4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tommi Rantala tommi.t.rantala@nokia.com
[ Upstream commit 8cc88773855f988d6a3bbf102bbd9dd9c828eb81 ]
Fix missing dst_release() when local broadcast or multicast traffic is xfrm policy blocked.
For IPv4 this results to dst leak: ip_route_output_flow() allocates dst_entry via __ip_route_output_key() and passes it to xfrm_lookup_route(). xfrm_lookup returns ERR_PTR(-EPERM) that is propagated. The dst that was allocated is never released.
IPv4 local broadcast testcase: ping -b 192.168.1.255 & sleep 1 ip xfrm policy add src 0.0.0.0/0 dst 192.168.1.255/32 dir out action block
IPv4 multicast testcase: ping 224.0.0.1 & sleep 1 ip xfrm policy add src 0.0.0.0/0 dst 224.0.0.1/32 dir out action block
For IPv6 the missing dst_release() causes trouble e.g. when used in netns: ip netns add TEST ip netns exec TEST ip link set lo up ip link add dummy0 type dummy ip link set dev dummy0 netns TEST ip netns exec TEST ip addr add fd00::1111 dev dummy0 ip netns exec TEST ip link set dummy0 up ip netns exec TEST ping -6 -c 5 ff02::1%dummy0 & sleep 1 ip netns exec TEST ip xfrm policy add src ::/0 dst ff02::1 dir out action block wait ip netns del TEST
After netns deletion we see: [ 258.239097] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 268.279061] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 278.367018] unregister_netdevice: waiting for lo to become free. Usage count = 2 [ 288.375259] unregister_netdevice: waiting for lo to become free. Usage count = 2
Fixes: ac37e2515c1a ("xfrm: release dst_orig in case of error in xfrm_lookup()") Signed-off-by: Tommi Rantala tommi.t.rantala@nokia.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/xfrm/xfrm_policy.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -2326,6 +2326,9 @@ struct dst_entry *xfrm_lookup_route(stru if (IS_ERR(dst) && PTR_ERR(dst) == -EREMOTE) return make_blackhole(net, dst_orig->ops->family, dst_orig);
+ if (IS_ERR(dst)) + dst_release(dst_orig); + return dst; } EXPORT_SYMBOL(xfrm_lookup_route);