On 25.04.2013 14:27, Konstantin Khomoutov wrote:
> Stephen, could you please help us and look at modifying your patch so
> that it applies on 2.1.10? My own Erlang skills are not up to this
> task. I'm referring to this Debian bug report [1]. And the release
> time is unfortunately very close.
Hi, I backported the patch to the v2.1.10 tag of ejabberd, could you
please verify that it works? I just tested it with the haskell testcase
from joey hess.
>From 60376459c183543f5767e8cf0a93690cf52d6e24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephen=20R=C3=B6ttger?= <stephen.roett...@zero-entropy.de>
Date: Thu, 25 Apr 2013 16:34:45 +0200
Subject: [PATCH] SCRAM optional parameter parsing bugfix
The server gave an authentication error, if optional parameters
were present in the GS2 Header. Specifically, the "a=" parameter,
that can be used by admins to login as a different user.
Backport of 9e9b0eae802ee0508db6780426954efd048e7976 to 2.1.10
---
src/cyrsasl_scram.erl | 58 ++++++++++++++++++++++++++++++---------------------
1 file changed, 34 insertions(+), 24 deletions(-)
diff --git a/src/cyrsasl_scram.erl b/src/cyrsasl_scram.erl
index 002d6e4..efc63c8 100644
--- a/src/cyrsasl_scram.erl
+++ b/src/cyrsasl_scram.erl
@@ -34,6 +34,8 @@
-include("ejabberd.hrl").
+-include("jlib.hrl").
+
-behaviour(cyrsasl).
-record(state, {step, stored_key, server_key, username, get_password, check_password,
@@ -52,8 +54,12 @@ mech_new(_Host, GetPassword, _CheckPassword, _CheckPasswordDigest) ->
{ok, #state{step = 2, get_password = GetPassword}}.
mech_step(#state{step = 2} = State, ClientIn) ->
- case string:tokens(ClientIn, ",") of
- [CBind, UserNameAttribute, ClientNonceAttribute] when (CBind == "y") or (CBind == "n") ->
+ case re:split(ClientIn, ",", [{return, list}]) of
+ [_CBind, _AuthorizationIdentity, _UserNameAttribute, _ClientNonceAttribute, ExtensionAttribute | _]
+ when ExtensionAttribute /= [] ->
+ {error, <<"protocol-error-extension-not-supported">>};
+ [CBind, _AuthorizationIdentity, UserNameAttribute, ClientNonceAttribute | _]
+ when (CBind == "y") or (CBind == "n") ->
case parse_attribute(UserNameAttribute) of
{error, Reason} ->
{error, Reason};
@@ -100,32 +106,36 @@ mech_step(#state{step = 4} = State, ClientIn) ->
case string:tokens(ClientIn, ",") of
[GS2ChannelBindingAttribute, NonceAttribute, ClientProofAttribute] ->
case parse_attribute(GS2ChannelBindingAttribute) of
- {$c, CVal} when (CVal == "biws") or (CVal == "eSws") ->
- %% biws is base64 for n,, => channelbinding not supported
- %% eSws is base64 for y,, => channelbinding supported by client only
- Nonce = State#state.client_nonce ++ State#state.server_nonce,
- case parse_attribute(NonceAttribute) of
- {$r, CompareNonce} when CompareNonce == Nonce ->
- case parse_attribute(ClientProofAttribute) of
- {$p, ClientProofB64} ->
- ClientProof = base64:decode(ClientProofB64),
- AuthMessage = State#state.auth_message ++ "," ++ string:substr(ClientIn, 1, string:str(ClientIn, ",p=")-1),
- ClientSignature = scram:client_signature(State#state.stored_key, AuthMessage),
- ClientKey = scram:client_key(ClientProof, ClientSignature),
- CompareStoredKey = scram:stored_key(ClientKey),
- if CompareStoredKey == State#state.stored_key ->
- ServerSignature = scram:server_signature(State#state.server_key, AuthMessage),
- {ok, [{username, State#state.username}], "v=" ++ base64:encode_to_string(ServerSignature)};
- true ->
- {error, "bad-auth"}
+ {$c, CVal} ->
+ ChannelBindingSupport = string:left(jlib:decode_base64(CVal), 1),
+ if (ChannelBindingSupport == "n")
+ or (ChannelBindingSupport == "y") ->
+ Nonce = State#state.client_nonce ++ State#state.server_nonce,
+ case parse_attribute(NonceAttribute) of
+ {$r, CompareNonce} when CompareNonce == Nonce ->
+ case parse_attribute(ClientProofAttribute) of
+ {$p, ClientProofB64} ->
+ ClientProof = base64:decode(ClientProofB64),
+ AuthMessage = State#state.auth_message ++ "," ++ string:substr(ClientIn, 1, string:str(ClientIn, ",p=")-1),
+ ClientSignature = scram:client_signature(State#state.stored_key, AuthMessage),
+ ClientKey = scram:client_key(ClientProof, ClientSignature),
+ CompareStoredKey = scram:stored_key(ClientKey),
+ if CompareStoredKey == State#state.stored_key ->
+ ServerSignature = scram:server_signature(State#state.server_key, AuthMessage),
+ {ok, [{username, State#state.username}], "v=" ++ base64:encode_to_string(ServerSignature)};
+ true ->
+ {error, "bad-auth"}
+ end;
+ _Else ->
+ {error, "bad-protocol"}
end;
+ {$r, _} ->
+ {error, "bad-nonce"};
_Else ->
{error, "bad-protocol"}
end;
- {$r, _} ->
- {error, "bad-nonce"};
- _Else ->
- {error, "bad-protocol"}
+ true ->
+ {error, "bad-channel-binding"}
end;
_Else ->
{error, "bad-protocol"}
--
1.8.1.4
