ipv6: fix problem with expired dst cache

If the ipv6 dst cache which copy from the dst generated by ICMPV6 RA packet.
this dst cache will not check expire because it has no RTF_EXPIRES flag.
So this dst cache will always be used until the dst gc run.

Change the struct dst_entry,add a union contains new pointer from and expires.
When rt6_info.rt6i_flags has no RTF_EXPIRES flag,the dst.expires has no use.
we can use this field to point to where the dst cache copy from.
The dst.from is only used in IPV6.

rt6_check_expired check if rt6_info.dst.from is expired.

ip6_rt_copy only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.then hold the ort.

ip6_dst_destroy release the ort.

Add some functions to operate the RTF_EXPIRES flag and expires(from) together.
and change the code to use these new adding functions.

Changes from v5:
modify ip6_route_add and ndisc_router_discovery to use new adding functions.

Only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.then hold the ort.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 6 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6a3bb6077e19..7d5cb975cc6f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -803,8 +803,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
                                 ip6_del_rt(rt);
                                 rt = NULL;
                         } else if (!(rt->rt6i_flags & RTF_EXPIRES)) {
-                                rt->dst.expires = expires;
-                                rt->rt6i_flags |= RTF_EXPIRES;
+                                rt6_set_expires(rt, expires);
                         }
                 }
                 dst_release(&rt->dst);
@@ -1887,11 +1886,9 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
                                 rt = NULL;
                         } else if (addrconf_finite_timeout(rt_expires)) {
                                 /* not infinity */
-                                rt->dst.expires = jiffies + rt_expires;
-                                rt->rt6i_flags |= RTF_EXPIRES;
+                                rt6_set_expires(rt, jiffies + rt_expires);
                         } else {
-                                rt->rt6i_flags &= ~RTF_EXPIRES;
-                                rt->dst.expires = 0;
+                                rt6_clean_expires(rt);
                         }
                 } else if (valid_lft) {
                         clock_t expires = 0;