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

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Message-Id: <20201013122312.8761-1-geokohma@cisco.com>
Date:   Tue, 13 Oct 2020 14:23:12 +0200
From:   Georg Kohmann <geokohma@...co.com>
To:     netdev@...r.kernel.org
Cc:     netfilter-devel@...r.kernel.org, pablo@...filter.org,
        kadlec@...filter.org, fw@...len.de, davem@...emloft.net,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org, kuba@...nel.org,
        Georg Kohmann <geokohma@...co.com>
Subject: [PATCH net V2] netfilter: Drop fragmented ndisc packets assembled in netfilter

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@...co.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