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1/*
2 * Contains the CIFS DFS referral mounting routines used for handling
3 * traversal via DFS junction point
4 *
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.
13 */
14
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>
20#include <linux/fs.h>
21#include <linux/inet.h>
22#include "cifsglob.h"
23#include "cifsproto.h"
24#include "cifsfs.h"
25#include "dns_resolve.h"
26#include "cifs_debug.h"
27#include "cifs_unicode.h"
28
29static LIST_HEAD(cifs_dfs_automount_list);
30
31static 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;
35
36static void cifs_dfs_expire_automounts(struct work_struct *work)
37{
38 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));
49 cancel_delayed_work_sync(&cifs_dfs_automount_task);
50}
51
52/**
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)
56 *
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.
60 *
61 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
62 * for freeing the returned string.
63 */
64static char *
65cifs_build_devname(char *nodename, const char *prepath)
66{
67 size_t pplen;
68 size_t unclen;
69 char *dev;
70 char *pos;
71
72 /* 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)
95 return ERR_PTR(-ENOMEM);
96
97 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;
114 }
115
116 /* NULL terminator */
117 *pos = '\0';
118
119 convert_delimiter(dev, '/');
120 return dev;
121}
122
123
124/**
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: 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 */
137char *cifs_compose_mount_options(const char *sb_mountdata,
138 const char *fullpath,
139 const struct dfs_info3_param *ref,
140 char **devname)
141{
142 int rc;
143 char *mountdata = NULL;
144 const char *prepath = NULL;
145 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
154 if (strlen(fullpath) - ref->path_consumed)
155 prepath = fullpath + ref->path_consumed;
156
157 *devname = cifs_build_devname(ref->node_name, prepath);
158 if (IS_ERR(*devname)) {
159 rc = PTR_ERR(*devname);
160 *devname = NULL;
161 goto compose_mount_options_err;
162 }
163
164 rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
165 if (rc < 0) {
166 cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
167 __func__, *devname, rc);
168 goto compose_mount_options_err;
169 }
170
171 /*
172 * In most cases, we'll be building a shorter string than the original,
173 * but we do have to assume that the address in the ip= option may be
174 * much longer than the original. Add the max length of an address
175 * string to the length of the original string to allow for worst case.
176 */
177 md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
178 mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
179 if (mountdata == NULL) {
180 rc = -ENOMEM;
181 goto compose_mount_options_err;
182 }
183
184 /* copy all options except of unc,ip,prefixpath */
185 off = 0;
186 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
187 sep = sb_mountdata[4];
188 strncpy(mountdata, sb_mountdata, 5);
189 off += 5;
190 }
191
192 do {
193 tkn_e = strchr(sb_mountdata + off, sep);
194 if (tkn_e == NULL)
195 noff = strlen(sb_mountdata + off);
196 else
197 noff = tkn_e - (sb_mountdata + off) + 1;
198
199 if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
200 off += noff;
201 continue;
202 }
203 if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
204 off += noff;
205 continue;
206 }
207 if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
208 off += noff;
209 continue;
210 }
211 strncat(mountdata, sb_mountdata + off, noff);
212 off += noff;
213 } while (tkn_e);
214 strcat(mountdata, sb_mountdata + off);
215 mountdata[md_len] = '\0';
216
217 /* copy new IP and ref share name */
218 if (mountdata[strlen(mountdata) - 1] != sep)
219 strncat(mountdata, &sep, 1);
220 strcat(mountdata, "ip=");
221 strcat(mountdata, srvIP);
222
223 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
