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                 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 parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
  95                  char **_link_str)
  96 {
  97         int rc;
  98         unsigned int link_len;
  99         const char *md5_str1;
 100         const char *link_str;
 101         u8 md5_hash[16];
 102         char md5_str2[34];
 103
 104         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 105                 return -EINVAL;
 106
 107         md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
 108         link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
 109
 110         rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
 111         if (rc != 1)
 112                 return -EINVAL;
 113
 114         rc = symlink_hash(link_len, link_str, md5_hash);
 115         if (rc) {
 116                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
 117                 return rc;
 118         }
 119
 120         snprintf(md5_str2, sizeof(md5_str2),
 121                  CIFS_MF_SYMLINK_MD5_FORMAT,
 122                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 123
 124         if (strncmp(md5_str1, md5_str2, 17) != 0)
 125                 return -EINVAL;
 126
 127         if (_link_str) {
 128                 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
 129                 if (!*_link_str)
 130                         return -ENOMEM;
 131         }
 132
 133         *_link_len = link_len;
 134         return 0;
 135 }
 136
 137 static int
 138 format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
 139 {
 140         int rc;
 141         unsigned int link_len;
 142         unsigned int ofs;
 143         u8 md5_hash[16];
 144
 145         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 146                 return -EINVAL;
 147
 148         link_len = strlen(link_str);
 149
 150         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
 151                 return -ENAMETOOLONG;
 152
 153         rc = symlink_hash(link_len, link_str, md5_hash);
 154         if (rc) {
 155                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
 156                 return rc;
 157         }
 158
 159         snprintf(buf, buf_len,
 160                  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
 161                  link_len,
 162                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 163
 164         ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 165         memcpy(buf + ofs, link_str, link_len);
 166
 167         ofs += link_len;
 168         if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 169                 buf[ofs] = '\n';
 170                 ofs++;
 171         }
 172
 173         while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 174                 buf[ofs] = ' ';
 175                 ofs++;
 176         }
 177
 178         return 0;
 179 }
 180
 181 static int
 182 create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 183                   struct cifs_sb_info *cifs_sb, const char *fromName,
 184                   const char *toName)
 185 {
 186         int rc;
 187         u8 *buf;
 188         unsigned int bytes_written = 0;
 189
 190         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 191         if (!buf)
 192                 return -ENOMEM;
 193
 194         rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 195         if (rc)
 196                 goto out;
 197
 198         rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon, cifs_sb,
 199                                         fromName, buf, &bytes_written);
 200         if (rc)
 201                 goto out;
 202
 203         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 204                 rc = -EIO;
 205 out:
 206         kfree(buf);
 207         return rc;
 208 }
 209
 210 static int
 211 query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 212                  struct cifs_sb_info *cifs_sb, const unsigned char *path,
 213                  char **symlinkinfo)
 214 {
 215         int rc;
 216         u8 *buf = NULL;
 217         unsigned int link_len = 0;
 218         unsigned int bytes_read = 0;
 219
 220         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 221         if (!buf)
 222                 return -ENOMEM;
 223
 224         if (tcon->ses->server->ops->query_mf_symlink)
 225                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 226                                               cifs_sb, path, buf, &bytes_read);
 227         else
 228                 rc = -ENOSYS;
 229
 230         if (rc)
 231                 goto out;
 232
 233         if (bytes_read == 0) { /* not a symlink */
 234                 rc = -EINVAL;
 235                 goto out;
 236         }
 237
 238         rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
 239 out:
 240         kfree(buf);
 241         return rc;
 242 }
 243
 244 bool
 245 couldbe_mf_symlink(const struct cifs_fattr *fattr)
 246 {
 247         if (!(fattr->cf_mode & S_IFREG))
 248                 /* it's not a symlink */
 249                 return false;
 250
 251         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 252                 /* it's not a symlink */
 253                 return false;
 254
 255         return true;
 256 }
 257
 258 int
 259 cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 260                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
 261                       char *pbuf, unsigned int *pbytes_read)
 262 {
 263         int rc;
 264         int oplock = 0;
 265         __u16 netfid = 0;
 266         struct cifs_io_parms io_parms;
 267         int buf_type = CIFS_NO_BUFFER;
 268         FILE_ALL_INFO file_info;
 269
 270         rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, GENERIC_READ,
 271                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 272                          cifs_sb->local_nls,
 273                          cifs_sb->mnt_cifs_flags &
