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Commit | Line | Data |
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e9be9d5e MS |
1 | /* |
2 | * | |
3 | * Copyright (C) 2011 Novell Inc. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License version 2 as published by | |
7 | * the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/fs.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/xattr.h> | |
5201dc44 | 13 | #include <linux/posix_acl.h> |
e9be9d5e MS |
14 | #include "overlayfs.h" |
15 | ||
0f7ff2da | 16 | static int ovl_copy_up_truncate(struct dentry *dentry) |
e9be9d5e MS |
17 | { |
18 | int err; | |
19 | struct dentry *parent; | |
20 | struct kstat stat; | |
21 | struct path lowerpath; | |
22 | ||
23 | parent = dget_parent(dentry); | |
24 | err = ovl_copy_up(parent); | |
25 | if (err) | |
26 | goto out_dput_parent; | |
27 | ||
28 | ovl_path_lower(dentry, &lowerpath); | |
29 | err = vfs_getattr(&lowerpath, &stat); | |
30 | if (err) | |
31 | goto out_dput_parent; | |
32 | ||
0f7ff2da AV |
33 | stat.size = 0; |
34 | err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); | |
e9be9d5e MS |
35 | |
36 | out_dput_parent: | |
37 | dput(parent); | |
38 | return err; | |
39 | } | |
40 | ||
41 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) | |
42 | { | |
43 | int err; | |
44 | struct dentry *upperdentry; | |
1175b6b8 | 45 | const struct cred *old_cred; |
e9be9d5e | 46 | |
cf9a6784 MS |
47 | /* |
48 | * Check for permissions before trying to copy-up. This is redundant | |
49 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
50 | * without this, copy-up can be triggered by just about anybody. | |
51 | * | |
52 | * We don't initialize inode->size, which just means that | |
53 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
54 | * check for a swapfile (which this won't be anyway). | |
55 | */ | |
56 | err = inode_change_ok(dentry->d_inode, attr); | |
57 | if (err) | |
58 | return err; | |
59 | ||
e9be9d5e MS |
60 | err = ovl_want_write(dentry); |
61 | if (err) | |
62 | goto out; | |
63 | ||
03bea604 MS |
64 | if (attr->ia_valid & ATTR_SIZE) { |
65 | struct inode *realinode = d_inode(ovl_dentry_real(dentry)); | |
66 | ||
67 | err = -ETXTBSY; | |
68 | if (atomic_read(&realinode->i_writecount) < 0) | |
69 | goto out_drop_write; | |
70 | } | |
71 | ||
acff81ec MS |
72 | err = ovl_copy_up(dentry); |
73 | if (!err) { | |
03bea604 MS |
74 | struct inode *winode = NULL; |
75 | ||
acff81ec MS |
76 | upperdentry = ovl_dentry_upper(dentry); |
77 | ||
03bea604 MS |
78 | if (attr->ia_valid & ATTR_SIZE) { |
79 | winode = d_inode(upperdentry); | |
80 | err = get_write_access(winode); | |
81 | if (err) | |
82 | goto out_drop_write; | |
83 | } | |
84 | ||
b99c2d91 MS |
85 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
86 | attr->ia_valid &= ~ATTR_MODE; | |
87 | ||
5955102c | 88 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 89 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 90 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 91 | revert_creds(old_cred); |
b81de061 KK |
92 | if (!err) |
93 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 94 | inode_unlock(upperdentry->d_inode); |
03bea604 MS |
95 | |
96 | if (winode) | |
97 | put_write_access(winode); | |
e9be9d5e | 98 | } |
03bea604 | 99 | out_drop_write: |
e9be9d5e MS |
100 | ovl_drop_write(dentry); |
101 | out: | |
102 | return err; | |
103 | } | |
104 | ||
105 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
106 | struct kstat *stat) | |
107 | { | |
108 | struct path realpath; | |
1175b6b8 VG |
109 | const struct cred *old_cred; |
110 | int err; | |
e9be9d5e MS |
111 | |
112 | ovl_path_real(dentry, &realpath); | |
1175b6b8 VG |
113 | old_cred = ovl_override_creds(dentry->d_sb); |
