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Merge tag 'gvt-fixes-2018-09-10' of https://github.com/intel/gvt-linux into drm-intel...
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b2441318 1// SPDX-License-Identifier: GPL-2.0
1da177e4
LT
2/*
3 * linux/fs/attr.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 * changes by Thomas Schoebel-Theuer
7 */
8
630d9c47 9#include <linux/export.h>
1da177e4
LT
10#include <linux/time.h>
11#include <linux/mm.h>
12#include <linux/string.h>
3f07c014 13#include <linux/sched/signal.h>
16f7e0fe 14#include <linux/capability.h>
0eeca283 15#include <linux/fsnotify.h>
1da177e4 16#include <linux/fcntl.h>
1da177e4 17#include <linux/security.h>
975d2943 18#include <linux/evm.h>
9957a504 19#include <linux/ima.h>
1da177e4 20
0031181c
EB
21static 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
2c27c65e 47/**
31051c85
JK
48 * setattr_prepare - check if attribute changes to a dentry are allowed
49 * @dentry: dentry to check
2c27c65e
CH
50 * @attr: attributes to change
51 *
52 * Check if we are allowed to change the attributes contained in @attr
31051c85
JK
53 * 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.
2c27c65e
CH
57 *
58 * Should be called as the first thing in ->setattr implementations,
59 * possibly after taking additional locks.
60 */
31051c85 61int setattr_prepare(struct dentry *dentry, struct iattr *attr)
1da177e4 62{
31051c85 63 struct inode *inode = d_inode(dentry);
1da177e4
LT
64 unsigned int ia_valid = attr->ia_valid;
65
2c27c65e
CH
66 /*
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
1da177e4
LT
76 /* If force is set do it anyway. */
77 if (ia_valid & ATTR_FORCE)
030b533c 78 goto kill_priv;
1da177e4
LT
79
80 /* Make sure a caller can chown. */
0031181c 81 if ((ia_valid & ATTR_UID) && !chown_ok(inode, attr->ia_uid))
2c27c65e 82 return -EPERM;
1da177e4
LT
83
84 /* Make sure caller can chgrp. */
0031181c 85 if ((ia_valid & ATTR_GID) && !chgrp_ok(inode, attr->ia_gid))
2c27c65e 86 return -EPERM;
1da177e4
LT
87
88 /* Make sure a caller can chmod. */
89 if (ia_valid & ATTR_MODE) {
2e149670 90 if (!inode_owner_or_capable(inode))
2c27c65e 91 return -EPERM;
1da177e4
LT
92 /* Also check the setgid bit! */
93 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
7fa294c8 94 inode->i_gid) &&
23adbe12 95 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
1da177e4
LT
96 attr->ia_mode &= ~S_ISGID;
97 }
98
99 /* Check for setting the inode time. */
9767d749 100 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
2e149670 101 if (!inode_owner_or_capable(inode))
2c27c65e 102 return -EPERM;
1da177e4 103 }
2c27c65e 104
030b533c
JK
105kill_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
2c27c65e 115 return 0;
1da177e4 116}
31051c85 117EXPORT_SYMBOL(setattr_prepare);
1da177e4 118
25d9e2d1 119/**
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
25d9e2d1 123 *
7bb46a67 124 * inode_newsize_ok must be called with i_mutex held.
125 *
25d9e2d1 126 * 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).
3fae1746
MW
132 *
133 * Return: 0 on success, -ve errno on failure
25d9e2d1 134 */
135int inode_newsize_ok(const struct inode *inode, loff_t offset)
136{
137 if (inode->i_size < offset) {
138 unsigned long limit;
139
d554ed89 140 limit = rlimit(RLIMIT_FSIZE);
25d9e2d1 141 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
7bb46a67 163/**
6a1a90ad 164 * setattr_copy - copy simple metadata updates into the generic inode
7bb46a67 165 * @inode: the inode to be updated
166 * @attr: the new attributes
167 *
6a1a90ad 168 * setattr_copy must be called with i_mutex held.
7bb46a67 169 *
6a1a90ad 170 * setattr_copy updates the inode's metadata with that specified
25985edc 171 * in attr. Noticeably missing is inode size update, which is more complex
2c27c65e 172 * as it requires pagecache updates.
