source/modules/vfs_streams_depot.c

   1 /*
   2  * Store streams in a separate subdirectory
   3  *
   4  * Copyright (C) Volker Lendecke, 2007
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21
  22 #undef DBGC_CLASS
  23 #define DBGC_CLASS DBGC_VFS
  24
  25 /*
  26  * Excerpt from a mail from tridge:
  27  *
  28  * Volker, what I'm thinking of is this:
  29  * /mount-point/.streams/XX/YY/aaaa.bbbb/namedstream1
  30  * /mount-point/.streams/XX/YY/aaaa.bbbb/namedstream2
  31  *
  32  * where XX/YY is a 2 level hash based on the fsid/inode. "aaaa.bbbb"
  33  * is the fsid/inode. "namedstreamX" is a file named after the stream
  34  * name.
  35  */
  36
  37 static uint32_t hash_fn(DATA_BLOB key)
  38 {
  39         uint32_t value; /* Used to compute the hash value.  */
  40         uint32_t i;     /* Used to cycle through random values. */
  41
  42         /* Set the initial value from the key size. */
  43         for (value = 0x238F13AF * key.length, i=0; i < key.length; i++)
  44                 value = (value + (key.data[i] << (i*5 % 24)));
  45
  46         return (1103515243 * value + 12345);
  47 }
  48
  49 /*
  50  * With the hashing scheme based on the inode we need to protect against
  51  * streams showing up on files with re-used inodes. This can happen if we
  52  * create a stream directory from within Samba, and a local process or NFS
  53  * client deletes the file without deleting the streams directory. When the
  54  * inode is re-used and the stream directory is still around, the streams in
  55  * there would be show up as belonging to the new file.
  56  *
  57  * There are several workarounds for this, probably the easiest one is on
  58  * systems which have a true birthtime stat element: When the file has a later
  59  * birthtime than the streams directory, then we have to recreate the
  60  * directory.
  61  *
  62  * The other workaround is to somehow mark the file as generated by Samba with
  63  * something that a NFS client would not do. The closest one is a special
  64  * xattr value being set. On systems which do not support xattrs, it might be
  65  * an option to put in a special ACL entry for a non-existing group.
  66  */
  67
  68 #define SAMBA_XATTR_MARKER "user.SAMBA_STREAMS"
  69
  70 static bool file_is_valid(vfs_handle_struct *handle, const char *path)
  71 {
  72         char buf;
  73
  74         DEBUG(10, ("file_is_valid (%s) called\n", path));
  75
  76         if (SMB_VFS_NEXT_GETXATTR(handle, path, SAMBA_XATTR_MARKER,
  77                                   &buf, sizeof(buf)) != sizeof(buf)) {
  78                 DEBUG(10, ("GETXATTR failed: %s\n", strerror(errno)));
  79                 return false;
  80         }
  81
  82         if (buf != '1') {
  83                 DEBUG(10, ("got wrong buffer content: '%c'\n", buf));
  84                 return false;
  85         }
  86
  87         return true;
  88 }
  89
  90 static bool mark_file_valid(vfs_handle_struct *handle, const char *path)
  91 {
  92         char buf = '1';
  93         int ret;
  94
  95         DEBUG(10, ("marking file %s as valid\n", path));
  96
  97         ret = SMB_VFS_NEXT_SETXATTR(handle, path, SAMBA_XATTR_MARKER,
  98                                     &buf, sizeof(buf), 0);
  99
 100         if (ret == -1) {
 101                 DEBUG(10, ("SETXATTR failed: %s\n", strerror(errno)));
 102                 return false;
 103         }
 104
 105         return true;
 106 }
 107
 108 static char *stream_dir(vfs_handle_struct *handle, const char *base_path,
 109                         const SMB_STRUCT_STAT *base_sbuf, bool create_it)
 110 {
 111         uint32_t hash;
 112         char *result = NULL;
 113         SMB_STRUCT_STAT sbuf;
 114         uint8_t first, second;
 115         char *tmp;
 116         char *id_hex;
 117         struct file_id id;
 118         uint8 id_buf[16];
 119
 120         tmp = talloc_asprintf(talloc_tos(), "%s/.streams", handle->conn->connectpath);
 121
 122         if (tmp == NULL) {
 123                 errno = ENOMEM;
 124                 goto fail;
 125         }
 126
 127         const char *rootdir = lp_parm_const_string(
 128                 SNUM(handle->conn), "streams_depot", "directory",
 129                 tmp);
 130         TALLOC_FREE(tmp);
 131
 132         if (base_sbuf == NULL) {
 133                 if (SMB_VFS_NEXT_STAT(handle, base_path, &sbuf) == -1) {
