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
28 static LIST_HEAD(cifs_dfs_automount_list);
29
30 static void cifs_dfs_expire_automounts(struct work_struct *work);
31 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
32 cifs_dfs_expire_automounts);
33 static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
34
cifs_dfs_expire_automounts(struct work_struct * work)35 static 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
cifs_dfs_release_automount_timer(void)45 void 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_get_share_name - extracts share name from UNC
53 * @node_name: pointer to UNC string
54 *
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 beginning of DFS node refferal
58 * if necessary.
59 * Returns pointer to share name on success or ERR_PTR on error.
60 * Caller is responsible for freeing returned string.
61 */
cifs_get_share_name(const char * node_name)62 static char *cifs_get_share_name(const char *node_name)
63 {
64 int len;
65 char *UNC;
66 char *pSep;
67
68 len = strlen(node_name);
69 UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
70 GFP_KERNEL);
71 if (!UNC)
72 return ERR_PTR(-ENOMEM);
73
74 /* get share name and server name */
75 if (node_name[1] != '\\') {
76 UNC[0] = '\\';
77 strncpy(UNC+1, node_name, len);
78 len++;
79 UNC[len] = 0;
80 } else {
81 strncpy(UNC, node_name, len);
82 UNC[len] = 0;
83 }
84
85 /* find server name end */
86 pSep = memchr(UNC+2, '\\', len-2);
87 if (!pSep) {
88 cERROR(1, "%s: no server name end in node name: %s",
89 __func__, node_name);
90 kfree(UNC);
91 return ERR_PTR(-EINVAL);
92 }
93
94 /* find sharename end */
95 pSep++;
96 pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
97 if (pSep) {
98 /* trim path up to sharename end
99 * now we have share name in UNC */
100 *pSep = 0;
101 }
102
103 return UNC;
104 }
105
106
107 /**
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
113 *
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.
116 *
117 * Returns: pointer to new mount options or ERR_PTR.
118 * Caller is responcible for freeing retunrned value if it is not error.
119 */
cifs_compose_mount_options(const char * sb_mountdata,const char * fullpath,const struct dfs_info3_param * ref,char ** devname)120 char *cifs_compose_mount_options(const char *sb_mountdata,
121 const char *fullpath,
122 const struct dfs_info3_param *ref,
123 char **devname)
124 {
125 int rc;
126 char *mountdata = NULL;
127 int md_len;
128 char *tkn_e;
129 char *srvIP = NULL;
130 char sep = ',';
131 int off, noff;
132
133 if (sb_mountdata == NULL)
134 return ERR_PTR(-EINVAL);
135
136 *devname = cifs_get_share_name(ref->node_name);
137 if (IS_ERR(*devname)) {
138 rc = PTR_ERR(*devname);
139 *devname = NULL;
140 goto compose_mount_options_err;
141 }
142
143 rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
144 if (rc < 0) {
145 cFYI(1, "%s: Failed to resolve server part of %s to IP: %d",
146 __func__, *devname, rc);
147 goto compose_mount_options_err;
148 }
149
150 /* md_len = strlen(...) + 12 for 'sep+prefixpath='
151 * assuming that we have 'unc=' and 'ip=' in
152 * the original sb_mountdata
153 */
154 md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12 +
155 INET6_ADDRSTRLEN;
156 mountdata = kzalloc(md_len+1, GFP_KERNEL);
157 if (mountdata == NULL) {
158 rc = -ENOMEM;
159 goto compose_mount_options_err;
160 }
161
162 /* copy all options except of unc,ip,prefixpath */
163 off = 0;
164 if (strncmp(sb_mountdata, "sep=", 4) == 0) {
165 sep = sb_mountdata[4];
166 strncpy(mountdata, sb_mountdata, 5);
167 off += 5;
168 }
169
170 do {
171 tkn_e = strchr(sb_mountdata + off, sep);
172 if (tkn_e == NULL)
173 noff = strlen(sb_mountdata + off);
174 else
175 noff = tkn_e - (sb_mountdata + off) + 1;
176
177 if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
178 off += noff;
179 continue;
180 }
181 if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
182 off += noff;
183 continue;
184 }
185 if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
186 off += noff;
187 continue;
188 }
189 strncat(mountdata, sb_mountdata + off, noff);
190 off += noff;
191 } while (tkn_e);
192 strcat(mountdata, sb_mountdata + off);
193 mountdata[md_len] = '\0';
194
195 /* copy new IP and ref share name */
196 if (mountdata[strlen(mountdata) - 1] != sep)
197 strncat(mountdata, &sep, 1);
198 strcat(mountdata, "ip=");
199 strcat(mountdata, srvIP);
200 strncat(mountdata, &sep, 1);
201 strcat(mountdata, "unc=");
202 strcat(mountdata, *devname);
203
204 /* find & copy prefixpath */
205 tkn_e = strchr(ref->node_name + 2, '\\');
206 if (tkn_e == NULL) {
207 /* invalid unc, missing share name*/
208 rc = -EINVAL;
209 goto compose_mount_options_err;
210 }
211
212 tkn_e = strchr(tkn_e + 1, '\\');
213 if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
