tinc-vpn.org Git - tinc/blob - src/fsck.c

   1 /*
   2     fsck.c -- Check the configuration files for problems
   3     Copyright (C) 2014 Guus Sliepen <guus@tinc-vpn.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21
  22 #include "crypto.h"
  23 #include "ecdsa.h"
  24 #include "ecdsagen.h"
  25 #include "fsck.h"
  26 #include "names.h"
  27 #ifndef DISABLE_LEGACY
  28 #include "rsa.h"
  29 #include "rsagen.h"
  30 #endif
  31 #include "tincctl.h"
  32 #include "utils.h"
  33
  34 static bool ask_fix(void) {
  35         if(force) {
  36                 return true;
  37         }
  38
  39         if(!tty) {
  40                 return false;
  41         }
  42
  43 again:
  44         fprintf(stderr, "Fix y/n? ");
  45         char buf[1024];
  46
  47         if(!fgets(buf, sizeof(buf), stdin)) {
  48                 tty = false;
  49                 return false;
  50         }
  51
  52         if(buf[0] == 'y' || buf[0] == 'Y') {
  53                 return true;
  54         }
  55
  56         if(buf[0] == 'n' || buf[0] == 'N') {
  57                 return false;
  58         }
  59
  60         goto again;
  61 }
  62
  63 static void print_tinc_cmd(const char *argv0, const char *format, ...) {
  64         if(confbasegiven) {
  65                 fprintf(stderr, "%s -c %s ", argv0, confbase);
  66         } else if(netname) {
  67                 fprintf(stderr, "%s -n %s ", argv0, netname);
  68         } else {
  69                 fprintf(stderr, "%s ", argv0);
  70         }
  71
  72         va_list va;
  73         va_start(va, format);
  74         vfprintf(stderr, format, va);
  75         va_end(va);
  76         fputc('\n', stderr);
  77 }
  78
  79 static int strtailcmp(const char *str, const char *tail) {
  80         size_t slen = strlen(str);
  81         size_t tlen = strlen(tail);
  82
  83         if(tlen > slen) {
  84                 return -1;
  85         }
  86
  87         return memcmp(str + slen - tlen, tail, tlen);
  88 }
  89
  90 static void check_conffile(const char *fname, bool server) {
  91         (void)server;
  92
  93         FILE *f = fopen(fname, "r");
  94
  95         if(!f) {
  96                 fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
  97                 return;
  98         }
  99
 100         char line[2048];
 101         int lineno = 0;
 102         bool skip = false;
 103         const int maxvariables = 50;
 104         int count[maxvariables];
 105         memset(count, 0, sizeof(count));
 106
 107         while(fgets(line, sizeof(line), f)) {
 108                 if(skip) {
 109                         if(!strncmp(line, "-----END", 8)) {
 110                                 skip = false;
 111                         }
 112
 113                         continue;
 114                 } else {
 115                         if(!strncmp(line, "-----BEGIN", 10)) {
 116                                 skip = true;
 117                                 continue;
 118                         }
 119                 }
 120
 121                 int len;
 122                 char *variable, *value, *eol;
 123                 variable = value = line;
 124
 125                 lineno++;
 126
 127                 eol = line + strlen(line);
 128
 129                 while(strchr("\t \r\n", *--eol)) {
 130                         *eol = '\0';
 131                 }
 132
 133                 if(!line[0] || line[0] == '#') {
 134                         continue;
 135                 }
 136
 137                 len = strcspn(value, "\t =");
 138                 value += len;
 139                 value += strspn(value, "\t ");
 140
 141                 if(*value == '=') {
 142                         value++;
 143                         value += strspn(value, "\t ");
 144                 }
 145
 146                 variable[len] = '\0';
 147
 148                 bool found = false;
 149
 150                 for(int i = 0; variables[i].name; i++) {
 151                         if(strcasecmp(variables[i].name, variable)) {
 152                                 continue;
 153                         }
 154
 155                         found = true;
 156
 157                         if(variables[i].type & VAR_OBSOLETE) {
 158                                 fprintf(stderr, "WARNING: obsolete variable %s in %s line %d\n", variable, fname, lineno);
 159                         }
 160
 161                         if(i < maxvariables) {
 162                                 count[i]++;
 163                         }
 164                 }
 165
 166                 if(!found) {
 167                         fprintf(stderr, "WARNING: unknown variable %s in %s line %d\n", variable, fname, lineno);
 168                 }
 169
 170                 if(!*value) {
 171                         fprintf(stderr, "ERROR: no value for variable %s in %s line %d\n", variable, fname, lineno);
 172                 }
 173         }
 174
 175         for(int i = 0; variables[i].name && i < maxvariables; i++) {
 176                 if(count[i] > 1 && !(variables[i].type & VAR_MULTIPLE)) {
 177                         fprintf(stderr, "WARNING: multiple instances of variable %s in %s\n", variables[i].name, fname);
 178                 }
 179         }
 180
 181         if(ferror(f)) {
 182                 fprintf(stderr, "ERROR: while reading %s: %s\n", fname, strerror(errno));
 183         }
 184
 185         fclose(f);
 186 }
 187
 188 int fsck(const char *argv0) {
 189 #ifdef HAVE_MINGW
 190         int uid = 0;
 191 #else
 192         uid_t uid = getuid();
 193 #endif
 194
 195         // Check that tinc.conf is readable.
