linux/fs/cifs/link.c
<<
>>
Prefs
   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", __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", __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", __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", __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", __func__);
  85
  86symlink_hash_err:
  87        crypto_free_shash(md5);
  88        kfree(sdescmd5);
  89
  90        return rc;
  91}
  92
  93static int
  94CIFSParseMFSymlink(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", __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
 139static int
 140CIFSFormatMFSymlink(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", __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
 183static int
 184CIFSCreateMFSymLink(const unsigned int xid, struct cifs_tcon *tcon,
 185                    const char *fromName, const char *toName,
 186                    struct cifs_sb_info *cifs_sb)
 187{
 188        int rc;
 189        int oplock = 0;
 190        int remap;
 191        int create_options = CREATE_NOT_DIR;
 192        __u16 netfid = 0;
 193        u8 *buf;
 194        unsigned int bytes_written = 0;
 195        struct cifs_io_parms io_parms;
 196        struct nls_table *nls_codepage;
 197
 198        nls_codepage = cifs_sb->local_nls;
 199        remap = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR;
 200
 201        buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 202        if (!buf)
 203                return -ENOMEM;
 204
 205        rc = CIFSFormatMFSymlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 206        if (rc != 0) {
 207                kfree(buf);
 208                return rc;
 209        }
 210
 211        if (backup_cred(cifs_sb))
 212                create_options |= CREATE_OPEN_BACKUP_INTENT;
 213
 214        rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
 215                         create_options, &netfid, &oplock, NULL,
 216                         nls_codepage, remap);
 217        if (rc != 0) {
 218                kfree(buf);
 219                return rc;
 220        }
 221
 222        io_parms.netfid = netfid;
 223        io_parms.pid = current->tgid;
 224        io_parms.tcon = tcon;
 225        io_parms.offset = 0;
 226        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 227
 228        rc = CIFSSMBWrite(xid, &io_parms, &bytes_written, buf, NULL, 0);
 229        CIFSSMBClose(xid, tcon, netfid);
 230        kfree(buf);
 231        if (rc != 0)
 232                return rc;
 233
 234        if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 235                return -EIO;
 236
 237        return 0;
 238}
 239
 240static int
 241CIFSQueryMFSymLink(const unsigned int xid, struct cifs_tcon *tcon,
 242                   const unsigned char *searchName, char **symlinkinfo,
 243                   const struct nls_table *nls_codepage, int remap)
 244{
 245        int rc;
 246        int oplock = 0;
 247        __u16 netfid = 0;
 248        u8 *buf;
 249        char *pbuf;
 250        unsigned int bytes_read = 0;
 251        int buf_type = CIFS_NO_BUFFER;
 252        unsigned int link_len = 0;
 253        struct cifs_io_parms io_parms;
 254        FILE_ALL_INFO file_info;
 255
 256        rc = CIFSSMBOpen(xid, tcon, searchName, FILE_OPEN, GENERIC_READ,
 257                         CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 258                         nls_codepage, remap);
 259        if (rc != 0)
 260                return rc;
 261
 262        if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 263                CIFSSMBClose(xid, tcon, netfid);
 264                /* it's not a symlink */
 265                return -EINVAL;
 266        }
 267
 268        buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 269        if (!buf)
 270                return -ENOMEM;
 271        pbuf = buf;
 272        io_parms.netfid = netfid;
 273        io_parms.pid = current->tgid;
 274        io_parms.tcon = tcon;
 275        io_parms.offset = 0;
 276        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 277
 278        rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 279        CIFSSMBClose(xid, tcon, netfid);
 280        if (rc != 0) {
 281                kfree(buf);
 282                return rc;
 283        }
 284
 285        rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, symlinkinfo);
 286        kfree(buf);
 287        if (rc != 0)
 288                return rc;
 289
 290        return 0;
 291}
 292
 293bool
 294CIFSCouldBeMFSymlink(const struct cifs_fattr *fattr)
 295{
 296        if (!(fattr->cf_mode & S_IFREG))
 297                /* it's not a symlink */
 298                return false;
 299
 300        if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 301                /* it's not a symlink */
 302                return false;
 303
 304        return true;
 305}
 306
 307int
 308CIFSCheckMFSymlink(struct cifs_fattr *fattr,
 309                   const unsigned char *path,
 310                   struct cifs_sb_info *cifs_sb, unsigned int xid)
 311{
 312        int rc;
 313        int oplock = 0;
 314        __u16 netfid = 0;
 315        struct tcon_link *tlink;
 316        struct cifs_tcon *pTcon;
