X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fprotocol_key.c;h=c392a469846e3878a53a65b84a110f43698df02e;hp=1d471c80084181817ab3529821f9fac5675676f9;hb=3fba80174dbe29bcfe0d121a2a1d2e61be5ee57b;hpb=65e8e06c6dc7349b11c3c1e8f4071b51e2994c65

diff --git a/src/protocol_key.c b/src/protocol_key.c
index 1d471c80..c392a469 100644
--- a/src/protocol_key.c
+++ b/src/protocol_key.c
@@ -20,16 +20,16 @@
 
 #include "system.h"
 
-#include <openssl/evp.h>
-#include <openssl/err.h>
-#include <openssl/rand.h>
-
-#include "avl_tree.h"
+#include "splay_tree.h"
+#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"
@@ -37,7 +37,7 @@
 static bool mykeyused = false;
 
 void send_key_changed(void) {
-	avl_node_t *node;
+	splay_node_t *node;
 	connection_t *c;
 
 	send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
@@ -51,22 +51,17 @@ void send_key_changed(void) {
 	}
 }
 
-bool key_changed_h(connection_t *c) {
+bool key_changed_h(connection_t *c, char *request) {
 	char name[MAX_STRING_SIZE];
 	node_t *n;
 
-	if(sscanf(c->buffer, "%*d %*x " MAX_STRING, name) != 1) {
+	if(sscanf(request, "%*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))
+	if(seen_request(request))
 		return true;
 
 	n = lookup_node(name);
@@ -83,21 +78,22 @@ bool key_changed_h(connection_t *c) {
 	/* Tell the others */
 
 	if(!tunnelserver)
-		forward_request(c);
+		forward_request(c, request);
 
 	return true;
 }
 
 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) {
+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(c->buffer, "%*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;
@@ -127,6 +123,10 @@ bool req_key_h(connection_t *c) {
 	/* 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)
@@ -138,55 +138,80 @@ bool req_key_h(connection_t *c) {
 			return true;
 		}
 
-		send_request(to->nexthop->connection, "%s", c->buffer);
+		send_request(to->nexthop->connection, "%s", 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) {
-	// Set key parameters
-	to->incipher = myself->incipher;
-	to->inkeylength = myself->inkeylength;
-	to->indigest = myself->indigest;
-	to->inmaclength = myself->inmaclength;
+	if(experimental && to->status.ecdh)
+		return send_ans_key_ecdh(to);
+
+	size_t keylen = cipher_keylength(&myself->incipher);
+	char key[keylen * 2 + 1];
+
+	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;
 
-	// Allocate memory for key
-	to->inkey = xrealloc(to->inkey, to->inkeylength);
+	randomize(key, keylen);
+	cipher_set_key(&to->incipher, key, false);
+	digest_set_key(&to->indigest, key, keylen);
 
-	// Create a new key
-	RAND_pseudo_bytes((unsigned char *)to->inkey, to->inkeylength);
-	if(to->incipher)
-		EVP_DecryptInit_ex(&to->inctx, to->incipher, NULL, (unsigned char *)to->inkey, (unsigned char *)to->inkey + to->incipher->key_len);
+	bin2hex(key, key, keylen);
 
 	// 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 ? to->incipher->nid : 0,
-			to->indigest ? to->indigest->type : 0, to->inmaclength,
-			to->incompression);
+	return send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
+						myself->name, to->name, key,
+						cipher_get_nid(&to->incipher),
+						digest_get_nid(&to->indigest),
+						digest_length(&to->indigest),
+						to->incompression);
 }
 
-bool ans_key_h(connection_t *c) {
+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;
+        char address[MAX_STRING_SIZE] = "";
+        char port[MAX_STRING_SIZE] = "";
+	int cipher, digest, maclength, compression, keylen;
 	node_t *from, *to;
 
-	if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
+	if(sscanf(request, "%*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,
@@ -223,7 +248,7 @@ bool ans_key_h(connection_t *c) {
 
 		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);
+				   "ANS_KEY", c->name, c->hostname, to_name);
 			return true;
 		}
 
@@ -231,74 +256,146 @@ bool ans_key_h(connection_t *c) {
 			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);
+			send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 			free(address);
 			free(port);
 			return true;
 		}
 
-		return send_request(to->nexthop->connection, "%s", c->buffer);
+		return send_request(to->nexthop->connection, "%s", request);
 	}
 
-	/* Update our copy of the origin's packet key */
-	from->outkey = xrealloc(from->outkey, strlen(key) / 2);
-	from->outkeylength = strlen(key) / 2;
-	hex2bin(key, from->outkey, from->outkeylength);
-
 	/* Check and lookup cipher and digest algorithms */
 
-	if(cipher) {
-		from->outcipher = EVP_get_cipherbynid(cipher);
+	if(!cipher_open_by_nid(&from->outcipher, cipher)) {
+		logger(LOG_ERR, "Node %s (%s) uses unknown cipher!", 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;
+	}
+
+	if(maclength != digest_length(&from->outdigest)) {
+		logger(LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
+		return false;
+	}
 
-		if(!from->outcipher) {
-			logger(LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name,
-				   from->hostname);
+	if(compression < 0 || compression > 11) {
+		logger(LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+		return true;
+	}
+
+	from->outcompression = compression;
+
+	/* 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(from->outkeylength != from->outcipher->key_len + from->outcipher->iv_len) {
-			logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name,
-				   from->hostname);
+		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;
 		}
-	} else {
-		from->outcipher = NULL;
-	}
 
-	from->outmaclength = maclength;
+		if(!from->ecdh) {
+			from->status.ecdh = true;
+			if(!send_ans_key(from))
+				return true;
+		}
 
-	if(digest) {
-		from->outdigest = EVP_get_digestbynid(digest);
+		char shared[ECDH_SHARED_SIZE * 2 + 1];
 
-		if(!from->outdigest) {
-			logger(LOG_ERR, "Node %s (%s) uses unknown digest!", from->name,
-				   from->hostname);
+		if(!ecdh_compute_shared(&from->ecdh, key + 5, shared))
 			return true;
+
+		/* 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(from->outmaclength > from->outdigest->md_size || from->outmaclength < 0) {
-			logger(LOG_ERR, "Node %s (%s) uses bogus MAC length!",
-				   from->name, from->hostname);
+		if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
 			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;
+		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;
 
-	if(from->outcipher)
-		if(!EVP_EncryptInit_ex(&from->outctx, from->outcipher, NULL, (unsigned char *)from->outkey, (unsigned char *)from->outkey + from->outcipher->key_len)) {
-			logger(LOG_ERR, "Error during initialisation of key from %s (%s): %s",
-					from->name, from->hostname, ERR_error_string(ERR_get_error(), NULL));
+		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;
 
@@ -308,7 +405,7 @@ bool ans_key_h(connection_t *c) {
 		update_node_udp(from, &sa);
 	}
 
-	if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuevent)
+	if(from->options & OPTION_PMTU_DISCOVERY)
 		send_mtu_probe(from);
 
 	return true;