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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/filelock.h>
18#include <linux/security.h>
19
20/**
21 * setattr_should_drop_sgid - determine whether the setgid bit needs to be
22 * removed
23 * @idmap: idmap of the mount @inode was found from
24 * @inode: inode to check
25 *
26 * This function determines whether the setgid bit needs to be removed.
27 * We retain backwards compatibility and require setgid bit to be removed
28 * unconditionally if S_IXGRP is set. Otherwise we have the exact same
29 * requirements as setattr_prepare() and setattr_copy().
30 *
31 * Return: ATTR_KILL_SGID if setgid bit needs to be removed, 0 otherwise.
32 */
33int setattr_should_drop_sgid(struct mnt_idmap *idmap,
34 const struct inode *inode)
35{
36 umode_t mode = inode->i_mode;
37
38 if (!(mode & S_ISGID))
39 return 0;
40 if (mode & S_IXGRP)
41 return ATTR_KILL_SGID;
42 if (!in_group_or_capable(idmap, inode, i_gid_into_vfsgid(idmap, inode)))
43 return ATTR_KILL_SGID;
44 return 0;
45}
46EXPORT_SYMBOL(setattr_should_drop_sgid);
47
48/**
49 * setattr_should_drop_suidgid - determine whether the set{g,u}id bit needs to
50 * be dropped
51 * @idmap: idmap of the mount @inode was found from
52 * @inode: inode to check
53 *
54 * This function determines whether the set{g,u}id bits need to be removed.
55 * If the setuid bit needs to be removed ATTR_KILL_SUID is returned. If the
56 * setgid bit needs to be removed ATTR_KILL_SGID is returned. If both
57 * set{g,u}id bits need to be removed the corresponding mask of both flags is
58 * returned.
59 *
60 * Return: A mask of ATTR_KILL_S{G,U}ID indicating which - if any - setid bits
61 * to remove, 0 otherwise.
62 */
63int setattr_should_drop_suidgid(struct mnt_idmap *idmap,
64 struct inode *inode)
65{
66 umode_t mode = inode->i_mode;
67 int kill = 0;
68
69 /* suid always must be killed */
70 if (unlikely(mode & S_ISUID))
71 kill = ATTR_KILL_SUID;
72
73 kill |= setattr_should_drop_sgid(idmap, inode);
74
75 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
76 return kill;
77
78 return 0;
79}
80EXPORT_SYMBOL(setattr_should_drop_suidgid);
81
82/**
83 * chown_ok - verify permissions to chown inode
84 * @idmap: idmap of the mount @inode was found from
85 * @inode: inode to check permissions on
86 * @ia_vfsuid: uid to chown @inode to
87 *
88 * If the inode has been found through an idmapped mount the idmap of
89 * the vfsmount must be passed through @idmap. This function will then
90 * take care to map the inode according to @idmap before checking
91 * permissions. On non-idmapped mounts or if permission checking is to be
92 * performed on the raw inode simply pass @nop_mnt_idmap.
93 */
94static bool chown_ok(struct mnt_idmap *idmap,
95 const struct inode *inode, vfsuid_t ia_vfsuid)
96{
97 vfsuid_t vfsuid = i_uid_into_vfsuid(idmap, inode);
98 if (vfsuid_eq_kuid(vfsuid, current_fsuid()) &&
99 vfsuid_eq(ia_vfsuid, vfsuid))
100 return true;
101 if (capable_wrt_inode_uidgid(idmap, inode, CAP_CHOWN))
102 return true;
103 if (!vfsuid_valid(vfsuid) &&
104 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
105 return true;
106 return false;
107}
108
109/**
110 * chgrp_ok - verify permissions to chgrp inode
111 * @idmap: idmap of the mount @inode was found from
112 * @inode: inode to check permissions on
113 * @ia_vfsgid: gid to chown @inode to
114 *
115 * If the inode has been found through an idmapped mount the idmap of
116 * the vfsmount must be passed through @idmap. This function will then
117 * take care to map the inode according to @idmap before checking
118 * permissions. On non-idmapped mounts or if permission checking is to be
119 * performed on the raw inode simply pass @nop_mnt_idmap.
