netdev - [PATCH V2] ipvlan: fix ipvlan MTU limits

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Date:   Wed, 10 Jan 2018 15:21:49 +0800
From:   <liuqifa@...wei.com>
To:     <davem@...emloft.net>, <dsahern@...il.com>, <maheshb@...gle.com>,
        <mschiffer@...verse-factory.net>, <idosch@...lanox.com>,
        <fw@...len.de>, <kjlx@...pleofstupid.com>,
        <girish.moodalbail@...cle.com>, <sainath.grandhi@...el.com>
CC:     <netdev@...r.kernel.org>, <weiyongjun1@...wei.com>,
        <chenweilong@...wei.com>, <maowenan@...wei.com>,
        <wangyufen@...wei.com>, <yuehaibing@...wei.com>,
        <liujian56@...wei.com>, <liuqifa@...wei.com>,
        <liuzhe24@...wei.com>, <wangkefeng.wang@...wei.com>,
        <dingtianhong@...wei.com>
Subject: [PATCH V2] ipvlan: fix ipvlan MTU limits

From: Keefe Liu <liuqifa@...wei.com>

The MTU of ipvlan interface should not bigger than the phy device, When we
run following scripts, we will find there are some problems.
Step1:
	ip link add link eth0 name ipv1 type ipvlan mode l2
	ip netns add net1
	ip link set dev ipv1 netns net1
Step2:
	ip netns exec net1 ip link set dev ipv1 mtu 1501
	RTNETLINK answers: Invalid argument
	dmesg info: "ipv1: Invalid MTU 1501 requested, hw max 1500"
Step3:
	ip link set dev eth0 mtu 1600
	ip netns exec net1 ip link set dev ipv1 mtu 1501
	RTNETLINK answers: Invalid argument
	dmesg info: "ipv1: Invalid MTU 1501 requested, hw max 1500"
Step4:
	ip link set dev eth0 mtu 1400
	ip netns exec net1 ip link set dev ipv1 mtu 1500
The result of Step2 is we expected, but the result of Step3 and Step4
are not.

This patch set ipvlan's MTU ranges from ETH_MIN_MTU to phy device's maximum
MTU. When we create a new ipvlan device, its MTU will be set to the same
with phy device if we not specify the mtu value. When we change the ipvlan
device's MTU, ipvlan_change_mtu() will make sure the new MTU no bigger than
the phy device's MTU.

When we change the phy device's MTU, ipvlan devices attached to this
phy device will check their MTU value. If ipvlan's MTU bigger than phy's,
ipvlan's MTU will be set to the same with phy device, otherwise ipvlan's
MTU remains unchanged.

Signed-off-by: Keefe Liu <liuqifa@...wei.com>
---
 drivers/net/ipvlan/ipvlan_main.c | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 30cb803..2ba071a 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -34,11 +34,6 @@ struct ipvlan_netns {
 	.l3mdev_l3_rcv = ipvlan_l3_rcv,
 };
 
-static void ipvlan_adjust_mtu(struct ipvl_dev *ipvlan, struct net_device *dev)
-{
-	ipvlan->dev->mtu = dev->mtu;
-}
-
 static int ipvlan_register_nf_hook(struct net *net)
 {
 	struct ipvlan_netns *vnet = net_generic(net, ipvlan_netid);
@@ -380,12 +375,24 @@ static int ipvlan_get_iflink(const struct net_device *dev)
 	return ipvlan->phy_dev->ifindex;
 }
 
+static int ipvlan_change_mtu(struct net_device *dev, int new_mtu)
+{
+	struct ipvl_dev *ipvlan = netdev_priv(dev);
+
+	if (ipvlan->phy_dev->mtu < new_mtu)
+		return -EINVAL;
+
+	dev->mtu = new_mtu;
+	return 0;
+}
+
 static const struct net_device_ops ipvlan_netdev_ops = {
 	.ndo_init		= ipvlan_init,
 	.ndo_uninit		= ipvlan_uninit,
 	.ndo_open		= ipvlan_open,
 	.ndo_stop		= ipvlan_stop,
 	.ndo_start_xmit		= ipvlan_start_xmit,
+	.ndo_change_mtu		= ipvlan_change_mtu,
 	.ndo_fix_features	= ipvlan_fix_features,
 	.ndo_change_rx_flags	= ipvlan_change_rx_flags,
 	.ndo_set_rx_mode	= ipvlan_set_multicast_mac_filter,
@@ -581,10 +588,18 @@ int ipvlan_link_new(struct net *src_net, struct net_device *dev,
 		}
 	}
 
+	if (!tb[IFLA_MTU])
+		dev->mtu = phy_dev->mtu;
+	else if (dev->mtu > phy_dev->mtu)
+		return -EINVAL;
+
+	/* MTU range: 68 - phy_dev->max_mtu */
+	dev->min_mtu = ETH_MIN_MTU;
+	dev->max_mtu = phy_dev->max_mtu;
+
 	ipvlan->phy_dev = phy_dev;
 	ipvlan->dev = dev;
 	ipvlan->sfeatures = IPVLAN_FEATURES;
-	ipvlan_adjust_mtu(ipvlan, phy_dev);
 	INIT_LIST_HEAD(&ipvlan->addrs);
 
 	/* TODO Probably put random address here to be presented to the
@@ -680,6 +695,8 @@ void ipvlan_link_setup(struct net_device *dev)
 {
 	ether_setup(dev);
 
+	dev->min_mtu = 0;
+	dev->max_mtu = ETH_MAX_MTU;
 	dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
 	dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
 	dev->netdev_ops = &ipvlan_netdev_ops;
@@ -775,8 +792,11 @@ static int ipvlan_device_event(struct notifier_block *unused,
 		break;
 
 	case NETDEV_CHANGEMTU:
-		list_for_each_entry(ipvlan, &port->ipvlans, pnode)
-			ipvlan_adjust_mtu(ipvlan, dev);
+		list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
+			if (ipvlan->dev->mtu <= dev->mtu)
+				continue;
+			dev_set_mtu(ipvlan->dev, dev->mtu);
+		}
 		break;
 
 	case NETDEV_CHANGEADDR:
-- 
1.8.3.1