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-rw-r--r--lib/ssl/doc/src/ssl.xml17
-rw-r--r--lib/ssl/src/ssl.erl8
-rw-r--r--lib/ssl/src/ssl_alert.erl4
-rw-r--r--lib/ssl/src/ssl_alert.hrl4
-rw-r--r--lib/ssl/src/ssl_cipher.erl5
-rw-r--r--lib/ssl/src/ssl_cipher.hrl6
-rw-r--r--lib/ssl/src/ssl_internal.hrl3
-rw-r--r--lib/ssl/src/tls_handshake.erl82
-rw-r--r--lib/ssl/src/tls_record.erl9
-rw-r--r--lib/ssl/test/ssl_basic_SUITE.erl39
10 files changed, 138 insertions, 39 deletions
diff --git a/lib/ssl/doc/src/ssl.xml b/lib/ssl/doc/src/ssl.xml
index 249fee5760..0c042f8571 100644
--- a/lib/ssl/doc/src/ssl.xml
+++ b/lib/ssl/doc/src/ssl.xml
@@ -425,6 +425,23 @@ fun(srp, Username :: string(), UserState :: term()) ->
Indication extension will be sent if possible, this option may also be
used to disable that behavior.</p>
</item>
+ <tag>{fallback, boolean()}</tag>
+ <item>
+ <p> Send special cipher suite TLS_FALLBACK_SCSV to avoid undesired TLS version downgrade.
+ Defaults to false</p>
+ <warning><p>Note this option is not needed in normal TLS usage and should not be used
+ to implement new clients. But legacy clients that that retries connections in the following manner</p>
+
+ <p><c> ssl:connect(Host, Port, [...{versions, ['tlsv2', 'tlsv1.1', 'tlsv1', 'sslv3']}])</c></p>
+ <p><c> ssl:connect(Host, Port, [...{versions, [tlsv1.1', 'tlsv1', 'sslv3']}, {fallback, true}])</c></p>
+ <p><c> ssl:connect(Host, Port, [...{versions, ['tlsv1', 'sslv3']}, {fallback, true}]) </c></p>
+ <p><c> ssl:connect(Host, Port, [...{versions, ['sslv3']}, {fallback, true}]) </c></p>
+
+ <p>may use it to avoid undesired TLS version downgrade. Note that TLS_FALLBACK_SCSV must also
+ be supported by the server for the prevention to work.
+ </p></warning>
+ </item>
+
</taglist>
</section>
diff --git a/lib/ssl/src/ssl.erl b/lib/ssl/src/ssl.erl
index 4b7f49547b..5f4ad7f013 100644
--- a/lib/ssl/src/ssl.erl
+++ b/lib/ssl/src/ssl.erl
@@ -657,7 +657,8 @@ handle_options(Opts0) ->
server_name_indication = handle_option(server_name_indication, Opts, undefined),
honor_cipher_order = handle_option(honor_cipher_order, Opts, false),
protocol = proplists:get_value(protocol, Opts, tls),
- padding_check = proplists:get_value(padding_check, Opts, true)
+ padding_check = proplists:get_value(padding_check, Opts, true),
+ fallback = proplists:get_value(fallback, Opts, false)
},
CbInfo = proplists:get_value(cb_info, Opts, {gen_tcp, tcp, tcp_closed, tcp_error}),
@@ -670,7 +671,8 @@ handle_options(Opts0) ->
cb_info, renegotiate_at, secure_renegotiate, hibernate_after,
erl_dist, next_protocols_advertised,
client_preferred_next_protocols, log_alert,
- server_name_indication, honor_cipher_order, padding_check],
+ server_name_indication, honor_cipher_order, padding_check,
+ fallback],
SockOpts = lists:foldl(fun(Key, PropList) ->
proplists:delete(Key, PropList)
@@ -850,6 +852,8 @@ validate_option(honor_cipher_order, Value) when is_boolean(Value) ->
Value;
validate_option(padding_check, Value) when is_boolean(Value) ->
Value;
+validate_option(fallback, Value) when is_boolean(Value) ->
+ Value;
validate_option(Opt, Value) ->
throw({error, {options, {Opt, Value}}}).
diff --git a/lib/ssl/src/ssl_alert.erl b/lib/ssl/src/ssl_alert.erl
index 78dc98bc25..9e372f739a 100644
--- a/lib/ssl/src/ssl_alert.erl
+++ b/lib/ssl/src/ssl_alert.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 2007-2014. All Rights Reserved.
