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 | */ | |
235 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) | |
236 | if (capable(CAP_DAC_READ_SEARCH)) | |
237 | return 0; | |
238 | ||
239 | return -EACCES; | |
240 | } | |
241 | ||
cb23beb5 CH |
242 | /** |
243 | * inode_permission - check for access rights to a given inode | |
244 | * @inode: inode to check permission on | |
245 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
246 | * | |
247 | * Used to check for read/write/execute permissions on an inode. | |
248 | * We use "fsuid" for this, letting us set arbitrary permissions | |
249 | * for filesystem access without changing the "normal" uids which | |
250 | * are used for other things. | |
251 | */ | |
f419a2e3 | 252 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 253 | { |
e6305c43 | 254 | int retval; |
1da177e4 LT |
255 | |
256 | if (mask & MAY_WRITE) { | |
22590e41 | 257 | umode_t mode = inode->i_mode; |
1da177e4 LT |
258 | |
259 | /* | |
260 | * Nobody gets write access to a read-only fs. | |
261 | */ | |
262 | if (IS_RDONLY(inode) && | |
263 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
264 | return -EROFS; | |
265 | ||
266 | /* | |
267 | * Nobody gets write access to an immutable file. | |
268 | */ | |
269 | if (IS_IMMUTABLE(inode)) | |
270 | return -EACCES; | |
271 | } | |
272 | ||
acfa4380 | 273 | if (inode->i_op->permission) |
b77b0646 | 274 | retval = inode->i_op->permission(inode, mask); |
f696a365 | 275 | else |
5909ccaa | 276 | retval = generic_permission(inode, mask, inode->i_op->check_acl); |
f696a365 | 277 | |
1da177e4 LT |
278 | if (retval) |
279 | return retval; | |
280 | ||
08ce5f16 SH |
281 | retval = devcgroup_inode_permission(inode, mask); |
282 | if (retval) | |
283 | return retval; | |
284 | ||
e6305c43 | 285 | return security_inode_permission(inode, |
f418b006 | 286 | mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); |
1da177e4 LT |
287 | } |
288 | ||
8c744fb8 CH |
289 | /** |
290 | * file_permission - check for additional access rights to a given file | |
291 | * @file: file to check access rights for | |
292 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
293 | * | |
294 | * Used to check for read/write/execute permissions on an already opened | |
295 | * file. | |
296 | * | |
297 | * Note: | |
298 | * Do not use this function in new code. All access checks should | |
cb23beb5 | 299 | * be done using inode_permission(). |
8c744fb8 CH |
300 | */ |
301 | int file_permission(struct file *file, int mask) | |
302 | { | |
f419a2e3 | 303 | return inode_permission(file->f_path.dentry->d_inode, mask); |
8c744fb8 CH |
304 | } |
305 | ||
1da177e4 LT |
306 | /* |
307 | * get_write_access() gets write permission for a file. | |
308 | * put_write_access() releases this write permission. | |
309 | * This is used for regular files. | |
310 | * We cannot support write (and maybe mmap read-write shared) accesses and | |
311 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode | |
312 | * can have the following values: | |
313 | * 0: no writers, no VM_DENYWRITE mappings | |
314 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist | |
315 | * > 0: (i_writecount) users are writing to the file. | |
316 | * | |
317 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe | |
318 | * except for the cases where we don't hold i_writecount yet. Then we need to | |
319 | * use {get,deny}_write_access() - these functions check the sign and refuse | |
320 | * to do the change if sign is wrong. Exclusion between them is provided by | |
321 | * the inode->i_lock spinlock. | |
322 | */ | |
323 | ||
324 | int get_write_access(struct inode * inode) | |
325 | { | |
326 | spin_lock(&inode->i_lock); | |
327 | if (atomic_read(&inode->i_writecount) < 0) { | |
328 | spin_unlock(&inode->i_lock); | |
329 | return -ETXTBSY; | |
330 | } | |
331 | atomic_inc(&inode->i_writecount); | |
332 | spin_unlock(&inode->i_lock); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | ||
337 | int deny_write_access(struct file * file) | |
338 | { | |
0f7fc9e4 | 339 | struct inode *inode = file->f_path.dentry->d_inode; |
1da177e4 LT |
340 | |
341 | spin_lock(&inode->i_lock); | |
342 | if (atomic_read(&inode->i_writecount) > 0) { | |
343 | spin_unlock(&inode->i_lock); | |
344 | return -ETXTBSY; | |
345 | } | |
346 | atomic_dec(&inode->i_writecount); | |
347 | spin_unlock(&inode->i_lock); | |
348 | ||
349 | return 0; | |
350 | } | |
351 | ||
5dd784d0 JB |
352 | /** |
353 | * path_get - get a reference to a path | |
354 | * @path: path to get the reference to | |
355 | * | |
356 | * Given a path increment the reference count to the dentry and the vfsmount. | |
357 | */ | |
358 | void path_get(struct path *path) | |
359 | { | |
360 | mntget(path->mnt); | |
361 | dget(path->dentry); | |
362 | } | |
363 | EXPORT_SYMBOL(path_get); | |
364 | ||
1d957f9b JB |
365 | /** |
366 | * path_put - put a reference to a path | |
367 | * @path: path to put the reference to | |
368 | * | |
369 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
370 | */ | |
371 | void path_put(struct path *path) | |
1da177e4 | 372 | { |
1d957f9b JB |
373 | dput(path->dentry); |
374 | mntput(path->mnt); | |
1da177e4 | 375 | } |
1d957f9b | 376 | EXPORT_SYMBOL(path_put); |
1da177e4 | 377 | |
834f2a4a TM |
378 | /** |
379 | * release_open_intent - free up open intent resources | |
380 | * @nd: pointer to nameidata | |
381 | */ | |
382 | void release_open_intent(struct nameidata *nd) | |
383 | { | |
0f7fc9e4 | 384 | if (nd->intent.open.file->f_path.dentry == NULL) |
834f2a4a TM |
385 | put_filp(nd->intent.open.file); |
386 | else | |
387 | fput(nd->intent.open.file); | |
388 | } | |
389 | ||
bcdc5e01 IK |
390 | static inline struct dentry * |
391 | do_revalidate(struct dentry *dentry, struct nameidata *nd) | |
392 | { | |
393 | int status = dentry->d_op->d_revalidate(dentry, nd); | |
394 | if (unlikely(status <= 0)) { | |
395 | /* | |
396 | * The dentry failed validation. | |
397 | * If d_revalidate returned 0 attempt to invalidate | |
398 | * the dentry otherwise d_revalidate is asking us | |
399 | * to return a fail status. | |
400 | */ | |
401 | if (!status) { | |
402 | if (!d_invalidate(dentry)) { | |
403 | dput(dentry); | |
404 | dentry = NULL; | |
405 | } | |
406 | } else { | |
407 | dput(dentry); | |
408 | dentry = ERR_PTR(status); | |
409 | } | |
410 | } | |
411 | return dentry; | |
412 | } | |
413 | ||
39159de2 JL |
414 | /* |
415 | * force_reval_path - force revalidation of a dentry | |
416 | * | |
417 | * In some situations the path walking code will trust dentries without | |
418 | * revalidating them. This causes problems for filesystems that depend on | |
419 | * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set | |
420 | * (which indicates that it's possible for the dentry to go stale), force | |
421 | * a d_revalidate call before proceeding. | |
422 | * | |
423 | * Returns 0 if the revalidation was successful. If the revalidation fails, | |
424 | * either return the error returned by d_revalidate or -ESTALE if the | |
425 | * revalidation it just returned 0. If d_revalidate returns 0, we attempt to | |
426 | * invalidate the dentry. It's up to the caller to handle putting references | |
427 | * to the path if necessary. | |
428 | */ | |
429 | static int | |
430 | force_reval_path(struct path *path, struct nameidata *nd) | |
431 | { | |
432 | int status; | |
433 | struct dentry *dentry = path->dentry; | |
434 | ||
435 | /* | |
436 | * only check on filesystems where it's possible for the dentry to | |
437 | * become stale. It's assumed that if this flag is set then the | |
438 | * d_revalidate op will also be defined. | |
439 | */ | |
440 | if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) | |
441 | return 0; | |
442 | ||
443 | status = dentry->d_op->d_revalidate(dentry, nd); | |
444 | if (status > 0) | |
445 | return 0; | |
446 | ||
447 | if (!status) { | |
448 | d_invalidate(dentry); | |
449 | status = -ESTALE; | |
450 | } | |
451 | return status; | |
452 | } | |
453 | ||
1da177e4 | 454 | /* |
b75b5086 AV |
455 | * Short-cut version of permission(), for calling on directories |
456 | * during pathname resolution. Combines parts of permission() | |
457 | * and generic_permission(), and tests ONLY for MAY_EXEC permission. | |
1da177e4 LT |
458 | * |
459 | * If appropriate, check DAC only. If not appropriate, or | |
b75b5086 | 460 | * short-cut DAC fails, then call ->permission() to do more |
1da177e4 LT |
461 | * complete permission check. |
462 | */ | |
b75b5086 | 463 | static int exec_permission(struct inode *inode) |
1da177e4 | 464 | { |
5909ccaa | 465 | int ret; |
1da177e4 | 466 | |
cb9179ea | 467 | if (inode->i_op->permission) { |
5909ccaa | 468 | ret = inode->i_op->permission(inode, MAY_EXEC); |
cb9179ea LT |
469 | if (!ret) |
470 | goto ok; | |
471 | return ret; | |
472 | } | |
5909ccaa LT |
473 | ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); |
474 | if (!ret) | |
1da177e4 LT |
475 | goto ok; |
476 | ||
f1ac9f6b | 477 | if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
478 | goto ok; |
479 | ||
5909ccaa | 480 | return ret; |
1da177e4 | 481 | ok: |
b77b0646 | 482 | return security_inode_permission(inode, MAY_EXEC); |
1da177e4 LT |
483 | } |
484 | ||
2a737871 AV |
485 | static __always_inline void set_root(struct nameidata *nd) |
486 | { | |
487 | if (!nd->root.mnt) { | |
488 | struct fs_struct *fs = current->fs; | |
489 | read_lock(&fs->lock); | |
490 | nd->root = fs->root; | |
491 | path_get(&nd->root); | |
492 | read_unlock(&fs->lock); | |
493 | } | |
494 | } | |
495 | ||
6de88d72 AV |
496 | static int link_path_walk(const char *, struct nameidata *); |
497 | ||
f1662356 | 498 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 LT |
499 | { |
500 | int res = 0; | |
501 | char *name; | |
502 | if (IS_ERR(link)) | |
503 | goto fail; | |
504 | ||
505 | if (*link == '/') { | |
2a737871 | 506 | set_root(nd); |
1d957f9b | 507 | path_put(&nd->path); |
2a737871 AV |
508 | nd->path = nd->root; |
509 | path_get(&nd->root); | |
1da177e4 | 510 | } |
b4091d5f | 511 | |
1da177e4 | 512 | res = link_path_walk(link, nd); |
1da177e4 LT |
513 | if (nd->depth || res || nd->last_type!=LAST_NORM) |
514 | return res; | |
515 | /* | |
516 | * If it is an iterative symlinks resolution in open_namei() we | |
517 | * have to copy the last component. And all that crap because of | |
518 | * bloody create() on broken symlinks. Furrfu... | |
519 | */ | |
520 | name = __getname(); | |
521 | if (unlikely(!name)) { | |
1d957f9b | 522 | path_put(&nd->path); |
1da177e4 LT |
523 | return -ENOMEM; |
524 | } | |
525 | strcpy(name, nd->last.name); | |
526 | nd->last.name = name; | |
527 | return 0; | |
528 | fail: | |
1d957f9b | 529 | path_put(&nd->path); |
1da177e4 LT |
530 | return PTR_ERR(link); |
531 | } | |
532 | ||
1d957f9b | 533 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
534 | { |
535 | dput(path->dentry); | |
4ac91378 | 536 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
537 | mntput(path->mnt); |
538 | } | |
539 | ||
540 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) | |
541 | { | |
4ac91378 JB |
542 | dput(nd->path.dentry); |
543 | if (nd->path.mnt != path->mnt) | |
544 | mntput(nd->path.mnt); | |
545 | nd->path.mnt = path->mnt; | |
546 | nd->path.dentry = path->dentry; | |
051d3812 IK |
547 | } |
548 | ||
f1662356 | 549 | static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
550 | { |
551 | int error; | |
cc314eef | 552 | void *cookie; |
cd4e91d3 | 553 | struct dentry *dentry = path->dentry; |
1da177e4 | 554 | |
d671a1cb | 555 | touch_atime(path->mnt, dentry); |
