2 * Contains the CIFS DFS referral mounting routines used for handling
3 * traversal via DFS junction point
5 * Copyright (c) 2007 Igor Mammedov
6 * Copyright (C) International Business Machines Corp., 2008
7 * Author(s): Igor Mammedov (niallain@gmail.com)
8 * Steve French (sfrench@us.ibm.com)
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
15 #include <linux/dcache.h>
16 #include <linux/mount.h>
17 #include <linux/namei.h>
18 #include <linux/slab.h>
19 #include <linux/vfs.h>
21 #include <linux/inet.h>
23 #include "cifsproto.h"
25 #include "dns_resolve.h"
26 #include "cifs_debug.h"
27 #include "cifs_unicode.h"
28 #include "dfs_cache.h"
30 static LIST_HEAD(cifs_dfs_automount_list
);
32 static void cifs_dfs_expire_automounts(struct work_struct
*work
);
33 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task
,
34 cifs_dfs_expire_automounts
);
35 static int cifs_dfs_mountpoint_expiry_timeout
= 500 * HZ
;
37 static void cifs_dfs_expire_automounts(struct work_struct
*work
)
39 struct list_head
*list
= &cifs_dfs_automount_list
;
41 mark_mounts_for_expiry(list
);
42 if (!list_empty(list
))
43 schedule_delayed_work(&cifs_dfs_automount_task
,
44 cifs_dfs_mountpoint_expiry_timeout
);
47 void cifs_dfs_release_automount_timer(void)
49 BUG_ON(!list_empty(&cifs_dfs_automount_list
));
50 cancel_delayed_work_sync(&cifs_dfs_automount_task
);
54 * cifs_build_devname - build a devicename from a UNC and optional prepath
55 * @nodename: pointer to UNC string
56 * @prepath: pointer to prefixpath (or NULL if there isn't one)
58 * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
59 * big enough to hold the final thing. Copy the UNC from the nodename, and
60 * concatenate the prepath onto the end of it if there is one.
62 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
63 * for freeing the returned string.
66 cifs_build_devname(char *nodename
, const char *prepath
)
73 /* skip over any preceding delimiters */
74 nodename
+= strspn(nodename
, "\\");
76 return ERR_PTR(-EINVAL
);
78 /* get length of UNC and set pos to last char */
79 unclen
= strlen(nodename
);
80 pos
= nodename
+ unclen
- 1;
82 /* trim off any trailing delimiters */
83 while (*pos
== '\\') {
89 * +2 for preceding "//"
90 * +1 for delimiter between UNC and prepath
91 * +1 for trailing NULL
93 pplen
= prepath
? strlen(prepath
) : 0;
94 dev
= kmalloc(2 + unclen
+ 1 + pplen
+ 1, GFP_KERNEL
);
96 return ERR_PTR(-ENOMEM
);
99 /* add the initial "//" */
105 /* copy in the UNC portion from referral */
106 memcpy(pos
, nodename
, unclen
);
109 /* copy the prefixpath remainder (if there is one) */
113 memcpy(pos
, prepath
, pplen
);
117 /* NULL terminator */
120 convert_delimiter(dev
, '/');
126 * cifs_compose_mount_options - creates mount options for refferral
127 * @sb_mountdata: parent/root DFS mount options (template)
128 * @fullpath: full path in UNC format
129 * @ref: server's referral
130 * @devname: optional pointer for saving device name
132 * creates mount options for submount based on template options sb_mountdata
133 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
135 * Returns: pointer to new mount options or ERR_PTR.
136 * Caller is responcible for freeing retunrned value if it is not error.
