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Commit | Line | Data |
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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> |
ca6fe334 | 38 | #include <linux/init_task.h> |
1da177e4 LT |
39 | #include <asm/uaccess.h> |
40 | ||
e81e3f4d | 41 | #include "internal.h" |
c7105365 | 42 | #include "mount.h" |
e81e3f4d | 43 | |
1da177e4 LT |
44 | /* [Feb-1997 T. Schoebel-Theuer] |
45 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
46 | * were necessary because of omirr. The reason is that omirr needs | |
47 | * to know the _real_ pathname, not the user-supplied one, in case | |
48 | * of symlinks (and also when transname replacements occur). | |
49 | * | |
50 | * The new code replaces the old recursive symlink resolution with | |
51 | * an iterative one (in case of non-nested symlink chains). It does | |
52 | * this with calls to <fs>_follow_link(). | |
53 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
54 | * replaced with a single function lookup_dentry() that can handle all | |
55 | * the special cases of the former code. | |
56 | * | |
57 | * With the new dcache, the pathname is stored at each inode, at least as | |
58 | * long as the refcount of the inode is positive. As a side effect, the | |
59 | * size of the dcache depends on the inode cache and thus is dynamic. | |
60 | * | |
61 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
62 | * resolution to correspond with current state of the code. | |
63 | * | |
64 | * Note that the symlink resolution is not *completely* iterative. | |
65 | * There is still a significant amount of tail- and mid- recursion in | |
66 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
67 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
68 | * may return different results than <fs>_follow_link(). Many virtual | |
69 | * filesystems (including /proc) exhibit this behavior. | |
70 | */ | |
71 | ||
72 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
73 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
74 | * and the name already exists in form of a symlink, try to create the new | |
75 | * name indicated by the symlink. The old code always complained that the | |
76 | * name already exists, due to not following the symlink even if its target | |
77 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 78 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
79 | * |
80 | * I don't know which semantics is the right one, since I have no access | |
81 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
82 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
83 | * "old" one. Personally, I think the new semantics is much more logical. | |
84 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
85 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
86 | * and in the old Linux semantics. | |
87 | */ | |
88 | ||
89 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
90 | * semantics. See the comments in "open_namei" and "do_link" below. | |
91 | * | |
92 | * [10-Sep-98 Alan Modra] Another symlink change. | |
93 | */ | |
94 | ||
95 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
96 | * inside the path - always follow. | |
97 | * in the last component in creation/removal/renaming - never follow. | |
98 | * if LOOKUP_FOLLOW passed - follow. | |
99 | * if the pathname has trailing slashes - follow. | |
100 | * otherwise - don't follow. | |
101 | * (applied in that order). | |
102 | * | |
103 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
104 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
105 | * During the 2.4 we need to fix the userland stuff depending on it - | |
106 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
107 | * XEmacs seems to be relying on it... | |
108 | */ | |
109 | /* | |
110 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 111 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
112 | * any extra contention... |
113 | */ | |
114 | ||
115 | /* In order to reduce some races, while at the same time doing additional | |
116 | * checking and hopefully speeding things up, we copy filenames to the | |
117 | * kernel data space before using them.. | |
118 | * | |
119 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
120 | * PATH_MAX includes the nul terminator --RR. | |
121 | */ | |
91a27b2a | 122 | |
fd2f7cb5 | 123 | #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) |
7950e385 | 124 | |
51f39a1f | 125 | struct filename * |
91a27b2a JL |
126 | getname_flags(const char __user *filename, int flags, int *empty) |
127 | { | |
94b5d262 | 128 | struct filename *result; |
7950e385 | 129 | char *kname; |
94b5d262 | 130 | int len; |
4043cde8 | 131 | |
7ac86265 JL |
132 | result = audit_reusename(filename); |
133 | if (result) | |
134 | return result; | |
135 | ||
7950e385 | 136 | result = __getname(); |
3f9f0aa6 | 137 | if (unlikely(!result)) |
4043cde8 EP |
138 | return ERR_PTR(-ENOMEM); |
139 | ||
7950e385 JL |
140 | /* |
141 | * First, try to embed the struct filename inside the names_cache | |
142 | * allocation | |
143 | */ | |
fd2f7cb5 | 144 | kname = (char *)result->iname; |
91a27b2a | 145 | result->name = kname; |
7950e385 | 146 | |
94b5d262 | 147 | len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); |
91a27b2a | 148 | if (unlikely(len < 0)) { |
94b5d262 AV |
149 | __putname(result); |
150 | return ERR_PTR(len); | |
91a27b2a | 151 | } |
3f9f0aa6 | 152 | |
7950e385 JL |
153 | /* |
154 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
155 | * separate struct filename so we can dedicate the entire | |
156 | * names_cache allocation for the pathname, and re-do the copy from | |
157 | * userland. | |
158 | */ | |
94b5d262 | 159 | if (unlikely(len == EMBEDDED_NAME_MAX)) { |
fd2f7cb5 | 160 | const size_t size = offsetof(struct filename, iname[1]); |
7950e385 JL |
161 | kname = (char *)result; |
162 | ||
fd2f7cb5 AV |
163 | /* |
164 | * size is chosen that way we to guarantee that | |
165 | * result->iname[0] is within the same object and that | |
166 | * kname can't be equal to result->iname, no matter what. | |
167 | */ | |
168 | result = kzalloc(size, GFP_KERNEL); | |
94b5d262 AV |
169 | if (unlikely(!result)) { |
170 | __putname(kname); | |
171 | return ERR_PTR(-ENOMEM); | |
7950e385 JL |
172 | } |
173 | result->name = kname; | |
94b5d262 AV |
174 | len = strncpy_from_user(kname, filename, PATH_MAX); |
175 | if (unlikely(len < 0)) { | |
176 | __putname(kname); | |
177 | kfree(result); | |
178 | return ERR_PTR(len); | |
179 | } | |
180 | if (unlikely(len == PATH_MAX)) { | |
181 | __putname(kname); | |
182 | kfree(result); | |
183 | return ERR_PTR(-ENAMETOOLONG); | |
184 | } | |
7950e385 JL |
185 | } |
186 | ||
94b5d262 | 187 | result->refcnt = 1; |
3f9f0aa6 LT |
188 | /* The empty path is special. */ |
189 | if (unlikely(!len)) { | |
190 | if (empty) | |
4043cde8 | 191 | *empty = 1; |
94b5d262 AV |
192 | if (!(flags & LOOKUP_EMPTY)) { |
193 | putname(result); | |
194 | return ERR_PTR(-ENOENT); | |
195 | } | |
1da177e4 | 196 | } |
3f9f0aa6 | 197 | |
7950e385 | 198 | result->uptr = filename; |
c4ad8f98 | 199 | result->aname = NULL; |
7950e385 JL |
200 | audit_getname(result); |
201 | return result; | |
1da177e4 LT |
202 | } |
203 | ||
91a27b2a JL |
204 | struct filename * |
205 | getname(const char __user * filename) | |
f52e0c11 | 206 | { |
f7493e5d | 207 | return getname_flags(filename, 0, NULL); |
f52e0c11 AV |
208 | } |
209 | ||
c4ad8f98 LT |
210 | struct filename * |
211 | getname_kernel(const char * filename) | |
212 | { | |
213 | struct filename *result; | |
08518549 | 214 | int len = strlen(filename) + 1; |
c4ad8f98 LT |
215 | |
216 | result = __getname(); | |
217 | if (unlikely(!result)) | |
218 | return ERR_PTR(-ENOMEM); | |
219 | ||
08518549 | 220 | if (len <= EMBEDDED_NAME_MAX) { |
fd2f7cb5 | 221 | result->name = (char *)result->iname; |
08518549 PM |
222 | } else if (len <= PATH_MAX) { |
223 | struct filename *tmp; | |
224 | ||
225 | tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); | |
226 | if (unlikely(!tmp)) { | |
227 | __putname(result); | |
228 | return ERR_PTR(-ENOMEM); | |
229 | } | |
230 | tmp->name = (char *)result; | |
08518549 PM |
231 | result = tmp; |
232 | } else { | |
233 | __putname(result); | |
234 | return ERR_PTR(-ENAMETOOLONG); | |
235 | } | |
236 | memcpy((char *)result->name, filename, len); | |
c4ad8f98 LT |
237 | result->uptr = NULL; |
238 | result->aname = NULL; | |
55422d0b | 239 | result->refcnt = 1; |
fd3522fd | 240 | audit_getname(result); |
c4ad8f98 | 241 | |
c4ad8f98 LT |
242 | return result; |
243 | } | |
244 | ||
91a27b2a | 245 | void putname(struct filename *name) |
1da177e4 | 246 | { |
55422d0b PM |
247 | BUG_ON(name->refcnt <= 0); |
248 | ||
249 | if (--name->refcnt > 0) | |
250 | return; | |
251 | ||
fd2f7cb5 | 252 | if (name->name != name->iname) { |
55422d0b PM |
253 | __putname(name->name); |
254 | kfree(name); | |
255 | } else | |
256 | __putname(name); | |
1da177e4 | 257 | } |
1da177e4 | 258 | |
e77819e5 LT |
259 | static int check_acl(struct inode *inode, int mask) |
260 | { | |
84635d68 | 261 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
262 | struct posix_acl *acl; |
263 | ||
e77819e5 | 264 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
265 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
266 | if (!acl) | |
e77819e5 | 267 | return -EAGAIN; |
3567866b AV |
268 | /* no ->get_acl() calls in RCU mode... */ |
269 | if (acl == ACL_NOT_CACHED) | |
270 | return -ECHILD; | |
206b1d09 | 271 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
272 | } |
273 | ||
2982baa2 CH |
274 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
275 | if (IS_ERR(acl)) | |
276 | return PTR_ERR(acl); | |
e77819e5 LT |
277 | if (acl) { |
278 | int error = posix_acl_permission(inode, acl, mask); | |
279 | posix_acl_release(acl); | |
280 | return error; | |
281 | } | |
84635d68 | 282 | #endif |
e77819e5 LT |
283 | |
284 | return -EAGAIN; | |
285 | } | |
286 | ||
5909ccaa | 287 | /* |
948409c7 | 288 | * This does the basic permission checking |
1da177e4 | 289 | */ |
7e40145e | 290 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 291 | { |
26cf46be | 292 | unsigned int mode = inode->i_mode; |
1da177e4 | 293 | |
8e96e3b7 | 294 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
295 | mode >>= 6; |
296 | else { | |
e77819e5 | 297 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 298 | int error = check_acl(inode, mask); |
b74c79e9 NP |
299 | if (error != -EAGAIN) |
300 | return error; | |
1da177e4 LT |
301 | } |
302 | ||
303 | if (in_group_p(inode->i_gid)) | |
304 | mode >>= 3; | |
305 | } | |
306 | ||
307 | /* | |
308 | * If the DACs are ok we don't need any capability check. | |
309 | */ | |
9c2c7039 | 310 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 311 | return 0; |
5909ccaa LT |
312 | return -EACCES; |
313 | } | |
314 | ||
315 | /** | |
b74c79e9 | 316 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 317 | * @inode: inode to check access rights for |
8fd90c8d | 318 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
319 | * |
320 | * Used to check for read/write/execute permissions on a file. | |
321 | * We use "fsuid" for this, letting us set arbitrary permissions | |
322 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
323 | * are used for other things. |
324 | * | |
325 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
326 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
327 | * It would then be called again in ref-walk mode. | |
5909ccaa | 328 | */ |
2830ba7f | 329 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
330 | { |
331 | int ret; | |
332 | ||
333 | /* | |
948409c7 | 334 | * Do the basic permission checks. |
5909ccaa | 335 | */ |
7e40145e | 336 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
337 | if (ret != -EACCES) |
338 | return ret; | |
1da177e4 | 339 | |
d594e7ec AV |
340 | if (S_ISDIR(inode->i_mode)) { |
341 | /* DACs are overridable for directories */ | |
23adbe12 | 342 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
343 | return 0; |
344 | if (!(mask & MAY_WRITE)) | |
23adbe12 AL |
345 | if (capable_wrt_inode_uidgid(inode, |
346 | CAP_DAC_READ_SEARCH)) | |
d594e7ec AV |
347 | return 0; |
348 | return -EACCES; | |
349 | } | |
1da177e4 LT |
350 | /* |
351 | * Read/write DACs are always overridable. | |
d594e7ec AV |
352 | * Executable DACs are overridable when there is |
353 | * at least one exec bit set. | |
1da177e4 | 354 | */ |
d594e7ec | 355 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
23adbe12 | 356 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
357 | return 0; |
358 | ||
359 | /* | |
360 | * Searching includes executable on directories, else just read. | |
361 | */ | |
7ea66001 | 362 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 363 | if (mask == MAY_READ) |
23adbe12 | 364 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
365 | return 0; |
366 | ||
367 | return -EACCES; | |
368 | } | |
4d359507 | 369 | EXPORT_SYMBOL(generic_permission); |
1da177e4 | 370 | |
3ddcd056 LT |
371 | /* |
372 | * We _really_ want to just do "generic_permission()" without | |
373 | * even looking at the inode->i_op values. So we keep a cache | |
374 | * flag in inode->i_opflags, that says "this has not special | |
375 | * permission function, use the fast case". | |
376 | */ | |
377 | static inline int do_inode_permission(struct inode *inode, int mask) | |
378 | { | |
379 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
380 | if (likely(inode->i_op->permission)) | |
381 | return inode->i_op->permission(inode, mask); | |
382 | ||
383 | /* This gets set once for the inode lifetime */ | |
384 | spin_lock(&inode->i_lock); | |
385 | inode->i_opflags |= IOP_FASTPERM; | |
386 | spin_unlock(&inode->i_lock); | |
387 | } | |
388 | return generic_permission(inode, mask); | |
389 | } | |
390 | ||
cb23beb5 | 391 | /** |
0bdaea90 DH |
392 | * __inode_permission - Check for access rights to a given inode |
393 | * @inode: Inode to check permission on | |
394 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 395 | * |
0bdaea90 | 396 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
397 | * |
398 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
399 | * |
400 | * This does not check for a read-only file system. You probably want | |
401 | * inode_permission(). | |
cb23beb5 | 402 | */ |
0bdaea90 | 403 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 404 | { |
e6305c43 | 405 | int retval; |
1da177e4 | 406 | |
3ddcd056 | 407 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
408 | /* |
409 | * Nobody gets write access to an immutable file. | |
410 | */ | |
411 | if (IS_IMMUTABLE(inode)) | |
412 | return -EACCES; | |
be494dcc EB |
413 | |
414 | /* | |
415 | * Updating mtime will likely cause i_uid and i_gid to be | |
416 | * written back improperly if their true value is unknown | |
417 | * to the vfs. | |
418 | */ | |
419 | if (HAS_UNMAPPED_ID(inode)) | |
420 | return -EACCES; | |
1da177e4 LT |
421 | } |
422 | ||
3ddcd056 | 423 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
424 | if (retval) |
425 | return retval; | |
426 | ||
08ce5f16 SH |
427 | retval = devcgroup_inode_permission(inode, mask); |
428 | if (retval) | |
429 | return retval; | |
430 | ||
d09ca739 | 431 | return security_inode_permission(inode, mask); |
1da177e4 | 432 | } |
bd5d0856 | 433 | EXPORT_SYMBOL(__inode_permission); |
1da177e4 | 434 | |
0bdaea90 DH |
435 | /** |
436 | * sb_permission - Check superblock-level permissions | |
437 | * @sb: Superblock of inode to check permission on | |
55852635 | 438 | * @inode: Inode to check permission on |
0bdaea90 DH |
439 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
440 | * | |
441 | * Separate out file-system wide checks from inode-specific permission checks. | |
442 | */ | |
443 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
444 | { | |
445 | if (unlikely(mask & MAY_WRITE)) { | |
446 | umode_t mode = inode->i_mode; | |
447 | ||
448 | /* Nobody gets write access to a read-only fs. */ | |
449 | if ((sb->s_flags & MS_RDONLY) && | |
450 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
451 | return -EROFS; | |
452 | } | |
453 | return 0; | |
454 | } | |
455 | ||
456 | /** | |
457 | * inode_permission - Check for access rights to a given inode | |
458 | * @inode: Inode to check permission on | |
459 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
460 | * | |
461 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
462 | * this, letting us set arbitrary permissions for filesystem access without | |
463 | * changing the "normal" UIDs which are used for other things. | |
464 | * | |
465 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
466 | */ | |
467 | int inode_permission(struct inode *inode, int mask) | |
468 | { | |
469 | int retval; | |
470 | ||
471 | retval = sb_permission(inode->i_sb, inode, mask); | |
472 | if (retval) | |
473 | return retval; | |
474 | return __inode_permission(inode, mask); | |
475 | } | |
4d359507 | 476 | EXPORT_SYMBOL(inode_permission); |
0bdaea90 | 477 | |
5dd784d0 JB |
478 | /** |
479 | * path_get - get a reference to a path | |
480 | * @path: path to get the reference to | |
481 | * | |
482 | * Given a path increment the reference count to the dentry and the vfsmount. | |
483 | */ | |
dcf787f3 | 484 | void path_get(const struct path *path) |
5dd784d0 JB |
485 | { |
486 | mntget(path->mnt); | |
487 | dget(path->dentry); | |
488 | } | |
489 | EXPORT_SYMBOL(path_get); | |
490 | ||
1d957f9b JB |
491 | /** |
492 | * path_put - put a reference to a path | |
493 | * @path: path to put the reference to | |
494 | * | |
495 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
496 | */ | |
dcf787f3 | 497 | void path_put(const struct path *path) |
1da177e4 | 498 | { |
1d957f9b JB |
499 | dput(path->dentry); |
500 | mntput(path->mnt); | |
1da177e4 | 501 | } |
1d957f9b | 502 | EXPORT_SYMBOL(path_put); |
1da177e4 | 503 | |
894bc8c4 | 504 | #define EMBEDDED_LEVELS 2 |
1f55a6ec AV |
505 | struct nameidata { |
506 | struct path path; | |
1cf2665b | 507 | struct qstr last; |
1f55a6ec AV |
508 | struct path root; |
509 | struct inode *inode; /* path.dentry.d_inode */ | |
510 | unsigned int flags; | |
9883d185 | 511 | unsigned seq, m_seq; |
1f55a6ec AV |
512 | int last_type; |
513 | unsigned depth; | |
756daf26 | 514 | int total_link_count; |
697fc6ca AV |
515 | struct saved { |
516 | struct path link; | |
517 | void *cookie; | |
518 | const char *name; | |
237d8b32 | 519 | struct inode *inode; |
0450b2d1 | 520 | unsigned seq; |
894bc8c4 | 521 | } *stack, internal[EMBEDDED_LEVELS]; |
9883d185 AV |
522 | struct filename *name; |
523 | struct nameidata *saved; | |
524 | unsigned root_seq; | |
525 | int dfd; | |
1f55a6ec AV |
526 | }; |
527 | ||
9883d185 | 528 | static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) |
894bc8c4 | 529 | { |
756daf26 N |
530 | struct nameidata *old = current->nameidata; |
531 | p->stack = p->internal; | |
c8a53ee5 AV |
532 | p->dfd = dfd; |
533 | p->name = name; | |
756daf26 | 534 | p->total_link_count = old ? old->total_link_count : 0; |
9883d185 | 535 | p->saved = old; |
756daf26 | 536 | current->nameidata = p; |
894bc8c4 AV |
537 | } |
538 | ||
9883d185 | 539 | static void restore_nameidata(void) |
894bc8c4 | 540 | { |
9883d185 | 541 | struct nameidata *now = current->nameidata, *old = now->saved; |
756daf26 N |
542 | |
543 | current->nameidata = old; | |
544 | if (old) | |
545 | old->total_link_count = now->total_link_count; | |
546 | if (now->stack != now->internal) { | |
547 | kfree(now->stack); | |
548 | now->stack = now->internal; | |
894bc8c4 AV |
549 | } |
550 | } | |
551 | ||
552 | static int __nd_alloc_stack(struct nameidata *nd) | |
553 | { | |
bc40aee0 AV |
554 | struct saved *p; |
555 | ||
556 | if (nd->flags & LOOKUP_RCU) { | |
557 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
558 | GFP_ATOMIC); | |
559 | if (unlikely(!p)) | |
560 | return -ECHILD; | |
561 | } else { | |
562 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
894bc8c4 | 563 | GFP_KERNEL); |
bc40aee0 AV |
564 | if (unlikely(!p)) |
565 | return -ENOMEM; | |
566 | } | |
894bc8c4 AV |
567 | memcpy(p, nd->internal, sizeof(nd->internal)); |
568 | nd->stack = p; | |
569 | return 0; | |
570 | } | |
571 | ||
397d425d EB |
572 | /** |
573 | * path_connected - Verify that a path->dentry is below path->mnt.mnt_root | |
574 | * @path: nameidate to verify | |
575 | * | |
576 | * Rename can sometimes move a file or directory outside of a bind | |
577 | * mount, path_connected allows those cases to be detected. | |
578 | */ | |
579 | static bool path_connected(const struct path *path) | |
580 | { | |
581 | struct vfsmount *mnt = path->mnt; | |
582 | ||
583 | /* Only bind mounts can have disconnected paths */ | |
584 | if (mnt->mnt_root == mnt->mnt_sb->s_root) | |
585 | return true; | |
586 | ||
587 | return is_subdir(path->dentry, mnt->mnt_root); | |
588 | } | |
589 | ||
894bc8c4 AV |
590 | static inline int nd_alloc_stack(struct nameidata *nd) |
591 | { | |
da4e0be0 | 592 | if (likely(nd->depth != EMBEDDED_LEVELS)) |
894bc8c4 AV |
593 | return 0; |
594 | if (likely(nd->stack != nd->internal)) | |
595 | return 0; | |
596 | return __nd_alloc_stack(nd); | |
597 | } | |
598 | ||
7973387a AV |
599 | static void drop_links(struct nameidata *nd) |
600 | { | |
601 | int i = nd->depth; | |
602 | while (i--) { | |
603 | struct saved *last = nd->stack + i; | |
604 | struct inode *inode = last->inode; | |
605 | if (last->cookie && inode->i_op->put_link) { | |
606 | inode->i_op->put_link(inode, last->cookie); | |
607 | last->cookie = NULL; | |
608 | } | |
609 | } | |
610 | } | |
611 | ||
612 | static void terminate_walk(struct nameidata *nd) | |
613 | { | |
614 | drop_links(nd); | |
615 | if (!(nd->flags & LOOKUP_RCU)) { | |
616 | int i; | |
617 | path_put(&nd->path); | |
618 | for (i = 0; i < nd->depth; i++) | |
