Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6
[linux-2.6] / fs / cifs / cifs_dfs_ref.c
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/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
26 static LIST_HEAD(cifs_dfs_automount_list);
27
28 static void cifs_dfs_expire_automounts(struct work_struct *work);
29 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
30                             cifs_dfs_expire_automounts);
31 static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
32
33 static void cifs_dfs_expire_automounts(struct work_struct *work)
34 {
35         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
43 void 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();
48 }
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  */
61 static 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",
88                         __func__, node_name));
89                 kfree(UNC);
90                 return NULL;
91         }
92
93         /* find sharename end */
94         pSep++;
95         pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
96         if (pSep) {
97                 /* trim path up to sharename end
98                  * now we have share name in UNC */
99                 *pSep = 0;
100         }
101
102         return UNC;
103 }
104
105
106 /**
107  * compose_mount_options        -       creates mount options for refferral
108  * @sb_mountdata:       parent/root DFS mount options (template)
109  * @ref_unc:            refferral server UNC
110  * @devname:            pointer for saving device name
111  *
112  * creates mount options for submount based on template options sb_mountdata
113  * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
114  *
115  * Returns: pointer to new mount options or ERR_PTR.
116  * Caller is responcible for freeing retunrned value if it is not error.
117  */
118 static char *compose_mount_options(const char *sb_mountdata,
119                                    const char *ref_unc,
120                                    char **devname)
121 {
122         int rc;
123         char *mountdata;
124         int md_len;
125         char *tkn_e;
126         char *srvIP = NULL;
127         char sep = ',';
128         int off, noff;
129
130         if (sb_mountdata == NULL)
131                 return ERR_PTR(-EINVAL);
132
133         *devname = cifs_get_share_name(ref_unc);
134         rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
135         if (rc != 0) {
136                 cERROR(1, ("%s: Failed to resolve server part of %s to IP",
137                           __func__, *devname));
138                 mountdata = ERR_PTR(rc);
139                 goto compose_mount_options_out;
140         }
141         md_len = strlen(sb_mountdata) + strlen(srvIP) + strlen(ref_unc) + 3;
142         mountdata = kzalloc(md_len+1, GFP_KERNEL);
143         if (mountdata == NULL) {
144                 mountdata = ERR_PTR(-ENOMEM);
145                 goto compose_mount_options_out;
146         }
147
148         /* copy all options except of unc,ip,prefixpath */
149         off = 0;
150         if (strncmp(sb_mountdata, "sep=", 4) == 0) {
151                         sep = sb_mountdata[4];
152                         strncpy(mountdata, sb_mountdata, 5);
153                         off += 5;
154         }
155         while ((tkn_e = strchr(sb_mountdata+off, sep))) {
156                 noff = (tkn_e - (sb_mountdata+off)) + 1;
157                 if (strnicmp(sb_mountdata+off, "unc=", 4) == 0) {
158                         off += noff;
159                         continue;
160                 }
161                 if (strnicmp(sb_mountdata+off, "ip=", 3) == 0) {
162                         off += noff;
163                         continue;
164                 }
165                 if (strnicmp(sb_mountdata+off, "prefixpath=", 3) == 0) {
166                         off += noff;
167                         continue;
168                 }
169                 strncat(mountdata, sb_mountdata+off, noff);
170                 off += noff;
171         }
172         strcat(mountdata, sb_mountdata+off);
173         mountdata[md_len] = '\0';
174
175         /* copy new IP and ref share name */
176         strcat(mountdata, ",ip=");
177         strcat(mountdata, srvIP);
178         strcat(mountdata, ",unc=");
179         strcat(mountdata, *devname);
180
181         /* find & copy prefixpath */
182         tkn_e = strchr(ref_unc+2, '\\');
183         if (tkn_e) {
184                 tkn_e = strchr(tkn_e+1, '\\');
185                 if (tkn_e) {
186                         strcat(mountdata, ",prefixpath=");
187                         strcat(mountdata, tkn_e+1);
188                 }
189         }
190
191         /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
192         /*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/
193
194 compose_mount_options_out:
195         kfree(srvIP);
196         return mountdata;
197 }
198
199
200 static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
201                 struct dentry *dentry, char *ref_unc)
202 {
203         struct cifs_sb_info *cifs_sb;
204         struct vfsmount *mnt;
205         char *mountdata;
206         char *devname = NULL;
207
208         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
209         mountdata = compose_mount_options(cifs_sb->mountdata,
210                                                 ref_unc, &devname);
211
212         if (IS_ERR(mountdata))
213                 return (struct vfsmount *)mountdata;
214
215         mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
216         kfree(mountdata);
217         kfree(devname);
218         return mnt;
219
220 }
221
222 static char *build_full_dfs_path_from_dentry(struct dentry *dentry)
223 {
224         char *full_path = NULL;
225         char *search_path;
226         char *tmp_path;
227         size_t l_max_len;
228         struct cifs_sb_info *cifs_sb;
229
230         if (dentry->d_inode == NULL)
231                 return NULL;
232
233         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
234
235         if (cifs_sb->tcon == NULL)
