netdev - Re: [PATCH net,v2] vrf: check forwarding on the original netdevice when generating ICMP dest unreachable

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Message-ID: <ac1ac1ce-b569-9c3a-366e-6f3609af5ade@gmail.com>
Date:   Wed, 28 Feb 2018 08:49:25 -0700
From:   David Ahern <dsahern@...il.com>
To:     Stephen Suryaputra <ssuryaextr@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net,v2] vrf: check forwarding on the original netdevice
 when generating ICMP dest unreachable

On 2/28/18 7:46 AM, Stephen Suryaputra wrote:
> When ip_error() is called the device is the l3mdev master instead of the
> original device. So the forwarding check should be on the original one.
> 
> Changes from v1:
> - Only need to reset the device on which __in_dev_get_rcu() is done (per
>   David Ahern).
> 
> Signed-off-by: Stephen Suryaputra <ssuryaextr@...il.com>
> ---
>  net/ipv4/route.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index a4f44d8..89c020f 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -930,19 +930,26 @@ void ip_rt_send_redirect(struct sk_buff *skb)
>  
>  static int ip_error(struct sk_buff *skb)
>  {
> -	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
>  	struct rtable *rt = skb_rtable(skb);
> +	struct net_device *dev = skb->dev;
> +	struct in_device *in_dev;
>  	struct inet_peer *peer;
>  	unsigned long now;
>  	struct net *net;
>  	bool send;
>  	int code;
>  
> +	net = dev_net(rt->dst.dev);
> +
> +	if (netif_is_l3_master(skb->dev))
> +		dev = __dev_get_by_index(net, IPCB(skb)->iif);

Do need to handle the device disappearing.
if (!dev)
	goto out;

> +
> +	in_dev = __in_dev_get_rcu(dev);
> +
>  	/* IP on this device is disabled. */
>  	if (!in_dev)
>  		goto out;
>  
> -	net = dev_net(rt->dst.dev);
>  	if (!IN_DEV_FORWARD(in_dev)) {
>  		switch (rt->dst.error) {
>  		case EHOSTUNREACH:
>