619 | path_put(&nd->stack[i].link); | |
102b8af2 AV |
620 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
621 | path_put(&nd->root); | |
622 | nd->root.mnt = NULL; | |
623 | } | |
7973387a AV |
624 | } else { |
625 | nd->flags &= ~LOOKUP_RCU; | |
626 | if (!(nd->flags & LOOKUP_ROOT)) | |
627 | nd->root.mnt = NULL; | |
628 | rcu_read_unlock(); | |
629 | } | |
630 | nd->depth = 0; | |
631 | } | |
632 | ||
633 | /* path_put is needed afterwards regardless of success or failure */ | |
634 | static bool legitimize_path(struct nameidata *nd, | |
635 | struct path *path, unsigned seq) | |
636 | { | |
637 | int res = __legitimize_mnt(path->mnt, nd->m_seq); | |
638 | if (unlikely(res)) { | |
639 | if (res > 0) | |
640 | path->mnt = NULL; | |
641 | path->dentry = NULL; | |
642 | return false; | |
643 | } | |
644 | if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { | |
645 | path->dentry = NULL; | |
646 | return false; | |
647 | } | |
648 | return !read_seqcount_retry(&path->dentry->d_seq, seq); | |
649 | } | |
650 | ||
651 | static bool legitimize_links(struct nameidata *nd) | |
652 | { | |
653 | int i; | |
654 | for (i = 0; i < nd->depth; i++) { | |
655 | struct saved *last = nd->stack + i; | |
656 | if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { | |
657 | drop_links(nd); | |
658 | nd->depth = i + 1; | |
659 | return false; | |
660 | } | |
661 | } | |
662 | return true; | |
663 | } | |
664 | ||
19660af7 | 665 | /* |
31e6b01f | 666 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
667 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
668 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
669 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
670 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
671 | * got stuck, so ref-walk may continue from there. If this is not successful | |
672 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
673 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 674 | */ |
31e6b01f NP |
675 | |
676 | /** | |
19660af7 AV |
677 | * unlazy_walk - try to switch to ref-walk mode. |
678 | * @nd: nameidata pathwalk data | |
679 | * @dentry: child of nd->path.dentry or NULL | |
6e9918b7 | 680 | * @seq: seq number to check dentry against |
39191628 | 681 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 682 | * |
19660af7 AV |
683 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
684 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
685 | * @nd or NULL. Must be called from rcu-walk context. | |
7973387a AV |
686 | * Nothing should touch nameidata between unlazy_walk() failure and |
687 | * terminate_walk(). | |
31e6b01f | 688 | */ |
6e9918b7 | 689 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) |
31e6b01f | 690 | { |
31e6b01f NP |
691 | struct dentry *parent = nd->path.dentry; |
692 | ||
693 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 | 694 | |
e5c832d5 | 695 | nd->flags &= ~LOOKUP_RCU; |
7973387a AV |
696 | if (unlikely(!legitimize_links(nd))) |
697 | goto out2; | |
698 | if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) | |
699 | goto out2; | |
700 | if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) | |
701 | goto out1; | |
48a066e7 | 702 | |
15570086 LT |
703 | /* |
704 | * For a negative lookup, the lookup sequence point is the parents | |
705 | * sequence point, and it only needs to revalidate the parent dentry. | |
706 | * | |
707 | * For a positive lookup, we need to move both the parent and the | |
708 | * dentry from the RCU domain to be properly refcounted. And the | |
709 | * sequence number in the dentry validates *both* dentry counters, | |
710 | * since we checked the sequence number of the parent after we got | |
711 | * the child sequence number. So we know the parent must still | |
712 | * be valid if the child sequence number is still valid. | |
713 | */ | |
19660af7 | 714 | if (!dentry) { |
e5c832d5 LT |
715 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
716 | goto out; | |
19660af7 AV |
717 | BUG_ON(nd->inode != parent->d_inode); |
718 | } else { | |
e5c832d5 LT |
719 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
720 | goto out; | |
6e9918b7 | 721 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
e5c832d5 | 722 | goto drop_dentry; |
19660af7 | 723 | } |
e5c832d5 LT |
724 | |
725 | /* | |
726 | * Sequence counts matched. Now make sure that the root is | |
727 | * still valid and get it if required. | |
728 | */ | |
729 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
5a8d87e8 AV |
730 | if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { |
731 | rcu_read_unlock(); | |
732 | dput(dentry); | |
733 | return -ECHILD; | |
7973387a | 734 | } |
31e6b01f | 735 | } |
31e6b01f | 736 | |
8b61e74f | 737 | rcu_read_unlock(); |
31e6b01f | 738 | return 0; |
19660af7 | 739 | |
e5c832d5 | 740 | drop_dentry: |
8b61e74f | 741 | rcu_read_unlock(); |
15570086 | 742 | dput(dentry); |
d0d27277 | 743 | goto drop_root_mnt; |
7973387a AV |
744 | out2: |
745 | nd->path.mnt = NULL; | |
746 | out1: | |
747 | nd->path.dentry = NULL; | |
e5c832d5 | 748 | out: |
8b61e74f | 749 | rcu_read_unlock(); |
d0d27277 LT |
750 | drop_root_mnt: |
751 | if (!(nd->flags & LOOKUP_ROOT)) | |
752 | nd->root.mnt = NULL; | |
31e6b01f NP |
753 | return -ECHILD; |
754 | } | |
755 | ||
7973387a AV |
756 | static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) |
757 | { | |
758 | if (unlikely(!legitimize_path(nd, link, seq))) { | |
759 | drop_links(nd); | |
760 | nd->depth = 0; | |
761 | nd->flags &= ~LOOKUP_RCU; | |
762 | nd->path.mnt = NULL; | |
763 | nd->path.dentry = NULL; | |
764 | if (!(nd->flags & LOOKUP_ROOT)) | |
765 | nd->root.mnt = NULL; | |
766 | rcu_read_unlock(); | |
767 | } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { | |
768 | return 0; | |
769 | } | |
770 | path_put(link); | |
771 | return -ECHILD; | |
772 | } | |
773 | ||
4ce16ef3 | 774 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 775 | { |
4ce16ef3 | 776 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
777 | } |
778 | ||
9f1fafee AV |
779 | /** |
780 | * complete_walk - successful completion of path walk | |
781 | * @nd: pointer nameidata | |
39159de2 | 782 | * |
9f1fafee AV |
783 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
784 | * Revalidate the final result, unless we'd already done that during | |
785 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
786 | * success, -error on failure. In case of failure caller does not | |
787 | * need to drop nd->path. | |
39159de2 | 788 | */ |
9f1fafee | 789 | static int complete_walk(struct nameidata *nd) |
39159de2 | 790 | { |
16c2cd71 | 791 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 792 | int status; |
39159de2 | 793 | |
9f1fafee | 794 | if (nd->flags & LOOKUP_RCU) { |
9f1fafee AV |
795 | if (!(nd->flags & LOOKUP_ROOT)) |
796 | nd->root.mnt = NULL; | |
6e9918b7 | 797 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
9f1fafee | 798 | return -ECHILD; |
9f1fafee AV |
799 | } |
800 | ||
16c2cd71 AV |
801 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
802 | return 0; | |
803 | ||
ecf3d1f1 | 804 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
805 | return 0; |
806 | ||
ecf3d1f1 | 807 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
808 | if (status > 0) |
809 | return 0; | |
810 | ||
16c2cd71 | 811 | if (!status) |
39159de2 | 812 | status = -ESTALE; |
16c2cd71 | 813 | |
39159de2 JL |
814 | return status; |
815 | } | |
816 | ||
18d8c860 | 817 | static void set_root(struct nameidata *nd) |
2a737871 | 818 | { |
7bd88377 | 819 | get_fs_root(current->fs, &nd->root); |
2a737871 AV |
820 | } |
821 | ||
06d7137e | 822 | static void set_root_rcu(struct nameidata *nd) |
31e6b01f | 823 | { |
7bd88377 | 824 | struct fs_struct *fs = current->fs; |
8f47a016 | 825 | unsigned seq; |
c28cc364 | 826 | |
7bd88377 AV |
827 | do { |
828 | seq = read_seqcount_begin(&fs->seq); | |
829 | nd->root = fs->root; | |
8f47a016 | 830 | nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
7bd88377 | 831 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
832 | } |
833 | ||
1d957f9b | 834 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
835 | { |
836 | dput(path->dentry); | |
4ac91378 | 837 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
838 | mntput(path->mnt); |
839 | } | |
840 | ||
7b9337aa NP |
841 | static inline void path_to_nameidata(const struct path *path, |
842 | struct nameidata *nd) | |
051d3812 | 843 | { |
31e6b01f NP |
844 | if (!(nd->flags & LOOKUP_RCU)) { |
845 | dput(nd->path.dentry); | |
846 | if (nd->path.mnt != path->mnt) | |
847 | mntput(nd->path.mnt); | |
9a229683 | 848 | } |
31e6b01f | 849 | nd->path.mnt = path->mnt; |
4ac91378 | 850 | nd->path.dentry = path->dentry; |
051d3812 IK |
851 | } |
852 | ||
b5fb63c1 CH |
853 | /* |
854 | * Helper to directly jump to a known parsed path from ->follow_link, | |
855 | * caller must have taken a reference to path beforehand. | |
856 | */ | |
6e77137b | 857 | void nd_jump_link(struct path *path) |
b5fb63c1 | 858 | { |
6e77137b | 859 | struct nameidata *nd = current->nameidata; |
b5fb63c1 CH |
860 | path_put(&nd->path); |
861 | ||
862 | nd->path = *path; | |
863 | nd->inode = nd->path.dentry->d_inode; | |
864 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
865 | } |
866 | ||
b9ff4429 | 867 | static inline void put_link(struct nameidata *nd) |
574197e0 | 868 | { |
21c3003d | 869 | struct saved *last = nd->stack + --nd->depth; |
237d8b32 | 870 | struct inode *inode = last->inode; |
b9ff4429 | 871 | if (last->cookie && inode->i_op->put_link) |
5f2c4179 | 872 | inode->i_op->put_link(inode, last->cookie); |
6548fae2 AV |
873 | if (!(nd->flags & LOOKUP_RCU)) |
874 | path_put(&last->link); | |
574197e0 AV |
875 | } |
876 | ||
c331eb40 TG |
877 | int sysctl_protected_symlinks __read_mostly = 1; |
878 | int sysctl_protected_hardlinks __read_mostly = 1; | |
800179c9 KC |
879 | |
880 | /** | |
881 | * may_follow_link - Check symlink following for unsafe situations | |
55852635 | 882 | * @nd: nameidata pathwalk data |
800179c9 KC |
883 | * |
884 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
885 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
886 | * in a sticky world-writable directory. This is to protect privileged | |
887 | * processes from failing races against path names that may change out | |
888 | * from under them by way of other users creating malicious symlinks. | |
889 | * It will permit symlinks to be followed only when outside a sticky | |
890 | * world-writable directory, or when the uid of the symlink and follower | |
891 | * match, or when the directory owner matches the symlink's owner. | |
892 | * | |
893 | * Returns 0 if following the symlink is allowed, -ve on error. | |
894 | */ | |
fec2fa24 | 895 | static inline int may_follow_link(struct nameidata *nd) |
800179c9 KC |
896 | { |
897 | const struct inode *inode; | |
898 | const struct inode *parent; | |
d76b9a2e | 899 | kuid_t puid; |
800179c9 KC |
900 | |
901 | if (!sysctl_protected_symlinks) | |
902 | return 0; | |
903 | ||
904 | /* Allowed if owner and follower match. */ | |
237d8b32 | 905 | inode = nd->stack[0].inode; |
81abe27b | 906 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
907 | return 0; |
908 | ||
909 | /* Allowed if parent directory not sticky and world-writable. */ | |
aa65fa35 | 910 | parent = nd->inode; |
800179c9 KC |
911 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) |
912 | return 0; | |
913 | ||
914 | /* Allowed if parent directory and link owner match. */ | |
d76b9a2e SF |
915 | puid = parent->i_uid; |
916 | if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) | |
800179c9 KC |
917 | return 0; |
918 | ||
31956502 AV |
919 | if (nd->flags & LOOKUP_RCU) |
920 | return -ECHILD; | |
921 | ||
1cf2665b | 922 | audit_log_link_denied("follow_link", &nd->stack[0].link); |
800179c9 KC |
923 | return -EACCES; |
924 | } | |
925 | ||
926 | /** | |
927 | * safe_hardlink_source - Check for safe hardlink conditions | |
928 | * @inode: the source inode to hardlink from | |
929 | * | |
930 | * Return false if at least one of the following conditions: | |
931 | * - inode is not a regular file | |
932 | * - inode is setuid | |
933 | * - inode is setgid and group-exec | |
934 | * - access failure for read and write | |
935 | * | |
936 | * Otherwise returns true. | |
937 | */ | |
938 | static bool safe_hardlink_source(struct inode *inode) | |
939 | { | |
940 | umode_t mode = inode->i_mode; | |
941 | ||
942 | /* Special files should not get pinned to the filesystem. */ | |
943 | if (!S_ISREG(mode)) | |
944 | return false; | |
945 | ||
946 | /* Setuid files should not get pinned to the filesystem. */ | |
947 | if (mode & S_ISUID) | |
948 | return false; | |
949 | ||
950 | /* Executable setgid files should not get pinned to the filesystem. */ | |
951 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
952 | return false; | |
953 | ||
954 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
955 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
956 | return false; | |
957 | ||
958 | return true; | |
959 | } | |
960 | ||
961 | /** | |
962 | * may_linkat - Check permissions for creating a hardlink | |
963 | * @link: the source to hardlink from | |
964 | * | |
965 | * Block hardlink when all of: | |
966 | * - sysctl_protected_hardlinks enabled | |
967 | * - fsuid does not match inode | |
968 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
f2ca3796 | 969 | * - not CAP_FOWNER in a namespace with the inode owner uid mapped |
800179c9 KC |
970 | * |
971 | * Returns 0 if successful, -ve on error. | |
972 | */ | |
973 | static int may_linkat(struct path *link) | |
974 | { | |
800179c9 KC |
975 | struct inode *inode; |
976 | ||
977 | if (!sysctl_protected_hardlinks) | |
978 | return 0; | |
979 | ||
800179c9 KC |
980 | inode = link->dentry->d_inode; |
981 | ||
982 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
983 | * otherwise, it must be a safe source. | |
984 | */ | |
f2ca3796 | 985 | if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) |
800179c9 KC |
986 | return 0; |
987 | ||
a51d9eaa | 988 | audit_log_link_denied("linkat", link); |
800179c9 KC |
989 | return -EPERM; |
990 | } | |
991 | ||
3b2e7f75 AV |
992 | static __always_inline |
993 | const char *get_link(struct nameidata *nd) | |
1da177e4 | 994 | { |
ab104923 | 995 | struct saved *last = nd->stack + nd->depth - 1; |
1cf2665b | 996 | struct dentry *dentry = last->link.dentry; |
237d8b32 | 997 | struct inode *inode = last->inode; |
6d7b5aae | 998 | int error; |
0a959df5 | 999 | const char *res; |
1da177e4 | 1000 | |
8fa9dd24 N |
1001 | if (!(nd->flags & LOOKUP_RCU)) { |
1002 | touch_atime(&last->link); | |
1003 | cond_resched(); | |
1004 | } else if (atime_needs_update(&last->link, inode)) { | |
bc40aee0 AV |
1005 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
1006 | return ERR_PTR(-ECHILD); | |
8fa9dd24 | 1007 | touch_atime(&last->link); |
bc40aee0 | 1008 | } |
574197e0 | 1009 | |
bda0be7a N |
1010 | error = security_inode_follow_link(dentry, inode, |
1011 | nd->flags & LOOKUP_RCU); | |
1012 | if (unlikely(error)) | |
6920a440 | 1013 | return ERR_PTR(error); |
36f3b4f6 | 1014 | |
86acdca1 | 1015 | nd->last_type = LAST_BIND; |
d4dee48b AV |
1016 | res = inode->i_link; |
1017 | if (!res) { | |
8c1b4566 AV |
1018 | if (nd->flags & LOOKUP_RCU) { |
1019 | if (unlikely(unlazy_walk(nd, NULL, 0))) | |
1020 | return ERR_PTR(-ECHILD); | |
1021 | } | |
6e77137b | 1022 | res = inode->i_op->follow_link(dentry, &last->cookie); |
fab51e8a | 1023 | if (IS_ERR_OR_NULL(res)) { |
6920a440 | 1024 | last->cookie = NULL; |
fab51e8a AV |
1025 | return res; |
1026 | } | |
1027 | } | |
1028 | if (*res == '/') { | |
8c1b4566 | 1029 | if (nd->flags & LOOKUP_RCU) { |
8f47a016 AV |
1030 | struct dentry *d; |
1031 | if (!nd->root.mnt) | |
1032 | set_root_rcu(nd); | |
1033 | nd->path = nd->root; | |
1034 | d = nd->path.dentry; | |
1035 | nd->inode = d->d_inode; | |
1036 | nd->seq = nd->root_seq; | |
1037 | if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) | |
8c1b4566 | 1038 | return ERR_PTR(-ECHILD); |
8f47a016 AV |
1039 | } else { |
1040 | if (!nd->root.mnt) | |
1041 | set_root(nd); | |
1042 | path_put(&nd->path); | |
1043 | nd->path = nd->root; | |
1044 | path_get(&nd->root); | |
1045 | nd->inode = nd->path.dentry->d_inode; | |
8c1b4566 | 1046 | } |
fab51e8a AV |
1047 | nd->flags |= LOOKUP_JUMPED; |
1048 | while (unlikely(*++res == '/')) | |
1049 | ; | |
1da177e4 | 1050 | } |
fab51e8a AV |
1051 | if (!*res) |
1052 | res = NULL; | |
0a959df5 AV |
1053 | return res; |
1054 | } | |
6d7b5aae | 1055 | |
f015f126 DH |
1056 | /* |
1057 | * follow_up - Find the mountpoint of path's vfsmount | |
1058 | * | |
1059 | * Given a path, find the mountpoint of its source file system. | |
1060 | * Replace @path with the path of the mountpoint in the parent mount. | |
1061 | * Up is towards /. | |
1062 | * | |
1063 | * Return 1 if we went up a level and 0 if we were already at the | |
1064 | * root. | |
1065 | */ | |
bab77ebf | 1066 | int follow_up(struct path *path) |
1da177e4 | 1067 | { |
0714a533 AV |
1068 | struct mount *mnt = real_mount(path->mnt); |
1069 | struct mount *parent; | |
1da177e4 | 1070 | struct dentry *mountpoint; |
99b7db7b | 1071 | |
48a066e7 | 1072 | read_seqlock_excl(&mount_lock); |
0714a533 | 1073 | parent = mnt->mnt_parent; |
3c0a6163 | 1074 | if (parent == mnt) { |
48a066e7 | 1075 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
1076 | return 0; |
1077 | } | |
0714a533 | 1078 | mntget(&parent->mnt); |
a73324da | 1079 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 1080 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
1081 | dput(path->dentry); |
1082 | path->dentry = mountpoint; | |
1083 | mntput(path->mnt); | |
0714a533 | 1084 | path->mnt = &parent->mnt; |
1da177e4 LT |
1085 | return 1; |
1086 | } | |
4d359507 | 1087 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 1088 | |
b5c84bf6 | 1089 | /* |
9875cf80 DH |
1090 | * Perform an automount |
1091 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
1092 | * were called with. | |
1da177e4 | 1093 | */ |
756daf26 | 1094 | static int follow_automount(struct path *path, struct nameidata *nd, |
9875cf80 | 1095 | bool *need_mntput) |
31e6b01f | 1096 | { |
9875cf80 | 1097 | struct vfsmount *mnt; |
ea5b778a | 1098 | int err; |
9875cf80 DH |
1099 | |
1100 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
1101 | return -EREMOTE; | |
1102 | ||
0ec26fd0 MS |
1103 | /* We don't want to mount if someone's just doing a stat - |
1104 | * unless they're stat'ing a directory and appended a '/' to | |
1105 | * the name. | |
1106 | * | |
1107 | * We do, however, want to mount if someone wants to open or | |
1108 | * create a file of any type under the mountpoint, wants to | |
1109 | * traverse through the mountpoint or wants to open the | |
1110 | * mounted directory. Also, autofs may mark negative dentries | |
1111 | * as being automount points. These will need the attentions | |
1112 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 1113 | */ |
756daf26 N |
1114 | if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
1115 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && | |
0ec26fd0 MS |
1116 | path->dentry->d_inode) |
1117 | return -EISDIR; | |
1118 | ||
ca6fe334 EB |
1119 | if (path->dentry->d_sb->s_user_ns != &init_user_ns) |
1120 | return -EACCES; | |
1121 | ||
756daf26 N |
1122 | nd->total_link_count++; |
1123 | if (nd->total_link_count >= 40) | |
9875cf80 DH |
1124 | return -ELOOP; |
1125 | ||
1126 | mnt = path->dentry->d_op->d_automount(path); | |
1127 | if (IS_ERR(mnt)) { | |
1128 | /* | |
1129 | * The filesystem is allowed to return -EISDIR here to indicate | |
1130 | * it doesn't want to automount. For instance, autofs would do | |
1131 | * this so that its userspace daemon can mount on this dentry. | |
1132 | * | |
1133 | * However, we can only permit this if it's a terminal point in | |
1134 | * the path being looked up; if it wasn't then the remainder of | |
1135 | * the path is inaccessible and we should say so. | |
1136 | */ | |
756daf26 | 1137 | if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) |
9875cf80 DH |
1138 | return -EREMOTE; |
1139 | return PTR_ERR(mnt); | |
31e6b01f | 1140 | } |
ea5b778a | 1141 | |
9875cf80 DH |
1142 | if (!mnt) /* mount collision */ |
1143 | return 0; | |
31e6b01f | 1144 | |
8aef1884 AV |
1145 | if (!*need_mntput) { |
1146 | /* lock_mount() may release path->mnt on error */ | |
1147 | mntget(path->mnt); | |
1148 | *need_mntput = true; | |
1149 | } | |
19a167af | 1150 | err = finish_automount(mnt, path); |
9875cf80 | 1151 | |
ea5b778a DH |
1152 | switch (err) { |
1153 | case -EBUSY: | |
1154 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 1155 | return 0; |
ea5b778a | 1156 | case 0: |
8aef1884 | 1157 | path_put(path); |
ea5b778a DH |
1158 | path->mnt = mnt; |
1159 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1160 | return 0; |
19a167af AV |
1161 | default: |
1162 | return err; | |
ea5b778a | 1163 | } |
19a167af | 1164 | |
463ffb2e AV |
1165 | } |
1166 | ||
9875cf80 DH |
1167 | /* |
1168 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1169 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1170 | * - Flagged as mountpoint |
1171 | * - Flagged as automount point | |
1172 | * | |
1173 | * This may only be called in refwalk mode. | |
1174 | * | |
1175 | * Serialization is taken care of in namespace.c | |
1176 | */ | |
756daf26 | 1177 | static int follow_managed(struct path *path, struct nameidata *nd) |
1da177e4 | 1178 | { |
8aef1884 | 1179 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1180 | unsigned managed; |
1181 | bool need_mntput = false; | |
8aef1884 | 1182 | int ret = 0; |
9875cf80 DH |
1183 | |
1184 | /* Given that we're not holding a lock here, we retain the value in a | |
1185 | * local variable for each dentry as we look at it so that we don't see | |
