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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#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
33#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
34#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
35#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
36#define CIFS_MF_SYMLINK_FILE_SIZE \
37 (CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)
38
39#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
40#define CIFS_MF_SYMLINK_MD5_FORMAT \
41 "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n"
42#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) \
43 md5_hash[0], md5_hash[1], md5_hash[2], md5_hash[3], \
44 md5_hash[4], md5_hash[5], md5_hash[6], md5_hash[7], \
45 md5_hash[8], md5_hash[9], md5_hash[10], md5_hash[11],\
46 md5_hash[12], md5_hash[13], md5_hash[14], md5_hash[15]
47
48static int
49symlink_hash(unsigned int link_len, const char *link_str, u8 *md5_hash)
50{
51 int rc;
52 unsigned int size;
53 struct crypto_shash *md5;
54 struct sdesc *sdescmd5;
55
56 md5 = crypto_alloc_shash("md5", 0, 0);
57 if (IS_ERR(md5)) {
58 rc = PTR_ERR(md5);
59 cERROR(1, "%s: Crypto md5 allocation error %d\n", __func__, rc);
60 return rc;
61 }
62 size = sizeof(struct shash_desc) + crypto_shash_descsize(md5);
63 sdescmd5 = kmalloc(size, GFP_KERNEL);
64 if (!sdescmd5) {
65 rc = -ENOMEM;
66 cERROR(1, "%s: Memory allocation failure\n", __func__);
67 goto symlink_hash_err;
68 }
69 sdescmd5->shash.tfm = md5;
70 sdescmd5->shash.flags = 0x0;
71
72 rc = crypto_shash_init(&sdescmd5->shash);
73 if (rc) {
74 cERROR(1, "%s: Could not init md5 shash\n", __func__);
75 goto symlink_hash_err;
76 }
77 rc = crypto_shash_update(&sdescmd5->shash, link_str, link_len);
78 if (rc) {
79 cERROR(1, "%s: Could not update iwth link_str\n", __func__);
80 goto symlink_hash_err;
81 }
82 rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
83 if (rc)
84 cERROR(1, "%s: Could not generate md5 hash\n", __func__);
85
86symlink_hash_err:
87 crypto_free_shash(md5);
88 kfree(sdescmd5);
89
90 return rc;
91}
92
93static int
94CIFSParseMFSymlink(const u8 *buf,
95 unsigned int buf_len,
96 unsigned int *_link_len,
97 char **_link_str)
98{
99 int rc;
100 unsigned int link_len;
101 const char *md5_str1;
102 const char *link_str;
103 u8 md5_hash[16];
104 char md5_str2[34];
105
106 if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
107 return -EINVAL;
108
109 md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
110 link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
111
112 rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
113 if (rc != 1)
114 return -EINVAL;
115
116 rc = symlink_hash(link_len, link_str, md5_hash);
117 if (rc) {
118 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
119 return rc;
120 }
121
122 snprintf(md5_str2, sizeof(md5_str2),
123 CIFS_MF_SYMLINK_MD5_FORMAT,
124 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
125
126 if (strncmp(md5_str1, md5_str2, 17) != 0)
127 return -EINVAL;
128
129 if (_link_str) {
130 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
131 if (!*_link_str)
132 return -ENOMEM;
133 }
134
135 *_link_len = link_len;
136 return 0;
137}
138
139static int
140CIFSFormatMFSymlink(u8 *buf, unsigned int buf_len, const char *link_str)
141{
142 int rc;
143 unsigned int link_len;
144 unsigned int ofs;
145 u8 md5_hash[16];
146
147 if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
148 return -EINVAL;
149
150 link_len = strlen(link_str);
151
152 if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
153 return -ENAMETOOLONG;
154
155 rc = symlink_hash(link_len, link_str, md5_hash);
156 if (rc) {
157 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
158 return rc;
159 }
160