120 */
121static bool chgrp_ok(struct mnt_idmap *idmap,
122 const struct inode *inode, vfsgid_t ia_vfsgid)
123{
124 vfsgid_t vfsgid = i_gid_into_vfsgid(idmap, inode);
125 vfsuid_t vfsuid = i_uid_into_vfsuid(idmap, inode);
126 if (vfsuid_eq_kuid(vfsuid, current_fsuid())) {
127 if (vfsgid_eq(ia_vfsgid, vfsgid))
128 return true;
129 if (vfsgid_in_group_p(ia_vfsgid))
130 return true;
131 }
132 if (capable_wrt_inode_uidgid(idmap, inode, CAP_CHOWN))
133 return true;
134 if (!vfsgid_valid(vfsgid) &&
135 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
136 return true;
137 return false;
138}
139
140/**
141 * setattr_prepare - check if attribute changes to a dentry are allowed
142 * @idmap: idmap of the mount the inode was found from
143 * @dentry: dentry to check
144 * @attr: attributes to change
145 *
146 * Check if we are allowed to change the attributes contained in @attr
147 * in the given dentry. This includes the normal unix access permission
148 * checks, as well as checks for rlimits and others. The function also clears
149 * SGID bit from mode if user is not allowed to set it. Also file capabilities
150 * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
151 *
152 * If the inode has been found through an idmapped mount the idmap of
153 * the vfsmount must be passed through @idmap. This function will then
154 * take care to map the inode according to @idmap before checking
155 * permissions. On non-idmapped mounts or if permission checking is to be
156 * performed on the raw inode simply pass @nop_mnt_idmap.
157 *
158 * Should be called as the first thing in ->setattr implementations,
159 * possibly after taking additional locks.
160 */
161int setattr_prepare(struct mnt_idmap *idmap, struct dentry *dentry,
162 struct iattr *attr)
163{
164 struct inode *inode = d_inode(dentry);
165 unsigned int ia_valid = attr->ia_valid;
166
167 /*
168 * First check size constraints. These can't be overriden using
169 * ATTR_FORCE.
170 */
171 if (ia_valid & ATTR_SIZE) {
172 int error = inode_newsize_ok(inode, attr->ia_size);
173 if (error)
174 return error;
175 }
176
177 /* If force is set do it anyway. */
178 if (ia_valid & ATTR_FORCE)
179 goto kill_priv;
180
181 /* Make sure a caller can chown. */
182 if ((ia_valid & ATTR_UID) &&
183 !chown_ok(idmap, inode, attr->ia_vfsuid))
184 return -EPERM;
185
186 /* Make sure caller can chgrp. */
187 if ((ia_valid & ATTR_GID) &&
188 !chgrp_ok(idmap, inode, attr->ia_vfsgid))
189 return -EPERM;
190
191 /* Make sure a caller can chmod. */
192 if (ia_valid & ATTR_MODE) {
193 vfsgid_t vfsgid;
194
195 if (!inode_owner_or_capable(idmap, inode))
196 return -EPERM;
197
198 if (ia_valid & ATTR_GID)
199 vfsgid = attr->ia_vfsgid;
200 else
201 vfsgid = i_gid_into_vfsgid(idmap, inode);
202
203 /* Also check the setgid bit! */
204 if (!in_group_or_capable(idmap, inode, vfsgid))
205 attr->ia_mode &= ~S_ISGID;
206 }
207
208 /* Check for setting the inode time. */
209 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
210 if (!inode_owner_or_capable(idmap, inode))
211 return -EPERM;
212 }
213
214kill_priv:
215 /* User has permission for the change */
216 if (ia_valid & ATTR_KILL_PRIV) {
217 int error;
218
219 error = security_inode_killpriv(idmap, dentry);
220 if (error)
221 return error;
222 }
223
224 return 0;
225}
226EXPORT_SYMBOL(setattr_prepare);
227
228/**
229 * inode_newsize_ok - may this inode be truncated to a given size
230 * @inode: the inode to be truncated
231 * @offset: the new size to assign to the inode
232 *
233 * inode_newsize_ok must be called with i_mutex held.
