linux-kernel - Re: [PATCH net-next 1/9] openvswitch: Scrub packet in ovs_vport

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Date:	Fri, 31 Jul 2015 10:51:11 -0700
From:	Joe Stringer <joestringer@...ira.com>
To:	Hannes Frederic Sowa <hannes@...hat.com>
Cc:	Linux Netdev List <netdev@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Patrick McHardy <kaber@...sh.net>,
	Justin Pettit <jpettit@...ira.com>,
	Pravin Shelar <pshelar@...ira.com>,
	Andy Zhou <azhou@...ira.com>, Jesse Gross <jesse@...ira.com>,
	Florian Westphal <fwestpha@...hat.com>,
	Thomas Graf <tgraf@...ronetworks.com>
Subject: Re: [PATCH net-next 1/9] openvswitch: Scrub packet in ovs_vport_receive()

On 31 July 2015 at 07:34, Hannes Frederic Sowa <hannes@...hat.com> wrote:
> On Thu, 2015-07-30 at 11:12 -0700, Joe Stringer wrote:
>> Signed-off-by: Joe Stringer <joestringer@...ira.com>
>> ---
>>  net/openvswitch/vport.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
>> index d14f594..baa018f 100644
>> --- a/net/openvswitch/vport.c
>> +++ b/net/openvswitch/vport.c
>> @@ -475,6 +475,9 @@ void ovs_vport_receive(struct vport *vport, struct
>> sk_buff *skb,
>>       struct sw_flow_key key;
>>       int error;
>>
>> +     if (!skb->sk || (sock_net(skb->sk) != read_pnet(&vport->dp
>> ->net)))
>> +             skb_scrub_packet(skb, true);
>> +
>>       stats = this_cpu_ptr(vport->percpu_stats);
>>       u64_stats_update_begin(&stats->syncp);
>>       stats->rx_packets++;
>
> In general, this shouldn't be necessary as the packet should already be
> scrubbed before they arrive here.
>
> Could you maybe add a WARN_ON and check how those skbs with conntrack
> data traverse the stack? I also didn't understand why make it dependent
> on the socket.

OK, sure. One case I could think of is with an OVS internal port in
another namespace, directly attached to the bridge. I'll have a play
around with WARN_ON and see if I can come up with something more
trimmed down.
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