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 <openssl/sha.h>
24 #include <openssl/rand.h>
25 #include <openssl/err.h>
26 #include <openssl/evp.h>
30 #include "connection.h"
41 bool send_id(connection_t *c) {
42 return send_request(c, "%d %s %d", ID, myself->connection->name,
43 myself->connection->protocol_version);
46 bool id_h(connection_t *c) {
47 char name[MAX_STRING_SIZE];
49 if(sscanf(c->buffer, "%*d " MAX_STRING " %d", name, &c->protocol_version) != 2) {
50 logger(LOG_ERR, "Got bad %s from %s (%s)", "ID", c->name,
55 /* Check if identity is a valid name */
58 logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ID", c->name,
59 c->hostname, "invalid name");
63 /* If this is an outgoing connection, make sure we are connected to the right host */
66 if(strcmp(c->name, name)) {
67 logger(LOG_ERR, "Peer %s is %s instead of %s", c->hostname, name,
74 c->name = xstrdup(name);
77 /* Check if version matches */
79 if(c->protocol_version != myself->connection->protocol_version) {
80 logger(LOG_ERR, "Peer %s (%s) uses incompatible version %d",
81 c->name, c->hostname, c->protocol_version);
87 init_configuration(&c->config_tree);
88 c->allow_request = ACK;
93 init_configuration(&c->config_tree);
95 if(!read_connection_config(c)) {
96 logger(LOG_ERR, "Peer %s had unknown identity (%s)", c->hostname,
102 if(!read_rsa_public_key(c)) {
106 c->allow_request = METAKEY;
108 return send_metakey(c);
111 bool send_metakey(connection_t *c) {
116 len = RSA_size(c->rsa_key);
118 /* Allocate buffers for the meta key */
120 buffer = alloca(2 * len + 1);
122 c->outkey = xrealloc(c->outkey, len);
125 c->outctx = xmalloc_and_zero(sizeof(*c->outctx));
127 /* Copy random data to the buffer */
129 RAND_pseudo_bytes((unsigned char *)c->outkey, len);
131 /* The message we send must be smaller than the modulus of the RSA key.
132 By definition, for a key of k bits, the following formula holds:
134 2^(k-1) <= modulus < 2^(k)
136 Where ^ means "to the power of", not "xor".
137 This means that to be sure, we must choose our message < 2^(k-1).
138 This can be done by setting the most significant bit to zero.
141 c->outkey[0] &= 0x7F;
143 ifdebug(SCARY_THINGS) {
144 bin2hex(c->outkey, buffer, len);
145 buffer[len * 2] = '\0';
146 logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s",
150 /* Encrypt the random data
152 We do not use one of the PKCS padding schemes here.
153 This is allowed, because we encrypt a totally random string
154 with a length equal to that of the modulus of the RSA key.
157 if(RSA_public_encrypt(len, (unsigned char *)c->outkey, (unsigned char *)buffer, c->rsa_key, RSA_NO_PADDING) != len) {
158 logger(LOG_ERR, "Error during encryption of meta key for %s (%s)",
159 c->name, c->hostname);
163 /* Convert the encrypted random data to a hexadecimal formatted string */
165 bin2hex(buffer, buffer, len);
166 buffer[len * 2] = '\0';
168 /* Send the meta key */
170 x = send_request(c, "%d %d %d %d %d %s", METAKEY,
171 c->outcipher ? c->outcipher->nid : 0,
172 c->outdigest ? c->outdigest->type : 0, c->outmaclength,
173 c->outcompression, buffer);
175 /* Further outgoing requests are encrypted with the key we just generated */
178 if(!EVP_EncryptInit(c->outctx, c->outcipher,
179 (unsigned char *)c->outkey + len - c->outcipher->key_len,
180 (unsigned char *)c->outkey + len - c->outcipher->key_len -
181 c->outcipher->iv_len)) {
182 logger(LOG_ERR, "Error during initialisation of cipher for %s (%s): %s",
183 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
187 c->status.encryptout = true;
193 bool metakey_h(connection_t *c) {
194 char buffer[MAX_STRING_SIZE];
195 int cipher, digest, maclength, compression;
198 if(sscanf(c->buffer, "%*d %d %d %d %d " MAX_STRING, &cipher, &digest, &maclength, &compression, buffer) != 5) {
199 logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name,
204 len = RSA_size(myself->connection->rsa_key);
206 /* Check if the length of the meta key is all right */
208 if(strlen(buffer) != len * 2) {
209 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength");
213 /* Allocate buffers for the meta key */
215 c->inkey = xrealloc(c->inkey, len);
218 c->inctx = xmalloc_and_zero(sizeof(*c->inctx));
220 /* Convert the challenge from hexadecimal back to binary */
222 hex2bin(buffer, buffer, len);
224 /* Decrypt the meta key */
226 if(RSA_private_decrypt(len, (unsigned char *)buffer, (unsigned char *)c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) { /* See challenge() */
227 logger(LOG_ERR, "Error during decryption of meta key for %s (%s)",
