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                 cifs_dbg(VFS, "%s: Crypto md5 allocation error %d\n",
  60                          __func__, rc);
  61                 return rc;
  62         }
  63         size = sizeof(struct shash_desc) + crypto_shash_descsize(md5);
  64         sdescmd5 = kmalloc(size, GFP_KERNEL);
  65         if (!sdescmd5) {
  66                 rc = -ENOMEM;
  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                 cifs_dbg(VFS, "%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                 cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
  80                 goto symlink_hash_err;
  81         }
  82         rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
  83         if (rc)
  84                 cifs_dbg(VFS, "%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 parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
  95                  char **_link_str)
  96 {
  97         int rc;
  98         unsigned int link_len;
  99         const char *md5_str1;
 100         const char *link_str;
 101         u8 md5_hash[16];
 102         char md5_str2[34];
 103
 104         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 105                 return -EINVAL;
 106
 107         md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
 108         link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
 109
 110         rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
 111         if (rc != 1)
 112                 return -EINVAL;
 113
 114         rc = symlink_hash(link_len, link_str, md5_hash);
 115         if (rc) {
 116                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
 117                 return rc;
 118         }
 119
 120         snprintf(md5_str2, sizeof(md5_str2),
 121                  CIFS_MF_SYMLINK_MD5_FORMAT,
 122                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 123
 124         if (strncmp(md5_str1, md5_str2, 17) != 0)
 125                 return -EINVAL;
 126
 127         if (_link_str) {
 128                 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
 129                 if (!*_link_str)
 130                         return -ENOMEM;
 131         }
 132
 133         *_link_len = link_len;
 134         return 0;
 135 }
 136
 137 static int
 138 format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
 139 {
 140         int rc;
 141         unsigned int link_len;
 142         unsigned int ofs;
 143         u8 md5_hash[16];
 144
 145         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 146                 return -EINVAL;
 147
 148         link_len = strlen(link_str);
 149
 150         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
 151                 return -ENAMETOOLONG;
 152
 153         rc = symlink_hash(link_len, link_str, md5_hash);
 154         if (rc) {
 155                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
 156                 return rc;
 157         }
 158
 159         snprintf(buf, buf_len,
 160                  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
 161                  link_len,
 162                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 163
 164         ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 165         memcpy(buf + ofs, link_str, link_len);
 166
 167         ofs += link_len;
 168         if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 169                 buf[ofs] = '\n';
 170                 ofs++;
 171         }
 172
 173         while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 174                 buf[ofs] = ' ';
 175                 ofs++;
 176         }
 177
 178         return 0;
 179 }
 180
 181 static int
 182 create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 183                     const char *fromName, const char *toName,
 184                     struct cifs_sb_info *cifs_sb)
 185 {
 186         int rc;
 187         int oplock = 0;
 188         int remap;
 189         int create_options = CREATE_NOT_DIR;
 190         __u16 netfid = 0;
 191         u8 *buf;
 192         unsigned int bytes_written = 0;
 193         struct cifs_io_parms io_parms;
 194         struct nls_table *nls_codepage;
 195
 196         nls_codepage = cifs_sb->local_nls;
 197         remap = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR;
 198
 199         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 200         if (!buf)
 201                 return -ENOMEM;
 202
 203         rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 204         if (rc != 0) {
 205                 kfree(buf);
 206                 return rc;
 207         }
 208
 209         if (backup_cred(cifs_sb))
 210                 create_options |= CREATE_OPEN_BACKUP_INTENT;
 211
 212         rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
 213                          create_options, &netfid, &oplock, NULL,
 214                          nls_codepage, remap);
 215         if (rc != 0) {
 216                 kfree(buf);
 217                 return rc;
 218         }
 219
 220         io_parms.netfid = netfid;
 221         io_parms.pid = current->tgid;
 222         io_parms.tcon = tcon;
 223         io_parms.offset = 0;
 224         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 225
 226         rc = CIFSSMBWrite(xid, &io_parms, &bytes_written, buf, NULL, 0);
 227         CIFSSMBClose(xid, tcon, netfid);
 228         kfree(buf);
 229         if (rc != 0)
 230                 return rc;
 231
 232         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 233                 return -EIO;
 234
 235         return 0;
 236 }
 237
 238 static int
 239 query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 240                  struct cifs_sb_info *cifs_sb, const unsigned char *path,
 241                  char **symlinkinfo)
 242 {
 243         int rc;
 244         u8 *buf = NULL;
 245         unsigned int link_len = 0;
 246         unsigned int bytes_read = 0;
 247
 248         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 249         if (!buf)
 250                 return -ENOMEM;
 251
 252         if (tcon->ses->server->ops->query_mf_symlink)
 253                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 254                                               cifs_sb, path, buf, &bytes_read);
