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         const char *rootdir;
 120
 121         tmp = talloc_asprintf(talloc_tos(), "%s/.streams", handle->conn->connectpath);
 122
 123         if (tmp == NULL) {
 124                 errno = ENOMEM;
 125                 goto fail;
 126         }
 127
 128         rootdir = lp_parm_const_string(
 129                 SNUM(handle->conn), "streams_depot", "directory",
 130                 tmp);
 131         TALLOC_FREE(tmp);
 132
 133         if (base_sbuf == NULL) {
 134                 if (SMB_VFS_NEXT_STAT(handle, base_path, &sbuf) == -1) {
 135                         /*
 136                          * base file is not there
 137                          */
 138                         goto fail;
 139                 }
 140                 base_sbuf = &sbuf;
 141         }
 142
 143         id = SMB_VFS_FILE_ID_CREATE(handle->conn, base_sbuf->st_dev,
 144                                     base_sbuf->st_ino);
 145
 146         push_file_id_16((char *)id_buf, &id);
 147
 148         hash = hash_fn(data_blob_const(id_buf, sizeof(id_buf)));
 149
 150         first = hash & 0xff;
 151         second = (hash >> 8) & 0xff;
 152
 153         id_hex = hex_encode(talloc_tos(), id_buf, sizeof(id_buf));
 154
 155         if (id_hex == NULL) {
 156                 errno = ENOMEM;
 157                 goto fail;
 158         }
 159
 160         result = talloc_asprintf(talloc_tos(), "%s/%2.2X/%2.2X/%s", rootdir,
 161                                  first, second, id_hex);
 162
 163         TALLOC_FREE(id_hex);
 164
 165         if (result == NULL) {
 166                 errno = ENOMEM;
 167                 return NULL;
 168         }
 169
 170         if (SMB_VFS_NEXT_STAT(handle, result, &sbuf) == 0) {
 171                 char *newname;
 172
 173                 if (!S_ISDIR(sbuf.st_mode)) {
 174                         errno = EINVAL;
 175                         goto fail;
 176                 }
 177
 178                 if (file_is_valid(handle, base_path)) {
 179                         return result;
 180                 }
 181
 182                 /*
 183                  * Someone has recreated a file under an existing inode
 184                  * without deleting the streams directory. For now, just move
 185                  * it away.
 186                  */
 187
 188         again:
 189                 newname = talloc_asprintf(talloc_tos(), "lost-%lu", random());
 190                 if (newname == NULL) {
 191                         errno = ENOMEM;
 192                         goto fail;
 193                 }
 194
 195                 if (SMB_VFS_NEXT_RENAME(handle, result, newname) == -1) {
 196                         if ((errno == EEXIST) || (errno == ENOTEMPTY)) {
 197                                 TALLOC_FREE(newname);
 198                                 goto again;
 199                         }
 200                         goto fail;
 201                 }
 202
 203                 TALLOC_FREE(newname);
 204         }
 205
 206         if (!create_it) {
 207                 errno = ENOENT;
 208                 goto fail;
 209         }
 210
 211         if ((SMB_VFS_NEXT_MKDIR(handle, rootdir, 0755) != 0)
 212             && (errno != EEXIST)) {
 213                 goto fail;
 214         }
 215
 216         tmp = talloc_asprintf(result, "%s/%2.2X", rootdir, first);
 217         if (tmp == NULL) {
 218                 errno = ENOMEM;
 219                 goto fail;
 220         }
 221
 222         if ((SMB_VFS_NEXT_MKDIR(handle, tmp, 0755) != 0)
 223             && (errno != EEXIST)) {
 224                 goto fail;
 225         }
 226
 227         TALLOC_FREE(tmp);
 228
 229         tmp = talloc_asprintf(result, "%s/%2.2X/%2.2X", rootdir, first,
 230                               second);
 231         if (tmp == NULL) {
 232                 errno = ENOMEM;
 233                 goto fail;
 234         }
 235
 236         if ((SMB_VFS_NEXT_MKDIR(handle, tmp, 0755) != 0)
 237             && (errno != EEXIST)) {
 238                 goto fail;
 239         }
 240
 241         TALLOC_FREE(tmp);
 242
 243         if ((SMB_VFS_NEXT_MKDIR(handle, result, 0755) != 0)
 244             && (errno != EEXIST)) {
 245                 goto fail;
 246         }
 247
 248         if (!mark_file_valid(handle, base_path)) {
 249                 goto fail;
 250         }
 251
 252         return result;
 253
 254  fail:
 255         TALLOC_FREE(result);
 256         return NULL;
 257 }
 258
