Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
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> | |
1da177e4 LT |
12 | #include <linux/file.h> |
13 | #include <linux/xattr.h> | |
18f335af | 14 | #include <linux/mount.h> |
1da177e4 LT |
15 | #include <linux/namei.h> |
16 | #include <linux/security.h> | |
c7b87de2 | 17 | #include <linux/evm.h> |
1da177e4 | 18 | #include <linux/syscalls.h> |
630d9c47 | 19 | #include <linux/export.h> |
0eeca283 | 20 | #include <linux/fsnotify.h> |
73241ccc | 21 | #include <linux/audit.h> |
0d08d7b7 | 22 | #include <linux/vmalloc.h> |
2f6f0654 | 23 | #include <linux/posix_acl_xattr.h> |
1da177e4 | 24 | |
0d08d7b7 | 25 | #include <asm/uaccess.h> |
5be196e5 | 26 | |
e0ad7b07 | 27 | /* |
28 | * Check permissions for extended attribute access. This is a bit complicated | |
29 | * because different namespaces have very different rules. | |
30 | */ | |
31 | static int | |
32 | xattr_permission(struct inode *inode, const char *name, int mask) | |
33 | { | |
34 | /* | |
35 | * We can never set or remove an extended attribute on a read-only | |
36 | * filesystem or on an immutable / append-only inode. | |
37 | */ | |
38 | if (mask & MAY_WRITE) { | |
e0ad7b07 | 39 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) |
40 | return -EPERM; | |
41 | } | |
42 | ||
43 | /* | |
44 | * No restriction for security.* and system.* from the VFS. Decision | |
45 | * on these is left to the underlying filesystem / security module. | |
46 | */ | |
47 | if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || | |
48 | !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
49 | return 0; | |
50 | ||
51 | /* | |
55b23bde | 52 | * The trusted.* namespace can only be accessed by privileged users. |
e0ad7b07 | 53 | */ |
55b23bde AG |
54 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { |
55 | if (!capable(CAP_SYS_ADMIN)) | |
56 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; | |
57 | return 0; | |
58 | } | |
e0ad7b07 | 59 | |
55b23bde AG |
60 | /* |
61 | * In the user.* namespace, only regular files and directories can have | |
f1f2d871 | 62 | * extended attributes. For sticky directories, only the owner and |
55b23bde | 63 | * privileged users can write attributes. |
f1f2d871 | 64 | */ |
e0ad7b07 | 65 | if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { |
f1f2d871 | 66 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
55b23bde | 67 | return (mask & MAY_WRITE) ? -EPERM : -ENODATA; |
f1f2d871 | 68 | if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && |
2e149670 | 69 | (mask & MAY_WRITE) && !inode_owner_or_capable(inode)) |
e0ad7b07 | 70 | return -EPERM; |
71 | } | |
72 | ||
f419a2e3 | 73 | return inode_permission(inode, mask); |
e0ad7b07 | 74 | } |
75 | ||
b1ab7e4b DQ |
76 | /** |
77 | * __vfs_setxattr_noperm - perform setxattr operation without performing | |
78 | * permission checks. | |
79 | * | |
80 | * @dentry - object to perform setxattr on | |
81 | * @name - xattr name to set | |
82 | * @value - value to set @name to | |
83 | * @size - size of @value | |
84 | * @flags - flags to pass into filesystem operations | |
85 | * | |
86 | * returns the result of the internal setxattr or setsecurity operations. | |
87 | * | |
88 | * This function requires the caller to lock the inode's i_mutex before it | |
89 | * is executed. It also assumes that the caller will make the appropriate | |
90 | * permission checks. | |
91 | */ | |
92 | int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, | |
93 | const void *value, size_t size, int flags) | |
5be196e5 CH |
94 | { |
95 | struct inode *inode = dentry->d_inode; | |
b1ab7e4b | 96 | int error = -EOPNOTSUPP; |
69b45732 AK |
97 | int issec = !strncmp(name, XATTR_SECURITY_PREFIX, |
98 | XATTR_SECURITY_PREFIX_LEN); | |
e0ad7b07 | 99 | |
69b45732 AK |
100 | if (issec) |
101 | inode->i_flags &= ~S_NOSEC; | |
5be196e5 CH |
102 | if (inode->i_op->setxattr) { |
103 | error = inode->i_op->setxattr(dentry, name, value, size, flags); | |
104 | if (!error) { | |
105 | fsnotify_xattr(dentry); | |
106 | security_inode_post_setxattr(dentry, name, value, | |
107 | size, flags); | |
108 | } | |
69b45732 | 109 | } else if (issec) { |
e0ad7b07 | 110 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
5be196e5 CH |
111 | error = security_inode_setsecurity(inode, suffix, value, |
