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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#include "fs_context.h"
27
28static LIST_HEAD(cifs_dfs_automount_list);
29
30static void cifs_dfs_expire_automounts(struct work_struct *work);
31static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
32 cifs_dfs_expire_automounts);
33static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
34
35static void cifs_dfs_expire_automounts(struct work_struct *work)
36{
37 struct list_head *list = &cifs_dfs_automount_list;
38
39 mark_mounts_for_expiry(list);
40 if (!list_empty(list))
41 schedule_delayed_work(&cifs_dfs_automount_task,
42 cifs_dfs_mountpoint_expiry_timeout);
43}
44
45void cifs_dfs_release_automount_timer(void)
46{
47 BUG_ON(!list_empty(&cifs_dfs_automount_list));
48 cancel_delayed_work_sync(&cifs_dfs_automount_task);
49}
50
51/**
52 * cifs_build_devname - build a devicename from a UNC and optional prepath
53 * @nodename: pointer to UNC string
54 * @prepath: pointer to prefixpath (or NULL if there isn't one)
55 *
56 * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
57 * big enough to hold the final thing. Copy the UNC from the nodename, and
58 * concatenate the prepath onto the end of it if there is one.
59 *
60 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
61 * for freeing the returned string.
62 */
63static char *
64cifs_build_devname(char *nodename, const char *prepath)
65{
66 size_t pplen;
67 size_t unclen;
68 char *dev;
69 char *pos;
70
71 /* skip over any preceding delimiters */
72 nodename += strspn(nodename, "\\");
73 if (!*nodename)
74 return ERR_PTR(-EINVAL);
75
76 /* get length of UNC and set pos to last char */
77 unclen = strlen(nodename);
78 pos = nodename + unclen - 1;
79
80 /* trim off any trailing delimiters */
81 while (*pos == '\\') {
82 --pos;
83 --unclen;
84 }
85
86 /* allocate a buffer:
87 * +2 for preceding "//"
88 * +1 for delimiter between UNC and prepath
89 * +1 for trailing NULL
90 */
91 pplen = prepath ? strlen(prepath) : 0;
92 dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
93 if (!dev)
94 return ERR_PTR(-ENOMEM);
95
96 pos = dev;
97 /* add the initial "//" */
98 *pos = '/';
99 ++pos;
100 *pos = '/';
101 ++pos;
102
103 /* copy in the UNC portion from referral */
104 memcpy(pos, nodename, unclen);
105 pos += unclen;
106
107 /* copy the prefixpath remainder (if there is one) */
108 if (pplen) {
109 *pos = '/';
110 ++pos;
111 memcpy(pos, prepath, pplen);
112 pos += pplen;
113 }
114
115 /* NULL terminator */
116 *pos = '\0';
117
118 convert_delimiter(dev, '/');
119 return dev;
120}
121
122
123/**
124 * cifs_compose_mount_options - creates mount options for referral
125 * @sb_mountdata: parent/root DFS mount options (template)
126 * @fullpath: full path in UNC format
127 * @ref: optional server's referral
128 * @devname: return the built cifs device name if passed pointer not NULL
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 (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0))
155 return ERR_PTR(-EINVAL);
156
157 if (strlen(fullpath) - ref->path_consumed) {
158 prepath = fullpath + ref->path_consumed;
159 /* skip initial delimiter */
160 if (*prepath == '/' || *prepath == '\\')
161 prepath++;
162 }
163
164 name = cifs_build_devname(ref->node_name, prepath);
165 if (IS_ERR(name)) {
166 rc = PTR_ERR(name);
167 name = NULL;
168 goto compose_mount_options_err;
169 }
170 } else {
171 name = cifs_build_devname((char *)fullpath, NULL);
172 if (IS_ERR(name)) {
173 rc = PTR_ERR(name);
174 name = NULL;
175 goto compose_mount_options_err;
176 }
177 }
178
179 rc = dns_resolve_server_name_to_ip(name, &srvIP, NULL);
180 if (rc < 0) {
181 cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
182 __func__, name, rc);
183 goto compose_mount_options_err;
184 }
185
186 /*
187 * In most cases, we'll be building a shorter string than the original,
188 * but we do have to assume that the address in the ip= option may be
189 * much longer than the original. Add the max length of an address
190 * string to the length of the original string to allow for worst case.
191 */
192 md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
193 mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
194 if (mountdata == NULL) {
195 rc = -ENOMEM;
196 goto compose_mount_options_err;
197 }
198
199 /* copy all options except of unc,ip,prefixpath */
200 off = 0;
201 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
202 sep = sb_mountdata[4];
203 strncpy(mountdata, sb_mountdata, 5);
204 off += 5;
205 }
206
207 do {
208 tkn_e = strchr(sb_mountdata + off, sep);
209 if (tkn_e == NULL)
210 noff = strlen(sb_mountdata + off);
211 else
212 noff = tkn_e - (sb_mountdata + off) + 1;
213
214 if (strncasecmp(sb_mountdata + off, "cruid=", 6) == 0) {
215 off += noff;
216 continue;
217 }
218 if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
219 off += noff;
220 continue;
221 }
222 if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
223 off += noff;
224 continue;
225 }
226 if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
227 off += noff;
228 continue;
229 }
230 strncat(mountdata, sb_mountdata + off, noff);
231 off += noff;
232 } while (tkn_e);
233 strcat(mountdata, sb_mountdata + off);
234 mountdata[md_len] = '\0';
235
236 /* copy new IP and ref share name */
237 if (mountdata[strlen(mountdata) - 1] != sep)
238 strncat(mountdata, &sep, 1);
239 strcat(mountdata, "ip=");
240 strcat(mountdata, srvIP);
241
242 if (devname)
243 *devname = name;
244 else
245 kfree(name);
246
247 /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
248 /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
249
250compose_mount_options_out:
251 kfree(srvIP);
252 return mountdata;
253
254compose_mount_options_err:
255 kfree(mountdata);
256 mountdata = ERR_PTR(rc);
257 kfree(name);
258 goto compose_mount_options_out;
259}
260
261/**
262 * cifs_dfs_do_mount - mounts specified path using DFS full path
263 *
264 * Always pass down @fullpath to smb3_do_mount() so we can use the root server
265 * to perform failover in case we failed to connect to the first target in the
266 * referral.
