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Commit 0241b836 authored by Roopa Prabhu's avatar Roopa Prabhu Committed by David S. Miller
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vxlan: fix default fdb entry netlink notify ordering during netdev create 



Problem:
In vxlan_newlink, a default fdb entry is added before register_netdev.
The default fdb creation function also notifies user-space of the
fdb entry on the vxlan device which user-space does not know about yet.
(RTM_NEWNEIGH goes before RTM_NEWLINK for the same ifindex).

This patch fixes the user-space netlink notification ordering issue
with the following changes:
- decouple fdb notify from fdb create.
- Move fdb notify after register_netdev.
- Call rtnl_configure_link in vxlan newlink handler to notify
userspace about the newlink before fdb notify and
hence avoiding the user-space race.

Fixes: afbd8bae ("vxlan: add implicit fdb entry for default destination")
Signed-off-by: default avatarRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4c2438ba

drivers/net/vxlan.c

+21 −8
Original line number Diff line number Diff line
@@ -3197,6 +3197,7 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, 
{

	struct vxlan_net *vn = net_generic(net, vxlan_net_id);

	struct vxlan_dev *vxlan = netdev_priv(dev);

	struct vxlan_fdb *f = NULL;

	int err;



	err = vxlan_dev_configure(net, dev, conf, false, extack);
@@ -3207,27 +3208,38 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, 


	/* create an fdb entry for a valid default destination */

	if (!vxlan_addr_any(&vxlan->default_dst.remote_ip)) {

		err = vxlan_fdb_update(vxlan, all_zeros_mac,

		err = vxlan_fdb_create(vxlan, all_zeros_mac,

				       &vxlan->default_dst.remote_ip,

				       NUD_REACHABLE | NUD_PERMANENT,

				       NLM_F_EXCL | NLM_F_CREATE,

				       vxlan->cfg.dst_port,

				       vxlan->default_dst.remote_vni,

				       vxlan->default_dst.remote_vni,

				       vxlan->default_dst.remote_ifindex,

				       NTF_SELF);

				       NTF_SELF, &f);

		if (err)

			return err;

	}



	err = register_netdevice(dev);

	if (err)

		goto errout;



	err = rtnl_configure_link(dev, NULL);

	if (err) {

		vxlan_fdb_delete_default(vxlan, vxlan->default_dst.remote_vni);

		return err;

		unregister_netdevice(dev);

		goto errout;

	}



	/* notify default fdb entry */

	if (f)

		vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH);



	list_add(&vxlan->next, &vn->vxlan_list);

	return 0;

errout:

	if (f)

		vxlan_fdb_destroy(vxlan, f, false);

	return err;

}



static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
@@ -3462,6 +3474,7 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], 
	struct vxlan_rdst *dst = &vxlan->default_dst;

	struct vxlan_rdst old_dst;

	struct vxlan_config conf;

	struct vxlan_fdb *f = NULL;

	int err;



	err = vxlan_nl2conf(tb, data,
@@ -3487,19 +3500,19 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], 
					   old_dst.remote_ifindex, 0);



		if (!vxlan_addr_any(&dst->remote_ip)) {

			err = vxlan_fdb_update(vxlan, all_zeros_mac,

			err = vxlan_fdb_create(vxlan, all_zeros_mac,

					       &dst->remote_ip,

					       NUD_REACHABLE | NUD_PERMANENT,

					       NLM_F_CREATE | NLM_F_APPEND,

					       vxlan->cfg.dst_port,

					       dst->remote_vni,

					       dst->remote_vni,

					       dst->remote_ifindex,

					       NTF_SELF);

					       NTF_SELF, &f);

			if (err) {

				spin_unlock_bh(&vxlan->hash_lock);

				return err;

			}

			vxlan_fdb_notify(vxlan, f, first_remote_rtnl(f), RTM_NEWNEIGH);

		}

		spin_unlock_bh(&vxlan->hash_lock);

	}