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 /*
  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
  52 static int
  53 symlink_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
  90 symlink_hash_err:
  91         crypto_free_shash(md5);
  92         kfree(sdescmd5);
  93
  94         return rc;
  95 }
  96
  97 static int
  98 parse_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
 141 static int
 142 format_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
 185 bool
 186 couldbe_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
 199 static int
 200 create_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;
 223 out:
 224         kfree(buf);
 225         return rc;
 226 }
 227
 228 static int
 229 query_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);
 257 out:
 258         kfree(buf);
 259         return rc;
 260 }
 261
 262 int
 263 check_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;
 307 out:
 308         kfree(buf);
 309         return rc;
 310 }
 311
 312 /*
 313  * SMB 1.0 Protocol specific functions
 314  */
 315
 316 int
 317 cifs_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);
 353 out:
 354         CIFSSMBClose(xid, tcon, fid.netfid);
 355         return rc;
 356 }
 357
 358 int
 359 cifs_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
 401 int
 402 cifs_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
 486 cifs_hl_exit:
 487         kfree(from_name);
 488         kfree(to_name);
 489         free_xid(xid);
 490         cifs_put_tlink(tlink);
 491         return rc;
 492 }
 493
 494 void *
 495 cifs_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);
 538 out:
 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
 551 int
 552 cifs_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         }
 605 symlink_exit:
 606         kfree(full_path);
 607         cifs_put_tlink(tlink);
 608         free_xid(xid);
 609         return rc;
 610 }