Re: [PATCH] Do not drop DNATed 6to4/6rd packets

[Joe Perches <joe@perches.com>]

On Sun, 2013-09-22 at 13:58 +0300, Catalin(ux) M. BOIE wrote:
> From: "Catalin(ux) M. BOIE" <catab@embedromix.ro>
> 
> When a router is doing  DNAT for 6to4/6rd packets the latest anti-spoofing
> patch (218774dc) will drop them because the IPv6 address embedded
> does not match the IPv4 destination. This patch will allow them to
> pass by testing if we have an address that matches on 6to4/6rd interface.
> I have been hit by this problem using Fedora and IPV6TO4_IPV4ADDR.
> Also, log the dropped packets (with rate limit).

Thanks.  trivial nits which maybe fixed later:

> diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
[]
> +/* Returns true if a packet is spoofed
> + */

probably nicer as single line /* Returns true ... */

> +static bool packet_is_spoofed(struct sk_buff *skb,
> +			      const struct iphdr *iph,
> +			      struct ip_tunnel *tunnel)
> +{
> +	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
> +
> +	if (tunnel->dev->priv_flags & IFF_ISATAP) {
> +		if (!isatap_chksrc(skb, iph, tunnel))
> +			return true;
> +
> +		return false;
> +	}
> +
> +	if ((tunnel->dev->flags&IFF_POINTOPOINT))

It'd be nicer with spaces around the &

> +		return false;

It'd be slightly faster code moving the ipv6_hdr(skb)
assignment below these tests.