blob: d22e8187477fa77350c003d73a446284c02383bb [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
3 * linux/fs/attr.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 * changes by Thomas Schoebel-Theuer
7 */
8
Paul Gortmaker630d9c42011-11-16 23:57:37 -05009#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/time.h>
11#include <linux/mm.h>
12#include <linux/string.h>
Ingo Molnar3f07c012017-02-08 18:51:30 +010013#include <linux/sched/signal.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080014#include <linux/capability.h>
Robert Love0eeca282005-07-12 17:06:03 -040015#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/fcntl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/security.h>
Mimi Zohar975d2942011-03-09 14:39:57 -050018#include <linux/evm.h>
Mimi Zohar9957a502011-03-09 22:57:53 -050019#include <linux/ima.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
Eric W. Biederman00311812016-10-15 18:36:59 -050021static bool chown_ok(const struct inode *inode, kuid_t uid)
22{
23 if (uid_eq(current_fsuid(), inode->i_uid) &&
24 uid_eq(uid, inode->i_uid))
25 return true;
26 if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
27 return true;
28 if (uid_eq(inode->i_uid, INVALID_UID) &&
29 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
30 return true;
31 return false;
32}
33
34static bool chgrp_ok(const struct inode *inode, kgid_t gid)
35{
36 if (uid_eq(current_fsuid(), inode->i_uid) &&
37 (in_group_p(gid) || gid_eq(gid, inode->i_gid)))
38 return true;
39 if (capable_wrt_inode_uidgid(inode, CAP_CHOWN))
40 return true;
41 if (gid_eq(inode->i_gid, INVALID_GID) &&
42 ns_capable(inode->i_sb->s_user_ns, CAP_CHOWN))
43 return true;
44 return false;
45}
46
Christoph Hellwig2c27c652010-06-04 11:30:04 +020047/**
Jan Kara31051c82016-05-26 16:55:18 +020048 * setattr_prepare - check if attribute changes to a dentry are allowed
49 * @dentry: dentry to check
Christoph Hellwig2c27c652010-06-04 11:30:04 +020050 * @attr: attributes to change
51 *
52 * Check if we are allowed to change the attributes contained in @attr
Jan Kara31051c82016-05-26 16:55:18 +020053 * in the given dentry. This includes the normal unix access permission
54 * checks, as well as checks for rlimits and others. The function also clears
55 * SGID bit from mode if user is not allowed to set it. Also file capabilities
56 * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set.
Christoph Hellwig2c27c652010-06-04 11:30:04 +020057 *
58 * Should be called as the first thing in ->setattr implementations,
59 * possibly after taking additional locks.
60 */
Jan Kara31051c82016-05-26 16:55:18 +020061int setattr_prepare(struct dentry *dentry, struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070062{
Jan Kara31051c82016-05-26 16:55:18 +020063 struct inode *inode = d_inode(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 unsigned int ia_valid = attr->ia_valid;
65
Christoph Hellwig2c27c652010-06-04 11:30:04 +020066 /*
67 * First check size constraints. These can't be overriden using
68 * ATTR_FORCE.
69 */
70 if (ia_valid & ATTR_SIZE) {
71 int error = inode_newsize_ok(inode, attr->ia_size);
72 if (error)
73 return error;
74 }
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 /* If force is set do it anyway. */
77 if (ia_valid & ATTR_FORCE)
Jan Kara030b5332016-05-26 17:21:32 +020078 goto kill_priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80 /* Make sure a caller can chown. */
Eric W. Biederman00311812016-10-15 18:36:59 -050081 if ((ia_valid & ATTR_UID) && !chown_ok(inode, attr->ia_uid))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020082 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
84 /* Make sure caller can chgrp. */
Eric W. Biederman00311812016-10-15 18:36:59 -050085 if ((ia_valid & ATTR_GID) && !chgrp_ok(inode, attr->ia_gid))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020086 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
88 /* Make sure a caller can chmod. */
89 if (ia_valid & ATTR_MODE) {
Serge E. Hallyn2e149672011-03-23 16:43:26 -070090 if (!inode_owner_or_capable(inode))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020091 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 /* Also check the setgid bit! */
93 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
Eric W. Biederman7fa294c2012-09-02 19:12:51 -070094 inode->i_gid) &&
Andy Lutomirski23adbe12014-06-10 12:45:42 -070095 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 attr->ia_mode &= ~S_ISGID;
97 }
98
99 /* Check for setting the inode time. */
Miklos Szeredi9767d742008-07-01 15:01:26 +0200100 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
Serge E. Hallyn2e149672011-03-23 16:43:26 -0700101 if (!inode_owner_or_capable(inode))
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200102 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 }
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200104
Jan Kara030b5332016-05-26 17:21:32 +0200105kill_priv:
106 /* User has permission for the change */
107 if (ia_valid & ATTR_KILL_PRIV) {
108 int error;
109
110 error = security_inode_killpriv(dentry);
111 if (error)
112 return error;
113 }
114
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200115 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116}
Jan Kara31051c82016-05-26 16:55:18 +0200117EXPORT_SYMBOL(setattr_prepare);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000119/**
120 * inode_newsize_ok - may this inode be truncated to a given size
121 * @inode: the inode to be truncated
122 * @offset: the new size to assign to the inode
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000123 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000124 * inode_newsize_ok must be called with i_mutex held.