1da177e4 | 556 | nd_set_link(nd, NULL); |
cd4e91d3 | 557 | |
4ac91378 | 558 | if (path->mnt != nd->path.mnt) { |
051d3812 IK |
559 | path_to_nameidata(path, nd); |
560 | dget(dentry); | |
561 | } | |
562 | mntget(path->mnt); | |
cc314eef LT |
563 | cookie = dentry->d_inode->i_op->follow_link(dentry, nd); |
564 | error = PTR_ERR(cookie); | |
565 | if (!IS_ERR(cookie)) { | |
1da177e4 | 566 | char *s = nd_get_link(nd); |
cc314eef | 567 | error = 0; |
1da177e4 LT |
568 | if (s) |
569 | error = __vfs_follow_link(nd, s); | |
39159de2 JL |
570 | else if (nd->last_type == LAST_BIND) { |
571 | error = force_reval_path(&nd->path, nd); | |
572 | if (error) | |
573 | path_put(&nd->path); | |
574 | } | |
1da177e4 | 575 | if (dentry->d_inode->i_op->put_link) |
cc314eef | 576 | dentry->d_inode->i_op->put_link(dentry, nd, cookie); |
1da177e4 | 577 | } |
1da177e4 LT |
578 | return error; |
579 | } | |
580 | ||
581 | /* | |
582 | * This limits recursive symlink follows to 8, while | |
583 | * limiting consecutive symlinks to 40. | |
584 | * | |
585 | * Without that kind of total limit, nasty chains of consecutive | |
586 | * symlinks can cause almost arbitrarily long lookups. | |
587 | */ | |
90ebe565 | 588 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
1da177e4 LT |
589 | { |
590 | int err = -ELOOP; | |
591 | if (current->link_count >= MAX_NESTED_LINKS) | |
592 | goto loop; | |
593 | if (current->total_link_count >= 40) | |
594 | goto loop; | |
595 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
596 | cond_resched(); | |
90ebe565 | 597 | err = security_inode_follow_link(path->dentry, nd); |
1da177e4 LT |
598 | if (err) |
599 | goto loop; | |
600 | current->link_count++; | |
601 | current->total_link_count++; | |
602 | nd->depth++; | |
cd4e91d3 | 603 | err = __do_follow_link(path, nd); |
258fa999 | 604 | path_put(path); |
839d9f93 AV |
605 | current->link_count--; |
606 | nd->depth--; | |
1da177e4 LT |
607 | return err; |
608 | loop: | |
1d957f9b JB |
609 | path_put_conditional(path, nd); |
610 | path_put(&nd->path); | |
1da177e4 LT |
611 | return err; |
612 | } | |
613 | ||
bab77ebf | 614 | int follow_up(struct path *path) |
1da177e4 LT |
615 | { |
616 | struct vfsmount *parent; | |
617 | struct dentry *mountpoint; | |
618 | spin_lock(&vfsmount_lock); | |
bab77ebf AV |
619 | parent = path->mnt->mnt_parent; |
620 | if (parent == path->mnt) { | |
1da177e4 LT |
621 | spin_unlock(&vfsmount_lock); |
622 | return 0; | |
623 | } | |
624 | mntget(parent); | |
bab77ebf | 625 | mountpoint = dget(path->mnt->mnt_mountpoint); |
1da177e4 | 626 | spin_unlock(&vfsmount_lock); |
bab77ebf AV |
627 | dput(path->dentry); |
628 | path->dentry = mountpoint; | |
629 | mntput(path->mnt); | |
630 | path->mnt = parent; | |
1da177e4 LT |
631 | return 1; |
632 | } | |
633 | ||
634 | /* no need for dcache_lock, as serialization is taken care in | |
635 | * namespace.c | |
636 | */ | |
463ffb2e AV |
637 | static int __follow_mount(struct path *path) |
638 | { | |
639 | int res = 0; | |
640 | while (d_mountpoint(path->dentry)) { | |
1c755af4 | 641 | struct vfsmount *mounted = lookup_mnt(path); |
463ffb2e AV |
642 | if (!mounted) |
643 | break; | |
644 | dput(path->dentry); | |
645 | if (res) | |
646 | mntput(path->mnt); | |
647 | path->mnt = mounted; | |
648 | path->dentry = dget(mounted->mnt_root); | |
649 | res = 1; | |
650 | } | |
651 | return res; | |
652 | } | |
653 | ||
79ed0226 | 654 | static void follow_mount(struct path *path) |
1da177e4 | 655 | { |
79ed0226 | 656 | while (d_mountpoint(path->dentry)) { |
1c755af4 | 657 | struct vfsmount *mounted = lookup_mnt(path); |
1da177e4 LT |
658 | if (!mounted) |
659 | break; | |
79ed0226 AV |
660 | dput(path->dentry); |
661 | mntput(path->mnt); | |
662 | path->mnt = mounted; | |
663 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 | 664 | } |
1da177e4 LT |
665 | } |
666 | ||
667 | /* no need for dcache_lock, as serialization is taken care in | |
668 | * namespace.c | |
669 | */ | |
9393bd07 | 670 | int follow_down(struct path *path) |
1da177e4 LT |
671 | { |
672 | struct vfsmount *mounted; | |
673 | ||
1c755af4 | 674 | mounted = lookup_mnt(path); |
1da177e4 | 675 | if (mounted) { |
9393bd07 AV |
676 | dput(path->dentry); |
677 | mntput(path->mnt); | |
678 | path->mnt = mounted; | |
679 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
680 | return 1; |
681 | } | |
682 | return 0; | |
683 | } | |
684 | ||
f1662356 | 685 | static __always_inline void follow_dotdot(struct nameidata *nd) |
1da177e4 | 686 | { |
2a737871 | 687 | set_root(nd); |
e518ddb7 | 688 | |
1da177e4 LT |
689 | while(1) { |
690 | struct vfsmount *parent; | |
4ac91378 | 691 | struct dentry *old = nd->path.dentry; |
1da177e4 | 692 | |
2a737871 AV |
693 | if (nd->path.dentry == nd->root.dentry && |
694 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
695 | break; |
696 | } | |
1da177e4 | 697 | spin_lock(&dcache_lock); |
4ac91378 JB |
698 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
699 | nd->path.dentry = dget(nd->path.dentry->d_parent); | |
1da177e4 LT |
700 | spin_unlock(&dcache_lock); |
701 | dput(old); | |
702 | break; | |
703 | } | |
704 | spin_unlock(&dcache_lock); | |
705 | spin_lock(&vfsmount_lock); | |
4ac91378 JB |
706 | parent = nd->path.mnt->mnt_parent; |
707 | if (parent == nd->path.mnt) { | |
1da177e4 LT |
708 | spin_unlock(&vfsmount_lock); |
709 | break; | |
710 | } | |
711 | mntget(parent); | |
4ac91378 | 712 | nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); |
1da177e4 LT |
713 | spin_unlock(&vfsmount_lock); |
714 | dput(old); | |
4ac91378 JB |
715 | mntput(nd->path.mnt); |
716 | nd->path.mnt = parent; | |
1da177e4 | 717 | } |
79ed0226 | 718 | follow_mount(&nd->path); |
1da177e4 LT |
719 | } |
720 | ||
1da177e4 LT |
721 | /* |
722 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
723 | * small and for now I'd prefer to have fast path as straight as possible. | |
724 | * It _is_ time-critical. | |
725 | */ | |
726 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
727 | struct path *path) | |
728 | { | |
4ac91378 | 729 | struct vfsmount *mnt = nd->path.mnt; |
6e6b1bd1 AV |
730 | struct dentry *dentry, *parent; |
731 | struct inode *dir; | |
3cac260a AV |
732 | /* |
733 | * See if the low-level filesystem might want | |
734 | * to use its own hash.. | |
735 | */ | |
736 | if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { | |
737 | int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name); | |
738 | if (err < 0) | |
739 | return err; | |
740 | } | |
1da177e4 | 741 | |
3cac260a | 742 | dentry = __d_lookup(nd->path.dentry, name); |
1da177e4 LT |
743 | if (!dentry) |
744 | goto need_lookup; | |
745 | if (dentry->d_op && dentry->d_op->d_revalidate) | |
746 | goto need_revalidate; | |
747 | done: | |
748 | path->mnt = mnt; | |
749 | path->dentry = dentry; | |
634ee701 | 750 | __follow_mount(path); |
1da177e4 LT |
751 | return 0; |
752 | ||
753 | need_lookup: | |
6e6b1bd1 AV |
754 | parent = nd->path.dentry; |
755 | dir = parent->d_inode; | |
756 | ||
757 | mutex_lock(&dir->i_mutex); | |
758 | /* | |
759 | * First re-do the cached lookup just in case it was created | |
760 | * while we waited for the directory semaphore.. | |
761 | * | |
762 | * FIXME! This could use version numbering or similar to | |
763 | * avoid unnecessary cache lookups. | |
764 | * | |
765 | * The "dcache_lock" is purely to protect the RCU list walker | |
766 | * from concurrent renames at this point (we mustn't get false | |
767 | * negatives from the RCU list walk here, unlike the optimistic | |
768 | * fast walk). | |
769 | * | |
770 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup | |
771 | */ | |
772 | dentry = d_lookup(parent, name); | |
773 | if (!dentry) { | |
774 | struct dentry *new; | |
775 | ||
776 | /* Don't create child dentry for a dead directory. */ | |
777 | dentry = ERR_PTR(-ENOENT); | |
778 | if (IS_DEADDIR(dir)) | |
779 | goto out_unlock; | |
780 | ||
781 | new = d_alloc(parent, name); | |
782 | dentry = ERR_PTR(-ENOMEM); | |
783 | if (new) { | |
784 | dentry = dir->i_op->lookup(dir, new, nd); | |
785 | if (dentry) | |
786 | dput(new); | |
787 | else | |
788 | dentry = new; | |
789 | } | |
790 | out_unlock: | |
791 | mutex_unlock(&dir->i_mutex); | |
792 | if (IS_ERR(dentry)) | |
793 | goto fail; | |
794 | goto done; | |
795 | } | |
796 | ||
797 | /* | |
798 | * Uhhuh! Nasty case: the cache was re-populated while | |
799 | * we waited on the semaphore. Need to revalidate. | |
800 | */ | |
801 | mutex_unlock(&dir->i_mutex); | |
802 | if (dentry->d_op && dentry->d_op->d_revalidate) { | |
803 | dentry = do_revalidate(dentry, nd); | |
804 | if (!dentry) | |
805 | dentry = ERR_PTR(-ENOENT); | |
806 | } | |
1da177e4 LT |
807 | if (IS_ERR(dentry)) |
808 | goto fail; | |
809 | goto done; | |
810 | ||
811 | need_revalidate: | |
bcdc5e01 IK |
812 | dentry = do_revalidate(dentry, nd); |
813 | if (!dentry) | |
814 | goto need_lookup; | |
815 | if (IS_ERR(dentry)) | |
816 | goto fail; | |
817 | goto done; | |
1da177e4 LT |
818 | |
819 | fail: | |
820 | return PTR_ERR(dentry); | |
821 | } | |
822 | ||
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 LT |
942 | inode = next.dentry->d_inode; |
943 | if ((lookup_flags & LOOKUP_FOLLOW) | |
acfa4380 | 944 | && inode && inode->i_op->follow_link) { |
90ebe565 | 945 | err = do_follow_link(&next, nd); |
1da177e4 LT |
946 | if (err) |
947 | goto return_err; | |
4ac91378 | 948 | inode = nd->path.dentry->d_inode; |
09dd17d3 MS |
949 | } else |
950 | path_to_nameidata(&next, nd); | |
1da177e4 LT |
951 | err = -ENOENT; |
952 | if (!inode) | |
953 | break; | |
954 | if (lookup_flags & LOOKUP_DIRECTORY) { | |
955 | err = -ENOTDIR; | |
acfa4380 | 956 | if (!inode->i_op->lookup) |
1da177e4 LT |
957 | break; |
958 | } | |
959 | goto return_base; | |
960 | lookup_parent: | |
961 | nd->last = this; | |
962 | nd->last_type = LAST_NORM; | |
963 | if (this.name[0] != '.') | |
964 | goto return_base; | |
965 | if (this.len == 1) | |
966 | nd->last_type = LAST_DOT; | |
967 | else if (this.len == 2 && this.name[1] == '.') | |
968 | nd->last_type = LAST_DOTDOT; | |
969 | else | |
970 | goto return_base; | |
971 | return_reval: | |
972 | /* | |
973 | * We bypassed the ordinary revalidation routines. | |
974 | * We may need to check the cached dentry for staleness. | |
975 | */ | |
4ac91378 JB |
976 | if (nd->path.dentry && nd->path.dentry->d_sb && |
977 | (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { | |
1da177e4 LT |
978 | err = -ESTALE; |
979 | /* Note: we do not d_invalidate() */ | |
4ac91378 JB |
980 | if (!nd->path.dentry->d_op->d_revalidate( |
981 | nd->path.dentry, nd)) | |
1da177e4 LT |
982 | break; |
983 | } | |
984 | return_base: | |
985 | return 0; | |
986 | out_dput: | |
1d957f9b | 987 | path_put_conditional(&next, nd); |
1da177e4 LT |
988 | break; |
989 | } | |
1d957f9b | 990 | path_put(&nd->path); |
1da177e4 LT |
991 | return_err: |
992 | return err; | |
993 | } | |
994 | ||
fc9b52cd | 995 | static int path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 996 | { |
6de88d72 AV |
997 | struct path save = nd->path; |
998 | int result; | |
999 | ||
1da177e4 | 1000 | current->total_link_count = 0; |
6de88d72 AV |
1001 | |
1002 | /* make sure the stuff we saved doesn't go away */ | |
1003 | path_get(&save); | |
1004 | ||
1005 | result = link_path_walk(name, nd); | |
1006 | if (result == -ESTALE) { | |
1007 | /* nd->path had been dropped */ | |
1008 | current->total_link_count = 0; | |
1009 | nd->path = save; | |
1010 | path_get(&nd->path); | |
1011 | nd->flags |= LOOKUP_REVAL; | |
