blob: 7444fb1b348455d1ef0e3f26805f3b6d82b21fa9 [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>
Mimi Zoharc7b87de2011-03-09 14:39:18 -050017#include <linux/evm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/syscalls.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050019#include <linux/export.h>
Robert Love0eeca282005-07-12 17:06:03 -040020#include <linux/fsnotify.h>
Amy Griffis73241cc2005-11-03 16:00:25 +000021#include <linux/audit.h>
Andrew Morton0d08d7b2012-04-05 14:25:07 -070022#include <linux/vmalloc.h>
Eric W. Biederman2f6f0652012-02-07 18:52:57 -080023#include <linux/posix_acl_xattr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Andrew Morton0d08d7b2012-04-05 14:25:07 -070025#include <asm/uaccess.h>
Christoph Hellwig5be196e2006-01-09 20:51:55 -080026
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080027/*
28 * Check permissions for extended attribute access. This is a bit complicated
29 * because different namespaces have very different rules.
30 */
31static int
32xattr_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) {
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080039 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 /*
Andreas Gruenbacher55b23bd2011-05-27 14:50:36 +020052 * The trusted.* namespace can only be accessed by privileged users.
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080053 */
Andreas Gruenbacher55b23bd2011-05-27 14:50:36 +020054 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 }
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080059
Andreas Gruenbacher55b23bd2011-05-27 14:50:36 +020060 /*
61 * In the user.* namespace, only regular files and directories can have
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080062 * extended attributes. For sticky directories, only the owner and
Andreas Gruenbacher55b23bd2011-05-27 14:50:36 +020063 * privileged users can write attributes.
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080064 */
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080065 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080066 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
Andreas Gruenbacher55b23bd2011-05-27 14:50:36 +020067 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
Andreas Gruenbacherf1f2d872006-11-02 22:07:29 -080068 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
Serge E. Hallyn2e149672011-03-23 16:43:26 -070069 (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080070 return -EPERM;
71 }
72
SamarV-121b5757112020-09-21 05:47:44 +000073 return inode_permission2(ERR_PTR(-EOPNOTSUPP), inode, mask);
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -080074}
75
David P. Quigleyb1ab7e42009-09-03 14:25:56 -040076/**
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 */
92int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
93 const void *value, size_t size, int flags)
Christoph Hellwig5be196e2006-01-09 20:51:55 -080094{
95 struct inode *inode = dentry->d_inode;
David P. Quigleyb1ab7e42009-09-03 14:25:56 -040096 int error = -EOPNOTSUPP;
Andi Kleen69b45732011-05-28 08:25:51 -070097 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
98 XATTR_SECURITY_PREFIX_LEN);
Christoph Hellwig5be196e2006-01-09 20:51:55 -080099
Andi Kleen69b45732011-05-28 08:25:51 -0700100 if (issec)
101 inode->i_flags &= ~S_NOSEC;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800102 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 }
Andi Kleen69b45732011-05-28 08:25:51 -0700109 } else if (issec) {
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800110 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800111 error = security_inode_setsecurity(inode, suffix, value,
112 size, flags);
113 if (!error)
114 fsnotify_xattr(dentry);
115 }
David P. Quigleyb1ab7e42009-09-03 14:25:56 -0400116
117 return error;
118}
119
120
121int
122vfs_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
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800139out:
140 mutex_unlock(&inode->i_mutex);
141 return error;
142}
143EXPORT_SYMBOL_GPL(vfs_setxattr);
144
145ssize_t
David P. Quigley42492592008-02-04 22:29:39 -0800146xattr_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);
165out:
Casey Schauflerdd1f96a2017-09-19 09:39:08 -0700166 kfree(buffer);
David P. Quigley42492592008-02-04 22:29:39 -0800167out_noalloc:
168 return len;
169}
170EXPORT_SYMBOL_GPL(xattr_getsecurity);
171
Mimi Zohar1601fba2011-03-09 14:23:34 -0500172/*
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 */
180ssize_t
181vfs_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
211/* Compare an extended attribute value with the given value */
212int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
213 const char *value, size_t size, gfp_t flags)
214{
215 char *xattr_value = NULL;
216 int rc;
217
218 rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
219 if (rc < 0)
220 return rc;
221
222 if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
223 rc = -EINVAL;
224 else
225 rc = 0;
226 kfree(xattr_value);
227 return rc;
228}
229
David P. Quigley42492592008-02-04 22:29:39 -0800230ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700231vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800232{
233 struct inode *inode = dentry->d_inode;
234 int error;
235
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800236 error = xattr_permission(inode, name, MAY_READ);
237 if (error)
238 return error;
239
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800240 error = security_inode_getxattr(dentry, name);
241 if (error)
242 return error;
243
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800244 if (!strncmp(name, XATTR_SECURITY_PREFIX,
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800245 XATTR_SECURITY_PREFIX_LEN)) {
246 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
David P. Quigley42492592008-02-04 22:29:39 -0800247 int ret = xattr_getsecurity(inode, suffix, value, size);
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800248 /*
249 * Only overwrite the return value if a security module
250 * is actually active.