114 | err = vfs_getattr(&realpath, stat); | |
115 | revert_creds(old_cred); | |
116 | return err; | |
e9be9d5e MS |
117 | } |
118 | ||
119 | int ovl_permission(struct inode *inode, int mask) | |
120 | { | |
e9be9d5e | 121 | bool is_upper; |
39b681f8 | 122 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 123 | const struct cred *old_cred; |
e9be9d5e MS |
124 | int err; |
125 | ||
e9be9d5e | 126 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
127 | if (!realinode) { |
128 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 129 | return -ECHILD; |
e9be9d5e MS |
130 | } |
131 | ||
c0ca3d70 VG |
132 | /* |
133 | * Check overlay inode with the creds of task and underlying inode | |
134 | * with creds of mounter | |
135 | */ | |
136 | err = generic_permission(inode, mask); | |
137 | if (err) | |
138 | return err; | |
139 | ||
140 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 141 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 142 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
143 | /* Make sure mounter can read file for copy up later */ |
144 | mask |= MAY_READ; | |
145 | } | |
9c630ebe | 146 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
147 | revert_creds(old_cred); |
148 | ||
149 | return err; | |
e9be9d5e MS |
150 | } |
151 | ||
6b255391 | 152 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
153 | struct inode *inode, |
154 | struct delayed_call *done) | |
e9be9d5e | 155 | { |
e9be9d5e MS |
156 | struct dentry *realdentry; |
157 | struct inode *realinode; | |
1175b6b8 VG |
158 | const struct cred *old_cred; |
159 | const char *p; | |
e9be9d5e | 160 | |
6b255391 AV |
161 | if (!dentry) |
162 | return ERR_PTR(-ECHILD); | |
163 | ||
e9be9d5e MS |
164 | realdentry = ovl_dentry_real(dentry); |
165 | realinode = realdentry->d_inode; | |
166 | ||
6b255391 | 167 | if (WARN_ON(!realinode->i_op->get_link)) |
e9be9d5e MS |
168 | return ERR_PTR(-EPERM); |
169 | ||
1175b6b8 VG |
170 | old_cred = ovl_override_creds(dentry->d_sb); |
171 | p = realinode->i_op->get_link(realdentry, realinode, done); | |
172 | revert_creds(old_cred); | |
173 | return p; | |
e9be9d5e MS |
174 | } |
175 | ||
176 | static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) | |
177 | { | |
178 | struct path realpath; | |
179 | struct inode *realinode; | |
1175b6b8 VG |
180 | const struct cred *old_cred; |
181 | int err; | |
e9be9d5e MS |
182 | |
183 | ovl_path_real(dentry, &realpath); | |
184 | realinode = realpath.dentry->d_inode; | |
185 | ||
186 | if (!realinode->i_op->readlink) | |
187 | return -EINVAL; | |
188 | ||
1175b6b8 VG |
189 | old_cred = ovl_override_creds(dentry->d_sb); |
190 | err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz); | |
191 | revert_creds(old_cred); | |
192 | return err; | |
e9be9d5e MS |
193 | } |
194 | ||
0956254a | 195 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 196 | { |
fe2b7595 AG |
197 | return strncmp(name, OVL_XATTR_PREFIX, |
198 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
199 | } |
200 | ||
0e585ccc AG |
201 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
202 | size_t size, int flags) | |
e9be9d5e MS |
203 | { |
204 | int err; | |
0e585ccc AG |
205 | struct path realpath; |
206 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 207 | const struct cred *old_cred; |
e9be9d5e MS |
208 | |
209 | err = ovl_want_write(dentry); | |
210 | if (err) | |
211 | goto out; | |
212 | ||
0e585ccc AG |
213 | if (!value && !OVL_TYPE_UPPER(type)) { |
214 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
215 | if (err < 0) | |
216 | goto out_drop_write; | |
217 | } | |
218 | ||
e9be9d5e MS |
219 | err = ovl_copy_up(dentry); |
220 | if (err) | |
221 | goto out_drop_write; | |
222 | ||
0e585ccc AG |
223 | if (!OVL_TYPE_UPPER(type)) |
