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> | |
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 | ||
acff81ec MS |
64 | err = ovl_copy_up(dentry); |
65 | if (!err) { | |
66 | upperdentry = ovl_dentry_upper(dentry); | |
67 | ||
b99c2d91 MS |
68 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
69 | attr->ia_valid &= ~ATTR_MODE; | |
70 | ||
5955102c | 71 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 72 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 73 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 74 | revert_creds(old_cred); |
b81de061 KK |
75 | if (!err) |
76 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 77 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
78 | } |
79 | ovl_drop_write(dentry); | |
80 | out: | |
81 | return err; | |
82 | } | |
83 | ||
84 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
85 | struct kstat *stat) | |
86 | { | |
87 | struct path realpath; | |
1175b6b8 VG |
88 | const struct cred *old_cred; |
89 | int err; | |
e9be9d5e MS |
90 | |
91 | ovl_path_real(dentry, &realpath); | |
1175b6b8 VG |
92 | old_cred = ovl_override_creds(dentry->d_sb); |
93 | err = vfs_getattr(&realpath, stat); | |
94 | revert_creds(old_cred); | |
95 | return err; | |
e9be9d5e MS |
96 | } |
97 | ||
98 | int ovl_permission(struct inode *inode, int mask) | |
99 | { | |
e9be9d5e | 100 | bool is_upper; |
39b681f8 | 101 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 102 | const struct cred *old_cred; |
e9be9d5e MS |
103 | int err; |
104 | ||
e9be9d5e | 105 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
106 | if (!realinode) { |
107 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 108 | return -ECHILD; |
e9be9d5e MS |
109 | } |
110 | ||
c0ca3d70 VG |
111 | /* |
112 | * Check overlay inode with the creds of task and underlying inode | |
113 | * with creds of mounter | |
114 | */ | |
115 | err = generic_permission(inode, mask); | |
116 | if (err) | |
117 | return err; | |
118 | ||
119 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 120 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 121 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
122 | /* Make sure mounter can read file for copy up later */ |
123 | mask |= MAY_READ; | |
124 | } | |
9c630ebe | 125 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
126 | revert_creds(old_cred); |
127 | ||
128 | return err; | |
e9be9d5e MS |
129 | } |
130 | ||
6b255391 | 131 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
132 | struct inode *inode, |
133 | struct delayed_call *done) | |
e9be9d5e | 134 | { |
e9be9d5e MS |
135 | struct dentry *realdentry; |
136 | struct inode *realinode; | |
1175b6b8 VG |
137 | const struct cred *old_cred; |
138 | const char *p; | |
e9be9d5e | 139 | |
6b255391 AV |
140 | if (!dentry) |
141 | return ERR_PTR(-ECHILD); | |
142 | ||
e9be9d5e MS |
143 | realdentry = ovl_dentry_real(dentry); |
144 | realinode = realdentry->d_inode; | |
145 | ||
6b255391 | 146 | if (WARN_ON(!realinode->i_op->get_link)) |
e9be9d5e MS |
147 | return ERR_PTR(-EPERM); |
148 | ||
1175b6b8 VG |
149 | old_cred = ovl_override_creds(dentry->d_sb); |
150 | p = realinode->i_op->get_link(realdentry, realinode, done); | |
151 | revert_creds(old_cred); | |
152 | return p; | |
e9be9d5e MS |
153 | } |
154 | ||
155 | static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) | |
156 | { | |
157 | struct path realpath; | |
158 | struct inode *realinode; | |
1175b6b8 VG |
159 | const struct cred *old_cred; |
160 | int err; | |
e9be9d5e MS |
161 | |
162 | ovl_path_real(dentry, &realpath); | |
163 | realinode = realpath.dentry->d_inode; | |
164 | ||
165 | if (!realinode->i_op->readlink) | |
166 | return -EINVAL; | |
167 | ||
1175b6b8 VG |
168 | old_cred = ovl_override_creds(dentry->d_sb); |
169 | err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz); | |
170 | revert_creds(old_cred); | |
171 | return err; | |
e9be9d5e MS |
172 | } |
173 | ||
0956254a | 174 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 175 | { |
fe2b7595 AG |
176 | return strncmp(name, OVL_XATTR_PREFIX, |
177 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
178 | } |
179 | ||
0e585ccc AG |
180 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
