1 files changed, 43 insertions, 11 deletions

diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index 6c915a72890..2dd3328d71e 100644
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -860,6 +860,8 @@ CheckMD5Auth(Port *port, char *shadow_pass, char **logdetail)
 static int
 CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 {
+	char	   *sasl_mechs;
+	char	   *p;
 	int			mtype;
 	StringInfoData buf;
 	void	   *scram_opaq;
@@ -869,6 +871,8 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 	int			inputlen;
 	int			result;
 	bool		initial;
+	char	   *tls_finished = NULL;
+	size_t		tls_finished_len = 0;
 
 	/*
 	 * SASL auth is not supported for protocol versions before 3, because it
@@ -885,12 +889,39 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 
 	/*
 	 * Send the SASL authentication request to user.  It includes the list of
-	 * authentication mechanisms (which is trivial, because we only support
-	 * SCRAM-SHA-256 at the moment).  The extra "\0" is for an empty string to
-	 * terminate the list.
+	 * authentication mechanisms that are supported.  The order of mechanisms
+	 * is advertised in decreasing order of importance.  So the
+	 * channel-binding variants go first, if they are supported.  Channel
+	 * binding is only supported in SSL builds.
 	 */
-	sendAuthRequest(port, AUTH_REQ_SASL, SCRAM_SHA256_NAME "\0",
-					strlen(SCRAM_SHA256_NAME) + 2);
+	sasl_mechs = palloc(strlen(SCRAM_SHA256_PLUS_NAME) +
+						strlen(SCRAM_SHA256_NAME) + 3);
+	p = sasl_mechs;
+
+	if (port->ssl_in_use)
+	{
+		strcpy(p, SCRAM_SHA256_PLUS_NAME);
+		p += strlen(SCRAM_SHA256_PLUS_NAME) + 1;
+	}
+
+	strcpy(p, SCRAM_SHA256_NAME);
+	p += strlen(SCRAM_SHA256_NAME) + 1;
+
+	/* Put another '\0' to mark that list is finished. */
+	p[0] = '\0';
+
+	sendAuthRequest(port, AUTH_REQ_SASL, sasl_mechs, p - sasl_mechs + 1);
+	pfree(sasl_mechs);
+
+#ifdef USE_SSL
+	/*
+	 * Get data for channel binding.
+	 */
+	if (port->ssl_in_use)
+	{
+		tls_finished = be_tls_get_peer_finished(port, &tls_finished_len);
+	}
+#endif
 
 	/*
 	 * Initialize the status tracker for message exchanges.
@@ -903,7 +934,11 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 	 * This is because we don't want to reveal to an attacker what usernames
 	 * are valid, nor which users have a valid password.
 	 */
-	scram_opaq = pg_be_scram_init(port->user_name, shadow_pass);
+	scram_opaq = pg_be_scram_init(port->user_name,
+								  shadow_pass,
+								  port->ssl_in_use,
+								  tls_finished,
+								  tls_finished_len);
 
 	/*
 	 * Loop through SASL message exchange.  This exchange can consist of
@@ -951,12 +986,9 @@ CheckSCRAMAuth(Port *port, char *shadow_pass, char **logdetail)
 		{
 			const char *selected_mech;
 
-			/*
-			 * We only support SCRAM-SHA-256 at the moment, so anything else
-			 * is an error.
-			 */
 			selected_mech = pq_getmsgrawstring(&buf);
-			if (strcmp(selected_mech, SCRAM_SHA256_NAME) != 0)
+			if (strcmp(selected_mech, SCRAM_SHA256_NAME) != 0 &&
+				strcmp(selected_mech, SCRAM_SHA256_PLUS_NAME) != 0)
 			{
 				ereport(ERROR,
 						(errcode(ERRCODE_PROTOCOL_VIOLATION),