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authorIngela Anderton Andin <[email protected]>2017-11-07 18:34:34 +0100
committerIngela Anderton Andin <[email protected]>2017-11-09 16:48:30 +0100
commitde3b9cdb8521d7edd524b4e17d1e3f883f832ec0 (patch)
treeec7ca6948bc66a21ab7664fbb072a19d6e3fe2d1
parent19e938e708bb4823d5deac94fd110b7d3896390a (diff)
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ssl: Countermeasurements for Bleichenbacher attack
Back ported for security reasons. Remove DTLS changes as DTLS is not at all working in OTP 18.
-rw-r--r--lib/ssl/src/ssl_connection.erl21
-rw-r--r--lib/ssl/src/ssl_connection.hrl3
-rw-r--r--lib/ssl/src/tls_connection.erl1
3 files changed, 22 insertions, 3 deletions
diff --git a/lib/ssl/src/ssl_connection.erl b/lib/ssl/src/ssl_connection.erl
index 0f0072ba34..4be59501e4 100644
--- a/lib/ssl/src/ssl_connection.erl
+++ b/lib/ssl/src/ssl_connection.erl
@@ -1157,8 +1157,25 @@ server_certify_and_key_exchange(State0, Connection) ->
request_client_cert(State2, Connection).
certify_client_key_exchange(#encrypted_premaster_secret{premaster_secret= EncPMS},
- #state{private_key = Key} = State, Connection) ->
- PremasterSecret = ssl_handshake:premaster_secret(EncPMS, Key),
+ #state{private_key = Key, client_hello_version = {Major, Minor} = Version} = State, Connection) ->
+
+ %% Countermeasure for Bleichenbacher attack always provide some kind of premaster secret
+ %% and fail handshake later.RFC 5246 section 7.4.7.1.
+ PremasterSecret =
+ try ssl_handshake:premaster_secret(EncPMS, Key) of
+ Secret when erlang:byte_size(Secret) == ?NUM_OF_PREMASTERSECRET_BYTES ->
+ case Secret of
+ <<?BYTE(Major), ?BYTE(Minor), _/binary>> -> %% Correct
+ Secret;
+ <<?BYTE(_), ?BYTE(_), Rest/binary>> -> %% Version mismatch
+ <<?BYTE(Major), ?BYTE(Minor), Rest/binary>>
+ end;
+ _ -> %% erlang:byte_size(Secret) =/= ?NUM_OF_PREMASTERSECRET_BYTES
+ make_premaster_secret(Version, rsa)
+ catch
+ #alert{description = ?DECRYPT_ERROR} ->
+ make_premaster_secret(Version, rsa)
+ end,
calculate_master_secret(PremasterSecret, State, Connection, certify, cipher);
certify_client_key_exchange(#client_diffie_hellman_public{dh_public = ClientPublicDhKey},
diff --git a/lib/ssl/src/ssl_connection.hrl b/lib/ssl/src/ssl_connection.hrl
index 9a58f2b8f7..e3abc7d4aa 100644
--- a/lib/ssl/src/ssl_connection.hrl
+++ b/lib/ssl/src/ssl_connection.hrl
@@ -54,7 +54,8 @@
session_cache :: db_handle(),
session_cache_cb :: atom(),
crl_db :: term(),
- negotiated_version :: ssl_record:ssl_version(),
+ negotiated_version :: ssl_record:ssl_version() | 'undefined',
+ client_hello_version :: ssl_record:ssl_version() | 'undefined',
client_certificate_requested = false :: boolean(),
key_algorithm :: ssl_cipher:key_algo(),
hashsign_algorithm = {undefined, undefined},
diff --git a/lib/ssl/src/tls_connection.erl b/lib/ssl/src/tls_connection.erl
index 93716d31b8..5a70cf96dc 100644
--- a/lib/ssl/src/tls_connection.erl
+++ b/lib/ssl/src/tls_connection.erl
@@ -206,6 +206,7 @@ hello(Hello = #client_hello{client_version = ClientVersion,
ssl_connection:hello({common_client_hello, Type, ServerHelloExt},
State#state{connection_states = ConnectionStates,
negotiated_version = Version,
+ client_hello_version = ClientVersion,
hashsign_algorithm = HashSign,
session = Session,
client_ecc = {EllipticCurves, EcPointFormats},