Add support for TLS 1.3 post handshake messages and key updating.

tested against openssl 1.1's server.

ok jsing@ tb@

3 files changed, 217 insertions, 20 deletions

diff --git a/lib/libssl/tls13_internal.h b/lib/libssl/tls13_internal.h
index 859030747f4..b33e4818af8 100644
--- a/lib/libssl/tls13_internal.h
+++ b/lib/libssl/tls13_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_internal.h,v 1.35 2019/11/20 16:21:20 beck Exp $ */
+/* $OpenBSD: tls13_internal.h,v 1.36 2019/11/26 23:46:18 beck Exp $ */
 /*
  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -38,8 +38,8 @@ __BEGIN_HIDDEN_DECLS
 #define TLS13_IO_USE_LEGACY	-4
 
 typedef void (*tls13_alert_cb)(uint8_t _alert_desc, void *_cb_arg);
-typedef int (*tls13_post_handshake_recv_cb)(void *_cb_arg, CBS *cbs);
-typedef int (*tls13_post_handshake_sent_cb)(void *_cb_arg);
+typedef ssize_t (*tls13_phh_recv_cb)(void *_cb_arg, CBS *cbs);
+typedef void (*tls13_phh_sent_cb)(void *_cb_arg);
 typedef ssize_t (*tls13_read_cb)(void *_buf, size_t _buflen, void *_cb_arg);
 typedef ssize_t (*tls13_write_cb)(const void *_buf, size_t _buflen,
     void *_cb_arg);
@@ -111,8 +111,8 @@ struct tls13_record_layer;
 
 struct tls13_record_layer *tls13_record_layer_new(tls13_read_cb wire_read,
     tls13_write_cb wire_write, tls13_alert_cb alert_cb,
-    tls13_post_handshake_recv_cb post_handshake_recv_cb,
-    tls13_post_handshake_sent_cb post_handshake_sent_cb, void *cb_arg);
+    tls13_phh_recv_cb phh_recv_cb,
+    tls13_phh_sent_cb phh_sent_cb, void *cb_arg);
 void tls13_record_layer_free(struct tls13_record_layer *rl);
 void tls13_record_layer_set_aead(struct tls13_record_layer *rl,
     const EVP_AEAD *aead);
@@ -172,7 +172,16 @@ struct tls13_ctx {
 
 	struct tls13_record_layer *rl;
 	struct tls13_handshake_msg *hs_msg;
+	uint8_t key_update_request;
+	int phh_count;
+	time_t phh_last_seen;
 };
+#ifndef TLS13_PHH_LIMIT_TIME
+#define TLS13_PHH_LIMIT_TIME 3600
+#endif
+#ifndef TLS13_PHH_LIMIT
+#define TLS13_PHH_LIMIT 100
+#endif
 
 struct tls13_ctx *tls13_ctx_new(int mode);
 void tls13_ctx_free(struct tls13_ctx *ctx);
diff --git a/lib/libssl/tls13_lib.c b/lib/libssl/tls13_lib.c
index 61ca3d46821..6876528f50d 100644
--- a/lib/libssl/tls13_lib.c
+++ b/lib/libssl/tls13_lib.c
@@ -1,6 +1,7 @@
-/*	$OpenBSD: tls13_lib.c,v 1.12 2019/11/17 00:10:47 beck Exp $ */
+/*	$OpenBSD: tls13_lib.c,v 1.13 2019/11/26 23:46:18 beck Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
+ * Copyright (c) 2019 Bob Beck <beck@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -90,6 +91,149 @@ tls13_alert_received_cb(uint8_t alert_desc, void *arg)
 	SSL_CTX_remove_session(s->ctx, s->session);
 }
 
