Commit 345010b5 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

net: vxlan: use custom ndo_change_mtu handler 



When adding a new vxlan device to an "underlying carrier" (here:
dst->remote_ifindex), the MTU size assigned to the vxlan device
is the MTU at setup time of the carrier - needed headroom, when
adding a vxlan device w/o explicit carrier, then it defaults
to 1500.

In case of an explicit carrier that supports jumbo frames, we
currently cannot change vxlan MTU via ip(8) to > 1500 in
post-setup time, as vxlan driver uses eth_change_mtu() as default
method for manually setting MTU.

Hence, use a custom implementation that only falls back to
eth_change_mtu() in case we didn't use a dev parameter on device
setup time, and otherwise allow a max MTU setting of the carrier
incl. adjustment for headroom.

Reported-by: default avatarShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Acked-by: default avatarStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 289dccbe

drivers/net/vxlan.c

+24 −1
Original line number Diff line number Diff line
@@ -2014,6 +2014,29 @@ static void vxlan_set_multicast_list(struct net_device *dev) 
{

}



static int vxlan_change_mtu(struct net_device *dev, int new_mtu)

{

	struct vxlan_dev *vxlan = netdev_priv(dev);

	struct vxlan_rdst *dst = &vxlan->default_dst;

	struct net_device *lowerdev;

	int max_mtu;



	lowerdev = __dev_get_by_index(dev_net(dev), dst->remote_ifindex);

	if (lowerdev == NULL)

		return eth_change_mtu(dev, new_mtu);



	if (dst->remote_ip.sa.sa_family == AF_INET6)

		max_mtu = lowerdev->mtu - VXLAN6_HEADROOM;

	else

		max_mtu = lowerdev->mtu - VXLAN_HEADROOM;



	if (new_mtu < 68 || new_mtu > max_mtu)

		return -EINVAL;



	dev->mtu = new_mtu;

	return 0;

}



static const struct net_device_ops vxlan_netdev_ops = {

	.ndo_init		= vxlan_init,

	.ndo_uninit		= vxlan_uninit,
@@ -2022,7 +2045,7 @@ static const struct net_device_ops vxlan_netdev_ops = { 
	.ndo_start_xmit		= vxlan_xmit,

	.ndo_get_stats64	= ip_tunnel_get_stats64,

	.ndo_set_rx_mode	= vxlan_set_multicast_list,

	.ndo_change_mtu		= eth_change_mtu,

	.ndo_change_mtu		= vxlan_change_mtu,

	.ndo_validate_addr	= eth_validate_addr,

	.ndo_set_mac_address	= eth_mac_addr,

	.ndo_fdb_add		= vxlan_fdb_add,

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