228 c->name, c->hostname);
232 ifdebug(SCARY_THINGS) {
233 bin2hex(c->inkey, buffer, len);
234 buffer[len * 2] = '\0';
235 logger(LOG_DEBUG, "Received random meta key (unencrypted): %s", buffer);
238 /* All incoming requests will now be encrypted. */
240 /* Check and lookup cipher and digest algorithms */
243 c->incipher = EVP_get_cipherbynid(cipher);
246 logger(LOG_ERR, "%s (%s) uses unknown cipher!", c->name, c->hostname);
250 if(!EVP_DecryptInit(c->inctx, c->incipher,
251 (unsigned char *)c->inkey + len - c->incipher->key_len,
252 (unsigned char *)c->inkey + len - c->incipher->key_len -
253 c->incipher->iv_len)) {
254 logger(LOG_ERR, "Error during initialisation of cipher from %s (%s): %s",
255 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
259 c->status.decryptin = true;
264 c->inmaclength = maclength;
267 c->indigest = EVP_get_digestbynid(digest);
270 logger(LOG_ERR, "Node %s (%s) uses unknown digest!", c->name, c->hostname);
274 if(c->inmaclength > c->indigest->md_size || c->inmaclength < 0) {
275 logger(LOG_ERR, "%s (%s) uses bogus MAC length!", c->name, c->hostname);
282 c->incompression = compression;
284 c->allow_request = CHALLENGE;
286 return send_challenge(c);
289 bool send_challenge(connection_t *c) {
293 /* CHECKME: what is most reasonable value for len? */
295 len = RSA_size(c->rsa_key);
297 /* Allocate buffers for the challenge */
299 buffer = alloca(2 * len + 1);
301 c->hischallenge = xrealloc(c->hischallenge, len);
303 /* Copy random data to the buffer */
305 RAND_pseudo_bytes((unsigned char *)c->hischallenge, len);
309 bin2hex(c->hischallenge, buffer, len);
310 buffer[len * 2] = '\0';
312 /* Send the challenge */
314 return send_request(c, "%d %s", CHALLENGE, buffer);
317 bool challenge_h(connection_t *c) {
318 char buffer[MAX_STRING_SIZE];
321 if(sscanf(c->buffer, "%*d " MAX_STRING, buffer) != 1) {
322 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHALLENGE", c->name,
327 len = RSA_size(myself->connection->rsa_key);
329 /* Check if the length of the challenge is all right */
331 if(strlen(buffer) != len * 2) {
332 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
333 c->hostname, "wrong challenge length");
337 /* Allocate buffers for the challenge */
339 c->mychallenge = xrealloc(c->mychallenge, len);
341 /* Convert the challenge from hexadecimal back to binary */
343 hex2bin(buffer, c->mychallenge, len);
345 c->allow_request = CHAL_REPLY;
347 /* Rest is done by send_chal_reply() */
349 return send_chal_reply(c);
352 bool send_chal_reply(connection_t *c) {
353 char hash[EVP_MAX_MD_SIZE * 2 + 1];
356 /* Calculate the hash from the challenge we received */
358 if(!EVP_DigestInit(&ctx, c->indigest)
359 || !EVP_DigestUpdate(&ctx, c->mychallenge, RSA_size(myself->connection->rsa_key))
360 || !EVP_DigestFinal(&ctx, (unsigned char *)hash, NULL)) {
361 logger(LOG_ERR, "Error during calculation of response for %s (%s): %s",
362 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
366 /* Convert the hash to a hexadecimal formatted string */
368 bin2hex(hash, hash, c->indigest->md_size);
369 hash[c->indigest->md_size * 2] = '\0';
373 return send_request(c, "%d %s", CHAL_REPLY, hash);
376 bool chal_reply_h(connection_t *c) {
377 char hishash[MAX_STRING_SIZE];
378 char myhash[EVP_MAX_MD_SIZE];
381 if(sscanf(c->buffer, "%*d " MAX_STRING, hishash) != 1) {
382 logger(LOG_ERR, "Got bad %s from %s (%s)", "CHAL_REPLY", c->name,
387 /* Check if the length of the hash is all right */
389 if(strlen(hishash) != c->outdigest->md_size * 2) {
390 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
391 c->hostname, "wrong challenge reply length");
395 /* Convert the hash to binary format */
397 hex2bin(hishash, hishash, c->outdigest->md_size);
399 /* Calculate the hash from the challenge we sent */
401 if(!EVP_DigestInit(&ctx, c->outdigest)
402 || !EVP_DigestUpdate(&ctx, c->hischallenge, RSA_size(c->rsa_key))
403 || !EVP_DigestFinal(&ctx, (unsigned char *)myhash, NULL)) {
404 logger(LOG_ERR, "Error during calculation of response from %s (%s): %s",
405 c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
409 /* Verify the incoming hash with the calculated hash */
411 if(memcmp(hishash, myhash, c->outdigest->md_size)) {
412 logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name,
413 c->hostname, "wrong challenge reply");
415 ifdebug(SCARY_THINGS) {
416 bin2hex(myhash, hishash, SHA_DIGEST_LENGTH);
417 hishash[SHA_DIGEST_LENGTH * 2] = '\0';
418 logger(LOG_DEBUG, "Expected challenge reply: %s", hishash);
424 /* Identity has now been positively verified.
