net: Fix userspace RTM_NEWLINK notifications.

commit d90a909e1f3e006a1d57fe11fd417173b6494701 upstream.

I received some bug reports about userspace programs having problems
because after RTM_NEWLINK was received they could not immeidate
access files under /proc/sys/net/ because they had not been
registered yet.

The problem was trivailly fixed by moving the userspace
notification from rtnetlink_event to the end of register_netdevice.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/core/dev.c b/net/core/dev.c
index fe10551d3671053ea6d6a6da57de037f43ad78d0..584046eef9cb61920a39d943cb24a9fe71719669 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4860,6 +4860,11 @@ 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;
@@ -5398,6 +5403,12 @@ 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 eb42873f2a3a768197d7f760709810fa5b1e2ee2..d4fd895e8712b59df367033f20d13047f7dcc5d1 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1334,13 +1334,11 @@ 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_REGISTER:
        case NETDEV_CHANGE:
        case NETDEV_GOING_DOWN:
                break;