From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: Ido Schimmel idosch@nvidia.com
commit 76c03bf8e2624076b88d93542d78e22d5345c88e upstream.
As far as user space is concerned, blackhole nexthops do not have a nexthop device and therefore should not be affected by the administrative or carrier state of any netdev.
However, when the loopback netdev goes down all the blackhole nexthops are flushed. This happens because internally the kernel associates blackhole nexthops with the loopback netdev.
This behavior is both confusing to those not familiar with kernel internals and also diverges from the legacy API where blackhole IPv4 routes are not flushed when the loopback netdev goes down:
# ip route add blackhole 198.51.100.0/24 # ip link set dev lo down # ip route show 198.51.100.0/24 blackhole 198.51.100.0/24
Blackhole IPv6 routes are flushed, but at least user space knows that they are associated with the loopback netdev:
# ip -6 route show 2001:db8:1::/64 blackhole 2001:db8:1::/64 dev lo metric 1024 pref medium
Fix this by only flushing blackhole nexthops when the loopback netdev is unregistered.
Fixes: ab84be7e54fc ("net: Initial nexthop code") Signed-off-by: Ido Schimmel idosch@nvidia.com Reported-by: Donald Sharp sharpd@nvidia.com Reviewed-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/nexthop.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -1065,7 +1065,7 @@ out:
/* rtnl */ /* remove all nexthops tied to a device being deleted */ -static void nexthop_flush_dev(struct net_device *dev) +static void nexthop_flush_dev(struct net_device *dev, unsigned long event) { unsigned int hash = nh_dev_hashfn(dev->ifindex); struct net *net = dev_net(dev); @@ -1077,6 +1077,10 @@ static void nexthop_flush_dev(struct net if (nhi->fib_nhc.nhc_dev != dev) continue;
+ if (nhi->reject_nh && + (event == NETDEV_DOWN || event == NETDEV_CHANGE)) + continue; + remove_nexthop(net, nhi->nh_parent, NULL); } } @@ -1794,11 +1798,11 @@ static int nh_netdev_event(struct notifi switch (event) { case NETDEV_DOWN: case NETDEV_UNREGISTER: - nexthop_flush_dev(dev); + nexthop_flush_dev(dev, event); break; case NETDEV_CHANGE: if (!(dev_get_flags(dev) & (IFF_RUNNING | IFF_LOWER_UP))) - nexthop_flush_dev(dev); + nexthop_flush_dev(dev, event); break; case NETDEV_CHANGEMTU: info_ext = ptr;