 255         else
 256                 rc = -ENOSYS;
 257
 258         if (rc)
 259                 goto out;
 260
 261         if (bytes_read == 0) { /* not a symlink */
 262                 rc = -EINVAL;
 263                 goto out;
 264         }
 265
 266         rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
 267 out:
 268         kfree(buf);
 269         return rc;
 270 }
 271
 272 bool
 273 couldbe_mf_symlink(const struct cifs_fattr *fattr)
 274 {
 275         if (!(fattr->cf_mode & S_IFREG))
 276                 /* it's not a symlink */
 277                 return false;
 278
 279         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 280                 /* it's not a symlink */
 281                 return false;
 282
 283         return true;
 284 }
 285
 286 int
 287 cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 288                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
 289                       char *pbuf, unsigned int *pbytes_read)
 290 {
 291         int rc;
 292         int oplock = 0;
 293         __u16 netfid = 0;
 294         struct cifs_io_parms io_parms;
 295         int buf_type = CIFS_NO_BUFFER;
 296         FILE_ALL_INFO file_info;
 297
 298         rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, GENERIC_READ,
 299                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 300                          cifs_sb->local_nls,
 301                          cifs_sb->mnt_cifs_flags &
 302                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 303         if (rc)
 304                 return rc;
 305
 306         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE))
 307                 /* it's not a symlink */
 308                 goto out;
 309
 310         io_parms.netfid = netfid;
 311         io_parms.pid = current->tgid;
 312         io_parms.tcon = tcon;
 313         io_parms.offset = 0;
 314         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 315
 316         rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
 317 out:
 318         CIFSSMBClose(xid, tcon, netfid);
 319         return rc;
 320 }
 321
 322 int
 323 check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 324                  struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
 325                  const unsigned char *path)
 326 {
 327         int rc;
 328         u8 *buf = NULL;
 329         unsigned int link_len = 0;
 330         unsigned int bytes_read = 0;
 331
 332         if (!couldbe_mf_symlink(fattr))
 333                 /* it's not a symlink */
 334                 return 0;
 335
 336         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 337         if (!buf)
 338                 return -ENOMEM;
 339
 340         if (tcon->ses->server->ops->query_mf_symlink)
 341                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 342                                               cifs_sb, path, buf, &bytes_read);
 343         else
 344                 rc = -ENOSYS;
 345
 346         if (rc)
 347                 goto out;
 348
 349         if (bytes_read == 0) /* not a symlink */
 350                 goto out;
 351
 352         rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
 353         if (rc == -EINVAL) {
 354                 /* it's not a symlink */
 355                 rc = 0;
 356                 goto out;
 357         }
 358
 359         if (rc != 0)
 360                 goto out;
 361
 362         /* it is a symlink */
 363         fattr->cf_eof = link_len;
 364         fattr->cf_mode &= ~S_IFMT;
 365         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 366         fattr->cf_dtype = DT_LNK;
 367 out:
 368         kfree(buf);
 369         return rc;
 370 }
 371
 372 int
 373 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 374               struct dentry *direntry)
 375 {
 376         int rc = -EACCES;
 377         unsigned int xid;
 378         char *from_name = NULL;
 379         char *to_name = NULL;
 380         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 381         struct tcon_link *tlink;
 382         struct cifs_tcon *tcon;
 383         struct TCP_Server_Info *server;
 384         struct cifsInodeInfo *cifsInode;
 385
 386         tlink = cifs_sb_tlink(cifs_sb);
 387         if (IS_ERR(tlink))
 388                 return PTR_ERR(tlink);
 389         tcon = tlink_tcon(tlink);
 390
 391         xid = get_xid();
 392
 393         from_name = build_path_from_dentry(old_file);
 394         to_name = build_path_from_dentry(direntry);
 395         if ((from_name == NULL) || (to_name == NULL)) {
 396                 rc = -ENOMEM;
 397                 goto cifs_hl_exit;
 398         }
 399
 400         if (tcon->unix_ext)
 401                 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
 402                                             cifs_sb->local_nls,
 403                                             cifs_sb->mnt_cifs_flags &
 404                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 405         else {
 406                 server = tcon->ses->server;
 407                 if (!server->ops->create_hardlink) {
 408                         rc = -ENOSYS;
 409                         goto cifs_hl_exit;
 410                 }
 411                 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
 412                                                   cifs_sb);
 413                 if ((rc == -EIO) || (rc == -EINVAL))
 414                         rc = -EOPNOTSUPP;
 415         }
 416
 417         d_drop(direntry);       /* force new lookup from server of target */
 418
 419         /*
 420          * if source file is cached (oplocked) revalidate will not go to server
 421          * until the file is closed or oplock broken so update nlinks locally
 422          */
 423         if (old_file->d_inode) {
 424                 cifsInode = CIFS_I(old_file->d_inode);
 425                 if (rc == 0) {
 426                         spin_lock(&old_file->d_inode->i_lock);
 427                         inc_nlink(old_file->d_inode);
 428                         spin_unlock(&old_file->d_inode->i_lock);
 429                         /*
 430                          * BB should we make this contingent on superblock flag
 431                          * NOATIME?
