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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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090018#include <linux/slab.h>
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000019#include <linux/vfs.h>
20#include <linux/fs.h>
Jeff Layton166faf22013-05-24 07:40:04 -040021#include <linux/inet.h>
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000022#include "cifsglob.h"
23#include "cifsproto.h"
24#include "cifsfs.h"
25#include "dns_resolve.h"
26#include "cifs_debug.h"
Nakajima Akirabc8ebdc42015-02-13 15:35:58 +090027#include "cifs_unicode.h"
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000028
Steve French8d142132008-04-16 03:56:51 +000029static LIST_HEAD(cifs_dfs_automount_list);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000030
Igor Mammedov78d31a32008-04-24 12:56:07 +040031static void cifs_dfs_expire_automounts(struct work_struct *work);
32static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
33 cifs_dfs_expire_automounts);
34static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000035
Igor Mammedov78d31a32008-04-24 12:56:07 +040036static void cifs_dfs_expire_automounts(struct work_struct *work)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000037{
Igor Mammedov78d31a32008-04-24 12:56:07 +040038 struct list_head *list = &cifs_dfs_automount_list;
39
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);
44}
45
46void cifs_dfs_release_automount_timer(void)
47{
48 BUG_ON(!list_empty(&cifs_dfs_automount_list));
Tejun Heo3e24e132010-10-19 17:55:54 +020049 cancel_delayed_work_sync(&cifs_dfs_automount_task);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000050}
51
52/**
Jeff Laytond9deef02013-05-24 07:40:06 -040053 * 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)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000056 *
Jeff Laytond9deef02013-05-24 07:40:06 -040057 * 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.
60 *
61 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
62 * for freeing the returned string.
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000063 */
Jeff Laytond9deef02013-05-24 07:40:06 -040064static char *
65cifs_build_devname(char *nodename, const char *prepath)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000066{
Jeff Laytond9deef02013-05-24 07:40:06 -040067 size_t pplen;
68 size_t unclen;
69 char *dev;
70 char *pos;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000071
Jeff Laytond9deef02013-05-24 07:40:06 -040072 /* skip over any preceding delimiters */
73 nodename += strspn(nodename, "\\");
74 if (!*nodename)
75 return ERR_PTR(-EINVAL);
76
77 /* get length of UNC and set pos to last char */
78 unclen = strlen(nodename);
79 pos = nodename + unclen - 1;
80
81 /* trim off any trailing delimiters */
82 while (*pos == '\\') {
83 --pos;
84 --unclen;
85 }
86
87 /* allocate a buffer:
88 * +2 for preceding "//"
89 * +1 for delimiter between UNC and prepath
90 * +1 for trailing NULL
91 */
92 pplen = prepath ? strlen(prepath) : 0;
93 dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
94 if (!dev)
Jeff Layton7b91e262009-07-23 15:22:30 -040095 return ERR_PTR(-ENOMEM);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +000096
Jeff Laytond9deef02013-05-24 07:40:06 -040097 pos = dev;
98 /* add the initial "//" */
99 *pos = '/';
100 ++pos;
101 *pos = '/';
102 ++pos;
103
104 /* copy in the UNC portion from referral */
105 memcpy(pos, nodename, unclen);
106 pos += unclen;
107
108 /* copy the prefixpath remainder (if there is one) */
109 if (pplen) {
110 *pos = '/';
111 ++pos;
112 memcpy(pos, prepath, pplen);
113 pos += pplen;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000114 }
115
Jeff Laytond9deef02013-05-24 07:40:06 -0400116 /* NULL terminator */
117 *pos = '\0';
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000118
Jeff Laytond9deef02013-05-24 07:40:06 -0400119 convert_delimiter(dev, '/');
120 return dev;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000121}
122
123
124/**
Steve Frenchc6c00912009-03-18 05:50:07 +0000125 * cifs_compose_mount_options - creates mount options for refferral
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000126 * @sb_mountdata: parent/root DFS mount options (template)
Steve Frenchc6c00912009-03-18 05:50:07 +0000127 * @fullpath: full path in UNC format
Igor Mammedov2c556082008-10-23 13:58:42 +0400128 * @ref: server's referral
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000129 * @devname: pointer for saving device name
130 *
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.
133 *
134 * Returns: pointer to new mount options or ERR_PTR.
