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                     const struct nls_table *nls_codepage, int remap)
 187 {
 188         int rc;
 189         int oplock = 0;
 190         __u16 netfid = 0;
 191         u8 *buf;
 192         unsigned int bytes_written = 0;
 193         struct cifs_io_parms io_parms;
 194
 195         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 196         if (!buf)
 197                 return -ENOMEM;
 198
 199         rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 200         if (rc != 0) {
 201                 kfree(buf);
 202                 return rc;
 203         }
 204
 205         rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
 206                          CREATE_NOT_DIR, &netfid, &oplock, NULL,
 207                          nls_codepage, remap);
 208         if (rc != 0) {
 209                 kfree(buf);
 210                 return rc;
 211         }
 212
 213         io_parms.netfid = netfid;
 214         io_parms.pid = current->tgid;
 215         io_parms.tcon = tcon;
 216         io_parms.offset = 0;
 217         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 218
 219         rc = CIFSSMBWrite(xid, &io_parms, &bytes_written, buf, NULL, 0);
 220         CIFSSMBClose(xid, tcon, netfid);
 221         kfree(buf);
 222         if (rc != 0)
 223                 return rc;
 224
 225         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 226                 return -EIO;
 227
 228         return 0;
 229 }
 230
 231 static int
 232 CIFSQueryMFSymLink(const int xid, struct cifs_tcon *tcon,
 233                    const unsigned char *searchName, char **symlinkinfo,
 234                    const struct nls_table *nls_codepage, int remap)
 235 {
 236         int rc;
 237         int oplock = 0;
 238         __u16 netfid = 0;
 239         u8 *buf;
 240         char *pbuf;
 241         unsigned int bytes_read = 0;
 242         int buf_type = CIFS_NO_BUFFER;
 243         unsigned int link_len = 0;
 244         struct cifs_io_parms io_parms;
 245         FILE_ALL_INFO file_info;
 246
 247         rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
 248                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 249                          nls_codepage, remap);
 250         if (rc != 0)
 251                 return rc;
 252
 253         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 254                 CIFSSMBClose(xid, tcon, netfid);
 255                 /* it's not a symlink */
 256                 return -EINVAL;
 257         }
 258
 259         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 260         if (!buf)
 261                 return -ENOMEM;
 262         pbuf = buf;
 263         io_parms.netfid = netfid;
 264         io_parms.pid = current->tgid;
 265         io_parms.tcon = tcon;
 266         io_parms.offset = 0;
 267         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 268
 269         rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 270         CIFSSMBClose(xid, tcon, netfid);
 271         if (rc != 0) {
 272                 kfree(buf);
 273                 return rc;
 274         }
 275
 276         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
 277         kfree(buf);
 278         if (rc != 0)
 279                 return rc;
 280
 281         return 0;
 282 }
 283
 284 bool
 285 CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
 286 {
 287         if (!(fattr->cf_mode & S_IFREG))
 288                 /* it's not a symlink */
 289                 return false;
 290
 291         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 292                 /* it's not a symlink */
 293                 return false;
 294
 295         return true;
 296 }
 297
 298 int
 299 CIFSCheckMFSymlink(struct cifs_fattr *fattr,
 300                    const unsigned char *path,
 301                    struct cifs_sb_info *cifs_sb, int xid)
 302 {
 303         int rc;
 304         int oplock = 0;
 305         __u16 netfid = 0;
 306         struct tcon_link *tlink;
 307         struct cifs_tcon *pTcon;
 308         struct cifs_io_parms io_parms;
 309         u8 *buf;
 310         char *pbuf;
 311         unsigned int bytes_read = 0;
 312         int buf_type = CIFS_NO_BUFFER;
 313         unsigned int link_len = 0;
 314         FILE_ALL_INFO file_info;
 315
 316         if (!CIFSCouldBeMFSymlink(fattr))
 317                 /* it's not a symlink */
 318                 return 0;
 319
 320         tlink = cifs_sb_tlink(cifs_sb);
 321         if (IS_ERR(tlink))
 322                 return PTR_ERR(tlink);
 323         pTcon = tlink_tcon(tlink);
 324
