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 check_rc;
  35         int num_entries = 0;
  36         struct tdb_validation_status v_status;
  37
  38         v_status.tdb_error = False;
  39         v_status.bad_freelist = False;
  40         v_status.bad_entry = False;
  41         v_status.unknown_key = False;
  42         v_status.success = True;
  43
  44         if (!tdb) {
  45                 v_status.tdb_error = True;
  46                 v_status.success = False;
  47                 goto out;
  48         }
  49
  50         /*
  51          * we can simplify this by passing a check function,
  52          * but I don't want to change all the callers...
  53          */
  54         check_rc = tdb_check(tdb, NULL, NULL);
  55         if (check_rc != 0) {
  56                 v_status.tdb_error = True;
  57                 v_status.success = False;
  58                 goto out;
  59         }
  60
  61         /* Check if the tdb's freelist is good. */
  62         if (tdb_validate_freelist(tdb, &num_entries) == -1) {
  63                 v_status.bad_freelist = True;
  64                 v_status.success = False;
  65                 goto out;
  66         }
  67
  68         DEBUG(10,("tdb_validate_child: tdb %s freelist has %d entries\n",
  69                   tdb_name(tdb), num_entries));
  70
  71         /* Now traverse the tdb to validate it. */
  72         num_entries = tdb_traverse(tdb, validate_fn, (void *)&v_status);
  73         if (!v_status.success) {
  74                 goto out;
  75         } else if (num_entries < 0) {
  76                 v_status.tdb_error = True;
  77                 v_status.success = False;
  78                 goto out;
  79         }
  80
  81         DEBUG(10,("tdb_validate_child: tdb %s is good with %d entries\n",
  82                   tdb_name(tdb), num_entries));
  83         ret = 0; /* Cache is good. */
  84
  85 out:
  86         DEBUG(10,   ("tdb_validate_child: summary of validation status:\n"));
  87         DEBUGADD(10,(" * tdb error: %s\n", v_status.tdb_error ? "yes" : "no"));
  88         DEBUGADD(10,(" * bad freelist: %s\n",v_status.bad_freelist?"yes":"no"));
  89         DEBUGADD(10,(" * bad entry: %s\n", v_status.bad_entry ? "yes" : "no"));
  90         DEBUGADD(10,(" * unknown key: %s\n", v_status.unknown_key?"yes":"no"));
  91         DEBUGADD(10,(" => overall success: %s\n", v_status.success?"yes":"no"));
  92
  93         return ret;
  94 }
  95
  96 /*
  97  * tdb validation function.
  98  * returns 0 if tdb is ok, != 0 if it isn't.
  99  * this function expects an opened tdb.
 100  */
 101 int tdb_validate(struct tdb_context *tdb, tdb_validate_data_func validate_fn)
 102 {
 103         pid_t child_pid = -1;
 104         int child_status = 0;
 105         int wait_pid = 0;
 106         int ret = 1;
 107
 108         if (tdb == NULL) {
 109                 DEBUG(1, ("Error: tdb_validate called with tdb == NULL\n"));
 110                 return ret;
 111         }
 112
 113         DEBUG(5, ("tdb_validate called for tdb '%s'\n", tdb_name(tdb)));
 114
 115         /* fork and let the child do the validation.
 116          * benefit: no need to twist signal handlers and panic functions.