236                 return NULL;
237
238         search_path = build_path_from_dentry(dentry);
239         if (search_path == NULL)
240                 return NULL;
241
242         if (cifs_sb->tcon->Flags & SMB_SHARE_IS_IN_DFS) {
243                 int i;
244                 /* we should use full path name for correct working with DFS */
245                 l_max_len = strnlen(cifs_sb->tcon->treeName, MAX_TREE_SIZE+1) +
246                                         strnlen(search_path, MAX_PATHCONF) + 1;
247                 tmp_path = kmalloc(l_max_len, GFP_KERNEL);
248                 if (tmp_path == NULL) {
249                         kfree(search_path);
250                         return NULL;
251                 }
252                 strncpy(tmp_path, cifs_sb->tcon->treeName, l_max_len);
253                 tmp_path[l_max_len-1] = 0;
254                 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
255                         for (i = 0; i < l_max_len; i++) {
256                                 if (tmp_path[i] == '\\')
257                                         tmp_path[i] = '/';
258                         }
259                 strncat(tmp_path, search_path, l_max_len - strlen(tmp_path));
260
261                 full_path = tmp_path;
262                 kfree(search_path);
263         } else {
264                 full_path = search_path;
265         }
266         return full_path;
267 }
268
269 static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
270                                 struct list_head *mntlist)
271 {
272         /* stolen from afs code */
273         int err;
274
275         mntget(newmnt);
276         err = do_add_mount(newmnt, nd, nd->path.mnt->mnt_flags, mntlist);
277         switch (err) {
278         case 0:
279                 path_put(&nd->path);
280                 nd->path.mnt = newmnt;
281                 nd->path.dentry = dget(newmnt->mnt_root);
282                 schedule_delayed_work(&cifs_dfs_automount_task,
283                                       cifs_dfs_mountpoint_expiry_timeout);
284                 break;
285         case -EBUSY:
286                 /* someone else made a mount here whilst we were busy */
287                 while (d_mountpoint(nd->path.dentry) &&
288                        follow_down(&nd->path.mnt, &nd->path.dentry))
289                         ;
290                 err = 0;
291         default:
292                 mntput(newmnt);
293                 break;
294         }
295         return err;
296 }
297
298 static void dump_referral(const struct dfs_info3_param *ref)
299 {
300         cFYI(1, ("DFS: ref path: %s", ref->path_name));
301         cFYI(1, ("DFS: node path: %s", ref->node_name));
302         cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
303         cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
304                                 ref->path_consumed));
305 }
306
307
308 static void*
309 cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
310 {
311         struct dfs_info3_param *referrals = NULL;
312         unsigned int num_referrals = 0;
313         struct cifs_sb_info *cifs_sb;
314         struct cifsSesInfo *ses;
315         char *full_path = NULL;
316         int xid, i;
317         int rc = 0;
318         struct vfsmount *mnt = ERR_PTR(-ENOENT);
319
320         cFYI(1, ("in %s", __func__));
321         BUG_ON(IS_ROOT(dentry));
322
323         xid = GetXid();
324
325         dput(nd->path.dentry);
326         nd->path.dentry = dget(dentry);
327
328         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
329         ses = cifs_sb->tcon->ses;
330
331         if (!ses) {
332                 rc = -EINVAL;
333                 goto out_err;
334         }
335
336         full_path = build_full_dfs_path_from_dentry(dentry);
337         if (full_path == NULL) {
338                 rc = -ENOMEM;
339                 goto out_err;
340         }
341
342         rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls,
343                 &num_referrals, &referrals,
344                 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
345
346         for (i = 0; i < num_referrals; i++) {
347                 dump_referral(referrals+i);
348                 /* connect to a storage node */
349                 if (referrals[i].flags & DFSREF_STORAGE_SERVER) {
350                         int len;
351                         len = strlen(referrals[i].node_name);
352                         if (len < 2) {
353                                 cERROR(1, ("%s: Net Address path too short: %s",
354                                         __func__, referrals[i].node_name));
355                                 rc = -EINVAL;
356                                 goto out_err;
357                         }
358                         mnt = cifs_dfs_do_refmount(nd->path.mnt,
359                                                 nd->path.dentry,
360                                                 referrals[i].node_name);
361                         cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p",
362                                          __func__,
363                                         referrals[i].node_name, mnt));
364
365                         /* complete mount procedure if we accured submount */
366                         if (!IS_ERR(mnt))
367                                 break;
368                 }
369         }
370
371         /* we need it cause for() above could exit without valid submount */
372         rc = PTR_ERR(mnt);
373         if (IS_ERR(mnt))
374                 goto out_err;
375
376         nd->path.mnt->mnt_flags |= MNT_SHRINKABLE;
377         rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
378
379 out:
380         FreeXid(xid);
381         free_dfs_info_array(referrals, num_referrals);
382         kfree(full_path);
383         cFYI(1, ("leaving %s" , __func__));
384         return ERR_PTR(rc);
385 out_err:
386         path_put(&nd->path);
387         goto out;
388 }
389
390 struct inode_operations cifs_dfs_referral_inode_operations = {
391         .follow_link = cifs_dfs_follow_mountpoint,
392 };
393