135 * Caller is responcible for freeing retunrned value if it is not error.
136 */
Steve Frenchc6c00912009-03-18 05:50:07 +0000137char *cifs_compose_mount_options(const char *sb_mountdata,
138 const char *fullpath,
Igor Mammedov2c556082008-10-23 13:58:42 +0400139 const struct dfs_info3_param *ref,
Steve French366781c2008-01-25 10:12:41 +0000140 char **devname)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000141{
142 int rc;
Steve Frenchc6fbba02008-12-18 01:41:20 +0000143 char *mountdata = NULL;
Jeff Laytond9deef02013-05-24 07:40:06 -0400144 const char *prepath = NULL;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000145 int md_len;
146 char *tkn_e;
147 char *srvIP = NULL;
148 char sep = ',';
149 int off, noff;
150
151 if (sb_mountdata == NULL)
152 return ERR_PTR(-EINVAL);
153
Sachin Prabhu11e31642016-02-08 13:44:01 +0530154 if (strlen(fullpath) - ref->path_consumed) {
Jeff Laytond9deef02013-05-24 07:40:06 -0400155 prepath = fullpath + ref->path_consumed;
Sachin Prabhu11e31642016-02-08 13:44:01 +0530156 /* skip initial delimiter */
157 if (*prepath == '/' || *prepath == '\\')
158 prepath++;
159 }
Jeff Laytond9deef02013-05-24 07:40:06 -0400160
161 *devname = cifs_build_devname(ref->node_name, prepath);
Jeff Layton7b91e262009-07-23 15:22:30 -0400162 if (IS_ERR(*devname)) {
163 rc = PTR_ERR(*devname);
164 *devname = NULL;
165 goto compose_mount_options_err;
166 }
167
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000168 rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
David Howells67b76262010-07-22 18:33:01 +0100169 if (rc < 0) {
Joe Perchesf96637b2013-05-04 22:12:25 -0500170 cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
171 __func__, *devname, rc);
Steve Frenchc6fbba02008-12-18 01:41:20 +0000172 goto compose_mount_options_err;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000173 }
Jeff Laytonb8028982011-07-26 12:20:18 -0400174
Jeff Laytond9deef02013-05-24 07:40:06 -0400175 /*
176 * In most cases, we'll be building a shorter string than the original,
177 * but we do have to assume that the address in the ip= option may be
178 * much longer than the original. Add the max length of an address
179 * string to the length of the original string to allow for worst case.
Igor Mammedov2c556082008-10-23 13:58:42 +0400180 */
Jeff Laytond9deef02013-05-24 07:40:06 -0400181 md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
Insu Yunf34d69c2016-02-01 11:34:58 -0500182 mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000183 if (mountdata == NULL) {
Steve Frenchc6fbba02008-12-18 01:41:20 +0000184 rc = -ENOMEM;
185 goto compose_mount_options_err;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000186 }
187
188 /* copy all options except of unc,ip,prefixpath */
189 off = 0;
190 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
191 sep = sb_mountdata[4];
192 strncpy(mountdata, sb_mountdata, 5);
193 off += 5;
194 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400195
196 do {
197 tkn_e = strchr(sb_mountdata + off, sep);
198 if (tkn_e == NULL)
199 noff = strlen(sb_mountdata + off);
200 else
201 noff = tkn_e - (sb_mountdata + off) + 1;
202
Rasmus Villemoes87e747c2014-10-13 15:54:35 -0700203 if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000204 off += noff;
205 continue;
206 }
Rasmus Villemoes87e747c2014-10-13 15:54:35 -0700207 if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000208 off += noff;
209 continue;
210 }
Rasmus Villemoes87e747c2014-10-13 15:54:35 -0700211 if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000212 off += noff;
213 continue;
214 }
Igor Mammedov2c556082008-10-23 13:58:42 +0400215 strncat(mountdata, sb_mountdata + off, noff);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000216 off += noff;
Igor Mammedov2c556082008-10-23 13:58:42 +0400217 } while (tkn_e);
218 strcat(mountdata, sb_mountdata + off);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000219 mountdata[md_len] = '\0';
