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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
48 static int
49 symlink_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                 cifs_dbg(VFS, "%s: Crypto md5 allocation error %d\n",
60                          __func__, rc);
61                 return rc;
62         }
63         size = sizeof(struct shash_desc) + crypto_shash_descsize(md5);
64         sdescmd5 = kmalloc(size, GFP_KERNEL);
65         if (!sdescmd5) {
66                 rc = -ENOMEM;
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                 cifs_dbg(VFS, "%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                 cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
80                 goto symlink_hash_err;
81         }
82         rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
83         if (rc)
84                 cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
85
86 symlink_hash_err:
87         crypto_free_shash(md5);
88         kfree(sdescmd5);
89
90         return rc;
91 }
92
93 static int
94 CIFSParseMFSymlink(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                 cifs_dbg(FYI, "%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
139 static int
140 CIFSFormatMFSymlink(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                 cifs_dbg(FYI, "%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
183 static int
184 CIFSCreateMFSymLink(const unsigned 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
240 static int
241 CIFSQueryMFSymLink(const unsigned 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
293 bool
294 CIFSCouldBeMFSymlink(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
307 int
308 open_query_close_cifs_symlink(const unsigned char *path, char *pbuf,
309                         unsigned int *pbytes_read, struct cifs_sb_info *cifs_sb,
310                         unsigned 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         int buf_type = CIFS_NO_BUFFER;
319         FILE_ALL_INFO file_info;
320
321         tlink = cifs_sb_tlink(cifs_sb);
322         if (IS_ERR(tlink))
323                 return PTR_ERR(tlink);
324         ptcon = tlink_tcon(tlink);
325
326         rc = CIFSSMBOpen(xid, ptcon, path, FILE_OPEN, GENERIC_READ,
327                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
328                          cifs_sb->local_nls,
329                          cifs_sb->mnt_cifs_flags &
330                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
331         if (rc != 0) {
332                 cifs_put_tlink(tlink);
333                 return rc;
334         }
335
336         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
337                 CIFSSMBClose(xid, ptcon, netfid);
338                 cifs_put_tlink(tlink);
339                 /* it's not a symlink */
340                 return rc;
341         }
342
343         io_parms.netfid = netfid;
344         io_parms.pid = current->tgid;
345         io_parms.tcon = ptcon;
346         io_parms.offset = 0;
347         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
348
349         rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
350         CIFSSMBClose(xid, ptcon, netfid);
351         cifs_put_tlink(tlink);
352         return rc;
353 }
354
355
356 int
357 CIFSCheckMFSymlink(unsigned int xid, struct cifs_tcon *tcon,
358                    struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
359                    const unsigned char *path)
360 {
361         int rc;
362         u8 *buf = NULL;
363         unsigned int link_len = 0;
364         unsigned int bytes_read = 0;
365
366         if (!CIFSCouldBeMFSymlink(fattr))
367                 /* it's not a symlink */
368                 return 0;
369
370         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
371         if (!buf)
372                 return -ENOMEM;
373
374         if (tcon->ses->server->ops->query_mf_symlink)
375                 rc = tcon->ses->server->ops->query_mf_symlink(path, buf,
376                                                 &bytes_read, cifs_sb, xid);
377         else
378                 rc = -ENOSYS;
379
380         if (rc)
381                 goto out;
382
383         if (bytes_read == 0) /* not a symlink */
384                 goto out;
385
386         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
387         if (rc == -EINVAL) {
388                 /* it's not a symlink */
389                 rc = 0;
390                 goto out;
391         }
392
393         if (rc != 0)
394                 goto out;
395
396         /* it is a symlink */
397         fattr->cf_eof = link_len;
398         fattr->cf_mode &= ~S_IFMT;
399         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
400         fattr->cf_dtype = DT_LNK;
401 out:
402         kfree(buf);
403         return rc;
404 }
405
406 int
407 cifs_hardlink(struct dentry *old_file, struct inode *inode,
408               struct dentry *direntry)
409 {
410         int rc = -EACCES;
411         unsigned int xid;
412         char *from_name = NULL;
413         char *to_name = NULL;
414         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
415         struct tcon_link *tlink;
416         struct cifs_tcon *tcon;
417         struct TCP_Server_Info *server;
418         struct cifsInodeInfo *cifsInode;
419
420         tlink = cifs_sb_tlink(cifs_sb);
421         if (IS_ERR(tlink))
422                 return PTR_ERR(tlink);
423         tcon = tlink_tcon(tlink);
424
425         xid = get_xid();
426
427         from_name = build_path_from_dentry(old_file);
428         to_name = build_path_from_dentry(direntry);
429         if ((from_name == NULL) || (to_name == NULL)) {
430                 rc = -ENOMEM;
431                 goto cifs_hl_exit;
432         }
433
434         if (tcon->unix_ext)
435                 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
436                                             cifs_sb->local_nls,
437                                             cifs_sb->mnt_cifs_flags &
438                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
439         else {
440                 server = tcon->ses->server;
441                 if (!server->ops->create_hardlink)
442                         return -ENOSYS;
443                 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
444                                                   cifs_sb);
445                 if ((rc == -EIO) || (rc == -EINVAL))
446                         rc = -EOPNOTSUPP;
447         }
448
449         d_drop(direntry);       /* force new lookup from server of target */
450
451         /*
452          * if source file is cached (oplocked) revalidate will not go to server
453          * until the file is closed or oplock broken so update nlinks locally
454          */
455         if (old_file->d_inode) {
456                 cifsInode = CIFS_I(old_file->d_inode);
457                 if (rc == 0) {
458                         spin_lock(&old_file->d_inode->i_lock);
459                         inc_nlink(old_file->d_inode);
460                         spin_unlock(&old_file->d_inode->i_lock);
461                         /*
462                          * BB should we make this contingent on superblock flag
463                          * NOATIME?
