Limit key validity

4 files changed, 21 insertions, 18 deletions

diff --git a/src/config.c b/src/config.c
index 5da6abe..1eda277 100644
--- a/src/config.c
+++ b/src/config.c
@@ -62,8 +62,11 @@ static void default_config(fastd_config *conf) {
 
 	conf->mtu = 1500;
 	conf->mode = MODE_TAP;
+
 	conf->protocol = &fastd_protocol_null;
 	conf->secret = NULL;
+	conf->rekey = 3600;
+
 	conf->peers = NULL;
 
 	conf->on_up = NULL;
diff --git a/src/fastd.h b/src/fastd.h
index 4db53e4..cceaaf3 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -92,6 +92,7 @@ struct _fastd_config {
 
 	fastd_protocol *protocol;
 	char *secret;
+	unsigned rekey;
 
 	fastd_peer_config *peers;
 
@@ -198,6 +199,11 @@ static inline size_t fastd_max_packet_size(const fastd_context *ctx) {
 	}
 }
 
+static inline bool timespec_after(const struct timespec *tp1, const struct timespec *tp2) {
+	return (tp1->tv_sec > tp2->tv_sec ||
+		(tp1->tv_sec == tp2->tv_sec && tp1->tv_nsec > tp2->tv_nsec));
+}
+
 /* returns (tp1 - tp2) in milliseconds  */
 static inline int timespec_diff(const struct timespec *tp1, const struct timespec *tp2) {
 	return ((tp1->tv_sec - tp2->tv_sec))*1000 + (tp1->tv_nsec - tp2->tv_nsec)/1e6;
diff --git a/src/protocol_ec25519_fhmqvc_xsalsa20_poly1305.c b/src/protocol_ec25519_fhmqvc_xsalsa20_poly1305.c
index 4888589..df551fb 100644
--- a/src/protocol_ec25519_fhmqvc_xsalsa20_poly1305.c
+++ b/src/protocol_ec25519_fhmqvc_xsalsa20_poly1305.c
@@ -90,9 +90,8 @@ typedef struct _protocol_handshake {
 } protocol_handshake;
 
 typedef struct _protocol_session {
-	bool valid;
+	struct timespec valid_till;
 	uint8_t key[HASHBYTES];
-	struct timespec since;
 
 	uint8_t send_nonce[NONCEBYTES];
 	uint8_t receive_nonce[NONCEBYTES];
@@ -148,6 +147,10 @@ static inline void increment_nonce(uint8_t nonce[NONCEBYTES]) {
 	}
 }
 
+static inline bool is_session_valid(fastd_context *ctx, protocol_session *session) {
+	return timespec_after(&session->valid_till, &ctx->now);
+}
+
 static inline bool is_nonce_valid(const uint8_t nonce[NONCEBYTES], const uint8_t old_nonce[NONCEBYTES]) {
 	if ((nonce[0] & 1) != (old_nonce[0] & 1))
 		return false;
@@ -214,11 +217,7 @@ static void init_peer_state(fastd_context *ctx, fastd_peer *peer) {
 		return;
 
 	peer->protocol_state = malloc(sizeof(fastd_protocol_peer_state));
-
-	peer->protocol_state->old_session.valid = false;
-	peer->protocol_state->session.valid = false;
-	peer->protocol_state->initiating_handshake = NULL;
-	peer->protocol_state->accepting_handshake = NULL;
+	memset(peer->protocol_state, 0, sizeof(fastd_protocol_peer_state));
 }
 
 static inline void free_handshake(protocol_handshake *handshake) {
@@ -342,7 +341,7 @@ static void establish(fastd_context *ctx, fastd_peer *peer, const fastd_peer_con
 	int i;
 	uint8_t hashinput[5*PUBLICKEYBYTES];
 
-	if (peer->protocol_state->session.valid)
+	if (is_session_valid(ctx, &peer->protocol_state->session))
 		peer->protocol_state->old_session = peer->protocol_state->session;
 
 	memcpy(hashinput, X->p, PUBLICKEYBYTES);
@@ -352,8 +351,8 @@ static void establish(fastd_context *ctx, fastd_peer *peer, const fastd_peer_con
 	memcpy(hashinput+4*PUBLICKEYBYTES, sigma->p, PUBLICKEYBYTES);
 	crypto_hash_sha256(peer->protocol_state->session.key, hashinput, 5*PUBLICKEYBYTES);
 
-	peer->protocol_state->session.valid = true;
-	peer->protocol_state->session.since = ctx->now;
+	peer->protocol_state->session.valid_till = ctx->now;
+	peer->protocol_state->session.valid_till.tv_sec += ctx->conf->rekey;
 
 	peer->protocol_state->session.send_nonce[0] = initiator ? 3 : 2;
 	peer->protocol_state->session.receive_nonce[0] = initiator ? 0 : 1;
@@ -589,7 +588,7 @@ static void protocol_handle_recv(fastd_context *ctx, fastd_peer *peer, fastd_buf
 	if (buffer.len < NONCEBYTES)
 		goto end;
 
-	if (!peer->protocol_state || !peer->protocol_state->session.valid) {
+	if (!peer->protocol_state || !is_session_valid(ctx, &peer->protocol_state->session)) {
 		pr_debug(ctx, "received unexpected packet from %P", peer);
 		goto end;
 	}
@@ -626,7 +625,7 @@ static void protocol_handle_recv(fastd_context *ctx, fastd_peer *peer, fastd_buf
 }
 
 static void protocol_send(fastd_context *ctx, fastd_peer *peer, fastd_buffer buffer) {
-	if (!peer->protocol_state || !peer->protocol_state->session.valid) {
+	if (!peer->protocol_state || !is_session_valid(ctx, &peer->protocol_state->session)) {
 		fastd_buffer_free(buffer);
 		return;
 	}
diff --git a/src/queue.c b/src/queue.c
index a2ef3dc..2509538 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -30,11 +30,6 @@
 #include <stdint.h>
 
 
-static inline bool after(const struct timespec *tp1, const struct timespec *tp2) {
-	return (tp1->tv_sec > tp2->tv_sec ||
-		(tp1->tv_sec == tp2->tv_sec && tp1->tv_nsec > tp2->tv_nsec));
-}
-
 void fastd_queue_put(fastd_context *ctx, fastd_queue *queue, fastd_queue_entry *entry, int timeout) {
 	entry->timeout = ctx->now;
 
@@ -50,7 +45,7 @@ void fastd_queue_put(fastd_context *ctx, fastd_queue *queue, fastd_queue_entry *
 
 	fastd_queue_entry **current;
 	for (current = &queue->head;; current = &(*current)->next) {
-		if (!(*current) || after(&(*current)->timeout, &entry->timeout)) {
+		if (!(*current) || timespec_after(&(*current)->timeout, &entry->timeout)) {
 			entry->next = *current;
 			*current = entry;
 			break;