 134                         /*
 135                          * base file is not there
 136                          */
 137                         goto fail;
 138                 }
 139                 base_sbuf = &sbuf;
 140         }
 141
 142         id = SMB_VFS_FILE_ID_CREATE(handle->conn, base_sbuf->st_dev,
 143                                     base_sbuf->st_ino);
 144
 145         push_file_id_16((char *)id_buf, &id);
 146
 147         hash = hash_fn(data_blob_const(id_buf, sizeof(id_buf)));
 148
 149         first = hash & 0xff;
 150         second = (hash >> 8) & 0xff;
 151
 152         id_hex = hex_encode(talloc_tos(), id_buf, sizeof(id_buf));
 153
 154         if (id_hex == NULL) {
 155                 errno = ENOMEM;
 156                 goto fail;
 157         }
 158
 159         result = talloc_asprintf(talloc_tos(), "%s/%2.2X/%2.2X/%s", rootdir,
 160                                  first, second, id_hex);
 161
 162         TALLOC_FREE(id_hex);
 163
 164         if (result == NULL) {
 165                 errno = ENOMEM;
 166                 return NULL;
 167         }
 168
 169         if (SMB_VFS_NEXT_STAT(handle, result, &sbuf) == 0) {
 170                 char *newname;
 171
 172                 if (!S_ISDIR(sbuf.st_mode)) {
 173                         errno = EINVAL;
 174                         goto fail;
 175                 }
 176
 177                 if (file_is_valid(handle, base_path)) {
 178                         return result;
 179                 }
 180
 181                 /*
 182                  * Someone has recreated a file under an existing inode
 183                  * without deleting the streams directory. For now, just move
 184                  * it away.
 185                  */
 186
 187         again:
 188                 newname = talloc_asprintf(talloc_tos(), "lost-%lu", random());
 189                 if (newname == NULL) {
 190                         errno = ENOMEM;
 191                         goto fail;
 192                 }
 193
 194                 if (SMB_VFS_NEXT_RENAME(handle, result, newname) == -1) {
 195                         if ((errno == EEXIST) || (errno == ENOTEMPTY)) {
 196                                 TALLOC_FREE(newname);
 197                                 goto again;
 198                         }
 199                         goto fail;
 200                 }
 201
 202                 TALLOC_FREE(newname);
 203         }
 204
 205         if (!create_it) {
 206                 errno = ENOENT;
 207                 goto fail;
 208         }
 209
 210         if ((SMB_VFS_NEXT_MKDIR(handle, rootdir, 0755) != 0)
 211             && (errno != EEXIST)) {
 212                 goto fail;
 213         }
 214
 215         tmp = talloc_asprintf(result, "%s/%2.2X", rootdir, first);
 216         if (tmp == NULL) {
 217                 errno = ENOMEM;
 218                 goto fail;
 219         }
 220
 221         if ((SMB_VFS_NEXT_MKDIR(handle, tmp, 0755) != 0)
 222             && (errno != EEXIST)) {
 223                 goto fail;
 224         }
 225
 226         TALLOC_FREE(tmp);
 227
 228         tmp = talloc_asprintf(result, "%s/%2.2X/%2.2X", rootdir, first,
 229                               second);
 230         if (tmp == NULL) {
 231                 errno = ENOMEM;
 232                 goto fail;
 233         }
 234
 235         if ((SMB_VFS_NEXT_MKDIR(handle, tmp, 0755) != 0)
 236             && (errno != EEXIST)) {
 237                 goto fail;
 238         }
 239
 240         TALLOC_FREE(tmp);
 241
 242         if ((SMB_VFS_NEXT_MKDIR(handle, result, 0755) != 0)
 243             && (errno != EEXIST)) {
 244                 goto fail;
 245         }
 246
 247         if (!mark_file_valid(handle, base_path)) {
 248                 goto fail;
 249         }
 250
 251         return result;
 252
 253  fail:
 254         TALLOC_FREE(result);
 255         return NULL;
 256 }
 257
 258 static char *stream_name(vfs_handle_struct *handle, const char *fname,
 259                          bool create_dir)
 260 {
 261         char *base = NULL;
 262         char *sname = NULL;
 263         char *id_hex = NULL;
 264         char *dirname, *stream_fname;
 265
 266         if (!NT_STATUS_IS_OK(split_ntfs_stream_name(talloc_tos(), fname,
 267                                                     &base, &sname))) {
