2 protocol_auth.c -- handle the meta-protocol, authentication
3 Copyright (C) 1999-2005 Ivo Timmermans,
4 2000-2016 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 <openssl/sha.h>
24 #include <openssl/rand.h>
25 #include <openssl/err.h>
26 #include <openssl/evp.h>
30 #include "connection.h"
43 bool send_id(connection_t *c) {
44 if(proxytype && c->outgoing && !c->status.proxy_passed)
45 return send_proxyrequest(c);
47 return send_request(c, "%d %s %d", ID, myself->connection->name,
48 myself->connection->protocol_version);
51 bool id_h(connection_t *c) {
52 char name[MAX_STRING_SIZE];
54 if(sscanf(c->buffer, "%*d " MAX_STRING " %d", name, &c->protocol_version) != 2) {
55 logger(LOG_ERR, "Got bad %s from %s (%s)", "ID", c->name,
60 /* Check if identity is a valid name */
63 logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ID", c->name,
64 c->hostname, "invalid name");
68 /* If this is an outgoing connection, make sure we are connected to the right host */
71 if(strcmp(c->name, name)) {
72 logger(LOG_ERR, "Peer %s is %s instead of %s", c->hostname, name,
79 c->name = xstrdup(name);
82 /* Check if version matches */
84 if(c->protocol_version != myself->connection->protocol_version) {
85 logger(LOG_ERR, "Peer %s (%s) uses incompatible version %d",
86 c->name, c->hostname, c->protocol_version);
92 init_configuration(&c->config_tree);
93 c->allow_request = ACK;
98 init_configuration(&c->config_tree);
100 if(!read_connection_config(c)) {
101 logger(LOG_ERR, "Peer %s had unknown identity (%s)", c->hostname,
107 if(!read_rsa_public_key(c)) {
111 c->allow_request = METAKEY;
113 return send_metakey(c);
116 bool send_metakey(connection_t *c) {
119 int len = RSA_size(c->rsa_key);
121 /* Allocate buffers for the meta key */
123 char buffer[2 * len + 1];
125 c->outkey = xrealloc(c->outkey, len);
128 c->outctx = EVP_CIPHER_CTX_new();
133 /* Copy random data to the buffer */
135 if (1 != RAND_bytes((unsigned char *)c->outkey, len)) {
136 int err = ERR_get_error();
137 logger(LOG_ERR, "Failed to generate meta key (%s)", ERR_error_string(err, NULL));
142 /* The message we send must be smaller than the modulus of the RSA key.
143 By definition, for a key of k bits, the following formula holds:
145 2^(k-1) <= modulus < 2^(k)
147 Where ^ means "to the power of", not "xor".
148 This means that to be sure, we must choose our message < 2^(k-1).
149 This can be done by setting the most significant bit to zero.
152 c->outkey[0] &= 0x7F;
154 ifdebug(SCARY_THINGS) {
155 bin2hex(c->outkey, buffer, len);
156 buffer[len * 2] = '\0';
157 logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s",
161 /* Encrypt the random data
163 We do not use one of the PKCS padding schemes here.
164 This is allowed, because we encrypt a totally random string
165 with a length equal to that of the modulus of the RSA key.