112 | size, flags); | |
113 | if (!error) | |
114 | fsnotify_xattr(dentry); | |
115 | } | |
b1ab7e4b DQ |
116 | |
117 | return error; | |
118 | } | |
119 | ||
120 | ||
121 | int | |
122 | vfs_setxattr(struct dentry *dentry, const char *name, const void *value, | |
123 | size_t size, int flags) | |
124 | { | |
125 | struct inode *inode = dentry->d_inode; | |
126 | int error; | |
127 | ||
128 | error = xattr_permission(inode, name, MAY_WRITE); | |
129 | if (error) | |
130 | return error; | |
131 | ||
132 | mutex_lock(&inode->i_mutex); | |
133 | error = security_inode_setxattr(dentry, name, value, size, flags); | |
134 | if (error) | |
135 | goto out; | |
136 | ||
137 | error = __vfs_setxattr_noperm(dentry, name, value, size, flags); | |
138 | ||
5be196e5 CH |
139 | out: |
140 | mutex_unlock(&inode->i_mutex); | |
141 | return error; | |
142 | } | |
143 | EXPORT_SYMBOL_GPL(vfs_setxattr); | |
144 | ||
42492594 DQ |
145 | ssize_t |
146 | xattr_getsecurity(struct inode *inode, const char *name, void *value, | |
147 | size_t size) | |
148 | { | |
149 | void *buffer = NULL; | |
150 | ssize_t len; | |
151 | ||
152 | if (!value || !size) { | |
153 | len = security_inode_getsecurity(inode, name, &buffer, false); | |
154 | goto out_noalloc; | |
155 | } | |
156 | ||
157 | len = security_inode_getsecurity(inode, name, &buffer, true); | |
158 | if (len < 0) | |
159 | return len; | |
160 | if (size < len) { | |
161 | len = -ERANGE; | |
162 | goto out; | |
163 | } | |
164 | memcpy(value, buffer, len); | |
165 | out: | |
166 | security_release_secctx(buffer, len); | |
167 | out_noalloc: | |
168 | return len; | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(xattr_getsecurity); | |
171 | ||
1601fbad MZ |
172 | /* |
173 | * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr | |
174 | * | |
175 | * Allocate memory, if not already allocated, or re-allocate correct size, | |
176 | * before retrieving the extended attribute. | |
177 | * | |
178 | * Returns the result of alloc, if failed, or the getxattr operation. | |
179 | */ | |
180 | ssize_t | |
181 | vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, | |
182 | size_t xattr_size, gfp_t flags) | |
183 | { | |
184 | struct inode *inode = dentry->d_inode; | |
185 | char *value = *xattr_value; | |
186 | int error; | |
187 | ||
188 | error = xattr_permission(inode, name, MAY_READ); | |
189 | if (error) | |
190 | return error; | |
191 | ||
192 | if (!inode->i_op->getxattr) | |
193 | return -EOPNOTSUPP; | |
194 | ||
195 | error = inode->i_op->getxattr(dentry, name, NULL, 0); | |
196 | if (error < 0) | |
197 | return error; | |
198 | ||
199 | if (!value || (error > xattr_size)) { | |
200 | value = krealloc(*xattr_value, error + 1, flags); | |
201 | if (!value) | |
202 | return -ENOMEM; | |
203 | memset(value, 0, error + 1); | |
204 | } | |
205 | ||
206 | error = inode->i_op->getxattr(dentry, name, value, error); | |
207 | *xattr_value = value; | |
208 | return error; | |
209 | } | |
210 | ||
5be196e5 | 211 | ssize_t |
8f0cfa52 | 212 | vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) |
5be196e5 CH |
213 | { |
214 | struct inode *inode = dentry->d_inode; | |
215 | int error; | |
216 | ||
e0ad7b07 | 217 | error = xattr_permission(inode, name, MAY_READ); |
218 | if (error) | |
219 | return error; | |
220 | ||
5be196e5 CH |
221 | error = security_inode_getxattr(dentry, name); |
222 | if (error) | |
223 | return error; | |
224 | ||
5be196e5 | 225 | if (!strncmp(name, XATTR_SECURITY_PREFIX, |
e0ad7b07 | 226 | XATTR_SECURITY_PREFIX_LEN)) { |
227 | const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; | |
42492594 | 228 | int ret = xattr_getsecurity(inode, suffix, value, size); |
5be196e5 CH |
229 | /* |
230 | * Only overwrite the return value if a security module | |
231 | * is actually active. | |
232 | */ | |
4bea5805 DQ |
233 | if (ret == -EOPNOTSUPP) |
234 | goto nolsm; | |
235 | return ret; | |
5be196e5 | 236 | } |
4bea5805 DQ |
237 | nolsm: |
238 | if (inode->i_op->getxattr) | |
239 | error = inode->i_op->getxattr(dentry, name, value, size); | |
240 | else | |
241 | error = -EOPNOTSUPP; | |
5be196e5 CH |
242 | |
243 | return error; | |
244 | } | |
245 | EXPORT_SYMBOL_GPL(vfs_getxattr); | |
246 | ||
659564c8 BN |
247 | ssize_t |
248 | vfs_listxattr(struct dentry *d, char *list, size_t size) | |
