_mkdir(&path, dentry, mode);
a8104a9f
AV
3800 if (!error)
3801 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
921a1650 3802 done_path_create(&path, dentry);
b76d8b82
JL
3803 if (retry_estale(error, lookup_flags)) {
3804 lookup_flags |= LOOKUP_REVAL;
3805 goto retry;
3806 }
1da177e4
LT
3807 return error;
3808}
3809
a218d0fd 3810SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
5590ff0d
UD
3811{
3812 return sys_mkdirat(AT_FDCWD, pathname, mode);
3813}
3814
1da177e4
LT
3815int vfs_rmdir(struct inode *dir, struct dentry *dentry)
3816{
3817 int error = may_delete(dir, dentry, 1);
3818
3819 if (error)
3820 return error;
3821
acfa4380 3822 if (!dir->i_op->rmdir)
1da177e4
LT
3823 return -EPERM;
3824
1d2ef590 3825 dget(dentry);
5955102c 3826 inode_lock(dentry->d_inode);
912dbc15
SW
3827
3828 error = -EBUSY;
7af1364f 3829 if (is_local_mountpoint(dentry))
912dbc15
SW
3830 goto out;
3831
3832 error = security_inode_rmdir(dir, dentry);
3833 if (error)
3834 goto out;
3835
3cebde24 3836 shrink_dcache_parent(dentry);
912dbc15
SW
3837 error = dir->i_op->rmdir(dir, dentry);
3838 if (error)
3839 goto out;
3840
3841 dentry->d_inode->i_flags |= S_DEAD;
3842 dont_mount(dentry);
8ed936b5 3843 detach_mounts(dentry);
912dbc15
SW
3844
3845out:
5955102c 3846 inode_unlock(dentry->d_inode);
1d2ef590 3847 dput(dentry);
912dbc15 3848 if (!error)
1da177e4 3849 d_delete(dentry);
1da177e4
LT
3850 return error;
3851}
4d359507 3852EXPORT_SYMBOL(vfs_rmdir);
1da177e4 3853
5590ff0d 3854static long do_rmdir(int dfd, const char __user *pathname)
1da177e4
LT
3855{
3856 int error = 0;
91a27b2a 3857 struct filename *name;
1da177e4 3858 struct dentry *dentry;
f5beed75
AV
3859 struct path path;
3860 struct qstr last;
3861 int type;
c6ee9206
JL
3862 unsigned int lookup_flags = 0;
3863retry:
f5beed75
AV
3864 name = user_path_parent(dfd, pathname,
3865 &path, &last, &type, lookup_flags);
91a27b2a
JL
3866 if (IS_ERR(name))
3867 return PTR_ERR(name);
1da177e4 3868
f5beed75 3869 switch (type) {
0612d9fb
OH
3870 case LAST_DOTDOT:
3871 error = -ENOTEMPTY;
3872 goto exit1;
3873 case LAST_DOT:
3874 error = -EINVAL;
3875 goto exit1;
3876 case LAST_ROOT:
3877 error = -EBUSY;
3878 goto exit1;
1da177e4 3879 }
0612d9fb 3880
f5beed75 3881 error = mnt_want_write(path.mnt);
c30dabfe
JK
3882 if (error)
3883 goto exit1;
0612d9fb 3884
5955102c 3885 inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
f5beed75 3886 dentry = __lookup_hash(&last, path.dentry, lookup_flags);
1da177e4 3887 error = PTR_ERR(dentry);
6902d925
DH
3888 if (IS_ERR(dentry))
3889 goto exit2;
e6bc45d6
TT
3890 if (!dentry->d_inode) {
3891 error = -ENOENT;
3892 goto exit3;
3893 }
f5beed75 3894 error = security_path_rmdir(&path, dentry);
be6d3e56 3895 if (error)
c30dabfe 3896 goto exit3;
f5beed75 3897 error = vfs_rmdir(path.dentry->d_inode, dentry);
0622753b 3898exit3:
6902d925
DH
3899 dput(dentry);
3900exit2:
5955102c 3901 inode_unlock(path.dentry->d_inode);
f5beed75 3902 mnt_drop_write(path.mnt);
1da177e4 3903exit1:
f5beed75 3904 path_put(&path);
1da177e4 3905 putname(name);
c6ee9206
JL
3906 if (retry_estale(error, lookup_flags)) {
3907 lookup_flags |= LOOKUP_REVAL;
3908 goto retry;
3909 }
1da177e4
LT
3910 return error;
3911}
3912
3cdad428 3913SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
5590ff0d
UD
3914{
3915 return do_rmdir(AT_FDCWD, pathname);
3916}
3917
b21996e3
BF
3918/**
3919 * vfs_unlink - unlink a filesystem object
3920 * @dir: parent directory
3921 * @dentry: victim
3922 * @delegated_inode: returns victim inode, if the inode is delegated.
3923 *
3924 * The caller must hold dir->i_mutex.
3925 *
3926 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3927 * return a reference to the inode in delegated_inode. The caller
3928 * should then break the delegation on that inode and retry. Because
3929 * breaking a delegation may take a long time, the caller should drop
3930 * dir->i_mutex before doing so.