168 if(RSA_public_encrypt(len, (unsigned char *)c->outkey, (unsigned char *)buffer, c->rsa_key, RSA_NO_PADDING) != len) {
169 logger(LOG_ERR, "Error during encryption of meta key for %s (%s): %s",
170 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
174 /* Convert the encrypted random data to a hexadecimal formatted string */
176 bin2hex(buffer, buffer, len);
177 buffer[len * 2] = '\0';
179 /* Send the meta key */
181 x = send_request(c, "%d %d %d %d %d %s", METAKEY,
182 c->outcipher ? EVP_CIPHER_nid(c->outcipher) : 0,
183 c->outdigest ? EVP_MD_type(c->outdigest) : 0, c->outmaclength,
184 c->outcompression, buffer);
186 /* Further outgoing requests are encrypted with the key we just generated */
189 if(!EVP_EncryptInit(c->outctx, c->outcipher,
190 (unsigned char *)c->outkey + len - EVP_CIPHER_key_length(c->outcipher),
191 (unsigned char *)c->outkey + len - EVP_CIPHER_key_length(c->outcipher) -
192 EVP_CIPHER_iv_length(c->outcipher))) {
193 logger(LOG_ERR, "Error during initialisation of cipher for %s (%s): %s",
194 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
198 c->status.encryptout = true;
204 bool metakey_h(connection_t *c) {
205 char buffer[MAX_STRING_SIZE];
206 int cipher, digest, maclength, compression;
209 if(sscanf(c->buffer, "%*d %d %d %d %d " MAX_STRING, &cipher, &digest, &maclength, &compression, buffer) != 5) {
210 logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name,
215 len = RSA_size(myself->connection->rsa_key);
217 /* Check if the length of the meta key is all right */
219 if(strlen(buffer) != len * 2) {
220 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength");
224 /* Allocate buffers for the meta key */
226 c->inkey = xrealloc(c->inkey, len);
229 c->inctx = EVP_CIPHER_CTX_new();
234 /* Convert the challenge from hexadecimal back to binary */
236 if(!hex2bin(buffer, buffer, len)) {
237 logger(LOG_ERR, "Got bad %s from %s(%s): %s", "METAKEY", c->name, c->hostname, "invalid key");
241 /* Decrypt the meta key */
243 if(RSA_private_decrypt(len, (unsigned char *)buffer, (unsigned char *)c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) { /* See challenge() */
244 logger(LOG_ERR, "Error during decryption of meta key for %s (%s): %s",
245 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
249 ifdebug(SCARY_THINGS) {
250 bin2hex(c->inkey, buffer, len);
251 buffer[len * 2] = '\0';
252 logger(LOG_DEBUG, "Received random meta key (unencrypted): %s", buffer);
255 /* All incoming requests will now be encrypted. */
257 /* Check and lookup cipher and digest algorithms */
260 c->incipher = EVP_get_cipherbynid(cipher);
263 logger(LOG_ERR, "%s (%s) uses unknown cipher!", c->name, c->hostname);
267 if(!EVP_DecryptInit(c->inctx, c->incipher,
268 (unsigned char *)c->inkey + len - EVP_CIPHER_key_length(c->incipher),
269 (unsigned char *)c->inkey + len - EVP_CIPHER_key_length(c->incipher) -
270 EVP_CIPHER_iv_length(c->incipher))) {
271 logger(LOG_ERR, "Error during initialisation of cipher from %s (%s): %s",
272 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
276 c->status.decryptin = true;
281 c->inmaclength = maclength;
284 c->indigest = EVP_get_digestbynid(digest);
287 logger(LOG_ERR, "Node %s (%s) uses unknown digest!", c->name, c->hostname);
291 if(c->inmaclength > EVP_MD_size(c->indigest) || c->inmaclength < 0) {
292 logger(LOG_ERR, "%s (%s) uses bogus MAC length!", c->name, c->hostname);
299 c->incompression = compression;
301 c->allow_request = CHALLENGE;
303 return send_challenge(c);
306 bool send_challenge(connection_t *c) {
307 /* CHECKME: what is most reasonable value for len? */
309 int len = RSA_size(c->rsa_key);
311 /* Allocate buffers for the challenge */
313 char buffer[2 * len + 1];
315 c->hischallenge = xrealloc(c->hischallenge, len);
317 /* Copy random data to the buffer */
319 if (1 != RAND_bytes((unsigned char *)c->hischallenge, len)) {
320 int err = ERR_get_error();
321 logger(LOG_ERR, "Failed to generate challenge (%s)", ERR_error_string(err, NULL));
322 return false; // Do not send predictable challenges, let connection attempt fail.