249 | { | |
250 | ssize_t error; | |
251 | ||
252 | error = security_inode_listxattr(d); | |
253 | if (error) | |
254 | return error; | |
255 | error = -EOPNOTSUPP; | |
acfa4380 | 256 | if (d->d_inode->i_op->listxattr) { |
659564c8 BN |
257 | error = d->d_inode->i_op->listxattr(d, list, size); |
258 | } else { | |
259 | error = security_inode_listsecurity(d->d_inode, list, size); | |
260 | if (size && error > size) | |
261 | error = -ERANGE; | |
262 | } | |
263 | return error; | |
264 | } | |
265 | EXPORT_SYMBOL_GPL(vfs_listxattr); | |
266 | ||
5be196e5 | 267 | int |
8f0cfa52 | 268 | vfs_removexattr(struct dentry *dentry, const char *name) |
5be196e5 CH |
269 | { |
270 | struct inode *inode = dentry->d_inode; | |
271 | int error; | |
272 | ||
273 | if (!inode->i_op->removexattr) | |
274 | return -EOPNOTSUPP; | |
275 | ||
e0ad7b07 | 276 | error = xattr_permission(inode, name, MAY_WRITE); |
277 | if (error) | |
278 | return error; | |
279 | ||
2ab51f37 | 280 | mutex_lock(&inode->i_mutex); |
5be196e5 | 281 | error = security_inode_removexattr(dentry, name); |
7c51bb00 DK |
282 | if (error) |
283 | goto out; | |
5be196e5 | 284 | |
5be196e5 | 285 | error = inode->i_op->removexattr(dentry, name); |
5be196e5 | 286 | |
c7b87de2 | 287 | if (!error) { |
5be196e5 | 288 | fsnotify_xattr(dentry); |
c7b87de2 MZ |
289 | evm_inode_post_removexattr(dentry, name); |
290 | } | |
7c51bb00 DK |
291 | |
292 | out: | |
293 | mutex_unlock(&inode->i_mutex); | |
5be196e5 CH |
294 | return error; |
295 | } | |
296 | EXPORT_SYMBOL_GPL(vfs_removexattr); | |
297 | ||
298 | ||
1da177e4 LT |
299 | /* |
300 | * Extended attribute SET operations | |
301 | */ | |
302 | static long | |
8f0cfa52 | 303 | setxattr(struct dentry *d, const char __user *name, const void __user *value, |
1da177e4 LT |
304 | size_t size, int flags) |
305 | { | |
306 | int error; | |
307 | void *kvalue = NULL; | |
44c82498 | 308 | void *vvalue = NULL; /* If non-NULL, we used vmalloc() */ |
1da177e4 LT |
309 | char kname[XATTR_NAME_MAX + 1]; |
310 | ||
311 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) | |
312 | return -EINVAL; | |
313 | ||
314 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
315 | if (error == 0 || error == sizeof(kname)) | |
316 | error = -ERANGE; | |
317 | if (error < 0) | |
318 | return error; | |
319 | ||
320 | if (size) { | |
321 | if (size > XATTR_SIZE_MAX) | |
322 | return -E2BIG; | |
44c82498 AM |
323 | kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); |
324 | if (!kvalue) { | |
325 | vvalue = vmalloc(size); | |
326 | if (!vvalue) | |
327 | return -ENOMEM; | |
328 | kvalue = vvalue; | |
329 | } | |
330 | if (copy_from_user(kvalue, value, size)) { | |
331 | error = -EFAULT; | |
332 | goto out; | |
333 | } | |
2f6f0654 EB |
334 | if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || |
335 | (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) | |
336 | posix_acl_fix_xattr_from_user(kvalue, size); | |
1da177e4 LT |
337 | } |
338 | ||
5be196e5 | 339 | error = vfs_setxattr(d, kname, kvalue, size, flags); |
44c82498 AM |
340 | out: |
341 | if (vvalue) | |
342 | vfree(vvalue); | |
343 | else | |
344 | kfree(kvalue); | |
1da177e4 LT |
345 | return error; |
346 | } | |
347 | ||
8cc43116 EB |
348 | static int path_setxattr(const char __user *pathname, |
349 | const char __user *name, const void __user *value, | |
350 | size_t size, int flags, unsigned int lookup_flags) | |
1da177e4 | 351 | { |
2d8f3038 | 352 | struct path path; |
1da177e4 | 353 | int error; |
68f1bb8b JL |
354 | retry: |
355 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
1da177e4 LT |
356 | if (error) |
357 | return error; | |
2d8f3038 | 358 | error = mnt_want_write(path.mnt); |
18f335af | 359 | if (!error) { |
2d8f3038 AV |
360 | error = setxattr(path.dentry, name, value, size, flags); |
361 | mnt_drop_write(path.mnt); | |
18f335af | 362 | } |
2d8f3038 | 363 | path_put(&path); |
68f1bb8b JL |
364 | if (retry_estale(error, lookup_flags)) { |
365 | lookup_flags |= LOOKUP_REVAL; | |
366 | goto retry; | |
367 | } | |
1da177e4 LT |
368 | return error; |
369 | } | |
370 | ||
8cc43116 EB |
371 | SYSCALL_DEFINE5(setxattr, const char __user *, pathname, |
372 | const char __user *, name, const void __user *, value, | |
373 | size_t, size, int, flags) | |
374 | { | |