 317        struct cifs_io_parms io_parms;
 318        u8 *buf;
 319        char *pbuf;
 320        unsigned int bytes_read = 0;
 321        int buf_type = CIFS_NO_BUFFER;
 322        unsigned int link_len = 0;
 323        FILE_ALL_INFO file_info;
 324
 325        if (!CIFSCouldBeMFSymlink(fattr))
 326                /* it's not a symlink */
 327                return 0;
 328
 329        tlink = cifs_sb_tlink(cifs_sb);
 330        if (IS_ERR(tlink))
 331                return PTR_ERR(tlink);
 332        pTcon = tlink_tcon(tlink);
 333
 334        rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
 335                         CREATE_NOT_DIR, &netfid, &oplock, &file_info,
 336                         cifs_sb->local_nls,
 337                         cifs_sb->mnt_cifs_flags &
 338                                CIFS_MOUNT_MAP_SPECIAL_CHR);
 339        if (rc != 0)
 340                goto out;
 341
 342        if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 343                CIFSSMBClose(xid, pTcon, netfid);
 344                /* it's not a symlink */
 345                goto out;
 346        }
 347
 348        buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 349        if (!buf) {
 350                rc = -ENOMEM;
 351                goto out;
 352        }
 353        pbuf = buf;
 354        io_parms.netfid = netfid;
 355        io_parms.pid = current->tgid;
 356        io_parms.tcon = pTcon;
 357        io_parms.offset = 0;
 358        io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 359
 360        rc = CIFSSMBRead(xid, &io_parms, &bytes_read, &pbuf, &buf_type);
 361        CIFSSMBClose(xid, pTcon, netfid);
 362        if (rc != 0) {
 363                kfree(buf);
 364                goto out;
 365        }
 366
 367        rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
 368        kfree(buf);
 369        if (rc == -EINVAL) {
 370                /* it's not a symlink */
 371                rc = 0;
 372                goto out;
 373        }
 374
 375        if (rc != 0)
 376                goto out;
 377
 378        /* it is a symlink */
 379        fattr->cf_eof = link_len;
 380        fattr->cf_mode &= ~S_IFMT;
 381        fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 382        fattr->cf_dtype = DT_LNK;
 383out:
 384        cifs_put_tlink(tlink);
 385        return rc;
 386}
 387
 388int
 389cifs_hardlink(struct dentry *old_file, struct inode *inode,
 390              struct dentry *direntry)
 391{
 392        int rc = -EACCES;
 393        unsigned int xid;
 394        char *fromName = NULL;
 395        char *toName = NULL;
 396        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 397        struct tcon_link *tlink;
 398        struct cifs_tcon *pTcon;
 399        struct cifsInodeInfo *cifsInode;
 400
 401        tlink = cifs_sb_tlink(cifs_sb);
 402        if (IS_ERR(tlink))
 403                return PTR_ERR(tlink);
 404        pTcon = tlink_tcon(tlink);
 405
 406        xid = get_xid();
 407
 408        fromName = build_path_from_dentry(old_file);
 409        toName = build_path_from_dentry(direntry);
 410        if ((fromName == NULL) || (toName == NULL)) {
 411                rc = -ENOMEM;
 412                goto cifs_hl_exit;
 413        }
 414
 415        if (pTcon->unix_ext)
 416                rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
 417                                            cifs_sb->local_nls,
 418                                            cifs_sb->mnt_cifs_flags &
 419                                                CIFS_MOUNT_MAP_SPECIAL_CHR);
 420        else {
 421                rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
 422                                        cifs_sb->local_nls,
 423                                        cifs_sb->mnt_cifs_flags &
 424                                                CIFS_MOUNT_MAP_SPECIAL_CHR);
 425                if ((rc == -EIO) || (rc == -EINVAL))
 426                        rc = -EOPNOTSUPP;
 427        }
 428
 429        d_drop(direntry);       /* force new lookup from server of target */
 430
 431        /* if source file is cached (oplocked) revalidate will not go to server
 432           until the file is closed or oplock broken so update nlinks locally */
 433        if (old_file->d_inode) {
 434                cifsInode = CIFS_I(old_file->d_inode);
 435                if (rc == 0) {
 436                        spin_lock(&old_file->d_inode->i_lock);
 437                        inc_nlink(old_file->d_inode);
 438                        spin_unlock(&old_file->d_inode->i_lock);
 439/* BB should we make this contingent on superblock flag NOATIME? */
 440/*                      old_file->d_inode->i_ctime = CURRENT_TIME;*/
 441                        /* parent dir timestamps will update from srv
 442                        within a second, would it really be worth it
 443                        to set the parent dir cifs inode time to zero
 444                        to force revalidate (faster) for it too? */
 445                }
 446                /* if not oplocked will force revalidate to get info
 447                   on source file from srv */
 448                cifsInode->time = 0;
 449
 450                /* Will update parent dir timestamps from srv within a second.