3931 *
3932 * Alternatively, a caller may pass NULL for delegated_inode. This may
3933 * be appropriate for callers that expect the underlying filesystem not
3934 * to be NFS exported.
3935 */
3936int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
1da177e4 3937{
9accbb97 3938 struct inode *target = dentry->d_inode;
1da177e4
LT
3939 int error = may_delete(dir, dentry, 0);
3940
3941 if (error)
3942 return error;
3943
acfa4380 3944 if (!dir->i_op->unlink)
1da177e4
LT
3945 return -EPERM;
3946
5955102c 3947 inode_lock(target);
8ed936b5 3948 if (is_local_mountpoint(dentry))
1da177e4
LT
3949 error = -EBUSY;
3950 else {
3951 error = security_inode_unlink(dir, dentry);
bec1052e 3952 if (!error) {
5a14696c
BF
3953 error = try_break_deleg(target, delegated_inode);
3954 if (error)
b21996e3 3955 goto out;
1da177e4 3956 error = dir->i_op->unlink(dir, dentry);
8ed936b5 3957 if (!error) {
d83c49f3 3958 dont_mount(dentry);
8ed936b5
EB
3959 detach_mounts(dentry);
3960 }
bec1052e 3961 }
1da177e4 3962 }
b21996e3 3963out:
5955102c 3964 inode_unlock(target);
1da177e4
LT
3965
3966 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3967 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
9accbb97 3968 fsnotify_link_count(target);
e234f35c 3969 d_delete(dentry);
1da177e4 3970 }
0eeca283 3971
1da177e4
LT
3972 return error;
3973}
4d359507 3974EXPORT_SYMBOL(vfs_unlink);
1da177e4
LT
3975
3976/*
3977 * Make sure that the actual truncation of the file will occur outside its
1b1dcc1b 3978 * directory's i_mutex. Truncate can take a long time if there is a lot of
1da177e4
LT
3979 * writeout happening, and we don't want to prevent access to the directory
3980 * while waiting on the I/O.
3981 */
5590ff0d 3982static long do_unlinkat(int dfd, const char __user *pathname)
1da177e4 3983{
2ad94ae6 3984 int error;
91a27b2a 3985 struct filename *name;
1da177e4 3986 struct dentry *dentry;
f5beed75
AV
3987 struct path path;
3988 struct qstr last;
3989 int type;
1da177e4 3990 struct inode *inode = NULL;
b21996e3 3991 struct inode *delegated_inode = NULL;
5d18f813
JL
3992 unsigned int lookup_flags = 0;
3993retry:
f5beed75
AV
3994 name = user_path_parent(dfd, pathname,
3995 &path, &last, &type, lookup_flags);
91a27b2a
JL
3996 if (IS_ERR(name))
3997 return PTR_ERR(name);
2ad94ae6 3998
1da177e4 3999 error = -EISDIR;
f5beed75 4000 if (type != LAST_NORM)
1da177e4 4001 goto exit1;
0612d9fb 4002
f5beed75 4003 error = mnt_want_write(path.mnt);
c30dabfe
JK
4004 if (error)
4005 goto exit1;
b21996e3 4006retry_deleg:
5955102c 4007 inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
f5beed75 4008 dentry = __lookup_hash(&last, path.dentry, lookup_flags);
1da177e4
LT
4009 error = PTR_ERR(dentry);
4010 if (!IS_ERR(dentry)) {
4011 /* Why not before? Because we want correct error value */
f5beed75 4012 if (last.name[last.len])
50338b88 4013 goto slashes;
1da177e4 4014 inode = dentry->d_inode;
b18825a7 4015 if (d_is_negative(dentry))
e6bc45d6
TT
4016 goto slashes;
4017 ihold(inode);
f5beed75 4018 error = security_path_unlink(&path, dentry);
be6d3e56 4019 if (error)
c30dabfe 4020 goto exit2;
f5beed75 4021 error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode);
c30dabfe 4022exit2:
1da177e4
LT
4023 dput(dentry);
4024 }
5955102c 4025 inode_unlock(path.dentry->d_inode);
1da177e4
LT
4026 if (inode)
4027 iput(inode); /* truncate the inode here */
b21996e3
BF
4028 inode = NULL;
4029 if (delegated_inode) {
5a14696c 4030 error = break_deleg_wait(&delegated_inode);
b21996e3
BF
4031 if (!error)
4032 goto retry_deleg;
4033 }
f5beed75 4034 mnt_drop_write(path.mnt);
1da177e4 4035exit1:
f5beed75 4036 path_put(&path);
1da177e4 4037 putname(name);
5d18f813
JL
4038 if (retry_estale(error, lookup_flags)) {
4039 lookup_flags |= LOOKUP_REVAL;
4040 inode = NULL;
4041 goto retry;
4042 }
1da177e4
LT
4043 return error;
4044
4045slashes:
b18825a7
DH
4046 if (d_is_negative(dentry))
4047 error = -ENOENT;
44b1d530 4048 else if (d_is_dir(dentry))