375 | return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW); | |
376 | } | |
377 | ||
64fd1de3 HC |
378 | SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, |
379 | const char __user *, name, const void __user *, value, | |
380 | size_t, size, int, flags) | |
1da177e4 | 381 | { |
8cc43116 | 382 | return path_setxattr(pathname, name, value, size, flags, 0); |
1da177e4 LT |
383 | } |
384 | ||
64fd1de3 HC |
385 | SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, |
386 | const void __user *,value, size_t, size, int, flags) | |
1da177e4 | 387 | { |
2903ff01 | 388 | struct fd f = fdget(fd); |
1da177e4 LT |
389 | int error = -EBADF; |
390 | ||
2903ff01 | 391 | if (!f.file) |
1da177e4 | 392 | return error; |
9f45f5bf | 393 | audit_file(f.file); |
2903ff01 | 394 | error = mnt_want_write_file(f.file); |
18f335af | 395 | if (!error) { |
9f45f5bf | 396 | error = setxattr(f.file->f_path.dentry, name, value, size, flags); |
2903ff01 | 397 | mnt_drop_write_file(f.file); |
18f335af | 398 | } |
2903ff01 | 399 | fdput(f); |
1da177e4 LT |
400 | return error; |
401 | } | |
402 | ||
403 | /* | |
404 | * Extended attribute GET operations | |
405 | */ | |
406 | static ssize_t | |
8f0cfa52 DH |
407 | getxattr(struct dentry *d, const char __user *name, void __user *value, |
408 | size_t size) | |
1da177e4 LT |
409 | { |
410 | ssize_t error; | |
411 | void *kvalue = NULL; | |
779302e6 | 412 | void *vvalue = NULL; |
1da177e4 LT |
413 | char kname[XATTR_NAME_MAX + 1]; |
414 | ||
415 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
416 | if (error == 0 || error == sizeof(kname)) | |
417 | error = -ERANGE; | |
418 | if (error < 0) | |
419 | return error; | |
420 | ||
421 | if (size) { | |
422 | if (size > XATTR_SIZE_MAX) | |
423 | size = XATTR_SIZE_MAX; | |
779302e6 SL |
424 | kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); |
425 | if (!kvalue) { | |
426 | vvalue = vmalloc(size); | |
427 | if (!vvalue) | |
428 | return -ENOMEM; | |
429 | kvalue = vvalue; | |
430 | } | |
1da177e4 LT |
431 | } |
432 | ||
5be196e5 | 433 | error = vfs_getxattr(d, kname, kvalue, size); |
f549d6c1 | 434 | if (error > 0) { |
2f6f0654 EB |
435 | if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || |
436 | (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) | |
437 | posix_acl_fix_xattr_to_user(kvalue, size); | |
f549d6c1 SS |
438 | if (size && copy_to_user(value, kvalue, error)) |
439 | error = -EFAULT; | |
440 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { | |
441 | /* The file system tried to returned a value bigger | |
442 | than XATTR_SIZE_MAX bytes. Not possible. */ | |
443 | error = -E2BIG; | |
1da177e4 | 444 | } |
779302e6 SL |
445 | if (vvalue) |
446 | vfree(vvalue); | |
447 | else | |
448 | kfree(kvalue); | |
1da177e4 LT |
449 | return error; |
450 | } | |
451 | ||
8cc43116 EB |
452 | static ssize_t path_getxattr(const char __user *pathname, |
453 | const char __user *name, void __user *value, | |
454 | size_t size, unsigned int lookup_flags) | |
1da177e4 | 455 | { |
2d8f3038 | 456 | struct path path; |
1da177e4 | 457 | ssize_t error; |
60e66b48 JL |
458 | retry: |
459 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
1da177e4 LT |
460 | if (error) |
461 | return error; | |
2d8f3038 AV |
462 | error = getxattr(path.dentry, name, value, size); |
463 | path_put(&path); | |
60e66b48 JL |
464 | if (retry_estale(error, lookup_flags)) { |
465 | lookup_flags |= LOOKUP_REVAL; | |
466 | goto retry; | |
467 | } | |
1da177e4 LT |
468 | return error; |
469 | } | |
470 | ||
8cc43116 EB |
471 | SYSCALL_DEFINE4(getxattr, const char __user *, pathname, |
472 | const char __user *, name, void __user *, value, size_t, size) | |
473 | { | |
474 | return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW); | |
475 | } | |
476 | ||
64fd1de3 HC |
477 | SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, |
478 | const char __user *, name, void __user *, value, size_t, size) | |
1da177e4 | 479 | { |
8cc43116 | 480 | return path_getxattr(pathname, name, value, size, 0); |
1da177e4 LT |
481 | } |
482 | ||
64fd1de3 HC |
483 | SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, |
484 | void __user *, value, size_t, size) | |
1da177e4 | 485 | { |
2903ff01 | 486 | struct fd f = fdget(fd); |
1da177e4 LT |
487 | ssize_t error = -EBADF; |
488 | ||
2903ff01 | 489 | if (!f.file) |
