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- /*
- protocol_key.c -- handle the meta-protocol, key exchange
- Copyright (C) 1999-2005 Ivo Timmermans,
- 2000-2016 Guus Sliepen <guus@tinc-vpn.org>
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
- #include "system.h"
- #include <openssl/evp.h>
- #include <openssl/err.h>
- #include <openssl/rand.h>
- #include "avl_tree.h"
- #include "connection.h"
- #include "logger.h"
- #include "net.h"
- #include "netutl.h"
- #include "node.h"
- #include "protocol.h"
- #include "utils.h"
- #include "xalloc.h"
- static bool mykeyused = false;
- void send_key_changed(void) {
- avl_node_t *node;
- connection_t *c;
- send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
- /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
- for(node = connection_tree->head; node; node = node->next) {
- c = node->data;
- if(c->status.active && c->node && c->node->status.reachable) {
- send_ans_key(c->node);
- }
- }
- }
- bool key_changed_h(connection_t *c) {
- char name[MAX_STRING_SIZE];
- node_t *n;
- if(sscanf(c->buffer, "%*d %*x " MAX_STRING, name) != 1) {
- logger(LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
- c->name, c->hostname);
- return false;
- }
- if(!check_id(name)) {
- logger(LOG_ERR, "Got bad %s from %s (%s): %s", "KEY_CHANGED", c->name, c->hostname, "invalid name");
- return false;
- }
- if(seen_request(c->buffer)) {
- return true;
- }
- n = lookup_node(name);
- if(!n) {
- logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
- "KEY_CHANGED", c->name, c->hostname, name);
- return true;
- }
- n->status.validkey = false;
- n->last_req_key = 0;
- /* Tell the others */
- if(!tunnelserver) {
- forward_request(c);
- }
- return true;
- }
- bool send_req_key(node_t *to) {
- return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
- }
- bool req_key_h(connection_t *c) {
- char from_name[MAX_STRING_SIZE];
- char to_name[MAX_STRING_SIZE];
- node_t *from, *to;
- if(sscanf(c->buffer, "%*d " MAX_STRING " " MAX_STRING, from_name, to_name) != 2) {
- logger(LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
- c->hostname);
- return false;
- }
- if(!check_id(from_name) || !check_id(to_name)) {
- logger(LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
- return false;
- }
- from = lookup_node(from_name);
- if(!from) {
- logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
- "REQ_KEY", c->name, c->hostname, from_name);
- return true;
- }
- to = lookup_node(to_name);
- if(!to) {
- logger(LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
- "REQ_KEY", c->name, c->hostname, to_name);
- return true;
- }
- /* Check if this key request is for us */
- if(to == myself) { /* Yes, send our own key back */
- if(!from->status.reachable) {
- logger(LOG_WARNING, "Got %s from %s (%s) origin %s which is not reachable",
- "REQ_KEY", c->name, c->hostname, from_name);
- return true;
- }
- if(!send_ans_key(from)) {
- return false;
- }
- } else {
- if(tunnelserver) {
- return true;
- }
- if(!to->status.reachable) {
- logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
- "REQ_KEY", c->name, c->hostname, to_name);
- return true;
- }
- send_request(to->nexthop->connection, "%s", c->buffer);
- }
- return true;
- }
- bool send_ans_key(node_t *to) {
- // Set key parameters
- to->incipher = myself->incipher;
- to->inkeylength = myself->inkeylength;
- to->indigest = myself->indigest;
- to->inmaclength = myself->inmaclength;
- to->incompression = myself->incompression;
- // Allocate memory for key
- to->inkey = xrealloc(to->inkey, to->inkeylength);
- // Create a new key
- if(1 != RAND_bytes((unsigned char *)to->inkey, to->inkeylength)) {
- int err = ERR_get_error();
- logger(LOG_ERR, "Failed to generate random for key (%s)", ERR_error_string(err, NULL));
- return false; // Do not send insecure keys, let connection attempt fail.