1186 | * the components of that value change under us */ | |
1187 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1188 | managed &= DCACHE_MANAGED_DENTRY, | |
1189 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1190 | /* Allow the filesystem to manage the transit without i_mutex |
1191 | * being held. */ | |
1192 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1193 | BUG_ON(!path->dentry->d_op); | |
1194 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1195 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1196 | if (ret < 0) |
8aef1884 | 1197 | break; |
cc53ce53 DH |
1198 | } |
1199 | ||
9875cf80 DH |
1200 | /* Transit to a mounted filesystem. */ |
1201 | if (managed & DCACHE_MOUNTED) { | |
1202 | struct vfsmount *mounted = lookup_mnt(path); | |
1203 | if (mounted) { | |
1204 | dput(path->dentry); | |
1205 | if (need_mntput) | |
1206 | mntput(path->mnt); | |
1207 | path->mnt = mounted; | |
1208 | path->dentry = dget(mounted->mnt_root); | |
1209 | need_mntput = true; | |
1210 | continue; | |
1211 | } | |
1212 | ||
1213 | /* Something is mounted on this dentry in another | |
1214 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1215 | * namespace got unmounted before lookup_mnt() could |
1216 | * get it */ | |
9875cf80 DH |
1217 | } |
1218 | ||
1219 | /* Handle an automount point */ | |
1220 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
756daf26 | 1221 | ret = follow_automount(path, nd, &need_mntput); |
9875cf80 | 1222 | if (ret < 0) |
8aef1884 | 1223 | break; |
9875cf80 DH |
1224 | continue; |
1225 | } | |
1226 | ||
1227 | /* We didn't change the current path point */ | |
1228 | break; | |
1da177e4 | 1229 | } |
8aef1884 AV |
1230 | |
1231 | if (need_mntput && path->mnt == mnt) | |
1232 | mntput(path->mnt); | |
1233 | if (ret == -EISDIR) | |
1234 | ret = 0; | |
8402752e AV |
1235 | if (need_mntput) |
1236 | nd->flags |= LOOKUP_JUMPED; | |
1237 | if (unlikely(ret < 0)) | |
1238 | path_put_conditional(path, nd); | |
1239 | return ret; | |
1da177e4 LT |
1240 | } |
1241 | ||
cc53ce53 | 1242 | int follow_down_one(struct path *path) |
1da177e4 LT |
1243 | { |
1244 | struct vfsmount *mounted; | |
1245 | ||
1c755af4 | 1246 | mounted = lookup_mnt(path); |
1da177e4 | 1247 | if (mounted) { |
9393bd07 AV |
1248 | dput(path->dentry); |
1249 | mntput(path->mnt); | |
1250 | path->mnt = mounted; | |
1251 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1252 | return 1; |
1253 | } | |
1254 | return 0; | |
1255 | } | |
4d359507 | 1256 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1257 | |
b8faf035 | 1258 | static inline int managed_dentry_rcu(struct dentry *dentry) |
62a7375e | 1259 | { |
b8faf035 N |
1260 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
1261 | dentry->d_op->d_manage(dentry, true) : 0; | |
62a7375e IK |
1262 | } |
1263 | ||
9875cf80 | 1264 | /* |
287548e4 AV |
1265 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1266 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1267 | */ |
1268 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
254cf582 | 1269 | struct inode **inode, unsigned *seqp) |
9875cf80 | 1270 | { |
62a7375e | 1271 | for (;;) { |
c7105365 | 1272 | struct mount *mounted; |
62a7375e IK |
1273 | /* |
1274 | * Don't forget we might have a non-mountpoint managed dentry | |
1275 | * that wants to block transit. | |
1276 | */ | |
b8faf035 N |
1277 | switch (managed_dentry_rcu(path->dentry)) { |
1278 | case -ECHILD: | |
1279 | default: | |
ab90911f | 1280 | return false; |
b8faf035 N |
1281 | case -EISDIR: |
1282 | return true; | |
1283 | case 0: | |
1284 | break; | |
1285 | } | |
62a7375e IK |
1286 | |
1287 | if (!d_mountpoint(path->dentry)) | |
b8faf035 | 1288 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
62a7375e | 1289 | |
474279dc | 1290 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1291 | if (!mounted) |
1292 | break; | |
c7105365 AV |
1293 | path->mnt = &mounted->mnt; |
1294 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1295 | nd->flags |= LOOKUP_JUMPED; |
254cf582 | 1296 | *seqp = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1297 | /* |
1298 | * Update the inode too. We don't need to re-check the | |
1299 | * dentry sequence number here after this d_inode read, | |
1300 | * because a mount-point is always pinned. | |
1301 | */ | |
1302 | *inode = path->dentry->d_inode; | |
9875cf80 | 1303 | } |
f5be3e29 | 1304 | return !read_seqretry(&mount_lock, nd->m_seq) && |
b8faf035 | 1305 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
287548e4 AV |
1306 | } |
1307 | ||
31e6b01f NP |
1308 | static int follow_dotdot_rcu(struct nameidata *nd) |
1309 | { | |
4023bfc9 | 1310 | struct inode *inode = nd->inode; |
7bd88377 AV |
1311 | if (!nd->root.mnt) |
1312 | set_root_rcu(nd); | |
31e6b01f | 1313 | |
9875cf80 | 1314 | while (1) { |
aed434ad | 1315 | if (path_equal(&nd->path, &nd->root)) |
31e6b01f | 1316 | break; |
31e6b01f NP |
1317 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
1318 | struct dentry *old = nd->path.dentry; | |
1319 | struct dentry *parent = old->d_parent; | |
1320 | unsigned seq; | |
1321 | ||
4023bfc9 | 1322 | inode = parent->d_inode; |
31e6b01f | 1323 | seq = read_seqcount_begin(&parent->d_seq); |
aed434ad AV |
1324 | if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) |
1325 | return -ECHILD; | |
31e6b01f NP |
1326 | nd->path.dentry = parent; |
1327 | nd->seq = seq; | |
397d425d EB |
1328 | if (unlikely(!path_connected(&nd->path))) |
1329 | return -ENOENT; | |
31e6b01f | 1330 | break; |
aed434ad AV |
1331 | } else { |
1332 | struct mount *mnt = real_mount(nd->path.mnt); | |
1333 | struct mount *mparent = mnt->mnt_parent; | |
1334 | struct dentry *mountpoint = mnt->mnt_mountpoint; | |
1335 | struct inode *inode2 = mountpoint->d_inode; | |
1336 | unsigned seq = read_seqcount_begin(&mountpoint->d_seq); | |
1337 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) | |
1338 | return -ECHILD; | |
1339 | if (&mparent->mnt == nd->path.mnt) | |
1340 | break; | |
1341 | /* we know that mountpoint was pinned */ | |
1342 | nd->path.dentry = mountpoint; | |
1343 | nd->path.mnt = &mparent->mnt; | |
1344 | inode = inode2; | |
1345 | nd->seq = seq; | |
31e6b01f | 1346 | } |
31e6b01f | 1347 | } |
aed434ad | 1348 | while (unlikely(d_mountpoint(nd->path.dentry))) { |
b37199e6 AV |
1349 | struct mount *mounted; |
1350 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
aed434ad AV |
1351 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) |
1352 | return -ECHILD; | |
b37199e6 AV |
1353 | if (!mounted) |
1354 | break; | |
1355 | nd->path.mnt = &mounted->mnt; | |
1356 | nd->path.dentry = mounted->mnt.mnt_root; | |
4023bfc9 | 1357 | inode = nd->path.dentry->d_inode; |
b37199e6 | 1358 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
b37199e6 | 1359 | } |
4023bfc9 | 1360 | nd->inode = inode; |
31e6b01f NP |
1361 | return 0; |
1362 | } | |
1363 | ||
cc53ce53 DH |
1364 | /* |
1365 | * Follow down to the covering mount currently visible to userspace. At each | |
1366 | * point, the filesystem owning that dentry may be queried as to whether the | |
1367 | * caller is permitted to proceed or not. | |
cc53ce53 | 1368 | */ |
7cc90cc3 | 1369 | int follow_down(struct path *path) |
cc53ce53 DH |
1370 | { |
1371 | unsigned managed; | |
1372 | int ret; | |
1373 | ||
1374 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1375 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1376 | /* Allow the filesystem to manage the transit without i_mutex | |
1377 | * being held. | |
1378 | * | |
1379 | * We indicate to the filesystem if someone is trying to mount | |
1380 | * something here. This gives autofs the chance to deny anyone | |
1381 | * other than its daemon the right to mount on its | |
1382 | * superstructure. | |
1383 | * | |
1384 | * The filesystem may sleep at this point. | |
1385 | */ | |
1386 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1387 | BUG_ON(!path->dentry->d_op); | |
1388 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1389 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1390 | path->dentry, false); |
cc53ce53 DH |
1391 | if (ret < 0) |
1392 | return ret == -EISDIR ? 0 : ret; | |
1393 | } | |
1394 | ||
1395 | /* Transit to a mounted filesystem. */ | |
1396 | if (managed & DCACHE_MOUNTED) { | |
1397 | struct vfsmount *mounted = lookup_mnt(path); | |
1398 | if (!mounted) | |
1399 | break; | |
1400 | dput(path->dentry); | |
1401 | mntput(path->mnt); | |
1402 | path->mnt = mounted; | |
1403 | path->dentry = dget(mounted->mnt_root); | |
1404 | continue; | |
1405 | } | |
1406 | ||
1407 | /* Don't handle automount points here */ | |
1408 | break; | |
1409 | } | |
1410 | return 0; | |
1411 | } | |
4d359507 | 1412 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1413 | |
9875cf80 DH |
1414 | /* |
1415 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1416 | */ | |
1417 | static void follow_mount(struct path *path) | |
1418 | { | |
1419 | while (d_mountpoint(path->dentry)) { | |
1420 | struct vfsmount *mounted = lookup_mnt(path); | |
1421 | if (!mounted) | |
1422 | break; | |
1423 | dput(path->dentry); | |
1424 | mntput(path->mnt); | |
1425 | path->mnt = mounted; | |
1426 | path->dentry = dget(mounted->mnt_root); | |
1427 | } | |
1428 | } | |
1429 | ||
397d425d | 1430 | static int follow_dotdot(struct nameidata *nd) |
1da177e4 | 1431 | { |
7bd88377 AV |
1432 | if (!nd->root.mnt) |
1433 | set_root(nd); | |
e518ddb7 | 1434 | |
1da177e4 | 1435 | while(1) { |
4ac91378 | 1436 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1437 | |
2a737871 AV |
1438 | if (nd->path.dentry == nd->root.dentry && |
1439 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1440 | break; |
1441 | } | |
4ac91378 | 1442 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1443 | /* rare case of legitimate dget_parent()... */ |
1444 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 | 1445 | dput(old); |
397d425d EB |
1446 | if (unlikely(!path_connected(&nd->path))) |
1447 | return -ENOENT; | |
1da177e4 LT |
1448 | break; |
1449 | } | |
3088dd70 | 1450 | if (!follow_up(&nd->path)) |
1da177e4 | 1451 | break; |
1da177e4 | 1452 | } |
79ed0226 | 1453 | follow_mount(&nd->path); |
31e6b01f | 1454 | nd->inode = nd->path.dentry->d_inode; |
397d425d | 1455 | return 0; |
1da177e4 LT |
1456 | } |
1457 | ||
baa03890 | 1458 | /* |
bad61189 MS |
1459 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1460 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1461 | * returns whether i_op->lookup is necessary. | |
1462 | * | |
1463 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1464 | */ |
bad61189 | 1465 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1466 | unsigned int flags, bool *need_lookup) |
baa03890 | 1467 | { |
baa03890 | 1468 | struct dentry *dentry; |
bad61189 | 1469 | int error; |
baa03890 | 1470 | |
bad61189 MS |
1471 | *need_lookup = false; |
1472 | dentry = d_lookup(dir, name); | |
1473 | if (dentry) { | |
39e3c955 | 1474 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1475 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1476 | if (unlikely(error <= 0)) { |
1477 | if (error < 0) { | |
1478 | dput(dentry); | |
1479 | return ERR_PTR(error); | |
5542aa2f EB |
1480 | } else { |
1481 | d_invalidate(dentry); | |
bad61189 MS |
1482 | dput(dentry); |
1483 | dentry = NULL; | |
1484 | } | |
1485 | } | |
1486 | } | |
1487 | } | |
baa03890 | 1488 | |
bad61189 MS |
1489 | if (!dentry) { |
1490 | dentry = d_alloc(dir, name); | |
1491 | if (unlikely(!dentry)) | |
1492 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1493 | |
bad61189 | 1494 | *need_lookup = true; |
baa03890 NP |
1495 | } |
1496 | return dentry; | |
1497 | } | |
1498 | ||
44396f4b | 1499 | /* |
13a2c3be BF |
1500 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1501 | * unhashed. | |
bad61189 MS |
1502 | * |
1503 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1504 | */ |
bad61189 | 1505 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1506 | unsigned int flags) |
44396f4b | 1507 | { |
44396f4b JB |
1508 | struct dentry *old; |
1509 | ||
1510 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1511 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1512 | dput(dentry); |
44396f4b | 1513 | return ERR_PTR(-ENOENT); |
e188dc02 | 1514 | } |
44396f4b | 1515 | |
72bd866a | 1516 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1517 | if (unlikely(old)) { |
1518 | dput(dentry); | |
1519 | dentry = old; | |
1520 | } | |
1521 | return dentry; | |
1522 | } | |
1523 | ||
a3255546 | 1524 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1525 | struct dentry *base, unsigned int flags) |
a3255546 | 1526 | { |
bad61189 | 1527 | bool need_lookup; |
a3255546 AV |
1528 | struct dentry *dentry; |
1529 | ||
72bd866a | 1530 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1531 | if (!need_lookup) |
1532 | return dentry; | |
a3255546 | 1533 | |
72bd866a | 1534 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1535 | } |
1536 | ||
1da177e4 LT |
1537 | /* |
1538 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1539 | * small and for now I'd prefer to have fast path as straight as possible. | |
1540 | * It _is_ time-critical. | |
1541 | */ | |
e97cdc87 | 1542 | static int lookup_fast(struct nameidata *nd, |
254cf582 AV |
1543 | struct path *path, struct inode **inode, |
1544 | unsigned *seqp) | |
1da177e4 | 1545 | { |
4ac91378 | 1546 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1547 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1548 | int need_reval = 1; |
1549 | int status = 1; | |
9875cf80 DH |
1550 | int err; |
1551 | ||
b04f784e NP |
1552 | /* |
1553 | * Rename seqlock is not required here because in the off chance | |
1554 | * of a false negative due to a concurrent rename, we're going to | |
1555 | * do the non-racy lookup, below. | |
1556 | */ | |
31e6b01f NP |
1557 | if (nd->flags & LOOKUP_RCU) { |
1558 | unsigned seq; | |
766c4cbf | 1559 | bool negative; |
da53be12 | 1560 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1561 | if (!dentry) |
1562 | goto unlazy; | |
1563 | ||
12f8ad4b LT |
1564 | /* |
1565 | * This sequence count validates that the inode matches | |
1566 | * the dentry name information from lookup. | |
1567 | */ | |
63afdfc7 | 1568 | *inode = d_backing_inode(dentry); |
766c4cbf | 1569 | negative = d_is_negative(dentry); |
12f8ad4b LT |
1570 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
1571 | return -ECHILD; | |
1572 | ||
1573 | /* | |
1574 | * This sequence count validates that the parent had no | |
1575 | * changes while we did the lookup of the dentry above. | |
1576 | * | |
1577 | * The memory barrier in read_seqcount_begin of child is | |
1578 | * enough, we can use __read_seqcount_retry here. | |
1579 | */ | |
31e6b01f NP |
1580 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1581 | return -ECHILD; | |
5a18fff2 | 1582 | |
254cf582 | 1583 | *seqp = seq; |
24643087 | 1584 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1585 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1586 | if (unlikely(status <= 0)) { |
1587 | if (status != -ECHILD) | |
1588 | need_reval = 0; | |
1589 | goto unlazy; | |
1590 | } | |
24643087 | 1591 | } |
daf3761c TM |
1592 | /* |
1593 | * Note: do negative dentry check after revalidation in | |
1594 | * case that drops it. | |
1595 | */ | |
1596 | if (negative) | |
1597 | return -ENOENT; | |
31e6b01f NP |
1598 | path->mnt = mnt; |
1599 | path->dentry = dentry; | |
254cf582 | 1600 | if (likely(__follow_mount_rcu(nd, path, inode, seqp))) |
b8faf035 | 1601 | return 0; |
5a18fff2 | 1602 | unlazy: |
254cf582 | 1603 | if (unlazy_walk(nd, dentry, seq)) |
19660af7 | 1604 | return -ECHILD; |
5a18fff2 | 1605 | } else { |
e97cdc87 | 1606 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1607 | } |
5a18fff2 | 1608 | |
81e6f520 AV |
1609 | if (unlikely(!dentry)) |
1610 | goto need_lookup; | |
1611 | ||
5a18fff2 | 1612 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1613 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1614 | if (unlikely(status <= 0)) { |
1615 | if (status < 0) { | |
1616 | dput(dentry); | |
1617 | return status; | |
1618 | } | |
5542aa2f EB |
1619 | d_invalidate(dentry); |
1620 | dput(dentry); | |
1621 | goto need_lookup; | |
24643087 | 1622 | } |
697f514d | 1623 | |
766c4cbf AV |
1624 | if (unlikely(d_is_negative(dentry))) { |
1625 | dput(dentry); | |
1626 | return -ENOENT; | |
1627 | } | |
9875cf80 DH |
1628 | path->mnt = mnt; |
1629 | path->dentry = dentry; | |
756daf26 | 1630 | err = follow_managed(path, nd); |
8402752e | 1631 | if (likely(!err)) |
63afdfc7 | 1632 | *inode = d_backing_inode(path->dentry); |
8402752e | 1633 | return err; |
81e6f520 AV |
1634 | |
1635 | need_lookup: | |
697f514d MS |
1636 | return 1; |
1637 | } | |
1638 | ||
1639 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1640 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1641 | { |
1642 | struct dentry *dentry, *parent; | |
697f514d MS |
1643 | |
1644 | parent = nd->path.dentry; | |
81e6f520 AV |
1645 | BUG_ON(nd->inode != parent->d_inode); |
1646 | ||
1647 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1648 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1649 | mutex_unlock(&parent->d_inode->i_mutex); |
1650 | if (IS_ERR(dentry)) | |
1651 | return PTR_ERR(dentry); | |
697f514d MS |
1652 | path->mnt = nd->path.mnt; |
1653 | path->dentry = dentry; | |
8402752e | 1654 | return follow_managed(path, nd); |
1da177e4 LT |
1655 | } |
1656 | ||
52094c8a AV |
1657 | static inline int may_lookup(struct nameidata *nd) |
1658 | { | |
1659 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1660 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1661 | if (err != -ECHILD) |
1662 | return err; | |
6e9918b7 | 1663 | if (unlazy_walk(nd, NULL, 0)) |
52094c8a AV |
1664 | return -ECHILD; |
1665 | } | |
4ad5abb3 | 1666 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1667 | } |
1668 | ||
9856fa1b AV |
1669 | static inline int handle_dots(struct nameidata *nd, int type) |
1670 | { | |
1671 | if (type == LAST_DOTDOT) { | |
1672 | if (nd->flags & LOOKUP_RCU) { | |
70291aec | 1673 | return follow_dotdot_rcu(nd); |
9856fa1b | 1674 | } else |
397d425d | 1675 | return follow_dotdot(nd); |
9856fa1b AV |
1676 | } |
1677 | return 0; | |
1678 | } | |
1679 | ||
181548c0 AV |
1680 | static int pick_link(struct nameidata *nd, struct path *link, |
1681 | struct inode *inode, unsigned seq) | |
d63ff28f | 1682 | { |
626de996 | 1683 | int error; |
1cf2665b | 1684 | struct saved *last; |
756daf26 | 1685 | if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { |
626de996 AV |
1686 | path_to_nameidata(link, nd); |
1687 | return -ELOOP; | |
1688 | } | |
bc40aee0 | 1689 | if (!(nd->flags & LOOKUP_RCU)) { |
7973387a AV |
1690 | if (link->mnt == nd->path.mnt) |
1691 | mntget(link->mnt); | |
d63ff28f | 1692 | } |
626de996 AV |
1693 | error = nd_alloc_stack(nd); |
1694 | if (unlikely(error)) { | |
bc40aee0 AV |
1695 | if (error == -ECHILD) { |
1696 | if (unlikely(unlazy_link(nd, link, seq))) | |
1697 | return -ECHILD; | |
1698 | error = nd_alloc_stack(nd); | |
1699 | } | |
1700 | if (error) { | |
1701 | path_put(link); | |
1702 | return error; | |
1703 | } | |
626de996 AV |
1704 | } |
1705 | ||
ab104923 | 1706 | last = nd->stack + nd->depth++; |
1cf2665b | 1707 | last->link = *link; |
ab104923 | 1708 | last->cookie = NULL; |
181548c0 | 1709 | last->inode = inode; |
0450b2d1 | 1710 | last->seq = seq; |
d63ff28f AV |
1711 | return 1; |
1712 | } | |
1713 | ||
3ddcd056 LT |
1714 | /* |
1715 | * Do we need to follow links? We _really_ want to be able | |
1716 | * to do this check without having to look at inode->i_op, | |
1717 | * so we keep a cache of "no, this doesn't need follow_link" | |
1718 | * for the common case. | |
1719 | */ | |
254cf582 | 1720 | static inline int should_follow_link(struct nameidata *nd, struct path *link, |
181548c0 AV |
1721 | int follow, |
1722 | struct inode *inode, unsigned seq) | |
3ddcd056 | 1723 | { |
d63ff28f AV |
1724 | if (likely(!d_is_symlink(link->dentry))) |
1725 | return 0; | |
1726 | if (!follow) | |
1727 | return 0; | |
3b97fd9e AV |
1728 | /* make sure that d_is_symlink above matches inode */ |
1729 | if (nd->flags & LOOKUP_RCU) { | |
1730 | if (read_seqcount_retry(&link->dentry->d_seq, seq)) | |
1731 | return -ECHILD; | |
1732 | } | |
181548c0 | 1733 | return pick_link(nd, link, inode, seq); |
3ddcd056 LT |
1734 | } |
1735 | ||
4693a547 AV |
1736 | enum {WALK_GET = 1, WALK_PUT = 2}; |
1737 | ||
1738 | static int walk_component(struct nameidata *nd, int flags) | |
ce57dfc1 | 1739 | { |
caa85634 | 1740 | struct path path; |
ce57dfc1 | 1741 | struct inode *inode; |
254cf582 | 1742 | unsigned seq; |
ce57dfc1 AV |
1743 | int err; |
1744 | /* | |
1745 | * "." and ".." are special - ".." especially so because it has | |
1746 | * to be able to know about the current root directory and | |
1747 | * parent relationships. | |
1748 | */ | |
4693a547 AV |
1749 | if (unlikely(nd->last_type != LAST_NORM)) { |
1750 | err = handle_dots(nd, nd->last_type); | |
1751 | if (flags & WALK_PUT) | |
1752 | put_link(nd); | |
1753 | return err; | |
1754 | } | |
254cf582 | 1755 | err = lookup_fast(nd, &path, &inode, &seq); |
ce57dfc1 | 1756 | if (unlikely(err)) { |
697f514d | 1757 | if (err < 0) |
f0a9ba70 | 1758 | return err; |
697f514d | 1759 | |
caa85634 | 1760 | err = lookup_slow(nd, &path); |
697f514d | 1761 | if (err < 0) |
f0a9ba70 | 1762 | return err; |
697f514d | 1763 | |
254cf582 | 1764 | seq = 0; /* we are already out of RCU mode */ |
766c4cbf | 1765 | err = -ENOENT; |
caa85634 | 1766 | if (d_is_negative(path.dentry)) |
766c4cbf | 1767 | goto out_path_put; |
32b9b145 | 1768 | inode = d_backing_inode(path.dentry); |
ce57dfc1 | 1769 | } |
697f514d | 1770 | |
4693a547 AV |
1771 | if (flags & WALK_PUT) |
1772 | put_link(nd); | |
181548c0 | 1773 | err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); |
