blob: 24896e8335658c9c0ce2c81c117cb664b964da70 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/pagemap.h>
Robert Love0eeca282005-07-12 17:06:03 -040023#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/personality.h>
25#include <linux/security.h>
Mimi Zohar6146f0d2009-02-04 09:06:57 -050026#include <linux/ima.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/syscalls.h>
28#include <linux/mount.h>
29#include <linux/audit.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080030#include <linux/capability.h>
Trond Myklebust834f2a42005-10-18 14:20:16 -070031#include <linux/file.h>
Ulrich Drepper5590ff02006-01-18 17:43:53 -080032#include <linux/fcntl.h>
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -070033#include <linux/device_cgroup.h>
Al Viro5ad4e532009-03-29 19:50:06 -040034#include <linux/fs_struct.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <asm/uaccess.h>
36
Eric Parise81e3f42009-12-04 15:47:36 -050037#include "internal.h"
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039/* [Feb-1997 T. Schoebel-Theuer]
40 * Fundamental changes in the pathname lookup mechanisms (namei)
41 * were necessary because of omirr. The reason is that omirr needs
42 * to know the _real_ pathname, not the user-supplied one, in case
43 * of symlinks (and also when transname replacements occur).
44 *
45 * The new code replaces the old recursive symlink resolution with
46 * an iterative one (in case of non-nested symlink chains). It does
47 * this with calls to <fs>_follow_link().
48 * As a side effect, dir_namei(), _namei() and follow_link() are now
49 * replaced with a single function lookup_dentry() that can handle all
50 * the special cases of the former code.
51 *
52 * With the new dcache, the pathname is stored at each inode, at least as
53 * long as the refcount of the inode is positive. As a side effect, the
54 * size of the dcache depends on the inode cache and thus is dynamic.
55 *
56 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
57 * resolution to correspond with current state of the code.
58 *
59 * Note that the symlink resolution is not *completely* iterative.
60 * There is still a significant amount of tail- and mid- recursion in
61 * the algorithm. Also, note that <fs>_readlink() is not used in
62 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
63 * may return different results than <fs>_follow_link(). Many virtual
64 * filesystems (including /proc) exhibit this behavior.
65 */
66
67/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
68 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
69 * and the name already exists in form of a symlink, try to create the new
70 * name indicated by the symlink. The old code always complained that the
71 * name already exists, due to not following the symlink even if its target
72 * is nonexistent. The new semantics affects also mknod() and link() when
73 * the name is a symlink pointing to a non-existant name.
74 *
75 * I don't know which semantics is the right one, since I have no access
76 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
77 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
78 * "old" one. Personally, I think the new semantics is much more logical.
79 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
80 * file does succeed in both HP-UX and SunOs, but not in Solaris
81 * and in the old Linux semantics.
82 */
83
84/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
85 * semantics. See the comments in "open_namei" and "do_link" below.
86 *
87 * [10-Sep-98 Alan Modra] Another symlink change.
88 */
89
90/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
91 * inside the path - always follow.
92 * in the last component in creation/removal/renaming - never follow.
93 * if LOOKUP_FOLLOW passed - follow.
94 * if the pathname has trailing slashes - follow.
95 * otherwise - don't follow.
96 * (applied in that order).
97 *
98 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
99 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
100 * During the 2.4 we need to fix the userland stuff depending on it -
101 * hopefully we will be able to get rid of that wart in 2.5. So far only
102 * XEmacs seems to be relying on it...
103 */
104/*
105 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
Arjan van de Vena11f3a02006-03-23 03:00:33 -0800106 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 * any extra contention...
108 */
109
110/* In order to reduce some races, while at the same time doing additional
111 * checking and hopefully speeding things up, we copy filenames to the
112 * kernel data space before using them..
113 *
114 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
115 * PATH_MAX includes the nul terminator --RR.
116 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800117static int do_getname(const char __user *filename, char *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118{
119 int retval;
120 unsigned long len = PATH_MAX;
121
122 if (!segment_eq(get_fs(), KERNEL_DS)) {
123 if ((unsigned long) filename >= TASK_SIZE)
124 return -EFAULT;
125 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
126 len = TASK_SIZE - (unsigned long) filename;
127 }
128
129 retval = strncpy_from_user(page, filename, len);
130 if (retval > 0) {
131 if (retval < len)
132 return 0;
133 return -ENAMETOOLONG;
134 } else if (!retval)
135 retval = -ENOENT;
136 return retval;
137}
138
139char * getname(const char __user * filename)
140{
141 char *tmp, *result;
142
143 result = ERR_PTR(-ENOMEM);
144 tmp = __getname();
145 if (tmp) {
146 int retval = do_getname(filename, tmp);
147
148 result = tmp;
149 if (retval < 0) {
150 __putname(tmp);
151 result = ERR_PTR(retval);
152 }
153 }
154 audit_getname(result);
155 return result;
156}
157
158#ifdef CONFIG_AUDITSYSCALL
159void putname(const char *name)
160{
Al Viro5ac3a9c2006-07-16 06:38:45 -0400161 if (unlikely(!audit_dummy_context()))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 audit_putname(name);
163 else
164 __putname(name);
165}
166EXPORT_SYMBOL(putname);
167#endif
168
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700169/*
170 * This does basic POSIX ACL permission checking
171 */
172static int acl_permission_check(struct inode *inode, int mask,
173 int (*check_acl)(struct inode *inode, int mask))
174{
175 umode_t mode = inode->i_mode;
176
177 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
178
179 if (current_fsuid() == inode->i_uid)
180 mode >>= 6;
181 else {
182 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
183 int error = check_acl(inode, mask);
184 if (error != -EAGAIN)
185 return error;
186 }
187
188 if (in_group_p(inode->i_gid))
189 mode >>= 3;
190 }
191
192 /*
193 * If the DACs are ok we don't need any capability check.
194 */
195 if ((mask & ~mode) == 0)
196 return 0;
197 return -EACCES;
198}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
200/**
201 * generic_permission - check for access rights on a Posix-like filesystem
202 * @inode: inode to check access rights for
203 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
204 * @check_acl: optional callback to check for Posix ACLs
205 *
206 * Used to check for read/write/execute permissions on a file.
207 * We use "fsuid" for this, letting us set arbitrary permissions
208 * for filesystem access without changing the "normal" uids which
209 * are used for other things..
210 */
211int generic_permission(struct inode *inode, int mask,
212 int (*check_acl)(struct inode *inode, int mask))
213{
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700214 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
216 /*
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700217 * Do the basic POSIX ACL permission checks.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 */
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700219 ret = acl_permission_check(inode, mask, check_acl);
220 if (ret != -EACCES)
221 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 /*
224 * Read/write DACs are always overridable.
225 * Executable DACs are overridable if at least one exec bit is set.
226 */
Miklos Szeredif696a362008-07-31 13:41:58 +0200227 if (!(mask & MAY_EXEC) || execute_ok(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 if (capable(CAP_DAC_OVERRIDE))
229 return 0;
230
231 /*
232 * Searching includes executable on directories, else just read.
233 */
Serge E. Hallyn7ea66002009-12-29 14:50:19 -0600234 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 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
Christoph Hellwigcb23beb2008-10-24 09:59:29 +0200242/**
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 */
Al Virof419a2e2008-07-22 00:07:17 -0400252int inode_permission(struct inode *inode, int mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253{
Al Viroe6305c42008-07-15 21:03:57 -0400254 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
256 if (mask & MAY_WRITE) {
Miklos Szeredi22590e42007-10-16 23:27:08 -0700257 umode_t mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
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
Al Viroacfa4382008-12-04 10:06:33 -0500273 if (inode->i_op->permission)
Al Virob77b0642008-07-17 09:37:02 -0400274 retval = inode->i_op->permission(inode, mask);
Miklos Szeredif696a362008-07-31 13:41:58 +0200275 else
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700276 retval = generic_permission(inode, mask, inode->i_op->check_acl);
Miklos Szeredif696a362008-07-31 13:41:58 +0200277
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 if (retval)
279 return retval;
280
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -0700281 retval = devcgroup_inode_permission(inode, mask);
282 if (retval)
283 return retval;
284
Eric Parisd09ca732010-07-23 11:43:57 -0400285 return security_inode_permission(inode, mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286}
287
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800288/**
Christoph Hellwig8c744fb2005-11-08 21:35:04 -0800289 * file_permission - check for additional access rights to a given file
290 * @file: file to check access rights for
291 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
292 *
293 * Used to check for read/write/execute permissions on an already opened
294 * file.
295 *
296 * Note:
297 * Do not use this function in new code. All access checks should
Christoph Hellwigcb23beb2008-10-24 09:59:29 +0200298 * be done using inode_permission().
Christoph Hellwig8c744fb2005-11-08 21:35:04 -0800299 */
300int file_permission(struct file *file, int mask)
301{
Al Virof419a2e2008-07-22 00:07:17 -0400302 return inode_permission(file->f_path.dentry->d_inode, mask);
Christoph Hellwig8c744fb2005-11-08 21:35:04 -0800303}
304
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305/*
306 * get_write_access() gets write permission for a file.
307 * put_write_access() releases this write permission.
308 * This is used for regular files.
309 * We cannot support write (and maybe mmap read-write shared) accesses and
310 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
311 * can have the following values:
312 * 0: no writers, no VM_DENYWRITE mappings
313 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
314 * > 0: (i_writecount) users are writing to the file.
315 *
316 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
317 * except for the cases where we don't hold i_writecount yet. Then we need to
318 * use {get,deny}_write_access() - these functions check the sign and refuse
319 * to do the change if sign is wrong. Exclusion between them is provided by
320 * the inode->i_lock spinlock.
321 */
322
323int get_write_access(struct inode * inode)
324{
325 spin_lock(&inode->i_lock);
326 if (atomic_read(&inode->i_writecount) < 0) {
327 spin_unlock(&inode->i_lock);
328 return -ETXTBSY;
329 }
330 atomic_inc(&inode->i_writecount);
331 spin_unlock(&inode->i_lock);
332
333 return 0;
334}
335
336int deny_write_access(struct file * file)
337{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800338 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339
340 spin_lock(&inode->i_lock);
341 if (atomic_read(&inode->i_writecount) > 0) {
342 spin_unlock(&inode->i_lock);
343 return -ETXTBSY;
344 }
345 atomic_dec(&inode->i_writecount);
346 spin_unlock(&inode->i_lock);
347
348 return 0;
349}
350
Jan Blunck1d957f92008-02-14 19:34:35 -0800351/**
Jan Blunck5dd784d02008-02-14 19:34:38 -0800352 * path_get - get a reference to a path
353 * @path: path to get the reference to
354 *
355 * Given a path increment the reference count to the dentry and the vfsmount.
356 */
357void path_get(struct path *path)
358{
359 mntget(path->mnt);
360 dget(path->dentry);
361}
362EXPORT_SYMBOL(path_get);
363
364/**
Jan Blunck1d957f92008-02-14 19:34:35 -0800365 * path_put - put a reference to a path
366 * @path: path to put the reference to
367 *
368 * Given a path decrement the reference count to the dentry and the vfsmount.
369 */
370void path_put(struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371{
Jan Blunck1d957f92008-02-14 19:34:35 -0800372 dput(path->dentry);
373 mntput(path->mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374}
Jan Blunck1d957f92008-02-14 19:34:35 -0800375EXPORT_SYMBOL(path_put);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
Trond Myklebust834f2a42005-10-18 14:20:16 -0700377/**
378 * release_open_intent - free up open intent resources
379 * @nd: pointer to nameidata
380 */
381void release_open_intent(struct nameidata *nd)
382{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800383 if (nd->intent.open.file->f_path.dentry == NULL)
Trond Myklebust834f2a42005-10-18 14:20:16 -0700384 put_filp(nd->intent.open.file);
385 else
386 fput(nd->intent.open.file);
387}
388
Ian Kentbcdc5e02006-09-27 01:50:44 -0700389static inline struct dentry *
390do_revalidate(struct dentry *dentry, struct nameidata *nd)
391{
392 int status = dentry->d_op->d_revalidate(dentry, nd);
393 if (unlikely(status <= 0)) {
394 /*
395 * The dentry failed validation.
396 * If d_revalidate returned 0 attempt to invalidate
397 * the dentry otherwise d_revalidate is asking us
398 * to return a fail status.
399 */
400 if (!status) {
401 if (!d_invalidate(dentry)) {
402 dput(dentry);
403 dentry = NULL;
404 }
405 } else {
406 dput(dentry);
407 dentry = ERR_PTR(status);
408 }
409 }
410 return dentry;
411}
412
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413/*
Jeff Layton39159de2009-12-07 12:01:50 -0500414 * force_reval_path - force revalidation of a dentry
415 *
416 * In some situations the path walking code will trust dentries without
417 * revalidating them. This causes problems for filesystems that depend on
418 * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
419 * (which indicates that it's possible for the dentry to go stale), force
420 * a d_revalidate call before proceeding.
421 *
422 * Returns 0 if the revalidation was successful. If the revalidation fails,
423 * either return the error returned by d_revalidate or -ESTALE if the
424 * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
425 * invalidate the dentry. It's up to the caller to handle putting references
426 * to the path if necessary.
427 */
428static int
429force_reval_path(struct path *path, struct nameidata *nd)
430{
431 int status;
432 struct dentry *dentry = path->dentry;
433
434 /*
435 * only check on filesystems where it's possible for the dentry to
436 * become stale. It's assumed that if this flag is set then the
437 * d_revalidate op will also be defined.
438 */
439 if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
440 return 0;
441
442 status = dentry->d_op->d_revalidate(dentry, nd);
443 if (status > 0)
444 return 0;
445
446 if (!status) {
447 d_invalidate(dentry);
448 status = -ESTALE;
449 }
450 return status;
451}
452
453/*
Al Virob75b5082009-12-16 01:01:38 -0500454 * Short-cut version of permission(), for calling on directories
455 * during pathname resolution. Combines parts of permission()
456 * and generic_permission(), and tests ONLY for MAY_EXEC permission.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 *
458 * If appropriate, check DAC only. If not appropriate, or
Al Virob75b5082009-12-16 01:01:38 -0500459 * short-cut DAC fails, then call ->permission() to do more
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 * complete permission check.
