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[linux-2.6.git] / 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  *   Author(s): Igor Mammedov (niallain@gmail.com)
7  *
8  *   This program is free software; you can redistribute it and/or
9  *   modify it under the terms of the GNU General Public License
10  *   as published by the Free Software Foundation; either version
11  *   2 of the License, or (at your option) any later version.
12  */
13
14 #include <linux/dcache.h>
15 #include <linux/mount.h>
16 #include <linux/namei.h>
17 #include <linux/vfs.h>
18 #include <linux/fs.h>
19 #include "cifsglob.h"
20 #include "cifsproto.h"
21 #include "cifsfs.h"
22 #include "dns_resolve.h"
23 #include "cifs_debug.h"
24
25 LIST_HEAD(cifs_dfs_automount_list);
26
27 /*
28  * DFS functions
29 */
30
31 void dfs_shrink_umount_helper(struct vfsmount *vfsmnt)
32 {
33         mark_mounts_for_expiry(&cifs_dfs_automount_list);
34         mark_mounts_for_expiry(&cifs_dfs_automount_list);
35         shrink_submounts(vfsmnt, &cifs_dfs_automount_list);
36 }
37
38 /**
39  * cifs_get_share_name  -       extracts share name from UNC
40  * @node_name:  pointer to UNC string
41  *
42  * Extracts sharename form full UNC.
43  * i.e. strips from UNC trailing path that is not part of share
44  * name and fixup missing '\' in the begining of DFS node refferal
45  * if neccessary.
46  * Returns pointer to share name on success or NULL on error.
47  * Caller is responsible for freeing returned string.
48  */
49 static char *cifs_get_share_name(const char *node_name)
50 {
51         int len;
52         char *UNC;
53         char *pSep;
54
55         len = strlen(node_name);
56         UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
57                          GFP_KERNEL);
58         if (!UNC)
59                 return NULL;
60
61         /* get share name and server name */
62         if (node_name[1] != '\\') {
63                 UNC[0] = '\\';
64                 strncpy(UNC+1, node_name, len);
65                 len++;
66                 UNC[len] = 0;
67         } else {
68                 strncpy(UNC, node_name, len);
69                 UNC[len] = 0;
70         }
71
72         /* find server name end */
73         pSep = memchr(UNC+2, '\\', len-2);
74         if (!pSep) {
75                 cERROR(1, ("%s: no server name end in node name: %s",
76                         __FUNCTION__, node_name));
77                 kfree(UNC);
78                 return NULL;
79         }
80
81         /* find sharename end */
82         pSep++;
83         pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
84         if (!pSep) {
85                 cERROR(1, ("%s:2 cant find share name in node name: %s",
86                         __FUNCTION__, node_name));
87                 kfree(UNC);
88                 return NULL;
89         }
90         /* trim path up to sharename end
91          *          * now we have share name in UNC */
92         *pSep = 0;
93
94         return UNC;
95 }
96
97
98 /**
99  * compose_mount_options        -       creates mount options for refferral
100  * @sb_mountdata:       parent/root DFS mount options (template)
101  * @ref_unc:            refferral server UNC
102  * @devname:            pointer for saving device name
103  *
104  * creates mount options for submount based on template options sb_mountdata
105  * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
106  *
107  * Returns: pointer to new mount options or ERR_PTR.
108  * Caller is responcible for freeing retunrned value if it is not error.
