source3/lib/tdb_validate.c

   1 /*
   2  * Unix SMB/CIFS implementation.
   3  *
   4  * A general tdb content validation mechanism
   5  *
   6  * Copyright (C) Michael Adam      2007
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 3 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "tdb_validate.h"
  23 #include "includes.h"
  24
  25 /*
  26  * internal validation function, executed by the child.
  27  */
  28 static int tdb_validate_child(struct tdb_context *tdb,
  29                               tdb_validate_data_func validate_fn)
  30 {
  31         int ret = 1;
  32         int num_entries = 0;
  33         struct tdb_validation_status v_status;
  34
  35         v_status.tdb_error = False;
  36         v_status.bad_freelist = False;
  37         v_status.bad_entry = False;
  38         v_status.unknown_key = False;
  39         v_status.success = True;
  40
  41         if (!tdb) {
  42                 v_status.tdb_error = True;
  43                 v_status.success = False;
  44                 goto out;
  45         }
  46
  47         /*
  48          * we can simplify this by passing a check function,
  49          * but I don't want to change all the callers...
  50          */
  51         ret = tdb_check(tdb, NULL, NULL);
  52         if (ret == -1) {
  53                 v_status.tdb_error = True;
  54                 v_status.success = False;
  55                 goto out;
  56         }
  57
  58         /* Check if the tdb's freelist is good. */
  59         if (tdb_validate_freelist(tdb, &num_entries) == -1) {
  60                 v_status.bad_freelist = True;
  61                 v_status.success = False;
  62                 goto out;
  63         }
  64
  65         DEBUG(10,("tdb_validate_child: tdb %s freelist has %d entries\n",
  66                   tdb_name(tdb), num_entries));
  67
  68         /* Now traverse the tdb to validate it. */
  69         num_entries = tdb_traverse(tdb, validate_fn, (void *)&v_status);
  70         if (!v_status.success) {
  71                 goto out;
  72         } else if (num_entries == -1) {
  73                 v_status.tdb_error = True;
  74                 v_status.success = False;
  75                 goto out;
  76         }
  77
  78         DEBUG(10,("tdb_validate_child: tdb %s is good with %d entries\n",
  79                   tdb_name(tdb), num_entries));
  80         ret = 0; /* Cache is good. */
  81
  82 out:
  83         DEBUG(10,   ("tdb_validate_child: summary of validation status:\n"));
  84         DEBUGADD(10,(" * tdb error: %s\n", v_status.tdb_error ? "yes" : "no"));
  85         DEBUGADD(10,(" * bad freelist: %s\n",v_status.bad_freelist?"yes":"no"));
  86         DEBUGADD(10,(" * bad entry: %s\n", v_status.bad_entry ? "yes" : "no"));
  87         DEBUGADD(10,(" * unknown key: %s\n", v_status.unknown_key?"yes":"no"));
  88         DEBUGADD(10,(" => overall success: %s\n", v_status.success?"yes":"no"));
  89
  90         return ret;
  91 }
  92
  93 /*
  94  * tdb validation function.
  95  * returns 0 if tdb is ok, != 0 if it isn't.
  96  * this function expects an opened tdb.
  97  */
  98 int tdb_validate(struct tdb_context *tdb, tdb_validate_data_func validate_fn)
  99 {
 100         pid_t child_pid = -1;
 101         int child_status = 0;
 102         int wait_pid = 0;
 103         int ret = 1;
 104
 105         if (tdb == NULL) {
 106                 DEBUG(1, ("Error: tdb_validate called with tdb == NULL\n"));
 107                 return ret;
 108         }
 109
 110         DEBUG(5, ("tdb_validate called for tdb '%s'\n", tdb_name(tdb)));
 111
 112         /* fork and let the child do the validation.
 113          * benefit: no need to twist signal handlers and panic functions.
