net: ipv6 sysctl option to ignore routes when nexthop link is down
Like the ipv4 patch with a similar title, this adds a sysctl to allow
the user to change routing behavior based on whether or not the
interface associated with the nexthop was an up or down link. The
default setting preserves the current behavior, but anyone that enables
it will notice that nexthops on down interfaces will no longer be
selected:
net.ipv6.conf.all.ignore_routes_with_linkdown = 0
net.ipv6.conf.default.ignore_routes_with_linkdown = 0
net.ipv6.conf.lo.ignore_routes_with_linkdown = 0
...
When the above sysctls are set, not only will link status be reported to
userspace, but an indication that a nexthop is dead and will not be used
is also reported.
1000::/8 via 7000::2 dev p7p1 metric 1024 dead linkdown pref medium
1000::/8 via 8000::2 dev p8p1 metric 1024 pref medium
7000::/8 dev p7p1 proto kernel metric 256 dead linkdown pref medium
8000::/8 dev p8p1 proto kernel metric 256 pref medium
9000::/8 via 8000::2 dev p8p1 metric 2048 pref medium
9000::/8 via 7000::2 dev p7p1 metric 1024 dead linkdown pref medium
fe80::/64 dev p7p1 proto kernel metric 256 dead linkdown pref medium
fe80::/64 dev p8p1 proto kernel metric 256 pref medium
This also adds devconf support and notification when sysctl values
change.
v2: drop use of rt6i_nhflags since it is not needed right now
Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 370f727..1c0217e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -665,6 +665,12 @@
{
int m;
bool match_do_rr = false;
+ struct inet6_dev *idev = rt->rt6i_idev;
+ struct net_device *dev = rt->dst.dev;
+
+ if (dev && !netif_carrier_ok(dev) &&
+ idev->cnf.ignore_routes_with_linkdown)
+ goto out;
if (rt6_check_expired(rt))
goto out;
@@ -2887,8 +2893,11 @@
else
rtm->rtm_type = RTN_UNICAST;
rtm->rtm_flags = 0;
- if (!netif_carrier_ok(rt->dst.dev))
+ if (!netif_carrier_ok(rt->dst.dev)) {
rtm->rtm_flags |= RTNH_F_LINKDOWN;
+ if (rt->rt6i_idev->cnf.ignore_routes_with_linkdown)
+ rtm->rtm_flags |= RTNH_F_DEAD;
+ }
rtm->rtm_scope = RT_SCOPE_UNIVERSE;
rtm->rtm_protocol = rt->rt6i_protocol;
if (rt->rt6i_flags & RTF_DYNAMIC)