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                 cERROR(1, "%s: Crypto md5 allocation error %d\n", __func__, rc);
  59                 return PTR_ERR(md5);
  60         }
  61         size = sizeof(struct shash_desc) + crypto_shash_descsize(md5);
  62         sdescmd5 = kmalloc(size, GFP_KERNEL);
  63         if (!sdescmd5) {
  64                 rc = -ENOMEM;
  65                 cERROR(1, "%s: Memory allocation failure\n", __func__);
  66                 goto symlink_hash_err;
  67         }
  68         sdescmd5->shash.tfm = md5;
  69         sdescmd5->shash.flags = 0x0;
  70
  71         rc = crypto_shash_init(&sdescmd5->shash);
  72         if (rc) {
  73                 cERROR(1, "%s: Could not init md5 shash\n", __func__);
  74                 goto symlink_hash_err;
  75         }
  76         crypto_shash_update(&sdescmd5->shash, link_str, link_len);
  77         rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
  78
  79 symlink_hash_err:
  80         crypto_free_shash(md5);
  81         kfree(sdescmd5);
  82
  83         return rc;
  84 }
  85
  86 static int
  87 CIFSParseMFSymlink(const u8 *buf,
  88                    unsigned int buf_len,
  89                    unsigned int *_link_len,
  90                    char **_link_str)
  91 {
  92         int rc;
  93         unsigned int link_len;
  94         const char *md5_str1;
  95         const char *link_str;
  96         u8 md5_hash[16];
  97         char md5_str2[34];
  98
  99         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 100                 return -EINVAL;
 101
 102         md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
 103         link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
 104
 105         rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
 106         if (rc != 1)
 107                 return -EINVAL;
 108
 109         rc = symlink_hash(link_len, link_str, md5_hash);
 110         if (rc) {
 111                 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
 112                 return rc;
 113         }
 114
 115         snprintf(md5_str2, sizeof(md5_str2),
 116                  CIFS_MF_SYMLINK_MD5_FORMAT,
 117                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 118
 119         if (strncmp(md5_str1, md5_str2, 17) != 0)
 120                 return -EINVAL;
 121
 122         if (_link_str) {
 123                 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
 124                 if (!*_link_str)
 125                         return -ENOMEM;
 126         }
 127
 128         *_link_len = link_len;
 129         return 0;
 130 }
 131
 132 static int
 133 CIFSFormatMFSymlink(u8 *buf, unsigned int buf_len, const char *link_str)
 134 {
 135         int rc;
 136         unsigned int link_len;
 137         unsigned int ofs;
 138         u8 md5_hash[16];
 139
 140         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 141                 return -EINVAL;
 142
 143         link_len = strlen(link_str);
 144
 145         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
 146                 return -ENAMETOOLONG;
 147
 148         rc = symlink_hash(link_len, link_str, md5_hash);
 149         if (rc) {
 150                 cFYI(1, "%s: MD5 hash failure: %d\n", __func__, rc);
 151                 return rc;
 152         }
 153
 154         snprintf(buf, buf_len,
 155                  CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
 156                  link_len,
 157                  CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 158
 159         ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 160         memcpy(buf + ofs, link_str, link_len);
 161
 162         ofs += link_len;
 163         if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 164                 buf[ofs] = '\n';
 165                 ofs++;
 166         }
 167
 168         while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 169                 buf[ofs] = ' ';
 170                 ofs++;
 171         }
 172
 173         return 0;
 174 }
 175
 176 static int
 177 CIFSCreateMFSymLink(const int xid, struct cifsTconInfo *tcon,
 178                     const char *fromName, const char *toName,
 179                     const struct nls_table *nls_codepage, int remap)
 180 {
 181         int rc;
 182         int oplock = 0;
 183         __u16 netfid = 0;
 184         u8 *buf;
 185         unsigned int bytes_written = 0;
 186
 187         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 188         if (!buf)
 189                 return -ENOMEM;
 190
 191         rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 192         if (rc != 0) {
 193                 kfree(buf);
 194                 return rc;
 195         }
 196
 197         rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
