1
/* -*- coding: utf-8 -*- */
3
* Mandos client - get and decrypt data from a Mandos server
5
* This program is partly derived from an example program for an Avahi
6
* service browser, downloaded from
7
* <http://avahi.org/browser/examples/core-browse-services.c>. This
8
* includes the following functions: "resolve_callback",
9
* "browse_callback", and parts of "main".
11
* Everything else is Copyright © 2007-2008 Teddy Hogeborn and Björn
14
* This program is free software: you can redistribute it and/or
15
* modify it under the terms of the GNU General Public License as
16
* published by the Free Software Foundation, either version 3 of the
17
* License, or (at your option) any later version.
19
* This program is distributed in the hope that it will be useful, but
20
* WITHOUT ANY WARRANTY; without even the implied warranty of
21
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22
* General Public License for more details.
24
* You should have received a copy of the GNU General Public License
25
* along with this program. If not, see
26
* <http://www.gnu.org/licenses/>.
28
* Contact the authors at <https://www.fukt.bsnet.se/~belorn/> and
29
* <https://www.fukt.bsnet.se/~teddy/>.
32
#define _FORTIFY_SOURCE 2
34
#define _LARGEFILE_SOURCE
35
#define _FILE_OFFSET_BITS 64
41
#include <net/if.h> /* if_nametoindex */
43
#include <avahi-core/core.h>
44
#include <avahi-core/lookup.h>
45
#include <avahi-core/log.h>
46
#include <avahi-common/simple-watch.h>
47
#include <avahi-common/malloc.h>
48
#include <avahi-common/error.h>
51
#include <sys/types.h> /* socket(), inet_pton() */
52
#include <sys/socket.h> /* socket(), struct sockaddr_in6,
53
struct in6_addr, inet_pton() */
54
#include <gnutls/gnutls.h> /* All GnuTLS stuff */
55
#include <gnutls/openpgp.h> /* GnuTLS with openpgp stuff */
57
#include <unistd.h> /* close() */
58
#include <netinet/in.h>
59
#include <stdbool.h> /* true */
60
#include <string.h> /* memset */
61
#include <arpa/inet.h> /* inet_pton() */
62
#include <iso646.h> /* not */
65
#include <errno.h> /* perror() */
71
#define BUFFER_SIZE 256
74
const char *certdir = "/conf/conf.d/cryptkeyreq/";
75
const char *certfile = "openpgp-client.txt";
76
const char *certkey = "openpgp-client-key.txt";
81
gnutls_session_t session;
82
gnutls_certificate_credentials_t cred;
83
gnutls_dh_params_t dh_params;
87
ssize_t pgp_packet_decrypt (char *packet, size_t packet_size,
88
char **new_packet, const char *homedir){
89
gpgme_data_t dh_crypto, dh_plain;
93
ssize_t new_packet_capacity = 0;
94
ssize_t new_packet_length = 0;
95
gpgme_engine_info_t engine_info;
98
fprintf(stderr, "Trying to decrypt OpenPGP packet\n");
102
gpgme_check_version(NULL);
103
rc = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
104
if (rc != GPG_ERR_NO_ERROR){
105
fprintf(stderr, "bad gpgme_engine_check_version: %s: %s\n",
106
gpgme_strsource(rc), gpgme_strerror(rc));
110
/* Set GPGME home directory */
111
rc = gpgme_get_engine_info (&engine_info);
112
if (rc != GPG_ERR_NO_ERROR){
113
fprintf(stderr, "bad gpgme_get_engine_info: %s: %s\n",
114
gpgme_strsource(rc), gpgme_strerror(rc));
117
while(engine_info != NULL){
118
if(engine_info->protocol == GPGME_PROTOCOL_OpenPGP){