1da177e4 | 490 | return error; |
9f45f5bf | 491 | audit_file(f.file); |
2903ff01 AV |
492 | error = getxattr(f.file->f_path.dentry, name, value, size); |
493 | fdput(f); | |
1da177e4 LT |
494 | return error; |
495 | } | |
496 | ||
497 | /* | |
498 | * Extended attribute LIST operations | |
499 | */ | |
500 | static ssize_t | |
501 | listxattr(struct dentry *d, char __user *list, size_t size) | |
502 | { | |
503 | ssize_t error; | |
504 | char *klist = NULL; | |
0d08d7b7 | 505 | char *vlist = NULL; /* If non-NULL, we used vmalloc() */ |
1da177e4 LT |
506 | |
507 | if (size) { | |
508 | if (size > XATTR_LIST_MAX) | |
509 | size = XATTR_LIST_MAX; | |
703bf2d1 | 510 | klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL); |
0d08d7b7 AM |
511 | if (!klist) { |
512 | vlist = vmalloc(size); | |
513 | if (!vlist) | |
514 | return -ENOMEM; | |
515 | klist = vlist; | |
516 | } | |
1da177e4 LT |
517 | } |
518 | ||
659564c8 | 519 | error = vfs_listxattr(d, klist, size); |
f549d6c1 SS |
520 | if (error > 0) { |
521 | if (size && copy_to_user(list, klist, error)) | |
522 | error = -EFAULT; | |
523 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { | |
524 | /* The file system tried to returned a list bigger | |
525 | than XATTR_LIST_MAX bytes. Not possible. */ | |
526 | error = -E2BIG; | |
1da177e4 | 527 | } |
0d08d7b7 AM |
528 | if (vlist) |
529 | vfree(vlist); | |
530 | else | |
531 | kfree(klist); | |
1da177e4 LT |
532 | return error; |
533 | } | |
534 | ||
8cc43116 EB |
535 | static ssize_t path_listxattr(const char __user *pathname, char __user *list, |
536 | size_t size, unsigned int lookup_flags) | |
1da177e4 | 537 | { |
2d8f3038 | 538 | struct path path; |
1da177e4 | 539 | ssize_t error; |
10a90cf3 JL |
540 | retry: |
541 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
1da177e4 LT |
542 | if (error) |
543 | return error; | |
2d8f3038 AV |
544 | error = listxattr(path.dentry, list, size); |
545 | path_put(&path); | |
10a90cf3 JL |
546 | if (retry_estale(error, lookup_flags)) { |
547 | lookup_flags |= LOOKUP_REVAL; | |
548 | goto retry; | |
549 | } | |
1da177e4 LT |
550 | return error; |
551 | } | |
552 | ||
8cc43116 EB |
553 | SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, |
554 | size_t, size) | |
555 | { | |
556 | return path_listxattr(pathname, list, size, LOOKUP_FOLLOW); | |
557 | } | |
558 | ||
64fd1de3 HC |
559 | SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, |
560 | size_t, size) | |
1da177e4 | 561 | { |
8cc43116 | 562 | return path_listxattr(pathname, list, size, 0); |
1da177e4 LT |
563 | } |
564 | ||
64fd1de3 | 565 | SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) |
1da177e4 | 566 | { |
2903ff01 | 567 | struct fd f = fdget(fd); |
1da177e4 LT |
568 | ssize_t error = -EBADF; |
569 | ||
2903ff01 | 570 | if (!f.file) |
1da177e4 | 571 | return error; |
9f45f5bf | 572 | audit_file(f.file); |
2903ff01 AV |
573 | error = listxattr(f.file->f_path.dentry, list, size); |
574 | fdput(f); | |
1da177e4 LT |
575 | return error; |
576 | } | |
577 | ||
578 | /* | |
579 | * Extended attribute REMOVE operations | |
580 | */ | |
581 | static long | |
8f0cfa52 | 582 | removexattr(struct dentry *d, const char __user *name) |
1da177e4 LT |
583 | { |
584 | int error; | |
585 | char kname[XATTR_NAME_MAX + 1]; | |
586 | ||
587 | error = strncpy_from_user(kname, name, sizeof(kname)); | |
588 | if (error == 0 || error == sizeof(kname)) | |
589 | error = -ERANGE; | |
590 | if (error < 0) | |
591 | return error; | |
592 | ||
5be196e5 | 593 | return vfs_removexattr(d, kname); |
1da177e4 LT |
594 | } |
595 | ||
8cc43116 EB |
596 | static int path_removexattr(const char __user *pathname, |
597 | const char __user *name, unsigned int lookup_flags) | |
1da177e4 | 598 | { |
2d8f3038 | 599 | struct path path; |
1da177e4 | 600 | int error; |
12f06212 JL |
601 | retry: |
602 | error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); | |
1da177e4 LT |
603 | if (error) |
604 | return error; | |
2d8f3038 | 605 | error = mnt_want_write(path.mnt); |
18f335af | 606 | if (!error) { |
2d8f3038 AV |
607 | error = removexattr(path.dentry, name); |
608 | mnt_drop_write(path.mnt); | |
18f335af | 609 | } |
2d8f3038 | 610 | path_put(&path); |
12f06212 JL |
611 | if (retry_estale(error, lookup_flags)) { |
612 | lookup_flags |= LOOKUP_REVAL; | |
