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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> |
1da177e4 LT |
37 | #include <asm/uaccess.h> |
38 | ||
e81e3f4d | 39 | #include "internal.h" |
c7105365 | 40 | #include "mount.h" |
e81e3f4d | 41 | |
1da177e4 LT |
42 | /* [Feb-1997 T. Schoebel-Theuer] |
43 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
44 | * were necessary because of omirr. The reason is that omirr needs | |
45 | * to know the _real_ pathname, not the user-supplied one, in case | |
46 | * of symlinks (and also when transname replacements occur). | |
47 | * | |
48 | * The new code replaces the old recursive symlink resolution with | |
49 | * an iterative one (in case of non-nested symlink chains). It does | |
50 | * this with calls to <fs>_follow_link(). | |
51 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
52 | * replaced with a single function lookup_dentry() that can handle all | |
53 | * the special cases of the former code. | |
54 | * | |
55 | * With the new dcache, the pathname is stored at each inode, at least as | |
56 | * long as the refcount of the inode is positive. As a side effect, the | |
57 | * size of the dcache depends on the inode cache and thus is dynamic. | |
58 | * | |
59 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
60 | * resolution to correspond with current state of the code. | |
61 | * | |
62 | * Note that the symlink resolution is not *completely* iterative. | |
63 | * There is still a significant amount of tail- and mid- recursion in | |
64 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
65 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
66 | * may return different results than <fs>_follow_link(). Many virtual | |
67 | * filesystems (including /proc) exhibit this behavior. | |
68 | */ | |
69 | ||
70 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
71 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
72 | * and the name already exists in form of a symlink, try to create the new | |
73 | * name indicated by the symlink. The old code always complained that the | |
74 | * name already exists, due to not following the symlink even if its target | |
75 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 76 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
77 | * |
78 | * I don't know which semantics is the right one, since I have no access | |
79 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
80 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
81 | * "old" one. Personally, I think the new semantics is much more logical. | |
82 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
83 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
84 | * and in the old Linux semantics. | |
85 | */ | |
86 | ||
87 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
88 | * semantics. See the comments in "open_namei" and "do_link" below. | |
89 | * | |
90 | * [10-Sep-98 Alan Modra] Another symlink change. | |
91 | */ | |
92 | ||
93 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
94 | * inside the path - always follow. | |
95 | * in the last component in creation/removal/renaming - never follow. | |
96 | * if LOOKUP_FOLLOW passed - follow. | |
97 | * if the pathname has trailing slashes - follow. | |
98 | * otherwise - don't follow. | |
99 | * (applied in that order). | |
100 | * | |
101 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
102 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
103 | * During the 2.4 we need to fix the userland stuff depending on it - | |
104 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
105 | * XEmacs seems to be relying on it... | |
106 | */ | |
107 | /* | |
108 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 109 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
110 | * any extra contention... |
111 | */ | |
112 | ||
113 | /* In order to reduce some races, while at the same time doing additional | |
114 | * checking and hopefully speeding things up, we copy filenames to the | |
115 | * kernel data space before using them.. | |
116 | * | |
117 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
118 | * PATH_MAX includes the nul terminator --RR. | |
119 | */ | |
91a27b2a | 120 | void final_putname(struct filename *name) |
1da177e4 | 121 | { |
7950e385 JL |
122 | if (name->separate) { |
123 | __putname(name->name); | |
124 | kfree(name); | |
125 | } else { | |
126 | __putname(name); | |
127 | } | |
91a27b2a JL |
128 | } |
129 | ||
7950e385 JL |
130 | #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) |
131 | ||
91a27b2a JL |
132 | static struct filename * |
133 | getname_flags(const char __user *filename, int flags, int *empty) | |
134 | { | |
135 | struct filename *result, *err; | |
3f9f0aa6 | 136 | int len; |
7950e385 JL |
137 | long max; |
138 | char *kname; | |
4043cde8 | 139 | |
7ac86265 JL |
140 | result = audit_reusename(filename); |
141 | if (result) | |
142 | return result; | |
143 | ||
7950e385 | 144 | result = __getname(); |
3f9f0aa6 | 145 | if (unlikely(!result)) |
4043cde8 EP |
146 | return ERR_PTR(-ENOMEM); |
147 | ||
7950e385 JL |
148 | /* |
149 | * First, try to embed the struct filename inside the names_cache | |
150 | * allocation | |
151 | */ | |
152 | kname = (char *)result + sizeof(*result); | |
91a27b2a | 153 | result->name = kname; |
7950e385 JL |
154 | result->separate = false; |
155 | max = EMBEDDED_NAME_MAX; | |
156 | ||
157 | recopy: | |
158 | len = strncpy_from_user(kname, filename, max); | |
91a27b2a JL |
159 | if (unlikely(len < 0)) { |
160 | err = ERR_PTR(len); | |
3f9f0aa6 | 161 | goto error; |
91a27b2a | 162 | } |
3f9f0aa6 | 163 | |
7950e385 JL |
164 | /* |
165 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
166 | * separate struct filename so we can dedicate the entire | |
167 | * names_cache allocation for the pathname, and re-do the copy from | |
168 | * userland. | |
169 | */ | |
170 | if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { | |
171 | kname = (char *)result; | |
172 | ||
173 | result = kzalloc(sizeof(*result), GFP_KERNEL); | |
174 | if (!result) { | |
175 | err = ERR_PTR(-ENOMEM); | |
176 | result = (struct filename *)kname; | |
177 | goto error; | |
178 | } | |
179 | result->name = kname; | |
180 | result->separate = true; | |
181 | max = PATH_MAX; | |
182 | goto recopy; | |
183 | } | |
184 | ||
3f9f0aa6 LT |
185 | /* The empty path is special. */ |
186 | if (unlikely(!len)) { | |
187 | if (empty) | |
4043cde8 | 188 | *empty = 1; |
3f9f0aa6 LT |
189 | err = ERR_PTR(-ENOENT); |
190 | if (!(flags & LOOKUP_EMPTY)) | |
191 | goto error; | |
1da177e4 | 192 | } |
3f9f0aa6 LT |
193 | |
194 | err = ERR_PTR(-ENAMETOOLONG); | |
7950e385 JL |
195 | if (unlikely(len >= PATH_MAX)) |
196 | goto error; | |
197 | ||
198 | result->uptr = filename; | |
199 | audit_getname(result); | |
200 | return result; | |
3f9f0aa6 LT |
201 | |
202 | error: | |
7950e385 | 203 | final_putname(result); |
3f9f0aa6 | 204 | return err; |
1da177e4 LT |
205 | } |
206 | ||
91a27b2a JL |
207 | struct filename * |
208 | getname(const char __user * filename) | |
f52e0c11 | 209 | { |
f7493e5d | 210 | return getname_flags(filename, 0, NULL); |
f52e0c11 | 211 | } |
91a27b2a | 212 | EXPORT_SYMBOL(getname); |
f52e0c11 | 213 | |
1da177e4 | 214 | #ifdef CONFIG_AUDITSYSCALL |
91a27b2a | 215 | void putname(struct filename *name) |
1da177e4 | 216 | { |
5ac3a9c2 | 217 | if (unlikely(!audit_dummy_context())) |
91a27b2a JL |
218 | return audit_putname(name); |
219 | final_putname(name); | |
1da177e4 | 220 | } |
1da177e4 LT |
221 | #endif |
222 | ||
e77819e5 LT |
223 | static int check_acl(struct inode *inode, int mask) |
224 | { | |
84635d68 | 225 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
226 | struct posix_acl *acl; |
227 | ||
e77819e5 | 228 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
229 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
230 | if (!acl) | |
e77819e5 | 231 | return -EAGAIN; |
3567866b AV |
232 | /* no ->get_acl() calls in RCU mode... */ |
233 | if (acl == ACL_NOT_CACHED) | |
234 | return -ECHILD; | |
206b1d09 | 235 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
236 | } |
237 | ||
238 | acl = get_cached_acl(inode, ACL_TYPE_ACCESS); | |
239 | ||
240 | /* | |
4e34e719 CH |
241 | * A filesystem can force a ACL callback by just never filling the |
242 | * ACL cache. But normally you'd fill the cache either at inode | |
243 | * instantiation time, or on the first ->get_acl call. | |
e77819e5 | 244 | * |
4e34e719 CH |
245 | * If the filesystem doesn't have a get_acl() function at all, we'll |
246 | * just create the negative cache entry. | |
e77819e5 LT |
247 | */ |
248 | if (acl == ACL_NOT_CACHED) { | |
4e34e719 CH |
249 | if (inode->i_op->get_acl) { |
250 | acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); | |
251 | if (IS_ERR(acl)) | |
252 | return PTR_ERR(acl); | |
253 | } else { | |
254 | set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); | |
255 | return -EAGAIN; | |
256 | } | |
e77819e5 LT |
257 | } |
258 | ||
259 | if (acl) { | |
260 | int error = posix_acl_permission(inode, acl, mask); | |
261 | posix_acl_release(acl); | |
262 | return error; | |
263 | } | |
84635d68 | 264 | #endif |
e77819e5 LT |
265 | |
266 | return -EAGAIN; | |
267 | } | |
268 | ||
5909ccaa | 269 | /* |
948409c7 | 270 | * This does the basic permission checking |
1da177e4 | 271 | */ |
7e40145e | 272 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 273 | { |
26cf46be | 274 | unsigned int mode = inode->i_mode; |
1da177e4 | 275 | |
8e96e3b7 | 276 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
277 | mode >>= 6; |
278 | else { | |
e77819e5 | 279 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 280 | int error = check_acl(inode, mask); |
b74c79e9 NP |
281 | if (error != -EAGAIN) |
282 | return error; | |
1da177e4 LT |
283 | } |
284 | ||
285 | if (in_group_p(inode->i_gid)) | |
286 | mode >>= 3; | |
287 | } | |
288 | ||
289 | /* | |
290 | * If the DACs are ok we don't need any capability check. | |
291 | */ | |
9c2c7039 | 292 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 293 | return 0; |
5909ccaa LT |
294 | return -EACCES; |
295 | } | |
296 | ||
297 | /** | |
b74c79e9 | 298 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 299 | * @inode: inode to check access rights for |
8fd90c8d | 300 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
301 | * |
302 | * Used to check for read/write/execute permissions on a file. | |
303 | * We use "fsuid" for this, letting us set arbitrary permissions | |
304 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
305 | * are used for other things. |
306 | * | |
307 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
308 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
309 | * It would then be called again in ref-walk mode. | |
5909ccaa | 310 | */ |
2830ba7f | 311 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
312 | { |
313 | int ret; | |
314 | ||
315 | /* | |
948409c7 | 316 | * Do the basic permission checks. |
5909ccaa | 317 | */ |
7e40145e | 318 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
319 | if (ret != -EACCES) |
320 | return ret; | |
1da177e4 | 321 | |
d594e7ec AV |
322 | if (S_ISDIR(inode->i_mode)) { |
323 | /* DACs are overridable for directories */ | |
1a48e2ac | 324 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
325 | return 0; |
326 | if (!(mask & MAY_WRITE)) | |
1a48e2ac | 327 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
d594e7ec AV |
328 | return 0; |
329 | return -EACCES; | |
330 | } | |
1da177e4 LT |
331 | /* |
332 | * Read/write DACs are always overridable. | |
d594e7ec AV |
333 | * Executable DACs are overridable when there is |
334 | * at least one exec bit set. | |
1da177e4 | 335 | */ |
d594e7ec | 336 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
1a48e2ac | 337 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
338 | return 0; |
339 | ||
340 | /* | |
341 | * Searching includes executable on directories, else just read. | |
342 | */ | |
7ea66001 | 343 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 344 | if (mask == MAY_READ) |
1a48e2ac | 345 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
346 | return 0; |
347 | ||
348 | return -EACCES; | |
349 | } | |
350 | ||
3ddcd056 LT |
351 | /* |
352 | * We _really_ want to just do "generic_permission()" without | |
353 | * even looking at the inode->i_op values. So we keep a cache | |
354 | * flag in inode->i_opflags, that says "this has not special | |
355 | * permission function, use the fast case". | |
356 | */ | |
357 | static inline int do_inode_permission(struct inode *inode, int mask) | |
358 | { | |
359 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
360 | if (likely(inode->i_op->permission)) | |
361 | return inode->i_op->permission(inode, mask); | |
362 | ||
363 | /* This gets set once for the inode lifetime */ | |
364 | spin_lock(&inode->i_lock); | |
365 | inode->i_opflags |= IOP_FASTPERM; | |
366 | spin_unlock(&inode->i_lock); | |
367 | } | |
368 | return generic_permission(inode, mask); | |
369 | } | |
370 | ||
cb23beb5 | 371 | /** |
0bdaea90 DH |
372 | * __inode_permission - Check for access rights to a given inode |
373 | * @inode: Inode to check permission on | |
374 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 375 | * |
0bdaea90 | 376 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
377 | * |
378 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
379 | * |
380 | * This does not check for a read-only file system. You probably want | |
381 | * inode_permission(). | |
cb23beb5 | 382 | */ |
0bdaea90 | 383 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 384 | { |
e6305c43 | 385 | int retval; |
1da177e4 | 386 | |
3ddcd056 | 387 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
388 | /* |
389 | * Nobody gets write access to an immutable file. | |
390 | */ | |
391 | if (IS_IMMUTABLE(inode)) | |
392 | return -EACCES; | |
393 | } | |
394 | ||
3ddcd056 | 395 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
396 | if (retval) |
397 | return retval; | |
398 | ||
08ce5f16 SH |
399 | retval = devcgroup_inode_permission(inode, mask); |
400 | if (retval) | |
401 | return retval; | |
402 | ||
d09ca739 | 403 | return security_inode_permission(inode, mask); |
1da177e4 LT |
404 | } |
405 | ||
0bdaea90 DH |
406 | /** |
407 | * sb_permission - Check superblock-level permissions | |
408 | * @sb: Superblock of inode to check permission on | |
55852635 | 409 | * @inode: Inode to check permission on |
0bdaea90 DH |
410 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
411 | * | |
412 | * Separate out file-system wide checks from inode-specific permission checks. | |
413 | */ | |
414 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
415 | { | |
416 | if (unlikely(mask & MAY_WRITE)) { | |
417 | umode_t mode = inode->i_mode; | |
418 | ||
419 | /* Nobody gets write access to a read-only fs. */ | |
420 | if ((sb->s_flags & MS_RDONLY) && | |
421 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
422 | return -EROFS; | |
423 | } | |
424 | return 0; | |
425 | } | |
426 | ||
427 | /** | |
428 | * inode_permission - Check for access rights to a given inode | |
429 | * @inode: Inode to check permission on | |
430 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
431 | * | |
432 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
433 | * this, letting us set arbitrary permissions for filesystem access without | |
434 | * changing the "normal" UIDs which are used for other things. | |
435 | * | |
436 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
437 | */ | |
438 | int inode_permission(struct inode *inode, int mask) | |
439 | { | |
440 | int retval; | |
441 | ||
442 | retval = sb_permission(inode->i_sb, inode, mask); | |
443 | if (retval) | |
444 | return retval; | |
445 | return __inode_permission(inode, mask); | |
446 | } | |
447 | ||
5dd784d0 JB |
448 | /** |
449 | * path_get - get a reference to a path | |
450 | * @path: path to get the reference to | |
451 | * | |
452 | * Given a path increment the reference count to the dentry and the vfsmount. | |
453 | */ | |
454 | void path_get(struct path *path) | |
455 | { | |
456 | mntget(path->mnt); | |
457 | dget(path->dentry); | |
458 | } | |
459 | EXPORT_SYMBOL(path_get); | |
460 | ||
1d957f9b JB |
461 | /** |
462 | * path_put - put a reference to a path | |
463 | * @path: path to put the reference to | |
464 | * | |
465 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
466 | */ | |
467 | void path_put(struct path *path) | |
1da177e4 | 468 | { |
1d957f9b JB |
469 | dput(path->dentry); |
470 | mntput(path->mnt); | |
1da177e4 | 471 | } |
1d957f9b | 472 | EXPORT_SYMBOL(path_put); |
1da177e4 | 473 | |
19660af7 | 474 | /* |
31e6b01f | 475 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
476 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
477 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
478 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
479 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
480 | * got stuck, so ref-walk may continue from there. If this is not successful | |
481 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
482 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 483 | */ |
31e6b01f | 484 | |
32a7991b AV |
485 | static inline void lock_rcu_walk(void) |
486 | { | |
487 | br_read_lock(&vfsmount_lock); | |
488 | rcu_read_lock(); | |
489 | } | |
490 | ||
491 | static inline void unlock_rcu_walk(void) | |
492 | { | |
493 | rcu_read_unlock(); | |
494 | br_read_unlock(&vfsmount_lock); | |
495 | } | |
496 | ||
31e6b01f | 497 | /** |
19660af7 AV |
498 | * unlazy_walk - try to switch to ref-walk mode. |
499 | * @nd: nameidata pathwalk data | |
500 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 501 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 502 | * |
19660af7 AV |
503 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
504 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
505 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 506 | */ |
19660af7 | 507 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
508 | { |
509 | struct fs_struct *fs = current->fs; | |
510 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 511 | int want_root = 0; |
31e6b01f NP |
512 | |
513 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
514 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
515 | want_root = 1; | |
31e6b01f NP |
516 | spin_lock(&fs->lock); |
517 | if (nd->root.mnt != fs->root.mnt || | |
518 | nd->root.dentry != fs->root.dentry) | |
519 | goto err_root; | |
520 | } | |
521 | spin_lock(&parent->d_lock); | |
19660af7 AV |
522 | if (!dentry) { |
