fs/cifs/link.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  *
   4  *   Copyright (C) International Business Machines  Corp., 2002,2008
   5  *   Author(s): Steve French ([email protected])
   6  *
   7  */
   8 #include <linux/fs.h>
   9 #include <linux/stat.h>
  10 #include <linux/slab.h>
  11 #include <linux/namei.h>
  12 #include "cifsfs.h"
  13 #include "cifspdu.h"
  14 #include "cifsglob.h"
  15 #include "cifsproto.h"
  16 #include "cifs_debug.h"
  17 #include "cifs_fs_sb.h"
  18 #include "cifs_unicode.h"
  19 #include "smb2proto.h"
  20 #include "cifs_ioctl.h"
  21
  22 /*
  23  * M-F Symlink Functions - Begin
  24  */
  25
  26 #define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
  27 #define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
  28 #define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
  29 #define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
  30 #define CIFS_MF_SYMLINK_FILE_SIZE \
  31         (CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)
  32
  33 #define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
  34 #define CIFS_MF_SYMLINK_MD5_FORMAT "%16phN\n"
  35 #define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) md5_hash
  36
  37 static int
  38 symlink_hash(unsigned int link_len, const char *link_str, u8 *md5_hash)
  39 {
  40         int rc;
  41         struct crypto_shash *md5 = NULL;
  42         struct sdesc *sdescmd5 = NULL;
  43
  44         rc = cifs_alloc_hash("md5", &md5, &sdescmd5);
  45         if (rc)
  46                 goto symlink_hash_err;
  47
  48         rc = crypto_shash_init(&sdescmd5->shash);
  49         if (rc) {
  50                 cifs_dbg(VFS, "%s: Could not init md5 shash\n", __func__);
  51                 goto symlink_hash_err;
  52         }
  53         rc = crypto_shash_update(&sdescmd5->shash, link_str, link_len);
  54         if (rc) {
  55                 cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
  56                 goto symlink_hash_err;
  57         }
  58         rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
  59         if (rc)
  60                 cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
  61
  62 symlink_hash_err:
  63         cifs_free_hash(&md5, &sdescmd5);
  64         return rc;
  65 }
  66
  67 static int
  68 parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
  69                  char **_link_str)
  70 {
  71         int rc;
  72         unsigned int link_len;
  73         const char *md5_str1;
  74         const char *link_str;
  75         u8 md5_hash[16];
  76         char md5_str2[34];
  77
  78         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
  79                 return -EINVAL;
  80
  81         md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
  82         link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
  83
  84         rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
  85         if (rc != 1)
  86                 return -EINVAL;
  87
  88         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
  89                 return -EINVAL;
  90
  91         rc = symlink_hash(link_len, link_str, md5_hash);
  92         if (rc) {
  93                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
  94                 return rc;
  95         }
  96
  97         scnprintf(md5_str2, sizeof(md5_str2),
  98                   CIFS_MF_SYMLINK_MD5_FORMAT,
  99                   CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 100
 101         if (strncmp(md5_str1, md5_str2, 17) != 0)
 102                 return -EINVAL;
 103
 104         if (_link_str) {
 105                 *_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
 106                 if (!*_link_str)
 107                         return -ENOMEM;
 108         }
 109
 110         *_link_len = link_len;
 111         return 0;
 112 }
 113
 114 static int
 115 format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
 116 {
 117         int rc;
 118         unsigned int link_len;
 119         unsigned int ofs;
 120         u8 md5_hash[16];
 121
 122         if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
 123                 return -EINVAL;
 124
 125         link_len = strlen(link_str);
 126
 127         if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
 128                 return -ENAMETOOLONG;
 129
 130         rc = symlink_hash(link_len, link_str, md5_hash);
 131         if (rc) {
 132                 cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
 133                 return rc;
 134         }
 135
 136         scnprintf(buf, buf_len,
 137                   CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
 138                   link_len,
 139                   CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
 140
 141         ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
 142         memcpy(buf + ofs, link_str, link_len);
 143
 144         ofs += link_len;
 145         if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 146                 buf[ofs] = '\n';
 147                 ofs++;
 148         }
 149
 150         while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