119
gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP,
120
engine_info->file_name, homedir);
123
engine_info = engine_info->next;
125
if(engine_info == NULL){
126
fprintf(stderr, "Could not set home dir to %s\n", homedir);
130
/* Create new GPGME data buffer from packet buffer */
131
rc = gpgme_data_new_from_mem(&dh_crypto, packet, packet_size, 0);
132
if (rc != GPG_ERR_NO_ERROR){
133
fprintf(stderr, "bad gpgme_data_new_from_mem: %s: %s\n",
134
gpgme_strsource(rc), gpgme_strerror(rc));
138
/* Create new empty GPGME data buffer for the plaintext */
139
rc = gpgme_data_new(&dh_plain);
140
if (rc != GPG_ERR_NO_ERROR){
141
fprintf(stderr, "bad gpgme_data_new: %s: %s\n",
142
gpgme_strsource(rc), gpgme_strerror(rc));
146
/* Create new GPGME "context" */
147
rc = gpgme_new(&ctx);
148
if (rc != GPG_ERR_NO_ERROR){
149
fprintf(stderr, "bad gpgme_new: %s: %s\n",
150
gpgme_strsource(rc), gpgme_strerror(rc));
154
/* Decrypt data from the FILE pointer to the plaintext data
156
rc = gpgme_op_decrypt(ctx, dh_crypto, dh_plain);
157
if (rc != GPG_ERR_NO_ERROR){
158
fprintf(stderr, "bad gpgme_op_decrypt: %s: %s\n",
159
gpgme_strsource(rc), gpgme_strerror(rc));
164
fprintf(stderr, "Decryption of OpenPGP packet succeeded\n");
168
gpgme_decrypt_result_t result;
169
result = gpgme_op_decrypt_result(ctx);
171
fprintf(stderr, "gpgme_op_decrypt_result failed\n");
173
fprintf(stderr, "Unsupported algorithm: %s\n",
174
result->unsupported_algorithm);
175
fprintf(stderr, "Wrong key usage: %d\n",
176
result->wrong_key_usage);
177
if(result->file_name != NULL){
178
fprintf(stderr, "File name: %s\n", result->file_name);
180
gpgme_recipient_t recipient;
181
recipient = result->recipients;
183
while(recipient != NULL){
184
fprintf(stderr, "Public key algorithm: %s\n",
185
gpgme_pubkey_algo_name(recipient->pubkey_algo));
186
fprintf(stderr, "Key ID: %s\n", recipient->keyid);
187
fprintf(stderr, "Secret key available: %s\n",
188
recipient->status == GPG_ERR_NO_SECKEY
190
recipient = recipient->next;
196
/* Delete the GPGME FILE pointer cryptotext data buffer */
197
gpgme_data_release(dh_crypto);
199
/* Seek back to the beginning of the GPGME plaintext data buffer */
200
gpgme_data_seek(dh_plain, (off_t) 0, SEEK_SET);
204
if (new_packet_length + BUFFER_SIZE > new_packet_capacity){
205
*new_packet = realloc(*new_packet,
206
(unsigned int)new_packet_capacity
208
if (*new_packet == NULL){
212
new_packet_capacity += BUFFER_SIZE;
215
ret = gpgme_data_read(dh_plain, *new_packet + new_packet_length,
217
/* Print the data, if any */
222
perror("gpgme_data_read");
225
new_packet_length += ret;
228
/* FIXME: check characters before printing to screen so to not print
229
terminal control characters */
231
/* fprintf(stderr, "decrypted password is: "); */
232
/* fwrite(*new_packet, 1, new_packet_length, stderr); */
233
/* fprintf(stderr, "\n"); */
236
/* Delete the GPGME plaintext data buffer */
237
gpgme_data_release(dh_plain);
238
return new_packet_length;
241
static const char * safer_gnutls_strerror (int value) {
242
const char *ret = gnutls_strerror (value);
248
void debuggnutls(__attribute__((unused)) int level,
250