1012 | result = link_path_walk(name, nd); | |
1013 | } | |
1014 | ||
1015 | path_put(&save); | |
1016 | ||
1017 | return result; | |
1da177e4 LT |
1018 | } |
1019 | ||
9b4a9b14 | 1020 | static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) |
1da177e4 | 1021 | { |
ea3834d9 | 1022 | int retval = 0; |
170aa3d0 UD |
1023 | int fput_needed; |
1024 | struct file *file; | |
1da177e4 LT |
1025 | |
1026 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
1027 | nd->flags = flags; | |
1028 | nd->depth = 0; | |
2a737871 | 1029 | nd->root.mnt = NULL; |
1da177e4 | 1030 | |
1da177e4 | 1031 | if (*name=='/') { |
2a737871 AV |
1032 | set_root(nd); |
1033 | nd->path = nd->root; | |
1034 | path_get(&nd->root); | |
5590ff0d | 1035 | } else if (dfd == AT_FDCWD) { |
2a737871 | 1036 | struct fs_struct *fs = current->fs; |
e518ddb7 | 1037 | read_lock(&fs->lock); |
6ac08c39 JB |
1038 | nd->path = fs->pwd; |
1039 | path_get(&fs->pwd); | |
e518ddb7 | 1040 | read_unlock(&fs->lock); |
5590ff0d | 1041 | } else { |
5590ff0d UD |
1042 | struct dentry *dentry; |
1043 | ||
1044 | file = fget_light(dfd, &fput_needed); | |
170aa3d0 UD |
1045 | retval = -EBADF; |
1046 | if (!file) | |
6d09bb62 | 1047 | goto out_fail; |
5590ff0d | 1048 | |
0f7fc9e4 | 1049 | dentry = file->f_path.dentry; |
5590ff0d | 1050 | |
170aa3d0 UD |
1051 | retval = -ENOTDIR; |
1052 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
6d09bb62 | 1053 | goto fput_fail; |
5590ff0d UD |
1054 | |
1055 | retval = file_permission(file, MAY_EXEC); | |
170aa3d0 | 1056 | if (retval) |
6d09bb62 | 1057 | goto fput_fail; |
5590ff0d | 1058 | |
5dd784d0 JB |
1059 | nd->path = file->f_path; |
1060 | path_get(&file->f_path); | |
5590ff0d UD |
1061 | |
1062 | fput_light(file, fput_needed); | |
1da177e4 | 1063 | } |
9b4a9b14 | 1064 | return 0; |
2dfdd266 | 1065 | |
9b4a9b14 AV |
1066 | fput_fail: |
1067 | fput_light(file, fput_needed); | |
1068 | out_fail: | |
1069 | return retval; | |
1070 | } | |
1071 | ||
1072 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ | |
1073 | static int do_path_lookup(int dfd, const char *name, | |
1074 | unsigned int flags, struct nameidata *nd) | |
1075 | { | |
1076 | int retval = path_init(dfd, name, flags, nd); | |
1077 | if (!retval) | |
1078 | retval = path_walk(name, nd); | |
4ac91378 JB |
1079 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1080 | nd->path.dentry->d_inode)) | |
1081 | audit_inode(name, nd->path.dentry); | |
2a737871 AV |
1082 | if (nd->root.mnt) { |
1083 | path_put(&nd->root); | |
1084 | nd->root.mnt = NULL; | |
1085 | } | |
170aa3d0 | 1086 | return retval; |
1da177e4 LT |
1087 | } |
1088 | ||
fc9b52cd | 1089 | int path_lookup(const char *name, unsigned int flags, |
5590ff0d UD |
1090 | struct nameidata *nd) |
1091 | { | |
1092 | return do_path_lookup(AT_FDCWD, name, flags, nd); | |
1093 | } | |
1094 | ||
d1811465 AV |
1095 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1096 | { | |
1097 | struct nameidata nd; | |
1098 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1099 | if (!res) | |
1100 | *path = nd.path; | |
1101 | return res; | |
1102 | } | |
1103 | ||
16f18200 JJS |
1104 | /** |
1105 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1106 | * @dentry: pointer to dentry of the base directory | |
1107 | * @mnt: pointer to vfs mount of the base directory | |
1108 | * @name: pointer to file name | |
1109 | * @flags: lookup flags | |
1110 | * @nd: pointer to nameidata | |
1111 | */ | |
1112 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1113 | const char *name, unsigned int flags, | |
1114 | struct nameidata *nd) | |
1115 | { | |
1116 | int retval; | |
1117 | ||
1118 | /* same as do_path_lookup */ | |
1119 | nd->last_type = LAST_ROOT; | |
1120 | nd->flags = flags; | |
1121 | nd->depth = 0; | |
1122 | ||
c8e7f449 JB |
1123 | nd->path.dentry = dentry; |
1124 | nd->path.mnt = mnt; | |
1125 | path_get(&nd->path); | |
5b857119 AV |
1126 | nd->root = nd->path; |
1127 | path_get(&nd->root); | |
16f18200 JJS |
1128 | |
1129 | retval = path_walk(name, nd); | |
4ac91378 JB |
1130 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1131 | nd->path.dentry->d_inode)) | |
1132 | audit_inode(name, nd->path.dentry); | |
16f18200 | 1133 | |
5b857119 AV |
1134 | path_put(&nd->root); |
1135 | nd->root.mnt = NULL; | |
16f18200 | 1136 | |
2a737871 | 1137 | return retval; |
16f18200 JJS |
1138 | } |
1139 | ||
eead1911 CH |
1140 | static struct dentry *__lookup_hash(struct qstr *name, |
1141 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1142 | { |
057f6c01 | 1143 | struct dentry *dentry; |
1da177e4 LT |
1144 | struct inode *inode; |
1145 | int err; | |
1146 | ||
1147 | inode = base->d_inode; | |
1da177e4 LT |
1148 | |
1149 | /* | |
1150 | * See if the low-level filesystem might want | |
1151 | * to use its own hash.. | |
1152 | */ | |
1153 | if (base->d_op && base->d_op->d_hash) { | |
1154 | err = base->d_op->d_hash(base, name); | |
1155 | dentry = ERR_PTR(err); | |
1156 | if (err < 0) | |
1157 | goto out; | |
1158 | } | |
1159 | ||
6e6b1bd1 AV |
1160 | dentry = __d_lookup(base, name); |
1161 | ||
1162 | /* lockess __d_lookup may fail due to concurrent d_move() | |
1163 | * in some unrelated directory, so try with d_lookup | |
1164 | */ | |
1165 | if (!dentry) | |
1166 | dentry = d_lookup(base, name); | |
1167 | ||
1168 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) | |
1169 | dentry = do_revalidate(dentry, nd); | |
1170 | ||
1da177e4 | 1171 | if (!dentry) { |
d70b67c8 MS |
1172 | struct dentry *new; |
1173 | ||
1174 | /* Don't create child dentry for a dead directory. */ | |
1175 | dentry = ERR_PTR(-ENOENT); | |
1176 | if (IS_DEADDIR(inode)) | |
1177 | goto out; | |
1178 | ||
1179 | new = d_alloc(base, name); | |
1da177e4 LT |
1180 | dentry = ERR_PTR(-ENOMEM); |
1181 | if (!new) | |
1182 | goto out; | |
1183 | dentry = inode->i_op->lookup(inode, new, nd); | |
1184 | if (!dentry) | |
1185 | dentry = new; | |
1186 | else | |
1187 | dput(new); | |
1188 | } | |
1189 | out: | |
1190 | return dentry; | |
1191 | } | |
1192 | ||
057f6c01 JM |
1193 | /* |
1194 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1195 | * needs parent already locked. Doesn't follow mounts. | |
1196 | * SMP-safe. | |
1197 | */ | |
eead1911 | 1198 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1199 | { |
057f6c01 JM |
1200 | int err; |
1201 | ||
b75b5086 | 1202 | err = exec_permission(nd->path.dentry->d_inode); |
057f6c01 | 1203 | if (err) |
eead1911 | 1204 | return ERR_PTR(err); |
4ac91378 | 1205 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1206 | } |
1207 | ||
eead1911 CH |
1208 | static int __lookup_one_len(const char *name, struct qstr *this, |
1209 | struct dentry *base, int len) | |
1da177e4 LT |
1210 | { |
1211 | unsigned long hash; | |
1da177e4 LT |
1212 | unsigned int c; |
1213 | ||
057f6c01 JM |
1214 | this->name = name; |
1215 | this->len = len; | |
1da177e4 | 1216 | if (!len) |
057f6c01 | 1217 | return -EACCES; |
1da177e4 LT |
1218 | |
1219 | hash = init_name_hash(); | |
1220 | while (len--) { | |
1221 | c = *(const unsigned char *)name++; | |
1222 | if (c == '/' || c == '\0') | |
057f6c01 | 1223 | return -EACCES; |
1da177e4 LT |
1224 | hash = partial_name_hash(c, hash); |
1225 | } | |
057f6c01 JM |
1226 | this->hash = end_name_hash(hash); |
1227 | return 0; | |
1228 | } | |
1da177e4 | 1229 | |
eead1911 | 1230 | /** |
a6b91919 | 1231 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1232 | * @name: pathname component to lookup |
1233 | * @base: base directory to lookup from | |
1234 | * @len: maximum length @len should be interpreted to | |
1235 | * | |
a6b91919 RD |
1236 | * Note that this routine is purely a helper for filesystem usage and should |
1237 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1238 | * nameidata argument is passed to the filesystem methods and a filesystem |
1239 | * using this helper needs to be prepared for that. | |
1240 | */ | |
057f6c01 JM |
1241 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1242 | { | |
1243 | int err; | |
1244 | struct qstr this; | |
1245 | ||
2f9092e1 DW |
1246 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1247 | ||
057f6c01 | 1248 | err = __lookup_one_len(name, &this, base, len); |
eead1911 CH |
1249 | if (err) |
1250 | return ERR_PTR(err); | |
1251 | ||
b75b5086 | 1252 | err = exec_permission(base->d_inode); |
057f6c01 JM |
1253 | if (err) |
1254 | return ERR_PTR(err); | |
49705b77 | 1255 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1256 | } |
1257 | ||
2d8f3038 AV |
1258 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1259 | struct path *path) | |
1da177e4 | 1260 | { |
2d8f3038 | 1261 | struct nameidata nd; |
1da177e4 LT |
1262 | char *tmp = getname(name); |
1263 | int err = PTR_ERR(tmp); | |
1da177e4 | 1264 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1265 | |
1266 | BUG_ON(flags & LOOKUP_PARENT); | |
1267 | ||
1268 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1269 | putname(tmp); |
2d8f3038 AV |
1270 | if (!err) |
1271 | *path = nd.path; | |
1da177e4 LT |
1272 | } |
1273 | return err; | |
1274 | } | |
1275 | ||
2ad94ae6 AV |
1276 | static int user_path_parent(int dfd, const char __user *path, |
1277 | struct nameidata *nd, char **name) | |
1278 | { | |
1279 | char *s = getname(path); | |
1280 | int error; | |
1281 | ||
1282 | if (IS_ERR(s)) | |
1283 | return PTR_ERR(s); | |
1284 | ||
1285 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1286 | if (error) | |
1287 | putname(s); | |
1288 | else | |
1289 | *name = s; | |
1290 | ||
1291 | return error; | |
1292 | } | |
1293 | ||
1da177e4 LT |
1294 | /* |
1295 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1296 | * minimal. | |
1297 | */ | |
1298 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1299 | { | |
da9592ed DH |
1300 | uid_t fsuid = current_fsuid(); |
1301 | ||
1da177e4 LT |
1302 | if (!(dir->i_mode & S_ISVTX)) |
1303 | return 0; | |
da9592ed | 1304 | if (inode->i_uid == fsuid) |
1da177e4 | 1305 | return 0; |
da9592ed | 1306 | if (dir->i_uid == fsuid) |
1da177e4 LT |
1307 | return 0; |
1308 | return !capable(CAP_FOWNER); | |
1309 | } | |
1310 | ||
1311 | /* | |
1312 | * Check whether we can remove a link victim from directory dir, check | |
1313 | * whether the type of victim is right. | |
1314 | * 1. We can't do it if dir is read-only (done in permission()) | |
1315 | * 2. We should have write and exec permissions on dir | |
1316 | * 3. We can't remove anything from append-only dir | |
1317 | * 4. We can't do anything with immutable dir (done in permission()) | |
1318 | * 5. If the sticky bit on dir is set we should either | |
1319 | * a. be owner of dir, or | |
1320 | * b. be owner of victim, or | |
1321 | * c. have CAP_FOWNER capability | |
1322 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1323 | * links pointing to it. | |
1324 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1325 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1326 | * 9. We can't remove a root or mountpoint. | |
1327 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1328 | * nfs_async_unlink(). | |
1329 | */ | |
858119e1 | 1330 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1331 | { |
1332 | int error; | |
1333 | ||
1334 | if (!victim->d_inode) | |
1335 | return -ENOENT; | |
1336 | ||
1337 | BUG_ON(victim->d_parent->d_inode != dir); | |
5a190ae6 | 1338 | audit_inode_child(victim->d_name.name, victim, dir); |
1da177e4 | 1339 | |
f419a2e3 | 1340 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1341 | if (error) |
1342 | return error; | |
1343 | if (IS_APPEND(dir)) | |
1344 | return -EPERM; | |
