fs/cifs/link.c

   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                 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
  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                 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
 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                 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
 183 static int
 184 CIFSCreateMFSymLink(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
 240 static int
 241 CIFSQueryMFSymLink(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
 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 CIFSCheckMFSymlink(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;
 383 out:
 384         cifs_put_tlink(tlink);
 385         return rc;
 386 }
 387
 388 int
 389 cifs_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
 455 cifs_hl_exit:
 456         kfree(fromName);
 457         kfree(toName);
 458         FreeXid(xid);
 459         cifs_put_tlink(tlink);
 460         return rc;
 461 }
 462
 463 void *
 464 cifs_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);
 526 out:
 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
 539 int
 540 cifs_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         }
 594 symlink_exit:
 595         kfree(full_path);
 596         cifs_put_tlink(tlink);
 597         FreeXid(xid);
 598         return rc;
 599 }
 600
 601 void 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 }