blob: 4706a8b1f4959cdf955cc8b625ee5bac3b53ccf7 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 File: fs/xattr.c
3
4 Extended attribute handling.
5
6 Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
7 Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
8 Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
9 */
10#include <linux/fs.h>
11#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/file.h>
13#include <linux/xattr.h>
Dave Hansen18f335a2008-02-15 14:37:38 -080014#include <linux/mount.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/namei.h>
16#include <linux/security.h>
17#include <linux/syscalls.h>
18#include <linux/module.h>
Robert Love0eeca282005-07-12 17:06:03 -040019#include <linux/fsnotify.h>
Amy Griffis73241cc2005-11-03 16:00:25 +000020#include <linux/audit.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <asm/uaccess.h>
22
Christoph Hellwig5be196e2006-01-09 20:51:55 -080023
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080024/*
25 * Check permissions for extended attribute access. This is a bit complicated
26 * because different namespaces have very different rules.
27 */
28static int
29xattr_permission(struct inode *inode, const char *name, int mask)
30{
31 /*
32 * We can never set or remove an extended attribute on a read-only
33 * filesystem or on an immutable / append-only inode.
34 */
35 if (mask & MAY_WRITE) {
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080036 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
37 return -EPERM;
38 }
39
40 /*
41 * No restriction for security.* and system.* from the VFS. Decision
42 * on these is left to the underlying filesystem / security module.
43 */
44 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
45 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
46 return 0;
47
48 /*
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080049 * The trusted.* namespace can only be accessed by a privileged user.
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080050 */
51 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
52 return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
53
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080054 /* In user.* namespace, only regular files and directories can have
55 * extended attributes. For sticky directories, only the owner and
56 * privileged user can write attributes.
57 */
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080058 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080059 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
60 return -EPERM;
61 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
Satyam Sharma3bd858a2007-07-17 15:00:08 +053062 (mask & MAY_WRITE) && !is_owner_or_cap(inode))
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080063 return -EPERM;
64 }
65
66 return permission(inode, mask, NULL);
67}
68
Christoph Hellwig5be196e2006-01-09 20:51:55 -080069int
David Howells8f0cfa52008-04-29 00:59:41 -070070vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
Christoph Hellwig5be196e2006-01-09 20:51:55 -080071 size_t size, int flags)
72{
73 struct inode *inode = dentry->d_inode;
74 int error;
75
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080076 error = xattr_permission(inode, name, MAY_WRITE);
77 if (error)
78 return error;
79
Christoph Hellwig5be196e2006-01-09 20:51:55 -080080 mutex_lock(&inode->i_mutex);
81 error = security_inode_setxattr(dentry, name, value, size, flags);
82 if (error)
83 goto out;
84 error = -EOPNOTSUPP;
85 if (inode->i_op->setxattr) {
86 error = inode->i_op->setxattr(dentry, name, value, size, flags);
87 if (!error) {
88 fsnotify_xattr(dentry);
89 security_inode_post_setxattr(dentry, name, value,
90 size, flags);
91 }
92 } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080093 XATTR_SECURITY_PREFIX_LEN)) {
94 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -080095 error = security_inode_setsecurity(inode, suffix, value,
96 size, flags);
97 if (!error)
98 fsnotify_xattr(dentry);
99 }
100out:
101 mutex_unlock(&inode->i_mutex);
102 return error;
103}
104EXPORT_SYMBOL_GPL(vfs_setxattr);
105
106ssize_t
David P. Quigley42492592008-02-04 22:29:39 -0800107xattr_getsecurity(struct inode *inode, const char *name, void *value,
108 size_t size)
109{
110 void *buffer = NULL;
111 ssize_t len;
112
113 if (!value || !size) {
114 len = security_inode_getsecurity(inode, name, &buffer, false);
115 goto out_noalloc;
116 }
117
118 len = security_inode_getsecurity(inode, name, &buffer, true);
119 if (len < 0)
120 return len;
121 if (size < len) {
122 len = -ERANGE;
123 goto out;
124 }
125 memcpy(value, buffer, len);
126out:
127 security_release_secctx(buffer, len);
128out_noalloc:
129 return len;
130}
131EXPORT_SYMBOL_GPL(xattr_getsecurity);
132
133ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700134vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800135{
136 struct inode *inode = dentry->d_inode;
137 int error;
138
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800139 error = xattr_permission(inode, name, MAY_READ);
140 if (error)
141 return error;
142
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800143 error = security_inode_getxattr(dentry, name);
144 if (error)
145 return error;
146
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800147 if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800148 XATTR_SECURITY_PREFIX_LEN)) {
149 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
David P. Quigley42492592008-02-04 22:29:39 -0800150 int ret = xattr_getsecurity(inode, suffix, value, size);
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800151 /*
152 * Only overwrite the return value if a security module
153 * is actually active.