1345 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1346 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1347 | return -EPERM; |
1348 | if (isdir) { | |
1349 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1350 | return -ENOTDIR; | |
1351 | if (IS_ROOT(victim)) | |
1352 | return -EBUSY; | |
1353 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1354 | return -EISDIR; | |
1355 | if (IS_DEADDIR(dir)) | |
1356 | return -ENOENT; | |
1357 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1358 | return -EBUSY; | |
1359 | return 0; | |
1360 | } | |
1361 | ||
1362 | /* Check whether we can create an object with dentry child in directory | |
1363 | * dir. | |
1364 | * 1. We can't do it if child already exists (open has special treatment for | |
1365 | * this case, but since we are inlined it's OK) | |
1366 | * 2. We can't do it if dir is read-only (done in permission()) | |
1367 | * 3. We should have write and exec permissions on dir | |
1368 | * 4. We can't do it if dir is immutable (done in permission()) | |
1369 | */ | |
a95164d9 | 1370 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1371 | { |
1372 | if (child->d_inode) | |
1373 | return -EEXIST; | |
1374 | if (IS_DEADDIR(dir)) | |
1375 | return -ENOENT; | |
f419a2e3 | 1376 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1377 | } |
1378 | ||
1379 | /* | |
1da177e4 LT |
1380 | * O_DIRECTORY translates into forcing a directory lookup. |
1381 | */ | |
1382 | static inline int lookup_flags(unsigned int f) | |
1383 | { | |
1384 | unsigned long retval = LOOKUP_FOLLOW; | |
1385 | ||
1386 | if (f & O_NOFOLLOW) | |
1387 | retval &= ~LOOKUP_FOLLOW; | |
1388 | ||
1da177e4 LT |
1389 | if (f & O_DIRECTORY) |
1390 | retval |= LOOKUP_DIRECTORY; | |
1391 | ||
1392 | return retval; | |
1393 | } | |
1394 | ||
1395 | /* | |
1396 | * p1 and p2 should be directories on the same fs. | |
1397 | */ | |
1398 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1399 | { | |
1400 | struct dentry *p; | |
1401 | ||
1402 | if (p1 == p2) { | |
f2eace23 | 1403 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1404 | return NULL; |
1405 | } | |
1406 | ||
a11f3a05 | 1407 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1408 | |
e2761a11 OH |
1409 | p = d_ancestor(p2, p1); |
1410 | if (p) { | |
1411 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1412 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1413 | return p; | |
1da177e4 LT |
1414 | } |
1415 | ||
e2761a11 OH |
1416 | p = d_ancestor(p1, p2); |
1417 | if (p) { | |
1418 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1419 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1420 | return p; | |
1da177e4 LT |
1421 | } |
1422 | ||
f2eace23 IM |
1423 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1424 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1425 | return NULL; |
1426 | } | |
1427 | ||
1428 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1429 | { | |
1b1dcc1b | 1430 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1431 | if (p1 != p2) { |
1b1dcc1b | 1432 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1433 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1434 | } |
1435 | } | |
1436 | ||
1437 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1438 | struct nameidata *nd) | |
1439 | { | |
a95164d9 | 1440 | int error = may_create(dir, dentry); |
1da177e4 LT |
1441 | |
1442 | if (error) | |
1443 | return error; | |
1444 | ||
acfa4380 | 1445 | if (!dir->i_op->create) |
1da177e4 LT |
1446 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1447 | mode &= S_IALLUGO; | |
1448 | mode |= S_IFREG; | |
1449 | error = security_inode_create(dir, dentry, mode); | |
1450 | if (error) | |
1451 | return error; | |
9e3509e2 | 1452 | vfs_dq_init(dir); |
1da177e4 | 1453 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1454 | if (!error) |
f38aa942 | 1455 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1456 | return error; |
1457 | } | |
1458 | ||
3fb64190 | 1459 | int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1460 | { |
3fb64190 | 1461 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1462 | struct inode *inode = dentry->d_inode; |
1463 | int error; | |
1464 | ||
1465 | if (!inode) | |
1466 | return -ENOENT; | |
1467 | ||
c8fe8f30 CH |
1468 | switch (inode->i_mode & S_IFMT) { |
1469 | case S_IFLNK: | |
1da177e4 | 1470 | return -ELOOP; |
c8fe8f30 CH |
1471 | case S_IFDIR: |
1472 | if (acc_mode & MAY_WRITE) | |
1473 | return -EISDIR; | |
1474 | break; | |
1475 | case S_IFBLK: | |
1476 | case S_IFCHR: | |
3fb64190 | 1477 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 1478 | return -EACCES; |
c8fe8f30 CH |
1479 | /*FALLTHRU*/ |
1480 | case S_IFIFO: | |
1481 | case S_IFSOCK: | |
1da177e4 | 1482 | flag &= ~O_TRUNC; |
c8fe8f30 | 1483 | break; |
4a3fd211 | 1484 | } |
b41572e9 | 1485 | |
3fb64190 | 1486 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
1487 | if (error) |
1488 | return error; | |
6146f0d5 | 1489 | |
1da177e4 LT |
1490 | /* |
1491 | * An append-only file must be opened in append mode for writing. | |
1492 | */ | |
1493 | if (IS_APPEND(inode)) { | |
1494 | if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) | |
7715b521 | 1495 | return -EPERM; |
1da177e4 | 1496 | if (flag & O_TRUNC) |
7715b521 | 1497 | return -EPERM; |
1da177e4 LT |
1498 | } |
1499 | ||
1500 | /* O_NOATIME can only be set by the owner or superuser */ | |
7715b521 AV |
1501 | if (flag & O_NOATIME && !is_owner_or_cap(inode)) |
1502 | return -EPERM; | |
1da177e4 LT |
1503 | |
1504 | /* | |
1505 | * Ensure there are no outstanding leases on the file. | |
1506 | */ | |
b65a9cfc | 1507 | return break_lease(inode, flag); |
7715b521 | 1508 | } |
1da177e4 | 1509 | |
7715b521 AV |
1510 | static int handle_truncate(struct path *path) |
1511 | { | |
1512 | struct inode *inode = path->dentry->d_inode; | |
1513 | int error = get_write_access(inode); | |
1514 | if (error) | |
1515 | return error; | |
1516 | /* | |
1517 | * Refuse to truncate files with mandatory locks held on them. | |
1518 | */ | |
1519 | error = locks_verify_locked(inode); | |
1520 | if (!error) | |
1521 | error = security_path_truncate(path, 0, | |
1522 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); | |
1523 | if (!error) { | |
1524 | error = do_truncate(path->dentry, 0, | |
1525 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
1526 | NULL); | |
1527 | } | |
1528 | put_write_access(inode); | |
acd0c935 | 1529 | return error; |
1da177e4 LT |
1530 | } |
1531 | ||
d57999e1 DH |
1532 | /* |
1533 | * Be careful about ever adding any more callers of this | |
1534 | * function. Its flags must be in the namei format, not | |
1535 | * what get passed to sys_open(). | |
1536 | */ | |
1537 | static int __open_namei_create(struct nameidata *nd, struct path *path, | |
aab520e2 DH |
1538 | int flag, int mode) |
1539 | { | |
1540 | int error; | |
4ac91378 | 1541 | struct dentry *dir = nd->path.dentry; |
aab520e2 DH |
1542 | |
1543 | if (!IS_POSIXACL(dir->d_inode)) | |
ce3b0f8d | 1544 | mode &= ~current_umask(); |
be6d3e56 KT |
1545 | error = security_path_mknod(&nd->path, path->dentry, mode, 0); |
1546 | if (error) | |
1547 | goto out_unlock; | |
aab520e2 | 1548 | error = vfs_create(dir->d_inode, path->dentry, mode, nd); |
be6d3e56 | 1549 | out_unlock: |
aab520e2 | 1550 | mutex_unlock(&dir->d_inode->i_mutex); |
4ac91378 JB |
1551 | dput(nd->path.dentry); |
1552 | nd->path.dentry = path->dentry; | |
aab520e2 DH |
1553 | if (error) |
1554 | return error; | |
1555 | /* Don't check for write permission, don't truncate */ | |
3fb64190 | 1556 | return may_open(&nd->path, 0, flag & ~O_TRUNC); |
aab520e2 DH |
1557 | } |
1558 | ||
d57999e1 DH |
1559 | /* |
1560 | * Note that while the flag value (low two bits) for sys_open means: | |
1561 | * 00 - read-only | |
1562 | * 01 - write-only | |
1563 | * 10 - read-write | |
1564 | * 11 - special | |
1565 | * it is changed into | |
1566 | * 00 - no permissions needed | |
1567 | * 01 - read-permission | |
1568 | * 10 - write-permission | |
1569 | * 11 - read-write | |
1570 | * for the internal routines (ie open_namei()/follow_link() etc) | |
1571 | * This is more logical, and also allows the 00 "no perm needed" | |
1572 | * to be used for symlinks (where the permissions are checked | |
1573 | * later). | |
1574 | * | |
1575 | */ | |
1576 | static inline int open_to_namei_flags(int flag) | |
1577 | { | |
1578 | if ((flag+1) & O_ACCMODE) | |
1579 | flag++; | |
1580 | return flag; | |
1581 | } | |
1582 | ||
7715b521 | 1583 | static int open_will_truncate(int flag, struct inode *inode) |
4a3fd211 DH |
1584 | { |
1585 | /* | |
1586 | * We'll never write to the fs underlying | |
1587 | * a device file. | |
1588 | */ | |
1589 | if (special_file(inode->i_mode)) | |
1590 | return 0; | |
1591 | return (flag & O_TRUNC); | |
1592 | } | |
1593 | ||
1da177e4 | 1594 | /* |
4a3fd211 DH |
1595 | * Note that the low bits of the passed in "open_flag" |
1596 | * are not the same as in the local variable "flag". See | |
1597 | * open_to_namei_flags() for more details. | |
1da177e4 | 1598 | */ |
a70e65df | 1599 | struct file *do_filp_open(int dfd, const char *pathname, |
6e8341a1 | 1600 | int open_flag, int mode, int acc_mode) |
1da177e4 | 1601 | { |
4a3fd211 | 1602 | struct file *filp; |
a70e65df | 1603 | struct nameidata nd; |
6e8341a1 | 1604 | int error; |
6de88d72 | 1605 | struct path path, save; |
1da177e4 LT |
1606 | struct dentry *dir; |
1607 | int count = 0; | |
7715b521 | 1608 | int will_truncate; |
d57999e1 | 1609 | int flag = open_to_namei_flags(open_flag); |
1da177e4 | 1610 | |
6b2f3d1f CH |
1611 | /* |
1612 | * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only | |
1613 | * check for O_DSYNC if the need any syncing at all we enforce it's | |
1614 | * always set instead of having to deal with possibly weird behaviour | |
1615 | * for malicious applications setting only __O_SYNC. | |
1616 | */ | |
1617 | if (open_flag & __O_SYNC) | |
1618 | open_flag |= O_DSYNC; | |
1619 | ||
6e8341a1 AV |
1620 | if (!acc_mode) |
1621 | acc_mode = MAY_OPEN | ACC_MODE(flag); | |
1da177e4 | 1622 | |
834f2a4a TM |
1623 | /* O_TRUNC implies we need access checks for write permissions */ |
1624 | if (flag & O_TRUNC) | |
1625 | acc_mode |= MAY_WRITE; | |
1626 | ||
1da177e4 LT |
1627 | /* Allow the LSM permission hook to distinguish append |
1628 | access from general write access. */ | |
1629 | if (flag & O_APPEND) | |
1630 | acc_mode |= MAY_APPEND; | |
1631 | ||
1da177e4 LT |
1632 | /* |
1633 | * The simplest case - just a plain lookup. | |
1634 | */ | |
1635 | if (!(flag & O_CREAT)) { | |
2dd6d1f4 AV |
1636 | filp = get_empty_filp(); |
1637 | ||
1638 | if (filp == NULL) | |
1639 | return ERR_PTR(-ENFILE); | |
1640 | nd.intent.open.file = filp; | |
482928d5 | 1641 | filp->f_flags = open_flag; |
2dd6d1f4 AV |
1642 | nd.intent.open.flags = flag; |
1643 | nd.intent.open.create_mode = 0; | |
1644 | error = do_path_lookup(dfd, pathname, | |
1645 | lookup_flags(flag)|LOOKUP_OPEN, &nd); | |
1646 | if (IS_ERR(nd.intent.open.file)) { | |
1647 | if (error == 0) { | |
1648 | error = PTR_ERR(nd.intent.open.file); | |
1649 | path_put(&nd.path); | |
1650 | } | |
1651 | } else if (error) | |
1652 | release_open_intent(&nd); | |
1da177e4 | 1653 | if (error) |
a70e65df | 1654 | return ERR_PTR(error); |
1da177e4 LT |
1655 | goto ok; |
1656 | } | |
1657 | ||
1658 | /* | |
1659 | * Create - we need to know the parent. | |
1660 | */ | |
9b4a9b14 | 1661 | error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); |
1da177e4 | 1662 | if (error) |
a70e65df | 1663 | return ERR_PTR(error); |
9b4a9b14 | 1664 | error = path_walk(pathname, &nd); |
