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>

11 files changed, 40 insertions, 45 deletions

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 1635da07285f..d285c1f6f1a6 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -212,7 +212,7 @@ static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
 	} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
 		res = true;
 	} else {
-		struct rt6_info *rt = (struct rt6_info *)dst;
+		struct rt6_info *rt = dst_rt6_info(dst);
 		int tmo = net->ipv6.sysctl.icmpv6_time;
 		struct inet_peer *peer;
 
@@ -241,7 +241,7 @@ static bool icmpv6_rt_has_prefsrc(struct sock *sk, u8 type,
 
 	dst = ip6_route_output(net, sk, fl6);
 	if (!dst->error) {
-		struct rt6_info *rt = (struct rt6_info *)dst;
+		struct rt6_info *rt = dst_rt6_info(dst);
 		struct in6_addr prefsrc;
 
 		rt6_get_prefsrc(rt, &prefsrc);
@@ -616,7 +616,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
 	if (ip6_append_data(sk, icmpv6_getfrag, &msg,
 			    len + sizeof(struct icmp6hdr),
 			    sizeof(struct icmp6hdr),
-			    &ipc6, &fl6, (struct rt6_info *)dst,
+			    &ipc6, &fl6, dst_rt6_info(dst),
 			    MSG_DONTWAIT)) {
 		ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
 		ip6_flush_pending_frames(sk);
@@ -803,7 +803,7 @@ static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb)
 	if (ip6_append_data(sk, icmpv6_getfrag, &msg,
 			    skb->len + sizeof(struct icmp6hdr),
 			    sizeof(struct icmp6hdr), &ipc6, &fl6,
-			    (struct rt6_info *)dst, MSG_DONTWAIT)) {
+			    dst_rt6_info(dst), MSG_DONTWAIT)) {
 		__ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
 		ip6_flush_pending_frames(sk);
 	} else {
diff --git a/net/ipv6/ila/ila_lwt.c b/net/ipv6/ila/ila_lwt.c
index 8c1ce78956ba..0601bad79822 100644
--- a/net/ipv6/ila/ila_lwt.c
+++ b/net/ipv6/ila/ila_lwt.c
@@ -38,7 +38,7 @@ static inline struct ila_params *ila_params_lwtunnel(
 static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct dst_entry *orig_dst = skb_dst(skb);
-	struct rt6_info *rt = (struct rt6_info *)orig_dst;
+	struct rt6_info *rt = dst_rt6_info(orig_dst);
 	struct ila_lwt *ilwt = ila_lwt_lwtunnel(orig_dst->lwtstate);
 	struct dst_entry *dst;
 	int err = -EINVAL;
@@ -70,7 +70,7 @@ static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 		memset(&fl6, 0, sizeof(fl6));
 		fl6.flowi6_oif = orig_dst->dev->ifindex;
 		fl6.flowi6_iif = LOOPBACK_IFINDEX;
-		fl6.daddr = *rt6_nexthop((struct rt6_info *)orig_dst,
+		fl6.daddr = *rt6_nexthop(dst_rt6_info(orig_dst),
 					 &ip6h->daddr);
 
 		dst = ip6_route_output(net, NULL, &fl6);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index b9dd3a66e423..8f906e9fbc38 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -120,7 +120,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
 
 	rcu_read_lock();
-	nexthop = rt6_nexthop((struct rt6_info *)dst, daddr);
+	nexthop = rt6_nexthop(dst_rt6_info(dst), daddr);
 	neigh = __ipv6_neigh_lookup_noref(dev, nexthop);
 
 	if (unlikely(IS_ERR_OR_NULL(neigh))) {
@@ -599,7 +599,7 @@ int ip6_forward(struct sk_buff *skb)
 		 *	send a redirect.
 		 */
 
-		rt = (struct rt6_info *) dst;
+		rt = dst_rt6_info(dst);
 		if (rt->rt6i_flags & RTF_GATEWAY)
 			target = &rt->rt6i_gateway;
 		else
@@ -856,7 +856,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		 int (*output)(struct net *, struct sock *, struct sk_buff *))
 {
 	struct sk_buff *frag;
-	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	struct rt6_info *rt = dst_rt6_info(skb_dst(skb));
 	struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
 				inet6_sk(skb->sk) : NULL;
 	bool mono_delivery_time = skb->mono_delivery_time;
@@ -1063,7 +1063,7 @@ static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
 		return NULL;
 	}
 
