ipv6: introduce dst_rt6_info() helper

Instead of (struct rt6_info *)dst casts, we can use :

 #define dst_rt6_info(_ptr) \
         container_of_const(_ptr, struct rt6_info, dst)

Some places needed missing const qualifiers :

ip6_confirm_neigh(), ipv6_anycast_destination(),
ipv6_unicast_destination(), has_gateway()

v2: added missing parts (David Ahern)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 12 insertions, 16 deletions

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 39b5fd6bbf65..6e8b9d100ad2 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -180,7 +180,7 @@ static inline bool crosses_local_route_boundary(int skb_af, struct sk_buff *skb,
 			(!skb->dev || skb->dev->flags & IFF_LOOPBACK) &&
 			(addr_type & IPV6_ADDR_LOOPBACK);
 		old_rt_is_local = __ip_vs_is_local_route6(
-			(struct rt6_info *)skb_dst(skb));
+			dst_rt6_info(skb_dst(skb)));
 	} else
 #endif
 	{
@@ -481,7 +481,7 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 	if (dest) {
 		dest_dst = __ip_vs_dst_check(dest);
 		if (likely(dest_dst))
-			rt = (struct rt6_info *) dest_dst->dst_cache;
+			rt = dst_rt6_info(dest_dst->dst_cache);
 		else {
 			u32 cookie;
 
@@ -501,7 +501,7 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 				ip_vs_dest_dst_free(dest_dst);
 				goto err_unreach;
 			}
-			rt = (struct rt6_info *) dst;
+			rt = dst_rt6_info(dst);
 			cookie = rt6_get_cookie(rt);
 			__ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
 			spin_unlock_bh(&dest->dst_lock);
@@ -517,7 +517,7 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 					      rt_mode);
 		if (!dst)
 			goto err_unreach;
-		rt = (struct rt6_info *) dst;
+		rt = dst_rt6_info(dst);
 	}
 
 	local = __ip_vs_is_local_route6(rt);
@@ -862,7 +862,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 				      IP_VS_RT_MODE_RDR);
 	if (local < 0)
 		goto tx_error;
-	rt = (struct rt6_info *) skb_dst(skb);
+	rt = dst_rt6_info(skb_dst(skb));
 	/*
 	 * Avoid duplicate tuple in reply direction for NAT traffic
 	 * to local address when connection is sync-ed
@@ -1288,7 +1288,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 	if (local)
 		return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1);
 
-	rt = (struct rt6_info *) skb_dst(skb);
+	rt = dst_rt6_info(skb_dst(skb));
 	tdev = rt->dst.dev;
 
 	/*
@@ -1590,7 +1590,7 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 				      &cp->daddr.in6, NULL, ipvsh, 0, rt_mode);
 	if (local < 0)
 		goto tx_error;
-	rt = (struct rt6_info *) skb_dst(skb);
+	rt = dst_rt6_info(skb_dst(skb));
 	/*
 	 * Avoid duplicate tuple in reply direction for NAT traffic
 	 * to local address when connection is sync-ed
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index a0571339239c..5c1ff07eaee0 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -77,12 +77,8 @@ EXPORT_SYMBOL_GPL(flow_offload_alloc);
 
 static u32 flow_offload_dst_cookie(struct flow_offload_tuple *flow_tuple)
 {
-	const struct rt6_info *rt;
-
-	if (flow_tuple->l3proto == NFPROTO_IPV6) {
-		rt = (const struct rt6_info *)flow_tuple->dst_cache;
-		return rt6_get_cookie(rt);
-	}
+	if (flow_tuple->l3proto == NFPROTO_IPV6)
+		return rt6_get_cookie(dst_rt6_info(flow_tuple->dst_cache));
 
 	return 0;
 }
diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
index 5383bed3d3e0..100887beed31 100644
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -729,7 +729,7 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 		return NF_ACCEPT;
 
 	if (unlikely(tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM)) {
-		rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
+		rt = dst_rt6_info(tuplehash->tuple.dst_cache);
 		memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
 		IP6CB(skb)->iif = skb->dev->ifindex;
 		IP6CB(skb)->flags = IP6SKB_FORWARDED;
@@ -741,7 +741,7 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
 
 	switch (tuplehash->tuple.xmit_type) {
 	case FLOW_OFFLOAD_XMIT_NEIGH:
-		rt = (struct rt6_info *)tuplehash->tuple.dst_cache;
+		rt = dst_rt6_info(tuplehash->tuple.dst_cache);
 		outdev = rt->dst.dev;
 		skb->dev = outdev;
 		nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6);
diff --git a/net/netfilter/nft_rt.c b/net/netfilter/nft_rt.c
index 24d977138572..2434c624aafd 100644
--- a/net/netfilter/nft_rt.c
+++ b/net/netfilter/nft_rt.c
@@ -80,7 +80,7 @@ void nft_rt_get_eval(const struct nft_expr *expr,
 		if (nft_pf(pkt) != NFPROTO_IPV6)
 			goto err;
 
-		memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
+		memcpy(dest, rt6_nexthop(dst_rt6_info(dst),
 					 &ipv6_hdr(skb)->daddr),
 		       sizeof(struct in6_addr));
 		break;