d63ff28f AV |
1774 | if (unlikely(err)) |
1775 | return err; | |
caa85634 | 1776 | path_to_nameidata(&path, nd); |
ce57dfc1 | 1777 | nd->inode = inode; |
254cf582 | 1778 | nd->seq = seq; |
ce57dfc1 | 1779 | return 0; |
697f514d MS |
1780 | |
1781 | out_path_put: | |
caa85634 | 1782 | path_to_nameidata(&path, nd); |
697f514d | 1783 | return err; |
ce57dfc1 AV |
1784 | } |
1785 | ||
bfcfaa77 LT |
1786 | /* |
1787 | * We can do the critical dentry name comparison and hashing | |
1788 | * operations one word at a time, but we are limited to: | |
1789 | * | |
1790 | * - Architectures with fast unaligned word accesses. We could | |
1791 | * do a "get_unaligned()" if this helps and is sufficiently | |
1792 | * fast. | |
1793 | * | |
bfcfaa77 LT |
1794 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1795 | * do not trap on the (extremely unlikely) case of a page | |
1796 | * crossing operation. | |
1797 | * | |
1798 | * - Furthermore, we need an efficient 64-bit compile for the | |
1799 | * 64-bit case in order to generate the "number of bytes in | |
1800 | * the final mask". Again, that could be replaced with a | |
1801 | * efficient population count instruction or similar. | |
1802 | */ | |
1803 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1804 | ||
f68e556e | 1805 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1806 | |
f68e556e | 1807 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1808 | |
1809 | static inline unsigned int fold_hash(unsigned long hash) | |
1810 | { | |
99d263d4 | 1811 | return hash_64(hash, 32); |
bfcfaa77 LT |
1812 | } |
1813 | ||
1814 | #else /* 32-bit case */ | |
1815 | ||
bfcfaa77 LT |
1816 | #define fold_hash(x) (x) |
1817 | ||
1818 | #endif | |
1819 | ||
1820 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1821 | { | |
1822 | unsigned long a, mask; | |
1823 | unsigned long hash = 0; | |
1824 | ||
1825 | for (;;) { | |
e419b4cc | 1826 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1827 | if (len < sizeof(unsigned long)) |
1828 | break; | |
1829 | hash += a; | |
f132c5be | 1830 | hash *= 9; |
bfcfaa77 LT |
1831 | name += sizeof(unsigned long); |
1832 | len -= sizeof(unsigned long); | |
1833 | if (!len) | |
1834 | goto done; | |
1835 | } | |
a5c21dce | 1836 | mask = bytemask_from_count(len); |
bfcfaa77 LT |
1837 | hash += mask & a; |
1838 | done: | |
1839 | return fold_hash(hash); | |
1840 | } | |
1841 | EXPORT_SYMBOL(full_name_hash); | |
1842 | ||
bfcfaa77 LT |
1843 | /* |
1844 | * Calculate the length and hash of the path component, and | |
d6bb3e90 | 1845 | * return the "hash_len" as the result. |
bfcfaa77 | 1846 | */ |
d6bb3e90 | 1847 | static inline u64 hash_name(const char *name) |
bfcfaa77 | 1848 | { |
36126f8f LT |
1849 | unsigned long a, b, adata, bdata, mask, hash, len; |
1850 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1851 | |
1852 | hash = a = 0; | |
1853 | len = -sizeof(unsigned long); | |
1854 | do { | |
1855 | hash = (hash + a) * 9; | |
1856 | len += sizeof(unsigned long); | |
e419b4cc | 1857 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1858 | b = a ^ REPEAT_BYTE('/'); |
1859 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1860 | ||
1861 | adata = prep_zero_mask(a, adata, &constants); | |
1862 | bdata = prep_zero_mask(b, bdata, &constants); | |
1863 | ||
1864 | mask = create_zero_mask(adata | bdata); | |
1865 | ||
1866 | hash += a & zero_bytemask(mask); | |
9226b5b4 | 1867 | len += find_zero(mask); |
d6bb3e90 | 1868 | return hashlen_create(fold_hash(hash), len); |
bfcfaa77 LT |
1869 | } |
1870 | ||
1871 | #else | |
1872 | ||
0145acc2 LT |
1873 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1874 | { | |
1875 | unsigned long hash = init_name_hash(); | |
1876 | while (len--) | |
1877 | hash = partial_name_hash(*name++, hash); | |
1878 | return end_name_hash(hash); | |
1879 | } | |
ae942ae7 | 1880 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1881 | |
200e9ef7 LT |
1882 | /* |
1883 | * We know there's a real path component here of at least | |
1884 | * one character. | |
1885 | */ | |
d6bb3e90 | 1886 | static inline u64 hash_name(const char *name) |
200e9ef7 LT |
1887 | { |
1888 | unsigned long hash = init_name_hash(); | |
1889 | unsigned long len = 0, c; | |
1890 | ||
1891 | c = (unsigned char)*name; | |
1892 | do { | |
1893 | len++; | |
1894 | hash = partial_name_hash(c, hash); | |
1895 | c = (unsigned char)name[len]; | |
1896 | } while (c && c != '/'); | |
d6bb3e90 | 1897 | return hashlen_create(end_name_hash(hash), len); |
200e9ef7 LT |
1898 | } |
1899 | ||
bfcfaa77 LT |
1900 | #endif |
1901 | ||
1da177e4 LT |
1902 | /* |
1903 | * Name resolution. | |
ea3834d9 PM |
1904 | * This is the basic name resolution function, turning a pathname into |
1905 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1906 | * |
ea3834d9 PM |
1907 | * Returns 0 and nd will have valid dentry and mnt on success. |
1908 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1909 | */ |
6de88d72 | 1910 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 1911 | { |
1da177e4 | 1912 | int err; |
32cd7468 | 1913 | |
1da177e4 LT |
1914 | while (*name=='/') |
1915 | name++; | |
1916 | if (!*name) | |
9e18f10a | 1917 | return 0; |
1da177e4 | 1918 | |
1da177e4 LT |
1919 | /* At this point we know we have a real path component. */ |
1920 | for(;;) { | |
d6bb3e90 | 1921 | u64 hash_len; |
fe479a58 | 1922 | int type; |
1da177e4 | 1923 | |
52094c8a | 1924 | err = may_lookup(nd); |
1da177e4 | 1925 | if (err) |
3595e234 | 1926 | return err; |
1da177e4 | 1927 | |
d6bb3e90 | 1928 | hash_len = hash_name(name); |
1da177e4 | 1929 | |
fe479a58 | 1930 | type = LAST_NORM; |
d6bb3e90 | 1931 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
fe479a58 | 1932 | case 2: |
200e9ef7 | 1933 | if (name[1] == '.') { |
fe479a58 | 1934 | type = LAST_DOTDOT; |
16c2cd71 AV |
1935 | nd->flags |= LOOKUP_JUMPED; |
1936 | } | |
fe479a58 AV |
1937 | break; |
1938 | case 1: | |
1939 | type = LAST_DOT; | |
1940 | } | |
5a202bcd AV |
1941 | if (likely(type == LAST_NORM)) { |
1942 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1943 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1944 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
a060dc50 | 1945 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
da53be12 | 1946 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd | 1947 | if (err < 0) |
3595e234 | 1948 | return err; |
d6bb3e90 LT |
1949 | hash_len = this.hash_len; |
1950 | name = this.name; | |
5a202bcd AV |
1951 | } |
1952 | } | |
fe479a58 | 1953 | |
d6bb3e90 LT |
1954 | nd->last.hash_len = hash_len; |
1955 | nd->last.name = name; | |
5f4a6a69 AV |
1956 | nd->last_type = type; |
1957 | ||
d6bb3e90 LT |
1958 | name += hashlen_len(hash_len); |
1959 | if (!*name) | |
bdf6cbf1 | 1960 | goto OK; |
200e9ef7 LT |
1961 | /* |
1962 | * If it wasn't NUL, we know it was '/'. Skip that | |
1963 | * slash, and continue until no more slashes. | |
1964 | */ | |
1965 | do { | |
d6bb3e90 LT |
1966 | name++; |
1967 | } while (unlikely(*name == '/')); | |
8620c238 AV |
1968 | if (unlikely(!*name)) { |
1969 | OK: | |
368ee9ba | 1970 | /* pathname body, done */ |
8620c238 AV |
1971 | if (!nd->depth) |
1972 | return 0; | |
1973 | name = nd->stack[nd->depth - 1].name; | |
368ee9ba | 1974 | /* trailing symlink, done */ |
8620c238 AV |
1975 | if (!name) |
1976 | return 0; | |
1977 | /* last component of nested symlink */ | |
4693a547 | 1978 | err = walk_component(nd, WALK_GET | WALK_PUT); |
8620c238 | 1979 | } else { |
4693a547 | 1980 | err = walk_component(nd, WALK_GET); |
8620c238 | 1981 | } |
ce57dfc1 | 1982 | if (err < 0) |
3595e234 | 1983 | return err; |
1da177e4 | 1984 | |
ce57dfc1 | 1985 | if (err) { |
626de996 | 1986 | const char *s = get_link(nd); |
5a460275 | 1987 | |
a1c83681 | 1988 | if (IS_ERR(s)) |
3595e234 | 1989 | return PTR_ERR(s); |
d40bcc09 AV |
1990 | err = 0; |
1991 | if (unlikely(!s)) { | |
1992 | /* jumped */ | |
b9ff4429 | 1993 | put_link(nd); |
d40bcc09 | 1994 | } else { |
fab51e8a AV |
1995 | nd->stack[nd->depth - 1].name = name; |
1996 | name = s; | |
1997 | continue; | |
d40bcc09 | 1998 | } |
31e6b01f | 1999 | } |
97242f99 AV |
2000 | if (unlikely(!d_can_lookup(nd->path.dentry))) { |
2001 | if (nd->flags & LOOKUP_RCU) { | |
2002 | if (unlazy_walk(nd, NULL, 0)) | |
2003 | return -ECHILD; | |
2004 | } | |
3595e234 | 2005 | return -ENOTDIR; |
97242f99 | 2006 | } |
1da177e4 | 2007 | } |
1da177e4 LT |
2008 | } |
2009 | ||
c8a53ee5 | 2010 | static const char *path_init(struct nameidata *nd, unsigned flags) |
31e6b01f NP |
2011 | { |
2012 | int retval = 0; | |
c8a53ee5 | 2013 | const char *s = nd->name->name; |
31e6b01f NP |
2014 | |
2015 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
980f3ea2 | 2016 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
31e6b01f | 2017 | nd->depth = 0; |
5b6ca027 | 2018 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
2019 | struct dentry *root = nd->root.dentry; |
2020 | struct inode *inode = root->d_inode; | |
fd2f7cb5 | 2021 | if (*s) { |
44b1d530 | 2022 | if (!d_can_lookup(root)) |
368ee9ba | 2023 | return ERR_PTR(-ENOTDIR); |
73d049a4 AV |
2024 | retval = inode_permission(inode, MAY_EXEC); |
2025 | if (retval) | |
368ee9ba | 2026 | return ERR_PTR(retval); |
73d049a4 | 2027 | } |
5b6ca027 AV |
2028 | nd->path = nd->root; |
2029 | nd->inode = inode; | |
2030 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 2031 | rcu_read_lock(); |
5b6ca027 | 2032 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8f47a016 | 2033 | nd->root_seq = nd->seq; |
48a066e7 | 2034 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
2035 | } else { |
2036 | path_get(&nd->path); | |
2037 | } | |
368ee9ba | 2038 | return s; |
5b6ca027 AV |
2039 | } |
2040 | ||
31e6b01f | 2041 | nd->root.mnt = NULL; |
31e6b01f | 2042 | |
48a066e7 | 2043 | nd->m_seq = read_seqbegin(&mount_lock); |
fd2f7cb5 | 2044 | if (*s == '/') { |
e41f7d4e | 2045 | if (flags & LOOKUP_RCU) { |
8b61e74f | 2046 | rcu_read_lock(); |
06d7137e AV |
2047 | set_root_rcu(nd); |
2048 | nd->seq = nd->root_seq; | |
e41f7d4e AV |
2049 | } else { |
2050 | set_root(nd); | |
2051 | path_get(&nd->root); | |
2052 | } | |
2053 | nd->path = nd->root; | |
c8a53ee5 | 2054 | } else if (nd->dfd == AT_FDCWD) { |
e41f7d4e AV |
2055 | if (flags & LOOKUP_RCU) { |
2056 | struct fs_struct *fs = current->fs; | |
2057 | unsigned seq; | |
31e6b01f | 2058 | |
8b61e74f | 2059 | rcu_read_lock(); |
c28cc364 | 2060 | |
e41f7d4e AV |
2061 | do { |
2062 | seq = read_seqcount_begin(&fs->seq); | |
2063 | nd->path = fs->pwd; | |
2064 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
2065 | } while (read_seqcount_retry(&fs->seq, seq)); | |
2066 | } else { | |
2067 | get_fs_pwd(current->fs, &nd->path); | |
2068 | } | |
31e6b01f | 2069 | } else { |
582aa64a | 2070 | /* Caller must check execute permissions on the starting path component */ |
c8a53ee5 | 2071 | struct fd f = fdget_raw(nd->dfd); |
31e6b01f NP |
2072 | struct dentry *dentry; |
2073 | ||
2903ff01 | 2074 | if (!f.file) |
368ee9ba | 2075 | return ERR_PTR(-EBADF); |
31e6b01f | 2076 | |
2903ff01 | 2077 | dentry = f.file->f_path.dentry; |
31e6b01f | 2078 | |
fd2f7cb5 | 2079 | if (*s) { |
44b1d530 | 2080 | if (!d_can_lookup(dentry)) { |
2903ff01 | 2081 | fdput(f); |
368ee9ba | 2082 | return ERR_PTR(-ENOTDIR); |
2903ff01 | 2083 | } |
f52e0c11 | 2084 | } |
31e6b01f | 2085 | |
2903ff01 | 2086 | nd->path = f.file->f_path; |
e41f7d4e | 2087 | if (flags & LOOKUP_RCU) { |
8b61e74f | 2088 | rcu_read_lock(); |
34a26b99 AV |
2089 | nd->inode = nd->path.dentry->d_inode; |
2090 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
e41f7d4e | 2091 | } else { |
2903ff01 | 2092 | path_get(&nd->path); |
34a26b99 | 2093 | nd->inode = nd->path.dentry->d_inode; |
e41f7d4e | 2094 | } |
34a26b99 | 2095 | fdput(f); |
368ee9ba | 2096 | return s; |
31e6b01f | 2097 | } |
31e6b01f | 2098 | |
31e6b01f | 2099 | nd->inode = nd->path.dentry->d_inode; |
4023bfc9 | 2100 | if (!(flags & LOOKUP_RCU)) |
368ee9ba | 2101 | return s; |
4023bfc9 | 2102 | if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) |
368ee9ba | 2103 | return s; |
4023bfc9 AV |
2104 | if (!(nd->flags & LOOKUP_ROOT)) |
2105 | nd->root.mnt = NULL; | |
2106 | rcu_read_unlock(); | |
368ee9ba | 2107 | return ERR_PTR(-ECHILD); |
9b4a9b14 AV |
2108 | } |
2109 | ||
3bdba28b | 2110 | static const char *trailing_symlink(struct nameidata *nd) |
95fa25d9 AV |
2111 | { |
2112 | const char *s; | |
fec2fa24 | 2113 | int error = may_follow_link(nd); |
deb106c6 | 2114 | if (unlikely(error)) |
3bdba28b | 2115 | return ERR_PTR(error); |
95fa25d9 | 2116 | nd->flags |= LOOKUP_PARENT; |
fab51e8a | 2117 | nd->stack[0].name = NULL; |
3b2e7f75 | 2118 | s = get_link(nd); |
deb106c6 | 2119 | return s ? s : ""; |
95fa25d9 AV |
2120 | } |
2121 | ||
caa85634 | 2122 | static inline int lookup_last(struct nameidata *nd) |
bd92d7fe AV |
2123 | { |
2124 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
2125 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
2126 | ||
2127 | nd->flags &= ~LOOKUP_PARENT; | |
deb106c6 | 2128 | return walk_component(nd, |
4693a547 AV |
2129 | nd->flags & LOOKUP_FOLLOW |
2130 | ? nd->depth | |
2131 | ? WALK_PUT | WALK_GET | |
2132 | : WALK_GET | |
2133 | : 0); | |
bd92d7fe AV |
2134 | } |
2135 | ||
9b4a9b14 | 2136 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
c8a53ee5 | 2137 | static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) |
9b4a9b14 | 2138 | { |
c8a53ee5 | 2139 | const char *s = path_init(nd, flags); |
bd92d7fe | 2140 | int err; |
31e6b01f | 2141 | |
368ee9ba AV |
2142 | if (IS_ERR(s)) |
2143 | return PTR_ERR(s); | |
3bdba28b AV |
2144 | while (!(err = link_path_walk(s, nd)) |
2145 | && ((err = lookup_last(nd)) > 0)) { | |
2146 | s = trailing_symlink(nd); | |
2147 | if (IS_ERR(s)) { | |
2148 | err = PTR_ERR(s); | |
2149 | break; | |
bd92d7fe AV |
2150 | } |
2151 | } | |
9f1fafee AV |
2152 | if (!err) |
2153 | err = complete_walk(nd); | |
bd92d7fe | 2154 | |
deb106c6 AV |
2155 | if (!err && nd->flags & LOOKUP_DIRECTORY) |
2156 | if (!d_can_lookup(nd->path.dentry)) | |
bd23a539 | 2157 | err = -ENOTDIR; |
625b6d10 AV |
2158 | if (!err) { |
2159 | *path = nd->path; | |
2160 | nd->path.mnt = NULL; | |
2161 | nd->path.dentry = NULL; | |
2162 | } | |
2163 | terminate_walk(nd); | |
bd92d7fe | 2164 | return err; |
ee0827cd | 2165 | } |
31e6b01f | 2166 | |
625b6d10 | 2167 | static int filename_lookup(int dfd, struct filename *name, unsigned flags, |
9ad1aaa6 | 2168 | struct path *path, struct path *root) |
ee0827cd | 2169 | { |
894bc8c4 | 2170 | int retval; |
9883d185 | 2171 | struct nameidata nd; |
abc9f5be AV |
2172 | if (IS_ERR(name)) |
2173 | return PTR_ERR(name); | |
9ad1aaa6 AV |
2174 | if (unlikely(root)) { |
2175 | nd.root = *root; | |
2176 | flags |= LOOKUP_ROOT; | |
2177 | } | |
9883d185 | 2178 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2179 | retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); |
ee0827cd | 2180 | if (unlikely(retval == -ECHILD)) |
c8a53ee5 | 2181 | retval = path_lookupat(&nd, flags, path); |
ee0827cd | 2182 | if (unlikely(retval == -ESTALE)) |
c8a53ee5 | 2183 | retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); |
31e6b01f | 2184 | |
f78570dd | 2185 | if (likely(!retval)) |
625b6d10 | 2186 | audit_inode(name, path->dentry, flags & LOOKUP_PARENT); |
9883d185 | 2187 | restore_nameidata(); |
e4bd1c1a | 2188 | putname(name); |
170aa3d0 | 2189 | return retval; |
1da177e4 LT |
2190 | } |
2191 | ||
8bcb77fa | 2192 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
c8a53ee5 | 2193 | static int path_parentat(struct nameidata *nd, unsigned flags, |
391172c4 | 2194 | struct path *parent) |
8bcb77fa | 2195 | { |
c8a53ee5 | 2196 | const char *s = path_init(nd, flags); |
368ee9ba AV |
2197 | int err; |
2198 | if (IS_ERR(s)) | |
2199 | return PTR_ERR(s); | |
2200 | err = link_path_walk(s, nd); | |
8bcb77fa AV |
2201 | if (!err) |
2202 | err = complete_walk(nd); | |
391172c4 AV |
2203 | if (!err) { |
2204 | *parent = nd->path; | |
2205 | nd->path.mnt = NULL; | |
2206 | nd->path.dentry = NULL; | |
2207 | } | |
2208 | terminate_walk(nd); | |
8bcb77fa AV |
2209 | return err; |
2210 | } | |
2211 | ||
5c31b6ce | 2212 | static struct filename *filename_parentat(int dfd, struct filename *name, |
391172c4 AV |
2213 | unsigned int flags, struct path *parent, |
2214 | struct qstr *last, int *type) | |
8bcb77fa AV |
2215 | { |
2216 | int retval; | |
9883d185 | 2217 | struct nameidata nd; |
8bcb77fa | 2218 | |
5c31b6ce AV |
2219 | if (IS_ERR(name)) |
2220 | return name; | |
9883d185 | 2221 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2222 | retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); |
8bcb77fa | 2223 | if (unlikely(retval == -ECHILD)) |
c8a53ee5 | 2224 | retval = path_parentat(&nd, flags, parent); |
8bcb77fa | 2225 | if (unlikely(retval == -ESTALE)) |
c8a53ee5 | 2226 | retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); |
391172c4 AV |
2227 | if (likely(!retval)) { |
2228 | *last = nd.last; | |
2229 | *type = nd.last_type; | |
2230 | audit_inode(name, parent->dentry, LOOKUP_PARENT); | |
5c31b6ce AV |
2231 | } else { |
2232 | putname(name); | |
2233 | name = ERR_PTR(retval); | |
391172c4 | 2234 | } |
9883d185 | 2235 | restore_nameidata(); |
5c31b6ce | 2236 | return name; |
8bcb77fa AV |
2237 | } |
2238 | ||
79714f72 AV |
2239 | /* does lookup, returns the object with parent locked */ |
2240 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2241 | { |
5c31b6ce AV |
2242 | struct filename *filename; |
2243 | struct dentry *d; | |
391172c4 AV |
2244 | struct qstr last; |
2245 | int type; | |
51689104 | 2246 | |
5c31b6ce AV |
2247 | filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, |
2248 | &last, &type); | |
51689104 PM |
2249 | if (IS_ERR(filename)) |
2250 | return ERR_CAST(filename); | |
5c31b6ce | 2251 | if (unlikely(type != LAST_NORM)) { |
391172c4 | 2252 | path_put(path); |
5c31b6ce AV |
2253 | putname(filename); |
2254 | return ERR_PTR(-EINVAL); | |
79714f72 | 2255 | } |
391172c4 AV |
2256 | mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2257 | d = __lookup_hash(&last, path->dentry, 0); | |
79714f72 | 2258 | if (IS_ERR(d)) { |
391172c4 AV |
2259 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
2260 | path_put(path); | |
79714f72 | 2261 | } |
51689104 | 2262 | putname(filename); |
79714f72 | 2263 | return d; |
5590ff0d UD |
2264 | } |
2265 | ||
d1811465 AV |
2266 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2267 | { | |
abc9f5be AV |
2268 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
2269 | flags, path, NULL); | |
d1811465 | 2270 | } |
4d359507 | 2271 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2272 | |
16f18200 JJS |
2273 | /** |
2274 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2275 | * @dentry: pointer to dentry of the base directory | |
2276 | * @mnt: pointer to vfs mount of the base directory | |
2277 | * @name: pointer to file name | |
2278 | * @flags: lookup flags | |
e0a01249 | 2279 | * @path: pointer to struct path to fill |
16f18200 JJS |
2280 | */ |
2281 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2282 | const char *name, unsigned int flags, | |
e0a01249 | 2283 | struct path *path) |
16f18200 | 2284 | { |
9ad1aaa6 | 2285 | struct path root = {.mnt = mnt, .dentry = dentry}; |
9ad1aaa6 | 2286 | /* the first argument of filename_lookup() is ignored with root */ |
abc9f5be AV |
2287 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
2288 | flags , path, &root); | |
16f18200 | 2289 | } |
4d359507 | 2290 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2291 | |
eead1911 | 2292 | /** |
a6b91919 | 2293 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2294 | * @name: pathname component to lookup |
2295 | * @base: base directory to lookup from | |
2296 | * @len: maximum length @len should be interpreted to | |
2297 | * | |
a6b91919 | 2298 | * Note that this routine is purely a helper for filesystem usage and should |
9e7543e9 | 2299 | * not be called by generic code. |
eead1911 | 2300 | */ |
057f6c01 JM |
2301 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2302 | { | |
057f6c01 | 2303 | struct qstr this; |
6a96ba54 | 2304 | unsigned int c; |
cda309de | 2305 | int err; |
057f6c01 | 2306 | |
2f9092e1 DW |
2307 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2308 | ||
6a96ba54 AV |
2309 | this.name = name; |
2310 | this.len = len; | |
0145acc2 | 2311 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2312 | if (!len) |
2313 | return ERR_PTR(-EACCES); | |
2314 | ||
21d8a15a AV |
2315 | if (unlikely(name[0] == '.')) { |
2316 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2317 | return ERR_PTR(-EACCES); | |
2318 | } | |
2319 | ||
6a96ba54 AV |
2320 | while (len--) { |
2321 | c = *(const unsigned char *)name++; | |
2322 | if (c == '/' || c == '\0') | |
2323 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2324 | } |
5a202bcd AV |
2325 | /* |
2326 | * See if the low-level filesystem might want | |
2327 | * to use its own hash.. | |
2328 | */ | |
2329 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2330 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2331 | if (err < 0) |
2332 | return ERR_PTR(err); | |
2333 | } | |
eead1911 | 2334 | |
cda309de MS |
2335 | err = inode_permission(base->d_inode, MAY_EXEC); |
2336 | if (err) | |
2337 | return ERR_PTR(err); | |
2338 | ||
72bd866a | 2339 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2340 | } |
4d359507 | 2341 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2342 | |
1fa1e7f6 AW |
2343 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2344 | struct path *path, int *empty) | |
1da177e4 | 2345 | { |
abc9f5be AV |
2346 | return filename_lookup(dfd, getname_flags(name, flags, empty), |
2347 | flags, path, NULL); | |
1da177e4 | 2348 | } |
b853a161 | 2349 | EXPORT_SYMBOL(user_path_at_empty); |
1fa1e7f6 | 2350 | |
873f1eed JL |
2351 | /* |
