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1/*
2 * fs/cifs/link.c
3 *
4 * Copyright (C) International Business Machines Corp., 2002,2008
5 * Author(s): Steve French (sfrench@us.ibm.com)
6 *
7 * This library is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as published
9 * by the Free Software Foundation; either version 2.1 of the License, or
10 * (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
15 * the GNU Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public License
18 * along with this library; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21#include <linux/fs.h>
22#include <linux/stat.h>
23#include <linux/slab.h>
24#include <linux/namei.h>
25#include "cifsfs.h"
26#include "cifspdu.h"
27#include "cifsglob.h"
28#include "cifsproto.h"
29#include "cifs_debug.h"
30#include "cifs_fs_sb.h"
31
32/*
33 * M-F Symlink Functions - Begin
34 */
35
36#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
37#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
38#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
39#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
40#define CIFS_MF_SYMLINK_FILE_SIZE \
41 (CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)
42
43#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
44#define CIFS_MF_SYMLINK_MD5_FORMAT \
45 "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n"
46#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) \
47 md5_hash[0], md5_hash[1], md5_hash[2], md5_hash[3], \
48 md5_hash[4], md5_hash[5], md5_hash[6], md5_hash[7], \
49 md5_hash[8], md5_hash[9], md5_hash[10], md5_hash[11],\
50 md5_hash[12], md5_hash[13], md5_hash[14], md5_hash[15]
51
52static int
53symlink_hash(unsigned int link_len, const char *link_str, u8 *md5_hash)
54{
55 int rc;
56 unsigned int size;
57 struct crypto_shash *md5;
58 struct sdesc *sdescmd5;
59
60 md5 = crypto_alloc_shash("md5", 0, 0);
61 if (IS_ERR(md5)) {
62 rc = PTR_ERR(md5);
63 cifs_dbg(VFS, "%s: Crypto md5 allocation error %d\n",
64 __func__, rc);
65 return rc;
66 }
67 size = sizeof(struct shash_desc) + crypto_shash_descsize(md5);
68 sdescmd5 = kmalloc(size, GFP_KERNEL);
69 if (!sdescmd5) {
70 rc = -ENOMEM;
71 goto symlink_hash_err;
72 }
73 sdescmd5->shash.tfm = md5;
74 sdescmd5->shash.flags = 0x0;
75
76 rc = crypto_shash_init(&sdescmd5->shash);
77 if (rc) {
78 cifs_dbg(VFS, "%s: Could not init md5 shash\n", __func__);
79 goto symlink_hash_err;
80 }
81 rc = crypto_shash_update(&sdescmd5->shash, link_str, link_len);
82 if (rc) {
83 cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
84 goto symlink_hash_err;
85 }
86 rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
87 if (rc)
88 cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
89
90symlink_hash_err:
91 crypto_free_shash(md5);
92 kfree(sdescmd5);
93
94 return rc;
95}
96
97static int
98parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
99 char **_link_str)
100{
101 int rc;
102 unsigned int link_len;
103 const char *md5_str1;
104 const char *link_str;
105 u8 md5_hash[16];
106 char md5_str2[34];
107
108 if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
109 return -EINVAL;
110
111 md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
112 link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
113
114 rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
115 if (rc != 1)
116 return -EINVAL;
117
118 rc = symlink_hash(link_len, link_str, md5_hash);
119 if (rc) {
120 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
121 return rc;
122 }
123
124 snprintf(md5_str2, sizeof(md5_str2),
125 CIFS_MF_SYMLINK_MD5_FORMAT,
126 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
127
128 if (strncmp(md5_str1, md5_str2, 17) != 0)
129 return -EINVAL;
130
131 if (_link_str) {
132 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
133 if (!*_link_str)
134 return -ENOMEM;
135 }
136
137 *_link_len = link_len;
138 return 0;
139}
140
141static int
142format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
