3 * Copyright (C) 2011 Novell Inc.
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.
11 #include <linux/slab.h>
12 #include <linux/xattr.h>
13 #include "overlayfs.h"
15 static int ovl_copy_up_last(struct dentry *dentry, struct iattr *attr,
19 struct dentry *parent;
21 struct path lowerpath;
23 parent = dget_parent(dentry);
24 err = ovl_copy_up(parent);
28 ovl_path_lower(dentry, &lowerpath);
29 err = vfs_getattr(&lowerpath, &stat);
36 err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat, attr);
43 int ovl_setattr(struct dentry *dentry, struct iattr *attr)
46 struct dentry *upperdentry;
48 err = ovl_want_write(dentry);
52 upperdentry = ovl_dentry_upper(dentry);
54 mutex_lock(&upperdentry->d_inode->i_mutex);
55 err = notify_change(upperdentry, attr, NULL);
56 mutex_unlock(&upperdentry->d_inode->i_mutex);
58 err = ovl_copy_up_last(dentry, attr, false);
60 ovl_drop_write(dentry);
65 static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
70 ovl_path_real(dentry, &realpath);
71 return vfs_getattr(&realpath, stat);
74 int ovl_permission(struct inode *inode, int mask)
77 struct dentry *alias = NULL;
78 struct inode *realinode;
79 struct dentry *realdentry;
83 if (S_ISDIR(inode->i_mode)) {
84 oe = inode->i_private;
85 } else if (mask & MAY_NOT_BLOCK) {
89 * For non-directories find an alias and get the info
92 alias = d_find_any_alias(inode);
99 realdentry = ovl_entry_real(oe, &is_upper);
101 /* Careful in RCU walk mode */
102 realinode = ACCESS_ONCE(realdentry->d_inode);
104 WARN_ON(!(mask & MAY_NOT_BLOCK));
109 if (mask & MAY_WRITE) {
110 umode_t mode = realinode->i_mode;
113 * Writes will always be redirected to upper layer, so
114 * ignore lower layer being read-only.
116 * If the overlay itself is read-only then proceed
117 * with the permission check, don't return EROFS.
118 * This will only happen if this is the lower layer of
121 * If upper fs becomes read-only after the overlay was
122 * constructed return EROFS to prevent modification of
126 if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
127 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
131 err = __inode_permission(realinode, mask);
138 struct ovl_link_data {
139 struct dentry *realdentry;
143 static const char *ovl_follow_link(struct dentry *dentry, void **cookie)
145 struct dentry *realdentry;
146 struct inode *realinode;
147 struct ovl_link_data *data = NULL;
150 realdentry = ovl_dentry_real(dentry);
151 realinode = realdentry->d_inode;
153 if (WARN_ON(!realinode->i_op->follow_link))
154 return ERR_PTR(-EPERM);
156 if (realinode->i_op->put_link) {
157 data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
159 return ERR_PTR(-ENOMEM);
160 data->realdentry = realdentry;
163 ret = realinode->i_op->follow_link(realdentry, cookie);
164 if (IS_ERR_OR_NULL(ret)) {
170 data->cookie = *cookie;
177 static void ovl_put_link(struct inode *unused, void *c)
179 struct inode *realinode;
180 struct ovl_link_data *data = c;
185 realinode = data->realdentry->d_inode;
186 realinode->i_op->put_link(realinode, data->cookie);
190 static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
192 struct path realpath;
193 struct inode *realinode;
195 ovl_path_real(dentry, &realpath);
196 realinode = realpath.dentry->d_inode;
198 if (!realinode->i_op->readlink)
201 touch_atime(&realpath);
203 return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
207 static bool ovl_is_private_xattr(const char *name)
209 return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0;
212 int ovl_setxattr(struct dentry *dentry, const char *name,
213 const void *value, size_t size, int flags)
216 struct dentry *upperdentry;
218 err = ovl_want_write(dentry);
