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 "includes.h"
  23 #include "system/filesys.h"
  24 #include "util_tdb.h"
  25 #include "tdb_validate.h"
  26
  27 /*
  28  * internal validation function, executed by the child.
  29  */
  30 static int tdb_validate_child(struct tdb_context *tdb,
  31                               tdb_validate_data_func validate_fn)
  32 {
  33         int ret = 1;
  34         int num_entries = 0;
  35         struct tdb_validation_status v_status;
  36
  37         v_status.tdb_error = False;
  38         v_status.bad_freelist = False;
  39         v_status.bad_entry = False;
  40         v_status.unknown_key = False;
  41         v_status.success = True;
  42
  43         if (!tdb) {
  44                 v_status.tdb_error = True;
  45                 v_status.success = False;
  46                 goto out;
  47         }
  48
  49         /*
  50          * we can simplify this by passing a check function,
  51          * but I don't want to change all the callers...
  52          */
  53         ret = tdb_check(tdb, NULL, NULL);
  54         if (ret != 0) {
  55                 v_status.tdb_error = True;
  56                 v_status.success = False;
  57                 goto out;
  58         }
  59
  60         /* Check if the tdb's freelist is good. */
  61         if (tdb_validate_freelist(tdb, &num_entries) == -1) {
  62                 v_status.bad_freelist = True;
  63                 v_status.success = False;
  64                 goto out;
  65         }
  66
  67         DEBUG(10,("tdb_validate_child: tdb %s freelist has %d entries\n",
  68                   tdb_name(tdb), num_entries));
  69
  70         /* Now traverse the tdb to validate it. */
  71         num_entries = tdb_traverse(tdb, validate_fn, (void *)&v_status);
  72         if (!v_status.success) {
  73                 goto out;
  74         } else if (num_entries < 0) {
  75                 v_status.tdb_error = True;
  76                 v_status.success = False;
  77                 goto out;
  78         }
  79
  80         DEBUG(10,("tdb_validate_child: tdb %s is good with %d entries\n",
  81                   tdb_name(tdb), num_entries));
  82         ret = 0; /* Cache is good. */
  83
  84 out:
  85         DEBUG(10,   ("tdb_validate_child: summary of validation status:\n"));
  86         DEBUGADD(10,(" * tdb error: %s\n", v_status.tdb_error ? "yes" : "no"));
  87         DEBUGADD(10,(" * bad freelist: %s\n",v_status.bad_freelist?"yes":"no"));
  88         DEBUGADD(10,(" * bad entry: %s\n", v_status.bad_entry ? "yes" : "no"));
  89         DEBUGADD(10,(" * unknown key: %s\n", v_status.unknown_key?"yes":"no"));
  90         DEBUGADD(10,(" => overall success: %s\n", v_status.success?"yes":"no"));
  91
  92         return ret;
  93 }
  94
  95 /*
  96  * tdb validation function.
  97  * returns 0 if tdb is ok, != 0 if it isn't.
  98  * this function expects an opened tdb.
  99  */
 100 int tdb_validate(struct tdb_context *tdb, tdb_validate_data_func validate_fn)
 101 {
 102         pid_t child_pid = -1;
 103         int child_status = 0;
 104         int wait_pid = 0;
 105         int ret = 1;
 106
 107         if (tdb == NULL) {
 108                 DEBUG(1, ("Error: tdb_validate called with tdb == NULL\n"));
 109                 return ret;
 110         }
 111
 112         DEBUG(5, ("tdb_validate called for tdb '%s'\n", tdb_name(tdb)));
 113
 114         /* fork and let the child do the validation.
 115          * benefit: no need to twist signal handlers and panic functions.
