Re: [PATCH v3 net] ipv6: Fix MLD Query message check

["YOSHIFUJI Hideaki/吉藤英明" <hideaki.yoshifuji@miraclelinux.com>]

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 <liuhangbin@gmail.com>

Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

> ---
>   net/ipv6/mcast.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
> index 08b367c..617f095 100644
> --- a/net/ipv6/mcast.c
> +++ b/net/ipv6/mcast.c
> @@ -1301,8 +1301,17 @@ 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 ||
> +	    !(IP6CB(skb)->flags & IP6SKB_ROUTERALERT) ||
> +	    IP6CB(skb)->ra != htons(IPV6_OPT_ROUTERALERT_MLD))
>   		return -EINVAL;
>   
>   	idev = __in6_dev_get(skb->dev);
> 

--yoshfuji