-	rt = (struct rt6_info *)dst;
+	rt = dst_rt6_info(dst);
 	/* Yes, checking route validity in not connected
 	 * case is not very simple. Take into account,
 	 * that we do not support routing by source, TOS,
@@ -1118,7 +1118,7 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 		struct rt6_info *rt;
 
 		*dst = ip6_route_output(net, sk, fl6);
-		rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
+		rt = (*dst)->error ? NULL : dst_rt6_info(*dst);
 
 		rcu_read_lock();
 		from = rt ? rcu_dereference(rt->from) : NULL;
@@ -1159,7 +1159,7 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 	 * dst entry and replace it instead with the
 	 * dst entry of the nexthop router
 	 */
-	rt = (struct rt6_info *) *dst;
+	rt = dst_rt6_info(*dst);
 	rcu_read_lock();
 	n = __ipv6_neigh_lookup_noref(rt->dst.dev,
 				      rt6_nexthop(rt, &fl6->daddr));
@@ -1423,7 +1423,7 @@ static int __ip6_append_data(struct sock *sk,
 	int offset = 0;
 	bool zc = false;
 	u32 tskey = 0;
-	struct rt6_info *rt = (struct rt6_info *)cork->dst;
+	struct rt6_info *rt = dst_rt6_info(cork->dst);
 	bool paged, hold_tskey, extra_uref = false;
 	struct ipv6_txoptions *opt = v6_cork->opt;
 	int csummode = CHECKSUM_NONE;
@@ -1877,7 +1877,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 	struct net *net = sock_net(sk);
 	struct ipv6hdr *hdr;
 	struct ipv6_txoptions *opt = v6_cork->opt;
-	struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
+	struct rt6_info *rt = dst_rt6_info(cork->base.dst);
 	struct flowi6 *fl6 = &cork->fl.u.ip6;
 	unsigned char proto = fl6->flowi6_proto;
 
@@ -1949,7 +1949,7 @@ out:
 int ip6_send_skb(struct sk_buff *skb)
 {
 	struct net *net = sock_net(skb->sk);
-	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	struct rt6_info *rt = dst_rt6_info(skb_dst(skb));
 	int err;
 
 	err = ip6_local_out(net, skb->sk, skb);
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index cb0ee81a068a..dd342e6ecf3f 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -2273,7 +2273,7 @@ int ip6mr_get_route(struct net *net, struct sk_buff *skb, struct rtmsg *rtm,
 	int err;
 	struct mr_table *mrt;
 	struct mfc6_cache *cache;
-	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	struct rt6_info *rt = dst_rt6_info(skb_dst(skb));
 
 	mrt = ip6mr_get_table(net, RT6_TABLE_DFLT);
 	if (!mrt)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index ae134634c323..d914b23256ce 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1722,7 +1722,7 @@ void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)
 	if (IS_ERR(dst))
 		return;
 
-	rt = (struct rt6_info *) dst;
+	rt = dst_rt6_info(dst);
 
 	if (rt->rt6i_flags & RTF_GATEWAY) {
 		ND_PRINTK(2, warn,
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index ef2059c88955..88b3fcacd4f9 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -154,7 +154,7 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	dst = ip6_sk_dst_lookup_flow(sk, &fl6, daddr, false);
 	if (IS_ERR(dst))
 		return PTR_ERR(dst);
-	rt = (struct rt6_info *) dst;
+	rt = dst_rt6_info(dst);
 
 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 		fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 0d896ca7b589..2eedf255600b 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -598,7 +598,7 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
 	struct ipv6hdr *iph;
 	struct sk_buff *skb;
 	int err;
-	struct rt6_info *rt = (struct rt6_info *)*dstp;
+	struct rt6_info *rt = dst_rt6_info(*dstp);
 	int hlen = LL_RESERVED_SPACE(rt->dst.dev);
 	int tlen = rt->dst.dev->needed_tailroom;
 