154 */
David P. Quigley4bea5802008-02-04 22:29:40 -0800155 if (ret == -EOPNOTSUPP)
156 goto nolsm;
157 return ret;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800158 }
David P. Quigley4bea5802008-02-04 22:29:40 -0800159nolsm:
160 if (inode->i_op->getxattr)
161 error = inode->i_op->getxattr(dentry, name, value, size);
162 else
163 error = -EOPNOTSUPP;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800164
165 return error;
166}
167EXPORT_SYMBOL_GPL(vfs_getxattr);
168
Bill Nottingham659564c2006-10-09 16:10:48 -0400169ssize_t
170vfs_listxattr(struct dentry *d, char *list, size_t size)
171{
172 ssize_t error;
173
174 error = security_inode_listxattr(d);
175 if (error)
176 return error;
177 error = -EOPNOTSUPP;
178 if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
179 error = d->d_inode->i_op->listxattr(d, list, size);
180 } else {
181 error = security_inode_listsecurity(d->d_inode, list, size);
182 if (size && error > size)
183 error = -ERANGE;
184 }
185 return error;
186}
187EXPORT_SYMBOL_GPL(vfs_listxattr);
188
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800189int
David Howells8f0cfa52008-04-29 00:59:41 -0700190vfs_removexattr(struct dentry *dentry, const char *name)
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800191{
192 struct inode *inode = dentry->d_inode;
193 int error;
194
195 if (!inode->i_op->removexattr)
196 return -EOPNOTSUPP;
197
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800198 error = xattr_permission(inode, name, MAY_WRITE);
199 if (error)
200 return error;
201
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800202 error = security_inode_removexattr(dentry, name);
203 if (error)
204 return error;
205
206 mutex_lock(&inode->i_mutex);
207 error = inode->i_op->removexattr(dentry, name);
208 mutex_unlock(&inode->i_mutex);
209
210 if (!error)
211 fsnotify_xattr(dentry);
212 return error;
213}
214EXPORT_SYMBOL_GPL(vfs_removexattr);
215
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217/*
218 * Extended attribute SET operations
219 */
220static long
David Howells8f0cfa52008-04-29 00:59:41 -0700221setxattr(struct dentry *d, const char __user *name, const void __user *value,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 size_t size, int flags)
223{
224 int error;
225 void *kvalue = NULL;
226 char kname[XATTR_NAME_MAX + 1];
227
228 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
229 return -EINVAL;
230
231 error = strncpy_from_user(kname, name, sizeof(kname));
232 if (error == 0 || error == sizeof(kname))
233 error = -ERANGE;
234 if (error < 0)
235 return error;
236
237 if (size) {
238 if (size > XATTR_SIZE_MAX)
239 return -E2BIG;
240 kvalue = kmalloc(size, GFP_KERNEL);
241 if (!kvalue)
242 return -ENOMEM;
243 if (copy_from_user(kvalue, value, size)) {
244 kfree(kvalue);
245 return -EFAULT;
246 }
247 }
248
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800249 error = vfs_setxattr(d, kname, kvalue, size, flags);
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800250 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 return error;
252}
253
254asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700255sys_setxattr(const char __user *path, const char __user *name,
256 const void __user *value, size_t size, int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
258 struct nameidata nd;
259 int error;
260
261 error = user_path_walk(path, &nd);
262 if (error)
263 return error;
Dave Hansen18f335a2008-02-15 14:37:38 -0800264 error = mnt_want_write(nd.path.mnt);
265 if (!error) {
266 error = setxattr(nd.path.dentry, name, value, size, flags);
267 mnt_drop_write(nd.path.mnt);
268 }
Jan Blunck1d957f92008-02-14 19:34:35 -0800269 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 return error;
271}
272
273asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700274sys_lsetxattr(const char __user *path, const char __user *name,
275 const void __user *value, size_t size, int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276{
277 struct nameidata nd;
278 int error;
279
280 error = user_path_walk_link(path, &nd);
281 if (error)
282 return error;
Dave Hansen18f335a2008-02-15 14:37:38 -0800283 error = mnt_want_write(nd.path.mnt);
284 if (!error) {
285 error = setxattr(nd.path.dentry, name, value, size, flags);
286 mnt_drop_write(nd.path.mnt);
287 }
Jan Blunck1d957f92008-02-14 19:34:35 -0800288 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 return error;
290}
291
292asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700293sys_fsetxattr(int fd, const char __user *name, const void __user *value,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 size_t size, int flags)
