Re: [PATCH v2] OpenVPN: Introduce new AES-GCM cipher for N2N and RW

[ummeegge <ummeegge@ipfire.org>]

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As a version 3 idea,
or might it be possibly a better idea to delete the '--auth *' directive in N2N.conf
if AES-GCM has been chosen ? i think it might also be better to integrate
'--tls-crypt' --> https://www.mail-archive.com/openvpn-devel(a)lists.sourceforge.net/msg12357.html 
instead of '--tls-auth' to N2N connections which uses a static AES-256-CTR whereby
a HMAC can not be selected ?

But also it might be time to delete SHA1 complete from Net-to-Net HMAC
selection since this won´t harm old connections but brings a little
more security per default ?

Sorry for the back and forth but the way is the goal :D .

Some feedback might be nevertheless nice and important.

Greetings,

Erik


Am Mittwoch, den 14.02.2018, 15:40 +0100 schrieb Erik Kapfer:
> AES-GCM 128, 196 and 256 bit has been added to Net-to-Net and
> Roadwarrior section.
> 
> Cipher menu description has been changed for N2N and RW since AES-GCM 
> uses own authentication encryption (GMAC).
>     More information can be found in here https://tools.ietf.org/html
> /rfc5288 .
> Added java script snipped to disable HMAC selection for N2N if AES-
> GCM has been selected.
>     'auth *' line in N2N.conf won´t be deleted even if AES-GCM is
> used so possible individual '--tls-auth' configurations won´t broke.
>     'auth *' line in N2N.conf will also be ignored if AES-GCM is used
> and no '--tls-auth' are configured.
> Left HMAC selection menu for Roadwarriors as it was since the WUI do
> provides '--tls-auth' which uses the configuered HMAC even AES-GCM
> has been applied.
> 
> Signed-off-by: Erik Kapfer <erik.kapfer(a)ipfire.org>
> ---
>  html/cgi-bin/ovpnmain.cgi | 32 ++++++++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/html/cgi-bin/ovpnmain.cgi b/html/cgi-bin/ovpnmain.cgi
> index 9f5e682..0a18ec7 100644
> --- a/html/cgi-bin/ovpnmain.cgi
> +++ b/html/cgi-bin/ovpnmain.cgi
> @@ -4543,6 +4543,9 @@ if ($cgiparams{'TYPE'} eq 'net') {
>      }
>      $checked{'PMTU_DISCOVERY'}{$cgiparams{'PMTU_DISCOVERY'}} =
> 'checked=\'checked\'';
>  
> +    $selected{'DCIPHER'}{'AES-256-GCM'} = '';
> +    $selected{'DCIPHER'}{'AES-192-GCM'} = '';
> +    $selected{'DCIPHER'}{'AES-128-GCM'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-256-CBC'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-192-CBC'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-128-CBC'} = '';
> @@ -4706,7 +4709,10 @@ if ($cgiparams{'TYPE'} eq 'net') {
>  	</tr>
>  
>  	<tr><td class='boldbase'>$Lang::tr{'cipher'}</td>
> -		<td><select name='DCIPHER'>
> +		<td><select name='DCIPHER'  id="n2ncipher" required>
> +				<option value='AES-256-GCM'		
> $selected{'DCIPHER'}{'AES-256-GCM'}>AES-GCM (256 $Lang::tr{'bit'})
> with SHA384</option>
> +				<option value='AES-192-GCM'		
> $selected{'DCIPHER'}{'AES-192-GCM'}>AES-GCM (192 $Lang::tr{'bit'})
> with SHA256</option>
> +				<option value='AES-128-GCM'		
> $selected{'DCIPHER'}{'AES-128-GCM'}>AES-GCM (128 $Lang::tr{'bit'})
> with SHA256</option>