 198                          CREATE_NOT_DIR, &netfid, &oplock, NULL,
 199                          nls_codepage, remap);
 200         if (rc != 0) {
 201                 kfree(buf);
 202                 return rc;
 203         }
 204
 205         rc = CIFSSMBWrite(xid, tcon, netfid,
 206                           CIFS_MF_SYMLINK_FILE_SIZE /* length */,
 207                           0 /* offset */,
 208                           &bytes_written, buf, NULL, 0);
 209         CIFSSMBClose(xid, tcon, netfid);
 210         kfree(buf);
 211         if (rc != 0)
 212                 return rc;
 213
 214         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 215                 return -EIO;
 216
 217         return 0;
 218 }
 219
 220 static int
 221 CIFSQueryMFSymLink(const int xid, struct cifsTconInfo *tcon,
 222                    const unsigned char *searchName, char **symlinkinfo,
 223                    const struct nls_table *nls_codepage, int remap)
 224 {
 225         int rc;
 226         int oplock = 0;
 227         __u16 netfid = 0;
 228         u8 *buf;
 229         char *pbuf;
 230         unsigned int bytes_read = 0;
 231         int buf_type = CIFS_NO_BUFFER;
 232         unsigned int link_len = 0;
 233         FILE_ALL_INFO file_info;
 234
 235         rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
 236                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 237                          nls_codepage, remap);
 238         if (rc != 0)
 239                 return rc;
 240
 241         if (file_info.EndOfFile != CIFS_MF_SYMLINK_FILE_SIZE) {
 242                 CIFSSMBClose(xid, tcon, netfid);
 243                 /* it's not a symlink */
 244                 return -EINVAL;
 245         }
 246
 247         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 248         if (!buf)
 249                 return -ENOMEM;
 250         pbuf = buf;
 251
 252         rc = CIFSSMBRead(xid, tcon, netfid,
 253                          CIFS_MF_SYMLINK_FILE_SIZE /* length */,
 254                          0 /* offset */,
 255                          &bytes_read, &pbuf, &buf_type);
 256         CIFSSMBClose(xid, tcon, netfid);
 257         if (rc != 0) {
 258                 kfree(buf);
 259                 return rc;
 260         }
 261
 262         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
 263         kfree(buf);
 264         if (rc != 0)
 265                 return rc;
 266
 267         return 0;
 268 }
 269
 270 bool
 271 CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
 272 {
 273         if (!(fattr->cf_mode & S_IFREG))
 274                 /* it's not a symlink */
 275                 return false;
 276
 277         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 278                 /* it's not a symlink */
 279                 return false;
 280
 281         return true;
 282 }
 283
 284 int
 285 CIFSCheckMFSymlink(struct cifs_fattr *fattr,
 286                    const unsigned char *path,
 287                    struct cifs_sb_info *cifs_sb, int xid)
 288 {
 289         int rc;
 290         int oplock = 0;
 291         __u16 netfid = 0;
 292         struct tcon_link *tlink;
 293         struct cifsTconInfo *pTcon;
 294         u8 *buf;
 295         char *pbuf;
 296         unsigned int bytes_read = 0;
 297         int buf_type = CIFS_NO_BUFFER;
 298         unsigned int link_len = 0;
 299         FILE_ALL_INFO file_info;
 300
 301         if (!CIFSCouldBeMFSymlink(fattr))
 302                 /* it's not a symlink */
 303                 return 0;
 304
 305         tlink = cifs_sb_tlink(cifs_sb);
 306         if (IS_ERR(tlink))
 307                 return PTR_ERR(tlink);
 308         pTcon = tlink_tcon(tlink);
 309
 310         rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
 311                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 312                          cifs_sb->local_nls,
 313                          cifs_sb->mnt_cifs_flags &
 314                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 315         if (rc != 0)
 316                 goto out;
 317
 318         if (file_info.EndOfFile != CIFS_MF_SYMLINK_FILE_SIZE) {
 319                 CIFSSMBClose(xid, pTcon, netfid);
 320                 /* it's not a symlink */
 321                 goto out;
 322         }
 323
 324         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 325         if (!buf) {
 326                 rc = -ENOMEM;
 327                 goto out;
 328         }
 329         pbuf = buf;
 330
 331         rc = CIFSSMBRead(xid, pTcon, netfid,
 332                          CIFS_MF_SYMLINK_FILE_SIZE /* length */,
 333                          0 /* offset */,
 334                          &bytes_read, &pbuf, &buf_type);
 335         CIFSSMBClose(xid, pTcon, netfid);