461 */
Al Virob75b5082009-12-16 01:01:38 -0500462static int exec_permission(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463{
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700464 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465
Linus Torvaldscb9179e2009-08-28 11:08:31 -0700466 if (inode->i_op->permission) {
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700467 ret = inode->i_op->permission(inode, MAY_EXEC);
Linus Torvaldscb9179e2009-08-28 11:08:31 -0700468 if (!ret)
469 goto ok;
470 return ret;
471 }
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700472 ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl);
473 if (!ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 goto ok;
475
Linus Torvaldsf1ac9f62009-08-28 10:53:56 -0700476 if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 goto ok;
478
Linus Torvalds5909ccaa2009-08-28 11:51:25 -0700479 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480ok:
Al Virob77b0642008-07-17 09:37:02 -0400481 return security_inode_permission(inode, MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482}
483
Al Viro2a737872009-04-07 11:49:53 -0400484static __always_inline void set_root(struct nameidata *nd)
485{
Miklos Szeredif7ad3c62010-08-10 11:41:36 +0200486 if (!nd->root.mnt)
487 get_fs_root(current->fs, &nd->root);
Al Viro2a737872009-04-07 11:49:53 -0400488}
489
Al Viro6de88d72009-08-09 01:41:57 +0400490static int link_path_walk(const char *, struct nameidata *);
491
Arjan van de Venf1662352006-01-14 13:21:31 -0800492static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 if (IS_ERR(link))
495 goto fail;
496
497 if (*link == '/') {
Al Viro2a737872009-04-07 11:49:53 -0400498 set_root(nd);
Jan Blunck1d957f92008-02-14 19:34:35 -0800499 path_put(&nd->path);
Al Viro2a737872009-04-07 11:49:53 -0400500 nd->path = nd->root;
501 path_get(&nd->root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 }
Christoph Hellwigb4091d52008-11-05 15:07:21 +0100503
Al Virodef4af32009-12-26 08:37:05 -0500504 return link_path_walk(link, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505fail:
Jan Blunck1d957f92008-02-14 19:34:35 -0800506 path_put(&nd->path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 return PTR_ERR(link);
508}
509
Jan Blunck1d957f92008-02-14 19:34:35 -0800510static void path_put_conditional(struct path *path, struct nameidata *nd)
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700511{
512 dput(path->dentry);
Jan Blunck4ac91372008-02-14 19:34:32 -0800513 if (path->mnt != nd->path.mnt)
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700514 mntput(path->mnt);
515}
516
517static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
518{
Jan Blunck4ac91372008-02-14 19:34:32 -0800519 dput(nd->path.dentry);
Huang Shijie9a229682010-04-02 17:37:13 +0800520 if (nd->path.mnt != path->mnt) {
Jan Blunck4ac91372008-02-14 19:34:32 -0800521 mntput(nd->path.mnt);
Huang Shijie9a229682010-04-02 17:37:13 +0800522 nd->path.mnt = path->mnt;
523 }
Jan Blunck4ac91372008-02-14 19:34:32 -0800524 nd->path.dentry = path->dentry;
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700525}
526
Al Virodef4af32009-12-26 08:37:05 -0500527static __always_inline int
528__do_follow_link(struct path *path, struct nameidata *nd, void **p)
Ian Kent051d3812006-03-27 01:14:53 -0800529{
530 int error;
Ian Kent051d3812006-03-27 01:14:53 -0800531 struct dentry *dentry = path->dentry;
532
533 touch_atime(path->mnt, dentry);
534 nd_set_link(nd, NULL);
535
Jan Blunck4ac91372008-02-14 19:34:32 -0800536 if (path->mnt != nd->path.mnt) {
Ian Kent051d3812006-03-27 01:14:53 -0800537 path_to_nameidata(path, nd);
538 dget(dentry);
539 }
540 mntget(path->mnt);
Al Viro86acdca12009-12-22 23:45:11 -0500541 nd->last_type = LAST_BIND;
Al Virodef4af32009-12-26 08:37:05 -0500542 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
543 error = PTR_ERR(*p);
544 if (!IS_ERR(*p)) {
Ian Kent051d3812006-03-27 01:14:53 -0800545 char *s = nd_get_link(nd);
546 error = 0;
547 if (s)
548 error = __vfs_follow_link(nd, s);
Jeff Layton39159de2009-12-07 12:01:50 -0500549 else if (nd->last_type == LAST_BIND) {
550 error = force_reval_path(&nd->path, nd);
551 if (error)
552 path_put(&nd->path);
553 }
Ian Kent051d3812006-03-27 01:14:53 -0800554 }
Ian Kent051d3812006-03-27 01:14:53 -0800555 return error;
556}
557
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558/*
559 * This limits recursive symlink follows to 8, while
560 * limiting consecutive symlinks to 40.
561 *
562 * Without that kind of total limit, nasty chains of consecutive
563 * symlinks can cause almost arbitrarily long lookups.
564 */
Al Viro90ebe562005-06-06 13:35:58 -0700565static inline int do_follow_link(struct path *path, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566{
Al Virodef4af32009-12-26 08:37:05 -0500567 void *cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 int err = -ELOOP;
569 if (current->link_count >= MAX_NESTED_LINKS)
570 goto loop;
571 if (current->total_link_count >= 40)
572 goto loop;
573 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
574 cond_resched();
Al Viro90ebe562005-06-06 13:35:58 -0700575 err = security_inode_follow_link(path->dentry, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 if (err)
577 goto loop;
578 current->link_count++;
579 current->total_link_count++;
580 nd->depth++;
Al Virodef4af32009-12-26 08:37:05 -0500581 err = __do_follow_link(path, nd, &cookie);
582 if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link)
583 path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie);
Al Viro258fa992009-08-09 01:32:02 +0400584 path_put(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 current->link_count--;
586 nd->depth--;
587 return err;
588loop:
Jan Blunck1d957f92008-02-14 19:34:35 -0800589 path_put_conditional(path, nd);
590 path_put(&nd->path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 return err;
592}
593
Al Virobab77eb2009-04-18 03:26:48 -0400594int follow_up(struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595{
596 struct vfsmount *parent;
597 struct dentry *mountpoint;
Nick Piggin99b7db72010-08-18 04:37:39 +1000598
599 br_read_lock(vfsmount_lock);
Al Virobab77eb2009-04-18 03:26:48 -0400600 parent = path->mnt->mnt_parent;
601 if (parent == path->mnt) {
Nick Piggin99b7db72010-08-18 04:37:39 +1000602 br_read_unlock(vfsmount_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 return 0;
604 }
605 mntget(parent);
Al Virobab77eb2009-04-18 03:26:48 -0400606 mountpoint = dget(path->mnt->mnt_mountpoint);
Nick Piggin99b7db72010-08-18 04:37:39 +1000607 br_read_unlock(vfsmount_lock);
Al Virobab77eb2009-04-18 03:26:48 -0400608 dput(path->dentry);
609 path->dentry = mountpoint;
610 mntput(path->mnt);
611 path->mnt = parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 return 1;
613}
614
615/* no need for dcache_lock, as serialization is taken care in
616 * namespace.c
617 */
Al Viro463ffb22005-06-06 13:36:05 -0700618static int __follow_mount(struct path *path)
619{
620 int res = 0;
621 while (d_mountpoint(path->dentry)) {
Al Viro1c755af2009-04-18 14:06:57 -0400622 struct vfsmount *mounted = lookup_mnt(path);
Al Viro463ffb22005-06-06 13:36:05 -0700623 if (!mounted)
624 break;
625 dput(path->dentry);
626 if (res)
627 mntput(path->mnt);
628 path->mnt = mounted;
629 path->dentry = dget(mounted->mnt_root);
630 res = 1;
631 }
632 return res;
633}
634
Al Viro79ed0222009-04-18 13:59:41 -0400635static void follow_mount(struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636{
Al Viro79ed0222009-04-18 13:59:41 -0400637 while (d_mountpoint(path->dentry)) {
Al Viro1c755af2009-04-18 14:06:57 -0400638 struct vfsmount *mounted = lookup_mnt(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 if (!mounted)
640 break;
Al Viro79ed0222009-04-18 13:59:41 -0400641 dput(path->dentry);
642 mntput(path->mnt);
643 path->mnt = mounted;
644 path->dentry = dget(mounted->mnt_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646}
647
648/* no need for dcache_lock, as serialization is taken care in
649 * namespace.c
650 */
Al Viro9393bd02009-04-18 13:58:15 -0400651int follow_down(struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652{
653 struct vfsmount *mounted;
654
Al Viro1c755af2009-04-18 14:06:57 -0400655 mounted = lookup_mnt(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 if (mounted) {
Al Viro9393bd02009-04-18 13:58:15 -0400657 dput(path->dentry);
658 mntput(path->mnt);
659 path->mnt = mounted;
660 path->dentry = dget(mounted->mnt_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 return 1;
662 }
663 return 0;
664}
665
Arjan van de Venf1662352006-01-14 13:21:31 -0800666static __always_inline void follow_dotdot(struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667{
Al Viro2a737872009-04-07 11:49:53 -0400668 set_root(nd);
Andreas Mohre518ddb2006-09-29 02:01:22 -0700669
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 while(1) {
Jan Blunck4ac91372008-02-14 19:34:32 -0800671 struct dentry *old = nd->path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672
Al Viro2a737872009-04-07 11:49:53 -0400673 if (nd->path.dentry == nd->root.dentry &&
674 nd->path.mnt == nd->root.mnt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 break;
676 }
Jan Blunck4ac91372008-02-14 19:34:32 -0800677 if (nd->path.dentry != nd->path.mnt->mnt_root) {
Al Viro3088dd72010-01-30 15:47:29 -0500678 /* rare case of legitimate dget_parent()... */
679 nd->path.dentry = dget_parent(nd->path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 dput(old);
681 break;
682 }
Al Viro3088dd72010-01-30 15:47:29 -0500683 if (!follow_up(&nd->path))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 }
Al Viro79ed0222009-04-18 13:59:41 -0400686 follow_mount(&nd->path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687}
688
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689/*
Nick Pigginbaa03892010-08-18 04:37:31 +1000690 * Allocate a dentry with name and parent, and perform a parent
691 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
692 * on error. parent->d_inode->i_mutex must be held. d_lookup must
693 * have verified that no child exists while under i_mutex.
694 */
695static struct dentry *d_alloc_and_lookup(struct dentry *parent,
696 struct qstr *name, struct nameidata *nd)
697{
698 struct inode *inode = parent->d_inode;
699 struct dentry *dentry;
700 struct dentry *old;
701
702 /* Don't create child dentry for a dead directory. */
703 if (unlikely(IS_DEADDIR(inode)))
704 return ERR_PTR(-ENOENT);
705
706 dentry = d_alloc(parent, name);
707 if (unlikely(!dentry))
708 return ERR_PTR(-ENOMEM);
709
710 old = inode->i_op->lookup(inode, dentry, nd);
711 if (unlikely(old)) {
712 dput(dentry);
713 dentry = old;
714 }
715 return dentry;
716}
717
718/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 * It's more convoluted than I'd like it to be, but... it's still fairly
720 * small and for now I'd prefer to have fast path as straight as possible.
721 * It _is_ time-critical.
722 */
723static int do_lookup(struct nameidata *nd, struct qstr *name,
724 struct path *path)
725{
Jan Blunck4ac91372008-02-14 19:34:32 -0800726 struct vfsmount *mnt = nd->path.mnt;
Al Viro6e6b1bd2009-08-13 23:38:37 +0400727 struct dentry *dentry, *parent;
728 struct inode *dir;
Al Viro3cac2602009-08-13 18:27:43 +0400729 /*
730 * See if the low-level filesystem might want
731 * to use its own hash..
732 */
733 if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
734 int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name);
735 if (err < 0)
736 return err;
737 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738
Nick Pigginb04f7842010-08-18 04:37:34 +1000739 /*
740 * Rename seqlock is not required here because in the off chance
741 * of a false negative due to a concurrent rename, we're going to
742 * do the non-racy lookup, below.
743 */
Al Viro3cac2602009-08-13 18:27:43 +0400744 dentry = __d_lookup(nd->path.dentry, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 if (!dentry)
746 goto need_lookup;
Nick Piggin2e2e88e2010-08-18 04:37:30 +1000747found:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 if (dentry->d_op && dentry->d_op->d_revalidate)
749 goto need_revalidate;
750done:
751 path->mnt = mnt;
752 path->dentry = dentry;
Al Viro634ee702005-06-06 13:36:13 -0700753 __follow_mount(path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 return 0;
755
756need_lookup:
Al Viro6e6b1bd2009-08-13 23:38:37 +0400757 parent = nd->path.dentry;
758 dir = parent->d_inode;
759
760 mutex_lock(&dir->i_mutex);
761 /*
762 * First re-do the cached lookup just in case it was created
Nick Pigginb04f7842010-08-18 04:37:34 +1000763 * while we waited for the directory semaphore, or the first
764 * lookup failed due to an unrelated rename.
Al Viro6e6b1bd2009-08-13 23:38:37 +0400765 *
Nick Pigginb04f7842010-08-18 04:37:34 +1000766 * This could use version numbering or similar to avoid unnecessary
767 * cache lookups, but then we'd have to do the first lookup in the
768 * non-racy way. However in the common case here, everything should
769 * be hot in cache, so would it be a big win?
Al Viro6e6b1bd2009-08-13 23:38:37 +0400770 */
771 dentry = d_lookup(parent, name);
Nick Pigginbaa03892010-08-18 04:37:31 +1000772 if (likely(!dentry)) {
773 dentry = d_alloc_and_lookup(parent, name, nd);
Al Viro6e6b1bd2009-08-13 23:38:37 +0400774 mutex_unlock(&dir->i_mutex);
775 if (IS_ERR(dentry))
776 goto fail;
777 goto done;
778 }
Al Viro6e6b1bd2009-08-13 23:38:37 +0400779 /*
780 * Uhhuh! Nasty case: the cache was re-populated while
781 * we waited on the semaphore. Need to revalidate.
782 */
783 mutex_unlock(&dir->i_mutex);
Nick Piggin2e2e88e2010-08-18 04:37:30 +1000784 goto found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785
786need_revalidate:
Ian Kentbcdc5e02006-09-27 01:50:44 -0700787 dentry = do_revalidate(dentry, nd);
788 if (!dentry)
789 goto need_lookup;
790 if (IS_ERR(dentry))
791 goto fail;
792 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793
794fail:
795 return PTR_ERR(dentry);
796}
797
798/*
Al Viroac278a92010-02-16 18:09:36 +0000799 * This is a temporary kludge to deal with "automount" symlinks; proper
800 * solution is to trigger them on follow_mount(), so that do_lookup()
801 * would DTRT. To be killed before 2.6.34-final.
802 */
803static inline int follow_on_final(struct inode *inode, unsigned lookup_flags)
804{
805 return inode && unlikely(inode->i_op->follow_link) &&
806 ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode));
807}
808
809/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 * Name resolution.
