netdev - Re: [PATCH next v2 0/7] Introduce l3

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Date:	Sun, 13 Mar 2016 17:01:11 -0700
From:	Mahesh Bandewar <maheshb@...gle.com>
To:	Cong Wang <xiyou.wangcong@...il.com>
Cc:	Nicolas Dichtel <nicolas.dichtel@...nd.com>,
	Mahesh Bandewar <mahesh@...dewar.net>,
	David Miller <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	netdev <netdev@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Cong Wang <cwang@...pensource.com>
Subject: Re: [PATCH next v2 0/7] Introduce l3_dev pointer for L3 processing

>> If I understand correctly (and as Cong already said), information are
>> leaking
>> between netns during the input phase. On the tx side, skb_scrub_packet() is
>> called, but not on the rx side. I think it's wrong. There should be an
>> explicit
>> boundary.
>
> That is not what I am complaining about.
>
> I dislike the trick of switching skb->dev pointer with skb->dev->l3_dev.
> This is not how we switch netns, nor the way how netns works.
>
How it is different from what we are doing currently?

Current: Use skb->dev for L3 processing and derive netns from skb->dev
Proposal: use skb->dev->l3_dev for L3 processing and derive netns from
skb->dev->l3_dev

> Look at veth pair or dev_change_net_namespace(), each time when we
> switch netns, we need to do a full reregistration or a full reentrance, we
> never just switch some pointers to switch netns. This is why I said it breaks
> isolation.
>
> Also, it is ugly to hide such a ipvlan-specific pointer for half of the RX code
> path.
I think I have already mentioned, I'm adding RX code now and later
I'll add TX code to use
l3_dev to make it symmetric. This way all L3 (Tx/Rx) will use this
device reference
always.