 114          * just let the child panic. we catch the signal. */
 115
 116         DEBUG(10, ("tdb_validate: forking to let child do validation.\n"));
 117         child_pid = sys_fork();
 118         if (child_pid == 0) {
 119                 /* child code */
 120                 DEBUG(10, ("tdb_validate (validation child): created\n"));
 121                 DEBUG(10, ("tdb_validate (validation child): "
 122                            "calling tdb_validate_child\n"));
 123                 exit(tdb_validate_child(tdb, validate_fn));
 124         }
 125         else if (child_pid < 0) {
 126                 DEBUG(1, ("tdb_validate: fork for validation failed.\n"));
 127                 goto done;
 128         }
 129
 130         /* parent */
 131
 132         DEBUG(10, ("tdb_validate: fork succeeded, child PID = %u\n",
 133                 (unsigned int)child_pid));
 134
 135         DEBUG(10, ("tdb_validate: waiting for child to finish...\n"));
 136         while  ((wait_pid = sys_waitpid(child_pid, &child_status, 0)) < 0) {
 137                 if (errno == EINTR) {
 138                         DEBUG(10, ("tdb_validate: got signal during waitpid, "
 139                                    "retrying\n"));
 140                         errno = 0;
 141                         continue;
 142                 }
 143                 DEBUG(1, ("tdb_validate: waitpid failed with error '%s'.\n",
 144                           strerror(errno)));
 145                 goto done;
 146         }
 147         if (wait_pid != child_pid) {
 148                 DEBUG(1, ("tdb_validate: waitpid returned pid %d, "
 149                           "but %u was expected\n", wait_pid, (unsigned int)child_pid));
 150                 goto done;
 151         }
 152
 153         DEBUG(10, ("tdb_validate: validating child returned.\n"));
 154         if (WIFEXITED(child_status)) {
 155                 DEBUG(10, ("tdb_validate: child exited, code %d.\n",
 156                            WEXITSTATUS(child_status)));
 157                 ret = WEXITSTATUS(child_status);
 158         }
 159         if (WIFSIGNALED(child_status)) {
 160                 DEBUG(10, ("tdb_validate: child terminated by signal %d\n",
 161                            WTERMSIG(child_status)));
 162 #ifdef WCOREDUMP
 163                 if (WCOREDUMP(child_status)) {
 164                         DEBUGADD(10, ("core dumped\n"));
 165                 }
 166 #endif
 167                 ret = WTERMSIG(child_status);
 168         }
 169         if (WIFSTOPPED(child_status)) {
 170                 DEBUG(10, ("tdb_validate: child was stopped by signal %d\n",
 171                            WSTOPSIG(child_status)));
 172                 ret = WSTOPSIG(child_status);
 173         }
 174
 175 done:
 176         DEBUG(5, ("tdb_validate returning code '%d' for tdb '%s'\n", ret,
 177                   tdb_name(tdb)));
 178
 179         return ret;
 180 }
 181
 182 /*
 183  * tdb validation function.
 184  * returns 0 if tdb is ok, != 0 if it isn't.
 185  * this is a wrapper around the actual validation function that opens and closes
 186  * the tdb.
 187  */
 188 int tdb_validate_open(const char *tdb_path, tdb_validate_data_func validate_fn)
 189 {
 190         TDB_CONTEXT *tdb = NULL;
 191         int ret = 1;
 192
 193         DEBUG(5, ("tdb_validate_open called for tdb '%s'\n", tdb_path));
 194
 195         tdb = tdb_open_log(tdb_path, 0, TDB_DEFAULT, O_RDWR, 0);
 196         if (!tdb) {
 197                 DEBUG(1, ("Error opening tdb %s\n", tdb_path));
 198                 return ret;
 199         }
 200
 201         ret = tdb_validate(tdb, validate_fn);
 202         tdb_close(tdb);
 203         return ret;
 204 }
 205
 206 /*
 207  * tdb backup function and helpers for tdb_validate wrapper with backup
 208  * handling.
