Re: [PATCH v2] vpnmain.cgi: set SubjectAlternativeName default during root certificate generation

[Michael Tremer <michael.tremer@ipfire.org>]

[-- Attachment #1: Type: text/plain, Size: 1985 bytes --]

Hello,

> On 5 Jan 2020, at 18:11, Peter Müller <peter.mueller(a)ipfire.org> wrote:
> 
> Some IPsec implementations such as OpenIKED require SubjectAlternativeName
> data on certificates and refuse to establish connections otherwise.
> 
> The StrongSwan project also recommends it (see:
> https://wiki.strongswan.org/projects/strongswan/wiki/SimpleCA) although
> it is currently not enforced by their IPsec software.
> 
> For convenience purposes and to raise awareness, this patch adds a default
> SubjectAlternativeName based on the machines hostname or IP address. Existing
> certificates remain unchanged for obvious reasons.
> 
> Fixes #11594
> 
> Signed-off-by: Peter Müller <peter.mueller(a)ipfire.org>
> ---
> html/cgi-bin/vpnmain.cgi | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/html/cgi-bin/vpnmain.cgi b/html/cgi-bin/vpnmain.cgi
> index 33b504bc9..9b7bd81ca 100644
> --- a/html/cgi-bin/vpnmain.cgi
> +++ b/html/cgi-bin/vpnmain.cgi
> @@ -822,8 +822,10 @@ END
> 			close IPADDR;
> 			chomp ($ipaddr);
> 			$cgiparams{'ROOTCERT_HOSTNAME'} = (gethostbyaddr(pack("C4", split(/\./, $ipaddr)), 2))[0];
> +			$cgiparams{'SUBJECTALTNAME'} = "DNS:" . (gethostbyaddr(pack("C4", split(/\./, $ipaddr)), 2))[0];

This relies on DNS working at the time of generating the certificate which obviously is a very bad idea.

Since the original code is like this, I guess there is not point in changing it, but you could have however just copied the value of ROOTCERT_HOSTNAME to avoid a second DNS lookup.

> 			if ($cgiparams{'ROOTCERT_HOSTNAME'} eq '') {
> 				$cgiparams{'ROOTCERT_HOSTNAME'} = $ipaddr;
> +				$cgiparams{'SUBJECTALTNAME'} = "IP:" . $ipaddr;
> 			}
> 		}

Does overwriting SUBJECTALTNAME work? There is a place where the user can set this. Is that still being honoured?

-Michael

> 		$cgiparams{'ROOTCERT_COUNTRY'} = $vpnsettings{'ROOTCERT_COUNTRY'} if (!$cgiparams{'ROOTCERT_COUNTRY'});
> -- 
> 2.16.4
>