lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Tue, 19 Dec 2006 16:27:36 +0100 (MET)
From:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
To:	Patrick McHardy <kaber@...sh.net>
cc:	Netfilter Developer Mailing List 
	<netfilter-devel@...ts.netfilter.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xt_request_find_match


>>>>Reusing code is a good idea, and I would like to do so from my 
>>>>match modules. netfilter already provides a xt_request_find_target() but 
>>>>an xt_request_find_match() does not yet exist. This patch adds it.
>>>
>>>Why does your match module needs to lookup other matches?
>> 
>> To use them?
>> 
>> I did not want to write
>> 
>> some_xt_target() {
>>     if(skb->nh.iph->protocol == IPPROTO_TCP)
>>         do_this();
>>     else
>>         do_that();
>> }
>
>I don't think
>
>xt_request_find_match(match->family, "tcp", 0)->match(lots of arguments)
>
>is better than a simple comparison. Besides that the tcp match itself
>expects that the protocol match already checked for IPPROTO_TCP, so
>you'd still have to do it.
>>     /* To quote Alan:
>> 
>>        Don't allow a fragment of TCP 8 bytes in. Nobody normal
>>        causes this. Its a cracker trying to break in by doing a
>>        flag overwrite to pass the direction checks.
>>     */
>
>This check makes sure the flags are not overwritten _after you
>matched on them_. It doesn't matter at all if you're only
>interested in the protocol since the user didn't tell you to care.

Ok, but let's say I wanted to use a bigger match module (layer7, anyone?)
Then it's just not if(protocol == IPPROTO_TCP). What's the preferred solution
then?


	-`J'
-- 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists