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; | |
44 | ||
cf9a6784 MS |
45 | /* |
46 | * Check for permissions before trying to copy-up. This is redundant | |
47 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
48 | * without this, copy-up can be triggered by just about anybody. | |
49 | * | |
50 | * We don't initialize inode->size, which just means that | |
51 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
52 | * check for a swapfile (which this won't be anyway). | |
53 | */ | |
54 | err = inode_change_ok(dentry->d_inode, attr); | |
55 | if (err) | |
56 | return err; | |
57 | ||
e9be9d5e MS |
58 | err = ovl_want_write(dentry); |
59 | if (err) | |
60 | goto out; | |
61 | ||
03bea604 MS |
62 | if (attr->ia_valid & ATTR_SIZE) { |
63 | struct inode *realinode = d_inode(ovl_dentry_real(dentry)); | |
64 | ||
65 | err = -ETXTBSY; | |
66 | if (atomic_read(&realinode->i_writecount) < 0) | |
67 | goto out_drop_write; | |
68 | } | |
69 | ||
acff81ec MS |
70 | err = ovl_copy_up(dentry); |
71 | if (!err) { | |
03bea604 MS |
72 | struct inode *winode = NULL; |
73 | ||
acff81ec MS |
74 | upperdentry = ovl_dentry_upper(dentry); |
75 | ||
03bea604 MS |
76 | if (attr->ia_valid & ATTR_SIZE) { |
77 | winode = d_inode(upperdentry); | |
78 | err = get_write_access(winode); | |
79 | if (err) | |
80 | goto out_drop_write; | |
81 | } | |
82 | ||
b99c2d91 MS |
83 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
84 | attr->ia_valid &= ~ATTR_MODE; | |
85 | ||
5955102c | 86 | inode_lock(upperdentry->d_inode); |
e9be9d5e | 87 | err = notify_change(upperdentry, attr, NULL); |
b81de061 KK |
88 | if (!err) |
89 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 90 | inode_unlock(upperdentry->d_inode); |
03bea604 MS |
91 | |
92 | if (winode) | |
93 | put_write_access(winode); | |
e9be9d5e | 94 | } |
03bea604 | 95 | out_drop_write: |
e9be9d5e MS |
96 | ovl_drop_write(dentry); |
97 | out: | |
98 | return err; | |
99 | } | |
100 | ||
101 | static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
102 | struct kstat *stat) | |
103 | { | |
104 | struct path realpath; | |
105 | ||
106 | ovl_path_real(dentry, &realpath); | |
107 | return vfs_getattr(&realpath, stat); | |
108 | } | |
109 | ||
110 | int ovl_permission(struct inode *inode, int mask) | |
111 | { | |
58ed4e70 | 112 | struct ovl_entry *oe = inode->i_private; |
e9be9d5e | 113 | bool is_upper; |
58ed4e70 AG |
114 | struct dentry *realdentry = ovl_entry_real(oe, &is_upper); |
115 | struct inode *realinode; | |
e9be9d5e MS |
116 | int err; |
117 | ||
8d3095f4 MS |
118 | if (ovl_is_default_permissions(inode)) { |
119 | struct kstat stat; | |
120 | struct path realpath = { .dentry = realdentry }; | |
121 | ||
122 | if (mask & MAY_NOT_BLOCK) | |
123 | return -ECHILD; | |
124 | ||
125 | realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper); | |
126 | ||
127 | err = vfs_getattr(&realpath, &stat); | |
128 | if (err) | |
58ed4e70 | 129 | return err; |
8d3095f4 MS |
130 | |
131 | if ((stat.mode ^ inode->i_mode) & S_IFMT) | |
58ed4e70 | 132 | return -ESTALE; |
8d3095f4 MS |
133 | |
134 | inode->i_mode = stat.mode; | |
135 | inode->i_uid = stat.uid; | |
136 | inode->i_gid = stat.gid; | |
137 | ||
58ed4e70 | 138 | return generic_permission(inode, mask); |
8d3095f4 MS |
139 | } |
140 | ||
e9be9d5e | 141 | /* Careful in RCU walk mode */ |
58ed4e70 | 142 | realinode = d_inode_rcu(realdentry); |
e9be9d5e MS |
143 | if (!realinode) { |
144 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
58ed4e70 | 145 | return -ENOENT; |
e9be9d5e MS |
146 | } |
147 | ||
148 | if (mask & MAY_WRITE) { | |
149 | umode_t mode = realinode->i_mode; | |
150 | ||
151 | /* | |
152 | * Writes will always be redirected to upper layer, so | |
153 | * ignore lower layer being read-only. | |
154 | * | |
155 | * If the overlay itself is read-only then proceed | |
156 | * with the permission check, don't return EROFS. | |
157 | * This will only happen if this is the lower layer of | |
