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Viewing changes to plugins.d/mandos-client.c

  • Committer: Teddy Hogeborn
  • Date: 2015-07-01 20:01:26 UTC
  • mto: This revision was merged to the branch mainline in revision 759.
  • Revision ID: teddy@recompile.se-20150701200126-qb3f6c3jcas2f4og
mandos-client: Try to start a plugin to add and remove a local route.

* debian/mandos-client.README.Debian: Add setting of environment
                                      variable MANDOSPLUGINHELPERDIR
                                      to command line testing
                                      mandos-client.
* mandos-client.c (raise_privileges): Moved to top of file.
                  (raise_privileges_permanently): - '' -
                  (lower_privileges): - '' -
                  (lower_privileges_permanently): - '' -
  (add_remove_local_route, add_local_route, remove_local_route): New.
  (start_mandos_communication): Set SOCK_CLOEXEC flag on socket.  Run
                                the above functions to add (and
                                remove) local route, if the conditions
                                indicates it could help.
  (run_network_hooks): Use O_DIRECTORY, O_PATH, and O_CLOEXEC flags
                       when opening network hook directory. Do
                       TEMP_FAILURE_RETRY around opening of /dev/null
                       and network hook executables.  Move redirecting
                       of stdout and stderr to as late as possible
                       before fexecve().
  (main): Use O_DIRECTORY and O_PATH when opening temporary directory.
* plugins.d/mandos-client.xml (ENVIRONMENT): Document usage of the
                                             MANDOSPLUGINHELPERDIR
                                             environment variable.

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added added

removed removed

Lines of Context:
plugins.d/mandos-client.c
493
493
  return plaintext_length;
494
494
}
495
495
 
496
 
__attribute__((warn_unused_result, const))
497
 
static const char *safe_string(const char *str){
498
 
  if(str == NULL)
499
 
    return "(unknown)";
500
 
  return str;
501
 
}
502
 
 
503
496
__attribute__((warn_unused_result))
504
497
static const char *safer_gnutls_strerror(int value){
505
498
  const char *ret = gnutls_strerror(value);
506
 
  return safe_string(ret);
 
499
  if(ret == NULL)
 
500
    ret = "(unknown)";
 
501
  return ret;
507
502
}
508
503
 
509
504
/* GnuTLS log function callback */
516
511
__attribute__((nonnull, warn_unused_result))
517
512
static int init_gnutls_global(const char *pubkeyfilename,
518
513
                              const char *seckeyfilename,
519
 
                              const char *dhparamsfilename,
520
514
                              mandos_context *mc){
521
515
  int ret;
522
 
  unsigned int uret;
523
516
  
524
517
  if(debug){
525
518
    fprintf_plus(stderr, "Initializing GnuTLS\n");
576
569
                 safer_gnutls_strerror(ret));
577
570
    goto globalfail;
578
571
  }
579
 
