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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/namei.h> | |
22 | #include <linux/quotaops.h> | |
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> |
1da177e4 LT |
36 | #include <asm/uaccess.h> |
37 | ||
e81e3f4d EP |
38 | #include "internal.h" |
39 | ||
1da177e4 LT |
40 | /* [Feb-1997 T. Schoebel-Theuer] |
41 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
42 | * were necessary because of omirr. The reason is that omirr needs | |
43 | * to know the _real_ pathname, not the user-supplied one, in case | |
44 | * of symlinks (and also when transname replacements occur). | |
45 | * | |
46 | * The new code replaces the old recursive symlink resolution with | |
47 | * an iterative one (in case of non-nested symlink chains). It does | |
48 | * this with calls to <fs>_follow_link(). | |
49 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
50 | * replaced with a single function lookup_dentry() that can handle all | |
51 | * the special cases of the former code. | |
52 | * | |
53 | * With the new dcache, the pathname is stored at each inode, at least as | |
54 | * long as the refcount of the inode is positive. As a side effect, the | |
55 | * size of the dcache depends on the inode cache and thus is dynamic. | |
56 | * | |
57 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
58 | * resolution to correspond with current state of the code. | |
59 | * | |
60 | * Note that the symlink resolution is not *completely* iterative. | |
61 | * There is still a significant amount of tail- and mid- recursion in | |
62 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
63 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
64 | * may return different results than <fs>_follow_link(). Many virtual | |
65 | * filesystems (including /proc) exhibit this behavior. | |
66 | */ | |
67 | ||
68 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
69 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
70 | * and the name already exists in form of a symlink, try to create the new | |
71 | * name indicated by the symlink. The old code always complained that the | |
72 | * name already exists, due to not following the symlink even if its target | |
73 | * is nonexistent. The new semantics affects also mknod() and link() when | |
74 | * the name is a symlink pointing to a non-existant name. | |
75 | * | |
76 | * I don't know which semantics is the right one, since I have no access | |
77 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
78 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
79 | * "old" one. Personally, I think the new semantics is much more logical. | |
80 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
81 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
82 | * and in the old Linux semantics. | |
83 | */ | |
84 | ||
85 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
86 | * semantics. See the comments in "open_namei" and "do_link" below. | |
87 | * | |
88 | * [10-Sep-98 Alan Modra] Another symlink change. | |
89 | */ | |
90 | ||
91 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
92 | * inside the path - always follow. | |
93 | * in the last component in creation/removal/renaming - never follow. | |
94 | * if LOOKUP_FOLLOW passed - follow. | |
95 | * if the pathname has trailing slashes - follow. | |
96 | * otherwise - don't follow. | |
97 | * (applied in that order). | |
98 | * | |
99 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
100 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
101 | * During the 2.4 we need to fix the userland stuff depending on it - | |
102 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
103 | * XEmacs seems to be relying on it... | |
104 | */ | |
105 | /* | |
106 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 107 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
108 | * any extra contention... |
109 | */ | |
110 | ||
111 | /* In order to reduce some races, while at the same time doing additional | |
112 | * checking and hopefully speeding things up, we copy filenames to the | |
113 | * kernel data space before using them.. | |
114 | * | |
115 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
116 | * PATH_MAX includes the nul terminator --RR. | |
117 | */ | |
858119e1 | 118 | static int do_getname(const char __user *filename, char *page) |
1da177e4 LT |
119 | { |
120 | int retval; | |
121 | unsigned long len = PATH_MAX; | |
122 | ||
123 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
124 | if ((unsigned long) filename >= TASK_SIZE) | |
125 | return -EFAULT; | |
126 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
127 | len = TASK_SIZE - (unsigned long) filename; | |
128 | } | |
129 | ||
130 | retval = strncpy_from_user(page, filename, len); | |
131 | if (retval > 0) { | |
132 | if (retval < len) | |
133 | return 0; | |
134 | return -ENAMETOOLONG; | |
135 | } else if (!retval) | |
136 | retval = -ENOENT; | |
137 | return retval; | |
138 | } | |
139 | ||
140 | char * getname(const char __user * filename) | |
141 | { | |
142 | char *tmp, *result; | |
143 | ||
144 | result = ERR_PTR(-ENOMEM); | |
145 | tmp = __getname(); | |
146 | if (tmp) { | |
147 | int retval = do_getname(filename, tmp); | |
148 | ||
149 | result = tmp; | |
150 | if (retval < 0) { | |
151 | __putname(tmp); | |
152 | result = ERR_PTR(retval); | |
153 | } | |
154 | } | |
155 | audit_getname(result); | |
156 | return result; | |
157 | } | |
158 | ||
159 | #ifdef CONFIG_AUDITSYSCALL | |
160 | void putname(const char *name) | |
161 | { | |
5ac3a9c2 | 162 | if (unlikely(!audit_dummy_context())) |
1da177e4 LT |
163 | audit_putname(name); |
164 | else | |
165 | __putname(name); | |
166 | } | |
167 | EXPORT_SYMBOL(putname); | |
168 | #endif | |
169 | ||
5909ccaa LT |
170 | /* |
171 | * This does basic POSIX ACL permission checking | |
1da177e4 | 172 | */ |
5909ccaa | 173 | static int acl_permission_check(struct inode *inode, int mask, |
1da177e4 LT |
174 | int (*check_acl)(struct inode *inode, int mask)) |
175 | { | |
176 | umode_t mode = inode->i_mode; | |
177 | ||
e6305c43 AV |
178 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
179 | ||
da9592ed | 180 | if (current_fsuid() == inode->i_uid) |
1da177e4 LT |
181 | mode >>= 6; |
182 | else { | |
183 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { | |
184 | int error = check_acl(inode, mask); | |
5909ccaa | 185 | if (error != -EAGAIN) |
1da177e4 LT |
186 | return error; |
187 | } | |
188 | ||
189 | if (in_group_p(inode->i_gid)) | |
190 | mode >>= 3; | |
191 | } | |
192 | ||
193 | /* | |
194 | * If the DACs are ok we don't need any capability check. | |
195 | */ | |
e6305c43 | 196 | if ((mask & ~mode) == 0) |
1da177e4 | 197 | return 0; |
5909ccaa LT |
198 | return -EACCES; |
199 | } | |
200 | ||
201 | /** | |
202 | * generic_permission - check for access rights on a Posix-like filesystem | |
203 | * @inode: inode to check access rights for | |
204 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
205 | * @check_acl: optional callback to check for Posix ACLs | |
206 | * | |
207 | * Used to check for read/write/execute permissions on a file. | |
208 | * We use "fsuid" for this, letting us set arbitrary permissions | |
209 | * for filesystem access without changing the "normal" uids which | |
210 | * are used for other things.. | |
211 | */ | |
212 | int generic_permission(struct inode *inode, int mask, | |
213 | int (*check_acl)(struct inode *inode, int mask)) | |
214 | { | |
215 | int ret; | |
216 | ||
217 | /* | |
218 | * Do the basic POSIX ACL permission checks. | |
219 | */ | |
220 | ret = acl_permission_check(inode, mask, check_acl); | |
221 | if (ret != -EACCES) | |
222 | return ret; | |
1da177e4 | 223 | |
1da177e4 LT |
224 | /* |
225 | * Read/write DACs are always overridable. | |
226 | * Executable DACs are overridable if at least one exec bit is set. | |
227 | */ | |
f696a365 | 228 | if (!(mask & MAY_EXEC) || execute_ok(inode)) |
1da177e4 LT |
229 | if (capable(CAP_DAC_OVERRIDE)) |
230 | return 0; | |
231 | ||
232 | /* | |
233 | * Searching includes executable on directories, else just read. | |
234 | */ | |
7ea66001 | 235 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
1da177e4 LT |
236 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) |
237 | if (capable(CAP_DAC_READ_SEARCH)) | |
238 | return 0; | |
239 | ||
240 | return -EACCES; | |
241 | } | |
242 | ||
cb23beb5 CH |
243 | /** |
244 | * inode_permission - check for access rights to a given inode | |
245 | * @inode: inode to check permission on | |
246 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
247 | * | |
248 | * Used to check for read/write/execute permissions on an inode. | |
249 | * We use "fsuid" for this, letting us set arbitrary permissions | |
250 | * for filesystem access without changing the "normal" uids which | |
251 | * are used for other things. | |
252 | */ | |
f419a2e3 | 253 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 254 | { |
e6305c43 | 255 | int retval; |
1da177e4 LT |
256 | |
257 | if (mask & MAY_WRITE) { | |
22590e41 | 258 | umode_t mode = inode->i_mode; |
1da177e4 LT |
259 | |
260 | /* | |
261 | * Nobody gets write access to a read-only fs. | |
262 | */ | |
263 | if (IS_RDONLY(inode) && | |
264 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
265 | return -EROFS; | |
266 | ||
267 | /* | |
268 | * Nobody gets write access to an immutable file. | |
269 | */ | |
270 | if (IS_IMMUTABLE(inode)) | |
271 | return -EACCES; | |
272 | } | |
273 | ||
acfa4380 | 274 | if (inode->i_op->permission) |
b77b0646 | 275 | retval = inode->i_op->permission(inode, mask); |
f696a365 | 276 | else |
5909ccaa | 277 | retval = generic_permission(inode, mask, inode->i_op->check_acl); |
f696a365 | 278 | |
1da177e4 LT |
279 | if (retval) |
280 | return retval; | |
281 | ||
08ce5f16 SH |
282 | retval = devcgroup_inode_permission(inode, mask); |
283 | if (retval) | |
284 | return retval; | |
285 | ||
e6305c43 | 286 | return security_inode_permission(inode, |
f418b006 | 287 | mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); |
1da177e4 LT |
288 | } |
289 | ||
8c744fb8 CH |
290 | /** |
291 | * file_permission - check for additional access rights to a given file | |
292 | * @file: file to check access rights for | |
293 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
294 | * | |
295 | * Used to check for read/write/execute permissions on an already opened | |
296 | * file. | |
297 | * | |
298 | * Note: | |
299 | * Do not use this function in new code. All access checks should | |
cb23beb5 | 300 | * be done using inode_permission(). |
8c744fb8 CH |
301 | */ |
302 | int file_permission(struct file *file, int mask) | |
303 | { | |
f419a2e3 | 304 | return inode_permission(file->f_path.dentry->d_inode, mask); |
8c744fb8 CH |
305 | } |
306 | ||
1da177e4 LT |
307 | /* |
308 | * get_write_access() gets write permission for a file. | |
309 | * put_write_access() releases this write permission. | |
310 | * This is used for regular files. | |
311 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
312 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
313 | * can have the following values: | |
314 | * 0: no writers, no VM_DENYWRITE mappings | |
315 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
316 | * > 0: (i_writecount) users are writing to the file. | |
317 | * | |
318 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
319 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
320 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
321 | * to do the change if sign is wrong. Exclusion between them is provided by | |
322 | * the inode->i_lock spinlock. | |
323 | */ | |
324 | ||
325 | int get_write_access(struct inode * inode) | |
326 | { | |
327 | spin_lock(&inode->i_lock); | |
328 | if (atomic_read(&inode->i_writecount) < 0) { | |
329 | spin_unlock(&inode->i_lock); | |
330 | return -ETXTBSY; | |
331 | } | |
332 | atomic_inc(&inode->i_writecount); | |
333 | spin_unlock(&inode->i_lock); | |
334 | ||
335 | return 0; | |
336 | } | |
337 | ||
338 | int deny_write_access(struct file * file) | |
339 | { | |
0f7fc9e4 | 340 | struct inode *inode = file->f_path.dentry->d_inode; |
1da177e4 LT |
341 | |
342 | spin_lock(&inode->i_lock); | |
343 | if (atomic_read(&inode->i_writecount) > 0) { | |
344 | spin_unlock(&inode->i_lock); | |
345 | return -ETXTBSY; | |
346 | } | |
347 | atomic_dec(&inode->i_writecount); | |
348 | spin_unlock(&inode->i_lock); | |
349 | ||
350 | return 0; | |
351 | } | |
352 | ||
5dd784d0 JB |
353 | /** |
354 | * path_get - get a reference to a path | |
355 | * @path: path to get the reference to | |
356 | * | |
357 | * Given a path increment the reference count to the dentry and the vfsmount. | |
358 | */ | |
359 | void path_get(struct path *path) | |
360 | { | |
361 | mntget(path->mnt); | |
362 | dget(path->dentry); | |
363 | } | |
364 | EXPORT_SYMBOL(path_get); | |
365 | ||
1d957f9b JB |
366 | /** |
367 | * path_put - put a reference to a path | |
368 | * @path: path to put the reference to | |
369 | * | |
370 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
371 | */ | |
372 | void path_put(struct path *path) | |
