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         crypto_shash_update(&sdescmd5->shash, link_str, link_len);
  78         rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
  79
  80 symlink_hash_err:
  81         crypto_free_shash(md5);
  82         kfree(sdescmd5);
  83
  84         return rc;
  85 }
  86
  87 static int
  88 CIFSParseMFSymlink(const u8 *buf,
  89                    unsigned int buf_len,
  90                    unsigned int *_link_len,
  91                    char **_link_str)
  92 {
  93         int rc;
  94         unsigned int link_len;
  95         const char *md5_str1;
  96         const char *link_str;
  97         u8 md5_hash[16];
  98         char md5_str2[34];
  99
 100         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 101                 return -EINVAL;
 102
 103         md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
 104         link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
 105
 106         rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
 107         if (rc != 1)
 108                 return -EINVAL;
 109
 110         rc = symlink_hash(link_len, link_str, md5_hash);
 111         if (rc) {
 112                 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
 113                 return rc;
 114         }
 115
 116         snprintf(md5_str2, sizeof(md5_str2),
 117                  CIFS_MF_SYMLINK_MD5_FORMAT,
 118                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 119
 120         if (strncmp(md5_str1, md5_str2, 17) != 0)
 121                 return -EINVAL;
 122
 123         if (_link_str) {
 124                 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
 125                 if (!*_link_str)
 126                         return -ENOMEM;
 127         }
 128
 129         *_link_len = link_len;
 130         return 0;
 131 }
 132
 133 static int
 134 CIFSFormatMFSymlink(u8 *buf, unsigned int buf_len, const char *link_str)
 135 {
 136         int rc;
 137         unsigned int link_len;
 138         unsigned int ofs;
 139         u8 md5_hash[16];
 140
 141         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 142                 return -EINVAL;
 143
 144         link_len = strlen(link_str);
 145
 146         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
 147                 return -ENAMETOOLONG;
 148
 149         rc = symlink_hash(link_len, link_str, md5_hash);
 150         if (rc) {
 151                 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
 152                 return rc;
 153         }
 154
 155         snprintf(buf, buf_len,
 156                  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
 157                  link_len,
 158                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 159
 160         ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 161         memcpy(buf + ofs, link_str, link_len);
 162
 163         ofs += link_len;
 164         if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 165                 buf[ofs] = '\n';
 166                 ofs++;
 167         }
 168
 169         while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 170                 buf[ofs] = ' ';
 171                 ofs++;
 172         }
 173
 174         return 0;
 175 }
 176
 177 static int
 178 CIFSCreateMFSymLink(const int xid, struct cifs_tcon *tcon,
 179                     const char *fromName, const char *toName,
 180                     const struct nls_table *nls_codepage, int remap)
 181 {
 182         int rc;
 183         int oplock = 0;
 184         __u16 netfid = 0;
 185         u8 *buf;
 186         unsigned int bytes_written = 0;
 187         struct cifs_io_parms io_parms;
 188
 189         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 190         if (!buf)
 191                 return -ENOMEM;
 192
 193         rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 194         if (rc != 0) {
 195                 kfree(buf);
 196                 return rc;
 197         }
 198
 199         rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
 200                          CREATE_NOT_DIR, &netfid, &oplock, NULL,
 201                          nls_codepage, remap);
 202         if (rc != 0) {
 203                 kfree(buf);
 204                 return rc;
 205         }
 206
 207         io_parms.netfid = netfid;
 208         io_parms.pid = current->tgid;
 209         io_parms.tcon = tcon;
 210         io_parms.offset = 0;
 211         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 212
 213         rc = CIFSSMBWrite(xid, &io_parms, &bytes_written, buf, NULL, 0);
 214         CIFSSMBClose(xid, tcon, netfid);
 215         kfree(buf);
 216         if (rc != 0)
 217                 return rc;
 218
 219         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 220                 return -EIO;
 221
 222         return 0;
 223 }
 224
 225 static int
 226 CIFSQueryMFSymLink(const int xid, struct cifs_tcon *tcon,
 227                    const unsigned char *searchName, char **symlinkinfo,
 228                    const struct nls_table *nls_codepage, int remap)
 229 {
 230         int rc;
 231         int oplock = 0;
 232         __u16 netfid = 0;
 233         u8 *buf;
 234         char *pbuf;
 235         unsigned int bytes_read = 0;
 236         int buf_type = CIFS_NO_BUFFER;
 237         unsigned int link_len = 0;
 238         struct cifs_io_parms io_parms;
 239         FILE_ALL_INFO file_info;
 240
 241         rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
 242                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 243                          nls_codepage, remap);
 244         if (rc != 0)
 245                 return rc;
 246
 247         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 248                 CIFSSMBClose(xid, tcon, netfid);
 249                 /* it's not a symlink */
 250                 return -EINVAL;
 251         }
 252
 253         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 254         if (!buf)
 255                 return -ENOMEM;
 256         pbuf = buf;
 257         io_parms.netfid = netfid;
 258         io_parms.pid = current->tgid;
 259         io_parms.tcon = tcon;
 260         io_parms.offset = 0;
 261         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 262