224 | ovl_path_upper(dentry, &realpath); | |
225 | ||
1175b6b8 | 226 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
227 | if (value) |
228 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
229 | else { | |
230 | WARN_ON(flags != XATTR_REPLACE); | |
231 | err = vfs_removexattr(realpath.dentry, name); | |
232 | } | |
1175b6b8 | 233 | revert_creds(old_cred); |
e9be9d5e MS |
234 | |
235 | out_drop_write: | |
236 | ovl_drop_write(dentry); | |
237 | out: | |
238 | return err; | |
239 | } | |
240 | ||
0eb45fc3 AG |
241 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
242 | void *value, size_t size) | |
e9be9d5e | 243 | { |
b581755b | 244 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
245 | ssize_t res; |
246 | const struct cred *old_cred; | |
52148463 | 247 | |
1175b6b8 VG |
248 | old_cred = ovl_override_creds(dentry->d_sb); |
249 | res = vfs_getxattr(realdentry, name, value, size); | |
250 | revert_creds(old_cred); | |
251 | return res; | |
e9be9d5e MS |
252 | } |
253 | ||
254 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
255 | { | |
b581755b | 256 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e MS |
257 | ssize_t res; |
258 | int off; | |
1175b6b8 | 259 | const struct cred *old_cred; |
e9be9d5e | 260 | |
1175b6b8 | 261 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 262 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 263 | revert_creds(old_cred); |
e9be9d5e MS |
264 | if (res <= 0 || size == 0) |
265 | return res; | |
266 | ||
e9be9d5e MS |
267 | /* filter out private xattrs */ |
268 | for (off = 0; off < res;) { | |
269 | char *s = list + off; | |
270 | size_t slen = strlen(s) + 1; | |
271 | ||
272 | BUG_ON(off + slen > res); | |
273 | ||
274 | if (ovl_is_private_xattr(s)) { | |
275 | res -= slen; | |
276 | memmove(s, s + slen, res - off); | |
277 | } else { | |
278 | off += slen; | |
279 | } | |
280 | } | |
281 | ||
282 | return res; | |
283 | } | |
284 | ||
39a25b2b VG |
285 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
286 | { | |
39b681f8 | 287 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
288 | const struct cred *old_cred; |
289 | struct posix_acl *acl; | |
39a25b2b | 290 | |
5201dc44 | 291 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
292 | return NULL; |
293 | ||
294 | if (!realinode->i_op->get_acl) | |
295 | return NULL; | |
296 | ||
1175b6b8 | 297 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 298 | acl = get_acl(realinode, type); |
1175b6b8 VG |
299 | revert_creds(old_cred); |
300 | ||
301 | return acl; | |
39a25b2b VG |
302 | } |
303 | ||
e9be9d5e MS |
304 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
305 | struct dentry *realdentry) | |
306 | { | |
1afaba1e | 307 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
308 | return false; |
309 | ||
310 | if (special_file(realdentry->d_inode->i_mode)) | |
311 | return false; | |
312 | ||
313 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
314 | return false; | |
315 | ||
316 | return true; | |
317 | } | |
318 | ||
2d902671 | 319 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 320 | { |
2d902671 | 321 | int err = 0; |
e9be9d5e MS |
322 | struct path realpath; |
323 | enum ovl_path_type type; | |
e9be9d5e MS |
324 | |
325 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 326 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 327 | err = ovl_want_write(dentry); |
2d902671 MS |
328 | if (!err) { |
329 | if (file_flags & O_TRUNC) | |
330 | err = ovl_copy_up_truncate(dentry); | |
331 | else | |
332 | err = ovl_copy_up(dentry); | |
333 | ovl_drop_write(dentry); | |
334 | } | |
e9be9d5e MS |
335 | } |
336 | ||
2d902671 | 337 | return err; |
e9be9d5e MS |
338 | } |
339 | ||
d719e8f2 MS |
340 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
