[PATCH net V2] netfilter: Drop fragmented ndisc packets assembled in netfilter

[PATCH net V2] netfilter: Drop fragmented ndisc packets assembled in netfilter

[Georg Kohmann]

Fragmented ndisc packets assembled in netfilter not dropped as specified
in RFC 6980, section 5. This behaviour breaks TAHI IPv6 Core Conformance
Tests v6LC.2.1.22/23, V6LC.2.2.26/27 and V6LC.2.3.18.

Setting IP6SKB_FRAGMENTED flag during reassembly.

References: commit b800c3b966bc ("ipv6: drop fragmented ndisc packets by
default (RFC 6980)")
Signed-off-by: Georg Kohmann <geokohma@cisco.com>
---

V2: Fix spelling of IPSKB_FRAGMENTED to IP6SKB_FRAGMENTED in comment

 net/ipv6/netfilter/nf_conntrack_reasm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index fed9666..054d287 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -355,6 +355,7 @@ static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
 	ipv6_hdr(skb)->payload_len = htons(payload_len);
 	ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
 	IP6CB(skb)->frag_max_size = sizeof(struct ipv6hdr) + fq->q.max_size;
+	IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
 
 	/* Yes, and fold redundant checksum back. 8) */
 	if (skb->ip_summed == CHECKSUM_COMPLETE)
-- 
2.10.2

Re: [PATCH net V2] netfilter: Drop fragmented ndisc packets assembled in netfilter

[Pablo Neira Ayuso]

On Tue, Oct 13, 2020 at 02:23:12PM +0200, Georg Kohmann wrote:
> Fragmented ndisc packets assembled in netfilter not dropped as specified
> in RFC 6980, section 5. This behaviour breaks TAHI IPv6 Core Conformance
> Tests v6LC.2.1.22/23, V6LC.2.2.26/27 and V6LC.2.3.18.
> 
> Setting IP6SKB_FRAGMENTED flag during reassembly.

Applied, thanks.