214 strncat(mountdata, &sep, 1);
215 strcat(mountdata, "prefixpath=");
216 if (tkn_e)
217 strcat(mountdata, tkn_e + 1);
218 strcat(mountdata, fullpath + ref->path_consumed);
219 }
220
221 /*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/
222 /*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/
223
224 compose_mount_options_out:
225 kfree(srvIP);
226 return mountdata;
227
228 compose_mount_options_err:
229 kfree(mountdata);
230 mountdata = ERR_PTR(rc);
231 kfree(*devname);
232 *devname = NULL;
233 goto compose_mount_options_out;
234 }
235
236 /**
237 * cifs_dfs_do_refmount - mounts specified path using provided refferal
238 * @cifs_sb: parent/root superblock
239 * @fullpath: full path in UNC format
240 * @ref: server's referral
241 */
cifs_dfs_do_refmount(struct cifs_sb_info * cifs_sb,const char * fullpath,const struct dfs_info3_param * ref)242 static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
243 const char *fullpath, const struct dfs_info3_param *ref)
244 {
245 struct vfsmount *mnt;
246 char *mountdata;
247 char *devname = NULL;
248
249 /* strip first '\' from fullpath */
250 mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
251 fullpath + 1, ref, &devname);
252
253 if (IS_ERR(mountdata))
254 return (struct vfsmount *)mountdata;
255
256 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
257 kfree(mountdata);
258 kfree(devname);
259 return mnt;
260
261 }
262
dump_referral(const struct dfs_info3_param * ref)263 static void dump_referral(const struct dfs_info3_param *ref)
264 {
265 cFYI(1, "DFS: ref path: %s", ref->path_name);
266 cFYI(1, "DFS: node path: %s", ref->node_name);
267 cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type);
268 cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
269 ref->path_consumed);
270 }
271
272 /*
273 * Create a vfsmount that we can automount
274 */
cifs_dfs_do_automount(struct dentry * mntpt)275 static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
276 {
277 struct dfs_info3_param *referrals = NULL;
278 unsigned int num_referrals = 0;
279 struct cifs_sb_info *cifs_sb;
280 struct cifs_ses *ses;
281 char *full_path;
282 int xid, i;
283 int rc;
284 struct vfsmount *mnt;
285 struct tcon_link *tlink;
286
287 cFYI(1, "in %s", __func__);
288 BUG_ON(IS_ROOT(mntpt));
289
290 /*
291 * The MSDFS spec states that paths in DFS referral requests and
292 * responses must be prefixed by a single '\' character instead of
293 * the double backslashes usually used in the UNC. This function
294 * gives us the latter, so we must adjust the result.
295 */
296 mnt = ERR_PTR(-ENOMEM);
297 full_path = build_path_from_dentry(mntpt);
298 if (full_path == NULL)
299 goto cdda_exit;
300
301 cifs_sb = CIFS_SB(mntpt->d_inode->i_sb);
302 tlink = cifs_sb_tlink(cifs_sb);
303 if (IS_ERR(tlink)) {
304 mnt = ERR_CAST(tlink);
305 goto free_full_path;
306 }
307 ses = tlink_tcon(tlink)->ses;
308
309 xid = GetXid();
310 rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
311 &num_referrals, &referrals,
312 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
313 FreeXid(xid);
314
315 cifs_put_tlink(tlink);
316
317 mnt = ERR_PTR(-ENOENT);
318 for (i = 0; i < num_referrals; i++) {
319 int len;
320 dump_referral(referrals + i);
321 /* connect to a node */
322 len = strlen(referrals[i].node_name);
323 if (len < 2) {
324 cERROR(1, "%s: Net Address path too short: %s",
325 __func__, referrals[i].node_name);
326 mnt = ERR_PTR(-EINVAL);
327 break;
328 }
329 mnt = cifs_dfs_do_refmount(cifs_sb,
330 full_path, referrals + i);
331 cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
332 referrals[i].node_name, mnt);
333 if (!IS_ERR(mnt))
334 goto success;
335 }
336
337 /* no valid submounts were found; return error from get_dfs_path() by
338 * preference */
339 if (rc != 0)
340 mnt = ERR_PTR(rc);
341
342 success:
343 free_dfs_info_array(referrals, num_referrals);
344 free_full_path:
345 kfree(full_path);
346 cdda_exit:
347 cFYI(1, "leaving %s" , __func__);
348 return mnt;
349 }
350
351 /*
352 * Attempt to automount the referral
353 */
cifs_dfs_d_automount(struct path * path)354 struct vfsmount *cifs_dfs_d_automount(struct path *path)
355 {
356 struct vfsmount *newmnt;
357
358 cFYI(1, "in %s", __func__);
359
360 newmnt = cifs_dfs_do_automount(path->dentry);
361 if (IS_ERR(newmnt)) {
362 cFYI(1, "leaving %s [automount failed]" , __func__);
363 return newmnt;
364 }
365
366 mntget(newmnt); /* prevent immediate expiration */
367 mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
368 schedule_delayed_work(&cifs_dfs_automount_task,
369 cifs_dfs_mountpoint_expiry_timeout);
370 cFYI(1, "leaving %s [ok]" , __func__);
371 return newmnt;
372 }
373
374 const struct inode_operations cifs_dfs_referral_inode_operations = {
375 };
376