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() */
64
64
#include <assert.h> /* assert() */
65
65
#include <errno.h> /* perror(), errno */
66
#include <time.h> /* nanosleep(), time() */
66
#include <time.h> /* nanosleep(), time(), sleep() */
67
67
#include <net/if.h> /* ioctl, ifreq, SIOCGIFFLAGS, IFF_UP,
68
68
SIOCSIFFLAGS, if_indextoname(),
69
69
if_nametoindex(), IF_NAMESIZE */
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,
767
809
ret = gnutls_handshake(session);
772
815
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
774
817
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
775
818
gnutls_perror(ret);
781
824
fprintf(stderr, "Unknown error while reading data from"
782
825
" encrypted session with Mandos server\n");
784
826
gnutls_bye(session, GNUTLS_SHUT_RDWR);
800
gnutls_bye(session, GNUTLS_SHUT_RDWR);
845
ret = gnutls_bye(session, GNUTLS_SHUT_RDWR);
850
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
806
852
if(buffer_length > 0){
807
853
ssize_t decrypted_buffer_size;
820
867
(size_t)decrypted_buffer_size - written,
822
869
if(ret == 0 and ferror(stdout)){
824
872
fprintf(stderr, "Error writing encrypted data: %s\n",
825
873
strerror(errno));
830
878
written += (size_t)ret;
832
free(decrypted_buffer);
840
884
/* Shutdown procedure */
845
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
850
gnutls_deinit(session);
889
free(decrypted_buffer);
892
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
900
gnutls_deinit(session);
971
1024
errno = old_errno;
1028
* This function determines if a directory entry in /sys/class/net
1029
* corresponds to an acceptable network device.
1030
* (This function is passed to scandir(3) as a filter function.)
1032
int good_interface(const struct dirent *if_entry){
1034
char *flagname = NULL;
1035
int ret = asprintf(&flagname, "%s/%s/flags", sys_class_net,
1041
if(if_entry->d_name[0] == '.'){
1044
int flags_fd = (int)TEMP_FAILURE_RETRY(open(flagname, O_RDONLY));
1049
typedef short ifreq_flags; /* ifreq.ifr_flags in netdevice(7) */
1050
/* read line from flags_fd */
1051
ssize_t to_read = (sizeof(ifreq_flags)*2)+3; /* "0x1003\n" */
1052
char *flagstring = malloc((size_t)to_read+1); /* +1 for final \0 */
1053
flagstring[(size_t)to_read] = '\0';
1054
if(flagstring == NULL){
1060
ssret = (ssize_t)TEMP_FAILURE_RETRY(read(flags_fd, flagstring,
1077
tmpmax = strtoimax(flagstring, &tmp, 0);
1078
if(errno != 0 or tmp == flagstring or (*tmp != '\0'
1079
and not (isspace(*tmp)))
1080
or tmpmax != (ifreq_flags)tmpmax){
1082
fprintf(stderr, "Invalid flags \"%s\" for interface \"%s\"\n",
1083
flagstring, if_entry->d_name);
1089
ifreq_flags flags = (ifreq_flags)tmpmax;
1090
/* Reject the loopback device */
1091
if(flags & IFF_LOOPBACK){
1093
fprintf(stderr, "Rejecting loopback interface \"%s\"\n",
1098
/* Accept point-to-point devices only if connect_to is specified */
1099
if(connect_to != NULL and (flags & IFF_POINTOPOINT)){
1101
fprintf(stderr, "Accepting point-to-point interface \"%s\"\n",
1106
/* Otherwise, reject non-broadcast-capable devices */
1107
if(not (flags & IFF_BROADCAST)){
1109
fprintf(stderr, "Rejecting non-broadcast interface \"%s\"\n",
1114
/* Accept this device */
1116
fprintf(stderr, "Interface \"%s\" is acceptable\n",
974
1122
int main(int argc, char *argv[]){
975
1123
AvahiSServiceBrowser *sb = NULL;
978
1126
intmax_t tmpmax;
980
1128
int exitcode = EXIT_SUCCESS;
981
const char *interface = "eth0";
1129
const char *interface = "";
982
1130
struct ifreq network;
984
1132
bool take_down_interface = false;
987
char *connect_to = NULL;
988
1135
char tempdir[] = "/tmp/mandosXXXXXX";
989
1136
bool tempdir_created = false;
990
1137
