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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/attr.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * changes by Thomas Schoebel-Theuer | |
6 | */ | |
7 | ||
630d9c47 | 8 | #include <linux/export.h> |
1da177e4 LT |
9 | #include <linux/time.h> |
10 | #include <linux/mm.h> | |
11 | #include <linux/string.h> | |
16f7e0fe | 12 | #include <linux/capability.h> |
0eeca283 | 13 | #include <linux/fsnotify.h> |
1da177e4 | 14 | #include <linux/fcntl.h> |
1da177e4 | 15 | #include <linux/security.h> |
975d2943 | 16 | #include <linux/evm.h> |
9957a504 | 17 | #include <linux/ima.h> |
1da177e4 | 18 | |
2c27c65e | 19 | /** |
31051c85 JK |
20 | * setattr_prepare - check if attribute changes to a dentry are allowed |
21 | * @dentry: dentry to check | |
2c27c65e CH |
22 | * @attr: attributes to change |
23 | * | |
24 | * Check if we are allowed to change the attributes contained in @attr | |
31051c85 JK |
25 | * in the given dentry. This includes the normal unix access permission |
26 | * checks, as well as checks for rlimits and others. The function also clears | |
27 | * SGID bit from mode if user is not allowed to set it. Also file capabilities | |
28 | * and IMA extended attributes are cleared if ATTR_KILL_PRIV is set. | |
2c27c65e CH |
29 | * |
30 | * Should be called as the first thing in ->setattr implementations, | |
31 | * possibly after taking additional locks. | |
32 | */ | |
31051c85 | 33 | int setattr_prepare(struct dentry *dentry, struct iattr *attr) |
1da177e4 | 34 | { |
31051c85 | 35 | struct inode *inode = d_inode(dentry); |
1da177e4 LT |
36 | unsigned int ia_valid = attr->ia_valid; |
37 | ||
2c27c65e CH |
38 | /* |
39 | * First check size constraints. These can't be overriden using | |
40 | * ATTR_FORCE. | |
41 | */ | |
42 | if (ia_valid & ATTR_SIZE) { | |
43 | int error = inode_newsize_ok(inode, attr->ia_size); | |
44 | if (error) | |
45 | return error; | |
46 | } | |
47 | ||
1da177e4 LT |
48 | /* If force is set do it anyway. */ |
49 | if (ia_valid & ATTR_FORCE) | |
030b533c | 50 | goto kill_priv; |
1da177e4 LT |
51 | |
52 | /* Make sure a caller can chown. */ | |
53 | if ((ia_valid & ATTR_UID) && | |
8e96e3b7 | 54 | (!uid_eq(current_fsuid(), inode->i_uid) || |
7fa294c8 | 55 | !uid_eq(attr->ia_uid, inode->i_uid)) && |
23adbe12 | 56 | !capable_wrt_inode_uidgid(inode, CAP_CHOWN)) |
2c27c65e | 57 | return -EPERM; |
1da177e4 LT |
58 | |
59 | /* Make sure caller can chgrp. */ | |
60 | if ((ia_valid & ATTR_GID) && | |
8e96e3b7 EB |
61 | (!uid_eq(current_fsuid(), inode->i_uid) || |
62 | (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) && | |
23adbe12 | 63 | !capable_wrt_inode_uidgid(inode, CAP_CHOWN)) |
2c27c65e | 64 | return -EPERM; |
1da177e4 LT |
65 | |
66 | /* Make sure a caller can chmod. */ | |
67 | if (ia_valid & ATTR_MODE) { | |
2e149670 | 68 | if (!inode_owner_or_capable(inode)) |
2c27c65e | 69 | return -EPERM; |
1da177e4 LT |
70 | /* Also check the setgid bit! */ |
71 | if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : | |
7fa294c8 | 72 | inode->i_gid) && |
23adbe12 | 73 | !capable_wrt_inode_uidgid(inode, CAP_FSETID)) |
1da177e4 LT |
74 | attr->ia_mode &= ~S_ISGID; |
75 | } | |
76 | ||
77 | /* Check for setting the inode time. */ | |
