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() */
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 */
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
807
ret = gnutls_handshake(session);
772
813
} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);
774
815
fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");
775
816
gnutls_perror(ret);
781
822
fprintf(stderr, "Unknown error while reading data from"
782
823
" encrypted session with Mandos server\n");
784
824
gnutls_bye(session, GNUTLS_SHUT_RDWR);
800
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);
806
850
if(buffer_length > 0){
807
851
ssize_t decrypted_buffer_size;
820
865
(size_t)decrypted_buffer_size - written,
822
867
if(ret == 0 and ferror(stdout)){
824
870
fprintf(stderr, "Error writing encrypted data: %s\n",
825
871
strerror(errno));
830
876
written += (size_t)ret;
832
free(decrypted_buffer);
840
882
/* Shutdown procedure */
845
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
850
gnutls_deinit(session);
887
free(decrypted_buffer);
890
ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));
898
gnutls_deinit(session);
971
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",
974
1120
int main(int argc, char *argv[]){
975
1121
AvahiSServiceBrowser *sb = NULL;
978
1124
intmax_t tmpmax;
980
1126
int exitcode = EXIT_SUCCESS;
981
const char *interface = "eth0";
1127
const char *interface = "";
982
1128
struct ifreq network;
984
1130
bool take_down_interface = false;
987
char *connect_to = NULL;
988
1133
char tempdir[] = "/tmp/mandosXXXXXX";
989
1134
bool tempdir_created = false;
990
1135
AvahiIfIndex if_index = AVAHI_IF_UNSPEC;
995
1140
bool gpgme_initialized = false;
996
1141
float delay = 2.5f;
998
struct sigaction old_sigterm_action;
1143
struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };
999
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) */
1002
1168
struct argp_option options[] = {
1003
1169
{ .name = "debug", .key = 128,
1032
1198
.arg = "SECONDS",
1033
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 },
1035
1210
{ .name = NULL }
1038
1213
error_t parse_opt(int key, char *arg,
1039
1214
struct argp_state *state){
1041
1217
case 128: /* --debug */
1058
1234
tmpmax = strtoimax(arg, &tmp, 10);
1059
1235
if(errno != 0 or tmp == arg or *tmp != '\0'
1060
1236
or tmpmax != (typeof(mc.dh_bits))tmpmax){
1061
fprintf(stderr, "Bad number of DH bits\n");
1237
argp_error(state, "Bad number of DH bits");
1064
1239
mc.dh_bits = (typeof(mc.dh_bits))tmpmax;
1071
1246
delay = strtof(arg, &tmp);
1072
1247
if(errno != 0 or tmp == arg or *tmp != '\0'){
1073
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);
1082
1266
return ARGP_ERR_UNKNOWN;
1087
1271
struct argp argp = { .options = options, .parser = parse_opt,
1088
1272
.args_doc = "",
1089
1273
.doc = "Mandos client -- Get and decrypt"
1090
1274
" 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;
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;
1100
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;
1103
1321
/* Initialize Avahi early so avahi_simple_poll_quit() can be called
1104
1322
from the signal handler */
1115
1333
ret = sigaddset(&sigterm_action.sa_mask, SIGINT);
1117
1335
perror("sigaddset");
1118
exitcode = EXIT_FAILURE;
1336
exitcode = EX_OSERR;
1121
1339
ret = sigaddset(&sigterm_action.sa_mask, SIGHUP);
1123
1341
perror("sigaddset");
1124
exitcode = EXIT_FAILURE;
1342
exitcode = EX_OSERR;
1127
1345
ret = sigaddset(&sigterm_action.sa_mask, SIGTERM);
1129