 151                 buf[ofs] = ' ';
 152                 ofs++;
 153         }
 154
 155         return 0;
 156 }
 157
 158 bool
 159 couldbe_mf_symlink(const struct cifs_fattr *fattr)
 160 {
 161         if (!S_ISREG(fattr->cf_mode))
 162                 /* it's not a symlink */
 163                 return false;
 164
 165         if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
 166                 /* it's not a symlink */
 167                 return false;
 168
 169         return true;
 170 }
 171
 172 static int
 173 create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 174                   struct cifs_sb_info *cifs_sb, const char *fromName,
 175                   const char *toName)
 176 {
 177         int rc;
 178         u8 *buf;
 179         unsigned int bytes_written = 0;
 180
 181         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 182         if (!buf)
 183                 return -ENOMEM;
 184
 185         rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
 186         if (rc)
 187                 goto out;
 188
 189         if (tcon->ses->server->ops->create_mf_symlink)
 190                 rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
 191                                         cifs_sb, fromName, buf, &bytes_written);
 192         else
 193                 rc = -EOPNOTSUPP;
 194
 195         if (rc)
 196                 goto out;
 197
 198         if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
 199                 rc = -EIO;
 200 out:
 201         kfree(buf);
 202         return rc;
 203 }
 204
 205 static int
 206 query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 207                  struct cifs_sb_info *cifs_sb, const unsigned char *path,
 208                  char **symlinkinfo)
 209 {
 210         int rc;
 211         u8 *buf = NULL;
 212         unsigned int link_len = 0;
 213         unsigned int bytes_read = 0;
 214
 215         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 216         if (!buf)
 217                 return -ENOMEM;
 218
 219         if (tcon->ses->server->ops->query_mf_symlink)
 220                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 221                                               cifs_sb, path, buf, &bytes_read);
 222         else
 223                 rc = -ENOSYS;
 224
 225         if (rc)
 226                 goto out;
 227
 228         if (bytes_read == 0) { /* not a symlink */
 229                 rc = -EINVAL;
 230                 goto out;
 231         }
 232
 233         rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
 234 out:
 235         kfree(buf);
 236         return rc;
 237 }
 238
 239 int
 240 check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 241                  struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
 242                  const unsigned char *path)
 243 {
 244         int rc;
 245         u8 *buf = NULL;
 246         unsigned int link_len = 0;
 247         unsigned int bytes_read = 0;
 248
 249         if (!couldbe_mf_symlink(fattr))
 250                 /* it's not a symlink */
 251                 return 0;
 252
 253         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
 254         if (!buf)
 255                 return -ENOMEM;
 256
 257         if (tcon->ses->server->ops->query_mf_symlink)
 258                 rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
 259                                               cifs_sb, path, buf, &bytes_read);
 260         else
 261                 rc = -ENOSYS;
 262
 263         if (rc)
 264                 goto out;
 265
 266         if (bytes_read == 0) /* not a symlink */
 267                 goto out;
 268
 269         rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
 270         if (rc == -EINVAL) {
 271                 /* it's not a symlink */
 272                 rc = 0;
 273                 goto out;
 274         }
 275
 276         if (rc != 0)
 277                 goto out;
 278
 279         /* it is a symlink */
 280         fattr->cf_eof = link_len;
 281         fattr->cf_mode &= ~S_IFMT;
 282         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
 283         fattr->cf_dtype = DT_LNK;
 284 out:
 285         kfree(buf);
 286         return rc;
 287 }
 288
 289 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
 290 /*
 291  * SMB 1.0 Protocol specific functions
 292  */
 293
 294 int
 295 cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 296                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
 297                       char *pbuf, unsigned int *pbytes_read)
 298 {
 299         int rc;
 300         int oplock = 0;
 301         struct cifs_fid fid;
 302         struct cifs_open_parms oparms;
 303         struct cifs_io_parms io_parms = {0};
 304         int buf_type = CIFS_NO_BUFFER;
 305         FILE_ALL_INFO file_info;
 306
 307         oparms.tcon = tcon;
 308         oparms.cifs_sb = cifs_sb;
 309         oparms.desired_access = GENERIC_READ;
 310         oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
 311         oparms.disposition = FILE_OPEN;
 312         oparms.path = path;
 313         oparms.fid = &fid;
 314         oparms.reconnect = false;
