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.
10 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/file.h>
14 #include <linux/splice.h>
15 #include <linux/xattr.h>
16 #include <linux/security.h>
17 #include <linux/uaccess.h>
18 #include <linux/sched/signal.h>
19 #include <linux/cred.h>
20 #include <linux/namei.h>
21 #include <linux/fdtable.h>
22 #include <linux/ratelimit.h>
23 #include "overlayfs.h"
25 #define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
27 static bool __read_mostly ovl_check_copy_up
;
28 module_param_named(check_copy_up
, ovl_check_copy_up
, bool,
30 MODULE_PARM_DESC(ovl_check_copy_up
,
31 "Warn on copy-up when causing process also has a R/O fd open");
33 static int ovl_check_fd(const void *data
, struct file
*f
, unsigned int fd
)
35 const struct dentry
*dentry
= data
;
37 if (file_inode(f
) == d_inode(dentry
))
38 pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
39 f
, fd
, current
->pid
, current
->comm
);
44 * Check the fds open by this process and warn if something like the following
45 * scenario is about to occur:
47 * fd1 = open("foo", O_RDONLY);
48 * fd2 = open("foo", O_RDWR);
50 static void ovl_do_check_copy_up(struct dentry
*dentry
)
52 if (ovl_check_copy_up
)
53 iterate_fd(current
->files
, 0, ovl_check_fd
, dentry
);
56 int ovl_copy_xattr(struct dentry
*old
, struct dentry
*new)
58 ssize_t list_size
, size
, value_size
= 0;
59 char *buf
, *name
, *value
= NULL
;
60 int uninitialized_var(error
);
63 if (!(old
->d_inode
->i_opflags
& IOP_XATTR
) ||
64 !(new->d_inode
->i_opflags
& IOP_XATTR
))
67 list_size
= vfs_listxattr(old
, NULL
, 0);
69 if (list_size
== -EOPNOTSUPP
)
74 buf
= kzalloc(list_size
, GFP_KERNEL
);
78 list_size
= vfs_listxattr(old
, buf
, list_size
);
84 for (name
= buf
; list_size
; name
+= slen
) {
85 slen
= strnlen(name
, list_size
) + 1;
87 /* underlying fs providing us with an broken xattr list? */
88 if (WARN_ON(slen
> list_size
)) {
94 if (ovl_is_private_xattr(name
))
97 size
= vfs_getxattr(old
, name
, value
, value_size
);
99 size
= vfs_getxattr(old
, name
, NULL
, 0);
106 if (size
> value_size
) {
109 new = krealloc(value
, size
, GFP_KERNEL
);
119 error
= security_inode_copy_up_xattr(name
);
120 if (error
< 0 && error
!= -EOPNOTSUPP
)
124 continue; /* Discard */
126 error
= vfs_setxattr(new, name
, value
, size
, 0);
136 static int ovl_copy_up_data(struct path
*old
, struct path
*new, loff_t len
)
138 struct file
*old_file
;
139 struct file
*new_file
;
147 old_file
= ovl_path_open(old
, O_LARGEFILE
| O_RDONLY
);
148 if (IS_ERR(old_file
))
149 return PTR_ERR(old_file
);
151 new_file
= ovl_path_open(new, O_LARGEFILE
| O_WRONLY
);
152 if (IS_ERR(new_file
)) {
153 error
= PTR_ERR(new_file
);
157 /* Try to use clone_file_range to clone up within the same fs */
158 error
= vfs_clone_file_range(old_file
, 0, new_file
, 0, len
);
161 /* Couldn't clone, so now we try to copy the data */
164 /* FIXME: copy up sparse files efficiently */
166 size_t this_len
= OVL_COPY_UP_CHUNK_SIZE
;
172 if (signal_pending_state(TASK_KILLABLE
, current
)) {
177 bytes
= do_splice_direct(old_file
, &old_pos
,
179 this_len
, SPLICE_F_MOVE
);
184 WARN_ON(old_pos
!= new_pos
);
190 error
= vfs_fsync(new_file
, 0);
197 static int ovl_set_timestamps(struct dentry
*upperdentry
, struct kstat
*stat
)
199 struct iattr attr
= {
201 ATTR_ATIME
| ATTR_MTIME
| ATTR_ATIME_SET
| ATTR_MTIME_SET
,
202 .ia_atime
= stat
->atime
,
203 .ia_mtime
= stat
->mtime
,
206 return notify_change(upperdentry
, &attr
, NULL
);
209 int ovl_set_attr(struct dentry
*upperdentry
, struct kstat
*stat
)
213 if (!S_ISLNK(stat
->mode
)) {
214 struct iattr attr
= {
215 .ia_valid
= ATTR_MODE
,
216 .ia_mode
= stat
->mode
,
218 err
= notify_change(upperdentry
, &attr
, NULL
);
221 struct iattr attr
= {
222 .ia_valid
= ATTR_UID
| ATTR_GID
,
226 err
= notify_change(upperdentry
, &attr
, NULL