181 | size_t size, int flags) | |
e9be9d5e MS |
182 | { |
183 | int err; | |
0e585ccc AG |
184 | struct path realpath; |
185 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 186 | const struct cred *old_cred; |
e9be9d5e MS |
187 | |
188 | err = ovl_want_write(dentry); | |
189 | if (err) | |
190 | goto out; | |
191 | ||
0e585ccc AG |
192 | if (!value && !OVL_TYPE_UPPER(type)) { |
193 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
194 | if (err < 0) | |
195 | goto out_drop_write; | |
196 | } | |
197 | ||
e9be9d5e MS |
198 | err = ovl_copy_up(dentry); |
199 | if (err) | |
200 | goto out_drop_write; | |
201 | ||
0e585ccc AG |
202 | if (!OVL_TYPE_UPPER(type)) |
203 | ovl_path_upper(dentry, &realpath); | |
204 | ||
1175b6b8 | 205 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
206 | if (value) |
207 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
208 | else { | |
209 | WARN_ON(flags != XATTR_REPLACE); | |
210 | err = vfs_removexattr(realpath.dentry, name); | |
211 | } | |
1175b6b8 | 212 | revert_creds(old_cred); |
e9be9d5e MS |
213 | |
214 | out_drop_write: | |
215 | ovl_drop_write(dentry); | |
216 | out: | |
217 | return err; | |
218 | } | |
219 | ||
0eb45fc3 AG |
220 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
221 | void *value, size_t size) | |
e9be9d5e | 222 | { |
b581755b | 223 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
224 | ssize_t res; |
225 | const struct cred *old_cred; | |
52148463 | 226 | |
1175b6b8 VG |
227 | old_cred = ovl_override_creds(dentry->d_sb); |
228 | res = vfs_getxattr(realdentry, name, value, size); | |
229 | revert_creds(old_cred); | |
230 | return res; | |
e9be9d5e MS |
231 | } |
232 | ||
233 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
234 | { | |
b581755b | 235 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 236 | ssize_t res; |
7cb35119 MS |
237 | size_t len; |
238 | char *s; | |
1175b6b8 | 239 | const struct cred *old_cred; |
e9be9d5e | 240 | |
1175b6b8 | 241 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 242 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 243 | revert_creds(old_cred); |
e9be9d5e MS |
244 | if (res <= 0 || size == 0) |
245 | return res; | |
246 | ||
e9be9d5e | 247 | /* filter out private xattrs */ |
7cb35119 MS |
248 | for (s = list, len = res; len;) { |
249 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 250 | |
7cb35119 MS |
251 | /* underlying fs providing us with an broken xattr list? */ |
252 | if (WARN_ON(slen > len)) | |
253 | return -EIO; | |
e9be9d5e | 254 | |
7cb35119 | 255 | len -= slen; |
e9be9d5e MS |
256 | if (ovl_is_private_xattr(s)) { |
257 | res -= slen; | |
7cb35119 | 258 | memmove(s, s + slen, len); |
e9be9d5e | 259 | } else { |
7cb35119 | 260 | s += slen; |
e9be9d5e MS |
261 | } |
262 | } | |
263 | ||
264 | return res; | |
265 | } | |
266 | ||
39a25b2b VG |
267 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
268 | { | |
39b681f8 | 269 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
270 | const struct cred *old_cred; |
271 | struct posix_acl *acl; | |
39a25b2b | 272 | |
5201dc44 | 273 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
274 | return NULL; |
275 | ||
276 | if (!realinode->i_op->get_acl) | |
277 | return NULL; | |
278 | ||
1175b6b8 | 279 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 280 | acl = get_acl(realinode, type); |
1175b6b8 VG |
281 | revert_creds(old_cred); |
282 | ||
283 | return acl; | |
39a25b2b VG |
284 | } |
285 | ||
e9be9d5e MS |
286 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
287 | struct dentry *realdentry) | |
288 | { | |
1afaba1e | 289 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
290 | return false; |
291 | ||
292 | if (special_file(realdentry->d_inode->i_mode)) | |
293 | return false; | |
294 | ||
295 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
296 | return false; | |
297 | ||
298 | return true; | |
299 | } | |
300 | ||
2d902671 | 301 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 302 | { |
2d902671 | 303 | int err = 0; |
e9be9d5e MS |
304 | struct path realpath; |
305 | enum ovl_path_type type; | |
e9be9d5e MS |
306 | |
307 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 308 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 309 | err = ovl_want_write(dentry); |