 117          * just let the child panic. we catch the signal. */
 118
 119         DEBUG(10, ("tdb_validate: forking to let child do validation.\n"));
 120         child_pid = fork();
 121         if (child_pid == 0) {
 122                 /* child code */
 123                 DEBUG(10, ("tdb_validate (validation child): created\n"));
 124                 DEBUG(10, ("tdb_validate (validation child): "
 125                            "calling tdb_validate_child\n"));
 126                 exit(tdb_validate_child(tdb, validate_fn));
 127         }
 128         else if (child_pid < 0) {
 129                 DEBUG(1, ("tdb_validate: fork for validation failed.\n"));
 130                 goto done;
 131         }
 132
 133         /* parent */
 134
 135         DEBUG(10, ("tdb_validate: fork succeeded, child PID = %u\n",
 136                 (unsigned int)child_pid));
 137
 138         DEBUG(10, ("tdb_validate: waiting for child to finish...\n"));
 139         while  ((wait_pid = waitpid(child_pid, &child_status, 0)) < 0) {
 140                 if (errno == EINTR) {
 141                         DEBUG(10, ("tdb_validate: got signal during waitpid, "
 142                                    "retrying\n"));
 143                         errno = 0;
 144                         continue;
 145                 }
 146                 DEBUG(1, ("tdb_validate: waitpid failed with error '%s'.\n",
 147                           strerror(errno)));
 148                 goto done;
 149         }
 150         if (wait_pid != child_pid) {
 151                 DEBUG(1, ("tdb_validate: waitpid returned pid %d, "
 152                           "but %u was expected\n", wait_pid, (unsigned int)child_pid));
 153                 goto done;
 154         }
 155
 156         DEBUG(10, ("tdb_validate: validating child returned.\n"));
 157         if (WIFEXITED(child_status)) {
 158                 DEBUG(10, ("tdb_validate: child exited, code %d.\n",
 159                            WEXITSTATUS(child_status)));
 160                 ret = WEXITSTATUS(child_status);
 161         }
 162         if (WIFSIGNALED(child_status)) {
 163                 DEBUG(10, ("tdb_validate: child terminated by signal %d\n",
 164                            WTERMSIG(child_status)));
 165 #ifdef WCOREDUMP
 166                 if (WCOREDUMP(child_status)) {
 167                         DEBUGADD(10, ("core dumped\n"));
 168                 }
 169 #endif
 170                 ret = WTERMSIG(child_status);
 171         }
 172         if (WIFSTOPPED(child_status)) {
 173                 DEBUG(10, ("tdb_validate: child was stopped by signal %d\n",
 174                            WSTOPSIG(child_status)));
 175                 ret = WSTOPSIG(child_status);
 176         }
 177
 178 done:
 179         DEBUG(5, ("tdb_validate returning code '%d' for tdb '%s'\n", ret,
 180                   tdb_name(tdb)));
 181
 182         return ret;
 183 }
 184
 185 /*
 186  * tdb validation function.
 187  * returns 0 if tdb is ok, != 0 if it isn't.
 188  * this is a wrapper around the actual validation function that opens and closes
 189  * the tdb.
 190  */
 191 int tdb_validate_open(const char *tdb_path, tdb_validate_data_func validate_fn)
 192 {
 193         TDB_CONTEXT *tdb = NULL;
 194         int ret = 1;
 195
 196         DEBUG(5, ("tdb_validate_open called for tdb '%s'\n", tdb_path));
 197
 198         tdb = tdb_open_log(tdb_path, 0, TDB_DEFAULT, O_RDWR, 0);
 199         if (!tdb) {
 200                 DEBUG(1, ("Error opening tdb %s\n", tdb_path));
 201                 return ret;
 202         }
 203
 204         ret = tdb_validate(tdb, validate_fn);
 205         tdb_close(tdb);
 206         return ret;
 207 }
 208
 209 /*
 210  * tdb backup function and helpers for tdb_validate wrapper with backup
 211  * handling.