220
221 /* copy new IP and ref share name */
Igor Mammedov2c556082008-10-23 13:58:42 +0400222 if (mountdata[strlen(mountdata) - 1] != sep)
223 strncat(mountdata, &sep, 1);
224 strcat(mountdata, "ip=");
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000225 strcat(mountdata, srvIP);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000226
Joe Perchesf96637b2013-05-04 22:12:25 -0500227 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
228 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000229
230compose_mount_options_out:
231 kfree(srvIP);
232 return mountdata;
Steve Frenchc6fbba02008-12-18 01:41:20 +0000233
234compose_mount_options_err:
235 kfree(mountdata);
236 mountdata = ERR_PTR(rc);
Cong Ding10b8c7d2013-01-22 19:20:58 -0500237 kfree(*devname);
238 *devname = NULL;
Steve Frenchc6fbba02008-12-18 01:41:20 +0000239 goto compose_mount_options_out;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000240}
241
Steve Frenchf67909c2010-07-26 18:20:16 +0000242/**
243 * cifs_dfs_do_refmount - mounts specified path using provided refferal
244 * @cifs_sb: parent/root superblock
245 * @fullpath: full path in UNC format
246 * @ref: server's referral
247 */
248static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
249 const char *fullpath, const struct dfs_info3_param *ref)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000250{
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000251 struct vfsmount *mnt;
252 char *mountdata;
Steve French366781c2008-01-25 10:12:41 +0000253 char *devname = NULL;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000254
Steve Frenchf67909c2010-07-26 18:20:16 +0000255 /* strip first '\' from fullpath */
Steve Frenchc6c00912009-03-18 05:50:07 +0000256 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
257 fullpath + 1, ref, &devname);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000258
259 if (IS_ERR(mountdata))
260 return (struct vfsmount *)mountdata;
261
262 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
263 kfree(mountdata);
264 kfree(devname);
265 return mnt;
266
267}
268
Steve French366781c2008-01-25 10:12:41 +0000269static void dump_referral(const struct dfs_info3_param *ref)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000270{
Joe Perchesf96637b2013-05-04 22:12:25 -0500271 cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
272 cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
273 cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
274 ref->flags, ref->server_type);
275 cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
276 ref->ref_flag, ref->path_consumed);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000277}
278
David Howells01c64fe2011-01-14 18:45:47 +0000279/*
280 * Create a vfsmount that we can automount
281 */
282static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000283{
284 struct dfs_info3_param *referrals = NULL;
285 unsigned int num_referrals = 0;
286 struct cifs_sb_info *cifs_sb;
Steve French96daf2b2011-05-27 04:34:02 +0000287 struct cifs_ses *ses;
David Howells01c64fe2011-01-14 18:45:47 +0000288 char *full_path;
Pavel Shilovsky6d5786a2012-06-20 11:21:16 +0400289 unsigned int xid;
290 int i;
David Howells01c64fe2011-01-14 18:45:47 +0000291 int rc;
292 struct vfsmount *mnt;
Jeff Layton7ffec372010-09-29 19:51:11 -0400293 struct tcon_link *tlink;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000294
Joe Perchesf96637b2013-05-04 22:12:25 -0500295 cifs_dbg(FYI, "in %s\n", __func__);
David Howells01c64fe2011-01-14 18:45:47 +0000296 BUG_ON(IS_ROOT(mntpt));
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000297
Steve Frenchc6fbba02008-12-18 01:41:20 +0000298 /*
299 * The MSDFS spec states that paths in DFS referral requests and
300 * responses must be prefixed by a single '\' character instead of
301 * the double backslashes usually used in the UNC. This function
302 * gives us the latter, so we must adjust the result.
