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-rw-r--r--lib/ssh/src/ssh_transport.erl29
1 files changed, 25 insertions, 4 deletions
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index 35bfadb1df..d61fc76c0a 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -441,13 +441,14 @@ handle_kexdh_reply(#ssh_msg_kexdh_reply{public_host_key = PeerPubHostKey,
%%%
%%% diffie-hellman-group-exchange-sha1
%%%
-handle_kex_dh_gex_request(#ssh_msg_kex_dh_gex_request{min = Min,
+handle_kex_dh_gex_request(#ssh_msg_kex_dh_gex_request{min = Min0,
n = NBits,
- max = Max},
- Ssh0=#ssh{opts=Opts}) when Min=<NBits, NBits=<Max ->
+ max = Max0},
+ Ssh0=#ssh{opts=Opts}) when Min0=<NBits, NBits=<Max0 ->
%% server
+ {Min, Max} = adjust_gex_min_max(Min0, Max0, Opts),
case public_key:dh_gex_group(Min, NBits, Max,
- proplists:get_value(dh_gex_groups,Opts)) of
+ proplists:get_value(dh_gex_groups,Opts)) of
{ok, {_Sz, {G,P}}} ->
{Public, Private} = generate_key(dh, [P,G]),
{SshPacket, Ssh} =
@@ -471,6 +472,26 @@ handle_kex_dh_gex_request(_, _) ->
language = ""}
}).
+
+adjust_gex_min_max(Min0, Max0, Opts) ->
+ case proplists:get_value(dh_gex_limits, Opts) of
+ undefined ->
+ {Min0, Max0};
+ {Min1, Max1} ->
+ Min2 = max(Min0, Min1),
+ Max2 = min(Max0, Max1),
+ if
+ Min2 =< Max2 ->
+ {Min2, Max2};
+ Max2 < Min2 ->
+ throw(#ssh_msg_disconnect{
+ code = ?SSH_DISCONNECT_PROTOCOL_ERROR,
+ description = "No possible diffie-hellman-group-exchange group possible",
+ language = ""})
+ end
+ end.
+
+
handle_kex_dh_gex_group(#ssh_msg_kex_dh_gex_group{p = P, g = G}, Ssh0) ->
%% client
{Public, Private} = generate_key(dh, [P,G]),