+%% Copyright Ericsson AB 2007-2015. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -161,5 +161,7 @@ description_txt(?BAD_CERTIFICATE_HASH_VALUE) ->
"bad certificate hash value";
description_txt(?UNKNOWN_PSK_IDENTITY) ->
"unknown psk identity";
+description_txt(?INAPPROPRIATE_FALLBACK) ->
+ "inappropriate fallback";
description_txt(Enum) ->
lists:flatten(io_lib:format("unsupported/unknown alert: ~p", [Enum])).
diff --git a/lib/ssl/src/ssl_alert.hrl b/lib/ssl/src/ssl_alert.hrl
index f4f1d74264..a3619e4a35 100644
--- a/lib/ssl/src/ssl_alert.hrl
+++ b/lib/ssl/src/ssl_alert.hrl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 2007-2014. All Rights Reserved.
+%% Copyright Ericsson AB 2007-2015. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -58,6 +58,7 @@
%% protocol_version(70),
%% insufficient_security(71),
%% internal_error(80),
+%% inappropriate_fallback(86),
%% user_canceled(90),
%% no_renegotiation(100),
%% RFC 4366
@@ -93,6 +94,7 @@
-define(PROTOCOL_VERSION, 70).
-define(INSUFFICIENT_SECURITY, 71).
-define(INTERNAL_ERROR, 80).
+-define(INAPPROPRIATE_FALLBACK, 86).
-define(USER_CANCELED, 90).
-define(NO_RENEGOTIATION, 100).
-define(UNSUPPORTED_EXTENSION, 110).
diff --git a/lib/ssl/src/ssl_cipher.erl b/lib/ssl/src/ssl_cipher.erl
index ff9c618a35..bec0055353 100644
--- a/lib/ssl/src/ssl_cipher.erl
+++ b/lib/ssl/src/ssl_cipher.erl
@@ -36,7 +36,7 @@
decipher/6, cipher/5, suite/1, suites/1, all_suites/1,
ec_keyed_suites/0, anonymous_suites/0, psk_suites/1, srp_suites/0,
openssl_suite/1, openssl_suite_name/1, filter/2, filter_suites/1,
- hash_algorithm/1, sign_algorithm/1, is_acceptable_hash/2]).
+ hash_algorithm/1, sign_algorithm/1, is_acceptable_hash/2, is_fallback/1]).
-export_type([cipher_suite/0,
erl_cipher_suite/0, openssl_cipher_suite/0,
@@ -1108,6 +1108,9 @@ is_acceptable_prf(default_prf, _) ->
is_acceptable_prf(Prf, Algos) ->
proplists:get_bool(Prf, Algos).
+is_fallback(CipherSuites)->
+ lists:member(?TLS_FALLBACK_SCSV, CipherSuites).
+
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
diff --git a/lib/ssl/src/ssl_cipher.hrl b/lib/ssl/src/ssl_cipher.hrl
index 3ce9c19aa9..3e50563f0a 100644
--- a/lib/ssl/src/ssl_cipher.hrl
+++ b/lib/ssl/src/ssl_cipher.hrl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 2007-2014. All Rights Reserved.
+%% Copyright Ericsson AB 2007-2015. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -355,6 +355,10 @@
%% hello extension data as they should.
-define(TLS_EMPTY_RENEGOTIATION_INFO_SCSV, <<?BYTE(16#00), ?BYTE(16#FF)>>).
+%% TLS Fallback Signaling Cipher Suite Value (SCSV) for Preventing Protocol
+%% Downgrade Attacks
+-define(TLS_FALLBACK_SCSV, <<?BYTE(16#56), ?BYTE(16#00)>>).
+
%%% PSK Cipher Suites RFC 4279
%% TLS_PSK_WITH_RC4_128_SHA = { 0x00, 0x8A };
diff --git a/lib/ssl/src/ssl_internal.hrl b/lib/ssl/src/ssl_internal.hrl
index bb4e732517..88105cac5a 100644
--- a/lib/ssl/src/ssl_internal.hrl
+++ b/lib/ssl/src/ssl_internal.hrl
@@ -118,7 +118,8 @@
%% Should the server prefer its own cipher order over the one provided by
%% the client?
honor_cipher_order = false,
- padding_check = true
+ padding_check = true,
+ fallback = false
}).
-record(socket_options,
diff --git a/lib/ssl/src/tls_handshake.erl b/lib/ssl/src/tls_handshake.erl
index 183cabcfcd..b0b6d5a8e3 100644
--- a/lib/ssl/src/tls_handshake.erl
+++ b/lib/ssl/src/tls_handshake.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 2007-2014. All Rights Reserved.
+%% Copyright Ericsson AB 2007-2015. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -28,6 +28,7 @@
-include("tls_record.hrl").
-include("ssl_alert.hrl").
-include("ssl_internal.hrl").
+-include("ssl_cipher.hrl").