 336         if (rc != 0) {
 337                 kfree(buf);
 338                 goto out;
 339         }
 340
 341         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
 342         kfree(buf);
 343         if (rc == -EINVAL) {
 344                 /* it's not a symlink */
 345                 rc = 0;
 346                 goto out;
 347         }
 348
 349         if (rc != 0)
 350                 goto out;
 351
 352         /* it is a symlink */
 353         fattr->cf_eof = link_len;
 354         fattr->cf_mode &= ~S_IFMT;
 355         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 356         fattr->cf_dtype = DT_LNK;
 357 out:
 358         cifs_put_tlink(tlink);
 359         return rc;
 360 }
 361
 362 int
 363 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 364               struct dentry *direntry)
 365 {
 366         int rc = -EACCES;
 367         int xid;
 368         char *fromName = NULL;
 369         char *toName = NULL;
 370         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 371         struct tcon_link *tlink;
 372         struct cifsTconInfo *pTcon;
 373         struct cifsInodeInfo *cifsInode;
 374
 375         tlink = cifs_sb_tlink(cifs_sb);
 376         if (IS_ERR(tlink))
 377                 return PTR_ERR(tlink);
 378         pTcon = tlink_tcon(tlink);
 379
 380         xid = GetXid();
 381
 382         fromName = build_path_from_dentry(old_file);
 383         toName = build_path_from_dentry(direntry);
 384         if ((fromName == NULL) || (toName == NULL)) {
 385                 rc = -ENOMEM;
 386                 goto cifs_hl_exit;
 387         }
 388
 389         if (pTcon->unix_ext)
 390                 rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
 391                                             cifs_sb->local_nls,
 392                                             cifs_sb->mnt_cifs_flags &
 393                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 394         else {
 395                 rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
 396                                         cifs_sb->local_nls,
 397                                         cifs_sb->mnt_cifs_flags &
 398                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 399                 if ((rc == -EIO) || (rc == -EINVAL))
 400                         rc = -EOPNOTSUPP;
 401         }
 402
 403         d_drop(direntry);       /* force new lookup from server of target */
 404
 405         /* if source file is cached (oplocked) revalidate will not go to server
 406            until the file is closed or oplock broken so update nlinks locally */
 407         if (old_file->d_inode) {
 408                 cifsInode = CIFS_I(old_file->d_inode);
 409                 if (rc == 0) {
 410                         old_file->d_inode->i_nlink++;
 411 /* BB should we make this contingent on superblock flag NOATIME? */
 412 /*                      old_file->d_inode->i_ctime = CURRENT_TIME;*/
 413                         /* parent dir timestamps will update from srv
 414                         within a second, would it really be worth it
 415                         to set the parent dir cifs inode time to zero
 416                         to force revalidate (faster) for it too? */
 417                 }
 418                 /* if not oplocked will force revalidate to get info
 419                    on source file from srv */
 420                 cifsInode->time = 0;
 421
 422                 /* Will update parent dir timestamps from srv within a second.
 423                    Would it really be worth it to set the parent dir (cifs
 424                    inode) time field to zero to force revalidate on parent
 425                    directory faster ie
 426                         CIFS_I(inode)->time = 0;  */
 427         }
 428
 429 cifs_hl_exit:
 430         kfree(fromName);
 431         kfree(toName);
 432         FreeXid(xid);
 433         cifs_put_tlink(tlink);
 434         return rc;
 435 }
 436
 437 void *
 438 cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
 439 {
 440         struct inode *inode = direntry->d_inode;
 441         int rc = -ENOMEM;
 442         int xid;
 443         char *full_path = NULL;
 444         char *target_path = NULL;
 445         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 446         struct tcon_link *tlink = NULL;
 447         struct cifsTconInfo *tcon;
 448
 449         xid = GetXid();
 450
 451         tlink = cifs_sb_tlink(cifs_sb);
 452         if (IS_ERR(tlink)) {
 453                 rc = PTR_ERR(tlink);
 454                 tlink = NULL;
 455                 goto out;
 456         }
 457         tcon = tlink_tcon(tlink);
 458
 459         /*
 460          * For now, we just handle symlinks with unix extensions enabled.