295{
296 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000297 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 int error = -EBADF;
299
300 f = fget(fd);
301 if (!f)
302 return error;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800303 dentry = f->f_path.dentry;
Al Viro5a190ae2007-06-07 12:19:32 -0400304 audit_inode(NULL, dentry);
Dave Hansen18f335a2008-02-15 14:37:38 -0800305 error = mnt_want_write(f->f_path.mnt);
306 if (!error) {
307 error = setxattr(dentry, name, value, size, flags);
308 mnt_drop_write(f->f_path.mnt);
309 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 fput(f);
311 return error;
312}
313
314/*
315 * Extended attribute GET operations
316 */
317static ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700318getxattr(struct dentry *d, const char __user *name, void __user *value,
319 size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320{
321 ssize_t error;
322 void *kvalue = NULL;
323 char kname[XATTR_NAME_MAX + 1];
324
325 error = strncpy_from_user(kname, name, sizeof(kname));
326 if (error == 0 || error == sizeof(kname))
327 error = -ERANGE;
328 if (error < 0)
329 return error;
330
331 if (size) {
332 if (size > XATTR_SIZE_MAX)
333 size = XATTR_SIZE_MAX;
James Morrisd381d8a2005-10-30 14:59:22 -0800334 kvalue = kzalloc(size, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 if (!kvalue)
336 return -ENOMEM;
337 }
338
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800339 error = vfs_getxattr(d, kname, kvalue, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700340 if (error > 0) {
341 if (size && copy_to_user(value, kvalue, error))
342 error = -EFAULT;
343 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
344 /* The file system tried to returned a value bigger
345 than XATTR_SIZE_MAX bytes. Not possible. */
346 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800348 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 return error;
350}
351
352asmlinkage ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700353sys_getxattr(const char __user *path, const char __user *name,
354 void __user *value, size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355{
356 struct nameidata nd;
357 ssize_t error;
358
359 error = user_path_walk(path, &nd);
360 if (error)
361 return error;
Jan Blunck4ac91372008-02-14 19:34:32 -0800362 error = getxattr(nd.path.dentry, name, value, size);
Jan Blunck1d957f92008-02-14 19:34:35 -0800363 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 return error;
365}
366
367asmlinkage ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700368sys_lgetxattr(const char __user *path, const char __user *name, void __user *value,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 size_t size)
370{
371 struct nameidata nd;
372 ssize_t error;
373
374 error = user_path_walk_link(path, &nd);
375 if (error)
376 return error;
Jan Blunck4ac91372008-02-14 19:34:32 -0800377 error = getxattr(nd.path.dentry, name, value, size);
Jan Blunck1d957f92008-02-14 19:34:35 -0800378 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 return error;
380}
381
382asmlinkage ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700383sys_fgetxattr(int fd, const char __user *name, void __user *value, size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384{
385 struct file *f;
386 ssize_t error = -EBADF;
387
388 f = fget(fd);
389 if (!f)
390 return error;
Al Viro5a190ae2007-06-07 12:19:32 -0400391 audit_inode(NULL, f->f_path.dentry);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800392 error = getxattr(f->f_path.dentry, name, value, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 fput(f);
394 return error;
395}
396
397/*
398 * Extended attribute LIST operations
399 */
400static ssize_t
401listxattr(struct dentry *d, char __user *list, size_t size)
402{
403 ssize_t error;
404 char *klist = NULL;
405
406 if (size) {
407 if (size > XATTR_LIST_MAX)
408 size = XATTR_LIST_MAX;
409 klist = kmalloc(size, GFP_KERNEL);
410 if (!klist)
411 return -ENOMEM;
412 }
413
Bill Nottingham659564c2006-10-09 16:10:48 -0400414 error = vfs_listxattr(d, klist, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700415 if (error > 0) {
416 if (size && copy_to_user(list, klist, error))
417 error = -EFAULT;
418 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
419 /* The file system tried to returned a list bigger
420 than XATTR_LIST_MAX bytes. Not possible. */
421 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 }
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800423 kfree(klist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 return error;
425}
426
