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

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Message-ID: <CANr6G5wRS1zg4oLdS5L4gM7iCS11BHb7+8uUN1fh5Oa9F4_BBw@mail.gmail.com>
Date:	Thu, 30 Jul 2015 16:16:49 -0700
From:	Joe Stringer <joestringer@...ira.com>
To:	Thomas Graf <tgraf@...g.ch>
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>,
	Hannes Sowa <hannes@...hat.com>
Subject: Re: [PATCH net-next 1/9] openvswitch: Scrub packet in ovs_vport_receive()

On 30 July 2015 at 11:40, Thomas Graf <tgraf@...g.ch> wrote:
> On 07/30/15 at 11:12am, Joe Stringer wrote:
>> Signed-off-by: Joe Stringer <joestringer@...ira.com>
>
> Can you write a few lines on why this is needed? I have flows which
> use the mark to communicate with netfilter through internal ports.

The problem I was seeing is when packets come from a different
namespace on the localhost, they still have conntrack data associated.
This doesn't make sense, so the intention is to perform nf_reset().
However, it seems like we should actually be doing a bit more - at
least the skb_dst_drop() and perhaps some of the other stuff in
skb_scrub_packet().

Do you want to retain the mark when transitioning between namespaces?

Perhaps something like the below incremental would be sufficient:

diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index 8a63df6..82844e6 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -475,7 +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)))
+       if (!skb->sk)
+               skb_scrub_packet(skb, false);
+       else if (sock_net(skb->sk) != read_pnet(&vport->dp->net))
                skb_scrub_packet(skb, true);

        stats = this_cpu_ptr(vport->percpu_stats);
--
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