224 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
225
226compose_mount_options_out:
227 kfree(srvIP);
228 return mountdata;
229
230compose_mount_options_err:
231 kfree(mountdata);
232 mountdata = ERR_PTR(rc);
233 kfree(*devname);
234 *devname = NULL;
235 goto compose_mount_options_out;
236}
237
238/**
239 * cifs_dfs_do_refmount - mounts specified path using provided refferal
240 * @cifs_sb: parent/root superblock
241 * @fullpath: full path in UNC format
242 * @ref: server's referral
243 */
244static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
245 const char *fullpath, const struct dfs_info3_param *ref)
246{
247 struct vfsmount *mnt;
248 char *mountdata;
249 char *devname = NULL;
250
251 /* strip first '\' from fullpath */
252 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
253 fullpath + 1, ref, &devname);
254
255 if (IS_ERR(mountdata))
256 return (struct vfsmount *)mountdata;
257
258 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
259 kfree(mountdata);
260 kfree(devname);
261 return mnt;
262
263}
264
265static void dump_referral(const struct dfs_info3_param *ref)
266{
267 cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
268 cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
269 cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
270 ref->flags, ref->server_type);
271 cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
272 ref->ref_flag, ref->path_consumed);
273}
274
275/*
276 * Create a vfsmount that we can automount
277 */
278static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
279{
280 struct dfs_info3_param *referrals = NULL;
281 unsigned int num_referrals = 0;
282 struct cifs_sb_info *cifs_sb;
283 struct cifs_ses *ses;
284 char *full_path;
285 unsigned int xid;
286 int i;
287 int rc;
288 struct vfsmount *mnt;
289 struct tcon_link *tlink;
290
291 cifs_dbg(FYI, "in %s\n", __func__);
292 BUG_ON(IS_ROOT(mntpt));
293
294 /*
295 * The MSDFS spec states that paths in DFS referral requests and
296 * responses must be prefixed by a single '\' character instead of
297 * the double backslashes usually used in the UNC. This function
298 * gives us the latter, so we must adjust the result.
299 */
300 mnt = ERR_PTR(-ENOMEM);
301 full_path = build_path_from_dentry(mntpt);
302 if (full_path == NULL)
303 goto cdda_exit;
304
305 cifs_sb = CIFS_SB(d_inode(mntpt)->i_sb);
306 tlink = cifs_sb_tlink(cifs_sb);
307 if (IS_ERR(tlink)) {
308 mnt = ERR_CAST(tlink);
309 goto free_full_path;
310 }
311 ses = tlink_tcon(tlink)->ses;
312
313 xid = get_xid();
314 rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
315 &num_referrals, &referrals,
316 cifs_remap(cifs_sb));
317 free_xid(xid);
318
319 cifs_put_tlink(tlink);
320
321 mnt = ERR_PTR(-ENOENT);
322 for (i = 0; i < num_referrals; i++) {
323 int len;
324 dump_referral(referrals + i);
325 /* connect to a node */
326 len = strlen(referrals[i].node_name);
327 if (len < 2) {
328 cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
329 __func__, referrals[i].node_name);
330 mnt = ERR_PTR(-EINVAL);
331 break;
332 }
333 mnt = cifs_dfs_do_refmount(cifs_sb,
334 full_path, referrals + i);
335 cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
336 __func__, referrals[i].node_name, mnt);
337 if (!IS_ERR(mnt))
338 goto success;
339 }
340
341 /* no valid submounts were found; return error from get_dfs_path() by
342 * preference */
343 if (rc != 0)
344 mnt = ERR_PTR(rc);
345
346success:
347 free_dfs_info_array(referrals, num_referrals);
348free_full_path:
349 kfree(full_path);
350cdda_exit:
351 cifs_dbg(FYI, "leaving %s\n" , __func__);
352 return mnt;
353}
354
355/*
356 * Attempt to automount the referral
357 */
358struct vfsmount *cifs_dfs_d_automount(struct path *path)
359{
360 struct vfsmount *newmnt;
361
362 cifs_dbg(FYI, "in %s\n", __func__);
363
364 newmnt = cifs_dfs_do_automount(path->dentry);
365 if (IS_ERR(newmnt)) {
366 cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
367 return newmnt;
368 }
369
370 mntget(newmnt); /* prevent immediate expiration */
