43
43
stdout, ferror(), remove() */
44
44
#include <stdint.h> /* uint16_t, uint32_t */
45
45
#include <stddef.h> /* NULL, size_t, ssize_t */
46
#include <stdlib.h> /* free(), EXIT_SUCCESS, EXIT_FAILURE,
46
#include <stdlib.h> /* free(), EXIT_SUCCESS, srand(),
48
48
#include <stdbool.h> /* bool, false, true */
49
49
#include <string.h> /* memset(), strcmp(), strlen(),
50
50
strerror(), asprintf(), strcpy() */
71
71
INET_ADDRSTRLEN, INET6_ADDRSTRLEN
73
73
#include <unistd.h> /* close(), SEEK_SET, off_t, write(),
74
getuid(), getgid(), setuid(),
74
getuid(), getgid(), seteuid(),
76
76
#include <arpa/inet.h> /* inet_pton(), htons */
77
77
#include <iso646.h> /* not, or, and */
78
78
#include <argp.h> /* struct argp_option, error_t, struct
82
82
#include <signal.h> /* sigemptyset(), sigaddset(),
83
83
sigaction(), SIGTERM, sig_atomic_t,
85
#include <sysexits.h> /* EX_OSERR, EX_USAGE, EX_UNAVAILABLE,
86
EX_NOHOST, EX_IOERR, EX_PROTOCOL */
87
89
#include <sys/klog.h> /* klogctl() */
125
127
static const char mandos_protocol_version[] = "1";
126
128
const char *argp_program_version = "mandos-client " VERSION;
127
129
const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";
130
static const char sys_class_net[] = "/sys/class/net";
131
char *connect_to = NULL;
129
133
/* Used for passing in values through the Avahi callback functions */
142
146
.dh_bits = 1024, .priority = "SECURE256"
143
147
":!CTYPE-X.509:+CTYPE-OPENPGP" };
149
sig_atomic_t quit_now = 0;
150
int signal_received = 0;
146
153
* Make additional room in "buffer" for at least BUFFER_SIZE more
147
154
* bytes. "buffer_capacity" is how much is currently allocated,
474
481
static int init_gnutls_session(gnutls_session_t *session){
476
483
/* GnuTLS session creation */
477
ret = gnutls_init(session, GNUTLS_SERVER);
485
ret = gnutls_init(session, GNUTLS_SERVER);
489
} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);
478
490
if(ret != GNUTLS_E_SUCCESS){
479
491
fprintf(stderr, "Error in GnuTLS session initialization: %s\n",
480
492
safer_gnutls_strerror(ret));
485
ret = gnutls_priority_set_direct(*session, mc.priority, &err);
498
ret = gnutls_priority_set_direct(*session, mc.priority, &err);
500
gnutls_deinit(*session);
503
} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);
486
504
if(ret != GNUTLS_E_SUCCESS){
487
505
fprintf(stderr, "Syntax error at: %s\n", err);
488
506
fprintf(stderr, "GnuTLS error: %s\n",
495
ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,
514
ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,
517
gnutls_deinit(*session);
520
} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);
497
521
if(ret != GNUTLS_E_SUCCESS){
498
522
fprintf(stderr, "Error setting GnuTLS credentials: %s\n",
499
523
safer_gnutls_strerror(ret));
504
528
/* ignore client certificate if any. */
505
gnutls_certificate_server_set_request(*session,
529
gnutls_certificate_server_set_request(*session, GNUTLS_CERT_IGNORE);
508
531
gnutls_dh_set_prime_bits(*session, mc.dh_bits);
514
537
static void empty_log(__attribute__((unused)) AvahiLogLevel level,
515
538
__attribute__((unused)) const char *txt){}
517
sig_atomic_t quit_now = 0;
518
int signal_received = 0;
520
540
/* Called when a Mandos server is found */
521
541
static int start_mandos_communication(const char *ip, uint16_t port,
522
542
AvahiIfIndex if_index,
544
int ret, tcp_sd = -1;
527
547
struct sockaddr_in in;
528
548
struct sockaddr_in6 in6;
530
550
char *buffer = NULL;
531
char *decrypted_buffer;
551
char *decrypted_buffer = NULL;
532
552
size_t buffer_length = 0;
533
553
size_t buffer_capacity = 0;
534
ssize_t decrypted_buffer_size;
537
556
gnutls_session_t session;
538
557
int pf; /* Protocol family */
592
630
if(if_index == AVAHI_IF_UNSPEC){
593
631
fprintf(stderr, "An IPv6 link-local address is incomplete"
