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 if(experimental && OPTION_VERSION(to->options) >= 2) {
88 if(!node_read_ecdsa_public_key(to))
89 send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
91 return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
94 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
96 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
99 char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
100 send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
106 if(node_read_ecdsa_public_key(from)) {
107 logger(DEBUG_ALWAYS, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
112 if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
113 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
117 logger(DEBUG_ALWAYS, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
118 append_config_file(from->name, "ECDSAPublicKey", pubkey);
123 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
128 bool req_key_h(connection_t *c, const char *request) {
129 char from_name[MAX_STRING_SIZE];
130 char to_name[MAX_STRING_SIZE];
134 if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
135 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
140 if(!check_id(from_name) || !check_id(to_name)) {
141 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
145 from = lookup_node(from_name);
148 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
149 "REQ_KEY", c->name, c->hostname, from_name);
153 to = lookup_node(to_name);
156 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
157 "REQ_KEY", c->name, c->hostname, to_name);
161 /* Check if this key request is for us */
163 if(to == myself) { /* Yes, send our own key back */
164 if(experimental && reqno)
165 return req_key_ext_h(c, request, from, reqno);
172 if(!to->status.reachable) {
173 logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
174 "REQ_KEY", c->name, c->hostname, to_name);
178 send_request(to->nexthop->connection, "%s", request);
184 bool send_ans_key_ecdh(node_t *to) {
185 int siglen = ecdsa_size(&myself->connection->ecdsa);
186 char key[(ECDH_SIZE + siglen) * 2 + 1];
188 if(!ecdh_generate_public(&to->ecdh, key))
191 if(!ecdsa_sign(&myself->connection->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE))
194 b64encode(key, key, ECDH_SIZE + siglen);
196 int result = send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
197 myself->name, to->name, key,
198 cipher_get_nid(&myself->incipher),
199 digest_get_nid(&myself->indigest),
200 digest_length(&myself->indigest),
201 myself->incompression);
206 bool send_ans_key(node_t *to) {
207 if(experimental && OPTION_VERSION(to->options) >= 2)
208 return send_ans_key_ecdh(to);
210 size_t keylen = cipher_keylength(&myself->incipher);
211 char key[keylen * 2 + 1];
213 cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
214 digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
215 to->incompression = myself->incompression;
217 randomize(key, keylen);
218 cipher_set_key(&to->incipher, key, false);
219 digest_set_key(&to->indigest, key, keylen);
221 bin2hex(key, key, keylen);
223 // Reset sequence number and late packet window
225 to->received_seqno = 0;
226 if(replaywin) memset(to->late, 0, replaywin);
228 return send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
229 myself->name, to->name, key,
230 cipher_get_nid(&to->incipher),
231 digest_get_nid(&to->indigest),
232 digest_length(&to->indigest),
236 bool ans_key_h(connection_t *c, const char *request) {
237 char from_name[MAX_STRING_SIZE];
238 char to_name[MAX_STRING_SIZE];
239 char key[MAX_STRING_SIZE];
240 char address[MAX_STRING_SIZE] = "";
241 char port[MAX_STRING_SIZE] = "";
242 int cipher, digest, maclength, compression, keylen;
245 if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
246 from_name, to_name, key, &cipher, &digest, &maclength,
247 &compression, address, port) < 7) {
248 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
253 if(!check_id(from_name) || !check_id(to_name)) {
254 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
258 from = lookup_node(from_name);
261 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
262 "ANS_KEY", c->name, c->hostname, from_name);
266 to = lookup_node(to_name);
269 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
270 "ANS_KEY", c->name, c->hostname, to_name);
274 /* Forward it if necessary */
280 if(!to->status.reachable) {
281 logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
282 "ANS_KEY", c->name, c->hostname, to_name);
286 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
287 char *address, *port;
288 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
289 sockaddr2str(&from->address, &address, &port);
290 send_request(to->nexthop->connection, "%s %s %s", request, address, port);
296 return send_request(to->nexthop->connection, "%s", request);
299 /* Check and lookup cipher and digest algorithms */
301 if(!cipher_open_by_nid(&from->outcipher, cipher)) {
302 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
306 if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
307 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
311 if(maclength != digest_length(&from->outdigest)) {
312 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
316 if(compression < 0 || compression > 11) {
317 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
321 from->outcompression = compression;
323 /* ECDH or old-style key exchange? */
325 if(experimental && OPTION_VERSION(from->options) >= 2) {
326 /* Check if we already have an ECDSA public key for this node. */
328 if(!node_read_ecdsa_public_key(from)) {
329 logger(DEBUG_ALWAYS, LOG_ERR, "No ECDSA public key known for %s (%s), cannot verify ECDH key exchange!", from->name, from->hostname);
333 int siglen = ecdsa_size(&from->ecdsa);
334 int keylen = b64decode(key, key, sizeof key);
336 if(keylen != ECDH_SIZE + siglen) {
337 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength! %d != %d", from->name, from->hostname, keylen, ECDH_SIZE + siglen);
341 if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) {
342 logger(DEBUG_ALWAYS, LOG_ERR, "ECDH key too short for cipher of %s!", from->name);
346 if(!ecdsa_verify(&from->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE)) {
347 logger(DEBUG_ALWAYS, LOG_ERR, "Possible intruder %s (%s): %s", from->name, from->hostname, "invalid ECDSA signature");
352 if(!send_ans_key_ecdh(from))
356 char shared[ECDH_SHARED_SIZE * 2 + 1];
358 if(!ecdh_compute_shared(&from->ecdh, key, shared))
361 /* Update our crypto end */
363 size_t mykeylen = cipher_keylength(&myself->incipher);
364 size_t hiskeylen = cipher_keylength(&from->outcipher);
370 if(strcmp(myself->name, from->name) < 0) {
372 hiskey = key + mykeylen * 2;
373 xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
375 mykey = key + hiskeylen * 2;
377 xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name);
380 if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
385 cipher_open_by_nid(&from->incipher, cipher_get_nid(&myself->incipher));
386 digest_open_by_nid(&from->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
387 from->incompression = myself->incompression;
389 cipher_set_key(&from->incipher, mykey, false);
390 digest_set_key(&from->indigest, mykey + mykeylen, mykeylen);
392 cipher_set_key(&from->outcipher, hiskey, true);
393 digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen);
395 // Reset sequence number and late packet window
397 from->received_seqno = 0;
399 memset(from->late, 0, replaywin);
401 if(strcmp(myself->name, from->name) < 0)
402 memmove(key, key + mykeylen * 2, hiskeylen * 2);
404 keylen = hex2bin(key, key, sizeof key);
406 if(keylen != cipher_keylength(&from->outcipher)) {
407 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
411 /* Update our copy of the origin's packet key */
413 cipher_set_key(&from->outcipher, key, true);
414 digest_set_key(&from->outdigest, key, keylen);
417 from->status.validkey = true;
418 from->sent_seqno = 0;
420 if(*address && *port) {
421 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
422 sockaddr_t sa = str2sockaddr(address, port);
423 update_node_udp(from, &sa);
426 if(from->options & OPTION_PMTU_DISCOVERY)
427 send_mtu_probe(from);