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
80
80
argp_parse(), ARGP_KEY_ARG,
81
81
ARGP_KEY_END, ARGP_ERR_UNKNOWN */
82
82
#include <signal.h> /* sigemptyset(), sigaddset(),
83
sigaction(), SIGTERM, sigaction,
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);
518
541
static int start_mandos_communication(const char *ip, uint16_t port,
519
542
AvahiIfIndex if_index,
544
int ret, tcp_sd = -1;
524
547
struct sockaddr_in in;
525
548
struct sockaddr_in6 in6;
527
550
char *buffer = NULL;
528
char *decrypted_buffer;
551
char *decrypted_buffer = NULL;
529
552
size_t buffer_length = 0;
530
553
size_t buffer_capacity = 0;
531
ssize_t decrypted_buffer_size;
534
556
gnutls_session_t session;
535
557
int pf; /* Protocol family */
589
630
if(if_index == AVAHI_IF_UNSPEC){
590
631
fprintf(stderr, "An IPv6 link-local address is incomplete"
591
632
" without a network interface\n");
594
636
/* Set the network interface number as scope */
595
637
to.in6.sin6_scope_id = (uint32_t)if_index;
670
735
fprintf(stderr, "Establishing TLS session with %s\n", ip);
673
743
gnutls_transport_set_ptr(session, (gnutls_transport_ptr_t) tcp_sd);
676
751
ret = gnutls_handshake(session);
677
756
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
679
758
if(ret != GNUTLS_E_SUCCESS){
712
803
case GNUTLS_E_AGAIN:
714
805
case GNUTLS_E_REHANDSHAKE:
716
807
ret = gnutls_handshake(session);
717
813
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
719
815
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
720
816
gnutls_perror(ret);
726
822
fprintf(stderr, "Unknown error while reading data from"
727
823
" encrypted session with Mandos server\n");
729
824
gnutls_bye(session, GNUTLS_SHUT_RDWR);
738
834
fprintf(stderr, "Closing TLS session\n");
741
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);
743
850
if(buffer_length > 0){
851
ssize_t decrypted_buffer_size;
744
852
decrypted_buffer_size = pgp_packet_decrypt(buffer,
746
854
&decrypted_buffer);
747
855
if(decrypted_buffer_size >= 0){
749
858
while(written < (size_t) decrypted_buffer_size){
750
864
ret = (int)fwrite(decrypted_buffer + written, 1,
751
865
(size_t)decrypted_buffer_size - written,
753
867
if(ret == 0 and ferror(stdout)){
755
870
fprintf(stderr, "Error writing encrypted data: %s\n",
756
871
strerror(errno));
761
876
written += (size_t)ret;
763
free(decrypted_buffer);
771
882
/* Shutdown procedure */
775
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);
779
gnutls_deinit(session);
878
sig_atomic_t quit_now = 0;
880
1011
/* stop main loop after sigterm has been called */
881
static void handle_sigterm(__attribute__((unused)) int sig){
1012
static void handle_sigterm(int sig){
1017
signal_received = sig;
886
1018
int old_errno = errno;
887
1019
if(mc.simple_poll != NULL){
888
1020
avahi_simple_poll_quit(mc.simple_poll);
890
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",
893
1120
int main(int argc, char *argv[]){
894
1121
AvahiSServiceBrowser *sb = NULL;
897
1124
intmax_t tmpmax;
899
1126
int exitcode = EXIT_SUCCESS;
900
const char *interface = "eth0";
1127
const char *interface = "";
901
1128
struct ifreq network;
1130
bool take_down_interface = false;
905
char *connect_to = NULL;
906
1133
char tempdir[] = "/tmp/mandosXXXXXX";
907
1134
bool tempdir_created = false;
908
1135
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
913
1140
bool gpgme_initialized = false;
914
1141
float delay = 2.5f;
916
struct sigaction old_sigterm_action;
1143
struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
917
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) */
920
1168
struct argp_option options[] = {
921
1169
{ .name = "debug", .key = 128,
950
1198
.arg = "SECONDS",
951
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 },
953
1210
{ .name = NULL }
956
1213
error_t parse_opt(int key, char *arg,
957
1214
struct argp_state *state){
959
1217
case 128: /* --debug */
976
1234
tmpmax = strtoimax(arg, &tmp, 10);
977
1235
if(errno != 0 or tmp == arg or *tmp != '\0'
978
1236
or tmpmax != (typeof(mc.dh_bits))tmpmax){
979
fprintf(stderr, "Bad number of DH bits\n");
1237
argp_error(state, "Bad number of DH bits");
982
1239
mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
989
1246
delay = strtof(arg, &tmp);
990
1247
if(errno != 0 or tmp == arg or *tmp != '\0'){
991
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);