 116          * just let the child panic. we catch the signal. */
 117
 118         DEBUG(10, ("tdb_validate: forking to let child do validation.\n"));
 119         child_pid = fork();
 120         if (child_pid == 0) {
 121                 /* child code */
 122                 DEBUG(10, ("tdb_validate (validation child): created\n"));
 123                 DEBUG(10, ("tdb_validate (validation child): "
 124                            "calling tdb_validate_child\n"));
 125                 exit(tdb_validate_child(tdb, validate_fn));
 126         }
 127         else if (child_pid < 0) {
 128                 DEBUG(1, ("tdb_validate: fork for validation failed.\n"));
 129                 goto done;
 130         }
 131
 132         /* parent */
 133
 134         DEBUG(10, ("tdb_validate: fork succeeded, child PID = %u\n",
 135                 (unsigned int)child_pid));
 136
 137         DEBUG(10, ("tdb_validate: waiting for child to finish...\n"));
 138         while  ((wait_pid = waitpid(child_pid, &child_status, 0)) < 0) {
 139                 if (errno == EINTR) {
 140                         DEBUG(10, ("tdb_validate: got signal during waitpid, "
 141                                    "retrying\n"));
 142                         errno = 0;
 143                         continue;
 144                 }
 145                 DEBUG(1, ("tdb_validate: waitpid failed with error '%s'.\n",
 146                           strerror(errno)));
 147                 goto done;
 148         }
 149         if (wait_pid != child_pid) {
 150                 DEBUG(1, ("tdb_validate: waitpid returned pid %d, "
 151                           "but %u was expected\n", wait_pid, (unsigned int)child_pid));
 152                 goto done;
 153         }
 154
 155         DEBUG(10, ("tdb_validate: validating child returned.\n"));
 156         if (WIFEXITED(child_status)) {
 157                 DEBUG(10, ("tdb_validate: child exited, code %d.\n",
 158                            WEXITSTATUS(child_status)));
 159                 ret = WEXITSTATUS(child_status);
 160         }
 161         if (WIFSIGNALED(child_status)) {
 162                 DEBUG(10, ("tdb_validate: child terminated by signal %d\n",
 163                            WTERMSIG(child_status)));
 164 #ifdef WCOREDUMP
 165                 if (WCOREDUMP(child_status)) {
 166                         DEBUGADD(10, ("core dumped\n"));
 167                 }
 168 #endif
 169                 ret = WTERMSIG(child_status);
 170         }
 171         if (WIFSTOPPED(child_status)) {
 172                 DEBUG(10, ("tdb_validate: child was stopped by signal %d\n",
 173                            WSTOPSIG(child_status)));
 174                 ret = WSTOPSIG(child_status);
 175         }
 176
 177 done:
 178         DEBUG(5, ("tdb_validate returning code '%d' for tdb '%s'\n", ret,
 179                   tdb_name(tdb)));
 180
 181         return ret;
 182 }
 183
 184 /*
 185  * tdb validation function.
 186  * returns 0 if tdb is ok, != 0 if it isn't.
 187  * this is a wrapper around the actual validation function that opens and closes
 188  * the tdb.
 189  */
 190 int tdb_validate_open(const char *tdb_path, tdb_validate_data_func validate_fn)
 191 {
 192         TDB_CONTEXT *tdb = NULL;
 193         int ret = 1;
 194
 195         DEBUG(5, ("tdb_validate_open called for tdb '%s'\n", tdb_path));
 196
 197         tdb = tdb_open_log(tdb_path, 0, TDB_DEFAULT, O_RDWR, 0);
 198         if (!tdb) {
 199                 DEBUG(1, ("Error opening tdb %s\n", tdb_path));
 200                 return ret;
 201         }
 202
 203         ret = tdb_validate(tdb, validate_fn);
 204         tdb_close(tdb);
 205         return ret;
 206 }
 207
 208 /*
 209  * tdb backup function and helpers for tdb_validate wrapper with backup
 210  * handling.
