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From: Daniel Borkmann <daniel@iogearbox.net>
To: Jamal Hadi Salim <jhs@mojatatu.com>, davem@davemloft.net
Cc: netdev@vger.kernel.org, xiyou.wangcong@gmail.com,
	Jamal Hadi Salim <hadi@mojatatu.com>
Subject: Re: [net-next PATCH v2 1/1] net sched actions: skbedit add support for mod-ing skb pkt_type
Date: Mon, 13 Jun 2016 10:00:27 +0200	[thread overview]
Message-ID: <575E681B.8080500@iogearbox.net> (raw)
In-Reply-To: <1465766693-2336-1-git-send-email-jhs@emojatatu.com>

Hi Jamal,

On 06/12/2016 11:24 PM, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <hadi@mojatatu.com>
>
> Extremely useful for setting packet type to host so i dont
> have to modify the dst mac address using pedit (which requires
> that i know the mac address)
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>

I'm wondering if this is a good idea, I was thinking about something
like this as well some time ago. So far pkt_type is just exposed as
read-only to user space right now and I'm a bit worried that when we
allow to set it arbitrarily, then this could lead to hard to debug
issues since skb->pkt_type is used in a lot of places with possibly
different assumptions and applications now need to mistrust the kernel
whether skb->pkt_type was actually what the kernel itself set in the
first place or skbedit with possibly some nonsense value (like rewriting
PACKET_OUTGOING into PACKET_LOOPBACK, etc). Did you audit that this
is safe?

Thanks,
Daniel

  reply	other threads:[~2016-06-13  8:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-12 21:24 [net-next PATCH v2 1/1] net sched actions: skbedit add support for mod-ing skb pkt_type Jamal Hadi Salim
2016-06-13  8:00 ` Daniel Borkmann [this message]
2016-06-13 11:52   ` Jamal Hadi Salim
2016-06-13 12:21     ` Daniel Borkmann
2016-06-13 21:52       ` Jamal Hadi Salim

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