linux-kernel - Re: [PATCH] ipvs: Keep skb->sk when allocating headroom on tunnel xmit

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Message-ID: <545D43BD.8030203@fb.com>
Date:	Fri, 7 Nov 2014 14:12:13 -0800
From:	Calvin Owens <calvinowens@...com>
To:	Julian Anastasov <ja@....bg>
CC:	Simon Horman <horms@...ge.net.au>,
	Wensong Zhang <wensong@...ux-vs.org>,
	<lvs-devel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <agartrell@...com>, <kernel-team@...com>
Subject: Re: [PATCH] ipvs: Keep skb->sk when allocating headroom on tunnel
 xmit

On 11/05/2014 01:21 AM, Julian Anastasov wrote:
>
> 	Hello,
>
> On Tue, 4 Nov 2014, Calvin Owens wrote:
>
>> ip_vs_prepare_tunneled_skb() ignores ->sk when allocating a new
>> skb, either unconditionally setting ->sk to NULL or allowing
>> the uninitialized ->sk from a newly allocated skb to leak through
>> to the caller.
>>
>> This patch properly copies ->sk and increments its reference count.
>>
>> Signed-off-by: Calvin Owens <calvinowens@...com>
>
> 	Good catch. Please, extend your patch to
> fix also the second place that has such error,
> ip_vs_tunnel_xmit_v6. This call is missing from long time,
> it was not needed. But commits that allow skb->sk (local
> clients) already need it, eg.

I'm not sure where exactly you mean: ip_vs_tunnel_xmit_v6() calls
ip_vs_prepare_tunneled_skb() to do the allocation, so this patch covers 
that case.

In older versions of the kernel, ip_vs_tunnel_xmit_v6() does it 
directly, could that be what you're looking at?

> - f2428ed5e7bc89c7 ("ipvs: load balance ipv6 connections from a local
> process"), 2.6.28
> - 4856c84c1358b798 ("ipvs: load balance IPv4 connections from a local
> process"), 2.6.28
>
>> ---
>>   net/netfilter/ipvs/ip_vs_xmit.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
>> index 437a366..bd90bf8 100644
>> --- a/net/netfilter/ipvs/ip_vs_xmit.c
>> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
>> @@ -846,6 +846,8 @@ ip_vs_prepare_tunneled_skb(struct sk_buff *skb, int skb_af,
>>   		new_skb = skb_realloc_headroom(skb, max_headroom);
>>   		if (!new_skb)
>>   			goto error;
>> +		if (skb->sk)
>> +			skb_set_owner_w(new_skb, skb->sk);
>>   		consume_skb(skb);
>>   		skb = new_skb;
>>   	}
>
> Regards
>
> --
> Julian Anastasov <ja@....bg>
>
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