aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--lib/ssl/src/ssl_connection.erl67
-rw-r--r--lib/ssl/src/ssl_internal.hrl15
-rw-r--r--lib/ssl/src/tls_handshake.erl28
3 files changed, 106 insertions, 4 deletions
diff --git a/lib/ssl/src/ssl_connection.erl b/lib/ssl/src/ssl_connection.erl
index bd17f19d10..5c7f76a28b 100644
--- a/lib/ssl/src/ssl_connection.erl
+++ b/lib/ssl/src/ssl_connection.erl
@@ -1515,13 +1515,18 @@ do_server_hello(Type, #hello_extensions{next_protocol_negotiation = NextProtocol
ServerHelloExt,
#state{negotiated_version = Version,
session = #session{session_id = SessId},
- connection_states = ConnectionStates0}
+ connection_states = ConnectionStates0,
+ ssl_options = #ssl_options{versions = [HighestVersion|_]}}
= State0, Connection) when is_atom(Type) ->
-
+ %% TLS 1.3 - Section 4.1.3
+ %% Override server random values for TLS 1.3 downgrade protection mechanism.
+ ConnectionStates1 = update_server_random(ConnectionStates0, Version, HighestVersion),
+ State1 = State0#state{connection_states = ConnectionStates1},
ServerHello =
- ssl_handshake:server_hello(SessId, ssl:tls_version(Version), ConnectionStates0, ServerHelloExt),
+ ssl_handshake:server_hello(SessId, ssl:tls_version(Version),
+ ConnectionStates1, ServerHelloExt),
State = server_hello(ServerHello,
- State0#state{expecting_next_protocol_negotiation =
+ State1#state{expecting_next_protocol_negotiation =
NextProtocols =/= undefined}, Connection),
case Type of
new ->
@@ -1530,6 +1535,60 @@ do_server_hello(Type, #hello_extensions{next_protocol_negotiation = NextProtocol
resumed_server_hello(State, Connection)
end.
+update_server_random(#{pending_read := #{security_parameters := ReadSecParams0} =
+ ReadState0,
+ pending_write := #{security_parameters := WriteSecParams0} =
+ WriteState0} = ConnectionStates,
+ Version, HighestVersion) ->
+ ReadRandom = override_server_random(
+ ReadSecParams0#security_parameters.server_random,
+ Version,
+ HighestVersion),
+ WriteRandom = override_server_random(
+ WriteSecParams0#security_parameters.server_random,
+ Version,
+ HighestVersion),
+ ReadSecParams = ReadSecParams0#security_parameters{server_random = ReadRandom},
+ WriteSecParams = WriteSecParams0#security_parameters{server_random = WriteRandom},
+ ReadState = ReadState0#{security_parameters => ReadSecParams},
+ WriteState = WriteState0#{security_parameters => WriteSecParams},
+
+ ConnectionStates#{pending_read => ReadState, pending_write => WriteState}.
+
+%% TLS 1.3 - Section 4.1.3
+%%
+%% If negotiating TLS 1.2, TLS 1.3 servers MUST set the last eight bytes
+%% of their Random value to the bytes:
+%%
+%% 44 4F 57 4E 47 52 44 01
+%%
+%% If negotiating TLS 1.1 or below, TLS 1.3 servers MUST and TLS 1.2
+%% servers SHOULD set the last eight bytes of their Random value to the
+%% bytes:
+%%
+%% 44 4F 57 4E 47 52 44 00
+override_server_random(<<Random0:24/binary,_:8/binary>> = Random, {M,N}, {Major,Minor})
+ when Major > 3 orelse Major =:= 3 andalso Minor >= 4 -> %% TLS 1.3 or above
+ if M =:= 3 andalso N =:= 3 -> %% Negotating TLS 1.2
+ Down = ?RANDOM_OVERRIDE_TLS12,
+ <<Random0/binary,Down/binary>>;
+ M =:= 3 andalso N < 3 -> %% Negotating TLS 1.1 or prior
+ Down = ?RANDOM_OVERRIDE_TLS11,
+ <<Random0/binary,Down/binary>>;
+ true ->
+ Random
+ end;
+override_server_random(<<Random0:24/binary,_:8/binary>> = Random, {M,N}, {Major,Minor})
+ when Major =:= 3 andalso Minor =:= 3 -> %% TLS 1.2
+ if M =:= 3 andalso N < 3 -> %% Negotating TLS 1.1 or prior
+ Down = ?RANDOM_OVERRIDE_TLS11,
+ <<Random0/binary,Down/binary>>;
+ true ->
+ Random
+ end;
+override_server_random(Random, _, _) ->
+ Random.
