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> | |
5b825c3a | 12 | #include <linux/cred.h> |
e9be9d5e | 13 | #include <linux/xattr.h> |
5201dc44 | 14 | #include <linux/posix_acl.h> |
e9be9d5e MS |
15 | #include "overlayfs.h" |
16 | ||
e9be9d5e MS |
17 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) |
18 | { | |
19 | int err; | |
20 | struct dentry *upperdentry; | |
1175b6b8 | 21 | const struct cred *old_cred; |
e9be9d5e | 22 | |
cf9a6784 MS |
23 | /* |
24 | * Check for permissions before trying to copy-up. This is redundant | |
25 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
26 | * without this, copy-up can be triggered by just about anybody. | |
27 | * | |
28 | * We don't initialize inode->size, which just means that | |
29 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
30 | * check for a swapfile (which this won't be anyway). | |
31 | */ | |
31051c85 | 32 | err = setattr_prepare(dentry, attr); |
cf9a6784 MS |
33 | if (err) |
34 | return err; | |
35 | ||
e9be9d5e MS |
36 | err = ovl_want_write(dentry); |
37 | if (err) | |
38 | goto out; | |
39 | ||
acff81ec MS |
40 | err = ovl_copy_up(dentry); |
41 | if (!err) { | |
42 | upperdentry = ovl_dentry_upper(dentry); | |
43 | ||
b99c2d91 MS |
44 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
45 | attr->ia_valid &= ~ATTR_MODE; | |
46 | ||
5955102c | 47 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 48 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 49 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 50 | revert_creds(old_cred); |
b81de061 KK |
51 | if (!err) |
52 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 53 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
54 | } |
55 | ovl_drop_write(dentry); | |
56 | out: | |
57 | return err; | |
58 | } | |
59 | ||
a528d35e DH |
60 | static int ovl_getattr(const struct path *path, struct kstat *stat, |
61 | u32 request_mask, unsigned int flags) | |
e9be9d5e | 62 | { |
a528d35e | 63 | struct dentry *dentry = path->dentry; |
e9be9d5e | 64 | struct path realpath; |
1175b6b8 VG |
65 | const struct cred *old_cred; |
66 | int err; | |
e9be9d5e MS |
67 | |
68 | ovl_path_real(dentry, &realpath); | |
1175b6b8 | 69 | old_cred = ovl_override_creds(dentry->d_sb); |
a528d35e | 70 | err = vfs_getattr(&realpath, stat, request_mask, flags); |
1175b6b8 VG |
71 | revert_creds(old_cred); |
72 | return err; | |
e9be9d5e MS |
73 | } |
74 | ||
75 | int ovl_permission(struct inode *inode, int mask) | |
76 | { | |
e9be9d5e | 77 | bool is_upper; |
39b681f8 | 78 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 79 | const struct cred *old_cred; |
e9be9d5e MS |
80 | int err; |
81 | ||
e9be9d5e | 82 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
83 | if (!realinode) { |
84 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 85 | return -ECHILD; |
e9be9d5e MS |
86 | } |
87 | ||
c0ca3d70 VG |
88 | /* |
89 | * Check overlay inode with the creds of task and underlying inode | |
90 | * with creds of mounter | |
91 | */ | |
92 | err = generic_permission(inode, mask); | |
93 | if (err) | |
94 | return err; | |
95 | ||
96 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 97 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 98 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
99 | /* Make sure mounter can read file for copy up later */ |
100 | mask |= MAY_READ; | |
101 | } | |
9c630ebe | 102 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
103 | revert_creds(old_cred); |
104 | ||
105 | return err; | |
e9be9d5e MS |
106 | } |
107 | ||
6b255391 | 108 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
109 | struct inode *inode, |
110 | struct delayed_call *done) | |
e9be9d5e | 111 | { |
1175b6b8 VG |
112 | const struct cred *old_cred; |
113 | const char *p; | |
e9be9d5e | 114 | |
6b255391 AV |
115 | if (!dentry) |
116 | return ERR_PTR(-ECHILD); | |
117 | ||
1175b6b8 | 118 | old_cred = ovl_override_creds(dentry->d_sb); |
7764235b | 119 | p = vfs_get_link(ovl_dentry_real(dentry), done); |
1175b6b8 VG |
120 | revert_creds(old_cred); |
121 | return p; | |
e9be9d5e MS |
122 | } |
123 | ||