 212  */
 213
 214 /* this structure eliminates the need for a global overall status for
 215  * the traverse-copy */
 216 struct tdb_copy_data {
 217         struct tdb_context *dst;
 218         bool success;
 219 };
 220
 221 static int traverse_copy_fn(struct tdb_context *tdb, TDB_DATA key,
 222                             TDB_DATA dbuf, void *private_data)
 223 {
 224         struct tdb_copy_data *data = (struct tdb_copy_data *)private_data;
 225
 226         if (tdb_store(data->dst, key, dbuf, TDB_INSERT) != 0) {
 227                 DEBUG(4, ("Failed to insert into %s: %s\n", tdb_name(data->dst),
 228                           strerror(errno)));
 229                 data->success = False;
 230                 return 1;
 231         }
 232         return 0;
 233 }
 234
 235 static int tdb_copy(struct tdb_context *src, struct tdb_context *dst)
 236 {
 237         struct tdb_copy_data data;
 238         int count;
 239
 240         data.dst = dst;
 241         data.success = True;
 242
 243         count = tdb_traverse(src, traverse_copy_fn, (void *)(&data));
 244         if ((count < 0) || (data.success == False)) {
 245                 return -1;
 246         }
 247         return count;
 248 }
 249
 250 static int tdb_verify_basic(struct tdb_context *tdb)
 251 {
 252         return tdb_traverse(tdb, NULL, NULL);
 253 }
 254
 255 /* this backup function is essentially taken from lib/tdb/tools/tdbbackup.tdb
 256  */
 257 static int tdb_backup(TALLOC_CTX *ctx, const char *src_path,
 258                       const char *dst_path, int hash_size)
 259 {
 260         struct tdb_context *src_tdb = NULL;
 261         struct tdb_context *dst_tdb = NULL;
 262         char *tmp_path = NULL;
 263         struct stat st;
 264         int count1, count2;
 265         int saved_errno = 0;
 266         int ret = -1;
 267
 268         if (stat(src_path, &st) != 0) {
 269                 DEBUG(3, ("Could not stat '%s': %s\n", src_path,
 270                           strerror(errno)));
 271                 goto done;
 272         }
 273
 274         /* open old tdb RDWR - so we can lock it */
 275         src_tdb = tdb_open_log(src_path, 0, TDB_DEFAULT, O_RDWR, 0);
 276         if (src_tdb == NULL) {
 277                 DEBUG(3, ("Failed to open tdb '%s'\n", src_path));
 278                 goto done;
 279         }
 280
 281         if (tdb_lockall(src_tdb) != 0) {
 282                 DEBUG(3, ("Failed to lock tdb '%s'\n", src_path));
 283                 goto done;
 284         }
 285
 286         tmp_path = talloc_asprintf(ctx, "%s%s", dst_path, ".tmp");
 287         if (!tmp_path) {
 288                 DEBUG(3, ("talloc fail\n"));
 289                 goto done;
 290         }
 291
 292         unlink(tmp_path);
 293
 294         if (!hash_size) {
 295                 hash_size = tdb_hash_size(src_tdb);
 296         }
 297
 298         dst_tdb = tdb_open_log(tmp_path, hash_size,
 299                                TDB_DEFAULT, O_RDWR | O_CREAT | O_EXCL,
 300                                st.st_mode & 0777);
 301         if (dst_tdb == NULL) {
 302                 DEBUG(3, ("Error creating tdb '%s': %s\n", tmp_path,
 303                           strerror(errno)));
 304                 saved_errno = errno;
 305                 unlink(tmp_path);
 306                 goto done;
 307         }
 308
 309         count1 = tdb_copy(src_tdb, dst_tdb);
 310         if (count1 < 0) {
 311                 DEBUG(3, ("Failed to copy tdb '%s': %s\n", src_path,
 312                           strerror(errno)));
 313                 tdb_close(dst_tdb);
 314                 goto done;
 315         }
 316
 317         /* reopen ro and do basic verification */
 318         tdb_close(dst_tdb);
 319         dst_tdb = tdb_open_log(tmp_path, 0, TDB_DEFAULT, O_RDONLY, 0);
 320         if (!dst_tdb) {
 321                 DEBUG(3, ("Failed to reopen tdb '%s': %s\n", tmp_path,
 322                           strerror(errno)));
 323                 goto done;
 324         }
 325         count2 = tdb_verify_basic(dst_tdb);
 326         if (count2 != count1) {
 327                 DEBUG(3, ("Failed to verify result of copying tdb '%s'.\n",
 328                           src_path));
 329                 tdb_close(dst_tdb);
 330                 goto done;
 331         }
 332
 333         DEBUG(10, ("tdb_backup: successfully copied %d entries\n", count1));
 334
 335         /* make sure the new tdb has reached stable storage
