Merge branch 'ipv6-route-fixes'

Martin KaFai Lau says:

====================
ipv6: Fixes for pmtu update and DST_NOCACHE route

This patchset fixes:
1. An oops during IPv6 pmtu update on a IPv4 GRE running
   in an IPSec setup
2. Misc fixes on DST_NOCACHE route
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/ip6_fib.h

@@ -167,7 +167,8 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
 
 static inline u32 rt6_get_cookie(const struct rt6_info *rt)
 {
-	if (rt->rt6i_flags & RTF_PCPU || unlikely(rt->dst.flags & DST_NOCACHE))
+	if (rt->rt6i_flags & RTF_PCPU ||
+	    (unlikely(rt->dst.flags & DST_NOCACHE) && rt->dst.from))
 		rt = (struct rt6_info *)(rt->dst.from);
 
 	return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;

net/ipv6/route.c

@@ -404,6 +404,14 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 	}
 }
 
+static bool __rt6_check_expired(const struct rt6_info *rt)
+{
+	if (rt->rt6i_flags & RTF_EXPIRES)
+		return time_after(jiffies, rt->dst.expires);
+	else
+		return false;
+}
+
 static bool rt6_check_expired(const struct rt6_info *rt)
 {
 	if (rt->rt6i_flags & RTF_EXPIRES) {
@@ -1252,7 +1260,8 @@ static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
 
 static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie)
 {
-	if (rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
+	if (!__rt6_check_expired(rt) &&
+	    rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
 	    rt6_check((struct rt6_info *)(rt->dst.from), cookie))
 		return &rt->dst;
 	else
@@ -1272,7 +1281,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 
 	rt6_dst_from_metrics_check(rt);
 
-	if ((rt->rt6i_flags & RTF_PCPU) || unlikely(dst->flags & DST_NOCACHE))
+	if (rt->rt6i_flags & RTF_PCPU ||
+	    (unlikely(dst->flags & DST_NOCACHE) && rt->dst.from))
 		return rt6_dst_from_check(rt, cookie);
 	else
 		return rt6_check(rt, cookie);
@@ -1322,6 +1332,12 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
 	rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires);
 }
 
+static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
+{
+	return !(rt->rt6i_flags & RTF_CACHE) &&
+		(rt->rt6i_flags & RTF_PCPU || rt->rt6i_node);
+}
+
 static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
 				 const struct ipv6hdr *iph, u32 mtu)
 {
@@ -1335,7 +1351,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
 	if (mtu >= dst_mtu(dst))
 		return;
 
-	if (rt6->rt6i_flags & RTF_CACHE) {
+	if (!rt6_cache_allowed_for_pmtu(rt6)) {
 		rt6_do_update_pmtu(rt6, mtu);
 	} else {
 		const struct in6_addr *daddr, *saddr;