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

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index ac61f70..d82677e 100644 (file)
--- 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) {