 336          * then rename it to its destination */
 337         fsync(tdb_fd(dst_tdb));
 338         tdb_close(dst_tdb);
 339         unlink(dst_path);
 340         if (rename(tmp_path, dst_path) != 0) {
 341                 DEBUG(3, ("Failed to rename '%s' to '%s': %s\n",
 342                           tmp_path, dst_path, strerror(errno)));
 343                 goto done;
 344         }
 345
 346         /* success */
 347         ret = 0;
 348
 349 done:
 350         if (src_tdb != NULL) {
 351                 tdb_close(src_tdb);
 352         }
 353         if (tmp_path != NULL) {
 354                 unlink(tmp_path);
 355                 TALLOC_FREE(tmp_path);
 356         }
 357         if (saved_errno != 0) {
 358                 errno = saved_errno;
 359         }
 360         return ret;
 361 }
 362
 363 static int rename_file_with_suffix(TALLOC_CTX *ctx, const char *path,
 364                                    const char *suffix)
 365 {
 366         int ret = -1;
 367         char *dst_path;
 368
 369         dst_path = talloc_asprintf(ctx, "%s%s", path, suffix);
 370         if (dst_path == NULL) {
 371                 DEBUG(3, ("error out of memory\n"));
 372                 return ret;
 373         }
 374
 375         ret = (rename(path, dst_path) != 0);
 376
 377         if (ret == 0) {
 378                 DEBUG(5, ("moved '%s' to '%s'\n", path, dst_path));
 379         } else if (errno == ENOENT) {
 380                 DEBUG(3, ("file '%s' does not exist - so not moved\n", path));
 381                 ret = 0;
 382         } else {
 383                 DEBUG(3, ("error renaming %s to %s: %s\n", path, dst_path,
 384                           strerror(errno)));
 385         }
 386
 387         TALLOC_FREE(dst_path);
 388         return ret;
 389 }
 390
 391 /*
 392  * do a backup of a tdb, moving the destination out of the way first
 393  */
 394 static int tdb_backup_with_rotate(TALLOC_CTX *ctx, const char *src_path,
 395                                   const char *dst_path, int hash_size,
 396                                   const char *rotate_suffix,
 397                                   bool retry_norotate_if_nospc,
 398                                   bool rename_as_last_resort_if_nospc)
 399 {
 400         int ret;
 401
 402         rename_file_with_suffix(ctx, dst_path, rotate_suffix);
 403
 404         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 405
 406         if (ret != 0) {
 407                 DEBUG(10, ("backup of %s failed: %s\n", src_path, strerror(errno)));
 408         }
 409         if ((ret != 0) && (errno == ENOSPC) && retry_norotate_if_nospc)
 410         {
 411                 char *rotate_path = talloc_asprintf(ctx, "%s%s", dst_path,
 412                                                     rotate_suffix);
 413                 if (rotate_path == NULL) {
 414                         DEBUG(10, ("talloc fail\n"));
 415                         return -1;
 416                 }
 417                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 418                            src_path));
 419                 DEBUGADD(10, ("trying to free some space by removing rotated "
 420                               "dst %s\n", rotate_path));
 421                 if (unlink(rotate_path) == -1) {
 422                         DEBUG(10, ("unlink of %s failed: %s\n", rotate_path,
 423                                    strerror(errno)));
 424                 } else {
 425                         ret = tdb_backup(ctx, src_path, dst_path, hash_size);
 426                 }
 427                 TALLOC_FREE(rotate_path);
 428         }
 429
 430         if ((ret != 0) && (errno == ENOSPC) && rename_as_last_resort_if_nospc)
 431         {
 432                 DEBUG(10, ("backup of %s failed due to lack of space\n",
 433                            src_path));
 434                 DEBUGADD(10, ("using 'rename' as a last resort\n"));
 435                 ret = rename(src_path, dst_path);
 436         }
 437
 438         return ret;
 439 }
 440
 441 /*
 442  * validation function with backup handling:
 443  *
 444  *  - calls tdb_validate
 445  *  - if the tdb is ok, create a backup "name.bak", possibly moving
 446  *    existing backup to name.bak.old,
 447  *    return 0 (success) even if the backup fails
 448  *  - if the tdb is corrupt:
 449  *    - move the tdb to "name.corrupt"
 450  *    - check if there is valid backup.
