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"
29 static LIST_HEAD(cifs_dfs_automount_list);
31 static void cifs_dfs_expire_automounts(struct work_struct *work);
32 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
33 cifs_dfs_expire_automounts);
34 static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
36 static void cifs_dfs_expire_automounts(struct work_struct *work)
38 struct list_head *list = &cifs_dfs_automount_list;
40 mark_mounts_for_expiry(list);
41 if (!list_empty(list))
42 schedule_delayed_work(&cifs_dfs_automount_task,
43 cifs_dfs_mountpoint_expiry_timeout);
46 void cifs_dfs_release_automount_timer(void)
48 BUG_ON(!list_empty(&cifs_dfs_automount_list));
49 cancel_delayed_work_sync(&cifs_dfs_automount_task);
53 * cifs_build_devname - build a devicename from a UNC and optional prepath
54 * @nodename: pointer to UNC string
55 * @prepath: pointer to prefixpath (or NULL if there isn't one)
57 * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
58 * big enough to hold the final thing. Copy the UNC from the nodename, and
59 * concatenate the prepath onto the end of it if there is one.
61 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
62 * for freeing the returned string.
65 cifs_build_devname(char *nodename, const char *prepath)
72 /* skip over any preceding delimiters */
73 nodename += strspn(nodename, "\\");
75 return ERR_PTR(-EINVAL);
77 /* get length of UNC and set pos to last char */
78 unclen = strlen(nodename);
79 pos = nodename + unclen - 1;
81 /* trim off any trailing delimiters */
82 while (*pos == '\\') {
88 * +2 for preceding "//"
89 * +1 for delimiter between UNC and prepath
90 * +1 for trailing NULL
92 pplen = prepath ? strlen(prepath) : 0;
93 dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
95 return ERR_PTR(-ENOMEM);
98 /* add the initial "//" */
104 /* copy in the UNC portion from referral */
105 memcpy(pos, nodename, unclen);
108 /* copy the prefixpath remainder (if there is one) */
112 memcpy(pos, prepath, pplen);
116 /* NULL terminator */
119 convert_delimiter(dev, '/');
125 * cifs_compose_mount_options - creates mount options for refferral
126 * @sb_mountdata: parent/root DFS mount options (template)
127 * @fullpath: full path in UNC format
128 * @ref: server's referral
129 * @devname: optional pointer for saving device name
131 * creates mount options for submount based on template options sb_mountdata
132 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
134 * Returns: pointer to new mount options or ERR_PTR.
135 * Caller is responcible for freeing retunrned value if it is not error.
137 char *cifs_compose_mount_options(const char *sb_mountdata,
138 const char *fullpath,
139 const struct dfs_info3_param *ref,
144 char *mountdata = NULL;
145 const char *prepath = NULL;
152 if (sb_mountdata == NULL)
153 return ERR_PTR(-EINVAL);
155 if (strlen(fullpath) - ref->path_consumed) {
156 prepath = fullpath + ref->path_consumed;
157 /* skip initial delimiter */
158 if (*prepath == '/' || *prepath == '\\')
162 name = cifs_build_devname(ref->node_name, prepath);
166 goto compose_mount_options_err;
169 rc = dns_resolve_server_name_to_ip(name, &srvIP);
171 cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
173 goto compose_mount_options_err;
177 * In most cases, we'll be building a shorter string than the original,
178 * but we do have to assume that the address in the ip= option may be
179 * much longer than the original. Add the max length of an address
180 * string to the length of the original string to allow for worst case.