9767d749 | 78 | if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { |
2e149670 | 79 | if (!inode_owner_or_capable(inode)) |
2c27c65e | 80 | return -EPERM; |
1da177e4 | 81 | } |
2c27c65e | 82 | |
030b533c JK |
83 | kill_priv: |
84 | /* User has permission for the change */ | |
85 | if (ia_valid & ATTR_KILL_PRIV) { | |
86 | int error; | |
87 | ||
88 | error = security_inode_killpriv(dentry); | |
89 | if (error) | |
90 | return error; | |
91 | } | |
92 | ||
2c27c65e | 93 | return 0; |
1da177e4 | 94 | } |
31051c85 | 95 | EXPORT_SYMBOL(setattr_prepare); |
1da177e4 | 96 | |
25d9e2d1 NP |
97 | /** |
98 | * inode_newsize_ok - may this inode be truncated to a given size | |
99 | * @inode: the inode to be truncated | |
100 | * @offset: the new size to assign to the inode | |
101 | * @Returns: 0 on success, -ve errno on failure | |
102 | * | |
7bb46a67 NP |
103 | * inode_newsize_ok must be called with i_mutex held. |
104 | * | |
25d9e2d1 NP |
105 | * inode_newsize_ok will check filesystem limits and ulimits to check that the |
106 | * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ | |
107 | * when necessary. Caller must not proceed with inode size change if failure is | |
108 | * returned. @inode must be a file (not directory), with appropriate | |
109 | * permissions to allow truncate (inode_newsize_ok does NOT check these | |
110 | * conditions). | |
25d9e2d1 NP |
111 | */ |
112 | int inode_newsize_ok(const struct inode *inode, loff_t offset) | |
113 | { | |
114 | if (inode->i_size < offset) { | |
115 | unsigned long limit; | |
116 | ||
d554ed89 | 117 | limit = rlimit(RLIMIT_FSIZE); |
25d9e2d1 NP |
118 | if (limit != RLIM_INFINITY && offset > limit) |
119 | goto out_sig; | |
120 | if (offset > inode->i_sb->s_maxbytes) | |
121 | goto out_big; | |
122 | } else { | |
123 | /* | |
124 | * truncation of in-use swapfiles is disallowed - it would | |
125 | * cause subsequent swapout to scribble on the now-freed | |
126 | * blocks. | |
127 | */ | |
128 | if (IS_SWAPFILE(inode)) | |
129 | return -ETXTBSY; | |
130 | } | |
131 | ||
132 | return 0; | |
133 | out_sig: | |
134 | send_sig(SIGXFSZ, current, 0); | |
135 | out_big: | |
136 | return -EFBIG; | |
137 | } | |
138 | EXPORT_SYMBOL(inode_newsize_ok); | |
139 | ||
7bb46a67 | 140 | /** |
6a1a90ad | 141 | * setattr_copy - copy simple metadata updates into the generic inode |
7bb46a67 NP |
142 | * @inode: the inode to be updated |
143 | * @attr: the new attributes | |
144 | * | |
6a1a90ad | 145 | * setattr_copy must be called with i_mutex held. |
7bb46a67 | 146 | * |
6a1a90ad | 147 | * setattr_copy updates the inode's metadata with that specified |
25985edc | 148 | * in attr. Noticeably missing is inode size update, which is more complex |
2c27c65e | 149 | * as it requires pagecache updates. |
7bb46a67 NP |
150 | * |
151 | * The inode is not marked as dirty after this operation. The rationale is | |
152 | * that for "simple" filesystems, the struct inode is the inode storage. | |
153 | * The caller is free to mark the inode dirty afterwards if needed. | |
154 | */ | |
6a1a90ad | 155 | void setattr_copy(struct inode *inode, const struct iattr *attr) |
1da177e4 LT |
156 | { |
157 | unsigned int ia_valid = attr->ia_valid; | |
4a30131e | 158 | |
1da177e4 LT |
159 | if (ia_valid & ATTR_UID) |