654f562c O |
1665 | if (error) { |
1666 | if (nd.root.mnt) | |
1667 | path_put(&nd.root); | |
9b4a9b14 | 1668 | return ERR_PTR(error); |
654f562c | 1669 | } |
9b4a9b14 AV |
1670 | if (unlikely(!audit_dummy_context())) |
1671 | audit_inode(pathname, nd.path.dentry); | |
1da177e4 LT |
1672 | |
1673 | /* | |
1674 | * We have the parent and last component. First of all, check | |
1675 | * that we are not asked to creat(2) an obvious directory - that | |
1676 | * will not do. | |
1677 | */ | |
1678 | error = -EISDIR; | |
a70e65df | 1679 | if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) |
8737f3a1 | 1680 | goto exit_parent; |
1da177e4 | 1681 | |
8737f3a1 AV |
1682 | error = -ENFILE; |
1683 | filp = get_empty_filp(); | |
1684 | if (filp == NULL) | |
1685 | goto exit_parent; | |
1686 | nd.intent.open.file = filp; | |
482928d5 | 1687 | filp->f_flags = open_flag; |
8737f3a1 AV |
1688 | nd.intent.open.flags = flag; |
1689 | nd.intent.open.create_mode = mode; | |
a70e65df CH |
1690 | dir = nd.path.dentry; |
1691 | nd.flags &= ~LOOKUP_PARENT; | |
8737f3a1 | 1692 | nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; |
3516586a AV |
1693 | if (flag & O_EXCL) |
1694 | nd.flags |= LOOKUP_EXCL; | |
1b1dcc1b | 1695 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1696 | path.dentry = lookup_hash(&nd); |
1697 | path.mnt = nd.path.mnt; | |
1da177e4 LT |
1698 | |
1699 | do_last: | |
4e7506e4 AV |
1700 | error = PTR_ERR(path.dentry); |
1701 | if (IS_ERR(path.dentry)) { | |
1b1dcc1b | 1702 | mutex_unlock(&dir->d_inode->i_mutex); |
1da177e4 LT |
1703 | goto exit; |
1704 | } | |
1705 | ||
a70e65df | 1706 | if (IS_ERR(nd.intent.open.file)) { |
a70e65df | 1707 | error = PTR_ERR(nd.intent.open.file); |
4a3fd211 | 1708 | goto exit_mutex_unlock; |
4af4c52f OD |
1709 | } |
1710 | ||
1da177e4 | 1711 | /* Negative dentry, just create the file */ |
4e7506e4 | 1712 | if (!path.dentry->d_inode) { |
4a3fd211 DH |
1713 | /* |
1714 | * This write is needed to ensure that a | |
1715 | * ro->rw transition does not occur between | |
1716 | * the time when the file is created and when | |
1717 | * a permanent write count is taken through | |
1718 | * the 'struct file' in nameidata_to_filp(). | |
1719 | */ | |
1720 | error = mnt_want_write(nd.path.mnt); | |
1da177e4 | 1721 | if (error) |
4a3fd211 DH |
1722 | goto exit_mutex_unlock; |
1723 | error = __open_namei_create(&nd, &path, flag, mode); | |
1724 | if (error) { | |
1725 | mnt_drop_write(nd.path.mnt); | |
1da177e4 | 1726 | goto exit; |
4a3fd211 | 1727 | } |
482928d5 | 1728 | filp = nameidata_to_filp(&nd); |
4a3fd211 | 1729 | mnt_drop_write(nd.path.mnt); |
654f562c O |
1730 | if (nd.root.mnt) |
1731 | path_put(&nd.root); | |
b65a9cfc AV |
1732 | if (!IS_ERR(filp)) { |
1733 | error = ima_path_check(&filp->f_path, filp->f_mode & | |
1429b3ec | 1734 | (MAY_READ | MAY_WRITE | MAY_EXEC)); |
b65a9cfc AV |
1735 | if (error) { |
1736 | fput(filp); | |
1737 | filp = ERR_PTR(error); | |
1738 | } | |
1739 | } | |
4a3fd211 | 1740 | return filp; |
1da177e4 LT |
1741 | } |
1742 | ||
1743 | /* | |
1744 | * It already exists. | |
1745 | */ | |
1b1dcc1b | 1746 | mutex_unlock(&dir->d_inode->i_mutex); |
5a190ae6 | 1747 | audit_inode(pathname, path.dentry); |
1da177e4 LT |
1748 | |
1749 | error = -EEXIST; | |
1750 | if (flag & O_EXCL) | |
1751 | goto exit_dput; | |
1752 | ||
e13b210f | 1753 | if (__follow_mount(&path)) { |
1da177e4 | 1754 | error = -ELOOP; |
ba7a4c1a AV |
1755 | if (flag & O_NOFOLLOW) |
1756 | goto exit_dput; | |
1da177e4 | 1757 | } |
3e2efce0 | 1758 | |
1da177e4 | 1759 | error = -ENOENT; |
4e7506e4 | 1760 | if (!path.dentry->d_inode) |
1da177e4 | 1761 | goto exit_dput; |
acfa4380 | 1762 | if (path.dentry->d_inode->i_op->follow_link) |
1da177e4 LT |
1763 | goto do_link; |
1764 | ||
a70e65df | 1765 | path_to_nameidata(&path, &nd); |
1da177e4 | 1766 | error = -EISDIR; |
cb59861f | 1767 | if (S_ISDIR(path.dentry->d_inode->i_mode)) |
1da177e4 LT |
1768 | goto exit; |
1769 | ok: | |
4a3fd211 DH |
1770 | /* |
1771 | * Consider: | |
1772 | * 1. may_open() truncates a file | |
1773 | * 2. a rw->ro mount transition occurs | |
1774 | * 3. nameidata_to_filp() fails due to | |
1775 | * the ro mount. | |
1776 | * That would be inconsistent, and should | |
1777 | * be avoided. Taking this mnt write here | |
1778 | * ensures that (2) can not occur. | |
1779 | */ | |
7715b521 AV |
1780 | will_truncate = open_will_truncate(flag, nd.path.dentry->d_inode); |
1781 | if (will_truncate) { | |
4a3fd211 DH |
1782 | error = mnt_want_write(nd.path.mnt); |
1783 | if (error) | |
1784 | goto exit; | |
1785 | } | |
3fb64190 | 1786 | error = may_open(&nd.path, acc_mode, flag); |
4a3fd211 | 1787 | if (error) { |
7715b521 | 1788 | if (will_truncate) |
4a3fd211 | 1789 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 1790 | goto exit; |
4a3fd211 | 1791 | } |
482928d5 | 1792 | filp = nameidata_to_filp(&nd); |
b65a9cfc AV |
1793 | if (!IS_ERR(filp)) { |
1794 | error = ima_path_check(&filp->f_path, filp->f_mode & | |
1429b3ec | 1795 | (MAY_READ | MAY_WRITE | MAY_EXEC)); |
7715b521 | 1796 | if (error) { |
7715b521 | 1797 | fput(filp); |
b65a9cfc AV |
1798 | filp = ERR_PTR(error); |
1799 | } | |
1800 | } | |
1801 | if (!IS_ERR(filp)) { | |
1802 | if (acc_mode & MAY_WRITE) | |
1803 | vfs_dq_init(nd.path.dentry->d_inode); | |
1804 | ||
1805 | if (will_truncate) { | |
1806 | error = handle_truncate(&nd.path); | |
1807 | if (error) { | |
1808 | fput(filp); | |
1809 | filp = ERR_PTR(error); | |
1810 | } | |
7715b521 AV |
1811 | } |
1812 | } | |
4a3fd211 DH |
1813 | /* |
1814 | * It is now safe to drop the mnt write | |
1815 | * because the filp has had a write taken | |
1816 | * on its behalf. | |
1817 | */ | |
7715b521 | 1818 | if (will_truncate) |
4a3fd211 | 1819 | mnt_drop_write(nd.path.mnt); |
654f562c O |
1820 | if (nd.root.mnt) |
1821 | path_put(&nd.root); | |
4a3fd211 | 1822 | return filp; |
1da177e4 | 1823 | |
4a3fd211 DH |
1824 | exit_mutex_unlock: |
1825 | mutex_unlock(&dir->d_inode->i_mutex); | |
1da177e4 | 1826 | exit_dput: |
a70e65df | 1827 | path_put_conditional(&path, &nd); |
1da177e4 | 1828 | exit: |
a70e65df CH |
1829 | if (!IS_ERR(nd.intent.open.file)) |
1830 | release_open_intent(&nd); | |
8737f3a1 | 1831 | exit_parent: |
2a737871 AV |
1832 | if (nd.root.mnt) |
1833 | path_put(&nd.root); | |
a70e65df CH |
1834 | path_put(&nd.path); |
1835 | return ERR_PTR(error); | |
1da177e4 LT |
1836 | |
1837 | do_link: | |
1838 | error = -ELOOP; | |
1839 | if (flag & O_NOFOLLOW) | |
1840 | goto exit_dput; | |
1841 | /* | |
1842 | * This is subtle. Instead of calling do_follow_link() we do the | |
1843 | * thing by hands. The reason is that this way we have zero link_count | |
1844 | * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. | |
1845 | * After that we have the parent and last component, i.e. | |
1846 | * we are in the same situation as after the first path_walk(). | |
1847 | * Well, almost - if the last component is normal we get its copy | |
1848 | * stored in nd->last.name and we will have to putname() it when we | |
1849 | * are done. Procfs-like symlinks just set LAST_BIND. | |
1850 | */ | |
a70e65df CH |
1851 | nd.flags |= LOOKUP_PARENT; |
1852 | error = security_inode_follow_link(path.dentry, &nd); | |
1da177e4 LT |
1853 | if (error) |
1854 | goto exit_dput; | |
6de88d72 AV |
1855 | save = nd.path; |
1856 | path_get(&save); | |
a70e65df | 1857 | error = __do_follow_link(&path, &nd); |
6de88d72 AV |
1858 | if (error == -ESTALE) { |
1859 | /* nd.path had been dropped */ | |
1860 | nd.path = save; | |
1861 | path_get(&nd.path); | |
1862 | nd.flags |= LOOKUP_REVAL; | |
1863 | error = __do_follow_link(&path, &nd); | |
1864 | } | |
1865 | path_put(&save); | |
258fa999 | 1866 | path_put(&path); |
de459215 KK |
1867 | if (error) { |
1868 | /* Does someone understand code flow here? Or it is only | |
1869 | * me so stupid? Anathema to whoever designed this non-sense | |
1870 | * with "intent.open". | |
1871 | */ | |
a70e65df | 1872 | release_open_intent(&nd); |
654f562c O |
1873 | if (nd.root.mnt) |
1874 | path_put(&nd.root); | |
a70e65df | 1875 | return ERR_PTR(error); |
de459215 | 1876 | } |
a70e65df CH |
1877 | nd.flags &= ~LOOKUP_PARENT; |
1878 | if (nd.last_type == LAST_BIND) | |
1da177e4 | 1879 | goto ok; |
1da177e4 | 1880 | error = -EISDIR; |
a70e65df | 1881 | if (nd.last_type != LAST_NORM) |
1da177e4 | 1882 | goto exit; |
a70e65df CH |
1883 | if (nd.last.name[nd.last.len]) { |
1884 | __putname(nd.last.name); | |
1da177e4 LT |
1885 | goto exit; |
1886 | } | |
1887 | error = -ELOOP; | |
1888 | if (count++==32) { | |
a70e65df | 1889 | __putname(nd.last.name); |
1da177e4 LT |
1890 | goto exit; |
1891 | } | |
a70e65df | 1892 | dir = nd.path.dentry; |
1b1dcc1b | 1893 | mutex_lock(&dir->d_inode->i_mutex); |
a70e65df CH |
1894 | path.dentry = lookup_hash(&nd); |
1895 | path.mnt = nd.path.mnt; | |
1896 | __putname(nd.last.name); | |
1da177e4 LT |
1897 | goto do_last; |
1898 | } | |
1899 | ||
a70e65df CH |
1900 | /** |
1901 | * filp_open - open file and return file pointer | |
1902 | * | |
1903 | * @filename: path to open | |
1904 | * @flags: open flags as per the open(2) second argument | |
1905 | * @mode: mode for the new file if O_CREAT is set, else ignored | |
1906 | * | |
1907 | * This is the helper to open a file from kernelspace if you really | |
1908 | * have to. But in generally you should not do this, so please move | |
1909 | * along, nothing to see here.. | |
1910 | */ | |
1911 | struct file *filp_open(const char *filename, int flags, int mode) | |
1912 | { | |
6e8341a1 | 1913 | return do_filp_open(AT_FDCWD, filename, flags, mode, 0); |
a70e65df CH |
1914 | } |
1915 | EXPORT_SYMBOL(filp_open); | |
1916 | ||
1da177e4 LT |
1917 | /** |
1918 | * lookup_create - lookup a dentry, creating it if it doesn't exist | |
1919 | * @nd: nameidata info | |
1920 | * @is_dir: directory flag | |
1921 | * | |
1922 | * Simple function to lookup and return a dentry and create it | |
1923 | * if it doesn't exist. Is SMP-safe. | |
c663e5d8 | 1924 | * |
4ac91378 | 1925 | * Returns with nd->path.dentry->d_inode->i_mutex locked. |
1da177e4 LT |
1926 | */ |
1927 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) | |
1928 | { | |
c663e5d8 | 1929 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1da177e4 | 1930 | |
4ac91378 | 1931 | mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
c663e5d8 CH |
1932 | /* |
1933 | * Yucky last component or no last component at all? | |
1934 | * (foo/., foo/.., /////) | |
1935 | */ | |
1da177e4 LT |
1936 | if (nd->last_type != LAST_NORM) |
1937 | goto fail; | |
1938 | nd->flags &= ~LOOKUP_PARENT; | |
3516586a | 1939 | nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
a634904a | 1940 | nd->intent.open.flags = O_EXCL; |
c663e5d8 CH |
1941 | |
1942 | /* | |
1943 | * Do the final lookup. | |
1944 | */ | |
49705b77 | 1945 | dentry = lookup_hash(nd); |
1da177e4 LT |
1946 | if (IS_ERR(dentry)) |
1947 | goto fail; | |
c663e5d8 | 1948 | |
e9baf6e5 AV |
1949 | if (dentry->d_inode) |
1950 | goto eexist; | |
c663e5d8 CH |
1951 | /* |
1952 | * Special case - lookup gave negative, but... we had foo/bar/ | |
1953 | * From the vfs_mknod() POV we just have a negative dentry - | |
1954 | * all is fine. Let's be bastards - you had / on the end, you've | |
1955 | * been asking for (non-existent) directory. -ENOENT for you. | |
1956 | */ | |
e9baf6e5 AV |
1957 | if (unlikely(!is_dir && nd->last.name[nd->last.len])) { |
1958 | dput(dentry); | |
1959 | dentry = ERR_PTR(-ENOENT); | |
1960 | } | |
1da177e4 | 1961 | return dentry; |
e9baf6e5 | 1962 | eexist: |
1da177e4 | 1963 | dput(dentry); |