 432                          */
 433                         /* old_file->d_inode->i_ctime = CURRENT_TIME; */
 434                         /*
 435                          * parent dir timestamps will update from srv within a
 436                          * second, would it really be worth it to set the parent
 437                          * dir cifs inode time to zero to force revalidate
 438                          * (faster) for it too?
 439                          */
 440                 }
 441                 /*
 442                  * if not oplocked will force revalidate to get info on source
 443                  * file from srv
 444                  */
 445                 cifsInode->time = 0;
 446
 447                 /*
 448                  * Will update parent dir timestamps from srv within a second.
 449                  * Would it really be worth it to set the parent dir (cifs
 450                  * inode) time field to zero to force revalidate on parent
 451                  * directory faster ie
 452                  *
 453                  * CIFS_I(inode)->time = 0;
 454                  */
 455         }
 456
 457 cifs_hl_exit:
 458         kfree(from_name);
 459         kfree(to_name);
 460         free_xid(xid);
 461         cifs_put_tlink(tlink);
 462         return rc;
 463 }
 464
 465 void *
 466 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 467 {
 468         struct inode *inode = direntry->d_inode;
 469         int rc = -ENOMEM;
 470         unsigned int xid;
 471         char *full_path = NULL;
 472         char *target_path = NULL;
 473         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 474         struct tcon_link *tlink = NULL;
 475         struct cifs_tcon *tcon;
 476         struct TCP_Server_Info *server;
 477
 478         xid = get_xid();
 479
 480         tlink = cifs_sb_tlink(cifs_sb);
 481         if (IS_ERR(tlink)) {
 482                 rc = PTR_ERR(tlink);
 483                 tlink = NULL;
 484                 goto out;
 485         }
 486         tcon = tlink_tcon(tlink);
 487         server = tcon->ses->server;
 488
 489         full_path = build_path_from_dentry(direntry);
 490         if (!full_path)
 491                 goto out;
 492
 493         cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", 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 = query_mf_symlink(xid, tcon, cifs_sb, full_path,
 502                                       &target_path);
 503
 504         if ((rc != 0) && cap_unix(tcon->ses))
 505                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 506                                              cifs_sb->local_nls);
 507         else if (rc != 0 && server->ops->query_symlink)
 508                 rc = server->ops->query_symlink(xid, tcon, full_path,
 509                                                 &target_path, cifs_sb);
 510
 511         kfree(full_path);
 512 out:
 513         if (rc != 0) {
 514                 kfree(target_path);
 515                 target_path = ERR_PTR(rc);
 516         }
 517
 518         free_xid(xid);
 519         if (tlink)
 520                 cifs_put_tlink(tlink);
 521         nd_set_link(nd, target_path);
 522         return NULL;
 523 }
 524
 525 int
 526 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 527 {
 528         int rc = -EOPNOTSUPP;
 529         unsigned int xid;
 530         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 531         struct tcon_link *tlink;
 532         struct cifs_tcon *pTcon;
 533         char *full_path = NULL;
 534         struct inode *newinode = NULL;
 535
 536         xid = get_xid();
 537
 538         tlink = cifs_sb_tlink(cifs_sb);
 539         if (IS_ERR(tlink)) {
 540                 rc = PTR_ERR(tlink);
 541                 goto symlink_exit;
 542         }
 543         pTcon = tlink_tcon(tlink);
 544
 545         full_path = build_path_from_dentry(direntry);
 546         if (full_path == NULL) {
 547                 rc = -ENOMEM;
 548                 goto symlink_exit;
 549         }
 550
 551         cifs_dbg(FYI, "Full path: %s\n", full_path);
 552         cifs_dbg(FYI, "symname is %s\n", symname);
 553
 554         /* BB what if DFS and this volume is on different share? BB */
 555         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 556                 rc = create_mf_symlink(xid, pTcon, full_path, symname,
 557                                         cifs_sb);
 558         else if (pTcon->unix_ext)
 559                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 560                                            cifs_sb->local_nls);
 561         /* else
 562            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 563                                         cifs_sb_target->local_nls); */
 564
 565         if (rc == 0) {
 566                 if (pTcon->unix_ext)
 567                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 568                                                       inode->i_sb, xid);
 569                 else
 570                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 571                                                  inode->i_sb, xid, NULL);
 572
 573                 if (rc != 0) {
 574                         cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
 575                                  rc);
 576                 } else {
 577                         d_instantiate(direntry, newinode);
 578                 }
 579         }
 580 symlink_exit:
 581         kfree(full_path);
 582         cifs_put_tlink(tlink);
 583         free_xid(xid);
 584         return rc;
 585 }