613 | goto retry; | |
614 | } | |
1da177e4 LT |
615 | return error; |
616 | } | |
617 | ||
8cc43116 EB |
618 | SYSCALL_DEFINE2(removexattr, const char __user *, pathname, |
619 | const char __user *, name) | |
620 | { | |
621 | return path_removexattr(pathname, name, LOOKUP_FOLLOW); | |
622 | } | |
623 | ||
6a6160a7 HC |
624 | SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, |
625 | const char __user *, name) | |
1da177e4 | 626 | { |
8cc43116 | 627 | return path_removexattr(pathname, name, 0); |
1da177e4 LT |
628 | } |
629 | ||
6a6160a7 | 630 | SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) |
1da177e4 | 631 | { |
2903ff01 | 632 | struct fd f = fdget(fd); |
1da177e4 LT |
633 | int error = -EBADF; |
634 | ||
2903ff01 | 635 | if (!f.file) |
1da177e4 | 636 | return error; |
9f45f5bf | 637 | audit_file(f.file); |
2903ff01 | 638 | error = mnt_want_write_file(f.file); |
18f335af | 639 | if (!error) { |
9f45f5bf | 640 | error = removexattr(f.file->f_path.dentry, name); |
2903ff01 | 641 | mnt_drop_write_file(f.file); |
18f335af | 642 | } |
2903ff01 | 643 | fdput(f); |
1da177e4 LT |
644 | return error; |
645 | } | |
646 | ||
647 | ||
648 | static const char * | |
649 | strcmp_prefix(const char *a, const char *a_prefix) | |
650 | { | |
651 | while (*a_prefix && *a == *a_prefix) { | |
652 | a++; | |
653 | a_prefix++; | |
654 | } | |
655 | return *a_prefix ? NULL : a; | |
656 | } | |
657 | ||
658 | /* | |
659 | * In order to implement different sets of xattr operations for each xattr | |
660 | * prefix with the generic xattr API, a filesystem should create a | |
661 | * null-terminated array of struct xattr_handler (one for each prefix) and | |
662 | * hang a pointer to it off of the s_xattr field of the superblock. | |
663 | * | |
664 | * The generic_fooxattr() functions will use this list to dispatch xattr | |
665 | * operations to the correct xattr_handler. | |
666 | */ | |
667 | #define for_each_xattr_handler(handlers, handler) \ | |
668 | for ((handler) = *(handlers)++; \ | |
669 | (handler) != NULL; \ | |
670 | (handler) = *(handlers)++) | |
671 | ||
672 | /* | |
673 | * Find the xattr_handler with the matching prefix. | |
674 | */ | |
bb435453 SH |
675 | static const struct xattr_handler * |
676 | xattr_resolve_name(const struct xattr_handler **handlers, const char **name) | |
1da177e4 | 677 | { |
bb435453 | 678 | const struct xattr_handler *handler; |
1da177e4 LT |
679 | |
680 | if (!*name) | |
681 | return NULL; | |
682 | ||
683 | for_each_xattr_handler(handlers, handler) { | |
98e9cb57 AG |
684 | const char *n; |
685 | ||
686 | n = strcmp_prefix(*name, xattr_prefix(handler)); | |
1da177e4 | 687 | if (n) { |
98e9cb57 AG |
688 | if (!handler->prefix ^ !*n) { |
689 | if (*n) | |
690 | continue; | |
691 | return ERR_PTR(-EINVAL); | |
692 | } | |
1da177e4 | 693 | *name = n; |
98e9cb57 | 694 | return handler; |
1da177e4 LT |
695 | } |
696 | } | |
98e9cb57 | 697 | return ERR_PTR(-EOPNOTSUPP); |
1da177e4 LT |
698 | } |
699 | ||
700 | /* | |
701 | * Find the handler for the prefix and dispatch its get() operation. | |
702 | */ | |
703 | ssize_t | |
704 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) | |
705 | { | |
bb435453 | 706 | const struct xattr_handler *handler; |
1da177e4 | 707 | |
431547b3 | 708 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
98e9cb57 AG |
709 | if (IS_ERR(handler)) |
710 | return PTR_ERR(handler); | |
d9a82a04 | 711 | return handler->get(handler, dentry, name, buffer, size); |
1da177e4 LT |
712 | } |
713 | ||
714 | /* | |
715 | * Combine the results of the list() operation from every xattr_handler in the | |
716 | * list. | |
717 | */ | |
718 | ssize_t | |
719 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) | |
720 | { | |
bb435453 | 721 | const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr; |
1da177e4 LT |
722 | unsigned int size = 0; |
723 | ||
724 | if (!buffer) { | |
431547b3 | 725 | for_each_xattr_handler(handlers, handler) { |
d9a82a04 AG |
726 | size += handler->list(handler, dentry, NULL, 0, |
727 | NULL, 0); | |
431547b3 | 728 | } |
1da177e4 LT |
729 | } else { |
730 | char *buf = buffer; | |
731 | ||
732 | for_each_xattr_handler(handlers, handler) { | |
d9a82a04 AG |
733 | size = handler->list(handler, dentry, buf, buffer_size, |
734 | NULL, 0); | |
1da177e4 LT |
