X-Git-Url: https://www.tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fprotocol_key.c;h=8bbb6ad4e875e7eb04edf66a66e35a076c8d5877;hb=82f00ea07bffc10985ccb1a15723e6daa0ab4969;hp=3b022679dbadb6fae80a6001ed2c3726bc0f8afe;hpb=c845bc109c85e6fb350096c63e13ef8e617ee29b;p=tinc

diff --git a/src/protocol_key.c b/src/protocol_key.c
index 3b022679..8bbb6ad4 100644
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -1,7 +1,7 @@
 /*
     protocol_key.c -- handle the meta-protocol, key exchange
     Copyright (C) 1999-2005 Ivo Timmermans,
-                  2000-2009 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2011 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
@@ -24,25 +24,31 @@
 #include "cipher.h"
 #include "connection.h"
 #include "crypto.h"
+#include "ecdh.h"
 #include "logger.h"
 #include "net.h"
 #include "netutl.h"
 #include "node.h"
+#include "prf.h"
 #include "protocol.h"
 #include "utils.h"
 #include "xalloc.h"
 
 static bool mykeyused = false;
 
-bool send_key_changed() {
-	/* Only send this message if some other daemon requested our key previously.
-	   This reduces unnecessary key_changed broadcasts.
-	 */
+void send_key_changed(void) {
+	splay_node_t *node;
+	connection_t *c;
 
-	if(!mykeyused)
-		return true;
+	send_request(broadcast, "%d %x %s", KEY_CHANGED, rand(), myself->name);
+
+	/* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
 
-	return send_request(broadcast, "%d %x %s", KEY_CHANGED, rand(), myself->name);
+	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 *request) {
@@ -63,11 +69,11 @@ bool key_changed_h(connection_t *c, char *request) {
 	if(!n) {
 		logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
 			   "KEY_CHANGED", c->name, c->hostname, name);
-		return false;
+		return true;
 	}
 
 	n->status.validkey = false;
-	n->status.waitingforkey = false;
+	n->last_req_key = 0;
 
 	/* Tell the others */
 
@@ -78,26 +84,32 @@ bool key_changed_h(connection_t *c, char *request) {
 }
 
 bool send_req_key(node_t *to) {
-	return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
+	return send_request(to->nexthop->connection, "%d %s %s 1", REQ_KEY, myself->name, to->name);
 }
 
 bool req_key_h(connection_t *c, char *request) {
 	char from_name[MAX_STRING_SIZE];
 	char to_name[MAX_STRING_SIZE];
 	node_t *from, *to;
+	int kx_version = 0;
 
-	if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING, from_name, to_name) != 2) {
+	if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &kx_version) < 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 false;
+		return true;
 	}
 
 	to = lookup_node(to_name);
@@ -105,17 +117,20 @@ bool req_key_h(connection_t *c, char *request) {
 	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 false;
+		return true;
 	}
 
 	/* Check if this key request is for us */
 
 	if(to == myself) {			/* Yes, send our own key back */
-
+		if(kx_version > 0) {
+			logger(LOG_DEBUG, "Got ECDH key request from %s", from->name);
+			from->status.ecdh = true;
+		}
 		send_ans_key(from);
 	} else {
 		if(tunnelserver)
-			return false;
+			return true;
 
 		if(!to->status.reachable) {
 			logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
@@ -129,7 +144,26 @@ bool req_key_h(connection_t *c, char *request) {
 	return true;
 }
 
+bool send_ans_key_ecdh(node_t *to) {
+	char key[ECDH_SIZE * 2 + 1];
+
+	ecdh_generate_public(&to->ecdh, key);
+
+	bin2hex(key, key, ECDH_SIZE);
+	key[ECDH_SIZE * 2] = '\0';
+
+	return send_request(to->nexthop->connection, "%d %s %s ECDH:%s %d %d %zu %d", ANS_KEY,
+						myself->name, to->name, key,
+						cipher_get_nid(&myself->incipher),
+						digest_get_nid(&myself->indigest),
+						digest_length(&myself->indigest),
+						myself->incompression);
+}
+
 bool send_ans_key(node_t *to) {
+	if(to->status.ecdh)
+		return send_ans_key_ecdh(to);
+
 	size_t keylen = cipher_keylength(&myself->incipher);
 	char key[keylen * 2 + 1];
 
@@ -147,7 +181,7 @@ bool send_ans_key(node_t *to) {
 	// Reset sequence number and late packet window
 	mykeyused = true;
 	to->received_seqno = 0;
-	memset(to->late, 0, sizeof(to->late));
+	if(replaywin) memset(to->late, 0, replaywin);
 
 	return send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
 						myself->name, to->name, key,
@@ -161,23 +195,30 @@ bool ans_key_h(connection_t *c, char *request) {
 	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, keylen;
 	node_t *from, *to;
 