523 | if (!__d_rcu_to_refcount(parent, nd->seq)) | |
524 | goto err_parent; | |
525 | BUG_ON(nd->inode != parent->d_inode); | |
526 | } else { | |
94c0d4ec AV |
527 | if (dentry->d_parent != parent) |
528 | goto err_parent; | |
19660af7 AV |
529 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
530 | if (!__d_rcu_to_refcount(dentry, nd->seq)) | |
531 | goto err_child; | |
532 | /* | |
533 | * If the sequence check on the child dentry passed, then | |
534 | * the child has not been removed from its parent. This | |
535 | * means the parent dentry must be valid and able to take | |
536 | * a reference at this point. | |
537 | */ | |
538 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); | |
539 | BUG_ON(!parent->d_count); | |
540 | parent->d_count++; | |
541 | spin_unlock(&dentry->d_lock); | |
542 | } | |
31e6b01f | 543 | spin_unlock(&parent->d_lock); |
5b6ca027 | 544 | if (want_root) { |
31e6b01f NP |
545 | path_get(&nd->root); |
546 | spin_unlock(&fs->lock); | |
547 | } | |
548 | mntget(nd->path.mnt); | |
549 | ||
32a7991b | 550 | unlock_rcu_walk(); |
31e6b01f NP |
551 | nd->flags &= ~LOOKUP_RCU; |
552 | return 0; | |
19660af7 AV |
553 | |
554 | err_child: | |
31e6b01f | 555 | spin_unlock(&dentry->d_lock); |
19660af7 | 556 | err_parent: |
31e6b01f NP |
557 | spin_unlock(&parent->d_lock); |
558 | err_root: | |
5b6ca027 | 559 | if (want_root) |
31e6b01f NP |
560 | spin_unlock(&fs->lock); |
561 | return -ECHILD; | |
562 | } | |
563 | ||
4ce16ef3 | 564 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 565 | { |
4ce16ef3 | 566 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
567 | } |
568 | ||
9f1fafee AV |
569 | /** |
570 | * complete_walk - successful completion of path walk | |
571 | * @nd: pointer nameidata | |
39159de2 | 572 | * |
9f1fafee AV |
573 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
574 | * Revalidate the final result, unless we'd already done that during | |
575 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
576 | * success, -error on failure. In case of failure caller does not | |
577 | * need to drop nd->path. | |
39159de2 | 578 | */ |
9f1fafee | 579 | static int complete_walk(struct nameidata *nd) |
39159de2 | 580 | { |
16c2cd71 | 581 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 582 | int status; |
39159de2 | 583 | |
9f1fafee AV |
584 | if (nd->flags & LOOKUP_RCU) { |
585 | nd->flags &= ~LOOKUP_RCU; | |
586 | if (!(nd->flags & LOOKUP_ROOT)) | |
587 | nd->root.mnt = NULL; | |
588 | spin_lock(&dentry->d_lock); | |
589 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { | |
590 | spin_unlock(&dentry->d_lock); | |
32a7991b | 591 | unlock_rcu_walk(); |
9f1fafee AV |
592 | return -ECHILD; |
593 | } | |
594 | BUG_ON(nd->inode != dentry->d_inode); | |
595 | spin_unlock(&dentry->d_lock); | |
596 | mntget(nd->path.mnt); | |
32a7991b | 597 | unlock_rcu_walk(); |
9f1fafee AV |
598 | } |
599 | ||
16c2cd71 AV |
600 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
601 | return 0; | |
602 | ||
603 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) | |
39159de2 JL |
604 | return 0; |
605 | ||
16c2cd71 AV |
606 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
607 | return 0; | |
608 | ||
609 | /* Note: we do not d_invalidate() */ | |
4ce16ef3 | 610 | status = d_revalidate(dentry, nd->flags); |
39159de2 JL |
611 | if (status > 0) |
612 | return 0; | |
613 | ||
16c2cd71 | 614 | if (!status) |
39159de2 | 615 | status = -ESTALE; |
16c2cd71 | 616 | |
9f1fafee | 617 | path_put(&nd->path); |
39159de2 JL |
618 | return status; |
619 | } | |
620 | ||
2a737871 AV |
621 | static __always_inline void set_root(struct nameidata *nd) |
622 | { | |
f7ad3c6b MS |
623 | if (!nd->root.mnt) |
624 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
625 | } |
626 | ||
6de88d72 AV |
627 | static int link_path_walk(const char *, struct nameidata *); |
628 | ||
31e6b01f NP |
629 | static __always_inline void set_root_rcu(struct nameidata *nd) |
630 | { | |
631 | if (!nd->root.mnt) { | |
632 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
633 | unsigned seq; |
634 | ||
635 | do { | |
636 | seq = read_seqcount_begin(&fs->seq); | |
637 | nd->root = fs->root; | |
c1530019 | 638 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 639 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
640 | } |
641 | } | |
642 | ||
f1662356 | 643 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 644 | { |
31e6b01f NP |
645 | int ret; |
646 | ||
1da177e4 LT |
647 | if (IS_ERR(link)) |
648 | goto fail; | |
649 | ||
650 | if (*link == '/') { | |
2a737871 | 651 | set_root(nd); |
1d957f9b | 652 | path_put(&nd->path); |
2a737871 AV |
653 | nd->path = nd->root; |
654 | path_get(&nd->root); | |
16c2cd71 | 655 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 656 | } |
31e6b01f | 657 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 658 | |
31e6b01f NP |
659 | ret = link_path_walk(link, nd); |
660 | return ret; | |
1da177e4 | 661 | fail: |
1d957f9b | 662 | path_put(&nd->path); |
1da177e4 LT |
663 | return PTR_ERR(link); |
664 | } | |
665 | ||
1d957f9b | 666 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
667 | { |
668 | dput(path->dentry); | |
4ac91378 | 669 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
670 | mntput(path->mnt); |
671 | } | |
672 | ||
7b9337aa NP |
673 | static inline void path_to_nameidata(const struct path *path, |
674 | struct nameidata *nd) | |
051d3812 | 675 | { |
31e6b01f NP |
676 | if (!(nd->flags & LOOKUP_RCU)) { |
677 | dput(nd->path.dentry); | |
678 | if (nd->path.mnt != path->mnt) | |
679 | mntput(nd->path.mnt); | |
9a229683 | 680 | } |
31e6b01f | 681 | nd->path.mnt = path->mnt; |
4ac91378 | 682 | nd->path.dentry = path->dentry; |
051d3812 IK |
683 | } |
684 | ||
b5fb63c1 CH |
685 | /* |
686 | * Helper to directly jump to a known parsed path from ->follow_link, | |
687 | * caller must have taken a reference to path beforehand. | |
688 | */ | |
689 | void nd_jump_link(struct nameidata *nd, struct path *path) | |
690 | { | |
691 | path_put(&nd->path); | |
692 | ||
693 | nd->path = *path; | |
694 | nd->inode = nd->path.dentry->d_inode; | |
695 | nd->flags |= LOOKUP_JUMPED; | |
696 | ||
697 | BUG_ON(nd->inode->i_op->follow_link); | |
698 | } | |
699 | ||
574197e0 AV |
700 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
701 | { | |
702 | struct inode *inode = link->dentry->d_inode; | |
6d7b5aae | 703 | if (inode->i_op->put_link) |
574197e0 AV |
704 | inode->i_op->put_link(link->dentry, nd, cookie); |
705 | path_put(link); | |
706 | } | |
707 | ||
561ec64a LT |
708 | int sysctl_protected_symlinks __read_mostly = 0; |
709 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
710 | |
711 | /** | |
712 | * may_follow_link - Check symlink following for unsafe situations | |
713 | * @link: The path of the symlink | |
55852635 | 714 | * @nd: nameidata pathwalk data |
800179c9 KC |
715 | * |
716 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
717 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
718 | * in a sticky world-writable directory. This is to protect privileged | |
719 | * processes from failing races against path names that may change out | |
720 | * from under them by way of other users creating malicious symlinks. | |
721 | * It will permit symlinks to be followed only when outside a sticky | |
722 | * world-writable directory, or when the uid of the symlink and follower | |
723 | * match, or when the directory owner matches the symlink's owner. | |
724 | * | |
725 | * Returns 0 if following the symlink is allowed, -ve on error. | |
726 | */ | |
727 | static inline int may_follow_link(struct path *link, struct nameidata *nd) | |
728 | { | |
729 | const struct inode *inode; | |
730 | const struct inode *parent; | |
731 | ||
732 | if (!sysctl_protected_symlinks) | |
733 | return 0; | |
734 | ||
735 | /* Allowed if owner and follower match. */ | |
736 | inode = link->dentry->d_inode; | |
81abe27b | 737 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
738 | return 0; |
739 | ||
740 | /* Allowed if parent directory not sticky and world-writable. */ | |
741 | parent = nd->path.dentry->d_inode; | |
742 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
743 | return 0; | |
744 | ||
745 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 746 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
747 | return 0; |
748 | ||
ffd8d101 | 749 | audit_log_link_denied("follow_link", link); |
800179c9 KC |
750 | path_put_conditional(link, nd); |
751 | path_put(&nd->path); | |
752 | return -EACCES; | |
753 | } | |
754 | ||
755 | /** | |
756 | * safe_hardlink_source - Check for safe hardlink conditions | |
757 | * @inode: the source inode to hardlink from | |
758 | * | |
759 | * Return false if at least one of the following conditions: | |
760 | * - inode is not a regular file | |
761 | * - inode is setuid | |
762 | * - inode is setgid and group-exec | |
763 | * - access failure for read and write | |
764 | * | |
765 | * Otherwise returns true. | |
766 | */ | |
767 | static bool safe_hardlink_source(struct inode *inode) | |
768 | { | |
769 | umode_t mode = inode->i_mode; | |
770 | ||
771 | /* Special files should not get pinned to the filesystem. */ | |
772 | if (!S_ISREG(mode)) | |
773 | return false; | |
774 | ||
775 | /* Setuid files should not get pinned to the filesystem. */ | |
776 | if (mode & S_ISUID) | |
777 | return false; | |
778 | ||
779 | /* Executable setgid files should not get pinned to the filesystem. */ | |
780 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
781 | return false; | |
782 | ||
783 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
784 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
785 | return false; | |
786 | ||
787 | return true; | |
788 | } | |
789 | ||
790 | /** | |
791 | * may_linkat - Check permissions for creating a hardlink | |
792 | * @link: the source to hardlink from | |
793 | * | |
794 | * Block hardlink when all of: | |
795 | * - sysctl_protected_hardlinks enabled | |
796 | * - fsuid does not match inode | |
797 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
798 | * - not CAP_FOWNER | |
799 | * | |
800 | * Returns 0 if successful, -ve on error. | |
801 | */ | |
802 | static int may_linkat(struct path *link) | |
803 | { | |
804 | const struct cred *cred; | |
805 | struct inode *inode; | |
806 | ||
807 | if (!sysctl_protected_hardlinks) | |
808 | return 0; | |
809 | ||
810 | cred = current_cred(); | |
811 | inode = link->dentry->d_inode; | |
812 | ||
813 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
814 | * otherwise, it must be a safe source. | |
815 | */ | |
81abe27b | 816 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
817 | capable(CAP_FOWNER)) |
818 | return 0; | |
819 | ||
a51d9eaa | 820 | audit_log_link_denied("linkat", link); |
800179c9 KC |
821 | return -EPERM; |
822 | } | |
823 | ||
def4af30 | 824 | static __always_inline int |
574197e0 | 825 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 | 826 | { |
7b9337aa | 827 | struct dentry *dentry = link->dentry; |
6d7b5aae AV |
828 | int error; |
829 | char *s; | |
1da177e4 | 830 | |
844a3917 AV |
831 | BUG_ON(nd->flags & LOOKUP_RCU); |
832 | ||
0e794589 AV |
833 | if (link->mnt == nd->path.mnt) |
834 | mntget(link->mnt); | |
835 | ||
6d7b5aae AV |
836 | error = -ELOOP; |
837 | if (unlikely(current->total_link_count >= 40)) | |
838 | goto out_put_nd_path; | |
839 | ||
574197e0 AV |
840 | cond_resched(); |
841 | current->total_link_count++; | |
842 | ||
68ac1234 | 843 | touch_atime(link); |
1da177e4 | 844 | nd_set_link(nd, NULL); |
cd4e91d3 | 845 | |
36f3b4f6 | 846 | error = security_inode_follow_link(link->dentry, nd); |
6d7b5aae AV |
847 | if (error) |
848 | goto out_put_nd_path; | |
36f3b4f6 | 849 | |
86acdca1 | 850 | nd->last_type = LAST_BIND; |
def4af30 AV |
851 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
852 | error = PTR_ERR(*p); | |
6d7b5aae | 853 | if (IS_ERR(*p)) |
408ef013 | 854 | goto out_put_nd_path; |
6d7b5aae AV |
855 | |
856 | error = 0; | |
857 | s = nd_get_link(nd); | |
858 | if (s) { | |
859 | error = __vfs_follow_link(nd, s); | |
b5fb63c1 CH |
860 | if (unlikely(error)) |
861 | put_link(nd, link, *p); | |
1da177e4 | 862 | } |
6d7b5aae AV |
863 | |
864 | return error; | |
865 | ||
866 | out_put_nd_path: | |
98f6ef64 | 867 | *p = NULL; |
6d7b5aae | 868 | path_put(&nd->path); |
6d7b5aae | 869 | path_put(link); |
1da177e4 LT |
870 | return error; |
871 | } | |
872 | ||
31e6b01f NP |
873 | static int follow_up_rcu(struct path *path) |
874 | { | |
0714a533 AV |
875 | struct mount *mnt = real_mount(path->mnt); |
876 | struct mount *parent; | |
31e6b01f NP |
877 | struct dentry *mountpoint; |
878 | ||
0714a533 AV |
879 | parent = mnt->mnt_parent; |
880 | if (&parent->mnt == path->mnt) | |
31e6b01f | 881 | return 0; |
a73324da | 882 | mountpoint = mnt->mnt_mountpoint; |
31e6b01f | 883 | path->dentry = mountpoint; |
0714a533 | 884 | path->mnt = &parent->mnt; |
31e6b01f NP |
885 | return 1; |
886 | } | |
887 | ||
f015f126 DH |
888 | /* |
889 | * follow_up - Find the mountpoint of path's vfsmount | |
890 | * | |
891 | * Given a path, find the mountpoint of its source file system. | |
892 | * Replace @path with the path of the mountpoint in the parent mount. | |
893 | * Up is towards /. | |
894 | * | |
895 | * Return 1 if we went up a level and 0 if we were already at the | |
896 | * root. | |
897 | */ | |
bab77ebf | 898 | int follow_up(struct path *path) |
1da177e4 | 899 | { |
0714a533 AV |
900 | struct mount *mnt = real_mount(path->mnt); |
901 | struct mount *parent; | |
1da177e4 | 902 | struct dentry *mountpoint; |
99b7db7b | 903 | |
962830df | 904 | br_read_lock(&vfsmount_lock); |
0714a533 | 905 | parent = mnt->mnt_parent; |
3c0a6163 | 906 | if (parent == mnt) { |
962830df | 907 | br_read_unlock(&vfsmount_lock); |
1da177e4 LT |
908 | return 0; |
909 | } | |
0714a533 | 910 | mntget(&parent->mnt); |
a73324da | 911 | mountpoint = dget(mnt->mnt_mountpoint); |
962830df | 912 | br_read_unlock(&vfsmount_lock); |
bab77ebf AV |
913 | dput(path->dentry); |
914 | path->dentry = mountpoint; | |
915 | mntput(path->mnt); | |
0714a533 | 916 | path->mnt = &parent->mnt; |
1da177e4 LT |
917 | return 1; |
918 | } | |
919 | ||
b5c84bf6 | 920 | /* |
9875cf80 DH |
921 | * Perform an automount |
922 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
923 | * were called with. | |
1da177e4 | 924 | */ |
9875cf80 DH |
925 | static int follow_automount(struct path *path, unsigned flags, |
926 | bool *need_mntput) | |
31e6b01f | 927 | { |
9875cf80 | 928 | struct vfsmount *mnt; |
ea5b778a | 929 | int err; |
9875cf80 DH |
930 | |
931 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
932 | return -EREMOTE; | |
933 | ||
0ec26fd0 MS |
934 | /* We don't want to mount if someone's just doing a stat - |
935 | * unless they're stat'ing a directory and appended a '/' to | |
936 | * the name. | |
937 | * | |
938 | * We do, however, want to mount if someone wants to open or | |
939 | * create a file of any type under the mountpoint, wants to | |
940 | * traverse through the mountpoint or wants to open the | |
941 | * mounted directory. Also, autofs may mark negative dentries | |
942 | * as being automount points. These will need the attentions | |
943 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 944 | */ |
0ec26fd0 | 945 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 946 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
947 | path->dentry->d_inode) |
948 | return -EISDIR; | |
949 | ||
9875cf80 DH |
950 | current->total_link_count++; |
951 | if (current->total_link_count >= 40) | |
952 | return -ELOOP; | |
953 | ||
954 | mnt = path->dentry->d_op->d_automount(path); | |
955 | if (IS_ERR(mnt)) { | |
956 | /* | |
957 | * The filesystem is allowed to return -EISDIR here to indicate | |
958 | * it doesn't want to automount. For instance, autofs would do | |
959 | * this so that its userspace daemon can mount on this dentry. | |
960 | * | |
961 | * However, we can only permit this if it's a terminal point in | |
962 | * the path being looked up; if it wasn't then the remainder of | |
963 | * the path is inaccessible and we should say so. | |
964 | */ | |
49084c3b | 965 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
966 | return -EREMOTE; |
967 | return PTR_ERR(mnt); | |
31e6b01f | 968 | } |
ea5b778a | 969 | |
9875cf80 DH |
970 | if (!mnt) /* mount collision */ |
971 | return 0; | |
31e6b01f | 972 | |
8aef1884 AV |
973 | if (!*need_mntput) { |
974 | /* lock_mount() may release path->mnt on error */ | |
975 | mntget(path->mnt); | |
976 | *need_mntput = true; | |
977 | } | |
19a167af | 978 | err = finish_automount(mnt, path); |
9875cf80 | 979 | |
ea5b778a DH |
980 | switch (err) { |
981 | case -EBUSY: | |
982 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 983 | return 0; |
ea5b778a | 984 | case 0: |
8aef1884 | 985 | path_put(path); |
ea5b778a DH |
986 | path->mnt = mnt; |
987 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 988 | return 0; |
19a167af AV |
989 | default: |
990 | return err; | |
ea5b778a | 991 | } |
19a167af | 992 | |
463ffb2e AV |
993 | } |
994 | ||
9875cf80 DH |
995 | /* |
996 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 997 | * - Flagged for transit management (autofs) |
9875cf80 DH |
998 | * - Flagged as mountpoint |
999 | * - Flagged as automount point | |
1000 | * | |
1001 | * This may only be called in refwalk mode. | |
1002 | * | |
1003 | * Serialization is taken care of in namespace.c | |
1004 | */ | |
1005 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 1006 | { |
8aef1884 | 1007 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1008 | unsigned managed; |
1009 | bool need_mntput = false; | |
8aef1884 | 1010 | int ret = 0; |
9875cf80 DH |
1011 | |
1012 | /* Given that we're not holding a lock here, we retain the value in a | |
1013 | * local variable for each dentry as we look at it so that we don't see | |
1014 | * the components of that value change under us */ | |
1015 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1016 | managed &= DCACHE_MANAGED_DENTRY, | |
1017 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1018 | /* Allow the filesystem to manage the transit without i_mutex |
1019 | * being held. */ | |
1020 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1021 | BUG_ON(!path->dentry->d_op); | |
1022 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1023 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1024 | if (ret < 0) |
8aef1884 | 1025 | break; |
cc53ce53 DH |
1026 | } |
1027 | ||
9875cf80 DH |
1028 | /* Transit to a mounted filesystem. */ |
1029 | if (managed & DCACHE_MOUNTED) { | |