160 | inode->i_uid = attr->ia_uid; | |
161 | if (ia_valid & ATTR_GID) | |
162 | inode->i_gid = attr->ia_gid; | |
163 | if (ia_valid & ATTR_ATIME) | |
164 | inode->i_atime = timespec_trunc(attr->ia_atime, | |
165 | inode->i_sb->s_time_gran); | |
166 | if (ia_valid & ATTR_MTIME) | |
167 | inode->i_mtime = timespec_trunc(attr->ia_mtime, | |
168 | inode->i_sb->s_time_gran); | |
169 | if (ia_valid & ATTR_CTIME) | |
170 | inode->i_ctime = timespec_trunc(attr->ia_ctime, | |
171 | inode->i_sb->s_time_gran); | |
172 | if (ia_valid & ATTR_MODE) { | |
173 | umode_t mode = attr->ia_mode; | |
174 | ||
7fa294c8 | 175 | if (!in_group_p(inode->i_gid) && |
23adbe12 | 176 | !capable_wrt_inode_uidgid(inode, CAP_FSETID)) |
1da177e4 LT |
177 | mode &= ~S_ISGID; |
178 | inode->i_mode = mode; | |
179 | } | |
7bb46a67 | 180 | } |
6a1a90ad | 181 | EXPORT_SYMBOL(setattr_copy); |
7bb46a67 | 182 | |
27ac0ffe BF |
183 | /** |
184 | * notify_change - modify attributes of a filesytem object | |
185 | * @dentry: object affected | |
186 | * @iattr: new attributes | |
187 | * @delegated_inode: returns inode, if the inode is delegated | |
188 | * | |
189 | * The caller must hold the i_mutex on the affected object. | |
190 | * | |
191 | * If notify_change discovers a delegation in need of breaking, | |
192 | * it will return -EWOULDBLOCK and return a reference to the inode in | |
193 | * delegated_inode. The caller should then break the delegation and | |
194 | * retry. Because breaking a delegation may take a long time, the | |
195 | * caller should drop the i_mutex before doing so. | |
196 | * | |
197 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
198 | * be appropriate for callers that expect the underlying filesystem not | |
199 | * to be NFS exported. Also, passing NULL is fine for callers holding | |
200 | * the file open for write, as there can be no conflicting delegation in | |
201 | * that case. | |
202 | */ | |
203 | int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode) | |
1da177e4 LT |
204 | { |
205 | struct inode *inode = dentry->d_inode; | |
8d334acd | 206 | umode_t mode = inode->i_mode; |
1da177e4 LT |
207 | int error; |
208 | struct timespec now; | |
209 | unsigned int ia_valid = attr->ia_valid; | |
210 | ||
5955102c | 211 | WARN_ON_ONCE(!inode_is_locked(inode)); |
c4107b30 | 212 | |
beb29e05 MS |
213 | if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { |
214 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
215 | return -EPERM; | |
216 | } | |
217 | ||
f2b20f6e MS |
218 | /* |
219 | * If utimes(2) and friends are called with times == NULL (or both | |
220 | * times are UTIME_NOW), then we need to check for write permission | |
221 | */ | |
222 | if (ia_valid & ATTR_TOUCH) { | |
223 | if (IS_IMMUTABLE(inode)) | |
224 | return -EPERM; | |
225 | ||
226 | if (!inode_owner_or_capable(inode)) { | |
227 | error = inode_permission(inode, MAY_WRITE); | |
228 | if (error) | |
229 | return error; | |
230 | } | |
231 | } | |
232 | ||
69b45732 | 233 | if ((ia_valid & ATTR_MODE)) { |
8d334acd | 234 | umode_t amode = attr->ia_mode; |
69b45732 AK |
235 | /* Flag setting protected by i_mutex */ |
236 | if (is_sxid(amode)) | |
237 | inode->i_flags &= ~S_NOSEC; | |
238 | } | |
239 | ||
c2050a45 | 240 | now = current_time(inode); |