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
995
1142
bool gpgme_initialized = false;
996
1143
float delay = 2.5f;
998
struct sigaction old_sigterm_action;
1145
struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
999
1146
struct sigaction sigterm_action = { .sa_handler = handle_sigterm };
1151
/* Lower any group privileges we might have, just to be safe */
1158
/* Lower user privileges (temporarily) */
1002
1170
struct argp_option options[] = {
1003
1171
{ .name = "debug", .key = 128,
1032
1200
.arg = "SECONDS",
1033
1201
.doc = "Maximum delay to wait for interface startup",
1204
* These reproduce what we would get without ARGP_NO_HELP
1206
{ .name = "help", .key = '?',
1207
.doc = "Give this help list", .group = -1 },
1208
{ .name = "usage", .key = -3,
1209
.doc = "Give a short usage message", .group = -1 },
1210
{ .name = "version", .key = 'V',
1211
.doc = "Print program version", .group = -1 },
1035
1212
{ .name = NULL }
1038
1215
error_t parse_opt(int key, char *arg,
1039
1216
struct argp_state *state){
1041
1219
case 128: /* --debug */
1058
1236
tmpmax = strtoimax(arg, &tmp, 10);
1059
1237
if(errno != 0 or tmp == arg or *tmp != '\0'
1060
1238
or tmpmax != (typeof(mc.dh_bits))tmpmax){
1061
fprintf(stderr, "Bad number of DH bits\n");
1239
argp_error(state, "Bad number of DH bits");
1064
1241
mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
1071
1248
delay = strtof(arg, &tmp);
1072
1249
if(errno != 0 or tmp == arg or *tmp != '\0'){
1073
fprintf(stderr, "Bad delay\n");
1250
argp_error(state, "Bad delay");
1254
* These reproduce what we would get without ARGP_NO_HELP
1256
case '?': /* --help */
1257
argp_state_help(state, state->out_stream,
1258
(ARGP_HELP_STD_HELP | ARGP_HELP_EXIT_ERR)
1259
& ~(unsigned int)ARGP_HELP_EXIT_OK);
1260
case -3: /* --usage */
1261
argp_state_help(state, state->out_stream,
1262
ARGP_HELP_USAGE | ARGP_HELP_EXIT_ERR);
1263
case 'V': /* --version */
1264
fprintf(state->out_stream, "%s\n", argp_program_version);
1265
exit(argp_err_exit_status);
1082
1268
return ARGP_ERR_UNKNOWN;
1087
1273
struct argp argp = { .options = options, .parser = parse_opt,
1088
1274
.args_doc = "",
1089
1275
.doc = "Mandos client -- Get and decrypt"
1090
1276
" passwords from a Mandos server" };
1091
ret = argp_parse(&argp, argc, argv, 0, 0, NULL);
1092
if(ret == ARGP_ERR_UNKNOWN){
1093
fprintf(stderr, "Unknown error while parsing arguments\n");
1094
exitcode = EXIT_FAILURE;
1277
ret = argp_parse(&argp, argc, argv,
1278
ARGP_IN_ORDER | ARGP_NO_HELP, 0, NULL);
1285
perror("argp_parse");
1286
exitcode = EX_OSERR;
1289
exitcode = EX_USAGE;
1100
1295
avahi_set_log_function(empty_log);
1298
if(interface[0] == '\0'){
1299
struct dirent **direntries;
1300
ret = scandir(sys_class_net, &direntries, good_interface,
1303
/* Pick the first good interface */
1304
interface = strdup(direntries[0]->d_name);
1306
fprintf(stderr, "Using interface \"%s\"\n", interface);
1308
if(interface == NULL){
1311
exitcode = EXIT_FAILURE;
1317
fprintf(stderr, "Could not find a network interface\n");
1318
exitcode = EXIT_FAILURE;
1103
1323
/* Initialize Avahi early so avahi_simple_poll_quit() can be called
1104
1324
from the signal handler */
1115
1335
ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
1117
1337
perror("sigaddset");
1118
exitcode = EXIT_FAILURE;
1338
exitcode = EX_OSERR;
1121
1341
ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
1123
1343
perror("sigaddset");
1124
exitcode = EXIT_FAILURE;
1344
exitcode = EX_OSERR;
1127
1347
ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
1129
1349
perror("sigaddset");
1130
exitcode = EXIT_FAILURE;
1350
exitcode = EX_OSERR;
1133
1353
/* Need to check if the handler is SIG_IGN before handling:
1137
1357
ret = sigaction(SIGINT, NULL, &old_sigterm_action);
1139
1359
perror("sigaction");
1140
return EXIT_FAILURE;
1142
1362
if(old_sigterm_action.sa_handler != SIG_IGN){
1143
1363
ret = sigaction(SIGINT, &sigterm_action, NULL);
1145
1365
perror("sigaction");
1146
exitcode = EXIT_FAILURE;
1366
exitcode = EX_OSERR;
1150
1370
ret = sigaction(SIGHUP, NULL, &old_sigterm_action);
1152
1372
perror("sigaction");
1153
return EXIT_FAILURE;
1155
1375
if(old_sigterm_action.sa_handler != SIG_IGN){
1156
1376
ret = sigaction(SIGHUP, &sigterm_action, NULL);
1158
1378
perror("sigaction");
1159
exitcode = EXIT_FAILURE;
1379
exitcode = EX_OSERR;
1163
1383
ret = sigaction(SIGTERM, NULL, &old_sigterm_action);
1165
1385
perror("sigaction");
1166
return EXIT_FAILURE;
1168
1388
if(old_sigterm_action.sa_handler != SIG_IGN){
1169
1389
ret = sigaction(SIGTERM, &sigterm_action, NULL);
1171
1391
perror("sigaction");
1172
exitcode = EXIT_FAILURE;
1392
exitcode = EX_OSERR;
1177
1397
/* If the interface is down, bring it up */
1178
if(interface[0] != '\0'){
1398
if(strcmp(interface, "none") != 0){
1179
1399
if_index = (AvahiIfIndex) if_nametoindex(interface);
1180
1400
if(if_index == 0){
1181
1401
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1182
exitcode = EXIT_FAILURE;
1402
exitcode = EX_UNAVAILABLE;
1410
/* Re-raise priviliges */
1190
1417
#ifdef __linux__
1191
1418
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1192
messages to mess up the prompt */
1419
messages about the network interface to mess up the prompt */
1193
1420
ret = klogctl(8, NULL, 5);
1194
1421
bool restore_loglevel = true;
1233
1472
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1235
1474
take_down_interface = false;
1236
perror("ioctl SIOCSIFFLAGS");
1237
exitcode = EXIT_FAILURE;
1475
perror("ioctl SIOCSIFFLAGS +IFF_UP");
1476
exitcode = EX_OSERR;
1238
1477
#ifdef __linux__
1239
1478
if(restore_loglevel){
1240
1479
ret = klogctl(7, NULL, 0);
1327
1569
if(not init_gpgme(pubkey, seckey, tempdir)){
1328
1570
fprintf(stderr, "init_gpgme failed\n");
1329
exitcode = EXIT_FAILURE;
1571
exitcode = EX_UNAVAILABLE;
1332
1574
gpgme_initialized = true;
1382
ret = start_mandos_communication(address, port, if_index, af);
1384
exitcode = EXIT_FAILURE;
1624
while(not quit_now){
1625
ret = start_mandos_communication(address, port, if_index, af);
1626
if(quit_now or ret == 0){
1386
1633
exitcode = EXIT_SUCCESS;
1474
1722
/* Take down the network interface */
1475
1723
if(take_down_interface){
1476
ret = ioctl(sd, SIOCGIFFLAGS, &network);
1724
/* Re-raise priviliges */
1478
perror("ioctl SIOCGIFFLAGS");
1479
} else if(network.ifr_flags & IFF_UP) {
1480
network.ifr_flags &= ~IFF_UP; /* clear flag */
1481
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1483
perror("ioctl SIOCSIFFLAGS");
1486
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1731
ret = ioctl(sd, SIOCGIFFLAGS, &network);
1733
perror("ioctl SIOCGIFFLAGS");
1734
} else if(network.ifr_flags & IFF_UP) {
1735
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1736
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1738
perror("ioctl SIOCSIFFLAGS -IFF_UP");
1741
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1745
/* Lower privileges permanently */
1537
1799
sigemptyset(&old_sigterm_action.sa_mask);
1538
1800
old_sigterm_action.sa_handler = SIG_DFL;
1539
ret = sigaction(signal_received, &old_sigterm_action, NULL);
1801
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
1802
&old_sigterm_action,
1541
1805
perror("sigaction");
1543
raise(signal_received);
1808
ret = raise(signal_received);
1809
} while(ret != 0 and errno == EINTR);
1814
TEMP_FAILURE_RETRY(pause());
1546
1817
return exitcode;