251 */
David P. Quigley4bea5802008-02-04 22:29:40 -0800252 if (ret == -EOPNOTSUPP)
253 goto nolsm;
254 return ret;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800255 }
David P. Quigley4bea5802008-02-04 22:29:40 -0800256nolsm:
257 if (inode->i_op->getxattr)
258 error = inode->i_op->getxattr(dentry, name, value, size);
259 else
260 error = -EOPNOTSUPP;
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800261
262 return error;
263}
264EXPORT_SYMBOL_GPL(vfs_getxattr);
265
Bill Nottingham659564c2006-10-09 16:10:48 -0400266ssize_t
267vfs_listxattr(struct dentry *d, char *list, size_t size)
268{
269 ssize_t error;
270
271 error = security_inode_listxattr(d);
272 if (error)
273 return error;
274 error = -EOPNOTSUPP;
Al Viroacfa4382008-12-04 10:06:33 -0500275 if (d->d_inode->i_op->listxattr) {
Bill Nottingham659564c2006-10-09 16:10:48 -0400276 error = d->d_inode->i_op->listxattr(d, list, size);
277 } else {
278 error = security_inode_listsecurity(d->d_inode, list, size);
279 if (size && error > size)
280 error = -ERANGE;
281 }
282 return error;
283}
284EXPORT_SYMBOL_GPL(vfs_listxattr);
285
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800286int
David Howells8f0cfa52008-04-29 00:59:41 -0700287vfs_removexattr(struct dentry *dentry, const char *name)
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800288{
289 struct inode *inode = dentry->d_inode;
290 int error;
291
292 if (!inode->i_op->removexattr)
293 return -EOPNOTSUPP;
294
akpm@osdl.orge0ad7b02006-01-09 20:51:56 -0800295 error = xattr_permission(inode, name, MAY_WRITE);
296 if (error)
297 return error;
298
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800299 mutex_lock(&inode->i_mutex);
Mimi Zohar2ab51f32011-03-23 17:23:06 -0400300 error = security_inode_removexattr(dentry, name);
Dmitry Kasatkin7c51bb02014-11-20 16:31:01 +0200301 if (error)
302 goto out;
Mimi Zohar2ab51f32011-03-23 17:23:06 -0400303
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800304 error = inode->i_op->removexattr(dentry, name);
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800305
Mimi Zoharc7b87de2011-03-09 14:39:18 -0500306 if (!error) {
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800307 fsnotify_xattr(dentry);
Mimi Zoharc7b87de2011-03-09 14:39:18 -0500308 evm_inode_post_removexattr(dentry, name);
309 }
Dmitry Kasatkin7c51bb02014-11-20 16:31:01 +0200310
311out:
312 mutex_unlock(&inode->i_mutex);
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800313 return error;
314}
315EXPORT_SYMBOL_GPL(vfs_removexattr);
316
317
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318/*
319 * Extended attribute SET operations
320 */
321static long
David Howells8f0cfa52008-04-29 00:59:41 -0700322setxattr(struct dentry *d, const char __user *name, const void __user *value,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 size_t size, int flags)
324{
325 int error;
326 void *kvalue = NULL;
Andrew Morton44c82492012-04-05 14:25:07 -0700327 void *vvalue = NULL; /* If non-NULL, we used vmalloc() */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 char kname[XATTR_NAME_MAX + 1];
329
330 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
331 return -EINVAL;
332
333 error = strncpy_from_user(kname, name, sizeof(kname));
334 if (error == 0 || error == sizeof(kname))
335 error = -ERANGE;
336 if (error < 0)
337 return error;
338
339 if (size) {
340 if (size > XATTR_SIZE_MAX)
341 return -E2BIG;
Andrew Morton44c82492012-04-05 14:25:07 -0700342 kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
343 if (!kvalue) {
344 vvalue = vmalloc(size);
345 if (!vvalue)
346 return -ENOMEM;
347 kvalue = vvalue;
348 }
349 if (copy_from_user(kvalue, value, size)) {
350 error = -EFAULT;
351 goto out;
352 }
Eric W. Biederman2f6f0652012-02-07 18:52:57 -0800353 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
354 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
355 posix_acl_fix_xattr_from_user(kvalue, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 }
