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         if (tcon->ses->server->ops->create_mf_symlink)
 217                 rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
 218                                         cifs_sb, fromName, buf, &bytes_written);
 219         else
 220                 rc = -EOPNOTSUPP;
 221
 222         if (rc)
 223                 goto out;
 224
 225         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 226                 rc = -EIO;
 227 out:
 228         kfree(buf);
 229         return rc;
 230 }
 231
 232 static int
 233 query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 234                  struct cifs_sb_info *cifs_sb, const unsigned char *path,
 235                  char **symlinkinfo)
 236 {
 237         int rc;
 238         u8 *buf = NULL;
 239         unsigned int link_len = 0;
 240         unsigned int bytes_read = 0;
 241
 242         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 243         if (!buf)
 244                 return -ENOMEM;
 245
 246         if (tcon->ses->server->ops->query_mf_symlink)
 247                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 248                                               cifs_sb, path, buf, &bytes_read);
 249         else
 250                 rc = -ENOSYS;
 251
 252         if (rc)
 253                 goto out;
 254
 255         if (bytes_read == 0) { /* not a symlink */
 256                 rc = -EINVAL;
 257                 goto out;
 258         }
 259
 260         rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
 261 out:
 262         kfree(buf);
 263         return rc;
 264 }
 265
 266 int
 267 check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 268                  struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
 269                  const unsigned char *path)
 270 {
 271         int rc;
 272         u8 *buf = NULL;
 273         unsigned int link_len = 0;
 274         unsigned int bytes_read = 0;
 275
 276         if (!couldbe_mf_symlink(fattr))
 277                 /* it's not a symlink */
 278                 return 0;
 279
 280         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 281         if (!buf)
 282                 return -ENOMEM;
 283
 284         if (tcon->ses->server->ops->query_mf_symlink)
 285                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 286                                               cifs_sb, path, buf, &bytes_read);
 287         else
 288                 rc = -ENOSYS;
 289
 290         if (rc)
 291                 goto out;
 292
 293         if (bytes_read == 0) /* not a symlink */
 294                 goto out;
 295
 296         rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
 297         if (rc == -EINVAL) {
 298                 /* it's not a symlink */
 299                 rc = 0;
 300                 goto out;
 301         }
 302
 303         if (rc != 0)
 304                 goto out;
 305
 306         /* it is a symlink */
 307         fattr->cf_eof = link_len;
 308         fattr->cf_mode &= ~S_IFMT;
 309         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 310         fattr->cf_dtype = DT_LNK;
 311 out:
 312         kfree(buf);
 313         return rc;
 314 }
 315
 316 /*
 317  * SMB 1.0 Protocol specific functions
 318  */
 319
 320 int
 321 cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 322                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
 323                       char *pbuf, unsigned int *pbytes_read)
 324 {
 325         int rc;
 326         int oplock = 0;
 327         struct cifs_fid fid;
 328         struct cifs_open_parms oparms;
 329         struct cifs_io_parms io_parms;
 330         int buf_type = CIFS_NO_BUFFER;
 331         FILE_ALL_INFO file_info;
 332
 333         oparms.tcon = tcon;
 334         oparms.cifs_sb = cifs_sb;
 335         oparms.desired_access = GENERIC_READ;
 336         oparms.create_options = CREATE_NOT_DIR;
 337         oparms.disposition = FILE_OPEN;
 338         oparms.path = path;
 339         oparms.fid = &fid;
 340         oparms.reconnect = false;
 341
 342         rc = CIFS_open(xid, &oparms, &oplock, &file_info);
 343         if (rc)
 344                 return rc;
 345
 346         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE))
 347                 /* it's not a symlink */
 348                 goto out;
 349
 350         io_parms.netfid = fid.netfid;
 351         io_parms.pid = current->tgid;
 352         io_parms.tcon = tcon;
 353         io_parms.offset = 0;
 354         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 355
 356         rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
 357 out:
 358         CIFSSMBClose(xid, tcon, fid.netfid);
 359         return rc;
 360 }
 361
 362 int