Prasanna Medaea3834d2005-04-29 16:00:17 +0100811 * This is the basic name resolution function, turning a pathname into
812 * the final dentry. We expect 'base' to be positive and a directory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 *
Prasanna Medaea3834d2005-04-29 16:00:17 +0100814 * Returns 0 and nd will have valid dentry and mnt on success.
815 * Returns error and drops reference to input namei data on failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 */
Al Viro6de88d72009-08-09 01:41:57 +0400817static int link_path_walk(const char *name, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818{
819 struct path next;
820 struct inode *inode;
821 int err;
822 unsigned int lookup_flags = nd->flags;
823
824 while (*name=='/')
825 name++;
826 if (!*name)
827 goto return_reval;
828
Jan Blunck4ac91372008-02-14 19:34:32 -0800829 inode = nd->path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 if (nd->depth)
Trond Myklebustf55eab82006-02-04 23:28:01 -0800831 lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832
833 /* At this point we know we have a real path component. */
834 for(;;) {
835 unsigned long hash;
836 struct qstr this;
837 unsigned int c;
838
Trond Myklebustcdce5d62005-10-18 14:20:18 -0700839 nd->flags |= LOOKUP_CONTINUE;
Al Virob75b5082009-12-16 01:01:38 -0500840 err = exec_permission(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 if (err)
842 break;
843
844 this.name = name;
845 c = *(const unsigned char *)name;
846
847 hash = init_name_hash();
848 do {
849 name++;
850 hash = partial_name_hash(c, hash);
851 c = *(const unsigned char *)name;
852 } while (c && (c != '/'));
853 this.len = name - (const char *) this.name;
854 this.hash = end_name_hash(hash);
855
856 /* remove trailing slashes? */
857 if (!c)
858 goto last_component;
859 while (*++name == '/');
860 if (!*name)
861 goto last_with_slashes;
862
863 /*
864 * "." and ".." are special - ".." especially so because it has
865 * to be able to know about the current root directory and
866 * parent relationships.
867 */
868 if (this.name[0] == '.') switch (this.len) {
869 default:
870 break;
871 case 2:
872 if (this.name[1] != '.')
873 break;
Al Viro58c465e2005-06-06 13:36:13 -0700874 follow_dotdot(nd);
Jan Blunck4ac91372008-02-14 19:34:32 -0800875 inode = nd->path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 /* fallthrough */
877 case 1:
878 continue;
879 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 /* This does the actual lookups.. */
881 err = do_lookup(nd, &this, &next);
882 if (err)
883 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884
885 err = -ENOENT;
886 inode = next.dentry->d_inode;
887 if (!inode)
888 goto out_dput;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889
890 if (inode->i_op->follow_link) {
Al Viro90ebe562005-06-06 13:35:58 -0700891 err = do_follow_link(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 if (err)
893 goto return_err;
894 err = -ENOENT;
Jan Blunck4ac91372008-02-14 19:34:32 -0800895 inode = nd->path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 if (!inode)
897 break;
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700898 } else
899 path_to_nameidata(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 err = -ENOTDIR;
901 if (!inode->i_op->lookup)
902 break;
903 continue;
904 /* here ends the main loop */
905
906last_with_slashes:
907 lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
908last_component:
Trond Myklebustf55eab82006-02-04 23:28:01 -0800909 /* Clear LOOKUP_CONTINUE iff it was previously unset */
910 nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 if (lookup_flags & LOOKUP_PARENT)
912 goto lookup_parent;
913 if (this.name[0] == '.') switch (this.len) {
914 default:
915 break;
916 case 2:
917 if (this.name[1] != '.')
918 break;
Al Viro58c465e2005-06-06 13:36:13 -0700919 follow_dotdot(nd);
Jan Blunck4ac91372008-02-14 19:34:32 -0800920 inode = nd->path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 /* fallthrough */
922 case 1:
923 goto return_reval;
924 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 err = do_lookup(nd, &this, &next);
926 if (err)
927 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 inode = next.dentry->d_inode;
Al Viroac278a92010-02-16 18:09:36 +0000929 if (follow_on_final(inode, lookup_flags)) {
Al Viro90ebe562005-06-06 13:35:58 -0700930 err = do_follow_link(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 if (err)
932 goto return_err;
Jan Blunck4ac91372008-02-14 19:34:32 -0800933 inode = nd->path.dentry->d_inode;
Miklos Szeredi09dd17d2005-09-06 15:18:21 -0700934 } else
935 path_to_nameidata(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 err = -ENOENT;
937 if (!inode)
938 break;
939 if (lookup_flags & LOOKUP_DIRECTORY) {
940 err = -ENOTDIR;
Al Viroacfa4382008-12-04 10:06:33 -0500941 if (!inode->i_op->lookup)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 break;
943 }
944 goto return_base;
945lookup_parent:
946 nd->last = this;
947 nd->last_type = LAST_NORM;
948 if (this.name[0] != '.')
949 goto return_base;
950 if (this.len == 1)
951 nd->last_type = LAST_DOT;
952 else if (this.len == 2 && this.name[1] == '.')
953 nd->last_type = LAST_DOTDOT;
954 else
955 goto return_base;
956return_reval:
957 /*
958 * We bypassed the ordinary revalidation routines.
959 * We may need to check the cached dentry for staleness.
960 */
Jan Blunck4ac91372008-02-14 19:34:32 -0800961 if (nd->path.dentry && nd->path.dentry->d_sb &&
962 (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 err = -ESTALE;
964 /* Note: we do not d_invalidate() */
Jan Blunck4ac91372008-02-14 19:34:32 -0800965 if (!nd->path.dentry->d_op->d_revalidate(
966 nd->path.dentry, nd))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 break;
968 }
969return_base:
970 return 0;
971out_dput:
Jan Blunck1d957f92008-02-14 19:34:35 -0800972 path_put_conditional(&next, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 break;
974 }
Jan Blunck1d957f92008-02-14 19:34:35 -0800975 path_put(&nd->path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976return_err:
977 return err;
978}
979
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -0800980static int path_walk(const char *name, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981{
Al Viro6de88d72009-08-09 01:41:57 +0400982 struct path save = nd->path;
983 int result;
984
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 current->total_link_count = 0;
Al Viro6de88d72009-08-09 01:41:57 +0400986
987 /* make sure the stuff we saved doesn't go away */
988 path_get(&save);
989
990 result = link_path_walk(name, nd);
991 if (result == -ESTALE) {
992 /* nd->path had been dropped */
993 current->total_link_count = 0;
994 nd->path = save;
995 path_get(&nd->path);
996 nd->flags |= LOOKUP_REVAL;
997 result = link_path_walk(name, nd);
998 }
999
1000 path_put(&save);
1001
1002 return result;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003}
1004
Al Viro9b4a9b12009-04-07 11:44:16 -04001005static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006{
Prasanna Medaea3834d2005-04-29 16:00:17 +01001007 int retval = 0;
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001008 int fput_needed;
1009 struct file *file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
1011 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1012 nd->flags = flags;
1013 nd->depth = 0;
Al Viro2a737872009-04-07 11:49:53 -04001014 nd->root.mnt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016 if (*name=='/') {
Al Viro2a737872009-04-07 11:49:53 -04001017 set_root(nd);
1018 nd->path = nd->root;
1019 path_get(&nd->root);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001020 } else if (dfd == AT_FDCWD) {
Miklos Szeredif7ad3c62010-08-10 11:41:36 +02001021 get_fs_pwd(current->fs, &nd->path);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001022 } else {
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001023 struct dentry *dentry;
1024
1025 file = fget_light(dfd, &fput_needed);
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001026 retval = -EBADF;
1027 if (!file)
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001028 goto out_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001029
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001030 dentry = file->f_path.dentry;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001031
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001032 retval = -ENOTDIR;
1033 if (!S_ISDIR(dentry->d_inode->i_mode))
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001034 goto fput_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001035
1036 retval = file_permission(file, MAY_EXEC);
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001037 if (retval)
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001038 goto fput_fail;
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001039
Jan Blunck5dd784d02008-02-14 19:34:38 -08001040 nd->path = file->f_path;
1041 path_get(&file->f_path);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001042
1043 fput_light(file, fput_needed);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 }
Al Viro9b4a9b12009-04-07 11:44:16 -04001045 return 0;
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001046
Trond Myklebust6d09bb62006-06-04 02:51:37 -07001047fput_fail:
Ulrich Drepper170aa3d2006-02-04 23:28:02 -08001048 fput_light(file, fput_needed);
Al Viro9b4a9b12009-04-07 11:44:16 -04001049out_fail:
1050 return retval;
1051}
1052
1053/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1054static int do_path_lookup(int dfd, const char *name,
1055 unsigned int flags, struct nameidata *nd)
1056{
1057 int retval = path_init(dfd, name, flags, nd);
1058 if (!retval)
1059 retval = path_walk(name, nd);
1060 if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1061 nd->path.dentry->d_inode))
1062 audit_inode(name, nd->path.dentry);
Al Viro2a737872009-04-07 11:49:53 -04001063 if (nd->root.mnt) {
1064 path_put(&nd->root);
1065 nd->root.mnt = NULL;
1066 }
Al Viro9b4a9b12009-04-07 11:44:16 -04001067 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068}
1069
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001070int path_lookup(const char *name, unsigned int flags,
Ulrich Drepper5590ff02006-01-18 17:43:53 -08001071 struct nameidata *nd)
1072{
1073 return do_path_lookup(AT_FDCWD, name, flags, nd);
1074}
1075
Al Virod1811462008-08-02 00:49:18 -04001076int kern_path(const char *name, unsigned int flags, struct path *path)
1077{
1078 struct nameidata nd;
1079 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1080 if (!res)
1081 *path = nd.path;
1082 return res;
1083}
1084
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07001085/**
1086 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1087 * @dentry: pointer to dentry of the base directory
1088 * @mnt: pointer to vfs mount of the base directory
1089 * @name: pointer to file name
1090 * @flags: lookup flags
1091 * @nd: pointer to nameidata
1092 */
1093int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1094 const char *name, unsigned int flags,
1095 struct nameidata *nd)
1096{
1097 int retval;
1098
1099 /* same as do_path_lookup */
1100 nd->last_type = LAST_ROOT;
1101 nd->flags = flags;
1102 nd->depth = 0;
1103
Jan Blunckc8e7f442008-06-09 16:40:35 -07001104 nd->path.dentry = dentry;
1105 nd->path.mnt = mnt;
1106 path_get(&nd->path);
Al Viro5b857112009-04-07 11:53:49 -04001107 nd->root = nd->path;
1108 path_get(&nd->root);
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07001109
1110 retval = path_walk(name, nd);
Jan Blunck4ac91372008-02-14 19:34:32 -08001111 if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
1112 nd->path.dentry->d_inode))
1113 audit_inode(name, nd->path.dentry);
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07001114
Al Viro5b857112009-04-07 11:53:49 -04001115 path_put(&nd->root);
1116 nd->root.mnt = NULL;
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07001117
Al Viro2a737872009-04-07 11:49:53 -04001118 return retval;
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07001119}
1120
Christoph Hellwigeead1912007-10-16 23:25:38 -07001121static struct dentry *__lookup_hash(struct qstr *name,
1122 struct dentry *base, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123{
James Morris057f6c02007-04-26 00:12:05 -07001124 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 struct inode *inode;
1126 int err;
1127
1128 inode = base->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129
1130 /*
1131 * See if the low-level filesystem might want
1132 * to use its own hash..
1133 */
1134 if (base->d_op && base->d_op->d_hash) {
1135 err = base->d_op->d_hash(base, name);
1136 dentry = ERR_PTR(err);
1137 if (err < 0)
1138 goto out;
1139 }
1140
Nick Pigginb04f7842010-08-18 04:37:34 +10001141 /*
1142 * Don't bother with __d_lookup: callers are for creat as
1143 * well as unlink, so a lot of the time it would cost
1144 * a double lookup.
Al Viro6e6b1bd2009-08-13 23:38:37 +04001145 */
Nick Pigginb04f7842010-08-18 04:37:34 +10001146 dentry = d_lookup(base, name);
Al Viro6e6b1bd2009-08-13 23:38:37 +04001147
1148 if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
1149 dentry = do_revalidate(dentry, nd);
1150
Nick Pigginbaa03892010-08-18 04:37:31 +10001151 if (!dentry)
1152 dentry = d_alloc_and_lookup(base, name, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153out:
1154 return dentry;
1155}
1156
James Morris057f6c02007-04-26 00:12:05 -07001157/*
1158 * Restricted form of lookup. Doesn't follow links, single-component only,
1159 * needs parent already locked. Doesn't follow mounts.
1160 * SMP-safe.
1161 */
Adrian Bunka244e162006-03-31 02:32:11 -08001162static struct dentry *lookup_hash(struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163{
Christoph Hellwigeead1912007-10-16 23:25:38 -07001164 int err;
1165
Al Virob75b5082009-12-16 01:01:38 -05001166 err = exec_permission(nd->path.dentry->d_inode);
Christoph Hellwigeead1912007-10-16 23:25:38 -07001167 if (err)
1168 return ERR_PTR(err);
Jan Blunck4ac91372008-02-14 19:34:32 -08001169 return __lookup_hash(&nd->last, nd->path.dentry, nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170}
1171
Christoph Hellwigeead1912007-10-16 23:25:38 -07001172static int __lookup_one_len(const char *name, struct qstr *this,
1173 struct dentry *base, int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174{
1175 unsigned long hash;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 unsigned int c;
1177
James Morris057f6c02007-04-26 00:12:05 -07001178 this->name = name;
1179 this->len = len;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 if (!len)
James Morris057f6c02007-04-26 00:12:05 -07001181 return -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182
1183 hash = init_name_hash();
1184 while (len--) {
1185 c = *(const unsigned char *)name++;
1186 if (c == '/' || c == '\0')
James Morris057f6c02007-04-26 00:12:05 -07001187 return -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 hash = partial_name_hash(c, hash);
1189 }
James Morris057f6c02007-04-26 00:12:05 -07001190 this->hash = end_name_hash(hash);
1191 return 0;
1192}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
Christoph Hellwigeead1912007-10-16 23:25:38 -07001194/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001195 * lookup_one_len - filesystem helper to lookup single pathname component
Christoph Hellwigeead1912007-10-16 23:25:38 -07001196 * @name: pathname component to lookup
1197 * @base: base directory to lookup from
1198 * @len: maximum length @len should be interpreted to
1199 *
Randy Dunlapa6b91912008-03-19 17:01:00 -07001200 * Note that this routine is purely a helper for filesystem usage and should
1201 * not be called by generic code. Also note that by using this function the
Christoph Hellwigeead1912007-10-16 23:25:38 -07001202 * nameidata argument is passed to the filesystem methods and a filesystem
1203 * using this helper needs to be prepared for that.