 268                 DEBUG(10, ("split_ntfs_stream_name failed\n"));
 269                 errno = ENOMEM;
 270                 goto fail;
 271         }
 272
 273         dirname = stream_dir(handle, base, NULL, create_dir);
 274
 275         if (dirname == NULL) {
 276                 goto fail;
 277         }
 278
 279         stream_fname = talloc_asprintf(talloc_tos(), "%s/:%s", dirname, sname);
 280
 281         if (stream_fname == NULL) {
 282                 errno = ENOMEM;
 283                 goto fail;
 284         }
 285
 286         DEBUG(10, ("stream filename = %s\n", stream_fname));
 287
 288         TALLOC_FREE(base);
 289         TALLOC_FREE(sname);
 290         TALLOC_FREE(id_hex);
 291
 292         return stream_fname;
 293
 294  fail:
 295         DEBUG(5, ("stream_name failed: %s\n", strerror(errno)));
 296         TALLOC_FREE(base);
 297         TALLOC_FREE(sname);
 298         TALLOC_FREE(id_hex);
 299         return NULL;
 300 }
 301
 302 static NTSTATUS walk_streams(vfs_handle_struct *handle,
 303                              const char *fname,
 304                              const SMB_STRUCT_STAT *sbuf,
 305                              char **pdirname,
 306                              bool (*fn)(const char *dirname,
 307                                         const char *dirent,
 308                                         void *private_data),
 309                              void *private_data)
 310 {
 311         char *dirname;
 312         SMB_STRUCT_DIR *dirhandle = NULL;
 313         char *dirent;
 314
 315         dirname = stream_dir(handle, fname, sbuf, false);
 316
 317         if (dirname == NULL) {
 318                 if (errno == ENOENT) {
 319                         /*
 320                          * no stream around
 321                          */
 322                         return NT_STATUS_OK;
 323                 }
 324                 return map_nt_error_from_unix(errno);
 325         }
 326
 327         DEBUG(10, ("walk_streams: dirname=%s\n", dirname));
 328
 329         dirhandle = SMB_VFS_NEXT_OPENDIR(handle, dirname, NULL, 0);
 330
 331         if (dirhandle == NULL) {
 332                 TALLOC_FREE(dirname);
 333                 return map_nt_error_from_unix(errno);
 334         }
 335
 336         while ((dirent = vfs_readdirname(handle->conn, dirhandle)) != NULL) {
 337
 338                 if (ISDOT(dirent) || ISDOTDOT(dirent)) {
 339                         continue;
 340                 }
 341
 342                 DEBUG(10, ("walk_streams: dirent=%s\n", dirent));
 343
 344                 if (!fn(dirname, dirent, private_data)) {
 345                         break;
 346                 }
 347         }
 348
 349         SMB_VFS_NEXT_CLOSEDIR(handle, dirhandle);
 350
 351         if (pdirname != NULL) {
 352                 *pdirname = dirname;
 353         }
 354         else {
 355                 TALLOC_FREE(dirname);
 356         }
 357
 358         return NT_STATUS_OK;
 359 }
 360
 361 static int streams_depot_stat(vfs_handle_struct *handle, const char *fname,
 362                               SMB_STRUCT_STAT *sbuf)
 363 {
 364         char *stream_fname;
 365         int ret = -1;
 366
 367         DEBUG(10, ("streams_depot_stat called for [%s]\n", fname));
 368
 369         if (!is_ntfs_stream_name(fname)) {
 370                 return SMB_VFS_NEXT_STAT(handle, fname, sbuf);
 371         }
 372
 373         stream_fname = stream_name(handle, fname, false);
 374         if (stream_fname == NULL) {
 375                 goto done;
 376         }
 377
 378         ret = SMB_VFS_NEXT_STAT(handle, stream_fname, sbuf);
 379
 380  done:
 381         TALLOC_FREE(stream_fname);
 382         return ret;
 383 }
 384
 385 static int streams_depot_lstat(vfs_handle_struct *handle, const char *fname,
 386                                SMB_STRUCT_STAT *sbuf)
 387 {
 388         char *stream_fname;
 389         int ret = -1;
 390
 391         if (!is_ntfs_stream_name(fname)) {
 392                 return SMB_VFS_NEXT_LSTAT(handle, fname, sbuf);
 393         }
 394
 395         stream_fname = stream_name(handle, fname, false);
 396         if (stream_fname == NULL) {
 397                 goto done;
 398         }
 399
 400         ret = SMB_VFS_NEXT_LSTAT(handle, stream_fname, sbuf);
 401
 402  done:
 403         TALLOC_FREE(stream_fname);
 404         return ret;
 405 }
 406
 407 static int streams_depot_open(vfs_handle_struct *handle,  const char *fname,
 408                               files_struct *fsp, int flags, mode_t mode)
 409 {
 410         TALLOC_CTX *frame;
 411         char *base = NULL;
 412         SMB_STRUCT_STAT base_sbuf;
 413         char *stream_fname;
 414         int ret = -1;
 415
 416         if (!is_ntfs_stream_name(fname)) {
 417                 return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
 418         }
 419
 420         frame = talloc_stackframe();
 421
 422         if (!NT_STATUS_IS_OK(split_ntfs_stream_name(talloc_tos(), fname,
 423                                                     &base, NULL))) {
 424                 errno = ENOMEM;
 425                 goto done;
 426         }
 427
 428         ret = SMB_VFS_NEXT_STAT(handle, base, &base_sbuf);
 429
 430         if (ret == -1) {
 431                 goto done;
 432         }
 433
 434         TALLOC_FREE(base);
 435
 436         stream_fname = stream_name(handle, fname, true);
 437         if (stream_fname == NULL) {
 438                 goto done;
 439         }
 440
 441         ret = SMB_VFS_NEXT_OPEN(handle, stream_fname, fsp, flags, mode);
 442
 443  done:
 444         TALLOC_FREE(frame);
 445         return ret;
 446 }
 447
 448 static int streams_depot_unlink(vfs_handle_struct *handle,  const char *fname)
 449 {
 450         int ret = -1;
 451         SMB_STRUCT_STAT sbuf;
 452
 453         DEBUG(10, ("streams_depot_unlink called for %s\n", fname));
 454
 455         if (is_ntfs_stream_name(fname)) {
 456                 char *stream_fname;
 457
 458                 stream_fname = stream_name(handle, fname, false);
 459                 if (stream_fname == NULL) {
 460                         return -1;
 461                 }
 462
 463                 ret = SMB_VFS_NEXT_UNLINK(handle, stream_fname);
 464
 465                 TALLOC_FREE(stream_fname);
 466                 return ret;
 467         }
 468
 469         /*
 470          * We potentially need to delete the per-inode streams directory
 471          */
 472
 473         if (SMB_VFS_NEXT_STAT(handle, fname, &sbuf) == -1) {
 474                 return -1;
 475         }
 476
 477         if (sbuf.st_nlink == 1) {
 478                 char *dirname = stream_dir(handle, fname, &sbuf, false);
 479
 480                 if (dirname != NULL) {
 481                         SMB_VFS_NEXT_RMDIR(handle, dirname);
 482                 }
 483                 TALLOC_FREE(dirname);
 484         }
 485
 486         return SMB_VFS_NEXT_UNLINK(handle, fname);
 487 }
 488
 489 static bool add_one_stream(TALLOC_CTX *mem_ctx, unsigned int *num_streams,
 490                            struct stream_struct **streams,
 491                            const char *name, SMB_OFF_T size,
 492                            SMB_OFF_T alloc_size)
 493 {
 494         struct stream_struct *tmp;
 495
 496         tmp = TALLOC_REALLOC_ARRAY(mem_ctx, *streams, struct stream_struct,
 497                                    (*num_streams)+1);
 498         if (tmp == NULL) {
 499                 return false;
 500         }
 501
 502         tmp[*num_streams].name = talloc_strdup(tmp, name);
 503         if (tmp[*num_streams].name == NULL) {
 504                 return false;
 505         }
 506
 507         tmp[*num_streams].size = size;
 508         tmp[*num_streams].alloc_size = alloc_size;
 509
 510         *streams = tmp;
 511         *num_streams += 1;
 512         return true;
 513 }
 514
 515 struct streaminfo_state {
 516         TALLOC_CTX *mem_ctx;
 517         vfs_handle_struct *handle;
 518         unsigned int num_streams;
 519         struct stream_struct *streams;
 520         NTSTATUS status;
 521 };
 522
 523 static bool collect_one_stream(const char *dirname,
 524                                const char *dirent,
 525                                void *private_data)
 526 {
 527         struct streaminfo_state *state =
 528                 (struct streaminfo_state *)private_data;
 529         char *full_sname;
 530         SMB_STRUCT_STAT sbuf;
 531
 532         if (asprintf(&full_sname, "%s/%s", dirname, dirent) == -1) {
 533                 state->status = NT_STATUS_NO_MEMORY;
 534                 return false;
 535         }
 536         if (SMB_VFS_NEXT_STAT(state->handle, full_sname, &sbuf) == -1) {
 537                 DEBUG(10, ("Could not stat %s: %s\n", full_sname,