b18825a7
DH
4049 error = -EISDIR;
4050 else
4051 error = -ENOTDIR;
1da177e4
LT
4052 goto exit2;
4053}
4054
2e4d0924 4055SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
5590ff0d
UD
4056{
4057 if ((flag & ~AT_REMOVEDIR) != 0)
4058 return -EINVAL;
4059
4060 if (flag & AT_REMOVEDIR)
4061 return do_rmdir(dfd, pathname);
4062
4063 return do_unlinkat(dfd, pathname);
4064}
4065
3480b257 4066SYSCALL_DEFINE1(unlink, const char __user *, pathname)
5590ff0d
UD
4067{
4068 return do_unlinkat(AT_FDCWD, pathname);
4069}
4070
db2e747b 4071int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
1da177e4 4072{
a95164d9 4073 int error = may_create(dir, dentry);
1da177e4
LT
4074
4075 if (error)
4076 return error;
4077
acfa4380 4078 if (!dir->i_op->symlink)
1da177e4
LT
4079 return -EPERM;
4080
4081 error = security_inode_symlink(dir, dentry, oldname);
4082 if (error)
4083 return error;
4084
1da177e4 4085 error = dir->i_op->symlink(dir, dentry, oldname);
a74574aa 4086 if (!error)
f38aa942 4087 fsnotify_create(dir, dentry);
1da177e4
LT
4088 return error;
4089}
4d359507 4090EXPORT_SYMBOL(vfs_symlink);
1da177e4 4091
2e4d0924
HC
4092SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
4093 int, newdfd, const char __user *, newname)
1da177e4 4094{
2ad94ae6 4095 int error;
91a27b2a 4096 struct filename *from;
6902d925 4097 struct dentry *dentry;
dae6ad8f 4098 struct path path;
f46d3567 4099 unsigned int lookup_flags = 0;
1da177e4
LT
4100
4101 from = getname(oldname);
2ad94ae6 4102 if (IS_ERR(from))
1da177e4 4103 return PTR_ERR(from);
f46d3567
JL
4104retry:
4105 dentry = user_path_create(newdfd, newname, &path, lookup_flags);
6902d925
DH
4106 error = PTR_ERR(dentry);
4107 if (IS_ERR(dentry))
dae6ad8f 4108 goto out_putname;
6902d925 4109
91a27b2a 4110 error = security_path_symlink(&path, dentry, from->name);
a8104a9f 4111 if (!error)
91a27b2a 4112 error = vfs_symlink(path.dentry->d_inode, dentry, from->name);
921a1650 4113 done_path_create(&path, dentry);
f46d3567
JL
4114 if (retry_estale(error, lookup_flags)) {
4115 lookup_flags |= LOOKUP_REVAL;
4116 goto retry;
4117 }
6902d925 4118out_putname:
1da177e4
LT
4119 putname(from);
4120 return error;
4121}
4122
3480b257 4123SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
5590ff0d
UD
4124{
4125 return sys_symlinkat(oldname, AT_FDCWD, newname);
4126}
4127
146a8595
BF
4128/**
4129 * vfs_link - create a new link
4130 * @old_dentry: object to be linked
4131 * @dir: new parent
4132 * @new_dentry: where to create the new link
4133 * @delegated_inode: returns inode needing a delegation break
4134 *
4135 * The caller must hold dir->i_mutex
4136 *
4137 * If vfs_link discovers a delegation on the to-be-linked file in need
4138 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4139 * inode in delegated_inode. The caller should then break the delegation
4140 * and retry. Because breaking a delegation may take a long time, the
4141 * caller should drop the i_mutex before doing so.
4142 *
4143 * Alternatively, a caller may pass NULL for delegated_inode. This may
4144 * be appropriate for callers that expect the underlying filesystem not
4145 * to be NFS exported.
4146 */
4147int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
1da177e4
LT
4148{
4149 struct inode *inode = old_dentry->d_inode;
8de52778 4150 unsigned max_links = dir->i_sb->s_max_links;
1da177e4
LT
4151 int error;
4152
4153 if (!inode)
4154 return -ENOENT;
4155
a95164d9 4156 error = may_create(dir, new_dentry);
1da177e4
LT
4157 if (error)
4158 return error;
4159
4160 if (dir->i_sb != inode->i_sb)
4161 return -EXDEV;
4162
4163 /*
4164 * A link to an append-only or immutable file cannot be created.
4165 */
4166 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
4167 return -EPERM;
0bd23d09
EB
4168 /*
4169 * Updating the link count will likely cause i_uid and i_gid to
4170 * be writen back improperly if their true value is unknown to
4171 * the vfs.