1204 */
James Morris057f6c02007-04-26 00:12:05 -07001205struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1206{
1207 int err;
1208 struct qstr this;
1209
David Woodhouse2f9092e2009-04-20 23:18:37 +01001210 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1211
James Morris057f6c02007-04-26 00:12:05 -07001212 err = __lookup_one_len(name, &this, base, len);
1213 if (err)
1214 return ERR_PTR(err);
Christoph Hellwigeead1912007-10-16 23:25:38 -07001215
Al Virob75b5082009-12-16 01:01:38 -05001216 err = exec_permission(base->d_inode);
Christoph Hellwigeead1912007-10-16 23:25:38 -07001217 if (err)
1218 return ERR_PTR(err);
Christoph Hellwig49705b72005-11-08 21:35:06 -08001219 return __lookup_hash(&this, base, NULL);
James Morris057f6c02007-04-26 00:12:05 -07001220}
1221
Al Viro2d8f3032008-07-22 09:59:21 -04001222int user_path_at(int dfd, const char __user *name, unsigned flags,
1223 struct path *path)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224{
Al Viro2d8f3032008-07-22 09:59:21 -04001225 struct nameidata nd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 char *tmp = getname(name);
1227 int err = PTR_ERR(tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 if (!IS_ERR(tmp)) {
Al Viro2d8f3032008-07-22 09:59:21 -04001229
1230 BUG_ON(flags & LOOKUP_PARENT);
1231
1232 err = do_path_lookup(dfd, tmp, flags, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 putname(tmp);
Al Viro2d8f3032008-07-22 09:59:21 -04001234 if (!err)
1235 *path = nd.path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236 }
1237 return err;
1238}
1239
Al Viro2ad94ae2008-07-21 09:32:51 -04001240static int user_path_parent(int dfd, const char __user *path,
1241 struct nameidata *nd, char **name)
1242{
1243 char *s = getname(path);
1244 int error;
1245
1246 if (IS_ERR(s))
1247 return PTR_ERR(s);
1248
1249 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1250 if (error)
1251 putname(s);
1252 else
1253 *name = s;
1254
1255 return error;
1256}
1257
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258/*
1259 * It's inline, so penalty for filesystems that don't use sticky bit is
1260 * minimal.
1261 */
1262static inline int check_sticky(struct inode *dir, struct inode *inode)
1263{
David Howellsda9592e2008-11-14 10:39:05 +11001264 uid_t fsuid = current_fsuid();
1265
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 if (!(dir->i_mode & S_ISVTX))
1267 return 0;
David Howellsda9592e2008-11-14 10:39:05 +11001268 if (inode->i_uid == fsuid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 return 0;
David Howellsda9592e2008-11-14 10:39:05 +11001270 if (dir->i_uid == fsuid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 return 0;
1272 return !capable(CAP_FOWNER);
1273}
1274
1275/*
1276 * Check whether we can remove a link victim from directory dir, check
1277 * whether the type of victim is right.
1278 * 1. We can't do it if dir is read-only (done in permission())
1279 * 2. We should have write and exec permissions on dir
1280 * 3. We can't remove anything from append-only dir
1281 * 4. We can't do anything with immutable dir (done in permission())
1282 * 5. If the sticky bit on dir is set we should either
1283 * a. be owner of dir, or
1284 * b. be owner of victim, or
1285 * c. have CAP_FOWNER capability
1286 * 6. If the victim is append-only or immutable we can't do antyhing with
1287 * links pointing to it.
1288 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1289 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1290 * 9. We can't remove a root or mountpoint.
1291 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1292 * nfs_async_unlink().
1293 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001294static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295{
1296 int error;
1297
1298 if (!victim->d_inode)
1299 return -ENOENT;
1300
1301 BUG_ON(victim->d_parent->d_inode != dir);
Al Virocccc6bb2009-12-25 05:07:33 -05001302 audit_inode_child(victim, dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
Al Virof419a2e2008-07-22 00:07:17 -04001304 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305 if (error)
1306 return error;
1307 if (IS_APPEND(dir))
1308 return -EPERM;
1309 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
Hugh Dickinsf9454542008-11-19 15:36:38 -08001310 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 return -EPERM;
1312 if (isdir) {
1313 if (!S_ISDIR(victim->d_inode->i_mode))
1314 return -ENOTDIR;
1315 if (IS_ROOT(victim))
1316 return -EBUSY;
1317 } else if (S_ISDIR(victim->d_inode->i_mode))
1318 return -EISDIR;
1319 if (IS_DEADDIR(dir))
1320 return -ENOENT;
1321 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1322 return -EBUSY;
1323 return 0;
1324}
1325
1326/* Check whether we can create an object with dentry child in directory
1327 * dir.
1328 * 1. We can't do it if child already exists (open has special treatment for
1329 * this case, but since we are inlined it's OK)
1330 * 2. We can't do it if dir is read-only (done in permission())
1331 * 3. We should have write and exec permissions on dir
1332 * 4. We can't do it if dir is immutable (done in permission())
1333 */
Miklos Szeredia95164d2008-07-30 15:08:48 +02001334static inline int may_create(struct inode *dir, struct dentry *child)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335{
1336 if (child->d_inode)
1337 return -EEXIST;
1338 if (IS_DEADDIR(dir))
1339 return -ENOENT;
Al Virof419a2e2008-07-22 00:07:17 -04001340 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341}
1342
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343/*
1344 * p1 and p2 should be directories on the same fs.
1345 */
1346struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1347{
1348 struct dentry *p;
1349
1350 if (p1 == p2) {
Ingo Molnarf2eace22006-07-03 00:25:05 -07001351 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 return NULL;
1353 }
1354
Arjan van de Vena11f3a02006-03-23 03:00:33 -08001355 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09001357 p = d_ancestor(p2, p1);
1358 if (p) {
1359 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1360 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1361 return p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 }
1363
OGAWA Hirofumie2761a12008-10-16 07:50:28 +09001364 p = d_ancestor(p1, p2);
1365 if (p) {
1366 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1367 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1368 return p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 }
1370
Ingo Molnarf2eace22006-07-03 00:25:05 -07001371 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1372 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 return NULL;
1374}
1375
1376void unlock_rename(struct dentry *p1, struct dentry *p2)
1377{
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001378 mutex_unlock(&p1->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 if (p1 != p2) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001380 mutex_unlock(&p2->d_inode->i_mutex);
Arjan van de Vena11f3a02006-03-23 03:00:33 -08001381 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 }
1383}
1384
1385int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1386 struct nameidata *nd)
1387{
Miklos Szeredia95164d2008-07-30 15:08:48 +02001388 int error = may_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389
1390 if (error)
1391 return error;
1392
Al Viroacfa4382008-12-04 10:06:33 -05001393 if (!dir->i_op->create)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 return -EACCES; /* shouldn't it be ENOSYS? */
1395 mode &= S_IALLUGO;
1396 mode |= S_IFREG;
1397 error = security_inode_create(dir, dentry, mode);
1398 if (error)
1399 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 error = dir->i_op->create(dir, dentry, mode, nd);
Stephen Smalleya74574a2005-09-09 13:01:44 -07001401 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00001402 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 return error;
1404}
1405
Christoph Hellwig3fb64192008-10-24 09:58:10 +02001406int may_open(struct path *path, int acc_mode, int flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407{
Christoph Hellwig3fb64192008-10-24 09:58:10 +02001408 struct dentry *dentry = path->dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 struct inode *inode = dentry->d_inode;
1410 int error;
1411
1412 if (!inode)
1413 return -ENOENT;
1414
Christoph Hellwigc8fe8f32009-01-05 19:27:23 +01001415 switch (inode->i_mode & S_IFMT) {
1416 case S_IFLNK:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 return -ELOOP;
Christoph Hellwigc8fe8f32009-01-05 19:27:23 +01001418 case S_IFDIR:
1419 if (acc_mode & MAY_WRITE)
1420 return -EISDIR;
1421 break;
1422 case S_IFBLK:
1423 case S_IFCHR:
Christoph Hellwig3fb64192008-10-24 09:58:10 +02001424 if (path->mnt->mnt_flags & MNT_NODEV)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 return -EACCES;
Christoph Hellwigc8fe8f32009-01-05 19:27:23 +01001426 /*FALLTHRU*/
1427 case S_IFIFO:
1428 case S_IFSOCK:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 flag &= ~O_TRUNC;
Christoph Hellwigc8fe8f32009-01-05 19:27:23 +01001430 break;
Dave Hansen4a3fd212008-02-15 14:37:48 -08001431 }
Dave Hansenb41572e2007-10-16 23:31:14 -07001432
Christoph Hellwig3fb64192008-10-24 09:58:10 +02001433 error = inode_permission(inode, acc_mode);
Dave Hansenb41572e2007-10-16 23:31:14 -07001434 if (error)
1435 return error;
Mimi Zohar6146f0d2009-02-04 09:06:57 -05001436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 /*
1438 * An append-only file must be opened in append mode for writing.
1439 */
1440 if (IS_APPEND(inode)) {
Al Viro8737c932009-12-24 06:47:55 -05001441 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
Al Viro7715b522009-12-16 03:54:00 -05001442 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 if (flag & O_TRUNC)
Al Viro7715b522009-12-16 03:54:00 -05001444 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 }
1446
1447 /* O_NOATIME can only be set by the owner or superuser */
Al Viro7715b522009-12-16 03:54:00 -05001448 if (flag & O_NOATIME && !is_owner_or_cap(inode))
1449 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450
1451 /*
1452 * Ensure there are no outstanding leases on the file.
1453 */
Al Virob65a9cf2009-12-16 06:27:40 -05001454 return break_lease(inode, flag);
Al Viro7715b522009-12-16 03:54:00 -05001455}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456
Al Viro7715b522009-12-16 03:54:00 -05001457static int handle_truncate(struct path *path)
1458{
1459 struct inode *inode = path->dentry->d_inode;
1460 int error = get_write_access(inode);
1461 if (error)
1462 return error;
1463 /*
1464 * Refuse to truncate files with mandatory locks held on them.
1465 */
1466 error = locks_verify_locked(inode);
1467 if (!error)
Tetsuo Handaea0d3ab2010-06-02 13:24:43 +09001468 error = security_path_truncate(path);
Al Viro7715b522009-12-16 03:54:00 -05001469 if (!error) {
1470 error = do_truncate(path->dentry, 0,
1471 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
1472 NULL);
1473 }
1474 put_write_access(inode);
Mimi Zoharacd0c932009-09-04 13:08:46 -04001475 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476}
1477
Dave Hansend57999e2008-02-15 14:37:27 -08001478/*
1479 * Be careful about ever adding any more callers of this
1480 * function. Its flags must be in the namei format, not
1481 * what get passed to sys_open().
1482 */
1483static int __open_namei_create(struct nameidata *nd, struct path *path,
Al Viro8737c932009-12-24 06:47:55 -05001484 int open_flag, int mode)
Dave Hansenaab520e2006-09-30 23:29:02 -07001485{
1486 int error;
Jan Blunck4ac91372008-02-14 19:34:32 -08001487 struct dentry *dir = nd->path.dentry;
Dave Hansenaab520e2006-09-30 23:29:02 -07001488
1489 if (!IS_POSIXACL(dir->d_inode))
Al Viroce3b0f82009-03-29 19:08:22 -04001490 mode &= ~current_umask();
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09001491 error = security_path_mknod(&nd->path, path->dentry, mode, 0);
1492 if (error)
1493 goto out_unlock;
Dave Hansenaab520e2006-09-30 23:29:02 -07001494 error = vfs_create(dir->d_inode, path->dentry, mode, nd);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09001495out_unlock:
Dave Hansenaab520e2006-09-30 23:29:02 -07001496 mutex_unlock(&dir->d_inode->i_mutex);
Jan Blunck4ac91372008-02-14 19:34:32 -08001497 dput(nd->path.dentry);
1498 nd->path.dentry = path->dentry;
Dave Hansenaab520e2006-09-30 23:29:02 -07001499 if (error)
1500 return error;
1501 /* Don't check for write permission, don't truncate */
Al Viro8737c932009-12-24 06:47:55 -05001502 return may_open(&nd->path, 0, open_flag & ~O_TRUNC);
Dave Hansenaab520e2006-09-30 23:29:02 -07001503}
1504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505/*
Dave Hansend57999e2008-02-15 14:37:27 -08001506 * Note that while the flag value (low two bits) for sys_open means:
1507 * 00 - read-only
1508 * 01 - write-only
1509 * 10 - read-write
1510 * 11 - special
1511 * it is changed into
1512 * 00 - no permissions needed
1513 * 01 - read-permission
1514 * 10 - write-permission
1515 * 11 - read-write
1516 * for the internal routines (ie open_namei()/follow_link() etc)
1517 * This is more logical, and also allows the 00 "no perm needed"
1518 * to be used for symlinks (where the permissions are checked
1519 * later).
1520 *
1521*/
1522static inline int open_to_namei_flags(int flag)
1523{
1524 if ((flag+1) & O_ACCMODE)
1525 flag++;
1526 return flag;
1527}
1528
Al Viro7715b522009-12-16 03:54:00 -05001529static int open_will_truncate(int flag, struct inode *inode)
Dave Hansen4a3fd212008-02-15 14:37:48 -08001530{
1531 /*
1532 * We'll never write to the fs underlying
1533 * a device file.
1534 */
1535 if (special_file(inode->i_mode))
1536 return 0;
1537 return (flag & O_TRUNC);
1538}
1539
Al Viro648fa862009-12-24 01:26:48 -05001540static struct file *finish_open(struct nameidata *nd,
Al Viro9a661792009-12-24 06:49:47 -05001541 int open_flag, int acc_mode)
Al Viro648fa862009-12-24 01:26:48 -05001542{
1543 struct file *filp;
1544 int will_truncate;
1545 int error;
1546
Al Viro9a661792009-12-24 06:49:47 -05001547 will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode);
Al Viro648fa862009-12-24 01:26:48 -05001548 if (will_truncate) {
1549 error = mnt_want_write(nd->path.mnt);
1550 if (error)
1551 goto exit;
1552 }
1553 error = may_open(&nd->path, acc_mode, open_flag);
1554 if (error) {
1555 if (will_truncate)
1556 mnt_drop_write(nd->path.mnt);
1557 goto exit;
1558 }
1559 filp = nameidata_to_filp(nd);
1560 if (!IS_ERR(filp)) {
1561 error = ima_file_check(filp, acc_mode);
1562 if (error) {
1563 fput(filp);
1564 filp = ERR_PTR(error);
1565 }
1566 }
1567 if (!IS_ERR(filp)) {
Al Viro648fa862009-12-24 01:26:48 -05001568 if (will_truncate) {
1569 error = handle_truncate(&nd->path);
1570 if (error) {
1571 fput(filp);
1572 filp = ERR_PTR(error);
1573 }
1574 }
1575 }
1576 /*
1577 * It is now safe to drop the mnt write
1578 * because the filp has had a write taken
1579 * on its behalf.