357
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800358 error = vfs_setxattr(d, kname, kvalue, size, flags);
Andrew Morton44c82492012-04-05 14:25:07 -0700359out:
360 if (vvalue)
361 vfree(vvalue);
362 else
363 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 return error;
365}
366
Eric Biggers8cc43112014-10-12 11:59:58 -0500367static int path_setxattr(const char __user *pathname,
368 const char __user *name, const void __user *value,
369 size_t size, int flags, unsigned int lookup_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370{
Al Viro2d8f3032008-07-22 09:59:21 -0400371 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 int error;
Jeff Layton68f1bb82012-12-11 12:10:15 -0500373retry:
374 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 if (error)
376 return error;
Al Viro2d8f3032008-07-22 09:59:21 -0400377 error = mnt_want_write(path.mnt);
Dave Hansen18f335a2008-02-15 14:37:38 -0800378 if (!error) {
Al Viro2d8f3032008-07-22 09:59:21 -0400379 error = setxattr(path.dentry, name, value, size, flags);
380 mnt_drop_write(path.mnt);
Dave Hansen18f335a2008-02-15 14:37:38 -0800381 }
Al Viro2d8f3032008-07-22 09:59:21 -0400382 path_put(&path);
Jeff Layton68f1bb82012-12-11 12:10:15 -0500383 if (retry_estale(error, lookup_flags)) {
384 lookup_flags |= LOOKUP_REVAL;
385 goto retry;
386 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 return error;
388}
389
Eric Biggers8cc43112014-10-12 11:59:58 -0500390SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
391 const char __user *, name, const void __user *, value,
392 size_t, size, int, flags)
393{
394 return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
395}
396
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100397SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
398 const char __user *, name, const void __user *, value,
399 size_t, size, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400{
Eric Biggers8cc43112014-10-12 11:59:58 -0500401 return path_setxattr(pathname, name, value, size, flags, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402}
403
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100404SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
405 const void __user *,value, size_t, size, int, flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
Al Viro2903ff02012-08-28 12:52:22 -0400407 struct fd f = fdget(fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 int error = -EBADF;
409
Al Viro2903ff02012-08-28 12:52:22 -0400410 if (!f.file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 return error;
Al Viro9f45f5b2014-10-31 17:44:57 -0400412 audit_file(f.file);
Al Viro2903ff02012-08-28 12:52:22 -0400413 error = mnt_want_write_file(f.file);
Dave Hansen18f335a2008-02-15 14:37:38 -0800414 if (!error) {
Al Viro9f45f5b2014-10-31 17:44:57 -0400415 error = setxattr(f.file->f_path.dentry, name, value, size, flags);
Al Viro2903ff02012-08-28 12:52:22 -0400416 mnt_drop_write_file(f.file);
Dave Hansen18f335a2008-02-15 14:37:38 -0800417 }
Al Viro2903ff02012-08-28 12:52:22 -0400418 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 return error;
420}
421
422/*
423 * Extended attribute GET operations
424 */
425static ssize_t
David Howells8f0cfa52008-04-29 00:59:41 -0700426getxattr(struct dentry *d, const char __user *name, void __user *value,
427 size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428{
429 ssize_t error;
430 void *kvalue = NULL;
Sasha Levin779302e2012-07-30 14:39:13 -0700431 void *vvalue = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 char kname[XATTR_NAME_MAX + 1];
433
434 error = strncpy_from_user(kname, name, sizeof(kname));
435 if (error == 0 || error == sizeof(kname))
436 error = -ERANGE;
437 if (error < 0)
438 return error;
439
440 if (size) {
441 if (size > XATTR_SIZE_MAX)
442 size = XATTR_SIZE_MAX;
Sasha Levin779302e2012-07-30 14:39:13 -0700443 kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
444 if (!kvalue) {
