netfilter: nft_osf: check for TCP packet before further processing

[ Upstream commit 8f518d43f89ae00b9cf5460e10b91694944ca1a8 ]

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@netfilter.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index a003533ff4d93a5cc9eb7c8eef006a5dfcb3e3e5..e259454b6a643dbb7192c004e6d3eae4e94e1667 100644 (file)
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -22,6 +22,11 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
        struct tcphdr _tcph;
        const char *os_name;
 
+       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) {