1580 */
1581 if (will_truncate)
1582 mnt_drop_write(nd->path.mnt);
1583 return filp;
1584
1585exit:
1586 if (!IS_ERR(nd->intent.open.file))
1587 release_open_intent(nd);
1588 path_put(&nd->path);
1589 return ERR_PTR(error);
1590}
1591
Al Virofb1cc552009-12-24 01:58:28 -05001592static struct file *do_last(struct nameidata *nd, struct path *path,
Al Viro5b369df2009-12-24 06:51:13 -05001593 int open_flag, int acc_mode,
Al Viro3e297b62010-03-26 12:40:13 -04001594 int mode, const char *pathname)
Al Virofb1cc552009-12-24 01:58:28 -05001595{
Al Viroa1e28032009-12-24 02:12:06 -05001596 struct dentry *dir = nd->path.dentry;
Al Virofb1cc552009-12-24 01:58:28 -05001597 struct file *filp;
Al Viro1f36f772009-12-26 10:56:19 -05001598 int error = -EISDIR;
Al Virofb1cc552009-12-24 01:58:28 -05001599
Al Viro1f36f772009-12-26 10:56:19 -05001600 switch (nd->last_type) {
1601 case LAST_DOTDOT:
1602 follow_dotdot(nd);
1603 dir = nd->path.dentry;
Neil Brown176306f2010-05-24 16:57:56 +10001604 case LAST_DOT:
Al Viro1f36f772009-12-26 10:56:19 -05001605 if (nd->path.mnt->mnt_sb->s_type->fs_flags & FS_REVAL_DOT) {
1606 if (!dir->d_op->d_revalidate(dir, nd)) {
1607 error = -ESTALE;
1608 goto exit;
1609 }
1610 }
1611 /* fallthrough */
Al Viro1f36f772009-12-26 10:56:19 -05001612 case LAST_ROOT:
1613 if (open_flag & O_CREAT)
1614 goto exit;
1615 /* fallthrough */
1616 case LAST_BIND:
1617 audit_inode(pathname, dir);
Al Viro67ee3ad2009-12-26 07:01:01 -05001618 goto ok;
Al Viro1f36f772009-12-26 10:56:19 -05001619 }
Al Viro67ee3ad2009-12-26 07:01:01 -05001620
Al Viro1f36f772009-12-26 10:56:19 -05001621 /* trailing slashes? */
1622 if (nd->last.name[nd->last.len]) {
1623 if (open_flag & O_CREAT)
1624 goto exit;
Jan Kara002baee2010-05-13 12:52:57 +02001625 nd->flags |= LOOKUP_DIRECTORY | LOOKUP_FOLLOW;
Al Viro1f36f772009-12-26 10:56:19 -05001626 }
Al Viroa2c36b42009-12-24 03:39:50 -05001627
Al Viro1f36f772009-12-26 10:56:19 -05001628 /* just plain open? */
1629 if (!(open_flag & O_CREAT)) {
1630 error = do_lookup(nd, &nd->last, path);
1631 if (error)
1632 goto exit;
1633 error = -ENOENT;
1634 if (!path->dentry->d_inode)
1635 goto exit_dput;
1636 if (path->dentry->d_inode->i_op->follow_link)
1637 return NULL;
1638 error = -ENOTDIR;
Al Viro3e297b62010-03-26 12:40:13 -04001639 if (nd->flags & LOOKUP_DIRECTORY) {
1640 if (!path->dentry->d_inode->i_op->lookup)
1641 goto exit_dput;
1642 }
Al Viro1f36f772009-12-26 10:56:19 -05001643 path_to_nameidata(path, nd);
1644 audit_inode(pathname, nd->path.dentry);
1645 goto ok;
1646 }
1647
1648 /* OK, it's O_CREAT */
Al Viroa1e28032009-12-24 02:12:06 -05001649 mutex_lock(&dir->d_inode->i_mutex);
1650
1651 path->dentry = lookup_hash(nd);
1652 path->mnt = nd->path.mnt;
1653
Al Virofb1cc552009-12-24 01:58:28 -05001654 error = PTR_ERR(path->dentry);
1655 if (IS_ERR(path->dentry)) {
1656 mutex_unlock(&dir->d_inode->i_mutex);
1657 goto exit;
1658 }
1659
1660 if (IS_ERR(nd->intent.open.file)) {
1661 error = PTR_ERR(nd->intent.open.file);
1662 goto exit_mutex_unlock;
1663 }
1664
1665 /* Negative dentry, just create the file */
1666 if (!path->dentry->d_inode) {
1667 /*
1668 * This write is needed to ensure that a
1669 * ro->rw transition does not occur between
1670 * the time when the file is created and when
1671 * a permanent write count is taken through
1672 * the 'struct file' in nameidata_to_filp().
1673 */
1674 error = mnt_want_write(nd->path.mnt);
1675 if (error)
1676 goto exit_mutex_unlock;
1677 error = __open_namei_create(nd, path, open_flag, mode);
1678 if (error) {
1679 mnt_drop_write(nd->path.mnt);
1680 goto exit;
1681 }
1682 filp = nameidata_to_filp(nd);
1683 mnt_drop_write(nd->path.mnt);
Al Virofb1cc552009-12-24 01:58:28 -05001684 if (!IS_ERR(filp)) {
1685 error = ima_file_check(filp, acc_mode);
1686 if (error) {
1687 fput(filp);
1688 filp = ERR_PTR(error);
1689 }
1690 }
1691 return filp;
1692 }
1693
1694 /*
1695 * It already exists.
1696 */
1697 mutex_unlock(&dir->d_inode->i_mutex);
1698 audit_inode(pathname, path->dentry);
1699
1700 error = -EEXIST;
Al Viro5b369df2009-12-24 06:51:13 -05001701 if (open_flag & O_EXCL)
Al Virofb1cc552009-12-24 01:58:28 -05001702 goto exit_dput;
1703
1704 if (__follow_mount(path)) {
1705 error = -ELOOP;
Al Viro5b369df2009-12-24 06:51:13 -05001706 if (open_flag & O_NOFOLLOW)
Al Virofb1cc552009-12-24 01:58:28 -05001707 goto exit_dput;
1708 }
1709
1710 error = -ENOENT;
1711 if (!path->dentry->d_inode)
1712 goto exit_dput;
Al Viro9e67f362009-12-26 07:04:50 -05001713
1714 if (path->dentry->d_inode->i_op->follow_link)
Al Virofb1cc552009-12-24 01:58:28 -05001715 return NULL;
Al Virofb1cc552009-12-24 01:58:28 -05001716
1717 path_to_nameidata(path, nd);
1718 error = -EISDIR;
1719 if (S_ISDIR(path->dentry->d_inode->i_mode))
1720 goto exit;
Al Viro67ee3ad2009-12-26 07:01:01 -05001721ok:
Al Viro9a661792009-12-24 06:49:47 -05001722 filp = finish_open(nd, open_flag, acc_mode);
Al Virofb1cc552009-12-24 01:58:28 -05001723 return filp;
1724
1725exit_mutex_unlock:
1726 mutex_unlock(&dir->d_inode->i_mutex);
1727exit_dput:
1728 path_put_conditional(path, nd);
1729exit:
1730 if (!IS_ERR(nd->intent.open.file))
1731 release_open_intent(nd);
Al Virofb1cc552009-12-24 01:58:28 -05001732 path_put(&nd->path);
1733 return ERR_PTR(error);
1734}
1735
Dave Hansend57999e2008-02-15 14:37:27 -08001736/*
Dave Hansen4a3fd212008-02-15 14:37:48 -08001737 * Note that the low bits of the passed in "open_flag"
1738 * are not the same as in the local variable "flag". See
1739 * open_to_namei_flags() for more details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001740 */
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001741struct file *do_filp_open(int dfd, const char *pathname,
Al Viro6e8341a2009-04-06 11:16:22 -04001742 int open_flag, int mode, int acc_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743{
Dave Hansen4a3fd212008-02-15 14:37:48 -08001744 struct file *filp;
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001745 struct nameidata nd;
Al Viro6e8341a2009-04-06 11:16:22 -04001746 int error;
Al Viro9850c052010-01-13 15:01:15 -05001747 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 int count = 0;
Dave Hansend57999e2008-02-15 14:37:27 -08001749 int flag = open_to_namei_flags(open_flag);
Al Viro9850c052010-01-13 15:01:15 -05001750 int force_reval = 0;
Al Viro1f36f772009-12-26 10:56:19 -05001751
1752 if (!(open_flag & O_CREAT))
1753 mode = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754
Christoph Hellwig6b2f3d12009-10-27 11:05:28 +01001755 /*
1756 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1757 * check for O_DSYNC if the need any syncing at all we enforce it's
1758 * always set instead of having to deal with possibly weird behaviour
1759 * for malicious applications setting only __O_SYNC.
1760 */
1761 if (open_flag & __O_SYNC)
1762 open_flag |= O_DSYNC;
1763
Al Viro6e8341a2009-04-06 11:16:22 -04001764 if (!acc_mode)
Al Viro6d125522009-12-24 06:58:56 -05001765 acc_mode = MAY_OPEN | ACC_MODE(open_flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766
Trond Myklebust834f2a42005-10-18 14:20:16 -07001767 /* O_TRUNC implies we need access checks for write permissions */
Al Viro4296e2c2009-12-24 07:15:41 -05001768 if (open_flag & O_TRUNC)
Trond Myklebust834f2a42005-10-18 14:20:16 -07001769 acc_mode |= MAY_WRITE;
1770
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 /* Allow the LSM permission hook to distinguish append
1772 access from general write access. */
Al Viro4296e2c2009-12-24 07:15:41 -05001773 if (open_flag & O_APPEND)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 acc_mode |= MAY_APPEND;
1775
Al Viro1f36f772009-12-26 10:56:19 -05001776 /* find the parent */
Al Viro9850c052010-01-13 15:01:15 -05001777reval:
Al Viro9b4a9b12009-04-07 11:44:16 -04001778 error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 if (error)
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001780 return ERR_PTR(error);
Al Viro9850c052010-01-13 15:01:15 -05001781 if (force_reval)
1782 nd.flags |= LOOKUP_REVAL;
Al Viro38662482009-12-26 07:21:48 -05001783
1784 current->total_link_count = 0;
1785 error = link_path_walk(pathname, &nd);
J. R. Okajima654f5622009-06-18 23:30:15 +09001786 if (error) {
Al Viro10fa8e62009-12-26 07:09:49 -05001787 filp = ERR_PTR(error);
1788 goto out;
J. R. Okajima654f5622009-06-18 23:30:15 +09001789 }
Al Viro1f36f772009-12-26 10:56:19 -05001790 if (unlikely(!audit_dummy_context()) && (open_flag & O_CREAT))
Al Viro9b4a9b12009-04-07 11:44:16 -04001791 audit_inode(pathname, nd.path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792
1793 /*
Al Viroa2c36b42009-12-24 03:39:50 -05001794 * We have the parent and last component.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796
Al Viro8737f3a2008-08-02 22:36:57 -04001797 error = -ENFILE;
1798 filp = get_empty_filp();
1799 if (filp == NULL)
1800 goto exit_parent;
1801 nd.intent.open.file = filp;
Al Viro482928d2009-12-19 10:10:39 -05001802 filp->f_flags = open_flag;
Al Viro8737f3a2008-08-02 22:36:57 -04001803 nd.intent.open.flags = flag;
1804 nd.intent.open.create_mode = mode;
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001805 nd.flags &= ~LOOKUP_PARENT;
Al Viro1f36f772009-12-26 10:56:19 -05001806 nd.flags |= LOOKUP_OPEN;
1807 if (open_flag & O_CREAT) {
1808 nd.flags |= LOOKUP_CREATE;
1809 if (open_flag & O_EXCL)
1810 nd.flags |= LOOKUP_EXCL;
1811 }
Al Viro3e297b62010-03-26 12:40:13 -04001812 if (open_flag & O_DIRECTORY)
1813 nd.flags |= LOOKUP_DIRECTORY;
Jan Kara002baee2010-05-13 12:52:57 +02001814 if (!(open_flag & O_NOFOLLOW))
1815 nd.flags |= LOOKUP_FOLLOW;
Al Viro3e297b62010-03-26 12:40:13 -04001816 filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
Al Viro806b6812009-12-26 07:16:40 -05001817 while (unlikely(!filp)) { /* trailing symlink */
Al Virodef4af32009-12-26 08:37:05 -05001818 struct path holder;
Al Viro1f36f772009-12-26 10:56:19 -05001819 struct inode *inode = path.dentry->d_inode;
Al Virodef4af32009-12-26 08:37:05 -05001820 void *cookie;
Al Viro806b6812009-12-26 07:16:40 -05001821 error = -ELOOP;
Al Viro1f36f772009-12-26 10:56:19 -05001822 /* S_ISDIR part is a temporary automount kludge */
Jan Kara002baee2010-05-13 12:52:57 +02001823 if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(inode->i_mode))
Al Viro1f36f772009-12-26 10:56:19 -05001824 goto exit_dput;
1825 if (count++ == 32)
Al Viro806b6812009-12-26 07:16:40 -05001826 goto exit_dput;
1827 /*
1828 * This is subtle. Instead of calling do_follow_link() we do
1829 * the thing by hands. The reason is that this way we have zero
1830 * link_count and path_walk() (called from ->follow_link)
1831 * honoring LOOKUP_PARENT. After that we have the parent and
1832 * last component, i.e. we are in the same situation as after
1833 * the first path_walk(). Well, almost - if the last component
1834 * is normal we get its copy stored in nd->last.name and we will
1835 * have to putname() it when we are done. Procfs-like symlinks
1836 * just set LAST_BIND.
1837 */
1838 nd.flags |= LOOKUP_PARENT;
1839 error = security_inode_follow_link(path.dentry, &nd);
1840 if (error)
1841 goto exit_dput;
Al Virodef4af32009-12-26 08:37:05 -05001842 error = __do_follow_link(&path, &nd, &cookie);
1843 if (unlikely(error)) {
Al Viro806b6812009-12-26 07:16:40 -05001844 /* nd.path had been dropped */
Al Virodef4af32009-12-26 08:37:05 -05001845 if (!IS_ERR(cookie) && inode->i_op->put_link)
1846 inode->i_op->put_link(path.dentry, &nd, cookie);
1847 path_put(&path);
Al Viro806b6812009-12-26 07:16:40 -05001848 release_open_intent(&nd);
1849 filp = ERR_PTR(error);
1850 goto out;
1851 }
Al Virodef4af32009-12-26 08:37:05 -05001852 holder = path;
Al Viro806b6812009-12-26 07:16:40 -05001853 nd.flags &= ~LOOKUP_PARENT;
Al Viro3e297b62010-03-26 12:40:13 -04001854 filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
Al Virodef4af32009-12-26 08:37:05 -05001855 if (inode->i_op->put_link)
1856 inode->i_op->put_link(holder.dentry, &nd, cookie);
1857 path_put(&holder);
Al Viro806b6812009-12-26 07:16:40 -05001858 }
Al Viro10fa8e62009-12-26 07:09:49 -05001859out:
Al Viro2a737872009-04-07 11:49:53 -04001860 if (nd.root.mnt)
1861 path_put(&nd.root);
Al Viro10fa8e62009-12-26 07:09:49 -05001862 if (filp == ERR_PTR(-ESTALE) && !force_reval) {
1863 force_reval = 1;
1864 goto reval;
1865 }
1866 return filp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867
Al Viro806b6812009-12-26 07:16:40 -05001868exit_dput:
1869 path_put_conditional(&path, &nd);
1870 if (!IS_ERR(nd.intent.open.file))
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001871 release_open_intent(&nd);
Al Viro806b6812009-12-26 07:16:40 -05001872exit_parent:
1873 path_put(&nd.path);
1874 filp = ERR_PTR(error);
Al Viro10fa8e62009-12-26 07:09:49 -05001875 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876}
1877
1878/**
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001879 * filp_open - open file and return file pointer
1880 *
1881 * @filename: path to open
1882 * @flags: open flags as per the open(2) second argument
1883 * @mode: mode for the new file if O_CREAT is set, else ignored
1884 *
1885 * This is the helper to open a file from kernelspace if you really
1886 * have to. But in generally you should not do this, so please move
1887 * along, nothing to see here..
1888 */
1889struct file *filp_open(const char *filename, int flags, int mode)
1890{
Al Viro6e8341a2009-04-06 11:16:22 -04001891 return do_filp_open(AT_FDCWD, filename, flags, mode, 0);
Christoph Hellwiga70e65d2008-02-15 14:37:28 -08001892}
1893EXPORT_SYMBOL(filp_open);
1894
1895/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 * lookup_create - lookup a dentry, creating it if it doesn't exist
1897 * @nd: nameidata info
1898 * @is_dir: directory flag
1899 *
1900 * Simple function to lookup and return a dentry and create it
1901 * if it doesn't exist. Is SMP-safe.
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001902 *
Jan Blunck4ac91372008-02-14 19:34:32 -08001903 * Returns with nd->path.dentry->d_inode->i_mutex locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904 */
1905struct dentry *lookup_create(struct nameidata *nd, int is_dir)
1906{
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001907 struct dentry *dentry = ERR_PTR(-EEXIST);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001908
Jan Blunck4ac91372008-02-14 19:34:32 -08001909 mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001910 /*
1911 * Yucky last component or no last component at all?
1912 * (foo/., foo/.., /////)
1913 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 if (nd->last_type != LAST_NORM)
1915 goto fail;
1916 nd->flags &= ~LOOKUP_PARENT;
Al Viro35165862008-08-05 03:00:49 -04001917 nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
ASANO Masahiroa6349042006-08-22 20:06:02 -04001918 nd->intent.open.flags = O_EXCL;
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001919
1920 /*
1921 * Do the final lookup.
1922 */
Christoph Hellwig49705b72005-11-08 21:35:06 -08001923 dentry = lookup_hash(nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 if (IS_ERR(dentry))
1925 goto fail;
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001926
Al Viroe9baf6e2008-05-15 04:49:12 -04001927 if (dentry->d_inode)
1928 goto eexist;
Christoph Hellwigc663e5d2005-06-23 00:09:49 -07001929 /*
1930 * Special case - lookup gave negative, but... we had foo/bar/
1931 * From the vfs_mknod() POV we just have a negative dentry -
1932 * all is fine. Let's be bastards - you had / on the end, you've
1933 * been asking for (non-existent) directory. -ENOENT for you.
1934 */
Al Viroe9baf6e2008-05-15 04:49:12 -04001935 if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
1936 dput(dentry);
1937 dentry = ERR_PTR(-ENOENT);
1938 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 return dentry;
Al Viroe9baf6e2008-05-15 04:49:12 -04001940eexist:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 dput(dentry);
Al Viroe9baf6e2008-05-15 04:49:12 -04001942 dentry = ERR_PTR(-EEXIST);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943fail:
1944 return dentry;
1945}
Christoph Hellwigf81a0bf2005-05-19 12:26:43 -07001946EXPORT_SYMBOL_GPL(lookup_create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947
1948int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1949{
Miklos Szeredia95164d2008-07-30 15:08:48 +02001950 int error = may_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951
1952 if (error)
1953 return error;
1954
1955 if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
1956 return -EPERM;
1957
Al Viroacfa4382008-12-04 10:06:33 -05001958 if (!dir->i_op->mknod)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959 return -EPERM;
1960
Serge E. Hallyn08ce5f12008-04-29 01:00:10 -07001961 error = devcgroup_inode_mknod(mode, dev);
1962 if (error)
1963 return error;
1964
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965 error = security_inode_mknod(dir, dentry, mode, dev);
1966 if (error)
1967 return error;
1968
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969 error = dir->i_op->mknod(dir, dentry, mode, dev);
Stephen Smalleya74574a2005-09-09 13:01:44 -07001970 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00001971 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972 return error;
1973}
1974
Dave Hansen463c3192008-02-15 14:37:57 -08001975static int may_mknod(mode_t mode)
1976{
1977 switch (mode & S_IFMT) {
1978 case S_IFREG:
1979 case S_IFCHR:
1980 case S_IFBLK:
1981 case S_IFIFO:
1982 case S_IFSOCK:
1983 case 0: /* zero mode translates to S_IFREG */
1984 return 0;
1985 case S_IFDIR:
1986 return -EPERM;
1987 default:
1988 return -EINVAL;
1989 }
1990}
1991
Heiko Carstens2e4d0922009-01-14 14:14:31 +01001992SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
1993 unsigned, dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994{
Al Viro2ad94ae2008-07-21 09:32:51 -04001995 int error;
1996 char *tmp;
1997 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001998 struct nameidata nd;
1999
2000 if (S_ISDIR(mode))
2001 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002
Al Viro2ad94ae2008-07-21 09:32:51 -04002003 error = user_path_parent(dfd, filename, &nd, &tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004 if (error)
Al Viro2ad94ae2008-07-21 09:32:51 -04002005 return error;
2006
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 dentry = lookup_create(&nd, 0);
Dave Hansen463c3192008-02-15 14:37:57 -08002008 if (IS_ERR(dentry)) {
2009 error = PTR_ERR(dentry);
2010 goto out_unlock;
2011 }
Jan Blunck4ac91372008-02-14 19:34:32 -08002012 if (!IS_POSIXACL(nd.path.dentry->d_inode))
Al Viroce3b0f82009-03-29 19:08:22 -04002013 mode &= ~current_umask();
Dave Hansen463c3192008-02-15 14:37:57 -08002014 error = may_mknod(mode);
2015 if (error)
2016 goto out_dput;
2017 error = mnt_want_write(nd.path.mnt);
2018 if (error)
2019 goto out_dput;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002020 error = security_path_mknod(&nd.path, dentry, mode, dev);
2021 if (error)
2022 goto out_drop_write;
Dave Hansen463c3192008-02-15 14:37:57 -08002023 switch (mode & S_IFMT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 case 0: case S_IFREG:
Jan Blunck4ac91372008-02-14 19:34:32 -08002025 error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 break;
2027 case S_IFCHR: case S_IFBLK:
Jan Blunck4ac91372008-02-14 19:34:32 -08002028 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002029 new_decode_dev(dev));
2030 break;
2031 case S_IFIFO: case S_IFSOCK:
Jan Blunck4ac91372008-02-14 19:34:32 -08002032 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002034 }
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002035out_drop_write:
Dave Hansen463c3192008-02-15 14:37:57 -08002036 mnt_drop_write(nd.path.mnt);
2037out_dput:
2038 dput(dentry);
2039out_unlock:
Jan Blunck4ac91372008-02-14 19:34:32 -08002040 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Jan Blunck1d957f92008-02-14 19:34:35 -08002041 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042 putname(tmp);
2043
2044 return error;
2045}
2046
Heiko Carstens3480b252009-01-14 14:14:16 +01002047SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002048{
2049 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2050}
2051
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2053{
Miklos Szeredia95164d2008-07-30 15:08:48 +02002054 int error = may_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055
2056 if (error)
2057 return error;
2058
Al Viroacfa4382008-12-04 10:06:33 -05002059 if (!dir->i_op->mkdir)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060 return -EPERM;
2061
2062 mode &= (S_IRWXUGO|S_ISVTX);
2063 error = security_inode_mkdir(dir, dentry, mode);
2064 if (error)
2065 return error;
2066
Linus Torvalds1da177e2005-04-16 15:20:36 -07002067 error = dir->i_op->mkdir(dir, dentry, mode);
Stephen Smalleya74574a2005-09-09 13:01:44 -07002068 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00002069 fsnotify_mkdir(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 return error;
2071}
2072
Heiko Carstens2e4d0922009-01-14 14:14:31 +01002073SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002074{
2075 int error = 0;
2076 char * tmp;
Dave Hansen6902d922006-09-30 23:29:01 -07002077 struct dentry *dentry;
2078 struct nameidata nd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079
Al Viro2ad94ae2008-07-21 09:32:51 -04002080 error = user_path_parent(dfd, pathname, &nd, &tmp);
2081 if (error)
Dave Hansen6902d922006-09-30 23:29:01 -07002082 goto out_err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
Dave Hansen6902d922006-09-30 23:29:01 -07002084 dentry = lookup_create(&nd, 1);
2085 error = PTR_ERR(dentry);
2086 if (IS_ERR(dentry))
2087 goto out_unlock;
2088
Jan Blunck4ac91372008-02-14 19:34:32 -08002089 if (!IS_POSIXACL(nd.path.dentry->d_inode))
Al Viroce3b0f82009-03-29 19:08:22 -04002090 mode &= ~current_umask();
Dave Hansen463c3192008-02-15 14:37:57 -08002091 error = mnt_want_write(nd.path.mnt);
2092 if (error)
2093 goto out_dput;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002094 error = security_path_mkdir(&nd.path, dentry, mode);
2095 if (error)
2096 goto out_drop_write;
Jan Blunck4ac91372008-02-14 19:34:32 -08002097 error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002098out_drop_write:
Dave Hansen463c3192008-02-15 14:37:57 -08002099 mnt_drop_write(nd.path.mnt);
2100out_dput:
Dave Hansen6902d922006-09-30 23:29:01 -07002101 dput(dentry);
2102out_unlock:
Jan Blunck4ac91372008-02-14 19:34:32 -08002103 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Jan Blunck1d957f92008-02-14 19:34:35 -08002104 path_put(&nd.path);
Dave Hansen6902d922006-09-30 23:29:01 -07002105 putname(tmp);
2106out_err:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 return error;
2108}
2109
Heiko Carstens3cdad422009-01-14 14:14:22 +01002110SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002111{
2112 return sys_mkdirat(AT_FDCWD, pathname, mode);
2113}
2114
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115/*
2116 * We try to drop the dentry early: we should have
2117 * a usage count of 2 if we're the only user of this
2118 * dentry, and if that is true (possibly after pruning
2119 * the dcache), then we drop the dentry now.
2120 *
2121 * A low-level filesystem can, if it choses, legally
2122 * do a
2123 *
2124 * if (!d_unhashed(dentry))
2125 * return -EBUSY;
2126 *
2127 * if it cannot handle the case of removing a directory
2128 * that is still in use by something else..
2129 */
2130void dentry_unhash(struct dentry *dentry)
2131{
2132 dget(dentry);
Vasily Averindc168422006-12-06 20:37:07 -08002133 shrink_dcache_parent(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134 spin_lock(&dcache_lock);
2135 spin_lock(&dentry->d_lock);
2136 if (atomic_read(&dentry->d_count) == 2)
2137 __d_drop(dentry);
2138 spin_unlock(&dentry->d_lock);
2139 spin_unlock(&dcache_lock);
2140}
2141
2142int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2143{
2144 int error = may_delete(dir, dentry, 1);
2145
2146 if (error)
2147 return error;
2148
Al Viroacfa4382008-12-04 10:06:33 -05002149 if (!dir->i_op->rmdir)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 return -EPERM;
2151
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002152 mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 dentry_unhash(dentry);
2154 if (d_mountpoint(dentry))
2155 error = -EBUSY;
2156 else {
2157 error = security_inode_rmdir(dir, dentry);
2158 if (!error) {
2159 error = dir->i_op->rmdir(dir, dentry);
Al Virod83c49f2010-04-30 17:17:09 -04002160 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 dentry->d_inode->i_flags |= S_DEAD;
Al Virod83c49f2010-04-30 17:17:09 -04002162 dont_mount(dentry);
2163 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 }
2165 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002166 mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 d_delete(dentry);
2169 }
2170 dput(dentry);
2171
2172 return error;
2173}
2174
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002175static long do_rmdir(int dfd, const char __user *pathname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176{
2177 int error = 0;
2178 char * name;
2179 struct dentry *dentry;
2180 struct nameidata nd;
2181
Al Viro2ad94ae2008-07-21 09:32:51 -04002182 error = user_path_parent(dfd, pathname, &nd, &name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 if (error)
Al Viro2ad94ae2008-07-21 09:32:51 -04002184 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185
2186 switch(nd.last_type) {
OGAWA Hirofumi0612d9f2008-10-16 07:50:29 +09002187 case LAST_DOTDOT:
2188 error = -ENOTEMPTY;
2189 goto exit1;
2190 case LAST_DOT:
2191 error = -EINVAL;
2192 goto exit1;
2193 case LAST_ROOT:
2194 error = -EBUSY;
2195 goto exit1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 }
OGAWA Hirofumi0612d9f2008-10-16 07:50:29 +09002197
2198 nd.flags &= ~LOOKUP_PARENT;
2199
Jan Blunck4ac91372008-02-14 19:34:32 -08002200 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwig49705b72005-11-08 21:35:06 -08002201 dentry = lookup_hash(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202 error = PTR_ERR(dentry);
Dave Hansen6902d922006-09-30 23:29:01 -07002203 if (IS_ERR(dentry))
2204 goto exit2;
Dave Hansen06227532008-02-15 14:37:34 -08002205 error = mnt_want_write(nd.path.mnt);
2206 if (error)
2207 goto exit3;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002208 error = security_path_rmdir(&nd.path, dentry);
2209 if (error)
2210 goto exit4;
Jan Blunck4ac91372008-02-14 19:34:32 -08002211 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002212exit4:
Dave Hansen06227532008-02-15 14:37:34 -08002213 mnt_drop_write(nd.path.mnt);
2214exit3:
Dave Hansen6902d922006-09-30 23:29:01 -07002215 dput(dentry);
2216exit2:
Jan Blunck4ac91372008-02-14 19:34:32 -08002217 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218exit1:
Jan Blunck1d957f92008-02-14 19:34:35 -08002219 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 putname(name);
2221 return error;
2222}
2223
Heiko Carstens3cdad422009-01-14 14:14:22 +01002224SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002225{
2226 return do_rmdir(AT_FDCWD, pathname);
2227}
2228
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229int vfs_unlink(struct inode *dir, struct dentry *dentry)
2230{
2231 int error = may_delete(dir, dentry, 0);
2232
2233 if (error)
2234 return error;
2235
Al Viroacfa4382008-12-04 10:06:33 -05002236 if (!dir->i_op->unlink)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237 return -EPERM;
2238
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002239 mutex_lock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240 if (d_mountpoint(dentry))
2241 error = -EBUSY;
2242 else {
2243 error = security_inode_unlink(dir, dentry);
Al Virobec10522010-03-03 14:12:08 -05002244 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 error = dir->i_op->unlink(dir, dentry);
Al Virobec10522010-03-03 14:12:08 -05002246 if (!error)
Al Virod83c49f2010-04-30 17:17:09 -04002247 dont_mount(dentry);
Al Virobec10522010-03-03 14:12:08 -05002248 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002250 mutex_unlock(&dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251
2252 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2253 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
Jan Karaece95912008-02-06 01:37:13 -08002254 fsnotify_link_count(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 d_delete(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 }
Robert Love0eeca282005-07-12 17:06:03 -04002257
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 return error;
2259}
2260
2261/*
2262 * Make sure that the actual truncation of the file will occur outside its
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002263 * directory's i_mutex. Truncate can take a long time if there is a lot of
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 * writeout happening, and we don't want to prevent access to the directory
2265 * while waiting on the I/O.
