OpenSSL: Allow cipher list to be overridden for tls_suiteb=1 case

This allows wpa_supplicant configuration with phase1="tls_suiteb=1" to
use openssl_ciphers="ECDHE-RSA-AES256-GCM-SHA384" to further limit the
possible TLS cipher suites when using Suite B with RSA >3K keys. This
combination disables use of DHE and as such, mandates ECDHE to be used.

Signed-off-by: Jouni Malinen <j@w1.fi>

diff --git a/src/crypto/tls_openssl.c b/src/crypto/tls_openssl.c
index 92aa711d2c59948e35e5ae5de1cc007bbcc91526..425d60f9daa6b818f2e53cd93ce18e4c89c077e9 100644 (file)
--- a/src/crypto/tls_openssl.c
+++ b/src/crypto/tls_openssl.c
@@ -2433,7 +2433,8 @@ static int suiteb_cert_cb(SSL *ssl, void *arg)
 #endif /* CONFIG_SUITEB */
 
 
-static int tls_set_conn_flags(struct tls_connection *conn, unsigned int flags)
+static int tls_set_conn_flags(struct tls_connection *conn, unsigned int flags,
+                             const char *openssl_ciphers)
 {
        SSL *ssl = conn->ssl;
 
@@ -2467,6 +2468,12 @@ static int tls_set_conn_flags(struct tls_connection *conn, unsigned int flags)
        if (flags & TLS_CONN_SUITEB_NO_ECDH) {
                const char *ciphers = "DHE-RSA-AES256-GCM-SHA384";
 
+               if (openssl_ciphers) {
+                       wpa_printf(MSG_DEBUG,
+                                  "OpenSSL: Override ciphers for Suite B (no ECDH): %s",
+                                  openssl_ciphers);
+                       ciphers = openssl_ciphers;
+               }
                if (SSL_set_cipher_list(ssl, ciphers) != 1) {
                        wpa_printf(MSG_INFO,
                                   "OpenSSL: Failed to set Suite B ciphers");
@@ -2477,6 +2484,12 @@ static int tls_set_conn_flags(struct tls_connection *conn, unsigned int flags)
                const char *ciphers =
                        "ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384";
 
+               if (openssl_ciphers) {
+                       wpa_printf(MSG_DEBUG,
+                                  "OpenSSL: Override ciphers for Suite B: %s",
+                                  openssl_ciphers);
+                       ciphers = openssl_ciphers;
+               }
                if (SSL_set_cipher_list(ssl, ciphers) != 1) {
                        wpa_printf(MSG_INFO,
                                   "OpenSSL: Failed to set Suite B ciphers");
@@ -2545,7 +2558,7 @@ int tls_connection_set_verify(void *ssl_ctx, struct tls_connection *conn,
                SSL_set_verify(conn->ssl, SSL_VERIFY_NONE, NULL);
        }
 
-       if (tls_set_conn_flags(conn, flags) < 0)
+       if (tls_set_conn_flags(conn, flags, NULL) < 0)
                return -1;
        conn->flags = flags;
 
@@ -4362,7 +4375,8 @@ int tls_connection_set_params(void *tls_ctx, struct tls_connection *conn,
                return -1;
        }
 
-       if (tls_set_conn_flags(conn, params->flags) < 0)
+       if (tls_set_conn_flags(conn, params->flags,
+                              params->openssl_ciphers) < 0)
                return -1;
 
 #ifdef OPENSSL_IS_BORINGSSL