 274                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 275         if (rc)
 276                 return rc;
 277
 278         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE))
 279                 /* it's not a symlink */
 280                 goto out;
 281
 282         io_parms.netfid = netfid;
 283         io_parms.pid = current->tgid;
 284         io_parms.tcon = tcon;
 285         io_parms.offset = 0;
 286         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 287
 288         rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
 289 out:
 290         CIFSSMBClose(xid, tcon, netfid);
 291         return rc;
 292 }
 293
 294 int
 295 cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 296                        struct cifs_sb_info *cifs_sb, const unsigned char *path,
 297                        char *pbuf, unsigned int *pbytes_written)
 298 {
 299         int rc;
 300         int oplock = 0;
 301         __u16 netfid = 0;
 302         struct cifs_io_parms io_parms;
 303         int create_options = CREATE_NOT_DIR;
 304
 305         if (backup_cred(cifs_sb))
 306                 create_options |= CREATE_OPEN_BACKUP_INTENT;
 307
 308         rc = CIFSSMBOpen(xid, tcon, path, FILE_CREATE, GENERIC_WRITE,
 309                          create_options, &netfid, &oplock, NULL,
 310                          cifs_sb->local_nls,
 311                          cifs_sb->mnt_cifs_flags &
 312                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 313         if (rc)
 314                 return rc;
 315
 316         io_parms.netfid = netfid;
 317         io_parms.pid = current->tgid;
 318         io_parms.tcon = tcon;
 319         io_parms.offset = 0;
 320         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 321
 322         rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf, NULL, 0);
 323         CIFSSMBClose(xid, tcon, netfid);
 324         return rc;
 325 }
 326
 327 int
 328 check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 329                  struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
 330                  const unsigned char *path)
 331 {
 332         int rc;
 333         u8 *buf = NULL;
 334         unsigned int link_len = 0;
 335         unsigned int bytes_read = 0;
 336
 337         if (!couldbe_mf_symlink(fattr))
 338                 /* it's not a symlink */
 339                 return 0;
 340
 341         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 342         if (!buf)
 343                 return -ENOMEM;
 344
 345         if (tcon->ses->server->ops->query_mf_symlink)
 346                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 347                                               cifs_sb, path, buf, &bytes_read);
 348         else
 349                 rc = -ENOSYS;
 350
 351         if (rc)
 352                 goto out;
 353
 354         if (bytes_read == 0) /* not a symlink */
 355                 goto out;
 356
 357         rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
 358         if (rc == -EINVAL) {
 359                 /* it's not a symlink */
 360                 rc = 0;
 361                 goto out;
 362         }
 363
 364         if (rc != 0)
 365                 goto out;
 366
 367         /* it is a symlink */
 368         fattr->cf_eof = link_len;
 369         fattr->cf_mode &= ~S_IFMT;
 370         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 371         fattr->cf_dtype = DT_LNK;
 372 out:
 373         kfree(buf);
 374         return rc;
 375 }
 376
 377 int
 378 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 379               struct dentry *direntry)
 380 {
 381         int rc = -EACCES;
 382         unsigned int xid;
 383         char *from_name = NULL;
 384         char *to_name = NULL;
 385         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 386         struct tcon_link *tlink;
 387         struct cifs_tcon *tcon;
 388         struct TCP_Server_Info *server;
 389         struct cifsInodeInfo *cifsInode;
 390
 391         tlink = cifs_sb_tlink(cifs_sb);
 392         if (IS_ERR(tlink))
 393                 return PTR_ERR(tlink);
 394         tcon = tlink_tcon(tlink);
 395
 396         xid = get_xid();
 397
 398         from_name = build_path_from_dentry(old_file);
 399         to_name = build_path_from_dentry(direntry);
 400         if ((from_name == NULL) || (to_name == NULL)) {
 401                 rc = -ENOMEM;
 402                 goto cifs_hl_exit;
 403         }
 404
 405         if (tcon->unix_ext)
 406                 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
 407                                             cifs_sb->local_nls,
 408                                             cifs_sb->mnt_cifs_flags &
 409                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 410         else {
 411                 server = tcon->ses->server;
 412                 if (!server->ops->create_hardlink) {
 413                         rc = -ENOSYS;
 414                         goto cifs_hl_exit;
 415                 }
 416                 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
 417                                                   cifs_sb);
 418                 if ((rc == -EIO) || (rc == -EINVAL))
 419                         rc = -EOPNOTSUPP;
 420         }
 421
 422         d_drop(direntry);       /* force new lookup from server of target */
 423
 424         /*
 425          * if source file is cached (oplocked) revalidate will not go to server
 426          * until the file is closed or oplock broken so update nlinks locally
 427          */
 428         if (old_file->d_inode) {
 429                 cifsInode = CIFS_I(old_file->d_inode);
 430                 if (rc == 0) {
 431                         spin_lock(&old_file->d_inode->i_lock);
 432                         inc_nlink(old_file->d_inode);
 433                         spin_unlock(&old_file->d_inode->i_lock);
 434                         /*
 435                          * BB should we make this contingent on superblock flag
 436                          * NOATIME?