1030 | struct vfsmount *mounted = lookup_mnt(path); | |
1031 | if (mounted) { | |
1032 | dput(path->dentry); | |
1033 | if (need_mntput) | |
1034 | mntput(path->mnt); | |
1035 | path->mnt = mounted; | |
1036 | path->dentry = dget(mounted->mnt_root); | |
1037 | need_mntput = true; | |
1038 | continue; | |
1039 | } | |
1040 | ||
1041 | /* Something is mounted on this dentry in another | |
1042 | * namespace and/or whatever was mounted there in this | |
1043 | * namespace got unmounted before we managed to get the | |
1044 | * vfsmount_lock */ | |
1045 | } | |
1046 | ||
1047 | /* Handle an automount point */ | |
1048 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
1049 | ret = follow_automount(path, flags, &need_mntput); | |
1050 | if (ret < 0) | |
8aef1884 | 1051 | break; |
9875cf80 DH |
1052 | continue; |
1053 | } | |
1054 | ||
1055 | /* We didn't change the current path point */ | |
1056 | break; | |
1da177e4 | 1057 | } |
8aef1884 AV |
1058 | |
1059 | if (need_mntput && path->mnt == mnt) | |
1060 | mntput(path->mnt); | |
1061 | if (ret == -EISDIR) | |
1062 | ret = 0; | |
a3fbbde7 | 1063 | return ret < 0 ? ret : need_mntput; |
1da177e4 LT |
1064 | } |
1065 | ||
cc53ce53 | 1066 | int follow_down_one(struct path *path) |
1da177e4 LT |
1067 | { |
1068 | struct vfsmount *mounted; | |
1069 | ||
1c755af4 | 1070 | mounted = lookup_mnt(path); |
1da177e4 | 1071 | if (mounted) { |
9393bd07 AV |
1072 | dput(path->dentry); |
1073 | mntput(path->mnt); | |
1074 | path->mnt = mounted; | |
1075 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1076 | return 1; |
1077 | } | |
1078 | return 0; | |
1079 | } | |
1080 | ||
62a7375e IK |
1081 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
1082 | { | |
1083 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
1084 | dentry->d_op->d_manage(dentry, true) < 0); | |
1085 | } | |
1086 | ||
9875cf80 | 1087 | /* |
287548e4 AV |
1088 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1089 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1090 | */ |
1091 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 1092 | struct inode **inode) |
9875cf80 | 1093 | { |
62a7375e | 1094 | for (;;) { |
c7105365 | 1095 | struct mount *mounted; |
62a7375e IK |
1096 | /* |
1097 | * Don't forget we might have a non-mountpoint managed dentry | |
1098 | * that wants to block transit. | |
1099 | */ | |
287548e4 | 1100 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 1101 | return false; |
62a7375e IK |
1102 | |
1103 | if (!d_mountpoint(path->dentry)) | |
1104 | break; | |
1105 | ||
9875cf80 DH |
1106 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
1107 | if (!mounted) | |
1108 | break; | |
c7105365 AV |
1109 | path->mnt = &mounted->mnt; |
1110 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1111 | nd->flags |= LOOKUP_JUMPED; |
9875cf80 | 1112 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1113 | /* |
1114 | * Update the inode too. We don't need to re-check the | |
1115 | * dentry sequence number here after this d_inode read, | |
1116 | * because a mount-point is always pinned. | |
1117 | */ | |
1118 | *inode = path->dentry->d_inode; | |
9875cf80 | 1119 | } |
9875cf80 DH |
1120 | return true; |
1121 | } | |
1122 | ||
dea39376 | 1123 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 1124 | { |
dea39376 | 1125 | while (d_mountpoint(nd->path.dentry)) { |
c7105365 | 1126 | struct mount *mounted; |
dea39376 | 1127 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
1128 | if (!mounted) |
1129 | break; | |
c7105365 AV |
1130 | nd->path.mnt = &mounted->mnt; |
1131 | nd->path.dentry = mounted->mnt.mnt_root; | |
dea39376 | 1132 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
287548e4 AV |
1133 | } |
1134 | } | |
1135 | ||
31e6b01f NP |
1136 | static int follow_dotdot_rcu(struct nameidata *nd) |
1137 | { | |
31e6b01f NP |
1138 | set_root_rcu(nd); |
1139 | ||
9875cf80 | 1140 | while (1) { |
31e6b01f NP |
1141 | if (nd->path.dentry == nd->root.dentry && |
1142 | nd->path.mnt == nd->root.mnt) { | |
1143 | break; | |
1144 | } | |
1145 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
1146 | struct dentry *old = nd->path.dentry; | |
1147 | struct dentry *parent = old->d_parent; | |
1148 | unsigned seq; | |
1149 | ||
1150 | seq = read_seqcount_begin(&parent->d_seq); | |
1151 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 1152 | goto failed; |
31e6b01f NP |
1153 | nd->path.dentry = parent; |
1154 | nd->seq = seq; | |
1155 | break; | |
1156 | } | |
1157 | if (!follow_up_rcu(&nd->path)) | |
1158 | break; | |
1159 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 1160 | } |
dea39376 AV |
1161 | follow_mount_rcu(nd); |
1162 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 1163 | return 0; |
ef7562d5 AV |
1164 | |
1165 | failed: | |
1166 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1167 | if (!(nd->flags & LOOKUP_ROOT)) |
1168 | nd->root.mnt = NULL; | |
32a7991b | 1169 | unlock_rcu_walk(); |
ef7562d5 | 1170 | return -ECHILD; |
31e6b01f NP |
1171 | } |
1172 | ||
cc53ce53 DH |
1173 | /* |
1174 | * Follow down to the covering mount currently visible to userspace. At each | |
1175 | * point, the filesystem owning that dentry may be queried as to whether the | |
1176 | * caller is permitted to proceed or not. | |
cc53ce53 | 1177 | */ |
7cc90cc3 | 1178 | int follow_down(struct path *path) |
cc53ce53 DH |
1179 | { |
1180 | unsigned managed; | |
1181 | int ret; | |
1182 | ||
1183 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1184 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1185 | /* Allow the filesystem to manage the transit without i_mutex | |
1186 | * being held. | |
1187 | * | |
1188 | * We indicate to the filesystem if someone is trying to mount | |
1189 | * something here. This gives autofs the chance to deny anyone | |
1190 | * other than its daemon the right to mount on its | |
1191 | * superstructure. | |
1192 | * | |
1193 | * The filesystem may sleep at this point. | |
1194 | */ | |
1195 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1196 | BUG_ON(!path->dentry->d_op); | |
1197 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1198 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1199 | path->dentry, false); |
cc53ce53 DH |
1200 | if (ret < 0) |
1201 | return ret == -EISDIR ? 0 : ret; | |
1202 | } | |
1203 | ||
1204 | /* Transit to a mounted filesystem. */ | |
1205 | if (managed & DCACHE_MOUNTED) { | |
1206 | struct vfsmount *mounted = lookup_mnt(path); | |
1207 | if (!mounted) | |
1208 | break; | |
1209 | dput(path->dentry); | |
1210 | mntput(path->mnt); | |
1211 | path->mnt = mounted; | |
1212 | path->dentry = dget(mounted->mnt_root); | |
1213 | continue; | |
1214 | } | |
1215 | ||
1216 | /* Don't handle automount points here */ | |
1217 | break; | |
1218 | } | |
1219 | return 0; | |
1220 | } | |
1221 | ||
9875cf80 DH |
1222 | /* |
1223 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1224 | */ | |
1225 | static void follow_mount(struct path *path) | |
1226 | { | |
1227 | while (d_mountpoint(path->dentry)) { | |
1228 | struct vfsmount *mounted = lookup_mnt(path); | |
1229 | if (!mounted) | |
1230 | break; | |
1231 | dput(path->dentry); | |
1232 | mntput(path->mnt); | |
1233 | path->mnt = mounted; | |
1234 | path->dentry = dget(mounted->mnt_root); | |
1235 | } | |
1236 | } | |
1237 | ||
31e6b01f | 1238 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1239 | { |
2a737871 | 1240 | set_root(nd); |
e518ddb7 | 1241 | |
1da177e4 | 1242 | while(1) { |
4ac91378 | 1243 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1244 | |
2a737871 AV |
1245 | if (nd->path.dentry == nd->root.dentry && |
1246 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1247 | break; |
1248 | } | |
4ac91378 | 1249 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1250 | /* rare case of legitimate dget_parent()... */ |
1251 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1252 | dput(old); |
1253 | break; | |
1254 | } | |
3088dd70 | 1255 | if (!follow_up(&nd->path)) |
1da177e4 | 1256 | break; |
1da177e4 | 1257 | } |
79ed0226 | 1258 | follow_mount(&nd->path); |
31e6b01f | 1259 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1260 | } |
1261 | ||
baa03890 | 1262 | /* |
bad61189 MS |
1263 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1264 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1265 | * returns whether i_op->lookup is necessary. | |
1266 | * | |
1267 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1268 | */ |
bad61189 | 1269 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1270 | unsigned int flags, bool *need_lookup) |
baa03890 | 1271 | { |
baa03890 | 1272 | struct dentry *dentry; |
bad61189 | 1273 | int error; |
baa03890 | 1274 | |
bad61189 MS |
1275 | *need_lookup = false; |
1276 | dentry = d_lookup(dir, name); | |
1277 | if (dentry) { | |
39e3c955 | 1278 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1279 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1280 | if (unlikely(error <= 0)) { |
1281 | if (error < 0) { | |
1282 | dput(dentry); | |
1283 | return ERR_PTR(error); | |
1284 | } else if (!d_invalidate(dentry)) { | |
1285 | dput(dentry); | |
1286 | dentry = NULL; | |
1287 | } | |
1288 | } | |
1289 | } | |
1290 | } | |
baa03890 | 1291 | |
bad61189 MS |
1292 | if (!dentry) { |
1293 | dentry = d_alloc(dir, name); | |
1294 | if (unlikely(!dentry)) | |
1295 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1296 | |
bad61189 | 1297 | *need_lookup = true; |
baa03890 NP |
1298 | } |
1299 | return dentry; | |
1300 | } | |
1301 | ||
44396f4b | 1302 | /* |
bad61189 MS |
1303 | * Call i_op->lookup on the dentry. The dentry must be negative but may be |
1304 | * hashed if it was pouplated with DCACHE_NEED_LOOKUP. | |
1305 | * | |
1306 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1307 | */ |
bad61189 | 1308 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1309 | unsigned int flags) |
44396f4b | 1310 | { |
44396f4b JB |
1311 | struct dentry *old; |
1312 | ||
1313 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1314 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1315 | dput(dentry); |
44396f4b | 1316 | return ERR_PTR(-ENOENT); |
e188dc02 | 1317 | } |
44396f4b | 1318 | |
72bd866a | 1319 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1320 | if (unlikely(old)) { |
1321 | dput(dentry); | |
1322 | dentry = old; | |
1323 | } | |
1324 | return dentry; | |
1325 | } | |
1326 | ||
a3255546 | 1327 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1328 | struct dentry *base, unsigned int flags) |
a3255546 | 1329 | { |
bad61189 | 1330 | bool need_lookup; |
a3255546 AV |
1331 | struct dentry *dentry; |
1332 | ||
72bd866a | 1333 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1334 | if (!need_lookup) |
1335 | return dentry; | |
a3255546 | 1336 | |
72bd866a | 1337 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1338 | } |
1339 | ||
1da177e4 LT |
1340 | /* |
1341 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1342 | * small and for now I'd prefer to have fast path as straight as possible. | |
1343 | * It _is_ time-critical. | |
1344 | */ | |
697f514d MS |
1345 | static int lookup_fast(struct nameidata *nd, struct qstr *name, |
1346 | struct path *path, struct inode **inode) | |
1da177e4 | 1347 | { |
4ac91378 | 1348 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1349 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1350 | int need_reval = 1; |
1351 | int status = 1; | |
9875cf80 DH |
1352 | int err; |
1353 | ||
b04f784e NP |
1354 | /* |
1355 | * Rename seqlock is not required here because in the off chance | |
1356 | * of a false negative due to a concurrent rename, we're going to | |
1357 | * do the non-racy lookup, below. | |
1358 | */ | |
31e6b01f NP |
1359 | if (nd->flags & LOOKUP_RCU) { |
1360 | unsigned seq; | |
12f8ad4b | 1361 | dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); |
5a18fff2 AV |
1362 | if (!dentry) |
1363 | goto unlazy; | |
1364 | ||
12f8ad4b LT |
1365 | /* |
1366 | * This sequence count validates that the inode matches | |
1367 | * the dentry name information from lookup. | |
1368 | */ | |
1369 | *inode = dentry->d_inode; | |
1370 | if (read_seqcount_retry(&dentry->d_seq, seq)) | |
1371 | return -ECHILD; | |
1372 | ||
1373 | /* | |
1374 | * This sequence count validates that the parent had no | |
1375 | * changes while we did the lookup of the dentry above. | |
1376 | * | |
1377 | * The memory barrier in read_seqcount_begin of child is | |
1378 | * enough, we can use __read_seqcount_retry here. | |
1379 | */ | |
31e6b01f NP |
1380 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1381 | return -ECHILD; | |
31e6b01f | 1382 | nd->seq = seq; |
5a18fff2 | 1383 | |
24643087 | 1384 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1385 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1386 | if (unlikely(status <= 0)) { |
1387 | if (status != -ECHILD) | |
1388 | need_reval = 0; | |
1389 | goto unlazy; | |
1390 | } | |
24643087 | 1391 | } |
31e6b01f NP |
1392 | path->mnt = mnt; |
1393 | path->dentry = dentry; | |
d6e9bd25 AV |
1394 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1395 | goto unlazy; | |
1396 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1397 | goto unlazy; | |
1398 | return 0; | |
5a18fff2 | 1399 | unlazy: |
19660af7 AV |
1400 | if (unlazy_walk(nd, dentry)) |
1401 | return -ECHILD; | |
5a18fff2 AV |
1402 | } else { |
1403 | dentry = __d_lookup(parent, name); | |
9875cf80 | 1404 | } |
5a18fff2 | 1405 | |
81e6f520 AV |
1406 | if (unlikely(!dentry)) |
1407 | goto need_lookup; | |
1408 | ||
5a18fff2 | 1409 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1410 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1411 | if (unlikely(status <= 0)) { |
1412 | if (status < 0) { | |
1413 | dput(dentry); | |
1414 | return status; | |
1415 | } | |
1416 | if (!d_invalidate(dentry)) { | |
1417 | dput(dentry); | |
81e6f520 | 1418 | goto need_lookup; |
5a18fff2 | 1419 | } |
24643087 | 1420 | } |
697f514d | 1421 | |
9875cf80 DH |
1422 | path->mnt = mnt; |
1423 | path->dentry = dentry; | |
1424 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1425 | if (unlikely(err < 0)) { |
1426 | path_put_conditional(path, nd); | |
9875cf80 | 1427 | return err; |
89312214 | 1428 | } |
a3fbbde7 AV |
1429 | if (err) |
1430 | nd->flags |= LOOKUP_JUMPED; | |
9875cf80 | 1431 | *inode = path->dentry->d_inode; |
1da177e4 | 1432 | return 0; |
81e6f520 AV |
1433 | |
1434 | need_lookup: | |
697f514d MS |
1435 | return 1; |
1436 | } | |
1437 | ||
1438 | /* Fast lookup failed, do it the slow way */ | |
1439 | static int lookup_slow(struct nameidata *nd, struct qstr *name, | |
1440 | struct path *path) | |
1441 | { | |
1442 | struct dentry *dentry, *parent; | |
1443 | int err; | |
1444 | ||
1445 | parent = nd->path.dentry; | |
81e6f520 AV |
1446 | BUG_ON(nd->inode != parent->d_inode); |
1447 | ||
1448 | mutex_lock(&parent->d_inode->i_mutex); | |
72bd866a | 1449 | dentry = __lookup_hash(name, parent, nd->flags); |
81e6f520 AV |
1450 | mutex_unlock(&parent->d_inode->i_mutex); |
1451 | if (IS_ERR(dentry)) | |
1452 | return PTR_ERR(dentry); | |
697f514d MS |
1453 | path->mnt = nd->path.mnt; |
1454 | path->dentry = dentry; | |
1455 | err = follow_managed(path, nd->flags); | |
1456 | if (unlikely(err < 0)) { | |
1457 | path_put_conditional(path, nd); | |
1458 | return err; | |
1459 | } | |
1460 | if (err) | |
1461 | nd->flags |= LOOKUP_JUMPED; | |
1462 | return 0; | |
1da177e4 LT |
1463 | } |
1464 | ||
52094c8a AV |
1465 | static inline int may_lookup(struct nameidata *nd) |
1466 | { | |
1467 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1468 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1469 | if (err != -ECHILD) |
1470 | return err; | |
19660af7 | 1471 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1472 | return -ECHILD; |
1473 | } | |
4ad5abb3 | 1474 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1475 | } |
1476 | ||
9856fa1b AV |
1477 | static inline int handle_dots(struct nameidata *nd, int type) |
1478 | { | |
1479 | if (type == LAST_DOTDOT) { | |
1480 | if (nd->flags & LOOKUP_RCU) { | |
1481 | if (follow_dotdot_rcu(nd)) | |
1482 | return -ECHILD; | |
1483 | } else | |
1484 | follow_dotdot(nd); | |
1485 | } | |
1486 | return 0; | |
1487 | } | |
1488 | ||
951361f9 AV |
1489 | static void terminate_walk(struct nameidata *nd) |
1490 | { | |
1491 | if (!(nd->flags & LOOKUP_RCU)) { | |
1492 | path_put(&nd->path); | |
1493 | } else { | |
1494 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1495 | if (!(nd->flags & LOOKUP_ROOT)) |
1496 | nd->root.mnt = NULL; | |
32a7991b | 1497 | unlock_rcu_walk(); |
951361f9 AV |
1498 | } |
1499 | } | |
1500 | ||
3ddcd056 LT |
1501 | /* |
1502 | * Do we need to follow links? We _really_ want to be able | |
1503 | * to do this check without having to look at inode->i_op, | |
1504 | * so we keep a cache of "no, this doesn't need follow_link" | |
1505 | * for the common case. | |
1506 | */ | |
7813b94a | 1507 | static inline int should_follow_link(struct inode *inode, int follow) |
3ddcd056 LT |
1508 | { |
1509 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
1510 | if (likely(inode->i_op->follow_link)) | |
1511 | return follow; | |
1512 | ||
1513 | /* This gets set once for the inode lifetime */ | |
1514 | spin_lock(&inode->i_lock); | |
1515 | inode->i_opflags |= IOP_NOFOLLOW; | |
1516 | spin_unlock(&inode->i_lock); | |
1517 | } | |
1518 | return 0; | |
1519 | } | |
1520 | ||
ce57dfc1 AV |
1521 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1522 | struct qstr *name, int type, int follow) | |
1523 | { | |
1524 | struct inode *inode; | |
1525 | int err; | |
1526 | /* | |
1527 | * "." and ".." are special - ".." especially so because it has | |
1528 | * to be able to know about the current root directory and | |
1529 | * parent relationships. | |
1530 | */ | |
1531 | if (unlikely(type != LAST_NORM)) | |
1532 | return handle_dots(nd, type); | |
697f514d | 1533 | err = lookup_fast(nd, name, path, &inode); |
ce57dfc1 | 1534 | if (unlikely(err)) { |
697f514d MS |
1535 | if (err < 0) |
1536 | goto out_err; | |
1537 | ||
1538 | err = lookup_slow(nd, name, path); | |
1539 | if (err < 0) | |
1540 | goto out_err; | |
1541 | ||
1542 | inode = path->dentry->d_inode; | |
ce57dfc1 | 1543 | } |
697f514d MS |
1544 | err = -ENOENT; |
1545 | if (!inode) | |
1546 | goto out_path_put; | |
1547 | ||
7813b94a | 1548 | if (should_follow_link(inode, follow)) { |
19660af7 AV |
1549 | if (nd->flags & LOOKUP_RCU) { |
1550 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
697f514d MS |
1551 | err = -ECHILD; |
1552 | goto out_err; | |
19660af7 AV |
1553 | } |
1554 | } | |
ce57dfc1 AV |
