On Thu, Nov 07, 2019 at 03:01:18PM +0100, Eelco Chaudron wrote:
> Any feedback on this?
>
>
> On 1 Oct 2019, at 11:55, Eelco Chaudron wrote:
>
> >Drivers natively supporting AF_XDP will check that a configured MTU size
> >will not exceed the allowed size for AF_XDP. However, when the skb
> >compatibility mode is used there is no check and any value is accepted.
> >This, for example, is the case when using the TAP interface.
> >
> >This fix adds a check to make sure only AF_XDP valid values are excepted.
> >
> >Signed-off-by: Eelco Chaudron <echau...@redhat.com>
> >---
> > lib/netdev-afxdp.c | 17 +++++++++++++++++
> > lib/netdev-afxdp.h | 1 +
> > lib/netdev-linux.c | 9 +++++++++
> > 3 files changed, 27 insertions(+)
> >
> >diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c
> >index 6e0180327..140150f29 100644
> >--- a/lib/netdev-afxdp.c
> >+++ b/lib/netdev-afxdp.c
> >@@ -1001,6 +1001,23 @@ netdev_afxdp_destruct(struct netdev *netdev)
> > ovs_mutex_destroy(&dev->mutex);
> > }
> >
> >+int
> >+netdev_afxdp_verify_mtu_size(const struct netdev *netdev, int mtu)
> >+{
> >+ /*
> >+ * If a device is used in xdpmode skb, no driver-specific MTU size is
> >+ * checked and any value is allowed resulting in packet drops.
> >+ * This check will verify the maximum supported value based on the
> >+ * buffer size allocated and the additional headroom required.
> >+ */
> >+ if (netdev == NULL || mtu <= 0
> >+ || mtu > (FRAME_SIZE - OVS_XDP_HEADROOM - XDP_PACKET_HEADROOM)) {
I remember XDP max MTU = 3520 bytes,
and it's (page_size(4096) - headroom(256) - shinfo(320))
so here we should also subtract shinfo?
Regards,
William
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