From b138f9e6879e44732e681d368704345acdf26b1b Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Thu, 29 Sep 2011 09:08:31 +0200 Subject: Add tls support to capabilities exchange To upgrade a connection to TLS or not, that is the question. It is possible for us to send a CER offering both NO_INBAND_SECURITY and TLS and for the peer to answer likewise: RFC 3588 doesn't make clear that a CEA should be unambiguous about the choice of security. Thus, if TLS is offered then assume the server is prepared to for a handshake. Similarly, when receiving a CER, choose TLS if it's offered and be unambiguous about our choice in CEA. There is no ssl:maybe_accept that would let us receive a handshake if it comes or another message if it doesn't. The choice of TLS should probably be made into a callback so that an application can decide based on the peer's Origin-Realm for example. Such a callback could also be used to reject a CER/CEA. Handle Inband-Security-Id values other than NO_INBAND_SECURITY and TLS by assuming that they require no intervention by the transport module, treating them like NO_INBAND_SECURITY. Whether or not this is reasonable (or useful) is unclear. There may be a need for more sychronization than we have on offer. (Having to do something before taking the connection up for example.) Note that diameter_peer_fsm must be upgraded before diameter_capx because of the new return value from diameter_capx:recv_CEA/2. --- lib/diameter/src/app/diameter_capx.erl | 145 ++++++++++++++++++--------------- 1 file changed, 81 insertions(+), 64 deletions(-) (limited to 'lib/diameter/src/app/diameter_capx.erl') diff --git a/lib/diameter/src/app/diameter_capx.erl b/lib/diameter/src/app/diameter_capx.erl index aa5318e79d..138e76411e 100644 --- a/lib/diameter/src/app/diameter_capx.erl +++ b/lib/diameter/src/app/diameter_capx.erl @@ -62,6 +62,7 @@ -define(NOSECURITY, ?'DIAMETER_BASE_RESULT-CODE_DIAMETER_NO_COMMON_SECURITY'). -define(NO_INBAND_SECURITY, 0). +-define(TLS, 1). %% =========================================================================== @@ -80,7 +81,7 @@ recv_CER(CER, Svc) -> try_it([fun rCER/2, CER, Svc]). -spec recv_CEA(#diameter_base_CEA{}, #diameter_service{}) - -> tried({['Unsigned32'()], #diameter_caps{}}). + -> tried({['Unsigned32'()], ['Unsigned32'()], #diameter_caps{}}). recv_CEA(CEA, Svc) -> try_it([fun rCEA/2, CEA, Svc]). @@ -126,10 +127,11 @@ mk_caps(Caps0, Opts) -> set_cap({Key, _}, _) -> ?THROW({duplicate, Key}). -cap(K, V) when K == 'Origin-Host'; - K == 'Origin-Realm'; - K == 'Vendor-Id'; - K == 'Product-Name' -> +cap(K, V) + when K == 'Origin-Host'; + K == 'Origin-Realm'; + K == 'Vendor-Id'; + K == 'Product-Name' -> V; cap('Host-IP-Address', Vs) @@ -139,11 +141,8 @@ cap('Host-IP-Address', Vs) cap('Firmware-Revision', V) -> [V]; -%% Not documented but accept it as long as it's what we support. -cap('Inband-Security-Id', [0] = Vs) -> %% NO_INBAND_SECURITY - Vs; - -cap(K, Vs) when K /= 'Inband-Security-Id', is_list(Vs) -> +cap(_, Vs) + when is_list(Vs) -> Vs; cap(K, V) -> @@ -161,28 +160,10 @@ ipaddr(A) -> %% %% Build a CER record to send to a remote peer. -bCER(#diameter_caps{origin_host = Host, - origin_realm = Realm, - host_ip_address = Addrs, - vendor_id = Vid, - product_name = Name, - origin_state_id = OSI, - supported_vendor_id = SVid, - auth_application_id = AuId, - acct_application_id = AcId, - vendor_specific_application_id = VSA, - firmware_revision = Rev}) -> - #diameter_base_CER{'Origin-Host' = Host, - 'Origin-Realm' = Realm, - 'Host-IP-Address' = Addrs, - 'Vendor-Id' = Vid, - 'Product-Name' = Name, - 'Origin-State-Id' = OSI, - 'Supported-Vendor-Id' = SVid, - 'Auth-Application-Id' = AuId, - 'Acct-Application-Id' = AcId, - 'Vendor-Specific-Application-Id' = VSA, - 'Firmware-Revision' = Rev}. +%% Use the fact that diameter_caps has the same field names as CER. +bCER(#diameter_caps{} = Rec) -> + #diameter_base_CER{} + = list_to_tuple([diameter_base_CER | tl(tuple_to_list(Rec))]). %% rCER/2 %% @@ -219,19 +200,16 @@ bCER(#diameter_caps{origin_host = Host, %% That is, each side sends all of its capabilities and is responsible for %% not sending commands that the peer doesn't support. -%% TODO: Make it an option to send only