1555 | BUG_ON(inode != path->dentry->d_inode); |
1556 | return 1; | |
1557 | } | |
1558 | path_to_nameidata(path, nd); | |
1559 | nd->inode = inode; | |
1560 | return 0; | |
697f514d MS |
1561 | |
1562 | out_path_put: | |
1563 | path_to_nameidata(path, nd); | |
1564 | out_err: | |
1565 | terminate_walk(nd); | |
1566 | return err; | |
ce57dfc1 AV |
1567 | } |
1568 | ||
b356379a AV |
1569 | /* |
1570 | * This limits recursive symlink follows to 8, while | |
1571 | * limiting consecutive symlinks to 40. | |
1572 | * | |
1573 | * Without that kind of total limit, nasty chains of consecutive | |
1574 | * symlinks can cause almost arbitrarily long lookups. | |
1575 | */ | |
1576 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1577 | { | |
1578 | int res; | |
1579 | ||
b356379a AV |
1580 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1581 | path_put_conditional(path, nd); | |
1582 | path_put(&nd->path); | |
1583 | return -ELOOP; | |
1584 | } | |
1a4022f8 | 1585 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1586 | |
1587 | nd->depth++; | |
1588 | current->link_count++; | |
1589 | ||
1590 | do { | |
1591 | struct path link = *path; | |
1592 | void *cookie; | |
574197e0 AV |
1593 | |
1594 | res = follow_link(&link, nd, &cookie); | |
6d7b5aae AV |
1595 | if (res) |
1596 | break; | |
1597 | res = walk_component(nd, path, &nd->last, | |
1598 | nd->last_type, LOOKUP_FOLLOW); | |
574197e0 | 1599 | put_link(nd, &link, cookie); |
b356379a AV |
1600 | } while (res > 0); |
1601 | ||
1602 | current->link_count--; | |
1603 | nd->depth--; | |
1604 | return res; | |
1605 | } | |
1606 | ||
3ddcd056 LT |
1607 | /* |
1608 | * We really don't want to look at inode->i_op->lookup | |
1609 | * when we don't have to. So we keep a cache bit in | |
1610 | * the inode ->i_opflags field that says "yes, we can | |
1611 | * do lookup on this inode". | |
1612 | */ | |
1613 | static inline int can_lookup(struct inode *inode) | |
1614 | { | |
1615 | if (likely(inode->i_opflags & IOP_LOOKUP)) | |
1616 | return 1; | |
1617 | if (likely(!inode->i_op->lookup)) | |
1618 | return 0; | |
1619 | ||
1620 | /* We do this once for the lifetime of the inode */ | |
1621 | spin_lock(&inode->i_lock); | |
1622 | inode->i_opflags |= IOP_LOOKUP; | |
1623 | spin_unlock(&inode->i_lock); | |
1624 | return 1; | |
1625 | } | |
1626 | ||
bfcfaa77 LT |
1627 | /* |
1628 | * We can do the critical dentry name comparison and hashing | |
1629 | * operations one word at a time, but we are limited to: | |
1630 | * | |
1631 | * - Architectures with fast unaligned word accesses. We could | |
1632 | * do a "get_unaligned()" if this helps and is sufficiently | |
1633 | * fast. | |
1634 | * | |
1635 | * - Little-endian machines (so that we can generate the mask | |
1636 | * of low bytes efficiently). Again, we *could* do a byte | |
1637 | * swapping load on big-endian architectures if that is not | |
1638 | * expensive enough to make the optimization worthless. | |
1639 | * | |
1640 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we | |
1641 | * do not trap on the (extremely unlikely) case of a page | |
1642 | * crossing operation. | |
1643 | * | |
1644 | * - Furthermore, we need an efficient 64-bit compile for the | |
1645 | * 64-bit case in order to generate the "number of bytes in | |
1646 | * the final mask". Again, that could be replaced with a | |
1647 | * efficient population count instruction or similar. | |
1648 | */ | |
1649 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1650 | ||
f68e556e | 1651 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1652 | |
f68e556e | 1653 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1654 | |
1655 | static inline unsigned int fold_hash(unsigned long hash) | |
1656 | { | |
1657 | hash += hash >> (8*sizeof(int)); | |
1658 | return hash; | |
1659 | } | |
1660 | ||
1661 | #else /* 32-bit case */ | |
1662 | ||
bfcfaa77 LT |
1663 | #define fold_hash(x) (x) |
1664 | ||
1665 | #endif | |
1666 | ||
1667 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1668 | { | |
1669 | unsigned long a, mask; | |
1670 | unsigned long hash = 0; | |
1671 | ||
1672 | for (;;) { | |
e419b4cc | 1673 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1674 | if (len < sizeof(unsigned long)) |
1675 | break; | |
1676 | hash += a; | |
f132c5be | 1677 | hash *= 9; |
bfcfaa77 LT |
1678 | name += sizeof(unsigned long); |
1679 | len -= sizeof(unsigned long); | |
1680 | if (!len) | |
1681 | goto done; | |
1682 | } | |
1683 | mask = ~(~0ul << len*8); | |
1684 | hash += mask & a; | |
1685 | done: | |
1686 | return fold_hash(hash); | |
1687 | } | |
1688 | EXPORT_SYMBOL(full_name_hash); | |
1689 | ||
bfcfaa77 LT |
1690 | /* |
1691 | * Calculate the length and hash of the path component, and | |
1692 | * return the length of the component; | |
1693 | */ | |
1694 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1695 | { | |
36126f8f LT |
1696 | unsigned long a, b, adata, bdata, mask, hash, len; |
1697 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1698 | |
1699 | hash = a = 0; | |
1700 | len = -sizeof(unsigned long); | |
1701 | do { | |
1702 | hash = (hash + a) * 9; | |
1703 | len += sizeof(unsigned long); | |
e419b4cc | 1704 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1705 | b = a ^ REPEAT_BYTE('/'); |
1706 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1707 | ||
1708 | adata = prep_zero_mask(a, adata, &constants); | |
1709 | bdata = prep_zero_mask(b, bdata, &constants); | |
1710 | ||
1711 | mask = create_zero_mask(adata | bdata); | |
1712 | ||
1713 | hash += a & zero_bytemask(mask); | |
bfcfaa77 LT |
1714 | *hashp = fold_hash(hash); |
1715 | ||
36126f8f | 1716 | return len + find_zero(mask); |
bfcfaa77 LT |
1717 | } |
1718 | ||
1719 | #else | |
1720 | ||
0145acc2 LT |
1721 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1722 | { | |
1723 | unsigned long hash = init_name_hash(); | |
1724 | while (len--) | |
1725 | hash = partial_name_hash(*name++, hash); | |
1726 | return end_name_hash(hash); | |
1727 | } | |
ae942ae7 | 1728 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1729 | |
200e9ef7 LT |
1730 | /* |
1731 | * We know there's a real path component here of at least | |
1732 | * one character. | |
1733 | */ | |
1734 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1735 | { | |
1736 | unsigned long hash = init_name_hash(); | |
1737 | unsigned long len = 0, c; | |
1738 | ||
1739 | c = (unsigned char)*name; | |
1740 | do { | |
1741 | len++; | |
1742 | hash = partial_name_hash(c, hash); | |
1743 | c = (unsigned char)name[len]; | |
1744 | } while (c && c != '/'); | |
1745 | *hashp = end_name_hash(hash); | |
1746 | return len; | |
1747 | } | |
1748 | ||
bfcfaa77 LT |
1749 | #endif |
1750 | ||
1da177e4 LT |
1751 | /* |
1752 | * Name resolution. | |
ea3834d9 PM |
1753 | * This is the basic name resolution function, turning a pathname into |
1754 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1755 | * |
ea3834d9 PM |
1756 | * Returns 0 and nd will have valid dentry and mnt on success. |
1757 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1758 | */ |
6de88d72 | 1759 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1760 | { |
1761 | struct path next; | |
1da177e4 | 1762 | int err; |
1da177e4 LT |
1763 | |
1764 | while (*name=='/') | |
1765 | name++; | |
1766 | if (!*name) | |
086e183a | 1767 | return 0; |
1da177e4 | 1768 | |
1da177e4 LT |
1769 | /* At this point we know we have a real path component. */ |
1770 | for(;;) { | |
1da177e4 | 1771 | struct qstr this; |
200e9ef7 | 1772 | long len; |
fe479a58 | 1773 | int type; |
1da177e4 | 1774 | |
52094c8a | 1775 | err = may_lookup(nd); |
1da177e4 LT |
1776 | if (err) |
1777 | break; | |
1778 | ||
200e9ef7 | 1779 | len = hash_name(name, &this.hash); |
1da177e4 | 1780 | this.name = name; |
200e9ef7 | 1781 | this.len = len; |
1da177e4 | 1782 | |
fe479a58 | 1783 | type = LAST_NORM; |
200e9ef7 | 1784 | if (name[0] == '.') switch (len) { |
fe479a58 | 1785 | case 2: |
200e9ef7 | 1786 | if (name[1] == '.') { |
fe479a58 | 1787 | type = LAST_DOTDOT; |
16c2cd71 AV |
1788 | nd->flags |= LOOKUP_JUMPED; |
1789 | } | |
fe479a58 AV |
1790 | break; |
1791 | case 1: | |
1792 | type = LAST_DOT; | |
1793 | } | |
5a202bcd AV |
1794 | if (likely(type == LAST_NORM)) { |
1795 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1796 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd AV |
1797 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1798 | err = parent->d_op->d_hash(parent, nd->inode, | |
1799 | &this); | |
1800 | if (err < 0) | |
1801 | break; | |
1802 | } | |
1803 | } | |
fe479a58 | 1804 | |
200e9ef7 | 1805 | if (!name[len]) |
1da177e4 | 1806 | goto last_component; |
200e9ef7 LT |
1807 | /* |
1808 | * If it wasn't NUL, we know it was '/'. Skip that | |
1809 | * slash, and continue until no more slashes. | |
1810 | */ | |
1811 | do { | |
1812 | len++; | |
1813 | } while (unlikely(name[len] == '/')); | |
1814 | if (!name[len]) | |
b356379a | 1815 | goto last_component; |
200e9ef7 | 1816 | name += len; |
1da177e4 | 1817 | |
ce57dfc1 AV |
1818 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1819 | if (err < 0) | |
1820 | return err; | |
1da177e4 | 1821 | |
ce57dfc1 | 1822 | if (err) { |
b356379a | 1823 | err = nested_symlink(&next, nd); |
1da177e4 | 1824 | if (err) |
a7472bab | 1825 | return err; |
31e6b01f | 1826 | } |
3ddcd056 LT |
1827 | if (can_lookup(nd->inode)) |
1828 | continue; | |
1da177e4 | 1829 | err = -ENOTDIR; |
3ddcd056 | 1830 | break; |
1da177e4 LT |
1831 | /* here ends the main loop */ |
1832 | ||
1da177e4 | 1833 | last_component: |
b356379a AV |
1834 | nd->last = this; |
1835 | nd->last_type = type; | |
086e183a | 1836 | return 0; |
1da177e4 | 1837 | } |
951361f9 | 1838 | terminate_walk(nd); |
1da177e4 LT |
1839 | return err; |
1840 | } | |
1841 | ||
70e9b357 AV |
1842 | static int path_init(int dfd, const char *name, unsigned int flags, |
1843 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1844 | { |
1845 | int retval = 0; | |
31e6b01f NP |
1846 | |
1847 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1848 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1849 | nd->depth = 0; |
5b6ca027 AV |
1850 | if (flags & LOOKUP_ROOT) { |
1851 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 | 1852 | if (*name) { |
741b7c3f | 1853 | if (!can_lookup(inode)) |
73d049a4 AV |
1854 | return -ENOTDIR; |
1855 | retval = inode_permission(inode, MAY_EXEC); | |
1856 | if (retval) | |
1857 | return retval; | |
1858 | } | |
5b6ca027 AV |
1859 | nd->path = nd->root; |
1860 | nd->inode = inode; | |
1861 | if (flags & LOOKUP_RCU) { | |
32a7991b | 1862 | lock_rcu_walk(); |
5b6ca027 AV |
1863 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1864 | } else { | |
1865 | path_get(&nd->path); | |
1866 | } | |
1867 | return 0; | |
1868 | } | |
1869 | ||
31e6b01f | 1870 | nd->root.mnt = NULL; |
31e6b01f NP |
1871 | |
1872 | if (*name=='/') { | |
e41f7d4e | 1873 | if (flags & LOOKUP_RCU) { |
32a7991b | 1874 | lock_rcu_walk(); |
e41f7d4e AV |
1875 | set_root_rcu(nd); |
1876 | } else { | |
1877 | set_root(nd); | |
1878 | path_get(&nd->root); | |
1879 | } | |
1880 | nd->path = nd->root; | |
31e6b01f | 1881 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1882 | if (flags & LOOKUP_RCU) { |
1883 | struct fs_struct *fs = current->fs; | |
1884 | unsigned seq; | |
31e6b01f | 1885 | |
32a7991b | 1886 | lock_rcu_walk(); |
c28cc364 | 1887 | |
e41f7d4e AV |
1888 | do { |
1889 | seq = read_seqcount_begin(&fs->seq); | |
1890 | nd->path = fs->pwd; | |
1891 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1892 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1893 | } else { | |
1894 | get_fs_pwd(current->fs, &nd->path); | |
1895 | } | |
31e6b01f | 1896 | } else { |
582aa64a | 1897 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 1898 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
1899 | struct dentry *dentry; |
1900 | ||
2903ff01 AV |
1901 | if (!f.file) |
1902 | return -EBADF; | |
31e6b01f | 1903 | |
2903ff01 | 1904 | dentry = f.file->f_path.dentry; |
31e6b01f | 1905 | |
f52e0c11 | 1906 | if (*name) { |
741b7c3f | 1907 | if (!can_lookup(dentry->d_inode)) { |
2903ff01 AV |
1908 | fdput(f); |
1909 | return -ENOTDIR; | |
1910 | } | |
f52e0c11 | 1911 | } |
31e6b01f | 1912 | |
2903ff01 | 1913 | nd->path = f.file->f_path; |
e41f7d4e | 1914 | if (flags & LOOKUP_RCU) { |
2903ff01 AV |
1915 | if (f.need_put) |
1916 | *fp = f.file; | |
e41f7d4e | 1917 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
32a7991b | 1918 | lock_rcu_walk(); |
e41f7d4e | 1919 | } else { |
2903ff01 AV |
1920 | path_get(&nd->path); |
1921 | fdput(f); | |
e41f7d4e | 1922 | } |
31e6b01f | 1923 | } |
31e6b01f | 1924 | |
31e6b01f | 1925 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1926 | return 0; |
9b4a9b14 AV |
1927 | } |
1928 | ||
bd92d7fe AV |
1929 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1930 | { | |
1931 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1932 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1933 | ||
1934 | nd->flags &= ~LOOKUP_PARENT; | |
1935 | return walk_component(nd, path, &nd->last, nd->last_type, | |
1936 | nd->flags & LOOKUP_FOLLOW); | |
1937 | } | |
1938 | ||
9b4a9b14 | 1939 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1940 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1941 | unsigned int flags, struct nameidata *nd) |
1942 | { | |
70e9b357 | 1943 | struct file *base = NULL; |
bd92d7fe AV |
1944 | struct path path; |
1945 | int err; | |
31e6b01f NP |
1946 | |
1947 | /* | |
1948 | * Path walking is largely split up into 2 different synchronisation | |
1949 | * schemes, rcu-walk and ref-walk (explained in | |
1950 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1951 | * path walk code, but some things particularly setup, cleanup, and | |
1952 | * following mounts are sufficiently divergent that functions are | |
1953 | * duplicated. Typically there is a function foo(), and its RCU | |
1954 | * analogue, foo_rcu(). | |
1955 | * | |
1956 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1957 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1958 | * be handled by restarting a traditional ref-walk (which will always | |
1959 | * be able to complete). | |
1960 | */ | |
bd92d7fe | 1961 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1962 | |
bd92d7fe AV |
1963 | if (unlikely(err)) |
1964 | return err; | |
ee0827cd AV |
1965 | |
1966 | current->total_link_count = 0; | |
bd92d7fe AV |
1967 | err = link_path_walk(name, nd); |
1968 | ||
1969 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1970 | err = lookup_last(nd, &path); |
1971 | while (err > 0) { | |
1972 | void *cookie; | |
1973 | struct path link = path; | |
800179c9 KC |
1974 | err = may_follow_link(&link, nd); |
1975 | if (unlikely(err)) | |
1976 | break; | |
bd92d7fe | 1977 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1978 | err = follow_link(&link, nd, &cookie); |
6d7b5aae AV |
1979 | if (err) |
1980 | break; | |
1981 | err = lookup_last(nd, &path); | |
574197e0 | 1982 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1983 | } |
1984 | } | |
ee0827cd | 1985 | |
9f1fafee AV |
1986 | if (!err) |
1987 | err = complete_walk(nd); | |
bd92d7fe AV |
1988 | |
1989 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
1990 | if (!nd->inode->i_op->lookup) { | |
1991 | path_put(&nd->path); | |
bd23a539 | 1992 | err = -ENOTDIR; |
bd92d7fe AV |
1993 | } |
1994 | } | |
16c2cd71 | 1995 | |
70e9b357 AV |
1996 | if (base) |
1997 | fput(base); | |
ee0827cd | 1998 | |
5b6ca027 | 1999 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
2000 | path_put(&nd->root); |
2001 | nd->root.mnt = NULL; | |
2002 | } | |
bd92d7fe | 2003 | return err; |
ee0827cd | 2004 | } |
31e6b01f | 2005 | |
873f1eed | 2006 | static int filename_lookup(int dfd, struct filename *name, |
ee0827cd AV |
2007 | unsigned int flags, struct nameidata *nd) |
2008 | { | |
873f1eed | 2009 | int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); |
ee0827cd | 2010 | if (unlikely(retval == -ECHILD)) |
873f1eed | 2011 | retval = path_lookupat(dfd, name->name, flags, nd); |
ee0827cd | 2012 | if (unlikely(retval == -ESTALE)) |
873f1eed JL |
2013 | retval = path_lookupat(dfd, name->name, |
2014 | flags | LOOKUP_REVAL, nd); | |
31e6b01f | 2015 | |
f78570dd | 2016 | if (likely(!retval)) |
adb5c247 | 2017 | audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); |
170aa3d0 | 2018 | return retval; |
1da177e4 LT |
2019 | } |
2020 | ||
873f1eed JL |
2021 | static int do_path_lookup(int dfd, const char *name, |
2022 | unsigned int flags, struct nameidata *nd) | |
2023 | { | |
2024 | struct filename filename = { .name = name }; | |
2025 | ||
2026 | return filename_lookup(dfd, &filename, flags, nd); | |
2027 | } | |
2028 | ||
79714f72 AV |
2029 | /* does lookup, returns the object with parent locked */ |
2030 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2031 | { |
79714f72 AV |
2032 | struct nameidata nd; |
2033 | struct dentry *d; | |
2034 | int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); | |
2035 | if (err) | |
2036 | return ERR_PTR(err); | |
2037 | if (nd.last_type != LAST_NORM) { | |
2038 | path_put(&nd.path); | |
2039 | return ERR_PTR(-EINVAL); | |
2040 | } | |
2041 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2042 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2043 | if (IS_ERR(d)) { |
2044 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2045 | path_put(&nd.path); | |
2046 | return d; | |
2047 | } | |
2048 | *path = nd.path; | |
2049 | return d; | |
5590ff0d UD |
2050 | } |
2051 | ||
d1811465 AV |
2052 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2053 | { | |
2054 | struct nameidata nd; | |
2055 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
2056 | if (!res) | |
2057 | *path = nd.path; | |
2058 | return res; | |
2059 | } | |
2060 | ||
16f18200 JJS |
2061 | /** |
2062 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2063 | * @dentry: pointer to dentry of the base directory | |
2064 | * @mnt: pointer to vfs mount of the base directory | |
2065 | * @name: pointer to file name | |
2066 | * @flags: lookup flags | |
e0a01249 | 2067 | * @path: pointer to struct path to fill |
16f18200 JJS |
2068 | */ |
2069 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2070 | const char *name, unsigned int flags, | |
e0a01249 | 2071 | struct path *path) |
16f18200 | 2072 | { |
e0a01249 AV |
2073 | struct nameidata nd; |
2074 | int err; | |
2075 | nd.root.dentry = dentry; | |
2076 | nd.root.mnt = mnt; | |
2077 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 2078 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