161 snprintf(buf, buf_len,
162 CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
163 link_len,
164 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
165
166 ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
167 memcpy(buf + ofs, link_str, link_len);
168
169 ofs += link_len;
170 if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
171 buf[ofs] = '\n';
172 ofs++;
173 }
174
175 while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
176 buf[ofs] = ' ';
177 ofs++;
178 }
179
180 return 0;
181}
182
183static int
184CIFSCreateMFSymLink(const int xid, struct cifs_tcon *tcon,
185 const char *fromName, const char *toName,
186 struct cifs_sb_info *cifs_sb)
187{
188 int rc;
189 int oplock = 0;
190 int remap;
191 int create_options = CREATE_NOT_DIR;
192 __u16 netfid = 0;
193 u8 *buf;
194 unsigned int bytes_written = 0;
195 struct cifs_io_parms io_parms;
196 struct nls_table *nls_codepage;
197
198 nls_codepage = cifs_sb->local_nls;
199 remap = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR;
200
201 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
202 if (!buf)
203 return -ENOMEM;
204
205 rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
206 if (rc != 0) {
207 kfree(buf);
208 return rc;
209 }
210
211 if (backup_cred(cifs_sb))
212 create_options |= CREATE_OPEN_BACKUP_INTENT;
213
214 rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
215 create_options, &netfid, &oplock, NULL,
216 nls_codepage, remap);
217 if (rc != 0) {
218 kfree(buf);
219 return rc;
220 }
221
222 io_parms.netfid = netfid;
223 io_parms.pid = current->tgid;
224 io_parms.tcon = tcon;
225 io_parms.offset = 0;
226 io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
227
228 rc = CIFSSMBWrite(xid, &io_parms, &bytes_written, buf, NULL, 0);
229 CIFSSMBClose(xid, tcon, netfid);
230 kfree(buf);
231 if (rc != 0)
232 return rc;
233
234 if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
235 return -EIO;
236
237 return 0;
238}
239
240static int
241CIFSQueryMFSymLink(const int xid, struct cifs_tcon *tcon,
242 const unsigned char *searchName, char **symlinkinfo,
243 const struct nls_table *nls_codepage, int remap)
244{
245 int rc;
246 int oplock = 0;
247 __u16 netfid = 0;
248 u8 *buf;
249 char *pbuf;
250 unsigned int bytes_read = 0;
251 int buf_type = CIFS_NO_BUFFER;
252 unsigned int link_len = 0;
253 struct cifs_io_parms io_parms;
254 FILE_ALL_INFO file_info;
255
256 rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
257 CREATE_NOT_DIR, &netfid, &oplock, &file_info,
258 nls_codepage, remap);
259 if (rc != 0)
260 return rc;
261
262 if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
263 CIFSSMBClose(xid, tcon, netfid);
264 /* it's not a symlink */
265 return -EINVAL;
266 }
267
268 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
269 if (!buf)
270 return -ENOMEM;
271 pbuf = buf;
272 io_parms.netfid = netfid;
273 io_parms.pid = current->tgid;
274 io_parms.tcon = tcon;
275 io_parms.offset = 0;
276 io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
277
278 rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
279 CIFSSMBClose(xid, tcon, netfid);
280 if (rc != 0) {
281 kfree(buf);
282 return rc;
283 }
284
285 rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
286 kfree(buf);
287 if (rc != 0)
288 return rc;
289
290 return 0;
291}
292
293bool
294CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
295{
296 if (!(fattr->cf_mode & S_IFREG))
297 /* it's not a symlink */
298 return false;
299
300 if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
301 /* it's not a symlink */
302 return false;
303
304 return true;
305}
306
307int
308CIFSCheckMFSymlink(struct cifs_fattr *fattr,
309 const unsigned char *path,
310 struct cifs_sb_info *cifs_sb, int xid)
311{
312 int rc;