 315
 316         rc = CIFS_open(xid, &oparms, &oplock, &file_info);
 317         if (rc)
 318                 return rc;
 319
 320         if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 321                 rc = -ENOENT;
 322                 /* it's not a symlink */
 323                 goto out;
 324         }
 325
 326         io_parms.netfid = fid.netfid;
 327         io_parms.pid = current->tgid;
 328         io_parms.tcon = tcon;
 329         io_parms.offset = 0;
 330         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 331
 332         rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
 333 out:
 334         CIFSSMBClose(xid, tcon, fid.netfid);
 335         return rc;
 336 }
 337
 338 int
 339 cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 340                        struct cifs_sb_info *cifs_sb, const unsigned char *path,
 341                        char *pbuf, unsigned int *pbytes_written)
 342 {
 343         int rc;
 344         int oplock = 0;
 345         struct cifs_fid fid;
 346         struct cifs_open_parms oparms;
 347         struct cifs_io_parms io_parms = {0};
 348
 349         oparms.tcon = tcon;
 350         oparms.cifs_sb = cifs_sb;
 351         oparms.desired_access = GENERIC_WRITE;
 352         oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
 353         oparms.disposition = FILE_CREATE;
 354         oparms.path = path;
 355         oparms.fid = &fid;
 356         oparms.reconnect = false;
 357
 358         rc = CIFS_open(xid, &oparms, &oplock, NULL);
 359         if (rc)
 360                 return rc;
 361
 362         io_parms.netfid = fid.netfid;
 363         io_parms.pid = current->tgid;
 364         io_parms.tcon = tcon;
 365         io_parms.offset = 0;
 366         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 367
 368         rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf);
 369         CIFSSMBClose(xid, tcon, fid.netfid);
 370         return rc;
 371 }
 372 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 373
 374 /*
 375  * SMB 2.1/SMB3 Protocol specific functions
 376  */
 377 int
 378 smb3_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 379                       struct cifs_sb_info *cifs_sb, const unsigned char *path,
 380                       char *pbuf, unsigned int *pbytes_read)
 381 {
 382         int rc;
 383         struct cifs_fid fid;
 384         struct cifs_open_parms oparms;
 385         struct cifs_io_parms io_parms = {0};
 386         int buf_type = CIFS_NO_BUFFER;
 387         __le16 *utf16_path;
 388         __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 389         struct smb2_file_all_info *pfile_info = NULL;
 390
 391         oparms.tcon = tcon;
 392         oparms.cifs_sb = cifs_sb;
 393         oparms.desired_access = GENERIC_READ;
 394         oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
 395         oparms.disposition = FILE_OPEN;
 396         oparms.fid = &fid;
 397         oparms.reconnect = false;
 398
 399         utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
 400         if (utf16_path == NULL)
 401                 return -ENOMEM;
 402
 403         pfile_info = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
 404                              GFP_KERNEL);
 405
 406         if (pfile_info == NULL) {
 407                 kfree(utf16_path);
 408                 return  -ENOMEM;
 409         }
 410
 411         rc = SMB2_open(xid, &oparms, utf16_path, &oplock, pfile_info, NULL,
 412                        NULL, NULL);
 413         if (rc)
 414                 goto qmf_out_open_fail;
 415
 416         if (pfile_info->EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
 417                 /* it's not a symlink */
 418                 rc = -ENOENT; /* Is there a better rc to return? */
 419                 goto qmf_out;
 420         }
 421
 422         io_parms.netfid = fid.netfid;
 423         io_parms.pid = current->tgid;
 424         io_parms.tcon = tcon;
 425         io_parms.offset = 0;
 426         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 427         io_parms.persistent_fid = fid.persistent_fid;
 428         io_parms.volatile_fid = fid.volatile_fid;
 429         rc = SMB2_read(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
 430 qmf_out:
 431         SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
 432 qmf_out_open_fail:
 433         kfree(utf16_path);
 434         kfree(pfile_info);
 435         return rc;
 436 }
 437
 438 int
 439 smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 440                        struct cifs_sb_info *cifs_sb, const unsigned char *path,
 441                        char *pbuf, unsigned int *pbytes_written)
 442 {
 443         int rc;
 444         struct cifs_fid fid;
 445         struct cifs_open_parms oparms;
 446         struct cifs_io_parms io_parms = {0};
 447         __le16 *utf16_path;
 448         __u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 449         struct kvec iov[2];
 450
 451         cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
 452
 453         utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
 454         if (!utf16_path)
 455                 return -ENOMEM;