2352 | * NB: most callers don't do anything directly with the reference to the | |
2353 | * to struct filename, but the nd->last pointer points into the name string | |
2354 | * allocated by getname. So we must hold the reference to it until all | |
2355 | * path-walking is complete. | |
2356 | */ | |
a2ec4a2d | 2357 | static inline struct filename * |
f5beed75 AV |
2358 | user_path_parent(int dfd, const char __user *path, |
2359 | struct path *parent, | |
2360 | struct qstr *last, | |
2361 | int *type, | |
9e790bd6 | 2362 | unsigned int flags) |
2ad94ae6 | 2363 | { |
9e790bd6 | 2364 | /* only LOOKUP_REVAL is allowed in extra flags */ |
5c31b6ce AV |
2365 | return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, |
2366 | parent, last, type); | |
2ad94ae6 AV |
2367 | } |
2368 | ||
8033426e | 2369 | /** |
197df04c | 2370 | * mountpoint_last - look up last component for umount |
8033426e JL |
2371 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2372 | * @path: pointer to container for result | |
2373 | * | |
2374 | * This is a special lookup_last function just for umount. In this case, we | |
2375 | * need to resolve the path without doing any revalidation. | |
2376 | * | |
2377 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2378 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2379 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2380 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2381 | * bogus and it doesn't exist. | |
2382 | * | |
2383 | * Returns: | |
2384 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2385 | * lookup found a negative dentry. The nd->path reference will also be | |
2386 | * put in this case. | |
2387 | * | |
2388 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2389 | * symlink that needs to be followed. "path" will also be populated. | |
2390 | * The nd->path reference will also be put. | |
2391 | * | |
2392 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2393 | * that needs to be followed. "path" will be populated with the path | |
2394 | * to the link, and nd->path will *not* be put. | |
2395 | */ | |
2396 | static int | |
197df04c | 2397 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2398 | { |
2399 | int error = 0; | |
2400 | struct dentry *dentry; | |
2401 | struct dentry *dir = nd->path.dentry; | |
2402 | ||
35759521 AV |
2403 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2404 | if (nd->flags & LOOKUP_RCU) { | |
6e9918b7 | 2405 | if (unlazy_walk(nd, NULL, 0)) |
deb106c6 | 2406 | return -ECHILD; |
8033426e JL |
2407 | } |
2408 | ||
2409 | nd->flags &= ~LOOKUP_PARENT; | |
2410 | ||
2411 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2412 | error = handle_dots(nd, nd->last_type); | |
35759521 | 2413 | if (error) |
deb106c6 | 2414 | return error; |
35759521 AV |
2415 | dentry = dget(nd->path.dentry); |
2416 | goto done; | |
8033426e JL |
2417 | } |
2418 | ||
2419 | mutex_lock(&dir->d_inode->i_mutex); | |
2420 | dentry = d_lookup(dir, &nd->last); | |
2421 | if (!dentry) { | |
2422 | /* | |
2423 | * No cached dentry. Mounted dentries are pinned in the cache, | |
2424 | * so that means that this dentry is probably a symlink or the | |
2425 | * path doesn't actually point to a mounted dentry. | |
2426 | */ | |
2427 | dentry = d_alloc(dir, &nd->last); | |
2428 | if (!dentry) { | |
bcceeeba | 2429 | mutex_unlock(&dir->d_inode->i_mutex); |
deb106c6 | 2430 | return -ENOMEM; |
8033426e | 2431 | } |
35759521 | 2432 | dentry = lookup_real(dir->d_inode, dentry, nd->flags); |
bcceeeba DJ |
2433 | if (IS_ERR(dentry)) { |
2434 | mutex_unlock(&dir->d_inode->i_mutex); | |
deb106c6 | 2435 | return PTR_ERR(dentry); |
bcceeeba | 2436 | } |
8033426e JL |
2437 | } |
2438 | mutex_unlock(&dir->d_inode->i_mutex); | |
2439 | ||
35759521 | 2440 | done: |
698934df | 2441 | if (d_is_negative(dentry)) { |
35759521 | 2442 | dput(dentry); |
deb106c6 | 2443 | return -ENOENT; |
8033426e | 2444 | } |
191d7f73 AV |
2445 | if (nd->depth) |
2446 | put_link(nd); | |
35759521 | 2447 | path->dentry = dentry; |
295dc39d | 2448 | path->mnt = nd->path.mnt; |
181548c0 AV |
2449 | error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, |
2450 | d_backing_inode(dentry), 0); | |
deb106c6 | 2451 | if (unlikely(error)) |
d63ff28f | 2452 | return error; |
295dc39d | 2453 | mntget(path->mnt); |
35759521 | 2454 | follow_mount(path); |
deb106c6 | 2455 | return 0; |
8033426e JL |
2456 | } |
2457 | ||
2458 | /** | |
197df04c | 2459 | * path_mountpoint - look up a path to be umounted |
2a78b857 | 2460 | * @nd: lookup context |
8033426e | 2461 | * @flags: lookup flags |
c8a53ee5 | 2462 | * @path: pointer to container for result |
8033426e JL |
2463 | * |
2464 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2465 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2466 | */ |
2467 | static int | |
c8a53ee5 | 2468 | path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) |
8033426e | 2469 | { |
c8a53ee5 | 2470 | const char *s = path_init(nd, flags); |
368ee9ba AV |
2471 | int err; |
2472 | if (IS_ERR(s)) | |
2473 | return PTR_ERR(s); | |
3bdba28b AV |
2474 | while (!(err = link_path_walk(s, nd)) && |
2475 | (err = mountpoint_last(nd, path)) > 0) { | |
2476 | s = trailing_symlink(nd); | |
2477 | if (IS_ERR(s)) { | |
2478 | err = PTR_ERR(s); | |
8033426e | 2479 | break; |
3bdba28b | 2480 | } |
8033426e | 2481 | } |
deb106c6 | 2482 | terminate_walk(nd); |
8033426e JL |
2483 | return err; |
2484 | } | |
2485 | ||
2d864651 | 2486 | static int |
668696dc | 2487 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
2d864651 AV |
2488 | unsigned int flags) |
2489 | { | |
9883d185 | 2490 | struct nameidata nd; |
cbaab2db | 2491 | int error; |
668696dc AV |
2492 | if (IS_ERR(name)) |
2493 | return PTR_ERR(name); | |
9883d185 | 2494 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2495 | error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); |
2d864651 | 2496 | if (unlikely(error == -ECHILD)) |
c8a53ee5 | 2497 | error = path_mountpoint(&nd, flags, path); |
2d864651 | 2498 | if (unlikely(error == -ESTALE)) |
c8a53ee5 | 2499 | error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); |
2d864651 | 2500 | if (likely(!error)) |
668696dc | 2501 | audit_inode(name, path->dentry, 0); |
9883d185 | 2502 | restore_nameidata(); |
668696dc | 2503 | putname(name); |
2d864651 AV |
2504 | return error; |
2505 | } | |
2506 | ||
8033426e | 2507 | /** |
197df04c | 2508 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2509 | * @dfd: directory file descriptor |
2510 | * @name: pathname from userland | |
2511 | * @flags: lookup flags | |
2512 | * @path: pointer to container to hold result | |
2513 | * | |
2514 | * A umount is a special case for path walking. We're not actually interested | |
2515 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2516 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2517 | * and avoid revalidating the last component. | |
2518 | * | |
2519 | * Returns 0 and populates "path" on success. | |
2520 | */ | |
2521 | int | |
197df04c | 2522 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2523 | struct path *path) |
2524 | { | |
cbaab2db | 2525 | return filename_mountpoint(dfd, getname(name), path, flags); |
8033426e JL |
2526 | } |
2527 | ||
2d864651 AV |
2528 | int |
2529 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2530 | unsigned int flags) | |
2531 | { | |
cbaab2db | 2532 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
2d864651 AV |
2533 | } |
2534 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2535 | ||
cbdf35bc | 2536 | int __check_sticky(struct inode *dir, struct inode *inode) |
1da177e4 | 2537 | { |
8e96e3b7 | 2538 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2539 | |
8e96e3b7 | 2540 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2541 | return 0; |
8e96e3b7 | 2542 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2543 | return 0; |
23adbe12 | 2544 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 | 2545 | } |
cbdf35bc | 2546 | EXPORT_SYMBOL(__check_sticky); |
1da177e4 LT |
2547 | |
2548 | /* | |
2549 | * Check whether we can remove a link victim from directory dir, check | |
2550 | * whether the type of victim is right. | |
2551 | * 1. We can't do it if dir is read-only (done in permission()) | |
2552 | * 2. We should have write and exec permissions on dir | |
2553 | * 3. We can't remove anything from append-only dir | |
2554 | * 4. We can't do anything with immutable dir (done in permission()) | |
2555 | * 5. If the sticky bit on dir is set we should either | |
2556 | * a. be owner of dir, or | |
2557 | * b. be owner of victim, or | |
2558 | * c. have CAP_FOWNER capability | |
2559 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2560 | * links pointing to it. | |
be494dcc EB |
2561 | * 7. If the victim has an unknown uid or gid we can't change the inode. |
2562 | * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2563 | * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2564 | * 10. We can't remove a root or mountpoint. | |
2565 | * 11. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1da177e4 LT |
2566 | * nfs_async_unlink(). |
2567 | */ | |
b18825a7 | 2568 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2569 | { |
63afdfc7 | 2570 | struct inode *inode = d_backing_inode(victim); |
1da177e4 LT |
2571 | int error; |
2572 | ||
b18825a7 | 2573 | if (d_is_negative(victim)) |
1da177e4 | 2574 | return -ENOENT; |
b18825a7 | 2575 | BUG_ON(!inode); |
1da177e4 LT |
2576 | |
2577 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2578 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2579 | |
f419a2e3 | 2580 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2581 | if (error) |
2582 | return error; | |
2583 | if (IS_APPEND(dir)) | |
2584 | return -EPERM; | |
b18825a7 DH |
2585 | |
2586 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
be494dcc | 2587 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) |
1da177e4 LT |
2588 | return -EPERM; |
2589 | if (isdir) { | |
44b1d530 | 2590 | if (!d_is_dir(victim)) |
1da177e4 LT |
2591 | return -ENOTDIR; |
2592 | if (IS_ROOT(victim)) | |
2593 | return -EBUSY; | |
44b1d530 | 2594 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2595 | return -EISDIR; |
2596 | if (IS_DEADDIR(dir)) | |
2597 | return -ENOENT; | |
2598 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2599 | return -EBUSY; | |
2600 | return 0; | |
2601 | } | |
2602 | ||
2603 | /* Check whether we can create an object with dentry child in directory | |
2604 | * dir. | |
2605 | * 1. We can't do it if child already exists (open has special treatment for | |
2606 | * this case, but since we are inlined it's OK) | |
2607 | * 2. We can't do it if dir is read-only (done in permission()) | |
b95f0b70 EB |
2608 | * 3. We can't do it if the fs can't represent the fsuid or fsgid. |
2609 | * 4. We should have write and exec permissions on dir | |
2610 | * 5. We can't do it if dir is immutable (done in permission()) | |
1da177e4 | 2611 | */ |
a95164d9 | 2612 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2613 | { |
b95f0b70 | 2614 | struct user_namespace *s_user_ns; |
14e972b4 | 2615 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2616 | if (child->d_inode) |
2617 | return -EEXIST; | |
2618 | if (IS_DEADDIR(dir)) | |
2619 | return -ENOENT; | |
b95f0b70 EB |
2620 | s_user_ns = dir->i_sb->s_user_ns; |
2621 | if (!kuid_has_mapping(s_user_ns, current_fsuid()) || | |
2622 | !kgid_has_mapping(s_user_ns, current_fsgid())) | |
2623 | return -EOVERFLOW; | |
f419a2e3 | 2624 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2625 | } |
2626 | ||
1da177e4 LT |
2627 | /* |
2628 | * p1 and p2 should be directories on the same fs. | |
2629 | */ | |
2630 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2631 | { | |
2632 | struct dentry *p; | |
2633 | ||
2634 | if (p1 == p2) { | |
f2eace23 | 2635 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2636 | return NULL; |
2637 | } | |
2638 | ||
a11f3a05 | 2639 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2640 | |
e2761a11 OH |
2641 | p = d_ancestor(p2, p1); |
2642 | if (p) { | |
2643 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2644 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2645 | return p; | |
1da177e4 LT |
2646 | } |
2647 | ||
e2761a11 OH |
2648 | p = d_ancestor(p1, p2); |
2649 | if (p) { | |
2650 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2651 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2652 | return p; | |
1da177e4 LT |
2653 | } |
2654 | ||
f2eace23 | 2655 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
d1b72cc6 | 2656 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); |
1da177e4 LT |
2657 | return NULL; |
2658 | } | |
4d359507 | 2659 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2660 | |
2661 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2662 | { | |
1b1dcc1b | 2663 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2664 | if (p1 != p2) { |
1b1dcc1b | 2665 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2666 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2667 | } |
2668 | } | |
4d359507 | 2669 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2670 | |
4acdaf27 | 2671 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2672 | bool want_excl) |
1da177e4 | 2673 | { |
a95164d9 | 2674 | int error = may_create(dir, dentry); |
1da177e4 LT |
2675 | if (error) |
2676 | return error; | |
2677 | ||
acfa4380 | 2678 | if (!dir->i_op->create) |
1da177e4 LT |
2679 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2680 | mode &= S_IALLUGO; | |
2681 | mode |= S_IFREG; | |
2682 | error = security_inode_create(dir, dentry, mode); | |
2683 | if (error) | |
2684 | return error; | |
312b63fb | 2685 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2686 | if (!error) |
f38aa942 | 2687 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2688 | return error; |
2689 | } | |
4d359507 | 2690 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2691 | |
73d049a4 | 2692 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2693 | { |
3fb64190 | 2694 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2695 | struct inode *inode = dentry->d_inode; |
2696 | int error; | |
2697 | ||
bcda7652 AV |
2698 | /* O_PATH? */ |
2699 | if (!acc_mode) | |
2700 | return 0; | |
2701 | ||
1da177e4 LT |
2702 | if (!inode) |
2703 | return -ENOENT; | |
2704 | ||
c8fe8f30 CH |
2705 | switch (inode->i_mode & S_IFMT) { |
2706 | case S_IFLNK: | |
1da177e4 | 2707 | return -ELOOP; |
c8fe8f30 CH |
2708 | case S_IFDIR: |
2709 | if (acc_mode & MAY_WRITE) | |
2710 | return -EISDIR; | |
2711 | break; | |
2712 | case S_IFBLK: | |
2713 | case S_IFCHR: | |
3fb64190 | 2714 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2715 | return -EACCES; |
c8fe8f30 CH |
2716 | /*FALLTHRU*/ |
2717 | case S_IFIFO: | |
2718 | case S_IFSOCK: | |
1da177e4 | 2719 | flag &= ~O_TRUNC; |
c8fe8f30 | 2720 | break; |
4a3fd211 | 2721 | } |
b41572e9 | 2722 | |
3fb64190 | 2723 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2724 | if (error) |
2725 | return error; | |
6146f0d5 | 2726 | |
1da177e4 LT |
2727 | /* |
2728 | * An append-only file must be opened in append mode for writing. | |
2729 | */ | |
2730 | if (IS_APPEND(inode)) { | |
8737c930 | 2731 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2732 | return -EPERM; |
1da177e4 | 2733 | if (flag & O_TRUNC) |
7715b521 | 2734 | return -EPERM; |
1da177e4 LT |
2735 | } |
2736 | ||
2737 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2738 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2739 | return -EPERM; |
1da177e4 | 2740 | |
f3c7691e | 2741 | return 0; |
7715b521 | 2742 | } |
1da177e4 | 2743 | |
e1181ee6 | 2744 | static int handle_truncate(struct file *filp) |
7715b521 | 2745 | { |
e1181ee6 | 2746 | struct path *path = &filp->f_path; |
7715b521 AV |
2747 | struct inode *inode = path->dentry->d_inode; |
2748 | int error = get_write_access(inode); | |
2749 | if (error) | |
2750 | return error; | |
2751 | /* | |
2752 | * Refuse to truncate files with mandatory locks held on them. | |
2753 | */ | |
d7a06983 | 2754 | error = locks_verify_locked(filp); |
7715b521 | 2755 | if (!error) |
ea0d3ab2 | 2756 | error = security_path_truncate(path); |
7715b521 AV |
2757 | if (!error) { |
2758 | error = do_truncate(path->dentry, 0, | |
2759 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2760 | filp); |
7715b521 AV |
2761 | } |
2762 | put_write_access(inode); | |
acd0c935 | 2763 | return error; |
1da177e4 LT |
2764 | } |
2765 | ||
d57999e1 DH |
2766 | static inline int open_to_namei_flags(int flag) |
2767 | { | |
8a5e929d AV |
2768 | if ((flag & O_ACCMODE) == 3) |
2769 | flag--; | |
d57999e1 DH |
2770 | return flag; |
2771 | } | |
2772 | ||
d18e9008 MS |
2773 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2774 | { | |
2775 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2776 | if (error) | |
2777 | return error; | |
2778 | ||
2779 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2780 | if (error) | |
2781 | return error; | |
2782 | ||
2783 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2784 | } | |
2785 | ||
1acf0af9 DH |
2786 | /* |
2787 | * Attempt to atomically look up, create and open a file from a negative | |
2788 | * dentry. | |
2789 | * | |
2790 | * Returns 0 if successful. The file will have been created and attached to | |
2791 | * @file by the filesystem calling finish_open(). | |
2792 | * | |
2793 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2794 | * caller will need to perform the open themselves. @path will have been | |
2795 | * updated to point to the new dentry. This may be negative. | |
2796 | * | |
2797 | * Returns an error code otherwise. | |
2798 | */ | |
2675a4eb AV |
2799 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2800 | struct path *path, struct file *file, | |
2801 | const struct open_flags *op, | |
64894cf8 | 2802 | bool got_write, bool need_lookup, |
2675a4eb | 2803 | int *opened) |
d18e9008 MS |
2804 | { |
2805 | struct inode *dir = nd->path.dentry->d_inode; | |
2806 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2807 | umode_t mode; | |
2808 | int error; | |
2809 | int acc_mode; | |
d18e9008 MS |
2810 | int create_error = 0; |
2811 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
116cc022 | 2812 | bool excl; |
d18e9008 MS |
2813 | |
2814 | BUG_ON(dentry->d_inode); | |
2815 | ||
2816 | /* Don't create child dentry for a dead directory. */ | |
2817 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2818 | error = -ENOENT; |
d18e9008 MS |
2819 | goto out; |
2820 | } | |
2821 | ||
62b259d8 | 2822 | mode = op->mode; |
d18e9008 MS |
2823 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2824 | mode &= ~current_umask(); | |
2825 | ||
116cc022 MS |
2826 | excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); |
2827 | if (excl) | |
d18e9008 | 2828 | open_flag &= ~O_TRUNC; |
d18e9008 MS |
2829 | |
2830 | /* | |
2831 | * Checking write permission is tricky, bacuse we don't know if we are | |
2832 | * going to actually need it: O_CREAT opens should work as long as the | |
2833 | * file exists. But checking existence breaks atomicity. The trick is | |
2834 | * to check access and if not granted clear O_CREAT from the flags. | |
2835 | * | |
2836 | * Another problem is returing the "right" error value (e.g. for an | |
2837 | * O_EXCL open we want to return EEXIST not EROFS). | |
2838 | */ | |
64894cf8 AV |
2839 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2840 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2841 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2842 | /* |
2843 | * No O_CREATE -> atomicity not a requirement -> fall | |
2844 | * back to lookup + open | |
2845 | */ | |
2846 | goto no_open; | |
2847 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2848 | /* Fall back and fail with the right error */ | |
64894cf8 | 2849 | create_error = -EROFS; |
d18e9008 MS |
2850 | goto no_open; |
2851 | } else { | |
2852 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2853 | create_error = -EROFS; |
d18e9008 MS |
2854 | open_flag &= ~O_CREAT; |
2855 | } | |
2856 | } | |
2857 | ||
2858 | if (open_flag & O_CREAT) { | |
38227f78 | 2859 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2860 | if (error) { |
2861 | create_error = error; | |
2862 | if (open_flag & O_EXCL) | |
2863 | goto no_open; | |
2864 | open_flag &= ~O_CREAT; | |
2865 | } | |
2866 | } | |
2867 | ||
2868 | if (nd->flags & LOOKUP_DIRECTORY) | |
2869 | open_flag |= O_DIRECTORY; | |
2870 | ||
30d90494 AV |
2871 | file->f_path.dentry = DENTRY_NOT_SET; |
2872 | file->f_path.mnt = nd->path.mnt; | |
2873 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2874 | opened); |
d9585277 | 2875 | if (error < 0) { |
d9585277 AV |
2876 | if (create_error && error == -ENOENT) |
2877 | error = create_error; | |
d18e9008 MS |
2878 | goto out; |
2879 | } | |
2880 | ||
d9585277 | 2881 | if (error) { /* returned 1, that is */ |
30d90494 | 2882 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2883 | error = -EIO; |
d18e9008 MS |
2884 | goto out; |
2885 | } | |
30d90494 | 2886 | if (file->f_path.dentry) { |
d18e9008 | 2887 | dput(dentry); |
30d90494 | 2888 | dentry = file->f_path.dentry; |
d18e9008 | 2889 | } |
03da633a AV |
2890 | if (*opened & FILE_CREATED) |
2891 | fsnotify_create(dir, dentry); | |
2892 | if (!dentry->d_inode) { | |
2893 | WARN_ON(*opened & FILE_CREATED); | |
2894 | if (create_error) { | |
2895 | error = create_error; | |
2896 | goto out; | |
2897 | } | |
2898 | } else { | |
2899 | if (excl && !(*opened & FILE_CREATED)) { | |
2900 | error = -EEXIST; | |
2901 | goto out; | |
2902 | } | |
62b2ce96 | 2903 | } |
d18e9008 MS |
2904 | goto looked_up; |
2905 | } | |
2906 | ||
2907 | /* | |
2908 | * We didn't have the inode before the open, so check open permission | |
2909 | * here. | |
2910 | */ | |
03da633a AV |
2911 | acc_mode = op->acc_mode; |
2912 | if (*opened & FILE_CREATED) { | |