2079 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
2080 | if (!err) | |
2081 | *path = nd.path; | |
2082 | return err; | |
16f18200 JJS |
2083 | } |
2084 | ||
057f6c01 JM |
2085 | /* |
2086 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
2087 | * needs parent already locked. Doesn't follow mounts. | |
2088 | * SMP-safe. | |
2089 | */ | |
eead1911 | 2090 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 2091 | { |
72bd866a | 2092 | return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); |
1da177e4 LT |
2093 | } |
2094 | ||
eead1911 | 2095 | /** |
a6b91919 | 2096 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2097 | * @name: pathname component to lookup |
2098 | * @base: base directory to lookup from | |
2099 | * @len: maximum length @len should be interpreted to | |
2100 | * | |
a6b91919 RD |
2101 | * Note that this routine is purely a helper for filesystem usage and should |
2102 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
2103 | * nameidata argument is passed to the filesystem methods and a filesystem |
2104 | * using this helper needs to be prepared for that. | |
2105 | */ | |
057f6c01 JM |
2106 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2107 | { | |
057f6c01 | 2108 | struct qstr this; |
6a96ba54 | 2109 | unsigned int c; |
cda309de | 2110 | int err; |
057f6c01 | 2111 | |
2f9092e1 DW |
2112 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2113 | ||
6a96ba54 AV |
2114 | this.name = name; |
2115 | this.len = len; | |
0145acc2 | 2116 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2117 | if (!len) |
2118 | return ERR_PTR(-EACCES); | |
2119 | ||
21d8a15a AV |
2120 | if (unlikely(name[0] == '.')) { |
2121 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2122 | return ERR_PTR(-EACCES); | |
2123 | } | |
2124 | ||
6a96ba54 AV |
2125 | while (len--) { |
2126 | c = *(const unsigned char *)name++; | |
2127 | if (c == '/' || c == '\0') | |
2128 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2129 | } |
5a202bcd AV |
2130 | /* |
2131 | * See if the low-level filesystem might want | |
2132 | * to use its own hash.. | |
2133 | */ | |
2134 | if (base->d_flags & DCACHE_OP_HASH) { | |
2135 | int err = base->d_op->d_hash(base, base->d_inode, &this); | |
2136 | if (err < 0) | |
2137 | return ERR_PTR(err); | |
2138 | } | |
eead1911 | 2139 | |
cda309de MS |
2140 | err = inode_permission(base->d_inode, MAY_EXEC); |
2141 | if (err) | |
2142 | return ERR_PTR(err); | |
2143 | ||
72bd866a | 2144 | return __lookup_hash(&this, base, 0); |
057f6c01 JM |
2145 | } |
2146 | ||
1fa1e7f6 AW |
2147 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2148 | struct path *path, int *empty) | |
1da177e4 | 2149 | { |
2d8f3038 | 2150 | struct nameidata nd; |
91a27b2a | 2151 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2152 | int err = PTR_ERR(tmp); |
1da177e4 | 2153 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2154 | |
2155 | BUG_ON(flags & LOOKUP_PARENT); | |
2156 | ||
873f1eed | 2157 | err = filename_lookup(dfd, tmp, flags, &nd); |
1da177e4 | 2158 | putname(tmp); |
2d8f3038 AV |
2159 | if (!err) |
2160 | *path = nd.path; | |
1da177e4 LT |
2161 | } |
2162 | return err; | |
2163 | } | |
2164 | ||
1fa1e7f6 AW |
2165 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2166 | struct path *path) | |
2167 | { | |
f7493e5d | 2168 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 AW |
2169 | } |
2170 | ||
873f1eed JL |
2171 | /* |
2172 | * NB: most callers don't do anything directly with the reference to the | |
2173 | * to struct filename, but the nd->last pointer points into the name string | |
2174 | * allocated by getname. So we must hold the reference to it until all | |
2175 | * path-walking is complete. | |
2176 | */ | |
91a27b2a | 2177 | static struct filename * |
9e790bd6 JL |
2178 | user_path_parent(int dfd, const char __user *path, struct nameidata *nd, |
2179 | unsigned int flags) | |
2ad94ae6 | 2180 | { |
91a27b2a | 2181 | struct filename *s = getname(path); |
2ad94ae6 AV |
2182 | int error; |
2183 | ||
9e790bd6 JL |
2184 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2185 | flags &= LOOKUP_REVAL; | |
2186 | ||
2ad94ae6 | 2187 | if (IS_ERR(s)) |
91a27b2a | 2188 | return s; |
2ad94ae6 | 2189 | |
9e790bd6 | 2190 | error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); |
91a27b2a | 2191 | if (error) { |
2ad94ae6 | 2192 | putname(s); |
91a27b2a JL |
2193 | return ERR_PTR(error); |
2194 | } | |
2ad94ae6 | 2195 | |
91a27b2a | 2196 | return s; |
2ad94ae6 AV |
2197 | } |
2198 | ||
1da177e4 LT |
2199 | /* |
2200 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
2201 | * minimal. | |
2202 | */ | |
2203 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
2204 | { | |
8e96e3b7 | 2205 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2206 | |
1da177e4 LT |
2207 | if (!(dir->i_mode & S_ISVTX)) |
2208 | return 0; | |
8e96e3b7 | 2209 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2210 | return 0; |
8e96e3b7 | 2211 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2212 | return 0; |
1a48e2ac | 2213 | return !inode_capable(inode, CAP_FOWNER); |
1da177e4 LT |
2214 | } |
2215 | ||
2216 | /* | |
2217 | * Check whether we can remove a link victim from directory dir, check | |
2218 | * whether the type of victim is right. | |
2219 | * 1. We can't do it if dir is read-only (done in permission()) | |
2220 | * 2. We should have write and exec permissions on dir | |
2221 | * 3. We can't remove anything from append-only dir | |
2222 | * 4. We can't do anything with immutable dir (done in permission()) | |
2223 | * 5. If the sticky bit on dir is set we should either | |
2224 | * a. be owner of dir, or | |
2225 | * b. be owner of victim, or | |
2226 | * c. have CAP_FOWNER capability | |
2227 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2228 | * links pointing to it. | |
2229 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2230 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2231 | * 9. We can't remove a root or mountpoint. | |
2232 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2233 | * nfs_async_unlink(). | |
2234 | */ | |
858119e1 | 2235 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
2236 | { |
2237 | int error; | |
2238 | ||
2239 | if (!victim->d_inode) | |
2240 | return -ENOENT; | |
2241 | ||
2242 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2243 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2244 | |
f419a2e3 | 2245 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2246 | if (error) |
2247 | return error; | |
2248 | if (IS_APPEND(dir)) | |
2249 | return -EPERM; | |
2250 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 2251 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
2252 | return -EPERM; |
2253 | if (isdir) { | |
2254 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
2255 | return -ENOTDIR; | |
2256 | if (IS_ROOT(victim)) | |
2257 | return -EBUSY; | |
2258 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
2259 | return -EISDIR; | |
2260 | if (IS_DEADDIR(dir)) | |
2261 | return -ENOENT; | |
2262 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2263 | return -EBUSY; | |
2264 | return 0; | |
2265 | } | |
2266 | ||
2267 | /* Check whether we can create an object with dentry child in directory | |
2268 | * dir. | |
2269 | * 1. We can't do it if child already exists (open has special treatment for | |
2270 | * this case, but since we are inlined it's OK) | |
2271 | * 2. We can't do it if dir is read-only (done in permission()) | |
2272 | * 3. We should have write and exec permissions on dir | |
2273 | * 4. We can't do it if dir is immutable (done in permission()) | |
2274 | */ | |
a95164d9 | 2275 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
2276 | { |
2277 | if (child->d_inode) | |
2278 | return -EEXIST; | |
2279 | if (IS_DEADDIR(dir)) | |
2280 | return -ENOENT; | |
f419a2e3 | 2281 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2282 | } |
2283 | ||
1da177e4 LT |
2284 | /* |
2285 | * p1 and p2 should be directories on the same fs. | |
2286 | */ | |
2287 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2288 | { | |
2289 | struct dentry *p; | |
2290 | ||
2291 | if (p1 == p2) { | |
f2eace23 | 2292 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2293 | return NULL; |
2294 | } | |
2295 | ||
a11f3a05 | 2296 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2297 | |
e2761a11 OH |
2298 | p = d_ancestor(p2, p1); |
2299 | if (p) { | |
2300 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2301 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2302 | return p; | |
1da177e4 LT |
2303 | } |
2304 | ||
e2761a11 OH |
2305 | p = d_ancestor(p1, p2); |
2306 | if (p) { | |
2307 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2308 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2309 | return p; | |
1da177e4 LT |
2310 | } |
2311 | ||
f2eace23 IM |
2312 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2313 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
2314 | return NULL; |
2315 | } | |
2316 | ||
2317 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2318 | { | |
1b1dcc1b | 2319 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2320 | if (p1 != p2) { |
1b1dcc1b | 2321 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2322 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2323 | } |
2324 | } | |
2325 | ||
4acdaf27 | 2326 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2327 | bool want_excl) |
1da177e4 | 2328 | { |
a95164d9 | 2329 | int error = may_create(dir, dentry); |
1da177e4 LT |
2330 | if (error) |
2331 | return error; | |
2332 | ||
acfa4380 | 2333 | if (!dir->i_op->create) |
1da177e4 LT |
2334 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2335 | mode &= S_IALLUGO; | |
2336 | mode |= S_IFREG; | |
2337 | error = security_inode_create(dir, dentry, mode); | |
2338 | if (error) | |
2339 | return error; | |
312b63fb | 2340 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2341 | if (!error) |
f38aa942 | 2342 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2343 | return error; |
2344 | } | |
2345 | ||
73d049a4 | 2346 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2347 | { |
3fb64190 | 2348 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2349 | struct inode *inode = dentry->d_inode; |
2350 | int error; | |
2351 | ||
bcda7652 AV |
2352 | /* O_PATH? */ |
2353 | if (!acc_mode) | |
2354 | return 0; | |
2355 | ||
1da177e4 LT |
2356 | if (!inode) |
2357 | return -ENOENT; | |
2358 | ||
c8fe8f30 CH |
2359 | switch (inode->i_mode & S_IFMT) { |
2360 | case S_IFLNK: | |
1da177e4 | 2361 | return -ELOOP; |
c8fe8f30 CH |
2362 | case S_IFDIR: |
2363 | if (acc_mode & MAY_WRITE) | |
2364 | return -EISDIR; | |
2365 | break; | |
2366 | case S_IFBLK: | |
2367 | case S_IFCHR: | |
3fb64190 | 2368 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2369 | return -EACCES; |
c8fe8f30 CH |
2370 | /*FALLTHRU*/ |
2371 | case S_IFIFO: | |
2372 | case S_IFSOCK: | |
1da177e4 | 2373 | flag &= ~O_TRUNC; |
c8fe8f30 | 2374 | break; |
4a3fd211 | 2375 | } |
b41572e9 | 2376 | |
3fb64190 | 2377 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2378 | if (error) |
2379 | return error; | |
6146f0d5 | 2380 | |
1da177e4 LT |
2381 | /* |
2382 | * An append-only file must be opened in append mode for writing. | |
2383 | */ | |
2384 | if (IS_APPEND(inode)) { | |
8737c930 | 2385 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2386 | return -EPERM; |
1da177e4 | 2387 | if (flag & O_TRUNC) |
7715b521 | 2388 | return -EPERM; |
1da177e4 LT |
2389 | } |
2390 | ||
2391 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2392 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2393 | return -EPERM; |
1da177e4 | 2394 | |
f3c7691e | 2395 | return 0; |
7715b521 | 2396 | } |
1da177e4 | 2397 | |
e1181ee6 | 2398 | static int handle_truncate(struct file *filp) |
7715b521 | 2399 | { |
e1181ee6 | 2400 | struct path *path = &filp->f_path; |
7715b521 AV |
2401 | struct inode *inode = path->dentry->d_inode; |
2402 | int error = get_write_access(inode); | |
2403 | if (error) | |
2404 | return error; | |
2405 | /* | |
2406 | * Refuse to truncate files with mandatory locks held on them. | |
2407 | */ | |
2408 | error = locks_verify_locked(inode); | |
2409 | if (!error) | |
ea0d3ab2 | 2410 | error = security_path_truncate(path); |
7715b521 AV |
2411 | if (!error) { |
2412 | error = do_truncate(path->dentry, 0, | |
2413 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2414 | filp); |
7715b521 AV |
2415 | } |
2416 | put_write_access(inode); | |
acd0c935 | 2417 | return error; |
1da177e4 LT |
2418 | } |
2419 | ||
d57999e1 DH |
2420 | static inline int open_to_namei_flags(int flag) |
2421 | { | |
8a5e929d AV |
2422 | if ((flag & O_ACCMODE) == 3) |
2423 | flag--; | |
d57999e1 DH |
2424 | return flag; |
2425 | } | |
2426 | ||
d18e9008 MS |
2427 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2428 | { | |
2429 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2430 | if (error) | |
2431 | return error; | |
2432 | ||
2433 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2434 | if (error) | |
2435 | return error; | |
2436 | ||
2437 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2438 | } | |
2439 | ||
1acf0af9 DH |
2440 | /* |
2441 | * Attempt to atomically look up, create and open a file from a negative | |
2442 | * dentry. | |
2443 | * | |
2444 | * Returns 0 if successful. The file will have been created and attached to | |
2445 | * @file by the filesystem calling finish_open(). | |
2446 | * | |
2447 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2448 | * caller will need to perform the open themselves. @path will have been | |
2449 | * updated to point to the new dentry. This may be negative. | |
2450 | * | |
2451 | * Returns an error code otherwise. | |
2452 | */ | |
2675a4eb AV |
2453 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2454 | struct path *path, struct file *file, | |
2455 | const struct open_flags *op, | |
64894cf8 | 2456 | bool got_write, bool need_lookup, |
2675a4eb | 2457 | int *opened) |
d18e9008 MS |
2458 | { |
2459 | struct inode *dir = nd->path.dentry->d_inode; | |
2460 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2461 | umode_t mode; | |
2462 | int error; | |
2463 | int acc_mode; | |
d18e9008 MS |
2464 | int create_error = 0; |
2465 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
2466 | ||
2467 | BUG_ON(dentry->d_inode); | |
2468 | ||
2469 | /* Don't create child dentry for a dead directory. */ | |
2470 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2471 | error = -ENOENT; |
d18e9008 MS |
2472 | goto out; |
2473 | } | |
2474 | ||
62b259d8 | 2475 | mode = op->mode; |
d18e9008 MS |
2476 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2477 | mode &= ~current_umask(); | |
2478 | ||
f8310c59 | 2479 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) { |
d18e9008 | 2480 | open_flag &= ~O_TRUNC; |
47237687 | 2481 | *opened |= FILE_CREATED; |
d18e9008 MS |
2482 | } |
2483 | ||
2484 | /* | |
2485 | * Checking write permission is tricky, bacuse we don't know if we are | |
2486 | * going to actually need it: O_CREAT opens should work as long as the | |
2487 | * file exists. But checking existence breaks atomicity. The trick is | |
2488 | * to check access and if not granted clear O_CREAT from the flags. | |
2489 | * | |
2490 | * Another problem is returing the "right" error value (e.g. for an | |
2491 | * O_EXCL open we want to return EEXIST not EROFS). | |
2492 | */ | |
64894cf8 AV |
2493 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2494 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2495 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2496 | /* |
2497 | * No O_CREATE -> atomicity not a requirement -> fall | |
2498 | * back to lookup + open | |
2499 | */ | |
2500 | goto no_open; | |
2501 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2502 | /* Fall back and fail with the right error */ | |
64894cf8 | 2503 | create_error = -EROFS; |
d18e9008 MS |
2504 | goto no_open; |
2505 | } else { | |
2506 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2507 | create_error = -EROFS; |
d18e9008 MS |
2508 | open_flag &= ~O_CREAT; |
2509 | } | |
2510 | } | |
2511 | ||
2512 | if (open_flag & O_CREAT) { | |
38227f78 | 2513 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2514 | if (error) { |
2515 | create_error = error; | |
2516 | if (open_flag & O_EXCL) | |
2517 | goto no_open; | |
2518 | open_flag &= ~O_CREAT; | |
2519 | } | |
2520 | } | |
2521 | ||
2522 | if (nd->flags & LOOKUP_DIRECTORY) | |
2523 | open_flag |= O_DIRECTORY; | |
2524 | ||
30d90494 AV |
2525 | file->f_path.dentry = DENTRY_NOT_SET; |
2526 | file->f_path.mnt = nd->path.mnt; | |
2527 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2528 | opened); |
d9585277 | 2529 | if (error < 0) { |
d9585277 AV |
2530 | if (create_error && error == -ENOENT) |
2531 | error = create_error; | |
d18e9008 MS |
2532 | goto out; |
2533 | } | |
2534 | ||
2535 | acc_mode = op->acc_mode; | |
47237687 | 2536 | if (*opened & FILE_CREATED) { |
d18e9008 MS |
2537 | fsnotify_create(dir, dentry); |
2538 | acc_mode = MAY_OPEN; | |
2539 | } | |
2540 | ||
d9585277 | 2541 | if (error) { /* returned 1, that is */ |
30d90494 | 2542 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2543 | error = -EIO; |
d18e9008 MS |
2544 | goto out; |
2545 | } | |
30d90494 | 2546 | if (file->f_path.dentry) { |
d18e9008 | 2547 | dput(dentry); |
30d90494 | 2548 | dentry = file->f_path.dentry; |
d18e9008 | 2549 | } |
62b2ce96 SW |
2550 | if (create_error && dentry->d_inode == NULL) { |
2551 | error = create_error; | |
2552 | goto out; | |
2553 | } | |
d18e9008 MS |
2554 | goto looked_up; |
2555 | } | |
2556 | ||
2557 | /* | |
2558 | * We didn't have the inode before the open, so check open permission | |
2559 | * here. | |
2560 | */ | |
2675a4eb AV |
2561 | error = may_open(&file->f_path, acc_mode, open_flag); |
2562 | if (error) | |
2563 | fput(file); | |
d18e9008 MS |
2564 | |
2565 | out: | |
2566 | dput(dentry); | |
2675a4eb | 2567 | return error; |
d18e9008 | 2568 | |
d18e9008 MS |
2569 | no_open: |
2570 | if (need_lookup) { | |
72bd866a | 2571 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2572 | if (IS_ERR(dentry)) |
2675a4eb | 2573 | return PTR_ERR(dentry); |
d18e9008 MS |
2574 | |
2575 | if (create_error) { | |
2576 | int open_flag = op->open_flag; | |
2577 | ||
2675a4eb | 2578 | error = create_error; |
d18e9008 MS |
2579 | if ((open_flag & O_EXCL)) { |
2580 | if (!dentry->d_inode) | |
2581 | goto out; | |
2582 | } else if (!dentry->d_inode) { | |
2583 | goto out; | |
2584 | } else if ((open_flag & O_TRUNC) && | |
2585 | S_ISREG(dentry->d_inode->i_mode)) { | |
2586 | goto out; | |
2587 | } | |
2588 | /* will fail later, go on to get the right error */ | |
2589 | } | |
2590 | } | |
2591 | looked_up: | |
2592 | path->dentry = dentry; | |
2593 | path->mnt = nd->path.mnt; | |
2675a4eb | 2594 | return 1; |
d18e9008 MS |
2595 | } |
2596 | ||
d58ffd35 | 2597 | /* |
1acf0af9 | 2598 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2599 | * |
2600 | * Must be called with i_mutex held on parent. | |
2601 | * | |
1acf0af9 DH |
2602 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2603 | * opened. In this case the file will be returned attached to @file. | |
2604 | * | |
2605 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2606 | * and creations will have been performed and the dentry returned in @path will | |
2607 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2608 | * specified then a negative dentry may be returned. | |
2609 | * | |
2610 | * An error code is returned otherwise. | |
2611 | * | |
2612 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2613 | * cleared otherwise prior to returning. | |
d58ffd35 | 2614 | */ |
2675a4eb AV |
2615 | static int lookup_open(struct nameidata *nd, struct path *path, |
2616 | struct file *file, | |
2617 | const struct open_flags *op, | |
64894cf8 | 2618 | bool got_write, int *opened) |
d58ffd35 MS |
2619 | { |
2620 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2621 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2622 | struct dentry *dentry; |
2623 | int error; | |
54ef4872 | 2624 | bool need_lookup; |
d58ffd35 | 2625 | |
47237687 | 2626 | *opened &= ~FILE_CREATED; |
201f956e | 2627 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2628 | if (IS_ERR(dentry)) |
2675a4eb | 2629 | return PTR_ERR(dentry); |
d58ffd35 | 2630 | |
d18e9008 MS |
2631 | /* Cached positive dentry: will open in f_op->open */ |
2632 | if (!need_lookup && dentry->d_inode) | |
2633 | goto out_no_open; | |
2634 | ||
2635 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2636 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2637 | need_lookup, opened); |
d18e9008 MS |
2638 | } |
2639 | ||
54ef4872 MS |
2640 | if (need_lookup) { |
2641 | BUG_ON(dentry->d_inode); | |
2642 | ||
72bd866a | 2643 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2644 | if (IS_ERR(dentry)) |
2675a4eb | 2645 | return PTR_ERR(dentry); |
54ef4872 MS |
2646 | } |
2647 | ||
d58ffd35 MS |
2648 | /* Negative dentry, just create the file */ |
2649 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2650 | umode_t mode = op->mode; | |
2651 | if (!IS_POSIXACL(dir->d_inode)) | |
2652 | mode &= ~current_umask(); | |
2653 | /* | |
2654 | * This write is needed to ensure that a | |
2655 | * rw->ro transition does not occur between | |
2656 | * the time when the file is created and when | |
2657 | * a permanent write count is taken through | |
015c3bbc | 2658 | * the 'struct file' in finish_open(). |
d58ffd35 | 2659 | */ |
64894cf8 AV |
2660 | if (!got_write) { |
2661 | error = -EROFS; | |
d58ffd35 | 2662 | goto out_dput; |
64894cf8 | 2663 | } |
47237687 | 2664 | *opened |= FILE_CREATED; |
d58ffd35 MS |
2665 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2666 | if (error) | |
2667 | goto out_dput; | |
312b63fb AV |
2668 | error = vfs_create(dir->d_inode, dentry, mode, |
2669 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
2670 | if (error) |
2671 | goto out_dput; | |
2672 | } | |
d18e9008 | 2673 | out_no_open: |
d58ffd35 MS |
2674 | path->dentry = dentry; |
2675 | path->mnt = nd->path.mnt; | |
2675a4eb | 2676 | return 1; |
d58ffd35 MS |
2677 | |
2678 | out_dput: | |
2679 | dput(dentry); | |
2675a4eb | 2680 | return error; |
d58ffd35 MS |
2681 | } |
2682 | ||
31e6b01f | 2683 | /* |
fe2d35ff | 2684 | * Handle the last step of open() |
31e6b01f | 2685 | */ |
2675a4eb AV |
2686 | static int do_last(struct nameidata *nd, struct path *path, |
2687 | struct file *file, const struct open_flags *op, | |
669abf4e | 2688 | int *opened, struct filename *name) |
fb1cc555 | 2689 | { |
a1e28038 | 2690 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 2691 | int open_flag = op->open_flag; |
77d660a8 | 2692 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 2693 | bool got_write = false; |
bcda7652 | 2694 | int acc_mode = op->acc_mode; |
a1eb3315 | 2695 | struct inode *inode; |
77d660a8 | 2696 | bool symlink_ok = false; |
16b1c1cd MS |
2697 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
2698 | bool retried = false; | |
16c2cd71 | 2699 | int error; |
1f36f774 | 2700 | |
c3e380b0 AV |
2701 | nd->flags &= ~LOOKUP_PARENT; |
2702 | nd->flags |= op->intent; | |
2703 | ||
1f36f774 AV |
2704 | switch (nd->last_type) { |
2705 | case LAST_DOTDOT: | |
176306f5 | 2706 | case LAST_DOT: |
fe2d35ff AV |
2707 | error = handle_dots(nd, nd->last_type); |
2708 | if (error) | |
2675a4eb | 2709 | return error; |
1f36f774 | 2710 | /* fallthrough */ |
1f36f774 | 2711 | case LAST_ROOT: |
9f1fafee | 2712 | error = complete_walk(nd); |
16c2cd71 | 2713 | if (error) |
2675a4eb | 2714 | return error; |
adb5c247 | 2715 | audit_inode(name, nd->path.dentry, 0); |
ca344a89 | 2716 | if (open_flag & O_CREAT) { |
fe2d35ff | 2717 | error = -EISDIR; |
2675a4eb | 2718 | goto out; |
fe2d35ff | 2719 | } |
e83db167 | 2720 | goto finish_open; |
1f36f774 | 2721 | case LAST_BIND: |
9f1fafee | 2722 | error = complete_walk(nd); |
16c2cd71 | 2723 | if (error) |
2675a4eb | 2724 | return error; |
adb5c247 | 2725 | audit_inode(name, dir, 0); |
e83db167 | 2726 | goto finish_open; |
1f36f774 | 2727 | } |
67ee3ad2 | 2728 | |
ca344a89 | 2729 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
2730 | if (nd->last.name[nd->last.len]) |
2731 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 | 2732 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
77d660a8 | 2733 | symlink_ok = true; |
fe2d35ff | 2734 | /* we _can_ be in RCU mode here */ |
a1eb3315 | 2735 | error = lookup_fast(nd, &nd->last, path, &inode); |
71574865 MS |
2736 | if (likely(!error)) |
2737 | goto finish_lookup; | |
2738 | ||
2739 | if (error < 0) | |
2675a4eb | 2740 | goto out; |
71574865 MS |
2741 | |
2742 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
2743 | } else { |
2744 | /* create side of things */ | |
2745 | /* | |
2746 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
2747 | * has been cleared when we got to the last component we are | |
2748 | * about to look up | |
2749 | */ | |
2750 | error = complete_walk(nd); | |
2751 | if (error) | |
2675a4eb | 2752 | return error; |
fe2d35ff | 2753 | |
adb5c247 | 2754 | audit_inode(name, dir, 0); |
b6183df7 MS |
2755 | error = -EISDIR; |
2756 | /* trailing slashes? */ | |
2757 | if (nd->last.name[nd->last.len]) | |
2675a4eb | 2758 | goto out; |
b6183df7 | 2759 | } |
a2c36b45 | 2760 | |
16b1c1cd | 2761 | retry_lookup: |
64894cf8 AV |
2762 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2763 | error = mnt_want_write(nd->path.mnt); | |
2764 | if (!error) | |
2765 | got_write = true; | |
2766 | /* | |
2767 | * do _not_ fail yet - we might not need that or fail with | |
2768 | * a different error; let lookup_open() decide; we'll be | |
2769 | * dropping this one anyway. | |
2770 | */ | |
2771 | } | |
a1e28038 | 2772 | mutex_lock(&dir->d_inode->i_mutex); |
64894cf8 | 2773 | error = lookup_open(nd, path, file, op, got_write, opened); |
d58ffd35 | 2774 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 2775 | |
2675a4eb AV |
2776 | if (error <= 0) { |
2777 | if (error) | |
d18e9008 MS |
2778 | goto out; |
2779 | ||
47237687 | 2780 | if ((*opened & FILE_CREATED) || |
2675a4eb | 2781 | !S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
77d660a8 | 2782 | will_truncate = false; |
d18e9008 | 2783 | |
adb5c247 | 2784 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
2785 | goto opened; |
2786 | } | |
fb1cc555 | 2787 | |
47237687 | 2788 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 2789 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2790 | open_flag &= ~O_TRUNC; |
77d660a8 | 2791 | will_truncate = false; |
bcda7652 | 2792 | acc_mode = MAY_OPEN; |
d58ffd35 | 2793 | path_to_nameidata(path, nd); |
e83db167 | 2794 | goto finish_open_created; |
fb1cc555 AV |
2795 | } |
2796 | ||
2797 | /* | |
3134f37e | 2798 | * create/update audit record if it already exists. |
fb1cc555 | 2799 | */ |
3134f37e | 2800 | if (path->dentry->d_inode) |
adb5c247 | 2801 | audit_inode(name, path->dentry, 0); |
fb1cc555 | 2802 | |
d18e9008 MS |
2803 | /* |
2804 | * If atomic_open() acquired write access it is dropped now due to | |
2805 | * possible mount and symlink following (this might be optimized away if | |
2806 | * necessary...) | |
2807 | */ | |
64894cf8 | 2808 | if (got_write) { |
d18e9008 | 2809 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 2810 | got_write = false; |
d18e9008 MS |
2811 | } |
2812 | ||
fb1cc555 | 2813 | error = -EEXIST; |
f8310c59 | 2814 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
fb1cc555 AV |
2815 | goto exit_dput; |
2816 | ||
9875cf80 DH |
2817 | error = follow_managed(path, nd->flags); |
2818 | if (error < 0) | |
2819 | goto exit_dput; | |
fb1cc555 | 2820 | |
a3fbbde7 AV |
2821 | if (error) |
2822 | nd->flags |= LOOKUP_JUMPED; | |
2823 | ||
decf3400 MS |
2824 | BUG_ON(nd->flags & LOOKUP_RCU); |
2825 | inode = path->dentry->d_inode; | |
5f5daac1 MS |
2826 | finish_lookup: |
2827 | /* we _can_ be in RCU mode here */ | |
fb1cc555 | 2828 | error = -ENOENT; |
54c33e7f MS |
2829 | if (!inode) { |
2830 | path_to_nameidata(path, nd); | |
2675a4eb | 2831 | goto out; |
54c33e7f | 2832 | } |
9e67f361 | 2833 | |
d45ea867 MS |
2834 | if (should_follow_link(inode, !symlink_ok)) { |
2835 | if (nd->flags & LOOKUP_RCU) { | |
2836 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
2837 | error = -ECHILD; | |
2675a4eb | 2838 | goto out; |
d45ea867 MS |
2839 | } |
2840 | } | |
2841 | BUG_ON(inode != path->dentry->d_inode); | |
2675a4eb | 2842 | return 1; |
d45ea867 | 2843 | } |
fb1cc555 | 2844 | |
16b1c1cd MS |
2845 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { |
2846 | path_to_nameidata(path, nd); | |
2847 | } else { | |
2848 | save_parent.dentry = nd->path.dentry; | |
2849 | save_parent.mnt = mntget(path->mnt); | |
2850 | nd->path.dentry = path->dentry; | |
2851 | ||
2852 | } | |
decf3400 | 2853 | nd->inode = inode; |
a3fbbde7 AV |
2854 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
2855 | error = complete_walk(nd); | |
16b1c1cd MS |
2856 | if (error) { |
2857 | path_put(&save_parent); | |
2675a4eb | 2858 | return error; |
16b1c1cd | 2859 | } |
fb1cc555 | 2860 | error = -EISDIR; |
050ac841 | 2861 | if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) |
2675a4eb | 2862 | goto out; |
af2f5542 MS |
2863 | error = -ENOTDIR; |
2864 | if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) | |
2675a4eb | 2865 | goto out; |
adb5c247 | 2866 | audit_inode(name, nd->path.dentry, 0); |
e83db167 | 2867 | finish_open: |
6c0d46c4 | 2868 | if (!S_ISREG(nd->inode->i_mode)) |
77d660a8 | 2869 | will_truncate = false; |
6c0d46c4 | 2870 | |
0f9d1a10 AV |
2871 | if (will_truncate) { |
2872 | error = mnt_want_write(nd->path.mnt); | |
2873 | if (error) | |
2675a4eb | 2874 | goto out; |
64894cf8 | 2875 | got_write = true; |
0f9d1a10 | 2876 | } |
e83db167 | 2877 | finish_open_created: |
bcda7652 | 2878 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2879 | if (error) |
2675a4eb | 2880 | goto out; |
30d90494 AV |
2881 | file->f_path.mnt = nd->path.mnt; |
2882 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
2883 | if (error) { | |
30d90494 | 2884 | if (error == -EOPENSTALE) |
f60dc3db | 2885 | goto stale_open; |
015c3bbc | 2886 | goto out; |
f60dc3db | 2887 | } |
a8277b9b | 2888 | opened: |
2675a4eb | 2889 | error = open_check_o_direct(file); |
015c3bbc MS |
2890 | if (error) |
2891 | goto exit_fput; | |
2675a4eb | 2892 | error = ima_file_check(file, op->acc_mode); |
aa4caadb MS |
2893 | if (error) |
2894 | goto exit_fput; | |
2895 | ||
2896 | if (will_truncate) { | |
2675a4eb | 2897 | error = handle_truncate(file); |
aa4caadb MS |
2898 | if (error) |
2899 | goto exit_fput; | |
0f9d1a10 | 2900 | } |
ca344a89 | 2901 | out: |
64894cf8 | 2902 | if (got_write) |
0f9d1a10 | 2903 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 2904 | path_put(&save_parent); |
e276ae67 | 2905 | terminate_walk(nd); |
2675a4eb | 2906 | return error; |
fb1cc555 | 2907 | |
fb1cc555 AV |
2908 | exit_dput: |
2909 | path_put_conditional(path, nd); | |
ca344a89 | 2910 | goto out; |
015c3bbc | 2911 | exit_fput: |
2675a4eb AV |
2912 | fput(file); |
2913 | goto out; | |
015c3bbc | 2914 | |
f60dc3db MS |
2915 | stale_open: |
2916 | /* If no saved parent or already retried then can't retry */ | |
2917 | if (!save_parent.dentry || retried) | |
2918 | goto out; | |
2919 | ||
2920 | BUG_ON(save_parent.dentry != dir); | |
2921 | path_put(&nd->path); | |
2922 | nd->path = save_parent; | |
2923 | nd->inode = dir->d_inode; | |
2924 | save_parent.mnt = NULL; | |
2925 | save_parent.dentry = NULL; | |
64894cf8 | 2926 | if (got_write) { |
f60dc3db | 2927 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 2928 | got_write = false; |
f60dc3db MS |
2929 | } |
2930 | retried = true; | |
2931 | goto retry_lookup; | |
fb1cc555 AV |
2932 | } |
2933 | ||
669abf4e | 2934 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 2935 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 2936 | { |
fe2d35ff | 2937 | struct file *base = NULL; |
30d90494 | 2938 | struct file *file; |
9850c056 | 2939 | struct path path; |
47237687 | 2940 | int opened = 0; |
13aab428 | 2941 | int error; |
31e6b01f | 2942 | |
30d90494 AV |
2943 | file = get_empty_filp(); |
2944 | if (!file) | |
31e6b01f NP |
2945 | return ERR_PTR(-ENFILE); |
2946 | ||
30d90494 | 2947 | file->f_flags = op->open_flag; |
31e6b01f | 2948 | |
669abf4e | 2949 | error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 2950 | if (unlikely(error)) |
2675a4eb | 2951 | goto out; |
31e6b01f | 2952 | |
fe2d35ff | 2953 | current->total_link_count = 0; |
669abf4e | 2954 | error = link_path_walk(pathname->name, nd); |
31e6b01f | 2955 | if (unlikely(error)) |
2675a4eb | 2956 | goto out; |
1da177e4 | 2957 | |
2675a4eb AV |
2958 | error = do_last(nd, &path, file, op, &opened, pathname); |
2959 | while (unlikely(error > 0)) { /* trailing symlink */ | |
7b9337aa | 2960 | struct path link = path; |
def4af30 | 2961 | void *cookie; |
574197e0 | 2962 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
2963 | path_put_conditional(&path, nd); |
2964 | path_put(&nd->path); | |
2675a4eb | 2965 | error = -ELOOP; |
40b39136 AV |
2966 | break; |
2967 | } | |
800179c9 KC |
2968 | error = may_follow_link(&link, nd); |
2969 | if (unlikely(error)) | |
2970 | break; | |
73d049a4 AV |
2971 | nd->flags |= LOOKUP_PARENT; |
2972 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 2973 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 2974 | if (unlikely(error)) |
2675a4eb AV |
2975 | break; |
2976 | error = do_last(nd, &path, file, op, &opened, pathname); | |
574197e0 | 2977 | put_link(nd, &link, cookie); |
806b681c | 2978 | } |
10fa8e62 | 2979 | out: |
73d049a4 AV |
2980 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2981 | path_put(&nd->root); | |
fe2d35ff AV |
2982 | if (base) |
2983 | fput(base); | |
2675a4eb AV |
2984 | if (!(opened & FILE_OPENED)) { |
2985 | BUG_ON(!error); | |
30d90494 | 2986 | put_filp(file); |
16b1c1cd | 2987 | } |
2675a4eb AV |
2988 | if (unlikely(error)) { |
2989 | if (error == -EOPENSTALE) { | |
2990 | if (flags & LOOKUP_RCU) | |
2991 | error = -ECHILD; | |
2992 | else | |
2993 | error = -ESTALE; | |
2994 | } | |
2995 | file = ERR_PTR(error); | |
2996 | } | |
2997 | return file; | |
1da177e4 LT |
2998 | } |
2999 | ||
669abf4e | 3000 | struct file *do_filp_open(int dfd, struct filename *pathname, |
13aab428 AV |
3001 | const struct open_flags *op, int flags) |
3002 | { | |
73d049a4 | 3003 | struct nameidata nd; |
13aab428 AV |
3004 | struct file *filp; |
3005 | ||
73d049a4 | 3006 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3007 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3008 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3009 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3010 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
3011 | return filp; |
3012 | } | |
3013 | ||
73d049a4 AV |
3014 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
3015 | const char *name, const struct open_flags *op, int flags) | |
3016 | { | |
3017 | struct nameidata nd; | |
3018 | struct file *file; | |
669abf4e | 3019 | struct filename filename = { .name = name }; |
73d049a4 AV |
3020 | |
3021 | nd.root.mnt = mnt; | |
3022 | nd.root.dentry = dentry; | |
3023 | ||
3024 | flags |= LOOKUP_ROOT; | |
3025 | ||
bcda7652 | 3026 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3027 | return ERR_PTR(-ELOOP); |
3028 | ||
669abf4e | 3029 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3030 | if (unlikely(file == ERR_PTR(-ECHILD))) |
669abf4e | 3031 | file = path_openat(-1, &filename, &nd, op, flags); |
73d049a4 | 3032 | if (unlikely(file == ERR_PTR(-ESTALE))) |
669abf4e | 3033 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); |
73d049a4 AV |
3034 | return file; |
3035 | } | |
3036 | ||
1ac12b4b JL |
3037 | struct dentry *kern_path_create(int dfd, const char *pathname, |
3038 | struct path *path, unsigned int lookup_flags) | |
1da177e4 | 3039 | { |
c663e5d8 | 3040 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3041 | struct nameidata nd; |
c30dabfe | 3042 | int err2; |
1ac12b4b JL |
3043 | int error; |
3044 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3045 | ||
3046 | /* | |
3047 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3048 | * other flags passed in are ignored! | |
3049 | */ | |
3050 | lookup_flags &= LOOKUP_REVAL; | |
3051 | ||
3052 | error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); | |
ed75e95d AV |
3053 | if (error) |
3054 | return ERR_PTR(error); | |
1da177e4 | 3055 | |
c663e5d8 CH |
3056 | /* |
3057 | * Yucky last component or no last component at all? | |
3058 | * (foo/., foo/.., /////) | |
3059 | */ | |
ed75e95d AV |
3060 | if (nd.last_type != LAST_NORM) |
3061 | goto out; | |
3062 | nd.flags &= ~LOOKUP_PARENT; | |
3063 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3064 | |
c30dabfe JK |
3065 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3066 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3067 | /* |
3068 | * Do the final lookup. | |
3069 | */ | |
ed75e95d AV |
3070 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3071 | dentry = lookup_hash(&nd); | |
1da177e4 | 3072 | if (IS_ERR(dentry)) |
a8104a9f | 3073 | goto unlock; |
c663e5d8 | 3074 | |
a8104a9f | 3075 | error = -EEXIST; |
e9baf6e5 | 3076 | if (dentry->d_inode) |
a8104a9f | 3077 | goto fail; |
c663e5d8 CH |
3078 | /* |
3079 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3080 | * From the vfs_mknod() POV we just have a negative dentry - | |
3081 | * all is fine. Let's be bastards - you had / on the end, you've | |
3082 | * been asking for (non-existent) directory. -ENOENT for you. | |
3083 | */ | |
ed75e95d | 3084 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3085 | error = -ENOENT; |
ed75e95d | 3086 | goto fail; |
e9baf6e5 | 3087 | } |
c30dabfe JK |
3088 | if (unlikely(err2)) { |
3089 | error = err2; | |
a8104a9f | 3090 | goto fail; |
c30dabfe | 3091 | } |
ed75e95d | 3092 | *path = nd.path; |
1da177e4 | 3093 | return dentry; |
1da177e4 | 3094 | fail: |
a8104a9f AV |
3095 | dput(dentry); |
3096 | dentry = ERR_PTR(error); | |
3097 | unlock: | |
ed75e95d | 3098 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3099 | if (!err2) |
3100 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3101 | out: |
3102 | path_put(&nd.path); | |
1da177e4 LT |
3103 | return dentry; |
3104 | } | |
dae6ad8f AV |
3105 | EXPORT_SYMBOL(kern_path_create); |
3106 | ||
921a1650 AV |
3107 | void done_path_create(struct path *path, struct dentry *dentry) |
3108 | { | |
3109 | dput(dentry); | |
3110 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3111 | mnt_drop_write(path->mnt); |
921a1650 AV |
3112 | path_put(path); |
3113 | } | |
3114 | EXPORT_SYMBOL(done_path_create); | |
3115 | ||
1ac12b4b JL |
3116 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3117 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3118 | { |
91a27b2a | 3119 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3120 | struct dentry *res; |
3121 | if (IS_ERR(tmp)) | |
3122 | return ERR_CAST(tmp); | |
1ac12b4b | 3123 | res = kern_path_create(dfd, tmp->name, path, lookup_flags); |
dae6ad8f AV |
3124 | putname(tmp); |
3125 | return res; | |
3126 | } | |
3127 | EXPORT_SYMBOL(user_path_create); | |
3128 | ||
1a67aafb | 3129 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3130 | { |
a95164d9 | 3131 | int error = may_create(dir, dentry); |
1da177e4 LT |
3132 | |
3133 | if (error) | |
3134 | return error; | |
3135 | ||
975d6b39 | 3136 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3137 | return -EPERM; |
3138 | ||
acfa4380 | 3139 | if (!dir->i_op->mknod) |
1da177e4 LT |
3140 | return -EPERM; |
3141 | ||
08ce5f16 SH |
3142 | error = devcgroup_inode_mknod(mode, dev); |
3143 | if (error) | |
3144 | return error; | |
3145 | ||
1da177e4 LT |
3146 | error = security_inode_mknod(dir, dentry, mode, dev); |
3147 | if (error) | |
3148 | return error; | |
3149 | ||
1da177e4 | 3150 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3151 | if (!error) |
f38aa942 | 3152 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3153 | return error; |
3154 | } | |
3155 | ||
f69aac00 | 3156 | static int may_mknod(umode_t mode) |
463c3197 DH |
3157 | { |
3158 | switch (mode & S_IFMT) { | |
3159 | case S_IFREG: | |
3160 | case S_IFCHR: | |
3161 | case S_IFBLK: | |
3162 | case S_IFIFO: | |
3163 | case S_IFSOCK: | |
3164 | case 0: /* zero mode translates to S_IFREG */ | |
3165 | return 0; | |
3166 | case S_IFDIR: | |
3167 | return -EPERM; | |
3168 | default: | |
3169 | return -EINVAL; | |
3170 | } | |
3171 | } | |
3172 | ||
8208a22b | 3173 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3174 | unsigned, dev) |
1da177e4 | 3175 | { |
2ad94ae6 | 3176 | struct dentry *dentry; |
dae6ad8f AV |
3177 | struct path path; |
3178 | int error; | |
972567f1 | 3179 | unsigned int lookup_flags = 0; |
1da177e4 | 3180 | |
8e4bfca1 AV |
3181 | error = may_mknod(mode); |
3182 | if (error) | |
3183 | return error; | |
972567f1 JL |
3184 | retry: |
3185 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3186 | if (IS_ERR(dentry)) |
3187 | return PTR_ERR(dentry); | |
2ad94ae6 | 3188 | |
dae6ad8f | 3189 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3190 | mode &= ~current_umask(); |
dae6ad8f | 3191 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3192 | if (error) |
a8104a9f | 3193 | goto out; |
463c3197 | 3194 | switch (mode & S_IFMT) { |
1da177e4 | 3195 | case 0: case S_IFREG: |
312b63fb | 3196 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3197 | break; |
3198 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3199 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3200 | new_decode_dev(dev)); |
3201 | break; | |
3202 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3203 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3204 | break; |
1da177e4 | 3205 | } |
a8104a9f | 3206 | out: |
921a1650 | 3207 | done_path_create(&path, dentry); |
972567f1 JL |
3208 | if (retry_estale(error, lookup_flags)) { |
3209 | lookup_flags |= LOOKUP_REVAL; | |
3210 | goto retry; | |
3211 | } | |
1da177e4 LT |
3212 | return error; |
3213 | } | |
3214 | ||
8208a22b | 3215 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3216 | { |
3217 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3218 | } | |
3219 | ||
18bb1db3 | 3220 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3221 | { |
a95164d9 | 3222 | int error = may_create(dir, dentry); |
8de52778 | 3223 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3224 | |
3225 | if (error) | |
3226 | return error; | |
3227 | ||
acfa4380 | 3228 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3229 | return -EPERM; |
3230 | ||
3231 | mode &= (S_IRWXUGO|S_ISVTX); | |
3232 | error = security_inode_mkdir(dir, dentry, mode); | |
3233 | if (error) | |
3234 | return error; | |
3235 | ||
8de52778 AV |
3236 | if (max_links && dir->i_nlink >= max_links) |
3237 | return -EMLINK; | |
3238 | ||
1da177e4 | 3239 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3240 | if (!error) |
f38aa942 | 3241 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3242 | return error; |
3243 | } | |
3244 | ||
a218d0fd | 3245 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3246 | { |
6902d925 | 3247 | struct dentry *dentry; |
dae6ad8f AV |
3248 | struct path path; |
3249 | int error; | |
b76d8b82 | 3250 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3251 | |
b76d8b82 JL |
3252 | retry: |
3253 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3254 | if (IS_ERR(dentry)) |
dae6ad8f | 3255 | return PTR_ERR(dentry); |
1da177e4 | 3256 | |
dae6ad8f | 3257 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3258 | mode &= ~current_umask(); |
dae6ad8f | 3259 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3260 | if (!error) |
3261 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3262 | done_path_create(&path, dentry); |
b76d8b82 JL |
3263 | if (retry_estale(error, lookup_flags)) { |
3264 | lookup_flags |= LOOKUP_REVAL; | |
3265 | goto retry; | |
3266 | } | |
1da177e4 LT |
3267 | return error; |
3268 | } | |
3269 | ||
a218d0fd | 3270 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3271 | { |
3272 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3273 | } | |
3274 | ||
1da177e4 | 3275 | /* |
a71905f0 | 3276 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3277 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3278 | * dentry, and if that is true (possibly after pruning the dcache), |
3279 | * then we drop the dentry now. | |
1da177e4 LT |
3280 | * |
3281 | * A low-level filesystem can, if it choses, legally | |
3282 | * do a | |
3283 | * | |
3284 | * if (!d_unhashed(dentry)) | |
3285 | * return -EBUSY; | |
3286 | * | |
3287 | * if it cannot handle the case of removing a directory | |
3288 | * that is still in use by something else.. | |
3289 | */ | |
3290 | void dentry_unhash(struct dentry *dentry) | |
3291 | { | |
dc168427 | 3292 | shrink_dcache_parent(dentry); |
1da177e4 | 3293 | spin_lock(&dentry->d_lock); |
64252c75 | 3294 | if (dentry->d_count == 1) |
1da177e4 LT |
3295 | __d_drop(dentry); |
3296 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
3297 | } |
3298 | ||
3299 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3300 | { | |
3301 | int error = may_delete(dir, dentry, 1); | |
3302 | ||
3303 | if (error) | |
3304 | return error; | |
3305 | ||
acfa4380 | 3306 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3307 | return -EPERM; |
3308 | ||
1d2ef590 | 3309 | dget(dentry); |
1b1dcc1b | 3310 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3311 | |
3312 | error = -EBUSY; | |
1da177e4 | 3313 | if (d_mountpoint(dentry)) |
912dbc15 SW |
3314 | goto out; |
3315 | ||
3316 | error = security_inode_rmdir(dir, dentry); | |
3317 | if (error) | |
3318 | goto out; | |
3319 | ||
3cebde24 | 3320 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3321 | error = dir->i_op->rmdir(dir, dentry); |
3322 | if (error) | |
3323 | goto out; | |
3324 | ||
3325 | dentry->d_inode->i_flags |= S_DEAD; | |
3326 | dont_mount(dentry); | |
3327 | ||
3328 | out: | |
1b1dcc1b | 3329 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3330 | dput(dentry); |
912dbc15 | 3331 | if (!error) |
1da177e4 | 3332 | d_delete(dentry); |
1da177e4 LT |
3333 | return error; |
3334 | } | |
3335 | ||
5590ff0d | 3336 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3337 | { |
3338 | int error = 0; | |
91a27b2a | 3339 | struct filename *name; |
1da177e4 LT |
3340 | struct dentry *dentry; |
3341 | struct nameidata nd; | |
c6ee9206 JL |
3342 | unsigned int lookup_flags = 0; |
3343 | retry: | |
3344 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3345 | if (IS_ERR(name)) |
3346 | return PTR_ERR(name); | |
1da177e4 LT |
3347 | |
3348 | switch(nd.last_type) { | |
0612d9fb OH |
3349 | case LAST_DOTDOT: |
3350 | error = -ENOTEMPTY; | |
3351 | goto exit1; | |
3352 | case LAST_DOT: | |
3353 | error = -EINVAL; | |
3354 | goto exit1; | |
3355 | case LAST_ROOT: | |
3356 | error = -EBUSY; | |
3357 | goto exit1; | |
1da177e4 | 3358 | } |
0612d9fb OH |
3359 | |
3360 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3361 | error = mnt_want_write(nd.path.mnt); |
3362 | if (error) | |
3363 | goto exit1; | |
0612d9fb | 3364 | |
4ac91378 | 3365 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3366 | dentry = lookup_hash(&nd); |
1da177e4 | 3367 | error = PTR_ERR(dentry); |
6902d925 DH |
3368 | if (IS_ERR(dentry)) |
3369 | goto exit2; | |
e6bc45d6 TT |
3370 | if (!dentry->d_inode) { |
3371 | error = -ENOENT; | |
3372 | goto exit3; | |
3373 | } | |
be6d3e56 KT |
3374 | error = security_path_rmdir(&nd.path, dentry); |
3375 | if (error) | |
c30dabfe | 3376 | goto exit3; |
4ac91378 | 3377 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
0622753b | 3378 | exit3: |
6902d925 DH |
3379 | dput(dentry); |
3380 | exit2: | |
4ac91378 | 3381 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe | 3382 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3383 | exit1: |
1d957f9b | 3384 | path_put(&nd.path); |
1da177e4 | 3385 | putname(name); |
c6ee9206 JL |
3386 | if (retry_estale(error, lookup_flags)) { |
3387 | lookup_flags |= LOOKUP_REVAL; | |
3388 | goto retry; | |
3389 | } | |
1da177e4 LT |
3390 | return error; |
3391 | } | |
3392 | ||
3cdad428 | 3393 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3394 | { |
3395 | return do_rmdir(AT_FDCWD, pathname); | |
3396 | } | |
3397 | ||
1da177e4 LT |
3398 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
3399 | { | |
3400 | int error = may_delete(dir, dentry, 0); | |
3401 | ||
3402 | if (error) | |
3403 | return error; | |
3404 | ||
acfa4380 | 3405 | if (!dir->i_op->unlink) |
1da177e4 LT |
3406 | return -EPERM; |
3407 | ||
1b1dcc1b | 3408 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
3409 | if (d_mountpoint(dentry)) |
3410 | error = -EBUSY; | |
3411 | else { | |
3412 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3413 | if (!error) { |
1da177e4 | 3414 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 3415 | if (!error) |
d83c49f3 | 3416 | dont_mount(dentry); |
bec1052e | 3417 | } |
1da177e4 | 3418 | } |
1b1dcc1b | 3419 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
3420 | |
3421 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3422 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 3423 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 3424 | d_delete(dentry); |
1da177e4 | 3425 | } |
0eeca283 | 3426 | |
1da177e4 LT |
3427 | return error; |
3428 | } | |
3429 | ||
3430 | /* | |
3431 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3432 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3433 | * writeout happening, and we don't want to prevent access to the directory |
3434 | * while waiting on the I/O. | |
3435 | */ | |
5590ff0d | 3436 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3437 | { |
2ad94ae6 | 3438 | int error; |
91a27b2a | 3439 | struct filename *name; |
1da177e4 LT |
3440 | struct dentry *dentry; |
3441 | struct nameidata nd; | |
3442 | struct inode *inode = NULL; | |
5d18f813 JL |
3443 | unsigned int lookup_flags = 0; |
3444 | retry: | |
3445 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3446 | if (IS_ERR(name)) |
3447 | return PTR_ERR(name); | |
2ad94ae6 | 3448 | |
1da177e4 LT |
3449 | error = -EISDIR; |
3450 | if (nd.last_type != LAST_NORM) | |
3451 | goto exit1; | |
0612d9fb OH |
3452 | |
3453 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3454 | error = mnt_want_write(nd.path.mnt); |
3455 | if (error) | |
3456 | goto exit1; | |
0612d9fb | 3457 | |
4ac91378 | 3458 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3459 | dentry = lookup_hash(&nd); |
1da177e4 LT |
3460 | error = PTR_ERR(dentry); |
3461 | if (!IS_ERR(dentry)) { | |
3462 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
3463 | if (nd.last.name[nd.last.len]) |
3464 | goto slashes; | |
1da177e4 | 3465 | inode = dentry->d_inode; |
50338b88 | 3466 | if (!inode) |
e6bc45d6 TT |
3467 | goto slashes; |
3468 | ihold(inode); | |
be6d3e56 KT |
3469 | error = security_path_unlink(&nd.path, dentry); |
3470 | if (error) | |
c30dabfe | 3471 | goto exit2; |
4ac91378 | 3472 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
c30dabfe | 3473 | exit2: |
1da177e4 LT |
3474 | dput(dentry); |
3475 | } | |
4ac91378 | 3476 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3477 | if (inode) |
3478 | iput(inode); /* truncate the inode here */ | |
c30dabfe | 3479 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3480 | exit1: |
1d957f9b | 3481 | path_put(&nd.path); |
1da177e4 | 3482 | putname(name); |
5d18f813 JL |
3483 | if (retry_estale(error, lookup_flags)) { |
3484 | lookup_flags |= LOOKUP_REVAL; | |
3485 | inode = NULL; | |
3486 | goto retry; | |
3487 | } | |
1da177e4 LT |
3488 | return error; |
3489 | ||
3490 | slashes: | |
3491 | error = !dentry->d_inode ? -ENOENT : | |
3492 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
3493 | goto exit2; | |
3494 | } | |
3495 | ||
2e4d0924 | 3496 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3497 | { |
3498 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3499 | return -EINVAL; | |
3500 | ||
3501 | if (flag & AT_REMOVEDIR) | |
3502 | return do_rmdir(dfd, pathname); | |
3503 | ||
3504 | return do_unlinkat(dfd, pathname); | |
3505 | } | |
3506 | ||
3480b257 | 3507 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3508 | { |
3509 | return do_unlinkat(AT_FDCWD, pathname); | |
3510 | } | |
3511 | ||
db2e747b | 3512 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3513 | { |
a95164d9 | 3514 | int error = may_create(dir, dentry); |
1da177e4 LT |
3515 | |
3516 | if (error) | |
3517 | return error; | |
3518 | ||
acfa4380 | 3519 | if (!dir->i_op->symlink) |
1da177e4 LT |
3520 | return -EPERM; |
3521 | ||
3522 | error = security_inode_symlink(dir, dentry, oldname); | |
3523 | if (error) | |
3524 | return error; | |
3525 | ||
1da177e4 | 3526 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3527 | if (!error) |
f38aa942 | 3528 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3529 | return error; |
3530 | } | |
3531 | ||
2e4d0924 HC |
3532 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3533 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3534 | { |
2ad94ae6 | 3535 | int error; |
91a27b2a | 3536 | struct filename *from; |
6902d925 | 3537 | struct dentry *dentry; |
dae6ad8f | 3538 | struct path path; |
f46d3567 | 3539 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3540 | |
3541 | from = getname(oldname); | |
2ad94ae6 | 3542 | if (IS_ERR(from)) |
1da177e4 | 3543 | return PTR_ERR(from); |
f46d3567 JL |
3544 | retry: |
3545 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3546 | error = PTR_ERR(dentry); |
3547 | if (IS_ERR(dentry)) | |
dae6ad8f | 3548 | goto out_putname; |
6902d925 | 3549 | |
91a27b2a | 3550 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3551 | if (!error) |
91a27b2a | 3552 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3553 | done_path_create(&path, dentry); |
f46d3567 JL |
3554 | if (retry_estale(error, lookup_flags)) { |
3555 | lookup_flags |= LOOKUP_REVAL; | |
3556 | goto retry; | |
3557 | } | |
6902d925 | 3558 | out_putname: |
1da177e4 LT |
3559 | putname(from); |
3560 | return error; | |
3561 | } | |
3562 | ||
3480b257 | 3563 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3564 | { |
3565 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3566 | } | |
3567 | ||
1da177e4 LT |
3568 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
3569 | { | |
3570 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 3571 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3572 | int error; |
3573 | ||
3574 | if (!inode) | |
3575 | return -ENOENT; | |
3576 | ||
a95164d9 | 3577 | error = may_create(dir, new_dentry); |
1da177e4 LT |
3578 | if (error) |
3579 | return error; | |
3580 | ||
3581 | if (dir->i_sb != inode->i_sb) | |
3582 | return -EXDEV; | |
3583 | ||
3584 | /* | |
3585 | * A link to an append-only or immutable file cannot be created. | |
3586 | */ | |
3587 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
3588 | return -EPERM; | |
acfa4380 | 3589 | if (!dir->i_op->link) |
1da177e4 | 3590 | return -EPERM; |
7e79eedb | 3591 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
3592 | return -EPERM; |
3593 | ||
3594 | error = security_inode_link(old_dentry, dir, new_dentry); | |
3595 | if (error) | |
3596 | return error; | |
3597 | ||
7e79eedb | 3598 | mutex_lock(&inode->i_mutex); |
aae8a97d AK |
3599 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
3600 | if (inode->i_nlink == 0) | |
3601 | error = -ENOENT; | |
8de52778 AV |
3602 | else if (max_links && inode->i_nlink >= max_links) |
3603 | error = -EMLINK; | |
aae8a97d AK |
3604 | else |
3605 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
7e79eedb | 3606 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 3607 | if (!error) |
