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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/attr.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 * changes by Thomas Schoebel-Theuer
7 */
8
9#include <linux/export.h>
10#include <linux/time.h>
11#include <linux/mm.h>
12#include <linux/string.h>
13#include <linux/sched/signal.h>
14#include <linux/capability.h>
15#include <linux/fsnotify.h>
16#include <linux/fcntl.h>
17#include <linux/security.h>
18#include <linux/evm.h>
19#include <linux/ima.h>
20
21#include "internal.h"
22
23/**
24 * setattr_should_drop_sgid - determine whether the setgid bit needs to be
25 * removed
26 * @mnt_userns: user namespace of the mount @inode was found from
27 * @inode: inode to check
28 *
29 * This function determines whether the setgid bit needs to be removed.
30 * We retain backwards compatibility and require setgid bit to be removed
31 * unconditionally if S_IXGRP is set. Otherwise we have the exact same
32 * requirements as setattr_prepare() and setattr_copy().
33 *
34 * Return: ATTR_KILL_SGID if setgid bit needs to be removed, 0 otherwise.
35 */
36int setattr_should_drop_sgid(struct user_namespace *mnt_userns,
37 const struct inode *inode)
38{
39 umode_t mode = inode->i_mode;
40
41 if (!(mode & S_ISGID))
42 return 0;
43 if (mode & S_IXGRP)
44 return ATTR_KILL_SGID;
45 if (!in_group_or_capable(mnt_userns, inode,
46 i_gid_into_vfsgid(mnt_userns, inode)))
47 return ATTR_KILL_SGID;
48 return 0;
49}
50
51/**
52 * setattr_should_drop_suidgid - determine whether the set{g,u}id bit needs to
53 * be dropped
54 * @mnt_userns: user namespace of the mount @inode was found from
55 * @inode: inode to check
56 *
57 * This function determines whether the set{g,u}id bits need to be removed.
58 * If the setuid bit needs to be removed ATTR_KILL_SUID is returned. If the
59 * setgid bit needs to be removed ATTR_KILL_SGID is returned. If both
60 * set{g,u}id bits need to be removed the corresponding mask of both flags is
61 * returned.
62 *
63 * Return: A mask of ATTR_KILL_S{G,U}ID indicating which - if any - setid bits
64 * to remove, 0 otherwise.
65 */
66int setattr_should_drop_suidgid(struct user_namespace *mnt_userns,
67 struct inode *inode)
68{
69 umode_t mode = inode->i_mode;
70 int kill = 0;
71
72 /* suid always must be killed */
73 if (unlikely(mode & S_ISUID))
74 kill = ATTR_KILL_SUID;
75
76 kill |= setattr_should_drop_sgid(mnt_userns, inode);
77
78 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
79 return kill;
80
81 return 0;
82}
83EXPORT_SYMBOL(setattr_should_drop_suidgid);
84
85/**
86 * chown_ok - verify permissions to chown inode
87 * @mnt_userns: user namespace of the mount @inode was found from
88 * @inode: inode to check permissions on
89 * @ia_vfsuid: uid to chown @inode to
90 *
91 * If the inode has been found through an idmapped mount the user namespace of
92 * the vfsmount must be passed through @mnt_userns. This function will then
93 * take care to map the inode according to @mnt_userns before checking
94 * permissions. On non-idmapped mounts or if permission checking is to be
95 * performed on the raw inode simply passs init_user_ns.
96 */
97static bool chown_ok(struct user_namespace *mnt_userns,
98 const struct inode *inode, vfsuid_t ia_vfsuid)
99{
100 vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
101 if (vfsuid_eq_kuid(vfsuid, current_fsuid()) &&
102 vfsuid_eq(ia_vfsuid, vfsuid))
103 return true;
104 if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
105 return true;
106 if (!vfsuid_valid(vfsuid) &&
107 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
108 return true;
109 return false;
110}
111
112/**
113 * chgrp_ok - verify permissions to chgrp inode
114 * @mnt_userns: user namespace of the mount @inode was found from
115 * @inode: inode to check permissions on
116 * @ia_vfsgid: gid to chown @inode to
117 *
118 * If the inode has been found through an idmapped mount the user namespace of
119 * the vfsmount must be passed through @mnt_userns. This function will then
120 * take care to map the inode according to @mnt_userns before checking
121 * permissions. On non-idmapped mounts or if permission checking is to be
122 * performed on the raw inode simply passs init_user_ns.