427asmlinkage ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700428sys_listxattr(const char __user *path, char __user *list, size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429{
430 struct nameidata nd;
431 ssize_t error;
432
433 error = user_path_walk(path, &nd);
434 if (error)
435 return error;
Jan Blunck4ac91372008-02-14 19:34:32 -0800436 error = listxattr(nd.path.dentry, list, size);
Jan Blunck1d957f92008-02-14 19:34:35 -0800437 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 return error;
439}
440
441asmlinkage ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700442sys_llistxattr(const char __user *path, char __user *list, size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443{
444 struct nameidata nd;
445 ssize_t error;
446
447 error = user_path_walk_link(path, &nd);
448 if (error)
449 return error;
Jan Blunck4ac91372008-02-14 19:34:32 -0800450 error = listxattr(nd.path.dentry, list, size);
Jan Blunck1d957f92008-02-14 19:34:35 -0800451 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 return error;
453}
454
455asmlinkage ssize_t
456sys_flistxattr(int fd, char __user *list, size_t size)
457{
458 struct file *f;
459 ssize_t error = -EBADF;
460
461 f = fget(fd);
462 if (!f)
463 return error;
Al Viro5a190ae2007-06-07 12:19:32 -0400464 audit_inode(NULL, f->f_path.dentry);
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800465 error = listxattr(f->f_path.dentry, list, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 fput(f);
467 return error;
468}
469
470/*
471 * Extended attribute REMOVE operations
472 */
473static long
David Howells8f0cfa52008-04-29 00:59:41 -0700474removexattr(struct dentry *d, const char __user *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475{
476 int error;
477 char kname[XATTR_NAME_MAX + 1];
478
479 error = strncpy_from_user(kname, name, sizeof(kname));
480 if (error == 0 || error == sizeof(kname))
481 error = -ERANGE;
482 if (error < 0)
483 return error;
484
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800485 return vfs_removexattr(d, kname);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486}
487
488asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700489sys_removexattr(const char __user *path, const char __user *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490{
491 struct nameidata nd;
492 int error;
493
494 error = user_path_walk(path, &nd);
495 if (error)
496 return error;
Dave Hansen18f335a2008-02-15 14:37:38 -0800497 error = mnt_want_write(nd.path.mnt);
498 if (!error) {
499 error = removexattr(nd.path.dentry, name);
500 mnt_drop_write(nd.path.mnt);
501 }
Jan Blunck1d957f92008-02-14 19:34:35 -0800502 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 return error;
504}
505
506asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700507sys_lremovexattr(const char __user *path, const char __user *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508{
509 struct nameidata nd;
510 int error;
511
512 error = user_path_walk_link(path, &nd);
513 if (error)
514 return error;
Dave Hansen18f335a2008-02-15 14:37:38 -0800515 error = mnt_want_write(nd.path.mnt);
516 if (!error) {
517 error = removexattr(nd.path.dentry, name);
518 mnt_drop_write(nd.path.mnt);
519 }
Jan Blunck1d957f92008-02-14 19:34:35 -0800520 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 return error;
522}
523
524asmlinkage long
David Howells8f0cfa52008-04-29 00:59:41 -0700525sys_fremovexattr(int fd, const char __user *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526{
527 struct file *f;
Amy Griffis73241cc2005-11-03 16:00:25 +0000528 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 int error = -EBADF;
530
531 f = fget(fd);
532 if (!f)
533 return error;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800534 dentry = f->f_path.dentry;
Al Viro5a190ae2007-06-07 12:19:32 -0400535 audit_inode(NULL, dentry);
Dave Hansen18f335a2008-02-15 14:37:38 -0800536 error = mnt_want_write(f->f_path.mnt);
537 if (!error) {
538 error = removexattr(dentry, name);
539 mnt_drop_write(f->f_path.mnt);
540 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 fput(f);
542 return error;
543}
544
545
546static const char *
547strcmp_prefix(const char *a, const char *a_prefix)
548{
549 while (*a_prefix && *a == *a_prefix) {
550 a++;
551 a_prefix++;
552 }
553 return *a_prefix ? NULL : a;
554}
555
556/*
557 * In order to implement different sets of xattr operations for each xattr
558 * prefix with the generic xattr API, a filesystem should create a
559 * null-terminated array of struct xattr_handler (one for each prefix) and
560 * hang a pointer to it off of the s_xattr field of the superblock.