234 *
235 * inode_newsize_ok will check filesystem limits and ulimits to check that the
236 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
237 * when necessary. Caller must not proceed with inode size change if failure is
238 * returned. @inode must be a file (not directory), with appropriate
239 * permissions to allow truncate (inode_newsize_ok does NOT check these
240 * conditions).
241 *
242 * Return: 0 on success, -ve errno on failure
243 */
244int inode_newsize_ok(const struct inode *inode, loff_t offset)
245{
246 if (offset < 0)
247 return -EINVAL;
248 if (inode->i_size < offset) {
249 unsigned long limit;
250
251 limit = rlimit(RLIMIT_FSIZE);
252 if (limit != RLIM_INFINITY && offset > limit)
253 goto out_sig;
254 if (offset > inode->i_sb->s_maxbytes)
255 goto out_big;
256 } else {
257 /*
258 * truncation of in-use swapfiles is disallowed - it would
259 * cause subsequent swapout to scribble on the now-freed
260 * blocks.
261 */
262 if (IS_SWAPFILE(inode))
263 return -ETXTBSY;
264 }
265
266 return 0;
267out_sig:
268 send_sig(SIGXFSZ, current, 0);
269out_big:
270 return -EFBIG;
271}
272EXPORT_SYMBOL(inode_newsize_ok);
273
274/**
275 * setattr_copy_mgtime - update timestamps for mgtime inodes
276 * @inode: inode timestamps to be updated
277 * @attr: attrs for the update
278 *
279 * With multigrain timestamps, take more care to prevent races when
280 * updating the ctime. Always update the ctime to the very latest using
281 * the standard mechanism, and use that to populate the atime and mtime
282 * appropriately (unless those are being set to specific values).
283 */
284static void setattr_copy_mgtime(struct inode *inode, const struct iattr *attr)
285{
286 unsigned int ia_valid = attr->ia_valid;
287 struct timespec64 now;
288
289 if (ia_valid & ATTR_CTIME) {
290 /*
291 * In the case of an update for a write delegation, we must respect
292 * the value in ia_ctime and not use the current time.
293 */
294 if (ia_valid & ATTR_DELEG)
295 now = inode_set_ctime_deleg(inode, attr->ia_ctime);
296 else
297 now = inode_set_ctime_current(inode);
298 } else {
299 /* If ATTR_CTIME isn't set, then ATTR_MTIME shouldn't be either. */
300 WARN_ON_ONCE(ia_valid & ATTR_MTIME);
301 now = current_time(inode);
302 }
303
304 if (ia_valid & ATTR_ATIME_SET)
305 inode_set_atime_to_ts(inode, attr->ia_atime);
306 else if (ia_valid & ATTR_ATIME)
307 inode_set_atime_to_ts(inode, now);
308
309 if (ia_valid & ATTR_MTIME_SET)
310 inode_set_mtime_to_ts(inode, attr->ia_mtime);
311 else if (ia_valid & ATTR_MTIME)
312 inode_set_mtime_to_ts(inode, now);
313}
314
315/**
316 * setattr_copy - copy simple metadata updates into the generic inode
317 * @idmap: idmap of the mount the inode was found from
318 * @inode: the inode to be updated
319 * @attr: the new attributes
320 *
321 * setattr_copy must be called with i_mutex held.
322 *
323 * setattr_copy updates the inode's metadata with that specified
324 * in attr on idmapped mounts. Necessary permission checks to determine
325 * whether or not the S_ISGID property needs to be removed are performed with
326 * the correct idmapped mount permission helpers.
327 * Noticeably missing is inode size update, which is more complex
328 * as it requires pagecache updates.
329 *
330 * If the inode has been found through an idmapped mount the idmap of
331 * the vfsmount must be passed through @idmap. This function will then
332 * take care to map the inode according to @idmap before checking
333 * permissions. On non-idmapped mounts or if permission checking is to be
334 * performed on the raw inode simply pass @nop_mnt_idmap.