+
new_server_hello(#server_hello{cipher_suite = CipherSuite,
compression_method = Compression,
session_id = SessionId},
diff --git a/lib/ssl/src/ssl_internal.hrl b/lib/ssl/src/ssl_internal.hrl
index 2e1a928a62..0d3093c1ae 100644
--- a/lib/ssl/src/ssl_internal.hrl
+++ b/lib/ssl/src/ssl_internal.hrl
@@ -90,6 +90,21 @@
-define(ALL_DATAGRAM_SUPPORTED_VERSIONS, ['dtlsv1.2', dtlsv1]).
-define(MIN_DATAGRAM_SUPPORTED_VERSIONS, [dtlsv1]).
+%% TLS 1.3 - Section 4.1.3
+%%
+%% If negotiating TLS 1.2, TLS 1.3 servers MUST set the last eight bytes
+%% of their Random value to the bytes:
+%%
+%% 44 4F 57 4E 47 52 44 01
+%%
+%% If negotiating TLS 1.1 or below, TLS 1.3 servers MUST and TLS 1.2
+%% servers SHOULD set the last eight bytes of their Random value to the
+%% bytes:
+%%
+%% 44 4F 57 4E 47 52 44 00
+-define(RANDOM_OVERRIDE_TLS12, <<16#44,16#4F,16#57,16#4E,16#47,16#52,16#44,16#01>>).
+-define(RANDOM_OVERRIDE_TLS11, <<16#44,16#4F,16#57,16#4E,16#47,16#52,16#44,16#00>>).
+
-define('24H_in_msec', 86400000).
-define('24H_in_sec', 86400).
diff --git a/lib/ssl/src/tls_handshake.erl b/lib/ssl/src/tls_handshake.erl
index 39f0c1680b..7004c7a2f4 100644
--- a/lib/ssl/src/tls_handshake.erl
+++ b/lib/ssl/src/tls_handshake.erl
@@ -106,6 +106,34 @@ client_hello(Host, Port, ConnectionStates,
%% Description: Handles a received hello message
%%--------------------------------------------------------------------
+
+%% TLS 1.3 - Section 4.1.3
+%% TLS 1.3 clients receiving a ServerHello indicating TLS 1.2 or below
+%% MUST check that the last eight bytes are not equal to either of these
+%% values.
+hello(#server_hello{server_version = {Major, Minor},
+ random = <<_:24/binary,Down:8/binary>>},
+ #ssl_options{versions = [{M,N}|_]}, _, _)
+ when (M > 3 orelse M =:= 3 andalso N >= 4) andalso %% TLS 1.3 client
+ (Major =:= 3 andalso Minor =:= 3 andalso %% Negotiating TLS 1.2
+ Down =:= ?RANDOM_OVERRIDE_TLS12) orelse
+
+ (M > 3 orelse M =:= 3 andalso N >= 4) andalso %% TLS 1.3 client
+ (Major =:= 3 andalso Minor < 3 andalso %% Negotiating TLS 1.1 or prior
+ Down =:= ?RANDOM_OVERRIDE_TLS11) ->
+ ?ALERT_REC(?FATAL, ?ILLEGAL_PARAMETER);
+
+%% TLS 1.2 clients SHOULD also check that the last eight bytes are not
+%% equal to the second value if the ServerHello indicates TLS 1.1 or below.
+hello(#server_hello{server_version = {Major, Minor},
+ random = <<_:24/binary,Down:8/binary>>},
+ #ssl_options{versions = [{M,N}|_]}, _, _)
+ when (M =:= 3 andalso N =:= 3) andalso %% TLS 1.2 client
+ (Major =:= 3 andalso Minor < 3 andalso %% Negotiating TLS 1.1 or prior
+ Down =:= ?RANDOM_OVERRIDE_TLS11) ->
+ ?ALERT_REC(?FATAL, ?ILLEGAL_PARAMETER);
+
+
%% TLS 1.3 - 4.2.1. Supported Versions
%% If the "supported_versions" extension in the ServerHello contains a
%% version not offered by the client or contains a version prior to TLS
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-08 17:53:57 +0000