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