+static int
+tls13_phh_update_local_traffic_secret(struct tls13_ctx *ctx)
+{
+	struct tls13_secrets *secrets = ctx->hs->secrets;
+
+	if (ctx->mode == TLS13_HS_CLIENT)
+		return (tls13_update_client_traffic_secret(secrets) &&
+		    tls13_record_layer_set_write_traffic_key(ctx->rl,
+			&secrets->client_application_traffic));
+	return (tls13_update_server_traffic_secret(secrets) &&
+	    tls13_record_layer_set_read_traffic_key(ctx->rl,
+	    &secrets->server_application_traffic));
+}
+
+static int
+tls13_phh_update_peer_traffic_secret(struct tls13_ctx *ctx)
+{
+	struct tls13_secrets *secrets = ctx->hs->secrets;
+
+	if (ctx->mode == TLS13_HS_CLIENT)
+		return (tls13_update_server_traffic_secret(secrets) &&
+		    tls13_record_layer_set_read_traffic_key(ctx->rl,
+		    &secrets->server_application_traffic));
+	return (tls13_update_client_traffic_secret(secrets) &&
+	    tls13_record_layer_set_write_traffic_key(ctx->rl,
+	    &secrets->client_application_traffic));
+}
+
+/*
+ * XXX arbitrarily chosen limit of 100 post handshake handshake
+ * messages in an hour - to avoid a hostile peer from constantly
+ * requesting certificates or key renegotiaitons, etc.
+ */
+static int
+tls13_phh_limit_check(struct tls13_ctx *ctx)
+{
+	time_t now = time(NULL);
+
+	if (ctx->phh_last_seen > now - TLS13_PHH_LIMIT_TIME) {
+		if (ctx->phh_count > TLS13_PHH_LIMIT)
+			return 0;
+	} else
+		ctx->phh_count = 0;
+	ctx->phh_count++;
+	ctx->phh_last_seen = now;
+	return 1;
+}
+
+static ssize_t
+tls13_key_update_recv(struct tls13_ctx *ctx, CBS *cbs)
+{
+	ssize_t ret = TLS13_IO_FAILURE;
+
+	if (!CBS_get_u8(cbs, &ctx->key_update_request))
+		goto err;
+	if (CBS_len(cbs) != 0)
+		goto err;
+
+	if (!tls13_phh_update_peer_traffic_secret(ctx))
+		goto err;
+
+	if (ctx->key_update_request) {
+		CBB cbb;
+		CBS cbs; /* XXX */
+
+		free(ctx->hs_msg);
+		ctx->hs_msg = tls13_handshake_msg_new();
+		if (!tls13_handshake_msg_start(ctx->hs_msg, &cbb, TLS13_MT_KEY_UPDATE))
+			goto err;
+		if (!CBB_add_u8(&cbb, 0))
+			goto err;
+		if (!tls13_handshake_msg_finish(ctx->hs_msg))
+			goto err;
+		tls13_handshake_msg_data(ctx->hs_msg, &cbs);
+		ret = tls13_record_layer_phh(ctx->rl, &cbs);
+
+		tls13_handshake_msg_free(ctx->hs_msg);
+		ctx->hs_msg = NULL;
+	} else
+		ret = TLS13_IO_SUCCESS;
+
+	return ret;
+ err:
+	ctx->key_update_request = 0;
+	/* XXX alert */
+	return TLS13_IO_FAILURE;
+}
+
+static void
+tls13_phh_done_cb(void *cb_arg)
+{
+	struct tls13_ctx *ctx = cb_arg;
+
+	if (ctx->key_update_request) {
+		tls13_phh_update_local_traffic_secret(ctx);
+		ctx->key_update_request = 0;
+	}
+}
+
+static ssize_t
+tls13_phh_received_cb(void *cb_arg, CBS *cbs)
+{
+	ssize_t ret = TLS13_IO_FAILURE;
+	struct tls13_ctx *ctx = cb_arg;
+	CBS phh_cbs;
+
+	if (!tls13_phh_limit_check(ctx))
+		return tls13_send_alert(ctx->rl, SSL3_AD_UNEXPECTED_MESSAGE);
+
+	if ((ctx->hs_msg == NULL) &&
+	    ((ctx->hs_msg = tls13_handshake_msg_new()) == NULL))
+		return TLS13_IO_FAILURE;
+
+	if (!tls13_handshake_msg_set_buffer(ctx->hs_msg, cbs))
+		return TLS13_IO_FAILURE;
+
+	if ((ret = tls13_handshake_msg_recv(ctx->hs_msg, ctx->rl))
+	    != TLS13_IO_SUCCESS)
+		return ret;
+
+	if (!tls13_handshake_msg_content(ctx->hs_msg, &phh_cbs))
+		return TLS13_IO_FAILURE;
+
+	switch(tls13_handshake_msg_type(ctx->hs_msg)) {
+	case TLS13_MT_KEY_UPDATE:
+		ret = tls13_key_update_recv(ctx, &phh_cbs);
+		break;
+	case TLS13_MT_NEW_SESSION_TICKET:
+		/* XXX do nothing for now and ignore this */
+		break;
+	case TLS13_MT_CERTIFICATE_REQUEST:
+		/* XXX add support if we choose to advertise this */
+		/* FALLTHROUGH */
+	default:
+		ret = TLS13_IO_FAILURE; /* XXX send alert */
+		break;
+	}
+
+	tls13_handshake_msg_free(ctx->hs_msg);
+	ctx->hs_msg = NULL;
+	return ret;
+}
+
 struct tls13_ctx *
 tls13_ctx_new(int mode)
 {
@@ -101,8 +245,8 @@ tls13_ctx_new(int mode)
 	ctx->mode = mode;
 
 	if ((ctx->rl = tls13_record_layer_new(tls13_legacy_wire_read_cb,
-	    tls13_legacy_wire_write_cb, tls13_alert_received_cb, NULL, NULL,
-	    ctx)) == NULL)
+	    tls13_legacy_wire_write_cb, tls13_alert_received_cb,
+	    tls13_phh_received_cb, tls13_phh_done_cb, ctx)) == NULL)
 		goto err;
 
 	return ctx;
diff --git a/lib/libssl/tls13_record_layer.c b/lib/libssl/tls13_record_layer.c
index 188f56e0b48..feaca531811 100644
--- a/lib/libssl/tls13_record_layer.c
+++ b/lib/libssl/tls13_record_layer.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_record_layer.c,v 1.15 2019/11/18 02:44:20 jsing Exp $ */
+/* $OpenBSD: tls13_record_layer.c,v 1.16 2019/11/26 23:46:18 beck Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -30,6 +30,7 @@ static ssize_t tls13_record_layer_write_record(struct tls13_record_layer *rl,
 struct tls13_record_layer {
 	int change_cipher_spec_seen;
 	int handshake_completed;
+	int phh;
 
