net: split rt_genid for ipv4 and ipv6

Current net name space has only one genid for both IPv4 and IPv6, it has below
drawbacks:

- Add/delete an IPv4 address will invalidate all IPv6 routing table entries.
- Insert/remove XFRM policy will also invalidate both IPv4/IPv6 routing table
  entries even when the policy is only applied for one address family.

Thus, this patch attempt to split one genid for two to cater for IPv4 and IPv6
separately in a fine granularity.

Signed-off-by: Fan Du <fan.du@windriver.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 84e37b1..1313456 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -119,7 +119,6 @@
 	struct netns_ipvs	*ipvs;
 #endif
 	struct sock		*diag_nlsk;
-	atomic_t		rt_genid;
 	atomic_t		fnhe_genid;
 };
 
@@ -333,14 +332,42 @@
 }
 #endif
 
-static inline int rt_genid(struct net *net)
+static inline int rt_genid_ipv4(struct net *net)
 {
-	return atomic_read(&net->rt_genid);
+	return atomic_read(&net->ipv4.rt_genid);
 }
 
-static inline void rt_genid_bump(struct net *net)
+static inline void rt_genid_bump_ipv4(struct net *net)
 {
-	atomic_inc(&net->rt_genid);
+	atomic_inc(&net->ipv4.rt_genid);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static inline int rt_genid_ipv6(struct net *net)
+{
+	return atomic_read(&net->ipv6.rt_genid);
+}
+
+static inline void rt_genid_bump_ipv6(struct net *net)
+{
+	atomic_inc(&net->ipv6.rt_genid);
+}
+#else
+static inline int rt_genid_ipv6(struct net *net)
+{
+	return 0;
+}
+
+static inline void rt_genid_bump_ipv6(struct net *net)
+{
+}
+#endif
+
+/* For callers who don't really care about whether it's IPv4 or IPv6 */
+static inline void rt_genid_bump_all(struct net *net)
+{
+	rt_genid_bump_ipv4(net);
+	rt_genid_bump_ipv6(net);
 }
 
 static inline int fnhe_genid(struct net *net)
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 2ba9de8..bf2ec22 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -77,5 +77,6 @@
 	struct fib_rules_ops	*mr_rules_ops;
 #endif
 #endif
+	atomic_t	rt_genid;
 };
 #endif
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 005e2c2..0fb2401 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -72,6 +72,7 @@
 #endif
 #endif
 	atomic_t		dev_addr_genid;
+	atomic_t		rt_genid;
 };
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a9a54a2..e805481 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -435,12 +435,12 @@
 
 static inline bool rt_is_expired(const struct rtable *rth)
 {
-	return rth->rt_genid != rt_genid(dev_net(rth->dst.dev));
+	return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
 }
 
 void rt_cache_flush(struct net *net)
 {
-	rt_genid_bump(net);
+	rt_genid_bump_ipv4(net);
 }
 
 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
@@ -1458,7 +1458,7 @@
 #endif
 	rth->dst.output = ip_rt_bug;
 
-	rth->rt_genid	= rt_genid(dev_net(dev));
+	rth->rt_genid	= rt_genid_ipv4(dev_net(dev));
 	rth->rt_flags	= RTCF_MULTICAST;
 	rth->rt_type	= RTN_MULTICAST;
 	rth->rt_is_input= 1;
@@ -1589,7 +1589,7 @@
 		goto cleanup;
 	}
 
-	rth->rt_genid = rt_genid(dev_net(rth->dst.dev));
+	rth->rt_genid = rt_genid_ipv4(dev_net(rth->dst.dev));
 	rth->rt_flags = flags;
 	rth->rt_type = res->type;
 	rth->rt_is_input = 1;
@@ -1760,7 +1760,7 @@
 	rth->dst.tclassid = itag;
 #endif
 
-	rth->rt_genid = rt_genid(net);
+	rth->rt_genid = rt_genid_ipv4(net);
 	rth->rt_flags 	= flags|RTCF_LOCAL;
 	rth->rt_type	= res.type;
 	rth->rt_is_input = 1;
@@ -1945,7 +1945,7 @@
 
 	rth->dst.output = ip_output;
 
-	rth->rt_genid = rt_genid(dev_net(dev_out));
+	rth->rt_genid = rt_genid_ipv4(dev_net(dev_out));
 	rth->rt_flags	= flags;
 	rth->rt_type	= type;
 	rth->rt_is_input = 0;
@@ -2227,7 +2227,7 @@
 		rt->rt_iif = ort->rt_iif;
 		rt->rt_pmtu = ort->rt_pmtu;
 
-		rt->rt_genid = rt_genid(net);
+		rt->rt_genid = rt_genid_ipv4(net);
 		rt->rt_flags = ort->rt_flags;
 		rt->rt_type = ort->rt_type;
 		rt->rt_gateway = ort->rt_gateway;
@@ -2665,7 +2665,7 @@
 
 static __net_init int rt_genid_init(struct net *net)
 {
-	atomic_set(&net->rt_genid, 0);
+	atomic_set(&net->ipv4.rt_genid, 0);
 	atomic_set(&net->fnhe_genid, 0);
 	get_random_bytes(&net->ipv4.dev_addr_genid,
 			 sizeof(net->ipv4.dev_addr_genid));
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index a5ac969..0d1a9b1 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -766,6 +766,7 @@
 
 	net->ipv6.sysctl.bindv6only = 0;
 	net->ipv6.sysctl.icmpv6_time = 1*HZ;
+	atomic_set(&net->ipv6.rt_genid, 0);
 
 	err = ipv6_init_mibs(net);
 	if (err)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 74ab1f7..ce96163 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -283,7 +283,7 @@
 
 		memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
 		rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers);
-		rt->rt6i_genid = rt_genid(net);
+		rt->rt6i_genid = rt_genid_ipv6(net);
 		INIT_LIST_HEAD(&rt->rt6i_siblings);
 	}
 	return rt;
@@ -1061,7 +1061,7 @@
 	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
 	 * into this function always.
 	 */
-	if (rt->rt6i_genid != rt_genid(dev_net(rt->dst.dev)))
+	if (rt->rt6i_genid != rt_genid_ipv6(dev_net(rt->dst.dev)))
 		return NULL;
 
 	if (rt->rt6i_node && (rt->rt6i_node->fn_sernum == cookie))
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index e52cab3..d8da6b8 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -660,7 +660,13 @@
 	xfrm_pol_hold(policy);
 	net->xfrm.policy_count[dir]++;
 	atomic_inc(&flow_cache_genid);
-	rt_genid_bump(net);
+
+	/* After previous checking, family can either be AF_INET or AF_INET6 */
+	if (policy->family == AF_INET)
+		rt_genid_bump_ipv4(net);
+	else
+		rt_genid_bump_ipv6(net);
+
 	if (delpol) {
 		xfrm_policy_requeue(delpol, policy);
 		__xfrm_policy_unlink(delpol, dir);
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 65f67cb..6713f04 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -50,8 +50,13 @@
 
 static inline void selinux_xfrm_notify_policyload(void)
 {
+	struct net *net;
+
 	atomic_inc(&flow_cache_genid);
-	rt_genid_bump(&init_net);
+	rtnl_lock();
+	for_each_net(net)
+		rt_genid_bump_all(net);
+	rtnl_unlock();
 }
 #else
 static inline int selinux_xfrm_enabled(void)