0956254a | 124 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 125 | { |
fe2b7595 AG |
126 | return strncmp(name, OVL_XATTR_PREFIX, |
127 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
128 | } |
129 | ||
0e585ccc AG |
130 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
131 | size_t size, int flags) | |
e9be9d5e MS |
132 | { |
133 | int err; | |
0e585ccc AG |
134 | struct path realpath; |
135 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 136 | const struct cred *old_cred; |
e9be9d5e MS |
137 | |
138 | err = ovl_want_write(dentry); | |
139 | if (err) | |
140 | goto out; | |
141 | ||
0e585ccc AG |
142 | if (!value && !OVL_TYPE_UPPER(type)) { |
143 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
144 | if (err < 0) | |
145 | goto out_drop_write; | |
146 | } | |
147 | ||
e9be9d5e MS |
148 | err = ovl_copy_up(dentry); |
149 | if (err) | |
150 | goto out_drop_write; | |
151 | ||
0e585ccc AG |
152 | if (!OVL_TYPE_UPPER(type)) |
153 | ovl_path_upper(dentry, &realpath); | |
154 | ||
1175b6b8 | 155 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
156 | if (value) |
157 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
158 | else { | |
159 | WARN_ON(flags != XATTR_REPLACE); | |
160 | err = vfs_removexattr(realpath.dentry, name); | |
161 | } | |
1175b6b8 | 162 | revert_creds(old_cred); |
e9be9d5e MS |
163 | |
164 | out_drop_write: | |
165 | ovl_drop_write(dentry); | |
166 | out: | |
167 | return err; | |
168 | } | |
169 | ||
0eb45fc3 AG |
170 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
171 | void *value, size_t size) | |
e9be9d5e | 172 | { |
b581755b | 173 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
174 | ssize_t res; |
175 | const struct cred *old_cred; | |
52148463 | 176 | |
1175b6b8 VG |
177 | old_cred = ovl_override_creds(dentry->d_sb); |
178 | res = vfs_getxattr(realdentry, name, value, size); | |
179 | revert_creds(old_cred); | |
180 | return res; | |
e9be9d5e MS |
181 | } |
182 | ||
183 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
184 | { | |
b581755b | 185 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 186 | ssize_t res; |
7cb35119 MS |
187 | size_t len; |
188 | char *s; | |
1175b6b8 | 189 | const struct cred *old_cred; |
e9be9d5e | 190 | |
1175b6b8 | 191 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 192 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 193 | revert_creds(old_cred); |
e9be9d5e MS |
194 | if (res <= 0 || size == 0) |
195 | return res; | |
196 | ||
e9be9d5e | 197 | /* filter out private xattrs */ |
7cb35119 MS |
198 | for (s = list, len = res; len;) { |
199 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 200 | |
7cb35119 MS |
201 | /* underlying fs providing us with an broken xattr list? */ |
202 | if (WARN_ON(slen > len)) | |
203 | return -EIO; | |
e9be9d5e | 204 | |
7cb35119 | 205 | len -= slen; |
e9be9d5e MS |
206 | if (ovl_is_private_xattr(s)) { |
207 | res -= slen; | |
7cb35119 | 208 | memmove(s, s + slen, len); |
e9be9d5e | 209 | } else { |
7cb35119 | 210 | s += slen; |
e9be9d5e MS |
211 | } |
212 | } | |
213 | ||
214 | return res; | |
215 | } | |
216 | ||
39a25b2b VG |
217 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
218 | { | |
39b681f8 | 219 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
220 | const struct cred *old_cred; |
221 | struct posix_acl *acl; | |
39a25b2b | 222 | |
5201dc44 | 223 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
224 | return NULL; |
225 | ||
1175b6b8 | 226 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 227 | acl = get_acl(realinode, type); |
1175b6b8 VG |
228 | revert_creds(old_cred); |
229 | ||
230 | return acl; | |
39a25b2b VG |
231 | } |
232 | ||
e9be9d5e MS |
233 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
234 | struct dentry *realdentry) | |
235 | { | |
1afaba1e | 236 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
237 | return false; |
238 | ||
239 | if (special_file(realdentry->d_inode->i_mode)) | |
240 | return false; | |
241 | ||
242 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
243 | return false; | |
244 | ||
245 | return true; | |
246 | } | |
247 | ||