-	if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d",
+	if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING" %d",
 		from_name, to_name, key, &cipher, &digest, &maclength,
-		&compression) != 7) {
+		&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 false;
+		return true;
 	}
 
 	to = lookup_node(to_name);
@@ -185,14 +226,14 @@ bool ans_key_h(connection_t *c, char *request) {
 	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 false;
+		return true;
 	}
 
 	/* Forward it if necessary */
 
 	if(to != myself) {
 		if(tunnelserver)
-			return false;
+			return true;
 
 		if(!to->status.reachable) {
 			logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
@@ -200,6 +241,16 @@ bool ans_key_h(connection_t *c, char *request) {
 			return true;
 		}
 
+		if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
+			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", request, address, port);
+			free(address);
+			free(port);
+			return true;
+		}
+
 		return send_request(to->nexthop->connection, "%s", request);
 	}
 
@@ -210,13 +261,6 @@ bool ans_key_h(connection_t *c, char *request) {
 		return false;
 	}
 
-	keylen = strlen(key) / 2;
-
-	if(keylen != cipher_keylength(&from->outcipher)) {
-		logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
-		return false;
-	}
-
 	if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 		logger(LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 		return false;
@@ -229,22 +273,106 @@ bool ans_key_h(connection_t *c, char *request) {
 
 	if(compression < 0 || compression > 11) {
 		logger(LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
-		return false;
+		return true;
 	}
-	
+
 	from->outcompression = compression;
 
+	/* ECDH or old-style key exchange? */
+	/* TODO: look at SSH and TLS to see how they derive cipher and HMAC keys from shared secret properly */
+	
+	if(!strncmp(key, "ECDH:", 5)) {
+		logger(LOG_DEBUG, "Got ECDH key from %s", from->name);
+
+		keylen = (strlen(key) - 5) / 2;
+
+		if(keylen != ECDH_SIZE) {
+			logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+			return false;
+		}
+
+		if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) {
+			logger(LOG_ERR, "ECDH key too short for cipher of %s!", from->name);
+			return false;
+		}
+
+		if(!from->ecdh) {
+			logger(LOG_DEBUG, "Woops, we didn't generate our public key yet");
+			from->status.ecdh = true;
+			if(!send_ans_key(from))
+				return false;
+		}
+
+		char shared[ECDH_SHARED_SIZE * 2 + 1];
+		char hex[ECDH_SHARED_SIZE * 2 + 1];
+		hex2bin(key + 5, key + 5, keylen);
+
+		if(!ecdh_compute_shared(&from->ecdh, key + 5, shared))
+			return false;
+
+		/* Update our crypto end */
+
+		size_t mykeylen = cipher_keylength(&myself->incipher);
+		keylen = cipher_keylength(&from->outcipher);
+
+		char *mykey;
+		char *seed = NULL;
+		
+		if(strcmp(myself->name, from->name) < 0) {
+			logger(LOG_DEBUG, "Using left half of shared secret");
+			mykey = key;
+			xasprintf(&seed, "tinc key expansion %s %s", myself->name, from->name);
+		} else {
+			logger(LOG_DEBUG, "Using right half of shared secret");
+			mykey = key + keylen;
+			xasprintf(&seed, "tinc key expansion %s %s", from->name, myself->name);
+		}
+
+		if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, keylen + mykeylen))
+			return false;
+
+		free(seed);
+
+		cipher_open_by_nid(&from->incipher, cipher_get_nid(&myself->incipher));
+		digest_open_by_nid(&from->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
+		from->incompression = myself->incompression;
+
+		cipher_set_key(&from->incipher, mykey, true);
+		digest_set_key(&from->indigest, mykey, mykeylen);
+
+		// Reset sequence number and late packet window
+		mykeyused = true;
+		from->received_seqno = 0;
+		if(replaywin)
+			memset(from->late, 0, replaywin);
+
+		if(strcmp(myself->name, from->name) < 0)
+			memmove(key, key + mykeylen, keylen);
+	} else {
+		keylen = strlen(key) / 2;
+		hex2bin(key, key, keylen);
+	}
+
 	/* Update our copy of the origin's packet key */
 
-	hex2bin(key, key, keylen);
+	if(keylen != cipher_keylength(&from->outcipher)) {
+		logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+		return false;
+	}
+
 	cipher_set_key(&from->outcipher, key, false);
 	digest_set_key(&from->outdigest, key, keylen);
 
 	from->status.validkey = true;
-	from->status.waitingforkey = false;
 	from->sent_seqno = 0;
 
-	if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuprobes)
+	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)
 		send_mtu_probe(from);
 
 	return true;