Merge branch 'mpls-build-fix'

Roopa Prabhu says:

====================
af_mpls: fix undefined reference to ip6_route_output with CONFIG_IPV6=n

This patch series uses ipv6_stub_impl.ipv6_dst_lookup instead of
ip6_route_output. Follows the vxlan drivers usage of
ipv6_stub_impl.ipv6_dst_lookup.

There is no sk in the af_mpls context from where
ipv6_stub_impl.ipv6_dst_lookup is used. sk appears to be needed
to get the namespace 'net' and is optional otherwise. This patch series
changes ipv6_stub_impl.ipv6_dst_lookup to take net argument. sk remains
optional.

v1 - v2: use IS_BUILTIN

v2 - v3: Use new Kconfig option that depends on (IPV6 || IPV6=n) as
	 suggested by Dave. Also uses IS_ERR as suggested by Thomas.

v3 - v4: Include missed case of (MPLS_ROUTING=y && IPV6=m) reported by
         Dave.

v4 - v5: Use ipv6_stub_impl.ipv6_dst_lookup as suggested by Hannes

v5 - v6: protect against null ipv6_stub by statically declaring
	 a ipv6_dst_lookup NOP func
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 59 insertions, 23 deletions

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 81f0f24b2cfb..beed5d4025a3 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2034,7 +2034,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		fl6.flowi6_mark = skb->mark;
 		fl6.flowi6_proto = IPPROTO_UDP;
 
-		if (ipv6_stub->ipv6_dst_lookup(sk, &ndst, &fl6)) {
+		if (ipv6_stub->ipv6_dst_lookup(vxlan->net, sk, &ndst, &fl6)) {
 			netdev_dbg(dev, "no route to %pI6\n",
 				   &dst->sin6.sin6_addr);
 			dev->stats.tx_carrier_errors++;
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index def59d3a34d5..0c3ac5acb85f 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -158,8 +158,8 @@ struct ipv6_stub {
 				 const struct in6_addr *addr);
 	int (*ipv6_sock_mc_drop)(struct sock *sk, int ifindex,
 				 const struct in6_addr *addr);
-	int (*ipv6_dst_lookup)(struct sock *sk, struct dst_entry **dst,
-				struct flowi6 *fl6);
+	int (*ipv6_dst_lookup)(struct net *net, struct sock *sk,
+			       struct dst_entry **dst, struct flowi6 *fl6);
 	void (*udpv6_encap_enable)(void);
 	void (*ndisc_send_na)(struct net_device *dev, struct neighbour *neigh,
 			      const struct in6_addr *daddr,
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 7c79798bcaab..eecdfc92f807 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -813,7 +813,8 @@ static inline struct sk_buff *ip6_finish_skb(struct sock *sk)
 			      &inet6_sk(sk)->cork);
 }
 
-int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi6 *fl6);
+int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
+		   struct flowi6 *fl6);
 struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
 				      const struct in6_addr *final_dst);
 struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c
index ca09bf49ac68..bfa941fc1165 100644
--- a/net/ipv6/addrconf_core.c
+++ b/net/ipv6/addrconf_core.c
@@ -107,7 +107,16 @@ int inet6addr_notifier_call_chain(unsigned long val, void *v)
 }
 EXPORT_SYMBOL(inet6addr_notifier_call_chain);
 
-const struct ipv6_stub *ipv6_stub __read_mostly;
+static int eafnosupport_ipv6_dst_lookup(struct net *net, struct sock *u1,
+					struct dst_entry **u2,
+					struct flowi6 *u3)
+{
+	return -EAFNOSUPPORT;
+}
+
+const struct ipv6_stub *ipv6_stub __read_mostly = &(struct ipv6_stub) {
+	.ipv6_dst_lookup = eafnosupport_ipv6_dst_lookup,
+};
 EXPORT_SYMBOL_GPL(ipv6_stub);
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 713d7434c911..6c2b2132c8d3 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -329,7 +329,7 @@ static struct dst_entry *icmpv6_route_lookup(struct net *net,
 	struct flowi6 fl2;
 	int err;
 
-	err = ip6_dst_lookup(sk, &dst, fl6);
+	err = ip6_dst_lookup(net, sk, &dst, fl6);
 	if (err)
 		return ERR_PTR(err);
 
@@ -361,7 +361,7 @@ static struct dst_entry *icmpv6_route_lookup(struct net *net,
 	if (err)
 		goto relookup_failed;
 
-	err = ip6_dst_lookup(sk, &dst2, &fl2);
+	err = ip6_dst_lookup(net, sk, &dst2, &fl2);
 	if (err)
 		goto relookup_failed;
 
@@ -591,7 +591,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
 	else if (!fl6.flowi6_oif)
 		fl6.flowi6_oif = np->ucast_oif;
 
-	err = ip6_dst_lookup(sk, &dst, &fl6);
+	err = ip6_dst_lookup(net, sk, &dst, &fl6);
 	if (err)
 		goto out;
 	dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index c5fc85286ef6..92b7cf0dc1f9 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -881,10 +881,9 @@ out:
 	return dst;
 }
 