123 */
124static bool chgrp_ok(struct user_namespace *mnt_userns,
125 const struct inode *inode, vfsgid_t ia_vfsgid)
126{
127 vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
128 vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
129 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) {
130 if (vfsgid_eq(ia_vfsgid, vfsgid))
131 return true;
132 if (vfsgid_in_group_p(ia_vfsgid))
133 return true;
134 }
135 if (capable_wrt_inode_uidgid(mnt_userns, inode, CAP_CHOWN))
136 return true;
137 if (!vfsgid_valid(vfsgid) &&
138 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
139 return true;
140 return false;
141}
142
143/**
144 * setattr_prepare - check if attribute changes to a dentry are allowed
145 * @mnt_userns: user namespace of the mount the inode was found from
146 * @dentry: dentry to check
147 * @attr: attributes to change
148 *
149 * Check if we are allowed to change the attributes contained in @attr
150 * in the given dentry. This includes the normal unix access permission
151 * checks, as well as checks for rlimits and others. The function also clears
152 * SGID bit from mode if user is not allowed to set it. Also file capabilities
153 * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
154 *
155 * If the inode has been found through an idmapped mount the user namespace of
156 * the vfsmount must be passed through @mnt_userns. This function will then
157 * take care to map the inode according to @mnt_userns before checking
158 * permissions. On non-idmapped mounts or if permission checking is to be
159 * performed on the raw inode simply passs init_user_ns.
160 *
161 * Should be called as the first thing in ->setattr implementations,
162 * possibly after taking additional locks.
163 */
164int setattr_prepare(struct user_namespace *mnt_userns, struct dentry *dentry,
165 struct iattr *attr)
166{
167 struct inode *inode = d_inode(dentry);
168 unsigned int ia_valid = attr->ia_valid;
169
170 /*
171 * First check size constraints. These can't be overriden using
172 * ATTR_FORCE.
173 */
174 if (ia_valid & ATTR_SIZE) {
175 int error = inode_newsize_ok(inode, attr->ia_size);
176 if (error)
177 return error;
178 }
179
180 /* If force is set do it anyway. */
181 if (ia_valid & ATTR_FORCE)
182 goto kill_priv;
183
184 /* Make sure a caller can chown. */
185 if ((ia_valid & ATTR_UID) &&
186 !chown_ok(mnt_userns, inode, attr->ia_vfsuid))
187 return -EPERM;
188
189 /* Make sure caller can chgrp. */
190 if ((ia_valid & ATTR_GID) &&
191 !chgrp_ok(mnt_userns, inode, attr->ia_vfsgid))
192 return -EPERM;
193
194 /* Make sure a caller can chmod. */
195 if (ia_valid & ATTR_MODE) {
196 vfsgid_t vfsgid;
197
198 if (!inode_owner_or_capable(mnt_userns, inode))
199 return -EPERM;
200
201 if (ia_valid & ATTR_GID)
202 vfsgid = attr->ia_vfsgid;
203 else
204 vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
205
206 /* Also check the setgid bit! */
207 if (!in_group_or_capable(mnt_userns, inode, vfsgid))
208 attr->ia_mode &= ~S_ISGID;
209 }
210
211 /* Check for setting the inode time. */
212 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
213 if (!inode_owner_or_capable(mnt_userns, inode))
214 return -EPERM;
215 }
216
217kill_priv:
218 /* User has permission for the change */
219 if (ia_valid & ATTR_KILL_PRIV) {
220 int error;
221
222 error = security_inode_killpriv(mnt_userns, dentry);
223 if (error)
224 return error;
225 }
226
227 return 0;
228}
229EXPORT_SYMBOL(setattr_prepare);
230
231/**
232 * inode_newsize_ok - may this inode be truncated to a given size
233 * @inode: the inode to be truncated
234 * @offset: the new size to assign to the inode
235 *
236 * inode_newsize_ok must be called with i_mutex held.
237 *
238 * inode_newsize_ok will check filesystem limits and ulimits to check that the
239 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
240 * when necessary. Caller must not proceed with inode size change if failure is
241 * returned. @inode must be a file (not directory), with appropriate
242 * permissions to allow truncate (inode_newsize_ok does NOT check these
243 * conditions).