  /* If a Diffie-Hellman parameters file was given, try to use it */
580
 
  if(dhparamsfilename != NULL){
581
 
    gnutls_datum_t params = { .data = NULL, .size = 0 };
582
 
    do {
583
 
      int dhpfile = open(dhparamsfilename, O_RDONLY);
584
 
      if(dhpfile == -1){
585
 
        perror_plus("open");
586
 
        dhparamsfilename = NULL;
587
 
        break;
588
 
      }
589
 
      size_t params_capacity = 0;
590
 
      while(true){
591
 
        params_capacity = incbuffer((char **)&params.data,
592
 
                                    (size_t)params.size,
593
 
                                    (size_t)params_capacity);
594
 
        if(params_capacity == 0){
595
 
          perror_plus("incbuffer");
596
 
          free(params.data);
597
 
          params.data = NULL;
598
 
          dhparamsfilename = NULL;
599
 
          break;
600
 
        }
601
 
        ssize_t bytes_read = read(dhpfile,
602
 
                                  params.data + params.size,
603
 
                                  BUFFER_SIZE);
604
 
        /* EOF */
605
 
        if(bytes_read == 0){
606
 
          break;
607
 
        }
608
 
        /* check bytes_read for failure */
609
 
        if(bytes_read < 0){
610
 
          perror_plus("read");
611
 
          free(params.data);
612
 
          params.data = NULL;
613
 
          dhparamsfilename = NULL;
614
 
          break;
615
 
        }
616
 
        params.size += (unsigned int)bytes_read;
617
 
      }
618
 
      if(params.data == NULL){
619
 
        dhparamsfilename = NULL;
620
 
      }
621
 
      if(dhparamsfilename == NULL){
622
 
        break;
623
 
      }
624
 
      ret = gnutls_dh_params_import_pkcs3(mc->dh_params, &params,
625
 
                                          GNUTLS_X509_FMT_PEM);
626
 
      if(ret != GNUTLS_E_SUCCESS){
627
 
        fprintf_plus(stderr, "Failed to parse DH parameters in file"
628
 
                     " \"%s\": %s\n", dhparamsfilename,
629
 
                     safer_gnutls_strerror(ret));
630
 
        dhparamsfilename = NULL;
631
 
      }
632
 
    } while(false);
633
 
  }
634
 
  if(dhparamsfilename == NULL){
635
 
    if(mc->dh_bits == 0){
636
 
      /* Find out the optimal number of DH bits */
637
 
      /* Try to read the private key file */
638
 
      gnutls_datum_t buffer = { .data = NULL, .size = 0 };
639
 
      do {
640
 
        int secfile = open(seckeyfilename, O_RDONLY);
641
 
        if(secfile == -1){
642
 
          perror_plus("open");
643
 
          break;
644
 
        }
645
 
        size_t buffer_capacity = 0;
646
 
        while(true){
647
 
          buffer_capacity = incbuffer((char **)&buffer.data,
648
 
                                      (size_t)buffer.size,
649
 
                                      (size_t)buffer_capacity);
650
 
          if(buffer_capacity == 0){
651
 
            perror_plus("incbuffer");
652
 
            free(buffer.data);
653
 
            buffer.data = NULL;
654
 
            break;
655
 
          }
656
 
          ssize_t bytes_read = read(secfile,
657
 
                                    buffer.data + buffer.size,
658
 
                                    BUFFER_SIZE);
659
 
          /* EOF */
660
 
          if(bytes_read == 0){
661
 
            break;
662
 
          }
663
 
          /* check bytes_read for failure */
664
 
          if(bytes_read < 0){
665
 
            perror_plus("read");
666
 
            free(buffer.data);
667
 
            buffer.data = NULL;
668
 
            break;
669
 
          }
670
 
          buffer.size += (unsigned int)bytes_read;
671
 
        }
672
 
        close(secfile);
673
 
      } while(false);
674
 
      /* If successful, use buffer to parse private key */
675
 
      gnutls_sec_param_t sec_param = GNUTLS_SEC_PARAM_ULTRA;
676
 
      if(buffer.data != NULL){
677
 
        {
678
 
          gnutls_openpgp_privkey_t privkey = NULL;
679
 
          ret = gnutls_openpgp_privkey_init(&privkey);
680
 
          if(ret != GNUTLS_E_SUCCESS){
681
 
            fprintf_plus(stderr, "Error initializing OpenPGP key"
682
 
                         " structure: %s",
683
 
                         safer_gnutls_strerror(ret));
684
 
            free(buffer.data);
685
 
            buffer.data = NULL;
686
 
          } else {
687
 
            ret = gnutls_openpgp_privkey_import
688
 
              (privkey, &buffer, GNUTLS_OPENPGP_FMT_BASE64, "", 0);
689
 
