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; | |
8eac98b8 | 22 | const struct cred *old_cred; |
e9be9d5e MS |
23 | |
24 | parent = dget_parent(dentry); | |
25 | err = ovl_copy_up(parent); | |
26 | if (err) | |
27 | goto out_dput_parent; | |
28 | ||
29 | ovl_path_lower(dentry, &lowerpath); | |
e9be9d5e | 30 | |
8eac98b8 VG |
31 | old_cred = ovl_override_creds(dentry->d_sb); |
32 | err = vfs_getattr(&lowerpath, &stat); | |
33 | if (!err) { | |
34 | stat.size = 0; | |
35 | err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat); | |
36 | } | |
37 | revert_creds(old_cred); | |
e9be9d5e MS |
38 | |
39 | out_dput_parent: | |
40 | dput(parent); | |
41 | return err; | |
42 | } | |
43 | ||
44 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) | |
45 | { | |
46 | int err; | |
47 | struct dentry *upperdentry; | |
1175b6b8 | 48 | const struct cred *old_cred; |
e9be9d5e | 49 | |
cf9a6784 MS |
50 | /* |
51 | * Check for permissions before trying to copy-up. This is redundant | |
52 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
53 | * without this, copy-up can be triggered by just about anybody. | |
54 | * | |
55 | * We don't initialize inode->size, which just means that | |
56 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
57 | * check for a swapfile (which this won't be anyway). | |
58 | */ | |
31051c85 | 59 | err = setattr_prepare(dentry, attr); |
cf9a6784 MS |
60 | if (err) |
61 | return err; | |
62 | ||
e9be9d5e MS |
63 | err = ovl_want_write(dentry); |
64 | if (err) | |
65 | goto out; | |
66 | ||
acff81ec MS |
67 | err = ovl_copy_up(dentry); |
68 | if (!err) { | |
69 | upperdentry = ovl_dentry_upper(dentry); | |
70 | ||
b99c2d91 MS |
71 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
72 | attr->ia_valid &= ~ATTR_MODE; | |
73 | ||
5955102c | 74 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 75 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 76 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 77 | revert_creds(old_cred); |
b81de061 KK |
78 | if (!err) |
79 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 80 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
81 | } |
82 | ovl_drop_write(dentry); | |
83 | out: | |
84 | return err; | |
85 | } | |
86 | ||
87 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
88 | struct kstat *stat) | |
89 | { | |
90 | struct path realpath; | |
1175b6b8 VG |
91 | const struct cred *old_cred; |
92 | int err; | |
e9be9d5e MS |
93 | |
94 | ovl_path_real(dentry, &realpath); | |
1175b6b8 VG |
95 | old_cred = ovl_override_creds(dentry->d_sb); |
96 | err = vfs_getattr(&realpath, stat); | |
97 | revert_creds(old_cred); | |
98 | return err; | |
e9be9d5e MS |
99 | } |
100 | ||
101 | int ovl_permission(struct inode *inode, int mask) | |
102 | { | |
e9be9d5e | 103 | bool is_upper; |
39b681f8 | 104 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 105 | const struct cred *old_cred; |
e9be9d5e MS |
106 | int err; |
107 | ||
e9be9d5e | 108 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
109 | if (!realinode) { |
110 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 111 | return -ECHILD; |
e9be9d5e MS |
112 | } |
113 | ||
c0ca3d70 VG |
114 | /* |
115 | * Check overlay inode with the creds of task and underlying inode | |
116 | * with creds of mounter | |
117 | */ | |
118 | err = generic_permission(inode, mask); | |
119 | if (err) | |
120 | return err; | |
121 | ||
122 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 123 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 124 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
125 | /* Make sure mounter can read file for copy up later */ |
126 | mask |= MAY_READ; | |
127 | } | |
9c630ebe | 128 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
129 | revert_creds(old_cred); |
130 | ||
131 | return err; | |
e9be9d5e MS |
132 | } |
133 | ||
6b255391 | 134 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
135 | struct inode *inode, |
136 | struct delayed_call *done) | |
e9be9d5e | 137 | { |
1175b6b8 VG |
138 | const struct cred *old_cred; |
139 | const char *p; | |
e9be9d5e | 140 | |
6b255391 AV |
141 | if (!dentry) |
142 | return ERR_PTR(-ECHILD); | |
143 | ||
1175b6b8 | 144 | old_cred = ovl_override_creds(dentry->d_sb); |