 325         rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
 326                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 327                          cifs_sb->local_nls,
 328                          cifs_sb->mnt_cifs_flags &
 329                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 330         if (rc != 0)
 331                 goto out;
 332
 333         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 334                 CIFSSMBClose(xid, pTcon, netfid);
 335                 /* it's not a symlink */
 336                 goto out;
 337         }
 338
 339         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 340         if (!buf) {
 341                 rc = -ENOMEM;
 342                 goto out;
 343         }
 344         pbuf = buf;
 345         io_parms.netfid = netfid;
 346         io_parms.pid = current->tgid;
 347         io_parms.tcon = pTcon;
 348         io_parms.offset = 0;
 349         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 350
 351         rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 352         CIFSSMBClose(xid, pTcon, netfid);
 353         if (rc != 0) {
 354                 kfree(buf);
 355                 goto out;
 356         }
 357
 358         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
 359         kfree(buf);
 360         if (rc == -EINVAL) {
 361                 /* it's not a symlink */
 362                 rc = 0;
 363                 goto out;
 364         }
 365
 366         if (rc != 0)
 367                 goto out;
 368
 369         /* it is a symlink */
 370         fattr->cf_eof = link_len;
 371         fattr->cf_mode &= ~S_IFMT;
 372         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 373         fattr->cf_dtype = DT_LNK;
 374 out:
 375         cifs_put_tlink(tlink);
 376         return rc;
 377 }
 378
 379 int
 380 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 381               struct dentry *direntry)
 382 {
 383         int rc = -EACCES;
 384         int xid;
 385         char *fromName = NULL;
 386         char *toName = NULL;
 387         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 388         struct tcon_link *tlink;
 389         struct cifs_tcon *pTcon;
 390         struct cifsInodeInfo *cifsInode;
 391
 392         tlink = cifs_sb_tlink(cifs_sb);
 393         if (IS_ERR(tlink))
 394                 return PTR_ERR(tlink);
 395         pTcon = tlink_tcon(tlink);
 396
 397         xid = GetXid();
 398
 399         fromName = build_path_from_dentry(old_file);
 400         toName = build_path_from_dentry(direntry);
 401         if ((fromName == NULL) || (toName == NULL)) {
 402                 rc = -ENOMEM;
 403                 goto cifs_hl_exit;
 404         }
 405
 406         if (pTcon->unix_ext)
 407                 rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
 408                                             cifs_sb->local_nls,
 409                                             cifs_sb->mnt_cifs_flags &
 410                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 411         else {
 412                 rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
 413                                         cifs_sb->local_nls,
 414                                         cifs_sb->mnt_cifs_flags &
 415                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 416                 if ((rc == -EIO) || (rc == -EINVAL))
 417                         rc = -EOPNOTSUPP;
 418         }
 419
 420         d_drop(direntry);       /* force new lookup from server of target */
 421
 422         /* if source file is cached (oplocked) revalidate will not go to server
 423            until the file is closed or oplock broken so update nlinks locally */
 424         if (old_file->d_inode) {
 425                 cifsInode = CIFS_I(old_file->d_inode);
 426                 if (rc == 0) {
 427                         old_file->d_inode->i_nlink++;
 428 /* BB should we make this contingent on superblock flag NOATIME? */
 429 /*                      old_file->d_inode->i_ctime = CURRENT_TIME;*/
 430                         /* parent dir timestamps will update from srv
 431                         within a second, would it really be worth it
 432                         to set the parent dir cifs inode time to zero
 433                         to force revalidate (faster) for it too? */
 434                 }
 435                 /* if not oplocked will force revalidate to get info
 436                    on source file from srv */
 437                 cifsInode->time = 0;
 438
 439                 /* Will update parent dir timestamps from srv within a second.
