Some protocols (e.g. EAP-PEAP, EAP-TLS, EAP-TTLS) that use TLS as

transport layer need to generate additional application specific
key material. One way to generate such material is to use the TLS
PRF and key material from the TLS session itself.

This change makes it possible to use a TLS sessions PRF either with
the session internal or caller supplied key material to generate
additional key material.

5 files changed, 88 insertions, 5 deletions

diff --git a/lib/ssl/doc/src/ssl.xml b/lib/ssl/doc/src/ssl.xml
index 50268ae206..d9f10a8c4c 100644
--- a/lib/ssl/doc/src/ssl.xml
+++ b/lib/ssl/doc/src/ssl.xml
@@ -122,6 +122,9 @@
    <p> <c>hash() = md5 | sha
     </c></p>
 
+    <p><c>prf_random() =  client_random | server_random
+    </c></p>
+
   </section>
 
   <section>
@@ -561,6 +564,26 @@ fun(OtpCert :: #'OTPCertificate'{}, Event :: {bad_cert, Reason :: atom()} |
     </func>
     
     <func>
+      <name>prf(Socket, Secret, Label, Seed, WantedLength) -> {ok, binary()} | {error, reason()}</name>
+      <fsummary>Use a sessions pseudo random function to generate key material.</fsummary>
+      <type>
+	<v>Socket = sslsocket()</v>
+	<v>Secret = binary() | master_secret</v>
+	<v>Label = binary()</v>
+	<v>Seed = [binary() | prf_random()]</v>
+	<v>WantedLength = non_neg_integer()</v>
+      </type>
+      <desc>
+        <p>Use the pseudo random function (PRF) of a TLS session to generate
+	  additional key material. It either takes user generated values for
+	  <c>Secret</c> and <c>Seed</c> or atoms directing it use a specific
+	  value from the session security parameters.</p>
+        <p>This function can only be used with TLS connections, <c>{error, undefined}</c>
+	  is returned for SSLv3 connections.</p>
+      </desc>
+    </func>
+
+    <func>
       <name>renegotiate(Socket) -> ok | {error, Reason}</name>
       <fsummary> Initiates a new handshake.</fsummary>
       <type>
diff --git a/lib/ssl/src/ssl.erl b/lib/ssl/src/ssl.erl
index d0693445e0..1048583eca 100644
--- a/lib/ssl/src/ssl.erl
+++ b/lib/ssl/src/ssl.erl
@@ -30,7 +30,7 @@
 	 controlling_process/2, listen/2, pid/1, peername/1, peercert/1,
 	 recv/2, recv/3, send/2, getopts/2, setopts/2, sockname/1,
 	 versions/0, session_info/1, format_error/1,
-	 renegotiate/1]).
+	 renegotiate/1, prf/5]).
 
 -deprecated({pid, 1, next_major_release}).
 
@@ -67,7 +67,7 @@
 -type ssl_imp()      :: new | old.
 
 -type transport_option() :: {cb_info, {CallbackModule::atom(), DataTag::atom(), ClosedTag::atom()}}.
-
+-type prf_random() :: client_random | server_random.
 
 %%--------------------------------------------------------------------
 -spec start() -> ok  | {error, reason()}.
@@ -414,6 +414,17 @@ versions() ->
 renegotiate(#sslsocket{pid = Pid, fd = new_ssl}) ->
     ssl_connection:renegotiation(Pid).
 
+%%--------------------------------------------------------------------
+-spec prf(#sslsocket{}, binary() | 'master_secret', binary(),
+	  binary() | prf_random(), non_neg_integer()) ->
+		 {ok, binary()} | {error, reason()}.
+%%
+%% Description: use a ssl sessions TLS PRF to generate key material
+%%--------------------------------------------------------------------
+prf(#sslsocket{pid = Pid, fd = new_ssl},
+    Secret, Label, Seed, WantedLength) ->
+    ssl_connection:prf(Pid, Secret, Label, Seed, WantedLength).
+
 %%---------------------------------------------------------------
 -spec format_error({error, term()}) -> list().
 %%
diff --git a/lib/ssl/src/ssl_connection.erl b/lib/ssl/src/ssl_connection.erl
index 28dd0c85d0..59133dccf0 100644
--- a/lib/ssl/src/ssl_connection.erl
+++ b/lib/ssl/src/ssl_connection.erl
@@ -40,7 +40,8 @@
 -export([send/2, recv/3, connect/7, ssl_accept/6, handshake/2,
 	 socket_control/3, close/1, shutdown/2,
 	 new_user/2, get_opts/2, set_opts/2, info/1, session_info/1, 
-	 peer_certificate/1, sockname/1, peername/1, renegotiation/1]).
+	 peer_certificate/1, sockname/1, peername/1, renegotiation/1,
+	 prf/5]).
 