1da177e4 | 373 | { |
1d957f9b JB |
374 | dput(path->dentry); |
375 | mntput(path->mnt); | |
1da177e4 | 376 | } |
1d957f9b | 377 | EXPORT_SYMBOL(path_put); |
1da177e4 | 378 | |
834f2a4a TM |
379 | /** |
380 | * release_open_intent - free up open intent resources | |
381 | * @nd: pointer to nameidata | |
382 | */ | |
383 | void release_open_intent(struct nameidata *nd) | |
384 | { | |
0f7fc9e4 | 385 | if (nd->intent.open.file->f_path.dentry == NULL) |
834f2a4a TM |
386 | put_filp(nd->intent.open.file); |
387 | else | |
388 | fput(nd->intent.open.file); | |
389 | } | |
390 | ||
bcdc5e01 IK |
391 | static inline struct dentry * |
392 | do_revalidate(struct dentry *dentry, struct nameidata *nd) | |
393 | { | |
394 | int status = dentry->d_op->d_revalidate(dentry, nd); | |
395 | if (unlikely(status <= 0)) { | |
396 | /* | |
397 | * The dentry failed validation. | |
398 | * If d_revalidate returned 0 attempt to invalidate | |
399 | * the dentry otherwise d_revalidate is asking us | |
400 | * to return a fail status. | |
401 | */ | |
402 | if (!status) { | |
403 | if (!d_invalidate(dentry)) { | |
404 | dput(dentry); | |
405 | dentry = NULL; | |
406 | } | |
407 | } else { | |
408 | dput(dentry); | |
409 | dentry = ERR_PTR(status); | |
410 | } | |
411 | } | |
412 | return dentry; | |
413 | } | |
414 | ||
39159de2 JL |
415 | /* |
416 | * force_reval_path - force revalidation of a dentry | |
417 | * | |
418 | * In some situations the path walking code will trust dentries without | |
419 | * revalidating them. This causes problems for filesystems that depend on | |
420 | * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set | |
421 | * (which indicates that it's possible for the dentry to go stale), force | |
422 | * a d_revalidate call before proceeding. | |
423 | * | |
424 | * Returns 0 if the revalidation was successful. If the revalidation fails, | |
425 | * either return the error returned by d_revalidate or -ESTALE if the | |
426 | * revalidation it just returned 0. If d_revalidate returns 0, we attempt to | |
427 | * invalidate the dentry. It's up to the caller to handle putting references | |
428 | * to the path if necessary. | |
429 | */ | |
430 | static int | |
431 | force_reval_path(struct path *path, struct nameidata *nd) | |
432 | { | |
433 | int status; | |
434 | struct dentry *dentry = path->dentry; | |
435 | ||
436 | /* | |
437 | * only check on filesystems where it's possible for the dentry to | |
438 | * become stale. It's assumed that if this flag is set then the | |
439 | * d_revalidate op will also be defined. | |
440 | */ | |
441 | if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) | |
442 | return 0; | |
443 | ||
444 | status = dentry->d_op->d_revalidate(dentry, nd); | |
445 | if (status > 0) | |
446 | return 0; | |
447 | ||
448 | if (!status) { | |
449 | d_invalidate(dentry); | |
450 | status = -ESTALE; | |
451 | } | |
452 | return status; | |
453 | } | |
454 | ||
1da177e4 | 455 | /* |
b75b5086 AV |
456 | * Short-cut version of permission(), for calling on directories |
457 | * during pathname resolution. Combines parts of permission() | |
458 | * and generic_permission(), and tests ONLY for MAY_EXEC permission. | |
1da177e4 LT |
459 | * |
460 | * If appropriate, check DAC only. If not appropriate, or | |
b75b5086 | 461 | * short-cut DAC fails, then call ->permission() to do more |
1da177e4 LT |
462 | * complete permission check. |
463 | */ | |
b75b5086 | 464 | static int exec_permission(struct inode *inode) |
1da177e4 | 465 | { |
5909ccaa | 466 | int ret; |
1da177e4 | 467 | |
cb9179ea | 468 | if (inode->i_op->permission) { |
5909ccaa | 469 | ret = inode->i_op->permission(inode, MAY_EXEC); |
cb9179ea LT |
470 | if (!ret) |
471 | goto ok; | |
472 | return ret; | |
473 | } | |
5909ccaa LT |
474 | ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); |
475 | if (!ret) | |
1da177e4 LT |
476 | goto ok; |
477 | ||
f1ac9f6b | 478 | if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
479 | goto ok; |
480 | ||
5909ccaa | 481 | return ret; |
1da177e4 | 482 | ok: |
b77b0646 | 483 | return security_inode_permission(inode, MAY_EXEC); |
1da177e4 LT |
484 | } |
485 | ||
2a737871 AV |
486 | static __always_inline void set_root(struct nameidata *nd) |
487 | { | |
488 | if (!nd->root.mnt) { | |
489 | struct fs_struct *fs = current->fs; | |
490 | read_lock(&fs->lock); | |
491 | nd->root = fs->root; | |
492 | path_get(&nd->root); | |
493 | read_unlock(&fs->lock); | |
494 | } | |
495 | } | |
496 | ||
6de88d72 AV |
497 | static int link_path_walk(const char *, struct nameidata *); |
498 | ||
f1662356 | 499 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 LT |
500 | { |
501 | int res = 0; | |
502 | char *name; | |
503 | if (IS_ERR(link)) | |
504 | goto fail; | |
505 | ||
506 | if (*link == '/') { | |
2a737871 | 507 | set_root(nd); |
1d957f9b | 508 | path_put(&nd->path); |
2a737871 AV |
509 | nd->path = nd->root; |
510 | path_get(&nd->root); | |
1da177e4 | 511 | } |
b4091d5f | 512 | |
1da177e4 | 513 | res = link_path_walk(link, nd); |
1da177e4 LT |
514 | if (nd->depth || res || nd->last_type!=LAST_NORM) |
515 | return res; | |
516 | /* | |
517 | * If it is an iterative symlinks resolution in open_namei() we | |
518 | * have to copy the last component. And all that crap because of | |
519 | * bloody create() on broken symlinks. Furrfu... | |
520 | */ | |
521 | name = __getname(); | |
522 | if (unlikely(!name)) { | |
1d957f9b | 523 | path_put(&nd->path); |
1da177e4 LT |
524 | return -ENOMEM; |
525 | } | |
526 | strcpy(name, nd->last.name); | |
527 | nd->last.name = name; | |
528 | return 0; | |
529 | fail: | |
1d957f9b | 530 | path_put(&nd->path); |
1da177e4 LT |
531 | return PTR_ERR(link); |
532 | } | |
533 | ||
1d957f9b | 534 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
535 | { |
536 | dput(path->dentry); | |
4ac91378 | 537 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
538 | mntput(path->mnt); |
539 | } | |
540 | ||
541 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) | |
542 | { | |
4ac91378 JB |
543 | dput(nd->path.dentry); |
544 | if (nd->path.mnt != path->mnt) | |
545 | mntput(nd->path.mnt); | |
546 | nd->path.mnt = path->mnt; | |
547 | nd->path.dentry = path->dentry; | |
051d3812 IK |
548 | } |
549 | ||
f1662356 | 550 | static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
551 | { |
552 | int error; | |
cc314eef | 553 | void *cookie; |
cd4e91d3 | 554 | struct dentry *dentry = path->dentry; |
1da177e4 | 555 | |
d671a1cb | 556 | touch_atime(path->mnt, dentry); |
1da177e4 | 557 | nd_set_link(nd, NULL); |
cd4e91d3 | 558 | |
4ac91378 | 559 | if (path->mnt != nd->path.mnt) { |
051d3812 IK |
560 | path_to_nameidata(path, nd); |
561 | dget(dentry); | |
562 | } | |
563 | mntget(path->mnt); | |
86acdca1 | 564 | nd->last_type = LAST_BIND; |
cc314eef LT |
565 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
566 | error = PTR_ERR(cookie); | |
567 | if (!IS_ERR(cookie)) { | |
1da177e4 | 568 | char *s = nd_get_link(nd); |
cc314eef | 569 | error = 0; |
1da177e4 LT |
570 | if (s) |
571 | error = __vfs_follow_link(nd, s); | |
39159de2 JL |
572 | else if (nd->last_type == LAST_BIND) { |
573 | error = force_reval_path(&nd->path, nd); | |
574 | if (error) | |
575 | path_put(&nd->path); | |
576 | } | |
1da177e4 | 577 | if (dentry->d_inode->i_op->put_link) |
cc314eef | 578 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 579 | } |
1da177e4 LT |
580 | return error; |
581 | } | |
582 | ||
583 | /* | |
584 | * This limits recursive symlink follows to 8, while | |
585 | * limiting consecutive symlinks to 40. | |
586 | * | |
587 | * Without that kind of total limit, nasty chains of consecutive | |
588 | * symlinks can cause almost arbitrarily long lookups. | |
589 | */ | |
90ebe565 | 590 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
591 | { |
592 | int err = -ELOOP; | |
593 | if (current->link_count >= MAX_NESTED_LINKS) | |
594 | goto loop; | |
595 | if (current->total_link_count >= 40) | |
596 | goto loop; | |
597 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
598 | cond_resched(); | |
90ebe565 | 599 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
600 | if (err) |
601 | goto loop; | |
602 | current->link_count++; | |
603 | current->total_link_count++; | |
604 | nd->depth++; | |
cd4e91d3 | 605 | err = __do_follow_link(path, nd); |
258fa999 | 606 | path_put(path); |
839d9f93 AV |
607 | current->link_count--; |
608 | nd->depth--; | |
1da177e4 LT |
609 | return err; |
610 | loop: | |
1d957f9b JB |
611 | path_put_conditional(path, nd); |
612 | path_put(&nd->path); | |
1da177e4 LT |
613 | return err; |
614 | } | |
615 | ||
bab77ebf | 616 | int follow_up(struct path *path) |
1da177e4 LT |
617 | { |
618 | struct vfsmount *parent; | |
619 | struct dentry *mountpoint; | |
620 | spin_lock(&vfsmount_lock); | |
bab77ebf AV |
621 | parent = path->mnt->mnt_parent; |
622 | if (parent == path->mnt) { | |
1da177e4 LT |
623 | spin_unlock(&vfsmount_lock); |
624 | return 0; | |
625 | } | |
626 | mntget(parent); | |
bab77ebf | 627 | mountpoint = dget(path->mnt->mnt_mountpoint); |
1da177e4 | 628 | spin_unlock(&vfsmount_lock); |
bab77ebf AV |
629 | dput(path->dentry); |
630 | path->dentry = mountpoint; | |
631 | mntput(path->mnt); | |
632 | path->mnt = parent; | |
1da177e4 LT |
633 | return 1; |
634 | } | |
635 | ||
636 | /* no need for dcache_lock, as serialization is taken care in | |
637 | * namespace.c | |
638 | */ | |
463ffb2e AV |
639 | static int __follow_mount(struct path *path) |
640 | { | |
641 | int res = 0; | |
642 | while (d_mountpoint(path->dentry)) { | |
1c755af4 | 643 | struct vfsmount *mounted = lookup_mnt(path); |
463ffb2e AV |
644 | if (!mounted) |
645 | break; | |
646 | dput(path->dentry); | |
647 | if (res) | |
648 | mntput(path->mnt); | |
649 | path->mnt = mounted; | |
650 | path->dentry = dget(mounted->mnt_root); | |
651 | res = 1; | |
652 | } | |
653 | return res; | |
654 | } | |
655 | ||
79ed0226 | 656 | static void follow_mount(struct path *path) |
1da177e4 | 657 | { |
79ed0226 | 658 | while (d_mountpoint(path->dentry)) { |
1c755af4 | 659 | struct vfsmount *mounted = lookup_mnt(path); |
1da177e4 LT |
660 | if (!mounted) |
661 | break; | |
79ed0226 AV |
662 | dput(path->dentry); |
663 | mntput(path->mnt); | |
664 | path->mnt = mounted; | |
665 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 | 666 | } |
1da177e4 LT |
667 | } |
668 | ||
669 | /* no need for dcache_lock, as serialization is taken care in | |
670 | * namespace.c | |
671 | */ | |
9393bd07 | 672 | int follow_down(struct path *path) |
1da177e4 LT |
673 | { |
674 | struct vfsmount *mounted; | |
675 | ||
1c755af4 | 676 | mounted = lookup_mnt(path); |
1da177e4 | 677 | if (mounted) { |
9393bd07 AV |
678 | dput(path->dentry); |
679 | mntput(path->mnt); | |
680 | path->mnt = mounted; | |
681 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
682 | return 1; |
683 | } | |
684 | return 0; | |
685 | } | |
686 | ||
f1662356 | 687 | static __always_inline void follow_dotdot(struct nameidata *nd) |
1da177e4 | 688 | { |
2a737871 | 689 | set_root(nd); |
e518ddb7 | 690 | |
1da177e4 | 691 | while(1) { |
4ac91378 | 692 | struct dentry *old = nd->path.dentry; |
1da177e4 | 693 | |
2a737871 AV |
694 | if (nd->path.dentry == nd->root.dentry && |
695 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
696 | break; |
697 | } | |
4ac91378 | 698 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
699 | /* rare case of legitimate dget_parent()... */ |
700 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
701 | dput(old); |
702 | break; | |
703 | } | |
3088dd70 | 704 | if (!follow_up(&nd->path)) |
1da177e4 | 705 | break; |
1da177e4 | 706 | } |
79ed0226 | 707 | follow_mount(&nd->path); |
1da177e4 LT |
708 | } |
709 | ||
1da177e4 LT |
710 | /* |
711 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
712 | * small and for now I'd prefer to have fast path as straight as possible. | |
713 | * It _is_ time-critical. | |
714 | */ | |
715 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
716 | struct path *path) | |
717 | { | |
4ac91378 | 718 | struct vfsmount *mnt = nd->path.mnt; |
6e6b1bd1 AV |
719 | struct dentry *dentry, *parent; |
720 | struct inode *dir; | |
3cac260a AV |
721 | /* |
722 | * See if the low-level filesystem might want | |
723 | * to use its own hash.. | |
724 | */ | |
725 | if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { | |
726 | int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name); | |
727 | if (err < 0) | |
728 | return err; | |
729 | } | |
1da177e4 | 730 | |
3cac260a | 731 | dentry = __d_lookup(nd->path.dentry, name); |
1da177e4 LT |
732 | if (!dentry) |
733 | goto need_lookup; | |
734 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
735 | goto need_revalidate; | |
736 | done: | |
737 | path->mnt = mnt; | |
738 | path->dentry = dentry; | |
634ee701 | 739 | __follow_mount(path); |
1da177e4 LT |
740 | return 0; |
741 | ||
742 | need_lookup: | |
6e6b1bd1 AV |
743 | parent = nd->path.dentry; |
744 | dir = parent->d_inode; | |
745 | ||
746 | mutex_lock(&dir->i_mutex); | |
747 | /* | |
748 | * First re-do the cached lookup just in case it was created | |