 451  *      if so, restore the backup.
 452  *      if restore is successful, return 0 (success),
 453  *    - otherwise return -1 (failure)
 454  */
 455 int tdb_validate_and_backup(const char *tdb_path,
 456                             tdb_validate_data_func validate_fn)
 457 {
 458         int ret = -1;
 459         const char *backup_suffix = ".bak";
 460         const char *corrupt_suffix = ".corrupt";
 461         const char *rotate_suffix = ".old";
 462         char *tdb_path_backup;
 463         struct stat st;
 464         TALLOC_CTX *ctx = NULL;
 465
 466         ctx = talloc_new(NULL);
 467         if (ctx == NULL) {
 468                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 469                 goto done;
 470         }
 471
 472         tdb_path_backup = talloc_asprintf(ctx, "%s%s", tdb_path, backup_suffix);
 473         if (!tdb_path_backup) {
 474                 DEBUG(0, ("tdb_validate_and_backup: out of memory\n"));
 475                 goto done;
 476         }
 477
 478         ret = tdb_validate_open(tdb_path, validate_fn);
 479
 480         if (ret == 0) {
 481                 DEBUG(1, ("tdb '%s' is valid\n", tdb_path));
 482                 ret = tdb_backup_with_rotate(ctx, tdb_path, tdb_path_backup, 0,
 483                                              rotate_suffix, True, False);
 484                 if (ret != 0) {
 485                         DEBUG(1, ("Error creating backup of tdb '%s'\n",
 486                                   tdb_path));
 487                         /* the actual validation was successful: */
 488                         ret = 0;
 489                 } else {
 490                         DEBUG(1, ("Created backup '%s' of tdb '%s'\n",
 491                                   tdb_path_backup, tdb_path));
 492                 }
 493         } else {
 494                 DEBUG(1, ("tdb '%s' is invalid\n", tdb_path));
 495
 496                 ret =stat(tdb_path_backup, &st);
 497                 if (ret != 0) {
 498                         DEBUG(5, ("Could not stat '%s': %s\n", tdb_path_backup,
 499                                   strerror(errno)));
 500                         DEBUG(1, ("No backup found.\n"));
 501                 } else {
 502                         DEBUG(1, ("backup '%s' found.\n", tdb_path_backup));
 503                         ret = tdb_validate_open(tdb_path_backup, validate_fn);
 504                         if (ret != 0) {
 505                                 DEBUG(1, ("Backup '%s' is invalid.\n",
 506                                           tdb_path_backup));
 507                         }
 508                 }
 509
 510                 if (ret != 0) {
 511                         int renamed = rename_file_with_suffix(ctx, tdb_path,
 512                                                               corrupt_suffix);
 513                         if (renamed != 0) {
 514                                 DEBUG(1, ("Error moving tdb to '%s%s'\n",
 515                                           tdb_path, corrupt_suffix));
 516                         } else {
 517                                 DEBUG(1, ("Corrupt tdb stored as '%s%s'\n",
 518                                           tdb_path, corrupt_suffix));
 519                         }
 520                         goto done;
 521                 }
 522
 523                 DEBUG(1, ("valid backup '%s' found\n", tdb_path_backup));
 524                 ret = tdb_backup_with_rotate(ctx, tdb_path_backup, tdb_path, 0,
 525                                              corrupt_suffix, True, True);
 526                 if (ret != 0) {
 527                         DEBUG(1, ("Error restoring backup from '%s'\n",
 528                                   tdb_path_backup));
 529                 } else {
 530                         DEBUG(1, ("Restored tdb backup from '%s'\n",
 531                                   tdb_path_backup));
 532                 }
 533         }
 534
 535 done:
 536         TALLOC_FREE(ctx);
 537         return ret;
 538 }