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, srand(),
46
#include <stdlib.h> /* free(), EXIT_SUCCESS, EXIT_FAILURE,
48
48
#include <stdbool.h> /* bool, false, true */
49
49
#include <string.h> /* memset(), strcmp(), strlen(),
50
50
strerror(), asprintf(), strcpy() */
73
73
#include <unistd.h> /* close(), SEEK_SET, off_t, write(),
74
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 */
89
87
#include <sys/klog.h> /* klogctl() */
127
125
static const char mandos_protocol_version[] = "1";
128
126
const char *argp_program_version = "mandos-client " VERSION;
129
127
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;
133
129
/* Used for passing in values through the Avahi callback functions */
146
142
.dh_bits = 1024, .priority = "SECURE256"
147
143
":!CTYPE-X.509:+CTYPE-OPENPGP" };
149
sig_atomic_t quit_now = 0;
150
int signal_received = 0;
153
146
* Make additional room in "buffer" for at least BUFFER_SIZE more
154
147
* bytes. "buffer_capacity" is how much is currently allocated,
481
474
static int init_gnutls_session(gnutls_session_t *session){
483
476
/* GnuTLS session creation */
485
ret = gnutls_init(session, GNUTLS_SERVER);
489
} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);
477
ret = gnutls_init(session, GNUTLS_SERVER);
490
478
if(ret != GNUTLS_E_SUCCESS){
491
479
fprintf(stderr, "Error in GnuTLS session initialization: %s\n",
492
480
safer_gnutls_strerror(ret));
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);
485
ret = gnutls_priority_set_direct(*session, mc.priority, &err);
504
486
if(ret != GNUTLS_E_SUCCESS){
505
487
fprintf(stderr, "Syntax error at: %s\n", err);
506
488
fprintf(stderr, "GnuTLS error: %s\n",
514
ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,
517
gnutls_deinit(*session);
520
} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);
495
ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,
521
497
if(ret != GNUTLS_E_SUCCESS){
522
498
fprintf(stderr, "Error setting GnuTLS credentials: %s\n",
523
499
safer_gnutls_strerror(ret));
528
504
/* ignore client certificate if any. */
529
gnutls_certificate_server_set_request(*session, GNUTLS_CERT_IGNORE);
505
gnutls_certificate_server_set_request(*session,
531
508
gnutls_dh_set_prime_bits(*session, mc.dh_bits);
537
514
static void empty_log(__attribute__((unused)) AvahiLogLevel level,
538
515
__attribute__((unused)) const char *txt){}
517
sig_atomic_t quit_now = 0;
518
int signal_received = 0;
540
520
/* Called when a Mandos server is found */
541
521
static int start_mandos_communication(const char *ip, uint16_t port,
542
522
AvahiIfIndex if_index,
807
767
ret = gnutls_handshake(session);
813
772
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
815
774
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
816
775
gnutls_perror(ret);
822
781
fprintf(stderr, "Unknown error while reading data from"
823
782
" encrypted session with Mandos server\n");
824
784
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);
800
gnutls_bye(session, GNUTLS_SHUT_RDWR);
850
806
if(buffer_length > 0){
851
807
ssize_t decrypted_buffer_size;
865
820
(size_t)decrypted_buffer_size - written,
867
822
if(ret == 0 and ferror(stdout)){
870
824
fprintf(stderr, "Error writing encrypted data: %s\n",
871
825
strerror(errno));
876
830
written += (size_t)ret;
832
free(decrypted_buffer);
882
840
/* Shutdown procedure */
887
free(decrypted_buffer);
890
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
898
gnutls_deinit(session);
845
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
850
gnutls_deinit(session);
1022
971
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",
1120
974
int main(int argc, char *argv[]){
1121
975
AvahiSServiceBrowser *sb = NULL;
1124
978
intmax_t tmpmax;
1126
980
int exitcode = EXIT_SUCCESS;
1127
const char *interface = "";
981
const char *interface = "eth0";
1128
982
struct ifreq network;
1130
984
bool take_down_interface = false;
987
char *connect_to = NULL;
1133
988
char tempdir[] = "/tmp/mandosXXXXXX";
1134
989
bool tempdir_created = false;
1135
990
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
1140
995
bool gpgme_initialized = false;
1141
996
float delay = 2.5f;
1143
struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
998
struct sigaction old_sigterm_action;
1144
999
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) */
1168
1002
struct argp_option options[] = {
1169
1003
{ .name = "debug", .key = 128,
1198
1032
.arg = "SECONDS",
1199
1033
.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 },
1210
1035
{ .name = NULL }
1213
1038
error_t parse_opt(int key, char *arg,
1214
1039
struct argp_state *state){
1217
1041
case 128: /* --debug */
1234
1058
tmpmax = strtoimax(arg, &tmp, 10);
1235
1059
if(errno != 0 or tmp == arg or *tmp != '\0'
1236
1060
or tmpmax != (typeof(mc.dh_bits))tmpmax){
1237
argp_error(state, "Bad number of DH bits");
1061
fprintf(stderr, "Bad number of DH bits\n");
