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>
22 #include "cifsproto.h"
24 #include "dns_resolve.h"
25 #include "cifs_debug.h"
27 static LIST_HEAD(cifs_dfs_automount_list);
29 static void cifs_dfs_expire_automounts(struct work_struct *work);
30 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
31 cifs_dfs_expire_automounts);
32 static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
34 static void cifs_dfs_expire_automounts(struct work_struct *work)
36 struct list_head *list = &cifs_dfs_automount_list;
38 mark_mounts_for_expiry(list);
39 if (!list_empty(list))
40 schedule_delayed_work(&cifs_dfs_automount_task,
41 cifs_dfs_mountpoint_expiry_timeout);
44 void cifs_dfs_release_automount_timer(void)
46 BUG_ON(!list_empty(&cifs_dfs_automount_list));
47 cancel_delayed_work(&cifs_dfs_automount_task);
48 flush_scheduled_work();
52 * cifs_get_share_name - extracts share name from UNC
53 * @node_name: pointer to UNC string
55 * Extracts sharename form full UNC.
56 * i.e. strips from UNC trailing path that is not part of share
57 * name and fixup missing '\' in the begining of DFS node refferal
59 * Returns pointer to share name on success or ERR_PTR on error.
60 * Caller is responsible for freeing returned string.
62 static char *cifs_get_share_name(const char *node_name)
68 len = strlen(node_name);
69 UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
72 return ERR_PTR(-ENOMEM);
74 /* get share name and server name */
75 if (node_name[1] != '\\') {
77 strncpy(UNC+1, node_name, len);
81 strncpy(UNC, node_name, len);
85 /* find server name end */
86 pSep = memchr(UNC+2, '\\', len-2);
88 cERROR(1, "%s: no server name end in node name: %s",
91 return ERR_PTR(-EINVAL);
94 /* find sharename end */
96 pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
98 /* trim path up to sharename end
99 * now we have share name in UNC */
108 * cifs_compose_mount_options - creates mount options for refferral
109 * @sb_mountdata: parent/root DFS mount options (template)
110 * @fullpath: full path in UNC format
111 * @ref: server's referral
112 * @devname: pointer for saving device name
114 * creates mount options for submount based on template options sb_mountdata
115 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
117 * Returns: pointer to new mount options or ERR_PTR.
118 * Caller is responcible for freeing retunrned value if it is not error.
120 char *cifs_compose_mount_options(const char *sb_mountdata,
121 const char *fullpath,
122 const struct dfs_info3_param *ref,
126 char *mountdata = NULL;
133 if (sb_mountdata == NULL)
134 return ERR_PTR(-EINVAL);
136 *devname = cifs_get_share_name(ref->node_name);
137 if (IS_ERR(*devname)) {
138 rc = PTR_ERR(*devname);
140 goto compose_mount_options_err;
143 rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
145 cERROR(1, "%s: Failed to resolve server part of %s to IP: %d",
146 __func__, *devname, rc);
147 goto compose_mount_options_err;
149 /* md_len = strlen(...) + 12 for 'sep+prefixpath='
150 * assuming that we have 'unc=' and 'ip=' in
151 * the original sb_mountdata
153 md_len = strlen(sb_mountdata) + strlen(srvIP) +
154 strlen(ref->node_name) + 12;
155 mountdata = kzalloc(md_len+1, GFP_KERNEL);
156 if (mountdata == NULL) {
158 goto compose_mount_options_err;
161 /* copy all options except of unc,ip,prefixpath */
163 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
164 sep = sb_mountdata[4];
165 strncpy(mountdata, sb_mountdata, 5);
170 tkn_e = strchr(sb_mountdata + off, sep);
172 noff = strlen(sb_mountdata + off);
174 noff = tkn_e - (sb_mountdata + off) + 1;
176 if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
180 if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
184 if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
188 strncat(mountdata, sb_mountdata + off, noff);
191 strcat(mountdata, sb_mountdata + off);
192 mountdata[md_len] = '\0';
194 /* copy new IP and ref share name */
195 if (mountdata[strlen(mountdata) - 1] != sep)
196 strncat(mountdata, &sep, 1);
197 strcat(mountdata, "ip=");
