netfilter: fix a few (harmless) sparse warnings

net/netfilter/nft_payload.c:187:18: warning: incorrect type in return expression (expected bool got restricted __sum16 [usertype] check)
net/netfilter/nft_exthdr.c:222:14: warning: cast to restricted __be32
net/netfilter/nft_rt.c:49:23: warning: incorrect type in assignment (different base types expected unsigned int got restricted __be32)
net/netfilter/nft_rt.c:70:25: warning: symbol 'nft_rt_policy' was not declared. Should it be static?
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_exthdr.c

@@ -388,7 +388,7 @@ nft_exthdr_select_ops(const struct nft_ctx *ctx,
 	if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG])
 		return ERR_PTR(-EOPNOTSUPP);
 
-	op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP]));
+	op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP]));
 	switch (op) {
 	case NFT_EXTHDR_OP_TCPOPT:
 		if (tb[NFTA_EXTHDR_SREG])

net/netfilter/nft_payload.c

@@ -184,7 +184,7 @@ static bool nft_payload_udp_checksum(struct sk_buff *skb, unsigned int thoff)
 	if (!uh)
 		return false;
 
-	return uh->check;
+	return (__force bool)uh->check;
 }
 
 static int nft_payload_l4csum_offset(const struct nft_pktinfo *pkt,

net/netfilter/nft_rt.c

@@ -82,8 +82,8 @@ static void nft_rt_get_eval(const struct nft_expr *expr,
 		if (nft_pf(pkt) != NFPROTO_IPV4)
 			goto err;
 
-		*dest = rt_nexthop((const struct rtable *)dst,
-				   ip_hdr(skb)->daddr);
+		*dest = (__force u32)rt_nexthop((const struct rtable *)dst,
+						ip_hdr(skb)->daddr);
 		break;
 	case NFT_RT_NEXTHOP6:
 		if (nft_pf(pkt) != NFPROTO_IPV6)
@@ -106,7 +106,7 @@ static void nft_rt_get_eval(const struct nft_expr *expr,
 	regs->verdict.code = NFT_BREAK;
 }
 
-const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
+static const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
 	[NFTA_RT_DREG]		= { .type = NLA_U32 },
 	[NFTA_RT_KEY]		= { .type = NLA_U32 },
 };