            if(ret != GNUTLS_E_SUCCESS){
690
 
              fprintf_plus(stderr, "Error importing OpenPGP key : %s",
691
 
                           safer_gnutls_strerror(ret));
692
 
              privkey = NULL;
693
 
            }
694
 
            free(buffer.data);
695
 
            buffer.data = NULL;
696
 
            if(privkey != NULL){
697
 
              /* Use private key to suggest an appropriate
698
 
                 sec_param */
699
 
              sec_param = gnutls_openpgp_privkey_sec_param(privkey);
700
 
              gnutls_openpgp_privkey_deinit(privkey);
701
 
              if(debug){
702
 
                fprintf_plus(stderr, "This OpenPGP key implies using"
703
 
                             " a GnuTLS security parameter \"%s\".\n",
704
 
                             safe_string(gnutls_sec_param_get_name
705
 
                                         (sec_param)));
706
 
              }
707
 
            }
708
 
          }
709
 
        }
710
 
        if(sec_param == GNUTLS_SEC_PARAM_UNKNOWN){
711
 
          /* Err on the side of caution */
712
 
          sec_param = GNUTLS_SEC_PARAM_ULTRA;
713
 
          if(debug){
714
 
            fprintf_plus(stderr, "Falling back to security parameter"
715
 
                         " \"%s\"\n",
716
 
                         safe_string(gnutls_sec_param_get_name
717
 
                                     (sec_param)));
718
 
          }
719
 
        }
720
 
      }
721
 
      uret = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, sec_param);
722
 
      if(uret != 0){
723
 
        mc->dh_bits = uret;
724
 
        if(debug){
725
 
          fprintf_plus(stderr, "A \"%s\" GnuTLS security parameter"
726
 
                       " implies %u DH bits; using that.\n",
727
 
                       safe_string(gnutls_sec_param_get_name
728
 
                                   (sec_param)),
729
 
                       mc->dh_bits);
730
 
        }
731
 
      } else {
732
 
        fprintf_plus(stderr, "Failed to get implied number of DH"
733
 
                     " bits for security parameter \"%s\"): %s\n",
734
 
                     safe_string(gnutls_sec_param_get_name
735
 
                                 (sec_param)),
736
 
                     safer_gnutls_strerror(ret));
737
 
        goto globalfail;
738
 
      }
739
 
    } else if(debug){
740
 
      fprintf_plus(stderr, "DH bits explicitly set to %u\n",
741
 
                   mc->dh_bits);
742
 
    }
743
 
    ret = gnutls_dh_params_generate2(mc->dh_params, mc->dh_bits);
744
 
    if(ret != GNUTLS_E_SUCCESS){
745
 
      fprintf_plus(stderr, "Error in GnuTLS prime generation (%u"
746
 
                   " bits): %s\n", mc->dh_bits,
747
 
                   safer_gnutls_strerror(ret));
748
 
      goto globalfail;
749
 
    }
750
 
  }
 
572
  ret = gnutls_dh_params_generate2(mc->dh_params, mc->dh_bits);
 
573
  if(ret != GNUTLS_E_SUCCESS){
 
574
    fprintf_plus(stderr, "Error in GnuTLS prime generation: %s\n",
 
575
                 safer_gnutls_strerror(ret));
 
576
    goto globalfail;
 
577
  }
 
578
  
751
579
  gnutls_certificate_set_dh_params(mc->cred, mc->dh_params);
752
580
  
753
581
  return 0;
813
641
  /* ignore client certificate if any. */
814
642
  gnutls_certificate_server_set_request(*session, GNUTLS_CERT_IGNORE);
815
643
  
 
644
  gnutls_dh_set_prime_bits(*session, mc->dh_bits);
 
645
  
816
646
  return 0;
817
647
}
818
648
 
872
702
  return ret_errno;
873
703
}
874
704
 
875
 
/* Helper function to add_local_route() and delete_local_route() */
 
705
/* Helper function to add_local_route() and remove_local_route() */
876
706
__attribute__((nonnull, warn_unused_result))
877
 
static bool add_delete_local_route(const bool add,
 
707
static bool add_remove_local_route(const bool add,
878
708
                                   const char *address,
879
709
                                   AvahiIfIndex if_index){
880
710
  int ret;
881
711
  char helper[] = "mandos-client-iprouteadddel";
882
712
  char add_arg[] = "add";
883
 
  char delete_arg[] = "delete";
884
 
  char debug_flag[] = "--debug";
 
713
  char remove_arg[] = "remove";
885
714
  char *pluginhelperdir = getenv("MANDOSPLUGINHELPERDIR");
886
715
  if(pluginhelperdir == NULL){
887
716
    if(debug){
931
760
      perror_plus("dup2(devnull, STDIN_FILENO)");
932
761
      _exit(EX_OSERR);
933
762
    }
934
 
    ret = (int)TEMP_FAILURE_RETRY(close(devnull));
 