@@ -917,7 +917,7 @@ back_from_confirm:
 		ipc6.opt = opt;
 		lock_sock(sk);
 		err = ip6_append_data(sk, raw6_getfrag, &rfv,
-			len, 0, &ipc6, &fl6, (struct rt6_info *)dst,
+			len, 0, &ipc6, &fl6, dst_rt6_info(dst),
 			msg->msg_flags);
 
 		if (err)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1f4b935a0e57..3e0b2cb20fd2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -226,7 +226,7 @@ static struct neighbour *ip6_dst_neigh_lookup(const struct dst_entry *dst,
 					      struct sk_buff *skb,
 					      const void *daddr)
 {
-	const struct rt6_info *rt = container_of(dst, struct rt6_info, dst);
+	const struct rt6_info *rt = dst_rt6_info(dst);
 
 	return ip6_neigh_lookup(rt6_nexthop(rt, &in6addr_any),
 				dst->dev, skb, daddr);
@@ -234,8 +234,8 @@ static struct neighbour *ip6_dst_neigh_lookup(const struct dst_entry *dst,
 
 static void ip6_confirm_neigh(const struct dst_entry *dst, const void *daddr)
 {
+	const struct rt6_info *rt = dst_rt6_info(dst);
 	struct net_device *dev = dst->dev;
-	struct rt6_info *rt = (struct rt6_info *)dst;
 
 	daddr = choose_neigh_daddr(rt6_nexthop(rt, &in6addr_any), NULL, daddr);
 	if (!daddr)
@@ -354,7 +354,7 @@ EXPORT_SYMBOL(ip6_dst_alloc);
 
 static void ip6_dst_destroy(struct dst_entry *dst)
 {
-	struct rt6_info *rt = (struct rt6_info *)dst;
+	struct rt6_info *rt = dst_rt6_info(dst);
 	struct fib6_info *from;
 	struct inet6_dev *idev;
 
@@ -373,7 +373,7 @@ static void ip6_dst_destroy(struct dst_entry *dst)
 
 static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev)
 {
-	struct rt6_info *rt = (struct rt6_info *)dst;
+	struct rt6_info *rt = dst_rt6_info(dst);
 	struct inet6_dev *idev = rt->rt6i_idev;
 
 	if (idev && idev->dev != blackhole_netdev) {
@@ -1288,7 +1288,7 @@ struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
 
 	dst = fib6_rule_lookup(net, &fl6, skb, flags, ip6_pol_route_lookup);
 	if (dst->error == 0)
-		return (struct rt6_info *) dst;
+		return dst_rt6_info(dst);
 
 	dst_release(dst);
 
@@ -2647,7 +2647,7 @@ struct dst_entry *ip6_route_output_flags(struct net *net,
 
 	rcu_read_lock();
 	dst = ip6_route_output_flags_noref(net, sk, fl6, flags);
-	rt6 = (struct rt6_info *)dst;
+	rt6 = dst_rt6_info(dst);
 	/* For dst cached in uncached_list, refcnt is already taken. */
 	if (list_empty(&rt6->dst.rt_uncached) && !dst_hold_safe(dst)) {
 		dst = &net->ipv6.ip6_null_entry->dst;
@@ -2661,7 +2661,7 @@ EXPORT_SYMBOL_GPL(ip6_route_output_flags);
 
 struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)
 {
-	struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;
+	struct rt6_info *rt, *ort = dst_rt6_info(dst_orig);
 	struct net_device *loopback_dev = net->loopback_dev;
 	struct dst_entry *new = NULL;
 
@@ -2744,7 +2744,7 @@ INDIRECT_CALLABLE_SCOPE struct dst_entry *ip6_dst_check(struct dst_entry *dst,
 	struct fib6_info *from;
 	struct rt6_info *rt;
 
-	rt = container_of(dst, struct rt6_info, dst);
+	rt = dst_rt6_info(dst);
 
 	if (rt->sernum)
 		return rt6_is_valid(rt) ? dst : NULL;
@@ -2772,7 +2772,7 @@ EXPORT_INDIRECT_CALLABLE(ip6_dst_check);
 
 static struct dst_entry *ip6_negative_advice(struct dst_entry *dst)
 {
-	struct rt6_info *rt = (struct rt6_info *) dst;
+	struct rt6_info *rt = dst_rt6_info(dst);
 
 	if (rt) {
 		if (rt->rt6i_flags & RTF_CACHE) {
@@ -2796,7 +2796,7 @@ static void ip6_link_failure(struct sk_buff *skb)
 
 	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);
 