594
632
" without a network interface\n");
597
636
/* Set the network interface number as scope */
598
637
to.in6.sin6_scope_id = (uint32_t)if_index;
673
735
fprintf(stderr, "Establishing TLS session with %s\n", ip);
676
743
gnutls_transport_set_ptr(session, (gnutls_transport_ptr_t) tcp_sd);
679
751
ret = gnutls_handshake(session);
680
756
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
682
758
if(ret != GNUTLS_E_SUCCESS){
715
803
case GNUTLS_E_AGAIN:
717
805
case GNUTLS_E_REHANDSHAKE:
719
807
ret = gnutls_handshake(session);
720
813
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
722
815
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
723
816
gnutls_perror(ret);
729
822
fprintf(stderr, "Unknown error while reading data from"
730
823
" encrypted session with Mandos server\n");
732
824
gnutls_bye(session, GNUTLS_SHUT_RDWR);
741
834
fprintf(stderr, "Closing TLS session\n");
744
gnutls_bye(session, GNUTLS_SHUT_RDWR);
843
ret = gnutls_bye(session, GNUTLS_SHUT_RDWR);
848
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
746
850
if(buffer_length > 0){
851
ssize_t decrypted_buffer_size;
747
852
decrypted_buffer_size = pgp_packet_decrypt(buffer,
749
854
&decrypted_buffer);
750
855
if(decrypted_buffer_size >= 0){
752
858
while(written < (size_t) decrypted_buffer_size){
753
864
ret = (int)fwrite(decrypted_buffer + written, 1,
754
865
(size_t)decrypted_buffer_size - written,
756
867
if(ret == 0 and ferror(stdout)){
758
870
fprintf(stderr, "Error writing encrypted data: %s\n",
759
871
strerror(errno));
764
876
written += (size_t)ret;
766
free(decrypted_buffer);
774
882
/* Shutdown procedure */
778
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
887
free(decrypted_buffer);
890
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
898
gnutls_deinit(session);
782
gnutls_deinit(session);
896
1022
errno = old_errno;
1026
* This function determines if a directory entry in /sys/class/net
1027
* corresponds to an acceptable network device.
1028
* (This function is passed to scandir(3) as a filter function.)
1030
int good_interface(const struct dirent *if_entry){
1032
char *flagname = NULL;
1033
int ret = asprintf(&flagname, "%s/%s/flags", sys_class_net,
1039
if(if_entry->d_name[0] == '.'){
1042
int flags_fd = (int)TEMP_FAILURE_RETRY(open(flagname, O_RDONLY));
1047
typedef short ifreq_flags; /* ifreq.ifr_flags in netdevice(7) */
1048
/* read line from flags_fd */
1049
ssize_t to_read = (sizeof(ifreq_flags)*2)+3; /* "0x1003\n" */
1050
char *flagstring = malloc((size_t)to_read+1); /* +1 for final \0 */
1051
flagstring[(size_t)to_read] = '\0';
1052
if(flagstring == NULL){
1058
ssret = (ssize_t)TEMP_FAILURE_RETRY(read(flags_fd, flagstring,
1075
tmpmax = strtoimax(flagstring, &tmp, 0);
1076
if(errno != 0 or tmp == flagstring or (*tmp != '\0'
1077
and not (isspace(*tmp)))
1078
or tmpmax != (ifreq_flags)tmpmax){
1080
fprintf(stderr, "Invalid flags \"%s\" for interface \"%s\"\n",
1081
flagstring, if_entry->d_name);
1087
ifreq_flags flags = (ifreq_flags)tmpmax;
1088
/* Reject the loopback device */
1089
if(flags & IFF_LOOPBACK){
1091
fprintf(stderr, "Rejecting loopback interface \"%s\"\n",
1096
/* Accept point-to-point devices only if connect_to is specified */
1097
if(connect_to != NULL and (flags & IFF_POINTOPOINT)){
1099
fprintf(stderr, "Accepting point-to-point interface \"%s\"\n",
1104
/* Otherwise, reject non-broadcast-capable devices */
1105
if(not (flags & IFF_BROADCAST)){
1107
fprintf(stderr, "Rejecting non-broadcast interface \"%s\"\n",
1112
/* Accept this device */
1114
fprintf(stderr, "Interface \"%s\" is acceptable\n",
899
1120
int main(int argc, char *argv[]){
900
1121
AvahiSServiceBrowser *sb = NULL;
903
1124
intmax_t tmpmax;
905
1126
int exitcode = EXIT_SUCCESS;
906