 211  */
 212
 213 /* this structure eliminates the need for a global overall status for
 214  * the traverse-copy */
 215 struct tdb_copy_data {
 216         struct tdb_context *dst;
 217         bool success;
 218 };
 219
 220 static int traverse_copy_fn(struct tdb_context *tdb, TDB_DATA key,
 221                             TDB_DATA dbuf, void *private_data)
 222 {
 223         struct tdb_copy_data *data = (struct tdb_copy_data *)private_data;
 224
 225         if (tdb_store(data->dst, key, dbuf, TDB_INSERT) != 0) {
 226                 DEBUG(4, ("Failed to insert into %s: %s\n", tdb_name(data->dst),
 227                           strerror(errno)));
 228                 data->success = False;
 229                 return 1;
 230         }
 231         return 0;
 232 }
 233
 234 static int tdb_copy(struct tdb_context *src, struct tdb_context *dst)
 235 {
 236         struct tdb_copy_data data;
 237         int count;
 238
 239         data.dst = dst;
 240         data.success = True;
 241
 242         count = tdb_traverse(src, traverse_copy_fn, (void *)(&data));
 243         if ((count < 0) || (data.success == False)) {
 244                 return -1;
 245         }
 246         return count;
 247 }
 248
 249 static int tdb_verify_basic(struct tdb_context *tdb)
 250 {
 251         return tdb_traverse(tdb, NULL, NULL);
 252 }
 253
 254 /* this backup function is essentially taken from lib/tdb/tools/tdbbackup.tdb
 255  */
 256 static int tdb_backup(TALLOC_CTX *ctx, const char *src_path,
 257                       const char *dst_path, int hash_size)
 258 {
 259         struct tdb_context *src_tdb = NULL;
 260         struct tdb_context *dst_tdb = NULL;
 261         char *tmp_path = NULL;
 262         struct stat st;
 263         int count1, count2;
 264         int saved_errno = 0;
 265         int ret = -1;
 266
 267         if (stat(src_path, &st) != 0) {
 268                 DEBUG(3, ("Could not stat '%s': %s\n", src_path,
 269                           strerror(errno)));
 270                 goto done;
 271         }
 272
 273         /* open old tdb RDWR - so we can lock it */
 274         src_tdb = tdb_open_log(src_path, 0, TDB_DEFAULT, O_RDWR, 0);
 275         if (src_tdb == NULL) {
 276                 DEBUG(3, ("Failed to open tdb '%s'\n", src_path));
 277                 goto done;
 278         }
 279
 280         if (tdb_lockall(src_tdb) != 0) {
 281                 DEBUG(3, ("Failed to lock tdb '%s'\n", src_path));
 282                 goto done;
 283         }
 284
 285         tmp_path = talloc_asprintf(ctx, "%s%s", dst_path, ".tmp");
 286         if (!tmp_path) {
 287                 DEBUG(3, ("talloc fail\n"));
 288                 goto done;
 289         }
 290
 291         unlink(tmp_path);
 292
 293         if (!hash_size) {
 294                 hash_size = tdb_hash_size(src_tdb);
 295         }
 296
 297         dst_tdb = tdb_open_log(tmp_path, hash_size,
 298                                TDB_DEFAULT, O_RDWR | O_CREAT | O_EXCL,
 299                                st.st_mode & 0777);
 300         if (dst_tdb == NULL) {
 301                 DEBUG(3, ("Error creating tdb '%s': %s\n", tmp_path,
 302                           strerror(errno)));
 303                 saved_errno = errno;
 304                 unlink(tmp_path);
 305                 goto done;
 306         }
 307
 308         count1 = tdb_copy(src_tdb, dst_tdb);
 309         if (count1 < 0) {
 310                 DEBUG(3, ("Failed to copy tdb '%s': %s\n", src_path,
 311                           strerror(errno)));
 312                 tdb_close(dst_tdb);
 313                 goto done;
 314         }
 315
 316         /* reopen ro and do basic verification */
 317         tdb_close(dst_tdb);
 318         dst_tdb = tdb_open_log(tmp_path, 0, TDB_DEFAULT, O_RDONLY, 0);
 319         if (!dst_tdb) {
 320                 DEBUG(3, ("Failed to reopen tdb '%s': %s\n", tmp_path,
 321                           strerror(errno)));
 322                 goto done;
 323         }
 324         count2 = tdb_verify_basic(dst_tdb);
 325         if (count2 != count1) {
 326                 DEBUG(3, ("Failed to verify result of copying tdb '%s'.\n",
 327                           src_path));
 328                 tdb_close(dst_tdb);
 329                 goto done;
 330         }
 331
 332         DEBUG(10, ("tdb_backup: successfully copied %d entries\n", count1));
 333
 334         /* make sure the new tdb has reached stable storage