182 md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
183 mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
184 if (mountdata == NULL) {
186 goto compose_mount_options_err;
189 /* copy all options except of unc,ip,prefixpath */
191 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
192 sep = sb_mountdata[4];
193 strncpy(mountdata, sb_mountdata, 5);
198 tkn_e = strchr(sb_mountdata + off, sep);
200 noff = strlen(sb_mountdata + off);
202 noff = tkn_e - (sb_mountdata + off) + 1;
204 if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
208 if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
212 if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
216 strncat(mountdata, sb_mountdata + off, noff);
219 strcat(mountdata, sb_mountdata + off);
220 mountdata[md_len] = '\0';
222 /* copy new IP and ref share name */
223 if (mountdata[strlen(mountdata) - 1] != sep)
224 strncat(mountdata, &sep, 1);
225 strcat(mountdata, "ip=");
226 strcat(mountdata, srvIP);
231 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
232 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
234 compose_mount_options_out:
238 compose_mount_options_err:
240 mountdata = ERR_PTR(rc);
242 goto compose_mount_options_out;
246 * cifs_dfs_do_refmount - mounts specified path using provided refferal
247 * @cifs_sb: parent/root superblock
248 * @fullpath: full path in UNC format
249 * @ref: server's referral
251 static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
252 struct cifs_sb_info *cifs_sb,
253 const char *fullpath, const struct dfs_info3_param *ref)
255 struct vfsmount *mnt;
257 char *devname = NULL;
259 /* strip first '\' from fullpath */
260 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
261 fullpath + 1, ref, &devname);
263 if (IS_ERR(mountdata))
264 return (struct vfsmount *)mountdata;
266 mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
273 static void dump_referral(const struct dfs_info3_param *ref)
275 cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
276 cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
277 cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
278 ref->flags, ref->server_type);
279 cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
280 ref->ref_flag, ref->path_consumed);
284 * Create a vfsmount that we can automount
286 static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
288 struct dfs_info3_param *referrals = NULL;
289 unsigned int num_referrals = 0;
290 struct cifs_sb_info *cifs_sb;
291 struct cifs_ses *ses;
296 struct vfsmount *mnt;
297 struct tcon_link *tlink;
299 cifs_dbg(FYI, "in %s\n", __func__);
300 BUG_ON(IS_ROOT(mntpt));
303 * The MSDFS spec states that paths in DFS referral requests and
304 * responses must be prefixed by a single '\' character instead of
305 * the double backslashes usually used in the UNC. This function
306 * gives us the latter, so we must adjust the result.
308 mnt = ERR_PTR(-ENOMEM);
310 cifs_sb = CIFS_SB(mntpt->d_sb);
311 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
312 mnt = ERR_PTR(-EREMOTE);
316 /* always use tree name prefix */
317 full_path = build_path_from_dentry_optional_prefix(mntpt, true);
318 if (full_path == NULL)
321 tlink = cifs_sb_tlink(cifs_sb);
323 mnt = ERR_CAST(tlink);
326 ses = tlink_tcon(tlink)->ses;
329 rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
330 &num_referrals, &referrals,
331 cifs_remap(cifs_sb));
334 cifs_put_tlink(tlink);
336 mnt = ERR_PTR(-ENOENT);
337 for (i = 0; i < num_referrals; i++) {
339 dump_referral(referrals + i);
340 /* connect to a node */
341 len = strlen(referrals[i].node_name);
343 cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
344 __func__, referrals[i].node_name);
345 mnt = ERR_PTR(-EINVAL);
348 mnt = cifs_dfs_do_refmount(mntpt, cifs_sb,
349 full_path, referrals + i);
350 cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
351 __func__, referrals[i].node_name, mnt);
356 /* no valid submounts were found; return error from get_dfs_path() by
362 free_dfs_info_array(referrals, num_referrals);
366 cifs_dbg(FYI, "leaving %s\n" , __func__);
371 * Attempt to automount the referral
373 struct vfsmount *cifs_dfs_d_automount(struct path *path)
375 struct vfsmount *newmnt;
377 cifs_dbg(FYI, "in %s\n", __func__);
379 newmnt = cifs_dfs_do_automount(path->dentry);
380 if (IS_ERR(newmnt)) {
381 cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
385 mntget(newmnt); /* prevent immediate expiration */
386 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
387 schedule_delayed_work(&cifs_dfs_automount_task,
388 cifs_dfs_mountpoint_expiry_timeout);
389 cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
393 const struct inode_operations cifs_dfs_referral_inode_operations = {