>  				<option value='CAMELLIA-256-CBC'	
> $selected{'DCIPHER'}{'CAMELLIA-256-CBC'}>CAMELLIA-CBC (256
> $Lang::tr{'bit'})</option>
>  				<option value='CAMELLIA-192-CBC'	
> $selected{'DCIPHER'}{'CAMELLIA-192-CBC'}>CAMELLIA-CBC (192
> $Lang::tr{'bit'})</option>
>  				<option value='CAMELLIA-128-CBC'	
> $selected{'DCIPHER'}{'CAMELLIA-128-CBC'}>CAMELLIA-CBC (128
> $Lang::tr{'bit'})</option>
> @@ -4723,7 +4729,7 @@ if ($cgiparams{'TYPE'} eq 'net') {
>  		</td>
>  
>  		<td class='boldbase'>$Lang::tr{'ovpn ha'}:</td>
> -		<td><select name='DAUTH'>
> +		<td><select name='DAUTH' id="n2nhmac">
>  				<option value='whirlpool'		
> $selected{'DAUTH'}{'whirlpool'}>Whirlpool (512
> $Lang::tr{'bit'})</option>
>  				<option value='SHA512'		
> 	$selected{'DAUTH'}{'SHA512'}>SHA2 (512
> $Lang::tr{'bit'})</option>
>  				<option value='SHA384'		
> 	$selected{'DAUTH'}{'SHA384'}>SHA2 (384
> $Lang::tr{'bit'})</option>
> @@ -4737,6 +4743,22 @@ if ($cgiparams{'TYPE'} eq 'net') {
>  END
>  ;
>  	}
> +
> +#### JAVA SCRIPT ####
> +# Validate N2N cipher. If GCM is used, disable HMAC menu
> +print<<END;
> +	<script>
> +		var disable_options = false;
> +		document.getElementById('n2ncipher').onchange =
> function () {
> +			if((this.value == "AES-256-GCM"||this.value
> == "AES-192-GCM"||this.value == "AES-128-GCM")) {
> +				document.getElementById('n2nhmac').s
> etAttribute('disabled', true);
> +			} else {
> +				document.getElementById('n2nhmac').r
> emoveAttribute('disabled');
> +			}
> +		}
> +	</script>
> +END
> +
>  #jumper
>  	print "<tr><td class='boldbase'>$Lang::tr{'remark
> title'}</td>";
>  	print "<td colspan='3'><input type='text' name='REMARK'
> value='$cgiparams{'REMARK'}' size='55' maxlength='50'
> /></td></tr></table>";
> @@ -5108,6 +5130,9 @@ END
>      $selected{'DPROTOCOL'}{'tcp'} = '';
>      $selected{'DPROTOCOL'}{$cgiparams{'DPROTOCOL'}} = 'SELECTED';
>  
> +    $selected{'DCIPHER'}{'AES-256-GCM'} = '';
> +    $selected{'DCIPHER'}{'AES-192-GCM'} = '';
> +    $selected{'DCIPHER'}{'AES-128-GCM'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-256-CBC'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-192-CBC'} = '';
>      $selected{'DCIPHER'}{'CAMELLIA-128-CBC'} = '';
> @@ -5204,6 +5229,9 @@ END
>  
>  		<td class='boldbase'
> nowrap='nowrap'>$Lang::tr{'cipher'}</td>
>  		<td><select name='DCIPHER'>
> +				<option value='AES-256-GCM'
> $selected{'DCIPHER'}{'AES-256-GCM'}>AES-GCM (256 $Lang::tr{'bit'})
> with SHA384</option>
> +				<option value='AES-192-GCM'
> $selected{'DCIPHER'}{'AES-192-GCM'}>AES-GCM (192 $Lang::tr{'bit'})
> with SHA256</option>
> +				<option value='AES-128-GCM'
> $selected{'DCIPHER'}{'AES-128-GCM'}>AES-GCM (128 $Lang::tr{'bit'})
> with SHA256</option>
>  				<option value='CAMELLIA-256-CBC'
> $selected{'DCIPHER'}{'CAMELLIA-256-CBC'}>CAMELLIA-CBC (256
> $Lang::tr{'bit'})</option>
>  				<option value='CAMELLIA-192-CBC'
> $selected{'DCIPHER'}{'CAMELLIA-192-CBC'}>CAMELLIA-CBC (192
> $Lang::tr{'bit'})</option>
>  				<option value='CAMELLIA-128-CBC'
> $selected{'DCIPHER'}{'CAMELLIA-128-CBC'}>CAMELLIA-CBC (128
> $Lang::tr{'bit'})</option>