763
    ret = close(devnull);
935
764
    if(ret == -1){
936
765
      perror_plus("close");
937
766
      _exit(EX_OSERR);
946
775
                                                    | O_DIRECTORY
947
776
                                                    | O_PATH
948
777
                                                    | O_CLOEXEC));
949
 
    if(helperdir_fd == -1){
950
 
      perror_plus("open");
951
 
      _exit(EX_UNAVAILABLE);
952
 
    }
953
778
    int helper_fd = (int)TEMP_FAILURE_RETRY(openat(helperdir_fd,
954
779
                                                   helper, O_RDONLY));
955
 
    if(helper_fd == -1){
956
 
      perror_plus("openat");
957
 
      _exit(EX_UNAVAILABLE);
958
 
    }
959
780
    TEMP_FAILURE_RETRY(close(helperdir_fd));
960
781
#ifdef __GNUC__
961
782
#pragma GCC diagnostic push
962
783
#pragma GCC diagnostic ignored "-Wcast-qual"
963
784
#endif
964
785
    if(fexecve(helper_fd, (char *const [])
965
 
               { helper, add ? add_arg : delete_arg, (char *)address,
966
 
                   interface, debug ? debug_flag : NULL, NULL },
967
 
               environ) == -1){
 
786
               { helper, add ? add_arg : remove_arg, (char *)address,
 
787
                   interface, NULL }, environ) == -1){
968
788
#ifdef __GNUC__
969
789
#pragma GCC diagnostic pop
970
790
#endif
1022
842
__attribute__((nonnull, warn_unused_result))
1023
843
static bool add_local_route(const char *address,
1024
844
                            AvahiIfIndex if_index){
1025
 
  if(debug){
1026
 
    fprintf_plus(stderr, "Adding route to %s\n", address);
1027
 
  }
1028
 
  return add_delete_local_route(true, address, if_index);
 
845
  return add_remove_local_route(true, address, if_index);
1029
846
}
1030
847
 
1031
848
__attribute__((nonnull, warn_unused_result))
1032
 
static bool delete_local_route(const char *address,
 
849
static bool remove_local_route(const char *address,
1033
850
                               AvahiIfIndex if_index){
1034
 
  if(debug){
1035
 
    fprintf_plus(stderr, "Removing route to %s\n", address);
1036
 
  }
1037
 
  return add_delete_local_route(false, address, if_index);
 
851
  return add_remove_local_route(false, address, if_index);
1038
852
}
1039
853
 
1040
854
/* Called when a Mandos server is found */
1243
1057
           http://lists.freedesktop.org/archives/avahi/2010-February/001833.html
1244
1058
           https://bugs.debian.org/587961
1245
1059
        */
1246
 
        if(debug){
1247
 
          fprintf_plus(stderr, "Mandos server unreachable, trying"
1248
 
                       " direct route\n");
1249
 
        }
1250
1060
        int e = errno;
1251
1061
        route_added = add_local_route(ip, if_index);
1252
1062
        if(route_added){
1456
1266
 mandos_end:
1457
1267
  {
1458
1268
    if(route_added){
1459
 
      if(not delete_local_route(ip, if_index)){
1460
 
        fprintf_plus(stderr, "Failed to delete local route to %s on"
 
1269
      if(not remove_local_route(ip, if_index)){
 
1270
        fprintf_plus(stderr, "Failed to remove local route to %s on"
1461
1271
                     " interface %d", ip, if_index);
1462
1272
      }
1463
1273
    }
2003
1813
          _exit(EX_OSERR);
2004
1814
        }
2005
1815
      }
2006
 
      int hook_fd = (int)TEMP_FAILURE_RETRY(openat(hookdir_fd,
2007
 
                                                   direntry->d_name,
2008
 
                                                   O_RDONLY));
 
1816
      int hook_fd = TEMP_FAILURE_RETRY(openat(hookdir_fd,
 
1817
                                              direntry->d_name,
 
1818
                                              O_RDONLY));
2009
1819
      if(hook_fd == -1){
2010
1820
        perror_plus("openat");
2011
1821
        _exit(EXIT_FAILURE);
2019
1829
        perror_plus("dup2(devnull, STDIN_FILENO)");
2020
1830
        _exit(EX_OSERR);
2021
1831
      }
2022
 
      ret = (int)TEMP_FAILURE_RETRY(close(devnull));
 