Michal Hockoeb04a732017-05-08 15:57:24 -0700445 vvalue = vzalloc(size);
Sasha Levin779302e2012-07-30 14:39:13 -0700446 if (!vvalue)
447 return -ENOMEM;
448 kvalue = vvalue;
449 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 }
451
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800452 error = vfs_getxattr(d, kname, kvalue, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700453 if (error > 0) {
Eric W. Biederman2f6f0652012-02-07 18:52:57 -0800454 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
455 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
Christian Braunerf7f501c2018-06-07 13:43:48 +0200456 posix_acl_fix_xattr_to_user(kvalue, error);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700457 if (size && copy_to_user(value, kvalue, error))
458 error = -EFAULT;
459 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
460 /* The file system tried to returned a value bigger
461 than XATTR_SIZE_MAX bytes. Not possible. */
462 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 }
Sasha Levin779302e2012-07-30 14:39:13 -0700464 if (vvalue)
465 vfree(vvalue);
466 else
467 kfree(kvalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 return error;
469}
470
Eric Biggers8cc43112014-10-12 11:59:58 -0500471static ssize_t path_getxattr(const char __user *pathname,
472 const char __user *name, void __user *value,
473 size_t size, unsigned int lookup_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474{
Al Viro2d8f3032008-07-22 09:59:21 -0400475 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 ssize_t error;
Jeff Layton60e66b42012-12-11 12:10:16 -0500477retry:
478 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 if (error)
480 return error;
Al Viro2d8f3032008-07-22 09:59:21 -0400481 error = getxattr(path.dentry, name, value, size);
482 path_put(&path);
Jeff Layton60e66b42012-12-11 12:10:16 -0500483 if (retry_estale(error, lookup_flags)) {
484 lookup_flags |= LOOKUP_REVAL;
485 goto retry;
486 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 return error;
488}
489
Eric Biggers8cc43112014-10-12 11:59:58 -0500490SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
491 const char __user *, name, void __user *, value, size_t, size)
492{
493 return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
494}
495
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100496SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
497 const char __user *, name, void __user *, value, size_t, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498{
Eric Biggers8cc43112014-10-12 11:59:58 -0500499 return path_getxattr(pathname, name, value, size, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500}
501
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100502SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
503 void __user *, value, size_t, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504{
Al Viro2903ff02012-08-28 12:52:22 -0400505 struct fd f = fdget(fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 ssize_t error = -EBADF;
507
Al Viro2903ff02012-08-28 12:52:22 -0400508 if (!f.file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 return error;
Al Viro9f45f5b2014-10-31 17:44:57 -0400510 audit_file(f.file);
Al Viro2903ff02012-08-28 12:52:22 -0400511 error = getxattr(f.file->f_path.dentry, name, value, size);
512 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 return error;
514}
515
516/*
517 * Extended attribute LIST operations
518 */
519static ssize_t
520listxattr(struct dentry *d, char __user *list, size_t size)
521{
522 ssize_t error;
523 char *klist = NULL;
Andrew Morton0d08d7b2012-04-05 14:25:07 -0700524 char *vlist = NULL; /* If non-NULL, we used vmalloc() */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
526 if (size) {
527 if (size > XATTR_LIST_MAX)
528 size = XATTR_LIST_MAX;
Dave Jones703bf2d2012-04-05 14:25:06 -0700529 klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL);
Andrew Morton0d08d7b2012-04-05 14:25:07 -0700530 if (!klist) {
531 vlist = vmalloc(size);