e9baf6e5 | 1964 | dentry = ERR_PTR(-EEXIST); |
1da177e4 LT |
1965 | fail: |
1966 | return dentry; | |
1967 | } | |
f81a0bff | 1968 | EXPORT_SYMBOL_GPL(lookup_create); |
1da177e4 LT |
1969 | |
1970 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
1971 | { | |
a95164d9 | 1972 | int error = may_create(dir, dentry); |
1da177e4 LT |
1973 | |
1974 | if (error) | |
1975 | return error; | |
1976 | ||
1977 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) | |
1978 | return -EPERM; | |
1979 | ||
acfa4380 | 1980 | if (!dir->i_op->mknod) |
1da177e4 LT |
1981 | return -EPERM; |
1982 | ||
08ce5f16 SH |
1983 | error = devcgroup_inode_mknod(mode, dev); |
1984 | if (error) | |
1985 | return error; | |
1986 | ||
1da177e4 LT |
1987 | error = security_inode_mknod(dir, dentry, mode, dev); |
1988 | if (error) | |
1989 | return error; | |
1990 | ||
9e3509e2 | 1991 | vfs_dq_init(dir); |
1da177e4 | 1992 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 1993 | if (!error) |
f38aa942 | 1994 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1995 | return error; |
1996 | } | |
1997 | ||
463c3197 DH |
1998 | static int may_mknod(mode_t mode) |
1999 | { | |
2000 | switch (mode & S_IFMT) { | |
2001 | case S_IFREG: | |
2002 | case S_IFCHR: | |
2003 | case S_IFBLK: | |
2004 | case S_IFIFO: | |
2005 | case S_IFSOCK: | |
2006 | case 0: /* zero mode translates to S_IFREG */ | |
2007 | return 0; | |
2008 | case S_IFDIR: | |
2009 | return -EPERM; | |
2010 | default: | |
2011 | return -EINVAL; | |
2012 | } | |
2013 | } | |
2014 | ||
2e4d0924 HC |
2015 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2016 | unsigned, dev) | |
1da177e4 | 2017 | { |
2ad94ae6 AV |
2018 | int error; |
2019 | char *tmp; | |
2020 | struct dentry *dentry; | |
1da177e4 LT |
2021 | struct nameidata nd; |
2022 | ||
2023 | if (S_ISDIR(mode)) | |
2024 | return -EPERM; | |
1da177e4 | 2025 | |
2ad94ae6 | 2026 | error = user_path_parent(dfd, filename, &nd, &tmp); |
1da177e4 | 2027 | if (error) |
2ad94ae6 AV |
2028 | return error; |
2029 | ||
1da177e4 | 2030 | dentry = lookup_create(&nd, 0); |
463c3197 DH |
2031 | if (IS_ERR(dentry)) { |
2032 | error = PTR_ERR(dentry); | |
2033 | goto out_unlock; | |
2034 | } | |
4ac91378 | 2035 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
ce3b0f8d | 2036 | mode &= ~current_umask(); |
463c3197 DH |
2037 | error = may_mknod(mode); |
2038 | if (error) | |
2039 | goto out_dput; | |
2040 | error = mnt_want_write(nd.path.mnt); | |
2041 | if (error) | |
2042 | goto out_dput; | |
be6d3e56 KT |
2043 | error = security_path_mknod(&nd.path, dentry, mode, dev); |
2044 | if (error) | |
2045 | goto out_drop_write; | |
463c3197 | 2046 | switch (mode & S_IFMT) { |
1da177e4 | 2047 | case 0: case S_IFREG: |
4ac91378 | 2048 | error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); |
1da177e4 LT |
2049 | break; |
2050 | case S_IFCHR: case S_IFBLK: | |
4ac91378 | 2051 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2052 | new_decode_dev(dev)); |
2053 | break; | |
2054 | case S_IFIFO: case S_IFSOCK: | |
4ac91378 | 2055 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2056 | break; |
1da177e4 | 2057 | } |
be6d3e56 | 2058 | out_drop_write: |
463c3197 DH |
2059 | mnt_drop_write(nd.path.mnt); |
2060 | out_dput: | |
2061 | dput(dentry); | |
2062 | out_unlock: | |
4ac91378 | 2063 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2064 | path_put(&nd.path); |
1da177e4 LT |
2065 | putname(tmp); |
2066 | ||
2067 | return error; | |
2068 | } | |
2069 | ||
3480b257 | 2070 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2071 | { |
2072 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2073 | } | |
2074 | ||
1da177e4 LT |
2075 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2076 | { | |
a95164d9 | 2077 | int error = may_create(dir, dentry); |
1da177e4 LT |
2078 | |
2079 | if (error) | |
2080 | return error; | |
2081 | ||
acfa4380 | 2082 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2083 | return -EPERM; |
2084 | ||
2085 | mode &= (S_IRWXUGO|S_ISVTX); | |
2086 | error = security_inode_mkdir(dir, dentry, mode); | |
2087 | if (error) | |
2088 | return error; | |
2089 | ||
9e3509e2 | 2090 | vfs_dq_init(dir); |
1da177e4 | 2091 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2092 | if (!error) |
f38aa942 | 2093 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2094 | return error; |
2095 | } | |
2096 | ||
2e4d0924 | 2097 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 LT |
2098 | { |
2099 | int error = 0; | |
2100 | char * tmp; | |
6902d925 DH |
2101 | struct dentry *dentry; |
2102 | struct nameidata nd; | |
1da177e4 | 2103 | |
2ad94ae6 AV |
2104 | error = user_path_parent(dfd, pathname, &nd, &tmp); |
2105 | if (error) | |
6902d925 | 2106 | goto out_err; |
1da177e4 | 2107 | |
6902d925 DH |
2108 | dentry = lookup_create(&nd, 1); |
2109 | error = PTR_ERR(dentry); | |
2110 | if (IS_ERR(dentry)) | |
2111 | goto out_unlock; | |
1da177e4 | 2112 | |
4ac91378 | 2113 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
ce3b0f8d | 2114 | mode &= ~current_umask(); |
463c3197 DH |
2115 | error = mnt_want_write(nd.path.mnt); |
2116 | if (error) | |
2117 | goto out_dput; | |
be6d3e56 KT |
2118 | error = security_path_mkdir(&nd.path, dentry, mode); |
2119 | if (error) | |
2120 | goto out_drop_write; | |
4ac91378 | 2121 | error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2122 | out_drop_write: |
463c3197 DH |
2123 | mnt_drop_write(nd.path.mnt); |
2124 | out_dput: | |
6902d925 DH |
2125 | dput(dentry); |
2126 | out_unlock: | |
4ac91378 | 2127 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2128 | path_put(&nd.path); |
6902d925 DH |
2129 | putname(tmp); |
2130 | out_err: | |
1da177e4 LT |
2131 | return error; |
2132 | } | |
2133 | ||
3cdad428 | 2134 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2135 | { |
2136 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2137 | } | |
2138 | ||
1da177e4 LT |
2139 | /* |
2140 | * We try to drop the dentry early: we should have | |
2141 | * a usage count of 2 if we're the only user of this | |
2142 | * dentry, and if that is true (possibly after pruning | |
2143 | * the dcache), then we drop the dentry now. | |
2144 | * | |
2145 | * A low-level filesystem can, if it choses, legally | |
2146 | * do a | |
2147 | * | |
2148 | * if (!d_unhashed(dentry)) | |
2149 | * return -EBUSY; | |
2150 | * | |
2151 | * if it cannot handle the case of removing a directory | |
2152 | * that is still in use by something else.. | |
2153 | */ | |
2154 | void dentry_unhash(struct dentry *dentry) | |
2155 | { | |
2156 | dget(dentry); | |
dc168427 | 2157 | shrink_dcache_parent(dentry); |
1da177e4 LT |
2158 | spin_lock(&dcache_lock); |
2159 | spin_lock(&dentry->d_lock); | |
2160 | if (atomic_read(&dentry->d_count) == 2) | |
2161 | __d_drop(dentry); | |
2162 | spin_unlock(&dentry->d_lock); | |
2163 | spin_unlock(&dcache_lock); | |
2164 | } | |
2165 | ||
2166 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2167 | { | |
2168 | int error = may_delete(dir, dentry, 1); | |
2169 | ||
2170 | if (error) | |
2171 | return error; | |
2172 | ||
acfa4380 | 2173 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2174 | return -EPERM; |
2175 | ||
9e3509e2 | 2176 | vfs_dq_init(dir); |
1da177e4 | 2177 | |
1b1dcc1b | 2178 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2179 | dentry_unhash(dentry); |
2180 | if (d_mountpoint(dentry)) | |
2181 | error = -EBUSY; | |
2182 | else { | |
2183 | error = security_inode_rmdir(dir, dentry); | |
2184 | if (!error) { | |
2185 | error = dir->i_op->rmdir(dir, dentry); | |
2186 | if (!error) | |
2187 | dentry->d_inode->i_flags |= S_DEAD; | |
2188 | } | |
2189 | } | |
1b1dcc1b | 2190 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 | 2191 | if (!error) { |
1da177e4 LT |
2192 | d_delete(dentry); |
2193 | } | |
2194 | dput(dentry); | |
2195 | ||
2196 | return error; | |
2197 | } | |
2198 | ||
5590ff0d | 2199 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2200 | { |
2201 | int error = 0; | |
2202 | char * name; | |
2203 | struct dentry *dentry; | |
2204 | struct nameidata nd; | |
2205 | ||
2ad94ae6 | 2206 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2207 | if (error) |
2ad94ae6 | 2208 | return error; |
1da177e4 LT |
2209 | |
2210 | switch(nd.last_type) { | |
0612d9fb OH |
2211 | case LAST_DOTDOT: |
2212 | error = -ENOTEMPTY; | |
2213 | goto exit1; | |
2214 | case LAST_DOT: | |
2215 | error = -EINVAL; | |
2216 | goto exit1; | |
2217 | case LAST_ROOT: | |
2218 | error = -EBUSY; | |
2219 | goto exit1; | |
1da177e4 | 2220 | } |
0612d9fb OH |
2221 | |
2222 | nd.flags &= ~LOOKUP_PARENT; | |
2223 | ||
4ac91378 | 2224 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2225 | dentry = lookup_hash(&nd); |
1da177e4 | 2226 | error = PTR_ERR(dentry); |
6902d925 DH |
2227 | if (IS_ERR(dentry)) |
2228 | goto exit2; | |
0622753b DH |
2229 | error = mnt_want_write(nd.path.mnt); |
2230 | if (error) | |
2231 | goto exit3; | |
be6d3e56 KT |
2232 | error = security_path_rmdir(&nd.path, dentry); |
2233 | if (error) | |
2234 | goto exit4; | |
4ac91378 | 2235 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2236 | exit4: |
0622753b DH |
2237 | mnt_drop_write(nd.path.mnt); |
2238 | exit3: | |
6902d925 DH |
2239 | dput(dentry); |
2240 | exit2: | |
4ac91378 | 2241 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2242 | exit1: |
1d957f9b | 2243 | path_put(&nd.path); |
1da177e4 LT |
2244 | putname(name); |
2245 | return error; | |
2246 | } | |
2247 | ||
3cdad428 | 2248 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2249 | { |
2250 | return do_rmdir(AT_FDCWD, pathname); | |
2251 | } | |
2252 | ||
1da177e4 LT |
2253 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2254 | { | |
2255 | int error = may_delete(dir, dentry, 0); | |
2256 | ||
2257 | if (error) | |
2258 | return error; | |
2259 | ||
acfa4380 | 2260 | if (!dir->i_op->unlink) |
1da177e4 LT |
2261 | return -EPERM; |
2262 | ||
9e3509e2 | 2263 | vfs_dq_init(dir); |
1da177e4 | 2264 | |
1b1dcc1b | 2265 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2266 | if (d_mountpoint(dentry)) |
2267 | error = -EBUSY; | |
2268 | else { | |
2269 | error = security_inode_unlink(dir, dentry); | |
2270 | if (!error) | |
2271 | error = dir->i_op->unlink(dir, dentry); | |
2272 | } | |
1b1dcc1b | 2273 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2274 | |
2275 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2276 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2277 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2278 | d_delete(dentry); |
1da177e4 | 2279 | } |
0eeca283 | 2280 | |
1da177e4 LT |
2281 | return error; |
2282 | } | |
2283 | ||
2284 | /* | |
2285 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2286 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2287 | * writeout happening, and we don't want to prevent access to the directory |
2288 | * while waiting on the I/O. | |
2289 | */ | |
5590ff0d | 2290 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2291 | { |
2ad94ae6 AV |
2292 | int error; |
2293 | char *name; | |
1da177e4 LT |
2294 | struct dentry *dentry; |
2295 | struct nameidata nd; | |
2296 | struct inode *inode = NULL; | |
2297 | ||
2ad94ae6 | 2298 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2299 | if (error) |
2ad94ae6 AV |
2300 | return error; |
2301 | ||
1da177e4 LT |
2302 | error = -EISDIR; |
2303 | if (nd.last_type != LAST_NORM) | |
2304 | goto exit1; | |
0612d9fb OH |
2305 | |
2306 | nd.flags &= ~LOOKUP_PARENT; | |
2307 | ||
4ac91378 | 2308 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2309 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2310 | error = PTR_ERR(dentry); |