267 *
268 * @mntpt: directory entry for the path we are trying to automount
269 * @cifs_sb: parent/root superblock
270 * @fullpath: full path in UNC format
271 */
272static struct vfsmount *cifs_dfs_do_mount(struct dentry *mntpt,
273 struct cifs_sb_info *cifs_sb,
274 const char *fullpath)
275{
276 struct vfsmount *mnt;
277 char *mountdata;
278 char *devname;
279
280 devname = kstrdup(fullpath, GFP_KERNEL);
281 if (!devname)
282 return ERR_PTR(-ENOMEM);
283
284 convert_delimiter(devname, '/');
285
286 /* TODO: change to call fs_context_for_mount(), fill in context directly, call fc_mount */
287
288 /* See afs_mntpt_do_automount in fs/afs/mntpt.c for an example */
289
290 /* strip first '\' from fullpath */
291 mountdata = cifs_compose_mount_options(cifs_sb->ctx->mount_options,
292 fullpath + 1, NULL, NULL);
293 if (IS_ERR(mountdata)) {
294 kfree(devname);
295 return (struct vfsmount *)mountdata;
296 }
297
298 mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
299 kfree(mountdata);
300 kfree(devname);
301 return mnt;
302}
303
304/*
305 * Create a vfsmount that we can automount
306 */
307static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
308{
309 struct cifs_sb_info *cifs_sb;
310 struct cifs_ses *ses;
311 struct cifs_tcon *tcon;
312 void *page;
313 char *full_path, *root_path;
314 unsigned int xid;
315 int rc;
316 struct vfsmount *mnt;
317
318 cifs_dbg(FYI, "in %s\n", __func__);
319 BUG_ON(IS_ROOT(mntpt));
320
321 /*
322 * The MSDFS spec states that paths in DFS referral requests and
323 * responses must be prefixed by a single '\' character instead of
324 * the double backslashes usually used in the UNC. This function
325 * gives us the latter, so we must adjust the result.
326 */
327 mnt = ERR_PTR(-ENOMEM);
328
329 cifs_sb = CIFS_SB(mntpt->d_sb);
330 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
331 mnt = ERR_PTR(-EREMOTE);
332 goto cdda_exit;
333 }
334
335 page = alloc_dentry_path();
336 /* always use tree name prefix */
337 full_path = build_path_from_dentry_optional_prefix(mntpt, page, true);
338 if (IS_ERR(full_path)) {
339 mnt = ERR_CAST(full_path);
340 goto free_full_path;
341 }
342
343 convert_delimiter(full_path, '\\');
344
345 cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
346
347 if (!cifs_sb_master_tlink(cifs_sb)) {
348 cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
349 goto free_full_path;
350 }
351
352 tcon = cifs_sb_master_tcon(cifs_sb);
353 if (!tcon) {
354 cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
355 goto free_full_path;
356 }
357
358 root_path = kstrdup(tcon->treeName, GFP_KERNEL);
359 if (!root_path) {
360 mnt = ERR_PTR(-ENOMEM);
361 goto free_full_path;
362 }
363 cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
364
365 ses = tcon->ses;
366 xid = get_xid();
367
368 /*
369 * If DFS root has been expired, then unconditionally fetch it again to
370 * refresh DFS referral cache.
371 */
372 rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
373 root_path + 1, NULL, NULL);
374 if (!rc) {
375 rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
376 cifs_remap(cifs_sb), full_path + 1,
377 NULL, NULL);
378 }
379
380 free_xid(xid);
381
382 if (rc) {
383 mnt = ERR_PTR(rc);
384 goto free_root_path;
385 }
386 /*
387 * OK - we were able to get and cache a referral for @full_path.
388 *
389 * Now, pass it down to cifs_mount() and it will retry every available
390 * node server in case of failures - no need to do it here.
391 */
392 mnt = cifs_dfs_do_mount(mntpt, cifs_sb, full_path);
393 cifs_dbg(FYI, "%s: cifs_dfs_do_mount:%s , mnt:%p\n", __func__,
394 full_path + 1, mnt);
395
396free_root_path:
397 kfree(root_path);
398free_full_path:
399 free_dentry_path(page);
400cdda_exit:
401 cifs_dbg(FYI, "leaving %s\n" , __func__);
402 return mnt;
403}
404
405/*
406 * Attempt to automount the referral
407 */
408struct vfsmount *cifs_dfs_d_automount(struct path *path)
409{
410 struct vfsmount *newmnt;
411
412 cifs_dbg(FYI, "in %s\n", __func__);
413
414 newmnt = cifs_dfs_do_automount(path->dentry);
415 if (IS_ERR(newmnt)) {
416 cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
417 return newmnt;
418 }
419
420 mntget(newmnt); /* prevent immediate expiration */
421 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
422 schedule_delayed_work(&cifs_dfs_automount_task,
423 cifs_dfs_mountpoint_expiry_timeout);
424 cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
425 return newmnt;
426}
427
428const struct inode_operations cifs_dfs_referral_inode_operations = {
429};