158 | * another overlayfs. | |
159 | * | |
160 | * If upper fs becomes read-only after the overlay was | |
161 | * constructed return EROFS to prevent modification of | |
162 | * upper layer. | |
163 | */ | |
e9be9d5e MS |
164 | if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) && |
165 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
58ed4e70 | 166 | return -EROFS; |
e9be9d5e MS |
167 | } |
168 | ||
58ed4e70 | 169 | return __inode_permission(realinode, mask); |
e9be9d5e MS |
170 | } |
171 | ||
6b255391 | 172 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
173 | struct inode *inode, |
174 | struct delayed_call *done) | |
e9be9d5e | 175 | { |
e9be9d5e MS |
176 | struct dentry *realdentry; |
177 | struct inode *realinode; | |
178 | ||
6b255391 AV |
179 | if (!dentry) |
180 | return ERR_PTR(-ECHILD); | |
181 | ||
e9be9d5e MS |
182 | realdentry = ovl_dentry_real(dentry); |
183 | realinode = realdentry->d_inode; | |
184 | ||
6b255391 | 185 | if (WARN_ON(!realinode->i_op->get_link)) |
e9be9d5e MS |
186 | return ERR_PTR(-EPERM); |
187 | ||
fceef393 | 188 | return realinode->i_op->get_link(realdentry, realinode, done); |
e9be9d5e MS |
189 | } |
190 | ||
191 | static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz) | |
192 | { | |
193 | struct path realpath; | |
194 | struct inode *realinode; | |
195 | ||
196 | ovl_path_real(dentry, &realpath); | |
197 | realinode = realpath.dentry->d_inode; | |
198 | ||
199 | if (!realinode->i_op->readlink) | |
200 | return -EINVAL; | |
201 | ||
202 | touch_atime(&realpath); | |
203 | ||
204 | return realinode->i_op->readlink(realpath.dentry, buf, bufsiz); | |
205 | } | |
206 | ||
207 | ||
208 | static bool ovl_is_private_xattr(const char *name) | |
209 | { | |
cead89bb | 210 | return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0; |
e9be9d5e MS |
211 | } |
212 | ||
3767e255 AV |
213 | int ovl_setxattr(struct dentry *dentry, struct inode *inode, |
214 | const char *name, const void *value, | |
215 | size_t size, int flags) | |
e9be9d5e MS |
216 | { |
217 | int err; | |
218 | struct dentry *upperdentry; | |
219 | ||
220 | err = ovl_want_write(dentry); | |
221 | if (err) | |
222 | goto out; | |
223 | ||
224 | err = -EPERM; | |
225 | if (ovl_is_private_xattr(name)) | |
226 | goto out_drop_write; | |
227 | ||
228 | err = ovl_copy_up(dentry); | |
229 | if (err) | |
230 | goto out_drop_write; | |
231 | ||
232 | upperdentry = ovl_dentry_upper(dentry); | |
233 | err = vfs_setxattr(upperdentry, name, value, size, flags); | |
234 | ||
235 | out_drop_write: | |
236 | ovl_drop_write(dentry); | |
237 | out: | |
238 | return err; | |
239 | } | |
240 | ||
ce23e640 AV |
241 | ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode, |
242 | const char *name, void *value, size_t size) | |
e9be9d5e | 243 | { |
b581755b | 244 | struct dentry *realdentry = ovl_dentry_real(dentry); |
52148463 | 245 | |
b581755b | 246 | if (ovl_is_private_xattr(name)) |
e9be9d5e MS |
247 | return -ENODATA; |
248 | ||
b581755b | 249 | return vfs_getxattr(realdentry, name, value, size); |
e9be9d5e MS |
250 | } |
251 | ||
252 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) | |
253 | { | |
b581755b | 254 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e MS |
255 | ssize_t res; |
256 | int off; | |
257 | ||
b581755b | 258 | res = vfs_listxattr(realdentry, list, size); |
e9be9d5e MS |
259 | if (res <= 0 || size == 0) |
260 | return res; | |
261 | ||
e9be9d5e MS |
262 | /* filter out private xattrs */ |
263 | for (off = 0; off < res;) { | |
264 | char *s = list + off; | |
265 | size_t slen = strlen(s) + 1; | |
266 | ||
267 | BUG_ON(off + slen > res); | |
268 | ||
269 | if (ovl_is_private_xattr(s)) { | |
270 | res -= slen; | |
271 | memmove(s, s + slen, res - off); | |
272 | } else { | |
273 | off += slen; | |
274 | } | |
275 | } | |
276 | ||
277 | return res; | |
278 | } | |
279 | ||
280 | int ovl_removexattr(struct dentry *dentry, const char *name) | |
281 | { | |
282 | int err; | |