2d902671 | 248 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 249 | { |
2d902671 | 250 | int err = 0; |
e9be9d5e MS |
251 | struct path realpath; |
252 | enum ovl_path_type type; | |
e9be9d5e MS |
253 | |
254 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 255 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 256 | err = ovl_want_write(dentry); |
2d902671 | 257 | if (!err) { |
9aba6521 | 258 | err = ovl_copy_up_flags(dentry, file_flags); |
2d902671 MS |
259 | ovl_drop_write(dentry); |
260 | } | |
e9be9d5e MS |
261 | } |
262 | ||
2d902671 | 263 | return err; |
e9be9d5e MS |
264 | } |
265 | ||
d719e8f2 MS |
266 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
267 | { | |
268 | struct dentry *alias; | |
269 | struct path upperpath; | |
270 | ||
271 | if (!(flags & S_ATIME)) | |
272 | return 0; | |
273 | ||
274 | alias = d_find_any_alias(inode); | |
275 | if (!alias) | |
276 | return 0; | |
277 | ||
278 | ovl_path_upper(alias, &upperpath); | |
279 | if (upperpath.dentry) { | |
280 | touch_atime(&upperpath); | |
281 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
282 | } | |
283 | ||
284 | dput(alias); | |
285 | ||
286 | return 0; | |
287 | } | |
288 | ||
e9be9d5e MS |
289 | static const struct inode_operations ovl_file_inode_operations = { |
290 | .setattr = ovl_setattr, | |
291 | .permission = ovl_permission, | |
292 | .getattr = ovl_getattr, | |
e9be9d5e | 293 | .listxattr = ovl_listxattr, |
39a25b2b | 294 | .get_acl = ovl_get_acl, |
d719e8f2 | 295 | .update_time = ovl_update_time, |
e9be9d5e MS |
296 | }; |
297 | ||
298 | static const struct inode_operations ovl_symlink_inode_operations = { | |
299 | .setattr = ovl_setattr, | |
6b255391 | 300 | .get_link = ovl_get_link, |
e9be9d5e | 301 | .getattr = ovl_getattr, |
e9be9d5e | 302 | .listxattr = ovl_listxattr, |
d719e8f2 | 303 | .update_time = ovl_update_time, |
e9be9d5e MS |
304 | }; |
305 | ||
ca4c8a3a | 306 | static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) |
e9be9d5e | 307 | { |
e9be9d5e MS |
308 | inode->i_ino = get_next_ino(); |
309 | inode->i_mode = mode; | |
d719e8f2 | 310 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
311 | #ifdef CONFIG_FS_POSIX_ACL |
312 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
313 | #endif | |
e9be9d5e | 314 | |
ca4c8a3a MS |
315 | switch (mode & S_IFMT) { |
316 | case S_IFREG: | |
317 | inode->i_op = &ovl_file_inode_operations; | |
318 | break; | |
319 | ||
e9be9d5e | 320 | case S_IFDIR: |
e9be9d5e MS |
321 | inode->i_op = &ovl_dir_inode_operations; |
322 | inode->i_fop = &ovl_dir_operations; | |
323 | break; | |
324 | ||
325 | case S_IFLNK: | |
326 | inode->i_op = &ovl_symlink_inode_operations; | |
327 | break; | |
328 | ||
51f7e52d | 329 | default: |
e9be9d5e | 330 | inode->i_op = &ovl_file_inode_operations; |
ca4c8a3a | 331 | init_special_inode(inode, mode, rdev); |
e9be9d5e | 332 | break; |
51f7e52d MS |
333 | } |
334 | } | |
e9be9d5e | 335 | |
ca4c8a3a | 336 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
51f7e52d MS |
337 | { |
338 | struct inode *inode; | |
339 | ||
340 | inode = new_inode(sb); | |
341 | if (inode) | |
ca4c8a3a | 342 | ovl_fill_inode(inode, mode, rdev); |
51f7e52d MS |
343 | |
344 | return inode; | |
345 | } | |
346 | ||
347 | static int ovl_inode_test(struct inode *inode, void *data) | |
348 | { | |
349 | return ovl_inode_real(inode, NULL) == data; | |
350 | } | |
351 | ||
352 | static int ovl_inode_set(struct inode *inode, void *data) | |
353 | { | |
354 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
355 | return 0; | |
356 | } | |
357 | ||
358 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
359 | ||
360 | { | |
361 | struct inode *inode; | |
362 | ||
363 | inode = iget5_locked(sb, (unsigned long) realinode, | |
364 | ovl_inode_test, ovl_inode_set, realinode); | |
365 | if (inode && inode->i_state & I_NEW) { | |
ca4c8a3a | 366 | ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); |
51f7e52d MS |
367 | set_nlink(inode, realinode->i_nlink); |
368 | unlock_new_inode(inode); | |
e9be9d5e MS |
369 | } |
370 | ||
371 | return inode; | |
e9be9d5e | 372 | } |