 259 static char *stream_name(vfs_handle_struct *handle, const char *fname,
 260                          bool create_dir)
 261 {
 262         char *base = NULL;
 263         char *sname = NULL;
 264         char *id_hex = NULL;
 265         char *dirname, *stream_fname;
 266
 267         if (!NT_STATUS_IS_OK(split_ntfs_stream_name(talloc_tos(), fname,
 268                                                     &base, &sname))) {
 269                 DEBUG(10, ("split_ntfs_stream_name failed\n"));
 270                 errno = ENOMEM;
 271                 goto fail;
 272         }
 273
 274         dirname = stream_dir(handle, base, NULL, create_dir);
 275
 276         if (dirname == NULL) {
 277                 goto fail;
 278         }
 279
 280         stream_fname = talloc_asprintf(talloc_tos(), "%s/:%s", dirname, sname);
 281
 282         if (stream_fname == NULL) {
 283                 errno = ENOMEM;
 284                 goto fail;
 285         }
 286
 287         DEBUG(10, ("stream filename = %s\n", stream_fname));
 288
 289         TALLOC_FREE(base);
 290         TALLOC_FREE(sname);
 291         TALLOC_FREE(id_hex);
 292
 293         return stream_fname;
 294
 295  fail:
 296         DEBUG(5, ("stream_name failed: %s\n", strerror(errno)));
 297         TALLOC_FREE(base);
 298         TALLOC_FREE(sname);
 299         TALLOC_FREE(id_hex);
 300         return NULL;
 301 }
 302
 303 static NTSTATUS walk_streams(vfs_handle_struct *handle,
 304                              const char *fname,
 305                              const SMB_STRUCT_STAT *sbuf,
 306                              char **pdirname,
 307                              bool (*fn)(const char *dirname,
 308                                         const char *dirent,
 309                                         void *private_data),
 310                              void *private_data)
 311 {
 312         char *dirname;
 313         SMB_STRUCT_DIR *dirhandle = NULL;
 314         char *dirent;
 315
 316         dirname = stream_dir(handle, fname, sbuf, false);
 317
 318         if (dirname == NULL) {
 319                 if (errno == ENOENT) {
 320                         /*
 321                          * no stream around
 322                          */
 323                         return NT_STATUS_OK;
 324                 }
 325                 return map_nt_error_from_unix(errno);
 326         }
 327
 328         DEBUG(10, ("walk_streams: dirname=%s\n", dirname));
 329
 330         dirhandle = SMB_VFS_NEXT_OPENDIR(handle, dirname, NULL, 0);
 331
 332         if (dirhandle == NULL) {
 333                 TALLOC_FREE(dirname);
 334                 return map_nt_error_from_unix(errno);
 335         }
 336
 337         while ((dirent = vfs_readdirname(handle->conn, dirhandle)) != NULL) {
 338
 339                 if (ISDOT(dirent) || ISDOTDOT(dirent)) {
 340                         continue;
 341                 }
 342
 343                 DEBUG(10, ("walk_streams: dirent=%s\n", dirent));
 344
 345                 if (!fn(dirname, dirent, private_data)) {
 346                         break;
 347                 }
 348         }
 349
 350         SMB_VFS_NEXT_CLOSEDIR(handle, dirhandle);
 351
 352         if (pdirname != NULL) {
 353                 *pdirname = dirname;
 354         }
 355         else {
 356                 TALLOC_FREE(dirname);
 357         }
 358
 359         return NT_STATUS_OK;
 360 }
 361
 362 static int streams_depot_stat(vfs_handle_struct *handle, const char *fname,
 363                               SMB_STRUCT_STAT *sbuf)
 364 {
 365         char *stream_fname;
 366         int ret = -1;
 367
 368         DEBUG(10, ("streams_depot_stat called for [%s]\n", fname));
 369
 370         if (!is_ntfs_stream_name(fname)) {
 371                 return SMB_VFS_NEXT_STAT(handle, fname, sbuf);
 372         }
 373
 374         stream_fname = stream_name(handle, fname, false);
 375         if (stream_fname == NULL) {
 376                 goto done;
 377         }
 378
 379         ret = SMB_VFS_NEXT_STAT(handle, stream_fname, sbuf);
 380
 381  done:
 382         TALLOC_FREE(stream_fname);
 383         return ret;
 384 }
 385
 386 static int streams_depot_lstat(vfs_handle_struct *handle, const char *fname,
 387                                SMB_STRUCT_STAT *sbuf)
 388 {
 389         char *stream_fname;
 390         int ret = -1;
 391
 392         if (!is_ntfs_stream_name(fname)) {
 393                 return SMB_VFS_NEXT_LSTAT(handle, fname, sbuf);
 394         }
 395
 396         stream_fname = stream_name(handle, fname, false);
