netdev - Re: [net PATCH] ip_vti/ip6_vti: Clear skb->mark when resetting skb->dev in receive path

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Message-ID: <20150514062614.GA6320@gondor.apana.org.au>
Date:	Thu, 14 May 2015 14:26:14 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Alexander Duyck <alexander.h.duyck@...hat.com>,
	netdev@...r.kernel.org, steffen.klassert@...unet.com,
	tgraf@...g.ch, davem@...emloft.net
Subject: Re: [net PATCH] ip_vti/ip6_vti: Clear skb->mark when resetting
 skb->dev in receive path

On Wed, May 13, 2015 at 11:14:39PM -0700, Alexander Duyck wrote:
> 
> The fact is I am not all that familiar with the vti code and just
> started crawling through it a few days ago, but it seems like it is
> overwriting the skb->mark value with the i_key to determine which
> policy to use.  The code prior to commit df3893c176e9 ("vti: Update
> the ipv4 side to use it's own receive hook.") was saving the old
> skb->mark, overwriting it, and then restoring it after a call to
> xfrm4_policy_check.  After that commit it was letting
> skb_scrub_packet in vti_rcv_cb clear the mark and it was just
> dropped.

Steffen, why is vti touching skb->mark at all? This is supposed
to be a field used by user-space to control a packet as it moves
inside the kernel.  Seconding it for other purposes looks very
wrong.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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