Commit | Line | Data |
---|---|---|
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> | |
13 | #include "overlayfs.h" | |
14 | ||
0f7ff2da | 15 | static int ovl_copy_up_truncate(struct dentry *dentry) |
e9be9d5e MS |
16 | { |
17 | int err; | |
18 | struct dentry *parent; | |
19 | struct kstat stat; | |
20 | struct path lowerpath; | |
21 | ||
22 | parent = dget_parent(dentry); | |
23 | err = ovl_copy_up(parent); | |
24 | if (err) | |
25 | goto out_dput_parent; | |
26 | ||
27 | ovl_path_lower(dentry, &lowerpath); | |
28 | err = vfs_getattr(&lowerpath, &stat); | |
29 | if (err) | |
30 | goto out_dput_parent; | |
31 | ||
0f7ff2da AV |
32 | stat.size = 0; |
33 | err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); | |
e9be9d5e MS |
34 | |
35 | out_dput_parent: | |
36 | dput(parent); | |
37 | return err; | |
38 | } | |
39 | ||
40 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) | |
41 | { | |
42 | int err; | |
43 | struct dentry *upperdentry; | |
1175b6b8 | 44 | const struct cred *old_cred; |
e9be9d5e | 45 | |
cf9a6784 MS |
46 | /* |
47 | * Check for permissions before trying to copy-up. This is redundant | |
48 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
49 | * without this, copy-up can be triggered by just about anybody. | |
50 | * | |
51 | * We don't initialize inode->size, which just means that | |
52 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
53 | * check for a swapfile (which this won't be anyway). | |
54 | */ | |
55 | err = inode_change_ok(dentry->d_inode, attr); | |
56 | if (err) | |
57 | return err; | |
58 | ||
e9be9d5e MS |
59 | err = ovl_want_write(dentry); |
60 | if (err) | |
61 | goto out; | |
62 | ||
03bea604 MS |
63 | if (attr->ia_valid & ATTR_SIZE) { |
64 | struct inode *realinode = d_inode(ovl_dentry_real(dentry)); | |
65 | ||
66 | err = -ETXTBSY; | |
67 | if (atomic_read(&realinode->i_writecount) < 0) | |
68 | goto out_drop_write; | |
69 | } | |
70 | ||
acff81ec MS |
71 | err = ovl_copy_up(dentry); |
72 | if (!err) { | |
03bea604 MS |
73 | struct inode *winode = NULL; |
74 | ||
acff81ec MS |
75 | upperdentry = ovl_dentry_upper(dentry); |
76 | ||
03bea604 MS |
77 | if (attr->ia_valid & ATTR_SIZE) { |
78 | winode = d_inode(upperdentry); | |
79 | err = get_write_access(winode); | |
80 | if (err) | |
81 | goto out_drop_write; | |
82 | } | |
83 | ||
b99c2d91 MS |
84 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
85 | attr->ia_valid &= ~ATTR_MODE; | |
86 | ||
5955102c | 87 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 88 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 89 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 90 | revert_creds(old_cred); |
b81de061 KK |
91 | if (!err) |
92 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 93 | inode_unlock(upperdentry->d_inode); |
03bea604 MS |
94 | |
95 | if (winode) | |
96 | put_write_access(winode); | |
e9be9d5e | 97 | } |
03bea604 | 98 | out_drop_write: |
e9be9d5e MS |
99 | ovl_drop_write(dentry); |
100 | out: | |
101 | return err; | |
102 | } | |
103 | ||
104 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
105 | struct kstat *stat) | |
106 | { | |
107 | struct path realpath; | |
1175b6b8 VG |
108 | const struct cred *old_cred; |
109 | int err; | |
e9be9d5e MS |
110 | |
111 | ovl_path_real(dentry, &realpath); | |
1175b6b8 VG |
112 | old_cred = ovl_override_creds(dentry->d_sb); |
113 | err = vfs_getattr(&realpath, stat); | |
114 | revert_creds(old_cred); | |
115 | return err; | |
e9be9d5e MS |
116 | } |
117 | ||
118 | int ovl_permission(struct inode *inode, int mask) | |
119 | { | |
e9be9d5e | 120 | bool is_upper; |
39b681f8 | 121 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 122 | const struct cred *old_cred; |
e9be9d5e MS |
123 | int err; |
124 | ||
e9be9d5e | 125 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
126 | if (!realinode) { |