 437                          */
 438                         /* old_file->d_inode->i_ctime = CURRENT_TIME; */
 439                         /*
 440                          * parent dir timestamps will update from srv within a
 441                          * second, would it really be worth it to set the parent
 442                          * dir cifs inode time to zero to force revalidate
 443                          * (faster) for it too?
 444                          */
 445                 }
 446                 /*
 447                  * if not oplocked will force revalidate to get info on source
 448                  * file from srv
 449                  */
 450                 cifsInode->time = 0;
 451
 452                 /*
 453                  * Will update parent dir timestamps from srv within a second.
 454                  * Would it really be worth it to set the parent dir (cifs
 455                  * inode) time field to zero to force revalidate on parent
 456                  * directory faster ie
 457                  *
 458                  * CIFS_I(inode)->time = 0;
 459                  */
 460         }
 461
 462 cifs_hl_exit:
 463         kfree(from_name);
 464         kfree(to_name);
 465         free_xid(xid);
 466         cifs_put_tlink(tlink);
 467         return rc;
 468 }
 469
 470 void *
 471 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 472 {
 473         struct inode *inode = direntry->d_inode;
 474         int rc = -ENOMEM;
 475         unsigned int xid;
 476         char *full_path = NULL;
 477         char *target_path = NULL;
 478         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 479         struct tcon_link *tlink = NULL;
 480         struct cifs_tcon *tcon;
 481         struct TCP_Server_Info *server;
 482
 483         xid = get_xid();
 484
 485         tlink = cifs_sb_tlink(cifs_sb);
 486         if (IS_ERR(tlink)) {
 487                 rc = PTR_ERR(tlink);
 488                 tlink = NULL;
 489                 goto out;
 490         }
 491         tcon = tlink_tcon(tlink);
 492         server = tcon->ses->server;
 493
 494         full_path = build_path_from_dentry(direntry);
 495         if (!full_path)
 496                 goto out;
 497
 498         cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
 499
 500         rc = -EACCES;
 501         /*
 502          * First try Minshall+French Symlinks, if configured
 503          * and fallback to UNIX Extensions Symlinks.
 504          */
 505         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 506                 rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
 507                                       &target_path);
 508
 509         if ((rc != 0) && cap_unix(tcon->ses))
 510                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 511                                              cifs_sb->local_nls);
 512         else if (rc != 0 && server->ops->query_symlink)
 513                 rc = server->ops->query_symlink(xid, tcon, full_path,
 514                                                 &target_path, cifs_sb);
 515
 516         kfree(full_path);
 517 out:
 518         if (rc != 0) {
 519                 kfree(target_path);
 520                 target_path = ERR_PTR(rc);
 521         }
 522
 523         free_xid(xid);
 524         if (tlink)
 525                 cifs_put_tlink(tlink);
 526         nd_set_link(nd, target_path);
 527         return NULL;
 528 }
 529
 530 int
 531 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 532 {
 533         int rc = -EOPNOTSUPP;
 534         unsigned int xid;
 535         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 536         struct tcon_link *tlink;
 537         struct cifs_tcon *pTcon;
 538         char *full_path = NULL;
 539         struct inode *newinode = NULL;
 540
 541         xid = get_xid();
 542
 543         tlink = cifs_sb_tlink(cifs_sb);
 544         if (IS_ERR(tlink)) {
 545                 rc = PTR_ERR(tlink);
 546                 goto symlink_exit;
 547         }
 548         pTcon = tlink_tcon(tlink);
 549
 550         full_path = build_path_from_dentry(direntry);
 551         if (full_path == NULL) {
 552                 rc = -ENOMEM;
 553                 goto symlink_exit;
 554         }
 555
 556         cifs_dbg(FYI, "Full path: %s\n", full_path);
 557         cifs_dbg(FYI, "symname is %s\n", symname);
 558
 559         /* BB what if DFS and this volume is on different share? BB */
 560         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 561                 rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
 562         else if (pTcon->unix_ext)
 563                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 564                                            cifs_sb->local_nls);
 565         /* else
 566            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 567                                         cifs_sb_target->local_nls); */
 568
 569         if (rc == 0) {
 570                 if (pTcon->unix_ext)
 571                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 572                                                       inode->i_sb, xid);
 573                 else
 574                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 575                                                  inode->i_sb, xid, NULL);
 576
 577                 if (rc != 0) {
 578                         cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
 579                                  rc);
 580                 } else {
 581                         d_instantiate(direntry, newinode);
 582                 }
 583         }
 584 symlink_exit:
 585         kfree(full_path);
 586         cifs_put_tlink(tlink);
 587         free_xid(xid);
 588         return rc;
 589 }