 196
 197         if(access(tinc_conf, R_OK)) {
 198                 fprintf(stderr, "ERROR: cannot read %s: %s\n", tinc_conf, strerror(errno));
 199
 200                 if(errno == ENOENT) {
 201                         fprintf(stderr, "No tinc configuration found. Create a new one with:\n\n");
 202                         print_tinc_cmd(argv0, "init");
 203                 } else if(errno == EACCES) {
 204                         if(uid != 0) {
 205                                 fprintf(stderr, "You are currently not running tinc as root. Use sudo?\n");
 206                         } else {
 207                                 fprintf(stderr, "Check the permissions of each component of the path %s.\n", tinc_conf);
 208                         }
 209                 }
 210
 211                 return 1;
 212         }
 213
 214         char *name = get_my_name(true);
 215
 216         if(!name) {
 217                 fprintf(stderr, "ERROR: tinc cannot run without a valid Name.\n");
 218                 return 1;
 219         }
 220
 221         // Check for private keys.
 222         // TODO: use RSAPrivateKeyFile and Ed25519PrivateKeyFile variables if present.
 223
 224         struct stat st;
 225         char fname[PATH_MAX];
 226         char dname[PATH_MAX];
 227
 228 #ifndef DISABLE_LEGACY
 229         rsa_t *rsa_priv = NULL;
 230         snprintf(fname, sizeof(fname), "%s/rsa_key.priv", confbase);
 231
 232         if(stat(fname, &st)) {
 233                 if(errno != ENOENT) {
 234                         // Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
 235                         fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
 236                         fprintf(stderr, "Please correct this error.\n");
 237                         return 1;
 238                 }
 239         } else {
 240                 FILE *f = fopen(fname, "r");
 241
 242                 if(!f) {
 243                         fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
 244                         return 1;
 245                 }
 246
 247                 rsa_priv = rsa_read_pem_private_key(f);
 248                 fclose(f);
 249
 250                 if(!rsa_priv) {
 251                         fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
 252                         fprintf(stderr, "You can generate a new RSA key with:\n\n");
 253                         print_tinc_cmd(argv0, "generate-rsa-keys");
 254                         return 1;
 255                 }
 256
 257 #ifndef HAVE_MINGW
 258
 259                 if(st.st_mode & 077) {
 260                         fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
 261
 262                         if(st.st_uid != uid) {
 263                                 fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
 264                         } else if(ask_fix()) {
 265                                 if(chmod(fname, st.st_mode & ~077)) {
 266                                         fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
 267                                 } else {
 268                                         fprintf(stderr, "Fixed permissions of %s.\n", fname);
 269                                 }
 270                         }
 271                 }
 272
 273 #endif
 274         }
 275
 276 #endif
 277
 278         ecdsa_t *ecdsa_priv = NULL;
 279         snprintf(fname, sizeof(fname), "%s/ed25519_key.priv", confbase);
 280
 281         if(stat(fname, &st)) {
 282                 if(errno != ENOENT) {
 283                         // Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
 284                         fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
 285                         fprintf(stderr, "Please correct this error.\n");
 286                         return 1;
 287                 }
 288         } else {
 289                 FILE *f = fopen(fname, "r");
 290
 291                 if(!f) {
 292                         fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
 293                         return 1;
 294                 }
 295
 296                 ecdsa_priv = ecdsa_read_pem_private_key(f);
 297                 fclose(f);
 298
 299                 if(!ecdsa_priv) {
 300                         fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
 301                         fprintf(stderr, "You can generate a new Ed25519 key with:\n\n");
 302                         print_tinc_cmd(argv0, "generate-ed25519-keys");
 303                         return 1;
 304                 }
 305
 306 #ifndef HAVE_MINGW
 307
 308                 if(st.st_mode & 077) {
 309                         fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
 310
 311                         if(st.st_uid != uid) {
 312                                 fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
 313                         } else if(ask_fix()) {
 314                                 if(chmod(fname, st.st_mode & ~077)) {
 315                                         fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
 316                                 } else {
 317                                         fprintf(stderr, "Fixed permissions of %s.\n", fname);
 318                                 }
 319                         }
 320                 }
 321
 322 #endif
 323         }
 324
 325 #ifdef DISABLE_LEGACY
 326
 327         if(!ecdsa_priv) {
 328                 fprintf(stderr, "ERROR: No Ed25519 private key found.\n");
 329 #else
 330
 331         if(!rsa_priv && !ecdsa_priv) {
 332                 fprintf(stderr, "ERROR: Neither RSA or Ed25519 private key found.\n");
 333 #endif
 334                 fprintf(stderr, "You can generate new keys with:\n\n");
 335                 print_tinc_cmd(argv0, "generate-keys");
 336                 return 1;
 337         }
 338
 339         // Check for public keys.