532 if (!vlist)
533 return -ENOMEM;
534 klist = vlist;
535 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 }
537
Bill Nottingham659564c2006-10-09 16:10:48 -0400538 error = vfs_listxattr(d, klist, size);
Stephen Smalleyf549d6c2005-09-03 15:55:18 -0700539 if (error > 0) {
540 if (size && copy_to_user(list, klist, error))
541 error = -EFAULT;
542 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
543 /* The file system tried to returned a list bigger
544 than XATTR_LIST_MAX bytes. Not possible. */
545 error = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 }
Andrew Morton0d08d7b2012-04-05 14:25:07 -0700547 if (vlist)
548 vfree(vlist);
549 else
550 kfree(klist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 return error;
552}
553
Eric Biggers8cc43112014-10-12 11:59:58 -0500554static ssize_t path_listxattr(const char __user *pathname, char __user *list,
555 size_t size, unsigned int lookup_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556{
Al Viro2d8f3032008-07-22 09:59:21 -0400557 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 ssize_t error;
Jeff Layton10a90cf2012-12-11 12:10:16 -0500559retry:
560 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 if (error)
562 return error;
Al Viro2d8f3032008-07-22 09:59:21 -0400563 error = listxattr(path.dentry, list, size);
564 path_put(&path);
Jeff Layton10a90cf2012-12-11 12:10:16 -0500565 if (retry_estale(error, lookup_flags)) {
566 lookup_flags |= LOOKUP_REVAL;
567 goto retry;
568 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 return error;
570}
571
Eric Biggers8cc43112014-10-12 11:59:58 -0500572SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
573 size_t, size)
574{
575 return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
576}
577
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100578SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
579 size_t, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580{
Eric Biggers8cc43112014-10-12 11:59:58 -0500581 return path_listxattr(pathname, list, size, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582}
583
Heiko Carstens64fd1de2009-01-14 14:14:14 +0100584SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585{
Al Viro2903ff02012-08-28 12:52:22 -0400586 struct fd f = fdget(fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 ssize_t error = -EBADF;
588
Al Viro2903ff02012-08-28 12:52:22 -0400589 if (!f.file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 return error;
Al Viro9f45f5b2014-10-31 17:44:57 -0400591 audit_file(f.file);
Al Viro2903ff02012-08-28 12:52:22 -0400592 error = listxattr(f.file->f_path.dentry, list, size);
593 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 return error;
595}
596
597/*
598 * Extended attribute REMOVE operations
599 */
600static long
David Howells8f0cfa52008-04-29 00:59:41 -0700601removexattr(struct dentry *d, const char __user *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602{
603 int error;
604 char kname[XATTR_NAME_MAX + 1];
605
606 error = strncpy_from_user(kname, name, sizeof(kname));
607 if (error == 0 || error == sizeof(kname))
608 error = -ERANGE;
609 if (error < 0)
610 return error;
611
Christoph Hellwig5be196e2006-01-09 20:51:55 -0800612 return vfs_removexattr(d, kname);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613}
614
Eric Biggers8cc43112014-10-12 11:59:58 -0500615static int path_removexattr(const char __user *pathname,
616 const char __user *name, unsigned int lookup_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617{
Al Viro2d8f3032008-07-22 09:59:21 -0400618 struct path path;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 int error;
Jeff Layton12f06212012-12-11 12:10:17 -0500620retry:
621 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 if (error)
623 return error;
Al Viro2d8f3032008-07-22 09:59:21 -0400624 error = mnt_want_write(path.mnt);
Dave Hansen18f335a2008-02-15 14:37:38 -0800625 if (!error) {
Al Viro2d8f3032008-07-22 09:59:21 -0400626 error = removexattr(path.dentry, name);