143{
144 int rc;
145 unsigned int link_len;
146 unsigned int ofs;
147 u8 md5_hash[16];
148
149 if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
150 return -EINVAL;
151
152 link_len = strlen(link_str);
153
154 if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
155 return -ENAMETOOLONG;
156
157 rc = symlink_hash(link_len, link_str, md5_hash);
158 if (rc) {
159 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
160 return rc;
161 }
162
163 snprintf(buf, buf_len,
164 CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
165 link_len,
166 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
167
168 ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
169 memcpy(buf + ofs, link_str, link_len);
170
171 ofs += link_len;
172 if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
173 buf[ofs] = '\n';
174 ofs++;
175 }
176
177 while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
178 buf[ofs] = ' ';
179 ofs++;
180 }
181
182 return 0;
183}
184
185bool
186couldbe_mf_symlink(const struct cifs_fattr *fattr)
187{
188 if (!S_ISREG(fattr->cf_mode))
189 /* it's not a symlink */
190 return false;
191
192 if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
193 /* it's not a symlink */
194 return false;
195
196 return true;
197}
198
199static int
200create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
201 struct cifs_sb_info *cifs_sb, const char *fromName,
202 const char *toName)
203{
204 int rc;
205 u8 *buf;
206 unsigned int bytes_written = 0;
207
208 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
209 if (!buf)
210 return -ENOMEM;
211
212 rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
213 if (rc)
214 goto out;
215
216 rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon, cifs_sb,
217 fromName, buf, &bytes_written);
218 if (rc)
219 goto out;
220
221 if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
222 rc = -EIO;
223out:
224 kfree(buf);
225 return rc;
226}
227
228static int
229query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
230 struct cifs_sb_info *cifs_sb, const unsigned char *path,
231 char **symlinkinfo)
232{
233 int rc;
234 u8 *buf = NULL;
235 unsigned int link_len = 0;
236 unsigned int bytes_read = 0;
237
238 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
239 if (!buf)
240 return -ENOMEM;
241
242 if (tcon->ses->server->ops->query_mf_symlink)
243 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
244 cifs_sb, path, buf, &bytes_read);
245 else
246 rc = -ENOSYS;
247
248 if (rc)
249 goto out;
250
251 if (bytes_read == 0) { /* not a symlink */
252 rc = -EINVAL;
253 goto out;
254 }
255
256 rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
257out:
258 kfree(buf);
259 return rc;
260}
261
262int
263check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
264 struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
265 const unsigned char *path)
266{
267 int rc;
268 u8 *buf = NULL;
269 unsigned int link_len = 0;
270 unsigned int bytes_read = 0;
271
272 if (!couldbe_mf_symlink(fattr))
273 /* it's not a symlink */
274 return 0;
275
276 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
277 if (!buf)
278 return -ENOMEM;
279
280 if (tcon->ses->server->ops->query_mf_symlink)
281 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
282 cifs_sb, path, buf, &bytes_read);
283 else
284 rc = -ENOSYS;
285
286 if (rc)
287 goto out;
288
289 if (bytes_read == 0) /* not a symlink */
290 goto out;
291
292 rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
293 if (rc == -EINVAL) {
294 /* it's not a symlink */
295 rc = 0;
296 goto out;
297 }
298
299 if (rc != 0)
300 goto out;
301
302 /* it is a symlink */
303 fattr->cf_eof = link_len;
304 fattr->cf_mode &= ~S_IFMT;
305 fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
306 fattr->cf_dtype = DT_LNK;
307out:
308 kfree(buf);
309 return rc;
310}
311
312/*
313 * SMB 1.0 Protocol specific functions
314 */
315
316int
317cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
