netdev - Re: [PATCH net,v2] vrf: check accept_source

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Date:   Sun, 31 Mar 2019 18:04:00 -0600
From:   David Ahern <dsahern@...il.com>
To:     Stephen Suryaputra <ssuryaextr@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net,v2] vrf: check accept_source_route on the original
 netdevice

On 3/27/19 1:58 PM, Stephen Suryaputra wrote:
> Configuration check to accept source route IP options should be made on
> the incoming netdevice when the skb->dev is an l3mdev master. The route
> lookup for the source route next hop also needs the incoming netdev.
> 
> Signed-off-by: Stephen Suryaputra <ssuryaextr@...il.com>
> ---
>  net/ipv4/ip_input.c   | 3 +++
>  net/ipv4/ip_options.c | 6 +++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
> index ecce2dc78f17..754176222ef6 100644
> --- a/net/ipv4/ip_input.c
> +++ b/net/ipv4/ip_input.c
> @@ -263,6 +263,9 @@ static inline bool ip_rcv_options(struct sk_buff *skb)
>  	const struct iphdr *iph;
>  	struct net_device *dev = skb->dev;
>  
> +	if (netif_is_l3_master(dev))
> +		dev = __dev_get_by_index(dev_net(dev), IPCB(skb)->iif);

ip_rcv_options is called from ip_rcv_finish_core which already has this
dev. Passing it as an arg saves the lookup. I believe you can always use
dev as the input argument vs skb->dev.

> +
>  	/* It looks as overkill, because not all
>  	   IP options require packet mangling.
>  	   But it is the easiest for now, especially taking
> diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
> index 32a35043c9f5..99f37591d7c1 100644
> --- a/net/ipv4/ip_options.c
> +++ b/net/ipv4/ip_options.c
> @@ -620,6 +620,7 @@ int ip_options_rcv_srr(struct sk_buff *skb)
>  	struct iphdr *iph = ip_hdr(skb);
>  	unsigned char *optptr = skb_network_header(skb) + opt->srr;
>  	struct rtable *rt = skb_rtable(skb);
> +	struct net_device *dev = skb->dev;
>  	struct rtable *rt2;
>  	unsigned long orefdst;
>  	int err;
> @@ -638,6 +639,9 @@ int ip_options_rcv_srr(struct sk_buff *skb)
>  	if (rt->rt_type != RTN_LOCAL)
>  		return -EINVAL;
>  
> +	if (netif_is_l3_master(dev))
> +		dev = __dev_get_by_index(dev_net(dev), IPCB(skb)->iif);

same here - just pass net_device from ip_rcv_options
> +
>  	for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
>  		if (srrptr + 3 > srrspace) {
>  			icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
> @@ -647,7 +651,7 @@ int ip_options_rcv_srr(struct sk_buff *skb)
>  
>  		orefdst = skb->_skb_refdst;
>  		skb_dst_set(skb, NULL);
> -		err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
> +		err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, dev);
>  		rt2 = skb_rtable(skb);
>  		if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
>  			skb_dst_drop(skb);
>