627 mnt_drop_write(path.mnt);
Dave Hansen18f335a2008-02-15 14:37:38 -0800628 }
Al Viro2d8f3032008-07-22 09:59:21 -0400629 path_put(&path);
Jeff Layton12f06212012-12-11 12:10:17 -0500630 if (retry_estale(error, lookup_flags)) {
631 lookup_flags |= LOOKUP_REVAL;
632 goto retry;
633 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 return error;
635}
636
Eric Biggers8cc43112014-10-12 11:59:58 -0500637SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
638 const char __user *, name)
639{
640 return path_removexattr(pathname, name, LOOKUP_FOLLOW);
641}
642
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100643SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
644 const char __user *, name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645{
Eric Biggers8cc43112014-10-12 11:59:58 -0500646 return path_removexattr(pathname, name, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647}
648
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100649SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650{
Al Viro2903ff02012-08-28 12:52:22 -0400651 struct fd f = fdget(fd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 int error = -EBADF;
653
Al Viro2903ff02012-08-28 12:52:22 -0400654 if (!f.file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 return error;
Al Viro9f45f5b2014-10-31 17:44:57 -0400656 audit_file(f.file);
Al Viro2903ff02012-08-28 12:52:22 -0400657 error = mnt_want_write_file(f.file);
Dave Hansen18f335a2008-02-15 14:37:38 -0800658 if (!error) {
Al Viro9f45f5b2014-10-31 17:44:57 -0400659 error = removexattr(f.file->f_path.dentry, name);
Al Viro2903ff02012-08-28 12:52:22 -0400660 mnt_drop_write_file(f.file);
Dave Hansen18f335a2008-02-15 14:37:38 -0800661 }
Al Viro2903ff02012-08-28 12:52:22 -0400662 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 return error;
664}
665
666
667static const char *
668strcmp_prefix(const char *a, const char *a_prefix)
669{
670 while (*a_prefix && *a == *a_prefix) {
671 a++;
672 a_prefix++;
673 }
674 return *a_prefix ? NULL : a;
675}
676
677/*
678 * In order to implement different sets of xattr operations for each xattr
679 * prefix with the generic xattr API, a filesystem should create a
680 * null-terminated array of struct xattr_handler (one for each prefix) and
681 * hang a pointer to it off of the s_xattr field of the superblock.
682 *
683 * The generic_fooxattr() functions will use this list to dispatch xattr
684 * operations to the correct xattr_handler.
685 */
686#define for_each_xattr_handler(handlers, handler) \
687 for ((handler) = *(handlers)++; \
688 (handler) != NULL; \
689 (handler) = *(handlers)++)
690
691/*
692 * Find the xattr_handler with the matching prefix.
693 */
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700694static const struct xattr_handler *
695xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696{
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700697 const struct xattr_handler *handler;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
699 if (!*name)
700 return NULL;
701
702 for_each_xattr_handler(handlers, handler) {
703 const char *n = strcmp_prefix(*name, handler->prefix);
704 if (n) {
705 *name = n;
706 break;
707 }
708 }
709 return handler;
710}
711
712/*
713 * Find the handler for the prefix and dispatch its get() operation.
714 */
715ssize_t
716generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
717{
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700718 const struct xattr_handler *handler;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719
Christoph Hellwig431547b2009-11-13 09:52:56 +0000720 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 if (!handler)
722 return -EOPNOTSUPP;
Andreas Gruenbacherd9a82a02015-10-04 19:18:51 +0200723 return handler->get(handler, dentry, name, buffer, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724}
725
726/*
727 * Combine the results of the list() operation from every xattr_handler in the
728 * list.