244 *
245 * Return: 0 on success, -ve errno on failure
246 */
247int inode_newsize_ok(const struct inode *inode, loff_t offset)
248{
249 if (offset < 0)
250 return -EINVAL;
251 if (inode->i_size < offset) {
252 unsigned long limit;
253
254 limit = rlimit(RLIMIT_FSIZE);
255 if (limit != RLIM_INFINITY && offset > limit)
256 goto out_sig;
257 if (offset > inode->i_sb->s_maxbytes)
258 goto out_big;
259 } else {
260 /*
261 * truncation of in-use swapfiles is disallowed - it would
262 * cause subsequent swapout to scribble on the now-freed
263 * blocks.
264 */
265 if (IS_SWAPFILE(inode))
266 return -ETXTBSY;
267 }
268
269 return 0;
270out_sig:
271 send_sig(SIGXFSZ, current, 0);
272out_big:
273 return -EFBIG;
274}
275EXPORT_SYMBOL(inode_newsize_ok);
276
277/**
278 * setattr_copy - copy simple metadata updates into the generic inode
279 * @mnt_userns: user namespace of the mount the inode was found from
280 * @inode: the inode to be updated
281 * @attr: the new attributes
282 *
283 * setattr_copy must be called with i_mutex held.
284 *
285 * setattr_copy updates the inode's metadata with that specified
286 * in attr on idmapped mounts. Necessary permission checks to determine
287 * whether or not the S_ISGID property needs to be removed are performed with
288 * the correct idmapped mount permission helpers.
289 * Noticeably missing is inode size update, which is more complex
290 * as it requires pagecache updates.
291 *
292 * If the inode has been found through an idmapped mount the user namespace of
293 * the vfsmount must be passed through @mnt_userns. This function will then
294 * take care to map the inode according to @mnt_userns before checking
295 * permissions. On non-idmapped mounts or if permission checking is to be
296 * performed on the raw inode simply passs init_user_ns.
297 *
298 * The inode is not marked as dirty after this operation. The rationale is
299 * that for "simple" filesystems, the struct inode is the inode storage.
300 * The caller is free to mark the inode dirty afterwards if needed.
301 */
302void setattr_copy(struct user_namespace *mnt_userns, struct inode *inode,
303 const struct iattr *attr)
304{
305 unsigned int ia_valid = attr->ia_valid;
306
307 i_uid_update(mnt_userns, attr, inode);
308 i_gid_update(mnt_userns, attr, inode);
309 if (ia_valid & ATTR_ATIME)
310 inode->i_atime = attr->ia_atime;
311 if (ia_valid & ATTR_MTIME)
312 inode->i_mtime = attr->ia_mtime;
313 if (ia_valid & ATTR_CTIME)
314 inode->i_ctime = attr->ia_ctime;
315 if (ia_valid & ATTR_MODE) {
316 umode_t mode = attr->ia_mode;
317 if (!in_group_or_capable(mnt_userns, inode,
318 i_gid_into_vfsgid(mnt_userns, inode)))
319 mode &= ~S_ISGID;
320 inode->i_mode = mode;
321 }
322}
323EXPORT_SYMBOL(setattr_copy);
324
325int may_setattr(struct user_namespace *mnt_userns, struct inode *inode,
326 unsigned int ia_valid)
327{
328 int error;
329
330 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
331 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
332 return -EPERM;
333 }
334
335 /*
336 * If utimes(2) and friends are called with times == NULL (or both
337 * times are UTIME_NOW), then we need to check for write permission
338 */
339 if (ia_valid & ATTR_TOUCH) {
340 if (IS_IMMUTABLE(inode))
341 return -EPERM;
342
343 if (!inode_owner_or_capable(mnt_userns, inode)) {
344 error = inode_permission(mnt_userns, inode, MAY_WRITE);
345 if (error)
346 return error;
347 }
348 }
349 return 0;
350}
351EXPORT_SYMBOL(may_setattr);
352
353/**
354 * notify_change - modify attributes of a filesytem object
355 * @mnt_userns: user namespace of the mount the inode was found from
356 * @dentry: object affected
357 * @attr: new attributes
358 * @delegated_inode: returns inode, if the inode is delegated
359 *
360 * The caller must hold the i_mutex on the affected object.