125 *
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000126 * inode_newsize_ok will check filesystem limits and ulimits to check that the
127 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
128 * when necessary. Caller must not proceed with inode size change if failure is
129 * returned. @inode must be a file (not directory), with appropriate
130 * permissions to allow truncate (inode_newsize_ok does NOT check these
131 * conditions).
Matthew Wilcox3fae1742018-07-03 08:08:34 -0700132 *
133 * Return: 0 on success, -ve errno on failure
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000134 */
135int inode_newsize_ok(const struct inode *inode, loff_t offset)
136{
137 if (inode->i_size < offset) {
138 unsigned long limit;
139
Jiri Slabyd554ed892010-03-05 13:42:42 -0800140 limit = rlimit(RLIMIT_FSIZE);
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000141 if (limit != RLIM_INFINITY && offset > limit)
142 goto out_sig;
143 if (offset > inode->i_sb->s_maxbytes)
144 goto out_big;
145 } else {
146 /*
147 * truncation of in-use swapfiles is disallowed - it would
148 * cause subsequent swapout to scribble on the now-freed
149 * blocks.
150 */
151 if (IS_SWAPFILE(inode))
152 return -ETXTBSY;
153 }
154
155 return 0;
156out_sig:
157 send_sig(SIGXFSZ, current, 0);
158out_big:
159 return -EFBIG;
160}
161EXPORT_SYMBOL(inode_newsize_ok);
162
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000163/**
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200164 * setattr_copy - copy simple metadata updates into the generic inode
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000165 * @inode: the inode to be updated
166 * @attr: the new attributes
167 *
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200168 * setattr_copy must be called with i_mutex held.
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000169 *
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200170 * setattr_copy updates the inode's metadata with that specified
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300171 * in attr. Noticeably missing is inode size update, which is more complex
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200172 * as it requires pagecache updates.
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000173 *
174 * The inode is not marked as dirty after this operation. The rationale is
175 * that for "simple" filesystems, the struct inode is the inode storage.
176 * The caller is free to mark the inode dirty afterwards if needed.
177 */
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200178void setattr_copy(struct inode *inode, const struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179{
180 unsigned int ia_valid = attr->ia_valid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 if (ia_valid & ATTR_UID)
183 inode->i_uid = attr->ia_uid;
184 if (ia_valid & ATTR_GID)
185 inode->i_gid = attr->ia_gid;
186 if (ia_valid & ATTR_ATIME)
Deepa Dinamani95582b02018-05-08 19:36:02 -0700187 inode->i_atime = timespec64_trunc(attr->ia_atime,
188 inode->i_sb->s_time_gran);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 if (ia_valid & ATTR_MTIME)
Deepa Dinamani95582b02018-05-08 19:36:02 -0700190 inode->i_mtime = timespec64_trunc(attr->ia_mtime,
191 inode->i_sb->s_time_gran);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 if (ia_valid & ATTR_CTIME)
Deepa Dinamani95582b02018-05-08 19:36:02 -0700193 inode->i_ctime = timespec64_trunc(attr->ia_ctime,
194 inode->i_sb->s_time_gran);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 if (ia_valid & ATTR_MODE) {
196 umode_t mode = attr->ia_mode;
197
Eric W. Biederman7fa294c2012-09-02 19:12:51 -0700198 if (!in_group_p(inode->i_gid) &&
Andy Lutomirski23adbe12014-06-10 12:45:42 -0700199 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 mode &= ~S_ISGID;
201 inode->i_mode = mode;
202 }
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000203}
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200204EXPORT_SYMBOL(setattr_copy);
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000205
J. Bruce Fields27ac0ff2011-09-20 17:19:26 -0400206/**
207 * notify_change - modify attributes of a filesytem object
208 * @dentry: object affected
Matthew Wilcox3fae1742018-07-03 08:08:34 -0700209 * @attr: new attributes
J. Bruce Fields27ac0ff2011-09-20 17:19:26 -0400210 * @delegated_inode: returns inode, if the inode is delegated
211 *
212 * The caller must hold the i_mutex on the affected object.
213 *
214 * If notify_change discovers a delegation in need of breaking,
215 * it will return -EWOULDBLOCK and return a reference to the inode in
216 * delegated_inode. The caller should then break the delegation and
217 * retry. Because breaking a delegation may take a long time, the
218 * caller should drop the i_mutex before doing so.
219 *
220 * Alternatively, a caller may pass NULL for delegated_inode. This may
221 * be appropriate for callers that expect the underlying filesystem not
222 * to be NFS exported. Also, passing NULL is fine for callers holding
223 * the file open for write, as there can be no conflicting delegation in
224 * that case.