138 char *cifs_compose_mount_options(const char *sb_mountdata
,
139 const char *fullpath
,
140 const struct dfs_info3_param
*ref
,
145 char *mountdata
= NULL
;
146 const char *prepath
= NULL
;
153 if (sb_mountdata
== NULL
)
154 return ERR_PTR(-EINVAL
);
156 if (strlen(fullpath
) - ref
->path_consumed
) {
157 prepath
= fullpath
+ ref
->path_consumed
;
158 /* skip initial delimiter */
159 if (*prepath
== '/' || *prepath
== '\\')
163 name
= cifs_build_devname(ref
->node_name
, prepath
);
167 goto compose_mount_options_err
;
170 rc
= dns_resolve_server_name_to_ip(name
, &srvIP
);
172 cifs_dbg(FYI
, "%s: Failed to resolve server part of %s to IP: %d\n",
174 goto compose_mount_options_err
;
178 * In most cases, we'll be building a shorter string than the original,
179 * but we do have to assume that the address in the ip= option may be
180 * much longer than the original. Add the max length of an address
181 * string to the length of the original string to allow for worst case.
183 md_len
= strlen(sb_mountdata
) + INET6_ADDRSTRLEN
;
184 mountdata
= kzalloc(md_len
+ sizeof("ip=") + 1, GFP_KERNEL
);
185 if (mountdata
== NULL
) {
187 goto compose_mount_options_err
;
190 /* copy all options except of unc,ip,prefixpath */
192 if (strncmp(sb_mountdata
, "sep=", 4) == 0) {
193 sep
= sb_mountdata
[4];
194 strncpy(mountdata
, sb_mountdata
, 5);
199 tkn_e
= strchr(sb_mountdata
+ off
, sep
);
201 noff
= strlen(sb_mountdata
+ off
);
203 noff
= tkn_e
- (sb_mountdata
+ off
) + 1;
205 if (strncasecmp(sb_mountdata
+ off
, "unc=", 4) == 0) {
209 if (strncasecmp(sb_mountdata
+ off
, "ip=", 3) == 0) {
213 if (strncasecmp(sb_mountdata
+ off
, "prefixpath=", 11) == 0) {
217 strncat(mountdata
, sb_mountdata
+ off
, noff
);
220 strcat(mountdata
, sb_mountdata
+ off
);
221 mountdata
[md_len
] = '\0';
223 /* copy new IP and ref share name */
224 if (mountdata
[strlen(mountdata
) - 1] != sep
)
225 strncat(mountdata
, &sep
, 1);
226 strcat(mountdata
, "ip=");
227 strcat(mountdata
, srvIP
);
232 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
233 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
235 compose_mount_options_out
:
239 compose_mount_options_err
:
241 mountdata
= ERR_PTR(rc
);
243 goto compose_mount_options_out
;
247 * cifs_dfs_do_refmount - mounts specified path using provided refferal
248 * @cifs_sb: parent/root superblock
249 * @fullpath: full path in UNC format
250 * @ref: server's referral
252 static struct vfsmount
*cifs_dfs_do_refmount(struct dentry
*mntpt
,
253 struct cifs_sb_info
*cifs_sb
,
254 const char *fullpath
, const struct dfs_info3_param
*ref
)
256 struct vfsmount
*mnt
;
261 * Always pass down the DFS full path to smb3_do_mount() so we
262 * can use it later for failover.
264 devname
= kstrndup(fullpath
, strlen(fullpath
), GFP_KERNEL
);
266 return ERR_PTR(-ENOMEM
);
268 convert_delimiter(devname
, '/');
270 /* strip first '\' from fullpath */
271 mountdata
= cifs_compose_mount_options(cifs_sb
->mountdata
,
272 fullpath
+ 1, ref
, NULL
);
273 if (IS_ERR(mountdata
)) {
275 return (struct vfsmount
*)mountdata
;
278 mnt
= vfs_submount(mntpt
, &cifs_fs_type
, devname
, mountdata
);
284 static void dump_referral(const struct dfs_info3_param
*ref
)
286 cifs_dbg(FYI
, "DFS: ref path: %s\n", ref
->path_name
);
287 cifs_dbg(FYI
, "DFS: node path: %s\n", ref
->node_name
);
288 cifs_dbg(FYI
, "DFS: fl: %d, srv_type: %d\n",
289 ref
->flags
, ref
->server_type
);
290 cifs_dbg(FYI
, "DFS: ref_flags: %d, path_consumed: %d\n",
291 ref
->ref_flag
, ref
->path_consumed
);
295 * Create a vfsmount that we can automount
297 static struct vfsmount
*cifs_dfs_do_automount(struct dentry
*mntpt
)
299 struct dfs_info3_param referral
= {0};
300 struct cifs_sb_info
*cifs_sb
;
301 struct cifs_ses
*ses
;
302 struct cifs_tcon
*tcon
;
303 char *full_path
, *root_path
;
307 struct vfsmount
*mnt
;
309 cifs_dbg(FYI
, "in %s\n", __func__
);
310 BUG_ON(IS_ROOT(mntpt
));
313 * The MSDFS spec states that paths in DFS referral requests and
314 * responses must be prefixed by a single '\' character instead of
315 * the double backslashes usually used in the UNC. This function
316 * gives us the latter, so we must adjust the result.