const char *interface = "eth0";
1127
const char *interface = "";
907
1128
struct ifreq network;
909
1130
bool take_down_interface = false;
912
char *connect_to = NULL;
913
1133
char tempdir[] = "/tmp/mandosXXXXXX";
914
1134
bool tempdir_created = false;
915
1135
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
920
1140
bool gpgme_initialized = false;
921
1141
float delay = 2.5f;
923
struct sigaction old_sigterm_action;
1143
struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
924
1144
struct sigaction sigterm_action = { .sa_handler = handle_sigterm };
1149
/* Lower any group privileges we might have, just to be safe */
1156
/* Lower user privileges (temporarily) */
927
1168
struct argp_option options[] = {
928
1169
{ .name = "debug", .key = 128,
957
1198
.arg = "SECONDS",
958
1199
.doc = "Maximum delay to wait for interface startup",
1202
* These reproduce what we would get without ARGP_NO_HELP
1204
{ .name = "help", .key = '?',
1205
.doc = "Give this help list", .group = -1 },
1206
{ .name = "usage", .key = -3,
1207
.doc = "Give a short usage message", .group = -1 },
1208
{ .name = "version", .key = 'V',
1209
.doc = "Print program version", .group = -1 },
960
1210
{ .name = NULL }
963
1213
error_t parse_opt(int key, char *arg,
964
1214
struct argp_state *state){
966
1217
case 128: /* --debug */
983
1234
tmpmax = strtoimax(arg, &tmp, 10);
984
1235
if(errno != 0 or tmp == arg or *tmp != '\0'
985
1236
or tmpmax != (typeof(mc.dh_bits))tmpmax){
986
fprintf(stderr, "Bad number of DH bits\n");
1237
argp_error(state, "Bad number of DH bits");
989
1239
mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
996
1246
delay = strtof(arg, &tmp);
997
1247
if(errno != 0 or tmp == arg or *tmp != '\0'){
998
fprintf(stderr, "Bad delay\n");
1248
argp_error(state, "Bad delay");
1252
* These reproduce what we would get without ARGP_NO_HELP
1254
case '?': /* --help */
1255
argp_state_help(state, state->out_stream,
1256
(ARGP_HELP_STD_HELP | ARGP_HELP_EXIT_ERR)
1257
& ~(unsigned int)ARGP_HELP_EXIT_OK);
1258
case -3: /* --usage */
1259
argp_state_help(state, state->out_stream,
1260
ARGP_HELP_USAGE | ARGP_HELP_EXIT_ERR);
1261
case 'V': /* --version */
1262
fprintf(state->out_stream, "%s\n", argp_program_version);
1263
exit(argp_err_exit_status);
1007
1266
return ARGP_ERR_UNKNOWN;
1012
1271
struct argp argp = { .options = options, .parser = parse_opt,
1013
1272
.args_doc = "",
1014
1273
.doc = "Mandos client -- Get and decrypt"
1015
1274
" passwords from a Mandos server" };
1016
ret = argp_parse(&argp, argc, argv, 0, 0, NULL);
1017
if(ret == ARGP_ERR_UNKNOWN){
1018
fprintf(stderr, "Unknown error while parsing arguments\n");
1019
exitcode = EXIT_FAILURE;
1275
ret = argp_parse(&argp, argc, argv,
1276
ARGP_IN_ORDER | ARGP_NO_HELP, 0, NULL);
1283
perror("argp_parse");
1284
exitcode = EX_OSERR;
1287
exitcode = EX_USAGE;
1025
1293
avahi_set_log_function(empty_log);
1296
if(interface[0] == '\0'){
1297
struct dirent **direntries;
1298
ret = scandir(sys_class_net, &direntries, good_interface,
1301
/* Pick the first good interface */
1302
interface = strdup(direntries[0]->d_name);
1304
fprintf(stderr, "Using interface \"%s\"\n", interface);
1306
if(interface == NULL){
1309
exitcode = EXIT_FAILURE;
1315
fprintf(stderr, "Could not find a network interface\n");
1316
exitcode = EXIT_FAILURE;
1028
1321
/* Initialize Avahi early so avahi_simple_poll_quit() can be called
1029
1322
from the signal handler */
1040
1333
ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
1042
1335
perror("sigaddset");
1043
exitcode = EXIT_FAILURE;
1336
exitcode = EX_OSERR;
1046
1339
ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
1048
1341
perror("sigaddset");
1049
exitcode = EXIT_FAILURE;
1342
exitcode = EX_OSERR;
1052
1345
ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