 363 cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 364                        struct cifs_sb_info *cifs_sb, const unsigned char *path,
 365                        char *pbuf, unsigned int *pbytes_written)
 366 {
 367         int rc;
 368         int oplock = 0;
 369         struct cifs_fid fid;
 370         struct cifs_open_parms oparms;
 371         struct cifs_io_parms io_parms;
 372         int create_options = CREATE_NOT_DIR;
 373
 374         if (backup_cred(cifs_sb))
 375                 create_options |= CREATE_OPEN_BACKUP_INTENT;
 376
 377         oparms.tcon = tcon;
 378         oparms.cifs_sb = cifs_sb;
 379         oparms.desired_access = GENERIC_WRITE;
 380         oparms.create_options = create_options;
 381         oparms.disposition = FILE_CREATE;
 382         oparms.path = path;
 383         oparms.fid = &fid;
 384         oparms.reconnect = false;
 385
 386         rc = CIFS_open(xid, &oparms, &oplock, NULL);
 387         if (rc)
 388                 return rc;
 389
 390         io_parms.netfid = fid.netfid;
 391         io_parms.pid = current->tgid;
 392         io_parms.tcon = tcon;
 393         io_parms.offset = 0;
 394         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 395
 396         rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf, NULL, 0);
 397         CIFSSMBClose(xid, tcon, fid.netfid);
 398         return rc;
 399 }
 400
 401 /*
 402  * M-F Symlink Functions - End
 403  */
 404
 405 int
 406 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 407               struct dentry *direntry)
 408 {
 409         int rc = -EACCES;
 410         unsigned int xid;
 411         char *from_name = NULL;
 412         char *to_name = NULL;
 413         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 414         struct tcon_link *tlink;
 415         struct cifs_tcon *tcon;
 416         struct TCP_Server_Info *server;
 417         struct cifsInodeInfo *cifsInode;
 418
 419         tlink = cifs_sb_tlink(cifs_sb);
 420         if (IS_ERR(tlink))
 421                 return PTR_ERR(tlink);
 422         tcon = tlink_tcon(tlink);
 423
 424         xid = get_xid();
 425
 426         from_name = build_path_from_dentry(old_file);
 427         to_name = build_path_from_dentry(direntry);
 428         if ((from_name == NULL) || (to_name == NULL)) {
 429                 rc = -ENOMEM;
 430                 goto cifs_hl_exit;
 431         }
 432
 433         if (tcon->unix_ext)
 434                 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
 435                                             cifs_sb->local_nls,
 436                                             cifs_sb->mnt_cifs_flags &
 437                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 438         else {
 439                 server = tcon->ses->server;
 440                 if (!server->ops->create_hardlink) {
 441                         rc = -ENOSYS;
 442                         goto cifs_hl_exit;
 443                 }
 444                 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
 445                                                   cifs_sb);
 446                 if ((rc == -EIO) || (rc == -EINVAL))
 447                         rc = -EOPNOTSUPP;
 448         }
 449
 450         d_drop(direntry);       /* force new lookup from server of target */
 451
 452         /*
 453          * if source file is cached (oplocked) revalidate will not go to server
 454          * until the file is closed or oplock broken so update nlinks locally
 455          */
 456         if (old_file->d_inode) {
 457                 cifsInode = CIFS_I(old_file->d_inode);
 458                 if (rc == 0) {
 459                         spin_lock(&old_file->d_inode->i_lock);
 460                         inc_nlink(old_file->d_inode);
 461                         spin_unlock(&old_file->d_inode->i_lock);
 462                         /*
 463                          * BB should we make this contingent on superblock flag
 464                          * NOATIME?
 465                          */
 466                         /* old_file->d_inode->i_ctime = CURRENT_TIME; */
 467                         /*
 468                          * parent dir timestamps will update from srv within a
 469                          * second, would it really be worth it to set the parent
 470                          * dir cifs inode time to zero to force revalidate
 471                          * (faster) for it too?
 472                          */
 473                 }
 474                 /*
 475                  * if not oplocked will force revalidate to get info on source
 476                  * file from srv
 477                  */
 478                 cifsInode->time = 0;
 479
 480                 /*
 481                  * Will update parent dir timestamps from srv within a second.
