netdev - Re: [PATCH 1/1] tproxy: do not assign timewait sockets to skb->sk

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Date:	Wed, 16 Feb 2011 09:54:31 +0100
From:	KOVACS Krisztian <hidden@...abit.hu>
To:	Patrick McHardy <kaber@...sh.net>
CC:	Florian Westphal <fw@...len.de>, netfilter-devel@...r.kernel.org,
	netdev@...r.kernel.org, Balazs Scheidler <bazsi@...abit.hu>
Subject: Re: [PATCH 1/1] tproxy: do not assign timewait sockets to skb->sk

Hi,

On 02/14/2011 04:51 PM, Patrick McHardy wrote:
> Am 14.02.2011 12:44, schrieb Florian Westphal:
>> Assigning a socket in timewait state to skb->sk can trigger
>> kernel oops, e.g. in nfnetlink_log, which does:
>>
>> if (skb->sk) {
>>          read_lock_bh(&skb->sk->sk_callback_lock);
>>          if (skb->sk->sk_socket&&  skb->sk->sk_socket->file) ...
>>
>> in the timewait case, accessing sk->sk_callback_lock and sk->sk_socket
>> is invalid.
>>
>> Either all of these spots will need to add a test for sk->sk_state != TCP_TIME_WAIT,
>> or xt_TPROXY must not assign a timewait socket to skb->sk.
>>
>> This does the latter.
>>
>> If a TW socket is found, assign the tproxy nfmark, but skip the skb->sk assignment,
>> thus mimicking behaviour of a '-m socket .. -j MARK/ACCEPT' re-routing rule.
>>
>> The 'SYN to TW socket' case is left unchanged -- we try to redirect to the
>> listener socket.
>>
>> Cc: Balazs Scheidler<bazsi@...abit.hu>
>> Cc: KOVACS Krisztian<hidden@...abit.hu>
>> Signed-off-by: Florian Westphal<fwestphal@...aro.com>
>
> Looks fine to me. Balazs. Krisztian, any objections?

Seems to be OK, as far as I can see.

Florian, did you make sure the tests still run after applying this patch?

http://git.balabit.hu/?p=bazsi/tproxy-test.git;a=summary

-- 
KOVACS Krisztian
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