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'

6 files changed, 184 insertions, 46 deletions

diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index d24025ca4d..cf5e8f1aff 100644
--- a/lib/ssh/doc/src/ssh.xml
+++ b/lib/ssh/doc/src/ssh.xml
@@ -43,7 +43,7 @@
       <item>Supported public key algorithms: ssh-rsa and ssh-dss.</item>
       <item>Supported MAC algorithms: hmac-sha2-256 and hmac-sha1.</item>
       <item>Supported encryption algorithms: aes128-ctr, aes128-cb and 3des-cbc.</item>
-      <item>Supported key exchange algorithms: diffie-hellman-group1-sha1.</item>
+      <item>Supported key exchange algorithms: diffie-hellman-group1-sha1, diffie-hellman-group14-sha1, diffie-hellman-group-exchange-sha1 and diffie-hellman-group-exchange-sha256.</item>
       <item>Supported compression algorithms: none, zlib, [email protected],</item>
       <item>Supports unicode filenames if the emulator and the underlaying OS support it.
       See section DESCRIPTION in the
@@ -240,6 +240,13 @@ kex is implicit but public_key is set explicitly.</p>
 	</warning>
 	  </item>
 
+	  <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),I=integer(),Max=integer()}}]]></c></tag>
+	  <item>
+	    <p>Sets the three diffie-hellman-group-exchange parameters that guides the connected server in choosing a group.
+	    See RFC 4419 for the function of thoose.  The default value is <c>{512, 1024, 4096}</c>.
+	    </p>
+	  </item>
+
 	  <tag><c><![CDATA[{connect_timeout, timeout()}]]></c></tag>
 	  <item>
 	    <p>Sets a time-out on the transport layer
@@ -449,6 +456,15 @@ kex is implicit but public_key is set explicitly.</p>
 	</warning>
 	  </item>
 
+	  <tag><c><![CDATA[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} }]]></c></tag>
+	  <item>
+	    <p>Sets the groups that the server may choose among when diffie-hellman-group-exchange is negotiated.
+	    See RFC 4419 for details.
+	    </p>
+	    <p>If the parameter is <c>{file,filename()}</c>, the file must exist and have one or more three-tuples terminated by a dot. The interpretation is as if the tuples had been given directly in the option.  The file is read when the daemon starts.
+	    </p>
+	  </item>
+
 	  <tag><c><![CDATA[{pwdfun, fun(User::string(), password::string()) -> boolean()}]]></c></tag>
 	  <item>
 	    <p>Provides a function for password validation. This function is called
diff --git a/lib/ssh/src/ssh.erl b/lib/ssh/src/ssh.erl
index 370f086600..5b2e0a988c 100644
--- a/lib/ssh/src/ssh.erl
+++ b/lib/ssh/src/ssh.erl
@@ -373,6 +373,10 @@ handle_option([{auth_method_kb_interactive_data, _} = Opt | Rest], SocketOptions
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{preferred_algorithms,_} = Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([{dh_gex_groups,_} = Opt | Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([{dh_gex_limits,_} = Opt | Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{quiet_mode, _} = Opt|Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{idle_time, _} = Opt | Rest], SocketOptions, SshOptions) ->
@@ -411,6 +415,28 @@ handle_ssh_option({user_interaction, Value} = Opt) when is_boolean(Value) ->
     Opt;
 handle_ssh_option({preferred_algorithms,[_|_]} = Opt) -> 
     handle_pref_algs(Opt);
+handle_ssh_option({dh_gex_groups,L=[{I1,I2,I3}|_]}) when is_integer(I1), I1>0, 
+							 is_integer(I2), I2>0,
+							 is_integer(I3), I3>0 ->
+    {dh_gex_groups, lists:map(fun({N,G,P}) -> {N,{G,P}} end, L)};
+handle_ssh_option({dh_gex_groups,{file,File=[C|_]}}=Opt) when is_integer(C), C>0 ->
+    %% A string, (file name)
+    case file:consult(File) of
+	{ok, List} ->
+	    try handle_ssh_option({dh_gex_groups,List}) of
+		{dh_gex_groups,_} = NewOpt ->
+		    NewOpt
+	    catch
+		_:_ ->
+		    throw({error, {{eoptions, Opt}, "Bad format in file"}})
+	    end;
+	Error ->
+	    throw({error, {{eoptions, Opt},{"Error reading file",Error}}})
+    end;
+handle_ssh_option({dh_gex_limits,{Min,I,Max}} = Opt) when is_integer(Min), Min>0, 
+							  is_integer(I),   I>=Min,
+							  is_integer(Max), Max>=I ->
+    Opt;
 handle_ssh_option({connect_timeout, Value} = Opt) when is_integer(Value); Value == infinity ->
     Opt;
 handle_ssh_option({max_sessions, Value} = Opt) when is_integer(Value), Value>0 ->
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, _) ->
diff --git a/lib/ssh/src/ssh_transport.hrl b/lib/ssh/src/ssh_transport.hrl
index ab59742b96..9e1de171c2 100644
--- a/lib/ssh/src/ssh_transport.hrl
+++ b/lib/ssh/src/ssh_transport.hrl
@@ -188,4 +188,24 @@
 -define(SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE,  14).
 -define(SSH_DISCONNECT_ILLEGAL_USER_NAME,  15).
 