313 int oplock = 0;
314 __u16 netfid = 0;
315 struct tcon_link *tlink;
316 struct cifs_tcon *pTcon;
317 struct cifs_io_parms io_parms;
318 u8 *buf;
319 char *pbuf;
320 unsigned int bytes_read = 0;
321 int buf_type = CIFS_NO_BUFFER;
322 unsigned int link_len = 0;
323 FILE_ALL_INFO file_info;
324
325 if (!CIFSCouldBeMFSymlink(fattr))
326 /* it's not a symlink */
327 return 0;
328
329 tlink = cifs_sb_tlink(cifs_sb);
330 if (IS_ERR(tlink))
331 return PTR_ERR(tlink);
332 pTcon = tlink_tcon(tlink);
333
334 rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
335 CREATE_NOT_DIR, &netfid, &oplock, &file_info,
336 cifs_sb->local_nls,
337 cifs_sb->mnt_cifs_flags &
338 CIFS_MOUNT_MAP_SPECIAL_CHR);
339 if (rc != 0)
340 goto out;
341
342 if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
343 CIFSSMBClose(xid, pTcon, netfid);
344 /* it's not a symlink */
345 goto out;
346 }
347
348 buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
349 if (!buf) {
350 rc = -ENOMEM;
351 goto out;
352 }
353 pbuf = buf;
354 io_parms.netfid = netfid;
355 io_parms.pid = current->tgid;
356 io_parms.tcon = pTcon;
357 io_parms.offset = 0;
358 io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
359
360 rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
361 CIFSSMBClose(xid, pTcon, netfid);
362 if (rc != 0) {
363 kfree(buf);
364 goto out;
365 }
366
367 rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
368 kfree(buf);
369 if (rc == -EINVAL) {
370 /* it's not a symlink */
371 rc = 0;
372 goto out;
373 }
374
375 if (rc != 0)
376 goto out;
377
378 /* it is a symlink */
379 fattr->cf_eof = link_len;
380 fattr->cf_mode &= ~S_IFMT;
381 fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
382 fattr->cf_dtype = DT_LNK;
383out:
384 cifs_put_tlink(tlink);
385 return rc;
386}
387
388int
389cifs_hardlink(struct dentry *old_file, struct inode *inode,
390 struct dentry *direntry)
391{
392 int rc = -EACCES;
393 int xid;
394 char *fromName = NULL;
395 char *toName = NULL;
396 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
397 struct tcon_link *tlink;
398 struct cifs_tcon *pTcon;
399 struct cifsInodeInfo *cifsInode;
400
401 tlink = cifs_sb_tlink(cifs_sb);
402 if (IS_ERR(tlink))
403 return PTR_ERR(tlink);
404 pTcon = tlink_tcon(tlink);
405
406 xid = GetXid();
407
408 fromName = build_path_from_dentry(old_file);
409 toName = build_path_from_dentry(direntry);
410 if ((fromName == NULL) || (toName == NULL)) {
411 rc = -ENOMEM;
412 goto cifs_hl_exit;
413 }
414
415 if (pTcon->unix_ext)
416 rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
417 cifs_sb->local_nls,
418 cifs_sb->mnt_cifs_flags &
419 CIFS_MOUNT_MAP_SPECIAL_CHR);
420 else {
421 rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
422 cifs_sb->local_nls,
423 cifs_sb->mnt_cifs_flags &
424 CIFS_MOUNT_MAP_SPECIAL_CHR);
425 if ((rc == -EIO) || (rc == -EINVAL))
426 rc = -EOPNOTSUPP;
427 }
428
429 d_drop(direntry); /* force new lookup from server of target */
430
431 /* if source file is cached (oplocked) revalidate will not go to server
432 until the file is closed or oplock broken so update nlinks locally */
433 if (old_file->d_inode) {
434 cifsInode = CIFS_I(old_file->d_inode);
435 if (rc == 0) {
436 inc_nlink(old_file->d_inode);
437/* BB should we make this contingent on superblock flag NOATIME? */
438/* old_file->d_inode->i_ctime = CURRENT_TIME;*/
439 /* parent dir timestamps will update from srv
440 within a second, would it really be worth it
441 to set the parent dir cifs inode time to zero
442 to force revalidate (faster) for it too? */
443 }
444 /* if not oplocked will force revalidate to get info
445 on source file from srv */
446 cifsInode->time = 0;
447
448 /* Will update parent dir timestamps from srv within a second.
