netdev - [PATCH net 3/8] netfilter: nft_osf: check for TCP packet before further processing

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Date:   Tue, 22 Jun 2021 23:59:56 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 3/8] netfilter: nft_osf: check for TCP packet before further processing

The osf expression only supports for TCP packets, add a upfront sanity
check to skip packet parsing if this is not a TCP packet.

Fixes: b96af92d6eaf ("netfilter: nf_tables: implement Passive OS fingerprint module in nft_osf")
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nft_osf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index ac61f708b82d..d82677e83400 100644
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -28,6 +28,11 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	struct nf_osf_data data;
 	struct tcphdr _tcph;
 
+	if (pkt->tprot != IPPROTO_TCP) {
+		regs->verdict.code = NFT_BREAK;
+		return;
+	}
+
 	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
 				 sizeof(struct tcphdr), &_tcph);
 	if (!tcp) {
-- 
2.30.2