729 */
730ssize_t
731generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
732{
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700733 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 unsigned int size = 0;
735
736 if (!buffer) {
Christoph Hellwig431547b2009-11-13 09:52:56 +0000737 for_each_xattr_handler(handlers, handler) {
Andreas Gruenbacherd9a82a02015-10-04 19:18:51 +0200738 size += handler->list(handler, dentry, NULL, 0,
739 NULL, 0);
Christoph Hellwig431547b2009-11-13 09:52:56 +0000740 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 } else {
742 char *buf = buffer;
743
744 for_each_xattr_handler(handlers, handler) {
Andreas Gruenbacherd9a82a02015-10-04 19:18:51 +0200745 size = handler->list(handler, dentry, buf, buffer_size,
746 NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 if (size > buffer_size)
748 return -ERANGE;
749 buf += size;
750 buffer_size -= size;
751 }
752 size = buf - buffer;
753 }
754 return size;
755}
756
757/*
758 * Find the handler for the prefix and dispatch its set() operation.
759 */
760int
761generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
762{
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700763 const struct xattr_handler *handler;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765 if (size == 0)
766 value = ""; /* empty EA, do not remove */
Christoph Hellwig431547b2009-11-13 09:52:56 +0000767 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 if (!handler)
769 return -EOPNOTSUPP;
Andreas Gruenbacherd9a82a02015-10-04 19:18:51 +0200770 return handler->set(handler, dentry, name, value, size, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771}
772
773/*
774 * Find the handler for the prefix and dispatch its set() operation to remove
775 * any associated extended attribute.
776 */
777int
778generic_removexattr(struct dentry *dentry, const char *name)
779{
Stephen Hemmingerbb435452010-05-13 17:53:14 -0700780 const struct xattr_handler *handler;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
Christoph Hellwig431547b2009-11-13 09:52:56 +0000782 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 if (!handler)
784 return -EOPNOTSUPP;
Andreas Gruenbacherd9a82a02015-10-04 19:18:51 +0200785 return handler->set(handler, dentry, name, NULL, 0, XATTR_REPLACE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786}
787
788EXPORT_SYMBOL(generic_getxattr);
789EXPORT_SYMBOL(generic_listxattr);
790EXPORT_SYMBOL(generic_setxattr);
791EXPORT_SYMBOL(generic_removexattr);
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400792
Andreas Gruenbachere409de92015-10-04 19:18:52 +0200793/**
794 * xattr_full_name - Compute full attribute name from suffix
795 *
796 * @handler: handler of the xattr_handler operation
797 * @name: name passed to the xattr_handler operation
798 *
799 * The get and set xattr handler operations are called with the remainder of
800 * the attribute name after skipping the handler's prefix: for example, "foo"
801 * is passed to the get operation of a handler with prefix "user." to get
802 * attribute "user.foo". The full name is still "there" in the name though.
803 *
804 * Note: the list xattr handler operation when called from the vfs is passed a
805 * NULL name; some file systems use this operation internally, with varying
806 * semantics.
807 */
808const char *xattr_full_name(const struct xattr_handler *handler,
809 const char *name)
810{
811 size_t prefix_len = strlen(handler->prefix);
812
813 return name - prefix_len;
814}
815EXPORT_SYMBOL(xattr_full_name);
816
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400817/*
818 * Allocate new xattr and copy in the value; but leave the name to callers.
