From df0c5663dd944a3dd06936105d0696a704c20e4e Mon Sep 17 00:00:00 2001 From: Kenneth Lakin Date: Sat, 30 Apr 2016 02:31:51 -0700 Subject: ssl: Add BEAST mitigation selection option Some legacy TLS 1.0 software does not tolerate the 1/n-1 content split BEAST mitigation technique. This commit adds a beast_mitigation SSL option (defaulting to one_n_minus_one) to select or disable the BEAST mitigation technique. Valid option values are (one_n_minus_one | zero_n | disabled). --- lib/ssl/src/ssl_record.erl | 43 ++++++++++++++++++++++++++++--------------- 1 file changed, 28 insertions(+), 15 deletions(-) (limited to 'lib/ssl/src/ssl_record.erl') diff --git a/lib/ssl/src/ssl_record.erl b/lib/ssl/src/ssl_record.erl index 866bfcef7e..0a086f5eeb 100644 --- a/lib/ssl/src/ssl_record.erl +++ b/lib/ssl/src/ssl_record.erl @@ -30,7 +30,7 @@ -include("ssl_alert.hrl"). %% Connection state handling --export([init_connection_states/1, +-export([init_connection_states/2, current_connection_state/2, pending_connection_state/2, activate_pending_connection_state/2, set_security_params/3, @@ -62,15 +62,16 @@ %%==================================================================== %%-------------------------------------------------------------------- --spec init_connection_states(client | server) -> #connection_states{}. +-spec init_connection_states(client | server, one_n_minus_one | zero_n | disabled ) -> + #connection_states{}. %% %% Description: Creates a connection_states record with appropriate %% values for the initial SSL connection setup. %%-------------------------------------------------------------------- -init_connection_states(Role) -> +init_connection_states(Role, BeastMitigation) -> ConnectionEnd = record_protocol_role(Role), - Current = initial_connection_state(ConnectionEnd), - Pending = empty_connection_state(ConnectionEnd), + Current = initial_connection_state(ConnectionEnd, BeastMitigation), + Pending = empty_connection_state(ConnectionEnd, BeastMitigation), #connection_states{current_read = Current, pending_read = Pending, current_write = Current, @@ -119,9 +120,10 @@ activate_pending_connection_state(States = read) -> NewCurrent = Pending#connection_state{epoch = dtls_next_epoch(Current), sequence_number = 0}, + BeastMitigation = Pending#connection_state.beast_mitigation, SecParams = Pending#connection_state.security_parameters, ConnectionEnd = SecParams#security_parameters.connection_end, - EmptyPending = empty_connection_state(ConnectionEnd), + EmptyPending = empty_connection_state(ConnectionEnd, BeastMitigation), SecureRenegotation = NewCurrent#connection_state.secure_renegotiation, NewPending = EmptyPending#connection_state{secure_renegotiation = SecureRenegotation}, States#connection_states{current_read = NewCurrent, @@ -134,9 +136,10 @@ activate_pending_connection_state(States = write) -> NewCurrent = Pending#connection_state{epoch = dtls_next_epoch(Current), sequence_number = 0}, + BeastMitigation = Pending#connection_state.beast_mitigation, SecParams = Pending#connection_state.security_parameters, ConnectionEnd = SecParams#security_parameters.connection_end, - EmptyPending = empty_connection_state(ConnectionEnd), + EmptyPending = empty_connection_state(ConnectionEnd, BeastMitigation), SecureRenegotation = NewCurrent#connection_state.secure_renegotiation, NewPending = EmptyPending#connection_state{secure_renegotiation = SecureRenegotation}, States#connection_states{current_write = NewCurrent, @@ -314,12 +317,13 @@ set_pending_cipher_state(#connection_states{pending_read = Read, encode_handshake(Frag, Version, #connection_states{current_write = #connection_state{ + beast_mitigation = BeastMitigation, security_parameters = #security_parameters{bulk_cipher_algorithm = BCA}}} = ConnectionStates) -> case iolist_size(Frag) of N when N > ?MAX_PLAIN_TEXT_LENGTH -> - Data = split_bin(iolist_to_binary(Frag), ?MAX_PLAIN_TEXT_LENGTH, Version, BCA), + Data = split_bin(iolist_to_binary(Frag), ?MAX_PLAIN_TEXT_LENGTH, Version, BCA, BeastMitigation), encode_iolist(?HANDSHAKE, Data, Version, ConnectionStates); _ -> encode_plain_text(?HANDSHAKE, Version, Frag, ConnectionStates) @@ -352,10 +356,11 @@ encode_change_cipher_spec(Version, ConnectionStates) -> %%-------------------------------------------------------------------- encode_data(Frag, Version, #connection_states{current_write = #connection_state{ + beast_mitigation = BeastMitigation, security_parameters = #security_parameters{bulk_cipher_algorithm = BCA}}} = ConnectionStates) -> - Data = split_bin(Frag, ?MAX_PLAIN_TEXT_LENGTH, Version, BCA), + Data = split_bin(Frag, ?MAX_PLAIN_TEXT_LENGTH, Version, BCA, BeastMitigation), encode_iolist(?APPLICATION_DATA, Data, Version, ConnectionStates). uncompress(?NULL, Data, CS) -> @@ -447,9 +452,10 @@ decipher_aead(Version, CipherFragment, %%-------------------------------------------------------------------- %%% Internal functions %%-------------------------------------------------------------------- -empty_connection_state(ConnectionEnd) -> +empty_connection_state(ConnectionEnd, BeastMitigation) -> SecParams = empty_security_params(ConnectionEnd), - #connection_state{security_parameters = SecParams}. + #connection_state{security_parameters = SecParams, + beast_mitigation = BeastMitigation}. empty_security_params(ConnectionEnd = ?CLIENT) -> #security_parameters{connection_end = ConnectionEnd, @@ -478,10 +484,11 @@ record_protocol_role(client) -> record_protocol_role(server) -> ?SERVER. -initial_connection_state(ConnectionEnd) -> +initial_connection_state(ConnectionEnd, BeastMitigation) -> #connection_state{security_parameters = initial_security_params(ConnectionEnd), - sequence_number = 0 + sequence_number = 0, + beast_mitigation = BeastMitigation }. initial_security_params(ConnectionEnd) -> @@ -506,11 +513,17 @@ encode_iolist(Type, Data, Version, ConnectionStates0) -> %% 1/n-1 splitting countermeasure Rizzo/Duong-Beast, RC4 chiphers are %% not vulnerable to this attack. -split_bin(<>, ChunkSize, Version, BCA) when +split_bin(<>, ChunkSize, Version, BCA, one_n_minus_one) when BCA =/= ?RC4 andalso ({3, 1} == Version orelse {3, 0} == Version) -> do_split_bin(Rest, ChunkSize, [[FirstByte]]); -split_bin(Bin, ChunkSize, _, _) -> +%% 0/n splitting countermeasure for clients that are incompatible with 1/n-1 +%% splitting. +split_bin(Bin, ChunkSize, Version, BCA, zero_n) when + BCA =/= ?RC4 andalso ({3, 1} == Version orelse + {3, 0} == Version) -> + do_split_bin(Bin, ChunkSize, [[<<>>]]); +split_bin(Bin, ChunkSize, _, _, _) -> do_split_bin(Bin, ChunkSize, []). do_split_bin(<<>>, _, Acc) -> -- cgit v1.2.3