109  */
110 char *compose_mount_options(const char *sb_mountdata, const char *ref_unc,
111                                 char **devname)
112 {
113         int rc;
114         char *mountdata;
115         int md_len;
116         char *tkn_e;
117         char *srvIP = NULL;
118         char sep = ',';
119         int off, noff;
120
121         if (sb_mountdata == NULL)
122                 return ERR_PTR(-EINVAL);
123
124         *devname = cifs_get_share_name(ref_unc);
125         rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
126         if (rc != 0) {
127                 cERROR(1, ("%s: Failed to resolve server part of %s to IP",
128                           __FUNCTION__, *devname));
129                 mountdata = ERR_PTR(rc);
130                 goto compose_mount_options_out;
131         }
132         md_len = strlen(sb_mountdata) + strlen(srvIP) + strlen(ref_unc) + 3;
133         mountdata = kzalloc(md_len+1, GFP_KERNEL);
134         if (mountdata == NULL) {
135                 mountdata = ERR_PTR(-ENOMEM);
136                 goto compose_mount_options_out;
137         }
138
139         /* copy all options except of unc,ip,prefixpath */
140         off = 0;
141         if (strncmp(sb_mountdata, "sep=", 4) == 0) {
142                         sep = sb_mountdata[4];
143                         strncpy(mountdata, sb_mountdata, 5);
144                         off += 5;
145         }
146         while ((tkn_e = strchr(sb_mountdata+off, sep))) {
147                 noff = (tkn_e - (sb_mountdata+off)) + 1;
148                 if (strnicmp(sb_mountdata+off, "unc=", 4) == 0) {
149                         off += noff;
150                         continue;
151                 }
152                 if (strnicmp(sb_mountdata+off, "ip=", 3) == 0) {
153                         off += noff;
154                         continue;
155                 }
156                 if (strnicmp(sb_mountdata+off, "prefixpath=", 3) == 0) {
157                         off += noff;
158                         continue;
159                 }
160                 strncat(mountdata, sb_mountdata+off, noff);
161                 off += noff;
162         }
163         strcat(mountdata, sb_mountdata+off);
164         mountdata[md_len] = '\0';
165
166         /* copy new IP and ref share name */
167         strcat(mountdata, ",ip=");
168         strcat(mountdata, srvIP);
169         strcat(mountdata, ",unc=");
170         strcat(mountdata, *devname);
171
172         /* find & copy prefixpath */
173         tkn_e = strchr(ref_unc+2, '\\');
174         if (tkn_e) {
175                 tkn_e = strchr(tkn_e+1, '\\');
176                 if (tkn_e) {
177                         strcat(mountdata, ",prefixpath=");
178                         strcat(mountdata, tkn_e);
179                 }
180         }
181
182         /*cFYI(1,("%s: parent mountdata: %s", __FUNCTION__,sb_mountdata));*/
183         /*cFYI(1, ("%s: submount mountdata: %s", __FUNCTION__, mountdata ));*/
184
185 compose_mount_options_out:
186         kfree(srvIP);
187         return mountdata;
188 }
189
190
191 struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
192                 struct dentry *dentry, char *ref_unc)
193 {
194         struct cifs_sb_info *cifs_sb;
195         struct vfsmount *mnt;
196         char *mountdata;
197         char *devname;
198
199         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
200         mountdata = compose_mount_options(cifs_sb->mountdata,
201                                                 ref_unc, &devname);
202
203         if (IS_ERR(mountdata))
204                 return (struct vfsmount *)mountdata;
205
206         mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
207         kfree(mountdata);
208         kfree(devname);
209         return mnt;
210
211 }
212
213 static char *build_full_dfs_path_from_dentry(struct dentry *dentry)
214 {
215         char *full_path = NULL;
216         char *search_path;
217         char *tmp_path;
218         size_t l_max_len;
219         struct cifs_sb_info *cifs_sb;
220
221         if (dentry->d_inode == NULL)
222                 return NULL;
223
224         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
225
226         if (cifs_sb->tcon == NULL)
227                 return NULL;
228
229         search_path = build_path_from_dentry(dentry);
230         if (search_path == NULL)
231                 return NULL;
232
233         if (cifs_sb->tcon->Flags & SMB_SHARE_IS_IN_DFS) {
234                 /* we should use full path name to correct working with DFS */
235                 l_max_len = strnlen(cifs_sb->tcon->treeName, MAX_TREE_SIZE+1) +
236                                         strnlen(search_path, MAX_PATHCONF) + 1;
237                 tmp_path = kmalloc(l_max_len, GFP_KERNEL);
238                 if (tmp_path == NULL) {
239                         kfree(search_path);
240                         return NULL;