-	rt = (struct rt6_info *) skb_dst(skb);
+	rt = dst_rt6_info(skb_dst(skb));
 	if (rt) {
 		rcu_read_lock();
 		if (rt->rt6i_flags & RTF_CACHE) {
@@ -2852,7 +2852,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
 				 bool confirm_neigh)
 {
 	const struct in6_addr *daddr, *saddr;
-	struct rt6_info *rt6 = (struct rt6_info *)dst;
+	struct rt6_info *rt6 = dst_rt6_info(dst);
 
 	/* Note: do *NOT* check dst_metric_locked(dst, RTAX_MTU)
 	 * IPv6 pmtu discovery isn't optional, so 'mtu lock' cannot disable it.
@@ -4174,7 +4174,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 		}
 	}
 
-	rt = (struct rt6_info *) dst;
+	rt = dst_rt6_info(dst);
 	if (rt->rt6i_flags & RTF_REJECT) {
 		net_dbg_ratelimited("rt6_redirect: source isn't a valid nexthop for redirect target\n");
 		return;
@@ -5608,7 +5608,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			 int iif, int type, u32 portid, u32 seq,
 			 unsigned int flags)
 {
-	struct rt6_info *rt6 = (struct rt6_info *)dst;
+	struct rt6_info *rt6 = dst_rt6_info(dst);
 	struct rt6key *rt6_dst, *rt6_src;
 	u32 *pmetrics, table, rt6_flags;
 	unsigned char nh_flags = 0;
@@ -6111,7 +6111,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	}
 
 
-	rt = container_of(dst, struct rt6_info, dst);
+	rt = dst_rt6_info(dst);
 	if (rt->dst.error) {
 		err = rt->dst.error;
 		ip6_rt_put(rt);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 77958adf2e16..37201c4fb393 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -97,11 +97,9 @@ static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
 	struct dst_entry *dst = skb_dst(skb);
 
 	if (dst && dst_hold_safe(dst)) {
-		const struct rt6_info *rt = (const struct rt6_info *)dst;
-
 		rcu_assign_pointer(sk->sk_rx_dst, dst);
 		sk->sk_rx_dst_ifindex = skb->skb_iif;
-		sk->sk_rx_dst_cookie = rt6_get_cookie(rt);
+		sk->sk_rx_dst_cookie = rt6_get_cookie(dst_rt6_info(dst));
 	}
 }
 
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 085ee236d9a1..674eadfae569 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -910,11 +910,8 @@ start_lookup:
 
 static void udp6_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
 {
-	if (udp_sk_rx_dst_set(sk, dst)) {
-		const struct rt6_info *rt = (const struct rt6_info *)dst;
-
-		sk->sk_rx_dst_cookie = rt6_get_cookie(rt);
-	}
+	if (udp_sk_rx_dst_set(sk, dst))
+		sk->sk_rx_dst_cookie = rt6_get_cookie(dst_rt6_info(dst));
 }
 
 /* wrapper for udp_queue_rcv_skb tacking care of csum conversion and
@@ -1585,7 +1582,7 @@ back_from_confirm:
 
 		skb = ip6_make_skb(sk, getfrag, msg, ulen,
 				   sizeof(struct udphdr), &ipc6,
-				   (struct rt6_info *)dst,
+				   dst_rt6_info(dst),
 				   msg->msg_flags, &cork);
 		err = PTR_ERR(skb);
 		if (!IS_ERR_OR_NULL(skb))
@@ -1612,7 +1609,7 @@ do_append_data:
 		ipc6.dontfrag = inet6_test_bit(DONTFRAG, sk);
 	up->len += ulen;
 	err = ip6_append_data(sk, getfrag, msg, ulen, sizeof(struct udphdr),
-			      &ipc6, fl6, (struct rt6_info *)dst,
+			      &ipc6, fl6, dst_rt6_info(dst),
 			      corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
 	if (err)
 		udp_v6_flush_pending_frames(sk);
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 4891012b692f..7924e08ee142 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -70,7 +70,7 @@ static int xfrm6_get_saddr(struct net *net, int oif,
 static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 			  const struct flowi *fl)
 {
-	struct rt6_info *rt = (struct rt6_info *)xdst->route;
+	struct rt6_info *rt = dst_rt6_info(xdst->route);
 
 	xdst->u.dst.dev = dev;
 	netdev_hold(dev, &xdst->u.dst.dev_tracker, GFP_ATOMIC);