2 protocol_key.c -- handle the meta-protocol, key exchange
3 Copyright (C) 1999-2005 Ivo Timmermans,
4 2000-2012 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"
37 static bool mykeyused = false;
39 void send_key_changed(void) {
43 send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
45 /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
47 for(node = connection_tree->head; node; node = node->next) {
49 if(c->status.active && c->node && c->node->status.reachable)
50 send_ans_key(c->node);
54 bool key_changed_h(connection_t *c, const char *request) {
55 char name[MAX_STRING_SIZE];
58 if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
59 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
60 c->name, c->hostname);
64 if(seen_request(request))
67 n = lookup_node(name);
70 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
71 "KEY_CHANGED", c->name, c->hostname, name);
75 n->status.validkey = false;
81 forward_request(c, request);
86 bool send_req_key(node_t *to) {
87 return send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, experimental ? 1 : 0);
90 bool req_key_h(connection_t *c, const char *request) {
91 char from_name[MAX_STRING_SIZE];
92 char to_name[MAX_STRING_SIZE];
96 if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &kx_version) < 2) {
97 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
102 if(!check_id(from_name) || !check_id(to_name)) {
103 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
107 from = lookup_node(from_name);
110 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
111 "REQ_KEY", c->name, c->hostname, from_name);
115 to = lookup_node(to_name);
118 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
119 "REQ_KEY", c->name, c->hostname, to_name);
123 /* Check if this key request is for us */
125 if(to == myself) { /* Yes, send our own key back */
126 if(experimental && kx_version >= 1) {
127 logger(DEBUG_ALWAYS, LOG_DEBUG, "Got ECDH key request from %s", from->name);
128 from->status.ecdh = true;
135 if(!to->status.reachable) {
136 logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
137 "REQ_KEY", c->name, c->hostname, to_name);
141 send_request(to->nexthop->connection, "%s", request);
147 bool send_ans_key_ecdh(node_t *to) {
148 int siglen = ecdsa_size(&myself->connection->ecdsa);
149 char key[(ECDH_SIZE + siglen) * 2 + 1];
151 if(!ecdh_generate_public(&to->ecdh, key))
154 if(!ecdsa_sign(&myself->connection->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE))
157 b64encode(key, key, ECDH_SIZE + siglen);
159 char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
164 int result = send_request(to->nexthop->connection, "%d %s %s ECDH:%s:%s %d %d %zu %d", ANS_KEY,
165 myself->name, to->name, key, pubkey,
166 cipher_get_nid(&myself->incipher),
167 digest_get_nid(&myself->indigest),
168 digest_length(&myself->indigest),
169 myself->incompression);
175 bool send_ans_key(node_t *to) {
176 if(experimental && to->status.ecdh)
177 return send_ans_key_ecdh(to);
179 size_t keylen = cipher_keylength(&myself->incipher);
180 char key[keylen * 2 + 1];
182 cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
183 digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
184 to->incompression = myself->incompression;
186 randomize(key, keylen);
187 cipher_set_key(&to->incipher, key, false);
188 digest_set_key(&to->indigest, key, keylen);
190 bin2hex(key, key, keylen);
192 // Reset sequence number and late packet window
194 to->received_seqno = 0;
195 if(replaywin) memset(to->late, 0, replaywin);
197 return send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
198 myself->name, to->name, key,
199 cipher_get_nid(&to->incipher),
200 digest_get_nid(&to->indigest),
201 digest_length(&to->indigest),
205 bool ans_key_h(connection_t *c, const char *request) {
206 char from_name[MAX_STRING_SIZE];
207 char to_name[MAX_STRING_SIZE];
208 char key[MAX_STRING_SIZE];
209 char address[MAX_STRING_SIZE] = "";
210 char port[MAX_STRING_SIZE] = "";
211 int cipher, digest, maclength, compression, keylen;
214 if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
215 from_name, to_name, key, &cipher, &digest, &maclength,
216 &compression, address, port) < 7) {
217 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
222 if(!check_id(from_name) || !check_id(to_name)) {
223 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
227 from = lookup_node(from_name);
230 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
231 "ANS_KEY", c->name, c->hostname, from_name);
235 to = lookup_node(to_name);
238 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
239 "ANS_KEY", c->name, c->hostname, to_name);
243 /* Forward it if necessary */
249 if(!to->status.reachable) {
250 logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
251 "ANS_KEY", c->name, c->hostname, to_name);
255 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
256 char *address, *port;
257 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
258 sockaddr2str(&from->address, &address, &port);
259 send_request(to->nexthop->connection, "%s %s %s", request, address, port);
265 return send_request(to->nexthop->connection, "%s", request);
268 /* Check and lookup cipher and digest algorithms */
270 if(!cipher_open_by_nid(&from->outcipher, cipher)) {
271 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
275 if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
276 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
280 if(maclength != digest_length(&from->outdigest)) {
281 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
285 if(compression < 0 || compression > 11) {
286 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
290 from->outcompression = compression;
292 /* ECDH or old-style key exchange? */
294 if(experimental && !strncmp(key, "ECDH:", 5)) {
295 char *pubkey = strchr(key + 5, ':');
299 /* Check if we already have an ECDSA public key for this node.