1da177e4 LT |
241 | |
242 | attr->ia_ctime = now; | |
243 | if (!(ia_valid & ATTR_ATIME_SET)) | |
244 | attr->ia_atime = now; | |
245 | if (!(ia_valid & ATTR_MTIME_SET)) | |
246 | attr->ia_mtime = now; | |
b5376771 | 247 | if (ia_valid & ATTR_KILL_PRIV) { |
b5376771 | 248 | error = security_inode_need_killpriv(dentry); |
030b533c | 249 | if (error < 0) |
b5376771 | 250 | return error; |
030b533c JK |
251 | if (error == 0) |
252 | ia_valid = attr->ia_valid &= ~ATTR_KILL_PRIV; | |
b5376771 | 253 | } |
6de0ec00 JL |
254 | |
255 | /* | |
256 | * We now pass ATTR_KILL_S*ID to the lower level setattr function so | |
257 | * that the function has the ability to reinterpret a mode change | |
258 | * that's due to these bits. This adds an implicit restriction that | |
259 | * no function will ever call notify_change with both ATTR_MODE and | |
260 | * ATTR_KILL_S*ID set. | |
261 | */ | |
262 | if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) && | |
263 | (ia_valid & ATTR_MODE)) | |
264 | BUG(); | |
265 | ||
1da177e4 | 266 | if (ia_valid & ATTR_KILL_SUID) { |
1da177e4 | 267 | if (mode & S_ISUID) { |
6de0ec00 JL |
268 | ia_valid = attr->ia_valid |= ATTR_MODE; |
269 | attr->ia_mode = (inode->i_mode & ~S_ISUID); | |
1da177e4 LT |
270 | } |
271 | } | |
272 | if (ia_valid & ATTR_KILL_SGID) { | |
1da177e4 LT |
273 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
274 | if (!(ia_valid & ATTR_MODE)) { | |
275 | ia_valid = attr->ia_valid |= ATTR_MODE; | |
276 | attr->ia_mode = inode->i_mode; | |
277 | } | |
278 | attr->ia_mode &= ~S_ISGID; | |
279 | } | |
280 | } | |
6de0ec00 | 281 | if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID))) |
1da177e4 LT |
282 | return 0; |
283 | ||
a475acf0 SF |
284 | /* |
285 | * Verify that uid/gid changes are valid in the target | |
286 | * namespace of the superblock. | |
287 | */ | |
288 | if (ia_valid & ATTR_UID && | |
289 | !kuid_has_mapping(inode->i_sb->s_user_ns, attr->ia_uid)) | |
290 | return -EOVERFLOW; | |
291 | if (ia_valid & ATTR_GID && | |
292 | !kgid_has_mapping(inode->i_sb->s_user_ns, attr->ia_gid)) | |
293 | return -EOVERFLOW; | |
294 | ||
0bd23d09 EB |
295 | /* Don't allow modifications of files with invalid uids or |
296 | * gids unless those uids & gids are being made valid. | |
297 | */ | |
298 | if (!(ia_valid & ATTR_UID) && !uid_valid(inode->i_uid)) | |
299 | return -EOVERFLOW; | |
300 | if (!(ia_valid & ATTR_GID) && !gid_valid(inode->i_gid)) | |
301 | return -EOVERFLOW; | |
302 | ||
a77b72da | 303 | error = security_inode_setattr(dentry, attr); |
27ac0ffe BF |
304 | if (error) |
305 | return error; | |
306 | error = try_break_deleg(inode, delegated_inode); | |
a77b72da MS |
307 | if (error) |
308 | return error; | |
309 | ||
eef2380c | 310 | if (inode->i_op->setattr) |
a77b72da | 311 | error = inode->i_op->setattr(dentry, attr); |
eef2380c CH |
312 | else |
313 | error = simple_setattr(dentry, attr); | |
1da177e4 | 314 | |
975d2943 | 315 | if (!error) { |
0eeca283 | 316 | fsnotify_change(dentry, ia_valid); |
9957a504 | 317 | ima_inode_post_setattr(dentry); |
975d2943 MZ |
318 | evm_inode_post_setattr(dentry, ia_valid); |
319 | } | |
0eeca283 | 320 | |
1da177e4 LT |
321 | return error; |
322 | } | |
1da177e4 | 323 | EXPORT_SYMBOL(notify_change); |