%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2007-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
-module(tls_record_1_3).
-include("tls_record.hrl").
-include("tls_record_1_3.hrl").
-include("ssl_internal.hrl").
-include("ssl_alert.hrl").
-include("ssl_cipher.hrl").
%% Encoding
-export([encode_handshake/2, encode_alert_record/2,
encode_data/2]).
-export([encode_plain_text/3]).
%% Decoding
-export([decode_cipher_text/2]).
%%====================================================================
%% Encoding
%%====================================================================
%%--------------------------------------------------------------------
-spec encode_handshake(iolist(), ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%
%% Description: Encodes a handshake message to send on the tls-1.3-socket.
%%--------------------------------------------------------------------
encode_handshake(Frag, ConnectionStates) ->
case iolist_size(Frag) of
N when N > ?MAX_PLAIN_TEXT_LENGTH ->
%% TODO: Consider padding here
Data = split_bin(iolist_to_binary(Frag), ?MAX_PLAIN_TEXT_LENGTH),
encode_iolist(?HANDSHAKE, Data, ConnectionStates);
_ ->
encode_plain_text(?HANDSHAKE, Frag, ConnectionStates)
end.
%%--------------------------------------------------------------------
-spec encode_alert_record(#alert{}, ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%%
%% Description: Encodes an alert message to send on the ssl-socket.
%%--------------------------------------------------------------------
encode_alert_record(#alert{level = Level, description = Description},
ConnectionStates) ->
encode_plain_text(?ALERT, <<?BYTE(Level), ?BYTE(Description)>>,
ConnectionStates).
%%--------------------------------------------------------------------
-spec encode_data(binary(), ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%%
%% Description: Encodes data to send on the ssl-socket.
%%--------------------------------------------------------------------
encode_data(Frag, ConnectionStates) ->
Data = split_bin(Frag, ?MAX_PLAIN_TEXT_LENGTH, {3,4}),
encode_iolist(?APPLICATION_DATA, Data, ConnectionStates).
encode_plain_text(Type, Data0, #{current_write := Write0} = ConnectionStates) ->
PadLen = 0, %% TODO where to specify PadLen?
Data = inner_plaintext(Type, Data0, PadLen),
{CipherFragment, Write1} = encode_plain_text(Data, Write0),
{CipherText, Write} = encode_tls_cipher_text(CipherFragment, Write1),
{CipherText, ConnectionStates#{current_write => Write}}.
encode_iolist(Type, Data, ConnectionStates0) ->
{ConnectionStates, EncodedMsg} =
lists:foldl(fun(Text, {CS0, Encoded}) ->
{Enc, CS1} =
encode_plain_text(Type, Text, CS0),
{CS1, [Enc | Encoded]}
end, {ConnectionStates0, []}, Data),
{lists:reverse(EncodedMsg), ConnectionStates}.
%%====================================================================
%% Decoding
%%====================================================================
%%--------------------------------------------------------------------
-spec decode_cipher_text(#ssl_tls{}, ssl_record:connection_states()) ->
{#ssl_tls{}, ssl_record:connection_states()}| #alert{}.
%%
%% Description: Decode cipher text, use legacy type ssl_tls instead of tls_cipher_text
%% in decoding context so that we can reuse the code from erlier versions.
%%--------------------------------------------------------------------
decode_cipher_text(#ssl_tls{type = ?OPAQUE_TYPE,
version = ?LEGACY_VERSION,
fragment = CipherFragment},
#{current_read :=
#{sequence_number := Seq,
cipher_state := CipherS0,
security_parameters :=
#security_parameters{
cipher_type = ?AEAD,
bulk_cipher_algorithm =
BulkCipherAlgo}
} = ReadState0} = ConnectionStates0) ->
AAD = start_additional_data(),
CipherS1 = ssl_cipher:nonce_seed(<<?UINT64(Seq)>>, CipherS0),
case decipher_aead(BulkCipherAlgo, CipherS1, AAD, CipherFragment) of
{PlainFragment, CipherS1} ->
ConnectionStates =
ConnectionStates0#{current_read =>
ReadState0#{cipher_state => CipherS1,
sequence_number => Seq + 1}},
decode_inner_plaintext(PlainFragment, ConnectionStates);
#alert{} = Alert ->
Alert
end;
decode_cipher_text(#ssl_tls{type = Type,
version = ?LEGACY_VERSION,
fragment = CipherFragment},
#{current_read :=
#{security_parameters :=
#security_parameters{
cipher_suite = ?TLS_NULL_WITH_NULL_NULL}
}} = ConnnectionStates0) ->
{#ssl_tls{type = Type,
version = {3,4}, %% Internally use real version
fragment = CipherFragment}, ConnnectionStates0};
decode_cipher_text(#ssl_tls{type = Type}, _) ->
%% Version mismatch is already asserted
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, {record_typ_mismatch, Type}).