 451                   Would it really be worth it to set the parent dir (cifs
 452                   inode) time field to zero to force revalidate on parent
 453                   directory faster ie
 454                        CIFS_I(inode)->time = 0;  */
 455        }
 456
 457cifs_hl_exit:
 458        kfree(fromName);
 459        kfree(toName);
 460        free_xid(xid);
 461        cifs_put_tlink(tlink);
 462        return rc;
 463}
 464
 465void *
 466cifs_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
 477        xid = get_xid();
 478
 479        tlink = cifs_sb_tlink(cifs_sb);
 480        if (IS_ERR(tlink)) {
 481                rc = PTR_ERR(tlink);
 482                tlink = NULL;
 483                goto out;
 484        }
 485        tcon = tlink_tcon(tlink);
 486
 487        /*
 488         * For now, we just handle symlinks with unix extensions enabled.
 489         * Eventually we should handle NTFS reparse points, and MacOS
 490         * symlink support. For instance...
 491         *
 492         * rc = CIFSSMBQueryReparseLinkInfo(...)
 493         *
 494         * For now, just return -EACCES when the server doesn't support posix
 495         * extensions. Note that we still allow querying symlinks when posix
 496         * extensions are manually disabled. We could disable these as well
 497         * but there doesn't seem to be any harm in allowing the client to
 498         * read them.
 499         */
 500        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) &&
 501            !cap_unix(tcon->ses)) {
 502                rc = -EACCES;
 503                goto out;
 504        }
 505
 506        full_path = build_path_from_dentry(direntry);
 507        if (!full_path)
 508                goto out;
 509
 510        cFYI(1, "Full path: %s inode = 0x%p", full_path, inode);
 511
 512        rc = -EACCES;
 513        /*
 514         * First try Minshall+French Symlinks, if configured
 515         * and fallback to UNIX Extensions Symlinks.
 516         */
 517        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 518                rc = CIFSQueryMFSymLink(xid, tcon, full_path, &target_path,
 519                                        cifs_sb->local_nls,
 520                                        cifs_sb->mnt_cifs_flags &
 521                                                CIFS_MOUNT_MAP_SPECIAL_CHR);
 522
 523        if ((rc != 0) && cap_unix(tcon->ses))
 524                rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, &target_path,
 525                                             cifs_sb->local_nls);
 526
 527        kfree(full_path);
 528out:
 529        if (rc != 0) {
 530                kfree(target_path);
 531                target_path = ERR_PTR(rc);
 532        }
 533
 534        free_xid(xid);
 535        if (tlink)
 536                cifs_put_tlink(tlink);
 537        nd_set_link(nd, target_path);
 538        return NULL;
 539}
 540
 541int
 542cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 543{
 544        int rc = -EOPNOTSUPP;
 545        unsigned int xid;
 546        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 547        struct tcon_link *tlink;
 548        struct cifs_tcon *pTcon;
 549        char *full_path = NULL;
 550        struct inode *newinode = NULL;
 551
 552        xid = get_xid();
 553
 554        tlink = cifs_sb_tlink(cifs_sb);
 555        if (IS_ERR(tlink)) {
 556                rc = PTR_ERR(tlink);
 557                goto symlink_exit;
 558        }
 559        pTcon = tlink_tcon(tlink);
 560
 561        full_path = build_path_from_dentry(direntry);
 562        if (full_path == NULL) {
 563                rc = -ENOMEM;
 564                goto symlink_exit;
 565        }
 566
 567        cFYI(1, "Full path: %s", full_path);
 568        cFYI(1, "symname is %s", symname);
 569
 570        /* BB what if DFS and this volume is on different share? BB */
 571        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 572                rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
 573                                        cifs_sb);
 574        else if (pTcon->unix_ext)
 575                rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 576                                           cifs_sb->local_nls);
 577        /* else
 578           rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 579                                        cifs_sb_target->local_nls); */
 580
 581        if (rc == 0) {
 582                if (pTcon->unix_ext)
 583                        rc = cifs_get_inode_info_unix(&newinode, full_path,
 584                                                      inode->i_sb, xid);
 585                else
 586                        rc = cifs_get_inode_info(&newinode, full_path, NULL,
 587                                                 inode->i_sb, xid, NULL);
 588
 589                if (rc != 0) {
 590                        cFYI(1, "Create symlink ok, getinodeinfo fail rc = %d",
 591                              rc);
 592                } else {
 593                        d_instantiate(direntry, newinode);
 594                }
 595        }
 596symlink_exit:
 597        kfree(full_path);
 598        cifs_put_tlink(tlink);
 599        free_xid(xid);
 600        return rc;
 601}
 602
 603void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
 604{
 605        char *p = nd_get_link(nd);
 606        if (!IS_ERR(p))
 607                kfree(p);
 608}
 609
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.