127 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 128 | return -ECHILD; |
e9be9d5e MS |
129 | } |
130 | ||
c0ca3d70 VG |
131 | /* |
132 | * Check overlay inode with the creds of task and underlying inode | |
133 | * with creds of mounter | |
134 | */ | |
135 | err = generic_permission(inode, mask); | |
136 | if (err) | |
137 | return err; | |
138 | ||
139 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 140 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 141 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
142 | /* Make sure mounter can read file for copy up later */ |
143 | mask |= MAY_READ; | |
144 | } | |
9c630ebe | 145 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
146 | revert_creds(old_cred); |
147 | ||
148 | return err; | |
e9be9d5e MS |
149 | } |
150 | ||
6b255391 | 151 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
152 | struct inode *inode, |
153 | struct delayed_call *done) | |
e9be9d5e | 154 | { |
e9be9d5e MS |
155 | struct dentry *realdentry; |
156 | struct inode *realinode; | |
1175b6b8 VG |
157 | const struct cred *old_cred; |
158 | const char *p; | |
e9be9d5e | 159 | |
6b255391 AV |
160 | if (!dentry) |
161 | return ERR_PTR(-ECHILD); | |
162 | ||
e9be9d5e MS |
163 | realdentry = ovl_dentry_real(dentry); |
164 | realinode = realdentry->d_inode; | |
165 | ||
6b255391 | 166 | if (WARN_ON(!realinode->i_op->get_link)) |
e9be9d5e MS |
167 | return ERR_PTR(-EPERM); |
168 | ||
1175b6b8 VG |
169 | old_cred = ovl_override_creds(dentry->d_sb); |
170 | p = realinode->i_op->get_link(realdentry, realinode, done); | |
171 | revert_creds(old_cred); | |
172 | return p; | |
e9be9d5e MS |
173 | } |
174 | ||
175 | static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) | |
176 | { | |
177 | struct path realpath; | |
178 | struct inode *realinode; | |
1175b6b8 VG |
179 | const struct cred *old_cred; |
180 | int err; | |
e9be9d5e MS |
181 | |
182 | ovl_path_real(dentry, &realpath); | |
183 | realinode = realpath.dentry->d_inode; | |
184 | ||
185 | if (!realinode->i_op->readlink) | |
186 | return -EINVAL; | |
187 | ||
1175b6b8 VG |
188 | old_cred = ovl_override_creds(dentry->d_sb); |
189 | err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz); | |
190 | revert_creds(old_cred); | |
191 | return err; | |
e9be9d5e MS |
192 | } |
193 | ||
e9be9d5e MS |
194 | static bool ovl_is_private_xattr(const char *name) |
195 | { | |
d837a49b MS |
196 | #define OVL_XATTR_PRE_NAME OVL_XATTR_PREFIX "." |
197 | return strncmp(name, OVL_XATTR_PRE_NAME, | |
198 | sizeof(OVL_XATTR_PRE_NAME) - 1) == 0; | |
e9be9d5e MS |
199 | } |
200 | ||
3767e255 AV |
201 | int ovl_setxattr(struct dentry *dentry, struct inode *inode, |
202 | const char *name, const void *value, | |
203 | size_t size, int flags) | |
e9be9d5e MS |
204 | { |
205 | int err; | |
206 | struct dentry *upperdentry; | |
1175b6b8 | 207 | const struct cred *old_cred; |
e9be9d5e MS |
208 | |
209 | err = ovl_want_write(dentry); | |
210 | if (err) | |
211 | goto out; | |
212 | ||
e9be9d5e MS |
213 | err = ovl_copy_up(dentry); |
214 | if (err) | |
215 | goto out_drop_write; | |
216 | ||
217 | upperdentry = ovl_dentry_upper(dentry); | |
1175b6b8 | 218 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 219 | err = vfs_setxattr(upperdentry, name, value, size, flags); |
1175b6b8 | 220 | revert_creds(old_cred); |
e9be9d5e MS |
221 | |
222 | out_drop_write: | |
223 | ovl_drop_write(dentry); | |
224 | out: | |
225 | return err; | |
226 | } | |
227 | ||
ce23e640 AV |
228 | ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode, |
229 | const char *name, void *value, size_t size) | |
e9be9d5e | 230 | { |
b581755b | 231 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
232 | ssize_t res; |
233 | const struct cred *old_cred; | |
52148463 | 234 | |
b581755b | 235 | if (ovl_is_private_xattr(name)) |
e9be9d5e MS |
236 | return -ENODATA; |
