ipv6: Handle all fib6_nh in a nexthop in mtu updates

Use nexthop_for_each_fib6_nh to call fib6_nh_mtu_change for each
fib6_nh in a nexthop for rt6_mtu_change_route. For __ip6_rt_update_pmtu,
we need to find the nexthop that correlates to the device and gateway
in the rt6_info.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 1 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 715356e00f58..f287375fd0b2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2679,10 +2679,31 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
                         rcu_read_unlock();
                         return;
                 }
-                res.nh = res.f6i->fib6_nh;
                 res.fib6_flags = res.f6i->fib6_flags;
                 res.fib6_type = res.f6i->fib6_type;
 
+                if (res.f6i->nh) {
+                        struct fib6_nh_match_arg arg = {
+                                .dev = dst->dev,
+                                .gw = &rt6->rt6i_gateway,
+                        };
+
+                        nexthop_for_each_fib6_nh(res.f6i->nh,
+                                                 fib6_nh_find_match, &arg);
+
+                        /* fib6_info uses a nexthop that does not have fib6_nh
+                         * using the dst->dev + gw. Should be impossible.
+                         */
+                        if (!arg.match) {
+                                rcu_read_unlock();
+                                return;
+                        }
+
+                        res.nh = arg.match;
+                } else {
+                        res.nh = res.f6i->fib6_nh;
+                }
+
                 nrt6 = ip6_rt_cache_alloc(&res, daddr, saddr);
                 if (nrt6) {
                         rt6_do_update_pmtu(nrt6, mtu);
@@ -4650,6 +4671,12 @@ static int rt6_mtu_change_route(struct fib6_info *f6i, void *p_arg)
                 return 0;
 
         arg->f6i = f6i;
+        if (f6i->nh) {
+                /* fib6_nh_mtu_change only returns 0, so this is safe */
+                return nexthop_for_each_fib6_nh(f6i->nh, fib6_nh_mtu_change,
+                                                arg);
+        }
+
         return fib6_nh_mtu_change(f6i->fib6_nh, arg);
 }