361 *
362 * If notify_change discovers a delegation in need of breaking,
363 * it will return -EWOULDBLOCK and return a reference to the inode in
364 * delegated_inode. The caller should then break the delegation and
365 * retry. Because breaking a delegation may take a long time, the
366 * caller should drop the i_mutex before doing so.
367 *
368 * Alternatively, a caller may pass NULL for delegated_inode. This may
369 * be appropriate for callers that expect the underlying filesystem not
370 * to be NFS exported. Also, passing NULL is fine for callers holding
371 * the file open for write, as there can be no conflicting delegation in
372 * that case.
373 *
374 * If the inode has been found through an idmapped mount the user namespace of
375 * the vfsmount must be passed through @mnt_userns. This function will then
376 * take care to map the inode according to @mnt_userns before checking
377 * permissions. On non-idmapped mounts or if permission checking is to be
378 * performed on the raw inode simply passs init_user_ns.
379 */
380int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
381 struct iattr *attr, struct inode **delegated_inode)
382{
383 struct inode *inode = dentry->d_inode;
384 umode_t mode = inode->i_mode;
385 int error;
386 struct timespec64 now;
387 unsigned int ia_valid = attr->ia_valid;
388
389 WARN_ON_ONCE(!inode_is_locked(inode));
390
391 error = may_setattr(mnt_userns, inode, ia_valid);
392 if (error)
393 return error;
394
395 if ((ia_valid & ATTR_MODE)) {
396 umode_t amode = attr->ia_mode;
397 /* Flag setting protected by i_mutex */
398 if (is_sxid(amode))
399 inode->i_flags &= ~S_NOSEC;
400 }
401
402 now = current_time(inode);
403
404 attr->ia_ctime = now;
405 if (!(ia_valid & ATTR_ATIME_SET))
406 attr->ia_atime = now;
407 else
408 attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
409 if (!(ia_valid & ATTR_MTIME_SET))
410 attr->ia_mtime = now;
411 else
412 attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
413
414 if (ia_valid & ATTR_KILL_PRIV) {
415 error = security_inode_need_killpriv(dentry);
416 if (error < 0)
417 return error;
418 if (error == 0)
419 ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
420 }
421
422 /*
423 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
424 * that the function has the ability to reinterpret a mode change
425 * that's due to these bits. This adds an implicit restriction that
426 * no function will ever call notify_change with both ATTR_MODE and
427 * ATTR_KILL_S*ID set.
428 */
429 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
430 (ia_valid & ATTR_MODE))
431 BUG();
432
433 if (ia_valid & ATTR_KILL_SUID) {
434 if (mode & S_ISUID) {
435 ia_valid = attr->ia_valid |= ATTR_MODE;
436 attr->ia_mode = (inode->i_mode & ~S_ISUID);
437 }
438 }
439 if (ia_valid & ATTR_KILL_SGID) {
440 if (mode & S_ISGID) {
441 if (!(ia_valid & ATTR_MODE)) {
442 ia_valid = attr->ia_valid |= ATTR_MODE;
443 attr->ia_mode = inode->i_mode;
444 }
445 attr->ia_mode &= ~S_ISGID;
446 }
447 }
448 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
449 return 0;
450
451 /*
452 * Verify that uid/gid changes are valid in the target
453 * namespace of the superblock.
454 */
455 if (ia_valid & ATTR_UID &&
456 !vfsuid_has_fsmapping(mnt_userns, inode->i_sb->s_user_ns,
457 attr->ia_vfsuid))
458 return -EOVERFLOW;
459 if (ia_valid & ATTR_GID &&
460 !vfsgid_has_fsmapping(mnt_userns, inode->i_sb->s_user_ns,
461 attr->ia_vfsgid))
462 return -EOVERFLOW;
463
464 /* Don't allow modifications of files with invalid uids or
465 * gids unless those uids & gids are being made valid.