425 Send an acknowledgement with the rest of the information needed.
428 c->allow_request = ACK;
433 bool send_ack(connection_t *c) {
434 /* ACK message contains rest of the information the other end needs
435 to create node_t and edge_t structures. */
440 /* Estimate weight */
442 gettimeofday(&now, NULL);
443 c->estimated_weight = (now.tv_sec - c->start.tv_sec) * 1000 + (now.tv_usec - c->start.tv_usec) / 1000;
445 /* Check some options */
447 if((get_config_bool(lookup_config(c->config_tree, "IndirectData"), &choice) && choice) || myself->options & OPTION_INDIRECT)
448 c->options |= OPTION_INDIRECT;
450 if((get_config_bool(lookup_config(c->config_tree, "TCPOnly"), &choice) && choice) || myself->options & OPTION_TCPONLY)
451 c->options |= OPTION_TCPONLY | OPTION_INDIRECT;
453 if(myself->options & OPTION_PMTU_DISCOVERY)
454 c->options |= OPTION_PMTU_DISCOVERY;
456 choice = myself->options & OPTION_CLAMP_MSS;
457 get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice);
459 c->options |= OPTION_CLAMP_MSS;
461 get_config_int(lookup_config(c->config_tree, "Weight"), &c->estimated_weight);
463 return send_request(c, "%d %s %d %x", ACK, myport, c->estimated_weight, c->options);
466 static void send_everything(connection_t *c) {
467 avl_node_t *node, *node2;
472 /* Send all known subnets and edges */
475 for(node = myself->subnet_tree->head; node; node = node->next) {
477 send_add_subnet(c, s);
483 for(node = node_tree->head; node; node = node->next) {
486 for(node2 = n->subnet_tree->head; node2; node2 = node2->next) {
488 send_add_subnet(c, s);
491 for(node2 = n->edge_tree->head; node2; node2 = node2->next) {
498 bool ack_h(connection_t *c) {
499 char hisport[MAX_STRING_SIZE];
500 char *hisaddress, *dummy;
506 if(sscanf(c->buffer, "%*d " MAX_STRING " %d %x", hisport, &weight, &options) != 3) {
507 logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name,
512 /* Check if we already have a node_t for him */
514 n = lookup_node(c->name);
518 n->name = xstrdup(c->name);
522 /* Oh dear, we already have a connection to this node. */
523 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Established a second connection with %s (%s), closing old connection",
524 n->name, n->hostname);
525 terminate_connection(n->connection, false);
526 /* Run graph algorithm to purge key and make sure up/down scripts are rerun with new IP addresses and stuff */
533 if(!(c->options & options & OPTION_PMTU_DISCOVERY)) {
534 c->options &= ~OPTION_PMTU_DISCOVERY;
535 options &= ~OPTION_PMTU_DISCOVERY;
537 c->options |= options;
539 if(get_config_int(lookup_config(c->config_tree, "PMTU"), &mtu) && mtu < n->mtu)
542 if(get_config_int(lookup_config(myself->connection->config_tree, "PMTU"), &mtu) && mtu < n->mtu)
545 if(get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice)) {
547 c->options |= OPTION_CLAMP_MSS;
549 c->options &= ~OPTION_CLAMP_MSS;
552 /* Activate this connection */
554 c->allow_request = ALL;
555 c->status.active = true;
557 ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection with %s (%s) activated", c->name,
560 /* Send him everything we know */
564 /* Create an edge_t for this connection */
566 c->edge = new_edge();
567 c->edge->from = myself;
569 sockaddr2str(&c->address, &hisaddress, &dummy);
570 c->edge->address = str2sockaddr(hisaddress, hisport);
573 c->edge->weight = (weight + c->estimated_weight) / 2;
574 c->edge->connection = c;
575 c->edge->options = c->options;
579 /* Notify everyone of the new edge */
582 send_add_edge(c, c->edge);
584 send_add_edge(broadcast, c->edge);
586 /* Run MST and SSSP algorithms */