4172 */
4173 if (HAS_UNMAPPED_ID(inode))
4174 return -EPERM;
acfa4380 4175 if (!dir->i_op->link)
1da177e4 4176 return -EPERM;
7e79eedb 4177 if (S_ISDIR(inode->i_mode))
1da177e4
LT
4178 return -EPERM;
4179
4180 error = security_inode_link(old_dentry, dir, new_dentry);
4181 if (error)
4182 return error;
4183
5955102c 4184 inode_lock(inode);
aae8a97d 4185 /* Make sure we don't allow creating hardlink to an unlinked file */
f4e0c30c 4186 if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
aae8a97d 4187 error = -ENOENT;
8de52778
AV
4188 else if (max_links && inode->i_nlink >= max_links)
4189 error = -EMLINK;
146a8595
BF
4190 else {
4191 error = try_break_deleg(inode, delegated_inode);
4192 if (!error)
4193 error = dir->i_op->link(old_dentry, dir, new_dentry);
4194 }
f4e0c30c
AV
4195
4196 if (!error && (inode->i_state & I_LINKABLE)) {
4197 spin_lock(&inode->i_lock);
4198 inode->i_state &= ~I_LINKABLE;
4199 spin_unlock(&inode->i_lock);
4200 }
5955102c 4201 inode_unlock(inode);
e31e14ec 4202 if (!error)
7e79eedb 4203 fsnotify_link(dir, inode, new_dentry);
1da177e4
LT
4204 return error;
4205}
4d359507 4206EXPORT_SYMBOL(vfs_link);
1da177e4
LT
4207
4208/*
4209 * Hardlinks are often used in delicate situations. We avoid
4210 * security-related surprises by not following symlinks on the
4211 * newname. --KAB
4212 *
4213 * We don't follow them on the oldname either to be compatible
4214 * with linux 2.0, and to avoid hard-linking to directories
4215 * and other special files. --ADM
4216 */
2e4d0924
HC
4217SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
4218 int, newdfd, const char __user *, newname, int, flags)
1da177e4
LT
4219{
4220 struct dentry *new_dentry;
dae6ad8f 4221 struct path old_path, new_path;
146a8595 4222 struct inode *delegated_inode = NULL;
11a7b371 4223 int how = 0;
1da177e4 4224 int error;
1da177e4 4225
11a7b371 4226 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
c04030e1 4227 return -EINVAL;
11a7b371 4228 /*
f0cc6ffb
LT
4229 * To use null names we require CAP_DAC_READ_SEARCH
4230 * This ensures that not everyone will be able to create
4231 * handlink using the passed filedescriptor.
11a7b371 4232 */
f0cc6ffb
LT
4233 if (flags & AT_EMPTY_PATH) {
4234 if (!capable(CAP_DAC_READ_SEARCH))
4235 return -ENOENT;
11a7b371 4236 how = LOOKUP_EMPTY;
f0cc6ffb 4237 }
11a7b371
AK
4238
4239 if (flags & AT_SYMLINK_FOLLOW)
4240 how |= LOOKUP_FOLLOW;
442e31ca 4241retry:
11a7b371 4242 error = user_path_at(olddfd, oldname, how, &old_path);
1da177e4 4243 if (error)
2ad94ae6
AV
4244 return error;
4245
442e31ca
JL
4246 new_dentry = user_path_create(newdfd, newname, &new_path,
4247 (how & LOOKUP_REVAL));
1da177e4 4248 error = PTR_ERR(new_dentry);
6902d925 4249 if (IS_ERR(new_dentry))
dae6ad8f
AV
4250 goto out;
4251
4252 error = -EXDEV;
4253 if (old_path.mnt != new_path.mnt)
4254 goto out_dput;
800179c9
KC
4255 error = may_linkat(&old_path);
4256 if (unlikely(error))
4257 goto out_dput;
dae6ad8f 4258 error = security_path_link(old_path.dentry, &new_path, new_dentry);
be6d3e56 4259 if (error)
a8104a9f 4260 goto out_dput;
146a8595 4261 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode);
75c3f29d 4262out_dput:
921a1650 4263 done_path_create(&new_path, new_dentry);
146a8595
BF
4264 if (delegated_inode) {
4265 error = break_deleg_wait(&delegated_inode);
d22e6338
OD
4266 if (!error) {
4267 path_put(&old_path);
146a8595 4268 goto retry;
d22e6338 4269 }
146a8595 4270 }
442e31ca 4271 if (retry_estale(error, how)) {
d22e6338 4272 path_put(&old_path);
442e31ca
JL
4273 how |= LOOKUP_REVAL;
4274 goto retry;
4275 }
1da177e4 4276out:
2d8f3038 4277 path_put(&old_path);
1da177e4
LT
4278
4279 return error;
4280}
4281
3480b257 4282SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
5590ff0d 4283{
c04030e1 4284 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
5590ff0d
UD
4285}
4286
bc27027a
MS
4287/**
4288 * vfs_rename - rename a filesystem object
4289 * @old_dir: parent of source
4290 * @old_dentry: source
4291 * @new_dir: parent of destination
4292 * @new_dentry: destination
4293 * @delegated_inode: returns an inode needing a delegation break
520c8b16 4294 * @flags: rename flags
bc27027a
MS
4295 *
4296 * The caller must hold multiple mutexes--see lock_rename()).