fprintf(stderr, "%s", string);
253
int initgnutls(encrypted_session *es){
258
fprintf(stderr, "Initializing GnuTLS\n");
261
if ((ret = gnutls_global_init ())
262
!= GNUTLS_E_SUCCESS) {
263
fprintf (stderr, "global_init: %s\n", safer_gnutls_strerror(ret));
268
gnutls_global_set_log_level(11);
269
gnutls_global_set_log_function(debuggnutls);
272
/* openpgp credentials */
273
if ((ret = gnutls_certificate_allocate_credentials (&es->cred))
274
!= GNUTLS_E_SUCCESS) {
275
fprintf (stderr, "memory error: %s\n",
276
safer_gnutls_strerror(ret));
281
fprintf(stderr, "Attempting to use OpenPGP certificate %s"
282
" and keyfile %s as GnuTLS credentials\n", certfile,
286
ret = gnutls_certificate_set_openpgp_key_file
287
(es->cred, certfile, certkey, GNUTLS_OPENPGP_FMT_BASE64);
288
if (ret != GNUTLS_E_SUCCESS) {
290
(stderr, "Error[%d] while reading the OpenPGP key pair ('%s',"
292
ret, certfile, certkey);
293
fprintf(stdout, "The Error is: %s\n",
294
safer_gnutls_strerror(ret));
298
//GnuTLS server initialization
299
if ((ret = gnutls_dh_params_init (&es->dh_params))
300
!= GNUTLS_E_SUCCESS) {
301
fprintf (stderr, "Error in dh parameter initialization: %s\n",
302
safer_gnutls_strerror(ret));
306
if ((ret = gnutls_dh_params_generate2 (es->dh_params, DH_BITS))
307
!= GNUTLS_E_SUCCESS) {
308
fprintf (stderr, "Error in prime generation: %s\n",
309
safer_gnutls_strerror(ret));
313
gnutls_certificate_set_dh_params (es->cred, es->dh_params);
315
// GnuTLS session creation
316
if ((ret = gnutls_init (&es->session, GNUTLS_SERVER))
317
!= GNUTLS_E_SUCCESS){
318
fprintf(stderr, "Error in GnuTLS session initialization: %s\n",
319
safer_gnutls_strerror(ret));
322
if ((ret = gnutls_priority_set_direct (es->session, "NORMAL", &err))
323
!= GNUTLS_E_SUCCESS) {
324
fprintf(stderr, "Syntax error at: %s\n", err);
325
fprintf(stderr, "GnuTLS error: %s\n",
326
safer_gnutls_strerror(ret));
330
if ((ret = gnutls_credentials_set
331
(es->session, GNUTLS_CRD_CERTIFICATE, es->cred))
332
!= GNUTLS_E_SUCCESS) {
333
fprintf(stderr, "Error setting a credentials set: %s\n",
334
safer_gnutls_strerror(ret));
338
/* ignore client certificate if any. */
339
gnutls_certificate_server_set_request (es->session,
342
gnutls_dh_set_prime_bits (es->session, DH_BITS);
347
void empty_log(__attribute__((unused)) AvahiLogLevel level,
348
__attribute__((unused)) const char *txt){}
350
int start_mandos_communication(const char *ip, uint16_t port,
351
unsigned int if_index){
353
struct sockaddr_in6 to;
354
encrypted_session es;
356
char *decrypted_buffer;
357
size_t buffer_length = 0;
358
size_t buffer_capacity = 0;
359
ssize_t decrypted_buffer_size;
362
char interface[IF_NAMESIZE];
365
fprintf(stderr, "Setting up a tcp connection to %s\n", ip);
368
tcp_sd = socket(PF_INET6, SOCK_STREAM, 0);
374
if(if_indextoname(if_index, interface) == NULL){
376
perror("if_indextoname");
382
fprintf(stderr, "Binding to interface %s\n", interface);
385
memset(&to,0,sizeof(to)); /* Spurious warning */
386
to.sin6_family = AF_INET6;
387
ret = inet_pton(AF_INET6, ip, &to.sin6_addr);
393
fprintf(stderr, "Bad address: %s\n", ip);
396
to.sin6_port = htons(port); /* Spurious warning */
398
to.sin6_scope_id = (uint32_t)if_index;