466 */
467 if (!(ia_valid & ATTR_UID) &&
468 !vfsuid_valid(i_uid_into_vfsuid(mnt_userns, inode)))
469 return -EOVERFLOW;
470 if (!(ia_valid & ATTR_GID) &&
471 !vfsgid_valid(i_gid_into_vfsgid(mnt_userns, inode)))
472 return -EOVERFLOW;
473
474 error = security_inode_setattr(mnt_userns, dentry, attr);
475 if (error)
476 return error;
477 error = try_break_deleg(inode, delegated_inode);
478 if (error)
479 return error;
480
481 if (inode->i_op->setattr)
482 error = inode->i_op->setattr(mnt_userns, dentry, attr);
483 else
484 error = simple_setattr(mnt_userns, dentry, attr);
485
486 if (!error) {
487 fsnotify_change(dentry, ia_valid);
488 ima_inode_post_setattr(mnt_userns, dentry);
489 evm_inode_post_setattr(dentry, ia_valid);
490 }
491
492 return error;
493}
494EXPORT_SYMBOL(notify_change);
1/*
2 * linux/fs/attr.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * changes by Thomas Schoebel-Theuer
6 */
7
8#include <linux/module.h>
9#include <linux/time.h>
10#include <linux/mm.h>
11#include <linux/string.h>
12#include <linux/capability.h>
13#include <linux/fsnotify.h>
14#include <linux/fcntl.h>
15#include <linux/security.h>
16
17/**
18 * inode_change_ok - check if attribute changes to an inode are allowed
19 * @inode: inode to check
20 * @attr: attributes to change
21 *
22 * Check if we are allowed to change the attributes contained in @attr
23 * in the given inode. This includes the normal unix access permission
24 * checks, as well as checks for rlimits and others.
25 *
26 * Should be called as the first thing in ->setattr implementations,
27 * possibly after taking additional locks.
28 */
29int inode_change_ok(const struct inode *inode, struct iattr *attr)
30{
31 unsigned int ia_valid = attr->ia_valid;
32
33 /*
34 * First check size constraints. These can't be overriden using
35 * ATTR_FORCE.
36 */
37 if (ia_valid & ATTR_SIZE) {
38 int error = inode_newsize_ok(inode, attr->ia_size);
39 if (error)
40 return error;
41 }
42
43 /* If force is set do it anyway. */
44 if (ia_valid & ATTR_FORCE)
45 return 0;
46
47 /* Make sure a caller can chown. */
48 if ((ia_valid & ATTR_UID) &&
49 (current_fsuid() != inode->i_uid ||
50 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
51 return -EPERM;
52
53 /* Make sure caller can chgrp. */
54 if ((ia_valid & ATTR_GID) &&
55 (current_fsuid() != inode->i_uid ||
56 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
57 !capable(CAP_CHOWN))
58 return -EPERM;
59
60 /* Make sure a caller can chmod. */
61 if (ia_valid & ATTR_MODE) {
62 if (!inode_owner_or_capable(inode))
63 return -EPERM;
64 /* Also check the setgid bit! */
65 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
66 inode->i_gid) && !capable(CAP_FSETID))
67 attr->ia_mode &= ~S_ISGID;
68 }
69
70 /* Check for setting the inode time. */
71 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
72 if (!inode_owner_or_capable(inode))
73 return -EPERM;
74 }
75
76 return 0;
77}
78EXPORT_SYMBOL(inode_change_ok);
79
80/**
81 * inode_newsize_ok - may this inode be truncated to a given size
82 * @inode: the inode to be truncated
83 * @offset: the new size to assign to the inode
84 * @Returns: 0 on success, -ve errno on failure
85 *
86 * inode_newsize_ok must be called with i_mutex held.
87 *
88 * inode_newsize_ok will check filesystem limits and ulimits to check that the
89 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
90 * when necessary. Caller must not proceed with inode size change if failure is
91 * returned. @inode must be a file (not directory), with appropriate
92 * permissions to allow truncate (inode_newsize_ok does NOT check these
93 * conditions).
94 */
95int inode_newsize_ok(const struct inode *inode, loff_t offset)
96{
97 if (inode->i_size < offset) {
98 unsigned long limit;
99
100 limit = rlimit(RLIMIT_FSIZE);
101 if (limit != RLIM_INFINITY && offset > limit)
102 goto out_sig;
103 if (offset > inode->i_sb->s_maxbytes)
104 goto out_big;
105 } else {
106 /*
107 * truncation of in-use swapfiles is disallowed - it would
108 * cause subsequent swapout to scribble on the now-freed
109 * blocks.
110 */
111 if (IS_SWAPFILE(inode))
112 return -ETXTBSY;
113 }
114
115 return 0;
116out_sig:
117 send_sig(SIGXFSZ, current, 0);
118out_big:
119 return -EFBIG;
120}
121EXPORT_SYMBOL(inode_newsize_ok);
122
123/**
124 * setattr_copy - copy simple metadata updates into the generic inode
125 * @inode: the inode to be updated
126 * @attr: the new attributes
127 *
128 * setattr_copy must be called with i_mutex held.
