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Igor Mammedov6d5ae0d2008-01-25 03:28:31 +00001/*
2 * Contains the CIFS DFS referral mounting routines used for handling
3 * traversal via DFS junction point
4 *
5 * Copyright (c) 2007 Igor Mammedov
Steve French366781c2008-01-25 10:12:41 +00006 * Copyright (C) International Business Machines Corp., 2008
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +00007 * Author(s): Igor Mammedov (niallain@gmail.com)
Steve French366781c2008-01-25 10:12:41 +00008 * Steve French (sfrench@us.ibm.com)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +00009 * 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.
13 */
14
15#include <linux/dcache.h>
16#include <linux/mount.h>
17#include <linux/namei.h>
18#include <linux/vfs.h>
19#include <linux/fs.h>
20#include "cifsglob.h"
21#include "cifsproto.h"
22#include "cifsfs.h"
23#include "dns_resolve.h"
24#include "cifs_debug.h"
25
Steve French8d142132008-04-16 03:56:51 +000026static LIST_HEAD(cifs_dfs_automount_list);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000027
Igor Mammedov78d31a32008-04-24 12:56:07 +040028static void cifs_dfs_expire_automounts(struct work_struct *work);
29static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
30 cifs_dfs_expire_automounts);
31static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000032
Igor Mammedov78d31a32008-04-24 12:56:07 +040033static void cifs_dfs_expire_automounts(struct work_struct *work)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000034{
Igor Mammedov78d31a32008-04-24 12:56:07 +040035 struct list_head *list = &cifs_dfs_automount_list;
36
37 mark_mounts_for_expiry(list);
38 if (!list_empty(list))
39 schedule_delayed_work(&cifs_dfs_automount_task,
40 cifs_dfs_mountpoint_expiry_timeout);
41}
42
43void cifs_dfs_release_automount_timer(void)
44{
45 BUG_ON(!list_empty(&cifs_dfs_automount_list));
46 cancel_delayed_work(&cifs_dfs_automount_task);
47 flush_scheduled_work();
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000048}
49
50/**
51 * cifs_get_share_name - extracts share name from UNC
52 * @node_name: pointer to UNC string
53 *
54 * Extracts sharename form full UNC.
55 * i.e. strips from UNC trailing path that is not part of share
56 * name and fixup missing '\' in the begining of DFS node refferal
57 * if neccessary.
58 * Returns pointer to share name on success or NULL on error.
59 * Caller is responsible for freeing returned string.
60 */
61static char *cifs_get_share_name(const char *node_name)
62{
63 int len;
64 char *UNC;
65 char *pSep;
66
67 len = strlen(node_name);
68 UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
69 GFP_KERNEL);
70 if (!UNC)
71 return NULL;
72
73 /* get share name and server name */
74 if (node_name[1] != '\\') {
75 UNC[0] = '\\';
76 strncpy(UNC+1, node_name, len);
77 len++;
78 UNC[len] = 0;
79 } else {
80 strncpy(UNC, node_name, len);
81 UNC[len] = 0;
82 }
83
84 /* find server name end */
85 pSep = memchr(UNC+2, '\\', len-2);
86 if (!pSep) {
87 cERROR(1, ("%s: no server name end in node name: %s",
Harvey Harrison55f78e12008-03-10 17:14:34 +000088 __func__, node_name));
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000089 kfree(UNC);
90 return NULL;
91 }
92
93 /* find sharename end */
94 pSep++;
95 pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
Igor Mammedovbf62fd82008-04-28 23:05:58 +000096 if (pSep) {
97 /* trim path up to sharename end
98 * now we have share name in UNC */
99 *pSep = 0;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000100 }
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000101
102 return UNC;
103}
104
105
106/**
Steve Frenchc6c00912009-03-18 05:50:07 +0000107 * cifs_compose_mount_options - creates mount options for refferral
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000108 * @sb_mountdata: parent/root DFS mount options (template)
Steve Frenchc6c00912009-03-18 05:50:07 +0000109 * @fullpath: full path in UNC format
Igor Mammedov2c556082008-10-23 13:58:42 +0400110 * @ref: server's referral
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000111 * @devname: pointer for saving device name
112 *
113 * creates mount options for submount based on template options sb_mountdata
114 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
115 *
116 * Returns: pointer to new mount options or ERR_PTR.
117 * Caller is responcible for freeing retunrned value if it is not error.
