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: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index ea203c1..aef44aa 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2014,6 +2014,29 @@
{
}
+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 @@
.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,