 440                    Would it really be worth it to set the parent dir (cifs
 441                    inode) time field to zero to force revalidate on parent
 442                    directory faster ie
 443                         CIFS_I(inode)->time = 0;  */
 444         }
 445
 446 cifs_hl_exit:
 447         kfree(fromName);
 448         kfree(toName);
 449         FreeXid(xid);
 450         cifs_put_tlink(tlink);
 451         return rc;
 452 }
 453
 454 void *
 455 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 456 {
 457         struct inode *inode = direntry->d_inode;
 458         int rc = -ENOMEM;
 459         int xid;
 460         char *full_path = NULL;
 461         char *target_path = NULL;
 462         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 463         struct tcon_link *tlink = NULL;
 464         struct cifs_tcon *tcon;
 465
 466         xid = GetXid();
 467
 468         tlink = cifs_sb_tlink(cifs_sb);
 469         if (IS_ERR(tlink)) {
 470                 rc = PTR_ERR(tlink);
 471                 tlink = NULL;
 472                 goto out;
 473         }
 474         tcon = tlink_tcon(tlink);
 475
 476         /*
 477          * For now, we just handle symlinks with unix extensions enabled.
 478          * Eventually we should handle NTFS reparse points, and MacOS
 479          * symlink support. For instance...
 480          *
 481          * rc = CIFSSMBQueryReparseLinkInfo(...)
 482          *
 483          * For now, just return -EACCES when the server doesn't support posix
 484          * extensions. Note that we still allow querying symlinks when posix
 485          * extensions are manually disabled. We could disable these as well
 486          * but there doesn't seem to be any harm in allowing the client to
 487          * read them.
 488          */
 489         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 490             && !(tcon->ses->capabilities & CAP_UNIX)) {
 491                 rc = -EACCES;
 492                 goto out;
 493         }
 494
 495         full_path = build_path_from_dentry(direntry);
 496         if (!full_path)
 497                 goto out;
 498
 499         cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
 500
 501         rc = -EACCES;
 502         /*
 503          * First try Minshall+French Symlinks, if configured
 504          * and fallback to UNIX Extensions Symlinks.
 505          */
 506         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 507                 rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
 508                                         cifs_sb->local_nls,
 509                                         cifs_sb->mnt_cifs_flags &
 510                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 511
 512         if ((rc != 0) && (tcon->ses->capabilities & CAP_UNIX))
 513                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 514                                              cifs_sb->local_nls);
 515
 516         kfree(full_path);
 517 out:
 518         if (rc != 0) {
 519                 kfree(target_path);
 520                 target_path = ERR_PTR(rc);
 521         }
 522
 523         FreeXid(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         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 = GetXid();
 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         cFYI(1, "Full path: %s", full_path);
 557         cFYI(1, "symname is %s", 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 = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
 562                                          cifs_sb->local_nls,
 563                                          cifs_sb->mnt_cifs_flags &
 564                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 565         else if (pTcon->unix_ext)
 566                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 567                                            cifs_sb->local_nls);
 568         /* else
 569            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 570                                         cifs_sb_target->local_nls); */
 571
 572         if (rc == 0) {
 573                 if (pTcon->unix_ext)
 574                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 575                                                       inode->i_sb, xid);
 576                 else
 577                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 578                                                  inode->i_sb, xid, NULL);
 579
 580                 if (rc != 0) {
 581                         cFYI(1, "Create symlink ok, getinodeinfo fail rc = %d",
 582                               rc);
 583                 } else {
 584                         d_instantiate(direntry, newinode);
 585                 }
 586         }
 587 symlink_exit:
 588         kfree(full_path);
 589         cifs_put_tlink(tlink);
 590         FreeXid(xid);
 591         return rc;
 592 }
 593
 594 void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
 595 {
 596         char *p = nd_get_link(nd);
 597         if (!IS_ERR(p))
 598                 kfree(p);
 599 }