2311 | if (!IS_ERR(dentry)) { | |
2312 | /* Why not before? Because we want correct error value */ | |
2313 | if (nd.last.name[nd.last.len]) | |
2314 | goto slashes; | |
2315 | inode = dentry->d_inode; | |
2316 | if (inode) | |
2317 | atomic_inc(&inode->i_count); | |
0622753b DH |
2318 | error = mnt_want_write(nd.path.mnt); |
2319 | if (error) | |
2320 | goto exit2; | |
be6d3e56 KT |
2321 | error = security_path_unlink(&nd.path, dentry); |
2322 | if (error) | |
2323 | goto exit3; | |
4ac91378 | 2324 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2325 | exit3: |
0622753b | 2326 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2327 | exit2: |
2328 | dput(dentry); | |
2329 | } | |
4ac91378 | 2330 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2331 | if (inode) |
2332 | iput(inode); /* truncate the inode here */ | |
2333 | exit1: | |
1d957f9b | 2334 | path_put(&nd.path); |
1da177e4 LT |
2335 | putname(name); |
2336 | return error; | |
2337 | ||
2338 | slashes: | |
2339 | error = !dentry->d_inode ? -ENOENT : | |
2340 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2341 | goto exit2; | |
2342 | } | |
2343 | ||
2e4d0924 | 2344 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2345 | { |
2346 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2347 | return -EINVAL; | |
2348 | ||
2349 | if (flag & AT_REMOVEDIR) | |
2350 | return do_rmdir(dfd, pathname); | |
2351 | ||
2352 | return do_unlinkat(dfd, pathname); | |
2353 | } | |
2354 | ||
3480b257 | 2355 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2356 | { |
2357 | return do_unlinkat(AT_FDCWD, pathname); | |
2358 | } | |
2359 | ||
db2e747b | 2360 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2361 | { |
a95164d9 | 2362 | int error = may_create(dir, dentry); |
1da177e4 LT |
2363 | |
2364 | if (error) | |
2365 | return error; | |
2366 | ||
acfa4380 | 2367 | if (!dir->i_op->symlink) |
1da177e4 LT |
2368 | return -EPERM; |
2369 | ||
2370 | error = security_inode_symlink(dir, dentry, oldname); | |
2371 | if (error) | |
2372 | return error; | |
2373 | ||
9e3509e2 | 2374 | vfs_dq_init(dir); |
1da177e4 | 2375 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2376 | if (!error) |
f38aa942 | 2377 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2378 | return error; |
2379 | } | |
2380 | ||
2e4d0924 HC |
2381 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2382 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2383 | { |
2ad94ae6 AV |
2384 | int error; |
2385 | char *from; | |
2386 | char *to; | |
6902d925 DH |
2387 | struct dentry *dentry; |
2388 | struct nameidata nd; | |
1da177e4 LT |
2389 | |
2390 | from = getname(oldname); | |
2ad94ae6 | 2391 | if (IS_ERR(from)) |
1da177e4 | 2392 | return PTR_ERR(from); |
1da177e4 | 2393 | |
2ad94ae6 | 2394 | error = user_path_parent(newdfd, newname, &nd, &to); |
6902d925 | 2395 | if (error) |
2ad94ae6 AV |
2396 | goto out_putname; |
2397 | ||
6902d925 DH |
2398 | dentry = lookup_create(&nd, 0); |
2399 | error = PTR_ERR(dentry); | |
2400 | if (IS_ERR(dentry)) | |
2401 | goto out_unlock; | |
2402 | ||
75c3f29d DH |
2403 | error = mnt_want_write(nd.path.mnt); |
2404 | if (error) | |
2405 | goto out_dput; | |
be6d3e56 KT |
2406 | error = security_path_symlink(&nd.path, dentry, from); |
2407 | if (error) | |
2408 | goto out_drop_write; | |
db2e747b | 2409 | error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); |
be6d3e56 | 2410 | out_drop_write: |
75c3f29d DH |
2411 | mnt_drop_write(nd.path.mnt); |
2412 | out_dput: | |
6902d925 DH |
2413 | dput(dentry); |
2414 | out_unlock: | |
4ac91378 | 2415 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1d957f9b | 2416 | path_put(&nd.path); |
6902d925 DH |
2417 | putname(to); |
2418 | out_putname: | |
1da177e4 LT |
2419 | putname(from); |
2420 | return error; | |
2421 | } | |
2422 | ||
3480b257 | 2423 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2424 | { |
2425 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2426 | } | |
2427 | ||
1da177e4 LT |
2428 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2429 | { | |
2430 | struct inode *inode = old_dentry->d_inode; | |
2431 | int error; | |
2432 | ||
2433 | if (!inode) | |
2434 | return -ENOENT; | |
2435 | ||
a95164d9 | 2436 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2437 | if (error) |
2438 | return error; | |
2439 | ||
2440 | if (dir->i_sb != inode->i_sb) | |
2441 | return -EXDEV; | |
2442 | ||
2443 | /* | |
2444 | * A link to an append-only or immutable file cannot be created. | |
2445 | */ | |
2446 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2447 | return -EPERM; | |
acfa4380 | 2448 | if (!dir->i_op->link) |
1da177e4 | 2449 | return -EPERM; |
7e79eedb | 2450 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2451 | return -EPERM; |
2452 | ||
2453 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2454 | if (error) | |
2455 | return error; | |
2456 | ||
7e79eedb | 2457 | mutex_lock(&inode->i_mutex); |
9e3509e2 | 2458 | vfs_dq_init(dir); |
1da177e4 | 2459 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
7e79eedb | 2460 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2461 | if (!error) |
7e79eedb | 2462 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2463 | return error; |
2464 | } | |
2465 | ||
2466 | /* | |
2467 | * Hardlinks are often used in delicate situations. We avoid | |
2468 | * security-related surprises by not following symlinks on the | |
2469 | * newname. --KAB | |
2470 | * | |
2471 | * We don't follow them on the oldname either to be compatible | |
2472 | * with linux 2.0, and to avoid hard-linking to directories | |
2473 | * and other special files. --ADM | |
2474 | */ | |
2e4d0924 HC |
2475 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2476 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2477 | { |
2478 | struct dentry *new_dentry; | |
2d8f3038 AV |
2479 | struct nameidata nd; |
2480 | struct path old_path; | |
1da177e4 | 2481 | int error; |
2ad94ae6 | 2482 | char *to; |
1da177e4 | 2483 | |
45c9b11a | 2484 | if ((flags & ~AT_SYMLINK_FOLLOW) != 0) |
c04030e1 UD |
2485 | return -EINVAL; |
2486 | ||
2d8f3038 AV |
2487 | error = user_path_at(olddfd, oldname, |
2488 | flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, | |
2489 | &old_path); | |
1da177e4 | 2490 | if (error) |
2ad94ae6 AV |
2491 | return error; |
2492 | ||
2493 | error = user_path_parent(newdfd, newname, &nd, &to); | |
1da177e4 LT |
2494 | if (error) |
2495 | goto out; | |
2496 | error = -EXDEV; | |
2d8f3038 | 2497 | if (old_path.mnt != nd.path.mnt) |
1da177e4 LT |
2498 | goto out_release; |
2499 | new_dentry = lookup_create(&nd, 0); | |
2500 | error = PTR_ERR(new_dentry); | |
6902d925 DH |
2501 | if (IS_ERR(new_dentry)) |
2502 | goto out_unlock; | |
75c3f29d DH |
2503 | error = mnt_want_write(nd.path.mnt); |
2504 | if (error) | |
2505 | goto out_dput; | |
be6d3e56 KT |
2506 | error = security_path_link(old_path.dentry, &nd.path, new_dentry); |
2507 | if (error) | |
2508 | goto out_drop_write; | |
2d8f3038 | 2509 | error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); |
be6d3e56 | 2510 | out_drop_write: |
75c3f29d DH |
2511 | mnt_drop_write(nd.path.mnt); |
2512 | out_dput: | |
6902d925 DH |
2513 | dput(new_dentry); |
2514 | out_unlock: | |
4ac91378 | 2515 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2516 | out_release: |
1d957f9b | 2517 | path_put(&nd.path); |
2ad94ae6 | 2518 | putname(to); |
1da177e4 | 2519 | out: |
2d8f3038 | 2520 | path_put(&old_path); |
1da177e4 LT |
2521 | |
2522 | return error; | |
2523 | } | |
2524 | ||
3480b257 | 2525 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2526 | { |
c04030e1 | 2527 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2528 | } |
2529 | ||
1da177e4 LT |
2530 | /* |
2531 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2532 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2533 | * Problems: | |
2534 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2535 | * b) race potential - two innocent renames can create a loop together. | |
2536 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2537 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2538 | * story. |
2539 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2540 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2541 | * whether the target exists). Solution: try to be smart with locking |
2542 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2543 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2544 | * move will be locked. Thus we can rank directories by the tree |
2545 | * (ancestors first) and rank all non-directories after them. | |
2546 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2547 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2548 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2549 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2550 | * we'd better make sure that there's no link(2) for them. | |
2551 | * d) some filesystems don't support opened-but-unlinked directories, | |
2552 | * either because of layout or because they are not ready to deal with | |
2553 | * all cases correctly. The latter will be fixed (taking this sort of | |
2554 | * stuff into VFS), but the former is not going away. Solution: the same | |
2555 | * trick as in rmdir(). | |
2556 | * e) conversion from fhandle to dentry may come in the wrong moment - when | |
1b1dcc1b | 2557 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2558 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
1b1dcc1b | 2559 | * ->i_mutex on parents, which works but leads to some truely excessive |
1da177e4 LT |
2560 | * locking]. |
2561 | */ | |
75c96f85 AB |
2562 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2563 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2564 | { |
2565 | int error = 0; | |
2566 | struct inode *target; | |
2567 | ||
2568 | /* | |
2569 | * If we are going to change the parent - check write permissions, | |
2570 | * we'll need to flip '..'. | |
2571 | */ | |
2572 | if (new_dir != old_dir) { | |
f419a2e3 | 2573 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
2574 | if (error) |
2575 | return error; | |
2576 | } | |
2577 | ||
2578 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2579 | if (error) | |
2580 | return error; | |
2581 | ||
2582 | target = new_dentry->d_inode; | |
2583 | if (target) { | |
1b1dcc1b | 2584 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2585 | dentry_unhash(new_dentry); |
2586 | } | |
2587 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) | |
2588 | error = -EBUSY; | |
2589 | else | |
2590 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2591 | if (target) { | |
2592 | if (!error) | |
2593 | target->i_flags |= S_DEAD; | |
1b1dcc1b | 2594 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2595 | if (d_unhashed(new_dentry)) |
2596 | d_rehash(new_dentry); | |
2597 | dput(new_dentry); | |
2598 | } | |
e31e14ec | 2599 | if (!error) |
349457cc MF |
2600 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2601 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
2602 | return error; |
2603 | } | |
2604 | ||
75c96f85 AB |
2605 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2606 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2607 | { |
2608 | struct inode *target; | |
2609 | int error; | |
2610 | ||
2611 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2612 | if (error) | |
2613 | return error; | |
2614 | ||
2615 | dget(new_dentry); | |
2616 | target = new_dentry->d_inode; | |
2617 | if (target) | |
1b1dcc1b | 2618 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