4297 *
4298 * If vfs_rename discovers a delegation in need of breaking at either
4299 * the source or destination, it will return -EWOULDBLOCK and return a
4300 * reference to the inode in delegated_inode. The caller should then
4301 * break the delegation and retry. Because breaking a delegation may
4302 * take a long time, the caller should drop all locks before doing
4303 * so.
4304 *
4305 * Alternatively, a caller may pass NULL for delegated_inode. This may
4306 * be appropriate for callers that expect the underlying filesystem not
4307 * to be NFS exported.
4308 *
1da177e4
LT
4309 * The worst of all namespace operations - renaming directory. "Perverted"
4310 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4311 * Problems:
d03b29a2 4312 * a) we can get into loop creation.
1da177e4
LT
4313 * b) race potential - two innocent renames can create a loop together.
4314 * That's where 4.4 screws up. Current fix: serialization on
a11f3a05 4315 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
1da177e4 4316 * story.
6cedba89
BF
4317 * c) we have to lock _four_ objects - parents and victim (if it exists),
4318 * and source (if it is not a directory).
1b1dcc1b 4319 * And that - after we got ->i_mutex on parents (until then we don't know
1da177e4
LT
4320 * whether the target exists). Solution: try to be smart with locking
4321 * order for inodes. We rely on the fact that tree topology may change
a11f3a05 4322 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
1da177e4
LT
4323 * move will be locked. Thus we can rank directories by the tree
4324 * (ancestors first) and rank all non-directories after them.
4325 * That works since everybody except rename does "lock parent, lookup,
a11f3a05 4326 * lock child" and rename is under ->s_vfs_rename_mutex.
1da177e4
LT
4327 * HOWEVER, it relies on the assumption that any object with ->lookup()
4328 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4329 * we'd better make sure that there's no link(2) for them.
e4eaac06 4330 * d) conversion from fhandle to dentry may come in the wrong moment - when
1b1dcc1b 4331 * we are removing the target. Solution: we will have to grab ->i_mutex
1da177e4 4332 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
c41b20e7 4333 * ->i_mutex on parents, which works but leads to some truly excessive
1da177e4
LT
4334 * locking].
4335 */
bc27027a
MS
4336int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
4337 struct inode *new_dir, struct dentry *new_dentry,
520c8b16 4338 struct inode **delegated_inode, unsigned int flags)
1da177e4 4339{
bc27027a
MS
4340 int error;
4341 bool is_dir = d_is_dir(old_dentry);
4342 const unsigned char *old_name;
4343 struct inode *source = old_dentry->d_inode;
9055cba7 4344 struct inode *target = new_dentry->d_inode;
da1ce067
MS
4345 bool new_is_dir = false;
4346 unsigned max_links = new_dir->i_sb->s_max_links;
bc27027a 4347
9409e22a
MS
4348 /*
4349 * Check source == target.
4350 * On overlayfs need to look at underlying inodes.
4351 */
2d902671 4352 if (d_real_inode(old_dentry) == d_real_inode(new_dentry))
bc27027a
MS
4353 return 0;
4354
4355 error = may_delete(old_dir, old_dentry, is_dir);
4356 if (error)
4357 return error;
4358
da1ce067 4359 if (!target) {
bc27027a 4360 error = may_create(new_dir, new_dentry);
da1ce067
MS
4361 } else {
4362 new_is_dir = d_is_dir(new_dentry);
4363
4364 if (!(flags & RENAME_EXCHANGE))
4365 error = may_delete(new_dir, new_dentry, is_dir);
4366 else
4367 error = may_delete(new_dir, new_dentry, new_is_dir);
4368 }
bc27027a
MS
4369 if (error)
4370 return error;
4371
2773bf00 4372 if (!old_dir->i_op->rename)
bc27027a 4373 return -EPERM;
1da177e4
LT
4374
4375 /*
4376 * If we are going to change the parent - check write permissions,
4377 * we'll need to flip '..'.