7764235b | 145 | p = vfs_get_link(ovl_dentry_real(dentry), done); |
1175b6b8 VG |
146 | revert_creds(old_cred); |
147 | return p; | |
e9be9d5e MS |
148 | } |
149 | ||
0956254a | 150 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 151 | { |
fe2b7595 AG |
152 | return strncmp(name, OVL_XATTR_PREFIX, |
153 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
154 | } |
155 | ||
0e585ccc AG |
156 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
157 | size_t size, int flags) | |
e9be9d5e MS |
158 | { |
159 | int err; | |
0e585ccc AG |
160 | struct path realpath; |
161 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 162 | const struct cred *old_cred; |
e9be9d5e MS |
163 | |
164 | err = ovl_want_write(dentry); | |
165 | if (err) | |
166 | goto out; | |
167 | ||
0e585ccc AG |
168 | if (!value && !OVL_TYPE_UPPER(type)) { |
169 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
170 | if (err < 0) | |
171 | goto out_drop_write; | |
172 | } | |
173 | ||
e9be9d5e MS |
174 | err = ovl_copy_up(dentry); |
175 | if (err) | |
176 | goto out_drop_write; | |
177 | ||
0e585ccc AG |
178 | if (!OVL_TYPE_UPPER(type)) |
179 | ovl_path_upper(dentry, &realpath); | |
180 | ||
1175b6b8 | 181 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
182 | if (value) |
183 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
184 | else { | |
185 | WARN_ON(flags != XATTR_REPLACE); | |
186 | err = vfs_removexattr(realpath.dentry, name); | |
187 | } | |
1175b6b8 | 188 | revert_creds(old_cred); |
e9be9d5e MS |
189 | |
190 | out_drop_write: | |
191 | ovl_drop_write(dentry); | |
192 | out: | |
193 | return err; | |
194 | } | |
195 | ||
0eb45fc3 AG |
196 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
197 | void *value, size_t size) | |
e9be9d5e | 198 | { |
b581755b | 199 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
200 | ssize_t res; |
201 | const struct cred *old_cred; | |
52148463 | 202 | |
1175b6b8 VG |
203 | old_cred = ovl_override_creds(dentry->d_sb); |
204 | res = vfs_getxattr(realdentry, name, value, size); | |
205 | revert_creds(old_cred); | |
206 | return res; | |
e9be9d5e MS |
207 | } |
208 | ||
209 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
210 | { | |
b581755b | 211 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 212 | ssize_t res; |
7cb35119 MS |
213 | size_t len; |
214 | char *s; | |
1175b6b8 | 215 | const struct cred *old_cred; |
e9be9d5e | 216 | |
1175b6b8 | 217 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 218 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 219 | revert_creds(old_cred); |
e9be9d5e MS |
220 | if (res <= 0 || size == 0) |
221 | return res; | |
222 | ||
e9be9d5e | 223 | /* filter out private xattrs */ |
7cb35119 MS |
224 | for (s = list, len = res; len;) { |
225 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 226 | |
7cb35119 MS |
227 | /* underlying fs providing us with an broken xattr list? */ |
228 | if (WARN_ON(slen > len)) | |
229 | return -EIO; | |
e9be9d5e | 230 | |
7cb35119 | 231 | len -= slen; |
e9be9d5e MS |
232 | if (ovl_is_private_xattr(s)) { |
233 | res -= slen; | |
7cb35119 | 234 | memmove(s, s + slen, len); |
e9be9d5e | 235 | } else { |
7cb35119 | 236 | s += slen; |
e9be9d5e MS |
237 | } |
238 | } | |
239 | ||
240 | return res; | |
241 | } | |
242 | ||
39a25b2b VG |
243 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
244 | { | |
39b681f8 | 245 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
246 | const struct cred *old_cred; |
247 | struct posix_acl *acl; | |
39a25b2b | 248 | |
5201dc44 | 249 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
250 | return NULL; |
251 | ||
1175b6b8 | 252 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 253 | acl = get_acl(realinode, type); |
1175b6b8 VG |
254 | revert_creds(old_cred); |
255 | ||
256 | return acl; | |
39a25b2b VG |
257 | } |
258 | ||
e9be9d5e MS |
259 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
260 | struct dentry *realdentry) | |
261 | { | |
1afaba1e | 262 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
263 | return false; |
264 | ||
265 | if (special_file(realdentry->d_inode->i_mode)) | |
266 | return false; | |
267 | ||
268 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
269 | return false; | |
270 | ||
271 | return true; | |