300 * If not, use the one from the key exchange, and store it. */
302 if(!node_read_ecdsa_public_key(from)) {
304 logger(DEBUG_ALWAYS, LOG_ERR, "No ECDSA public key known for %s (%s), cannot verify ECDH key exchange!", from->name, from->hostname);
308 if(!ecdsa_set_base64_public_key(&from->ecdsa, pubkey))
311 append_config_file(from->name, "ECDSAPublicKey", pubkey);
314 int siglen = ecdsa_size(&from->ecdsa);
315 int keylen = b64decode(key + 5, key + 5, sizeof key - 5);
317 if(keylen != ECDH_SIZE + siglen) {
318 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength! %d != %d", from->name, from->hostname, keylen, ECDH_SIZE + siglen);
322 if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) {
323 logger(DEBUG_ALWAYS, LOG_ERR, "ECDH key too short for cipher of %s!", from->name);
327 if(!ecdsa_verify(&from->ecdsa, key + 5, ECDH_SIZE, key + 5 + ECDH_SIZE)) {
328 logger(DEBUG_ALWAYS, LOG_ERR, "Possible intruder %s (%s): %s", from->name, from->hostname, "invalid ECDSA signature");
333 from->status.ecdh = true;
334 if(!send_ans_key(from))
338 char shared[ECDH_SHARED_SIZE * 2 + 1];
340 if(!ecdh_compute_shared(&from->ecdh, key + 5, shared))
343 /* Update our crypto end */
345 size_t mykeylen = cipher_keylength(&myself->incipher);
346 size_t hiskeylen = cipher_keylength(&from->outcipher);
352 if(strcmp(myself->name, from->name) < 0) {
354 hiskey = key + mykeylen * 2;
355 xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
357 mykey = key + hiskeylen * 2;
359 xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name);
362 if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
367 cipher_open_by_nid(&from->incipher, cipher_get_nid(&myself->incipher));
368 digest_open_by_nid(&from->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
369 from->incompression = myself->incompression;
371 cipher_set_key(&from->incipher, mykey, false);
372 digest_set_key(&from->indigest, mykey + mykeylen, mykeylen);
374 cipher_set_key(&from->outcipher, hiskey, true);
375 digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen);
377 // Reset sequence number and late packet window
379 from->received_seqno = 0;
381 memset(from->late, 0, replaywin);
383 if(strcmp(myself->name, from->name) < 0)
384 memmove(key, key + mykeylen * 2, hiskeylen * 2);
386 keylen = hex2bin(key, key, sizeof key);
388 if(keylen != cipher_keylength(&from->outcipher)) {
389 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
393 /* Update our copy of the origin's packet key */
395 cipher_set_key(&from->outcipher, key, true);
396 digest_set_key(&from->outdigest, key, keylen);
399 from->status.validkey = true;
400 from->sent_seqno = 0;
402 if(*address && *port) {
403 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
404 sockaddr_t sa = str2sockaddr(address, port);
405 update_node_udp(from, &sa);
408 if(from->options & OPTION_PMTU_DISCOVERY)
409 send_mtu_probe(from);