From 78d6501ba52874f19645dd568f64449504a9f8c6 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xmission.com> Date: Sat, 12 Dec 2009 22:11:15 +0000 Subject: [PATCH] net: Fix userspace RTM_NEWLINK notifications. I received some bug reports about userspace programs having problems because after RTM_NEWLINK was received they could not immediate access files under /proc/sys/net/ because they had not been registered yet. The original problem was trivially fixed by moving the userspace notification from rtnetlink_event() to the end of register_netdevice(). When testing that change I discovered I was still getting RTM_NEWLINK events before I could access proc and I was also getting RTM_NEWLINK events after I was seeing RTM_DELLINK. Things practically guaranteed to confuse userspace. After a little more investigation these extra notifications proved to be from the new notifiers NETDEV_POST_INIT and NETDEV_UNREGISTER_BATCH hitting the default case in rtnetlink_event, and triggering unnecessary RTM_NEWLINK messages. rtnetlink_event now explicitly handles NETDEV_UNREGISTER_BATCH and NETDEV_POST_INIT to avoid sending the incorrect userspace notifications. Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net> --- net/core/dev.c | 11 +++++++++++ net/core/rtnetlink.c | 6 +++--- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 6fe7d739e59bd..be9924f60ec34 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5035,6 +5035,11 @@ int register_netdevice(struct net_device *dev) rollback_registered(dev); dev->reg_state = NETREG_UNREGISTERED; } + /* + * Prevent userspace races by waiting until the network + * device is fully setup before sending notifications. + */ + rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U); out: return ret; @@ -5597,6 +5602,12 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char /* Notify protocols, that a new device appeared. */ call_netdevice_notifiers(NETDEV_REGISTER, dev); + /* + * Prevent userspace races by waiting until the network + * device is fully setup before sending notifications. + */ + rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U); + synchronize_net(); err = 0; out: diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 33148a568199c..794bcb897ff00 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1364,15 +1364,15 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi case NETDEV_UNREGISTER: rtmsg_ifinfo(RTM_DELLINK, dev, ~0U); break; - case NETDEV_REGISTER: - rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U); - break; case NETDEV_UP: case NETDEV_DOWN: rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING); break; + case NETDEV_POST_INIT: + case NETDEV_REGISTER: case NETDEV_CHANGE: case NETDEV_GOING_DOWN: + case NETDEV_UNREGISTER_BATCH: break; default: rtmsg_ifinfo(RTM_NEWLINK, dev, 0); -- 2.39.5