237 | ||
1175b6b8 VG |
238 | old_cred = ovl_override_creds(dentry->d_sb); |
239 | res = vfs_getxattr(realdentry, name, value, size); | |
240 | revert_creds(old_cred); | |
241 | return res; | |
e9be9d5e MS |
242 | } |
243 | ||
244 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
245 | { | |
b581755b | 246 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e MS |
247 | ssize_t res; |
248 | int off; | |
1175b6b8 | 249 | const struct cred *old_cred; |
e9be9d5e | 250 | |
1175b6b8 | 251 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 252 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 253 | revert_creds(old_cred); |
e9be9d5e MS |
254 | if (res <= 0 || size == 0) |
255 | return res; | |
256 | ||
e9be9d5e MS |
257 | /* filter out private xattrs */ |
258 | for (off = 0; off < res;) { | |
259 | char *s = list + off; | |
260 | size_t slen = strlen(s) + 1; | |
261 | ||
262 | BUG_ON(off + slen > res); | |
263 | ||
264 | if (ovl_is_private_xattr(s)) { | |
265 | res -= slen; | |
266 | memmove(s, s + slen, res - off); | |
267 | } else { | |
268 | off += slen; | |
269 | } | |
270 | } | |
271 | ||
272 | return res; | |
273 | } | |
274 | ||
275 | int ovl_removexattr(struct dentry *dentry, const char *name) | |
276 | { | |
277 | int err; | |
278 | struct path realpath; | |
52148463 | 279 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); |
1175b6b8 | 280 | const struct cred *old_cred; |
e9be9d5e MS |
281 | |
282 | err = ovl_want_write(dentry); | |
283 | if (err) | |
284 | goto out; | |
285 | ||
52148463 | 286 | err = -ENODATA; |
b581755b | 287 | if (ovl_is_private_xattr(name)) |
e9be9d5e MS |
288 | goto out_drop_write; |
289 | ||
1afaba1e | 290 | if (!OVL_TYPE_UPPER(type)) { |
e9be9d5e MS |
291 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); |
292 | if (err < 0) | |
293 | goto out_drop_write; | |
294 | ||
295 | err = ovl_copy_up(dentry); | |
296 | if (err) | |
297 | goto out_drop_write; | |
298 | ||
299 | ovl_path_upper(dentry, &realpath); | |
300 | } | |
301 | ||
1175b6b8 | 302 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 303 | err = vfs_removexattr(realpath.dentry, name); |
1175b6b8 | 304 | revert_creds(old_cred); |
e9be9d5e MS |
305 | out_drop_write: |
306 | ovl_drop_write(dentry); | |
307 | out: | |
308 | return err; | |
309 | } | |
310 | ||
39a25b2b VG |
311 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
312 | { | |
39b681f8 | 313 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
314 | const struct cred *old_cred; |
315 | struct posix_acl *acl; | |
39a25b2b | 316 | |
39a25b2b VG |
317 | if (!IS_POSIXACL(realinode)) |
318 | return NULL; | |
319 | ||
320 | if (!realinode->i_op->get_acl) | |
321 | return NULL; | |
322 | ||
1175b6b8 VG |
323 | old_cred = ovl_override_creds(inode->i_sb); |
324 | acl = realinode->i_op->get_acl(realinode, type); | |
325 | revert_creds(old_cred); | |
326 | ||
327 | return acl; | |
39a25b2b VG |
328 | } |
329 | ||
e9be9d5e MS |
330 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
331 | struct dentry *realdentry) | |
332 | { | |
1afaba1e | 333 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
334 | return false; |
335 | ||
336 | if (special_file(realdentry->d_inode->i_mode)) | |
337 | return false; | |
338 | ||
339 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
340 | return false; | |
341 | ||
342 | return true; | |
343 | } | |
344 | ||
2d902671 | 345 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 346 | { |
2d902671 | 347 | int err = 0; |
e9be9d5e MS |
348 | struct path realpath; |
349 | enum ovl_path_type type; | |
e9be9d5e MS |
350 | |
351 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 352 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 353 | err = ovl_want_write(dentry); |
2d902671 MS |
354 | if (!err) { |
355 | if (file_flags & O_TRUNC) | |
356 | err = ovl_copy_up_truncate(dentry); | |