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
split_bin(Bin, ChunkSize) ->
split_bin(Bin, ChunkSize, []).
split_bin(Bin, ChunkSize, _) ->
do_split_bin(Bin, ChunkSize, []).
do_split_bin(<<>>, _, Acc) ->
lists:reverse(Acc);
do_split_bin(Bin, ChunkSize, Acc) ->
case Bin of
<<Chunk:ChunkSize/binary, Rest/binary>> ->
do_split_bin(Rest, ChunkSize, [Chunk | Acc]);
_ ->
lists:reverse(Acc, [Bin])
end.
inner_plaintext(Type, Data, Length) ->
#inner_plaintext{
content = Data,
type = Type,
zeros = zero_padding(Length)
}.
zero_padding(Length)->
binary:copy(<<?BYTE(0)>>, Length).
encode_plain_text(#inner_plaintext{
content = Data,
type = Type,
zeros = Zeros
}, #{cipher_state := CipherS0,
sequence_number := Seq,
security_parameters :=
#security_parameters{
cipher_type = ?AEAD}
} = WriteState0) ->
PlainText = <<Data/binary, ?BYTE(Type), Zeros/binary>>,
AAD = start_additional_data(),
CipherS1 = ssl_cipher:nonce_seed(<<?UINT64(Seq)>>, CipherS0),
{Encoded, WriteState} = cipher_aead(PlainText, WriteState0#{cipher_state => CipherS1}, AAD),
{#tls_cipher_text{opaque_type = Type,
legacy_version = {3,3},
encoded_record = Encoded}, WriteState};
encode_plain_text(#inner_plaintext{
content = Data,
type = Type
}, #{security_parameters :=
#security_parameters{
cipher_suite = ?TLS_NULL_WITH_NULL_NULL}
} = WriteState0) ->
%% RFC8446 - 5.1. Record Layer
%% When record protection has not yet been engaged, TLSPlaintext
%% structures are written directly onto the wire.
{#tls_cipher_text{opaque_type = Type,
legacy_version = {3,3},
encoded_record = Data}, WriteState0};
encode_plain_text(_, CS) ->
exit({cs, CS}).
start_additional_data() ->
{MajVer, MinVer} = ?LEGACY_VERSION,
<<?BYTE(?OPAQUE_TYPE), ?BYTE(MajVer), ?BYTE(MinVer)>>.
end_additional_data(AAD, Len) ->
<<AAD/binary, ?UINT16(Len)>>.
nonce(#cipher_state{nonce = Nonce, iv = IV}) ->
Len = size(IV),
crypto:exor(<<Nonce:Len/bytes>>, IV).
cipher_aead(Fragment,
#{cipher_state := CipherS0,
security_parameters :=
#security_parameters{bulk_cipher_algorithm =
BulkCipherAlgo}
} = WriteState0, AAD) ->
{CipherFragment, CipherS1} =
cipher_aead(BulkCipherAlgo, CipherS0, AAD, Fragment),
{CipherFragment, WriteState0#{cipher_state => CipherS1}}.
cipher_aead(Type, #cipher_state{key=Key} = CipherState, AAD0, Fragment) ->
AAD = end_additional_data(AAD0, erlang:iolist_size(Fragment)),
Nonce = nonce(CipherState),
{Content, CipherTag} = ssl_cipher:aead_encrypt(Type, Key, Nonce, Fragment, AAD),
{<<Content/binary, CipherTag/binary>>, CipherState}.
encode_tls_cipher_text(#tls_cipher_text{opaque_type = Type,
legacy_version = {MajVer, MinVer},
encoded_record = Encoded}, #{sequence_number := Seq} = Write) ->
Length = erlang:iolist_size(Encoded),
{[<<?BYTE(Type), ?BYTE(MajVer), ?BYTE(MinVer), ?UINT16(Length)>>, Encoded],
Write#{sequence_number => Seq +1}}.
decipher_aead(Type, #cipher_state{key = Key} = CipherState, AAD0, CipherFragment) ->
try
Nonce = nonce(CipherState),
{AAD, CipherText, CipherTag} = aead_ciphertext_split(CipherState, CipherFragment, AAD0),
case ssl_cipher:aead_decrypt(Type, Key, Nonce, CipherText, CipherTag, AAD) of
Content when is_binary(Content) ->
{Content, CipherState};
_ ->
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, decryption_failed)
end
catch
_:_ ->
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, decryption_failed)
end.
aead_ciphertext_split(#cipher_state{tag_len = Len}, CipherTextFragment, AAD) ->
CipherLen = size(CipherTextFragment) - Len,
<<CipherText:CipherLen/bytes, CipherTag:Len/bytes>> = CipherTextFragment,
{end_additional_data(AAD, CipherLen), CipherText, CipherTag}.
decode_inner_plaintext(PlainText, ConnnectionStates) ->
case remove_padding(PlainText) of
#alert{} = Alert ->
Alert;
{Data, Type} ->
{#ssl_tls{type = Type,
version = {3,4}, %% Internally use real version
fragment = Data}, ConnnectionStates}
end.
remove_padding(PlainText)->
case binary:split(PlainText, <<0>>, [global, trim]) of
[] ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE, padding_error);
[Content] ->
Type = binary:last(Content),
split_content(Type, Content, erlang:byte_size(Content) - 1)
end.
split_content(?HANDSHAKE, _, 0) ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE, empty_handshake);
split_content(?ALERT, _, 0) ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE, empty_alert);
%% For special middlebox compatible case!
split_content(?CHANGE_CIPHER_SPEC, _, 0) ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE, empty_change_cipher_spec);
split_content(?APPLICATION_DATA = Type, _, 0) ->
{Type, <<>>};
split_content(Type, Content, N) ->
<<Data:N/bytes, ?BYTE(Type)>> = Content,
{Type, Data}.
