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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 | ||
e9be9d5e MS |
16 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) |
17 | { | |
18 | int err; | |
19 | struct dentry *upperdentry; | |
1175b6b8 | 20 | const struct cred *old_cred; |
e9be9d5e | 21 | |
cf9a6784 MS |
22 | /* |
23 | * Check for permissions before trying to copy-up. This is redundant | |
24 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
25 | * without this, copy-up can be triggered by just about anybody. | |
26 | * | |
27 | * We don't initialize inode->size, which just means that | |
28 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
29 | * check for a swapfile (which this won't be anyway). | |
30 | */ | |
31051c85 | 31 | err = setattr_prepare(dentry, attr); |
cf9a6784 MS |
32 | if (err) |
33 | return err; | |
34 | ||
e9be9d5e MS |
35 | err = ovl_want_write(dentry); |
36 | if (err) | |
37 | goto out; | |
38 | ||
acff81ec MS |
39 | err = ovl_copy_up(dentry); |
40 | if (!err) { | |
41 | upperdentry = ovl_dentry_upper(dentry); | |
42 | ||
b99c2d91 MS |
43 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
44 | attr->ia_valid &= ~ATTR_MODE; | |
45 | ||
5955102c | 46 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 47 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 48 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 49 | revert_creds(old_cred); |
b81de061 KK |
50 | if (!err) |
51 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 52 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
53 | } |
54 | ovl_drop_write(dentry); | |
55 | out: | |
56 | return err; | |
57 | } | |
58 | ||
59 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
60 | struct kstat *stat) | |
61 | { | |
62 | struct path realpath; | |
1175b6b8 VG |
63 | const struct cred *old_cred; |
64 | int err; | |
e9be9d5e MS |
65 | |
66 | ovl_path_real(dentry, &realpath); | |
1175b6b8 VG |
67 | old_cred = ovl_override_creds(dentry->d_sb); |
68 | err = vfs_getattr(&realpath, stat); | |
69 | revert_creds(old_cred); | |
70 | return err; | |
e9be9d5e MS |
71 | } |
72 | ||
73 | int ovl_permission(struct inode *inode, int mask) | |
74 | { | |
e9be9d5e | 75 | bool is_upper; |
39b681f8 | 76 | struct inode *realinode = ovl_inode_real(inode, &is_upper); |
c0ca3d70 | 77 | const struct cred *old_cred; |
e9be9d5e MS |
78 | int err; |
79 | ||
e9be9d5e | 80 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
81 | if (!realinode) { |
82 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 83 | return -ECHILD; |
e9be9d5e MS |
84 | } |
85 | ||
c0ca3d70 VG |
86 | /* |
87 | * Check overlay inode with the creds of task and underlying inode | |
88 | * with creds of mounter | |
89 | */ | |
90 | err = generic_permission(inode, mask); | |
91 | if (err) | |
92 | return err; | |
93 | ||
94 | old_cred = ovl_override_creds(inode->i_sb); | |
500cac3c | 95 | if (!is_upper && !special_file(realinode->i_mode) && mask & MAY_WRITE) { |
754f8cb7 | 96 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
97 | /* Make sure mounter can read file for copy up later */ |
98 | mask |= MAY_READ; | |
99 | } | |
9c630ebe | 100 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
101 | revert_creds(old_cred); |
102 | ||
103 | return err; | |
e9be9d5e MS |
104 | } |
105 | ||
6b255391 | 106 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
107 | struct inode *inode, |
108 | struct delayed_call *done) | |
e9be9d5e | 109 | { |
1175b6b8 VG |
110 | const struct cred *old_cred; |
111 | const char *p; | |
e9be9d5e | 112 | |
6b255391 AV |
113 | if (!dentry) |
114 | return ERR_PTR(-ECHILD); | |
115 | ||
1175b6b8 | 116 | old_cred = ovl_override_creds(dentry->d_sb); |
7764235b | 117 | p = vfs_get_link(ovl_dentry_real(dentry), done); |
1175b6b8 VG |
118 | revert_creds(old_cred); |
119 | return p; | |
e9be9d5e MS |
120 | } |
121 | ||
0956254a | 122 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 123 | { |
fe2b7595 AG |
124 | return strncmp(name, OVL_XATTR_PREFIX, |
125 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
126 | } |