318 struct cifs_sb_info *cifs_sb, const unsigned char *path,
319 char *pbuf, unsigned int *pbytes_read)
320{
321 int rc;
322 int oplock = 0;
323 struct cifs_fid fid;
324 struct cifs_open_parms oparms;
325 struct cifs_io_parms io_parms;
326 int buf_type = CIFS_NO_BUFFER;
327 FILE_ALL_INFO file_info;
328
329 oparms.tcon = tcon;
330 oparms.cifs_sb = cifs_sb;
331 oparms.desired_access = GENERIC_READ;
332 oparms.create_options = CREATE_NOT_DIR;
333 oparms.disposition = FILE_OPEN;
334 oparms.path = path;
335 oparms.fid = &fid;
336 oparms.reconnect = false;
337
338 rc = CIFS_open(xid, &oparms, &oplock, &file_info);
339 if (rc)
340 return rc;
341
342 if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE))
343 /* it's not a symlink */
344 goto out;
345
346 io_parms.netfid = fid.netfid;
347 io_parms.pid = current->tgid;
348 io_parms.tcon = tcon;
349 io_parms.offset = 0;
350 io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
351
352 rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
353out:
354 CIFSSMBClose(xid, tcon, fid.netfid);
355 return rc;
356}
357
358int
359cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
360 struct cifs_sb_info *cifs_sb, const unsigned char *path,
361 char *pbuf, unsigned int *pbytes_written)
362{
363 int rc;
364 int oplock = 0;
365 struct cifs_fid fid;
366 struct cifs_open_parms oparms;
367 struct cifs_io_parms io_parms;
368 int create_options = CREATE_NOT_DIR;
369
370 if (backup_cred(cifs_sb))
371 create_options |= CREATE_OPEN_BACKUP_INTENT;
372
373 oparms.tcon = tcon;
374 oparms.cifs_sb = cifs_sb;
375 oparms.desired_access = GENERIC_WRITE;
376 oparms.create_options = create_options;
377 oparms.disposition = FILE_OPEN;
378 oparms.path = path;
379 oparms.fid = &fid;
380 oparms.reconnect = false;
381
382 rc = CIFS_open(xid, &oparms, &oplock, NULL);
383 if (rc)
384 return rc;
385
386 io_parms.netfid = fid.netfid;
387 io_parms.pid = current->tgid;
388 io_parms.tcon = tcon;
389 io_parms.offset = 0;
390 io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
391
392 rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf, NULL, 0);
393 CIFSSMBClose(xid, tcon, fid.netfid);
394 return rc;
395}
396
397/*
398 * M-F Symlink Functions - End
399 */
400
401int
402cifs_hardlink(struct dentry *old_file, struct inode *inode,
403 struct dentry *direntry)
404{
405 int rc = -EACCES;
406 unsigned int xid;
407 char *from_name = NULL;
408 char *to_name = NULL;
409 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
410 struct tcon_link *tlink;
411 struct cifs_tcon *tcon;
412 struct TCP_Server_Info *server;
413 struct cifsInodeInfo *cifsInode;
414
415 tlink = cifs_sb_tlink(cifs_sb);
416 if (IS_ERR(tlink))
417 return PTR_ERR(tlink);
418 tcon = tlink_tcon(tlink);
419
420 xid = get_xid();
421
422 from_name = build_path_from_dentry(old_file);
423 to_name = build_path_from_dentry(direntry);
424 if ((from_name == NULL) || (to_name == NULL)) {
425 rc = -ENOMEM;
426 goto cifs_hl_exit;
427 }
428
429 if (tcon->unix_ext)
430 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
431 cifs_sb->local_nls,
432 cifs_sb->mnt_cifs_flags &
433 CIFS_MOUNT_MAP_SPECIAL_CHR);
434 else {
435 server = tcon->ses->server;
436 if (!server->ops->create_hardlink) {
437 rc = -ENOSYS;
438 goto cifs_hl_exit;
439 }
440 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
441 cifs_sb);
442 if ((rc == -EIO) || (rc == -EINVAL))
443 rc = -EOPNOTSUPP;
444 }
445
446 d_drop(direntry); /* force new lookup from server of target */
447
448 /*
449 * if source file is cached (oplocked) revalidate will not go to server
450 * until the file is closed or oplock broken so update nlinks locally
451 */
452 if (old_file->d_inode) {
453 cifsInode = CIFS_I(old_file->d_inode);
454 if (rc == 0) {
455 spin_lock(&old_file->d_inode->i_lock);
456 inc_nlink(old_file->d_inode);
457 spin_unlock(&old_file->d_inode->i_lock);
458 /*
459 * BB should we make this contingent on superblock flag
460 * NOATIME?