2266 */
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002267static long do_unlinkat(int dfd, const char __user *pathname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268{
Al Viro2ad94ae2008-07-21 09:32:51 -04002269 int error;
2270 char *name;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271 struct dentry *dentry;
2272 struct nameidata nd;
2273 struct inode *inode = NULL;
2274
Al Viro2ad94ae2008-07-21 09:32:51 -04002275 error = user_path_parent(dfd, pathname, &nd, &name);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276 if (error)
Al Viro2ad94ae2008-07-21 09:32:51 -04002277 return error;
2278
Linus Torvalds1da177e2005-04-16 15:20:36 -07002279 error = -EISDIR;
2280 if (nd.last_type != LAST_NORM)
2281 goto exit1;
OGAWA Hirofumi0612d9f2008-10-16 07:50:29 +09002282
2283 nd.flags &= ~LOOKUP_PARENT;
2284
Jan Blunck4ac91372008-02-14 19:34:32 -08002285 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
Christoph Hellwig49705b72005-11-08 21:35:06 -08002286 dentry = lookup_hash(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287 error = PTR_ERR(dentry);
2288 if (!IS_ERR(dentry)) {
2289 /* Why not before? Because we want correct error value */
2290 if (nd.last.name[nd.last.len])
2291 goto slashes;
2292 inode = dentry->d_inode;
2293 if (inode)
2294 atomic_inc(&inode->i_count);
Dave Hansen06227532008-02-15 14:37:34 -08002295 error = mnt_want_write(nd.path.mnt);
2296 if (error)
2297 goto exit2;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002298 error = security_path_unlink(&nd.path, dentry);
2299 if (error)
2300 goto exit3;
Jan Blunck4ac91372008-02-14 19:34:32 -08002301 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002302exit3:
Dave Hansen06227532008-02-15 14:37:34 -08002303 mnt_drop_write(nd.path.mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 exit2:
2305 dput(dentry);
2306 }
Jan Blunck4ac91372008-02-14 19:34:32 -08002307 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 if (inode)
2309 iput(inode); /* truncate the inode here */
2310exit1:
Jan Blunck1d957f92008-02-14 19:34:35 -08002311 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 putname(name);
2313 return error;
2314
2315slashes:
2316 error = !dentry->d_inode ? -ENOENT :
2317 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2318 goto exit2;
2319}
2320
Heiko Carstens2e4d0922009-01-14 14:14:31 +01002321SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002322{
2323 if ((flag & ~AT_REMOVEDIR) != 0)
2324 return -EINVAL;
2325
2326 if (flag & AT_REMOVEDIR)
2327 return do_rmdir(dfd, pathname);
2328
2329 return do_unlinkat(dfd, pathname);
2330}
2331
Heiko Carstens3480b252009-01-14 14:14:16 +01002332SYSCALL_DEFINE1(unlink, const char __user *, pathname)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002333{
2334 return do_unlinkat(AT_FDCWD, pathname);
2335}
2336
Miklos Szeredidb2e7472008-06-24 16:50:16 +02002337int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338{
Miklos Szeredia95164d2008-07-30 15:08:48 +02002339 int error = may_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340
2341 if (error)
2342 return error;
2343
Al Viroacfa4382008-12-04 10:06:33 -05002344 if (!dir->i_op->symlink)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 return -EPERM;
2346
2347 error = security_inode_symlink(dir, dentry, oldname);
2348 if (error)
2349 return error;
2350
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 error = dir->i_op->symlink(dir, dentry, oldname);
Stephen Smalleya74574a2005-09-09 13:01:44 -07002352 if (!error)
Amy Griffisf38aa942005-11-03 15:57:06 +00002353 fsnotify_create(dir, dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 return error;
2355}
2356
Heiko Carstens2e4d0922009-01-14 14:14:31 +01002357SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2358 int, newdfd, const char __user *, newname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359{
Al Viro2ad94ae2008-07-21 09:32:51 -04002360 int error;
2361 char *from;
2362 char *to;
Dave Hansen6902d922006-09-30 23:29:01 -07002363 struct dentry *dentry;
2364 struct nameidata nd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365
2366 from = getname(oldname);
Al Viro2ad94ae2008-07-21 09:32:51 -04002367 if (IS_ERR(from))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 return PTR_ERR(from);
Al Viro2ad94ae2008-07-21 09:32:51 -04002369
2370 error = user_path_parent(newdfd, newname, &nd, &to);
2371 if (error)
Dave Hansen6902d922006-09-30 23:29:01 -07002372 goto out_putname;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373
Dave Hansen6902d922006-09-30 23:29:01 -07002374 dentry = lookup_create(&nd, 0);
2375 error = PTR_ERR(dentry);
2376 if (IS_ERR(dentry))
2377 goto out_unlock;
2378
Dave Hansen75c3f292008-02-15 14:37:45 -08002379 error = mnt_want_write(nd.path.mnt);
2380 if (error)
2381 goto out_dput;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002382 error = security_path_symlink(&nd.path, dentry, from);
2383 if (error)
2384 goto out_drop_write;
Miklos Szeredidb2e7472008-06-24 16:50:16 +02002385 error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002386out_drop_write:
Dave Hansen75c3f292008-02-15 14:37:45 -08002387 mnt_drop_write(nd.path.mnt);
2388out_dput:
Dave Hansen6902d922006-09-30 23:29:01 -07002389 dput(dentry);
2390out_unlock:
Jan Blunck4ac91372008-02-14 19:34:32 -08002391 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Jan Blunck1d957f92008-02-14 19:34:35 -08002392 path_put(&nd.path);
Dave Hansen6902d922006-09-30 23:29:01 -07002393 putname(to);
2394out_putname:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002395 putname(from);
2396 return error;
2397}
2398
Heiko Carstens3480b252009-01-14 14:14:16 +01002399SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002400{
2401 return sys_symlinkat(oldname, AT_FDCWD, newname);
2402}
2403
Linus Torvalds1da177e2005-04-16 15:20:36 -07002404int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2405{
2406 struct inode *inode = old_dentry->d_inode;
2407 int error;
2408
2409 if (!inode)
2410 return -ENOENT;
2411
Miklos Szeredia95164d2008-07-30 15:08:48 +02002412 error = may_create(dir, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002413 if (error)
2414 return error;
2415
2416 if (dir->i_sb != inode->i_sb)
2417 return -EXDEV;
2418
2419 /*
2420 * A link to an append-only or immutable file cannot be created.
2421 */
2422 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2423 return -EPERM;
Al Viroacfa4382008-12-04 10:06:33 -05002424 if (!dir->i_op->link)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002425 return -EPERM;
Tetsuo Handa7e79eed2008-06-24 16:50:15 +02002426 if (S_ISDIR(inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 return -EPERM;
2428
2429 error = security_inode_link(old_dentry, dir, new_dentry);
2430 if (error)
2431 return error;
2432
Tetsuo Handa7e79eed2008-06-24 16:50:15 +02002433 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 error = dir->i_op->link(old_dentry, dir, new_dentry);
Tetsuo Handa7e79eed2008-06-24 16:50:15 +02002435 mutex_unlock(&inode->i_mutex);
Stephen Smalleye31e14e2005-09-09 13:01:45 -07002436 if (!error)
Tetsuo Handa7e79eed2008-06-24 16:50:15 +02002437 fsnotify_link(dir, inode, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002438 return error;
2439}
2440
2441/*
2442 * Hardlinks are often used in delicate situations. We avoid
2443 * security-related surprises by not following symlinks on the
2444 * newname. --KAB
2445 *
2446 * We don't follow them on the oldname either to be compatible
2447 * with linux 2.0, and to avoid hard-linking to directories
2448 * and other special files. --ADM
2449 */
Heiko Carstens2e4d0922009-01-14 14:14:31 +01002450SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2451 int, newdfd, const char __user *, newname, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002452{
2453 struct dentry *new_dentry;
Al Viro2d8f3032008-07-22 09:59:21 -04002454 struct nameidata nd;
2455 struct path old_path;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002456 int error;
Al Viro2ad94ae2008-07-21 09:32:51 -04002457 char *to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002458
Ulrich Drepper45c9b112006-06-25 05:49:11 -07002459 if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
Ulrich Drepperc04030e2006-02-24 13:04:21 -08002460 return -EINVAL;
2461
Al Viro2d8f3032008-07-22 09:59:21 -04002462 error = user_path_at(olddfd, oldname,
2463 flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
2464 &old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465 if (error)
Al Viro2ad94ae2008-07-21 09:32:51 -04002466 return error;
2467
2468 error = user_path_parent(newdfd, newname, &nd, &to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469 if (error)
2470 goto out;
2471 error = -EXDEV;
Al Viro2d8f3032008-07-22 09:59:21 -04002472 if (old_path.mnt != nd.path.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 goto out_release;
2474 new_dentry = lookup_create(&nd, 0);
2475 error = PTR_ERR(new_dentry);
Dave Hansen6902d922006-09-30 23:29:01 -07002476 if (IS_ERR(new_dentry))
2477 goto out_unlock;
Dave Hansen75c3f292008-02-15 14:37:45 -08002478 error = mnt_want_write(nd.path.mnt);
2479 if (error)
2480 goto out_dput;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002481 error = security_path_link(old_path.dentry, &nd.path, new_dentry);
2482 if (error)
2483 goto out_drop_write;
Al Viro2d8f3032008-07-22 09:59:21 -04002484 error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002485out_drop_write:
Dave Hansen75c3f292008-02-15 14:37:45 -08002486 mnt_drop_write(nd.path.mnt);
2487out_dput:
Dave Hansen6902d922006-09-30 23:29:01 -07002488 dput(new_dentry);
2489out_unlock:
Jan Blunck4ac91372008-02-14 19:34:32 -08002490 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491out_release:
Jan Blunck1d957f92008-02-14 19:34:35 -08002492 path_put(&nd.path);
Al Viro2ad94ae2008-07-21 09:32:51 -04002493 putname(to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002494out:
Al Viro2d8f3032008-07-22 09:59:21 -04002495 path_put(&old_path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002496
2497 return error;
2498}
2499
Heiko Carstens3480b252009-01-14 14:14:16 +01002500SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002501{
Ulrich Drepperc04030e2006-02-24 13:04:21 -08002502 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002503}
2504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505/*
2506 * The worst of all namespace operations - renaming directory. "Perverted"
2507 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2508 * Problems:
2509 * a) we can get into loop creation. Check is done in is_subdir().
2510 * b) race potential - two innocent renames can create a loop together.
2511 * That's where 4.4 screws up. Current fix: serialization on
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002512 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513 * story.
2514 * c) we have to lock _three_ objects - parents and victim (if it exists).
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002515 * And that - after we got ->i_mutex on parents (until then we don't know
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 * whether the target exists). Solution: try to be smart with locking
2517 * order for inodes. We rely on the fact that tree topology may change
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002518 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
Linus Torvalds1da177e2005-04-16 15:20:36 -07002519 * move will be locked. Thus we can rank directories by the tree
2520 * (ancestors first) and rank all non-directories after them.
2521 * That works since everybody except rename does "lock parent, lookup,
Arjan van de Vena11f3a02006-03-23 03:00:33 -08002522 * lock child" and rename is under ->s_vfs_rename_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 * HOWEVER, it relies on the assumption that any object with ->lookup()
2524 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2525 * we'd better make sure that there's no link(2) for them.
2526 * d) some filesystems don't support opened-but-unlinked directories,
2527 * either because of layout or because they are not ready to deal with
2528 * all cases correctly. The latter will be fixed (taking this sort of
2529 * stuff into VFS), but the former is not going away. Solution: the same
2530 * trick as in rmdir().
2531 * e) conversion from fhandle to dentry may come in the wrong moment - when
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002532 * we are removing the target. Solution: we will have to grab ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
Adam Buchbinderc41b20e2009-12-11 16:35:39 -05002534 * ->i_mutex on parents, which works but leads to some truly excessive
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535 * locking].
2536 */
Adrian Bunk75c96f82005-05-05 16:16:09 -07002537static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2538 struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539{
2540 int error = 0;
2541 struct inode *target;
2542
2543 /*
2544 * If we are going to change the parent - check write permissions,
2545 * we'll need to flip '..'.