-include_lib("public_key/include/public_key.hrl").
-export([client_hello/8, hello/4,
@@ -47,22 +48,28 @@
%%--------------------------------------------------------------------
client_hello(Host, Port, ConnectionStates,
#ssl_options{versions = Versions,
- ciphers = UserSuites
+ ciphers = UserSuites,
+ fallback = Fallback
} = SslOpts,
Cache, CacheCb, Renegotiation, OwnCert) ->
Version = tls_record:highest_protocol_version(Versions),
Pending = ssl_record:pending_connection_state(ConnectionStates, read),
SecParams = Pending#connection_state.security_parameters,
- CipherSuites = ssl_handshake:available_suites(UserSuites, Version),
+ AvailableCipherSuites = ssl_handshake:available_suites(UserSuites, Version),
Extensions = ssl_handshake:client_hello_extensions(Host, Version,
- CipherSuites,
+ AvailableCipherSuites,
SslOpts, ConnectionStates, Renegotiation),
-
- Id = ssl_session:client_id({Host, Port, SslOpts}, Cache, CacheCb, OwnCert),
-
+ CipherSuites =
+ case Fallback of
+ true ->
+ [?TLS_FALLBACK_SCSV | ssl_handshake:cipher_suites(AvailableCipherSuites, Renegotiation)];
+ false ->
+ ssl_handshake:cipher_suites(AvailableCipherSuites, Renegotiation)
+ end,
+ Id = ssl_session:client_id({Host, Port, SslOpts}, Cache, CacheCb, OwnCert),
#client_hello{session_id = Id,
client_version = Version,
- cipher_suites = ssl_handshake:cipher_suites(CipherSuites, Renegotiation),
+ cipher_suites = CipherSuites,
compression_methods = ssl_record:compressions(),
random = SecParams#security_parameters.client_random,
extensions = Extensions
@@ -96,33 +103,22 @@ hello(#server_hello{server_version = Version, random = Random,
end;
hello(#client_hello{client_version = ClientVersion,
- session_id = SugesstedId,
- cipher_suites = CipherSuites,
- compression_methods = Compressions,
- random = Random,
- extensions = #hello_extensions{elliptic_curves = Curves} = HelloExt},
+ cipher_suites = CipherSuites} = Hello,
#ssl_options{versions = Versions} = SslOpts,
- {Port, Session0, Cache, CacheCb, ConnectionStates0, Cert}, Renegotiation) ->
+ Info, Renegotiation) ->
Version = ssl_handshake:select_version(tls_record, ClientVersion, Versions),
- case tls_record:is_acceptable_version(Version, Versions) of
- true ->
- ECCCurve = ssl_handshake:select_curve(Curves, ssl_handshake:supported_ecc(Version)),
- {Type, #session{cipher_suite = CipherSuite} = Session1}
- = ssl_handshake:select_session(SugesstedId, CipherSuites, Compressions,
- Port, Session0#session{ecc = ECCCurve}, Version,
- SslOpts, Cache, CacheCb, Cert),
- case CipherSuite of
- no_suite ->
- ?ALERT_REC(?FATAL, ?INSUFFICIENT_SECURITY);
- _ ->
- handle_client_hello_extensions(Version, Type, Random, CipherSuites, HelloExt,
- SslOpts, Session1, ConnectionStates0,
- Renegotiation)
+ case ssl_cipher:is_fallback(CipherSuites) of
+ true ->
+ Highest = tls_record:highest_protocol_version(Versions),
+ case tls_record:is_higher(Highest, Version) of
+ true ->
+ ?ALERT_REC(?FATAL, ?INAPPROPRIATE_FALLBACK);
+ false ->
+ handle_client_hello(Version, Hello, SslOpts, Info, Renegotiation)
end;
false ->
- ?ALERT_REC(?FATAL, ?PROTOCOL_VERSION)
+ handle_client_hello(Version, Hello, SslOpts, Info, Renegotiation)
end.
-
%%--------------------------------------------------------------------
-spec encode_handshake(tls_handshake(), tls_record:tls_version()) -> iolist().