 397         if (stream_fname == NULL) {
 398                 goto done;
 399         }
 400
 401         ret = SMB_VFS_NEXT_LSTAT(handle, stream_fname, sbuf);
 402
 403  done:
 404         TALLOC_FREE(stream_fname);
 405         return ret;
 406 }
 407
 408 static int streams_depot_open(vfs_handle_struct *handle,  const char *fname,
 409                               files_struct *fsp, int flags, mode_t mode)
 410 {
 411         TALLOC_CTX *frame;
 412         char *base = NULL;
 413         SMB_STRUCT_STAT base_sbuf;
 414         char *stream_fname;
 415         int ret = -1;
 416
 417         if (!is_ntfs_stream_name(fname)) {
 418                 return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
 419         }
 420
 421         frame = talloc_stackframe();
 422
 423         if (!NT_STATUS_IS_OK(split_ntfs_stream_name(talloc_tos(), fname,
 424                                                     &base, NULL))) {
 425                 errno = ENOMEM;
 426                 goto done;
 427         }
 428
 429         ret = SMB_VFS_NEXT_STAT(handle, base, &base_sbuf);
 430
 431         if (ret == -1) {
 432                 goto done;
 433         }
 434
 435         TALLOC_FREE(base);
 436
 437         stream_fname = stream_name(handle, fname, true);
 438         if (stream_fname == NULL) {
 439                 goto done;
 440         }
 441
 442         ret = SMB_VFS_NEXT_OPEN(handle, stream_fname, fsp, flags, mode);
 443
 444  done:
 445         TALLOC_FREE(frame);
 446         return ret;
 447 }
 448
 449 static int streams_depot_unlink(vfs_handle_struct *handle,  const char *fname)
 450 {
 451         int ret = -1;
 452         SMB_STRUCT_STAT sbuf;
 453
 454         DEBUG(10, ("streams_depot_unlink called for %s\n", fname));
 455
 456         if (is_ntfs_stream_name(fname)) {
 457                 char *stream_fname;
 458
 459                 stream_fname = stream_name(handle, fname, false);
 460                 if (stream_fname == NULL) {
 461                         return -1;
 462                 }
 463
 464                 ret = SMB_VFS_NEXT_UNLINK(handle, stream_fname);
 465
 466                 TALLOC_FREE(stream_fname);
 467                 return ret;
 468         }
 469
 470         /*
 471          * We potentially need to delete the per-inode streams directory
 472          */
 473
 474         if (SMB_VFS_NEXT_STAT(handle, fname, &sbuf) == -1) {
 475                 return -1;
 476         }
 477
 478         if (sbuf.st_nlink == 1) {
 479                 char *dirname = stream_dir(handle, fname, &sbuf, false);
 480
 481                 if (dirname != NULL) {
 482                         SMB_VFS_NEXT_RMDIR(handle, dirname);
 483                 }
 484                 TALLOC_FREE(dirname);
 485         }
 486
 487         return SMB_VFS_NEXT_UNLINK(handle, fname);
 488 }
 489
 490 static bool add_one_stream(TALLOC_CTX *mem_ctx, unsigned int *num_streams,
 491                            struct stream_struct **streams,
 492                            const char *name, SMB_OFF_T size,
 493                            SMB_OFF_T alloc_size)
 494 {
 495         struct stream_struct *tmp;
 496
 497         tmp = TALLOC_REALLOC_ARRAY(mem_ctx, *streams, struct stream_struct,
 498                                    (*num_streams)+1);
 499         if (tmp == NULL) {
 500                 return false;
 501         }
 502
 503         tmp[*num_streams].name = talloc_strdup(tmp, name);
 504         if (tmp[*num_streams].name == NULL) {
 505                 return false;
 506         }
 507
 508         tmp[*num_streams].size = size;
 509         tmp[*num_streams].alloc_size = alloc_size;
 510
 511         *streams = tmp;
 512         *num_streams += 1;
 513         return true;
 514 }
 515
 516 struct streaminfo_state {
 517         TALLOC_CTX *mem_ctx;
 518         vfs_handle_struct *handle;
 519         unsigned int num_streams;
 520         struct stream_struct *streams;
 521         NTSTATUS status;
 522 };
 523
 524 static bool collect_one_stream(const char *dirname,
 525                                const char *dirent,
 526                                void *private_data)
 527 {
 528         struct streaminfo_state *state =
 529                 (struct streaminfo_state *)private_data;
 530         char *full_sname;
 531         SMB_STRUCT_STAT sbuf;
 532
 533         if (asprintf(&full_sname, "%s/%s", dirname, dirent) == -1) {
 534                 state->status = NT_STATUS_NO_MEMORY;
 535                 return false;
 536         }