7bb46a67 173 *
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 */
6a1a90ad 178void setattr_copy(struct inode *inode, const struct iattr *attr)
1da177e4
LT
179{
180 unsigned int ia_valid = attr->ia_valid;
4a30131e 181
1da177e4
LT
182 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)
95582b00
DD
187 inode->i_atime = timespec64_trunc(attr->ia_atime,
188 inode->i_sb->s_time_gran);
1da177e4 189 if (ia_valid & ATTR_MTIME)
95582b00
DD
190 inode->i_mtime = timespec64_trunc(attr->ia_mtime,
191 inode->i_sb->s_time_gran);
1da177e4 192 if (ia_valid & ATTR_CTIME)
95582b00
DD
193 inode->i_ctime = timespec64_trunc(attr->ia_ctime,
194 inode->i_sb->s_time_gran);
1da177e4
LT
195 if (ia_valid & ATTR_MODE) {
196 umode_t mode = attr->ia_mode;
197
7fa294c8 198 if (!in_group_p(inode->i_gid) &&
23adbe12 199 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
1da177e4
LT
200 mode &= ~S_ISGID;
201 inode->i_mode = mode;
202 }
7bb46a67 203}
6a1a90ad 204EXPORT_SYMBOL(setattr_copy);
7bb46a67 205
27ac0ffe
BF
206/**
207 * notify_change - modify attributes of a filesytem object
208 * @dentry: object affected
3fae1746 209 * @attr: new attributes
27ac0ffe
BF
210 * @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)
1da177e4
LT
227{
228 struct inode *inode = dentry->d_inode;
8d334acd 229 umode_t mode = inode->i_mode;
1da177e4 230 int error;
95582b00 231 struct timespec64 now;
1da177e4
LT
232 unsigned int ia_valid = attr->ia_valid;
233
5955102c 234 WARN_ON_ONCE(!inode_is_locked(inode));
c4107b30 235
beb29e05
MS
236 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
f2b20f6e
MS
241 /*
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
69b45732 256 if ((ia_valid & ATTR_MODE)) {
8d334acd 257 umode_t amode = attr->ia_mode;
69b45732
AK
258 /* Flag setting protected by i_mutex */
259 if (is_sxid(amode))
260 inode->i_flags &= ~S_NOSEC;
261 }
262
c2050a45 263 now = current_time(inode);
1da177e4
LT
264
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;
b5376771 270 if (ia_valid & ATTR_KILL_PRIV) {
b5376771 271 error = security_inode_need_killpriv(dentry);
030b533c 272 if (error < 0)
b5376771 273 return error;
030b533c
JK
274 if (error == 0)
275 ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV;
b5376771 276 }
6de0ec00
JL
277
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
1da177e4 289 if (ia_valid & ATTR_KILL_SUID) {
1da177e4 290 if (mode & S_ISUID) {
6de0ec00
JL
291 ia_valid = attr->ia_valid |= ATTR_MODE;
292 attr->ia_mode = (inode->i_mode & ~S_ISUID);
1da177e4
LT
293 }
294 }
295 if (ia_valid & ATTR_KILL_SGID) {
1da177e4
LT
296 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 }
6de0ec00 304 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
1da177e4
LT
305 return 0;
306
a475acf0
SF
307 /*
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
0bd23d09
EB
318 /* 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
a77b72da 326 error = security_inode_setattr(dentry, attr);
27ac0ffe
BF
327 if (error)
328 return error;
329 error = try_break_deleg(inode, delegated_inode);
a77b72da
MS
330 if (error)
331 return error;
332
eef2380c 333 if (inode->i_op->setattr)
a77b72da 334 error = inode->i_op->setattr(dentry, attr);
eef2380c
CH
335 else
336 error = simple_setattr(dentry, attr);
1da177e4 337
975d2943 338 if (!error) {
0eeca283 339 fsnotify_change(dentry, ia_valid);
9957a504 340 ima_inode_post_setattr(dentry);
975d2943
MZ
341 evm_inode_post_setattr(dentry, ia_valid);
342 }
0eeca283 343
1da177e4
LT
344 return error;
345}
1da177e4 346EXPORT_SYMBOL(notify_change);