 209  */
 210
 211 /* this structure eliminates the need for a global overall status for
 212  * the traverse-copy */
 213 struct tdb_copy_data {
 214         struct tdb_context *dst;
 215         bool success;
 216 };
 217
 218 static int traverse_copy_fn(struct tdb_context *tdb, TDB_DATA key,
 219                             TDB_DATA dbuf, void *private_data)
 220 {
 221         struct tdb_copy_data *data = (struct tdb_copy_data *)private_data;
 222
 223         if (tdb_store(data->dst, key, dbuf, TDB_INSERT) != 0) {
 224                 DEBUG(4, ("Failed to insert into %s: %s\n", tdb_name(data->dst),
 225                           strerror(errno)));
 226                 data->success = False;
 227                 return 1;
 228         }
 229         return 0;
 230 }
 231
 232 static int tdb_copy(struct tdb_context *src, struct tdb_context *dst)
 233 {
 234         struct tdb_copy_data data;
 235         int count;
 236
 237         data.dst = dst;
 238         data.success = True;
 239
 240         count = tdb_traverse(src, traverse_copy_fn, (void *)(&data));
 241         if ((count < 0) || (data.success == False)) {
 242                 return -1;
 243         }
 244         return count;
 245 }
 246
 247 static int tdb_verify_basic(struct tdb_context *tdb)
 248 {
 249         return tdb_traverse(tdb, NULL, NULL);
 250 }
 251
 252 /* this backup function is essentially taken from lib/tdb/tools/tdbbackup.tdb
 253  */
 254 static int tdb_backup(TALLOC_CTX *ctx, const char *src_path,
 255                       const char *dst_path, int hash_size)
 256 {
 257         struct tdb_context *src_tdb = NULL;
 258         struct tdb_context *dst_tdb = NULL;
 259         char *tmp_path = NULL;
 260         struct stat st;
 261         int count1, count2;
 262         int saved_errno = 0;
 263         int ret = -1;
 264
 265         if (stat(src_path, &st) != 0) {
 266                 DEBUG(3, ("Could not stat '%s': %s\n", src_path,
 267                           strerror(errno)));
 268                 goto done;
 269         }
 270
 271         /* open old tdb RDWR - so we can lock it */
 272         src_tdb = tdb_open_log(src_path, 0, TDB_DEFAULT, O_RDWR, 0);
 273         if (src_tdb == NULL) {
 274                 DEBUG(3, ("Failed to open tdb '%s'\n", src_path));
 275                 goto done;
 276         }
 277
 278         if (tdb_lockall(src_tdb) != 0) {
 279                 DEBUG(3, ("Failed to lock tdb '%s'\n", src_path));
 280                 goto done;
 281         }
 282
 283         tmp_path = talloc_asprintf(ctx, "%s%s", dst_path, ".tmp");
 284         if (!tmp_path) {
 285                 DEBUG(3, ("talloc fail\n"));
 286                 goto done;
 287         }
 288
 289         unlink(tmp_path);
 290         dst_tdb = tdb_open_log(tmp_path,
 291                                hash_size ? hash_size : tdb_hash_size(src_tdb),
 292                                TDB_DEFAULT, O_RDWR | O_CREAT | O_EXCL,
 293                                st.st_mode & 0777);
 294         if (dst_tdb == NULL) {
 295                 DEBUG(3, ("Error creating tdb '%s': %s\n", tmp_path,
 296                           strerror(errno)));
 297                 saved_errno = errno;
 298                 unlink(tmp_path);
 299                 goto done;
 300         }
 301
 302         count1 = tdb_copy(src_tdb, dst_tdb);
 303         if (count1 < 0) {
 304                 DEBUG(3, ("Failed to copy tdb '%s': %s\n", src_path,
 305                           strerror(errno)));
 306                 tdb_close(dst_tdb);
 307                 goto done;
 308         }
 309
 310         /* reopen ro and do basic verification */
 311         tdb_close(dst_tdb);
 312         dst_tdb = tdb_open_log(tmp_path, 0, TDB_DEFAULT, O_RDONLY, 0);
 313         if (!dst_tdb) {
 314                 DEBUG(3, ("Failed to reopen tdb '%s': %s\n", tmp_path,
 315                           strerror(errno)));
 316                 goto done;
 317         }
 318         count2 = tdb_verify_basic(dst_tdb);
 319         if (count2 != count1) {
 320                 DEBUG(3, ("Failed to verify result of copying tdb '%s'.\n",
 321                           src_path));
 322                 tdb_close(dst_tdb);
 323                 goto done;
 324         }
 325
 326         DEBUG(10, ("tdb_backup: successfully copied %d entries\n", count1));
 327
 328         /* make sure the new tdb has reached stable storage