749 | * while we waited for the directory semaphore.. | |
750 | * | |
751 | * FIXME! This could use version numbering or similar to | |
752 | * avoid unnecessary cache lookups. | |
753 | * | |
754 | * The "dcache_lock" is purely to protect the RCU list walker | |
755 | * from concurrent renames at this point (we mustn't get false | |
756 | * negatives from the RCU list walk here, unlike the optimistic | |
757 | * fast walk). | |
758 | * | |
759 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
760 | */ | |
761 | dentry = d_lookup(parent, name); | |
762 | if (!dentry) { | |
763 | struct dentry *new; | |
764 | ||
765 | /* Don't create child dentry for a dead directory. */ | |
766 | dentry = ERR_PTR(-ENOENT); | |
767 | if (IS_DEADDIR(dir)) | |
768 | goto out_unlock; | |
769 | ||
770 | new = d_alloc(parent, name); | |
771 | dentry = ERR_PTR(-ENOMEM); | |
772 | if (new) { | |
773 | dentry = dir->i_op->lookup(dir, new, nd); | |
774 | if (dentry) | |
775 | dput(new); | |
776 | else | |
777 | dentry = new; | |
778 | } | |
779 | out_unlock: | |
780 | mutex_unlock(&dir->i_mutex); | |
781 | if (IS_ERR(dentry)) | |
782 | goto fail; | |
783 | goto done; | |
784 | } | |
785 | ||
786 | /* | |
787 | * Uhhuh! Nasty case: the cache was re-populated while | |
788 | * we waited on the semaphore. Need to revalidate. | |
789 | */ | |
790 | mutex_unlock(&dir->i_mutex); | |
791 | if (dentry->d_op && dentry->d_op->d_revalidate) { | |
792 | dentry = do_revalidate(dentry, nd); | |
793 | if (!dentry) | |
794 | dentry = ERR_PTR(-ENOENT); | |
795 | } | |
1da177e4 LT |
796 | if (IS_ERR(dentry)) |
797 | goto fail; | |
798 | goto done; | |
799 | ||
800 | need_revalidate: | |
bcdc5e01 IK |
801 | dentry = do_revalidate(dentry, nd); |
802 | if (!dentry) | |
803 | goto need_lookup; | |
804 | if (IS_ERR(dentry)) | |
805 | goto fail; | |
806 | goto done; | |
1da177e4 LT |
807 | |
808 | fail: | |
809 | return PTR_ERR(dentry); | |
810 | } | |
811 | ||
ac278a9c AV |
812 | /* |
813 | * This is a temporary kludge to deal with "automount" symlinks; proper | |
814 | * solution is to trigger them on follow_mount(), so that do_lookup() | |
815 | * would DTRT. To be killed before 2.6.34-final. | |
816 | */ | |
817 | static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) | |
818 | { | |
819 | return inode && unlikely(inode->i_op->follow_link) && | |
820 | ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); | |
821 | } | |
822 | ||
1da177e4 LT |
823 | /* |
824 | * Name resolution. | |
ea3834d9 PM |
825 | * This is the basic name resolution function, turning a pathname into |
826 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 827 | * |
ea3834d9 PM |
828 | * Returns 0 and nd will have valid dentry and mnt on success. |
829 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 830 | */ |
6de88d72 | 831 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
832 | { |
833 | struct path next; | |
834 | struct inode *inode; | |
835 | int err; | |
836 | unsigned int lookup_flags = nd->flags; | |
837 | ||
838 | while (*name=='/') | |
839 | name++; | |
840 | if (!*name) | |
841 | goto return_reval; | |
842 | ||
4ac91378 | 843 | inode = nd->path.dentry->d_inode; |
1da177e4 | 844 | if (nd->depth) |
f55eab82 | 845 | lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); |
1da177e4 LT |
846 | |
847 | /* At this point we know we have a real path component. */ | |
848 | for(;;) { | |
849 | unsigned long hash; | |
850 | struct qstr this; | |
851 | unsigned int c; | |
852 | ||
cdce5d6b | 853 | nd->flags |= LOOKUP_CONTINUE; |
b75b5086 | 854 | err = exec_permission(inode); |
1da177e4 LT |
855 | if (err) |
856 | break; | |
857 | ||
858 | this.name = name; | |
859 | c = *(const unsigned char *)name; | |
860 | ||
861 | hash = init_name_hash(); | |
862 | do { | |
863 | name++; | |
864 | hash = partial_name_hash(c, hash); | |
865 | c = *(const unsigned char *)name; | |
866 | } while (c && (c != '/')); | |
867 | this.len = name - (const char *) this.name; | |
868 | this.hash = end_name_hash(hash); | |
869 | ||
870 | /* remove trailing slashes? */ | |
871 | if (!c) | |
872 | goto last_component; | |
873 | while (*++name == '/'); | |
874 | if (!*name) | |
875 | goto last_with_slashes; | |
876 | ||
877 | /* | |
878 | * "." and ".." are special - ".." especially so because it has | |
879 | * to be able to know about the current root directory and | |
880 | * parent relationships. | |
881 | */ | |
882 | if (this.name[0] == '.') switch (this.len) { | |
883 | default: | |
884 | break; | |
885 | case 2: | |
886 | if (this.name[1] != '.') | |
887 | break; | |
58c465eb | 888 | follow_dotdot(nd); |
4ac91378 | 889 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
890 | /* fallthrough */ |
891 | case 1: | |
892 | continue; | |
893 | } | |
1da177e4 LT |
894 | /* This does the actual lookups.. */ |
895 | err = do_lookup(nd, &this, &next); | |
896 | if (err) | |
897 | break; | |
1da177e4 LT |
898 | |
899 | err = -ENOENT; | |
900 | inode = next.dentry->d_inode; | |
901 | if (!inode) | |
902 | goto out_dput; | |
1da177e4 LT |
903 | |
904 | if (inode->i_op->follow_link) { | |
90ebe565 | 905 | err = do_follow_link(&next, nd); |
1da177e4 LT |
906 | if (err) |
907 | goto return_err; | |
908 | err = -ENOENT; | |
4ac91378 | 909 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
910 | if (!inode) |
911 | break; | |
09dd17d3 MS |
912 | } else |
913 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
914 | err = -ENOTDIR; |
915 | if (!inode->i_op->lookup) | |
916 | break; | |
917 | continue; | |
918 | /* here ends the main loop */ | |
919 | ||
920 | last_with_slashes: | |
921 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
922 | last_component: | |
f55eab82 TM |
923 | /* Clear LOOKUP_CONTINUE iff it was previously unset */ |
924 | nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; | |
1da177e4 LT |
925 | if (lookup_flags & LOOKUP_PARENT) |
926 | goto lookup_parent; | |
927 | if (this.name[0] == '.') switch (this.len) { | |
928 | default: | |
929 | break; | |
930 | case 2: | |
931 | if (this.name[1] != '.') | |
932 | break; | |
58c465eb | 933 | follow_dotdot(nd); |
4ac91378 | 934 | inode = nd->path.dentry->d_inode; |
1da177e4 LT |
935 | /* fallthrough */ |
936 | case 1: | |
937 | goto return_reval; | |
938 | } | |
1da177e4 LT |
939 | err = do_lookup(nd, &this, &next); |
940 | if (err) | |
941 | break; | |
1da177e4 | 942 | inode = next.dentry->d_inode; |
ac278a9c | 943 | if (follow_on_final(inode, lookup_flags)) { |
90ebe565 | 944 | err = do_follow_link(&next, nd); |
1da177e4 LT |
945 | if (err) |
946 | goto return_err; | |
4ac91378 | 947 | inode = nd->path.dentry->d_inode; |
09dd17d3 MS |
948 | } else |
949 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
950 | err = -ENOENT; |
951 | if (!inode) | |
952 | break; | |
953 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
954 | err = -ENOTDIR; | |
acfa4380 | 955 | if (!inode->i_op->lookup) |
1da177e4 LT |
956 | break; |
957 | } | |
958 | goto return_base; | |
959 | lookup_parent: | |
960 | nd->last = this; | |
961 | nd->last_type = LAST_NORM; | |
962 | if (this.name[0] != '.') | |
963 | goto return_base; | |
964 | if (this.len == 1) | |
965 | nd->last_type = LAST_DOT; | |
966 | else if (this.len == 2 && this.name[1] == '.') | |
967 | nd->last_type = LAST_DOTDOT; | |
968 | else | |
969 | goto return_base; | |
970 | return_reval: | |
971 | /* | |
972 | * We bypassed the ordinary revalidation routines. | |
973 | * We may need to check the cached dentry for staleness. | |
974 | */ | |
4ac91378 JB |
975 | if (nd->path.dentry && nd->path.dentry->d_sb && |
976 | (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
1da177e4 LT |
977 | err = -ESTALE; |
978 | /* Note: we do not d_invalidate() */ | |
4ac91378 JB |
979 | if (!nd->path.dentry->d_op->d_revalidate( |
980 | nd->path.dentry, nd)) | |
1da177e4 LT |
981 | break; |
982 | } | |
983 | return_base: | |
984 | return 0; | |
985 | out_dput: | |
1d957f9b | 986 | path_put_conditional(&next, nd); |
1da177e4 LT |
987 | break; |
988 | } | |
1d957f9b | 989 | path_put(&nd->path); |
1da177e4 LT |
990 | return_err: |
991 | return err; | |
992 | } | |
993 | ||
fc9b52cd | 994 | static int path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 995 | { |
6de88d72 AV |
996 | struct path save = nd->path; |
997 | int result; | |
998 | ||
1da177e4 | 999 | current->total_link_count = 0; |
6de88d72 AV |
1000 | |
1001 | /* make sure the stuff we saved doesn't go away */ | |
1002 | path_get(&save); | |
1003 | ||
1004 | result = link_path_walk(name, nd); | |
1005 | if (result == -ESTALE) { | |
1006 | /* nd->path had been dropped */ | |
1007 | current->total_link_count = 0; | |
1008 | nd->path = save; | |
1009 | path_get(&nd->path); | |
1010 | nd->flags |= LOOKUP_REVAL; | |
1011 | result = link_path_walk(name, nd); | |
1012 | } | |
1013 | ||
1014 | path_put(&save); | |
1015 | ||
1016 | return result; | |
1da177e4 LT |
1017 | } |
1018 | ||
9b4a9b14 | 1019 | static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) |
1da177e4 | 1020 | { |
ea3834d9 | 1021 | int retval = 0; |
170aa3d0 UD |
1022 | int fput_needed; |
1023 | struct file *file; | |
1da177e4 LT |
1024 | |
1025 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1026 | nd->flags = flags; | |
1027 | nd->depth = 0; | |
2a737871 | 1028 | nd->root.mnt = NULL; |
1da177e4 | 1029 | |
1da177e4 | 1030 | if (*name=='/') { |
2a737871 AV |
1031 | set_root(nd); |
1032 | nd->path = nd->root; | |
1033 | path_get(&nd->root); | |
5590ff0d | 1034 | } else if (dfd == AT_FDCWD) { |
2a737871 | 1035 | struct fs_struct *fs = current->fs; |
e518ddb7 | 1036 | read_lock(&fs->lock); |
6ac08c39 JB |
1037 | nd->path = fs->pwd; |
1038 | path_get(&fs->pwd); | |
e518ddb7 | 1039 | read_unlock(&fs->lock); |
5590ff0d | 1040 | } else { |
5590ff0d UD |
1041 | struct dentry *dentry; |
1042 | ||
1043 | file = fget_light(dfd, &fput_needed); | |
170aa3d0 UD |
1044 | retval = -EBADF; |
1045 | if (!file) | |
6d09bb62 | 1046 | goto out_fail; |
5590ff0d | 1047 | |
0f7fc9e4 | 1048 | dentry = file->f_path.dentry; |
5590ff0d | 1049 | |
170aa3d0 UD |
1050 | retval = -ENOTDIR; |
1051 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
6d09bb62 | 1052 | goto fput_fail; |
5590ff0d UD |
1053 | |
1054 | retval = file_permission(file, MAY_EXEC); | |
170aa3d0 | 1055 | if (retval) |
6d09bb62 | 1056 | goto fput_fail; |
5590ff0d | 1057 | |
5dd784d0 JB |
1058 | nd->path = file->f_path; |
1059 | path_get(&file->f_path); | |
5590ff0d UD |
1060 | |
1061 | fput_light(file, fput_needed); | |
1da177e4 | 1062 | } |
9b4a9b14 | 1063 | return 0; |
2dfdd266 | 1064 | |
9b4a9b14 AV |
1065 | fput_fail: |
1066 | fput_light(file, fput_needed); | |
1067 | out_fail: | |
1068 | return retval; | |
1069 | } | |
1070 | ||
1071 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ | |
1072 | static int do_path_lookup(int dfd, const char *name, | |
1073 | unsigned int flags, struct nameidata *nd) | |
1074 | { | |
1075 | int retval = path_init(dfd, name, flags, nd); | |
1076 | if (!retval) | |
1077 | retval = path_walk(name, nd); | |
4ac91378 JB |
1078 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1079 | nd->path.dentry->d_inode)) | |
1080 | audit_inode(name, nd->path.dentry); | |
2a737871 AV |
1081 | if (nd->root.mnt) { |
1082 | path_put(&nd->root); | |
1083 | nd->root.mnt = NULL; | |
1084 | } | |
170aa3d0 | 1085 | return retval; |
1da177e4 LT |
1086 | } |
1087 | ||
fc9b52cd | 1088 | int path_lookup(const char *name, unsigned int flags, |
5590ff0d UD |
1089 | struct nameidata *nd) |
1090 | { | |
1091 | return do_path_lookup(AT_FDCWD, name, flags, nd); | |
1092 | } | |
1093 | ||
d1811465 AV |
1094 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1095 | { | |
1096 | struct nameidata nd; | |
1097 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1098 | if (!res) | |
1099 | *path = nd.path; | |
1100 | return res; | |
1101 | } | |
1102 | ||
16f18200 JJS |
1103 | /** |
1104 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1105 | * @dentry: pointer to dentry of the base directory | |
1106 | * @mnt: pointer to vfs mount of the base directory | |
1107 | * @name: pointer to file name | |
1108 | * @flags: lookup flags | |
1109 | * @nd: pointer to nameidata | |
1110 | */ | |
1111 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1112 | const char *name, unsigned int flags, | |
1113 | struct nameidata *nd) | |
1114 | { | |
1115 | int retval; | |
1116 | ||
1117 | /* same as do_path_lookup */ | |
1118 | nd->last_type = LAST_ROOT; | |
1119 | nd->flags = flags; | |
1120 | nd->depth = 0; | |
1121 | ||
c8e7f449 JB |
1122 | nd->path.dentry = dentry; |
1123 | nd->path.mnt = mnt; | |
1124 | path_get(&nd->path); | |
5b857119 AV |
1125 | nd->root = nd->path; |
1126 | path_get(&nd->root); | |
16f18200 JJS |
1127 | |
1128 | retval = path_walk(name, nd); | |
4ac91378 JB |
1129 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1130 | nd->path.dentry->d_inode)) | |
1131 | audit_inode(name, nd->path.dentry); | |
16f18200 | 1132 | |
5b857119 AV |
1133 | path_put(&nd->root); |
1134 | nd->root.mnt = NULL; | |
16f18200 | 1135 | |
2a737871 | 1136 | return retval; |
16f18200 JJS |
1137 | } |
1138 | ||
eead1911 CH |