 	/*
 	 * Read and/or write channels are closed due to an alert being
@@ -76,8 +77,8 @@ struct tls13_record_layer {
 
 	/* Record callbacks. */
 	tls13_alert_cb alert_cb;
-	tls13_post_handshake_recv_cb post_handshake_recv_cb;
-	tls13_post_handshake_sent_cb post_handshake_sent_cb;
+	tls13_phh_recv_cb phh_recv_cb;
+	tls13_phh_sent_cb phh_sent_cb;
 
 	/* Wire read/write callbacks. */
 	tls13_read_cb wire_read;
@@ -112,8 +113,8 @@ tls13_record_layer_wrec_free(struct tls13_record_layer *rl)
 struct tls13_record_layer *
 tls13_record_layer_new(tls13_read_cb wire_read, tls13_write_cb wire_write,
     tls13_alert_cb alert_cb,
-    tls13_post_handshake_recv_cb post_handshake_recv_cb,
-    tls13_post_handshake_sent_cb post_handshake_sent_cb,
+    tls13_phh_recv_cb phh_recv_cb,
+    tls13_phh_sent_cb phh_sent_cb,
     void *cb_arg)
 {
 	struct tls13_record_layer *rl;
@@ -124,8 +125,8 @@ tls13_record_layer_new(tls13_read_cb wire_read, tls13_write_cb wire_write,
 	rl->wire_read = wire_read;
 	rl->wire_write = wire_write;
 	rl->alert_cb = alert_cb;
-	rl->post_handshake_recv_cb = post_handshake_recv_cb;
-	rl->post_handshake_sent_cb = post_handshake_sent_cb;
+	rl->phh_recv_cb = phh_recv_cb;
+	rl->phh_sent_cb = phh_sent_cb;
 	rl->cb_arg = cb_arg;
 
 	return rl;
@@ -304,6 +305,8 @@ tls13_record_layer_send_phh(struct tls13_record_layer *rl)
 
 	CBS_init(&rl->phh_cbs, rl->phh_data, rl->phh_len);
 
+	rl->phh_sent_cb(rl->cb_arg);
+
 	return TLS13_IO_SUCCESS;
 }
 
@@ -812,6 +815,16 @@ tls13_record_layer_read(struct tls13_record_layer *rl, uint8_t content_type,
 
 		/* XXX - need to check record version. */
 	}
+
+	/*
+	 * If we are in post handshake handshake mode, we may not see
+	 * any record type that isn't a handshake until we are done.
+	 */
+	if (rl->phh && rl->rbuf_content_type != SSL3_RT_HANDSHAKE) {
+		/* XXX send unexpected message alert */
+		return TLS13_IO_FAILURE;
+	}
+
 	if (rl->rbuf_content_type != content_type) {
 		/*
 		 * Handshake content can appear as post-handshake messages (yup,
@@ -821,15 +834,46 @@ tls13_record_layer_read(struct tls13_record_layer *rl, uint8_t content_type,
 		 */
 		if (rl->rbuf_content_type == SSL3_RT_HANDSHAKE) {
 			if (rl->handshake_completed) {
-				if (rl->post_handshake_recv_cb != NULL)
-					rl->post_handshake_recv_cb(
+				rl->phh = 1;
+				ret = TLS13_IO_FAILURE;
+
+				/*
+				 * The post handshake handshake
+				 * receive callback is allowed to
+				 * return:
+				 *
+				 * TLS13_IO_WANT_POLLIN ->
+				 * I need more handshake data.
+				 *
+				 * TLS13_IO_WANT_POLLOUT -> I got the
+				 * whole handshake message, and have
+				 * enqueued a response
+				 *
+				 * TLS13_IO_SUCCESS -> I got the whole handshake,
+				 * nothing more to do
+				 *
+				 * TLS13_IO_FAILURE -> something broke.
+				 */
+				if (rl->phh_recv_cb != NULL) {
+					ret = rl->phh_recv_cb(
 					    rl->cb_arg, &rl->rbuf_cbs);
+				}
+
 				tls13_record_layer_rbuf_free(rl);
+
+				if (ret == TLS13_IO_WANT_POLLIN)
+					return ret;
+
 				/*
-				 * XXX if handshake or alert queued
-				 *  return POLLOUT
+				 * leave post handshake handshake mode
+				 * if we do not need more handshake data
 				 */
-				return TLS13_IO_WANT_POLLIN;
+				rl->phh = 0;
+
+				if (ret == TLS13_IO_SUCCESS)
+					return TLS13_IO_WANT_POLLIN;
+
+				return ret;
 			}
 		}