335 *
336 * The inode is not marked as dirty after this operation. The rationale is
337 * that for "simple" filesystems, the struct inode is the inode storage.
338 * The caller is free to mark the inode dirty afterwards if needed.
339 */
340void setattr_copy(struct mnt_idmap *idmap, struct inode *inode,
341 const struct iattr *attr)
342{
343 unsigned int ia_valid = attr->ia_valid;
344
345 i_uid_update(idmap, attr, inode);
346 i_gid_update(idmap, attr, inode);
347 if (ia_valid & ATTR_MODE) {
348 umode_t mode = attr->ia_mode;
349 if (!in_group_or_capable(idmap, inode,
350 i_gid_into_vfsgid(idmap, inode)))
351 mode &= ~S_ISGID;
352 inode->i_mode = mode;
353 }
354
355 if (is_mgtime(inode))
356 return setattr_copy_mgtime(inode, attr);
357
358 if (ia_valid & ATTR_ATIME)
359 inode_set_atime_to_ts(inode, attr->ia_atime);
360 if (ia_valid & ATTR_MTIME)
361 inode_set_mtime_to_ts(inode, attr->ia_mtime);
362 if (ia_valid & ATTR_CTIME) {
363 if (ia_valid & ATTR_DELEG)
364 inode_set_ctime_deleg(inode, attr->ia_ctime);
365 else
366 inode_set_ctime_to_ts(inode, attr->ia_ctime);
367 }
368}
369EXPORT_SYMBOL(setattr_copy);
370
371int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
372 unsigned int ia_valid)
373{
374 int error;
375
376 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
377 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
378 return -EPERM;
379 }
380
381 /*
382 * If utimes(2) and friends are called with times == NULL (or both
383 * times are UTIME_NOW), then we need to check for write permission
384 */
385 if (ia_valid & ATTR_TOUCH) {
386 if (IS_IMMUTABLE(inode))
387 return -EPERM;
388
389 if (!inode_owner_or_capable(idmap, inode)) {
390 error = inode_permission(idmap, inode, MAY_WRITE);
391 if (error)
392 return error;
393 }
394 }
395 return 0;
396}
397EXPORT_SYMBOL(may_setattr);
398
399/**
400 * notify_change - modify attributes of a filesystem object
401 * @idmap: idmap of the mount the inode was found from
402 * @dentry: object affected
403 * @attr: new attributes
404 * @delegated_inode: returns inode, if the inode is delegated
405 *
406 * The caller must hold the i_mutex on the affected object.
407 *
408 * If notify_change discovers a delegation in need of breaking,
409 * it will return -EWOULDBLOCK and return a reference to the inode in
410 * delegated_inode. The caller should then break the delegation and
411 * retry. Because breaking a delegation may take a long time, the
412 * caller should drop the i_mutex before doing so.
413 *
414 * Alternatively, a caller may pass NULL for delegated_inode. This may
415 * be appropriate for callers that expect the underlying filesystem not
416 * to be NFS exported. Also, passing NULL is fine for callers holding
417 * the file open for write, as there can be no conflicting delegation in
418 * that case.
419 *
420 * If the inode has been found through an idmapped mount the idmap of
421 * the vfsmount must be passed through @idmap. This function will then
422 * take care to map the inode according to @idmap before checking
423 * permissions. On non-idmapped mounts or if permission checking is to be
424 * performed on the raw inode simply pass @nop_mnt_idmap.
425 */
426int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
427 struct iattr *attr, struct inode **delegated_inode)
428{
429 struct inode *inode = dentry->d_inode;
430 umode_t mode = inode->i_mode;
431 int error;
432 struct timespec64 now;
433 unsigned int ia_valid = attr->ia_valid;
434
435 WARN_ON_ONCE(!inode_is_locked(inode));
436
437 error = may_setattr(idmap, inode, ia_valid);
438 if (error)
439 return error;
440
441 if ((ia_valid & ATTR_MODE)) {
442 /*
443 * Don't allow changing the mode of symlinks:
444 *
445 * (1) The vfs doesn't take the mode of symlinks into account
446 * during permission checking.