2913 | WARN_ON(!(open_flag & O_CREAT)); | |
2914 | fsnotify_create(dir, dentry); | |
2915 | acc_mode = MAY_OPEN; | |
2916 | } | |
2675a4eb AV |
2917 | error = may_open(&file->f_path, acc_mode, open_flag); |
2918 | if (error) | |
2919 | fput(file); | |
d18e9008 MS |
2920 | |
2921 | out: | |
2922 | dput(dentry); | |
2675a4eb | 2923 | return error; |
d18e9008 | 2924 | |
d18e9008 MS |
2925 | no_open: |
2926 | if (need_lookup) { | |
72bd866a | 2927 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2928 | if (IS_ERR(dentry)) |
2675a4eb | 2929 | return PTR_ERR(dentry); |
75a6552a AV |
2930 | } |
2931 | if (create_error && !dentry->d_inode) { | |
2932 | error = create_error; | |
2933 | goto out; | |
d18e9008 MS |
2934 | } |
2935 | looked_up: | |
2936 | path->dentry = dentry; | |
2937 | path->mnt = nd->path.mnt; | |
2675a4eb | 2938 | return 1; |
d18e9008 MS |
2939 | } |
2940 | ||
d58ffd35 | 2941 | /* |
1acf0af9 | 2942 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2943 | * |
2944 | * Must be called with i_mutex held on parent. | |
2945 | * | |
1acf0af9 DH |
2946 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2947 | * opened. In this case the file will be returned attached to @file. | |
2948 | * | |
2949 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2950 | * and creations will have been performed and the dentry returned in @path will | |
2951 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2952 | * specified then a negative dentry may be returned. | |
2953 | * | |
2954 | * An error code is returned otherwise. | |
2955 | * | |
2956 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2957 | * cleared otherwise prior to returning. | |
d58ffd35 | 2958 | */ |
2675a4eb AV |
2959 | static int lookup_open(struct nameidata *nd, struct path *path, |
2960 | struct file *file, | |
2961 | const struct open_flags *op, | |
64894cf8 | 2962 | bool got_write, int *opened) |
d58ffd35 MS |
2963 | { |
2964 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2965 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2966 | struct dentry *dentry; |
2967 | int error; | |
54ef4872 | 2968 | bool need_lookup; |
d58ffd35 | 2969 | |
47237687 | 2970 | *opened &= ~FILE_CREATED; |
201f956e | 2971 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2972 | if (IS_ERR(dentry)) |
2675a4eb | 2973 | return PTR_ERR(dentry); |
d58ffd35 | 2974 | |
d18e9008 MS |
2975 | /* Cached positive dentry: will open in f_op->open */ |
2976 | if (!need_lookup && dentry->d_inode) | |
2977 | goto out_no_open; | |
2978 | ||
2979 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2980 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2981 | need_lookup, opened); |
d18e9008 MS |
2982 | } |
2983 | ||
54ef4872 MS |
2984 | if (need_lookup) { |
2985 | BUG_ON(dentry->d_inode); | |
2986 | ||
72bd866a | 2987 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2988 | if (IS_ERR(dentry)) |
2675a4eb | 2989 | return PTR_ERR(dentry); |
54ef4872 MS |
2990 | } |
2991 | ||
d58ffd35 MS |
2992 | /* Negative dentry, just create the file */ |
2993 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2994 | umode_t mode = op->mode; | |
2995 | if (!IS_POSIXACL(dir->d_inode)) | |
2996 | mode &= ~current_umask(); | |
2997 | /* | |
2998 | * This write is needed to ensure that a | |
2999 | * rw->ro transition does not occur between | |
3000 | * the time when the file is created and when | |
3001 | * a permanent write count is taken through | |
015c3bbc | 3002 | * the 'struct file' in finish_open(). |
d58ffd35 | 3003 | */ |
64894cf8 AV |
3004 | if (!got_write) { |
3005 | error = -EROFS; | |
d58ffd35 | 3006 | goto out_dput; |
64894cf8 | 3007 | } |
47237687 | 3008 | *opened |= FILE_CREATED; |
d58ffd35 MS |
3009 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
3010 | if (error) | |
3011 | goto out_dput; | |
312b63fb AV |
3012 | error = vfs_create(dir->d_inode, dentry, mode, |
3013 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
3014 | if (error) |
3015 | goto out_dput; | |
3016 | } | |
d18e9008 | 3017 | out_no_open: |
d58ffd35 MS |
3018 | path->dentry = dentry; |
3019 | path->mnt = nd->path.mnt; | |
2675a4eb | 3020 | return 1; |
d58ffd35 MS |
3021 | |
3022 | out_dput: | |
3023 | dput(dentry); | |
2675a4eb | 3024 | return error; |
d58ffd35 MS |
3025 | } |
3026 | ||
31e6b01f | 3027 | /* |
fe2d35ff | 3028 | * Handle the last step of open() |
31e6b01f | 3029 | */ |
896475d5 | 3030 | static int do_last(struct nameidata *nd, |
2675a4eb | 3031 | struct file *file, const struct open_flags *op, |
76ae2a5a | 3032 | int *opened) |
fb1cc555 | 3033 | { |
a1e28038 | 3034 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 3035 | int open_flag = op->open_flag; |
77d660a8 | 3036 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 3037 | bool got_write = false; |
bcda7652 | 3038 | int acc_mode = op->acc_mode; |
254cf582 | 3039 | unsigned seq; |
a1eb3315 | 3040 | struct inode *inode; |
16b1c1cd | 3041 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
896475d5 | 3042 | struct path path; |
16b1c1cd | 3043 | bool retried = false; |
16c2cd71 | 3044 | int error; |
1f36f774 | 3045 | |
c3e380b0 AV |
3046 | nd->flags &= ~LOOKUP_PARENT; |
3047 | nd->flags |= op->intent; | |
3048 | ||
bc77daa7 | 3049 | if (nd->last_type != LAST_NORM) { |
fe2d35ff | 3050 | error = handle_dots(nd, nd->last_type); |
deb106c6 | 3051 | if (unlikely(error)) |
2675a4eb | 3052 | return error; |
e83db167 | 3053 | goto finish_open; |
1f36f774 | 3054 | } |
67ee3ad2 | 3055 | |
ca344a89 | 3056 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
3057 | if (nd->last.name[nd->last.len]) |
3058 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
3059 | /* we _can_ be in RCU mode here */ | |
254cf582 | 3060 | error = lookup_fast(nd, &path, &inode, &seq); |
71574865 MS |
3061 | if (likely(!error)) |
3062 | goto finish_lookup; | |
3063 | ||
3064 | if (error < 0) | |
deb106c6 | 3065 | return error; |
71574865 MS |
3066 | |
3067 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
3068 | } else { |
3069 | /* create side of things */ | |
3070 | /* | |
3071 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
3072 | * has been cleared when we got to the last component we are | |
3073 | * about to look up | |
3074 | */ | |
3075 | error = complete_walk(nd); | |
e8bb73df | 3076 | if (error) |
2675a4eb | 3077 | return error; |
fe2d35ff | 3078 | |
76ae2a5a | 3079 | audit_inode(nd->name, dir, LOOKUP_PARENT); |
b6183df7 | 3080 | /* trailing slashes? */ |
deb106c6 AV |
3081 | if (unlikely(nd->last.name[nd->last.len])) |
3082 | return -EISDIR; | |
b6183df7 | 3083 | } |
a2c36b45 | 3084 | |
16b1c1cd | 3085 | retry_lookup: |
64894cf8 AV |
3086 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
3087 | error = mnt_want_write(nd->path.mnt); | |
3088 | if (!error) | |
3089 | got_write = true; | |
3090 | /* | |
3091 | * do _not_ fail yet - we might not need that or fail with | |
3092 | * a different error; let lookup_open() decide; we'll be | |
3093 | * dropping this one anyway. | |
3094 | */ | |
3095 | } | |
a1e28038 | 3096 | mutex_lock(&dir->d_inode->i_mutex); |
896475d5 | 3097 | error = lookup_open(nd, &path, file, op, got_write, opened); |
d58ffd35 | 3098 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 3099 | |
2675a4eb AV |
3100 | if (error <= 0) { |
3101 | if (error) | |
d18e9008 MS |
3102 | goto out; |
3103 | ||
47237687 | 3104 | if ((*opened & FILE_CREATED) || |
496ad9aa | 3105 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 3106 | will_truncate = false; |
d18e9008 | 3107 | |
76ae2a5a | 3108 | audit_inode(nd->name, file->f_path.dentry, 0); |
d18e9008 MS |
3109 | goto opened; |
3110 | } | |
fb1cc555 | 3111 | |
47237687 | 3112 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 3113 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 3114 | open_flag &= ~O_TRUNC; |
77d660a8 | 3115 | will_truncate = false; |
bcda7652 | 3116 | acc_mode = MAY_OPEN; |
896475d5 | 3117 | path_to_nameidata(&path, nd); |
e83db167 | 3118 | goto finish_open_created; |
fb1cc555 AV |
3119 | } |
3120 | ||
3121 | /* | |
3134f37e | 3122 | * create/update audit record if it already exists. |
fb1cc555 | 3123 | */ |
896475d5 | 3124 | if (d_is_positive(path.dentry)) |
76ae2a5a | 3125 | audit_inode(nd->name, path.dentry, 0); |
fb1cc555 | 3126 | |
d18e9008 MS |
3127 | /* |
3128 | * If atomic_open() acquired write access it is dropped now due to | |
3129 | * possible mount and symlink following (this might be optimized away if | |
3130 | * necessary...) | |
3131 | */ | |
64894cf8 | 3132 | if (got_write) { |
d18e9008 | 3133 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3134 | got_write = false; |
d18e9008 MS |
3135 | } |
3136 | ||
deb106c6 AV |
3137 | if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { |
3138 | path_to_nameidata(&path, nd); | |
3139 | return -EEXIST; | |
3140 | } | |
fb1cc555 | 3141 | |
756daf26 | 3142 | error = follow_managed(&path, nd); |
deb106c6 AV |
3143 | if (unlikely(error < 0)) |
3144 | return error; | |
a3fbbde7 | 3145 | |
decf3400 | 3146 | BUG_ON(nd->flags & LOOKUP_RCU); |
254cf582 | 3147 | seq = 0; /* out of RCU mode, so the value doesn't matter */ |
deb106c6 | 3148 | if (unlikely(d_is_negative(path.dentry))) { |
896475d5 | 3149 | path_to_nameidata(&path, nd); |
deb106c6 | 3150 | return -ENOENT; |
54c33e7f | 3151 | } |
32b9b145 | 3152 | inode = d_backing_inode(path.dentry); |
766c4cbf | 3153 | finish_lookup: |
d63ff28f AV |
3154 | if (nd->depth) |
3155 | put_link(nd); | |
181548c0 AV |
3156 | error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, |
3157 | inode, seq); | |
deb106c6 | 3158 | if (unlikely(error)) |
d63ff28f | 3159 | return error; |
fb1cc555 | 3160 | |
896475d5 AV |
3161 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { |
3162 | path_to_nameidata(&path, nd); | |
16b1c1cd MS |
3163 | } else { |
3164 | save_parent.dentry = nd->path.dentry; | |
896475d5 AV |
3165 | save_parent.mnt = mntget(path.mnt); |
3166 | nd->path.dentry = path.dentry; | |
16b1c1cd MS |
3167 | |
3168 | } | |
decf3400 | 3169 | nd->inode = inode; |
254cf582 | 3170 | nd->seq = seq; |
a3fbbde7 | 3171 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3172 | finish_open: |
a3fbbde7 | 3173 | error = complete_walk(nd); |
16b1c1cd MS |
3174 | if (error) { |
3175 | path_put(&save_parent); | |
2675a4eb | 3176 | return error; |
16b1c1cd | 3177 | } |
76ae2a5a | 3178 | audit_inode(nd->name, nd->path.dentry, 0); |
6a2721a3 AV |
3179 | if (unlikely(d_is_symlink(nd->path.dentry)) && !(open_flag & O_PATH)) { |
3180 | error = -ELOOP; | |
3181 | goto out; | |
3182 | } | |
fb1cc555 | 3183 | error = -EISDIR; |
44b1d530 | 3184 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3185 | goto out; |
af2f5542 | 3186 | error = -ENOTDIR; |
44b1d530 | 3187 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3188 | goto out; |
4bbcbd3b | 3189 | if (!d_is_reg(nd->path.dentry)) |
77d660a8 | 3190 | will_truncate = false; |
6c0d46c4 | 3191 | |
0f9d1a10 AV |
3192 | if (will_truncate) { |
3193 | error = mnt_want_write(nd->path.mnt); | |
3194 | if (error) | |
2675a4eb | 3195 | goto out; |
64894cf8 | 3196 | got_write = true; |
0f9d1a10 | 3197 | } |
e83db167 | 3198 | finish_open_created: |
bcda7652 | 3199 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 3200 | if (error) |
2675a4eb | 3201 | goto out; |
4aa7c634 MS |
3202 | |
3203 | BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ | |
3204 | error = vfs_open(&nd->path, file, current_cred()); | |
3205 | if (!error) { | |
3206 | *opened |= FILE_OPENED; | |
3207 | } else { | |
30d90494 | 3208 | if (error == -EOPENSTALE) |
f60dc3db | 3209 | goto stale_open; |
015c3bbc | 3210 | goto out; |
f60dc3db | 3211 | } |
a8277b9b | 3212 | opened: |
2675a4eb | 3213 | error = open_check_o_direct(file); |
015c3bbc MS |
3214 | if (error) |
3215 | goto exit_fput; | |
3034a146 | 3216 | error = ima_file_check(file, op->acc_mode, *opened); |
aa4caadb MS |
3217 | if (error) |
3218 | goto exit_fput; | |
3219 | ||
3220 | if (will_truncate) { | |
2675a4eb | 3221 | error = handle_truncate(file); |
aa4caadb MS |
3222 | if (error) |
3223 | goto exit_fput; | |
0f9d1a10 | 3224 | } |
ca344a89 | 3225 | out: |
09c56bd9 AV |
3226 | if (unlikely(error > 0)) { |
3227 | WARN_ON(1); | |
3228 | error = -EINVAL; | |
3229 | } | |
64894cf8 | 3230 | if (got_write) |
0f9d1a10 | 3231 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3232 | path_put(&save_parent); |
2675a4eb | 3233 | return error; |
fb1cc555 | 3234 | |
015c3bbc | 3235 | exit_fput: |
2675a4eb AV |
3236 | fput(file); |
3237 | goto out; | |
015c3bbc | 3238 | |
f60dc3db MS |
3239 | stale_open: |
3240 | /* If no saved parent or already retried then can't retry */ | |
3241 | if (!save_parent.dentry || retried) | |
3242 | goto out; | |
3243 | ||
3244 | BUG_ON(save_parent.dentry != dir); | |
3245 | path_put(&nd->path); | |
3246 | nd->path = save_parent; | |
3247 | nd->inode = dir->d_inode; | |
3248 | save_parent.mnt = NULL; | |
3249 | save_parent.dentry = NULL; | |
64894cf8 | 3250 | if (got_write) { |
f60dc3db | 3251 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3252 | got_write = false; |
f60dc3db MS |
3253 | } |
3254 | retried = true; | |
3255 | goto retry_lookup; | |
fb1cc555 AV |
3256 | } |
3257 | ||
c8a53ee5 | 3258 | static int do_tmpfile(struct nameidata *nd, unsigned flags, |
60545d0d AV |
3259 | const struct open_flags *op, |
3260 | struct file *file, int *opened) | |
3261 | { | |
3262 | static const struct qstr name = QSTR_INIT("/", 1); | |
625b6d10 | 3263 | struct dentry *child; |
60545d0d | 3264 | struct inode *dir; |
625b6d10 | 3265 | struct path path; |
c8a53ee5 | 3266 | int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); |
60545d0d AV |
3267 | if (unlikely(error)) |
3268 | return error; | |
625b6d10 | 3269 | error = mnt_want_write(path.mnt); |
60545d0d AV |
3270 | if (unlikely(error)) |
3271 | goto out; | |
625b6d10 | 3272 | dir = path.dentry->d_inode; |
60545d0d | 3273 | /* we want directory to be writable */ |
625b6d10 | 3274 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
60545d0d AV |
3275 | if (error) |
3276 | goto out2; | |
60545d0d AV |
3277 | if (!dir->i_op->tmpfile) { |
3278 | error = -EOPNOTSUPP; | |
3279 | goto out2; | |
3280 | } | |
625b6d10 | 3281 | child = d_alloc(path.dentry, &name); |
60545d0d AV |
3282 | if (unlikely(!child)) { |
3283 | error = -ENOMEM; | |
3284 | goto out2; | |
3285 | } | |
625b6d10 AV |
3286 | dput(path.dentry); |
3287 | path.dentry = child; | |
3288 | error = dir->i_op->tmpfile(dir, child, op->mode); | |
60545d0d AV |
3289 | if (error) |
3290 | goto out2; | |
c8a53ee5 | 3291 | audit_inode(nd->name, child, 0); |
69a91c23 | 3292 | /* Don't check for other permissions, the inode was just created */ |
625b6d10 | 3293 | error = may_open(&path, MAY_OPEN, op->open_flag); |
60545d0d AV |
3294 | if (error) |
3295 | goto out2; | |
625b6d10 AV |
3296 | file->f_path.mnt = path.mnt; |
3297 | error = finish_open(file, child, NULL, opened); | |
60545d0d AV |
3298 | if (error) |
3299 | goto out2; | |
3300 | error = open_check_o_direct(file); | |
f4e0c30c | 3301 | if (error) { |
60545d0d | 3302 | fput(file); |
f4e0c30c AV |
3303 | } else if (!(op->open_flag & O_EXCL)) { |
3304 | struct inode *inode = file_inode(file); | |
3305 | spin_lock(&inode->i_lock); | |
3306 | inode->i_state |= I_LINKABLE; | |
3307 | spin_unlock(&inode->i_lock); | |
3308 | } | |
60545d0d | 3309 | out2: |
625b6d10 | 3310 | mnt_drop_write(path.mnt); |
60545d0d | 3311 | out: |
625b6d10 | 3312 | path_put(&path); |
60545d0d AV |
3313 | return error; |
3314 | } | |
3315 | ||
c8a53ee5 AV |
3316 | static struct file *path_openat(struct nameidata *nd, |
3317 | const struct open_flags *op, unsigned flags) | |
1da177e4 | 3318 | { |
368ee9ba | 3319 | const char *s; |
30d90494 | 3320 | struct file *file; |
47237687 | 3321 | int opened = 0; |
13aab428 | 3322 | int error; |
31e6b01f | 3323 | |
30d90494 | 3324 | file = get_empty_filp(); |
1afc99be AV |
3325 | if (IS_ERR(file)) |
3326 | return file; | |
31e6b01f | 3327 | |
30d90494 | 3328 | file->f_flags = op->open_flag; |
31e6b01f | 3329 | |
bb458c64 | 3330 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
c8a53ee5 | 3331 | error = do_tmpfile(nd, flags, op, file, &opened); |
f15133df | 3332 | goto out2; |
60545d0d AV |
3333 | } |
3334 | ||
c8a53ee5 | 3335 | s = path_init(nd, flags); |
368ee9ba AV |
3336 | if (IS_ERR(s)) { |
3337 | put_filp(file); | |
3338 | return ERR_CAST(s); | |
3339 | } | |
3bdba28b | 3340 | while (!(error = link_path_walk(s, nd)) && |
76ae2a5a | 3341 | (error = do_last(nd, file, op, &opened)) > 0) { |
73d049a4 | 3342 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
3bdba28b AV |
3343 | s = trailing_symlink(nd); |
3344 | if (IS_ERR(s)) { | |
3345 | error = PTR_ERR(s); | |
2675a4eb | 3346 | break; |
3bdba28b | 3347 | } |
806b681c | 3348 | } |
deb106c6 | 3349 | terminate_walk(nd); |
f15133df | 3350 | out2: |
2675a4eb AV |
3351 | if (!(opened & FILE_OPENED)) { |
3352 | BUG_ON(!error); | |
30d90494 | 3353 | put_filp(file); |
16b1c1cd | 3354 | } |
2675a4eb AV |
3355 | if (unlikely(error)) { |
3356 | if (error == -EOPENSTALE) { | |
3357 | if (flags & LOOKUP_RCU) | |
3358 | error = -ECHILD; | |
3359 | else | |
3360 | error = -ESTALE; | |
3361 | } | |
3362 | file = ERR_PTR(error); | |
3363 | } | |
3364 | return file; | |
1da177e4 LT |
3365 | } |
3366 | ||
669abf4e | 3367 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3368 | const struct open_flags *op) |
13aab428 | 3369 | { |
9883d185 | 3370 | struct nameidata nd; |
f9652e10 | 3371 | int flags = op->lookup_flags; |
13aab428 AV |
3372 | struct file *filp; |
3373 | ||
9883d185 | 3374 | set_nameidata(&nd, dfd, pathname); |
c8a53ee5 | 3375 | filp = path_openat(&nd, op, flags | LOOKUP_RCU); |
13aab428 | 3376 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
c8a53ee5 | 3377 | filp = path_openat(&nd, op, flags); |
13aab428 | 3378 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
c8a53ee5 | 3379 | filp = path_openat(&nd, op, flags | LOOKUP_REVAL); |
9883d185 | 3380 | restore_nameidata(); |
13aab428 AV |
3381 | return filp; |
3382 | } | |
3383 | ||
73d049a4 | 3384 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3385 | const char *name, const struct open_flags *op) |
73d049a4 | 3386 | { |
9883d185 | 3387 | struct nameidata nd; |
73d049a4 | 3388 | struct file *file; |
51689104 | 3389 | struct filename *filename; |
f9652e10 | 3390 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3391 | |
3392 | nd.root.mnt = mnt; | |
3393 | nd.root.dentry = dentry; | |
3394 | ||
b18825a7 | 3395 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3396 | return ERR_PTR(-ELOOP); |
3397 | ||
51689104 | 3398 | filename = getname_kernel(name); |
a1c83681 | 3399 | if (IS_ERR(filename)) |
51689104 PM |
3400 | return ERR_CAST(filename); |
3401 | ||
9883d185 | 3402 | set_nameidata(&nd, -1, filename); |
c8a53ee5 | 3403 | file = path_openat(&nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3404 | if (unlikely(file == ERR_PTR(-ECHILD))) |
c8a53ee5 | 3405 | file = path_openat(&nd, op, flags); |
73d049a4 | 3406 | if (unlikely(file == ERR_PTR(-ESTALE))) |
c8a53ee5 | 3407 | file = path_openat(&nd, op, flags | LOOKUP_REVAL); |
9883d185 | 3408 | restore_nameidata(); |
51689104 | 3409 | putname(filename); |
73d049a4 AV |
3410 | return file; |
3411 | } | |
3412 | ||
fa14a0b8 | 3413 | static struct dentry *filename_create(int dfd, struct filename *name, |
1ac12b4b | 3414 | struct path *path, unsigned int lookup_flags) |
1da177e4 | 3415 | { |
c663e5d8 | 3416 | struct dentry *dentry = ERR_PTR(-EEXIST); |
391172c4 AV |
3417 | struct qstr last; |
3418 | int type; | |
c30dabfe | 3419 | int err2; |
1ac12b4b JL |
3420 | int error; |
3421 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3422 | ||
3423 | /* | |
3424 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3425 | * other flags passed in are ignored! | |
3426 | */ | |
3427 | lookup_flags &= LOOKUP_REVAL; | |
3428 | ||
5c31b6ce AV |
3429 | name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); |
3430 | if (IS_ERR(name)) | |
3431 | return ERR_CAST(name); | |
1da177e4 | 3432 | |
c663e5d8 CH |
3433 | /* |
3434 | * Yucky last component or no last component at all? | |
3435 | * (foo/., foo/.., /////) | |
3436 | */ | |
5c31b6ce | 3437 | if (unlikely(type != LAST_NORM)) |
ed75e95d | 3438 | goto out; |
c663e5d8 | 3439 | |
c30dabfe | 3440 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
391172c4 | 3441 | err2 = mnt_want_write(path->mnt); |
c663e5d8 CH |
3442 | /* |
3443 | * Do the final lookup. | |
3444 | */ | |
391172c4 AV |
3445 | lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
3446 | mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
3447 | dentry = __lookup_hash(&last, path->dentry, lookup_flags); | |
1da177e4 | 3448 | if (IS_ERR(dentry)) |
a8104a9f | 3449 | goto unlock; |
c663e5d8 | 3450 | |
a8104a9f | 3451 | error = -EEXIST; |
b18825a7 | 3452 | if (d_is_positive(dentry)) |
a8104a9f | 3453 | goto fail; |
b18825a7 | 3454 | |
c663e5d8 CH |
3455 | /* |
3456 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3457 | * From the vfs_mknod() POV we just have a negative dentry - | |
3458 | * all is fine. Let's be bastards - you had / on the end, you've | |
3459 | * been asking for (non-existent) directory. -ENOENT for you. | |
3460 | */ | |
391172c4 | 3461 | if (unlikely(!is_dir && last.name[last.len])) { |
a8104a9f | 3462 | error = -ENOENT; |
ed75e95d | 3463 | goto fail; |
e9baf6e5 | 3464 | } |
c30dabfe JK |
3465 | if (unlikely(err2)) { |
3466 | error = err2; | |
a8104a9f | 3467 | goto fail; |
c30dabfe | 3468 | } |
181c37b6 | 3469 | putname(name); |
1da177e4 | 3470 | return dentry; |
1da177e4 | 3471 | fail: |
a8104a9f AV |
3472 | dput(dentry); |
3473 | dentry = ERR_PTR(error); | |
3474 | unlock: | |
391172c4 | 3475 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
c30dabfe | 3476 | if (!err2) |
391172c4 | 3477 | mnt_drop_write(path->mnt); |