4378 */
da1ce067
MS
4379 if (new_dir != old_dir) {
4380 if (is_dir) {
4381 error = inode_permission(source, MAY_WRITE);
4382 if (error)
4383 return error;
4384 }
4385 if ((flags & RENAME_EXCHANGE) && new_is_dir) {
4386 error = inode_permission(target, MAY_WRITE);
4387 if (error)
4388 return error;
4389 }
1da177e4
LT
4390 }
4391
0b3974eb
MS
4392 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry,
4393 flags);
1da177e4
LT
4394 if (error)
4395 return error;
4396
bc27027a 4397 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
1d2ef590 4398 dget(new_dentry);
da1ce067 4399 if (!is_dir || (flags & RENAME_EXCHANGE))
bc27027a
MS
4400 lock_two_nondirectories(source, target);
4401 else if (target)
5955102c 4402 inode_lock(target);
9055cba7
SW
4403
4404 error = -EBUSY;
7af1364f 4405 if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry))
9055cba7
SW
4406 goto out;
4407
da1ce067 4408 if (max_links && new_dir != old_dir) {
bc27027a 4409 error = -EMLINK;
da1ce067 4410 if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links)
bc27027a 4411 goto out;
da1ce067
MS
4412 if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
4413 old_dir->i_nlink >= max_links)
4414 goto out;
4415 }
4416 if (is_dir && !(flags & RENAME_EXCHANGE) && target)
4417 shrink_dcache_parent(new_dentry);
4418 if (!is_dir) {
bc27027a 4419 error = try_break_deleg(source, delegated_inode);
8e6d782c
BF
4420 if (error)
4421 goto out;
da1ce067
MS
4422 }
4423 if (target && !new_is_dir) {
4424 error = try_break_deleg(target, delegated_inode);
4425 if (error)
4426 goto out;
8e6d782c 4427 }
2773bf00 4428 error = old_dir->i_op->rename(old_dir, old_dentry,
18fc84da 4429 new_dir, new_dentry, flags);
51892bbb
SW
4430 if (error)
4431 goto out;
4432
da1ce067 4433 if (!(flags & RENAME_EXCHANGE) && target) {
bc27027a
MS
4434 if (is_dir)
4435 target->i_flags |= S_DEAD;
51892bbb 4436 dont_mount(new_dentry);
8ed936b5 4437 detach_mounts(new_dentry);
bc27027a 4438 }
da1ce067
MS
4439 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) {
4440 if (!(flags & RENAME_EXCHANGE))
4441 d_move(old_dentry, new_dentry);
4442 else
4443 d_exchange(old_dentry, new_dentry);
4444 }
51892bbb 4445out:
da1ce067 4446 if (!is_dir || (flags & RENAME_EXCHANGE))
bc27027a
MS
4447 unlock_two_nondirectories(source, target);
4448 else if (target)
5955102c 4449 inode_unlock(target);
1da177e4 4450 dput(new_dentry);
da1ce067 4451 if (!error) {
123df294 4452 fsnotify_move(old_dir, new_dir, old_name, is_dir,
da1ce067
MS
4453 !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
4454 if (flags & RENAME_EXCHANGE) {
4455 fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
4456 new_is_dir, NULL, new_dentry);
4457 }
4458 }
0eeca283
RL
4459 fsnotify_oldname_free(old_name);
4460
1da177e4
LT
4461 return error;
4462}
4d359507 4463EXPORT_SYMBOL(vfs_rename);
1da177e4 4464
520c8b16
MS
4465SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
4466 int, newdfd, const char __user *, newname, unsigned int, flags)
1da177e4 4467{
2ad94ae6
AV
4468 struct dentry *old_dentry, *new_dentry;
4469 struct dentry *trap;
f5beed75
AV
4470 struct path old_path, new_path;
4471 struct qstr old_last, new_last;
4472 int old_type, new_type;
8e6d782c 4473 struct inode *delegated_inode = NULL;
91a27b2a
JL
4474 struct filename *from;
4475 struct filename *to;
f5beed75 4476 unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
c6a94284 4477 bool should_retry = false;
2ad94ae6 4478 int error;
520c8b16 4479
0d7a8555 4480 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
da1ce067
MS
4481 return -EINVAL;
4482
0d7a8555
MS
4483 if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
4484 (flags & RENAME_EXCHANGE))
520c8b16
MS
4485 return -EINVAL;
4486
0d7a8555
MS
4487 if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
4488 return -EPERM;
4489
f5beed75
AV
4490 if (flags & RENAME_EXCHANGE)
4491 target_flags = 0;
4492
c6a94284 4493retry:
f5beed75
AV
4494 from = user_path_parent(olddfd, oldname,
4495 &old_path, &old_last, &old_type, lookup_flags);
91a27b2a
JL
4496 if (IS_ERR(from)) {
4497 error = PTR_ERR(from);
1da177e4 4498 goto exit;
91a27b2a 4499 }
1da177e4 4500
f5beed75
AV
4501 to = user_path_parent(newdfd, newname,
4502 &new_path, &new_last, &new_type, lookup_flags);
91a27b2a
JL
4503 if (IS_ERR(to)) {
4504 error = PTR_ERR(to);
1da177e4 4505 goto exit1;
91a27b2a 4506 }
1da177e4
LT
4507
4508 error = -EXDEV;
f5beed75 4509 if (old_path.mnt != new_path.mnt)