 329          * then rename it to its destination */
 330         fsync(tdb_fd(dst_tdb));
 331         tdb_close(dst_tdb);
 332         unlink(dst_path);
 333         if (rename(tmp_path, dst_path) != 0) {
 334                 DEBUG(3, ("Failed to rename '%s' to '%s': %s\n",
 335                           tmp_path, dst_path, strerror(errno)));
 336                 goto done;
 337         }
 338
 339         /* success */
 340         ret = 0;
 341
 342 done:
 343         if (src_tdb != NULL) {
 344                 tdb_close(src_tdb);
 345         }
 346         if (tmp_path != NULL) {
 347                 unlink(tmp_path);
 348                 TALLOC_FREE(tmp_path);
 349         }
 350         if (saved_errno != 0) {
 351                 errno = saved_errno;
 352         }
 353         return ret;
 354 }
 355
 356 static int rename_file_with_suffix(TALLOC_CTX *ctx, const char *path,
 357                                    const char *suffix)
 358 {
 359         int ret = -1;
 360         char *dst_path;
 361
 362         dst_path = talloc_asprintf(ctx, "%s%s", path, suffix);
 363         if (dst_path == NULL) {
 364                 DEBUG(3, ("error out of memory\n"));
 365                 return ret;
 366         }
 367
 368         ret = (rename(path, dst_path) != 0);
 369
 370         if (ret == 0) {
 371                 DEBUG(5, ("moved '%s' to '%s'\n", path, dst_path));
 372         } else if (errno == ENOENT) {
 373                 DEBUG(3, ("file '%s' does not exist - so not moved\n", path));
 374                 ret = 0;
 375         } else {
 376                 DEBUG(3, ("error renaming %s to %s: %s\n", path, dst_path,
 377                           strerror(errno)));
 378         }
 379
 380         TALLOC_FREE(dst_path);
 381         return ret;
 382 }
 383
 384 /*
 385  * do a backup of a tdb, moving the destination out of the way first
 386  */
 387 static int tdb_backup_with_rotate(TALLOC_CTX *ctx, const char *src_path,
 388                                   const char *dst_path, int hash_size,
 389                                   const char *rotate_suffix,
 390                                   bool retry_norotate_if_nospc,
 391                                   bool rename_as_last_resort_if_nospc)
 392 {
 393         int ret;
 394
 395         rename_file_with_suffix(ctx, dst_path, rotate_suffix);
 396
 397         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 398
 399         if (ret != 0) {
 400                 DEBUG(10, ("backup of %s failed: %s\n", src_path, strerror(errno)));
 401         }
 402         if ((ret != 0) && (errno == ENOSPC) && retry_norotate_if_nospc)
 403         {
 404                 char *rotate_path = talloc_asprintf(ctx, "%s%s", dst_path,
 405                                                     rotate_suffix);
 406                 if (rotate_path == NULL) {
 407                         DEBUG(10, ("talloc fail\n"));
 408                         return -1;
 409                 }
 410                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 411                            src_path));
 412                 DEBUGADD(10, ("trying to free some space by removing rotated "
 413                               "dst %s\n", rotate_path));
 414                 if (unlink(rotate_path) == -1) {
 415                         DEBUG(10, ("unlink of %s failed: %s\n", rotate_path,
 416                                    strerror(errno)));
 417                 } else {
 418                         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 419                 }
 420                 TALLOC_FREE(rotate_path);
 421         }
 422
 423         if ((ret != 0) && (errno == ENOSPC) && rename_as_last_resort_if_nospc)
 424         {
 425                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 426                            src_path));
 427                 DEBUGADD(10, ("using 'rename' as a last resort\n"));
 428                 ret = rename(src_path, dst_path);
 429         }
 430
 431         return ret;
 432 }
 433
 434 /*
 435  * validation function with backup handling:
 436  *
 437  *  - calls tdb_validate
 438  *  - if the tdb is ok, create a backup "name.bak", possibly moving
 439  *    existing backup to name.bak.old,
 440  *    return 0 (success) even if the backup fails
 441  *  - if the tdb is corrupt:
 442  *    - move the tdb to "name.corrupt"
 443  *    - check if there is valid backup.
