2 protocol_auth.c -- handle the meta-protocol, authentication
3 Copyright (C) 1999-2005 Ivo Timmermans,
4 2000-2010 Guus Sliepen <guus@tinc-vpn.org>
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation, Inc.,
18 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 #include "splay_tree.h"
25 #include "connection.h"
27 #include "control_common.h"
43 bool send_id(connection_t *c) {
44 gettimeofday(&c->start, NULL);
46 int minor = myself->connection->protocol_minor;
47 if(c->config_tree && !read_ecdsa_public_key(c))
50 return send_request(c, "%d %s %d.%d", ID, myself->connection->name,
51 myself->connection->protocol_major, minor);
54 bool id_h(connection_t *c, char *request) {
55 char name[MAX_STRING_SIZE];
57 if(sscanf(request, "%*d " MAX_STRING " %d.%d", name, &c->protocol_major, &c->protocol_minor) < 2) {
58 logger(LOG_ERR, "Got bad %s from %s (%s)", "ID", c->name,
63 /* Check if this is a control connection */
65 if(name[0] == '^' && !strcmp(name + 1, controlcookie)) {
66 c->status.control = true;
67 c->allow_request = CONTROL;
68 c->last_ping_time = time(NULL) + 3600;
69 return send_request(c, "%d %d %d", ACK, TINC_CTL_VERSION_CURRENT, getpid());
72 /* Check if identity is a valid name */
75 logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ID", c->name,
76 c->hostname, "invalid name");
80 /* If this is an outgoing connection, make sure we are connected to the right host */
83 if(strcmp(c->name, name)) {
84 logger(LOG_ERR, "Peer %s is %s instead of %s", c->hostname, name,
91 c->name = xstrdup(name);
94 /* Check if version matches */
96 if(c->protocol_major != myself->connection->protocol_major) {
97 logger(LOG_ERR, "Peer %s (%s) uses incompatible version %d.%d",
98 c->name, c->hostname, c->protocol_major, c->protocol_minor);
102 if(bypass_security) {
104 init_configuration(&c->config_tree);
105 c->allow_request = ACK;
109 if(!c->config_tree) {
110 init_configuration(&c->config_tree);
112 if(!read_connection_config(c)) {
113 logger(LOG_ERR, "Peer %s had unknown identity (%s)", c->hostname,
118 if(c->protocol_minor >= 2)
119 if(!read_ecdsa_public_key(c))
122 if(!ecdsa_active(&c->ecdsa))
123 c->protocol_minor = 1;
126 c->allow_request = METAKEY;
128 if(c->protocol_minor >= 2)
129 return send_metakey_ec(c);
131 return send_metakey(c);
134 bool send_metakey_ec(connection_t *c) {
135 logger(LOG_DEBUG, "Sending ECDH metakey to %s", c->name);
137 size_t siglen = ecdsa_size(&myself->connection->ecdsa);
142 // TODO: include nonce? Use relevant parts of SSH or TLS protocol
144 if(!ecdh_generate_public(&c->ecdh, key))
147 if(!ecdsa_sign(&myself->connection->ecdsa, key, ECDH_SIZE, sig))
150 char out[MAX_STRING_SIZE];
152 bin2hex(key, out, ECDH_SIZE);
153 bin2hex(sig, out + ECDH_SIZE * 2, siglen);
154 out[(ECDH_SIZE + siglen) * 2] = 0;
156 bool result = send_request(c, "%d %s", METAKEY, out);
159 bool send_metakey(connection_t *c) {
160 if(!read_rsa_public_key(c))
163 if(!cipher_open_blowfish_ofb(&c->outcipher))
166 if(!digest_open_sha1(&c->outdigest, -1))
169 size_t len = rsa_size(&c->rsa);
172 char hexkey[2 * len + 1];
174 /* Create a random key */
178 /* The message we send must be smaller than the modulus of the RSA key.
179 By definition, for a key of k bits, the following formula holds:
181 2^(k-1) <= modulus < 2^(k)
183 Where ^ means "to the power of", not "xor".
184 This means that to be sure, we must choose our message < 2^(k-1).
185 This can be done by setting the most significant bit to zero.
190 cipher_set_key_from_rsa(&c->outcipher, key, len, true);
192 ifdebug(SCARY_THINGS) {
193 bin2hex(key, hexkey, len);
194 hexkey[len * 2] = '\0';
195 logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s", hexkey);
198 /* Encrypt the random data
200 We do not use one of the PKCS padding schemes here.
201 This is allowed, because we encrypt a totally random string
202 with a length equal to that of the modulus of the RSA key.