401
fprintf(stderr, "Connection to: %s\n", ip);
404
ret = connect(tcp_sd, (struct sockaddr *) &to, sizeof(to));
410
ret = initgnutls (&es);
416
gnutls_transport_set_ptr (es.session,
417
(gnutls_transport_ptr_t) tcp_sd);
420
fprintf(stderr, "Establishing TLS session with %s\n", ip);
423
ret = gnutls_handshake (es.session);
425
if (ret != GNUTLS_E_SUCCESS){
427
fprintf(stderr, "\n*** Handshake failed ***\n");
434
//Retrieve OpenPGP packet that contains the wanted password
437
fprintf(stderr, "Retrieving pgp encrypted password from %s\n",
442
if (buffer_length + BUFFER_SIZE > buffer_capacity){
443
buffer = realloc(buffer, buffer_capacity + BUFFER_SIZE);
448
buffer_capacity += BUFFER_SIZE;
451
ret = gnutls_record_recv
452
(es.session, buffer+buffer_length, BUFFER_SIZE);
458
case GNUTLS_E_INTERRUPTED:
461
case GNUTLS_E_REHANDSHAKE:
462
ret = gnutls_handshake (es.session);
464
fprintf(stderr, "\n*** Handshake failed ***\n");
471
fprintf(stderr, "Unknown error while reading data from"
472
" encrypted session with mandos server\n");
474
gnutls_bye (es.session, GNUTLS_SHUT_RDWR);
478
buffer_length += (size_t) ret;
482
if (buffer_length > 0){
483
decrypted_buffer_size = pgp_packet_decrypt(buffer,
487
if (decrypted_buffer_size >= 0){
488
while(written < decrypted_buffer_size){
489
ret = (int)fwrite (decrypted_buffer + written, 1,
490
(size_t)decrypted_buffer_size - written,
492
if(ret == 0 and ferror(stdout)){
494
fprintf(stderr, "Error writing encrypted data: %s\n",
500
written += (size_t)ret;
502
free(decrypted_buffer);
511
fprintf(stderr, "Closing TLS session\n");
515
gnutls_bye (es.session, GNUTLS_SHUT_RDWR);
518
gnutls_deinit (es.session);
519
gnutls_certificate_free_credentials (es.cred);
520
gnutls_global_deinit ();
524
static AvahiSimplePoll *simple_poll = NULL;
525
static AvahiServer *server = NULL;
527
static void resolve_callback(
528
AvahiSServiceResolver *r,
529
AvahiIfIndex interface,
530
AVAHI_GCC_UNUSED AvahiProtocol protocol,
531
AvahiResolverEvent event,
535
const char *host_name,
536
const AvahiAddress *address,
538
AVAHI_GCC_UNUSED AvahiStringList *txt,
539
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
540
AVAHI_GCC_UNUSED void* userdata) {
542
assert(r); /* Spurious warning */
544
/* Called whenever a service has been resolved successfully or
549
case AVAHI_RESOLVER_FAILURE:
550
fprintf(stderr, "(Resolver) Failed to resolve service '%s' of"
551
" type '%s' in domain '%s': %s\n", name, type, domain,
552
avahi_strerror(avahi_server_errno(server)));
555
case AVAHI_RESOLVER_FOUND:
557
char ip[AVAHI_ADDRESS_STR_MAX];
558
avahi_address_snprint(ip, sizeof(ip), address);
560
fprintf(stderr, "Mandos server \"%s\" found on %s (%s) on"
561
" port %d\n", name, host_name, ip, port);
563
int ret = start_mandos_communication(ip, port,
564
(unsigned int) interface);
570
avahi_s_service_resolver_free(r);
573
static void browse_callback(
574
AvahiSServiceBrowser *b,
575
AvahiIfIndex interface,
576
AvahiProtocol protocol,
577
AvahiBrowserEvent event,
581
AVAHI_GCC_UNUSED AvahiLookupResultFlags flags,
584
AvahiServer *s = userdata;
585
assert(b); /* Spurious warning */
587