241                 }
242                 strncpy(tmp_path, cifs_sb->tcon->treeName, l_max_len);
243                 strcat(tmp_path, search_path);
244                 tmp_path[l_max_len-1] = 0;
245                 full_path = tmp_path;
246                 kfree(search_path);
247         } else {
248                 full_path = search_path;
249         }
250         return full_path;
251 }
252
253 static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
254                                 struct list_head *mntlist)
255 {
256         /* stolen from afs code */
257         int err;
258
259         mntget(newmnt);
260         err = do_add_mount(newmnt, nd, nd->mnt->mnt_flags, mntlist);
261         switch (err) {
262         case 0:
263                 dput(nd->dentry);
264                 mntput(nd->mnt);
265                 nd->mnt = newmnt;
266                 nd->dentry = dget(newmnt->mnt_root);
267                 break;
268         case -EBUSY:
269                 /* someone else made a mount here whilst we were busy */
270                 while (d_mountpoint(nd->dentry) &&
271                        follow_down(&nd->mnt, &nd->dentry))
272                         ;
273                 err = 0;
274         default:
275                 mntput(newmnt);
276                 break;
277         }
278         return err;
279 }
280
281 void dump_referral(const struct dfs_info3_param *ref)
282 {
283         cFYI(1, ("DFS: ref path: %s", ref->path_name));
284         cFYI(1, ("DFS: node path: %s", ref->node_name));
285         cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
286         cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
287                                 ref->PathConsumed));
288 }
289
290
291 static void*
292 cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
293 {
294         struct dfs_info3_param *referrals = NULL;
295         unsigned int num_referrals = 0;
296         struct cifs_sb_info *cifs_sb;
297         struct cifsSesInfo *ses;
298         char *full_path = NULL;
299         int xid, i;
300         int rc = 0;
301         struct vfsmount *mnt = ERR_PTR(-ENOENT);
302
303         cFYI(1, ("in %s", __FUNCTION__));
304         BUG_ON(IS_ROOT(dentry));
305
306         xid = GetXid();
307
308         dput(nd->dentry);
309         nd->dentry = dget(dentry);
310
311         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
312         ses = cifs_sb->tcon->ses;
313
314         if (!ses) {
315                 rc = -EINVAL;
316                 goto out_err;
317         }
318
319         full_path = build_full_dfs_path_from_dentry(dentry);
320         if (full_path == NULL) {
321                 rc = -ENOMEM;
322                 goto out_err;
323         }
324
325         rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls,
326                 &num_referrals, &referrals,
327                 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
328
329         for (i = 0; i < num_referrals; i++) {
330                 dump_referral(referrals+i);
331                 /* connect to a storage node */
332                 if (referrals[i].flags & DFSREF_STORAGE_SERVER) {
333                         int len;
334                         len = strlen(referrals[i].node_name);
335                         if (len < 2) {
336                                 cERROR(1, ("%s: Net Address path too short: %s",
337                                         __FUNCTION__, referrals[i].node_name));
338                                 rc = -EINVAL;
339                                 goto out_err;
340                         }
341                         mnt = cifs_dfs_do_refmount(nd->mnt, nd->dentry,
342                                                 referrals[i].node_name);
343                         cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p",
344                                          __FUNCTION__,
345                                         referrals[i].node_name, mnt));
346
347                         /* complete mount procedure if we accured submount */
348                         if (!IS_ERR(mnt))
349                                 break;
350                 }
351         }
352
353         /* we need it cause for() above could exit without valid submount */
354         rc = PTR_ERR(mnt);
355         if (IS_ERR(mnt))
356                 goto out_err;
357
358         nd->mnt->mnt_flags |= MNT_SHRINKABLE;
359         rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
360
361 out:
362         FreeXid(xid);
363         free_dfs_info_array(referrals, num_referrals);
364         kfree(full_path);
365         cFYI(1, ("leaving %s" , __FUNCTION__));
366         return ERR_PTR(rc);
367 out_err:
368         path_release(nd);
369         goto out;
370 }
371
372 struct inode_operations cifs_dfs_referral_inode_operations = {
373         .follow_link = cifs_dfs_follow_mountpoint,
374 };
375