1000
1266
return ARGP_ERR_UNKNOWN;
1005
1271
struct argp argp = { .options = options, .parser = parse_opt,
1006
1272
.args_doc = "",
1007
1273
.doc = "Mandos client -- Get and decrypt"
1008
1274
" passwords from a Mandos server" };
1009
ret = argp_parse(&argp, argc, argv, 0, 0, NULL);
1010
if(ret == ARGP_ERR_UNKNOWN){
1011
fprintf(stderr, "Unknown error while parsing arguments\n");
1012
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;
1018
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;
1021
1321
/* Initialize Avahi early so avahi_simple_poll_quit() can be called
1022
1322
from the signal handler */
1033
1333
ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
1035
1335
perror("sigaddset");
1036
exitcode = EXIT_FAILURE;
1336
exitcode = EX_OSERR;
1039
1339
ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
1041
1341
perror("sigaddset");
1042
exitcode = EXIT_FAILURE;
1342
exitcode = EX_OSERR;
1045
1345
ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
1047
1347
perror("sigaddset");
1048
exitcode = EXIT_FAILURE;
1051
ret = sigaction(SIGTERM, &sigterm_action, &old_sigterm_action);
1053
perror("sigaction");
1054
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;
1058
1395
/* If the interface is down, bring it up */
1059
if(interface[0] != '\0'){
1396
if(strcmp(interface, "none") != 0){
1397
if_index = (AvahiIfIndex) if_nametoindex(interface);
1399
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1400
exitcode = EX_UNAVAILABLE;
1408
/* Re-raise priviliges */
1060
1415
#ifdef __linux__
1061
1416
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1062
messages to mess up the prompt */
1417
messages about the network interface to mess up the prompt */
1063
1418
ret = klogctl(8, NULL, 5);
1064
1419
bool restore_loglevel = true;
1096
1457
#endif /* __linux__ */
1097
exitcode = EXIT_FAILURE;
1458
exitcode = EX_OSERR;
1459
/* Lower privileges */
1100
1467
if((network.ifr_flags & IFF_UP) == 0){
1101
1468
network.ifr_flags |= IFF_UP;
1469
take_down_interface = true;
1102
1470
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1104
perror("ioctl SIOCSIFFLAGS");
1105
exitcode = EXIT_FAILURE;
1472
take_down_interface = false;
1473
perror("ioctl SIOCSIFFLAGS +IFF_UP");
1474
exitcode = EX_OSERR;
1106
1475
#ifdef __linux__
1107
1476
if(restore_loglevel){
1108
1477
ret = klogctl(7, NULL, 0);
1143
1521
#endif /* __linux__ */
1522
/* Lower privileges */
1524
if(take_down_interface){
1525
/* Lower privileges */
1531
/* Lower privileges permanently */
1160
1543
ret = init_gnutls_global(pubkey, seckey);
1162
1545
fprintf(stderr, "init_gnutls_global failed\n");
1163
exitcode = EXIT_FAILURE;
1546
exitcode = EX_UNAVAILABLE;
1166
1549
gnutls_initialized = true;
1556
tempdir_created = true;
1169
1557
if(mkdtemp(tempdir) == NULL){
1558
tempdir_created = false;
1170
1559
perror("mkdtemp");
1173
tempdir_created = true;
1175
1567
if(not init_gpgme(pubkey, seckey, tempdir)){
1176
1568
fprintf(stderr, "init_gpgme failed\n");
1177
exitcode = EXIT_FAILURE;
1569
exitcode = EX_UNAVAILABLE;
1180
1572
gpgme_initialized = true;
1183
if(interface[0] != '\0'){
1184
if_index = (AvahiIfIndex) if_nametoindex(interface);
1186
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1187
exitcode = EXIT_FAILURE;
1192
1579
if(connect_to != NULL){
1195
1582
char *address = strrchr(connect_to, ':');
1196
1583
if(address == NULL){
1197
1584
fprintf(stderr, "No colon in address\n");
1198
exitcode = EXIT_FAILURE;
1585
exitcode = EX_USAGE;
1203
1595
tmpmax = strtoimax(address+1, &tmp, 10);
1204
1596
if(errno != 0 or tmp == address+1 or *tmp != '\0'
1205
1597
or tmpmax != (uint16_t)tmpmax){
1206
1598
fprintf(stderr, "Bad port number\n");
1207
exitcode = EXIT_FAILURE;
1599
exitcode = EX_USAGE;
1210
1607
port = (uint16_t)tmpmax;
1211
1608
*address = '\0';
1212
1609
address = connect_to;
1297
1729
gpgme_release(mc.ctx);
1732
/* Take down the network interface */
1733
if(take_down_interface){
1734
/* Re-raise priviliges */
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 */
1300
1764
/* Removes the temp directory used by GPGME */
1301
1765
if(tempdir_created){
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,
1815
perror("sigaction");
1818
ret = raise(signal_received);
1819
} while(ret != 0 and errno == EINTR);
1824
TEMP_FAILURE_RETRY(pause());
1344
1827
return exitcode;