netdev - Re: Revert 462fb2af9788a82a534f8184abfde31574e1cfa0 (bridge : Sanitize skb before it enters the IP stack)

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Date:	Tue, 20 May 2014 13:27:32 +0930
From:	David Newall <davidn@...idnewall.com>
To:	Florian Westphal <fw@...len.de>
CC:	Stephen Hemminger <stephen@...workplumber.org>,
	Netdev <netdev@...r.kernel.org>, netfilter-devel@...r.kernel.org,
	bridge@...ts.linux-foundation.org
Subject: Re: Revert 462fb2af9788a82a534f8184abfde31574e1cfa0 (bridge : Sanitize
 skb before it enters the IP stack)

On 20/05/14 02:39, Florian Westphal wrote:
>  From a quick glance, it should be sufficient to edit
> br_parse_ip_options() and remove everything after
>
> memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));

Yes.  That's the way it used to be, and how it would return with the 
change I'm proposing.  The br_parse_ip_option function would be removed 
and its remaining code moved back from whence it came.


> A 2nd step would be to move a copy of ip_options_compile()
> into br_netfilter.c and trim it down to only validate the
> ipv4 header without modifying it.

The bridge sounds like the wrong place to validate an IPv4 header, 
unless it also validates every type of header; and that can't be right.  
That we need to zero the cb area seems like a big clue that IP's 
treatment of the area is lame.  I think that's where the problem lies, 
and that the right thing to do is to yank out the crap from bridge that 
papers over IP's weakness.
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