1139 | static struct dentry *__lookup_hash(struct qstr *name, |
1140 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1141 | { |
057f6c01 | 1142 | struct dentry *dentry; |
1da177e4 LT |
1143 | struct inode *inode; |
1144 | int err; | |
1145 | ||
1146 | inode = base->d_inode; | |
1da177e4 LT |
1147 | |
1148 | /* | |
1149 | * See if the low-level filesystem might want | |
1150 | * to use its own hash.. | |
1151 | */ | |
1152 | if (base->d_op && base->d_op->d_hash) { | |
1153 | err = base->d_op->d_hash(base, name); | |
1154 | dentry = ERR_PTR(err); | |
1155 | if (err < 0) | |
1156 | goto out; | |
1157 | } | |
1158 | ||
6e6b1bd1 AV |
1159 | dentry = __d_lookup(base, name); |
1160 | ||
1161 | /* lockess __d_lookup may fail due to concurrent d_move() | |
1162 | * in some unrelated directory, so try with d_lookup | |
1163 | */ | |
1164 | if (!dentry) | |
1165 | dentry = d_lookup(base, name); | |
1166 | ||
1167 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) | |
1168 | dentry = do_revalidate(dentry, nd); | |
1169 | ||
1da177e4 | 1170 | if (!dentry) { |
d70b67c8 MS |
1171 | struct dentry *new; |
1172 | ||
1173 | /* Don't create child dentry for a dead directory. */ | |
1174 | dentry = ERR_PTR(-ENOENT); | |
1175 | if (IS_DEADDIR(inode)) | |
1176 | goto out; | |
1177 | ||
1178 | new = d_alloc(base, name); | |
1da177e4 LT |
1179 | dentry = ERR_PTR(-ENOMEM); |
1180 | if (!new) | |
1181 | goto out; | |
1182 | dentry = inode->i_op->lookup(inode, new, nd); | |
1183 | if (!dentry) | |
1184 | dentry = new; | |
1185 | else | |
1186 | dput(new); | |
1187 | } | |
1188 | out: | |
1189 | return dentry; | |
1190 | } | |
1191 | ||
057f6c01 JM |
1192 | /* |
1193 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1194 | * needs parent already locked. Doesn't follow mounts. | |
1195 | * SMP-safe. | |
1196 | */ | |
eead1911 | 1197 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1198 | { |
057f6c01 JM |
1199 | int err; |
1200 | ||
b75b5086 | 1201 | err = exec_permission(nd->path.dentry->d_inode); |
057f6c01 | 1202 | if (err) |
eead1911 | 1203 | return ERR_PTR(err); |
4ac91378 | 1204 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1205 | } |
1206 | ||
eead1911 CH |
1207 | static int __lookup_one_len(const char *name, struct qstr *this, |
1208 | struct dentry *base, int len) | |
1da177e4 LT |
1209 | { |
1210 | unsigned long hash; | |
1da177e4 LT |
1211 | unsigned int c; |
1212 | ||
057f6c01 JM |
1213 | this->name = name; |
1214 | this->len = len; | |
1da177e4 | 1215 | if (!len) |
057f6c01 | 1216 | return -EACCES; |
1da177e4 LT |
1217 | |
1218 | hash = init_name_hash(); | |
1219 | while (len--) { | |
1220 | c = *(const unsigned char *)name++; | |
1221 | if (c == '/' || c == '\0') | |
057f6c01 | 1222 | return -EACCES; |
1da177e4 LT |
1223 | hash = partial_name_hash(c, hash); |
1224 | } | |
057f6c01 JM |
1225 | this->hash = end_name_hash(hash); |
1226 | return 0; | |
1227 | } | |
1da177e4 | 1228 | |
eead1911 | 1229 | /** |
a6b91919 | 1230 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1231 | * @name: pathname component to lookup |
1232 | * @base: base directory to lookup from | |
1233 | * @len: maximum length @len should be interpreted to | |
1234 | * | |
a6b91919 RD |
1235 | * Note that this routine is purely a helper for filesystem usage and should |
1236 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1237 | * nameidata argument is passed to the filesystem methods and a filesystem |
1238 | * using this helper needs to be prepared for that. | |
1239 | */ | |
057f6c01 JM |
1240 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1241 | { | |
1242 | int err; | |
1243 | struct qstr this; | |
1244 | ||
2f9092e1 DW |
1245 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1246 | ||
057f6c01 | 1247 | err = __lookup_one_len(name, &this, base, len); |
eead1911 CH |
1248 | if (err) |
1249 | return ERR_PTR(err); | |
1250 | ||
b75b5086 | 1251 | err = exec_permission(base->d_inode); |
057f6c01 JM |
1252 | if (err) |
1253 | return ERR_PTR(err); | |
49705b77 | 1254 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1255 | } |
1256 | ||
2d8f3038 AV |
1257 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1258 | struct path *path) | |
1da177e4 | 1259 | { |
2d8f3038 | 1260 | struct nameidata nd; |
1da177e4 LT |
1261 | char *tmp = getname(name); |
1262 | int err = PTR_ERR(tmp); | |
1da177e4 | 1263 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1264 | |
1265 | BUG_ON(flags & LOOKUP_PARENT); | |
1266 | ||
1267 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1268 | putname(tmp); |
2d8f3038 AV |
1269 | if (!err) |
1270 | *path = nd.path; | |
1da177e4 LT |
1271 | } |
1272 | return err; | |
1273 | } | |
1274 | ||
2ad94ae6 AV |
1275 | static int user_path_parent(int dfd, const char __user *path, |
1276 | struct nameidata *nd, char **name) | |
1277 | { | |
1278 | char *s = getname(path); | |
1279 | int error; | |
1280 | ||
1281 | if (IS_ERR(s)) | |
1282 | return PTR_ERR(s); | |
1283 | ||
1284 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1285 | if (error) | |
1286 | putname(s); | |
1287 | else | |
1288 | *name = s; | |
1289 | ||
1290 | return error; | |
1291 | } | |
1292 | ||
1da177e4 LT |
1293 | /* |
1294 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1295 | * minimal. | |
1296 | */ | |
1297 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1298 | { | |
da9592ed DH |
1299 | uid_t fsuid = current_fsuid(); |
1300 | ||
1da177e4 LT |
1301 | if (!(dir->i_mode & S_ISVTX)) |
1302 | return 0; | |
da9592ed | 1303 | if (inode->i_uid == fsuid) |
1da177e4 | 1304 | return 0; |
da9592ed | 1305 | if (dir->i_uid == fsuid) |
1da177e4 LT |
1306 | return 0; |
1307 | return !capable(CAP_FOWNER); | |
1308 | } | |
1309 | ||
1310 | /* | |
1311 | * Check whether we can remove a link victim from directory dir, check | |
1312 | * whether the type of victim is right. | |
1313 | * 1. We can't do it if dir is read-only (done in permission()) | |
1314 | * 2. We should have write and exec permissions on dir | |
1315 | * 3. We can't remove anything from append-only dir | |
1316 | * 4. We can't do anything with immutable dir (done in permission()) | |
1317 | * 5. If the sticky bit on dir is set we should either | |
1318 | * a. be owner of dir, or | |
1319 | * b. be owner of victim, or | |
1320 | * c. have CAP_FOWNER capability | |
1321 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1322 | * links pointing to it. | |
1323 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1324 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1325 | * 9. We can't remove a root or mountpoint. | |
1326 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1327 | * nfs_async_unlink(). | |
1328 | */ | |
858119e1 | 1329 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1330 | { |
1331 | int error; | |
1332 | ||
1333 | if (!victim->d_inode) | |
1334 | return -ENOENT; | |
1335 | ||
1336 | BUG_ON(victim->d_parent->d_inode != dir); | |
cccc6bba | 1337 | audit_inode_child(victim, dir); |
1da177e4 | 1338 | |
f419a2e3 | 1339 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1340 | if (error) |
1341 | return error; | |
1342 | if (IS_APPEND(dir)) | |
1343 | return -EPERM; | |
1344 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1345 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1346 | return -EPERM; |
1347 | if (isdir) { | |
1348 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1349 | return -ENOTDIR; | |
1350 | if (IS_ROOT(victim)) | |
1351 | return -EBUSY; | |
1352 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1353 | return -EISDIR; | |
1354 | if (IS_DEADDIR(dir)) | |
1355 | return -ENOENT; | |
1356 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1357 | return -EBUSY; | |
1358 | return 0; | |
1359 | } | |
1360 | ||
1361 | /* Check whether we can create an object with dentry child in directory | |
1362 | * dir. | |
1363 | * 1. We can't do it if child already exists (open has special treatment for | |
1364 | * this case, but since we are inlined it's OK) | |
1365 | * 2. We can't do it if dir is read-only (done in permission()) | |
1366 | * 3. We should have write and exec permissions on dir | |
1367 | * 4. We can't do it if dir is immutable (done in permission()) | |
1368 | */ | |
a95164d9 | 1369 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1370 | { |
1371 | if (child->d_inode) | |
1372 | return -EEXIST; | |
1373 | if (IS_DEADDIR(dir)) | |
1374 | return -ENOENT; | |
f419a2e3 | 1375 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1376 | } |
1377 | ||
1378 | /* | |
1da177e4 LT |
1379 | * O_DIRECTORY translates into forcing a directory lookup. |
1380 | */ | |
1381 | static inline int lookup_flags(unsigned int f) | |
1382 | { | |
1383 | unsigned long retval = LOOKUP_FOLLOW; | |
1384 | ||
1385 | if (f & O_NOFOLLOW) | |
1386 | retval &= ~LOOKUP_FOLLOW; | |
1387 | ||
1da177e4 LT |
1388 | if (f & O_DIRECTORY) |
1389 | retval |= LOOKUP_DIRECTORY; | |
1390 | ||
1391 | return retval; | |
1392 | } | |
1393 | ||
1394 | /* | |
1395 | * p1 and p2 should be directories on the same fs. | |
1396 | */ | |
1397 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1398 | { | |
1399 | struct dentry *p; | |
1400 | ||
1401 | if (p1 == p2) { | |
f2eace23 | 1402 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1403 | return NULL; |
1404 | } | |
1405 | ||
a11f3a05 | 1406 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1407 | |
e2761a11 OH |
1408 | p = d_ancestor(p2, p1); |
1409 | if (p) { | |
1410 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1411 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1412 | return p; | |
1da177e4 LT |
1413 | } |
1414 | ||
e2761a11 OH |
1415 | p = d_ancestor(p1, p2); |
1416 | if (p) { | |
1417 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1418 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1419 | return p; | |
1da177e4 LT |
1420 | } |
1421 | ||
f2eace23 IM |
1422 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1423 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1424 | return NULL; |
1425 | } | |
1426 | ||
1427 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1428 | { | |
1b1dcc1b | 1429 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1430 | if (p1 != p2) { |
1b1dcc1b | 1431 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1432 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1433 | } |
1434 | } | |
1435 | ||
1436 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1437 | struct nameidata *nd) | |
1438 | { | |
a95164d9 | 1439 | int error = may_create(dir, dentry); |
1da177e4 LT |
1440 | |
1441 | if (error) | |
1442 | return error; | |
1443 | ||
acfa4380 | 1444 | if (!dir->i_op->create) |
1da177e4 LT |
1445 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1446 | mode &= S_IALLUGO; | |
1447 | mode |= S_IFREG; | |
1448 | error = security_inode_create(dir, dentry, mode); | |
1449 | if (error) | |
1450 | return error; | |
9e3509e2 | 1451 | vfs_dq_init(dir); |
1da177e4 | 1452 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1453 | if (!error) |
f38aa942 | 1454 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1455 | return error; |
1456 | } | |
1457 | ||
3fb64190 | 1458 | int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1459 | { |
3fb64190 | 1460 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1461 | struct inode *inode = dentry->d_inode; |
1462 | int error; | |
1463 | ||
1464 | if (!inode) | |
1465 | return -ENOENT; | |
1466 | ||
c8fe8f30 CH |
1467 | switch (inode->i_mode & S_IFMT) { |
1468 | case S_IFLNK: | |
1da177e4 | 1469 | return -ELOOP; |
c8fe8f30 CH |
1470 | case S_IFDIR: |
1471 | if (acc_mode & MAY_WRITE) | |
1472 | return -EISDIR; | |
1473 | break; | |
1474 | case S_IFBLK: | |
1475 | case S_IFCHR: | |
3fb64190 | 1476 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 1477 | return -EACCES; |
c8fe8f30 CH |
1478 | /*FALLTHRU*/ |
1479 | case S_IFIFO: | |
1480 | case S_IFSOCK: | |
1da177e4 | 1481 | flag &= ~O_TRUNC; |
c8fe8f30 | 1482 | break; |
4a3fd211 | 1483 | } |
b41572e9 | 1484 | |
3fb64190 | 1485 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
1486 | if (error) |
1487 | return error; | |
6146f0d5 | 1488 | |
1da177e4 LT |
1489 | /* |
1490 | * An append-only file must be opened in append mode for writing. | |
1491 | */ | |
1492 | if (IS_APPEND(inode)) { | |
8737c930 | 1493 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 1494 | return -EPERM; |
1da177e4 | 1495 | if (flag & O_TRUNC) |
7715b521 | 1496 | return -EPERM; |
1da177e4 LT |
1497 | } |
1498 | ||
1499 | /* O_NOATIME can only be set by the owner or superuser */ | |
7715b521 AV |
1500 | if (flag & O_NOATIME && !is_owner_or_cap(inode)) |
1501 | return -EPERM; | |
1da177e4 LT |
1502 | |
1503 | /* | |
1504 | * Ensure there are no outstanding leases on the file. | |
1505 | */ | |
b65a9cfc | 1506 | return break_lease(inode, flag); |
7715b521 | 1507 | } |
1da177e4 | 1508 | |
7715b521 AV |
1509 | static int handle_truncate(struct path *path) |
1510 | { | |
1511 | struct inode *inode = path->dentry->d_inode; | |
1512 | int error = get_write_access(inode); | |
1513 | if (error) | |
1514 | return error; | |
1515 | /* | |
1516 | * Refuse to truncate files with mandatory locks held on them. | |
