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 <[email protected]>
---
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)) {
+ return EINVAL;
+ }
+
+ return 0;
+}
+
int
netdev_afxdp_get_custom_stats(const struct netdev *netdev,
struct netdev_custom_stats
*custom_stats)
diff --git a/lib/netdev-afxdp.h b/lib/netdev-afxdp.h
index e2f400b72..ee6939fce 100644
--- a/lib/netdev-afxdp.h
+++ b/lib/netdev-afxdp.h
@@ -39,6 +39,7 @@ int netdev_afxdp_rxq_construct(struct netdev_rxq
*rxq_);
void netdev_afxdp_rxq_destruct(struct netdev_rxq *rxq_);
int netdev_afxdp_construct(struct netdev *netdev_);
void netdev_afxdp_destruct(struct netdev *netdev_);
+int netdev_afxdp_verify_mtu_size(const struct netdev *netdev, int
mtu);
int netdev_afxdp_rxq_recv(struct netdev_rxq *rxq_,
struct dp_packet_batch *batch,
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index f48192373..89d0d9a9d 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -1593,6 +1593,15 @@ netdev_linux_set_mtu(struct netdev *netdev_,
int mtu)
goto exit;
}
+#ifdef HAVE_AF_XDP
+ if (!strcmp(netdev_get_type(netdev_), "afxdp")) {
+ error = netdev_afxdp_verify_mtu_size(netdev_, mtu);
+ if (error) {
+ goto exit;
+ }
+ }
+#endif
+
if (netdev->cache_valid & VALID_MTU) {
error = netdev->netdev_mtu_error;
if (error || netdev->mtu == mtu) {
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