198 strcat(mountdata, srvIP);
199 strncat(mountdata, &sep, 1);
200 strcat(mountdata, "unc=");
201 strcat(mountdata, *devname);
203 /* find & copy prefixpath */
204 tkn_e = strchr(ref->node_name + 2, '\\');
206 /* invalid unc, missing share name*/
208 goto compose_mount_options_err;
211 tkn_e = strchr(tkn_e + 1, '\\');
212 if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
213 strncat(mountdata, &sep, 1);
214 strcat(mountdata, "prefixpath=");
216 strcat(mountdata, tkn_e + 1);
217 strcat(mountdata, fullpath + ref->path_consumed);
220 /*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/
221 /*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/
223 compose_mount_options_out:
227 compose_mount_options_err:
229 mountdata = ERR_PTR(rc);
230 goto compose_mount_options_out;
234 static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
235 struct dentry *dentry, const struct dfs_info3_param *ref)
237 struct cifs_sb_info *cifs_sb;
238 struct vfsmount *mnt;
240 char *devname = NULL;
243 cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
245 * this function gives us a path with a double backslash prefix. We
246 * require a single backslash for DFS.
248 fullpath = build_path_from_dentry(dentry);
250 return ERR_PTR(-ENOMEM);
252 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
253 fullpath + 1, ref, &devname);
256 if (IS_ERR(mountdata))
257 return (struct vfsmount *)mountdata;
259 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
266 static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
267 struct list_head *mntlist)
269 /* stolen from afs code */
273 err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist);
277 nd->path.mnt = newmnt;
278 nd->path.dentry = dget(newmnt->mnt_root);
279 schedule_delayed_work(&cifs_dfs_automount_task,
280 cifs_dfs_mountpoint_expiry_timeout);
283 /* someone else made a mount here whilst we were busy */
284 while (d_mountpoint(nd->path.dentry) &&
285 follow_down(&nd->path))
295 static void dump_referral(const struct dfs_info3_param *ref)
297 cFYI(1, "DFS: ref path: %s", ref->path_name);
298 cFYI(1, "DFS: node path: %s", ref->node_name);
299 cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type);
300 cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
306 cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
308 struct dfs_info3_param *referrals = NULL;
309 unsigned int num_referrals = 0;
310 struct cifs_sb_info *cifs_sb;
311 struct cifsSesInfo *ses;
312 char *full_path = NULL;
315 struct vfsmount *mnt = ERR_PTR(-ENOENT);
317 cFYI(1, "in %s", __func__);
318 BUG_ON(IS_ROOT(dentry));
322 dput(nd->path.dentry);
323 nd->path.dentry = dget(dentry);
325 cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
326 ses = cifs_sb->tcon->ses;
334 * The MSDFS spec states that paths in DFS referral requests and
335 * responses must be prefixed by a single '\' character instead of
336 * the double backslashes usually used in the UNC. This function
337 * gives us the latter, so we must adjust the result.
339 full_path = build_path_from_dentry(dentry);
340 if (full_path == NULL) {
345 rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
346 &num_referrals, &referrals,
347 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
349 for (i = 0; i < num_referrals; i++) {
351 dump_referral(referrals+i);
352 /* connect to a node */
353 len = strlen(referrals[i].node_name);
355 cERROR(1, "%s: Net Address path too short: %s",
356 __func__, referrals[i].node_name);
360 mnt = cifs_dfs_do_refmount(nd->path.mnt,
361 nd->path.dentry, referrals + i);
362 cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
363 referrals[i].node_name, mnt);
365 /* complete mount procedure if we accured submount */
370 /* we need it cause for() above could exit without valid submount */
375 rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
379 free_dfs_info_array(referrals, num_referrals);
381 cFYI(1, "leaving %s" , __func__);
388 const struct inode_operations cifs_dfs_referral_inode_operations = {
389 .follow_link = cifs_dfs_follow_mountpoint,