linux/fs/cifs/link.c
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   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
  48static int
  49symlink_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
  80symlink_hash_err:
  81        crypto_free_shash(md5);
  82        kfree(sdescmd5);
  83
  84        return rc;
  85}
  86
  87static int
  88CIFSParseMFSymlink(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
 133static int
 134CIFSFormatMFSymlink(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
 177static int
 178CIFSCreateMFSymLink(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
 221static int
 222CIFSQueryMFSymLink(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 != cpu_to_le64(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
 271bool
 272CIFSCouldBeMFSymlink(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
 285int
 286CIFSCheckMFSymlink(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 != cpu_to_le64(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;
 358out:
 359        cifs_put_tlink(tlink);
 360        return rc;
 361}
 362
 363int
 364cifs_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
 430cifs_hl_exit:
 431        kfree(fromName);
 432        kfree(toName);
 433        FreeXid(xid);
 434        cifs_put_tlink(tlink);
 435        return rc;
 436}
 437
 438void *
 439cifs_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);
 501out:
 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
 514int
 515cifs_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        }
 571symlink_exit:
 572        kfree(full_path);
 573        cifs_put_tlink(tlink);
 574        FreeXid(xid);
 575        return rc;
 576}
 577
 578void 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}
 584