 537         if (SMB_VFS_NEXT_STAT(state->handle, full_sname, &sbuf) == -1) {
 538                 DEBUG(10, ("Could not stat %s: %s\n", full_sname,
 539                            strerror(errno)));
 540                 SAFE_FREE(full_sname);
 541                 return true;
 542         }
 543
 544         SAFE_FREE(full_sname);
 545
 546         if (!add_one_stream(state->mem_ctx,
 547                             &state->num_streams, &state->streams,
 548                             dirent, sbuf.st_size,
 549                             get_allocation_size(
 550                                     state->handle->conn, NULL, &sbuf))) {
 551                 state->status = NT_STATUS_NO_MEMORY;
 552                 return false;
 553         }
 554
 555         return true;
 556 }
 557
 558 static NTSTATUS streams_depot_streaminfo(vfs_handle_struct *handle,
 559                                          struct files_struct *fsp,
 560                                          const char *fname,
 561                                          TALLOC_CTX *mem_ctx,
 562                                          unsigned int *pnum_streams,
 563                                          struct stream_struct **pstreams)
 564 {
 565         SMB_STRUCT_STAT sbuf;
 566         int ret;
 567         NTSTATUS status;
 568         struct streaminfo_state state;
 569
 570         if ((fsp != NULL) && (fsp->fh->fd != -1)) {
 571                 if (is_ntfs_stream_name(fsp->fsp_name)) {
 572                         return NT_STATUS_INVALID_PARAMETER;
 573                 }
 574                 ret = SMB_VFS_NEXT_FSTAT(handle, fsp, &sbuf);
 575         }
 576         else {
 577                 if (is_ntfs_stream_name(fname)) {
 578                         return NT_STATUS_INVALID_PARAMETER;
 579                 }
 580                 ret = SMB_VFS_NEXT_STAT(handle, fname, &sbuf);
 581         }
 582
 583         if (ret == -1) {
 584                 return map_nt_error_from_unix(errno);
 585         }
 586
 587         state.streams = NULL;
 588         state.num_streams = 0;
 589
 590         if (!S_ISDIR(sbuf.st_mode)) {
 591                 if (!add_one_stream(mem_ctx,
 592                                     &state.num_streams, &state.streams,
 593                                     "::$DATA", sbuf.st_size,
 594                                     get_allocation_size(handle->conn, fsp,
 595                                                         &sbuf))) {
 596                         return NT_STATUS_NO_MEMORY;
 597                 }
 598         }
 599
 600         state.mem_ctx = mem_ctx;
 601         state.handle = handle;
 602         state.status = NT_STATUS_OK;
 603
 604         status = walk_streams(handle, fname, &sbuf, NULL, collect_one_stream,
 605                               &state);
 606
 607         if (!NT_STATUS_IS_OK(status)) {
 608                 TALLOC_FREE(state.streams);
 609                 return status;
 610         }
 611
 612         if (!NT_STATUS_IS_OK(state.status)) {
 613                 TALLOC_FREE(state.streams);
 614                 return state.status;
 615         }
 616
 617         *pnum_streams = state.num_streams;
 618         *pstreams = state.streams;
 619         return NT_STATUS_OK;
 620 }
 621
 622 static uint32_t streams_depot_fs_capabilities(struct vfs_handle_struct *handle)
 623 {
 624         return SMB_VFS_NEXT_FS_CAPABILITIES(handle) | FILE_NAMED_STREAMS;
 625 }
 626
 627 /* VFS operations structure */
 628
 629 static vfs_op_tuple streams_depot_ops[] = {
 630         {SMB_VFS_OP(streams_depot_fs_capabilities), SMB_VFS_OP_FS_CAPABILITIES,
 631          SMB_VFS_LAYER_TRANSPARENT},
 632         {SMB_VFS_OP(streams_depot_open), SMB_VFS_OP_OPEN,
 633          SMB_VFS_LAYER_TRANSPARENT},
 634         {SMB_VFS_OP(streams_depot_stat), SMB_VFS_OP_STAT,
 635          SMB_VFS_LAYER_TRANSPARENT},
 636         {SMB_VFS_OP(streams_depot_lstat), SMB_VFS_OP_LSTAT,
 637          SMB_VFS_LAYER_TRANSPARENT},
 638         {SMB_VFS_OP(streams_depot_unlink), SMB_VFS_OP_UNLINK,
 639          SMB_VFS_LAYER_TRANSPARENT},
 640         {SMB_VFS_OP(streams_depot_streaminfo), SMB_VFS_OP_STREAMINFO,
 641          SMB_VFS_LAYER_OPAQUE},
 642         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 643 };
 644
 645 NTSTATUS vfs_streams_depot_init(void);
 646 NTSTATUS vfs_streams_depot_init(void)
 647 {
 648         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "streams_depot",
 649                                 streams_depot_ops);
 650 }