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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 "cifsglob.h" | |
22 | #include "cifsproto.h" | |
23 | #include "cifsfs.h" | |
24 | #include "dns_resolve.h" | |
25 | #include "cifs_debug.h" | |
26 | ||
27 | static LIST_HEAD(cifs_dfs_automount_list); | |
28 | ||
29 | static void cifs_dfs_expire_automounts(struct work_struct *work); | |
30 | static DECLARE_DELAYED_WORK(cifs_dfs_automount_task, | |
31 | cifs_dfs_expire_automounts); | |
32 | static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ; | |
33 | ||
34 | static void cifs_dfs_expire_automounts(struct work_struct *work) | |
35 | { | |
36 | struct list_head *list = &cifs_dfs_automount_list; | |
37 | ||
38 | mark_mounts_for_expiry(list); | |
39 | if (!list_empty(list)) | |
40 | schedule_delayed_work(&cifs_dfs_automount_task, | |
41 | cifs_dfs_mountpoint_expiry_timeout); | |
42 | } | |
43 | ||
44 | void cifs_dfs_release_automount_timer(void) | |
45 | { | |
46 | BUG_ON(!list_empty(&cifs_dfs_automount_list)); | |
47 | cancel_delayed_work(&cifs_dfs_automount_task); | |
48 | flush_scheduled_work(); | |
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 begining 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 | */ | |
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 | */ | |
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 | cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d", | |
146 | __func__, *devname, rc)); | |
147 | goto compose_mount_options_err; | |
148 | } | |
149 | /* md_len = strlen(...) + 12 for 'sep+prefixpath=' | |
150 | * assuming that we have 'unc=' and 'ip=' in | |
151 | * the original sb_mountdata | |
152 | */ | |
153 | md_len = strlen(sb_mountdata) + strlen(srvIP) + | |
154 | strlen(ref->node_name) + 12; | |
155 | mountdata = kzalloc(md_len+1, GFP_KERNEL); | |
156 | if (mountdata == NULL) { | |
157 | rc = -ENOMEM; | |
158 | goto compose_mount_options_err; | |
159 | } | |
160 | ||
161 | /* copy all options except of unc,ip,prefixpath */ | |
162 | off = 0; | |
163 | if (strncmp(sb_mountdata, "sep=", 4) == 0) { | |
164 | sep = sb_mountdata[4]; | |
165 | strncpy(mountdata, sb_mountdata, 5); | |
166 | off += 5; | |
167 | } | |
168 | ||
169 | do { | |
170 | tkn_e = strchr(sb_mountdata + off, sep); | |
171 | if (tkn_e == NULL) | |
172 | noff = strlen(sb_mountdata + off); | |
173 | else | |
174 | noff = tkn_e - (sb_mountdata + off) + 1; | |
175 | ||
176 | if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) { | |
177 | off += noff; | |
178 | continue; | |
179 | } | |
180 | if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) { | |
181 | off += noff; | |
182 | continue; | |
183 | } | |
184 | if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) { | |
185 | off += noff; | |
186 | continue; | |
187 | } | |
188 | strncat(mountdata, sb_mountdata + off, noff); | |
189 | off += noff; | |
190 | } while (tkn_e); | |
191 | strcat(mountdata, sb_mountdata + off); | |
192 | mountdata[md_len] = '\0'; | |
193 | ||
194 | /* copy new IP and ref share name */ | |
195 | if (mountdata[strlen(mountdata) - 1] != sep) | |
196 | strncat(mountdata, &sep, 1); | |
197 | strcat(mountdata, "ip="); | |
198 | strcat(mountdata, srvIP); | |
199 | strncat(mountdata, &sep, 1); | |
200 | strcat(mountdata, "unc="); | |
201 | strcat(mountdata, *devname); | |
202 | ||
203 | /* find & copy prefixpath */ | |
204 | tkn_e = strchr(ref->node_name + 2, '\\'); | |
205 | if (tkn_e == NULL) { | |
206 | /* invalid unc, missing share name*/ | |
207 | rc = -EINVAL; | |
208 | goto compose_mount_options_err; | |
209 | } | |
210 | ||
211 | tkn_e = strchr(tkn_e + 1, '\\'); | |
212 | if (tkn_e || (strlen(fullpath) - ref->path_consumed)) { | |
213 | strncat(mountdata, &sep, 1); | |
214 | strcat(mountdata, "prefixpath="); | |
215 | if (tkn_e) | |
216 | strcat(mountdata, tkn_e + 1); | |
217 | strcat(mountdata, fullpath + ref->path_consumed); | |
218 | } | |
219 | ||
220 | /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/ | |
221 | /*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/ | |
222 | ||
223 | compose_mount_options_out: | |
224 | kfree(srvIP); | |
225 | return mountdata; | |
226 | ||
227 | compose_mount_options_err: | |
228 | kfree(mountdata); | |
229 | mountdata = ERR_PTR(rc); | |
230 | goto compose_mount_options_out; | |
231 | } | |
232 | ||
233 | ||
234 | static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent, | |
235 | struct dentry *dentry, const struct dfs_info3_param *ref) | |
236 | { | |
237 | struct cifs_sb_info *cifs_sb; | |
238 | struct vfsmount *mnt; | |
239 | char *mountdata; | |
240 | char *devname = NULL; | |
241 | char *fullpath; | |
242 | ||
243 | cifs_sb = CIFS_SB(dentry->d_inode->i_sb); | |
