ssl: Implement option honor_cipher_order in TLS 1.3

2 files changed, 67 insertions, 12 deletions

diff --git a/lib/ssl/src/tls_handshake_1_3.erl b/lib/ssl/src/tls_handshake_1_3.erl
index 6aeb9f5663..c29366e717 100644
--- a/lib/ssl/src/tls_handshake_1_3.erl
+++ b/lib/ssl/src/tls_handshake_1_3.erl
@@ -504,7 +504,8 @@ do_start(#client_hello{cipher_suites = ClientCiphers,
                 ssl_options = #ssl_options{ciphers = ServerCiphers,
                                            signature_algs = ServerSignAlgs,
                                            supported_groups = ServerGroups0,
-                                           alpn_preferred_protocols = ALPNPreferredProtocols},
+                                           alpn_preferred_protocols = ALPNPreferredProtocols,
+                                           honor_cipher_order = HonorCipherOrder},
                 session = #session{own_certificate = Cert}} = State0) ->
     ClientGroups0 = maps:get(elliptic_curves, Extensions, undefined),
     ClientGroups = get_supported_groups(ClientGroups0),
@@ -531,7 +532,7 @@ do_start(#client_hello{cipher_suites = ClientCiphers,
         %% cipher suite, an (EC)DHE group and key share for key establishment,
         %% and a signature algorithm/certificate pair to authenticate itself to
         %% the client.
-        Cipher = Maybe(select_cipher_suite(ClientCiphers, ServerCiphers)),
+        Cipher = Maybe(select_cipher_suite(HonorCipherOrder, ClientCiphers, ServerCiphers)),
         Groups = Maybe(select_common_groups(ServerGroups, ClientGroups)),
         Maybe(validate_client_key_share(ClientGroups, ClientShares)),
 
@@ -1731,15 +1732,19 @@ handle_alpn([ServerProtocol|T], ClientProtocols) ->
     end.
 
 
-select_cipher_suite([], _) ->
+select_cipher_suite(_, [], _) ->
     {error, no_suitable_cipher};
-select_cipher_suite([Cipher|ClientCiphers], ServerCiphers) ->
+%% If honor_cipher_order is set to true, use the server's preference for
+%% cipher suite selection.
+select_cipher_suite(true, ClientCiphers, ServerCiphers) ->
+    select_cipher_suite(false, ServerCiphers, ClientCiphers);
+select_cipher_suite(false, [Cipher|ClientCiphers], ServerCiphers) ->
     case lists:member(Cipher, tls_v1:suites('TLS_v1.3')) andalso
         lists:member(Cipher, ServerCiphers) of
         true ->
             {ok, Cipher};
         false ->
-            select_cipher_suite(ClientCiphers, ServerCiphers)
+            select_cipher_suite(false, ClientCiphers, ServerCiphers)
     end.
 
 
diff --git a/lib/ssl/test/ssl_api_SUITE.erl b/lib/ssl/test/ssl_api_SUITE.erl
index a7b2a71690..4b44b4dc3e 100644
--- a/lib/ssl/test/ssl_api_SUITE.erl
+++ b/lib/ssl/test/ssl_api_SUITE.erl
@@ -127,7 +127,9 @@ beast_mitigation_test() ->
 
 tls13_group() ->
     [
-     supported_groups
+     supported_groups,
+     honor_server_cipher_order_tls13,
+     honor_client_cipher_order_tls13
     ].
 
 
@@ -1198,11 +1200,35 @@ honor_server_cipher_order(Config) when is_list(Config) ->
                        cipher => aes_128_cbc, 
                        mac => sha,
                        prf => default_prf}],
-    honor_cipher_order(Config, true, ServerCiphers, ClientCiphers, #{key_exchange => dhe_rsa, 
-                                                                     cipher => aes_256_cbc, 
+    honor_cipher_order(Config, true, ServerCiphers, ClientCiphers, #{key_exchange => dhe_rsa,
+                                                                     cipher => aes_256_cbc,
                                                                      mac => sha,
                                                                      prf => default_prf}).
 %%--------------------------------------------------------------------
+honor_server_cipher_order_tls13() ->
+    [{doc,"Test API honor server cipher order in TLS 1.3."}].
+honor_server_cipher_order_tls13(Config) when is_list(Config) ->
+    ClientCiphers = [#{key_exchange => any,
+                       cipher => aes_256_gcm,
+                       mac => aead,
+                       prf => sha384},
+                     #{key_exchange => any,
+                       cipher => aes_128_gcm,
+                       mac => aead,
+                       prf => sha256}],
+    ServerCiphers = [#{key_exchange => any,
+                       cipher => aes_128_gcm,
+                       mac => aead,
+                       prf => sha256},
+                     #{key_exchange => any,
+                       cipher => aes_256_gcm,
+                       mac => aead,
+                       prf => sha384}],
+    honor_cipher_order(Config, true, ServerCiphers, ClientCiphers, #{key_exchange => any,
+                                                                     cipher => aes_128_gcm,
+                                                                     mac => aead,
+                                                                     prf => sha256}).
+%%--------------------------------------------------------------------
 honor_client_cipher_order() ->
     [{doc,"Test API honor server cipher order."}].
 honor_client_cipher_order(Config) when is_list(Config) ->
@@ -1222,10 +1248,34 @@ honor_client_cipher_order(Config) when is_list(Config) ->
                        cipher => aes_128_cbc, 
                        mac => sha,
                        prf => default_prf}],
-honor_cipher_order(Config, false, ServerCiphers, ClientCiphers, #{key_exchange => dhe_rsa, 
-                                                                  cipher => aes_128_cbc, 
-                                                                  mac => sha,
-                                                                  prf => default_prf}).
+    honor_cipher_order(Config, false, ServerCiphers, ClientCiphers, #{key_exchange => dhe_rsa,
+                                                                      cipher => aes_128_cbc,
+                                                                      mac => sha,
+                                                                      prf => default_prf}).
+%%--------------------------------------------------------------------
+honor_client_cipher_order_tls13() ->
+    [{doc,"Test API honor server cipher order in TLS 1.3."}].
+honor_client_cipher_order_tls13(Config) when is_list(Config) ->
+    ClientCiphers = [#{key_exchange => any,
+                       cipher => aes_256_gcm,
+                       mac => aead,
+                       prf => sha384},
+                     #{key_exchange => any,
+                       cipher => aes_128_gcm,
+                       mac => aead,
+                       prf => sha256}],
+    ServerCiphers = [#{key_exchange => any,
+                       cipher => aes_128_gcm,
+                       mac => aead,
+                       prf => sha256},
+                     #{key_exchange => any,
+                       cipher => aes_256_gcm,
+                       mac => aead,
+                       prf => sha384}],
+    honor_cipher_order(Config, false, ServerCiphers, ClientCiphers, #{key_exchange => any,
+                                                                      cipher => aes_256_gcm,
+                                                                      mac => aead,
+                                                                      prf => sha384}).
 %%--------------------------------------------------------------------
 ipv6() ->
     [{require, ipv6_hosts},