Merge branch 'hans/ssh/diffie-hellman-group-exchange-shaN/OTP-12672' into maint

* hans/ssh/diffie-hellman-group-exchange-shaN/OTP-12672:
  ssh: announce dh-group-exchange
  ssh: document new options in doc/ssh.xml
  ssh: more dh_gex test cases
  ssh: options 'dh_gex_groups' and 'dh_gex_limits'

1 files changed, 44 insertions, 37 deletions

diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index 69ba797faf..38a0b7ec7c 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -67,10 +67,7 @@ default_algorithms(compression) ->
     %% Do not announce '[email protected]' because there seem to be problems
     supported_algorithms(compression, same(['[email protected]']));
 default_algorithms(kex) ->
-    %% Do not announce the experimental 'diffie-hellman-group-exchange-sha*' yet
-    supported_algorithms(kex, ['diffie-hellman-group-exchange-sha1',
-			       'diffie-hellman-group-exchange-sha256'
-			      ]);
+    supported_algorithms(kex, []);
 default_algorithms(Alg) ->
     supported_algorithms(Alg).
 
@@ -404,9 +401,10 @@ handle_kexdh_reply(#ssh_msg_kexdh_reply{public_host_key = HostKey,
 %%% 
 handle_kex_dh_gex_request(#ssh_msg_kex_dh_gex_request{min = Min,
 						      n   = NBits,
-						      max = Max}, Ssh0) when Min=<NBits, NBits=<Max ->
+						      max = Max}, 
+			  Ssh0=#ssh{opts=Opts}) when Min=<NBits, NBits=<Max ->
     %% server
-    {G, P} = dh_gex_group(Min, NBits, Max),
+    {G, P} = dh_gex_group(Min, NBits, Max, proplists:get_value(dh_gex_groups,Opts)),
     {Private, Public} = dh_gen_key(G, P, 1024),
     {SshPacket, Ssh} = 
 	ssh_packet(#ssh_msg_kex_dh_gex_group{p = P, g = G}, Ssh0),
@@ -1220,37 +1218,46 @@ peer_name({Host, _}) ->
 %%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-%%% rfc 2489, ch 6.2
-dh_group1() ->
-    {2, 16#FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF}.
-
-%%% rfc 3526, ch3
-dh_group14() ->
-    {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}.
-
-%%% rfc 3526, ch4
-dh_group15() ->
-   {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}.
-
-%%% rfc 3526, ch5
-dh_group16() ->
-   {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}.
-
-
-dh_group('diffie-hellman-group1-sha1') -> dh_group1();
-dh_group('diffie-hellman-group14-sha1') -> dh_group14().
-    
-
-%%% First try exact match:
-dh_gex_group(_Min, N, _Max) when N==1024 -> dh_group1();
-dh_gex_group(_Min, N, _Max) when N==2048 -> dh_group14();
-dh_gex_group(_Min, N, _Max) when N==3072 -> dh_group15();
-dh_gex_group(_Min, N, _Max) when N==4096 -> dh_group16();
-%%% If not an exact match, select the largest possible:
-dh_gex_group(Min, _N, Max) when Min=<4096, 4096=<Max -> dh_group16();
-dh_gex_group(Min, _N, Max) when Min=<3072, 3072=<Max -> dh_group15();
-dh_gex_group(Min, _N, Max) when Min=<2048, 2048=<Max -> dh_group14();
-dh_gex_group(Min, _N, Max) when Min=<1024, 1024=<Max -> dh_group1().
+dh_group('diffie-hellman-group1-sha1') -> ?dh_group1;
+dh_group('diffie-hellman-group14-sha1') -> ?dh_group14.
+
+dh_gex_default_groups() ->
+    [{1024, ?dh_group1 },
+     {2048, ?dh_group14},
+     {3072, ?dh_group15},
+     {4096, ?dh_group16}].
+
+
+dh_gex_group(Min, N, Max, undefined) ->
+    dh_gex_group(Min, N, Max, dh_gex_default_groups());
+dh_gex_group(Min, N, Max, Groups) ->
+    %% First try to find an exact match. If not an exact match, select the largest possible.
+    {_,Group} =
+	lists:foldl(
+	  fun(_, {I,G}) when I==N ->
+		  %% If we have an exact match already: use that one
+		  {I,G};
+	     ({I,G}, _) when I==N ->
+		  %% If we now found an exact match: use that very one
+		  {I,G};
+	     ({I,G}, {Imax,_Gmax}) when Min=<I,I=<Max, % a) {I,G} fullfills the requirements
+				        I>Imax ->      % b) {I,G} is larger than current max
+		  %% A group within the limits and better than the one we have
+		  {I,G};
+	     (_, IGmax) ->
+		  %% Keep the one we have
+		  IGmax
+	  end, {-1,undefined}, Groups),
+
+    case Group of
+	undefined ->
+	    throw(#ssh_msg_disconnect{
+		     code = ?SSH_DISCONNECT_PROTOCOL_ERROR,
+		     description = "No possible diffie-hellman-group-exchange group found", 
+		     language = ""});
+	_ ->
+	    Group
+    end.
 
 
 dh_gen_key(G, P, _) ->