netfilter: nft_osf: restrict osf to ipv4, ipv6 and inet families

As it was originally intended, restrict extension to supported families.

Fixes: b96af92d ("netfilter: nf_tables: implement Passive OS fingerprint module in nft_osf")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_osf.c

@@ -115,9 +115,21 @@ static int nft_osf_validate(const struct nft_ctx *ctx,
 			    const struct nft_expr *expr,
 			    const struct nft_data **data)
 {
-	return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
+	unsigned int hooks;
+
+	switch (ctx->family) {
+	case NFPROTO_IPV4:
+	case NFPROTO_IPV6:
+	case NFPROTO_INET:
+		hooks = (1 << NF_INET_LOCAL_IN) |
 			(1 << NF_INET_PRE_ROUTING) |
-						    (1 << NF_INET_FORWARD));
+			(1 << NF_INET_FORWARD);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return nft_chain_validate_hooks(ctx->chain, hooks);
 }
 
 static bool nft_osf_reduce(struct nft_regs_track *track,