327 bin2hex(c->hischallenge, buffer, len);
328 buffer[len * 2] = '\0';
330 /* Send the challenge */
332 return send_request(c, "%d %s", CHALLENGE, buffer);
335 bool challenge_h(connection_t *c) {
336 char buffer[MAX_STRING_SIZE];
339 if(sscanf(c->buffer, "%*d " MAX_STRING, buffer) != 1) {
340 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHALLENGE", c->name,
345 len = RSA_size(myself->connection->rsa_key);
347 /* Check if the length of the challenge is all right */
349 if(strlen(buffer) != len * 2) {
350 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
351 c->hostname, "wrong challenge length");
355 /* Allocate buffers for the challenge */
357 c->mychallenge = xrealloc(c->mychallenge, len);
359 /* Convert the challenge from hexadecimal back to binary */
361 if(!hex2bin(buffer, c->mychallenge, len)) {
362 logger(LOG_ERR, "Got bad %s from %s(%s): %s", "CHALLENGE", c->name, c->hostname, "invalid challenge");
366 c->allow_request = CHAL_REPLY;
368 /* Rest is done by send_chal_reply() */
370 return send_chal_reply(c);
373 bool send_chal_reply(connection_t *c) {
374 char hash[EVP_MAX_MD_SIZE * 2 + 1];
377 /* Calculate the hash from the challenge we received */
379 ctx = EVP_MD_CTX_create();
383 if(!EVP_DigestInit(ctx, c->indigest)
384 || !EVP_DigestUpdate(ctx, c->mychallenge, RSA_size(myself->connection->rsa_key))
385 || !EVP_DigestFinal(ctx, (unsigned char *)hash, NULL)) {
386 EVP_MD_CTX_destroy(ctx);
387 logger(LOG_ERR, "Error during calculation of response for %s (%s): %s",
388 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
392 EVP_MD_CTX_destroy(ctx);
394 /* Convert the hash to a hexadecimal formatted string */
396 bin2hex(hash, hash, EVP_MD_size(c->indigest));
397 hash[EVP_MD_size(c->indigest) * 2] = '\0';
401 return send_request(c, "%d %s", CHAL_REPLY, hash);
404 bool chal_reply_h(connection_t *c) {
405 char hishash[MAX_STRING_SIZE];
406 char myhash[EVP_MAX_MD_SIZE];
409 if(sscanf(c->buffer, "%*d " MAX_STRING, hishash) != 1) {
410 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHAL_REPLY", c->name,
415 /* Check if the length of the hash is all right */
417 if(strlen(hishash) != EVP_MD_size(c->outdigest) * 2) {
418 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
419 c->hostname, "wrong challenge reply length");
423 /* Convert the hash to binary format */
425 if(!hex2bin(hishash, hishash, EVP_MD_size(c->outdigest))) {
426 logger(LOG_ERR, "Got bad %s from %s(%s): %s", "CHAL_REPLY", c->name, c->hostname, "invalid hash");
430 /* Calculate the hash from the challenge we sent */
432 ctx = EVP_MD_CTX_create();
436 if(!EVP_DigestInit(ctx, c->outdigest)
437 || !EVP_DigestUpdate(ctx, c->hischallenge, RSA_size(c->rsa_key))
438 || !EVP_DigestFinal(ctx, (unsigned char *)myhash, NULL)) {
439 EVP_MD_CTX_destroy(ctx);
440 logger(LOG_ERR, "Error during calculation of response from %s (%s): %s",
441 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
445 EVP_MD_CTX_destroy(ctx);
447 /* Verify the incoming hash with the calculated hash */
449 if(memcmp(hishash, myhash, EVP_MD_size(c->outdigest))) {
450 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
451 c->hostname, "wrong challenge reply");
453 ifdebug(SCARY_THINGS) {
454 bin2hex(myhash, hishash, SHA_DIGEST_LENGTH);
455 hishash[SHA_DIGEST_LENGTH * 2] = '\0';
456 logger(LOG_DEBUG, "Expected challenge reply: %s", hishash);
462 /* Identity has now been positively verified.