2619 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2620 | error = -EBUSY; | |
2621 | else | |
2622 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2623 | if (!error) { | |
349457cc | 2624 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
1da177e4 | 2625 | d_move(old_dentry, new_dentry); |
1da177e4 LT |
2626 | } |
2627 | if (target) | |
1b1dcc1b | 2628 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2629 | dput(new_dentry); |
2630 | return error; | |
2631 | } | |
2632 | ||
2633 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2634 | struct inode *new_dir, struct dentry *new_dentry) | |
2635 | { | |
2636 | int error; | |
2637 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
0eeca283 | 2638 | const char *old_name; |
1da177e4 LT |
2639 | |
2640 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2641 | return 0; | |
2642 | ||
2643 | error = may_delete(old_dir, old_dentry, is_dir); | |
2644 | if (error) | |
2645 | return error; | |
2646 | ||
2647 | if (!new_dentry->d_inode) | |
a95164d9 | 2648 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
2649 | else |
2650 | error = may_delete(new_dir, new_dentry, is_dir); | |
2651 | if (error) | |
2652 | return error; | |
2653 | ||
acfa4380 | 2654 | if (!old_dir->i_op->rename) |
1da177e4 LT |
2655 | return -EPERM; |
2656 | ||
9e3509e2 JK |
2657 | vfs_dq_init(old_dir); |
2658 | vfs_dq_init(new_dir); | |
1da177e4 | 2659 | |
0eeca283 RL |
2660 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2661 | ||
1da177e4 LT |
2662 | if (is_dir) |
2663 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
2664 | else | |
2665 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
2666 | if (!error) { | |
0eeca283 | 2667 | const char *new_name = old_dentry->d_name.name; |
89204c40 | 2668 | fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, |
5a190ae6 | 2669 | new_dentry->d_inode, old_dentry); |
1da177e4 | 2670 | } |
0eeca283 RL |
2671 | fsnotify_oldname_free(old_name); |
2672 | ||
1da177e4 LT |
2673 | return error; |
2674 | } | |
2675 | ||
2e4d0924 HC |
2676 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
2677 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2678 | { |
2ad94ae6 AV |
2679 | struct dentry *old_dir, *new_dir; |
2680 | struct dentry *old_dentry, *new_dentry; | |
2681 | struct dentry *trap; | |
1da177e4 | 2682 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
2683 | char *from; |
2684 | char *to; | |
2685 | int error; | |
1da177e4 | 2686 | |
2ad94ae6 | 2687 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
2688 | if (error) |
2689 | goto exit; | |
2690 | ||
2ad94ae6 | 2691 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
2692 | if (error) |
2693 | goto exit1; | |
2694 | ||
2695 | error = -EXDEV; | |
4ac91378 | 2696 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
2697 | goto exit2; |
2698 | ||
4ac91378 | 2699 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
2700 | error = -EBUSY; |
2701 | if (oldnd.last_type != LAST_NORM) | |
2702 | goto exit2; | |
2703 | ||
4ac91378 | 2704 | new_dir = newnd.path.dentry; |
1da177e4 LT |
2705 | if (newnd.last_type != LAST_NORM) |
2706 | goto exit2; | |
2707 | ||
0612d9fb OH |
2708 | oldnd.flags &= ~LOOKUP_PARENT; |
2709 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 2710 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 2711 | |
1da177e4 LT |
2712 | trap = lock_rename(new_dir, old_dir); |
2713 | ||
49705b77 | 2714 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
2715 | error = PTR_ERR(old_dentry); |
2716 | if (IS_ERR(old_dentry)) | |
2717 | goto exit3; | |
2718 | /* source must exist */ | |
2719 | error = -ENOENT; | |
2720 | if (!old_dentry->d_inode) | |
2721 | goto exit4; | |
2722 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
2723 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
2724 | error = -ENOTDIR; | |
2725 | if (oldnd.last.name[oldnd.last.len]) | |
2726 | goto exit4; | |
2727 | if (newnd.last.name[newnd.last.len]) | |
2728 | goto exit4; | |
2729 | } | |
2730 | /* source should not be ancestor of target */ | |
2731 | error = -EINVAL; | |
2732 | if (old_dentry == trap) | |
2733 | goto exit4; | |
49705b77 | 2734 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
2735 | error = PTR_ERR(new_dentry); |
2736 | if (IS_ERR(new_dentry)) | |
2737 | goto exit4; | |
2738 | /* target should not be an ancestor of source */ | |
2739 | error = -ENOTEMPTY; | |
2740 | if (new_dentry == trap) | |
2741 | goto exit5; | |
2742 | ||
9079b1eb DH |
2743 | error = mnt_want_write(oldnd.path.mnt); |
2744 | if (error) | |
2745 | goto exit5; | |
be6d3e56 KT |
2746 | error = security_path_rename(&oldnd.path, old_dentry, |
2747 | &newnd.path, new_dentry); | |
2748 | if (error) | |
2749 | goto exit6; | |
1da177e4 LT |
2750 | error = vfs_rename(old_dir->d_inode, old_dentry, |
2751 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 2752 | exit6: |
9079b1eb | 2753 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
2754 | exit5: |
2755 | dput(new_dentry); | |
2756 | exit4: | |
2757 | dput(old_dentry); | |
2758 | exit3: | |
2759 | unlock_rename(new_dir, old_dir); | |
2760 | exit2: | |
1d957f9b | 2761 | path_put(&newnd.path); |
2ad94ae6 | 2762 | putname(to); |
1da177e4 | 2763 | exit1: |
1d957f9b | 2764 | path_put(&oldnd.path); |
1da177e4 | 2765 | putname(from); |
2ad94ae6 | 2766 | exit: |
1da177e4 LT |
2767 | return error; |
2768 | } | |
2769 | ||
a26eab24 | 2770 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2771 | { |
2772 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
2773 | } | |
2774 | ||
1da177e4 LT |
2775 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2776 | { | |
2777 | int len; | |
2778 | ||
2779 | len = PTR_ERR(link); | |
2780 | if (IS_ERR(link)) | |
2781 | goto out; | |
2782 | ||
2783 | len = strlen(link); | |
2784 | if (len > (unsigned) buflen) | |
2785 | len = buflen; | |
2786 | if (copy_to_user(buffer, link, len)) | |
2787 | len = -EFAULT; | |
2788 | out: | |
2789 | return len; | |
2790 | } | |
2791 | ||
2792 | /* | |
2793 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
2794 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
2795 | * using) it for any given inode is up to filesystem. | |
2796 | */ | |
2797 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2798 | { | |
2799 | struct nameidata nd; | |
cc314eef | 2800 | void *cookie; |
694a1764 | 2801 | int res; |
cc314eef | 2802 | |
1da177e4 | 2803 | nd.depth = 0; |
cc314eef | 2804 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
2805 | if (IS_ERR(cookie)) |
2806 | return PTR_ERR(cookie); | |
2807 | ||
2808 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
2809 | if (dentry->d_inode->i_op->put_link) | |
2810 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
2811 | return res; | |
1da177e4 LT |
2812 | } |
2813 | ||
2814 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
2815 | { | |
2816 | return __vfs_follow_link(nd, link); | |
2817 | } | |
2818 | ||
2819 | /* get the link contents into pagecache */ | |
2820 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
2821 | { | |
ebd09abb DG |
2822 | char *kaddr; |
2823 | struct page *page; | |
1da177e4 | 2824 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 2825 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 2826 | if (IS_ERR(page)) |
6fe6900e | 2827 | return (char*)page; |
1da177e4 | 2828 | *ppage = page; |
ebd09abb DG |
2829 | kaddr = kmap(page); |
2830 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
2831 | return kaddr; | |
1da177e4 LT |
2832 | } |
2833 | ||
2834 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
2835 | { | |
2836 | struct page *page = NULL; | |
2837 | char *s = page_getlink(dentry, &page); | |
2838 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
2839 | if (page) { | |
2840 | kunmap(page); | |
2841 | page_cache_release(page); | |
2842 | } | |
2843 | return res; | |
2844 | } | |
2845 | ||
cc314eef | 2846 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 2847 | { |
cc314eef | 2848 | struct page *page = NULL; |
1da177e4 | 2849 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 2850 | return page; |
1da177e4 LT |
2851 | } |
2852 | ||
cc314eef | 2853 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 2854 | { |
cc314eef LT |
2855 | struct page *page = cookie; |
2856 | ||
2857 | if (page) { | |
1da177e4 LT |
2858 | kunmap(page); |
2859 | page_cache_release(page); | |
1da177e4 LT |
2860 | } |
2861 | } | |
2862 | ||
54566b2c NP |
2863 | /* |
2864 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
2865 | */ | |
2866 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
2867 | { |
2868 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 2869 | struct page *page; |
afddba49 | 2870 | void *fsdata; |
beb497ab | 2871 | int err; |
1da177e4 | 2872 | char *kaddr; |
54566b2c NP |
2873 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
2874 | if (nofs) | |
2875 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 2876 | |
7e53cac4 | 2877 | retry: |
afddba49 | 2878 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 2879 | flags, &page, &fsdata); |
1da177e4 | 2880 | if (err) |
afddba49 NP |
2881 | goto fail; |
2882 | ||
1da177e4 LT |
2883 | kaddr = kmap_atomic(page, KM_USER0); |
2884 | memcpy(kaddr, symname, len-1); | |
2885 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
2886 | |
2887 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
2888 | page, fsdata); | |
1da177e4 LT |
2889 | if (err < 0) |
2890 | goto fail; | |
afddba49 NP |
2891 | if (err < len-1) |
2892 | goto retry; | |
2893 | ||
1da177e4 LT |
2894 | mark_inode_dirty(inode); |
2895 | return 0; | |
1da177e4 LT |
2896 | fail: |
2897 | return err; | |
2898 | } | |
2899 | ||
0adb25d2 KK |
2900 | int page_symlink(struct inode *inode, const char *symname, int len) |
2901 | { | |
2902 | return __page_symlink(inode, symname, len, | |
54566b2c | 2903 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
2904 | } |
2905 | ||
92e1d5be | 2906 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
2907 | .readlink = generic_readlink, |
2908 | .follow_link = page_follow_link_light, | |
2909 | .put_link = page_put_link, | |
2910 | }; | |
2911 | ||
2d8f3038 | 2912 | EXPORT_SYMBOL(user_path_at); |
1da177e4 LT |
2913 | EXPORT_SYMBOL(follow_down); |
2914 | EXPORT_SYMBOL(follow_up); | |
2915 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
2916 | EXPORT_SYMBOL(getname); | |
2917 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
2918 | EXPORT_SYMBOL(lookup_one_len); |
2919 | EXPORT_SYMBOL(page_follow_link_light); | |
2920 | EXPORT_SYMBOL(page_put_link); | |
2921 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 2922 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
2923 | EXPORT_SYMBOL(page_symlink); |
2924 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
2925 | EXPORT_SYMBOL(path_lookup); | |
d1811465 | 2926 | EXPORT_SYMBOL(kern_path); |
16f18200 | 2927 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 2928 | EXPORT_SYMBOL(inode_permission); |
8c744fb8 | 2929 | EXPORT_SYMBOL(file_permission); |
1da177e4 LT |
2930 | EXPORT_SYMBOL(unlock_rename); |
2931 | EXPORT_SYMBOL(vfs_create); | |
2932 | EXPORT_SYMBOL(vfs_follow_link); | |
2933 | EXPORT_SYMBOL(vfs_link); | |
2934 | EXPORT_SYMBOL(vfs_mkdir); | |
2935 | EXPORT_SYMBOL(vfs_mknod); | |
2936 | EXPORT_SYMBOL(generic_permission); | |
2937 | EXPORT_SYMBOL(vfs_readlink); | |
2938 | EXPORT_SYMBOL(vfs_rename); | |
2939 | EXPORT_SYMBOL(vfs_rmdir); | |
2940 | EXPORT_SYMBOL(vfs_symlink); | |
2941 | EXPORT_SYMBOL(vfs_unlink); | |
2942 | EXPORT_SYMBOL(dentry_unhash); | |
2943 | EXPORT_SYMBOL(generic_readlink); |