 335          * then rename it to its destination */
 336         fsync(tdb_fd(dst_tdb));
 337         tdb_close(dst_tdb);
 338         unlink(dst_path);
 339         if (rename(tmp_path, dst_path) != 0) {
 340                 DEBUG(3, ("Failed to rename '%s' to '%s': %s\n",
 341                           tmp_path, dst_path, strerror(errno)));
 342                 goto done;
 343         }
 344
 345         /* success */
 346         ret = 0;
 347
 348 done:
 349         if (src_tdb != NULL) {
 350                 tdb_close(src_tdb);
 351         }
 352         if (tmp_path != NULL) {
 353                 unlink(tmp_path);
 354                 TALLOC_FREE(tmp_path);
 355         }
 356         if (saved_errno != 0) {
 357                 errno = saved_errno;
 358         }
 359         return ret;
 360 }
 361
 362 static int rename_file_with_suffix(TALLOC_CTX *ctx, const char *path,
 363                                    const char *suffix)
 364 {
 365         int ret = -1;
 366         char *dst_path;
 367
 368         dst_path = talloc_asprintf(ctx, "%s%s", path, suffix);
 369         if (dst_path == NULL) {
 370                 DEBUG(3, ("error out of memory\n"));
 371                 return ret;
 372         }
 373
 374         ret = (rename(path, dst_path) != 0);
 375
 376         if (ret == 0) {
 377                 DEBUG(5, ("moved '%s' to '%s'\n", path, dst_path));
 378         } else if (errno == ENOENT) {
 379                 DEBUG(3, ("file '%s' does not exist - so not moved\n", path));
 380                 ret = 0;
 381         } else {
 382                 DEBUG(3, ("error renaming %s to %s: %s\n", path, dst_path,
 383                           strerror(errno)));
 384         }
 385
 386         TALLOC_FREE(dst_path);
 387         return ret;
 388 }
 389
 390 /*
 391  * do a backup of a tdb, moving the destination out of the way first
 392  */
 393 static int tdb_backup_with_rotate(TALLOC_CTX *ctx, const char *src_path,
 394                                   const char *dst_path, int hash_size,
 395                                   const char *rotate_suffix,
 396                                   bool retry_norotate_if_nospc,
 397                                   bool rename_as_last_resort_if_nospc)
 398 {
 399         int ret;
 400
 401         rename_file_with_suffix(ctx, dst_path, rotate_suffix);
 402
 403         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 404
 405         if (ret != 0) {
 406                 DEBUG(10, ("backup of %s failed: %s\n", src_path, strerror(errno)));
 407         }
 408         if ((ret != 0) && (errno == ENOSPC) && retry_norotate_if_nospc)
 409         {
 410                 char *rotate_path = talloc_asprintf(ctx, "%s%s", dst_path,
 411                                                     rotate_suffix);
 412                 if (rotate_path == NULL) {
 413                         DEBUG(10, ("talloc fail\n"));
 414                         return -1;
 415                 }
 416                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 417                            src_path));
 418                 DEBUGADD(10, ("trying to free some space by removing rotated "
 419                               "dst %s\n", rotate_path));
 420                 if (unlink(rotate_path) == -1) {
 421                         DEBUG(10, ("unlink of %s failed: %s\n", rotate_path,
 422                                    strerror(errno)));
 423                 } else {
 424                         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 425                 }
 426                 TALLOC_FREE(rotate_path);
 427         }
 428
 429         if ((ret != 0) && (errno == ENOSPC) && rename_as_last_resort_if_nospc)
 430         {
 431                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 432                            src_path));
 433                 DEBUGADD(10, ("using 'rename' as a last resort\n"));
 434                 ret = rename(src_path, dst_path);
 435         }
 436
 437         return ret;
 438 }
 439
 440 /*
 441  * validation function with backup handling:
 442  *
 443  *  - calls tdb_validate
 444  *  - if the tdb is ok, create a backup "name.bak", possibly moving
 445  *    existing backup to name.bak.old,
 446  *    return 0 (success) even if the backup fails
 447  *  - if the tdb is corrupt:
 448  *    - move the tdb to "name.corrupt"
 449  *    - check if there is valid backup.