1517 | */ | |
1518 | error = locks_verify_locked(inode); | |
1519 | if (!error) | |
1520 | error = security_path_truncate(path, 0, | |
1521 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); | |
1522 | if (!error) { | |
1523 | error = do_truncate(path->dentry, 0, | |
1524 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
1525 | NULL); | |
1526 | } | |
1527 | put_write_access(inode); | |
acd0c935 | 1528 | return error; |
1da177e4 LT |
1529 | } |
1530 | ||
d57999e1 DH |
1531 | /* |
1532 | * Be careful about ever adding any more callers of this | |
1533 | * function. Its flags must be in the namei format, not | |
1534 | * what get passed to sys_open(). | |
1535 | */ | |
1536 | static int __open_namei_create(struct nameidata *nd, struct path *path, | |
8737c930 | 1537 | int open_flag, int mode) |
aab520e2 DH |
1538 | { |
1539 | int error; | |
4ac91378 | 1540 | struct dentry *dir = nd->path.dentry; |
aab520e2 DH |
1541 | |
1542 | if (!IS_POSIXACL(dir->d_inode)) | |
ce3b0f8d | 1543 | mode &= ~current_umask(); |
be6d3e56 KT |
1544 | error = security_path_mknod(&nd->path, path->dentry, mode, 0); |
1545 | if (error) | |
1546 | goto out_unlock; | |
aab520e2 | 1547 | error = vfs_create(dir->d_inode, path->dentry, mode, nd); |
be6d3e56 | 1548 | out_unlock: |
aab520e2 | 1549 | mutex_unlock(&dir->d_inode->i_mutex); |
4ac91378 JB |
1550 | dput(nd->path.dentry); |
1551 | nd->path.dentry = path->dentry; | |
aab520e2 DH |
1552 | if (error) |
1553 | return error; | |
1554 | /* Don't check for write permission, don't truncate */ | |
8737c930 | 1555 | return may_open(&nd->path, 0, open_flag & ~O_TRUNC); |
aab520e2 DH |
1556 | } |
1557 | ||
d57999e1 DH |
1558 | /* |
1559 | * Note that while the flag value (low two bits) for sys_open means: | |
1560 | * 00 - read-only | |
1561 | * 01 - write-only | |
1562 | * 10 - read-write | |
1563 | * 11 - special | |
1564 | * it is changed into | |
1565 | * 00 - no permissions needed | |
1566 | * 01 - read-permission | |
1567 | * 10 - write-permission | |
1568 | * 11 - read-write | |
1569 | * for the internal routines (ie open_namei()/follow_link() etc) | |
1570 | * This is more logical, and also allows the 00 "no perm needed" | |
1571 | * to be used for symlinks (where the permissions are checked | |
1572 | * later). | |
1573 | * | |
1574 | */ | |
1575 | static inline int open_to_namei_flags(int flag) | |
1576 | { | |
1577 | if ((flag+1) & O_ACCMODE) | |
1578 | flag++; | |
1579 | return flag; | |
1580 | } | |
1581 | ||
7715b521 | 1582 | static int open_will_truncate(int flag, struct inode *inode) |
4a3fd211 DH |
1583 | { |
1584 | /* | |
1585 | * We'll never write to the fs underlying | |
1586 | * a device file. | |
1587 | */ | |
1588 | if (special_file(inode->i_mode)) | |
1589 | return 0; | |
1590 | return (flag & O_TRUNC); | |
1591 | } | |
1592 | ||
648fa861 AV |
1593 | static struct file *finish_open(struct nameidata *nd, |
1594 | int open_flag, int flag, int acc_mode) | |
1595 | { | |
1596 | struct file *filp; | |
1597 | int will_truncate; | |
1598 | int error; | |
1599 | ||
1600 | will_truncate = open_will_truncate(flag, nd->path.dentry->d_inode); | |
1601 | if (will_truncate) { | |
1602 | error = mnt_want_write(nd->path.mnt); | |
1603 | if (error) | |
1604 | goto exit; | |
1605 | } | |
1606 | error = may_open(&nd->path, acc_mode, open_flag); | |
1607 | if (error) { | |
1608 | if (will_truncate) | |
1609 | mnt_drop_write(nd->path.mnt); | |
1610 | goto exit; | |
1611 | } | |
1612 | filp = nameidata_to_filp(nd); | |
1613 | if (!IS_ERR(filp)) { | |
1614 | error = ima_file_check(filp, acc_mode); | |
1615 | if (error) { | |
1616 | fput(filp); | |
1617 | filp = ERR_PTR(error); | |
1618 | } | |
1619 | } | |
1620 | if (!IS_ERR(filp)) { | |
1621 | if (acc_mode & MAY_WRITE) | |
1622 | vfs_dq_init(nd->path.dentry->d_inode); | |
1623 | ||
1624 | if (will_truncate) { | |
1625 | error = handle_truncate(&nd->path); | |
1626 | if (error) { | |
1627 | fput(filp); | |
1628 | filp = ERR_PTR(error); | |
1629 | } | |
1630 | } | |
1631 | } | |
1632 | /* | |
1633 | * It is now safe to drop the mnt write | |
1634 | * because the filp has had a write taken | |
1635 | * on its behalf. | |
1636 | */ | |
1637 | if (will_truncate) | |
1638 | mnt_drop_write(nd->path.mnt); | |
1639 | return filp; | |
1640 | ||
1641 | exit: | |
1642 | if (!IS_ERR(nd->intent.open.file)) | |
1643 | release_open_intent(nd); | |
1644 | path_put(&nd->path); | |
1645 | return ERR_PTR(error); | |
1646 | } | |
1647 | ||
fb1cc555 AV |
1648 | static struct file *do_last(struct nameidata *nd, struct path *path, |
1649 | int open_flag, int flag, int acc_mode, | |
1650 | int mode, const char *pathname, | |
1651 | struct dentry *dir, int *is_link) | |
1652 | { | |
1653 | struct file *filp; | |
1654 | int error; | |
1655 | ||
1656 | *is_link = 0; | |
1657 | ||
1658 | error = PTR_ERR(path->dentry); | |
1659 | if (IS_ERR(path->dentry)) { | |
1660 | mutex_unlock(&dir->d_inode->i_mutex); | |
1661 | goto exit; | |
1662 | } | |
1663 | ||
1664 | if (IS_ERR(nd->intent.open.file)) { | |
1665 | error = PTR_ERR(nd->intent.open.file); | |
1666 | goto exit_mutex_unlock; | |
1667 | } | |
1668 | ||
1669 | /* Negative dentry, just create the file */ | |
1670 | if (!path->dentry->d_inode) { | |
1671 | /* | |
1672 | * This write is needed to ensure that a | |
1673 | * ro->rw transition does not occur between | |
1674 | * the time when the file is created and when | |
1675 | * a permanent write count is taken through | |
1676 | * the 'struct file' in nameidata_to_filp(). | |
1677 | */ | |
1678 | error = mnt_want_write(nd->path.mnt); | |
1679 | if (error) | |
1680 | goto exit_mutex_unlock; | |
1681 | error = __open_namei_create(nd, path, open_flag, mode); | |
1682 | if (error) { | |
1683 | mnt_drop_write(nd->path.mnt); | |
1684 | goto exit; | |
1685 | } | |
1686 | filp = nameidata_to_filp(nd); | |
1687 | mnt_drop_write(nd->path.mnt); | |
fb1cc555 AV |
1688 | if (!IS_ERR(filp)) { |
1689 | error = ima_file_check(filp, acc_mode); | |
1690 | if (error) { | |
1691 | fput(filp); | |
1692 | filp = ERR_PTR(error); | |
1693 | } | |
1694 | } | |
1695 | return filp; | |
1696 | } | |
1697 | ||
1698 | /* | |
1699 | * It already exists. | |
1700 | */ | |
1701 | mutex_unlock(&dir->d_inode->i_mutex); | |
1702 | audit_inode(pathname, path->dentry); | |
1703 | ||
1704 | error = -EEXIST; | |
1705 | if (flag & O_EXCL) | |
1706 | goto exit_dput; | |
1707 | ||
1708 | if (__follow_mount(path)) { | |
1709 | error = -ELOOP; | |
1710 | if (flag & O_NOFOLLOW) | |
1711 | goto exit_dput; | |
1712 | } | |
1713 | ||
1714 | error = -ENOENT; | |
1715 | if (!path->dentry->d_inode) | |
1716 | goto exit_dput; | |
1717 | if (path->dentry->d_inode->i_op->follow_link) { | |
1718 | *is_link = 1; | |
1719 | return NULL; | |
1720 | } | |
1721 | ||
1722 | path_to_nameidata(path, nd); | |
1723 | error = -EISDIR; | |
1724 | if (S_ISDIR(path->dentry->d_inode->i_mode)) | |
1725 | goto exit; | |
1726 | filp = finish_open(nd, open_flag, flag, acc_mode); | |
fb1cc555 AV |
1727 | return filp; |
1728 | ||
1729 | exit_mutex_unlock: | |
1730 | mutex_unlock(&dir->d_inode->i_mutex); | |
1731 | exit_dput: | |
1732 | path_put_conditional(path, nd); | |
1733 | exit: | |
1734 | if (!IS_ERR(nd->intent.open.file)) | |
1735 | release_open_intent(nd); | |
fb1cc555 AV |
1736 | path_put(&nd->path); |
1737 | return ERR_PTR(error); | |
1738 | } | |
1739 | ||
1da177e4 | 1740 | /* |
4a3fd211 DH |
1741 | * Note that the low bits of the passed in "open_flag" |
1742 | * are not the same as in the local variable "flag". See | |
1743 | * open_to_namei_flags() for more details. | |
1da177e4 | 1744 | */ |
a70e65df | 1745 | struct file *do_filp_open(int dfd, const char *pathname, |
6e8341a1 | 1746 | int open_flag, int mode, int acc_mode) |
1da177e4 | 1747 | { |
4a3fd211 | 1748 | struct file *filp; |
a70e65df | 1749 | struct nameidata nd; |
6e8341a1 | 1750 | int error; |
9850c056 | 1751 | struct path path; |
1da177e4 LT |
1752 | struct dentry *dir; |
1753 | int count = 0; | |
d57999e1 | 1754 | int flag = open_to_namei_flags(open_flag); |
9850c056 | 1755 | int force_reval = 0; |
fb1cc555 | 1756 | int is_link; |
1da177e4 | 1757 | |
6b2f3d1f CH |
1758 | /* |
1759 | * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only | |
1760 | * check for O_DSYNC if the need any syncing at all we enforce it's | |
1761 | * always set instead of having to deal with possibly weird behaviour | |
1762 | * for malicious applications setting only __O_SYNC. | |
1763 | */ | |
1764 | if (open_flag & __O_SYNC) | |
1765 | open_flag |= O_DSYNC; | |
1766 | ||
6e8341a1 | 1767 | if (!acc_mode) |
6d125529 | 1768 | acc_mode = MAY_OPEN | ACC_MODE(open_flag); |
1da177e4 | 1769 | |
834f2a4a TM |
1770 | /* O_TRUNC implies we need access checks for write permissions */ |
1771 | if (flag & O_TRUNC) | |
1772 | acc_mode |= MAY_WRITE; | |
1773 | ||
1da177e4 LT |
1774 | /* Allow the LSM permission hook to distinguish append |
1775 | access from general write access. */ | |
1776 | if (flag & O_APPEND) | |
1777 | acc_mode |= MAY_APPEND; | |
1778 | ||
1da177e4 LT |
1779 | /* |
1780 | * The simplest case - just a plain lookup. | |
1781 | */ | |
1782 | if (!(flag & O_CREAT)) { | |
2dd6d1f4 AV |
1783 | filp = get_empty_filp(); |
1784 | ||
1785 | if (filp == NULL) | |
1786 | return ERR_PTR(-ENFILE); | |
1787 | nd.intent.open.file = filp; | |
482928d5 | 1788 | filp->f_flags = open_flag; |
2dd6d1f4 AV |
1789 | nd.intent.open.flags = flag; |
1790 | nd.intent.open.create_mode = 0; | |
1791 | error = do_path_lookup(dfd, pathname, | |
1792 | lookup_flags(flag)|LOOKUP_OPEN, &nd); | |
1793 | if (IS_ERR(nd.intent.open.file)) { | |
1794 | if (error == 0) { | |
1795 | error = PTR_ERR(nd.intent.open.file); | |
1796 | path_put(&nd.path); | |
1797 | } | |
1798 | } else if (error) | |
1799 | release_open_intent(&nd); | |
1da177e4 | 1800 | if (error) |
a70e65df | 1801 | return ERR_PTR(error); |
1da177e4 LT |
1802 | goto ok; |
1803 | } | |
1804 | ||
1805 | /* | |
1806 | * Create - we need to know the parent. | |
1807 | */ | |
9850c056 | 1808 | reval: |
9b4a9b14 | 1809 | error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); |
1da177e4 | 1810 | if (error) |
a70e65df | 1811 | return ERR_PTR(error); |
9850c056 AV |
1812 | if (force_reval) |
1813 | nd.flags |= LOOKUP_REVAL; | |
9b4a9b14 | 1814 | error = path_walk(pathname, &nd); |
654f562c O |
1815 | if (error) { |
1816 | if (nd.root.mnt) | |
1817 | path_put(&nd.root); | |
9b4a9b14 | 1818 | return ERR_PTR(error); |
654f562c | 1819 | } |
9b4a9b14 AV |
1820 | if (unlikely(!audit_dummy_context())) |
1821 | audit_inode(pathname, nd.path.dentry); | |
1da177e4 LT |
1822 | |
1823 | /* | |
1824 | * We have the parent and last component. First of all, check | |
1825 | * that we are not asked to creat(2) an obvious directory - that | |
1826 | * will not do. | |
1827 | */ | |
1828 | error = -EISDIR; | |
a70e65df | 1829 | if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) |
8737f3a1 | 1830 | goto exit_parent; |
1da177e4 | 1831 | |
8737f3a1 AV |
1832 | error = -ENFILE; |
1833 | filp = get_empty_filp(); | |
1834 | if (filp == NULL) | |
1835 | goto exit_parent; | |
1836 | nd.intent.open.file = filp; | |
482928d5 | 1837 | filp->f_flags = open_flag; |
8737f3a1 AV |
1838 | nd.intent.open.flags = flag; |
1839 | nd.intent.open.create_mode = mode; | |
a70e65df CH |
1840 | dir = nd.path.dentry; |
1841 | nd.flags &= ~LOOKUP_PARENT; | |
8737f3a1 | 1842 | nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; |
3516586a AV |
1843 | if (flag & O_EXCL) |
1844 | nd.flags |= LOOKUP_EXCL; | |
1b1dcc1b | 1845 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1846 | path.dentry = lookup_hash(&nd); |
1847 | path.mnt = nd.path.mnt; | |
fb1cc555 AV |
1848 | filp = do_last(&nd, &path, open_flag, flag, acc_mode, mode, |
1849 | pathname, dir, &is_link); | |
1850 | if (is_link) | |
1da177e4 | 1851 | goto do_link; |
3343eb82 AV |
1852 | if (nd.root.mnt) |
1853 | path_put(&nd.root); | |
fb1cc555 | 1854 | return filp; |
1da177e4 | 1855 | |
1da177e4 | 1856 | ok: |
648fa861 | 1857 | filp = finish_open(&nd, open_flag, flag, acc_mode); |
654f562c O |
1858 | if (nd.root.mnt) |
1859 | path_put(&nd.root); | |
4a3fd211 | 1860 | return filp; |
1da177e4 LT |
1861 | |
1862 | exit_dput: | |
a70e65df | 1863 | path_put_conditional(&path, &nd); |
1da177e4 | 1864 | exit: |
a70e65df CH |
1865 | if (!IS_ERR(nd.intent.open.file)) |
1866 | release_open_intent(&nd); | |
8737f3a1 | 1867 | exit_parent: |
2a737871 AV |
1868 | if (nd.root.mnt) |
1869 | path_put(&nd.root); | |
a70e65df CH |
1870 | path_put(&nd.path); |
1871 | return ERR_PTR(error); | |
1da177e4 LT |
1872 | |
1873 | do_link: | |
1874 | error = -ELOOP; | |
1875 | if (flag & O_NOFOLLOW) | |
1876 | goto exit_dput; | |
1877 | /* | |
1878 | * This is subtle. Instead of calling do_follow_link() we do the | |
1879 | * thing by hands. The reason is that this way we have zero link_count | |
1880 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1881 | * After that we have the parent and last component, i.e. | |
1882 | * we are in the same situation as after the first path_walk(). | |
1883 | * Well, almost - if the last component is normal we get its copy | |