 482                  * Would it really be worth it to set the parent dir (cifs
 483                  * inode) time field to zero to force revalidate on parent
 484                  * directory faster ie
 485                  *
 486                  * CIFS_I(inode)->time = 0;
 487                  */
 488         }
 489
 490 cifs_hl_exit:
 491         kfree(from_name);
 492         kfree(to_name);
 493         free_xid(xid);
 494         cifs_put_tlink(tlink);
 495         return rc;
 496 }
 497
 498 void *
 499 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 500 {
 501         struct inode *inode = direntry->d_inode;
 502         int rc = -ENOMEM;
 503         unsigned int xid;
 504         char *full_path = NULL;
 505         char *target_path = NULL;
 506         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 507         struct tcon_link *tlink = NULL;
 508         struct cifs_tcon *tcon;
 509         struct TCP_Server_Info *server;
 510
 511         xid = get_xid();
 512
 513         tlink = cifs_sb_tlink(cifs_sb);
 514         if (IS_ERR(tlink)) {
 515                 rc = PTR_ERR(tlink);
 516                 tlink = NULL;
 517                 goto out;
 518         }
 519         tcon = tlink_tcon(tlink);
 520         server = tcon->ses->server;
 521
 522         full_path = build_path_from_dentry(direntry);
 523         if (!full_path)
 524                 goto out;
 525
 526         cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
 527
 528         rc = -EACCES;
 529         /*
 530          * First try Minshall+French Symlinks, if configured
 531          * and fallback to UNIX Extensions Symlinks.
 532          */
 533         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 534                 rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
 535                                       &target_path);
 536
 537         if (rc != 0 && server->ops->query_symlink)
 538                 rc = server->ops->query_symlink(xid, tcon, full_path,
 539                                                 &target_path, cifs_sb);
 540
 541         kfree(full_path);
 542 out:
 543         if (rc != 0) {
 544                 kfree(target_path);
 545                 target_path = ERR_PTR(rc);
 546         }
 547
 548         free_xid(xid);
 549         if (tlink)
 550                 cifs_put_tlink(tlink);
 551         nd_set_link(nd, target_path);
 552         return NULL;
 553 }
 554
 555 int
 556 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 557 {
 558         int rc = -EOPNOTSUPP;
 559         unsigned int xid;
 560         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 561         struct tcon_link *tlink;
 562         struct cifs_tcon *pTcon;
 563         char *full_path = NULL;
 564         struct inode *newinode = NULL;
 565
 566         xid = get_xid();
 567
 568         tlink = cifs_sb_tlink(cifs_sb);
 569         if (IS_ERR(tlink)) {
 570                 rc = PTR_ERR(tlink);
 571                 goto symlink_exit;
 572         }
 573         pTcon = tlink_tcon(tlink);
 574
 575         full_path = build_path_from_dentry(direntry);
 576         if (full_path == NULL) {
 577                 rc = -ENOMEM;
 578                 goto symlink_exit;
 579         }
 580
 581         cifs_dbg(FYI, "Full path: %s\n", full_path);
 582         cifs_dbg(FYI, "symname is %s\n", symname);
 583
 584         /* BB what if DFS and this volume is on different share? BB */
 585         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 586                 rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
 587         else if (pTcon->unix_ext)
 588                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 589                                            cifs_sb->local_nls);
 590         /* else
 591            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 592                                         cifs_sb_target->local_nls); */
 593
 594         if (rc == 0) {
 595                 if (pTcon->unix_ext)
 596                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 597                                                       inode->i_sb, xid);
 598                 else
 599                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 600                                                  inode->i_sb, xid, NULL);
 601
 602                 if (rc != 0) {
 603                         cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
 604                                  rc);
 605                 } else {
 606                         d_instantiate(direntry, newinode);
 607                 }
 608         }
 609 symlink_exit:
 610         kfree(full_path);
 611         cifs_put_tlink(tlink);
 612         free_xid(xid);
 613         return rc;
 614 }