357 | else | |
358 | err = ovl_copy_up(dentry); | |
359 | ovl_drop_write(dentry); | |
360 | } | |
e9be9d5e MS |
361 | } |
362 | ||
2d902671 | 363 | return err; |
e9be9d5e MS |
364 | } |
365 | ||
d719e8f2 MS |
366 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
367 | { | |
368 | struct dentry *alias; | |
369 | struct path upperpath; | |
370 | ||
371 | if (!(flags & S_ATIME)) | |
372 | return 0; | |
373 | ||
374 | alias = d_find_any_alias(inode); | |
375 | if (!alias) | |
376 | return 0; | |
377 | ||
378 | ovl_path_upper(alias, &upperpath); | |
379 | if (upperpath.dentry) { | |
380 | touch_atime(&upperpath); | |
381 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
382 | } | |
383 | ||
384 | dput(alias); | |
385 | ||
386 | return 0; | |
387 | } | |
388 | ||
e9be9d5e MS |
389 | static const struct inode_operations ovl_file_inode_operations = { |
390 | .setattr = ovl_setattr, | |
391 | .permission = ovl_permission, | |
392 | .getattr = ovl_getattr, | |
d837a49b | 393 | .setxattr = generic_setxattr, |
e9be9d5e MS |
394 | .getxattr = ovl_getxattr, |
395 | .listxattr = ovl_listxattr, | |
396 | .removexattr = ovl_removexattr, | |
39a25b2b | 397 | .get_acl = ovl_get_acl, |
d719e8f2 | 398 | .update_time = ovl_update_time, |
e9be9d5e MS |
399 | }; |
400 | ||
401 | static const struct inode_operations ovl_symlink_inode_operations = { | |
402 | .setattr = ovl_setattr, | |
6b255391 | 403 | .get_link = ovl_get_link, |
e9be9d5e MS |
404 | .readlink = ovl_readlink, |
405 | .getattr = ovl_getattr, | |
d837a49b | 406 | .setxattr = generic_setxattr, |
e9be9d5e MS |
407 | .getxattr = ovl_getxattr, |
408 | .listxattr = ovl_listxattr, | |
409 | .removexattr = ovl_removexattr, | |
d719e8f2 | 410 | .update_time = ovl_update_time, |
e9be9d5e MS |
411 | }; |
412 | ||
51f7e52d | 413 | static void ovl_fill_inode(struct inode *inode, umode_t mode) |
e9be9d5e | 414 | { |
e9be9d5e MS |
415 | inode->i_ino = get_next_ino(); |
416 | inode->i_mode = mode; | |
d719e8f2 | 417 | inode->i_flags |= S_NOCMTIME; |
e9be9d5e | 418 | |
07a2daab | 419 | mode &= S_IFMT; |
e9be9d5e MS |
420 | switch (mode) { |
421 | case S_IFDIR: | |
e9be9d5e MS |
422 | inode->i_op = &ovl_dir_inode_operations; |
423 | inode->i_fop = &ovl_dir_operations; | |
424 | break; | |
425 | ||
426 | case S_IFLNK: | |
427 | inode->i_op = &ovl_symlink_inode_operations; | |
428 | break; | |
429 | ||
51f7e52d MS |
430 | default: |
431 | WARN(1, "illegal file type: %i\n", mode); | |
432 | /* Fall through */ | |
433 | ||
e9be9d5e MS |
434 | case S_IFREG: |
435 | case S_IFSOCK: | |
436 | case S_IFBLK: | |
437 | case S_IFCHR: | |
438 | case S_IFIFO: | |
439 | inode->i_op = &ovl_file_inode_operations; | |
440 | break; | |
51f7e52d MS |
441 | } |
442 | } | |
e9be9d5e | 443 | |
51f7e52d MS |
444 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode) |
445 | { | |
446 | struct inode *inode; | |
447 | ||
448 | inode = new_inode(sb); | |
449 | if (inode) | |
450 | ovl_fill_inode(inode, mode); | |
451 | ||
452 | return inode; | |
453 | } | |
454 | ||
455 | static int ovl_inode_test(struct inode *inode, void *data) | |
456 | { | |
457 | return ovl_inode_real(inode, NULL) == data; | |
458 | } | |
459 | ||
460 | static int ovl_inode_set(struct inode *inode, void *data) | |
461 | { | |
462 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
463 | return 0; | |
464 | } | |
465 | ||
466 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
467 | ||
468 | { | |
469 | struct inode *inode; | |
470 | ||
471 | inode = iget5_locked(sb, (unsigned long) realinode, | |
472 | ovl_inode_test, ovl_inode_set, realinode); | |
473 | if (inode && inode->i_state & I_NEW) { | |
474 | ovl_fill_inode(inode, realinode->i_mode); | |
475 | set_nlink(inode, realinode->i_nlink); | |
476 | unlock_new_inode(inode); | |
e9be9d5e MS |
477 | } |
478 | ||
479 | return inode; | |
e9be9d5e | 480 | } |