223 if (ovl_is_private_xattr(name))
226 err = ovl_copy_up(dentry);
230 upperdentry = ovl_dentry_upper(dentry);
231 err = vfs_setxattr(upperdentry, name, value, size, flags);
234 ovl_drop_write(dentry);
239 static bool ovl_need_xattr_filter(struct dentry *dentry,
240 enum ovl_path_type type)
242 if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER)
243 return S_ISDIR(dentry->d_inode->i_mode);
248 ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
249 void *value, size_t size)
251 struct path realpath;
252 enum ovl_path_type type = ovl_path_real(dentry, &realpath);
254 if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
257 return vfs_getxattr(realpath.dentry, name, value, size);
260 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
262 struct path realpath;
263 enum ovl_path_type type = ovl_path_real(dentry, &realpath);
267 res = vfs_listxattr(realpath.dentry, list, size);
268 if (res <= 0 || size == 0)
271 if (!ovl_need_xattr_filter(dentry, type))
274 /* filter out private xattrs */
275 for (off = 0; off < res;) {
276 char *s = list + off;
277 size_t slen = strlen(s) + 1;
279 BUG_ON(off + slen > res);
281 if (ovl_is_private_xattr(s)) {
283 memmove(s, s + slen, res - off);
292 int ovl_removexattr(struct dentry *dentry, const char *name)
295 struct path realpath;
296 enum ovl_path_type type = ovl_path_real(dentry, &realpath);
298 err = ovl_want_write(dentry);
303 if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
306 if (!OVL_TYPE_UPPER(type)) {
307 err = vfs_getxattr(realpath.dentry, name, NULL, 0);
311 err = ovl_copy_up(dentry);
315 ovl_path_upper(dentry, &realpath);
318 err = vfs_removexattr(realpath.dentry, name);
320 ovl_drop_write(dentry);
325 static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
326 struct dentry *realdentry)
328 if (OVL_TYPE_UPPER(type))
331 if (special_file(realdentry->d_inode->i_mode))
334 if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
340 struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
343 struct path realpath;
344 enum ovl_path_type type;
346 if (d_is_dir(dentry))
347 return d_backing_inode(dentry);
349 type = ovl_path_real(dentry, &realpath);
350 if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
351 err = ovl_want_write(dentry);
355 if (file_flags & O_TRUNC)
356 err = ovl_copy_up_last(dentry, NULL, true);
358 err = ovl_copy_up(dentry);
359 ovl_drop_write(dentry);
363 ovl_path_upper(dentry, &realpath);
366 if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
367 return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
369 return d_backing_inode(realpath.dentry);
372 static const struct inode_operations ovl_file_inode_operations = {
373 .setattr = ovl_setattr,
374 .permission = ovl_permission,
375 .getattr = ovl_getattr,
376 .setxattr = ovl_setxattr,
377 .getxattr = ovl_getxattr,
378 .listxattr = ovl_listxattr,
379 .removexattr = ovl_removexattr,
382 static const struct inode_operations ovl_symlink_inode_operations = {
383 .setattr = ovl_setattr,
384 .follow_link = ovl_follow_link,
385 .put_link = ovl_put_link,
386 .readlink = ovl_readlink,
387 .getattr = ovl_getattr,
388 .setxattr = ovl_setxattr,
389 .getxattr = ovl_getxattr,
390 .listxattr = ovl_listxattr,
391 .removexattr = ovl_removexattr,
394 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
395 struct ovl_entry *oe)
399 inode = new_inode(sb);
405 inode->i_ino = get_next_ino();
406 inode->i_mode = mode;
407 inode->i_flags |= S_NOATIME | S_NOCMTIME;
411 inode->i_private = oe;
412 inode->i_op = &ovl_dir_inode_operations;
413 inode->i_fop = &ovl_dir_operations;
417 inode->i_op = &ovl_symlink_inode_operations;
425 inode->i_op = &ovl_file_inode_operations;
429 WARN(1, "illegal file type: %i\n", mode);