411 lines
12 KiB
C
411 lines
12 KiB
C
/*
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protocol_key.c -- handle the meta-protocol, key exchange
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Copyright (C) 1999-2005 Ivo Timmermans,
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2000-2012 Guus Sliepen <guus@tinc-vpn.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "system.h"
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#include "splay_tree.h"
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#include "cipher.h"
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#include "connection.h"
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#include "crypto.h"
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#include "logger.h"
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#include "net.h"
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#include "netutl.h"
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#include "node.h"
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#include "prf.h"
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#include "protocol.h"
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#include "sptps.h"
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#include "utils.h"
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#include "xalloc.h"
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static bool mykeyused = false;
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void send_key_changed(void) {
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splay_node_t *node;
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connection_t *c;
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send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
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/* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
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for(node = connection_tree->head; node; node = node->next) {
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c = node->data;
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if(c->status.active && c->node && c->node->status.reachable) {
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if(!c->node->status.sptps)
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send_ans_key(c->node);
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}
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}
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/* Force key exchange for connections using SPTPS */
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if(experimental) {
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for(node = node_tree->head; node; node = node->next) {
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node_t *n = node->data;
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if(n->status.reachable && n->status.validkey && n->status.sptps)
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sptps_force_kex(&n->sptps);
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}
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}
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}
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bool key_changed_h(connection_t *c, const char *request) {
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char name[MAX_STRING_SIZE];
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node_t *n;
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if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
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c->name, c->hostname);
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return false;
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}
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if(seen_request(request))
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return true;
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n = lookup_node(name);
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if(!n) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
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"KEY_CHANGED", c->name, c->hostname, name);
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return true;
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}
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if(!n->status.sptps) {
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n->status.validkey = false;
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n->last_req_key = 0;
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}
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/* Tell the others */
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if(!tunnelserver)
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forward_request(c, request);
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return true;
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}
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static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
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node_t *to = handle;
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to->sptps.send_data = send_sptps_data;
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char buf[len * 4 / 3 + 5];
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b64encode(data, buf, len);
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return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
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}
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bool send_req_key(node_t *to) {
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if(to->status.sptps) {
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if(!node_read_ecdsa_public_key(to)) {
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logger(DEBUG_ALWAYS, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
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send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
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return true;
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}
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char label[25 + strlen(myself->name) + strlen(to->name)];
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snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
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sptps_stop(&to->sptps);
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to->status.validkey = false;
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to->incompression = myself->incompression;
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return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
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}
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return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
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}
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/* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
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static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
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switch(reqno) {
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case REQ_PUBKEY: {
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char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
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send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
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free(pubkey);
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return true;
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}
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case ANS_PUBKEY: {
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if(node_read_ecdsa_public_key(from)) {
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logger(DEBUG_ALWAYS, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
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return true;
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}
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char pubkey[MAX_STRING_SIZE];
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if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
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return true;
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}
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logger(DEBUG_ALWAYS, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
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append_config_file(from->name, "ECDSAPublicKey", pubkey);
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return true;
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}
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case REQ_KEY: {
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if(!node_read_ecdsa_public_key(from)) {
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logger(DEBUG_ALWAYS, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
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send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
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return true;
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}
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}
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case REQ_SPTPS: {
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char buf[MAX_STRING_SIZE];
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if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
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return true;
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}
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int len = b64decode(buf, buf, strlen(buf));
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char label[25 + strlen(from->name) + strlen(myself->name)];
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snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
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sptps_stop(&from->sptps);
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from->status.validkey = false;
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sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
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sptps_receive_data(&from->sptps, buf, len);
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return true;
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}
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default:
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logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
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return true;
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}
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}
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bool req_key_h(connection_t *c, const char *request) {
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char from_name[MAX_STRING_SIZE];
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char to_name[MAX_STRING_SIZE];
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node_t *from, *to;
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int reqno = 0;
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if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
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c->hostname);
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return false;
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}
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if(!check_id(from_name) || !check_id(to_name)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
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return false;
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}
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from = lookup_node(from_name);
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if(!from) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
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"REQ_KEY", c->name, c->hostname, from_name);
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return true;
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}
