X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fprotocol_key.c;h=c392a469846e3878a53a65b84a110f43698df02e;hb=3fba80174dbe29bcfe0d121a2a1d2e61be5ee57b;hp=4187538b6e3f39f9be301a4ba9dc3042cb2ce836;hpb=2911af6e23d0dba6d771fcd590551a84bd9dc932;p=tinc diff --git a/src/protocol_key.c b/src/protocol_key.c index 4187538b..c392a469 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, - 2000-2010 Guus Sliepen + 2000-2011 Guus Sliepen 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 @@ -24,21 +24,23 @@ #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; -void send_key_changed() { +void send_key_changed(void) { splay_node_t *node; connection_t *c; - send_request(broadcast, "%d %x %s", KEY_CHANGED, rand(), myself->name); + send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name); /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */ @@ -82,15 +84,16 @@ 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 %d", REQ_KEY, myself->name, to->name, experimental ? 1 : 0); } 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; @@ -120,7 +123,10 @@ bool req_key_h(connection_t *c, char *request) { /* Check if this key request is for us */ if(to == myself) { /* Yes, send our own key back */ - + if(experimental && kx_version >= 1) { + logger(LOG_DEBUG, "Got ECDH key request from %s", from->name); + from->status.ecdh = true; + } send_ans_key(from); } else { if(tunnelserver) @@ -138,7 +144,38 @@ bool req_key_h(connection_t *c, char *request) { return true; } +bool send_ans_key_ecdh(node_t *to) { + int siglen = ecdsa_size(&myself->connection->ecdsa); + char key[(ECDH_SIZE + siglen) * 2 + 1]; + + if(!ecdh_generate_public(&to->ecdh, key)) + return false; + + if(!ecdsa_sign(&myself->connection->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE)) + return false; + + b64encode(key, key, ECDH_SIZE + siglen); + + char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa); + + if(!pubkey) + return false; + + int result = send_request(to->nexthop->connection, "%d %s %s ECDH:%s:%s %d %d %zu %d", ANS_KEY, + myself->name, to->name, key, pubkey, + cipher_get_nid(&myself->incipher), + digest_get_nid(&myself->indigest), + digest_length(&myself->indigest), + myself->incompression); + + free(pubkey); + return result; +} + bool send_ans_key(node_t *to) { + if(experimental && to->status.ecdh) + return send_ans_key_ecdh(to); + size_t keylen = cipher_keylength(&myself->incipher); char key[keylen * 2 + 1]; @@ -147,16 +184,15 @@ bool send_ans_key(node_t *to) { to->incompression = myself->incompression; randomize(key, keylen); - cipher_set_key(&to->incipher, key, true); + cipher_set_key(&to->incipher, key, false); digest_set_key(&to->indigest, key, keylen); bin2hex(key, key, keylen); - key[keylen * 2] = '\0'; // 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, @@ -216,7 +252,7 @@ bool ans_key_h(connection_t *c, char *request) { return true; } - if(!*address) { + 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); @@ -236,13 +272,6 @@ 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; @@ -257,14 +286,115 @@ bool ans_key_h(connection_t *c, char *request) { logger(LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname); return true; } - + from->outcompression = compression; - /* Update our copy of the origin's packet key */ + /* ECDH or old-style key exchange? */ + + if(experimental && !strncmp(key, "ECDH:", 5)) { + char *pubkey = strchr(key + 5, ':'); + if(pubkey) + *pubkey++ = 0; + + /* Check if we already have an ECDSA public key for this node. + * If not, use the one from the key exchange, and store it. */ + + if(!node_read_ecdsa_public_key(from)) { + if(!pubkey) { + logger(LOG_ERR, "No ECDSA public key known for %s (%s), cannot verify ECDH key exchange!", from->name, from->hostname); + return true; + } + + if(!ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) + return true; + + append_config_file(from->name, "ECDSAPublicKey", pubkey); + } + + int siglen = ecdsa_size(&from->ecdsa); + int keylen = b64decode(key + 5, key + 5, sizeof key - 5); + + if(keylen != ECDH_SIZE + siglen) { + logger(LOG_ERR, "Node %s (%s) uses wrong keylength! %d != %d", from->name, from->hostname, keylen, ECDH_SIZE + siglen); + return true; + } + + if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) { + logger(LOG_ERR, "ECDH key too short for cipher of %s!", from->name); + return true; + } + + if(!ecdsa_verify(&from->ecdsa, key + 5, ECDH_SIZE, key + 5 + ECDH_SIZE)) { + logger(LOG_ERR, "Possible intruder %s (%s): %s", from->name, from->hostname, "invalid ECDSA signature"); + return true; + } + + if(!from->ecdh) { + from->status.ecdh = true; + if(!send_ans_key(from)) + return true; + } + + char shared[ECDH_SHARED_SIZE * 2 + 1]; + + if(!ecdh_compute_shared(&from->ecdh, key + 5, shared)) + return true; - hex2bin(key, key, keylen); - cipher_set_key(&from->outcipher, key, false); - digest_set_key(&from->outdigest, key, keylen); + /* Update our crypto end */ + + size_t mykeylen = cipher_keylength(&myself->incipher); + size_t hiskeylen = cipher_keylength(&from->outcipher); + + char *mykey; + char *hiskey; + char *seed; + + if(strcmp(myself->name, from->name) < 0) { + mykey = key; + hiskey = key + mykeylen * 2; + xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name); + } else { + mykey = key + hiskeylen * 2; + hiskey = key; + xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name); + } + + if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2)) + return true; + + 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, false); + digest_set_key(&from->indigest, mykey + mykeylen, mykeylen); + + cipher_set_key(&from->outcipher, hiskey, true); + digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen); + + // 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 * 2, hiskeylen * 2); + } else { + keylen = hex2bin(key, key, sizeof key); + + if(keylen != cipher_keylength(&from->outcipher)) { + logger(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; @@ -275,7 +405,7 @@ bool ans_key_h(connection_t *c, char *request) { update_node_udp(from, &sa); } - if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuprobes) + if(from->options & OPTION_PMTU_DISCOVERY) send_mtu_probe(from); return true;