205 if(!rsa_public_encrypt(&c->rsa, key, len, enckey)) {
206 logger(LOG_ERR, "Error during encryption of meta key for %s (%s)", c->name, c->hostname);
210 /* Convert the encrypted random data to a hexadecimal formatted string */
212 bin2hex(enckey, hexkey, len);
213 hexkey[len * 2] = '\0';
215 /* Send the meta key */
217 bool result = send_request(c, "%d %d %d %d %d %s", METAKEY,
218 cipher_get_nid(&c->outcipher),
219 digest_get_nid(&c->outdigest), c->outmaclength,
220 c->outcompression, hexkey);
222 c->status.encryptout = true;
226 static bool metakey_ec_h(connection_t *c, const char *request) {
227 size_t siglen = ecdsa_size(&c->ecdsa);
228 char in[MAX_STRING_SIZE];
229 char key[MAX_STRING_SIZE];
232 logger(LOG_DEBUG, "Got ECDH metakey from %s", c->name);
234 if(sscanf(request, "%*d " MAX_STRING, in) != 1) {
235 logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname);
239 if(strlen(in) != (ECDH_SIZE + siglen) * 2) {
240 logger(LOG_ERR, "Possible intruder %s (%s): %s %d != %d", c->name, c->hostname, "wrong keylength", strlen(in) / 2, (ECDH_SIZE + siglen));
244 hex2bin(in, key, ECDH_SIZE);
245 hex2bin(in + ECDH_SIZE * 2, sig, siglen);
247 if(!ecdsa_verify(&c->ecdsa, key, ECDH_SIZE, sig)) {
248 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "invalid ECDSA signature");
252 char shared[ECDH_SHARED_SIZE * 2 + 1];
254 if(!ecdh_compute_shared(&c->ecdh, key, shared))
257 /* Update our crypto end */
259 if(!cipher_open_by_name(&c->incipher, "aes-256-ofb"))
261 if(!digest_open_by_name(&c->indigest, "sha512", -1))
263 if(!cipher_open_by_name(&c->outcipher, "aes-256-ofb"))
265 if(!digest_open_by_name(&c->outdigest, "sha512", -1))
268 size_t mykeylen = cipher_keylength(&c->incipher);
269 size_t hiskeylen = cipher_keylength(&c->outcipher);
275 if(strcmp(myself->name, c->name) < 0) {
277 hiskey = key + mykeylen * 2;
278 xasprintf(&seed, "tinc TCP key expansion %s %s", myself->name, c->name);
280 mykey = key + hiskeylen * 2;
282 xasprintf(&seed, "tinc TCP key expansion %s %s", c->name, myself->name);
285 if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
290 bin2hex(shared, shared, ECDH_SHARED_SIZE);
291 shared[ECDH_SHARED_SIZE * 2] = 0;
292 logger(LOG_DEBUG, "Shared secret is %s", shared);
294 cipher_set_key(&c->incipher, mykey, true);
295 digest_set_key(&c->indigest, mykey + mykeylen, mykeylen);
297 cipher_set_key(&c->outcipher, hiskey, false);
298 digest_set_key(&c->outdigest, hiskey + hiskeylen, hiskeylen);
300 c->status.decryptin = true;
301 c->status.encryptout = true;
302 c->allow_request = CHALLENGE;
304 return send_challenge(c);
307 bool metakey_h(connection_t *c, char *request) {
308 if(c->protocol_minor >= 2)
309 return metakey_ec_h(c, request);
311 char hexkey[MAX_STRING_SIZE];
312 int cipher, digest, maclength, compression;
313 size_t len = rsa_size(&myself->connection->rsa);
317 if(sscanf(request, "%*d %d %d %d %d " MAX_STRING, &cipher, &digest, &maclength, &compression, hexkey) != 5) {
318 logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname);
322 /* Check if the length of the meta key is all right */
324 if(strlen(hexkey) != len * 2) {
325 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength");