449 Would it really be worth it to set the parent dir (cifs
450 inode) time field to zero to force revalidate on parent
451 directory faster ie
452 CIFS_I(inode)->time = 0; */
453 }
454
455cifs_hl_exit:
456 kfree(fromName);
457 kfree(toName);
458 FreeXid(xid);
459 cifs_put_tlink(tlink);
460 return rc;
461}
462
463void *
464cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
465{
466 struct inode *inode = direntry->d_inode;
467 int rc = -ENOMEM;
468 int xid;
469 char *full_path = NULL;
470 char *target_path = NULL;
471 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
472 struct tcon_link *tlink = NULL;
473 struct cifs_tcon *tcon;
474
475 xid = GetXid();
476
477 tlink = cifs_sb_tlink(cifs_sb);
478 if (IS_ERR(tlink)) {
479 rc = PTR_ERR(tlink);
480 tlink = NULL;
481 goto out;
482 }
483 tcon = tlink_tcon(tlink);
484
485 /*
486 * For now, we just handle symlinks with unix extensions enabled.
487 * Eventually we should handle NTFS reparse points, and MacOS
488 * symlink support. For instance...
489 *
490 * rc = CIFSSMBQueryReparseLinkInfo(...)
491 *
492 * For now, just return -EACCES when the server doesn't support posix
493 * extensions. Note that we still allow querying symlinks when posix
494 * extensions are manually disabled. We could disable these as well
495 * but there doesn't seem to be any harm in allowing the client to
496 * read them.
497 */
498 if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
499 && !(tcon->ses->capabilities & CAP_UNIX)) {
500 rc = -EACCES;
501 goto out;
502 }
503
504 full_path = build_path_from_dentry(direntry);
505 if (!full_path)
506 goto out;
507
508 cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
509
510 rc = -EACCES;
511 /*
512 * First try Minshall+French Symlinks, if configured
513 * and fallback to UNIX Extensions Symlinks.
514 */
515 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
516 rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
517 cifs_sb->local_nls,
518 cifs_sb->mnt_cifs_flags &
519 CIFS_MOUNT_MAP_SPECIAL_CHR);
520
521 if ((rc != 0) && (tcon->ses->capabilities & CAP_UNIX))
522 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
523 cifs_sb->local_nls);
524
525 kfree(full_path);
526out:
527 if (rc != 0) {
528 kfree(target_path);
529 target_path = ERR_PTR(rc);
530 }
531
532 FreeXid(xid);
533 if (tlink)
534 cifs_put_tlink(tlink);
535 nd_set_link(nd, target_path);
536 return NULL;
537}
538
539int
540cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
541{
542 int rc = -EOPNOTSUPP;
543 int xid;
544 struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
545 struct tcon_link *tlink;
546 struct cifs_tcon *pTcon;
547 char *full_path = NULL;
548 struct inode *newinode = NULL;
549
550 xid = GetXid();
551
552 tlink = cifs_sb_tlink(cifs_sb);
553 if (IS_ERR(tlink)) {
554 rc = PTR_ERR(tlink);
555 goto symlink_exit;
556 }
557 pTcon = tlink_tcon(tlink);
558
559 full_path = build_path_from_dentry(direntry);
560 if (full_path == NULL) {
561 rc = -ENOMEM;
562 goto symlink_exit;
563 }
564
565 cFYI(1, "Full path: %s", full_path);
566 cFYI(1, "symname is %s", symname);
567
568 /* BB what if DFS and this volume is on different share? BB */
569 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
570 rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
571 cifs_sb);
572 else if (pTcon->unix_ext)
573 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
574 cifs_sb->local_nls);
575 /* else
576 rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
577 cifs_sb_target->local_nls); */
578
579 if (rc == 0) {
580 if (pTcon->unix_ext)
581 rc = cifs_get_inode_info_unix(&newinode, full_path,
582 inode->i_sb, xid);
583 else
584 rc = cifs_get_inode_info(&newinode, full_path, NULL,
585 inode->i_sb, xid, NULL);
586
587 if (rc != 0) {
588 cFYI(1, "Create symlink ok, getinodeinfo fail rc = %d",
589 rc);
590 } else {
591 d_instantiate(direntry, newinode);
592 }
593 }
594symlink_exit:
595 kfree(full_path);
596 cifs_put_tlink(tlink);
597 FreeXid(xid);
598 return rc;
599}
600
601void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
602{
603 char *p = nd_get_link(nd);
604 if (!IS_ERR(p))
605 kfree(p);
606}