From: David Wragg <david@weave.works>
Upstream commit:
Calculate the maximum MTU taking into account the size of headers
involved in GENEVE encapsulation, as for other tunnel types.
Changes in v3:
- Correct comment style
Changes in v2:
- Conform more closely to ip_tunnel_change_mtu
- Exclude GENEVE options from max MTU calculation
Signed-off-by: David Wragg <david@weave.works>
Acked-by: Jesse Gross <je...@kernel.org>
Signed-off-by: David S. Miller <da...@davemloft.net>
Upstream: aeee0e66c6b4 ("geneve: Refine MTU limit")
Signed-off-by: Joe Stringer <j...@ovn.org>
---
datapath/linux/compat/geneve.c | 27 ++++++++++++++++++++++-----
1 file changed, 22 insertions(+), 5 deletions(-)
diff --git a/datapath/linux/compat/geneve.c b/datapath/linux/compat/geneve.c
index 50ed3936d038..92feeef0900c 100644
--- a/datapath/linux/compat/geneve.c
+++ b/datapath/linux/compat/geneve.c
@@ -742,17 +742,34 @@ static netdev_tx_t geneve_dev_xmit(struct sk_buff *skb,
struct net_device *dev)
return NETDEV_TX_OK;
}
-static int geneve_change_mtu(struct net_device *dev, int new_mtu)
+static int __geneve_change_mtu(struct net_device *dev, int new_mtu, bool
strict)
{
- /* GENEVE overhead is not fixed, so we can't enforce a more
- * precise max MTU.
+ /* The max_mtu calculation does not take account of GENEVE
+ * options, to avoid excluding potentially valid
+ * configurations.
*/
- if (new_mtu < 68 || new_mtu > IP_MAX_MTU)
+ int max_mtu = IP_MAX_MTU - GENEVE_BASE_HLEN - sizeof(struct iphdr)
+ - dev->hard_header_len;
+
+ if (new_mtu < 68)
return -EINVAL;
+
+ if (new_mtu > max_mtu) {
+ if (strict)
+ return -EINVAL;
+
+ new_mtu = max_mtu;
+ }
+
dev->mtu = new_mtu;
return 0;
}
+static int geneve_change_mtu(struct net_device *dev, int new_mtu)
+{
+ return __geneve_change_mtu(dev, new_mtu, true);
+}
+
static const struct net_device_ops geneve_netdev_ops = {
#ifdef HAVE_DEV_TSTATS
.ndo_init = geneve_init,
@@ -1045,7 +1062,7 @@ struct net_device *rpl_geneve_dev_create_fb(struct net
*net, const char *name,
/* openvswitch users expect packet sizes to be unrestricted,
* so set the largest MTU we can.
*/
- err = geneve_change_mtu(dev, IP_MAX_MTU);
+ err = __geneve_change_mtu(dev, IP_MAX_MTU, false);
if (err)
goto err;
--
2.1.4
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