7e79eedb | 3608 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
3609 | return error; |
3610 | } | |
3611 | ||
3612 | /* | |
3613 | * Hardlinks are often used in delicate situations. We avoid | |
3614 | * security-related surprises by not following symlinks on the | |
3615 | * newname. --KAB | |
3616 | * | |
3617 | * We don't follow them on the oldname either to be compatible | |
3618 | * with linux 2.0, and to avoid hard-linking to directories | |
3619 | * and other special files. --ADM | |
3620 | */ | |
2e4d0924 HC |
3621 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3622 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
3623 | { |
3624 | struct dentry *new_dentry; | |
dae6ad8f | 3625 | struct path old_path, new_path; |
11a7b371 | 3626 | int how = 0; |
1da177e4 | 3627 | int error; |
1da177e4 | 3628 | |
11a7b371 | 3629 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 3630 | return -EINVAL; |
11a7b371 AK |
3631 | /* |
3632 | * To use null names we require CAP_DAC_READ_SEARCH | |
3633 | * This ensures that not everyone will be able to create | |
3634 | * handlink using the passed filedescriptor. | |
3635 | */ | |
3636 | if (flags & AT_EMPTY_PATH) { | |
3637 | if (!capable(CAP_DAC_READ_SEARCH)) | |
3638 | return -ENOENT; | |
3639 | how = LOOKUP_EMPTY; | |
3640 | } | |
3641 | ||
3642 | if (flags & AT_SYMLINK_FOLLOW) | |
3643 | how |= LOOKUP_FOLLOW; | |
442e31ca | 3644 | retry: |
11a7b371 | 3645 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 3646 | if (error) |
2ad94ae6 AV |
3647 | return error; |
3648 | ||
442e31ca JL |
3649 | new_dentry = user_path_create(newdfd, newname, &new_path, |
3650 | (how & LOOKUP_REVAL)); | |
1da177e4 | 3651 | error = PTR_ERR(new_dentry); |
6902d925 | 3652 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
3653 | goto out; |
3654 | ||
3655 | error = -EXDEV; | |
3656 | if (old_path.mnt != new_path.mnt) | |
3657 | goto out_dput; | |
800179c9 KC |
3658 | error = may_linkat(&old_path); |
3659 | if (unlikely(error)) | |
3660 | goto out_dput; | |
dae6ad8f | 3661 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 3662 | if (error) |
a8104a9f | 3663 | goto out_dput; |
dae6ad8f | 3664 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
75c3f29d | 3665 | out_dput: |
921a1650 | 3666 | done_path_create(&new_path, new_dentry); |
442e31ca JL |
3667 | if (retry_estale(error, how)) { |
3668 | how |= LOOKUP_REVAL; | |
3669 | goto retry; | |
3670 | } | |
1da177e4 | 3671 | out: |
2d8f3038 | 3672 | path_put(&old_path); |
1da177e4 LT |
3673 | |
3674 | return error; | |
3675 | } | |
3676 | ||
3480b257 | 3677 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 3678 | { |
c04030e1 | 3679 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
3680 | } |
3681 | ||
1da177e4 LT |
3682 | /* |
3683 | * The worst of all namespace operations - renaming directory. "Perverted" | |
3684 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
3685 | * Problems: | |
3686 | * a) we can get into loop creation. Check is done in is_subdir(). | |
3687 | * b) race potential - two innocent renames can create a loop together. | |
3688 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 3689 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
3690 | * story. |
3691 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 3692 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
3693 | * whether the target exists). Solution: try to be smart with locking |
3694 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 3695 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
3696 | * move will be locked. Thus we can rank directories by the tree |
3697 | * (ancestors first) and rank all non-directories after them. | |
3698 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 3699 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
3700 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
3701 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
3702 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 3703 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 3704 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 3705 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 3706 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
3707 | * locking]. |
3708 | */ | |
75c96f85 AB |
3709 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
3710 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
3711 | { |
3712 | int error = 0; | |
9055cba7 | 3713 | struct inode *target = new_dentry->d_inode; |
8de52778 | 3714 | unsigned max_links = new_dir->i_sb->s_max_links; |
1da177e4 LT |
3715 | |
3716 | /* | |
3717 | * If we are going to change the parent - check write permissions, | |
3718 | * we'll need to flip '..'. | |
3719 | */ | |
3720 | if (new_dir != old_dir) { | |
f419a2e3 | 3721 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
3722 | if (error) |
3723 | return error; | |
3724 | } | |
3725 | ||
3726 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3727 | if (error) | |
3728 | return error; | |
3729 | ||
1d2ef590 | 3730 | dget(new_dentry); |
d83c49f3 | 3731 | if (target) |
1b1dcc1b | 3732 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
3733 | |
3734 | error = -EBUSY; | |
3735 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
3736 | goto out; | |
3737 | ||
8de52778 AV |
3738 | error = -EMLINK; |
3739 | if (max_links && !target && new_dir != old_dir && | |
3740 | new_dir->i_nlink >= max_links) | |
3741 | goto out; | |
3742 | ||
3cebde24 SW |
3743 | if (target) |
3744 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
3745 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3746 | if (error) | |
3747 | goto out; | |
3748 | ||
1da177e4 | 3749 | if (target) { |
9055cba7 SW |
3750 | target->i_flags |= S_DEAD; |
3751 | dont_mount(new_dentry); | |
1da177e4 | 3752 | } |
9055cba7 SW |
3753 | out: |
3754 | if (target) | |
3755 | mutex_unlock(&target->i_mutex); | |
1d2ef590 | 3756 | dput(new_dentry); |
e31e14ec | 3757 | if (!error) |
349457cc MF |
3758 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3759 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
3760 | return error; |
3761 | } | |
3762 | ||
75c96f85 AB |
3763 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
3764 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 3765 | { |
51892bbb | 3766 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3767 | int error; |
3768 | ||
3769 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3770 | if (error) | |
3771 | return error; | |
3772 | ||
3773 | dget(new_dentry); | |
1da177e4 | 3774 | if (target) |
1b1dcc1b | 3775 | mutex_lock(&target->i_mutex); |
51892bbb SW |
3776 | |
3777 | error = -EBUSY; | |
1da177e4 | 3778 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
3779 | goto out; |
3780 | ||
3781 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
3782 | if (error) | |
3783 | goto out; | |
3784 | ||
3785 | if (target) | |
3786 | dont_mount(new_dentry); | |
3787 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
3788 | d_move(old_dentry, new_dentry); | |
3789 | out: | |
1da177e4 | 3790 | if (target) |
1b1dcc1b | 3791 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3792 | dput(new_dentry); |
3793 | return error; | |
3794 | } | |
3795 | ||
3796 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
3797 | struct inode *new_dir, struct dentry *new_dentry) | |
3798 | { | |
3799 | int error; | |
3800 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 3801 | const unsigned char *old_name; |
1da177e4 LT |
3802 | |
3803 | if (old_dentry->d_inode == new_dentry->d_inode) | |
3804 | return 0; | |
3805 | ||
3806 | error = may_delete(old_dir, old_dentry, is_dir); | |
3807 | if (error) | |
3808 | return error; | |
3809 | ||
3810 | if (!new_dentry->d_inode) | |
a95164d9 | 3811 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
3812 | else |
3813 | error = may_delete(new_dir, new_dentry, is_dir); | |
3814 | if (error) | |
3815 | return error; | |
3816 | ||
acfa4380 | 3817 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3818 | return -EPERM; |
3819 | ||
0eeca283 RL |
3820 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3821 | ||
1da177e4 LT |
3822 | if (is_dir) |
3823 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3824 | else | |
3825 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3826 | if (!error) |
3827 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3828 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3829 | fsnotify_oldname_free(old_name); |
3830 | ||
1da177e4 LT |
3831 | return error; |
3832 | } | |
3833 | ||
2e4d0924 HC |
3834 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3835 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3836 | { |
2ad94ae6 AV |
3837 | struct dentry *old_dir, *new_dir; |
3838 | struct dentry *old_dentry, *new_dentry; | |
3839 | struct dentry *trap; | |
1da177e4 | 3840 | struct nameidata oldnd, newnd; |
91a27b2a JL |
3841 | struct filename *from; |
3842 | struct filename *to; | |
c6a94284 JL |
3843 | unsigned int lookup_flags = 0; |
3844 | bool should_retry = false; | |
2ad94ae6 | 3845 | int error; |
c6a94284 JL |
3846 | retry: |
3847 | from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); | |
91a27b2a JL |
3848 | if (IS_ERR(from)) { |
3849 | error = PTR_ERR(from); | |
1da177e4 | 3850 | goto exit; |
91a27b2a | 3851 | } |
1da177e4 | 3852 | |
c6a94284 | 3853 | to = user_path_parent(newdfd, newname, &newnd, lookup_flags); |
91a27b2a JL |
3854 | if (IS_ERR(to)) { |
3855 | error = PTR_ERR(to); | |
1da177e4 | 3856 | goto exit1; |
91a27b2a | 3857 | } |
1da177e4 LT |
3858 | |
3859 | error = -EXDEV; | |
4ac91378 | 3860 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3861 | goto exit2; |
3862 | ||
4ac91378 | 3863 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3864 | error = -EBUSY; |
3865 | if (oldnd.last_type != LAST_NORM) | |
3866 | goto exit2; | |
3867 | ||
4ac91378 | 3868 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3869 | if (newnd.last_type != LAST_NORM) |
3870 | goto exit2; | |
3871 | ||
c30dabfe JK |
3872 | error = mnt_want_write(oldnd.path.mnt); |
3873 | if (error) | |
3874 | goto exit2; | |
3875 | ||
0612d9fb OH |
3876 | oldnd.flags &= ~LOOKUP_PARENT; |
3877 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3878 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3879 | |
1da177e4 LT |
3880 | trap = lock_rename(new_dir, old_dir); |
3881 | ||
49705b77 | 3882 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3883 | error = PTR_ERR(old_dentry); |
3884 | if (IS_ERR(old_dentry)) | |
3885 | goto exit3; | |
3886 | /* source must exist */ | |
3887 | error = -ENOENT; | |
3888 | if (!old_dentry->d_inode) | |
3889 | goto exit4; | |
3890 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3891 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3892 | error = -ENOTDIR; | |
3893 | if (oldnd.last.name[oldnd.last.len]) | |
3894 | goto exit4; | |
3895 | if (newnd.last.name[newnd.last.len]) | |
3896 | goto exit4; | |
3897 | } | |
3898 | /* source should not be ancestor of target */ | |
3899 | error = -EINVAL; | |
3900 | if (old_dentry == trap) | |
3901 | goto exit4; | |
49705b77 | 3902 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3903 | error = PTR_ERR(new_dentry); |
3904 | if (IS_ERR(new_dentry)) | |
3905 | goto exit4; | |
3906 | /* target should not be an ancestor of source */ | |
3907 | error = -ENOTEMPTY; | |
3908 | if (new_dentry == trap) | |
3909 | goto exit5; | |
3910 | ||
be6d3e56 KT |
3911 | error = security_path_rename(&oldnd.path, old_dentry, |
3912 | &newnd.path, new_dentry); | |
3913 | if (error) | |
c30dabfe | 3914 | goto exit5; |
1da177e4 LT |
3915 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3916 | new_dir->d_inode, new_dentry); | |
3917 | exit5: | |
3918 | dput(new_dentry); | |
3919 | exit4: | |
3920 | dput(old_dentry); | |
3921 | exit3: | |
3922 | unlock_rename(new_dir, old_dir); | |
c30dabfe | 3923 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 | 3924 | exit2: |
c6a94284 JL |
3925 | if (retry_estale(error, lookup_flags)) |
3926 | should_retry = true; | |
1d957f9b | 3927 | path_put(&newnd.path); |
2ad94ae6 | 3928 | putname(to); |
1da177e4 | 3929 | exit1: |
1d957f9b | 3930 | path_put(&oldnd.path); |
1da177e4 | 3931 | putname(from); |
c6a94284 JL |
3932 | if (should_retry) { |
3933 | should_retry = false; | |
3934 | lookup_flags |= LOOKUP_REVAL; | |
3935 | goto retry; | |
3936 | } | |
2ad94ae6 | 3937 | exit: |
1da177e4 LT |
3938 | return error; |
3939 | } | |
3940 | ||
a26eab24 | 3941 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3942 | { |
3943 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
3944 | } | |
3945 | ||
1da177e4 LT |
3946 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3947 | { | |
3948 | int len; | |
3949 | ||
3950 | len = PTR_ERR(link); | |
3951 | if (IS_ERR(link)) | |
3952 | goto out; | |
3953 | ||
3954 | len = strlen(link); | |
3955 | if (len > (unsigned) buflen) | |
3956 | len = buflen; | |
3957 | if (copy_to_user(buffer, link, len)) | |
3958 | len = -EFAULT; | |
3959 | out: | |
3960 | return len; | |
3961 | } | |
3962 | ||
3963 | /* | |
3964 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
3965 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
3966 | * using) it for any given inode is up to filesystem. | |
3967 | */ | |
3968 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3969 | { | |
3970 | struct nameidata nd; | |
cc314eef | 3971 | void *cookie; |
694a1764 | 3972 | int res; |
cc314eef | 3973 | |
1da177e4 | 3974 | nd.depth = 0; |
cc314eef | 3975 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
3976 | if (IS_ERR(cookie)) |
3977 | return PTR_ERR(cookie); | |
3978 | ||
3979 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
3980 | if (dentry->d_inode->i_op->put_link) | |
3981 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
3982 | return res; | |
1da177e4 LT |
3983 | } |
3984 | ||
3985 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
3986 | { | |
3987 | return __vfs_follow_link(nd, link); | |
3988 | } | |
3989 | ||
3990 | /* get the link contents into pagecache */ | |
3991 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
3992 | { | |
ebd09abb DG |
3993 | char *kaddr; |
3994 | struct page *page; | |
1da177e4 | 3995 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 3996 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 3997 | if (IS_ERR(page)) |
6fe6900e | 3998 | return (char*)page; |
1da177e4 | 3999 | *ppage = page; |
ebd09abb DG |
4000 | kaddr = kmap(page); |
4001 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4002 | return kaddr; | |
1da177e4 LT |
4003 | } |
4004 | ||
4005 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4006 | { | |
4007 | struct page *page = NULL; | |
4008 | char *s = page_getlink(dentry, &page); | |
4009 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
4010 | if (page) { | |
4011 | kunmap(page); | |
4012 | page_cache_release(page); | |
4013 | } | |
4014 | return res; | |
4015 | } | |
4016 | ||
cc314eef | 4017 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 4018 | { |
cc314eef | 4019 | struct page *page = NULL; |
1da177e4 | 4020 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 4021 | return page; |
1da177e4 LT |
4022 | } |
4023 | ||
cc314eef | 4024 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 4025 | { |
cc314eef LT |
4026 | struct page *page = cookie; |
4027 | ||
4028 | if (page) { | |
1da177e4 LT |
4029 | kunmap(page); |
4030 | page_cache_release(page); | |
1da177e4 LT |
4031 | } |
4032 | } | |
4033 | ||
54566b2c NP |
4034 | /* |
4035 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4036 | */ | |
4037 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4038 | { |
4039 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4040 | struct page *page; |
afddba49 | 4041 | void *fsdata; |
beb497ab | 4042 | int err; |
1da177e4 | 4043 | char *kaddr; |
54566b2c NP |
4044 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4045 | if (nofs) | |
4046 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4047 | |
7e53cac4 | 4048 | retry: |
afddba49 | 4049 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4050 | flags, &page, &fsdata); |
1da177e4 | 4051 | if (err) |
afddba49 NP |
4052 | goto fail; |
4053 | ||
e8e3c3d6 | 4054 | kaddr = kmap_atomic(page); |
1da177e4 | 4055 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4056 | kunmap_atomic(kaddr); |
afddba49 NP |
4057 | |
4058 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4059 | page, fsdata); | |
1da177e4 LT |
4060 | if (err < 0) |
4061 | goto fail; | |
afddba49 NP |
4062 | if (err < len-1) |
4063 | goto retry; | |
4064 | ||
1da177e4 LT |
4065 | mark_inode_dirty(inode); |
4066 | return 0; | |
1da177e4 LT |
4067 | fail: |
4068 | return err; | |
4069 | } | |
4070 | ||
0adb25d2 KK |
4071 | int page_symlink(struct inode *inode, const char *symname, int len) |
4072 | { | |
4073 | return __page_symlink(inode, symname, len, | |
54566b2c | 4074 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
4075 | } |
4076 | ||
92e1d5be | 4077 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4078 | .readlink = generic_readlink, |
4079 | .follow_link = page_follow_link_light, | |
4080 | .put_link = page_put_link, | |
4081 | }; | |
4082 | ||
2d8f3038 | 4083 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 4084 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
4085 | EXPORT_SYMBOL(follow_down); |
4086 | EXPORT_SYMBOL(follow_up); | |
f6d2ac5c | 4087 | EXPORT_SYMBOL(get_write_access); /* nfsd */ |
1da177e4 | 4088 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
4089 | EXPORT_SYMBOL(lookup_one_len); |
4090 | EXPORT_SYMBOL(page_follow_link_light); | |
4091 | EXPORT_SYMBOL(page_put_link); | |
4092 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 4093 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
4094 | EXPORT_SYMBOL(page_symlink); |
4095 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
d1811465 | 4096 | EXPORT_SYMBOL(kern_path); |
16f18200 | 4097 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 4098 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
4099 | EXPORT_SYMBOL(unlock_rename); |
4100 | EXPORT_SYMBOL(vfs_create); | |
4101 | EXPORT_SYMBOL(vfs_follow_link); | |
4102 | EXPORT_SYMBOL(vfs_link); | |
4103 | EXPORT_SYMBOL(vfs_mkdir); | |
4104 | EXPORT_SYMBOL(vfs_mknod); | |
4105 | EXPORT_SYMBOL(generic_permission); | |
4106 | EXPORT_SYMBOL(vfs_readlink); | |
4107 | EXPORT_SYMBOL(vfs_rename); | |
4108 | EXPORT_SYMBOL(vfs_rmdir); | |
4109 | EXPORT_SYMBOL(vfs_symlink); | |
4110 | EXPORT_SYMBOL(vfs_unlink); | |
4111 | EXPORT_SYMBOL(dentry_unhash); | |
4112 | EXPORT_SYMBOL(generic_readlink); |