118 */
Steve Frenchc6c00912009-03-18 05:50:07 +0000119char *cifs_compose_mount_options(const char *sb_mountdata,
120 const char *fullpath,
Igor Mammedov2c556082008-10-23 13:58:42 +0400121 const struct dfs_info3_param *ref,
Steve French366781c2008-01-25 10:12:41 +0000122 char **devname)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000123{
124 int rc;
Steve Frenchc6fbba02008-12-18 01:41:20 +0000125 char *mountdata = NULL;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000126 int md_len;
127 char *tkn_e;
128 char *srvIP = NULL;
129 char sep = ',';
130 int off, noff;
131
132 if (sb_mountdata == NULL)
133 return ERR_PTR(-EINVAL);
134
Igor Mammedov2c556082008-10-23 13:58:42 +0400135 *devname = cifs_get_share_name(ref->node_name);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000136 rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
137 if (rc != 0) {
Steve Frenchc6fbba02008-12-18 01:41:20 +0000138 cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
139 __func__, *devname, rc));;
140 goto compose_mount_options_err;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000141 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400142 /* md_len = strlen(...) + 12 for 'sep+prefixpath='
143 * assuming that we have 'unc=' and 'ip=' in
144 * the original sb_mountdata
145 */
146 md_len = strlen(sb_mountdata) + strlen(srvIP) +
147 strlen(ref->node_name) + 12;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000148 mountdata = kzalloc(md_len+1, GFP_KERNEL);
149 if (mountdata == NULL) {
Steve Frenchc6fbba02008-12-18 01:41:20 +0000150 rc = -ENOMEM;
151 goto compose_mount_options_err;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000152 }
153
154 /* copy all options except of unc,ip,prefixpath */
155 off = 0;
156 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
157 sep = sb_mountdata[4];
158 strncpy(mountdata, sb_mountdata, 5);
159 off += 5;
160 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400161
162 do {
163 tkn_e = strchr(sb_mountdata + off, sep);
164 if (tkn_e == NULL)
165 noff = strlen(sb_mountdata + off);
166 else
167 noff = tkn_e - (sb_mountdata + off) + 1;
168
169 if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000170 off += noff;
171 continue;
172 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400173 if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000174 off += noff;
175 continue;
176 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400177 if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000178 off += noff;
179 continue;
180 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400181 strncat(mountdata, sb_mountdata + off, noff);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000182 off += noff;
Igor Mammedov2c556082008-10-23 13:58:42 +0400183 } while (tkn_e);
184 strcat(mountdata, sb_mountdata + off);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000185 mountdata[md_len] = '\0';
186
187 /* copy new IP and ref share name */
Igor Mammedov2c556082008-10-23 13:58:42 +0400188 if (mountdata[strlen(mountdata) - 1] != sep)
189 strncat(mountdata, &sep, 1);
190 strcat(mountdata, "ip=");
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000191 strcat(mountdata, srvIP);
Igor Mammedov2c556082008-10-23 13:58:42 +0400192 strncat(mountdata, &sep, 1);
193 strcat(mountdata, "unc=");
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000194 strcat(mountdata, *devname);
195
196 /* find & copy prefixpath */
Igor Mammedov2c556082008-10-23 13:58:42 +0400197 tkn_e = strchr(ref->node_name + 2, '\\');
Steve Frenchc6fbba02008-12-18 01:41:20 +0000198 if (tkn_e == NULL) {
199 /* invalid unc, missing share name*/
200 rc = -EINVAL;
201 goto compose_mount_options_err;
202 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400203
Igor Mammedov2c556082008-10-23 13:58:42 +0400204 tkn_e = strchr(tkn_e + 1, '\\');
Steve Frenchc6fbba02008-12-18 01:41:20 +0000205 if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
Igor Mammedov2c556082008-10-23 13:58:42 +0400206 strncat(mountdata, &sep, 1);
207 strcat(mountdata, "prefixpath=");
208 if (tkn_e)
209 strcat(mountdata, tkn_e + 1);
Steve Frenchc6fbba02008-12-18 01:41:20 +0000210 strcat(mountdata, fullpath + ref->path_consumed);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000211 }
212
Harvey Harrison55f78e12008-03-10 17:14:34 +0000213 /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
214 /*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000215
216compose_mount_options_out:
217 kfree(srvIP);
218 return mountdata;
Steve Frenchc6fbba02008-12-18 01:41:20 +0000219
220compose_mount_options_err:
221 kfree(mountdata);
222 mountdata = ERR_PTR(rc);
223 goto compose_mount_options_out;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000224}
225
226
Steve French366781c2008-01-25 10:12:41 +0000227static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
Igor Mammedov2c556082008-10-23 13:58:42 +0400228 struct dentry *dentry, const struct dfs_info3_param *ref)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000229{
230 struct cifs_sb_info *cifs_sb;
231 struct vfsmount *mnt;
232 char *mountdata;
Steve French366781c2008-01-25 10:12:41 +0000233 char *devname = NULL;
Steve Frenchc6c00912009-03-18 05:50:07 +0000234 char *fullpath;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000235
236 cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
Steve Frenchc6c00912009-03-18 05:50:07 +0000237 /*
238 * this function gives us a path with a double backslash prefix. We
239 * require a single backslash for DFS.