244 | /* | |
245 | * this function gives us a path with a double backslash prefix. We | |
246 | * require a single backslash for DFS. | |
247 | */ | |
248 | fullpath = build_path_from_dentry(dentry); | |
249 | if (!fullpath) | |
250 | return ERR_PTR(-ENOMEM); | |
251 | ||
252 | mountdata = cifs_compose_mount_options(cifs_sb->mountdata, | |
253 | fullpath + 1, ref, &devname); | |
254 | kfree(fullpath); | |
255 | ||
256 | if (IS_ERR(mountdata)) | |
257 | return (struct vfsmount *)mountdata; | |
258 | ||
259 | mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata); | |
260 | kfree(mountdata); | |
261 | kfree(devname); | |
262 | return mnt; | |
263 | ||
264 | } | |
265 | ||
266 | static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd, | |
267 | struct list_head *mntlist) | |
268 | { | |
269 | /* stolen from afs code */ | |
270 | int err; | |
271 | ||
272 | mntget(newmnt); | |
273 | err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist); | |
274 | switch (err) { | |
275 | case 0: | |
276 | path_put(&nd->path); | |
277 | nd->path.mnt = newmnt; | |
278 | nd->path.dentry = dget(newmnt->mnt_root); | |
279 | schedule_delayed_work(&cifs_dfs_automount_task, | |
280 | cifs_dfs_mountpoint_expiry_timeout); | |
281 | break; | |
282 | case -EBUSY: | |
283 | /* someone else made a mount here whilst we were busy */ | |
284 | while (d_mountpoint(nd->path.dentry) && | |
285 | follow_down(&nd->path)) | |
286 | ; | |
287 | err = 0; | |
288 | default: | |
289 | mntput(newmnt); | |
290 | break; | |
291 | } | |
292 | return err; | |
293 | } | |
294 | ||
295 | static void dump_referral(const struct dfs_info3_param *ref) | |
296 | { | |
297 | cFYI(1, ("DFS: ref path: %s", ref->path_name)); | |
298 | cFYI(1, ("DFS: node path: %s", ref->node_name)); | |
299 | cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type)); | |
300 | cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag, | |
301 | ref->path_consumed)); | |
302 | } | |
303 | ||
304 | ||
305 | static void* | |
306 | cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) | |
307 | { | |
308 | struct dfs_info3_param *referrals = NULL; | |
309 | unsigned int num_referrals = 0; | |
310 | struct cifs_sb_info *cifs_sb; | |
311 | struct cifsSesInfo *ses; | |
312 | char *full_path = NULL; | |
313 | int xid, i; | |
314 | int rc = 0; | |
315 | struct vfsmount *mnt = ERR_PTR(-ENOENT); | |
316 | ||
317 | cFYI(1, ("in %s", __func__)); | |
318 | BUG_ON(IS_ROOT(dentry)); | |
319 | ||
320 | xid = GetXid(); | |
321 | ||
322 | dput(nd->path.dentry); | |
323 | nd->path.dentry = dget(dentry); | |
324 | ||
325 | cifs_sb = CIFS_SB(dentry->d_inode->i_sb); | |
326 | ses = cifs_sb->tcon->ses; | |
327 | ||
328 | if (!ses) { | |
329 | rc = -EINVAL; | |
330 | goto out_err; | |
331 | } | |
332 | ||
333 | /* | |
334 | * The MSDFS spec states that paths in DFS referral requests and | |
335 | * responses must be prefixed by a single '\' character instead of | |
336 | * the double backslashes usually used in the UNC. This function | |
337 | * gives us the latter, so we must adjust the result. | |
338 | */ | |
339 | full_path = build_path_from_dentry(dentry); | |
340 | if (full_path == NULL) { | |
341 | rc = -ENOMEM; | |
342 | goto out_err; | |
343 | } | |
344 | ||
345 | rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls, | |
346 | &num_referrals, &referrals, | |
347 | cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR); | |
348 | ||
349 | for (i = 0; i < num_referrals; i++) { | |
350 | int len; | |
351 | dump_referral(referrals+i); | |
352 | /* connect to a node */ | |
353 | len = strlen(referrals[i].node_name); | |
354 | if (len < 2) { | |
355 | cERROR(1, ("%s: Net Address path too short: %s", | |
356 | __func__, referrals[i].node_name)); | |
357 | rc = -EINVAL; | |
358 | goto out_err; | |
359 | } | |
360 | mnt = cifs_dfs_do_refmount(nd->path.mnt, | |
361 | nd->path.dentry, referrals + i); | |
362 | cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __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 | /* we need it cause for() above could exit without valid submount */ | |
371 | rc = PTR_ERR(mnt); | |
372 | if (IS_ERR(mnt)) | |
373 | goto out_err; | |
374 | ||
375 | rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list); | |
376 | ||
377 | out: | |
378 | FreeXid(xid); | |
379 | free_dfs_info_array(referrals, num_referrals); | |
380 | kfree(full_path); | |
381 | cFYI(1, ("leaving %s" , __func__)); | |
382 | return ERR_PTR(rc); | |
383 | out_err: | |
384 | path_put(&nd->path); | |
385 | goto out; | |
386 | } | |
387 | ||
388 | const struct inode_operations cifs_dfs_referral_inode_operations = { | |
389 | .follow_link = cifs_dfs_follow_mountpoint, | |
390 | }; | |
391 |