1884 | * stored in nd->last.name and we will have to putname() it when we | |
1885 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1886 | */ | |
a70e65df CH |
1887 | nd.flags |= LOOKUP_PARENT; |
1888 | error = security_inode_follow_link(path.dentry, &nd); | |
1da177e4 LT |
1889 | if (error) |
1890 | goto exit_dput; | |
a70e65df | 1891 | error = __do_follow_link(&path, &nd); |
258fa999 | 1892 | path_put(&path); |
de459215 KK |
1893 | if (error) { |
1894 | /* Does someone understand code flow here? Or it is only | |
1895 | * me so stupid? Anathema to whoever designed this non-sense | |
1896 | * with "intent.open". | |
1897 | */ | |
a70e65df | 1898 | release_open_intent(&nd); |
654f562c O |
1899 | if (nd.root.mnt) |
1900 | path_put(&nd.root); | |
9850c056 AV |
1901 | if (error == -ESTALE && !force_reval) { |
1902 | force_reval = 1; | |
1903 | goto reval; | |
1904 | } | |
a70e65df | 1905 | return ERR_PTR(error); |
de459215 | 1906 | } |
a70e65df CH |
1907 | nd.flags &= ~LOOKUP_PARENT; |
1908 | if (nd.last_type == LAST_BIND) | |
1da177e4 | 1909 | goto ok; |
1da177e4 | 1910 | error = -EISDIR; |
a70e65df | 1911 | if (nd.last_type != LAST_NORM) |
1da177e4 | 1912 | goto exit; |
a70e65df CH |
1913 | if (nd.last.name[nd.last.len]) { |
1914 | __putname(nd.last.name); | |
1da177e4 LT |
1915 | goto exit; |
1916 | } | |
1917 | error = -ELOOP; | |
1918 | if (count++==32) { | |
a70e65df | 1919 | __putname(nd.last.name); |
1da177e4 LT |
1920 | goto exit; |
1921 | } | |
a70e65df | 1922 | dir = nd.path.dentry; |
1b1dcc1b | 1923 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1924 | path.dentry = lookup_hash(&nd); |
1925 | path.mnt = nd.path.mnt; | |
27bff343 AV |
1926 | filp = do_last(&nd, &path, open_flag, flag, acc_mode, mode, |
1927 | pathname, dir, &is_link); | |
c41c1405 | 1928 | __putname(nd.last.name); |
27bff343 AV |
1929 | if (is_link) |
1930 | goto do_link; | |
1931 | if (nd.root.mnt) | |
1932 | path_put(&nd.root); | |
1933 | return filp; | |
1da177e4 LT |
1934 | } |
1935 | ||
a70e65df CH |
1936 | /** |
1937 | * filp_open - open file and return file pointer | |
1938 | * | |
1939 | * @filename: path to open | |
1940 | * @flags: open flags as per the open(2) second argument | |
1941 | * @mode: mode for the new file if O_CREAT is set, else ignored | |
1942 | * | |
1943 | * This is the helper to open a file from kernelspace if you really | |
1944 | * have to. But in generally you should not do this, so please move | |
1945 | * along, nothing to see here.. | |
1946 | */ | |
1947 | struct file *filp_open(const char *filename, int flags, int mode) | |
1948 | { | |
6e8341a1 | 1949 | return do_filp_open(AT_FDCWD, filename, flags, mode, 0); |
a70e65df CH |
1950 | } |
1951 | EXPORT_SYMBOL(filp_open); | |
1952 | ||
1da177e4 LT |
1953 | /** |
1954 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
1955 | * @nd: nameidata info | |
1956 | * @is_dir: directory flag | |
1957 | * | |
1958 | * Simple function to lookup and return a dentry and create it | |
1959 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 | 1960 | * |
4ac91378 | 1961 | * Returns with nd->path.dentry->d_inode->i_mutex locked. |
1da177e4 LT |
1962 | */ |
1963 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
1964 | { | |
c663e5d8 | 1965 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 | 1966 | |
4ac91378 | 1967 | mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
c663e5d8 CH |
1968 | /* |
1969 | * Yucky last component or no last component at all? | |
1970 | * (foo/., foo/.., /////) | |
1971 | */ | |
1da177e4 LT |
1972 | if (nd->last_type != LAST_NORM) |
1973 | goto fail; | |
1974 | nd->flags &= ~LOOKUP_PARENT; | |
3516586a | 1975 | nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
a634904a | 1976 | nd->intent.open.flags = O_EXCL; |
c663e5d8 CH |
1977 | |
1978 | /* | |
1979 | * Do the final lookup. | |
1980 | */ | |
49705b77 | 1981 | dentry = lookup_hash(nd); |
1da177e4 LT |
1982 | if (IS_ERR(dentry)) |
1983 | goto fail; | |
c663e5d8 | 1984 | |
e9baf6e5 AV |
1985 | if (dentry->d_inode) |
1986 | goto eexist; | |
c663e5d8 CH |
1987 | /* |
1988 | * Special case - lookup gave negative, but... we had foo/bar/ | |
1989 | * From the vfs_mknod() POV we just have a negative dentry - | |
1990 | * all is fine. Let's be bastards - you had / on the end, you've | |
1991 | * been asking for (non-existent) directory. -ENOENT for you. | |
1992 | */ | |
e9baf6e5 AV |
1993 | if (unlikely(!is_dir && nd->last.name[nd->last.len])) { |
1994 | dput(dentry); | |
1995 | dentry = ERR_PTR(-ENOENT); | |
1996 | } | |
1da177e4 | 1997 | return dentry; |
e9baf6e5 | 1998 | eexist: |
1da177e4 | 1999 | dput(dentry); |
e9baf6e5 | 2000 | dentry = ERR_PTR(-EEXIST); |
1da177e4 LT |
2001 | fail: |
2002 | return dentry; | |
2003 | } | |
f81a0bff | 2004 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
2005 | |
2006 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
2007 | { | |
a95164d9 | 2008 | int error = may_create(dir, dentry); |
1da177e4 LT |
2009 | |
2010 | if (error) | |
2011 | return error; | |
2012 | ||
2013 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
2014 | return -EPERM; | |
2015 | ||
acfa4380 | 2016 | if (!dir->i_op->mknod) |
1da177e4 LT |
2017 | return -EPERM; |
2018 | ||
08ce5f16 SH |
2019 | error = devcgroup_inode_mknod(mode, dev); |
2020 | if (error) | |
2021 | return error; | |
2022 | ||
1da177e4 LT |
2023 | error = security_inode_mknod(dir, dentry, mode, dev); |
2024 | if (error) | |
2025 | return error; | |
2026 | ||
9e3509e2 | 2027 | vfs_dq_init(dir); |
1da177e4 | 2028 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 2029 | if (!error) |
f38aa942 | 2030 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2031 | return error; |
2032 | } | |
2033 | ||
463c3197 DH |
2034 | static int may_mknod(mode_t mode) |
2035 | { | |
2036 | switch (mode & S_IFMT) { | |
2037 | case S_IFREG: | |
2038 | case S_IFCHR: | |
2039 | case S_IFBLK: | |
2040 | case S_IFIFO: | |
2041 | case S_IFSOCK: | |
2042 | case 0: /* zero mode translates to S_IFREG */ | |
2043 | return 0; | |
2044 | case S_IFDIR: | |
2045 | return -EPERM; | |
2046 | default: | |
2047 | return -EINVAL; | |
2048 | } | |
2049 | } | |
2050 | ||
2e4d0924 HC |
2051 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2052 | unsigned, dev) | |
1da177e4 | 2053 | { |
2ad94ae6 AV |
2054 | int error; |
2055 | char *tmp; | |
2056 | struct dentry *dentry; | |
1da177e4 LT |
2057 | struct nameidata nd; |
2058 | ||
2059 | if (S_ISDIR(mode)) | |
2060 | return -EPERM; | |
1da177e4 | 2061 | |
2ad94ae6 | 2062 | error = user_path_parent(dfd, filename, &nd, &tmp); |
1da177e4 | 2063 | if (error) |
2ad94ae6 AV |
2064 | return error; |
2065 | ||
1da177e4 | 2066 | dentry = lookup_create(&nd, 0); |
463c3197 DH |
2067 | if (IS_ERR(dentry)) { |
2068 | error = PTR_ERR(dentry); | |
2069 | goto out_unlock; | |
2070 | } | |
4ac91378 | 2071 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
ce3b0f8d | 2072 | mode &= ~current_umask(); |
463c3197 DH |
2073 | error = may_mknod(mode); |
2074 | if (error) | |
2075 | goto out_dput; | |
2076 | error = mnt_want_write(nd.path.mnt); | |
2077 | if (error) | |
2078 | goto out_dput; | |
be6d3e56 KT |
2079 | error = security_path_mknod(&nd.path, dentry, mode, dev); |
2080 | if (error) | |
2081 | goto out_drop_write; | |
463c3197 | 2082 | switch (mode & S_IFMT) { |
1da177e4 | 2083 | case 0: case S_IFREG: |
4ac91378 | 2084 | error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); |
1da177e4 LT |
2085 | break; |
2086 | case S_IFCHR: case S_IFBLK: | |
4ac91378 | 2087 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2088 | new_decode_dev(dev)); |
2089 | break; | |
2090 | case S_IFIFO: case S_IFSOCK: | |
4ac91378 | 2091 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2092 | break; |
1da177e4 | 2093 | } |
be6d3e56 | 2094 | out_drop_write: |
463c3197 DH |
2095 | mnt_drop_write(nd.path.mnt); |
2096 | out_dput: | |
2097 | dput(dentry); | |
2098 | out_unlock: | |
4ac91378 | 2099 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2100 | path_put(&nd.path); |
1da177e4 LT |
2101 | putname(tmp); |
2102 | ||
2103 | return error; | |
2104 | } | |
2105 | ||
3480b257 | 2106 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2107 | { |
2108 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2109 | } | |
2110 | ||
1da177e4 LT |
2111 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2112 | { | |
a95164d9 | 2113 | int error = may_create(dir, dentry); |
1da177e4 LT |
2114 | |
2115 | if (error) | |
2116 | return error; | |
2117 | ||
acfa4380 | 2118 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2119 | return -EPERM; |
2120 | ||
2121 | mode &= (S_IRWXUGO|S_ISVTX); | |
2122 | error = security_inode_mkdir(dir, dentry, mode); | |
2123 | if (error) | |
2124 | return error; | |
2125 | ||
9e3509e2 | 2126 | vfs_dq_init(dir); |
1da177e4 | 2127 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2128 | if (!error) |
f38aa942 | 2129 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2130 | return error; |
2131 | } | |
2132 | ||
2e4d0924 | 2133 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 LT |
2134 | { |
2135 | int error = 0; | |
2136 | char * tmp; | |
6902d925 DH |
2137 | struct dentry *dentry; |
2138 | struct nameidata nd; | |
1da177e4 | 2139 | |
2ad94ae6 AV |
2140 | error = user_path_parent(dfd, pathname, &nd, &tmp); |
2141 | if (error) | |
6902d925 | 2142 | goto out_err; |
1da177e4 | 2143 | |
6902d925 DH |
2144 | dentry = lookup_create(&nd, 1); |
2145 | error = PTR_ERR(dentry); | |
2146 | if (IS_ERR(dentry)) | |
2147 | goto out_unlock; | |
1da177e4 | 2148 | |
4ac91378 | 2149 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
ce3b0f8d | 2150 | mode &= ~current_umask(); |
463c3197 DH |
2151 | error = mnt_want_write(nd.path.mnt); |
2152 | if (error) | |
2153 | goto out_dput; | |
be6d3e56 KT |
2154 | error = security_path_mkdir(&nd.path, dentry, mode); |
2155 | if (error) | |
2156 | goto out_drop_write; | |
4ac91378 | 2157 | error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2158 | out_drop_write: |
463c3197 DH |
2159 | mnt_drop_write(nd.path.mnt); |
2160 | out_dput: | |
6902d925 DH |
2161 | dput(dentry); |
2162 | out_unlock: | |
4ac91378 | 2163 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2164 | path_put(&nd.path); |
6902d925 DH |
2165 | putname(tmp); |
2166 | out_err: | |
1da177e4 LT |
2167 | return error; |
2168 | } | |
2169 | ||
3cdad428 | 2170 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2171 | { |
2172 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2173 | } | |
2174 | ||
1da177e4 LT |
2175 | /* |
2176 | * We try to drop the dentry early: we should have | |
2177 | * a usage count of 2 if we're the only user of this | |
2178 | * dentry, and if that is true (possibly after pruning | |
2179 | * the dcache), then we drop the dentry now. | |
2180 | * | |
2181 | * A low-level filesystem can, if it choses, legally | |
2182 | * do a | |
2183 | * | |
2184 | * if (!d_unhashed(dentry)) | |
2185 | * return -EBUSY; | |
2186 | * | |
2187 | * if it cannot handle the case of removing a directory | |
2188 | * that is still in use by something else.. | |
2189 | */ | |
2190 | void dentry_unhash(struct dentry *dentry) | |
2191 | { | |
2192 | dget(dentry); | |
dc168427 | 2193 | shrink_dcache_parent(dentry); |
1da177e4 LT |
2194 | spin_lock(&dcache_lock); |
2195 | spin_lock(&dentry->d_lock); | |
2196 | if (atomic_read(&dentry->d_count) == 2) | |
2197 | __d_drop(dentry); | |
2198 | spin_unlock(&dentry->d_lock); | |
2199 | spin_unlock(&dcache_lock); | |
2200 | } | |
2201 | ||
2202 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2203 | { | |
2204 | int error = may_delete(dir, dentry, 1); | |
2205 | ||
2206 | if (error) | |
2207 | return error; | |
2208 | ||
acfa4380 | 2209 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2210 | return -EPERM; |
2211 | ||
9e3509e2 | 2212 | vfs_dq_init(dir); |
1da177e4 | 2213 | |
1b1dcc1b | 2214 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2215 | dentry_unhash(dentry); |
2216 | if (d_mountpoint(dentry)) | |
2217 | error = -EBUSY; | |
2218 | else { | |
2219 | error = security_inode_rmdir(dir, dentry); | |
2220 | if (!error) { | |
2221 | error = dir->i_op->rmdir(dir, dentry); | |
2222 | if (!error) | |
2223 | dentry->d_inode->i_flags |= S_DEAD; | |
2224 | } | |
2225 | } | |
1b1dcc1b | 2226 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 | 2227 | if (!error) { |
1da177e4 LT |
2228 | d_delete(dentry); |
2229 | } | |
2230 | dput(dentry); | |
2231 | ||
2232 | return error; | |
2233 | } | |
2234 | ||
5590ff0d | 2235 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2236 | { |
2237 | int error = 0; | |
2238 | char * name; | |
2239 | struct dentry *dentry; | |
2240 | struct nameidata nd; | |
2241 | ||
2ad94ae6 | 2242 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2243 | if (error) |
2ad94ae6 | 2244 | return error; |
1da177e4 LT |
2245 | |
2246 | switch(nd.last_type) { | |
0612d9fb OH |
2247 | case LAST_DOTDOT: |
2248 | error = -ENOTEMPTY; | |
2249 | goto exit1; | |
2250 | case LAST_DOT: | |
2251 | error = -EINVAL; | |
2252 | goto exit1; | |
2253 | case LAST_ROOT: | |
2254 | error = -EBUSY; | |