1347
perror("sigaddset");
1130
exitcode = EXIT_FAILURE;
1348
exitcode = EX_OSERR;
1133
1351
/* Need to check if the handler is SIG_IGN before handling:
1137
1355
ret = sigaction(SIGINT, NULL, &old_sigterm_action);
1139
1357
perror("sigaction");
1140
return EXIT_FAILURE;
1142
1360
if(old_sigterm_action.sa_handler != SIG_IGN){
1143
1361
ret = sigaction(SIGINT, &sigterm_action, NULL);
1145
1363
perror("sigaction");
1146
exitcode = EXIT_FAILURE;
1364
exitcode = EX_OSERR;
1150
1368
ret = sigaction(SIGHUP, NULL, &old_sigterm_action);
1152
1370
perror("sigaction");
1153
return EXIT_FAILURE;
1155
1373
if(old_sigterm_action.sa_handler != SIG_IGN){
1156
1374
ret = sigaction(SIGHUP, &sigterm_action, NULL);
1158
1376
perror("sigaction");
1159
exitcode = EXIT_FAILURE;
1377
exitcode = EX_OSERR;
1163
1381
ret = sigaction(SIGTERM, NULL, &old_sigterm_action);
1165
1383
perror("sigaction");
1166
return EXIT_FAILURE;
1168
1386
if(old_sigterm_action.sa_handler != SIG_IGN){
1169
1387
ret = sigaction(SIGTERM, &sigterm_action, NULL);
1171
1389
perror("sigaction");
1172
exitcode = EXIT_FAILURE;
1390
exitcode = EX_OSERR;
1177
1395
/* If the interface is down, bring it up */
1178
if(interface[0] != '\0'){
1396
if(strcmp(interface, "none") != 0){
1179
1397
if_index = (AvahiIfIndex) if_nametoindex(interface);
1180
1398
if(if_index == 0){
1181
1399
fprintf(stderr, "No such interface: \"%s\"\n", interface);
1182
exitcode = EXIT_FAILURE;
1400
exitcode = EX_UNAVAILABLE;
1408
/* Re-raise priviliges */
1190
1415
#ifdef __linux__
1191
1416
/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO
1192
messages to mess up the prompt */
1417
messages about the network interface to mess up the prompt */
1193
1418
ret = klogctl(8, NULL, 5);
1194
1419
bool restore_loglevel = true;
1233
1470
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1235
1472
take_down_interface = false;
1236
perror("ioctl SIOCSIFFLAGS");
1237
exitcode = EXIT_FAILURE;
1473
perror("ioctl SIOCSIFFLAGS +IFF_UP");
1474
exitcode = EX_OSERR;
1238
1475
#ifdef __linux__
1239
1476
if(restore_loglevel){
1240
1477
ret = klogctl(7, NULL, 0);
1278
1521
#endif /* __linux__ */
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 */
1522
/* Lower privileges */
1524
if(take_down_interface){
1525
/* Lower privileges */
1531
/* Lower privileges permanently */
1340
1567
if(not init_gpgme(pubkey, seckey, tempdir)){
1341
1568
fprintf(stderr, "init_gpgme failed\n");
1342
exitcode = EXIT_FAILURE;
1569
exitcode = EX_UNAVAILABLE;
1345
1572
gpgme_initialized = true;
1498
1743
perror("ioctl SIOCGIFFLAGS");
1499
1744
} else if(network.ifr_flags & IFF_UP) {
1500
network.ifr_flags &= ~IFF_UP; /* clear flag */
1745
network.ifr_flags &= ~(short)IFF_UP; /* clear flag */
1501
1746
ret = ioctl(sd, SIOCSIFFLAGS, &network);
1503
perror("ioctl SIOCSIFFLAGS");
1748
perror("ioctl SIOCSIFFLAGS -IFF_UP");
1506
1751
ret = (int)TEMP_FAILURE_RETRY(close(sd));
1508
1753
perror("close");
1510
/* Lower privileges, permanently this time */
1755
/* Lower privileges permanently */
1512
1757
ret = setuid(uid);
1564
1809
sigemptyset(&old_sigterm_action.sa_mask);
1565
1810
old_sigterm_action.sa_handler = SIG_DFL;
1566
ret = sigaction(signal_received, &old_sigterm_action, NULL);
1811
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
1812
&old_sigterm_action,
1568
1815
perror("sigaction");
1570
raise(signal_received);
1818
ret = raise(signal_received);
1819
} while(ret != 0 and errno == EINTR);
1824
TEMP_FAILURE_RETRY(pause());
1573
1827
return exitcode;