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Commit a2f1483b authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'vxlan-fix-default-fdb-entry-user-space-notify-ordering-race' 



Roopa Prabhu says:

====================
vxlan: fix default fdb entry user-space notify ordering/race

Problem:
In vxlan_newlink, a default fdb entry is added before register_netdev.
The default fdb creation function 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 series fixes the user-space netlink notification ordering issue
with the following changes:
- decouple fdb notify from fdb create.
- Move fdb notify after register_netdev.
- modify rtnl_configure_link to allow configuring a link early.
- 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>
parents 22dd1491 0241b836

drivers/net/vxlan.c

+87 −39
Original line number Diff line number Diff line
@@ -637,8 +637,61 @@ static int vxlan_gro_complete(struct sock *sk, struct sk_buff *skb, int nhoff) 
	return eth_gro_complete(skb, nhoff + sizeof(struct vxlanhdr));

}



/* Add new entry to forwarding table -- assumes lock held */

static struct vxlan_fdb *vxlan_fdb_alloc(struct vxlan_dev *vxlan,

					 const u8 *mac, __u16 state,

					 __be32 src_vni, __u8 ndm_flags)

{

	struct vxlan_fdb *f;



	f = kmalloc(sizeof(*f), GFP_ATOMIC);

	if (!f)

		return NULL;

	f->state = state;

	f->flags = ndm_flags;

	f->updated = f->used = jiffies;

	f->vni = src_vni;

	INIT_LIST_HEAD(&f->remotes);

	memcpy(f->eth_addr, mac, ETH_ALEN);



	return f;

}



static int vxlan_fdb_create(struct vxlan_dev *vxlan,

			    const u8 *mac, union vxlan_addr *ip,

			    __u16 state, __be16 port, __be32 src_vni,

			    __be32 vni, __u32 ifindex, __u8 ndm_flags,

			    struct vxlan_fdb **fdb)

{

	struct vxlan_rdst *rd = NULL;

	struct vxlan_fdb *f;

	int rc;



	if (vxlan->cfg.addrmax &&

	    vxlan->addrcnt >= vxlan->cfg.addrmax)

		return -ENOSPC;



	netdev_dbg(vxlan->dev, "add %pM -> %pIS\n", mac, ip);

	f = vxlan_fdb_alloc(vxlan, mac, state, src_vni, ndm_flags);

	if (!f)

		return -ENOMEM;



	rc = vxlan_fdb_append(f, ip, port, vni, ifindex, &rd);

	if (rc < 0) {

		kfree(f);

		return rc;

	}



	++vxlan->addrcnt;

	hlist_add_head_rcu(&f->hlist,

			   vxlan_fdb_head(vxlan, mac, src_vni));



	*fdb = f;



	return 0;

}



/* Add new entry to forwarding table -- assumes lock held */

static int vxlan_fdb_update(struct vxlan_dev *vxlan,

			    const u8 *mac, union vxlan_addr *ip,

			    __u16 state, __u16 flags,

			    __be16 port, __be32 src_vni, __be32 vni,
@@ -688,37 +741,17 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan, 
		if (!(flags & NLM_F_CREATE))

			return -ENOENT;



		if (vxlan->cfg.addrmax &&

		    vxlan->addrcnt >= vxlan->cfg.addrmax)

			return -ENOSPC;



		/* Disallow replace to add a multicast entry */

		if ((flags & NLM_F_REPLACE) &&

		    (is_multicast_ether_addr(mac) || is_zero_ether_addr(mac)))

			return -EOPNOTSUPP;



		netdev_dbg(vxlan->dev, "add %pM -> %pIS\n", mac, ip);

		f = kmalloc(sizeof(*f), GFP_ATOMIC);

		if (!f)

			return -ENOMEM;



		notify = 1;

		f->state = state;

		f->flags = ndm_flags;

		f->updated = f->used = jiffies;

		f->vni = src_vni;

		INIT_LIST_HEAD(&f->remotes);

		memcpy(f->eth_addr, mac, ETH_ALEN);



		rc = vxlan_fdb_append(f, ip, port, vni, ifindex, &rd);

		if (rc < 0) {

			kfree(f);

		rc = vxlan_fdb_create(vxlan, mac, ip, state, port, src_vni,

				      vni, ifindex, ndm_flags, &f);

		if (rc < 0)

			return rc;