735 | if (size > buffer_size) |
736 | return -ERANGE; | |
737 | buf += size; | |
738 | buffer_size -= size; | |
739 | } | |
740 | size = buf - buffer; | |
741 | } | |
742 | return size; | |
743 | } | |
744 | ||
745 | /* | |
746 | * Find the handler for the prefix and dispatch its set() operation. | |
747 | */ | |
748 | int | |
749 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) | |
750 | { | |
bb435453 | 751 | const struct xattr_handler *handler; |
1da177e4 LT |
752 | |
753 | if (size == 0) | |
754 | value = ""; /* empty EA, do not remove */ | |
431547b3 | 755 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
98e9cb57 AG |
756 | if (IS_ERR(handler)) |
757 | return PTR_ERR(handler); | |
d9a82a04 | 758 | return handler->set(handler, dentry, name, value, size, flags); |
1da177e4 LT |
759 | } |
760 | ||
761 | /* | |
762 | * Find the handler for the prefix and dispatch its set() operation to remove | |
763 | * any associated extended attribute. | |
764 | */ | |
765 | int | |
766 | generic_removexattr(struct dentry *dentry, const char *name) | |
767 | { | |
bb435453 | 768 | const struct xattr_handler *handler; |
1da177e4 | 769 | |
431547b3 | 770 | handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
98e9cb57 AG |
771 | if (IS_ERR(handler)) |
772 | return PTR_ERR(handler); | |
d9a82a04 | 773 | return handler->set(handler, dentry, name, NULL, 0, XATTR_REPLACE); |
1da177e4 LT |
774 | } |
775 | ||
776 | EXPORT_SYMBOL(generic_getxattr); | |
777 | EXPORT_SYMBOL(generic_listxattr); | |
778 | EXPORT_SYMBOL(generic_setxattr); | |
779 | EXPORT_SYMBOL(generic_removexattr); | |
38f38657 | 780 | |
e409de99 AG |
781 | /** |
782 | * xattr_full_name - Compute full attribute name from suffix | |
783 | * | |
784 | * @handler: handler of the xattr_handler operation | |
785 | * @name: name passed to the xattr_handler operation | |
786 | * | |
787 | * The get and set xattr handler operations are called with the remainder of | |
788 | * the attribute name after skipping the handler's prefix: for example, "foo" | |
789 | * is passed to the get operation of a handler with prefix "user." to get | |
790 | * attribute "user.foo". The full name is still "there" in the name though. | |
791 | * | |
792 | * Note: the list xattr handler operation when called from the vfs is passed a | |
793 | * NULL name; some file systems use this operation internally, with varying | |
794 | * semantics. | |
795 | */ | |
796 | const char *xattr_full_name(const struct xattr_handler *handler, | |
797 | const char *name) | |
798 | { | |
98e9cb57 | 799 | size_t prefix_len = strlen(xattr_prefix(handler)); |
e409de99 AG |
800 | |
801 | return name - prefix_len; | |
802 | } | |
803 | EXPORT_SYMBOL(xattr_full_name); | |
804 | ||
38f38657 AR |
805 | /* |
806 | * Allocate new xattr and copy in the value; but leave the name to callers. | |
807 | */ | |
808 | struct simple_xattr *simple_xattr_alloc(const void *value, size_t size) | |
809 | { | |
810 | struct simple_xattr *new_xattr; | |
811 | size_t len; | |
812 | ||
813 | /* wrap around? */ | |
814 | len = sizeof(*new_xattr) + size; | |
4e66d445 | 815 | if (len < sizeof(*new_xattr)) |
38f38657 AR |
816 | return NULL; |
817 | ||
818 | new_xattr = kmalloc(len, GFP_KERNEL); | |
819 | if (!new_xattr) | |
820 | return NULL; | |
821 | ||
822 | new_xattr->size = size; | |
823 | memcpy(new_xattr->value, value, size); | |
824 | return new_xattr; | |
825 | } | |
826 | ||
827 | /* | |
828 | * xattr GET operation for in-memory/pseudo filesystems | |
829 | */ | |
830 | int simple_xattr_get(struct simple_xattrs *xattrs, const char *name, | |
831 | void *buffer, size_t size) | |
832 | { | |
833 | struct simple_xattr *xattr; | |
834 | int ret = -ENODATA; | |
835 | ||
836 | spin_lock(&xattrs->lock); | |
837 | list_for_each_entry(xattr, &xattrs->head, list) { | |
838 | if (strcmp(name, xattr->name)) | |
839 | continue; | |
840 | ||
841 | ret = xattr->size; | |
842 | if (buffer) { | |
843 | if (size < xattr->size) | |
844 | ret = -ERANGE; | |
845 | else | |
846 | memcpy(buffer, xattr->value, xattr->size); | |
847 | } | |
848 | break; | |
849 | } | |
850 | spin_unlock(&xattrs->lock); | |
851 | return ret; | |
852 | } | |
853 | ||
aa7c5241 AG |
854 | /** |
855 | * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems | |
856 | * @xattrs: target simple_xattr list | |