1239
1064
mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
1246
1071
delay = strtof(arg, &tmp);
1247
1072
if(errno != 0 or tmp == arg or *tmp != '\0'){
1248
argp_error(state, "Bad delay");
1073
fprintf(stderr, "Bad delay\n");
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);
1266
1082
return ARGP_ERR_UNKNOWN;
1271
1087
struct argp argp = { .options = options, .parser = parse_opt,
1272
1088
.args_doc = "",
1273
1089
.doc = "Mandos client -- Get and decrypt"
1274
1090
" passwords from a Mandos server" };
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;
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;
1293
1100
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;
1321
1103
/* Initialize Avahi early so avahi_simple_poll_quit() can be called
1322
1104
from the signal handler */
1333
1115
ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
1335
1117
perror("sigaddset");
1336
exitcode = EX_OSERR;
1118
exitcode = EXIT_FAILURE;
1339
1121
ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
1341
1123
perror("sigaddset");
1342
exitcode = EX_OSERR;
1124
exitcode = EXIT_FAILURE;
1345
1127
ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
1347
1129
perror("sigaddset");
1348
exitcode = EX_OSERR;
1130
exitcode = EXIT_FAILURE;
1351
1133
/* Need to check if the handler is SIG_IGN before handling:
1355
1137
ret = sigaction(SIGINT, NULL, &old_sigterm_action);
1357
1139
perror("sigaction");
1140
return EXIT_FAILURE;
1360
1142
if(old_sigterm_action.sa_handler != SIG_IGN){
1361
1143
ret = sigaction(SIGINT, &sigterm_action, NULL);
1363
1145
perror("sigaction");
1364
exitcode = EX_OSERR;
1146
exitcode = EXIT_FAILURE;
1368
1150
ret = sigaction(SIGHUP, NULL, &old_sigterm_action);
1370
1152
perror("sigaction");
1153
return EXIT_FAILURE;
1373
1155
if(old_sigterm_action.sa_handler != SIG_IGN){
1374
1156
ret = sigaction(SIGHUP, &sigterm_action, NULL);
1376
1158
perror("sigaction");
1377
exitcode = EX_OSERR;
1159
exitcode = EXIT_FAILURE;
1381
1163
ret = sigaction(SIGTERM, NULL, &old_sigterm_action);
1383
1165
perror("sigaction");
1166
return EXIT_FAILURE;
1386
1168
if(old_sigterm_action.sa_handler != SIG_IGN){
1387
1169
ret = sigaction(SIGTERM, &sigterm_action, NULL);
1389
1171
perror("sigaction");
1390
exitcode = EX_OSERR;
1172
exitcode = EXIT_FAILURE;
1395
1177
/* If the interface is down, bring it up */
1396
if(strcmp(interface, "none") != 0){
1178
if(interface[0] != '\0'){
1397
1179
if_index = (AvahiIfIndex) if_nametoindex(interface);
1398
1180
if(if_index == 0){
1399
1181
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1400
exitcode = EX_UNAVAILABLE;
1182
exitcode = EXIT_FAILURE;
1408
/* Re-raise priviliges */
1415
1190
#ifdef __linux__
1416
1191
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1417
messages about the network interface to mess up the prompt */
1192
messages to mess up the prompt */
1418
1193
ret = klogctl(8, NULL, 5);
1419
1194
bool restore_loglevel = true;
1470
1233
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1472
1235
take_down_interface = false;
1473
perror("ioctl SIOCSIFFLAGS +IFF_UP");
1474
exitcode = EX_OSERR;
1236
perror("ioctl SIOCSIFFLAGS");
1237
exitcode = EXIT_FAILURE;
1475
1238
#ifdef __linux__
1476
1239
if(restore_loglevel){
1477
1240
ret = klogctl(7, NULL, 0);
1521
1278
#endif /* __linux__ */
1522
/* Lower privileges */
1524
if(take_down_interface){
1525
/* Lower privileges */
1531
/* Lower privileges permanently */
1288
/* Drop any group privileges we might have, just to be safe */
1295
/* Drop user privileges */
1297
/* Will we need privileges later? */
1298
if(take_down_interface){
1299
/* Drop user privileges temporarily */
1305
/* Drop user privileges permanently */
1567
1340
if(not init_gpgme(pubkey, seckey, tempdir)){
1568
1341
fprintf(stderr, "init_gpgme failed\n");
1569
exitcode = EX_UNAVAILABLE;
1342
exitcode = EXIT_FAILURE;
1572
1345
gpgme_initialized = true;
1743
1498
perror("ioctl SIOCGIFFLAGS");
1744
1499
} else if(network.ifr_flags & IFF_UP) {
1745
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1500
network.ifr_flags &= ~IFF_UP; /* clear flag */
1746
1501
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1748
perror("ioctl SIOCSIFFLAGS -IFF_UP");
1503
perror("ioctl SIOCSIFFLAGS");
1751
1506
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1753
1508
perror("close");
1755
/* Lower privileges permanently */
1510
/* Lower privileges, permanently this time */
1757
1512
ret = setuid(uid);
1809
1564
sigemptyset(&old_sigterm_action.sa_mask);
1810
1565
old_sigterm_action.sa_handler = SIG_DFL;
1811
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
1812
&old_sigterm_action,
1566
ret = sigaction(signal_received, &old_sigterm_action, NULL);
1815
1568
perror("sigaction");
1818
ret = raise(signal_received);
1819
} while(ret != 0 and errno == EINTR);
1824
TEMP_FAILURE_RETRY(pause());
1570
raise(signal_received);
1827
1573
return exitcode;