272 | } | |
273 | ||
2d902671 | 274 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 275 | { |
2d902671 | 276 | int err = 0; |
e9be9d5e MS |
277 | struct path realpath; |
278 | enum ovl_path_type type; | |
e9be9d5e MS |
279 | |
280 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 281 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 282 | err = ovl_want_write(dentry); |
2d902671 MS |
283 | if (!err) { |
284 | if (file_flags & O_TRUNC) | |
285 | err = ovl_copy_up_truncate(dentry); | |
286 | else | |
287 | err = ovl_copy_up(dentry); | |
288 | ovl_drop_write(dentry); | |
289 | } | |
e9be9d5e MS |
290 | } |
291 | ||
2d902671 | 292 | return err; |
e9be9d5e MS |
293 | } |
294 | ||
d719e8f2 MS |
295 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
296 | { | |
297 | struct dentry *alias; | |
298 | struct path upperpath; | |
299 | ||
300 | if (!(flags & S_ATIME)) | |
301 | return 0; | |
302 | ||
303 | alias = d_find_any_alias(inode); | |
304 | if (!alias) | |
305 | return 0; | |
306 | ||
307 | ovl_path_upper(alias, &upperpath); | |
308 | if (upperpath.dentry) { | |
309 | touch_atime(&upperpath); | |
310 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
311 | } | |
312 | ||
313 | dput(alias); | |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
e9be9d5e MS |
318 | static const struct inode_operations ovl_file_inode_operations = { |
319 | .setattr = ovl_setattr, | |
320 | .permission = ovl_permission, | |
321 | .getattr = ovl_getattr, | |
e9be9d5e | 322 | .listxattr = ovl_listxattr, |
39a25b2b | 323 | .get_acl = ovl_get_acl, |
d719e8f2 | 324 | .update_time = ovl_update_time, |
e9be9d5e MS |
325 | }; |
326 | ||
327 | static const struct inode_operations ovl_symlink_inode_operations = { | |
328 | .setattr = ovl_setattr, | |
6b255391 | 329 | .get_link = ovl_get_link, |
78a3fa4f | 330 | .readlink = generic_readlink, |
e9be9d5e | 331 | .getattr = ovl_getattr, |
e9be9d5e | 332 | .listxattr = ovl_listxattr, |
d719e8f2 | 333 | .update_time = ovl_update_time, |
e9be9d5e MS |
334 | }; |
335 | ||
ca4c8a3a | 336 | static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) |
e9be9d5e | 337 | { |
e9be9d5e MS |
338 | inode->i_ino = get_next_ino(); |
339 | inode->i_mode = mode; | |
d719e8f2 | 340 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
341 | #ifdef CONFIG_FS_POSIX_ACL |
342 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
343 | #endif | |
e9be9d5e | 344 | |
ca4c8a3a MS |
345 | switch (mode & S_IFMT) { |
346 | case S_IFREG: | |
347 | inode->i_op = &ovl_file_inode_operations; | |
348 | break; | |
349 | ||
e9be9d5e | 350 | case S_IFDIR: |
e9be9d5e MS |
351 | inode->i_op = &ovl_dir_inode_operations; |
352 | inode->i_fop = &ovl_dir_operations; | |
353 | break; | |
354 | ||
355 | case S_IFLNK: | |
356 | inode->i_op = &ovl_symlink_inode_operations; | |
357 | break; | |
358 | ||
51f7e52d | 359 | default: |
e9be9d5e | 360 | inode->i_op = &ovl_file_inode_operations; |
ca4c8a3a | 361 | init_special_inode(inode, mode, rdev); |
e9be9d5e | 362 | break; |
51f7e52d MS |
363 | } |
364 | } | |
e9be9d5e | 365 | |
ca4c8a3a | 366 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
51f7e52d MS |
367 | { |
368 | struct inode *inode; | |
369 | ||
370 | inode = new_inode(sb); | |
371 | if (inode) | |
ca4c8a3a | 372 | ovl_fill_inode(inode, mode, rdev); |
51f7e52d MS |
373 | |
374 | return inode; | |
375 | } | |
376 | ||
377 | static int ovl_inode_test(struct inode *inode, void *data) | |
378 | { | |
379 | return ovl_inode_real(inode, NULL) == data; | |
380 | } | |
381 | ||
382 | static int ovl_inode_set(struct inode *inode, void *data) | |
383 | { | |
384 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
385 | return 0; | |
386 | } | |
387 | ||
388 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
389 | ||
390 | { | |
391 | struct inode *inode; | |
392 | ||
393 | inode = iget5_locked(sb, (unsigned long) realinode, | |
394 | ovl_inode_test, ovl_inode_set, realinode); | |
395 | if (inode && inode->i_state & I_NEW) { | |
ca4c8a3a | 396 | ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); |
51f7e52d MS |
397 | set_nlink(inode, realinode->i_nlink); |
398 | unlock_new_inode(inode); | |
e9be9d5e MS |
399 | } |
400 | ||
401 | return inode; | |
e9be9d5e | 402 | } |