 461          * Eventually we should handle NTFS reparse points, and MacOS
 462          * symlink support. For instance...
 463          *
 464          * rc = CIFSSMBQueryReparseLinkInfo(...)
 465          *
 466          * For now, just return -EACCES when the server doesn't support posix
 467          * extensions. Note that we still allow querying symlinks when posix
 468          * extensions are manually disabled. We could disable these as well
 469          * but there doesn't seem to be any harm in allowing the client to
 470          * read them.
 471          */
 472         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 473             && !(tcon->ses->capabilities & CAP_UNIX)) {
 474                 rc = -EACCES;
 475                 goto out;
 476         }
 477
 478         full_path = build_path_from_dentry(direntry);
 479         if (!full_path)
 480                 goto out;
 481
 482         cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
 483
 484         rc = -EACCES;
 485         /*
 486          * First try Minshall+French Symlinks, if configured
 487          * and fallback to UNIX Extensions Symlinks.
 488          */
 489         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 490                 rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
 491                                         cifs_sb->local_nls,
 492                                         cifs_sb->mnt_cifs_flags &
 493                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 494
 495         if ((rc != 0) && (tcon->ses->capabilities & CAP_UNIX))
 496                 rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 497                                              cifs_sb->local_nls);
 498
 499         kfree(full_path);
 500 out:
 501         if (rc != 0) {
 502                 kfree(target_path);
 503                 target_path = ERR_PTR(rc);
 504         }
 505
 506         FreeXid(xid);
 507         if (tlink)
 508                 cifs_put_tlink(tlink);
 509         nd_set_link(nd, target_path);
 510         return NULL;
 511 }
 512
 513 int
 514 cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 515 {
 516         int rc = -EOPNOTSUPP;
 517         int xid;
 518         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 519         struct tcon_link *tlink;
 520         struct cifsTconInfo *pTcon;
 521         char *full_path = NULL;
 522         struct inode *newinode = NULL;
 523
 524         xid = GetXid();
 525
 526         tlink = cifs_sb_tlink(cifs_sb);
 527         if (IS_ERR(tlink)) {
 528                 rc = PTR_ERR(tlink);
 529                 goto symlink_exit;
 530         }
 531         pTcon = tlink_tcon(tlink);
 532
 533         full_path = build_path_from_dentry(direntry);
 534         if (full_path == NULL) {
 535                 rc = -ENOMEM;
 536                 goto symlink_exit;
 537         }
 538
 539         cFYI(1, "Full path: %s", full_path);
 540         cFYI(1, "symname is %s", symname);
 541
 542         /* BB what if DFS and this volume is on different share? BB */
 543         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 544                 rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
 545                                          cifs_sb->local_nls,
 546                                          cifs_sb->mnt_cifs_flags &
 547                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
 548         else if (pTcon->unix_ext)
 549                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 550                                            cifs_sb->local_nls);
 551         /* else
 552            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 553                                         cifs_sb_target->local_nls); */
 554
 555         if (rc == 0) {
 556                 if (pTcon->unix_ext)
 557                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 558                                                       inode->i_sb, xid);
 559                 else
 560                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 561                                                  inode->i_sb, xid, NULL);
 562
 563                 if (rc != 0) {
 564                         cFYI(1, "Create symlink ok, getinodeinfo fail rc = %d",
 565                               rc);
 566                 } else {
 567                         d_instantiate(direntry, newinode);
 568                 }
 569         }
 570 symlink_exit:
 571         kfree(full_path);
 572         cifs_put_tlink(tlink);
 573         FreeXid(xid);
 574         return rc;
 575 }
 576
 577 void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
 578 {
 579         char *p = nd_get_link(nd);
 580         if (!IS_ERR(p))
 581                 kfree(p);
 582 }