Subject: Re: [PATCH net] ipv6: Fix MLD Query message check

From: Sergei Shtylyov <[email-masked]>
Date: Tue, 24 Jun 2014 18:27:13 +0400

Hello.

On 06/24/2014 03:50 PM, Hangbin Liu wrote:

> Based on RFC3810 6.2, we also need to check the hop limit and router alert
> option besides source address.

> Signed-off-by: Hangbin Liu <[email-masked]>
> ---
>   net/ipv6/mcast.c | 14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)

> diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
> index 08b367c..fdf7455 100644
> --- a/net/ipv6/mcast.c
> +++ b/net/ipv6/mcast.c
> @@ -1301,8 +1301,18 @@ int igmp6_event_query(struct sk_buff *skb)
>   	len = ntohs(ipv6_hdr(skb)->payload_len) + sizeof(struct ipv6hdr);
>   	len -= skb_network_header_len(skb);
>
> -	/* Drop queries with not link local source */
> -	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
> +	/* RFC3810 6.2
> +	 * Upon reception of an MLD message that contains a Query, the node
> +	 * checks if the source address of the message is a valid link-local
> +	 * address, if the Hop Limit is set to 1, and if the Router Alert
> +	 * option is present in the Hop-By-Hop Options header of the IPv6
> +	 * packet.  If any of these checks fails, the packet is dropped.
> +	 */
> +	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL) ||
> +			ipv6_hdr(skb)->hop_limit != 1 ||
> +			ipv6_hdr(skb)->nexthdr != NEXTHDR_HOP ||
> +			!(IP6CB(skb)->flags & IP6SKB_ROUTERALERT) ||
> +			IP6CB(skb)->ra != htons(IPV6_OPT_ROUTERALERT_MLD))

    The continuation lines should start exactly under '!' on the broken up line.

WBR, Sergei