/* Called whenever a new services becomes available on the LAN or
588
is removed from the LAN */
592
case AVAHI_BROWSER_FAILURE:
594
fprintf(stderr, "(Browser) %s\n",
595
avahi_strerror(avahi_server_errno(server)));
596
avahi_simple_poll_quit(simple_poll);
599
case AVAHI_BROWSER_NEW:
600
/* We ignore the returned resolver object. In the callback
601
function we free it. If the server is terminated before
602
the callback function is called the server will free
603
the resolver for us. */
605
if (!(avahi_s_service_resolver_new(s, interface, protocol, name,
607
AVAHI_PROTO_INET6, 0,
608
resolve_callback, s)))
609
fprintf(stderr, "Failed to resolve service '%s': %s\n", name,
610
avahi_strerror(avahi_server_errno(s)));
613
case AVAHI_BROWSER_REMOVE:
616
case AVAHI_BROWSER_ALL_FOR_NOW:
617
case AVAHI_BROWSER_CACHE_EXHAUSTED:
622
/* combinds two strings and returns the malloced new string. som sane checks could/should be added */
623
const char *combinestrings(const char *first, const char *second){
625
tmp = malloc(strlen(first) + strlen(second));
636
int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
637
AvahiServerConfig config;
638
AvahiSServiceBrowser *sb = NULL;
641
int returncode = EXIT_SUCCESS;
642
const char *interface = "eth0";
645
static struct option long_options[] = {
646
{"debug", no_argument, (int *)&debug, 1},
647
{"interface", required_argument, 0, 'i'},
648
{"certdir", required_argument, 0, 'd'},
649
{"certkey", required_argument, 0, 'c'},
650
{"certfile", required_argument, 0, 'k'},
653
int option_index = 0;
654
ret = getopt_long (argc, argv, "i:", long_options,
681
certfile = combinestrings(certdir, certfile);
682
if (certfile == NULL){
686
certkey = combinestrings(certdir, certkey);
687
if (certkey == NULL){
692
avahi_set_log_function(empty_log);
695
/* Initialize the psuedo-RNG */
696
srand((unsigned int) time(NULL));
698
/* Allocate main loop object */
699
if (!(simple_poll = avahi_simple_poll_new())) {
700
fprintf(stderr, "Failed to create simple poll object.\n");
705
/* Do not publish any local records */
706
avahi_server_config_init(&config);
707
config.publish_hinfo = 0;
708
config.publish_addresses = 0;
709
config.publish_workstation = 0;
710
config.publish_domain = 0;
712
/* Allocate a new server */
713
server = avahi_server_new(avahi_simple_poll_get(simple_poll),
714
&config, NULL, NULL, &error);
716
/* Free the configuration data */
717
avahi_server_config_free(&config);
719
/* Check if creating the server object succeeded */
721
fprintf(stderr, "Failed to create server: %s\n",
722
avahi_strerror(error));
723
returncode = EXIT_FAILURE;
727
/* Create the service browser */
728
sb = avahi_s_service_browser_new(server,
730
if_nametoindex(interface),
732
"_mandos._tcp", NULL, 0,
733
browse_callback, server);
735
fprintf(stderr, "Failed to create service browser: %s\n",
736
avahi_strerror(avahi_server_errno(server)));
737
returncode = EXIT_FAILURE;
741
/* Run the main loop */
744
fprintf(stderr, "Starting avahi loop search\n");
747
avahi_simple_poll_loop(simple_poll);
752
fprintf(stderr, "%s exiting\n", argv[0]);
757
avahi_s_service_browser_free(sb);
760
avahi_server_free(server);
763
avahi_simple_poll_free(simple_poll);