283 | struct path realpath; | |
52148463 | 284 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); |
e9be9d5e MS |
285 | |
286 | err = ovl_want_write(dentry); | |
287 | if (err) | |
288 | goto out; | |
289 | ||
52148463 | 290 | err = -ENODATA; |
b581755b | 291 | if (ovl_is_private_xattr(name)) |
e9be9d5e MS |
292 | goto out_drop_write; |
293 | ||
1afaba1e | 294 | if (!OVL_TYPE_UPPER(type)) { |
e9be9d5e MS |
295 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); |
296 | if (err < 0) | |
297 | goto out_drop_write; | |
298 | ||
299 | err = ovl_copy_up(dentry); | |
300 | if (err) | |
301 | goto out_drop_write; | |
302 | ||
303 | ovl_path_upper(dentry, &realpath); | |
304 | } | |
305 | ||
306 | err = vfs_removexattr(realpath.dentry, name); | |
307 | out_drop_write: | |
308 | ovl_drop_write(dentry); | |
309 | out: | |
310 | return err; | |
311 | } | |
312 | ||
313 | static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, | |
314 | struct dentry *realdentry) | |
315 | { | |
1afaba1e | 316 | if (OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
317 | return false; |
318 | ||
319 | if (special_file(realdentry->d_inode->i_mode)) | |
320 | return false; | |
321 | ||
322 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
323 | return false; | |
324 | ||
325 | return true; | |
326 | } | |
327 | ||
2d902671 | 328 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 329 | { |
2d902671 | 330 | int err = 0; |
e9be9d5e MS |
331 | struct path realpath; |
332 | enum ovl_path_type type; | |
e9be9d5e MS |
333 | |
334 | type = ovl_path_real(dentry, &realpath); | |
4bacc9c9 | 335 | if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { |
e9be9d5e | 336 | err = ovl_want_write(dentry); |
2d902671 MS |
337 | if (!err) { |
338 | if (file_flags & O_TRUNC) | |
339 | err = ovl_copy_up_truncate(dentry); | |
340 | else | |
341 | err = ovl_copy_up(dentry); | |
342 | ovl_drop_write(dentry); | |
343 | } | |
e9be9d5e MS |
344 | } |
345 | ||
2d902671 | 346 | return err; |
e9be9d5e MS |
347 | } |
348 | ||
349 | static const struct inode_operations ovl_file_inode_operations = { | |
350 | .setattr = ovl_setattr, | |
351 | .permission = ovl_permission, | |
352 | .getattr = ovl_getattr, | |
353 | .setxattr = ovl_setxattr, | |
354 | .getxattr = ovl_getxattr, | |
355 | .listxattr = ovl_listxattr, | |
356 | .removexattr = ovl_removexattr, | |
e9be9d5e MS |
357 | }; |
358 | ||
359 | static const struct inode_operations ovl_symlink_inode_operations = { | |
360 | .setattr = ovl_setattr, | |
6b255391 | 361 | .get_link = ovl_get_link, |
e9be9d5e MS |
362 | .readlink = ovl_readlink, |
363 | .getattr = ovl_getattr, | |
364 | .setxattr = ovl_setxattr, | |
365 | .getxattr = ovl_getxattr, | |
366 | .listxattr = ovl_listxattr, | |
367 | .removexattr = ovl_removexattr, | |
368 | }; | |
369 | ||
370 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, | |
371 | struct ovl_entry *oe) | |
372 | { | |
373 | struct inode *inode; | |
374 | ||
375 | inode = new_inode(sb); | |
376 | if (!inode) | |
377 | return NULL; | |
378 | ||
e9be9d5e MS |
379 | inode->i_ino = get_next_ino(); |
380 | inode->i_mode = mode; | |
381 | inode->i_flags |= S_NOATIME | S_NOCMTIME; | |
58ed4e70 | 382 | inode->i_private = oe; |
e9be9d5e | 383 | |
07a2daab | 384 | mode &= S_IFMT; |
e9be9d5e MS |
385 | switch (mode) { |
386 | case S_IFDIR: | |
e9be9d5e MS |
387 | inode->i_op = &ovl_dir_inode_operations; |
388 | inode->i_fop = &ovl_dir_operations; | |
389 | break; | |
390 | ||
391 | case S_IFLNK: | |
392 | inode->i_op = &ovl_symlink_inode_operations; | |
393 | break; | |
394 | ||
395 | case S_IFREG: | |
396 | case S_IFSOCK: | |
397 | case S_IFBLK: | |
398 | case S_IFCHR: | |
399 | case S_IFIFO: | |
400 | inode->i_op = &ovl_file_inode_operations; | |
401 | break; | |
402 | ||
403 | default: | |
404 | WARN(1, "illegal file type: %i\n", mode); | |
405 | iput(inode); | |
406 | inode = NULL; | |
407 | } | |
408 | ||
409 | return inode; | |
e9be9d5e | 410 | } |