tinc/src/protocol_key.c

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/*
protocol_key.c -- handle the meta-protocol, key exchange
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
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.
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*/
#include "system.h"
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#include "cipher.h"
#include "connection.h"
#include "crypto.h"
#include "logger.h"
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#include "net.h"
#include "netutl.h"
#include "node.h"
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#include "prf.h"
#include "protocol.h"
#include "sptps.h"
#include "utils.h"
#include "xalloc.h"
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static bool mykeyused = false;
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void send_key_changed(void) {
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 list_each(connection_t, c, connection_list)
if(c->status.active && c->node && c->node->status.reachable && !c->node->status.sptps)
send_ans_key(c->node);
/* Force key exchange for connections using SPTPS */
if(experimental) {
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for splay_each(node_t, n, node_tree)
if(n->status.reachable && n->status.validkey && n->status.sptps)
sptps_force_kex(&n->sptps);
}
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}
bool key_changed_h(connection_t *c, const char *request) {
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char name[MAX_STRING_SIZE];
node_t *n;
if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
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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}
if(seen_request(request))
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return true;
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n = lookup_node(name);
if(!n) {
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);
return true;
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}
if(!n->status.sptps) {
n->status.validkey = false;
n->last_req_key = 0;
}
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/* Tell the others */
if(!tunnelserver)
forward_request(c, request);
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return true;
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}
static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
node_t *to = handle;
to->sptps.send_data = send_sptps_data;
char buf[len * 4 / 3 + 5];
b64encode(data, buf, len);
return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
}
bool send_req_key(node_t *to) {
if(to->status.sptps) {
if(!node_read_ecdsa_public_key(to)) {
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logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
return true;
}
if(to->sptps.label)
logger(DEBUG_ALWAYS, LOG_DEBUG, "send_req_key(%s) called while sptps->label != NULL!", to->name);
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char label[25 + strlen(myself->name) + strlen(to->name)];
snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
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sptps_stop(&to->sptps);
to->status.validkey = false;
to->status.waitingforkey = true;
to->last_req_key = time(NULL);
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);
}
return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
}
/* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
switch(reqno) {
case REQ_PUBKEY: {
char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
free(pubkey);
return true;
}
case ANS_PUBKEY: {
if(node_read_ecdsa_public_key(from)) {
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logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
return true;
}
char pubkey[MAX_STRING_SIZE];
if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
return true;
}
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logger(DEBUG_PROTOCOL, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
append_config_file(from->name, "ECDSAPublicKey", pubkey);
return true;
}
case REQ_KEY: {
if(!node_read_ecdsa_public_key(from)) {
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logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
return true;
}
if(from->sptps.label)
logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
char buf[MAX_STRING_SIZE];
if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
return true;
}
int len = b64decode(buf, buf, strlen(buf));
char label[25 + strlen(from->name) + strlen(myself->name)];
snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
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sptps_stop(&from->sptps);
from->status.validkey = false;
from->status.waitingforkey = true;
from->last_req_key = time(NULL);
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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);
sptps_receive_data(&from->sptps, buf, len);
return true;
}
case REQ_SPTPS: {
if(!from->status.validkey) {
logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
return true;
}
char buf[MAX_STRING_SIZE];
if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS", from->name, from->hostname, "invalid SPTPS data");
return true;
}
int len = b64decode(buf, buf, strlen(buf));
sptps_receive_data(&from->sptps, buf, len);
return true;
}
default:
logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
return true;
}
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}
bool req_key_h(connection_t *c, const char *request) {
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char from_name[MAX_STRING_SIZE];
char to_name[MAX_STRING_SIZE];
node_t *from, *to;
int reqno = 0;
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if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
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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}
if(!check_id(from_name) || !check_id(to_name)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
return false;
}
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from = lookup_node(from_name);
if(!from) {
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);
return true;
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}
to = lookup_node(to_name);
if(!to) {
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);
return true;
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}
/* Check if this key request is for us */
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if(to == myself) { /* Yes */
/* Is this an extended REQ_KEY message? */
if(experimental && reqno)
return req_key_ext_h(c, request, from, reqno);
/* No, just send our key back */
send_ans_key(from);
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} else {
if(tunnelserver)
return true;
if(!to->status.reachable) {
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logger(DEBUG_PROTOCOL, 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", request);
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}
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return true;
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}
bool send_ans_key(node_t *to) {
if(to->status.sptps)
abort();
size_t keylen = cipher_keylength(&myself->incipher);
char key[keylen * 2 + 1];
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cipher_close(&to->incipher);
digest_close(&to->indigest);
cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
to->incompression = myself->incompression;
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randomize(key, keylen);
cipher_set_key(&to->incipher, key, false);
digest_set_key(&to->indigest, key, keylen);
bin2hex(key, key, keylen);
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// Reset sequence number and late packet window
mykeyused = true;
to->received_seqno = 0;
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,
myself->name, to->name, key,
cipher_get_nid(&to->incipher),
digest_get_nid(&to->indigest),
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(int)digest_length(&to->indigest),
to->incompression);
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}
bool ans_key_h(connection_t *c, const char *request) {
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char from_name[MAX_STRING_SIZE];
char to_name[MAX_STRING_SIZE];
char key[MAX_STRING_SIZE];
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char address[MAX_STRING_SIZE] = "";
char port[MAX_STRING_SIZE] = "";
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,
&compression, address, port) < 7) {
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)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
return false;
}
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from = lookup_node(from_name);
if(!from) {
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);
return true;
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}
to = lookup_node(to_name);
if(!to) {
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);
return true;
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}
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/* Forward it if necessary */
if(to != myself) {
if(tunnelserver)
return true;
if(!to->status.reachable) {
logger(DEBUG_ALWAYS, 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) {
char *address, *port;
logger(DEBUG_PROTOCOL, 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", request, address, port);
free(address);
free(port);
return true;
}
return send_request(to->nexthop->connection, "%s", request);
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}
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/* Don't use key material until every check has passed. */
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cipher_close(&from->outcipher);
digest_close(&from->outdigest);
from->status.validkey = false;
if(compression < 0 || compression > 11) {
logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
return true;
}
from->outcompression = compression;
/* SPTPS or old-style key exchange? */
if(from->status.sptps) {
char buf[strlen(key)];
int len = b64decode(key, buf, strlen(key));
if(!sptps_receive_data(&from->sptps, buf, len))
logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
if(from->status.validkey) {
if(*address && *port) {
logger(DEBUG_PROTOCOL, 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)
send_mtu_probe(from);
}
return true;
}
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/* Check and lookup cipher and digest algorithms */
if(!cipher_open_by_nid(&from->outcipher, cipher)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
return false;
}
if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
return false;
}
if(maclength != digest_length(&from->outdigest)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
return false;
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}
/* Process key */
keylen = hex2bin(key, key, sizeof key);
if(keylen != cipher_keylength(&from->outcipher)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
return true;
}
/* Update our copy of the origin's packet key */
cipher_set_key(&from->outcipher, key, true);
digest_set_key(&from->outdigest, key, keylen);
from->status.validkey = true;
from->sent_seqno = 0;
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if(*address && *port) {
logger(DEBUG_PROTOCOL, 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)
send_mtu_probe(from);
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return true;
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}