127 | ||
0e585ccc AG |
128 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
129 | size_t size, int flags) | |
e9be9d5e MS |
130 | { |
131 | int err; | |
0e585ccc AG |
132 | struct path realpath; |
133 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 134 | const struct cred *old_cred; |
e9be9d5e MS |
135 | |
136 | err = ovl_want_write(dentry); | |
137 | if (err) | |
138 | goto out; | |
139 | ||
0e585ccc AG |
140 | if (!value && !OVL_TYPE_UPPER(type)) { |
141 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
142 | if (err < 0) | |
143 | goto out_drop_write; | |
144 | } | |
145 | ||
e9be9d5e MS |
146 | err = ovl_copy_up(dentry); |
147 | if (err) | |
148 | goto out_drop_write; | |
149 | ||
0e585ccc AG |
150 | if (!OVL_TYPE_UPPER(type)) |
151 | ovl_path_upper(dentry, &realpath); | |
152 | ||
1175b6b8 | 153 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
154 | if (value) |
155 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
156 | else { | |
157 | WARN_ON(flags != XATTR_REPLACE); | |
158 | err = vfs_removexattr(realpath.dentry, name); | |
159 | } | |
1175b6b8 | 160 | revert_creds(old_cred); |
e9be9d5e MS |
161 | |
162 | out_drop_write: | |
163 | ovl_drop_write(dentry); | |
164 | out: | |
165 | return err; | |
166 | } | |
167 | ||
0eb45fc3 AG |
168 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
169 | void *value, size_t size) | |
e9be9d5e | 170 | { |
b581755b | 171 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
172 | ssize_t res; |
173 | const struct cred *old_cred; | |
52148463 | 174 | |
1175b6b8 VG |
175 | old_cred = ovl_override_creds(dentry->d_sb); |
176 | res = vfs_getxattr(realdentry, name, value, size); | |
177 | revert_creds(old_cred); | |
178 | return res; | |
e9be9d5e MS |
179 | } |
180 | ||
181 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
182 | { | |
b581755b | 183 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 184 | ssize_t res; |
7cb35119 MS |
185 | size_t len; |
186 | char *s; | |
1175b6b8 | 187 | const struct cred *old_cred; |
e9be9d5e | 188 | |
1175b6b8 | 189 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 190 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 191 | revert_creds(old_cred); |
e9be9d5e MS |
192 | if (res <= 0 || size == 0) |
193 | return res; | |
194 | ||
e9be9d5e | 195 | /* filter out private xattrs */ |
7cb35119 MS |
196 | for (s = list, len = res; len;) { |
197 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 198 | |
7cb35119 MS |
199 | /* underlying fs providing us with an broken xattr list? */ |
200 | if (WARN_ON(slen > len)) | |
201 | return -EIO; | |
e9be9d5e | 202 | |
7cb35119 | 203 | len -= slen; |
e9be9d5e MS |
204 | if (ovl_is_private_xattr(s)) { |
205 | res -= slen; | |
7cb35119 | 206 | memmove(s, s + slen, len); |
e9be9d5e | 207 | } else { |
7cb35119 | 208 | s += slen; |
e9be9d5e MS |
209 | } |
210 | } | |
211 | ||
212 | return res; | |
213 | } | |
214 | ||
39a25b2b VG |
215 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
216 | { | |
39b681f8 | 217 | struct inode *realinode = ovl_inode_real(inode, NULL); |
1175b6b8 VG |
218 | const struct cred *old_cred; |
219 | struct posix_acl *acl; | |
39a25b2b | 220 | |
5201dc44 | 221 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
222 | return NULL; |
223 | ||
1175b6b8 | 224 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 225 | acl = get_acl(realinode, type); |
1175b6b8 VG |
226 | revert_creds(old_cred); |
227 | ||
228 | return acl; | |
39a25b2b VG |
229 | } |
230 | ||
e9be9d5e MS |
231 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, |
232 | struct dentry *realdentry) | |
233 | { | |
1afaba1e | 234 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
235 | return false; |
236 | ||
237 | if (special_file(realdentry->d_inode->i_mode)) | |
238 | return false; | |
239 | ||
240 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
241 | return false; | |
242 | ||
243 | return true; | |
244 | } | |
245 | ||
2d902671 | 246 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 247 | { |
2d902671 | 248 | int err = 0; |
e9be9d5e MS |
