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Commit d90a909e authored by Eric W. Biederman's avatar Eric W. Biederman Committed by David S. Miller
Browse files

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: default avatarEric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5781b235

net/core/dev.c

+11 −0
Original line number Original line Diff line number Diff line
@@ -5035,6 +5035,11 @@ int register_netdevice(struct net_device *dev) 
		rollback_registered(dev);

		rollback_registered(dev);

		dev->reg_state = NETREG_UNREGISTERED;

		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:

out:

	return ret;

	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. */

	/* Notify protocols, that a new device appeared. */

	call_netdevice_notifiers(NETDEV_REGISTER, dev);

	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();

	synchronize_net();

	err = 0;

	err = 0;

out:

out:

net/core/rtnetlink.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -1364,15 +1364,15 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi 
	case NETDEV_UNREGISTER:

	case NETDEV_UNREGISTER:

		rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);

		rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);

		break;

		break;

	case NETDEV_REGISTER:

		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);

		break;

	case NETDEV_UP:

	case NETDEV_UP:

	case NETDEV_DOWN:

	case NETDEV_DOWN:

		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);

		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);

		break;

		break;

	case NETDEV_POST_INIT:

	case NETDEV_REGISTER:

	case NETDEV_CHANGE:

	case NETDEV_CHANGE:

	case NETDEV_GOING_DOWN:

	case NETDEV_GOING_DOWN:

	case NETDEV_UNREGISTER_BATCH:

		break;

		break;

	default:

	default:

		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);

		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);