129 *
130 * setattr_copy updates the inode's metadata with that specified
131 * in attr. Noticeably missing is inode size update, which is more complex
132 * as it requires pagecache updates.
133 *
134 * The inode is not marked as dirty after this operation. The rationale is
135 * that for "simple" filesystems, the struct inode is the inode storage.
136 * The caller is free to mark the inode dirty afterwards if needed.
137 */
138void setattr_copy(struct inode *inode, const struct iattr *attr)
139{
140 unsigned int ia_valid = attr->ia_valid;
141
142 if (ia_valid & ATTR_UID)
143 inode->i_uid = attr->ia_uid;
144 if (ia_valid & ATTR_GID)
145 inode->i_gid = attr->ia_gid;
146 if (ia_valid & ATTR_ATIME)
147 inode->i_atime = timespec_trunc(attr->ia_atime,
148 inode->i_sb->s_time_gran);
149 if (ia_valid & ATTR_MTIME)
150 inode->i_mtime = timespec_trunc(attr->ia_mtime,
151 inode->i_sb->s_time_gran);
152 if (ia_valid & ATTR_CTIME)
153 inode->i_ctime = timespec_trunc(attr->ia_ctime,
154 inode->i_sb->s_time_gran);
155 if (ia_valid & ATTR_MODE) {
156 umode_t mode = attr->ia_mode;
157
158 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
159 mode &= ~S_ISGID;
160 inode->i_mode = mode;
161 }
162}
163EXPORT_SYMBOL(setattr_copy);
164
165int notify_change(struct dentry * dentry, struct iattr * attr)
166{
167 struct inode *inode = dentry->d_inode;
168 mode_t mode = inode->i_mode;
169 int error;
170 struct timespec now;
171 unsigned int ia_valid = attr->ia_valid;
172
173 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
174 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
175 return -EPERM;
176 }
177
178 if ((ia_valid & ATTR_MODE)) {
179 mode_t amode = attr->ia_mode;
180 /* Flag setting protected by i_mutex */
181 if (is_sxid(amode))
182 inode->i_flags &= ~S_NOSEC;
183 }
184
185 now = current_fs_time(inode->i_sb);
186
187 attr->ia_ctime = now;
188 if (!(ia_valid & ATTR_ATIME_SET))
189 attr->ia_atime = now;
190 if (!(ia_valid & ATTR_MTIME_SET))
191 attr->ia_mtime = now;
192 if (ia_valid & ATTR_KILL_PRIV) {
193 attr->ia_valid &= ~ATTR_KILL_PRIV;
194 ia_valid &= ~ATTR_KILL_PRIV;
195 error = security_inode_need_killpriv(dentry);
196 if (error > 0)
197 error = security_inode_killpriv(dentry);
198 if (error)
199 return error;
200 }
201
202 /*
203 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
204 * that the function has the ability to reinterpret a mode change
205 * that's due to these bits. This adds an implicit restriction that
206 * no function will ever call notify_change with both ATTR_MODE and
207 * ATTR_KILL_S*ID set.
208 */
209 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
210 (ia_valid & ATTR_MODE))
211 BUG();
212
213 if (ia_valid & ATTR_KILL_SUID) {
214 if (mode & S_ISUID) {
215 ia_valid = attr->ia_valid |= ATTR_MODE;
216 attr->ia_mode = (inode->i_mode & ~S_ISUID);
217 }
218 }
219 if (ia_valid & ATTR_KILL_SGID) {
220 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
221 if (!(ia_valid & ATTR_MODE)) {
222 ia_valid = attr->ia_valid |= ATTR_MODE;
223 attr->ia_mode = inode->i_mode;
224 }
225 attr->ia_mode &= ~S_ISGID;
226 }
227 }
228 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
229 return 0;
230
231 error = security_inode_setattr(dentry, attr);
232 if (error)
233 return error;
234
235 if (inode->i_op->setattr)
236 error = inode->i_op->setattr(dentry, attr);
237 else
238 error = simple_setattr(dentry, attr);
239
240 if (!error)
241 fsnotify_change(dentry, ia_valid);
242
243 return error;
244}
245
246EXPORT_SYMBOL(notify_change);