common applications in CEA to -%% allow backwards compatibility, and also because there are likely -%% servers that expect this. Or maybe a callback. - %% 6.10. Inband-Security-Id AVP %% %% NO_INBAND_SECURITY 0 %% This peer does not support TLS. This is the default value, if the %% AVP is omitted. +%% +%% TLS 1 +%% This node supports TLS security, as defined by [TLS]. rCER(CER, #diameter_service{capabilities = LCaps} = Svc) -> - #diameter_base_CER{'Inband-Security-Id' = RIS} - = CER, #diameter_base_CEA{} = CEA = cea_from_cer(bCER(LCaps)), @@ -241,56 +219,95 @@ rCER(CER, #diameter_service{capabilities = LCaps} = Svc) -> {SApps, RCaps, - build_CEA([] == SApps, - RIS, - lists:member(?NO_INBAND_SECURITY, RIS), - CEA#diameter_base_CEA{'Result-Code' = ?SUCCESS, - 'Inband-Security-Id' = []})}. + build_CEA(SApps, + LCaps, + RCaps, + CEA#diameter_base_CEA{'Result-Code' = ?SUCCESS})}. -%% TODO: 5.3 of RFC3588 says we MUST return DIAMETER_NO_COMMON_APPLICATION +%% TODO: 5.3 of RFC 3588 says we MUST return DIAMETER_NO_COMMON_APPLICATION %% in the CEA and SHOULD disconnect the transport. However, we have %% no way to guarantee the send before disconnecting. -build_CEA(true, _, _, CEA) -> +build_CEA([], _, _, CEA) -> CEA#diameter_base_CEA{'Result-Code' = ?NOAPP}; -build_CEA(false, [_|_], false, CEA) -> - CEA#diameter_base_CEA{'Result-Code' = ?NOSECURITY}; -build_CEA(false, [_|_], true, CEA) -> - CEA#diameter_base_CEA{'Inband-Security-Id' = [?NO_INBAND_SECURITY]}; -build_CEA(false, [], false, CEA) -> - CEA. + +build_CEA(_, LCaps, RCaps, CEA) -> + case common_security(LCaps, RCaps) of + [] -> + CEA#diameter_base_CEA{'Result-Code' = ?NOSECURITY}; + [_] = IS -> + CEA#diameter_base_CEA{'Inband-Security-Id' = IS} + end. + +%% common_security/2 + +common_security(#diameter_caps{inband_security_id = LS}, + #diameter_caps{inband_security_id = RS}) -> + cs(LS, RS). + +%% Unspecified is equivalent to NO_INBAND_SECURITY. +cs([], RS) -> + cs([?NO_INBAND_SECURITY], RS); +cs(LS, []) -> + cs(LS, [?NO_INBAND_SECURITY]); + +%% Agree on TLS if both parties support it. When sending CEA, this is +%% to ensure the peer is clear that we will be expecting a TLS +%% handshake since there is no ssl:maybe_accept that would allow the +%% peer to choose between TLS or not upon reception of our CEA. When +%% receiving CEA it deals with a server that isn't explicit about its choice. +%% TODO: Make the choice configurable. +cs(LS, RS) -> + Is = ordsets:to_list(ordsets:intersection(ordsets:from_list(LS), + ordsets:from_list(RS))), + case lists:member(?TLS, Is) of + true -> + [?TLS]; + false when [] == Is -> + Is; + false -> + [hd(Is)] %% probably NO_INBAND_SECURITY + end. +%% The only two values defined by RFC 3588 are NO_INBAND_SECURITY and +%% TLS but don't enforce this. In theory this allows some other +%% security mechanism we don't have to know about, although in +%% practice something there may be a need for more synchronization +%% than notification by way of an event subscription offers. %% cea_from_cer/1 +%% CER is a subset of CEA, the latter adding Result-Code and a few +%% more AVP's. cea_from_cer(#diameter_base_CER{} = CER) -> lists:foldl(fun(F,A) -> to_cea(CER, F, A) end, #diameter_base_CEA{}, record_info(fields, diameter_base_CER)). to_cea(CER, Field, CEA) -> - try ?BASE:'#info-'(diameter_base_CEA, {index, Field}) of - N -> - setelement(N, CEA, ?BASE:'#get-'(Field, CER)) + try ?BASE:'#get-'(Field, CER) of + V -> ?BASE:'#set-'({Field, V}, CEA) catch - error: _ -> - CEA + error: _ -> CEA end. - + %% rCEA/2 -rCEA(CEA, #diameter_service{capabilities = LCaps} = Svc) - when is_record(CEA, diameter_base_CEA) -> - #diameter_base_CEA{'Result-Code' = RC} - = CEA, - +rCEA(#diameter_base_CEA{'Result-Code' = RC} + = CEA, + #diameter_service{capabilities = LCaps} + = Svc) -> RC == ?SUCCESS orelse ?THROW({'Result-Code', RC}), RCaps = capx_to_caps(CEA), SApps = common_applications(LCaps, RCaps, Svc), - [] == SApps andalso ?THROW({no_common_apps, LCaps, RCaps}), + [] == SApps andalso ?THROW(no_common_applications), + + IS = common_security(LCaps, RCaps), + + [] == IS andalso ?THROW(no_common_security), - {SApps, RCaps}; + {SApps, IS, RCaps}; rCEA(CEA, _Svc) -> ?THROW({invalid, CEA}). -- cgit v1.2.3