+%% groups
+
+%%% rfc 2489, ch 6.2
+-define(dh_group1,
+    {2, 16#FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF}).
+
+%%% rfc 3526, ch3
+-define(dh_group14,
+    {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}).
+
+%%% rfc 3526, ch4
+-define(dh_group15,
+   {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}).
+
+%%% rfc 3526, ch5
+-define(dh_group16,
+   {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}).
+
+
+
 -endif. % -ifdef(ssh_transport).
diff --git a/lib/ssh/test/ssh_protocol_SUITE.erl b/lib/ssh/test/ssh_protocol_SUITE.erl
index d82cdaf2c7..246e3d4898 100644
--- a/lib/ssh/test/ssh_protocol_SUITE.erl
+++ b/lib/ssh/test/ssh_protocol_SUITE.erl
@@ -56,7 +56,11 @@ groups() ->
 		       lib_no_match
 		      ]},
      {kex, [], [no_common_alg_server_disconnects,
-		no_common_alg_client_disconnects
+		no_common_alg_client_disconnects,
+		gex_client_init_default_noexact,
+		gex_client_init_default_exact,
+		gex_client_init_option_groups,
+		gex_client_init_option_groups_file
 		]}
     ].
 
@@ -68,9 +72,32 @@ end_per_suite(Config) ->
     stop_apps(Config).
 
 
+
+init_per_testcase(TC, Config) when TC == gex_client_init_default_noexact ;
+				   TC == gex_client_init_default_exact ;
+				   TC == gex_client_init_option_groups ;
+				   TC == gex_client_init_option_groups_file ->
+    Opts = case TC of
+	       gex_client_init_option_groups ->
+		   [{dh_gex_groups, [{2345, 3, 41}]}];
+	       gex_client_init_option_groups_file ->
+		   DataDir = ?config(data_dir, Config),
+		   F = filename:join(DataDir, "dh_group_test"),
+		   [{dh_gex_groups, {file,F}}];
+	       _ ->
+		   []
+	   end,
+    start_std_daemon(Config,
+		     [{preferred_algorithms, ssh_transport:supported_algorithms()}
+		      | Opts]);
 init_per_testcase(_TestCase, Config) ->
     check_std_daemon_works(Config, ?LINE).
 
+end_per_testcase(TC, Config) when TC == gex_client_init_default_noexact ;
+				  TC == gex_client_init_default_exact ;
+				  TC == gex_client_init_option_groups ;
+				  TC == gex_client_init_option_groups_file ->
+    stop_std_daemon(Config);
 end_per_testcase(_TestCase, Config) ->
     check_std_daemon_works(Config, ?LINE).
 
@@ -293,6 +320,48 @@ no_common_alg_client_disconnects(Config) ->
 	X -> ct:fail(X)
     end.
 
+%%%--------------------------------------------------------------------
+gex_client_init_default_noexact(Config) ->
+    do_gex_client_init(Config, {2000, 3000, 4000},
+		       %% Warning, app knowledege:
+		       ?dh_group15).
+
+
+gex_client_init_default_exact(Config) ->
+    do_gex_client_init(Config, {2000, 2048, 4000},
+		       %% Warning, app knowledege:
+		       ?dh_group14).
+
+
+gex_client_init_option_groups(Config) ->
+    do_gex_client_init(Config, {2000, 2048, 4000}, {3,41}).
+
+
+gex_client_init_option_groups_file(Config) ->
+    do_gex_client_init(Config, {2000, 2048, 4000}, {5,61}).
+
+do_gex_client_init(Config, {Min,N,Max}, {G,P}) ->
+    {ok,_} =
+	ssh_trpt_test_lib:exec(
+	  [{set_options, [print_ops, print_seqnums, print_messages]},
+	   {connect,
+	    server_host(Config),server_port(Config),
+	    [{silently_accept_hosts, true},
+	     {user_dir, user_dir(Config)},
+	     {user_interaction, false},
+	     {preferred_algorithms,[{kex,['diffie-hellman-group-exchange-sha1']}]}
+	    ]},
+	   receive_hello,
+	   {send, hello},
+	   {send, ssh_msg_kexinit},
+	   {match, #ssh_msg_kexinit{_='_'}, receive_msg},
+	   {send, #ssh_msg_kex_dh_gex_request{min = Min, 
+					      n = N,
+					      max = Max}},
+	   {match, #ssh_msg_kex_dh_gex_group{p=P, g=G, _='_'},  receive_msg}
+	  ]
+	 ).
+
 %%%================================================================
 %%%==== Internal functions ========================================
 %%%================================================================
@@ -353,6 +422,7 @@ stop_std_daemon(Config) ->
     ct:log("Std server ~p at ~p:~p stopped", [server_pid(Config), server_host(Config), server_port(Config)]),
     lists:keydelete(server, 1, Config).
 
+
 check_std_daemon_works(Config, Line) ->
     case std_connect(Config) of
 	{ok,C} ->
@@ -362,13 +432,9 @@ check_std_daemon_works(Config, Line) ->
 	    ok = ssh:close(C),
 	    Config;
 	Error = {error,_} ->
-	    {fail,
-	     lists:flatten(
-	       io_lib:format("Standard server ~p:~p ~p is ill at line ~p: ~p",
-			     [server_host(Config), server_port(Config), 
-			      server_pid(Config), Line, Error])
-	      )
-	    }
+	    ct:fail("Standard server ~p:~p ~p is ill at line ~p: ~p",
+		    [server_host(Config), server_port(Config), 
+		     server_pid(Config), Line, Error])
     end.
 
 server_pid(Config)  -> element(1,?v(server,Config)).
diff --git a/lib/ssh/test/ssh_protocol_SUITE_data/dh_group_test b/lib/ssh/test/ssh_protocol_SUITE_data/dh_group_test
new file mode 100644
index 0000000000..2887bb4b60
--- /dev/null
+++ b/lib/ssh/test/ssh_protocol_SUITE_data/dh_group_test
@@ -0,0 +1,3 @@
+{2222, 5, 61}.
+{1111, 7, 91}.
+