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