1da177e4
LT
4510 goto exit2;
4511
1da177e4 4512 error = -EBUSY;
f5beed75 4513 if (old_type != LAST_NORM)
1da177e4
LT
4514 goto exit2;
4515
0a7c3937
MS
4516 if (flags & RENAME_NOREPLACE)
4517 error = -EEXIST;
f5beed75 4518 if (new_type != LAST_NORM)
1da177e4
LT
4519 goto exit2;
4520
f5beed75 4521 error = mnt_want_write(old_path.mnt);
c30dabfe
JK
4522 if (error)
4523 goto exit2;
4524
8e6d782c 4525retry_deleg:
f5beed75 4526 trap = lock_rename(new_path.dentry, old_path.dentry);
1da177e4 4527
f5beed75 4528 old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
1da177e4
LT
4529 error = PTR_ERR(old_dentry);
4530 if (IS_ERR(old_dentry))
4531 goto exit3;
4532 /* source must exist */
4533 error = -ENOENT;
b18825a7 4534 if (d_is_negative(old_dentry))
1da177e4 4535 goto exit4;
f5beed75 4536 new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags);
0a7c3937
MS
4537 error = PTR_ERR(new_dentry);
4538 if (IS_ERR(new_dentry))
4539 goto exit4;
4540 error = -EEXIST;
4541 if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
4542 goto exit5;
da1ce067
MS
4543 if (flags & RENAME_EXCHANGE) {
4544 error = -ENOENT;
4545 if (d_is_negative(new_dentry))
4546 goto exit5;
4547
4548 if (!d_is_dir(new_dentry)) {
4549 error = -ENOTDIR;
f5beed75 4550 if (new_last.name[new_last.len])
da1ce067
MS
4551 goto exit5;
4552 }
4553 }
1da177e4 4554 /* unless the source is a directory trailing slashes give -ENOTDIR */
44b1d530 4555 if (!d_is_dir(old_dentry)) {
1da177e4 4556 error = -ENOTDIR;
f5beed75 4557 if (old_last.name[old_last.len])
0a7c3937 4558 goto exit5;
f5beed75 4559 if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len])
0a7c3937 4560 goto exit5;
1da177e4
LT
4561 }
4562 /* source should not be ancestor of target */
4563 error = -EINVAL;
4564 if (old_dentry == trap)
0a7c3937 4565 goto exit5;
1da177e4 4566 /* target should not be an ancestor of source */
da1ce067
MS
4567 if (!(flags & RENAME_EXCHANGE))
4568 error = -ENOTEMPTY;
1da177e4
LT
4569 if (new_dentry == trap)
4570 goto exit5;
4571
f5beed75
AV
4572 error = security_path_rename(&old_path, old_dentry,
4573 &new_path, new_dentry, flags);
be6d3e56 4574 if (error)
c30dabfe 4575 goto exit5;
f5beed75
AV
4576 error = vfs_rename(old_path.dentry->d_inode, old_dentry,
4577 new_path.dentry->d_inode, new_dentry,
520c8b16 4578 &delegated_inode, flags);
1da177e4
LT
4579exit5:
4580 dput(new_dentry);
4581exit4:
4582 dput(old_dentry);
4583exit3:
f5beed75 4584 unlock_rename(new_path.dentry, old_path.dentry);
8e6d782c
BF
4585 if (delegated_inode) {
4586 error = break_deleg_wait(&delegated_inode);
4587 if (!error)
4588 goto retry_deleg;
4589 }
f5beed75 4590 mnt_drop_write(old_path.mnt);
1da177e4 4591exit2:
c6a94284
JL
4592 if (retry_estale(error, lookup_flags))
4593 should_retry = true;
f5beed75 4594 path_put(&new_path);
2ad94ae6 4595 putname(to);
1da177e4 4596exit1:
f5beed75 4597 path_put(&old_path);
1da177e4 4598 putname(from);
c6a94284
JL
4599 if (should_retry) {
4600 should_retry = false;
4601 lookup_flags |= LOOKUP_REVAL;
4602 goto retry;
4603 }
2ad94ae6 4604exit:
1da177e4
LT
4605 return error;
4606}
4607
520c8b16
MS
4608SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
4609 int, newdfd, const char __user *, newname)
4610{
4611 return sys_renameat2(olddfd, oldname, newdfd, newname, 0);
4612}
4613
a26eab24 4614SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
5590ff0d 4615{
520c8b16 4616 return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
5590ff0d
UD
4617}
4618
787fb6bc
MS
4619int vfs_whiteout(struct inode *dir, struct dentry *dentry)
4620{
4621 int error = may_create(dir, dentry);
4622 if (error)
4623 return error;
4624
4625 if (!dir->i_op->mknod)
4626 return -EPERM;
4627
4628 return dir->i_op->mknod(dir, dentry,
4629 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
4630}
4631EXPORT_SYMBOL(vfs_whiteout);
4632
5d826c84 4633int readlink_copy(char __user *buffer, int buflen, const char *link)
1da177e4 4634{
5d826c84 4635 int len = PTR_ERR(link);
1da177e4
LT
4636 if (IS_ERR(link))
4637 goto out;
4638
4639 len = strlen(link);
4640 if (len > (unsigned) buflen)
4641 len = buflen;
4642 if (copy_to_user(buffer, link, len))
4643 len = -EFAULT;
4644out:
4645 return len;
4646}
4647
4648/*
4649 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
6b255391
AV
4650 * have ->get_link() not calling nd_jump_link(). Using (or not using) it
4651 * for any given inode is up to filesystem.