 450  *      if so, restore the backup.
 451  *      if restore is successful, return 0 (success),
 452  *    - otherwise return -1 (failure)
 453  */
 454 int tdb_validate_and_backup(const char *tdb_path,
 455                             tdb_validate_data_func validate_fn)
 456 {
 457         int ret = -1;
 458         const char *backup_suffix = ".bak";
 459         const char *corrupt_suffix = ".corrupt";
 460         const char *rotate_suffix = ".old";
 461         char *tdb_path_backup;
 462         struct stat st;
 463         TALLOC_CTX *ctx = NULL;
 464
 465         ctx = talloc_new(NULL);
 466         if (ctx == NULL) {
 467                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 468                 goto done;
 469         }
 470
 471         tdb_path_backup = talloc_asprintf(ctx, "%s%s", tdb_path, backup_suffix);
 472         if (!tdb_path_backup) {
 473                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 474                 goto done;
 475         }
 476
 477         ret = tdb_validate_open(tdb_path, validate_fn);
 478
 479         if (ret == 0) {
 480                 DEBUG(1, ("tdb '%s' is valid\n", tdb_path));
 481                 ret = tdb_backup_with_rotate(ctx, tdb_path, tdb_path_backup, 0,
 482                                              rotate_suffix, True, False);
 483                 if (ret != 0) {
 484                         DEBUG(1, ("Error creating backup of tdb '%s'\n",
 485                                   tdb_path));
 486                         /* the actual validation was successful: */
 487                         ret = 0;
 488                 } else {
 489                         DEBUG(1, ("Created backup '%s' of tdb '%s'\n",
 490                                   tdb_path_backup, tdb_path));
 491                 }
 492         } else {
 493                 DEBUG(1, ("tdb '%s' is invalid\n", tdb_path));
 494
 495                 ret =stat(tdb_path_backup, &st);
 496                 if (ret != 0) {
 497                         DEBUG(5, ("Could not stat '%s': %s\n", tdb_path_backup,
 498                                   strerror(errno)));
 499                         DEBUG(1, ("No backup found.\n"));
 500                 } else {
 501                         DEBUG(1, ("backup '%s' found.\n", tdb_path_backup));
 502                         ret = tdb_validate_open(tdb_path_backup, validate_fn);
 503                         if (ret != 0) {
 504                                 DEBUG(1, ("Backup '%s' is invalid.\n",
 505                                           tdb_path_backup));
 506                         }
 507                 }
 508
 509                 if (ret != 0) {
 510                         int renamed = rename_file_with_suffix(ctx, tdb_path,
 511                                                               corrupt_suffix);
 512                         if (renamed != 0) {
 513                                 DEBUG(1, ("Error moving tdb to '%s%s'\n",
 514                                           tdb_path, corrupt_suffix));
 515                         } else {
 516                                 DEBUG(1, ("Corrupt tdb stored as '%s%s'\n",
 517                                           tdb_path, corrupt_suffix));
 518                         }
 519                         goto done;
 520                 }
 521
 522                 DEBUG(1, ("valid backup '%s' found\n", tdb_path_backup));
 523                 ret = tdb_backup_with_rotate(ctx, tdb_path_backup, tdb_path, 0,
 524                                              corrupt_suffix, True, True);
 525                 if (ret != 0) {
 526                         DEBUG(1, ("Error restoring backup from '%s'\n",
 527                                   tdb_path_backup));
 528                 } else {
 529                         DEBUG(1, ("Restored tdb backup from '%s'\n",
 530                                   tdb_path_backup));
 531                 }
 532         }
 533
 534 done:
 535         TALLOC_FREE(ctx);
 536         return ret;
 537 }