240 */
241 fullpath = build_path_from_dentry(dentry);
242 if (!fullpath)
243 return ERR_PTR(-ENOMEM);
244
245 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
246 fullpath + 1, ref, &devname);
247 kfree(fullpath);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000248
249 if (IS_ERR(mountdata))
250 return (struct vfsmount *)mountdata;
251
252 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
253 kfree(mountdata);
254 kfree(devname);
255 return mnt;
256
257}
258
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000259static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
260 struct list_head *mntlist)
261{
262 /* stolen from afs code */
263 int err;
264
265 mntget(newmnt);
Al Viro8d66bf52008-08-01 09:05:54 -0400266 err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags, mntlist);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000267 switch (err) {
268 case 0:
Igor Mammedov78d31a32008-04-24 12:56:07 +0400269 path_put(&nd->path);
Jan Blunck4ac91372008-02-14 19:34:32 -0800270 nd->path.mnt = newmnt;
271 nd->path.dentry = dget(newmnt->mnt_root);
Igor Mammedov78d31a32008-04-24 12:56:07 +0400272 schedule_delayed_work(&cifs_dfs_automount_task,
273 cifs_dfs_mountpoint_expiry_timeout);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000274 break;
275 case -EBUSY:
276 /* someone else made a mount here whilst we were busy */
Jan Blunck4ac91372008-02-14 19:34:32 -0800277 while (d_mountpoint(nd->path.dentry) &&
Al Viro9393bd02009-04-18 13:58:15 -0400278 follow_down(&nd->path))
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000279 ;
280 err = 0;
281 default:
282 mntput(newmnt);
283 break;
284 }
285 return err;
286}
287
Steve French366781c2008-01-25 10:12:41 +0000288static void dump_referral(const struct dfs_info3_param *ref)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000289{
290 cFYI(1, ("DFS: ref path: %s", ref->path_name));
291 cFYI(1, ("DFS: node path: %s", ref->node_name));
292 cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
293 cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
Igor Mammedov8aad0182008-02-15 18:21:49 +0000294 ref->path_consumed));
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000295}
296
297
298static void*
299cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
300{
301 struct dfs_info3_param *referrals = NULL;
302 unsigned int num_referrals = 0;
303 struct cifs_sb_info *cifs_sb;
304 struct cifsSesInfo *ses;
305 char *full_path = NULL;
306 int xid, i;
307 int rc = 0;
308 struct vfsmount *mnt = ERR_PTR(-ENOENT);
309
Harvey Harrison55f78e12008-03-10 17:14:34 +0000310 cFYI(1, ("in %s", __func__));
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000311 BUG_ON(IS_ROOT(dentry));
312
313 xid = GetXid();
314
Jan Blunck4ac91372008-02-14 19:34:32 -0800315 dput(nd->path.dentry);
316 nd->path.dentry = dget(dentry);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000317
318 cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
319 ses = cifs_sb->tcon->ses;
320
321 if (!ses) {
322 rc = -EINVAL;
323 goto out_err;
324 }
325
Steve Frenchc6fbba02008-12-18 01:41:20 +0000326 /*
327 * The MSDFS spec states that paths in DFS referral requests and
328 * responses must be prefixed by a single '\' character instead of
329 * the double backslashes usually used in the UNC. This function
330 * gives us the latter, so we must adjust the result.
331 */
Igor Mammedovde2db8d2008-05-16 13:10:32 +0400332 full_path = build_path_from_dentry(dentry);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000333 if (full_path == NULL) {
334 rc = -ENOMEM;
335 goto out_err;
336 }
337
Steve Frenchc6fbba02008-12-18 01:41:20 +0000338 rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000339 &num_referrals, &referrals,
340 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
341
342 for (i = 0; i < num_referrals; i++) {
Steve Frenchcf398e32009-05-01 03:50:42 +0000343 int len;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000344 dump_referral(referrals+i);
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300345 /* connect to a node */
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300346 len = strlen(referrals[i].node_name);
347 if (len < 2) {
348 cERROR(1, ("%s: Net Address path too short: %s",
Harvey Harrison55f78e12008-03-10 17:14:34 +0000349 __func__, referrals[i].node_name));
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300350 rc = -EINVAL;
351 goto out_err;
352 }
353 mnt = cifs_dfs_do_refmount(nd->path.mnt,
354 nd->path.dentry, referrals + i);
355 cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000356 referrals[i].node_name, mnt));
357
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300358 /* complete mount procedure if we accured submount */
359 if (!IS_ERR(mnt))
360 break;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000361 }
362
363 /* we need it cause for() above could exit without valid submount */
364 rc = PTR_ERR(mnt);
365 if (IS_ERR(mnt))
366 goto out_err;
367
Jan Blunck4ac91372008-02-14 19:34:32 -0800368 nd->path.mnt->mnt_flags |= MNT_SHRINKABLE;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000369 rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
370
371out:
372 FreeXid(xid);
373 free_dfs_info_array(referrals, num_referrals);
374 kfree(full_path);
Harvey Harrison55f78e12008-03-10 17:14:34 +0000375 cFYI(1, ("leaving %s" , __func__));
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000376 return ERR_PTR(rc);
377out_err:
Jan Blunck1d957f92008-02-14 19:34:35 -0800378 path_put(&nd->path);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000379 goto out;
380}
381
382struct inode_operations cifs_dfs_referral_inode_operations = {
383 .follow_link = cifs_dfs_follow_mountpoint,
384};
385