2255 | goto exit1; | |
1da177e4 | 2256 | } |
0612d9fb OH |
2257 | |
2258 | nd.flags &= ~LOOKUP_PARENT; | |
2259 | ||
4ac91378 | 2260 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2261 | dentry = lookup_hash(&nd); |
1da177e4 | 2262 | error = PTR_ERR(dentry); |
6902d925 DH |
2263 | if (IS_ERR(dentry)) |
2264 | goto exit2; | |
0622753b DH |
2265 | error = mnt_want_write(nd.path.mnt); |
2266 | if (error) | |
2267 | goto exit3; | |
be6d3e56 KT |
2268 | error = security_path_rmdir(&nd.path, dentry); |
2269 | if (error) | |
2270 | goto exit4; | |
4ac91378 | 2271 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2272 | exit4: |
0622753b DH |
2273 | mnt_drop_write(nd.path.mnt); |
2274 | exit3: | |
6902d925 DH |
2275 | dput(dentry); |
2276 | exit2: | |
4ac91378 | 2277 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2278 | exit1: |
1d957f9b | 2279 | path_put(&nd.path); |
1da177e4 LT |
2280 | putname(name); |
2281 | return error; | |
2282 | } | |
2283 | ||
3cdad428 | 2284 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2285 | { |
2286 | return do_rmdir(AT_FDCWD, pathname); | |
2287 | } | |
2288 | ||
1da177e4 LT |
2289 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2290 | { | |
2291 | int error = may_delete(dir, dentry, 0); | |
2292 | ||
2293 | if (error) | |
2294 | return error; | |
2295 | ||
acfa4380 | 2296 | if (!dir->i_op->unlink) |
1da177e4 LT |
2297 | return -EPERM; |
2298 | ||
9e3509e2 | 2299 | vfs_dq_init(dir); |
1da177e4 | 2300 | |
1b1dcc1b | 2301 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2302 | if (d_mountpoint(dentry)) |
2303 | error = -EBUSY; | |
2304 | else { | |
2305 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 2306 | if (!error) { |
1da177e4 | 2307 | error = dir->i_op->unlink(dir, dentry); |
bec1052e AV |
2308 | if (!error) |
2309 | dentry->d_inode->i_flags |= S_DEAD; | |
2310 | } | |
1da177e4 | 2311 | } |
1b1dcc1b | 2312 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2313 | |
2314 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2315 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2316 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2317 | d_delete(dentry); |
1da177e4 | 2318 | } |
0eeca283 | 2319 | |
1da177e4 LT |
2320 | return error; |
2321 | } | |
2322 | ||
2323 | /* | |
2324 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2325 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2326 | * writeout happening, and we don't want to prevent access to the directory |
2327 | * while waiting on the I/O. | |
2328 | */ | |
5590ff0d | 2329 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2330 | { |
2ad94ae6 AV |
2331 | int error; |
2332 | char *name; | |
1da177e4 LT |
2333 | struct dentry *dentry; |
2334 | struct nameidata nd; | |
2335 | struct inode *inode = NULL; | |
2336 | ||
2ad94ae6 | 2337 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2338 | if (error) |
2ad94ae6 AV |
2339 | return error; |
2340 | ||
1da177e4 LT |
2341 | error = -EISDIR; |
2342 | if (nd.last_type != LAST_NORM) | |
2343 | goto exit1; | |
0612d9fb OH |
2344 | |
2345 | nd.flags &= ~LOOKUP_PARENT; | |
2346 | ||
4ac91378 | 2347 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2348 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2349 | error = PTR_ERR(dentry); |
2350 | if (!IS_ERR(dentry)) { | |
2351 | /* Why not before? Because we want correct error value */ | |
2352 | if (nd.last.name[nd.last.len]) | |
2353 | goto slashes; | |
2354 | inode = dentry->d_inode; | |
2355 | if (inode) | |
2356 | atomic_inc(&inode->i_count); | |
0622753b DH |
2357 | error = mnt_want_write(nd.path.mnt); |
2358 | if (error) | |
2359 | goto exit2; | |
be6d3e56 KT |
2360 | error = security_path_unlink(&nd.path, dentry); |
2361 | if (error) | |
2362 | goto exit3; | |
4ac91378 | 2363 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2364 | exit3: |
0622753b | 2365 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2366 | exit2: |
2367 | dput(dentry); | |
2368 | } | |
4ac91378 | 2369 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2370 | if (inode) |
2371 | iput(inode); /* truncate the inode here */ | |
2372 | exit1: | |
1d957f9b | 2373 | path_put(&nd.path); |
1da177e4 LT |
2374 | putname(name); |
2375 | return error; | |
2376 | ||
2377 | slashes: | |
2378 | error = !dentry->d_inode ? -ENOENT : | |
2379 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2380 | goto exit2; | |
2381 | } | |
2382 | ||
2e4d0924 | 2383 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2384 | { |
2385 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2386 | return -EINVAL; | |
2387 | ||
2388 | if (flag & AT_REMOVEDIR) | |
2389 | return do_rmdir(dfd, pathname); | |
2390 | ||
2391 | return do_unlinkat(dfd, pathname); | |
2392 | } | |
2393 | ||
3480b257 | 2394 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2395 | { |
2396 | return do_unlinkat(AT_FDCWD, pathname); | |
2397 | } | |
2398 | ||
db2e747b | 2399 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2400 | { |
a95164d9 | 2401 | int error = may_create(dir, dentry); |
1da177e4 LT |
2402 | |
2403 | if (error) | |
2404 | return error; | |
2405 | ||
acfa4380 | 2406 | if (!dir->i_op->symlink) |
1da177e4 LT |
2407 | return -EPERM; |
2408 | ||
2409 | error = security_inode_symlink(dir, dentry, oldname); | |
2410 | if (error) | |
2411 | return error; | |
2412 | ||
9e3509e2 | 2413 | vfs_dq_init(dir); |
1da177e4 | 2414 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2415 | if (!error) |
f38aa942 | 2416 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2417 | return error; |
2418 | } | |
2419 | ||
2e4d0924 HC |
2420 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2421 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2422 | { |
2ad94ae6 AV |
2423 | int error; |
2424 | char *from; | |
2425 | char *to; | |
6902d925 DH |
2426 | struct dentry *dentry; |
2427 | struct nameidata nd; | |
1da177e4 LT |
2428 | |
2429 | from = getname(oldname); | |
2ad94ae6 | 2430 | if (IS_ERR(from)) |
1da177e4 | 2431 | return PTR_ERR(from); |
1da177e4 | 2432 | |
2ad94ae6 | 2433 | error = user_path_parent(newdfd, newname, &nd, &to); |
6902d925 | 2434 | if (error) |
2ad94ae6 AV |
2435 | goto out_putname; |
2436 | ||
6902d925 DH |
2437 | dentry = lookup_create(&nd, 0); |
2438 | error = PTR_ERR(dentry); | |
2439 | if (IS_ERR(dentry)) | |
2440 | goto out_unlock; | |
2441 | ||
75c3f29d DH |
2442 | error = mnt_want_write(nd.path.mnt); |
2443 | if (error) | |
2444 | goto out_dput; | |
be6d3e56 KT |
2445 | error = security_path_symlink(&nd.path, dentry, from); |
2446 | if (error) | |
2447 | goto out_drop_write; | |
db2e747b | 2448 | error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); |
be6d3e56 | 2449 | out_drop_write: |
75c3f29d DH |
2450 | mnt_drop_write(nd.path.mnt); |
2451 | out_dput: | |
6902d925 DH |
2452 | dput(dentry); |
2453 | out_unlock: | |
4ac91378 | 2454 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2455 | path_put(&nd.path); |
6902d925 DH |
2456 | putname(to); |
2457 | out_putname: | |
1da177e4 LT |
2458 | putname(from); |
2459 | return error; | |
2460 | } | |
2461 | ||
3480b257 | 2462 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2463 | { |
2464 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2465 | } | |
2466 | ||
1da177e4 LT |
2467 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2468 | { | |
2469 | struct inode *inode = old_dentry->d_inode; | |
2470 | int error; | |
2471 | ||
2472 | if (!inode) | |
2473 | return -ENOENT; | |
2474 | ||
a95164d9 | 2475 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2476 | if (error) |
2477 | return error; | |
2478 | ||
2479 | if (dir->i_sb != inode->i_sb) | |
2480 | return -EXDEV; | |
2481 | ||
2482 | /* | |
2483 | * A link to an append-only or immutable file cannot be created. | |
2484 | */ | |
2485 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2486 | return -EPERM; | |
acfa4380 | 2487 | if (!dir->i_op->link) |
1da177e4 | 2488 | return -EPERM; |
7e79eedb | 2489 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2490 | return -EPERM; |
2491 | ||
2492 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2493 | if (error) | |
2494 | return error; | |
2495 | ||
7e79eedb | 2496 | mutex_lock(&inode->i_mutex); |
9e3509e2 | 2497 | vfs_dq_init(dir); |
1da177e4 | 2498 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
7e79eedb | 2499 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2500 | if (!error) |
7e79eedb | 2501 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2502 | return error; |
2503 | } | |
2504 | ||
2505 | /* | |
2506 | * Hardlinks are often used in delicate situations. We avoid | |
2507 | * security-related surprises by not following symlinks on the | |
2508 | * newname. --KAB | |
2509 | * | |
2510 | * We don't follow them on the oldname either to be compatible | |
2511 | * with linux 2.0, and to avoid hard-linking to directories | |
2512 | * and other special files. --ADM | |
2513 | */ | |
2e4d0924 HC |
2514 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2515 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2516 | { |
2517 | struct dentry *new_dentry; | |
2d8f3038 AV |
2518 | struct nameidata nd; |
2519 | struct path old_path; | |
1da177e4 | 2520 | int error; |
2ad94ae6 | 2521 | char *to; |
1da177e4 | 2522 | |
45c9b11a | 2523 | if ((flags & ~AT_SYMLINK_FOLLOW) != 0) |
c04030e1 UD |
2524 | return -EINVAL; |
2525 | ||
2d8f3038 AV |
2526 | error = user_path_at(olddfd, oldname, |
2527 | flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, | |
2528 | &old_path); | |
1da177e4 | 2529 | if (error) |
2ad94ae6 AV |
2530 | return error; |
2531 | ||
2532 | error = user_path_parent(newdfd, newname, &nd, &to); | |
1da177e4 LT |
2533 | if (error) |
2534 | goto out; | |
2535 | error = -EXDEV; | |
2d8f3038 | 2536 | if (old_path.mnt != nd.path.mnt) |
1da177e4 LT |
2537 | goto out_release; |
2538 | new_dentry = lookup_create(&nd, 0); | |
2539 | error = PTR_ERR(new_dentry); | |
6902d925 DH |
2540 | if (IS_ERR(new_dentry)) |
2541 | goto out_unlock; | |
75c3f29d DH |
2542 | error = mnt_want_write(nd.path.mnt); |
2543 | if (error) | |
2544 | goto out_dput; | |
be6d3e56 KT |
2545 | error = security_path_link(old_path.dentry, &nd.path, new_dentry); |
2546 | if (error) | |
2547 | goto out_drop_write; | |
2d8f3038 | 2548 | error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); |
be6d3e56 | 2549 | out_drop_write: |
75c3f29d DH |
2550 | mnt_drop_write(nd.path.mnt); |
2551 | out_dput: | |
6902d925 DH |
2552 | dput(new_dentry); |
2553 | out_unlock: | |
4ac91378 | 2554 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2555 | out_release: |
1d957f9b | 2556 | path_put(&nd.path); |
2ad94ae6 | 2557 | putname(to); |
1da177e4 | 2558 | out: |
2d8f3038 | 2559 | path_put(&old_path); |
1da177e4 LT |
2560 | |
2561 | return error; | |
2562 | } | |
2563 | ||
3480b257 | 2564 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2565 | { |
c04030e1 | 2566 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2567 | } |
2568 | ||
1da177e4 LT |
2569 | /* |
2570 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2571 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2572 | * Problems: | |
2573 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2574 | * b) race potential - two innocent renames can create a loop together. | |
2575 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2576 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2577 | * story. |
2578 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2579 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2580 | * whether the target exists). Solution: try to be smart with locking |
2581 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2582 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2583 | * move will be locked. Thus we can rank directories by the tree |
2584 | * (ancestors first) and rank all non-directories after them. | |
2585 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2586 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2587 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2588 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2589 | * we'd better make sure that there's no link(2) for them. | |
2590 | * d) some filesystems don't support opened-but-unlinked directories, | |
2591 | * either because of layout or because they are not ready to deal with | |
2592 | * all cases correctly. The latter will be fixed (taking this sort of | |
2593 | * stuff into VFS), but the former is not going away. Solution: the same | |
2594 | * trick as in rmdir(). | |
2595 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
1b1dcc1b | 2596 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2597 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
1b1dcc1b | 2598 | * ->i_mutex on parents, which works but leads to some truely excessive |
1da177e4 LT |
2599 | * locking]. |
2600 | */ | |
75c96f85 AB |
2601 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2602 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2603 | { |
2604 | int error = 0; | |
2605 | struct inode *target; | |
2606 | ||
2607 | /* | |
2608 | * If we are going to change the parent - check write permissions, | |