 263         rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 264         CIFSSMBClose(xid, tcon, netfid);
 265         if (rc != 0) {
 266                 kfree(buf);
 267                 return rc;
 268         }
 269
 270         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
 271         kfree(buf);
 272         if (rc != 0)
 273                 return rc;
 274
 275         return 0;
 276 }
 277
 278 bool
 279 CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
 280 {
 281         if (!(fattr->cf_mode & S_IFREG))
 282                 /* it's not a symlink */
 283                 return false;
 284
 285         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 286                 /* it's not a symlink */
 287                 return false;
 288
 289         return true;
 290 }
 291
 292 int
 293 CIFSCheckMFSymlink(struct cifs_fattr *fattr,
 294                    const unsigned char *path,
 295                    struct cifs_sb_info *cifs_sb, int xid)
 296 {
 297         int rc;
 298         int oplock = 0;
 299         __u16 netfid = 0;
 300         struct tcon_link *tlink;
 301         struct cifs_tcon *pTcon;
 302         struct cifs_io_parms io_parms;
 303         u8 *buf;
 304         char *pbuf;
 305         unsigned int bytes_read = 0;
 306         int buf_type = CIFS_NO_BUFFER;
 307         unsigned int link_len = 0;
 308         FILE_ALL_INFO file_info;
 309
 310         if (!CIFSCouldBeMFSymlink(fattr))
 311                 /* it's not a symlink */
 312                 return 0;
 313
 314         tlink = cifs_sb_tlink(cifs_sb);
 315         if (IS_ERR(tlink))
 316                 return PTR_ERR(tlink);
 317         pTcon = tlink_tcon(tlink);
 318
 319         rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
 320                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 321                          cifs_sb->local_nls,
 322                          cifs_sb->mnt_cifs_flags &
 323                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 324         if (rc != 0)
 325                 goto out;
 326
 327         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 328                 CIFSSMBClose(xid, pTcon, netfid);
 329                 /* it's not a symlink */
 330                 goto out;
 331         }
 332
 333         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 334         if (!buf) {
 335                 rc = -ENOMEM;
 336                 goto out;
 337         }
 338         pbuf = buf;
 339         io_parms.netfid = netfid;
 340         io_parms.pid = current->tgid;
 341         io_parms.tcon = pTcon;
 342         io_parms.offset = 0;
 343         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 344
 345         rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 346         CIFSSMBClose(xid, pTcon, netfid);
 347         if (rc != 0) {
 348                 kfree(buf);
 349                 goto out;
 350         }
 351
 352         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
 353         kfree(buf);
 354         if (rc == -EINVAL) {
 355                 /* it's not a symlink */
 356                 rc = 0;
 357                 goto out;
 358         }
 359
 360         if (rc != 0)
 361                 goto out;
 362
 363         /* it is a symlink */
 364         fattr->cf_eof = link_len;
 365         fattr->cf_mode &= ~S_IFMT;
 366         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 367         fattr->cf_dtype = DT_LNK;
 368 out:
 369         cifs_put_tlink(tlink);
 370         return rc;
 371 }
 372
 373 int
 374 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 375               struct dentry *direntry)
 376 {
 377         int rc = -EACCES;
 378         int xid;
 379         char *fromName = NULL;
 380         char *toName = NULL;
 381         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 382         struct tcon_link *tlink;
 383         struct cifs_tcon *pTcon;
 384         struct cifsInodeInfo *cifsInode;
 385
 386         tlink = cifs_sb_tlink(cifs_sb);
 387         if (IS_ERR(tlink))
 388                 return PTR_ERR(tlink);
 389         pTcon = tlink_tcon(tlink);
 390
 391         xid = GetXid();
 392
 393         fromName = build_path_from_dentry(old_file);
 394         toName = build_path_from_dentry(direntry);
 395         if ((fromName == NULL) || (toName == NULL)) {
 396                 rc = -ENOMEM;
 397                 goto cifs_hl_exit;
 398         }
 399
 400         if (pTcon->unix_ext)
 401                 rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
 402                                             cifs_sb->local_nls,
 403                                             cifs_sb->mnt_cifs_flags &
 404                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 405         else {
 406                 rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
 407                                         cifs_sb->local_nls,
 408                                         cifs_sb->mnt_cifs_flags &
 409                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 410                 if ((rc == -EIO) || (rc == -EINVAL))
 411                         rc = -EOPNOTSUPP;
 412         }
 413
 414         d_drop(direntry);       /* force new lookup from server of target */
 415
 416         /* if source file is cached (oplocked) revalidate will not go to server
 417            until the file is closed or oplock broken so update nlinks locally */
 418         if (old_file->d_inode) {
 419                 cifsInode = CIFS_I(old_file->d_inode);
 420                 if (rc == 0) {
 421                         old_file->d_inode->i_nlink++;
 422 /* BB should we make this contingent on superblock flag NOATIME? */
 423 /*                      old_file->d_inode->i_ctime = CURRENT_TIME;*/
 424                         /* parent dir timestamps will update from srv
 425                         within a second, would it really be worth it
 426                         to set the parent dir cifs inode time to zero
 427                         to force revalidate (faster) for it too? */
 428                 }
 429                 /* if not oplocked will force revalidate to get info
 430                    on source file from srv */
 431                 cifsInode->time = 0;
 432
 433                 /* Will update parent dir timestamps from srv within a second.
