netdev - Re: [PATCH v2 net] ipv6: Fix MLD Query message check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 26 Jun 2014 17:33:41 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	liuhangbin@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH v2 net] ipv6: Fix MLD Query message check

From: Hangbin Liu <liuhangbin@...il.com>
Date: Wed, 25 Jun 2014 09:31:07 +0800

> @@ -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))
>  		return -EINVAL;
>  

Does the NEXTHDR_HOP have the be exactly the next extension header
present?  I think you need to allow for more flexibility here.

In any event, the only way the IP6SKB_ROUTERALERT bit can be set
is if there were hop-by-hop options present, so testing only the
bit itself is sufficient.

The forwarding path simplifies the check in this way too.

So please adjust this to only check the bit and remove the NEXTHDR_HOP
test.

Thanks.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html