 456
 457         oparms.tcon = tcon;
 458         oparms.cifs_sb = cifs_sb;
 459         oparms.desired_access = GENERIC_WRITE;
 460         oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
 461         oparms.disposition = FILE_CREATE;
 462         oparms.fid = &fid;
 463         oparms.reconnect = false;
 464
 465         rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
 466                        NULL, NULL);
 467         if (rc) {
 468                 kfree(utf16_path);
 469                 return rc;
 470         }
 471
 472         io_parms.netfid = fid.netfid;
 473         io_parms.pid = current->tgid;
 474         io_parms.tcon = tcon;
 475         io_parms.offset = 0;
 476         io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
 477         io_parms.persistent_fid = fid.persistent_fid;
 478         io_parms.volatile_fid = fid.volatile_fid;
 479
 480         /* iov[0] is reserved for smb header */
 481         iov[1].iov_base = pbuf;
 482         iov[1].iov_len = CIFS_MF_SYMLINK_FILE_SIZE;
 483
 484         rc = SMB2_write(xid, &io_parms, pbytes_written, iov, 1);
 485
 486         /* Make sure we wrote all of the symlink data */
 487         if ((rc == 0) && (*pbytes_written != CIFS_MF_SYMLINK_FILE_SIZE))
 488                 rc = -EIO;
 489
 490         SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
 491
 492         kfree(utf16_path);
 493         return rc;
 494 }
 495
 496 /*
 497  * M-F Symlink Functions - End
 498  */
 499
 500 int
 501 cifs_hardlink(struct dentry *old_file, struct inode *inode,
 502               struct dentry *direntry)
 503 {
 504         int rc = -EACCES;
 505         unsigned int xid;
 506         const char *from_name, *to_name;
 507         void *page1, *page2;
 508         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 509         struct tcon_link *tlink;
 510         struct cifs_tcon *tcon;
 511         struct TCP_Server_Info *server;
 512         struct cifsInodeInfo *cifsInode;
 513
 514         if (unlikely(cifs_forced_shutdown(cifs_sb)))
 515                 return -EIO;
 516
 517         tlink = cifs_sb_tlink(cifs_sb);
 518         if (IS_ERR(tlink))
 519                 return PTR_ERR(tlink);
 520         tcon = tlink_tcon(tlink);
 521
 522         xid = get_xid();
 523         page1 = alloc_dentry_path();
 524         page2 = alloc_dentry_path();
 525
 526         from_name = build_path_from_dentry(old_file, page1);
 527         if (IS_ERR(from_name)) {
 528                 rc = PTR_ERR(from_name);
 529                 goto cifs_hl_exit;
 530         }
 531         to_name = build_path_from_dentry(direntry, page2);
 532         if (IS_ERR(to_name)) {
 533                 rc = PTR_ERR(to_name);
 534                 goto cifs_hl_exit;
 535         }
 536
 537 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
 538         if (tcon->unix_ext)
 539                 rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
 540                                             cifs_sb->local_nls,
 541                                             cifs_remap(cifs_sb));
 542         else {
 543 #else
 544         {
 545 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 546                 server = tcon->ses->server;
 547                 if (!server->ops->create_hardlink) {
 548                         rc = -ENOSYS;
 549                         goto cifs_hl_exit;
 550                 }
 551                 rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
 552                                                   cifs_sb);
 553                 if ((rc == -EIO) || (rc == -EINVAL))
 554                         rc = -EOPNOTSUPP;
 555         }
 556
 557         d_drop(direntry);       /* force new lookup from server of target */
 558
 559         /*
 560          * if source file is cached (oplocked) revalidate will not go to server
 561          * until the file is closed or oplock broken so update nlinks locally
 562          */
 563         if (d_really_is_positive(old_file)) {
 564                 cifsInode = CIFS_I(d_inode(old_file));
 565                 if (rc == 0) {
 566                         spin_lock(&d_inode(old_file)->i_lock);
 567                         inc_nlink(d_inode(old_file));
 568                         spin_unlock(&d_inode(old_file)->i_lock);
 569
 570                         /*
 571                          * parent dir timestamps will update from srv within a
 572                          * second, would it really be worth it to set the parent
 573                          * dir cifs inode time to zero to force revalidate
 574                          * (faster) for it too?
 575                          */
 576                 }
 577                 /*
 578                  * if not oplocked will force revalidate to get info on source
 579                  * file from srv.  Note Samba server prior to 4.2 has bug -
 580                  * not updating src file ctime on hardlinks but Windows servers
 581                  * handle it properly
 582                  */
 583                 cifsInode->time = 0;
 584
 585                 /*
 586                  * Will update parent dir timestamps from srv within a second.