561 *
562 * The generic_fooxattr() functions will use this list to dispatch xattr
563 * operations to the correct xattr_handler.
564 */
565#define for_each_xattr_handler(handlers, handler) \
566 for ((handler) = *(handlers)++; \
567 (handler) != NULL; \
568 (handler) = *(handlers)++)
569
570/*
571 * Find the xattr_handler with the matching prefix.
572 */
573static struct xattr_handler *
574xattr_resolve_name(struct xattr_handler **handlers, const char **name)
575{
576 struct xattr_handler *handler;
577
578 if (!*name)
579 return NULL;
580
581 for_each_xattr_handler(handlers, handler) {
582 const char *n = strcmp_prefix(*name, handler->prefix);
583 if (n) {
584 *name = n;
585 break;
586 }
587 }
588 return handler;
589}
590
591/*
592 * Find the handler for the prefix and dispatch its get() operation.
593 */
594ssize_t
595generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
596{
597 struct xattr_handler *handler;
598 struct inode *inode = dentry->d_inode;
599
600 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
601 if (!handler)
602 return -EOPNOTSUPP;
603 return handler->get(inode, name, buffer, size);
604}
605
606/*
607 * Combine the results of the list() operation from every xattr_handler in the
608 * list.
609 */
610ssize_t
611generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
612{
613 struct inode *inode = dentry->d_inode;
614 struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr;
615 unsigned int size = 0;
616
617 if (!buffer) {
618 for_each_xattr_handler(handlers, handler)
619 size += handler->list(inode, NULL, 0, NULL, 0);
620 } else {
621 char *buf = buffer;
622
623 for_each_xattr_handler(handlers, handler) {
624 size = handler->list(inode, buf, buffer_size, NULL, 0);
625 if (size > buffer_size)
626 return -ERANGE;
627 buf += size;
628 buffer_size -= size;
629 }
630 size = buf - buffer;
631 }
632 return size;
633}
634
635/*
636 * Find the handler for the prefix and dispatch its set() operation.
637 */
638int
639generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
640{
641 struct xattr_handler *handler;
642 struct inode *inode = dentry->d_inode;
643
644 if (size == 0)
645 value = ""; /* empty EA, do not remove */
646 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
647 if (!handler)
648 return -EOPNOTSUPP;
649 return handler->set(inode, name, value, size, flags);
650}
651
652/*
653 * Find the handler for the prefix and dispatch its set() operation to remove
654 * any associated extended attribute.
655 */
656int
657generic_removexattr(struct dentry *dentry, const char *name)
658{
659 struct xattr_handler *handler;
660 struct inode *inode = dentry->d_inode;
661
662 handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
663 if (!handler)
664 return -EOPNOTSUPP;
665 return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
666}
667
668EXPORT_SYMBOL(generic_getxattr);
669EXPORT_SYMBOL(generic_listxattr);
670EXPORT_SYMBOL(generic_setxattr);
671EXPORT_SYMBOL(generic_removexattr);