 340         // TODO: use RSAPublicKeyFile variable if present.
 341
 342         snprintf(fname, sizeof(fname), "%s/hosts/%s", confbase, name);
 343
 344         if(access(fname, R_OK)) {
 345                 fprintf(stderr, "WARNING: cannot read %s\n", fname);
 346         }
 347
 348         FILE *f;
 349
 350 #ifndef DISABLE_LEGACY
 351         rsa_t *rsa_pub = NULL;
 352
 353         f = fopen(fname, "r");
 354
 355         if(f) {
 356                 rsa_pub = rsa_read_pem_public_key(f);
 357                 fclose(f);
 358         }
 359
 360         if(rsa_priv) {
 361                 if(!rsa_pub) {
 362                         fprintf(stderr, "WARNING: No (usable) public RSA key found.\n");
 363
 364                         if(ask_fix()) {
 365                                 FILE *f = fopen(fname, "a");
 366
 367                                 if(f) {
 368                                         if(rsa_write_pem_public_key(rsa_priv, f)) {
 369                                                 fprintf(stderr, "Wrote RSA public key to %s.\n", fname);
 370                                         } else {
 371                                                 fprintf(stderr, "ERROR: could not write RSA public key to %s.\n", fname);
 372                                         }
 373
 374                                         fclose(f);
 375                                 } else {
 376                                         fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
 377                                 }
 378                         }
 379                 } else {
 380                         // TODO: suggest remedies
 381                         size_t len = rsa_size(rsa_priv);
 382
 383                         if(len != rsa_size(rsa_pub)) {
 384                                 fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
 385                                 return 1;
 386                         }
 387
 388                         char buf1[len], buf2[len], buf3[len];
 389                         randomize(buf1, sizeof(buf1));
 390                         buf1[0] &= 0x7f;
 391                         memset(buf2, 0, sizeof(buf2));
 392                         memset(buf3, 0, sizeof(buf2));
 393
 394                         if(!rsa_public_encrypt(rsa_pub, buf1, sizeof(buf1), buf2)) {
 395                                 fprintf(stderr, "ERROR: public RSA key does not work.\n");
 396                                 return 1;
 397                         }
 398
 399                         if(!rsa_private_decrypt(rsa_priv, buf2, sizeof(buf2), buf3)) {
 400                                 fprintf(stderr, "ERROR: private RSA key does not work.\n");
 401                                 return 1;
 402                         }
 403
 404                         if(memcmp(buf1, buf3, sizeof(buf1))) {
 405                                 fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
 406                                 return 1;
 407                         }
 408                 }
 409         } else {
 410                 if(rsa_pub) {
 411                         fprintf(stderr, "WARNING: A public RSA key was found but no private key is known.\n");
 412                 }
 413         }
 414
 415 #endif
 416
 417         ecdsa_t *ecdsa_pub = NULL;
 418
 419         f = fopen(fname, "r");
 420
 421         if(f) {
 422                 ecdsa_pub = get_pubkey(f);
 423
 424                 if(!ecdsa_pub) {
 425                         rewind(f);
 426                         ecdsa_pub = ecdsa_read_pem_public_key(f);
 427                 }
 428
 429                 fclose(f);
 430         }
 431
 432         if(ecdsa_priv) {
 433                 if(!ecdsa_pub) {
 434                         fprintf(stderr, "WARNING: No (usable) public Ed25519 key found.\n");
 435
 436                         if(ask_fix()) {
 437                                 FILE *f = fopen(fname, "a");
 438
 439                                 if(f) {
 440                                         if(ecdsa_write_pem_public_key(ecdsa_priv, f)) {
 441                                                 fprintf(stderr, "Wrote Ed25519 public key to %s.\n", fname);
 442                                         } else {
 443                                                 fprintf(stderr, "ERROR: could not write Ed25519 public key to %s.\n", fname);
 444                                         }
 445
 446                                         fclose(f);
 447                                 } else {
 448                                         fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
 449                                 }
 450                         }
 451                 } else {
 452                         // TODO: suggest remedies
 453                         char *key1 = ecdsa_get_base64_public_key(ecdsa_pub);
 454
 455                         if(!key1) {
 456                                 fprintf(stderr, "ERROR: public Ed25519 key does not work.\n");
 457                                 return 1;
 458                         }
 459
 460                         char *key2 = ecdsa_get_base64_public_key(ecdsa_priv);
 461
 462                         if(!key2) {
 463                                 free(key1);