225 */
226int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227{
228 struct inode *inode = dentry->d_inode;
Al Viro8d334ac2011-07-24 23:21:59 -0400229 umode_t mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 int error;
Deepa Dinamani95582b02018-05-08 19:36:02 -0700231 struct timespec64 now;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 unsigned int ia_valid = attr->ia_valid;
233
Al Viro59551022016-01-22 15:40:57 -0500234 WARN_ON_ONCE(!inode_is_locked(inode));
Andrew Mortonc4107b32012-06-20 09:55:58 +1000235
Miklos Szeredibeb29e02008-07-01 15:01:29 +0200236 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
237 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
238 return -EPERM;
239 }
240
Miklos Szeredif2b20f62016-09-16 12:44:20 +0200241 /*
242 * If utimes(2) and friends are called with times == NULL (or both
243 * times are UTIME_NOW), then we need to check for write permission
244 */
245 if (ia_valid & ATTR_TOUCH) {
246 if (IS_IMMUTABLE(inode))
247 return -EPERM;
248
249 if (!inode_owner_or_capable(inode)) {
250 error = inode_permission(inode, MAY_WRITE);
251 if (error)
252 return error;
253 }
254 }
255
Andi Kleen69b45732011-05-28 08:25:51 -0700256 if ((ia_valid & ATTR_MODE)) {
Al Viro8d334ac2011-07-24 23:21:59 -0400257 umode_t amode = attr->ia_mode;
Andi Kleen69b45732011-05-28 08:25:51 -0700258 /* Flag setting protected by i_mutex */
259 if (is_sxid(amode))
260 inode->i_flags &= ~S_NOSEC;
261 }
262
Deepa Dinamanic2050a42016-09-14 07:48:06 -0700263 now = current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264
265 attr->ia_ctime = now;
266 if (!(ia_valid & ATTR_ATIME_SET))
267 attr->ia_atime = now;
268 if (!(ia_valid & ATTR_MTIME_SET))
269 attr->ia_mtime = now;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700270 if (ia_valid & ATTR_KILL_PRIV) {
Serge E. Hallynb5376772007-10-16 23:31:36 -0700271 error = security_inode_need_killpriv(dentry);
Jan Kara030b5332016-05-26 17:21:32 +0200272 if (error < 0)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700273 return error;
Jan Kara030b5332016-05-26 17:21:32 +0200274 if (error == 0)
275 ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700276 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700277
278 /*
279 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
280 * that the function has the ability to reinterpret a mode change
281 * that's due to these bits. This adds an implicit restriction that
282 * no function will ever call notify_change with both ATTR_MODE and
283 * ATTR_KILL_S*ID set.
284 */
285 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
286 (ia_valid & ATTR_MODE))
287 BUG();
288
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 if (ia_valid & ATTR_KILL_SUID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 if (mode & S_ISUID) {
Jeff Layton6de0ec02007-10-18 03:05:20 -0700291 ia_valid = attr->ia_valid |= ATTR_MODE;
292 attr->ia_mode = (inode->i_mode & ~S_ISUID);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 }
294 }
295 if (ia_valid & ATTR_KILL_SGID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
297 if (!(ia_valid & ATTR_MODE)) {
298 ia_valid = attr->ia_valid |= ATTR_MODE;
299 attr->ia_mode = inode->i_mode;
300 }
301 attr->ia_mode &= ~S_ISGID;
302 }
303 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700304 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 return 0;
306
Seth Forsheea475acf2016-04-26 14:36:25 -0500307 /*
308 * Verify that uid/gid changes are valid in the target
309 * namespace of the superblock.
310 */
311 if (ia_valid & ATTR_UID &&
312 !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid))
313 return -EOVERFLOW;
314 if (ia_valid & ATTR_GID &&
315 !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid))
316 return -EOVERFLOW;
317
Eric W. Biederman0bd23d092016-06-29 14:54:46 -0500318 /* Don't allow modifications of files with invalid uids or
319 * gids unless those uids & gids are being made valid.
320 */
321 if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid))
322 return -EOVERFLOW;
323 if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid))
324 return -EOVERFLOW;
325
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200326 error = security_inode_setattr(dentry, attr);
327 if (error)
328 return error;
J. Bruce Fields27ac0ff2011-09-20 17:19:26 -0400329 error = try_break_deleg(inode, delegated_inode);
330 if (error)
331 return error;
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200332
Christoph Hellwigeef23802010-06-04 11:30:01 +0200333 if (inode->i_op->setattr)
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200334 error = inode->i_op->setattr(dentry, attr);
Christoph Hellwigeef23802010-06-04 11:30:01 +0200335 else
336 error = simple_setattr(dentry, attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Mimi Zohar975d2942011-03-09 14:39:57 -0500338 if (!error) {
Robert Love0eeca282005-07-12 17:06:03 -0400339 fsnotify_change(dentry, ia_valid);
Mimi Zohar9957a502011-03-09 22:57:53 -0500340 ima_inode_post_setattr(dentry);
Mimi Zohar975d2942011-03-09 14:39:57 -0500341 evm_inode_post_setattr(dentry, ia_valid);
342 }
Robert Love0eeca282005-07-12 17:06:03 -0400343
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 return error;
345}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346EXPORT_SYMBOL(notify_change);