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to = lookup_node(to_name);
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if(!to) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
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"REQ_KEY", c->name, c->hostname, to_name);
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return true;
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}
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/* Check if this key request is for us */
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if(to == myself) { /* Yes */
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/* Is this an extended REQ_KEY message? */
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if(experimental && reqno)
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return req_key_ext_h(c, request, from, reqno);
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/* No, just send our key back */
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send_ans_key(from);
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} else {
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if(tunnelserver)
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return true;
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if(!to->status.reachable) {
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logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
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"REQ_KEY", c->name, c->hostname, to_name);
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return true;
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}
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send_request(to->nexthop->connection, "%s", request);
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}
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return true;
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}
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bool send_ans_key(node_t *to) {
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if(to->status.sptps)
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abort();
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size_t keylen = cipher_keylength(&myself->incipher);
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char key[keylen * 2 + 1];
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cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
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digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
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to->incompression = myself->incompression;
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randomize(key, keylen);
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cipher_set_key(&to->incipher, key, false);
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digest_set_key(&to->indigest, key, keylen);
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bin2hex(key, key, keylen);
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// Reset sequence number and late packet window
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mykeyused = true;
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to->received_seqno = 0;
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if(replaywin) memset(to->late, 0, replaywin);
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return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
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myself->name, to->name, key,
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cipher_get_nid(&to->incipher),
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digest_get_nid(&to->indigest),
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(int)digest_length(&to->indigest),
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to->incompression);
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}
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bool ans_key_h(connection_t *c, const char *request) {
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char from_name[MAX_STRING_SIZE];
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char to_name[MAX_STRING_SIZE];
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char key[MAX_STRING_SIZE];
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char address[MAX_STRING_SIZE] = "";
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char port[MAX_STRING_SIZE] = "";
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int cipher, digest, maclength, compression, keylen;
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node_t *from, *to;
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if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
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from_name, to_name, key, &cipher, &digest, &maclength,
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&compression, address, port) < 7) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
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c->hostname);
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return false;
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}
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if(!check_id(from_name) || !check_id(to_name)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
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return false;
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}
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from = lookup_node(from_name);
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if(!from) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
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"ANS_KEY", c->name, c->hostname, from_name);
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return true;
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}
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to = lookup_node(to_name);
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if(!to) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
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"ANS_KEY", c->name, c->hostname, to_name);
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return true;
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}
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/* Forward it if necessary */
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if(to != myself) {
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if(tunnelserver)
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return true;
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if(!to->status.reachable) {
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logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
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"ANS_KEY", c->name, c->hostname, to_name);
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return true;
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}
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if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
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char *address, *port;
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logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
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sockaddr2str(&from->address, &address, &port);
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send_request(to->nexthop->connection, "%s %s %s", request, address, port);
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free(address);
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free(port);
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return true;
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}
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return send_request(to->nexthop->connection, "%s", request);
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}
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if(compression < 0 || compression > 11) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
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return true;
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}
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from->outcompression = compression;
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/* SPTPS or old-style key exchange? */
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if(from->status.sptps) {
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char buf[strlen(key)];
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int len = b64decode(key, buf, strlen(key));
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if(!sptps_receive_data(&from->sptps, buf, len))
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logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
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if(from->status.validkey) {
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if(*address && *port) {
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logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
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sockaddr_t sa = str2sockaddr(address, port);
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update_node_udp(from, &sa);
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}
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if(from->options & OPTION_PMTU_DISCOVERY)
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send_mtu_probe(from);
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}
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return true;
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}
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/* Check and lookup cipher and digest algorithms */
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if(!cipher_open_by_nid(&from->outcipher, cipher)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
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return false;
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}
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if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
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return false;
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}
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if(maclength != digest_length(&from->outdigest)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
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return false;
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}
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/* Process key */
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keylen = hex2bin(key, key, sizeof key);
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if(keylen != cipher_keylength(&from->outcipher)) {
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logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
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return true;
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}
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/* Update our copy of the origin's packet key */
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cipher_set_key(&from->outcipher, key, true);
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digest_set_key(&from->outdigest, key, keylen);
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from->status.validkey = true;
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from->sent_seqno = 0;
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if(*address && *port) {
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logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
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sockaddr_t sa = str2sockaddr(address, port);
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update_node_udp(from, &sa);
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}
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if(from->options & OPTION_PMTU_DISCOVERY)
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send_mtu_probe(from);
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return true;
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}
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