		}



		++vxlan->addrcnt;

		hlist_add_head_rcu(&f->hlist,

				   vxlan_fdb_head(vxlan, mac, src_vni));

		notify = 1;

	}



	if (notify) {
@@ -742,12 +775,14 @@ static void vxlan_fdb_free(struct rcu_head *head) 
	kfree(f);

}



static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f)

static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f,

			      bool do_notify)

{

	netdev_dbg(vxlan->dev,

		    "delete %pM\n", f->eth_addr);



	--vxlan->addrcnt;

	if (do_notify)

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



	hlist_del_rcu(&f->hlist);
@@ -864,7 +899,7 @@ static int vxlan_fdb_add(struct ndmsg *ndm, struct nlattr *tb[], 
		return -EAFNOSUPPORT;



	spin_lock_bh(&vxlan->hash_lock);

	err = vxlan_fdb_create(vxlan, addr, &ip, ndm->ndm_state, flags,

	err = vxlan_fdb_update(vxlan, addr, &ip, ndm->ndm_state, flags,

			       port, src_vni, vni, ifindex, ndm->ndm_flags);

	spin_unlock_bh(&vxlan->hash_lock);
@@ -898,7 +933,7 @@ static int __vxlan_fdb_delete(struct vxlan_dev *vxlan, 
		goto out;

	}



	vxlan_fdb_destroy(vxlan, f);

	vxlan_fdb_destroy(vxlan, f, true);



out:

	return 0;
@@ -1007,7 +1042,7 @@ static bool vxlan_snoop(struct net_device *dev, 


		/* close off race between vxlan_flush and incoming packets */

		if (netif_running(dev))

			vxlan_fdb_create(vxlan, src_mac, src_ip,

			vxlan_fdb_update(vxlan, src_mac, src_ip,

					 NUD_REACHABLE,

					 NLM_F_EXCL|NLM_F_CREATE,

					 vxlan->cfg.dst_port,
@@ -2366,7 +2401,7 @@ static void vxlan_cleanup(struct timer_list *t) 
					   "garbage collect %pM\n",

					   f->eth_addr);

				f->state = NUD_STALE;

				vxlan_fdb_destroy(vxlan, f);

				vxlan_fdb_destroy(vxlan, f, true);

			} else if (time_before(timeout, next_timer))

				next_timer = timeout;

		}
@@ -2417,7 +2452,7 @@ static void vxlan_fdb_delete_default(struct vxlan_dev *vxlan, __be32 vni) 
	spin_lock_bh(&vxlan->hash_lock);

	f = __vxlan_find_mac(vxlan, all_zeros_mac, vni);

	if (f)

		vxlan_fdb_destroy(vxlan, f);

		vxlan_fdb_destroy(vxlan, f, true);

	spin_unlock_bh(&vxlan->hash_lock);

}
@@ -2471,7 +2506,7 @@ static void vxlan_flush(struct vxlan_dev *vxlan, bool do_all) 
				continue;

			/* the all_zeros_mac entry is deleted at vxlan_uninit */

			if (!is_zero_ether_addr(f->eth_addr))

				vxlan_fdb_destroy(vxlan, f);

				vxlan_fdb_destroy(vxlan, f, true);

		}

	}

	spin_unlock_bh(&vxlan->hash_lock);
@@ -3162,6 +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);
@@ -3175,24 +3211,35 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, 
		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[],
@@ -3427,6 +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,
@@ -3455,16 +3503,16 @@ static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[], 
			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);

	}

net/core/rtnetlink.c

+6 −3
Original line number Diff line number Diff line
@@ -2759,9 +2759,12 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm) 
			return err;

	}



	if (dev->rtnl_link_state == RTNL_LINK_INITIALIZED) {

		__dev_notify_flags(dev, old_flags, 0U);

	} else {

		dev->rtnl_link_state = RTNL_LINK_INITIALIZED;



		__dev_notify_flags(dev, old_flags, ~0U);

	}

	return 0;

}

EXPORT_SYMBOL(rtnl_configure_link);