);
229 ovl_set_timestamps(upperdentry
, stat
);
234 static int ovl_copy_up_locked(struct dentry
*workdir
, struct dentry
*upperdir
,
235 struct dentry
*dentry
, struct path
*lowerpath
,
236 struct kstat
*stat
, const char *link
)
238 struct inode
*wdir
= workdir
->d_inode
;
239 struct inode
*udir
= upperdir
->d_inode
;
240 struct dentry
*newdentry
= NULL
;
241 struct dentry
*upper
= NULL
;
243 const struct cred
*old_creds
= NULL
;
244 struct cred
*new_creds
= NULL
;
245 struct cattr cattr
= {
246 /* Can't properly set mode on creation because of the umask */
247 .mode
= stat
->mode
& S_IFMT
,
252 newdentry
= ovl_lookup_temp(workdir
, dentry
);
253 err
= PTR_ERR(newdentry
);
254 if (IS_ERR(newdentry
))
257 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
259 err
= PTR_ERR(upper
);
263 err
= security_inode_copy_up(dentry
, &new_creds
);
268 old_creds
= override_creds(new_creds
);
270 err
= ovl_create_real(wdir
, newdentry
, &cattr
, NULL
, true);
273 revert_creds(old_creds
);
280 if (S_ISREG(stat
->mode
)) {
281 struct path upperpath
;
283 ovl_path_upper(dentry
, &upperpath
);
284 BUG_ON(upperpath
.dentry
!= NULL
);
285 upperpath
.dentry
= newdentry
;
287 err
= ovl_copy_up_data(lowerpath
, &upperpath
, stat
->size
);
292 err
= ovl_copy_xattr(lowerpath
->dentry
, newdentry
);
296 inode_lock(newdentry
->d_inode
);
297 err
= ovl_set_attr(newdentry
, stat
);
298 inode_unlock(newdentry
->d_inode
);
302 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
, 0);
306 ovl_dentry_update(dentry
, newdentry
);
307 ovl_inode_update(d_inode(dentry
), d_inode(newdentry
));
317 ovl_cleanup(wdir
, newdentry
);
322 * Copy up a single dentry
324 * All renames start with copy up of source if necessary. The actual
325 * rename will only proceed once the copy up was successful. Copy up uses
326 * upper parent i_mutex for exclusion. Since rename can change d_parent it
327 * is possible that the copy up will lock the old parent. At that point
328 * the file will have already been copied up anyway.
330 static int ovl_copy_up_one(struct dentry
*parent
, struct dentry
*dentry
,
331 struct path
*lowerpath
, struct kstat
*stat
)
333 DEFINE_DELAYED_CALL(done
);
334 struct dentry
*workdir
= ovl_workdir(dentry
);
337 struct path parentpath
;
338 struct dentry
*lowerdentry
= lowerpath
->dentry
;
339 struct dentry
*upperdir
;
340 const char *link
= NULL
;
342 if (WARN_ON(!workdir
))
345 ovl_do_check_copy_up(lowerdentry
);
347 ovl_path_upper(parent
, &parentpath
);
348 upperdir
= parentpath
.dentry
;
350 err
= vfs_getattr(&parentpath
, &pstat
);
354 if (S_ISLNK(stat
->mode
)) {
355 link
= vfs_get_link(lowerdentry
, &done
);
357 return PTR_ERR(link
);
361 if (lock_rename(workdir
, upperdir
) != NULL
) {
362 pr_err("overlayfs: failed to lock workdir+upperdir\n");
365 if (ovl_dentry_upper(dentry
)) {
366 /* Raced with another copy-up? Nothing to do, then... */
371 err
= ovl_copy_up_locked(workdir
, upperdir
, dentry
, lowerpath
,
374 /* Restore timestamps on parent (best effort) */
375 ovl_set_timestamps(upperdir
, &pstat
);
378 unlock_rename(workdir
, upperdir
);
379 do_delayed_call(&done
);
384 int ovl_copy_up_flags(struct dentry
*dentry
, int flags
)
387 const struct cred
*old_cred
= ovl_override_creds(dentry
->d_sb
);
391 struct dentry
*parent
;
392 struct path lowerpath
;
394 enum ovl_path_type type
= ovl_path_type(dentry
);
396 if (OVL_TYPE_UPPER(type
))
400 /* find the topmost dentry not yet copied up */
402 parent
= dget_parent(next
);
404 type
= ovl_path_type(parent
);
405 if (OVL_TYPE_UPPER(type
))
412 ovl_path_lower(next
, &lowerpath
);
413 err
= vfs_getattr(&lowerpath
, &stat
);
414 /* maybe truncate regular file. this has no effect on dirs */
418 err
= ovl_copy_up_one(parent
, next
, &lowerpath
, &stat
);
423 revert_creds(old_cred
);
428 int ovl_copy_up(struct dentry
*dentry
)
430 return ovl_copy_up_flags(dentry
, 0);