netdev - RE: [PATCH net v2] net: bridge: Fix ethernet header pointer before check skb forwardable

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Date:   Wed, 16 Jan 2019 09:09:43 +0000
From:   wangyunjian <wangyunjian@...wei.com>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     xudingke <xudingke@...wei.com>,
        "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>,
        Nkolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>
Subject: RE: [PATCH net v2] net: bridge: Fix ethernet header pointer before
 check skb forwardable



> -----Original Message-----
> From: Sergei Shtylyov [mailto:sergei.shtylyov@...entembedded.com]
> Sent: Tuesday, January 15, 2019 5:22 PM
> To: wangyunjian <wangyunjian@...wei.com>; netdev@...r.kernel.org
> Cc: xudingke <xudingke@...wei.com>; bridge@...ts.linux-foundation.org;
> Nkolay Aleksandrov <nikolay@...ulusnetworks.com>; Roopa Prabhu
> <roopa@...ulusnetworks.com>
> Subject: Re: [PATCH net v2] net: bridge: Fix ethernet header pointer before
> check skb forwardable
> 
> On 15.01.2019 6:12, wangyunjian wrote:
> 
> > From: Yunjian Wang <wangyunjian@...wei.com>
> >
> > The skb header should be set to ethernet header before using
> > is_skb_forwardable. Because the ethernet header length has been
> > considered in is_skb_forwardable(including dev->hard_header_len
> > length).
> >
> > To reproduce the issue:
> > 1, add 2 ports on linux bridge br using following commands:
> > $ brctl addbr br
> > $ brctl addif br eth0
> > $ brctl addif br eth1
> > 2, the mtu of eth0 and eth1 is 1500
> > 3, send a 1504 packet from eth0 to eth1
> >
> > So the expect result is packet larger than 1500 cannot pass through
> > eth0 and eth1. But currently, the packet passes through success, it
> > means eth1's mtu limit donen't take effect.
> 
>     Doesn't. And MTU.

Thanks, I will fix them and send a new patch later.

Best regards,
	Yunjian
> 
> > Fixes: f6367b4660dd ("bridge: use is_skb_forwardable in forward path")
> > Cc: bridge@...ts.linux-foundation.org
> > Cc: Nkolay Aleksandrov <nikolay@...ulusnetworks.com>
> > Cc: Roopa Prabhu <roopa@...ulusnetworks.com>
> > Signed-off-by: Yunjian Wang <wangyunjian@...wei.com>
> [...]
> 
> MBR, Sergei