netdev - Re: [RFC] packet: handle too big packets for PACKET

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Message-Id: <1408063859.864295.152910193.45470221@webmail.messagingengine.com>
Date:	Fri, 15 Aug 2014 02:50:59 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Daniel Borkmann <dborkman@...hat.com>,
	Neil Horman <nhorman@...driver.com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: [RFC] packet: handle too big packets for PACKET_V3

Another thought...

On Fri, Aug 15, 2014, at 02:43, Hannes Frederic Sowa wrote:
> On Fri, Aug 15, 2014, at 02:09, Eric Dumazet wrote:
> > It looks like PACKET_V3 has no check that a packet can always fit in a
> > block.
> > 
> > Its trivial with GRO to break the assumption and write into kernel
> > memory.
>
> [...]
>
> 4) Can we still try to skb_gso_segment the packet again? Not nice, but I
> guess this will work. Maybe depending on a tunable (default to on)?

5) Or let a setsockopt control the NETIF_F_GRO bit of an interface if it
is bound to it? This will likely result in an implementation where we
must count current TPACKET_V3 sockets disabling GRO on an interface,
much like promisc counter.

Bye,
Hannes
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