 464                                 fprintf(stderr, "ERROR: private Ed25519 key does not work.\n");
 465                                 return 1;
 466                         }
 467
 468                         int result = strcmp(key1, key2);
 469                         free(key1);
 470                         free(key2);
 471
 472                         if(result) {
 473                                 fprintf(stderr, "ERROR: public and private Ed25519 keys do not match.\n");
 474                                 return 1;
 475                         }
 476                 }
 477         } else {
 478                 if(ecdsa_pub) {
 479                         fprintf(stderr, "WARNING: A public Ed25519 key was found but no private key is known.\n");
 480                 }
 481         }
 482
 483         // Check whether scripts are executable
 484
 485         struct dirent *ent;
 486         DIR *dir = opendir(confbase);
 487
 488         if(!dir) {
 489                 fprintf(stderr, "ERROR: cannot read directory %s: %s\n", confbase, strerror(errno));
 490                 return 1;
 491         }
 492
 493         while((ent = readdir(dir))) {
 494                 if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down")) {
 495                         continue;
 496                 }
 497
 498                 strncpy(fname, ent->d_name, sizeof(fname));
 499                 char *dash = strrchr(fname, '-');
 500
 501                 if(!dash) {
 502                         continue;
 503                 }
 504
 505                 *dash = 0;
 506
 507                 if(strcmp(fname, "tinc") && strcmp(fname, "host") && strcmp(fname, "subnet")) {
 508                         static bool explained = false;
 509                         fprintf(stderr, "WARNING: Unknown script %s" SLASH "%s found.\n", confbase, ent->d_name);
 510
 511                         if(!explained) {
 512                                 fprintf(stderr, "The only scripts in %s executed by tinc are:\n", confbase);
 513                                 fprintf(stderr, "tinc-up, tinc-down, host-up, host-down, subnet-up and subnet-down.\n");
 514                                 explained = true;
 515                         }
 516
 517                         continue;
 518                 }
 519
 520                 snprintf(fname, sizeof(fname), "%s" SLASH "%s", confbase, ent->d_name);
 521
 522                 if(access(fname, R_OK | X_OK)) {
 523                         if(errno != EACCES) {
 524                                 fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
 525                                 continue;
 526                         }
 527
 528                         fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
 529
 530                         if(ask_fix()) {
 531                                 if(chmod(fname, 0755)) {
 532                                         fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
 533                                 }
 534                         }
 535                 }
 536         }
 537
 538         closedir(dir);
 539
 540         snprintf(dname, sizeof(dname), "%s" SLASH "hosts", confbase);
 541         dir = opendir(dname);
 542
 543         if(!dir) {
 544                 fprintf(stderr, "ERROR: cannot read directory %s: %s\n", dname, strerror(errno));
 545                 return 1;
 546         }
 547
 548         while((ent = readdir(dir))) {
 549                 if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down")) {
 550                         continue;
 551                 }
 552
 553                 strncpy(fname, ent->d_name, sizeof(fname));
 554                 char *dash = strrchr(fname, '-');
 555
 556                 if(!dash) {
 557                         continue;
 558                 }
 559
 560                 *dash = 0;
 561
 562                 snprintf(fname, sizeof(fname), "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
 563
 564                 if(access(fname, R_OK | X_OK)) {
 565                         if(errno != EACCES) {
 566                                 fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
 567                                 continue;
 568                         }
 569
 570                         fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
 571
 572                         if(ask_fix()) {
 573                                 if(chmod(fname, 0755)) {
 574                                         fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
 575                                 }
 576                         }
 577                 }
 578         }
 579
 580         closedir(dir);
 581
 582         // Check for obsolete / unsafe / unknown configuration variables.
 583
 584         check_conffile(tinc_conf, true);
 585
 586         dir = opendir(dname);
 587
 588         if(dir) {
 589                 while((ent = readdir(dir))) {
 590                         if(!check_id(ent->d_name)) {
 591                                 continue;
 592                         }
 593
 594                         snprintf(fname, sizeof(fname), "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
 595                         check_conffile(fname, false);
 596                 }
 597
 598                 closedir(dir);
 599         }
 600
 601         return 0;
 602 }
 603