gnutls_session_get_flags: introduced GNUTLS_SFLAGS_RFC7919

This allows checking whether the DHE parameters used were negotiated
using RFC7919.

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

5 files changed, 14 insertions, 6 deletions

diff --git a/lib/auth/dh_common.c b/lib/auth/dh_common.c
index df57747183..6d6a7e5648 100644
--- a/lib/auth/dh_common.c
+++ b/lib/auth/dh_common.c
@@ -188,8 +188,9 @@ _gnutls_proc_dh_common_server_kx(gnutls_session_t session,
 	int i, bits, ret, p_bits;
 	unsigned j;
 	ssize_t data_size = _data_size;
-	unsigned used_ffdhe = 0;
-	
+
+	session->internals.used_ffdhe = 0;
+
 	/* just in case we are resuming a session */
 	gnutls_pk_params_release(&session->key.dh_params);
 
@@ -242,14 +243,14 @@ _gnutls_proc_dh_common_server_kx(gnutls_session_t session,
 			    memcmp(session->internals.priorities->groups.entry[j]->prime->data,
 				   data_p, n_p) == 0) {
 
-				used_ffdhe = 1;
+				session->internals.used_ffdhe = 1;
 				_gnutls_session_group_set(session, session->internals.priorities->groups.entry[j]);
 				session->key.dh_params.qbits = *session->internals.priorities->groups.entry[j]->q_bits;
 				break;
 			}
 		}
 
-		if (!used_ffdhe) {
+		if (!session->internals.used_ffdhe) {
 			_gnutls_audit_log(session, "FFDHE groups advertised, but server didn't support it; falling back to server's choice\n");
 		}
 	}
@@ -269,7 +270,7 @@ _gnutls_proc_dh_common_server_kx(gnutls_session_t session,
 	session->key.dh_params.params_nr = 3; /* include empty q */
 	session->key.dh_params.algo = GNUTLS_PK_DH;
 
-	if (used_ffdhe == 0) {
+	if (session->internals.used_ffdhe == 0) {
 		bits = _gnutls_dh_get_min_prime_bits(session);
 		if (bits < 0) {
 			gnutls_assert();
diff --git a/lib/dh.c b/lib/dh.c
index 4686736946..c8e84680f9 100644
--- a/lib/dh.c
+++ b/lib/dh.c
@@ -79,6 +79,7 @@ _gnutls_figure_dh_params(gnutls_session_t session, gnutls_dh_params_t dh_params,
 	group = get_group(session);
 
 	params.deinit = 0;
+	session->internals.used_ffdhe = 0;
 
 	/* if we negotiated RFC7919 FFDHE */
 	if (group && group->pk == GNUTLS_PK_DH) {
@@ -100,6 +101,7 @@ _gnutls_figure_dh_params(gnutls_session_t session, gnutls_dh_params_t dh_params,
 					goto cleanup;
 				}
 
+				session->internals.used_ffdhe = 1;
 				q_bits = *session->internals.priorities->groups.entry[i]->q_bits;
 				goto finished;
 			}
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index c0e0d7eed7..76e64083b2 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -1115,6 +1115,7 @@ typedef struct {
 
 	/* whether the peer has advertized at least an FFDHE group */
 	bool have_ffdhe;
+	bool used_ffdhe; /* whether ffdhe was actually negotiated and used */
 
 	/* candidate groups to be selected for security params groups */
 	const gnutls_group_entry_st *cand_ec_group;
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index fd6f063cc4..6c92600de6 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1294,6 +1294,7 @@ unsigned gnutls_session_etm_status(gnutls_session_t session);
  * @GNUTLS_SFLAGS_SAFE_RENEGOTIATION: Safe renegotiation (RFC5746) was used
  * @GNUTLS_SFLAGS_EXT_MASTER_SECRET: The extended master secret (RFC7627) extension was used
  * @GNUTLS_SFLAGS_ETM: The encrypt then MAC (RFC7366) extension was used
+ * @GNUTLS_SFLAGS_RFC7919: The RFC7919 Diffie-Hellman parameters were negotiated
  * @GNUTLS_SFLAGS_HB_LOCAL_SEND: The heartbeat negotiation allows the local side to send heartbeat messages
  * @GNUTLS_SFLAGS_HB_PEER_SEND: The heartbeat negotiation allows the peer to send heartbeat messages
  * @GNUTLS_SFLAGS_FALSE_START: The appdata set with gnutls_handshake_set_appdata() were sent during handshake (false start)
@@ -1306,7 +1307,8 @@ typedef enum {
 	GNUTLS_SFLAGS_ETM = 1<<2,
 	GNUTLS_SFLAGS_HB_LOCAL_SEND = 1<<3,
 	GNUTLS_SFLAGS_HB_PEER_SEND = 1<<4,
-	GNUTLS_SFLAGS_FALSE_START = 1<<5
+	GNUTLS_SFLAGS_FALSE_START = 1<<5,
+	GNUTLS_SFLAGS_RFC7919 = 1<<6
 } gnutls_session_flags_t;
 
 unsigned gnutls_session_get_flags(gnutls_session_t session);
diff --git a/lib/state.c b/lib/state.c
index edcabeba96..1551fa9794 100644
--- a/lib/state.c
+++ b/lib/state.c
@@ -1266,6 +1266,8 @@ unsigned gnutls_session_get_flags(gnutls_session_t session)
 		flags |= GNUTLS_SFLAGS_HB_PEER_SEND;
 	if (session->internals.false_start_used)
 		flags |= GNUTLS_SFLAGS_FALSE_START;
+	if (session->internals.used_ffdhe)
+		flags |= GNUTLS_SFLAGS_RFC7919;
 
 	return flags;
 }