447 * (2) This has never worked correctly. Most major filesystems
448 * did return EOPNOTSUPP due to interactions with POSIX ACLs
449 * but did still updated the mode of the symlink.
450 * This inconsistency led system call wrapper providers such
451 * as libc to block changing the mode of symlinks with
452 * EOPNOTSUPP already.
453 * (3) To even do this in the first place one would have to use
454 * specific file descriptors and quite some effort.
455 */
456 if (S_ISLNK(inode->i_mode))
457 return -EOPNOTSUPP;
458
459 /* Flag setting protected by i_mutex */
460 if (is_sxid(attr->ia_mode))
461 inode->i_flags &= ~S_NOSEC;
462 }
463
464 now = current_time(inode);
465
466 attr->ia_ctime = now;
467 if (!(ia_valid & ATTR_ATIME_SET))
468 attr->ia_atime = now;
469 else
470 attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
471 if (!(ia_valid & ATTR_MTIME_SET))
472 attr->ia_mtime = now;
473 else
474 attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
475
476 if (ia_valid & ATTR_KILL_PRIV) {
477 error = security_inode_need_killpriv(dentry);
478 if (error < 0)
479 return error;
480 if (error == 0)
481 ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
482 }
483
484 /*
485 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
486 * that the function has the ability to reinterpret a mode change
487 * that's due to these bits. This adds an implicit restriction that
488 * no function will ever call notify_change with both ATTR_MODE and
489 * ATTR_KILL_S*ID set.
490 */
491 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
492 (ia_valid & ATTR_MODE))
493 BUG();
494
495 if (ia_valid & ATTR_KILL_SUID) {
496 if (mode & S_ISUID) {
497 ia_valid = attr->ia_valid |= ATTR_MODE;
498 attr->ia_mode = (inode->i_mode & ~S_ISUID);
499 }
500 }
501 if (ia_valid & ATTR_KILL_SGID) {
502 if (mode & S_ISGID) {
503 if (!(ia_valid & ATTR_MODE)) {
504 ia_valid = attr->ia_valid |= ATTR_MODE;
505 attr->ia_mode = inode->i_mode;
506 }
507 attr->ia_mode &= ~S_ISGID;
508 }
509 }
510 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
511 return 0;
512
513 /*
514 * Verify that uid/gid changes are valid in the target
515 * namespace of the superblock.
516 */
517 if (ia_valid & ATTR_UID &&
518 !vfsuid_has_fsmapping(idmap, inode->i_sb->s_user_ns,
519 attr->ia_vfsuid))
520 return -EOVERFLOW;
521 if (ia_valid & ATTR_GID &&
522 !vfsgid_has_fsmapping(idmap, inode->i_sb->s_user_ns,
523 attr->ia_vfsgid))
524 return -EOVERFLOW;
525
526 /* Don't allow modifications of files with invalid uids or
527 * gids unless those uids & gids are being made valid.
528 */
529 if (!(ia_valid & ATTR_UID) &&
530 !vfsuid_valid(i_uid_into_vfsuid(idmap, inode)))
531 return -EOVERFLOW;
532 if (!(ia_valid & ATTR_GID) &&
533 !vfsgid_valid(i_gid_into_vfsgid(idmap, inode)))
534 return -EOVERFLOW;
535
536 error = security_inode_setattr(idmap, dentry, attr);
537 if (error)
538 return error;
539
540 /*
541 * If ATTR_DELEG is set, then these attributes are being set on
542 * behalf of the holder of a write delegation. We want to avoid
543 * breaking the delegation in this case.
544 */
545 if (!(ia_valid & ATTR_DELEG)) {
546 error = try_break_deleg(inode, delegated_inode);
547 if (error)
548 return error;
549 }
550
551 if (inode->i_op->setattr)
552 error = inode->i_op->setattr(idmap, dentry, attr);
553 else
554 error = simple_setattr(idmap, dentry, attr);
555
556 if (!error) {
557 fsnotify_change(dentry, ia_valid);
558 security_inode_post_setattr(idmap, dentry, ia_valid);
559 }
560
561 return error;
562}
563EXPORT_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);