%%
@@ -149,6 +145,32 @@ get_tls_handshake(Version, Data, Buffer) ->
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
+handle_client_hello(Version, #client_hello{session_id = SugesstedId,
+ cipher_suites = CipherSuites,
+ compression_methods = Compressions,
+ random = Random,
+ extensions = #hello_extensions{elliptic_curves = Curves} = HelloExt},
+ #ssl_options{versions = Versions} = SslOpts,
+ {Port, Session0, Cache, CacheCb, ConnectionStates0, Cert}, Renegotiation) ->
+ case tls_record:is_acceptable_version(Version, Versions) of
+ true ->
+ ECCCurve = ssl_handshake:select_curve(Curves, ssl_handshake:supported_ecc(Version)),
+ {Type, #session{cipher_suite = CipherSuite} = Session1}
+ = ssl_handshake:select_session(SugesstedId, CipherSuites, Compressions,
+ Port, Session0#session{ecc = ECCCurve}, Version,
+ SslOpts, Cache, CacheCb, Cert),
+ case CipherSuite of
+ no_suite ->
+ ?ALERT_REC(?FATAL, ?INSUFFICIENT_SECURITY);
+ _ ->
+ handle_client_hello_extensions(Version, Type, Random, CipherSuites, HelloExt,
+ SslOpts, Session1, ConnectionStates0,
+ Renegotiation)
+ end;
+ false ->
+ ?ALERT_REC(?FATAL, ?PROTOCOL_VERSION)
+ end.
+
get_tls_handshake_aux(Version, <<?BYTE(Type), ?UINT24(Length),
Body:Length/binary,Rest/binary>>, Acc) ->
Raw = <<?BYTE(Type), ?UINT24(Length), Body/binary>>,
diff --git a/lib/ssl/src/tls_record.erl b/lib/ssl/src/tls_record.erl
index ed61da2d62..168b2c8fd3 100644
--- a/lib/ssl/src/tls_record.erl
+++ b/lib/ssl/src/tls_record.erl
@@ -41,7 +41,7 @@
%% Protocol version handling
-export([protocol_version/1, lowest_protocol_version/2,
- highest_protocol_version/1, supported_protocol_versions/0,
+ highest_protocol_version/1, is_higher/2, supported_protocol_versions/0,
is_acceptable_version/1, is_acceptable_version/2]).
-export_type([tls_version/0, tls_atom_version/0]).
@@ -236,6 +236,13 @@ highest_protocol_version(Version = {M,_}, [{N,_} | Rest]) when M > N ->
highest_protocol_version(_, [Version | Rest]) ->
highest_protocol_version(Version, Rest).
+is_higher({M, N}, {M, O}) when N > O ->
+ true;
+is_higher({M, _}, {N, _}) when M > N ->
+ true;
+is_higher(_, _) ->
+ false.
+
%%--------------------------------------------------------------------
-spec supported_protocol_versions() -> [tls_version()].
%%
diff --git a/lib/ssl/test/ssl_basic_SUITE.erl b/lib/ssl/test/ssl_basic_SUITE.erl
index 2d4d2452e3..df9432a43b 100644
--- a/lib/ssl/test/ssl_basic_SUITE.erl
+++ b/lib/ssl/test/ssl_basic_SUITE.erl
@@ -90,7 +90,8 @@ basic_tests() ->
version_option,
connect_twice,
connect_dist,
- clear_pem_cache
+ clear_pem_cache,
+ fallback
].
options_tests() ->
@@ -281,6 +282,14 @@ init_per_testcase(empty_protocol_versions, Config) ->
ssl:start(),
Config;
+init_per_testcase(fallback, Config) ->
+ case tls_record:highest_protocol_version([]) of
+ {3, N} when N > 1 ->
+ Config;
+ _ ->
+ {skip, "Not relevant if highest supported version is less than 3.2"}
+ end;
+
%% init_per_testcase(different_ca_peer_sign, Config0) ->
%% ssl_test_lib:make_mix_cert(Config0);
@@ -643,6 +652,34 @@ clear_pem_cache(Config) when is_list(Config) ->
0 = ets:info(FilRefDb, size).
%%--------------------------------------------------------------------
+
+fallback() ->
+ [{doc, "Test TLS_FALLBACK_SCSV downgrade prevention"}].
+
+fallback(Config) when is_list(Config) ->
+ ClientOpts = ?config(client_opts, Config),
+ ServerOpts = ?config(server_opts, Config),
+ {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config),
+
+ Server =
+ ssl_test_lib:start_server_error([{node, ServerNode}, {port, 0},
+ {from, self()},
+ {options, ServerOpts}]),
+
+ Port = ssl_test_lib:inet_port(Server),
+
+ Client =
+ ssl_test_lib:start_client_error([{node, ClientNode},
+ {port, Port}, {host, Hostname},
+ {from, self()}, {options,
+ [{fallback, true},
+ {versions, ['tlsv1']}
+ | ClientOpts]}]),
+
+ ssl_test_lib:check_result(Server, {error,{tls_alert,"inappropriate fallback"}},
+ Client, {error,{tls_alert,"inappropriate fallback"}}).
+
+%%--------------------------------------------------------------------
peername() ->
[{doc,"Test API function peername/1"}].
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-01 02:37:44 +0000