Re: [PATCH] Netfilter: Fix an ICMPv6 bug which caused by a latter ICMPv6 NA packet to inherit the mark of previous NS packet.

From: Florian Westphal
Date: Fri Oct 21 2016 - 05:02:16 EST


XU Tianwen <evan.xu.tianwen@xxxxxxxxx> wrote:
> The root cause is an ICMPv6 packet hits an untracked connection and inherits a mark from the previous packet to which it is not related, IMO it doesn't make sense to inherit mark for nf_conntrack_untracked.
>
> Signed-off-by: XU Tianwen <evan.xu.tianwen@xxxxxxxxx>
> ---
> net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
> index f5a61bc..1be9000 100644
> --- a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
> +++ b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
> @@ -223,6 +223,9 @@ icmpv6_error(struct net *net, struct nf_conn *tmpl,
> if (type >= 0 && type < sizeof(noct_valid_new) &&
> noct_valid_new[type]) {
> skb->nfct = &nf_ct_untracked_get()->ct_general;
> +#ifdef CONFIG_NF_CONNTRACK_MARK
> + ((struct nf_conn *)skb->nfct)->mark = 0;
> +#endif
> skb->nfctinfo = IP_CT_NEW;
> nf_conntrack_get(skb->nfct);
> return NF_ACCEPT;
> --
> 2.1.2

Where does that bogus mark come from in first place?
Untracked mark should always be 0.

Maybe we need this instead?

diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c
--- a/net/netfilter/xt_connmark.c
+++ b/net/netfilter/xt_connmark.c
@@ -44,7 +44,7 @@ connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
u_int32_t newmark;

ct = nf_ct_get(skb, &ctinfo);
- if (ct == NULL)
+ if (ct == NULL || nf_ct_is_untracked(ct))
return XT_CONTINUE;