 %% Called by ssl_connection_sup
 -export([start_link/7]). 
@@ -273,6 +274,16 @@ peer_certificate(ConnectionPid) ->
 renegotiation(ConnectionPid) ->
     sync_send_all_state_event(ConnectionPid, renegotiate). 
 
+%%--------------------------------------------------------------------
+-spec prf(pid(), binary() | 'master_secret', binary(),
+	  binary() | ssl:prf_secret(), non_neg_integer()) ->
+		 {ok, binary()} | {error, reason()} | {'EXIT', term()}.
+%%
+%% Description: use a ssl sessions TLS PRF to generate key material
+%%--------------------------------------------------------------------
+prf(ConnectionPid, Secret, Label, Seed, WantedLength) ->
+    sync_send_all_state_event(ConnectionPid, {prf, Secret, Label, Seed, WantedLength}).
+
 %%====================================================================
 %% ssl_connection_sup API
 %%====================================================================
@@ -868,6 +879,32 @@ handle_sync_event(renegotiate, From, connection, State) ->
 handle_sync_event(renegotiate, _, StateName, State) ->
     {reply, {error, already_renegotiating}, StateName, State, get_timeout(State)};
 
+handle_sync_event({prf, Secret, Label, Seed, WantedLength}, _, StateName,
+		  #state{connection_states = ConnectionStates,
+			 negotiated_version = Version} = State) ->
+    ConnectionState =
+	ssl_record:current_connection_state(ConnectionStates, read),
+    SecParams = ConnectionState#connection_state.security_parameters,
+    #security_parameters{master_secret = MasterSecret,
+			 client_random = ClientRandom,
+			 server_random = ServerRandom} = SecParams,
+    Reply = try
+		SecretToUse = case Secret of
+				  _ when is_binary(Secret) -> Secret;
+				  master_secret -> MasterSecret
+			      end,
+		SeedToUse = lists:reverse(
+			      lists:foldl(fun(X, Acc) when is_binary(X) -> [X|Acc];
+					     (client_random, Acc) -> [ClientRandom|Acc];
+					     (server_random, Acc) -> [ServerRandom|Acc]
+					  end, [], Seed)),
+		ssl_handshake:prf(Version, SecretToUse, Label, SeedToUse, WantedLength)
+	    catch
+		exit:_ -> {error, badarg};
+		error:Reason -> {error, Reason}
+	    end,
+    {reply, Reply, StateName, State, get_timeout(State)};
+
 handle_sync_event(info, _, StateName, 
 		  #state{negotiated_version = Version,
 			 session = #session{cipher_suite = Suite}} = State) ->
diff --git a/lib/ssl/src/ssl_handshake.erl b/lib/ssl/src/ssl_handshake.erl
index 542033e6ce..ef60cac6df 100644
--- a/lib/ssl/src/ssl_handshake.erl
+++ b/lib/ssl/src/ssl_handshake.erl
@@ -37,7 +37,7 @@
 	 finished/4, verify_connection/5, get_tls_handshake/2,
 	 decode_client_key/3, server_hello_done/0,
 	 encode_handshake/2, init_hashes/0, update_hashes/2,
-	 decrypt_premaster_secret/2]).
+	 decrypt_premaster_secret/2, prf/5]).
 
 -export([dec_hello_extensions/2]).
 
@@ -543,6 +543,18 @@ server_key_exchange_hash(dhe_dss, Value) ->
     crypto:sha(Value).
 
 %%--------------------------------------------------------------------
+-spec prf(tls_version(), binary(), binary(), binary(), non_neg_integer()) ->
+		 {ok, binary()} | {error, undefined}.
+%%
+%% Description: use the TLS PRF to generate key material
+%%--------------------------------------------------------------------
+prf({3,0}, _, _, _, _) ->
+    {error, undefined};
+prf({3,N}, Secret, Label, Seed, WantedLength)
+  when N == 1; N == 2 ->
+    {ok, ssl_tls1:prf(Secret, Label, Seed, WantedLength)}.
+
+%%--------------------------------------------------------------------
 %%% Internal functions
 %%--------------------------------------------------------------------
 get_tls_handshake_aux(<<?BYTE(Type), ?UINT24(Length), 
diff --git a/lib/ssl/src/ssl_tls1.erl b/lib/ssl/src/ssl_tls1.erl
index 5f9850c386..7351f34b61 100644
--- a/lib/ssl/src/ssl_tls1.erl
+++ b/lib/ssl/src/ssl_tls1.erl
@@ -29,7 +29,7 @@
 -include("ssl_record.hrl"). 			
 
 -export([master_secret/3, finished/3, certificate_verify/2, mac_hash/7, 
-	 setup_keys/6, suites/0]).
+	 setup_keys/6, suites/0, prf/4]).
 
 %%====================================================================
 %% Internal application API