- }
- if(to->incipher) {
- EVP_DecryptInit_ex(to->inctx, to->incipher, NULL, (unsigned char *)to->inkey, (unsigned char *)to->inkey + EVP_CIPHER_key_length(to->incipher));
- }
- // Reset sequence number and late packet window
- mykeyused = true;
- to->received_seqno = 0;
- if(replaywin) {
- memset(to->late, 0, replaywin);
- }
- // Convert to hexadecimal and send
- char key[2 * to->inkeylength + 1];
- bin2hex(to->inkey, key, to->inkeylength);
- key[to->inkeylength * 2] = '\0';
- return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
- myself->name, to->name, key,
- to->incipher ? EVP_CIPHER_nid(to->incipher) : 0,
- to->indigest ? EVP_MD_type(to->indigest) : 0, to->inmaclength,
- to->incompression);
- }
- bool ans_key_h(connection_t *c) {
- char from_name[MAX_STRING_SIZE];
- char to_name[MAX_STRING_SIZE];
- char key[MAX_STRING_SIZE];
- char address[MAX_STRING_SIZE] = "";
- char port[MAX_STRING_SIZE] = "";
- int cipher, digest, maclength, compression;
- node_t *from, *to;
- if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
- from_name, to_name, key, &cipher, &digest, &maclength,
- &compression, address, port) < 7) {
- logger(LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
- c->hostname);
- return false;
- }
- if(!check_id(from_name) || !check_id(to_name)) {
- logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
- return false;
- }
- from = lookup_node(from_name);
- if(!from) {
- logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
- "ANS_KEY", c->name, c->hostname, from_name);
- return true;
- }
- to = lookup_node(to_name);
- if(!to) {
- logger(LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
- "ANS_KEY", c->name, c->hostname, to_name);
- return true;
- }
- /* Forward it if necessary */
- if(to != myself) {
- if(tunnelserver) {
- return true;
- }
- if(!to->status.reachable) {
- logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
- "ANS_KEY", c->name, c->hostname, to_name);
- return true;
- }
- if(!*address && from->address.sa.sa_family != AF_UNSPEC && to->minmtu) {
- char *address, *port;
- ifdebug(PROTOCOL) logger(LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
- sockaddr2str(&from->address, &address, &port);
- send_request(to->nexthop->connection, "%s %s %s", c->buffer, address, port);
- free(address);
- free(port);
- return true;
- }
- return send_request(to->nexthop->connection, "%s", c->buffer);
- }
- /* Don't use key material until every check has passed. */
- from->status.validkey = false;
- /* Update our copy of the origin's packet key */
- from->outkey = xrealloc(from->outkey, strlen(key) / 2);
- from->outkeylength = strlen(key) / 2;
- if(!hex2bin(key, from->outkey, from->outkeylength)) {
- logger(LOG_ERR, "Got bad %s from %s(%s): %s", "ANS_KEY", from->name, from->hostname, "invalid key");
- return true;
- }
- /* Check and lookup cipher and digest algorithms */
- if(cipher) {
- from->outcipher = EVP_get_cipherbynid(cipher);
- if(!from->outcipher) {
- logger(LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name,
- from->hostname);
- return true;
- }
- if(from->outkeylength != EVP_CIPHER_key_length(from->outcipher) + EVP_CIPHER_iv_length(from->outcipher)) {
- logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name,
- from->hostname);
- return true;
- }
- } else {
- if(from->outkeylength != 1) {
- logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
- return true;
- }
- from->outcipher = NULL;
- }
- from->outmaclength = maclength;
- if(digest) {
- from->outdigest = EVP_get_digestbynid(digest);
- if(!from->outdigest) {
- logger(LOG_ERR, "Node %s (%s) uses unknown digest!", from->name,
- from->hostname);
- return true;
- }
- if(from->outmaclength > EVP_MD_size(from->outdigest) || from->outmaclength < 0) {
- logger(LOG_ERR, "Node %s (%s) uses bogus MAC length!",
- from->name, from->hostname);
- return true;
- }
- } else {
- from->outdigest = NULL;
- }
- if(compression < 0 || compression > 11) {
- logger(LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
- return true;
- }
- from->outcompression = compression;
- if(from->outcipher)
- if(!EVP_EncryptInit_ex(from->outctx, from->outcipher, NULL, (unsigned char *)from->outkey, (unsigned char *)from->outkey + EVP_CIPHER_key_length(from->outcipher))) {
- logger(LOG_ERR, "Error during initialisation of key from %s (%s): %s",
- from->name, from->hostname, ERR_error_string(ERR_get_error(), NULL));
- return true;
- }
- from->status.validkey = true;
- from->sent_seqno = 0;
- if(*address && *port) {
- ifdebug(PROTOCOL) logger(LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
- sockaddr_t sa = str2sockaddr(address, port);
- update_node_udp(from, &sa);
- }
- if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuevent) {
- send_mtu_probe(from);
- }
- return true;
- }
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