2d902671 MS |
310 | if (!err) { |
311 | if (file_flags & O_TRUNC) | |
312 | err = ovl_copy_up_truncate(dentry); | |
313 | else | |
314 | err = ovl_copy_up(dentry); | |
315 | ovl_drop_write(dentry); | |
316 | } | |
e9be9d5e MS |
317 | } |
318 | ||
2d902671 | 319 | return err; |
e9be9d5e MS |
320 | } |
321 | ||
d719e8f2 MS |
322 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
323 | { | |
324 | struct dentry *alias; | |
325 | struct path upperpath; | |
326 | ||
327 | if (!(flags & S_ATIME)) | |
328 | return 0; | |
329 | ||
330 | alias = d_find_any_alias(inode); | |
331 | if (!alias) | |
332 | return 0; | |
333 | ||
334 | ovl_path_upper(alias, &upperpath); | |
335 | if (upperpath.dentry) { | |
336 | touch_atime(&upperpath); | |
337 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
338 | } | |
339 | ||
340 | dput(alias); | |
341 | ||
342 | return 0; | |
343 | } | |
344 | ||
e9be9d5e MS |
345 | static const struct inode_operations ovl_file_inode_operations = { |
346 | .setattr = ovl_setattr, | |
347 | .permission = ovl_permission, | |
348 | .getattr = ovl_getattr, | |
d837a49b | 349 | .setxattr = generic_setxattr, |
0eb45fc3 | 350 | .getxattr = generic_getxattr, |
e9be9d5e | 351 | .listxattr = ovl_listxattr, |
0e585ccc | 352 | .removexattr = generic_removexattr, |
39a25b2b | 353 | .get_acl = ovl_get_acl, |
d719e8f2 | 354 | .update_time = ovl_update_time, |
e9be9d5e MS |
355 | }; |
356 | ||
357 | static const struct inode_operations ovl_symlink_inode_operations = { | |
358 | .setattr = ovl_setattr, | |
6b255391 | 359 | .get_link = ovl_get_link, |
e9be9d5e MS |
360 | .readlink = ovl_readlink, |
361 | .getattr = ovl_getattr, | |
d837a49b | 362 | .setxattr = generic_setxattr, |
0eb45fc3 | 363 | .getxattr = generic_getxattr, |
e9be9d5e | 364 | .listxattr = ovl_listxattr, |
0e585ccc | 365 | .removexattr = generic_removexattr, |
d719e8f2 | 366 | .update_time = ovl_update_time, |
e9be9d5e MS |
367 | }; |
368 | ||
51f7e52d | 369 | static void ovl_fill_inode(struct inode *inode, umode_t mode) |
e9be9d5e | 370 | { |
e9be9d5e MS |
371 | inode->i_ino = get_next_ino(); |
372 | inode->i_mode = mode; | |
d719e8f2 | 373 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
374 | #ifdef CONFIG_FS_POSIX_ACL |
375 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
376 | #endif | |
e9be9d5e | 377 | |
07a2daab | 378 | mode &= S_IFMT; |
e9be9d5e MS |
379 | switch (mode) { |
380 | case S_IFDIR: | |
e9be9d5e MS |
381 | inode->i_op = &ovl_dir_inode_operations; |
382 | inode->i_fop = &ovl_dir_operations; | |
383 | break; | |
384 | ||
385 | case S_IFLNK: | |
386 | inode->i_op = &ovl_symlink_inode_operations; | |
387 | break; | |
388 | ||
51f7e52d MS |
389 | default: |
390 | WARN(1, "illegal file type: %i\n", mode); | |
391 | /* Fall through */ | |
392 | ||
e9be9d5e MS |
393 | case S_IFREG: |
394 | case S_IFSOCK: | |
395 | case S_IFBLK: | |
396 | case S_IFCHR: | |
397 | case S_IFIFO: | |
398 | inode->i_op = &ovl_file_inode_operations; | |
399 | break; | |
51f7e52d MS |
400 | } |
401 | } | |
e9be9d5e | 402 | |
51f7e52d MS |
403 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode) |
404 | { | |
405 | struct inode *inode; | |
406 | ||
407 | inode = new_inode(sb); | |
408 | if (inode) | |
409 | ovl_fill_inode(inode, mode); | |
410 | ||
411 | return inode; | |
412 | } | |
413 | ||
414 | static int ovl_inode_test(struct inode *inode, void *data) | |
415 | { | |
416 | return ovl_inode_real(inode, NULL) == data; | |
417 | } | |
418 | ||
419 | static int ovl_inode_set(struct inode *inode, void *data) | |
420 | { | |
421 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
422 | return 0; | |
423 | } | |
424 | ||
425 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
426 | ||
427 | { | |
428 | struct inode *inode; | |
429 | ||
430 | inode = iget5_locked(sb, (unsigned long) realinode, | |
431 | ovl_inode_test, ovl_inode_set, realinode); | |
432 | if (inode && inode->i_state & I_NEW) { | |
433 | ovl_fill_inode(inode, realinode->i_mode); | |
434 | set_nlink(inode, realinode->i_nlink); | |
435 | unlock_new_inode(inode); | |
e9be9d5e MS |
436 | } |
437 | ||
438 | return inode; | |
e9be9d5e | 439 | } |