318 mnt
= ERR_PTR(-ENOMEM
);
320 cifs_sb
= CIFS_SB(mntpt
->d_sb
);
321 if (cifs_sb
->mnt_cifs_flags
& CIFS_MOUNT_NO_DFS
) {
322 mnt
= ERR_PTR(-EREMOTE
);
326 /* always use tree name prefix */
327 full_path
= build_path_from_dentry_optional_prefix(mntpt
, true);
328 if (full_path
== NULL
)
331 cifs_dbg(FYI
, "%s: full_path: %s\n", __func__
, full_path
);
333 if (!cifs_sb_master_tlink(cifs_sb
)) {
334 cifs_dbg(FYI
, "%s: master tlink is NULL\n", __func__
);
338 tcon
= cifs_sb_master_tcon(cifs_sb
);
340 cifs_dbg(FYI
, "%s: master tcon is NULL\n", __func__
);
344 root_path
= kstrdup(tcon
->treeName
, GFP_KERNEL
);
346 mnt
= ERR_PTR(-ENOMEM
);
349 cifs_dbg(FYI
, "%s: root path: %s\n", __func__
, root_path
);
355 * If DFS root has been expired, then unconditionally fetch it again to
356 * refresh DFS referral cache.
358 rc
= dfs_cache_find(xid
, ses
, cifs_sb
->local_nls
, cifs_remap(cifs_sb
),
359 root_path
+ 1, NULL
, NULL
);
361 rc
= dfs_cache_find(xid
, ses
, cifs_sb
->local_nls
,
362 cifs_remap(cifs_sb
), full_path
+ 1,
373 dump_referral(&referral
);
375 len
= strlen(referral
.node_name
);
377 cifs_dbg(VFS
, "%s: Net Address path too short: %s\n",
378 __func__
, referral
.node_name
);
379 mnt
= ERR_PTR(-EINVAL
);
383 * cifs_mount() will retry every available node server in case
386 mnt
= cifs_dfs_do_refmount(mntpt
, cifs_sb
, full_path
, &referral
);
387 cifs_dbg(FYI
, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__
,
388 referral
.node_name
, mnt
);
391 free_dfs_info_param(&referral
);
397 cifs_dbg(FYI
, "leaving %s\n" , __func__
);
402 * Attempt to automount the referral
404 struct vfsmount
*cifs_dfs_d_automount(struct path
*path
)
406 struct vfsmount
*newmnt
;
408 cifs_dbg(FYI
, "in %s\n", __func__
);
410 newmnt
= cifs_dfs_do_automount(path
->dentry
);
411 if (IS_ERR(newmnt
)) {
412 cifs_dbg(FYI
, "leaving %s [automount failed]\n" , __func__
);
416 mntget(newmnt
); /* prevent immediate expiration */
417 mnt_set_expiry(newmnt
, &cifs_dfs_automount_list
);
418 schedule_delayed_work(&cifs_dfs_automount_task
,
419 cifs_dfs_mountpoint_expiry_timeout
);
420 cifs_dbg(FYI
, "leaving %s [ok]\n" , __func__
);
424 const struct inode_operations cifs_dfs_referral_inode_operations
= {