ed75e95d | 3478 | out: |
391172c4 | 3479 | path_put(path); |
181c37b6 | 3480 | putname(name); |
1da177e4 LT |
3481 | return dentry; |
3482 | } | |
fa14a0b8 AV |
3483 | |
3484 | struct dentry *kern_path_create(int dfd, const char *pathname, | |
3485 | struct path *path, unsigned int lookup_flags) | |
3486 | { | |
181c37b6 AV |
3487 | return filename_create(dfd, getname_kernel(pathname), |
3488 | path, lookup_flags); | |
fa14a0b8 | 3489 | } |
dae6ad8f AV |
3490 | EXPORT_SYMBOL(kern_path_create); |
3491 | ||
921a1650 AV |
3492 | void done_path_create(struct path *path, struct dentry *dentry) |
3493 | { | |
3494 | dput(dentry); | |
3495 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3496 | mnt_drop_write(path->mnt); |
921a1650 AV |
3497 | path_put(path); |
3498 | } | |
3499 | EXPORT_SYMBOL(done_path_create); | |
3500 | ||
520ae687 | 3501 | inline struct dentry *user_path_create(int dfd, const char __user *pathname, |
1ac12b4b | 3502 | struct path *path, unsigned int lookup_flags) |
dae6ad8f | 3503 | { |
181c37b6 | 3504 | return filename_create(dfd, getname(pathname), path, lookup_flags); |
dae6ad8f AV |
3505 | } |
3506 | EXPORT_SYMBOL(user_path_create); | |
3507 | ||
1a67aafb | 3508 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3509 | { |
a95164d9 | 3510 | int error = may_create(dir, dentry); |
1da177e4 LT |
3511 | |
3512 | if (error) | |
3513 | return error; | |
3514 | ||
975d6b39 | 3515 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3516 | return -EPERM; |
3517 | ||
acfa4380 | 3518 | if (!dir->i_op->mknod) |
1da177e4 LT |
3519 | return -EPERM; |
3520 | ||
08ce5f16 SH |
3521 | error = devcgroup_inode_mknod(mode, dev); |
3522 | if (error) | |
3523 | return error; | |
3524 | ||
1da177e4 LT |
3525 | error = security_inode_mknod(dir, dentry, mode, dev); |
3526 | if (error) | |
3527 | return error; | |
3528 | ||
1da177e4 | 3529 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3530 | if (!error) |
f38aa942 | 3531 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3532 | return error; |
3533 | } | |
4d359507 | 3534 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3535 | |
f69aac00 | 3536 | static int may_mknod(umode_t mode) |
463c3197 DH |
3537 | { |
3538 | switch (mode & S_IFMT) { | |
3539 | case S_IFREG: | |
3540 | case S_IFCHR: | |
3541 | case S_IFBLK: | |
3542 | case S_IFIFO: | |
3543 | case S_IFSOCK: | |
3544 | case 0: /* zero mode translates to S_IFREG */ | |
3545 | return 0; | |
3546 | case S_IFDIR: | |
3547 | return -EPERM; | |
3548 | default: | |
3549 | return -EINVAL; | |
3550 | } | |
3551 | } | |
3552 | ||
8208a22b | 3553 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3554 | unsigned, dev) |
1da177e4 | 3555 | { |
2ad94ae6 | 3556 | struct dentry *dentry; |
dae6ad8f AV |
3557 | struct path path; |
3558 | int error; | |
972567f1 | 3559 | unsigned int lookup_flags = 0; |
1da177e4 | 3560 | |
8e4bfca1 AV |
3561 | error = may_mknod(mode); |
3562 | if (error) | |
3563 | return error; | |
972567f1 JL |
3564 | retry: |
3565 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3566 | if (IS_ERR(dentry)) |
3567 | return PTR_ERR(dentry); | |
2ad94ae6 | 3568 | |
dae6ad8f | 3569 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3570 | mode &= ~current_umask(); |
dae6ad8f | 3571 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3572 | if (error) |
a8104a9f | 3573 | goto out; |
463c3197 | 3574 | switch (mode & S_IFMT) { |
1da177e4 | 3575 | case 0: case S_IFREG: |
312b63fb | 3576 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3577 | break; |
3578 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3579 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3580 | new_decode_dev(dev)); |
3581 | break; | |
3582 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3583 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3584 | break; |
1da177e4 | 3585 | } |
a8104a9f | 3586 | out: |
921a1650 | 3587 | done_path_create(&path, dentry); |
972567f1 JL |
3588 | if (retry_estale(error, lookup_flags)) { |
3589 | lookup_flags |= LOOKUP_REVAL; | |
3590 | goto retry; | |
3591 | } | |
1da177e4 LT |
3592 | return error; |
3593 | } | |
3594 | ||
8208a22b | 3595 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3596 | { |
3597 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3598 | } | |
3599 | ||
18bb1db3 | 3600 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3601 | { |
a95164d9 | 3602 | int error = may_create(dir, dentry); |
8de52778 | 3603 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3604 | |
3605 | if (error) | |
3606 | return error; | |
3607 | ||
acfa4380 | 3608 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3609 | return -EPERM; |
3610 | ||
3611 | mode &= (S_IRWXUGO|S_ISVTX); | |
3612 | error = security_inode_mkdir(dir, dentry, mode); | |
3613 | if (error) | |
3614 | return error; | |
3615 | ||
8de52778 AV |
3616 | if (max_links && dir->i_nlink >= max_links) |
3617 | return -EMLINK; | |
3618 | ||
1da177e4 | 3619 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3620 | if (!error) |
f38aa942 | 3621 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3622 | return error; |
3623 | } | |
4d359507 | 3624 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3625 | |
a218d0fd | 3626 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3627 | { |
6902d925 | 3628 | struct dentry *dentry; |
dae6ad8f AV |
3629 | struct path path; |
3630 | int error; | |
b76d8b82 | 3631 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3632 | |
b76d8b82 JL |
3633 | retry: |
3634 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3635 | if (IS_ERR(dentry)) |
dae6ad8f | 3636 | return PTR_ERR(dentry); |
1da177e4 | 3637 | |
dae6ad8f | 3638 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3639 | mode &= ~current_umask(); |
dae6ad8f | 3640 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3641 | if (!error) |
3642 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3643 | done_path_create(&path, dentry); |
b76d8b82 JL |
3644 | if (retry_estale(error, lookup_flags)) { |
3645 | lookup_flags |= LOOKUP_REVAL; | |
3646 | goto retry; | |
3647 | } | |
1da177e4 LT |
3648 | return error; |
3649 | } | |
3650 | ||
a218d0fd | 3651 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3652 | { |
3653 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3654 | } | |
3655 | ||
1da177e4 | 3656 | /* |
a71905f0 | 3657 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3658 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3659 | * dentry, and if that is true (possibly after pruning the dcache), |
3660 | * then we drop the dentry now. | |
1da177e4 LT |
3661 | * |
3662 | * A low-level filesystem can, if it choses, legally | |
3663 | * do a | |
3664 | * | |
3665 | * if (!d_unhashed(dentry)) | |
3666 | * return -EBUSY; | |
3667 | * | |
3668 | * if it cannot handle the case of removing a directory | |
3669 | * that is still in use by something else.. | |
3670 | */ | |
3671 | void dentry_unhash(struct dentry *dentry) | |
3672 | { | |
dc168427 | 3673 | shrink_dcache_parent(dentry); |
1da177e4 | 3674 | spin_lock(&dentry->d_lock); |
98474236 | 3675 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3676 | __d_drop(dentry); |
3677 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 3678 | } |
4d359507 | 3679 | EXPORT_SYMBOL(dentry_unhash); |
1da177e4 LT |
3680 | |
3681 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3682 | { | |
3683 | int error = may_delete(dir, dentry, 1); | |
3684 | ||
3685 | if (error) | |
3686 | return error; | |
3687 | ||
acfa4380 | 3688 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3689 | return -EPERM; |
3690 | ||
1d2ef590 | 3691 | dget(dentry); |
1b1dcc1b | 3692 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3693 | |
3694 | error = -EBUSY; | |
7af1364f | 3695 | if (is_local_mountpoint(dentry)) |
912dbc15 SW |
3696 | goto out; |
3697 | ||
3698 | error = security_inode_rmdir(dir, dentry); | |
3699 | if (error) | |
3700 | goto out; | |
3701 | ||
3cebde24 | 3702 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3703 | error = dir->i_op->rmdir(dir, dentry); |
3704 | if (error) | |
3705 | goto out; | |
3706 | ||
3707 | dentry->d_inode->i_flags |= S_DEAD; | |
3708 | dont_mount(dentry); | |
8ed936b5 | 3709 | detach_mounts(dentry); |
912dbc15 SW |
3710 | |
3711 | out: | |
1b1dcc1b | 3712 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3713 | dput(dentry); |
912dbc15 | 3714 | if (!error) |
1da177e4 | 3715 | d_delete(dentry); |
1da177e4 LT |
3716 | return error; |
3717 | } | |
4d359507 | 3718 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3719 | |
5590ff0d | 3720 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3721 | { |
3722 | int error = 0; | |
91a27b2a | 3723 | struct filename *name; |
1da177e4 | 3724 | struct dentry *dentry; |
f5beed75 AV |
3725 | struct path path; |
3726 | struct qstr last; | |
3727 | int type; | |
c6ee9206 JL |
3728 | unsigned int lookup_flags = 0; |
3729 | retry: | |
f5beed75 AV |
3730 | name = user_path_parent(dfd, pathname, |
3731 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3732 | if (IS_ERR(name)) |
3733 | return PTR_ERR(name); | |
1da177e4 | 3734 | |
f5beed75 | 3735 | switch (type) { |
0612d9fb OH |
3736 | case LAST_DOTDOT: |
3737 | error = -ENOTEMPTY; | |
3738 | goto exit1; | |
3739 | case LAST_DOT: | |
3740 | error = -EINVAL; | |
3741 | goto exit1; | |
3742 | case LAST_ROOT: | |
3743 | error = -EBUSY; | |
3744 | goto exit1; | |
1da177e4 | 3745 | } |
0612d9fb | 3746 | |
f5beed75 | 3747 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3748 | if (error) |
3749 | goto exit1; | |
0612d9fb | 3750 | |
f5beed75 AV |
3751 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3752 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 | 3753 | error = PTR_ERR(dentry); |
6902d925 DH |
3754 | if (IS_ERR(dentry)) |
3755 | goto exit2; | |
e6bc45d6 TT |
3756 | if (!dentry->d_inode) { |
3757 | error = -ENOENT; | |
3758 | goto exit3; | |
3759 | } | |
f5beed75 | 3760 | error = security_path_rmdir(&path, dentry); |
be6d3e56 | 3761 | if (error) |
c30dabfe | 3762 | goto exit3; |
f5beed75 | 3763 | error = vfs_rmdir(path.dentry->d_inode, dentry); |
0622753b | 3764 | exit3: |
6902d925 DH |
3765 | dput(dentry); |
3766 | exit2: | |
f5beed75 AV |
3767 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
3768 | mnt_drop_write(path.mnt); | |
1da177e4 | 3769 | exit1: |
f5beed75 | 3770 | path_put(&path); |
1da177e4 | 3771 | putname(name); |
c6ee9206 JL |
3772 | if (retry_estale(error, lookup_flags)) { |
3773 | lookup_flags |= LOOKUP_REVAL; | |
3774 | goto retry; | |
3775 | } | |
1da177e4 LT |
3776 | return error; |
3777 | } | |
3778 | ||
3cdad428 | 3779 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3780 | { |
3781 | return do_rmdir(AT_FDCWD, pathname); | |
3782 | } | |
3783 | ||
b21996e3 BF |
3784 | /** |
3785 | * vfs_unlink - unlink a filesystem object | |
3786 | * @dir: parent directory | |
3787 | * @dentry: victim | |
3788 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3789 | * | |
3790 | * The caller must hold dir->i_mutex. | |
3791 | * | |
3792 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3793 | * return a reference to the inode in delegated_inode. The caller | |
3794 | * should then break the delegation on that inode and retry. Because | |
3795 | * breaking a delegation may take a long time, the caller should drop | |
3796 | * dir->i_mutex before doing so. | |
3797 | * | |
3798 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3799 | * be appropriate for callers that expect the underlying filesystem not | |
3800 | * to be NFS exported. | |
3801 | */ | |
3802 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3803 | { |
9accbb97 | 3804 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3805 | int error = may_delete(dir, dentry, 0); |
3806 | ||
3807 | if (error) | |
3808 | return error; | |
3809 | ||
acfa4380 | 3810 | if (!dir->i_op->unlink) |
1da177e4 LT |
3811 | return -EPERM; |
3812 | ||
9accbb97 | 3813 | mutex_lock(&target->i_mutex); |
8ed936b5 | 3814 | if (is_local_mountpoint(dentry)) |
1da177e4 LT |
3815 | error = -EBUSY; |
3816 | else { | |
3817 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3818 | if (!error) { |
5a14696c BF |
3819 | error = try_break_deleg(target, delegated_inode); |
3820 | if (error) | |
b21996e3 | 3821 | goto out; |
1da177e4 | 3822 | error = dir->i_op->unlink(dir, dentry); |
8ed936b5 | 3823 | if (!error) { |
d83c49f3 | 3824 | dont_mount(dentry); |
8ed936b5 EB |
3825 | detach_mounts(dentry); |
3826 | } | |
bec1052e | 3827 | } |
1da177e4 | 3828 | } |
b21996e3 | 3829 | out: |
9accbb97 | 3830 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3831 | |
3832 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3833 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 3834 | fsnotify_link_count(target); |
e234f35c | 3835 | d_delete(dentry); |
1da177e4 | 3836 | } |
0eeca283 | 3837 | |
1da177e4 LT |
3838 | return error; |
3839 | } | |
4d359507 | 3840 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
3841 | |
3842 | /* | |
3843 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3844 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3845 | * writeout happening, and we don't want to prevent access to the directory |
3846 | * while waiting on the I/O. | |
3847 | */ | |
5590ff0d | 3848 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3849 | { |
2ad94ae6 | 3850 | int error; |
91a27b2a | 3851 | struct filename *name; |
1da177e4 | 3852 | struct dentry *dentry; |
f5beed75 AV |
3853 | struct path path; |
3854 | struct qstr last; | |
3855 | int type; | |
1da177e4 | 3856 | struct inode *inode = NULL; |
b21996e3 | 3857 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
3858 | unsigned int lookup_flags = 0; |
3859 | retry: | |
f5beed75 AV |
3860 | name = user_path_parent(dfd, pathname, |
3861 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3862 | if (IS_ERR(name)) |
3863 | return PTR_ERR(name); | |
2ad94ae6 | 3864 | |
1da177e4 | 3865 | error = -EISDIR; |
f5beed75 | 3866 | if (type != LAST_NORM) |
1da177e4 | 3867 | goto exit1; |
0612d9fb | 3868 | |
f5beed75 | 3869 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3870 | if (error) |
3871 | goto exit1; | |
b21996e3 | 3872 | retry_deleg: |
f5beed75 AV |
3873 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3874 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 LT |
3875 | error = PTR_ERR(dentry); |
3876 | if (!IS_ERR(dentry)) { | |
3877 | /* Why not before? Because we want correct error value */ | |
f5beed75 | 3878 | if (last.name[last.len]) |
50338b88 | 3879 | goto slashes; |
1da177e4 | 3880 | inode = dentry->d_inode; |
b18825a7 | 3881 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
3882 | goto slashes; |
3883 | ihold(inode); | |
f5beed75 | 3884 | error = security_path_unlink(&path, dentry); |
be6d3e56 | 3885 | if (error) |
c30dabfe | 3886 | goto exit2; |
f5beed75 | 3887 | error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 3888 | exit2: |
1da177e4 LT |
3889 | dput(dentry); |
3890 | } | |
f5beed75 | 3891 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3892 | if (inode) |
3893 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
3894 | inode = NULL; |
3895 | if (delegated_inode) { | |
5a14696c | 3896 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
3897 | if (!error) |
3898 | goto retry_deleg; | |
3899 | } | |
f5beed75 | 3900 | mnt_drop_write(path.mnt); |
1da177e4 | 3901 | exit1: |
f5beed75 | 3902 | path_put(&path); |
1da177e4 | 3903 | putname(name); |
5d18f813 JL |
3904 | if (retry_estale(error, lookup_flags)) { |
3905 | lookup_flags |= LOOKUP_REVAL; | |
3906 | inode = NULL; | |
3907 | goto retry; | |
3908 | } | |
1da177e4 LT |
3909 | return error; |
3910 | ||
3911 | slashes: | |
b18825a7 DH |
3912 | if (d_is_negative(dentry)) |
3913 | error = -ENOENT; | |
44b1d530 | 3914 | else if (d_is_dir(dentry)) |
b18825a7 DH |
3915 | error = -EISDIR; |
3916 | else | |
3917 | error = -ENOTDIR; | |
1da177e4 LT |
3918 | goto exit2; |
3919 | } | |
3920 | ||
2e4d0924 | 3921 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3922 | { |
3923 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3924 | return -EINVAL; | |
3925 | ||
3926 | if (flag & AT_REMOVEDIR) | |
3927 | return do_rmdir(dfd, pathname); | |
3928 | ||
3929 | return do_unlinkat(dfd, pathname); | |
3930 | } | |
3931 | ||
3480b257 | 3932 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3933 | { |
3934 | return do_unlinkat(AT_FDCWD, pathname); | |
3935 | } | |
3936 | ||
db2e747b | 3937 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3938 | { |
a95164d9 | 3939 | int error = may_create(dir, dentry); |
1da177e4 LT |
3940 | |
3941 | if (error) | |
3942 | return error; | |
3943 | ||
acfa4380 | 3944 | if (!dir->i_op->symlink) |
1da177e4 LT |
3945 | return -EPERM; |
3946 | ||
3947 | error = security_inode_symlink(dir, dentry, oldname); | |
3948 | if (error) | |
3949 | return error; | |
3950 | ||
1da177e4 | 3951 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3952 | if (!error) |
f38aa942 | 3953 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3954 | return error; |
3955 | } | |
4d359507 | 3956 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 3957 | |
2e4d0924 HC |
3958 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3959 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3960 | { |
2ad94ae6 | 3961 | int error; |
91a27b2a | 3962 | struct filename *from; |
6902d925 | 3963 | struct dentry *dentry; |
dae6ad8f | 3964 | struct path path; |
f46d3567 | 3965 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3966 | |
3967 | from = getname(oldname); | |
2ad94ae6 | 3968 | if (IS_ERR(from)) |
1da177e4 | 3969 | return PTR_ERR(from); |
f46d3567 JL |
3970 | retry: |
3971 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3972 | error = PTR_ERR(dentry); |
3973 | if (IS_ERR(dentry)) | |
dae6ad8f | 3974 | goto out_putname; |
6902d925 | 3975 | |
91a27b2a | 3976 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3977 | if (!error) |
91a27b2a | 3978 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3979 | done_path_create(&path, dentry); |
f46d3567 JL |
3980 | if (retry_estale(error, lookup_flags)) { |
3981 | lookup_flags |= LOOKUP_REVAL; | |
3982 | goto retry; | |
3983 | } | |
6902d925 | 3984 | out_putname: |
1da177e4 LT |
3985 | putname(from); |
3986 | return error; | |
3987 | } | |
3988 | ||
3480b257 | 3989 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3990 | { |
3991 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3992 | } | |
3993 | ||
146a8595 BF |
3994 | /** |
3995 | * vfs_link - create a new link | |
3996 | * @old_dentry: object to be linked | |
3997 | * @dir: new parent | |
3998 | * @new_dentry: where to create the new link | |
3999 | * @delegated_inode: returns inode needing a delegation break | |
4000 | * | |
4001 | * The caller must hold dir->i_mutex | |
4002 | * | |
4003 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
4004 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
4005 | * inode in delegated_inode. The caller should then break the delegation | |
4006 | * and retry. Because breaking a delegation may take a long time, the | |
4007 | * caller should drop the i_mutex before doing so. | |
4008 | * | |
4009 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4010 | * be appropriate for callers that expect the underlying filesystem not | |
4011 | * to be NFS exported. | |
4012 | */ | |
4013 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
4014 | { |
4015 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 4016 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
4017 | int error; |
4018 | ||
4019 | if (!inode) | |
4020 | return -ENOENT; | |
4021 | ||
a95164d9 | 4022 | error = may_create(dir, new_dentry); |
1da177e4 LT |
4023 | if (error) |
4024 | return error; | |
4025 | ||
4026 | if (dir->i_sb != inode->i_sb) | |
4027 | return -EXDEV; | |
4028 | ||
4029 | /* | |
4030 | * A link to an append-only or immutable file cannot be created. | |
4031 | */ | |
4032 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
4033 | return -EPERM; | |
be494dcc EB |
4034 | /* |
4035 | * Updating the link count will likely cause i_uid and i_gid to | |
4036 | * be writen back improperly if their true value is unknown to | |
4037 | * the vfs. | |
4038 | */ | |
4039 | if (HAS_UNMAPPED_ID(inode)) | |
4040 | return -EPERM; | |
acfa4380 | 4041 | if (!dir->i_op->link) |
1da177e4 | 4042 | return -EPERM; |
7e79eedb | 4043 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
4044 | return -EPERM; |
4045 | ||
4046 | error = security_inode_link(old_dentry, dir, new_dentry); | |
4047 | if (error) | |
4048 | return error; | |
4049 | ||
7e79eedb | 4050 | mutex_lock(&inode->i_mutex); |
aae8a97d | 4051 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 4052 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 4053 | error = -ENOENT; |
8de52778 AV |
4054 | else if (max_links && inode->i_nlink >= max_links) |
4055 | error = -EMLINK; | |
146a8595 BF |
4056 | else { |
4057 | error = try_break_deleg(inode, delegated_inode); | |
4058 | if (!error) | |
4059 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
4060 | } | |
f4e0c30c AV |
4061 | |
4062 | if (!error && (inode->i_state & I_LINKABLE)) { | |
4063 | spin_lock(&inode->i_lock); | |
4064 | inode->i_state &= ~I_LINKABLE; | |
4065 | spin_unlock(&inode->i_lock); | |
4066 | } | |
7e79eedb | 4067 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 4068 | if (!error) |
7e79eedb | 4069 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
4070 | return error; |
4071 | } | |
4d359507 | 4072 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
4073 | |
4074 | /* | |
4075 | * Hardlinks are often used in delicate situations. We avoid | |
4076 | * security-related surprises by not following symlinks on the | |
4077 | * newname. --KAB | |
4078 | * | |
4079 | * We don't follow them on the oldname either to be compatible | |