 434                    Would it really be worth it to set the parent dir (cifs
 435                    inode) time field to zero to force revalidate on parent
 436                    directory faster ie
 437                         CIFS_I(inode)->time = 0;  */
 438         }
 439
 440 cifs_hl_exit:
 441         kfree(fromName);
 442         kfree(toName);
 443         FreeXid(xid);
 444         cifs_put_tlink(tlink);
 445         return rc;
 446 }
 447
 448 void *
 449 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 450 {
 451         struct inode *inode = direntry->d_inode;
 452         int rc = -ENOMEM;
 453         int xid;
 454         char *full_path = NULL;
 455         char *target_path = NULL;
 456         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 457         struct tcon_link *tlink = NULL;
 458         struct cifs_tcon *tcon;
 459
 460         xid = GetXid();
 461
 462         tlink = cifs_sb_tlink(cifs_sb);
 463         if (IS_ERR(tlink)) {
 464                 rc = PTR_ERR(tlink);
 465                 tlink = NULL;
 466                 goto out;
 467         }
 468         tcon = tlink_tcon(tlink);
 469
 470         /*
 471          * For now, we just handle symlinks with unix extensions enabled.
 472          * Eventually we should handle NTFS reparse points, and MacOS
 473          * symlink support. For instance...
 474          *
 475          * rc = CIFSSMBQueryReparseLinkInfo(...)
 476          *
 477          * For now, just return -EACCES when the server doesn't support posix
 478          * extensions. Note that we still allow querying symlinks when posix
 479          * extensions are manually disabled. We could disable these as well
 480          * but there doesn't seem to be any harm in allowing the client to
 481          * read them.
 482          */
 483         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 484             && !(tcon->ses->capabilities & CAP_UNIX)) {
 485                 rc = -EACCES;
 486                 goto out;
 487         }
 488
 489         full_path = build_path_from_dentry(direntry);
 490         if (!full_path)
 491                 goto out;
 492
 493         cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
 494
 495         rc = -EACCES;
 496         /*
 497          * First try Minshall+French Symlinks, if configured
 498          * and fallback to UNIX Extensions Symlinks.
 499          */
 500         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 501                 rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
 502                                         cifs_sb->local_nls,
 503                                         cifs_sb->mnt_cifs_flags &
 504                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 505
 506         if ((rc != 0) && (tcon->ses->capabilities & CAP_UNIX))
 507                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 508                                              cifs_sb->local_nls);
 509
 510         kfree(full_path);
 511 out:
 512         if (rc != 0) {
 513                 kfree(target_path);
 514                 target_path = ERR_PTR(rc);
 515         }
 516
 517         FreeXid(xid);
 518         if (tlink)
 519                 cifs_put_tlink(tlink);
 520         nd_set_link(nd, target_path);
 521         return NULL;
 522 }
 523
 524 int
 525 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 526 {
 527         int rc = -EOPNOTSUPP;
 528         int xid;
 529         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 530         struct tcon_link *tlink;
 531         struct cifs_tcon *pTcon;
 532         char *full_path = NULL;
 533         struct inode *newinode = NULL;
 534
 535         xid = GetXid();
 536
 537         tlink = cifs_sb_tlink(cifs_sb);
 538         if (IS_ERR(tlink)) {
 539                 rc = PTR_ERR(tlink);
 540                 goto symlink_exit;
 541         }
 542         pTcon = tlink_tcon(tlink);
 543
 544         full_path = build_path_from_dentry(direntry);
 545         if (full_path == NULL) {
 546                 rc = -ENOMEM;
 547                 goto symlink_exit;
 548         }
 549
 550         cFYI(1, "Full path: %s", full_path);
 551         cFYI(1, "symname is %s", symname);
 552
 553         /* BB what if DFS and this volume is on different share? BB */
 554         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 555                 rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
 556                                          cifs_sb->local_nls,
 557                                          cifs_sb->mnt_cifs_flags &
 558                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 559         else if (pTcon->unix_ext)
 560                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 561                                            cifs_sb->local_nls);
 562         /* else
 563            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 564                                         cifs_sb_target->local_nls); */
 565
 566         if (rc == 0) {
 567                 if (pTcon->unix_ext)
 568                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 569                                                       inode->i_sb, xid);
 570                 else
 571                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 572                                                  inode->i_sb, xid, NULL);
 573
 574                 if (rc != 0) {
 575                         cFYI(1, "Create symlink ok, getinodeinfo fail rc = %d",
 576                               rc);
 577                 } else {
 578                         d_instantiate(direntry, newinode);
 579                 }
 580         }
 581 symlink_exit:
 582         kfree(full_path);
 583         cifs_put_tlink(tlink);
 584         FreeXid(xid);
 585         return rc;
 586 }
 587
 588 void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
 589 {
 590         char *p = nd_get_link(nd);
 591         if (!IS_ERR(p))
 592                 kfree(p);
 593 }