341 | { | |
342 | struct dentry *alias; | |
343 | struct path upperpath; | |
344 | ||
345 | if (!(flags & S_ATIME)) | |
346 | return 0; | |
347 | ||
348 | alias = d_find_any_alias(inode); | |
349 | if (!alias) | |
350 | return 0; | |
351 | ||
352 | ovl_path_upper(alias, &upperpath); | |
353 | if (upperpath.dentry) { | |
354 | touch_atime(&upperpath); | |
355 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
356 | } | |
357 | ||
358 | dput(alias); | |
359 | ||
360 | return 0; | |
361 | } | |
362 | ||
e9be9d5e MS |
363 | static const struct inode_operations ovl_file_inode_operations = { |
364 | .setattr = ovl_setattr, | |
365 | .permission = ovl_permission, | |
366 | .getattr = ovl_getattr, | |
d837a49b | 367 | .setxattr = generic_setxattr, |
0eb45fc3 | 368 | .getxattr = generic_getxattr, |
e9be9d5e | 369 | .listxattr = ovl_listxattr, |
0e585ccc | 370 | .removexattr = generic_removexattr, |
39a25b2b | 371 | .get_acl = ovl_get_acl, |
d719e8f2 | 372 | .update_time = ovl_update_time, |
e9be9d5e MS |
373 | }; |
374 | ||
375 | static const struct inode_operations ovl_symlink_inode_operations = { | |
376 | .setattr = ovl_setattr, | |
6b255391 | 377 | .get_link = ovl_get_link, |
e9be9d5e MS |
378 | .readlink = ovl_readlink, |
379 | .getattr = ovl_getattr, | |
d837a49b | 380 | .setxattr = generic_setxattr, |
0eb45fc3 | 381 | .getxattr = generic_getxattr, |
e9be9d5e | 382 | .listxattr = ovl_listxattr, |
0e585ccc | 383 | .removexattr = generic_removexattr, |
d719e8f2 | 384 | .update_time = ovl_update_time, |
e9be9d5e MS |
385 | }; |
386 | ||
51f7e52d | 387 | static void ovl_fill_inode(struct inode *inode, umode_t mode) |
e9be9d5e | 388 | { |
e9be9d5e MS |
389 | inode->i_ino = get_next_ino(); |
390 | inode->i_mode = mode; | |
d719e8f2 | 391 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
392 | #ifdef CONFIG_FS_POSIX_ACL |
393 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
394 | #endif | |
e9be9d5e | 395 | |
07a2daab | 396 | mode &= S_IFMT; |
e9be9d5e MS |
397 | switch (mode) { |
398 | case S_IFDIR: | |
e9be9d5e MS |
399 | inode->i_op = &ovl_dir_inode_operations; |
400 | inode->i_fop = &ovl_dir_operations; | |
401 | break; | |
402 | ||
403 | case S_IFLNK: | |
404 | inode->i_op = &ovl_symlink_inode_operations; | |
405 | break; | |
406 | ||
51f7e52d MS |
407 | default: |
408 | WARN(1, "illegal file type: %i\n", mode); | |
409 | /* Fall through */ | |
410 | ||
e9be9d5e MS |
411 | case S_IFREG: |
412 | case S_IFSOCK: | |
413 | case S_IFBLK: | |
414 | case S_IFCHR: | |
415 | case S_IFIFO: | |
416 | inode->i_op = &ovl_file_inode_operations; | |
417 | break; | |
51f7e52d MS |
418 | } |
419 | } | |
e9be9d5e | 420 | |
51f7e52d MS |
421 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode) |
422 | { | |
423 | struct inode *inode; | |
424 | ||
425 | inode = new_inode(sb); | |
426 | if (inode) | |
427 | ovl_fill_inode(inode, mode); | |
428 | ||
429 | return inode; | |
430 | } | |
431 | ||
432 | static int ovl_inode_test(struct inode *inode, void *data) | |
433 | { | |
434 | return ovl_inode_real(inode, NULL) == data; | |
435 | } | |
436 | ||
437 | static int ovl_inode_set(struct inode *inode, void *data) | |
438 | { | |
439 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
440 | return 0; | |
441 | } | |
442 | ||
443 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
444 | ||
445 | { | |
446 | struct inode *inode; | |
447 | ||
448 | inode = iget5_locked(sb, (unsigned long) realinode, | |
449 | ovl_inode_test, ovl_inode_set, realinode); | |
450 | if (inode && inode->i_state & I_NEW) { | |
451 | ovl_fill_inode(inode, realinode->i_mode); | |
452 | set_nlink(inode, realinode->i_nlink); | |
453 | unlock_new_inode(inode); | |
e9be9d5e MS |
454 | } |
455 | ||
456 | return inode; | |
e9be9d5e | 457 | } |