4080 | * with linux 2.0, and to avoid hard-linking to directories | |
4081 | * and other special files. --ADM | |
4082 | */ | |
2e4d0924 HC |
4083 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
4084 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
4085 | { |
4086 | struct dentry *new_dentry; | |
dae6ad8f | 4087 | struct path old_path, new_path; |
146a8595 | 4088 | struct inode *delegated_inode = NULL; |
11a7b371 | 4089 | int how = 0; |
1da177e4 | 4090 | int error; |
1da177e4 | 4091 | |
11a7b371 | 4092 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 4093 | return -EINVAL; |
11a7b371 | 4094 | /* |
f0cc6ffb LT |
4095 | * To use null names we require CAP_DAC_READ_SEARCH |
4096 | * This ensures that not everyone will be able to create | |
4097 | * handlink using the passed filedescriptor. | |
11a7b371 | 4098 | */ |
f0cc6ffb LT |
4099 | if (flags & AT_EMPTY_PATH) { |
4100 | if (!capable(CAP_DAC_READ_SEARCH)) | |
4101 | return -ENOENT; | |
11a7b371 | 4102 | how = LOOKUP_EMPTY; |
f0cc6ffb | 4103 | } |
11a7b371 AK |
4104 | |
4105 | if (flags & AT_SYMLINK_FOLLOW) | |
4106 | how |= LOOKUP_FOLLOW; | |
442e31ca | 4107 | retry: |
11a7b371 | 4108 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 4109 | if (error) |
2ad94ae6 AV |
4110 | return error; |
4111 | ||
442e31ca JL |
4112 | new_dentry = user_path_create(newdfd, newname, &new_path, |
4113 | (how & LOOKUP_REVAL)); | |
1da177e4 | 4114 | error = PTR_ERR(new_dentry); |
6902d925 | 4115 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
4116 | goto out; |
4117 | ||
4118 | error = -EXDEV; | |
4119 | if (old_path.mnt != new_path.mnt) | |
4120 | goto out_dput; | |
800179c9 KC |
4121 | error = may_linkat(&old_path); |
4122 | if (unlikely(error)) | |
4123 | goto out_dput; | |
dae6ad8f | 4124 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 4125 | if (error) |
a8104a9f | 4126 | goto out_dput; |
146a8595 | 4127 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 4128 | out_dput: |
921a1650 | 4129 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
4130 | if (delegated_inode) { |
4131 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
4132 | if (!error) { |
4133 | path_put(&old_path); | |
146a8595 | 4134 | goto retry; |
d22e6338 | 4135 | } |
146a8595 | 4136 | } |
442e31ca | 4137 | if (retry_estale(error, how)) { |
d22e6338 | 4138 | path_put(&old_path); |
442e31ca JL |
4139 | how |= LOOKUP_REVAL; |
4140 | goto retry; | |
4141 | } | |
1da177e4 | 4142 | out: |
2d8f3038 | 4143 | path_put(&old_path); |
1da177e4 LT |
4144 | |
4145 | return error; | |
4146 | } | |
4147 | ||
3480b257 | 4148 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4149 | { |
c04030e1 | 4150 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4151 | } |
4152 | ||
bc27027a MS |
4153 | /** |
4154 | * vfs_rename - rename a filesystem object | |
4155 | * @old_dir: parent of source | |
4156 | * @old_dentry: source | |
4157 | * @new_dir: parent of destination | |
4158 | * @new_dentry: destination | |
4159 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4160 | * @flags: rename flags |
bc27027a MS |
4161 | * |
4162 | * The caller must hold multiple mutexes--see lock_rename()). | |
4163 | * | |
4164 | * If vfs_rename discovers a delegation in need of breaking at either | |
4165 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4166 | * reference to the inode in delegated_inode. The caller should then | |
4167 | * break the delegation and retry. Because breaking a delegation may | |
4168 | * take a long time, the caller should drop all locks before doing | |
4169 | * so. | |
4170 | * | |
4171 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4172 | * be appropriate for callers that expect the underlying filesystem not | |
4173 | * to be NFS exported. | |
4174 | * | |
1da177e4 LT |
4175 | * The worst of all namespace operations - renaming directory. "Perverted" |
4176 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4177 | * Problems: | |
d03b29a2 | 4178 | * a) we can get into loop creation. |
1da177e4 LT |
4179 | * b) race potential - two innocent renames can create a loop together. |
4180 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4181 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4182 | * story. |
6cedba89 BF |
4183 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4184 | * and source (if it is not a directory). | |
1b1dcc1b | 4185 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4186 | * whether the target exists). Solution: try to be smart with locking |
4187 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4188 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4189 | * move will be locked. Thus we can rank directories by the tree |
4190 | * (ancestors first) and rank all non-directories after them. | |
4191 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4192 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4193 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4194 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4195 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4196 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4197 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4198 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4199 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4200 | * locking]. |
4201 | */ | |
bc27027a MS |
4202 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4203 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4204 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4205 | { |
bc27027a MS |
4206 | int error; |
4207 | bool is_dir = d_is_dir(old_dentry); | |
bc27027a | 4208 | struct inode *source = old_dentry->d_inode; |
9055cba7 | 4209 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4210 | bool new_is_dir = false; |
4211 | unsigned max_links = new_dir->i_sb->s_max_links; | |
626f7c23 | 4212 | struct name_snapshot old_name; |
bc27027a | 4213 | |
1f17780e MS |
4214 | /* |
4215 | * Check source == target. | |
4216 | * On overlayfs need to look at underlying inodes. | |
4217 | */ | |
4218 | if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) | |
bc27027a MS |
4219 | return 0; |
4220 | ||
4221 | error = may_delete(old_dir, old_dentry, is_dir); | |
4222 | if (error) | |
4223 | return error; | |
4224 | ||
da1ce067 | 4225 | if (!target) { |
bc27027a | 4226 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4227 | } else { |
4228 | new_is_dir = d_is_dir(new_dentry); | |
4229 | ||
4230 | if (!(flags & RENAME_EXCHANGE)) | |
4231 | error = may_delete(new_dir, new_dentry, is_dir); | |
4232 | else | |
4233 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4234 | } | |
bc27027a MS |
4235 | if (error) |
4236 | return error; | |
4237 | ||
7177a9c4 | 4238 | if (!old_dir->i_op->rename && !old_dir->i_op->rename2) |
bc27027a | 4239 | return -EPERM; |
1da177e4 | 4240 | |
520c8b16 MS |
4241 | if (flags && !old_dir->i_op->rename2) |
4242 | return -EINVAL; | |
4243 | ||
1da177e4 LT |
4244 | /* |
4245 | * If we are going to change the parent - check write permissions, | |
4246 | * we'll need to flip '..'. | |
4247 | */ | |
da1ce067 MS |
4248 | if (new_dir != old_dir) { |
4249 | if (is_dir) { | |
4250 | error = inode_permission(source, MAY_WRITE); | |
4251 | if (error) | |
4252 | return error; | |
4253 | } | |
4254 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4255 | error = inode_permission(target, MAY_WRITE); | |
4256 | if (error) | |
4257 | return error; | |
4258 | } | |
1da177e4 LT |
4259 | } |
4260 | ||
0b3974eb MS |
4261 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4262 | flags); | |
1da177e4 LT |
4263 | if (error) |
4264 | return error; | |
4265 | ||
626f7c23 | 4266 | take_dentry_name_snapshot(&old_name, old_dentry); |
1d2ef590 | 4267 | dget(new_dentry); |
da1ce067 | 4268 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4269 | lock_two_nondirectories(source, target); |
4270 | else if (target) | |
1b1dcc1b | 4271 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
4272 | |
4273 | error = -EBUSY; | |
7af1364f | 4274 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
9055cba7 SW |
4275 | goto out; |
4276 | ||
da1ce067 | 4277 | if (max_links && new_dir != old_dir) { |
bc27027a | 4278 | error = -EMLINK; |
da1ce067 | 4279 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4280 | goto out; |
da1ce067 MS |
4281 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4282 | old_dir->i_nlink >= max_links) | |
4283 | goto out; | |
4284 | } | |
4285 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4286 | shrink_dcache_parent(new_dentry); | |
4287 | if (!is_dir) { | |
bc27027a | 4288 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4289 | if (error) |
4290 | goto out; | |
da1ce067 MS |
4291 | } |
4292 | if (target && !new_is_dir) { | |
4293 | error = try_break_deleg(target, delegated_inode); | |
4294 | if (error) | |
4295 | goto out; | |
8e6d782c | 4296 | } |
7177a9c4 | 4297 | if (!old_dir->i_op->rename2) { |
520c8b16 MS |
4298 | error = old_dir->i_op->rename(old_dir, old_dentry, |
4299 | new_dir, new_dentry); | |
4300 | } else { | |
7177a9c4 | 4301 | WARN_ON(old_dir->i_op->rename != NULL); |
520c8b16 MS |
4302 | error = old_dir->i_op->rename2(old_dir, old_dentry, |
4303 | new_dir, new_dentry, flags); | |
4304 | } | |
51892bbb SW |
4305 | if (error) |
4306 | goto out; | |
4307 | ||
da1ce067 | 4308 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4309 | if (is_dir) |
4310 | target->i_flags |= S_DEAD; | |
51892bbb | 4311 | dont_mount(new_dentry); |
8ed936b5 | 4312 | detach_mounts(new_dentry); |
bc27027a | 4313 | } |
da1ce067 MS |
4314 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4315 | if (!(flags & RENAME_EXCHANGE)) | |
4316 | d_move(old_dentry, new_dentry); | |
4317 | else | |
4318 | d_exchange(old_dentry, new_dentry); | |
4319 | } | |
51892bbb | 4320 | out: |
da1ce067 | 4321 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4322 | unlock_two_nondirectories(source, target); |
4323 | else if (target) | |
4324 | mutex_unlock(&target->i_mutex); | |
1da177e4 | 4325 | dput(new_dentry); |
da1ce067 | 4326 | if (!error) { |
626f7c23 | 4327 | fsnotify_move(old_dir, new_dir, old_name.name, is_dir, |
da1ce067 MS |
4328 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4329 | if (flags & RENAME_EXCHANGE) { | |
4330 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4331 | new_is_dir, NULL, new_dentry); | |
4332 | } | |
4333 | } | |
626f7c23 | 4334 | release_dentry_name_snapshot(&old_name); |
0eeca283 | 4335 | |
1da177e4 LT |
4336 | return error; |
4337 | } | |
4d359507 | 4338 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4339 | |
520c8b16 MS |
4340 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4341 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4342 | { |
2ad94ae6 AV |
4343 | struct dentry *old_dentry, *new_dentry; |
4344 | struct dentry *trap; | |
f5beed75 AV |
4345 | struct path old_path, new_path; |
4346 | struct qstr old_last, new_last; | |
4347 | int old_type, new_type; | |
8e6d782c | 4348 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4349 | struct filename *from; |
4350 | struct filename *to; | |
f5beed75 | 4351 | unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; |
c6a94284 | 4352 | bool should_retry = false; |
2ad94ae6 | 4353 | int error; |
520c8b16 | 4354 | |
0d7a8555 | 4355 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
da1ce067 MS |
4356 | return -EINVAL; |
4357 | ||
0d7a8555 MS |
4358 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
4359 | (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4360 | return -EINVAL; |
4361 | ||
0d7a8555 MS |
4362 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
4363 | return -EPERM; | |
4364 | ||
f5beed75 AV |
4365 | if (flags & RENAME_EXCHANGE) |
4366 | target_flags = 0; | |
4367 | ||
c6a94284 | 4368 | retry: |
f5beed75 AV |
4369 | from = user_path_parent(olddfd, oldname, |
4370 | &old_path, &old_last, &old_type, lookup_flags); | |
91a27b2a JL |
4371 | if (IS_ERR(from)) { |
4372 | error = PTR_ERR(from); | |
1da177e4 | 4373 | goto exit; |
91a27b2a | 4374 | } |
1da177e4 | 4375 | |
f5beed75 AV |
4376 | to = user_path_parent(newdfd, newname, |
4377 | &new_path, &new_last, &new_type, lookup_flags); | |
91a27b2a JL |
4378 | if (IS_ERR(to)) { |
4379 | error = PTR_ERR(to); | |
1da177e4 | 4380 | goto exit1; |
91a27b2a | 4381 | } |
1da177e4 LT |
4382 | |
4383 | error = -EXDEV; | |
f5beed75 | 4384 | if (old_path.mnt != new_path.mnt) |
1da177e4 LT |
4385 | goto exit2; |
4386 | ||
1da177e4 | 4387 | error = -EBUSY; |
f5beed75 | 4388 | if (old_type != LAST_NORM) |
1da177e4 LT |
4389 | goto exit2; |
4390 | ||
0a7c3937 MS |
4391 | if (flags & RENAME_NOREPLACE) |
4392 | error = -EEXIST; | |
f5beed75 | 4393 | if (new_type != LAST_NORM) |
1da177e4 LT |
4394 | goto exit2; |
4395 | ||
f5beed75 | 4396 | error = mnt_want_write(old_path.mnt); |
c30dabfe JK |
4397 | if (error) |
4398 | goto exit2; | |
4399 | ||
8e6d782c | 4400 | retry_deleg: |
f5beed75 | 4401 | trap = lock_rename(new_path.dentry, old_path.dentry); |
1da177e4 | 4402 | |
f5beed75 | 4403 | old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); |
1da177e4 LT |
4404 | error = PTR_ERR(old_dentry); |
4405 | if (IS_ERR(old_dentry)) | |
4406 | goto exit3; | |
4407 | /* source must exist */ | |
4408 | error = -ENOENT; | |
b18825a7 | 4409 | if (d_is_negative(old_dentry)) |
1da177e4 | 4410 | goto exit4; |
f5beed75 | 4411 | new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); |
0a7c3937 MS |
4412 | error = PTR_ERR(new_dentry); |
4413 | if (IS_ERR(new_dentry)) | |
4414 | goto exit4; | |
4415 | error = -EEXIST; | |
4416 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4417 | goto exit5; | |
da1ce067 MS |
4418 | if (flags & RENAME_EXCHANGE) { |
4419 | error = -ENOENT; | |
4420 | if (d_is_negative(new_dentry)) | |
4421 | goto exit5; | |
4422 | ||
4423 | if (!d_is_dir(new_dentry)) { | |
4424 | error = -ENOTDIR; | |
f5beed75 | 4425 | if (new_last.name[new_last.len]) |
da1ce067 MS |
4426 | goto exit5; |
4427 | } | |
4428 | } | |
1da177e4 | 4429 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4430 | if (!d_is_dir(old_dentry)) { |
1da177e4 | 4431 | error = -ENOTDIR; |
f5beed75 | 4432 | if (old_last.name[old_last.len]) |
0a7c3937 | 4433 | goto exit5; |
f5beed75 | 4434 | if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) |
0a7c3937 | 4435 | goto exit5; |
1da177e4 LT |
4436 | } |
4437 | /* source should not be ancestor of target */ | |
4438 | error = -EINVAL; | |
4439 | if (old_dentry == trap) | |
0a7c3937 | 4440 | goto exit5; |
1da177e4 | 4441 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4442 | if (!(flags & RENAME_EXCHANGE)) |
4443 | error = -ENOTEMPTY; | |
1da177e4 LT |
4444 | if (new_dentry == trap) |
4445 | goto exit5; | |
4446 | ||
f5beed75 AV |
4447 | error = security_path_rename(&old_path, old_dentry, |
4448 | &new_path, new_dentry, flags); | |
be6d3e56 | 4449 | if (error) |
c30dabfe | 4450 | goto exit5; |
f5beed75 AV |
4451 | error = vfs_rename(old_path.dentry->d_inode, old_dentry, |
4452 | new_path.dentry->d_inode, new_dentry, | |
520c8b16 | 4453 | &delegated_inode, flags); |
1da177e4 LT |
4454 | exit5: |
4455 | dput(new_dentry); | |
4456 | exit4: | |
4457 | dput(old_dentry); | |
4458 | exit3: | |
f5beed75 | 4459 | unlock_rename(new_path.dentry, old_path.dentry); |
8e6d782c BF |
4460 | if (delegated_inode) { |
4461 | error = break_deleg_wait(&delegated_inode); | |
4462 | if (!error) | |
4463 | goto retry_deleg; | |
4464 | } | |
f5beed75 | 4465 | mnt_drop_write(old_path.mnt); |
1da177e4 | 4466 | exit2: |
c6a94284 JL |
4467 | if (retry_estale(error, lookup_flags)) |
4468 | should_retry = true; | |
f5beed75 | 4469 | path_put(&new_path); |
2ad94ae6 | 4470 | putname(to); |
1da177e4 | 4471 | exit1: |
f5beed75 | 4472 | path_put(&old_path); |
1da177e4 | 4473 | putname(from); |
c6a94284 JL |
4474 | if (should_retry) { |
4475 | should_retry = false; | |
4476 | lookup_flags |= LOOKUP_REVAL; | |
4477 | goto retry; | |
4478 | } | |
2ad94ae6 | 4479 | exit: |
1da177e4 LT |
4480 | return error; |
4481 | } | |
4482 | ||
520c8b16 MS |
4483 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4484 | int, newdfd, const char __user *, newname) | |
4485 | { | |
4486 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4487 | } | |
4488 | ||
a26eab24 | 4489 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4490 | { |
520c8b16 | 4491 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4492 | } |
4493 | ||
787fb6bc MS |
4494 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
4495 | { | |
4496 | int error = may_create(dir, dentry); | |
4497 | if (error) | |
4498 | return error; | |
4499 | ||
4500 | if (!dir->i_op->mknod) | |
4501 | return -EPERM; | |
4502 | ||
4503 | return dir->i_op->mknod(dir, dentry, | |
4504 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
4505 | } | |
4506 | EXPORT_SYMBOL(vfs_whiteout); | |
4507 | ||
5d826c84 | 4508 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4509 | { |
5d826c84 | 4510 | int len = PTR_ERR(link); |
1da177e4 LT |
4511 | if (IS_ERR(link)) |
4512 | goto out; | |
4513 | ||
4514 | len = strlen(link); | |
4515 | if (len > (unsigned) buflen) | |
4516 | len = buflen; | |
4517 | if (copy_to_user(buffer, link, len)) | |
4518 | len = -EFAULT; | |
4519 | out: | |
4520 | return len; | |
4521 | } | |
5d826c84 | 4522 | EXPORT_SYMBOL(readlink_copy); |
1da177e4 LT |
4523 | |
4524 | /* | |
4525 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4526 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4527 | * using) it for any given inode is up to filesystem. | |
4528 | */ | |
4529 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4530 | { | |
cc314eef | 4531 | void *cookie; |
5f2c4179 AV |
4532 | struct inode *inode = d_inode(dentry); |
4533 | const char *link = inode->i_link; | |
694a1764 | 4534 | int res; |
cc314eef | 4535 | |
d4dee48b | 4536 | if (!link) { |
5f2c4179 | 4537 | link = inode->i_op->follow_link(dentry, &cookie); |
d4dee48b AV |
4538 | if (IS_ERR(link)) |
4539 | return PTR_ERR(link); | |
4540 | } | |
680baacb | 4541 | res = readlink_copy(buffer, buflen, link); |
5f2c4179 AV |
4542 | if (inode->i_op->put_link) |
4543 | inode->i_op->put_link(inode, cookie); | |
694a1764 | 4544 | return res; |
1da177e4 | 4545 | } |
4d359507 | 4546 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4547 | |
1da177e4 LT |
4548 | /* get the link contents into pagecache */ |
4549 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4550 | { | |
ebd09abb DG |
4551 | char *kaddr; |
4552 | struct page *page; | |
1da177e4 | 4553 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4554 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4555 | if (IS_ERR(page)) |
6fe6900e | 4556 | return (char*)page; |
1da177e4 | 4557 | *ppage = page; |
ebd09abb DG |
4558 | kaddr = kmap(page); |
4559 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4560 | return kaddr; | |
1da177e4 LT |
4561 | } |
4562 | ||
4563 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4564 | { | |
4565 | struct page *page = NULL; | |
5d826c84 | 4566 | int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); |
1da177e4 LT |
4567 | if (page) { |
4568 | kunmap(page); | |
4569 | page_cache_release(page); | |
4570 | } | |
4571 | return res; | |
4572 | } | |
4d359507 | 4573 | EXPORT_SYMBOL(page_readlink); |
1da177e4 | 4574 | |
6e77137b | 4575 | const char *page_follow_link_light(struct dentry *dentry, void **cookie) |
1da177e4 | 4576 | { |
cc314eef | 4577 | struct page *page = NULL; |
680baacb AV |
4578 | char *res = page_getlink(dentry, &page); |
4579 | if (!IS_ERR(res)) | |
4580 | *cookie = page; | |
4581 | return res; | |
1da177e4 | 4582 | } |
4d359507 | 4583 | EXPORT_SYMBOL(page_follow_link_light); |
1da177e4 | 4584 | |
5f2c4179 | 4585 | void page_put_link(struct inode *unused, void *cookie) |
1da177e4 | 4586 | { |
cc314eef | 4587 | struct page *page = cookie; |
680baacb AV |
4588 | kunmap(page); |
4589 | page_cache_release(page); | |
1da177e4 | 4590 | } |
4d359507 | 4591 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4592 | |
54566b2c NP |
4593 | /* |
4594 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4595 | */ | |
4596 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4597 | { |
4598 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4599 | struct page *page; |
afddba49 | 4600 | void *fsdata; |
beb497ab | 4601 | int err; |
1da177e4 | 4602 | char *kaddr; |
54566b2c NP |
4603 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4604 | if (nofs) | |
4605 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4606 | |
7e53cac4 | 4607 | retry: |
afddba49 | 4608 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4609 | flags, &page, &fsdata); |
1da177e4 | 4610 | if (err) |
afddba49 NP |
4611 | goto fail; |
4612 | ||
e8e3c3d6 | 4613 | kaddr = kmap_atomic(page); |
1da177e4 | 4614 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4615 | kunmap_atomic(kaddr); |
afddba49 NP |
4616 | |
4617 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4618 | page, fsdata); | |
1da177e4 LT |
4619 | if (err < 0) |
4620 | goto fail; | |
afddba49 NP |
4621 | if (err < len-1) |
4622 | goto retry; | |
4623 | ||
1da177e4 LT |
4624 | mark_inode_dirty(inode); |
4625 | return 0; | |
1da177e4 LT |
4626 | fail: |
4627 | return err; | |
4628 | } | |
4d359507 | 4629 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4630 | |
0adb25d2 KK |
4631 | int page_symlink(struct inode *inode, const char *symname, int len) |
4632 | { | |
4633 | return __page_symlink(inode, symname, len, | |
c62d2555 | 4634 | !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); |
0adb25d2 | 4635 | } |
4d359507 | 4636 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4637 | |
92e1d5be | 4638 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4639 | .readlink = generic_readlink, |
4640 | .follow_link = page_follow_link_light, | |
4641 | .put_link = page_put_link, | |
4642 | }; | |
1da177e4 | 4643 | EXPORT_SYMBOL(page_symlink_inode_operations); |