 587                  * Would it really be worth it to set the parent dir (cifs
 588                  * inode) time field to zero to force revalidate on parent
 589                  * directory faster ie
 590                  *
 591                  * CIFS_I(inode)->time = 0;
 592                  */
 593         }
 594
 595 cifs_hl_exit:
 596         free_dentry_path(page1);
 597         free_dentry_path(page2);
 598         free_xid(xid);
 599         cifs_put_tlink(tlink);
 600         return rc;
 601 }
 602
 603 const char *
 604 cifs_get_link(struct dentry *direntry, struct inode *inode,
 605               struct delayed_call *done)
 606 {
 607         int rc = -ENOMEM;
 608         unsigned int xid;
 609         const char *full_path;
 610         void *page;
 611         char *target_path = NULL;
 612         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 613         struct tcon_link *tlink = NULL;
 614         struct cifs_tcon *tcon;
 615         struct TCP_Server_Info *server;
 616
 617         if (!direntry)
 618                 return ERR_PTR(-ECHILD);
 619
 620         xid = get_xid();
 621
 622         tlink = cifs_sb_tlink(cifs_sb);
 623         if (IS_ERR(tlink)) {
 624                 free_xid(xid);
 625                 return ERR_CAST(tlink);
 626         }
 627         tcon = tlink_tcon(tlink);
 628         server = tcon->ses->server;
 629
 630         page = alloc_dentry_path();
 631         full_path = build_path_from_dentry(direntry, page);
 632         if (IS_ERR(full_path)) {
 633                 free_xid(xid);
 634                 cifs_put_tlink(tlink);
 635                 free_dentry_path(page);
 636                 return ERR_CAST(full_path);
 637         }
 638
 639         cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
 640
 641         rc = -EACCES;
 642         /*
 643          * First try Minshall+French Symlinks, if configured
 644          * and fallback to UNIX Extensions Symlinks.
 645          */
 646         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 647                 rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
 648                                       &target_path);
 649
 650         if (rc != 0 && server->ops->query_symlink) {
 651                 struct cifsInodeInfo *cifsi = CIFS_I(inode);
 652                 bool reparse_point = false;
 653
 654                 if (cifsi->cifsAttrs & ATTR_REPARSE)
 655                         reparse_point = true;
 656
 657                 rc = server->ops->query_symlink(xid, tcon, cifs_sb, full_path,
 658                                                 &target_path, reparse_point);
 659         }
 660
 661         free_dentry_path(page);
 662         free_xid(xid);
 663         cifs_put_tlink(tlink);
 664         if (rc != 0) {
 665                 kfree(target_path);
 666                 return ERR_PTR(rc);
 667         }
 668         set_delayed_call(done, kfree_link, target_path);
 669         return target_path;
 670 }
 671
 672 int
 673 cifs_symlink(struct user_namespace *mnt_userns, struct inode *inode,
 674              struct dentry *direntry, const char *symname)
 675 {
 676         int rc = -EOPNOTSUPP;
 677         unsigned int xid;
 678         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 679         struct tcon_link *tlink;
 680         struct cifs_tcon *pTcon;
 681         const char *full_path;
 682         void *page;
 683         struct inode *newinode = NULL;
 684
 685         if (unlikely(cifs_forced_shutdown(cifs_sb)))
 686                 return -EIO;
 687
 688         page = alloc_dentry_path();
 689         if (!page)
 690                 return -ENOMEM;
 691
 692         xid = get_xid();
 693
 694         tlink = cifs_sb_tlink(cifs_sb);
 695         if (IS_ERR(tlink)) {
 696                 rc = PTR_ERR(tlink);
 697                 goto symlink_exit;
 698         }
 699         pTcon = tlink_tcon(tlink);
 700
 701         full_path = build_path_from_dentry(direntry, page);
 702         if (IS_ERR(full_path)) {
 703                 rc = PTR_ERR(full_path);
 704                 goto symlink_exit;
 705         }
 706
 707         cifs_dbg(FYI, "Full path: %s\n", full_path);
 708         cifs_dbg(FYI, "symname is %s\n", symname);
 709
 710         /* BB what if DFS and this volume is on different share? BB */
 711         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
 712                 rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
 713 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
 714         else if (pTcon->unix_ext)
 715                 rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
 716                                            cifs_sb->local_nls,
 717                                            cifs_remap(cifs_sb));
 718 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 719         /* else
 720            rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
 721                                         cifs_sb_target->local_nls); */
 722
 723         if (rc == 0) {
 724                 if (pTcon->posix_extensions)
 725                         rc = smb311_posix_get_inode_info(&newinode, full_path, inode->i_sb, xid);
 726                 else if (pTcon->unix_ext)
 727                         rc = cifs_get_inode_info_unix(&newinode, full_path,
 728                                                       inode->i_sb, xid);
 729                 else
 730                         rc = cifs_get_inode_info(&newinode, full_path, NULL,
 731                                                  inode->i_sb, xid, NULL);
 732
 733                 if (rc != 0) {
 734                         cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
 735                                  rc);
 736                 } else {
 737                         d_instantiate(direntry, newinode);
 738                 }
 739         }
 740 symlink_exit:
 741         free_dentry_path(page);
 742         cifs_put_tlink(tlink);
 743         free_xid(xid);
 744         return rc;
 745 }