819 */
820struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
821{
822 struct simple_xattr *new_xattr;
823 size_t len;
824
825 /* wrap around? */
826 len = sizeof(*new_xattr) + size;
Hugh Dickins4e66d442014-07-23 14:00:17 -0700827 if (len < sizeof(*new_xattr))
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400828 return NULL;
829
830 new_xattr = kmalloc(len, GFP_KERNEL);
831 if (!new_xattr)
832 return NULL;
833
834 new_xattr->size = size;
835 memcpy(new_xattr->value, value, size);
836 return new_xattr;
837}
838
839/*
840 * xattr GET operation for in-memory/pseudo filesystems
841 */
842int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
843 void *buffer, size_t size)
844{
845 struct simple_xattr *xattr;
846 int ret = -ENODATA;
847
848 spin_lock(&xattrs->lock);
849 list_for_each_entry(xattr, &xattrs->head, list) {
850 if (strcmp(name, xattr->name))
851 continue;
852
853 ret = xattr->size;
854 if (buffer) {
855 if (size < xattr->size)
856 ret = -ERANGE;
857 else
858 memcpy(buffer, xattr->value, xattr->size);
859 }
860 break;
861 }
862 spin_unlock(&xattrs->lock);
863 return ret;
864}
865
866static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
867 const void *value, size_t size, int flags)
868{
869 struct simple_xattr *xattr;
David Rientjes43385842012-10-17 20:41:15 -0700870 struct simple_xattr *new_xattr = NULL;
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400871 int err = 0;
872
873 /* value == NULL means remove */
874 if (value) {
875 new_xattr = simple_xattr_alloc(value, size);
876 if (!new_xattr)
877 return -ENOMEM;
878
879 new_xattr->name = kstrdup(name, GFP_KERNEL);
880 if (!new_xattr->name) {
881 kfree(new_xattr);
882 return -ENOMEM;
883 }
884 }
885
886 spin_lock(&xattrs->lock);
887 list_for_each_entry(xattr, &xattrs->head, list) {
888 if (!strcmp(name, xattr->name)) {
889 if (flags & XATTR_CREATE) {
890 xattr = new_xattr;
891 err = -EEXIST;
892 } else if (new_xattr) {
893 list_replace(&xattr->list, &new_xattr->list);
894 } else {
895 list_del(&xattr->list);
896 }
897 goto out;
898 }
899 }
900 if (flags & XATTR_REPLACE) {
901 xattr = new_xattr;
902 err = -ENODATA;
903 } else {
904 list_add(&new_xattr->list, &xattrs->head);
905 xattr = NULL;
906 }
907out:
908 spin_unlock(&xattrs->lock);
909 if (xattr) {
910 kfree(xattr->name);
911 kfree(xattr);
912 }
913 return err;
914
915}
916
Aristeu Rozanski48957682012-09-11 16:28:11 -0400917/**
918 * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
919 * @xattrs: target simple_xattr list
920 * @name: name of the new extended attribute
921 * @value: value of the new xattr. If %NULL, will remove the attribute
922 * @size: size of the new xattr
923 * @flags: %XATTR_{CREATE|REPLACE}
924 *
925 * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
926 * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
927 * otherwise, fails with -ENODATA.
928 *
929 * Returns 0 on success, -errno on failure.
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400930 */
931int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
932 const void *value, size_t size, int flags)
933{
934 if (size == 0)
935 value = ""; /* empty EA, do not remove */
936 return __simple_xattr_set(xattrs, name, value, size, flags);
937}
938
939/*
940 * xattr REMOVE operation for in-memory/pseudo filesystems
941 */
942int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
943{
944 return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
945}
946
947static bool xattr_is_trusted(const char *name)
948{
949 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
950}
951
952/*
953 * xattr LIST operation for in-memory/pseudo filesystems
954 */
955ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
956 size_t size)
957{
958 bool trusted = capable(CAP_SYS_ADMIN);
959 struct simple_xattr *xattr;
960 size_t used = 0;
961
962 spin_lock(&xattrs->lock);
963 list_for_each_entry(xattr, &xattrs->head, list) {
964 size_t len;
965
966 /* skip "trusted." attributes for unprivileged callers */
967 if (!trusted && xattr_is_trusted(xattr->name))
968 continue;
969
970 len = strlen(xattr->name) + 1;
971 used += len;
972 if (buffer) {
973 if (size < used) {
974 used = -ERANGE;
975 break;
976 }
977 memcpy(buffer, xattr->name, len);
978 buffer += len;
979 }
980 }
981 spin_unlock(&xattrs->lock);
982
983 return used;
984}
985
Aristeu Rozanski48957682012-09-11 16:28:11 -0400986/*
987 * Adds an extended attribute to the list
988 */
Aristeu Rozanski38f38652012-08-23 16:53:28 -0400989void simple_xattr_list_add(struct simple_xattrs *xattrs,
990 struct simple_xattr *new_xattr)
991{
992 spin_lock(&xattrs->lock);
993 list_add(&new_xattr->list, &xattrs->head);
994 spin_unlock(&xattrs->lock);
995}