tls13: do not send OCSP responses as client without server requesting

In client side ensure we see a request for OCSP from servers before
sending one.

Relates: #876

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

6 files changed, 21 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index 68a36e7ec1..23b4859682 100644
--- a/NEWS
+++ b/NEWS
@@ -41,6 +41,9 @@ See the end for copying conditions.
    to accepting it. This addresses the problem of accepting CAs which would
    have been marked as insecure otherwise (#877).
 
+** libgnutls: On client side only send OCSP staples if they have been requested
+   by the server (#876).
+
 ** libgnutls: The default-priority-string added to system configuration
    to allow overriding compiled-in default-priority-string.
 
@@ -56,6 +59,7 @@ See the end for copying conditions.
 
 ** API and ABI modifications:
 GNUTLS_SFLAGS_CLI_REQUESTED_OCSP: Added
+GNUTLS_SFLAGS_SERV_REQUESTED_OCSP: Added
 gnutls_ocsp_req_const_t: Added
 
 
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index f7cf830ca1..b48805190a 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -1383,6 +1383,7 @@ typedef struct {
 #define HSK_RECORD_SIZE_LIMIT_SENT (1<<25) /* record_size_limit extension was sent */
 #define HSK_RECORD_SIZE_LIMIT_RECEIVED (1<<26) /* server: record_size_limit extension was seen but not accepted yet */
 #define HSK_OCSP_REQUESTED (1<<27) /* server: client requested OCSP stapling */
+#define HSK_CLIENT_OCSP_REQUESTED (1<<28) /* client: server requested OCSP stapling */
 
 	/* The hsk_flags are for use within the ongoing handshake;
 	 * they are reset to zero prior to handshake start by gnutls_handshake. */
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index 1d0f924c26..61232de01b 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1570,6 +1570,7 @@ unsigned gnutls_session_etm_status(gnutls_session_t session);
  * @GNUTLS_SFLAGS_EARLY_START: The TLS1.3 server session returned early.
  * @GNUTLS_SFLAGS_EARLY_DATA: The TLS1.3 early data has been received by the server.
  * @GNUTLS_SFLAGS_CLI_REQUESTED_OCSP: Set when the client has requested OCSP staple during handshake.
+ * @GNUTLS_SFLAGS_SERV_REQUESTED_OCSP: Set when the server has requested OCSP staple during handshake.
  *
  * Enumeration of different session parameters.
  */
@@ -1585,7 +1586,8 @@ typedef enum {
 	GNUTLS_SFLAGS_POST_HANDSHAKE_AUTH = 1<<8,
 	GNUTLS_SFLAGS_EARLY_START = 1<<9,
 	GNUTLS_SFLAGS_EARLY_DATA = 1<<10,
-	GNUTLS_SFLAGS_CLI_REQUESTED_OCSP = 1<<11
+	GNUTLS_SFLAGS_CLI_REQUESTED_OCSP = 1<<11,
+	GNUTLS_SFLAGS_SERV_REQUESTED_OCSP = 1<<12
 } gnutls_session_flags_t;
 
 unsigned gnutls_session_get_flags(gnutls_session_t session);
diff --git a/lib/state.c b/lib/state.c
index 5e3a7f95aa..dff7312a87 100644
--- a/lib/state.c
+++ b/lib/state.c
@@ -1576,6 +1576,8 @@ unsigned gnutls_session_get_flags(gnutls_session_t session)
 		flags |= GNUTLS_SFLAGS_EARLY_DATA;
 	if (session->internals.hsk_flags & HSK_OCSP_REQUESTED)
 		flags |= GNUTLS_SFLAGS_CLI_REQUESTED_OCSP;
+	if (session->internals.hsk_flags & HSK_CLIENT_OCSP_REQUESTED)
+		flags |= GNUTLS_SFLAGS_SERV_REQUESTED_OCSP;
 
 	return flags;
 }
diff --git a/lib/tls13/certificate.c b/lib/tls13/certificate.c
index 82a45af336..7483251a53 100644
--- a/lib/tls13/certificate.c
+++ b/lib/tls13/certificate.c
@@ -273,7 +273,8 @@ int _gnutls13_send_certificate(gnutls_session_t session, unsigned again)
 #ifdef ENABLE_OCSP
 			if ((session->internals.selected_ocsp_length > 0 ||
 			     session->internals.selected_ocsp_func) &&
-			     (session->internals.hsk_flags & HSK_OCSP_REQUESTED)) {
+			     (((session->internals.hsk_flags & HSK_OCSP_REQUESTED) && IS_SERVER(session)) ||
+			     ((session->internals.hsk_flags & HSK_CLIENT_OCSP_REQUESTED) && !IS_SERVER(session)))) {
 				/* append status response if available */
 				ret = _gnutls_extv_append_init(&buf);
 				if (ret < 0) {
diff --git a/lib/tls13/certificate_request.c b/lib/tls13/certificate_request.c
index 58fdbbc187..7c0eb04d9b 100644
--- a/lib/tls13/certificate_request.c
+++ b/lib/tls13/certificate_request.c
@@ -26,6 +26,7 @@
 #include "handshake.h"
 #include "tls13/certificate_request.h"
 #include "ext/signature.h"
+#include "ext/status_request.h"
 #include "mbuffers.h"
 #include "algorithms.h"
 #include "auth/cert.h"
@@ -108,6 +109,14 @@ int parse_cert_extension(void *_ctx, unsigned tls_id, const uint8_t *data, unsig
 
 			ctx->pk_algos[ctx->pk_algos_length++] = se->pk;
 		}
+#ifdef ENABLE_OCSP
+	} else if (tls_id == ext_mod_status_request.tls_id) {
+		if (data_size != 0)
+			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);
+
+		/* we are now allowed to send OCSP staples */
+		session->internals.hsk_flags |= HSK_CLIENT_OCSP_REQUESTED;
+#endif
 	} else if (tls_id == EXTID_CERTIFICATE_AUTHORITIES) {
 		if (data_size < 3) {
 			return gnutls_assert_val(GNUTLS_E_TLS_PACKET_DECODING_ERROR);