461 */
462 /* old_file->d_inode->i_ctime = CURRENT_TIME; */
463 /*
464 * parent dir timestamps will update from srv within a
465 * second, would it really be worth it to set the parent
466 * dir cifs inode time to zero to force revalidate
467 * (faster) for it too?
468 */
469 }
470 /*
471 * if not oplocked will force revalidate to get info on source
472 * file from srv
473 */
474 cifsInode->time = 0;
475
476 /*
477 * Will update parent dir timestamps from srv within a second.
478 * Would it really be worth it to set the parent dir (cifs
479 * inode) time field to zero to force revalidate on parent
480 * directory faster ie
481 *
482 * CIFS_I(inode)->time = 0;
483 */
484 }
485
486cifs_hl_exit:
487 kfree(from_name);
488 kfree(to_name);
489 free_xid(xid);
490 cifs_put_tlink(tlink);
491 return rc;
492}
493
494void *
495cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
496{
497 struct inode *inode = direntry->d_inode;
498 int rc = -ENOMEM;
499 unsigned int xid;
500 char *full_path = NULL;
501 char *target_path = NULL;
502 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
503 struct tcon_link *tlink = NULL;
504 struct cifs_tcon *tcon;
505 struct TCP_Server_Info *server;
506
507 xid = get_xid();
508
509 tlink = cifs_sb_tlink(cifs_sb);
510 if (IS_ERR(tlink)) {
511 rc = PTR_ERR(tlink);
512 tlink = NULL;
513 goto out;
514 }
515 tcon = tlink_tcon(tlink);
516 server = tcon->ses->server;
517
518 full_path = build_path_from_dentry(direntry);
519 if (!full_path)
520 goto out;
521
522 cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
523
524 rc = -EACCES;
525 /*
526 * First try Minshall+French Symlinks, if configured
527 * and fallback to UNIX Extensions Symlinks.
528 */
529 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
530 rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
531 &target_path);
532
533 if (rc != 0 && server->ops->query_symlink)
534 rc = server->ops->query_symlink(xid, tcon, full_path,
535 &target_path, cifs_sb);
536
537 kfree(full_path);
538out:
539 if (rc != 0) {
540 kfree(target_path);
541 target_path = ERR_PTR(rc);
542 }
543
544 free_xid(xid);
545 if (tlink)
546 cifs_put_tlink(tlink);
547 nd_set_link(nd, target_path);
548 return NULL;
549}
550
551int
552cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
553{
554 int rc = -EOPNOTSUPP;
555 unsigned int xid;
556 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
557 struct tcon_link *tlink;
558 struct cifs_tcon *pTcon;
559 char *full_path = NULL;
560 struct inode *newinode = NULL;
561
562 xid = get_xid();
563
564 tlink = cifs_sb_tlink(cifs_sb);
565 if (IS_ERR(tlink)) {
566 rc = PTR_ERR(tlink);
567 goto symlink_exit;
568 }
569 pTcon = tlink_tcon(tlink);
570
571 full_path = build_path_from_dentry(direntry);
572 if (full_path == NULL) {
573 rc = -ENOMEM;
574 goto symlink_exit;
575 }
576
577 cifs_dbg(FYI, "Full path: %s\n", full_path);
578 cifs_dbg(FYI, "symname is %s\n", symname);
579
580 /* BB what if DFS and this volume is on different share? BB */
581 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
582 rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
583 else if (pTcon->unix_ext)
584 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
585 cifs_sb->local_nls);
586 /* else
587 rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
588 cifs_sb_target->local_nls); */
589
590 if (rc == 0) {
591 if (pTcon->unix_ext)
592 rc = cifs_get_inode_info_unix(&newinode, full_path,
593 inode->i_sb, xid);
594 else
595 rc = cifs_get_inode_info(&newinode, full_path, NULL,
596 inode->i_sb, xid, NULL);
597
598 if (rc != 0) {
599 cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
600 rc);
601 } else {
602 d_instantiate(direntry, newinode);
603 }
604 }
605symlink_exit:
606 kfree(full_path);
607 cifs_put_tlink(tlink);
608 free_xid(xid);
609 return rc;
610}