-static int ip6_dst_lookup_tail(struct sock *sk,
+static int ip6_dst_lookup_tail(struct net *net, struct sock *sk,
 			       struct dst_entry **dst, struct flowi6 *fl6)
 {
-	struct net *net = sock_net(sk);
 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
 	struct neighbour *n;
 	struct rt6_info *rt;
@@ -994,10 +993,11 @@ out_err_release:
  *
  *	It returns zero on success, or a standard errno code on error.
  */
-int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi6 *fl6)
+int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
+		   struct flowi6 *fl6)
 {
 	*dst = NULL;
-	return ip6_dst_lookup_tail(sk, dst, fl6);
+	return ip6_dst_lookup_tail(net, sk, dst, fl6);
 }
 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
 
@@ -1018,7 +1018,7 @@ struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
 	struct dst_entry *dst = NULL;
 	int err;
 
-	err = ip6_dst_lookup_tail(sk, &dst, fl6);
+	err = ip6_dst_lookup_tail(sock_net(sk), sk, &dst, fl6);
 	if (err)
 		return ERR_PTR(err);
 	if (final_dst)
@@ -1052,7 +1052,7 @@ struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
 
 	dst = ip6_sk_dst_check(sk, dst, fl6);
 
-	err = ip6_dst_lookup_tail(sk, &dst, fl6);
+	err = ip6_dst_lookup_tail(sock_net(sk), sk, &dst, fl6);
 	if (err)
 		return ERR_PTR(err);
 	if (final_dst)
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 49f1b0e41bdf..88cfaa241c07 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -15,7 +15,10 @@
 #include <net/ip_fib.h>
 #include <net/netevent.h>
 #include <net/netns/generic.h>
-#include <net/ip6_route.h>
+#if IS_ENABLED(CONFIG_IPV6)
+#include <net/ipv6.h>
+#include <net/addrconf.h>
+#endif
 #include "internal.h"
 
 #define LABEL_NOT_SPECIFIED (1<<20)
@@ -331,6 +334,7 @@ static unsigned find_free_label(struct net *net)
 	return LABEL_NOT_SPECIFIED;
 }
 
+#if IS_ENABLED(CONFIG_INET)
 static struct net_device *inet_fib_lookup_dev(struct net *net, void *addr)
 {
 	struct net_device *dev = NULL;
@@ -347,30 +351,49 @@ static struct net_device *inet_fib_lookup_dev(struct net *net, void *addr)
 
 	ip_rt_put(rt);
 
-errout:
 	return dev;
+errout:
+	return ERR_PTR(-ENODEV);
+}
+#else
+static struct net_device *inet_fib_lookup_dev(struct net *net, void *addr)
+{
+	return ERR_PTR(-EAFNOSUPPORT);
 }
+#endif
 
+#if IS_ENABLED(CONFIG_IPV6)
 static struct net_device *inet6_fib_lookup_dev(struct net *net, void *addr)
 {
 	struct net_device *dev = NULL;
 	struct dst_entry *dst;
 	struct flowi6 fl6;
+	int err;
+
+	if (!ipv6_stub)
+		return ERR_PTR(-EAFNOSUPPORT);
 
 	memset(&fl6, 0, sizeof(fl6));
 	memcpy(&fl6.daddr, addr, sizeof(struct in6_addr));
-	dst = ip6_route_output(net, NULL, &fl6);
-	if (dst->error)
+	err = ipv6_stub->ipv6_dst_lookup(net, NULL, &dst, &fl6);
+	if (err)
 		goto errout;
 
 	dev = dst->dev;
 	dev_hold(dev);
-
-errout:
 	dst_release(dst);
 
 	return dev;
+
+errout:
+	return ERR_PTR(err);
 }
+#else
+static struct net_device *inet6_fib_lookup_dev(struct net *net, void *addr)
+{
+	return ERR_PTR(-EAFNOSUPPORT);
+}
+#endif
 
 static struct net_device *find_outdev(struct net *net,
 				      struct mpls_route_config *cfg)
@@ -425,10 +448,12 @@ static int mpls_route_add(struct mpls_route_config *cfg)
 	if (cfg->rc_output_labels > MAX_NEW_LABELS)
 		goto errout;
 
-	err = -ENODEV;
 	dev = find_outdev(net, cfg);
-	if (!dev)
+	if (IS_ERR(dev)) {
+		err = PTR_ERR(dev);
+		dev = NULL;
 		goto errout;
+	}
 
 	/* Ensure this is a supported device */
 	err = -EINVAL;
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index 66deebc66aa1..c170d3138953 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -194,7 +194,8 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 			.saddr = src->ipv6,
 			.flowi6_proto = IPPROTO_UDP
 		};
-		err = ipv6_stub->ipv6_dst_lookup(ub->ubsock->sk, &ndst, &fl6);
+		err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk, &ndst,
+						 &fl6);
 		if (err)
 			goto tx_error;
 		ttl = ip6_dst_hoplimit(ndst);