857 | * @name: name of the extended attribute | |
858 | * @value: value of the xattr. If %NULL, will remove the attribute. | |
859 | * @size: size of the new xattr | |
860 | * @flags: %XATTR_{CREATE|REPLACE} | |
861 | * | |
862 | * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails | |
863 | * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist; | |
864 | * otherwise, fails with -ENODATA. | |
865 | * | |
866 | * Returns 0 on success, -errno on failure. | |
867 | */ | |
868 | int simple_xattr_set(struct simple_xattrs *xattrs, const char *name, | |
869 | const void *value, size_t size, int flags) | |
38f38657 AR |
870 | { |
871 | struct simple_xattr *xattr; | |
43385846 | 872 | struct simple_xattr *new_xattr = NULL; |
38f38657 AR |
873 | int err = 0; |
874 | ||
875 | /* value == NULL means remove */ | |
876 | if (value) { | |
877 | new_xattr = simple_xattr_alloc(value, size); | |
878 | if (!new_xattr) | |
879 | return -ENOMEM; | |
880 | ||
881 | new_xattr->name = kstrdup(name, GFP_KERNEL); | |
882 | if (!new_xattr->name) { | |
883 | kfree(new_xattr); | |
884 | return -ENOMEM; | |
885 | } | |
886 | } | |
887 | ||
888 | spin_lock(&xattrs->lock); | |
889 | list_for_each_entry(xattr, &xattrs->head, list) { | |
890 | if (!strcmp(name, xattr->name)) { | |
891 | if (flags & XATTR_CREATE) { | |
892 | xattr = new_xattr; | |
893 | err = -EEXIST; | |
894 | } else if (new_xattr) { | |
895 | list_replace(&xattr->list, &new_xattr->list); | |
896 | } else { | |
897 | list_del(&xattr->list); | |
898 | } | |
899 | goto out; | |
900 | } | |
901 | } | |
902 | if (flags & XATTR_REPLACE) { | |
903 | xattr = new_xattr; | |
904 | err = -ENODATA; | |
905 | } else { | |
906 | list_add(&new_xattr->list, &xattrs->head); | |
907 | xattr = NULL; | |
908 | } | |
909 | out: | |
910 | spin_unlock(&xattrs->lock); | |
911 | if (xattr) { | |
912 | kfree(xattr->name); | |
913 | kfree(xattr); | |
914 | } | |
915 | return err; | |
916 | ||
917 | } | |
918 | ||
38f38657 AR |
919 | static bool xattr_is_trusted(const char *name) |
920 | { | |
921 | return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); | |
922 | } | |
923 | ||
786534b9 AG |
924 | static int xattr_list_one(char **buffer, ssize_t *remaining_size, |
925 | const char *name) | |
926 | { | |
927 | size_t len = strlen(name) + 1; | |
928 | if (*buffer) { | |
929 | if (*remaining_size < len) | |
930 | return -ERANGE; | |
931 | memcpy(*buffer, name, len); | |
932 | *buffer += len; | |
933 | } | |
934 | *remaining_size -= len; | |
935 | return 0; | |
936 | } | |
937 | ||
38f38657 AR |
938 | /* |
939 | * xattr LIST operation for in-memory/pseudo filesystems | |
940 | */ | |
786534b9 AG |
941 | ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, |
942 | char *buffer, size_t size) | |
38f38657 AR |
943 | { |
944 | bool trusted = capable(CAP_SYS_ADMIN); | |
945 | struct simple_xattr *xattr; | |
786534b9 AG |
946 | ssize_t remaining_size = size; |
947 | int err; | |
948 | ||
949 | #ifdef CONFIG_FS_POSIX_ACL | |
950 | if (inode->i_acl) { | |
951 | err = xattr_list_one(&buffer, &remaining_size, | |
952 | XATTR_NAME_POSIX_ACL_ACCESS); | |
953 | if (err) | |
954 | return err; | |
955 | } | |
956 | if (inode->i_default_acl) { | |
957 | err = xattr_list_one(&buffer, &remaining_size, | |
958 | XATTR_NAME_POSIX_ACL_DEFAULT); | |
959 | if (err) | |
960 | return err; | |
961 | } | |
962 | #endif | |
38f38657 AR |
963 | |
964 | spin_lock(&xattrs->lock); | |
965 | list_for_each_entry(xattr, &xattrs->head, list) { | |
38f38657 AR |
966 | /* skip "trusted." attributes for unprivileged callers */ |
967 | if (!trusted && xattr_is_trusted(xattr->name)) | |
968 | continue; | |
969 | ||
786534b9 AG |
970 | err = xattr_list_one(&buffer, &remaining_size, xattr->name); |
971 | if (err) | |
972 | return err; | |
38f38657 AR |
973 | } |
974 | spin_unlock(&xattrs->lock); | |
975 | ||
786534b9 | 976 | return size - remaining_size; |
38f38657 AR |
977 | } |
978 | ||
4895768b AR |
979 | /* |
980 | * Adds an extended attribute to the list | |
981 | */ | |
38f38657 AR |
982 | void simple_xattr_list_add(struct simple_xattrs *xattrs, |
983 | struct simple_xattr *new_xattr) | |
984 | { | |
985 | spin_lock(&xattrs->lock); | |
986 | list_add(&new_xattr->list, &xattrs->head); | |
987 | spin_unlock(&xattrs->lock); | |
988 | } |