1da177e4
LT
4652 */
4653int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
4654{
fceef393 4655 DEFINE_DELAYED_CALL(done);
5f2c4179
AV
4656 struct inode *inode = d_inode(dentry);
4657 const char *link = inode->i_link;
694a1764 4658 int res;
cc314eef 4659
d4dee48b 4660 if (!link) {
fceef393 4661 link = inode->i_op->get_link(dentry, inode, &done);
d4dee48b
AV
4662 if (IS_ERR(link))
4663 return PTR_ERR(link);
4664 }
680baacb 4665 res = readlink_copy(buffer, buflen, link);
fceef393 4666 do_delayed_call(&done);
694a1764 4667 return res;
1da177e4 4668}
4d359507 4669EXPORT_SYMBOL(generic_readlink);
1da177e4 4670
d60874cd
MS
4671/**
4672 * vfs_get_link - get symlink body
4673 * @dentry: dentry on which to get symbolic link
4674 * @done: caller needs to free returned data with this
4675 *
4676 * Calls security hook and i_op->get_link() on the supplied inode.
4677 *
4678 * It does not touch atime. That's up to the caller if necessary.
4679 *
4680 * Does not work on "special" symlinks like /proc/$$/fd/N
4681 */
4682const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
4683{
4684 const char *res = ERR_PTR(-EINVAL);
4685 struct inode *inode = d_inode(dentry);
4686
4687 if (d_is_symlink(dentry)) {
4688 res = ERR_PTR(security_inode_readlink(dentry));
4689 if (!res)
4690 res = inode->i_op->get_link(dentry, inode, done);
4691 }
4692 return res;
4693}
4694EXPORT_SYMBOL(vfs_get_link);
4695
1da177e4 4696/* get the link contents into pagecache */
6b255391 4697const char *page_get_link(struct dentry *dentry, struct inode *inode,
fceef393 4698 struct delayed_call *callback)
1da177e4 4699{
ebd09abb
DG
4700 char *kaddr;
4701 struct page *page;
6b255391
AV
4702 struct address_space *mapping = inode->i_mapping;
4703
d3883d4f
AV
4704 if (!dentry) {
4705 page = find_get_page(mapping, 0);
4706 if (!page)
4707 return ERR_PTR(-ECHILD);
4708 if (!PageUptodate(page)) {
4709 put_page(page);
4710 return ERR_PTR(-ECHILD);
4711 }
4712 } else {
4713 page = read_mapping_page(mapping, 0, NULL);
4714 if (IS_ERR(page))
4715 return (char*)page;
4716 }
fceef393 4717 set_delayed_call(callback, page_put_link, page);
21fc61c7
AV
4718 BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM);
4719 kaddr = page_address(page);
6b255391 4720 nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1);
ebd09abb 4721 return kaddr;
1da177e4
LT
4722}
4723
6b255391 4724EXPORT_SYMBOL(page_get_link);
1da177e4 4725
fceef393 4726void page_put_link(void *arg)
1da177e4 4727{
fceef393 4728 put_page(arg);
1da177e4 4729}
4d359507 4730EXPORT_SYMBOL(page_put_link);
1da177e4 4731
aa80deab
AV
4732int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
4733{
fceef393 4734 DEFINE_DELAYED_CALL(done);
6b255391
AV
4735 int res = readlink_copy(buffer, buflen,
4736 page_get_link(dentry, d_inode(dentry),
fceef393
AV
4737 &done));
4738 do_delayed_call(&done);
aa80deab
AV
4739 return res;
4740}
4741EXPORT_SYMBOL(page_readlink);
4742
54566b2c
NP
4743/*
4744 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4745 */
4746int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
1da177e4
LT
4747{
4748 struct address_space *mapping = inode->i_mapping;
0adb25d2 4749 struct page *page;
afddba49 4750 void *fsdata;
beb497ab 4751 int err;
54566b2c
NP
4752 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
4753 if (nofs)
4754 flags |= AOP_FLAG_NOFS;
1da177e4 4755
7e53cac4 4756retry:
afddba49 4757 err = pagecache_write_begin(NULL, mapping, 0, len-1,
54566b2c 4758 flags, &page, &fsdata);
1da177e4 4759 if (err)
afddba49
NP
4760 goto fail;
4761
21fc61c7 4762 memcpy(page_address(page), symname, len-1);
afddba49
NP
4763
4764 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
4765 page, fsdata);
1da177e4
LT
4766 if (err < 0)
4767 goto fail;
afddba49
NP
4768 if (err < len-1)
4769 goto retry;
4770
1da177e4
LT
4771 mark_inode_dirty(inode);
4772 return 0;
1da177e4
LT
4773fail:
4774 return err;
4775}
4d359507 4776EXPORT_SYMBOL(__page_symlink);
1da177e4 4777
0adb25d2
KK
4778int page_symlink(struct inode *inode, const char *symname, int len)
4779{
4780 return __page_symlink(inode, symname, len,
c62d2555 4781 !mapping_gfp_constraint(inode->i_mapping, __GFP_FS));
0adb25d2 4782}
4d359507 4783EXPORT_SYMBOL(page_symlink);
0adb25d2 4784
92e1d5be 4785const struct inode_operations page_symlink_inode_operations = {
1da177e4 4786 .readlink = generic_readlink,
6b255391 4787 .get_link = page_get_link,
1da177e4 4788};
1da177e4 4789EXPORT_SYMBOL(page_symlink_inode_operations);