329 /* Convert the challenge from hexadecimal back to binary */
331 hex2bin(hexkey, enckey, len);
333 /* Decrypt the meta key */
335 if(!rsa_private_decrypt(&myself->connection->rsa, enckey, len, key)) {
336 logger(LOG_ERR, "Error during decryption of meta key for %s (%s)", c->name, c->hostname);
340 ifdebug(SCARY_THINGS) {
341 bin2hex(key, hexkey, len);
342 hexkey[len * 2] = '\0';
343 logger(LOG_DEBUG, "Received random meta key (unencrypted): %s", hexkey);
346 /* Check and lookup cipher and digest algorithms */
348 if(!cipher_open_by_nid(&c->incipher, cipher) || !cipher_set_key_from_rsa(&c->incipher, key, len, false)) {
349 logger(LOG_ERR, "Error during initialisation of cipher from %s (%s)", c->name, c->hostname);
353 if(!digest_open_by_nid(&c->indigest, digest, -1)) {
354 logger(LOG_ERR, "Error during initialisation of digest from %s (%s)", c->name, c->hostname);
358 c->status.decryptin = true;
360 c->allow_request = CHALLENGE;
362 return send_challenge(c);
365 bool send_challenge(connection_t *c) {
366 size_t len = c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&c->rsa);
367 char buffer[len * 2 + 1];
370 c->hischallenge = xrealloc(c->hischallenge, len);
372 /* Copy random data to the buffer */
374 randomize(c->hischallenge, len);
378 bin2hex(c->hischallenge, buffer, len);
379 buffer[len * 2] = '\0';
381 /* Send the challenge */
383 return send_request(c, "%d %s", CHALLENGE, buffer);
386 bool challenge_h(connection_t *c, char *request) {
387 char buffer[MAX_STRING_SIZE];
388 size_t len = c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&myself->connection->rsa);
389 size_t digestlen = digest_length(&c->indigest);
390 char digest[digestlen];
392 if(sscanf(request, "%*d " MAX_STRING, buffer) != 1) {
393 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHALLENGE", c->name, c->hostname);
397 /* Check if the length of the challenge is all right */
399 if(strlen(buffer) != len * 2) {
400 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge length");
404 /* Convert the challenge from hexadecimal back to binary */
406 hex2bin(buffer, buffer, len);
408 c->allow_request = CHAL_REPLY;
410 /* Calculate the hash from the challenge we received */
412 digest_create(&c->indigest, buffer, len, digest);
414 /* Convert the hash to a hexadecimal formatted string */
416 bin2hex(digest, buffer, digestlen);
417 buffer[digestlen * 2] = '\0';
421 return send_request(c, "%d %s", CHAL_REPLY, buffer);
424 bool chal_reply_h(connection_t *c, char *request) {
425 char hishash[MAX_STRING_SIZE];
427 if(sscanf(request, "%*d " MAX_STRING, hishash) != 1) {
428 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHAL_REPLY", c->name,
433 /* Check if the length of the hash is all right */
435 if(strlen(hishash) != digest_length(&c->outdigest) * 2) {
436 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply length");
440 /* Convert the hash to binary format */
442 hex2bin(hishash, hishash, digest_length(&c->outdigest));
444 /* Verify the hash */
446 if(!digest_verify(&c->outdigest, c->hischallenge, c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&c->rsa), hishash)) {
447 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply");
451 /* Identity has now been positively verified.