1054
1347
perror("sigaddset");
1055
exitcode = EXIT_FAILURE;
1058
ret = sigaction(SIGINT, &sigterm_action, &old_sigterm_action);
1060
perror("sigaction");
1061
exitcode = EXIT_FAILURE;
1064
ret = sigaction(SIGHUP, &sigterm_action, NULL);
1066
perror("sigaction");
1067
exitcode = EXIT_FAILURE;
1070
ret = sigaction(SIGTERM, &sigterm_action, NULL);
1072
perror("sigaction");
1073
exitcode = EXIT_FAILURE;
1348
exitcode = EX_OSERR;
1351
/* Need to check if the handler is SIG_IGN before handling:
1352
| [[info:libc:Initial Signal Actions]] |
1353
| [[info:libc:Basic Signal Handling]] |
1355
ret = sigaction(SIGINT, NULL, &old_sigterm_action);
1357
perror("sigaction");
1360
if(old_sigterm_action.sa_handler != SIG_IGN){
1361
ret = sigaction(SIGINT, &sigterm_action, NULL);
1363
perror("sigaction");
1364
exitcode = EX_OSERR;
1368
ret = sigaction(SIGHUP, NULL, &old_sigterm_action);
1370
perror("sigaction");
1373
if(old_sigterm_action.sa_handler != SIG_IGN){
1374
ret = sigaction(SIGHUP, &sigterm_action, NULL);
1376
perror("sigaction");
1377
exitcode = EX_OSERR;
1381
ret = sigaction(SIGTERM, NULL, &old_sigterm_action);
1383
perror("sigaction");
1386
if(old_sigterm_action.sa_handler != SIG_IGN){
1387
ret = sigaction(SIGTERM, &sigterm_action, NULL);
1389
perror("sigaction");
1390
exitcode = EX_OSERR;
1077
1395
/* If the interface is down, bring it up */
1078
if(interface[0] != '\0'){
1396
if(strcmp(interface, "none") != 0){
1079
1397
if_index = (AvahiIfIndex) if_nametoindex(interface);
1080
1398
if(if_index == 0){
1081
1399
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1082
exitcode = EXIT_FAILURE;
1400
exitcode = EX_UNAVAILABLE;
1408
/* Re-raise priviliges */
1090
1415
#ifdef __linux__
1091
1416
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1092
messages to mess up the prompt */
1417
messages about the network interface to mess up the prompt */
1093
1418
ret = klogctl(8, NULL, 5);
1094
1419
bool restore_loglevel = true;
1133
1470
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1135
1472
take_down_interface = false;
1136
perror("ioctl SIOCSIFFLAGS");
1137
exitcode = EXIT_FAILURE;
1473
perror("ioctl SIOCSIFFLAGS +IFF_UP");
1474
exitcode = EX_OSERR;
1138
1475
#ifdef __linux__
1139
1476
if(restore_loglevel){
1140
1477
ret = klogctl(7, NULL, 0);
1227
1567
if(not init_gpgme(pubkey, seckey, tempdir)){
1228
1568
fprintf(stderr, "init_gpgme failed\n");
1229
exitcode = EXIT_FAILURE;
1569
exitcode = EX_UNAVAILABLE;
1232
1572
gpgme_initialized = true;
1374
1732
/* Take down the network interface */
1375
1733
if(take_down_interface){
1376
ret = ioctl(sd, SIOCGIFFLAGS, &network);
1734
/* Re-raise priviliges */
1378
perror("ioctl SIOCGIFFLAGS");
1379
} else if(network.ifr_flags & IFF_UP) {
1380
network.ifr_flags &= ~IFF_UP; /* clear flag */
1381
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1383
perror("ioctl SIOCSIFFLAGS");
1386
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1741
ret = ioctl(sd, SIOCGIFFLAGS, &network);
1743
perror("ioctl SIOCGIFFLAGS");
1744
} else if(network.ifr_flags & IFF_UP) {
1745
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1746
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1748
perror("ioctl SIOCSIFFLAGS -IFF_UP");
1751
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1755
/* Lower privileges permanently */
1437
ret = sigaction(signal_received, &old_sigterm_action, NULL);
1809
sigemptyset(&old_sigterm_action.sa_mask);
1810
old_sigterm_action.sa_handler = SIG_DFL;
1811
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
1812
&old_sigterm_action,
1439
1815
perror("sigaction");
1441
raise(signal_received);
1818
ret = raise(signal_received);
1819
} while(ret != 0 and errno == EINTR);
1824
TEMP_FAILURE_RETRY(pause());
1444
1827
return exitcode;