2546 */
2547 if (new_dir != old_dir) {
Al Virof419a2e2008-07-22 00:07:17 -04002548 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002549 if (error)
2550 return error;
2551 }
2552
2553 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2554 if (error)
2555 return error;
2556
2557 target = new_dentry->d_inode;
Al Virod83c49f2010-04-30 17:17:09 -04002558 if (target)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002559 mutex_lock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2561 error = -EBUSY;
Al Virod83c49f2010-04-30 17:17:09 -04002562 else {
2563 if (target)
2564 dentry_unhash(new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
Al Virod83c49f2010-04-30 17:17:09 -04002566 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567 if (target) {
Al Virod83c49f2010-04-30 17:17:09 -04002568 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002569 target->i_flags |= S_DEAD;
Al Virod83c49f2010-04-30 17:17:09 -04002570 dont_mount(new_dentry);
2571 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002572 mutex_unlock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573 if (d_unhashed(new_dentry))
2574 d_rehash(new_dentry);
2575 dput(new_dentry);
2576 }
Stephen Smalleye31e14e2005-09-09 13:01:45 -07002577 if (!error)
Mark Fasheh349457c2006-09-08 14:22:21 -07002578 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2579 d_move(old_dentry,new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002580 return error;
2581}
2582
Adrian Bunk75c96f82005-05-05 16:16:09 -07002583static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2584 struct inode *new_dir, struct dentry *new_dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002585{
2586 struct inode *target;
2587 int error;
2588
2589 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2590 if (error)
2591 return error;
2592
2593 dget(new_dentry);
2594 target = new_dentry->d_inode;
2595 if (target)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002596 mutex_lock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2598 error = -EBUSY;
2599 else
2600 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2601 if (!error) {
Al Virobec10522010-03-03 14:12:08 -05002602 if (target)
Al Virod83c49f2010-04-30 17:17:09 -04002603 dont_mount(new_dentry);
Mark Fasheh349457c2006-09-08 14:22:21 -07002604 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002605 d_move(old_dentry, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606 }
2607 if (target)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002608 mutex_unlock(&target->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 dput(new_dentry);
2610 return error;
2611}
2612
2613int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2614 struct inode *new_dir, struct dentry *new_dentry)
2615{
2616 int error;
2617 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
Eric Paris59b0df22010-02-08 12:53:52 -05002618 const unsigned char *old_name;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002619
2620 if (old_dentry->d_inode == new_dentry->d_inode)
2621 return 0;
2622
2623 error = may_delete(old_dir, old_dentry, is_dir);
2624 if (error)
2625 return error;
2626
2627 if (!new_dentry->d_inode)
Miklos Szeredia95164d2008-07-30 15:08:48 +02002628 error = may_create(new_dir, new_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629 else
2630 error = may_delete(new_dir, new_dentry, is_dir);
2631 if (error)
2632 return error;
2633
Al Viroacfa4382008-12-04 10:06:33 -05002634 if (!old_dir->i_op->rename)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002635 return -EPERM;
2636
Robert Love0eeca282005-07-12 17:06:03 -04002637 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
2638
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639 if (is_dir)
2640 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
2641 else
2642 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
Al Viro123df292009-12-25 04:57:57 -05002643 if (!error)
2644 fsnotify_move(old_dir, new_dir, old_name, is_dir,
Al Viro5a190ae2007-06-07 12:19:32 -04002645 new_dentry->d_inode, old_dentry);
Robert Love0eeca282005-07-12 17:06:03 -04002646 fsnotify_oldname_free(old_name);
2647
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648 return error;
2649}
2650
Heiko Carstens2e4d0922009-01-14 14:14:31 +01002651SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
2652 int, newdfd, const char __user *, newname)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002653{
Al Viro2ad94ae2008-07-21 09:32:51 -04002654 struct dentry *old_dir, *new_dir;
2655 struct dentry *old_dentry, *new_dentry;
2656 struct dentry *trap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 struct nameidata oldnd, newnd;
Al Viro2ad94ae2008-07-21 09:32:51 -04002658 char *from;
2659 char *to;
2660 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661
Al Viro2ad94ae2008-07-21 09:32:51 -04002662 error = user_path_parent(olddfd, oldname, &oldnd, &from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663 if (error)
2664 goto exit;
2665
Al Viro2ad94ae2008-07-21 09:32:51 -04002666 error = user_path_parent(newdfd, newname, &newnd, &to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002667 if (error)
2668 goto exit1;
2669
2670 error = -EXDEV;
Jan Blunck4ac91372008-02-14 19:34:32 -08002671 if (oldnd.path.mnt != newnd.path.mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002672 goto exit2;
2673
Jan Blunck4ac91372008-02-14 19:34:32 -08002674 old_dir = oldnd.path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002675 error = -EBUSY;
2676 if (oldnd.last_type != LAST_NORM)
2677 goto exit2;
2678
Jan Blunck4ac91372008-02-14 19:34:32 -08002679 new_dir = newnd.path.dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680 if (newnd.last_type != LAST_NORM)
2681 goto exit2;
2682
OGAWA Hirofumi0612d9f2008-10-16 07:50:29 +09002683 oldnd.flags &= ~LOOKUP_PARENT;
2684 newnd.flags &= ~LOOKUP_PARENT;
OGAWA Hirofumi4e9ed2f2008-10-16 07:50:29 +09002685 newnd.flags |= LOOKUP_RENAME_TARGET;
OGAWA Hirofumi0612d9f2008-10-16 07:50:29 +09002686
Linus Torvalds1da177e2005-04-16 15:20:36 -07002687 trap = lock_rename(new_dir, old_dir);
2688
Christoph Hellwig49705b72005-11-08 21:35:06 -08002689 old_dentry = lookup_hash(&oldnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002690 error = PTR_ERR(old_dentry);
2691 if (IS_ERR(old_dentry))
2692 goto exit3;
2693 /* source must exist */
2694 error = -ENOENT;
2695 if (!old_dentry->d_inode)
2696 goto exit4;
2697 /* unless the source is a directory trailing slashes give -ENOTDIR */
2698 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
2699 error = -ENOTDIR;
2700 if (oldnd.last.name[oldnd.last.len])
2701 goto exit4;
2702 if (newnd.last.name[newnd.last.len])
2703 goto exit4;
2704 }
2705 /* source should not be ancestor of target */
2706 error = -EINVAL;
2707 if (old_dentry == trap)
2708 goto exit4;
Christoph Hellwig49705b72005-11-08 21:35:06 -08002709 new_dentry = lookup_hash(&newnd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002710 error = PTR_ERR(new_dentry);
2711 if (IS_ERR(new_dentry))
2712 goto exit4;
2713 /* target should not be an ancestor of source */
2714 error = -ENOTEMPTY;
2715 if (new_dentry == trap)
2716 goto exit5;
2717
Dave Hansen9079b1e2008-02-15 14:37:49 -08002718 error = mnt_want_write(oldnd.path.mnt);
2719 if (error)
2720 goto exit5;
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002721 error = security_path_rename(&oldnd.path, old_dentry,
2722 &newnd.path, new_dentry);
2723 if (error)
2724 goto exit6;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002725 error = vfs_rename(old_dir->d_inode, old_dentry,
2726 new_dir->d_inode, new_dentry);
Kentaro Takedabe6d3e52008-12-17 13:24:15 +09002727exit6:
Dave Hansen9079b1e2008-02-15 14:37:49 -08002728 mnt_drop_write(oldnd.path.mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002729exit5:
2730 dput(new_dentry);
2731exit4:
2732 dput(old_dentry);
2733exit3:
2734 unlock_rename(new_dir, old_dir);
2735exit2:
Jan Blunck1d957f92008-02-14 19:34:35 -08002736 path_put(&newnd.path);
Al Viro2ad94ae2008-07-21 09:32:51 -04002737 putname(to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738exit1:
Jan Blunck1d957f92008-02-14 19:34:35 -08002739 path_put(&oldnd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002740 putname(from);
Al Viro2ad94ae2008-07-21 09:32:51 -04002741exit:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742 return error;
2743}
2744
Heiko Carstensa26eab22009-01-14 14:14:17 +01002745SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
Ulrich Drepper5590ff02006-01-18 17:43:53 -08002746{
2747 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
2748}
2749
Linus Torvalds1da177e2005-04-16 15:20:36 -07002750int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
2751{
2752 int len;
2753
2754 len = PTR_ERR(link);
2755 if (IS_ERR(link))
2756 goto out;
2757
2758 len = strlen(link);
2759 if (len > (unsigned) buflen)
2760 len = buflen;
2761 if (copy_to_user(buffer, link, len))
2762 len = -EFAULT;
2763out:
2764 return len;
2765}
2766
2767/*
2768 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2769 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2770 * using) it for any given inode is up to filesystem.
2771 */
2772int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2773{
2774 struct nameidata nd;
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002775 void *cookie;
Marcin Slusarz694a1762008-06-09 16:40:37 -07002776 int res;
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002777
Linus Torvalds1da177e2005-04-16 15:20:36 -07002778 nd.depth = 0;
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002779 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
Marcin Slusarz694a1762008-06-09 16:40:37 -07002780 if (IS_ERR(cookie))
2781 return PTR_ERR(cookie);
2782
2783 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
2784 if (dentry->d_inode->i_op->put_link)
2785 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
2786 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002787}
2788
2789int vfs_follow_link(struct nameidata *nd, const char *link)
2790{
2791 return __vfs_follow_link(nd, link);
2792}
2793
2794/* get the link contents into pagecache */
2795static char *page_getlink(struct dentry * dentry, struct page **ppage)
2796{
Duane Griffinebd09ab2008-12-19 20:47:12 +00002797 char *kaddr;
2798 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799 struct address_space *mapping = dentry->d_inode->i_mapping;
Pekka Enberg090d2b12006-06-23 02:05:08 -07002800 page = read_mapping_page(mapping, 0, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002801 if (IS_ERR(page))
Nick Piggin6fe69002007-05-06 14:49:04 -07002802 return (char*)page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803 *ppage = page;
Duane Griffinebd09ab2008-12-19 20:47:12 +00002804 kaddr = kmap(page);
2805 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
2806 return kaddr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002807}
2808
2809int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
2810{
2811 struct page *page = NULL;
2812 char *s = page_getlink(dentry, &page);
2813 int res = vfs_readlink(dentry,buffer,buflen,s);
2814 if (page) {
2815 kunmap(page);
2816 page_cache_release(page);
2817 }
2818 return res;
2819}
2820
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002821void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002822{
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002823 struct page *page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002824 nd_set_link(nd, page_getlink(dentry, &page));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002825 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826}
2827
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002828void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002829{
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002830 struct page *page = cookie;
2831
2832 if (page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002833 kunmap(page);
2834 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002835 }
2836}
2837
Nick Piggin54566b22009-01-04 12:00:53 -08002838/*
2839 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2840 */
2841int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842{
2843 struct address_space *mapping = inode->i_mapping;
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002844 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002845 void *fsdata;
Dmitriy Monakhovbeb497a2007-02-16 01:27:18 -08002846 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847 char *kaddr;
Nick Piggin54566b22009-01-04 12:00:53 -08002848 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
2849 if (nofs)
2850 flags |= AOP_FLAG_NOFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002851
NeilBrown7e53cac2006-03-25 03:07:57 -08002852retry:
Nick Pigginafddba42007-10-16 01:25:01 -07002853 err = pagecache_write_begin(NULL, mapping, 0, len-1,
Nick Piggin54566b22009-01-04 12:00:53 -08002854 flags, &page, &fsdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855 if (err)
Nick Pigginafddba42007-10-16 01:25:01 -07002856 goto fail;
2857
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858 kaddr = kmap_atomic(page, KM_USER0);
2859 memcpy(kaddr, symname, len-1);
2860 kunmap_atomic(kaddr, KM_USER0);
Nick Pigginafddba42007-10-16 01:25:01 -07002861
2862 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
2863 page, fsdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864 if (err < 0)
2865 goto fail;
Nick Pigginafddba42007-10-16 01:25:01 -07002866 if (err < len-1)
2867 goto retry;
2868
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869 mark_inode_dirty(inode);
2870 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871fail:
2872 return err;
2873}
2874
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002875int page_symlink(struct inode *inode, const char *symname, int len)
2876{
2877 return __page_symlink(inode, symname, len,
Nick Piggin54566b22009-01-04 12:00:53 -08002878 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002879}
2880
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002881const struct inode_operations page_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882 .readlink = generic_readlink,
2883 .follow_link = page_follow_link_light,
2884 .put_link = page_put_link,
2885};
2886
Al Viro2d8f3032008-07-22 09:59:21 -04002887EXPORT_SYMBOL(user_path_at);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002888EXPORT_SYMBOL(follow_down);
2889EXPORT_SYMBOL(follow_up);
2890EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
2891EXPORT_SYMBOL(getname);
2892EXPORT_SYMBOL(lock_rename);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002893EXPORT_SYMBOL(lookup_one_len);
2894EXPORT_SYMBOL(page_follow_link_light);
2895EXPORT_SYMBOL(page_put_link);
2896EXPORT_SYMBOL(page_readlink);
Kirill Korotaev0adb25d2006-03-11 03:27:13 -08002897EXPORT_SYMBOL(__page_symlink);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002898EXPORT_SYMBOL(page_symlink);
2899EXPORT_SYMBOL(page_symlink_inode_operations);
2900EXPORT_SYMBOL(path_lookup);
Al Virod1811462008-08-02 00:49:18 -04002901EXPORT_SYMBOL(kern_path);
Josef 'Jeff' Sipek16f18202007-07-19 01:48:18 -07002902EXPORT_SYMBOL(vfs_path_lookup);
Al Virof419a2e2008-07-22 00:07:17 -04002903EXPORT_SYMBOL(inode_permission);
Christoph Hellwig8c744fb2005-11-08 21:35:04 -08002904EXPORT_SYMBOL(file_permission);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002905EXPORT_SYMBOL(unlock_rename);
2906EXPORT_SYMBOL(vfs_create);
2907EXPORT_SYMBOL(vfs_follow_link);
2908EXPORT_SYMBOL(vfs_link);
2909EXPORT_SYMBOL(vfs_mkdir);
2910EXPORT_SYMBOL(vfs_mknod);
2911EXPORT_SYMBOL(generic_permission);
2912EXPORT_SYMBOL(vfs_readlink);
2913EXPORT_SYMBOL(vfs_rename);
2914EXPORT_SYMBOL(vfs_rmdir);
2915EXPORT_SYMBOL(vfs_symlink);
2916EXPORT_SYMBOL(vfs_unlink);
2917EXPORT_SYMBOL(dentry_unhash);
2918EXPORT_SYMBOL(generic_readlink);