303 */
David Howells01c64fe2011-01-14 18:45:47 +0000304 mnt = ERR_PTR(-ENOMEM);
305 full_path = build_path_from_dentry(mntpt);
306 if (full_path == NULL)
Jeff Layton31c26592011-01-31 07:24:46 -0500307 goto cdda_exit;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000308
Al Virofc640052016-04-10 01:33:30 -0400309 cifs_sb = CIFS_SB(mntpt->d_sb);
Jeff Layton7ffec372010-09-29 19:51:11 -0400310 tlink = cifs_sb_tlink(cifs_sb);
311 if (IS_ERR(tlink)) {
David Howells01c64fe2011-01-14 18:45:47 +0000312 mnt = ERR_CAST(tlink);
313 goto free_full_path;
Jeff Layton7ffec372010-09-29 19:51:11 -0400314 }
315 ses = tlink_tcon(tlink)->ses;
316
Pavel Shilovsky6d5786a2012-06-20 11:21:16 +0400317 xid = get_xid();
Jeff Layton7ffec372010-09-29 19:51:11 -0400318 rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000319 &num_referrals, &referrals,
Nakajima Akirabc8ebdc42015-02-13 15:35:58 +0900320 cifs_remap(cifs_sb));
Pavel Shilovsky6d5786a2012-06-20 11:21:16 +0400321 free_xid(xid);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000322
Jeff Layton7ffec372010-09-29 19:51:11 -0400323 cifs_put_tlink(tlink);
324
David Howells01c64fe2011-01-14 18:45:47 +0000325 mnt = ERR_PTR(-ENOENT);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000326 for (i = 0; i < num_referrals; i++) {
Steve Frenchcf398e32009-05-01 03:50:42 +0000327 int len;
David Howells01c64fe2011-01-14 18:45:47 +0000328 dump_referral(referrals + i);
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300329 /* connect to a node */
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300330 len = strlen(referrals[i].node_name);
331 if (len < 2) {
Joe Perchesf96637b2013-05-04 22:12:25 -0500332 cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
333 __func__, referrals[i].node_name);
David Howells01c64fe2011-01-14 18:45:47 +0000334 mnt = ERR_PTR(-EINVAL);
335 break;
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300336 }
Steve Frenchf67909c2010-07-26 18:20:16 +0000337 mnt = cifs_dfs_do_refmount(cifs_sb,
338 full_path, referrals + i);
Joe Perchesf96637b2013-05-04 22:12:25 -0500339 cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
340 __func__, referrals[i].node_name, mnt);
Igor Mammedov1af28ce2009-03-17 19:00:30 +0300341 if (!IS_ERR(mnt))
David Howells01c64fe2011-01-14 18:45:47 +0000342 goto success;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000343 }
344
David Howells01c64fe2011-01-14 18:45:47 +0000345 /* no valid submounts were found; return error from get_dfs_path() by
346 * preference */
347 if (rc != 0)
348 mnt = ERR_PTR(rc);
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000349
David Howells01c64fe2011-01-14 18:45:47 +0000350success:
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000351 free_dfs_info_array(referrals, num_referrals);
David Howells01c64fe2011-01-14 18:45:47 +0000352free_full_path:
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000353 kfree(full_path);
Jeff Layton31c26592011-01-31 07:24:46 -0500354cdda_exit:
Joe Perchesf96637b2013-05-04 22:12:25 -0500355 cifs_dbg(FYI, "leaving %s\n" , __func__);
David Howells01c64fe2011-01-14 18:45:47 +0000356 return mnt;
357}
358
359/*
360 * Attempt to automount the referral
361 */
362struct vfsmount *cifs_dfs_d_automount(struct path *path)
363{
364 struct vfsmount *newmnt;
David Howells01c64fe2011-01-14 18:45:47 +0000365
Joe Perchesf96637b2013-05-04 22:12:25 -0500366 cifs_dbg(FYI, "in %s\n", __func__);
David Howells01c64fe2011-01-14 18:45:47 +0000367
368 newmnt = cifs_dfs_do_automount(path->dentry);
369 if (IS_ERR(newmnt)) {
Joe Perchesf96637b2013-05-04 22:12:25 -0500370 cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
David Howells01c64fe2011-01-14 18:45:47 +0000371 return newmnt;
372 }
373
David Howellsea5b7782011-01-14 19:10:03 +0000374 mntget(newmnt); /* prevent immediate expiration */
375 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
376 schedule_delayed_work(&cifs_dfs_automount_task,
377 cifs_dfs_mountpoint_expiry_timeout);
Joe Perchesf96637b2013-05-04 22:12:25 -0500378 cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
David Howellsea5b7782011-01-14 19:10:03 +0000379 return newmnt;
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000380}
381
Alexey Dobriyan6e1d5dc2009-09-21 17:01:11 -0700382const struct inode_operations cifs_dfs_referral_inode_operations = {
Igor Mammedov6d5ae0d2008-01-25 03:28:31 +0000383};