249 | struct path realpath; |
250 | enum ovl_path_type type; | |
e9be9d5e MS |
251 | |
252 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 253 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 254 | err = ovl_want_write(dentry); |
2d902671 | 255 | if (!err) { |
9aba6521 | 256 | err = ovl_copy_up_flags(dentry, file_flags); |
2d902671 MS |
257 | ovl_drop_write(dentry); |
258 | } | |
e9be9d5e MS |
259 | } |
260 | ||
2d902671 | 261 | return err; |
e9be9d5e MS |
262 | } |
263 | ||
d719e8f2 MS |
264 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
265 | { | |
266 | struct dentry *alias; | |
267 | struct path upperpath; | |
268 | ||
269 | if (!(flags & S_ATIME)) | |
270 | return 0; | |
271 | ||
272 | alias = d_find_any_alias(inode); | |
273 | if (!alias) | |
274 | return 0; | |
275 | ||
276 | ovl_path_upper(alias, &upperpath); | |
277 | if (upperpath.dentry) { | |
278 | touch_atime(&upperpath); | |
279 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
280 | } | |
281 | ||
282 | dput(alias); | |
283 | ||
284 | return 0; | |
285 | } | |
286 | ||
e9be9d5e MS |
287 | static const struct inode_operations ovl_file_inode_operations = { |
288 | .setattr = ovl_setattr, | |
289 | .permission = ovl_permission, | |
290 | .getattr = ovl_getattr, | |
e9be9d5e | 291 | .listxattr = ovl_listxattr, |
39a25b2b | 292 | .get_acl = ovl_get_acl, |
d719e8f2 | 293 | .update_time = ovl_update_time, |
e9be9d5e MS |
294 | }; |
295 | ||
296 | static const struct inode_operations ovl_symlink_inode_operations = { | |
297 | .setattr = ovl_setattr, | |
6b255391 | 298 | .get_link = ovl_get_link, |
78a3fa4f | 299 | .readlink = generic_readlink, |
e9be9d5e | 300 | .getattr = ovl_getattr, |
e9be9d5e | 301 | .listxattr = ovl_listxattr, |
d719e8f2 | 302 | .update_time = ovl_update_time, |
e9be9d5e MS |
303 | }; |
304 | ||
ca4c8a3a | 305 | static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) |
e9be9d5e | 306 | { |
e9be9d5e MS |
307 | inode->i_ino = get_next_ino(); |
308 | inode->i_mode = mode; | |
d719e8f2 | 309 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
310 | #ifdef CONFIG_FS_POSIX_ACL |
311 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
312 | #endif | |
e9be9d5e | 313 | |
ca4c8a3a MS |
314 | switch (mode & S_IFMT) { |
315 | case S_IFREG: | |
316 | inode->i_op = &ovl_file_inode_operations; | |
317 | break; | |
318 | ||
e9be9d5e | 319 | case S_IFDIR: |
e9be9d5e MS |
320 | inode->i_op = &ovl_dir_inode_operations; |
321 | inode->i_fop = &ovl_dir_operations; | |
322 | break; | |
323 | ||
324 | case S_IFLNK: | |
325 | inode->i_op = &ovl_symlink_inode_operations; | |
326 | break; | |
327 | ||
51f7e52d | 328 | default: |
e9be9d5e | 329 | inode->i_op = &ovl_file_inode_operations; |
ca4c8a3a | 330 | init_special_inode(inode, mode, rdev); |
e9be9d5e | 331 | break; |
51f7e52d MS |
332 | } |
333 | } | |
e9be9d5e | 334 | |
ca4c8a3a | 335 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
51f7e52d MS |
336 | { |
337 | struct inode *inode; | |
338 | ||
339 | inode = new_inode(sb); | |
340 | if (inode) | |
ca4c8a3a | 341 | ovl_fill_inode(inode, mode, rdev); |
51f7e52d MS |
342 | |
343 | return inode; | |
344 | } | |
345 | ||
346 | static int ovl_inode_test(struct inode *inode, void *data) | |
347 | { | |
348 | return ovl_inode_real(inode, NULL) == data; | |
349 | } | |
350 | ||
351 | static int ovl_inode_set(struct inode *inode, void *data) | |
352 | { | |
353 | inode->i_private = (void *) (((unsigned long) data) | OVL_ISUPPER_MASK); | |
354 | return 0; | |
355 | } | |
356 | ||
357 | struct inode *ovl_get_inode(struct super_block *sb, struct inode *realinode) | |
358 | ||
359 | { | |
360 | struct inode *inode; | |
361 | ||
362 | inode = iget5_locked(sb, (unsigned long) realinode, | |
363 | ovl_inode_test, ovl_inode_set, realinode); | |
364 | if (inode && inode->i_state & I_NEW) { | |
ca4c8a3a | 365 | ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); |
51f7e52d MS |
366 | set_nlink(inode, realinode->i_nlink); |
367 | unlock_new_inode(inode); | |
e9be9d5e MS |
368 | } |
369 | ||
370 | return inode; | |
e9be9d5e | 371 | } |