 538                            strerror(errno)));
 539                 SAFE_FREE(full_sname);
 540                 return true;
 541         }
 542
 543         SAFE_FREE(full_sname);
 544
 545         if (!add_one_stream(state->mem_ctx,
 546                             &state->num_streams, &state->streams,
 547                             dirent, sbuf.st_size,
 548                             get_allocation_size(
 549                                     state->handle->conn, NULL, &sbuf))) {
 550                 state->status = NT_STATUS_NO_MEMORY;
 551                 return false;
 552         }
 553
 554         return true;
 555 }
 556
 557 static NTSTATUS streams_depot_streaminfo(vfs_handle_struct *handle,
 558                                          struct files_struct *fsp,
 559                                          const char *fname,
 560                                          TALLOC_CTX *mem_ctx,
 561                                          unsigned int *pnum_streams,
 562                                          struct stream_struct **pstreams)
 563 {
 564         SMB_STRUCT_STAT sbuf;
 565         int ret;
 566         NTSTATUS status;
 567         struct streaminfo_state state;
 568
 569         if ((fsp != NULL) && (fsp->fh->fd != -1)) {
 570                 if (is_ntfs_stream_name(fsp->fsp_name)) {
 571                         return NT_STATUS_INVALID_PARAMETER;
 572                 }
 573                 ret = SMB_VFS_NEXT_FSTAT(handle, fsp, &sbuf);
 574         }
 575         else {
 576                 if (is_ntfs_stream_name(fname)) {
 577                         return NT_STATUS_INVALID_PARAMETER;
 578                 }
 579                 ret = SMB_VFS_NEXT_STAT(handle, fname, &sbuf);
 580         }
 581
 582         if (ret == -1) {
 583                 return map_nt_error_from_unix(errno);
 584         }
 585
 586         state.streams = NULL;
 587         state.num_streams = 0;
 588
 589         if (!S_ISDIR(sbuf.st_mode)) {
 590                 if (!add_one_stream(mem_ctx,
 591                                     &state.num_streams, &state.streams,
 592                                     "::$DATA", sbuf.st_size,
 593                                     get_allocation_size(handle->conn, fsp,
 594                                                         &sbuf))) {
 595                         return NT_STATUS_NO_MEMORY;
 596                 }
 597         }
 598
 599         state.mem_ctx = mem_ctx;
 600         state.handle = handle;
 601         state.status = NT_STATUS_OK;
 602
 603         status = walk_streams(handle, fname, &sbuf, NULL, collect_one_stream,
 604                               &state);
 605
 606         if (!NT_STATUS_IS_OK(status)) {
 607                 TALLOC_FREE(state.streams);
 608                 return status;
 609         }
 610
 611         if (!NT_STATUS_IS_OK(state.status)) {
 612                 TALLOC_FREE(state.streams);
 613                 return state.status;
 614         }
 615
 616         *pnum_streams = state.num_streams;
 617         *pstreams = state.streams;
 618         return NT_STATUS_OK;
 619 }
 620
 621 static uint32_t streams_depot_fs_capabilities(struct vfs_handle_struct *handle)
 622 {
 623         return SMB_VFS_NEXT_FS_CAPABILITIES(handle) | FILE_NAMED_STREAMS;
 624 }
 625
 626 /* VFS operations structure */
 627
 628 static vfs_op_tuple streams_depot_ops[] = {
 629         {SMB_VFS_OP(streams_depot_fs_capabilities), SMB_VFS_OP_FS_CAPABILITIES,
 630          SMB_VFS_LAYER_TRANSPARENT},
 631         {SMB_VFS_OP(streams_depot_open), SMB_VFS_OP_OPEN,
 632          SMB_VFS_LAYER_TRANSPARENT},
 633         {SMB_VFS_OP(streams_depot_stat), SMB_VFS_OP_STAT,
 634          SMB_VFS_LAYER_TRANSPARENT},
 635         {SMB_VFS_OP(streams_depot_lstat), SMB_VFS_OP_LSTAT,
 636          SMB_VFS_LAYER_TRANSPARENT},
 637         {SMB_VFS_OP(streams_depot_unlink), SMB_VFS_OP_UNLINK,
 638          SMB_VFS_LAYER_TRANSPARENT},
 639         {SMB_VFS_OP(streams_depot_streaminfo), SMB_VFS_OP_STREAMINFO,
 640          SMB_VFS_LAYER_OPAQUE},
 641         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 642 };
 643
 644 NTSTATUS vfs_streams_depot_init(void);
 645 NTSTATUS vfs_streams_depot_init(void)
 646 {
 647         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "streams_depot",
 648                                 streams_depot_ops);
 649 }