463 Send an acknowledgement with the rest of the information needed.
466 c->allow_request = ACK;
471 bool send_ack(connection_t *c) {
472 /* ACK message contains rest of the information the other end needs
473 to create node_t and edge_t structures. */
478 /* Estimate weight */
480 gettimeofday(&now, NULL);
481 c->estimated_weight = (now.tv_sec - c->start.tv_sec) * 1000 + (now.tv_usec - c->start.tv_usec) / 1000;
483 /* Check some options */
485 if((get_config_bool(lookup_config(c->config_tree, "IndirectData"), &choice) && choice) || myself->options & OPTION_INDIRECT)
486 c->options |= OPTION_INDIRECT;
488 if((get_config_bool(lookup_config(c->config_tree, "TCPOnly"), &choice) && choice) || myself->options & OPTION_TCPONLY)
489 c->options |= OPTION_TCPONLY | OPTION_INDIRECT;
491 if(myself->options & OPTION_PMTU_DISCOVERY)
492 c->options |= OPTION_PMTU_DISCOVERY;
494 choice = myself->options & OPTION_CLAMP_MSS;
495 get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice);
497 c->options |= OPTION_CLAMP_MSS;
499 get_config_int(lookup_config(c->config_tree, "Weight"), &c->estimated_weight);
501 return send_request(c, "%d %s %d %x", ACK, myport, c->estimated_weight, c->options);
504 static void send_everything(connection_t *c) {
505 avl_node_t *node, *node2;
510 /* Send all known subnets and edges */
513 for(node = myself->subnet_tree->head; node; node = node->next) {
515 send_add_subnet(c, s);
521 for(node = node_tree->head; node; node = node->next) {
524 for(node2 = n->subnet_tree->head; node2; node2 = node2->next) {
526 send_add_subnet(c, s);
529 for(node2 = n->edge_tree->head; node2; node2 = node2->next) {
536 bool ack_h(connection_t *c) {
537 char hisport[MAX_STRING_SIZE];
543 if(sscanf(c->buffer, "%*d " MAX_STRING " %d %x", hisport, &weight, &options) != 3) {
544 logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name,
549 /* Check if we already have a node_t for him */
551 n = lookup_node(c->name);
555 n->name = xstrdup(c->name);
559 /* Oh dear, we already have a connection to this node. */
560 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Established a second connection with %s (%s), closing old connection",
561 n->name, n->hostname);
562 terminate_connection(n->connection, false);
563 /* Run graph algorithm to purge key and make sure up/down scripts are rerun with new IP addresses and stuff */
570 if(!(c->options & options & OPTION_PMTU_DISCOVERY)) {
571 c->options &= ~OPTION_PMTU_DISCOVERY;
572 options &= ~OPTION_PMTU_DISCOVERY;
574 c->options |= options;
576 if(get_config_int(lookup_config(c->config_tree, "PMTU"), &mtu) && mtu < n->mtu)
579 if(get_config_int(lookup_config(config_tree, "PMTU"), &mtu) && mtu < n->mtu)
582 if(get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice)) {
584 c->options |= OPTION_CLAMP_MSS;
586 c->options &= ~OPTION_CLAMP_MSS;
589 /* Activate this connection */
591 c->allow_request = ALL;
592 c->status.active = true;
594 ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection with %s (%s) activated", c->name,
597 /* Send him everything we know */
601 /* Create an edge_t for this connection */
603 c->edge = new_edge();
604 c->edge->from = myself;
606 sockaddrcpy(&c->edge->address, &c->address);
607 sockaddr_setport(&c->edge->address, hisport);
608 c->edge->weight = (weight + c->estimated_weight) / 2;
609 c->edge->connection = c;
610 c->edge->options = c->options;
614 /* Notify everyone of the new edge */
617 send_add_edge(c, c->edge);
619 send_add_edge(everyone, c->edge);
621 /* Run MST and SSSP algorithms */