464                          */
465                         /* old_file->d_inode->i_ctime = CURRENT_TIME; */
466                         /*
467                          * parent dir timestamps will update from srv within a
468                          * second, would it really be worth it to set the parent
469                          * dir cifs inode time to zero to force revalidate
470                          * (faster) for it too?
471                          */
472                 }
473                 /*
474                  * if not oplocked will force revalidate to get info on source
475                  * file from srv
476                  */
477                 cifsInode->time = 0;
478
479                 /*
480                  * Will update parent dir timestamps from srv within a second.
481                  * Would it really be worth it to set the parent dir (cifs
482                  * inode) time field to zero to force revalidate on parent
483                  * directory faster ie
484                  *
485                  * CIFS_I(inode)->time = 0;
486                  */
487         }
488
489 cifs_hl_exit:
490         kfree(from_name);
491         kfree(to_name);
492         free_xid(xid);
493         cifs_put_tlink(tlink);
494         return rc;
495 }
496
497 void *
498 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
499 {
500         struct inode *inode = direntry->d_inode;
501         int rc = -ENOMEM;
502         unsigned int xid;
503         char *full_path = NULL;
504         char *target_path = NULL;
505         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
506         struct tcon_link *tlink = NULL;
507         struct cifs_tcon *tcon;
508         struct TCP_Server_Info *server;
509
510         xid = get_xid();
511
512         tlink = cifs_sb_tlink(cifs_sb);
513         if (IS_ERR(tlink)) {
514                 rc = PTR_ERR(tlink);
515                 tlink = NULL;
516                 goto out;
517         }
518         tcon = tlink_tcon(tlink);
519         server = tcon->ses->server;
520
521         full_path = build_path_from_dentry(direntry);
522         if (!full_path)
523                 goto out;
524
525         cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
526
527         rc = -EACCES;
528         /*
529          * First try Minshall+French Symlinks, if configured
530          * and fallback to UNIX Extensions Symlinks.
531          */
532         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
533                 rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
534                                         cifs_sb->local_nls,
535                                         cifs_sb->mnt_cifs_flags &
536                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
537
538         if ((rc != 0) && cap_unix(tcon->ses))
539                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
540                                              cifs_sb->local_nls);
541         else if (rc != 0 && server->ops->query_symlink)
542                 rc = server->ops->query_symlink(xid, tcon, full_path,
543                                                 &target_path, cifs_sb);
544
545         kfree(full_path);
546 out:
547         if (rc != 0) {
548                 kfree(target_path);
549                 target_path = ERR_PTR(rc);
550         }
551
552         free_xid(xid);
553         if (tlink)
554                 cifs_put_tlink(tlink);
555         nd_set_link(nd, target_path);
556         return NULL;
557 }
558
559 int
560 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
561 {
562         int rc = -EOPNOTSUPP;
563         unsigned int xid;
564         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
565         struct tcon_link *tlink;
566         struct cifs_tcon *pTcon;
567         char *full_path = NULL;
568         struct inode *newinode = NULL;
569
570         xid = get_xid();
571
572         tlink = cifs_sb_tlink(cifs_sb);
573         if (IS_ERR(tlink)) {
574                 rc = PTR_ERR(tlink);
575                 goto symlink_exit;
576         }
577         pTcon = tlink_tcon(tlink);
578
579         full_path = build_path_from_dentry(direntry);
580         if (full_path == NULL) {
581                 rc = -ENOMEM;
582                 goto symlink_exit;
583         }
584
585         cifs_dbg(FYI, "Full path: %s\n", full_path);
586         cifs_dbg(FYI, "symname is %s\n", symname);
587
588         /* BB what if DFS and this volume is on different share? BB */
589         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
590                 rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
591                                         cifs_sb);
592         else if (pTcon->unix_ext)
593                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
594                                            cifs_sb->local_nls);
595         /* else
596            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
597                                         cifs_sb_target->local_nls); */
598
599         if (rc == 0) {
600                 if (pTcon->unix_ext)
601                         rc = cifs_get_inode_info_unix(&newinode, full_path,
602                                                       inode->i_sb, xid);
603                 else
604                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
605                                                  inode->i_sb, xid, NULL);
606
607                 if (rc != 0) {
608                         cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
609                                  rc);
610                 } else {
611                         d_instantiate(direntry, newinode);
612                 }
613         }
614 symlink_exit:
615         kfree(full_path);
616         cifs_put_tlink(tlink);
617         free_xid(xid);
618         return rc;
619 }