371 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
372 schedule_delayed_work(&cifs_dfs_automount_task,
373 cifs_dfs_mountpoint_expiry_timeout);
374 cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
375 return newmnt;
376}
377
378const struct inode_operations cifs_dfs_referral_inode_operations = {
379};
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Contains the CIFS DFS referral mounting routines used for handling
4 * traversal via DFS junction point
5 *
6 * Copyright (c) 2007 Igor Mammedov
7 * Copyright (C) International Business Machines Corp., 2008
8 * Author(s): Igor Mammedov (niallain@gmail.com)
9 * Steve French (sfrench@us.ibm.com)
10 */
11
12#include <linux/dcache.h>
13#include <linux/mount.h>
14#include <linux/namei.h>
15#include <linux/slab.h>
16#include <linux/vfs.h>
17#include <linux/fs.h>
18#include <linux/inet.h>
19#include "cifsglob.h"
20#include "cifsproto.h"
21#include "cifsfs.h"
22#include "dns_resolve.h"
23#include "cifs_debug.h"
24#include "cifs_unicode.h"
25#include "dfs_cache.h"
26
27static LIST_HEAD(cifs_dfs_automount_list);
28
29static void cifs_dfs_expire_automounts(struct work_struct *work);
30static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
31 cifs_dfs_expire_automounts);
32static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
33
34static void cifs_dfs_expire_automounts(struct work_struct *work)
35{
36 struct list_head *list = &cifs_dfs_automount_list;
37
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);
42}
43
44void cifs_dfs_release_automount_timer(void)
45{
46 BUG_ON(!list_empty(&cifs_dfs_automount_list));
47 cancel_delayed_work_sync(&cifs_dfs_automount_task);
48}
49
50/**
51 * cifs_build_devname - build a devicename from a UNC and optional prepath
52 * @nodename: pointer to UNC string
53 * @prepath: pointer to prefixpath (or NULL if there isn't one)
54 *
55 * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
56 * big enough to hold the final thing. Copy the UNC from the nodename, and
57 * concatenate the prepath onto the end of it if there is one.
58 *
59 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
60 * for freeing the returned string.
61 */
62static char *
63cifs_build_devname(char *nodename, const char *prepath)
64{
65 size_t pplen;
66 size_t unclen;
67 char *dev;
68 char *pos;
69
70 /* skip over any preceding delimiters */
71 nodename += strspn(nodename, "\\");
72 if (!*nodename)
73 return ERR_PTR(-EINVAL);
74
75 /* get length of UNC and set pos to last char */
76 unclen = strlen(nodename);
77 pos = nodename + unclen - 1;
78
79 /* trim off any trailing delimiters */
80 while (*pos == '\\') {
81 --pos;
82 --unclen;
83 }
84
85 /* allocate a buffer:
86 * +2 for preceding "//"
87 * +1 for delimiter between UNC and prepath
88 * +1 for trailing NULL
89 */
90 pplen = prepath ? strlen(prepath) : 0;
91 dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
92 if (!dev)
93 return ERR_PTR(-ENOMEM);
94
95 pos = dev;
96 /* add the initial "//" */
97 *pos = '/';
98 ++pos;
99 *pos = '/';
100 ++pos;
101
102 /* copy in the UNC portion from referral */
103 memcpy(pos, nodename, unclen);
104 pos += unclen;
105
106 /* copy the prefixpath remainder (if there is one) */
107 if (pplen) {
108 *pos = '/';
109 ++pos;
110 memcpy(pos, prepath, pplen);
111 pos += pplen;
112 }
113
114 /* NULL terminator */
115 *pos = '\0';
116
117 convert_delimiter(dev, '/');
118 return dev;
119}
120
121
122/**
123 * cifs_compose_mount_options - creates mount options for referral
124 * @sb_mountdata: parent/root DFS mount options (template)
125 * @fullpath: full path in UNC format
126 * @ref: optional server's referral
127 * @devname: optional pointer for saving device name
128 *
129 * creates mount options for submount based on template options sb_mountdata
130 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
131 *
132 * Returns: pointer to new mount options or ERR_PTR.
133 * Caller is responsible for freeing returned value if it is not error.
