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