 444  *      if so, restore the backup.
 445  *      if restore is successful, return 0 (success),
 446  *    - otherwise return -1 (failure)
 447  */
 448 int tdb_validate_and_backup(const char *tdb_path,
 449                             tdb_validate_data_func validate_fn)
 450 {
 451         int ret = -1;
 452         const char *backup_suffix = ".bak";
 453         const char *corrupt_suffix = ".corrupt";
 454         const char *rotate_suffix = ".old";
 455         char *tdb_path_backup;
 456         struct stat st;
 457         TALLOC_CTX *ctx = NULL;
 458
 459         ctx = talloc_new(NULL);
 460         if (ctx == NULL) {
 461                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 462                 goto done;
 463         }
 464
 465         tdb_path_backup = talloc_asprintf(ctx, "%s%s", tdb_path, backup_suffix);
 466         if (!tdb_path_backup) {
 467                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 468                 goto done;
 469         }
 470
 471         ret = tdb_validate_open(tdb_path, validate_fn);
 472
 473         if (ret == 0) {
 474                 DEBUG(1, ("tdb '%s' is valid\n", tdb_path));
 475                 ret = tdb_backup_with_rotate(ctx, tdb_path, tdb_path_backup, 0,
 476                                              rotate_suffix, True, False);
 477                 if (ret != 0) {
 478                         DEBUG(1, ("Error creating backup of tdb '%s'\n",
 479                                   tdb_path));
 480                         /* the actual validation was successful: */
 481                         ret = 0;
 482                 } else {
 483                         DEBUG(1, ("Created backup '%s' of tdb '%s'\n",
 484                                   tdb_path_backup, tdb_path));
 485                 }
 486         } else {
 487                 DEBUG(1, ("tdb '%s' is invalid\n", tdb_path));
 488
 489                 ret =stat(tdb_path_backup, &st);
 490                 if (ret != 0) {
 491                         DEBUG(5, ("Could not stat '%s': %s\n", tdb_path_backup,
 492                                   strerror(errno)));
 493                         DEBUG(1, ("No backup found.\n"));
 494                 } else {
 495                         DEBUG(1, ("backup '%s' found.\n", tdb_path_backup));
 496                         ret = tdb_validate_open(tdb_path_backup, validate_fn);
 497                         if (ret != 0) {
 498                                 DEBUG(1, ("Backup '%s' is invalid.\n",
 499                                           tdb_path_backup));
 500                         }
 501                 }
 502
 503                 if (ret != 0) {
 504                         int renamed = rename_file_with_suffix(ctx, tdb_path,
 505                                                               corrupt_suffix);
 506                         if (renamed != 0) {
 507                                 DEBUG(1, ("Error moving tdb to '%s%s'\n",
 508                                           tdb_path, corrupt_suffix));
 509                         } else {
 510                                 DEBUG(1, ("Corrupt tdb stored as '%s%s'\n",
 511                                           tdb_path, corrupt_suffix));
 512                         }
 513                         goto done;
 514                 }
 515
 516                 DEBUG(1, ("valid backup '%s' found\n", tdb_path_backup));
 517                 ret = tdb_backup_with_rotate(ctx, tdb_path_backup, tdb_path, 0,
 518                                              corrupt_suffix, True, True);
 519                 if (ret != 0) {
 520                         DEBUG(1, ("Error restoring backup from '%s'\n",
 521                                   tdb_path_backup));
 522                 } else {
 523                         DEBUG(1, ("Restored tdb backup from '%s'\n",
 524                                   tdb_path_backup));
 525                 }
 526         }
 527
 528 done:
 529         TALLOC_FREE(ctx);
 530         return ret;
 531 }