452 Send an acknowledgement with the rest of the information needed.
455 free(c->hischallenge);
456 c->hischallenge = NULL;
457 c->allow_request = ACK;
462 static bool send_upgrade(connection_t *c) {
463 /* Special case when protocol_minor is 1: the other end is ECDSA capable,
464 * but doesn't know our key yet. So send it now. */
466 char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
471 bool result = send_request(c, "%d %s", ACK, pubkey);
476 bool send_ack(connection_t *c) {
477 if(c->protocol_minor == 1)
478 return send_upgrade(c);
480 /* ACK message contains rest of the information the other end needs
481 to create node_t and edge_t structures. */
486 /* Estimate weight */
488 gettimeofday(&now, NULL);
489 c->estimated_weight = (now.tv_sec - c->start.tv_sec) * 1000 + (now.tv_usec - c->start.tv_usec) / 1000;
491 /* Check some options */
493 if((get_config_bool(lookup_config(c->config_tree, "IndirectData"), &choice) && choice) || myself->options & OPTION_INDIRECT)
494 c->options |= OPTION_INDIRECT;
496 if((get_config_bool(lookup_config(c->config_tree, "TCPOnly"), &choice) && choice) || myself->options & OPTION_TCPONLY)
497 c->options |= OPTION_TCPONLY | OPTION_INDIRECT;
499 if(myself->options & OPTION_PMTU_DISCOVERY)
500 c->options |= OPTION_PMTU_DISCOVERY;
502 choice = myself->options & OPTION_CLAMP_MSS;
503 get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice);
505 c->options |= OPTION_CLAMP_MSS;
507 get_config_int(lookup_config(c->config_tree, "Weight"), &c->estimated_weight);
509 return send_request(c, "%d %s %d %x", ACK, myport, c->estimated_weight, c->options);
512 static void send_everything(connection_t *c) {
513 splay_node_t *node, *node2;
518 /* Send all known subnets and edges */
521 for(node = myself->subnet_tree->head; node; node = node->next) {
523 send_add_subnet(c, s);
529 for(node = node_tree->head; node; node = node->next) {
532 for(node2 = n->subnet_tree->head; node2; node2 = node2->next) {
534 send_add_subnet(c, s);
537 for(node2 = n->edge_tree->head; node2; node2 = node2->next) {
544 static bool upgrade_h(connection_t *c, char *request) {
545 char pubkey[MAX_STRING_SIZE];
547 if(sscanf(request, "%*d " MAX_STRING, pubkey) != 1) {
548 logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name, c->hostname);
552 if(ecdsa_active(&c->ecdsa) || read_ecdsa_public_key(c)) {
553 logger(LOG_INFO, "Already have ECDSA public key from %s (%s), not upgrading.", c->name, c->hostname);
557 logger(LOG_INFO, "Got ECDSA public key from %s (%s), upgrading!", c->name, c->hostname);
558 append_connection_config(c, "ECDSAPublicKey", pubkey);
559 c->allow_request = TERMREQ;
560 return send_termreq(c);
563 bool ack_h(connection_t *c, char *request) {
564 if(c->protocol_minor == 1)
565 return upgrade_h(c, request);
567 char hisport[MAX_STRING_SIZE];
574 if(sscanf(request, "%*d " MAX_STRING " %d %x", hisport, &weight, &options) != 3) {
575 logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name,
580 /* Check if we already have a node_t for him */
582 n = lookup_node(c->name);
586 n->name = xstrdup(c->name);
590 /* Oh dear, we already have a connection to this node. */
591 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Established a second connection with %s (%s), closing old connection", n->connection->name, n->connection->hostname);
593 if(n->connection->outgoing) {
595 logger(LOG_WARNING, "Two outgoing connections to the same node!");
597 c->outgoing = n->connection->outgoing;
599 n->connection->outgoing = NULL;
602 terminate_connection(n->connection, false);
603 /* Run graph algorithm to purge key and make sure up/down scripts are rerun with new IP addresses and stuff */
610 if(!(c->options & options & OPTION_PMTU_DISCOVERY)) {
611 c->options &= ~OPTION_PMTU_DISCOVERY;
612 options &= ~OPTION_PMTU_DISCOVERY;
614 c->options |= options;
616 if(get_config_int(lookup_config(c->config_tree, "PMTU"), &mtu) && mtu < n->mtu)
619 if(get_config_int(lookup_config(config_tree, "PMTU"), &mtu) && mtu < n->mtu)
622 if(get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice)) {
624 c->options |= OPTION_CLAMP_MSS;
626 c->options &= ~OPTION_CLAMP_MSS;
629 if(c->protocol_minor > 0)
630 c->node->status.ecdh = true;
632 /* Activate this connection */
634 c->allow_request = ALL;
635 c->status.active = true;
637 ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection with %s (%s) activated", c->name,
640 /* Send him everything we know */
644 /* Create an edge_t for this connection */
646 c->edge = new_edge();
647 c->edge->from = myself;
649 sockaddr2str(&c->address, &hisaddress, NULL);
650 c->edge->address = str2sockaddr(hisaddress, hisport);
652 c->edge->weight = (weight + c->estimated_weight) / 2;
653 c->edge->connection = c;
654 c->edge->options = c->options;
658 /* Notify everyone of the new edge */
661 send_add_edge(c, c->edge);
663 send_add_edge(broadcast, c->edge);
665 /* Run MST and SSSP algorithms */