1832
      ret = close(devnull);
2023
1833
      if(ret == -1){
2024
1834
        perror_plus("close");
2025
1835
        _exit(EX_OSERR);
2285
2095
}
2286
2096
 
2287
2097
int main(int argc, char *argv[]){
2288
 
  mandos_context mc = { .server = NULL, .dh_bits = 0,
 
2098
  mandos_context mc = { .server = NULL, .dh_bits = 1024,
2289
2099
                        .priority = "SECURE256:!CTYPE-X.509:"
2290
 
                        "+CTYPE-OPENPGP:!RSA", .current_server = NULL,
 
2100
                        "+CTYPE-OPENPGP", .current_server = NULL,
2291
2101
                        .interfaces = NULL, .interfaces_size = 0 };
2292
2102
  AvahiSServiceBrowser *sb = NULL;
2293
2103
  error_t ret_errno;
2303
2113
  AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
2304
2114
  const char *seckey = PATHDIR "/" SECKEY;
2305
2115
  const char *pubkey = PATHDIR "/" PUBKEY;
2306
 
  const char *dh_params_file = NULL;
2307
2116
  char *interfaces_hooks = NULL;
2308
2117
  
2309
2118
  bool gnutls_initialized = false;
2362
2171
        .doc = "Bit length of the prime number used in the"
2363
2172
        " Diffie-Hellman key exchange",
2364
2173
        .group = 2 },
2365
 
      { .name = "dh-params", .key = 134,
2366
 
        .arg = "FILE",
2367
 
        .doc = "PEM-encoded PKCS#3 file with pre-generated parameters"
2368
 
        " for the Diffie-Hellman key exchange",
2369
 
        .group = 2 },
2370
2174
      { .name = "priority", .key = 130,
2371
2175
        .arg = "STRING",
2372
2176
        .doc = "GnuTLS priority string for the TLS handshake",
2427
2231
        }
2428
2232
        mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
2429
2233
        break;
2430
 
      case 134:                 /* --dh-params */
2431
 
        dh_params_file = arg;
2432
 
        break;
2433
2234
      case 130:                 /* --priority */
2434
2235
        mc.priority = arg;
2435
2236
        break;
2546
2347
        }
2547
2348
      }
2548
2349
      
2549
 
      if(strcmp(dh_params_file, PATHDIR "/dhparams.pem" ) == 0){
2550
 
        int dhparams_fd = open(dh_params_file, O_RDONLY);
2551
 
        if(dhparams_fd == -1){
2552
 
          perror_plus("open");
2553
 
        } else {
2554
 
          ret = (int)TEMP_FAILURE_RETRY(fstat(dhparams_fd, &st));
2555
 
          if(ret == -1){
2556
 
            perror_plus("fstat");
2557
 
          } else {
2558
 
            if(S_ISREG(st.st_mode)
2559
 
               and st.st_uid == 0 and st.st_gid == 0){
2560
 
              ret = fchown(dhparams_fd, uid, gid);
2561
 
              if(ret == -1){
2562
 
                perror_plus("fchown");
2563
 
              }
2564
 
            }
2565
 
          }
2566
 
          TEMP_FAILURE_RETRY(close(dhparams_fd));
2567
 
        }
2568
 
      }
2569
 
      
2570
2350
      /* Lower privileges */
2571
2351
      ret_errno = lower_privileges();
2572
2352
      if(ret_errno != 0){
2746
2526
      errno = bring_up_interface(interface, delay);
2747
2527
      if(not interface_was_up){
2748
2528
        if(errno != 0){
2749
 
          fprintf_plus(stderr, "Failed to bring up interface \"%s\":"
2750
 
                       " %s\n", interface, strerror(errno));
 
2529
          perror_plus("Failed to bring up interface");
2751
2530
        } else {
2752
2531
          errno = argz_add(&interfaces_to_take_down,
2753
2532
                           &interfaces_to_take_down_size,
2776
2555
    goto end;
2777
2556
  }
2778
2557
  
2779
 
  ret = init_gnutls_global(pubkey, seckey, dh_params_file, &mc);
 
2558
  ret = init_gnutls_global(pubkey, seckey, &mc);
2780
2559
  if(ret == -1){
2781
2560
    fprintf_plus(stderr, "init_gnutls_global failed\n");
2782
2561
    exitcode = EX_UNAVAILABLE;