134 */
135char *cifs_compose_mount_options(const char *sb_mountdata,
136 const char *fullpath,
137 const struct dfs_info3_param *ref,
138 char **devname)
139{
140 int rc;
141 char *name;
142 char *mountdata = NULL;
143 const char *prepath = NULL;
144 int md_len;
145 char *tkn_e;
146 char *srvIP = NULL;
147 char sep = ',';
148 int off, noff;
149
150 if (sb_mountdata == NULL)
151 return ERR_PTR(-EINVAL);
152
153 if (ref) {
154 if (strlen(fullpath) - ref->path_consumed) {
155 prepath = fullpath + ref->path_consumed;
156 /* skip initial delimiter */
157 if (*prepath == '/' || *prepath == '\\')
158 prepath++;
159 }
160
161 name = cifs_build_devname(ref->node_name, prepath);
162 if (IS_ERR(name)) {
163 rc = PTR_ERR(name);
164 name = NULL;
165 goto compose_mount_options_err;
166 }
167 } else {
168 name = cifs_build_devname((char *)fullpath, NULL);
169 if (IS_ERR(name)) {
170 rc = PTR_ERR(name);
171 name = NULL;
172 goto compose_mount_options_err;
173 }
174 }
175
176 rc = dns_resolve_server_name_to_ip(name, &srvIP);
177 if (rc < 0) {
178 cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
179 __func__, name, rc);
180 goto compose_mount_options_err;
181 }
182
183 /*
184 * In most cases, we'll be building a shorter string than the original,
185 * but we do have to assume that the address in the ip= option may be
186 * much longer than the original. Add the max length of an address
187 * string to the length of the original string to allow for worst case.
188 */
189 md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
190 mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
191 if (mountdata == NULL) {
192 rc = -ENOMEM;
193 goto compose_mount_options_err;
194 }
195
196 /* copy all options except of unc,ip,prefixpath */
197 off = 0;
198 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
199 sep = sb_mountdata[4];
200 strncpy(mountdata, sb_mountdata, 5);
201 off += 5;
202 }
203
204 do {
205 tkn_e = strchr(sb_mountdata + off, sep);
206 if (tkn_e == NULL)
207 noff = strlen(sb_mountdata + off);
208 else
209 noff = tkn_e - (sb_mountdata + off) + 1;
210
211 if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
212 off += noff;
213 continue;
214 }
215 if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
216 off += noff;
217 continue;
218 }
219 if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
220 off += noff;
221 continue;
222 }
223 strncat(mountdata, sb_mountdata + off, noff);
224 off += noff;
225 } while (tkn_e);
226 strcat(mountdata, sb_mountdata + off);
227 mountdata[md_len] = '\0';
228
229 /* copy new IP and ref share name */
230 if (mountdata[strlen(mountdata) - 1] != sep)
231 strncat(mountdata, &sep, 1);
232 strcat(mountdata, "ip=");
233 strcat(mountdata, srvIP);
234
235 if (devname)
236 *devname = name;
237 else
238 kfree(name);
239
240 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
241 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
242
243compose_mount_options_out:
244 kfree(srvIP);
245 return mountdata;
246
247compose_mount_options_err:
248 kfree(mountdata);
249 mountdata = ERR_PTR(rc);
250 kfree(name);
251 goto compose_mount_options_out;
252}
253
254/**
255 * cifs_dfs_do_mount - mounts specified path using DFS full path
256 *
257 * Always pass down @fullpath to smb3_do_mount() so we can use the root server
258 * to perform failover in case we failed to connect to the first target in the
259 * referral.