2609 | * we'll need to flip '..'. | |
2610 | */ | |
2611 | if (new_dir != old_dir) { | |
f419a2e3 | 2612 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
2613 | if (error) |
2614 | return error; | |
2615 | } | |
2616 | ||
2617 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2618 | if (error) | |
2619 | return error; | |
2620 | ||
2621 | target = new_dentry->d_inode; | |
2622 | if (target) { | |
1b1dcc1b | 2623 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2624 | dentry_unhash(new_dentry); |
2625 | } | |
2626 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2627 | error = -EBUSY; | |
2628 | else | |
2629 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2630 | if (target) { | |
2631 | if (!error) | |
2632 | target->i_flags |= S_DEAD; | |
1b1dcc1b | 2633 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2634 | if (d_unhashed(new_dentry)) |
2635 | d_rehash(new_dentry); | |
2636 | dput(new_dentry); | |
2637 | } | |
e31e14ec | 2638 | if (!error) |
349457cc MF |
2639 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2640 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
2641 | return error; |
2642 | } | |
2643 | ||
75c96f85 AB |
2644 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2645 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2646 | { |
2647 | struct inode *target; | |
2648 | int error; | |
2649 | ||
2650 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2651 | if (error) | |
2652 | return error; | |
2653 | ||
2654 | dget(new_dentry); | |
2655 | target = new_dentry->d_inode; | |
2656 | if (target) | |
1b1dcc1b | 2657 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2658 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2659 | error = -EBUSY; | |
2660 | else | |
2661 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2662 | if (!error) { | |
bec1052e AV |
2663 | if (target) |
2664 | target->i_flags |= S_DEAD; | |
349457cc | 2665 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
1da177e4 | 2666 | d_move(old_dentry, new_dentry); |
1da177e4 LT |
2667 | } |
2668 | if (target) | |
1b1dcc1b | 2669 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2670 | dput(new_dentry); |
2671 | return error; | |
2672 | } | |
2673 | ||
2674 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2675 | struct inode *new_dir, struct dentry *new_dentry) | |
2676 | { | |
2677 | int error; | |
2678 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2679 | const char *old_name; |
1da177e4 LT |
2680 | |
2681 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2682 | return 0; | |
2683 | ||
2684 | error = may_delete(old_dir, old_dentry, is_dir); | |
2685 | if (error) | |
2686 | return error; | |
2687 | ||
2688 | if (!new_dentry->d_inode) | |
a95164d9 | 2689 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
2690 | else |
2691 | error = may_delete(new_dir, new_dentry, is_dir); | |
2692 | if (error) | |
2693 | return error; | |
2694 | ||
acfa4380 | 2695 | if (!old_dir->i_op->rename) |
1da177e4 LT |
2696 | return -EPERM; |
2697 | ||
9e3509e2 JK |
2698 | vfs_dq_init(old_dir); |
2699 | vfs_dq_init(new_dir); | |
1da177e4 | 2700 | |
0eeca283 RL |
2701 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2702 | ||
1da177e4 LT |
2703 | if (is_dir) |
2704 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2705 | else | |
2706 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
2707 | if (!error) |
2708 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 2709 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
2710 | fsnotify_oldname_free(old_name); |
2711 | ||
1da177e4 LT |
2712 | return error; |
2713 | } | |
2714 | ||
2e4d0924 HC |
2715 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
2716 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2717 | { |
2ad94ae6 AV |
2718 | struct dentry *old_dir, *new_dir; |
2719 | struct dentry *old_dentry, *new_dentry; | |
2720 | struct dentry *trap; | |
1da177e4 | 2721 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
2722 | char *from; |
2723 | char *to; | |
2724 | int error; | |
1da177e4 | 2725 | |
2ad94ae6 | 2726 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
2727 | if (error) |
2728 | goto exit; | |
2729 | ||
2ad94ae6 | 2730 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
2731 | if (error) |
2732 | goto exit1; | |
2733 | ||
2734 | error = -EXDEV; | |
4ac91378 | 2735 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
2736 | goto exit2; |
2737 | ||
4ac91378 | 2738 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
2739 | error = -EBUSY; |
2740 | if (oldnd.last_type != LAST_NORM) | |
2741 | goto exit2; | |
2742 | ||
4ac91378 | 2743 | new_dir = newnd.path.dentry; |
1da177e4 LT |
2744 | if (newnd.last_type != LAST_NORM) |
2745 | goto exit2; | |
2746 | ||
0612d9fb OH |
2747 | oldnd.flags &= ~LOOKUP_PARENT; |
2748 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 2749 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 2750 | |
1da177e4 LT |
2751 | trap = lock_rename(new_dir, old_dir); |
2752 | ||
49705b77 | 2753 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
2754 | error = PTR_ERR(old_dentry); |
2755 | if (IS_ERR(old_dentry)) | |
2756 | goto exit3; | |
2757 | /* source must exist */ | |
2758 | error = -ENOENT; | |
2759 | if (!old_dentry->d_inode) | |
2760 | goto exit4; | |
2761 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2762 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2763 | error = -ENOTDIR; | |
2764 | if (oldnd.last.name[oldnd.last.len]) | |
2765 | goto exit4; | |
2766 | if (newnd.last.name[newnd.last.len]) | |
2767 | goto exit4; | |
2768 | } | |
2769 | /* source should not be ancestor of target */ | |
2770 | error = -EINVAL; | |
2771 | if (old_dentry == trap) | |
2772 | goto exit4; | |
49705b77 | 2773 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
2774 | error = PTR_ERR(new_dentry); |
2775 | if (IS_ERR(new_dentry)) | |
2776 | goto exit4; | |
2777 | /* target should not be an ancestor of source */ | |
2778 | error = -ENOTEMPTY; | |
2779 | if (new_dentry == trap) | |
2780 | goto exit5; | |
2781 | ||
9079b1eb DH |
2782 | error = mnt_want_write(oldnd.path.mnt); |
2783 | if (error) | |
2784 | goto exit5; | |
be6d3e56 KT |
2785 | error = security_path_rename(&oldnd.path, old_dentry, |
2786 | &newnd.path, new_dentry); | |
2787 | if (error) | |
2788 | goto exit6; | |
1da177e4 LT |
2789 | error = vfs_rename(old_dir->d_inode, old_dentry, |
2790 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 2791 | exit6: |
9079b1eb | 2792 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
2793 | exit5: |
2794 | dput(new_dentry); | |
2795 | exit4: | |
2796 | dput(old_dentry); | |
2797 | exit3: | |
2798 | unlock_rename(new_dir, old_dir); | |
2799 | exit2: | |
1d957f9b | 2800 | path_put(&newnd.path); |
2ad94ae6 | 2801 | putname(to); |
1da177e4 | 2802 | exit1: |
1d957f9b | 2803 | path_put(&oldnd.path); |
1da177e4 | 2804 | putname(from); |
2ad94ae6 | 2805 | exit: |
1da177e4 LT |
2806 | return error; |
2807 | } | |
2808 | ||
a26eab24 | 2809 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2810 | { |
2811 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
2812 | } | |
2813 | ||
1da177e4 LT |
2814 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2815 | { | |
2816 | int len; | |
2817 | ||
2818 | len = PTR_ERR(link); | |
2819 | if (IS_ERR(link)) | |
2820 | goto out; | |
2821 | ||
2822 | len = strlen(link); | |
2823 | if (len > (unsigned) buflen) | |
2824 | len = buflen; | |
2825 | if (copy_to_user(buffer, link, len)) | |
2826 | len = -EFAULT; | |
2827 | out: | |
2828 | return len; | |
2829 | } | |
2830 | ||
2831 | /* | |
2832 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2833 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2834 | * using) it for any given inode is up to filesystem. | |
2835 | */ | |
2836 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2837 | { | |
2838 | struct nameidata nd; | |
cc314eef | 2839 | void *cookie; |
694a1764 | 2840 | int res; |
cc314eef | 2841 | |
1da177e4 | 2842 | nd.depth = 0; |
cc314eef | 2843 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
2844 | if (IS_ERR(cookie)) |
2845 | return PTR_ERR(cookie); | |
2846 | ||
2847 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
2848 | if (dentry->d_inode->i_op->put_link) | |
2849 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
2850 | return res; | |
1da177e4 LT |
2851 | } |
2852 | ||
2853 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2854 | { | |
2855 | return __vfs_follow_link(nd, link); | |
2856 | } | |
2857 | ||
2858 | /* get the link contents into pagecache */ | |
2859 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2860 | { | |
ebd09abb DG |
2861 | char *kaddr; |
2862 | struct page *page; | |
1da177e4 | 2863 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 2864 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 2865 | if (IS_ERR(page)) |
6fe6900e | 2866 | return (char*)page; |
1da177e4 | 2867 | *ppage = page; |
ebd09abb DG |
2868 | kaddr = kmap(page); |
2869 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
2870 | return kaddr; | |
1da177e4 LT |
2871 | } |
2872 | ||
2873 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2874 | { | |
2875 | struct page *page = NULL; | |
2876 | char *s = page_getlink(dentry, &page); | |
2877 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2878 | if (page) { | |
2879 | kunmap(page); | |
2880 | page_cache_release(page); | |
2881 | } | |
2882 | return res; | |
2883 | } | |
2884 | ||
cc314eef | 2885 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2886 | { |
cc314eef | 2887 | struct page *page = NULL; |
1da177e4 | 2888 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2889 | return page; |
1da177e4 LT |
2890 | } |
2891 | ||
cc314eef | 2892 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2893 | { |
cc314eef LT |
2894 | struct page *page = cookie; |
2895 | ||
2896 | if (page) { | |
1da177e4 LT |
2897 | kunmap(page); |
2898 | page_cache_release(page); | |
1da177e4 LT |
2899 | } |
2900 | } | |
2901 | ||
54566b2c NP |
2902 | /* |
2903 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
2904 | */ | |
2905 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
2906 | { |
2907 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 2908 | struct page *page; |
afddba49 | 2909 | void *fsdata; |
beb497ab | 2910 | int err; |
1da177e4 | 2911 | char *kaddr; |
54566b2c NP |
2912 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
2913 | if (nofs) | |
2914 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 2915 | |
7e53cac4 | 2916 | retry: |
afddba49 | 2917 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 2918 | flags, &page, &fsdata); |
1da177e4 | 2919 | if (err) |
afddba49 NP |
2920 | goto fail; |
2921 | ||
1da177e4 LT |
2922 | kaddr = kmap_atomic(page, KM_USER0); |
2923 | memcpy(kaddr, symname, len-1); | |
2924 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
2925 | |
2926 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
2927 | page, fsdata); | |
1da177e4 LT |
2928 | if (err < 0) |
2929 | goto fail; | |
afddba49 NP |
2930 | if (err < len-1) |
2931 | goto retry; | |
2932 | ||
1da177e4 LT |
2933 | mark_inode_dirty(inode); |
2934 | return 0; | |
1da177e4 LT |
2935 | fail: |
2936 | return err; | |
2937 | } | |
2938 | ||
0adb25d2 KK |
2939 | int page_symlink(struct inode *inode, const char *symname, int len) |
2940 | { | |
2941 | return __page_symlink(inode, symname, len, | |
54566b2c | 2942 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
2943 | } |
2944 | ||
92e1d5be | 2945 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
2946 | .readlink = generic_readlink, |
2947 | .follow_link = page_follow_link_light, | |
2948 | .put_link = page_put_link, | |
2949 | }; | |
2950 | ||
2d8f3038 | 2951 | EXPORT_SYMBOL(user_path_at); |
1da177e4 LT |
2952 | EXPORT_SYMBOL(follow_down); |
2953 | EXPORT_SYMBOL(follow_up); | |
2954 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2955 | EXPORT_SYMBOL(getname); | |
2956 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
2957 | EXPORT_SYMBOL(lookup_one_len); |
2958 | EXPORT_SYMBOL(page_follow_link_light); | |
2959 | EXPORT_SYMBOL(page_put_link); | |
2960 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 2961 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
2962 | EXPORT_SYMBOL(page_symlink); |
2963 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
2964 | EXPORT_SYMBOL(path_lookup); | |
d1811465 | 2965 | EXPORT_SYMBOL(kern_path); |
16f18200 | 2966 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 2967 | EXPORT_SYMBOL(inode_permission); |
8c744fb8 | 2968 | EXPORT_SYMBOL(file_permission); |
1da177e4 LT |
2969 | EXPORT_SYMBOL(unlock_rename); |
2970 | EXPORT_SYMBOL(vfs_create); | |
2971 | EXPORT_SYMBOL(vfs_follow_link); | |
2972 | EXPORT_SYMBOL(vfs_link); | |
2973 | EXPORT_SYMBOL(vfs_mkdir); | |
2974 | EXPORT_SYMBOL(vfs_mknod); | |
2975 | EXPORT_SYMBOL(generic_permission); | |
2976 | EXPORT_SYMBOL(vfs_readlink); | |
2977 | EXPORT_SYMBOL(vfs_rename); | |
2978 | EXPORT_SYMBOL(vfs_rmdir); | |
2979 | EXPORT_SYMBOL(vfs_symlink); | |
2980 | EXPORT_SYMBOL(vfs_unlink); | |
2981 | EXPORT_SYMBOL(dentry_unhash); | |
2982 | EXPORT_SYMBOL(generic_readlink); |