Add support for certificate status requests in TLS 1.3 client

ok jsing@, tb@, inoguchi@

4 files changed, 81 insertions, 12 deletions

diff --git a/lib/libssl/ssl_tlsext.c b/lib/libssl/ssl_tlsext.c
index cb2b2cadc74..bc122686c9b 100644
--- a/lib/libssl/ssl_tlsext.c
+++ b/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.64 2020/05/09 10:51:55 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.65 2020/05/09 15:05:50 beck Exp $ */
 /*
  * Copyright (c) 2016, 2017, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -921,12 +921,43 @@ tlsext_ocsp_server_build(SSL *s, CBB *cbb)
 int
 tlsext_ocsp_client_parse(SSL *s, CBS *cbs, int *alert)
 {
-	if (s->tlsext_status_type == -1) {
-		*alert = TLS1_AD_UNSUPPORTED_EXTENSION;
-		return 0;
+	CBS response;
+	size_t stow_len;
+	uint16_t version = TLS1_get_client_version(s);
+	uint8_t status_type;
+
+	if (version >= TLS1_3_VERSION) {
+		if (!CBS_get_u8(cbs, &status_type)) {
+			SSLerror(s, SSL_R_LENGTH_MISMATCH);
+			return 0;
+		}
+		if (status_type != TLSEXT_STATUSTYPE_ocsp) {
+			SSLerror(s, SSL_R_UNSUPPORTED_STATUS_TYPE);
+			return 0;
+		}
+		if (!CBS_get_u24_length_prefixed(cbs, &response)) {
+			SSLerror(s, SSL_R_LENGTH_MISMATCH);
+			return 0;
+		}
+		if (CBS_len(&response) > 65536) {
+			SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
+			return 0;
+		}
+		if (!CBS_stow(&response, &s->internal->tlsext_ocsp_resp,
+		    &stow_len)) {
+			s->internal->tlsext_ocsp_resplen = 0;
+			*alert = SSL_AD_INTERNAL_ERROR;
+			return 0;
+		}
+		s->internal->tlsext_ocsp_resplen = (int)stow_len;
+	} else {
+		if (s->tlsext_status_type == -1) {
+			*alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+			return 0;
+		}
+		/* Set flag to expect CertificateStatus message */
+		s->internal->tlsext_status_expected = 1;
 	}
-	/* Set flag to expect CertificateStatus message */
-	s->internal->tlsext_status_expected = 1;
 	return 1;
 }
 
diff --git a/lib/libssl/tls13_client.c b/lib/libssl/tls13_client.c
index 79318d93135..aab83dcc692 100644
--- a/lib/libssl/tls13_client.c
+++ b/lib/libssl/tls13_client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_client.c,v 1.54 2020/04/28 20:37:22 jsing Exp $ */
+/* $OpenBSD: tls13_client.c,v 1.55 2020/05/09 15:05:50 beck Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -550,13 +550,13 @@ tls13_server_certificate_request_recv(struct tls13_ctx *ctx, CBS *cbs)
 int
 tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs)
 {
-	CBS cert_request_context, cert_list, cert_data, cert_exts;
+	CBS cert_request_context, cert_list, cert_data;
 	struct stack_st_X509 *certs = NULL;
 	SSL *s = ctx->ssl;
 	X509 *cert = NULL;
 	EVP_PKEY *pkey;
 	const uint8_t *p;
-	int cert_idx;
+	int cert_idx, alert_desc;
 	int ret = 0;
 
 	if ((certs = sk_X509_new_null()) == NULL)
@@ -572,8 +572,12 @@ tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs)
 	while (CBS_len(&cert_list) > 0) {
 		if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data))
 			goto err;
-		if (!CBS_get_u16_length_prefixed(&cert_list, &cert_exts))
+
+		if (!tlsext_client_parse(ctx->ssl, &cert_list, &alert_desc,
+		    SSL_TLSEXT_MSG_CT)) {
+			ctx->alert = alert_desc;
 			goto err;
+		}
 
 		p = CBS_data(&cert_data);
 		if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL)
@@ -628,6 +632,10 @@ tls13_server_certificate_recv(struct tls13_ctx *ctx, CBS *cbs)
 	s->session->peer = cert;
 	s->session->verify_result = s->verify_result;
 
+	if (ctx->ocsp_status_recv_cb != NULL &&
+	    !ctx->ocsp_status_recv_cb(ctx))
+		goto err;
+
 	ret = 1;
 
  err:
diff --git a/lib/libssl/tls13_internal.h b/lib/libssl/tls13_internal.h
index d53672dbfe5..b699b205010 100644
--- a/lib/libssl/tls13_internal.h
+++ b/lib/libssl/tls13_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_internal.h,v 1.67 2020/04/28 20:37:22 jsing Exp $ */
+/* $OpenBSD: tls13_internal.h,v 1.68 2020/05/09 15:05:50 beck Exp $ */
 /*
  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -51,6 +51,7 @@ 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);
 typedef void (*tls13_handshake_message_cb)(void *_cb_arg);
+typedef int (*tls13_ocsp_status_cb)(void *_cb_arg);
 
 /*
  * Buffers.
@@ -233,6 +234,7 @@ struct tls13_ctx {
 
 	tls13_handshake_message_cb handshake_message_sent_cb;
 	tls13_handshake_message_cb handshake_message_recv_cb;
+	tls13_ocsp_status_cb ocsp_status_recv_cb;
 };
 #ifndef TLS13_PHH_LIMIT_TIME
 #define TLS13_PHH_LIMIT_TIME 3600
diff --git a/lib/libssl/tls13_lib.c b/lib/libssl/tls13_lib.c
index 199f43ca16c..37f300ae43b 100644
--- a/lib/libssl/tls13_lib.c
+++ b/lib/libssl/tls13_lib.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tls13_lib.c,v 1.36 2020/04/28 20:30:41 jsing Exp $ */
+/*	$OpenBSD: tls13_lib.c,v 1.37 2020/05/09 15:05:50 beck Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2019 Bob Beck <beck@openbsd.org>
@@ -163,6 +163,33 @@ tls13_legacy_handshake_message_sent_cb(void *arg)
 }
 
 static int
+tls13_legacy_ocsp_status_recv_cb(void *arg)
+{
+	struct tls13_ctx *ctx = arg;
+	SSL *s = ctx->ssl;
+	int ret;
+
+	if (s->ctx->internal->tlsext_status_cb == NULL ||
+	    s->internal->tlsext_ocsp_resplen == 0)
+		return 1;
+
+	ret = s->ctx->internal->tlsext_status_cb(s,
+	    s->ctx->internal->tlsext_status_arg);
+	if (ret < 0) {
+		ctx->alert = SSL_AD_INTERNAL_ERROR;
+		SSLerror(s, ERR_R_MALLOC_FAILURE);
+		return 0;
+	}
+	if (ret == 0) {
+		ctx->alert = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
+		SSLerror(s, SSL_R_INVALID_STATUS_RESPONSE);
+		return 0;
+	}
+
+	return 1;
+}
+
+static int
 tls13_phh_update_local_traffic_secret(struct tls13_ctx *ctx)
 {
 	struct tls13_secrets *secrets = ctx->hs->secrets;
@@ -322,6 +349,7 @@ tls13_ctx_new(int mode)
 
 	ctx->handshake_message_sent_cb = tls13_legacy_handshake_message_sent_cb;
 	ctx->handshake_message_recv_cb = tls13_legacy_handshake_message_recv_cb;
+	ctx->ocsp_status_recv_cb = tls13_legacy_ocsp_status_recv_cb;
 
 	return ctx;