260 *
261 * @cifs_sb: parent/root superblock
262 * @fullpath: full path in UNC format
263 */
264static struct vfsmount *cifs_dfs_do_mount(struct dentry *mntpt,
265 struct cifs_sb_info *cifs_sb,
266 const char *fullpath)
267{
268 struct vfsmount *mnt;
269 char *mountdata;
270 char *devname;
271
272 devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
273 if (!devname)
274 return ERR_PTR(-ENOMEM);
275
276 convert_delimiter(devname, '/');
277
278 /* strip first '\' from fullpath */
279 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
280 fullpath + 1, NULL, NULL);
281 if (IS_ERR(mountdata)) {
282 kfree(devname);
283 return (struct vfsmount *)mountdata;
284 }
285
286 mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
287 kfree(mountdata);
288 kfree(devname);
289 return mnt;
290}
291
292/*
293 * Create a vfsmount that we can automount
294 */
295static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
296{
297 struct cifs_sb_info *cifs_sb;
298 struct cifs_ses *ses;
299 struct cifs_tcon *tcon;
300 char *full_path, *root_path;
301 unsigned int xid;
302 int rc;
303 struct vfsmount *mnt;
304
305 cifs_dbg(FYI, "in %s\n", __func__);
306 BUG_ON(IS_ROOT(mntpt));
307
308 /*
309 * The MSDFS spec states that paths in DFS referral requests and
310 * responses must be prefixed by a single '\' character instead of
311 * the double backslashes usually used in the UNC. This function
312 * gives us the latter, so we must adjust the result.
313 */
314 mnt = ERR_PTR(-ENOMEM);
315
316 cifs_sb = CIFS_SB(mntpt->d_sb);
317 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
318 mnt = ERR_PTR(-EREMOTE);
319 goto cdda_exit;
320 }
321
322 /* always use tree name prefix */
323 full_path = build_path_from_dentry_optional_prefix(mntpt, true);
324 if (full_path == NULL)
325 goto cdda_exit;
326
327 convert_delimiter(full_path, '\\');
328
329 cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
330
331 if (!cifs_sb_master_tlink(cifs_sb)) {
332 cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
333 goto free_full_path;
334 }
335
336 tcon = cifs_sb_master_tcon(cifs_sb);
337 if (!tcon) {
338 cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
339 goto free_full_path;
340 }
341
342 root_path = kstrdup(tcon->treeName, GFP_KERNEL);
343 if (!root_path) {
344 mnt = ERR_PTR(-ENOMEM);
345 goto free_full_path;
346 }
347 cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
348
349 ses = tcon->ses;
350 xid = get_xid();
351
352 /*
353 * If DFS root has been expired, then unconditionally fetch it again to
354 * refresh DFS referral cache.
355 */
356 rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
357 root_path + 1, NULL, NULL);
358 if (!rc) {
359 rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
360 cifs_remap(cifs_sb), full_path + 1,
361 NULL, NULL);
362 }
363
364 free_xid(xid);
365
366 if (rc) {
367 mnt = ERR_PTR(rc);
368 goto free_root_path;
369 }
370 /*
371 * OK - we were able to get and cache a referral for @full_path.
372 *
373 * Now, pass it down to cifs_mount() and it will retry every available
374 * node server in case of failures - no need to do it here.
375 */
376 mnt = cifs_dfs_do_mount(mntpt, cifs_sb, full_path);
377 cifs_dbg(FYI, "%s: cifs_dfs_do_mount:%s , mnt:%p\n", __func__,
378 full_path + 1, mnt);
379
380free_root_path:
381 kfree(root_path);
382free_full_path:
383 kfree(full_path);
384cdda_exit:
385 cifs_dbg(FYI, "leaving %s\n" , __func__);
386 return mnt;
387}
388
389/*
390 * Attempt to automount the referral
391 */
392struct vfsmount *cifs_dfs_d_automount(struct path *path)
393{
394 struct vfsmount *newmnt;
395
396 cifs_dbg(FYI, "in %s\n", __func__);
397
398 newmnt = cifs_dfs_do_automount(path->dentry);
399 if (IS_ERR(newmnt)) {
400 cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
401 return newmnt;
402 }
403
404 mntget(newmnt); /* prevent immediate expiration */
405 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
406 schedule_delayed_work(&cifs_dfs_automount_task,
407 cifs_dfs_mountpoint_expiry_timeout);
408 cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
409 return newmnt;
410}
411
412const struct inode_operations cifs_dfs_referral_inode_operations = {
413};