Commit 38d40815 authored by Eric Biederman's avatar Eric Biederman Committed by David S. Miller
Browse files

veth: Allow setting the L3 MTU 



The limitation to only 1500 byte mtu's limits the utility of the veth
device for testing routing.  So implement implement a configurable
MTU.

For consistency I drop packets on the receive side when they are
larger than the MTU.  I count those drops.  And I allow
a little padding for vlan headers.

I also test the mtu when a new device is created with netlink
because that path currently bypasses the current mtu setting
code.

Signed-off-by: default avatarEric Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent abb79972

drivers/net/veth.c

+39 −6
Original line number Diff line number Diff line
@@ -19,12 +19,17 @@ 
#define DRV_NAME	"veth"

#define DRV_VERSION	"1.0"



#define MIN_MTU 68		/* Min L3 MTU */

#define MAX_MTU 65535		/* Max L3 MTU (arbitrary) */

#define MTU_PAD (ETH_HLEN + 4)  /* Max difference between L2 and L3 size MTU */



struct veth_net_stats {

	unsigned long	rx_packets;

	unsigned long	tx_packets;

	unsigned long	rx_bytes;

	unsigned long	tx_bytes;

	unsigned long	tx_dropped;

	unsigned long	rx_dropped;

};



struct veth_priv {
@@ -147,7 +152,7 @@ static int veth_xmit(struct sk_buff *skb, struct net_device *dev) 
{

	struct net_device *rcv = NULL;

	struct veth_priv *priv, *rcv_priv;

	struct veth_net_stats *stats;

	struct veth_net_stats *stats, *rcv_stats;

	int length, cpu;



	skb_orphan(skb);
@@ -158,9 +163,13 @@ static int veth_xmit(struct sk_buff *skb, struct net_device *dev) 


	cpu = smp_processor_id();

	stats = per_cpu_ptr(priv->stats, cpu);

	rcv_stats = per_cpu_ptr(rcv_priv->stats, cpu);



	if (!(rcv->flags & IFF_UP))

		goto outf;

		goto tx_drop;



	if (skb->len > (rcv->mtu + MTU_PAD))

		goto rx_drop;



	skb->pkt_type = PACKET_HOST;

	skb->protocol = eth_type_trans(skb, rcv);
@@ -178,17 +187,21 @@ static int veth_xmit(struct sk_buff *skb, struct net_device *dev) 
	stats->tx_bytes += length;

	stats->tx_packets++;



	stats = per_cpu_ptr(rcv_priv->stats, cpu);

	stats->rx_bytes += length;

	stats->rx_packets++;

	rcv_stats->rx_bytes += length;

	rcv_stats->rx_packets++;



	netif_rx(skb);

	return 0;



outf:

tx_drop:

	kfree_skb(skb);

	stats->tx_dropped++;

	return 0;



rx_drop:

	kfree_skb(skb);

	rcv_stats->rx_dropped++;

	return 0;

}



/*
@@ -210,6 +223,7 @@ static struct net_device_stats *veth_get_stats(struct net_device *dev) 
	dev_stats->rx_bytes = 0;

	dev_stats->tx_bytes = 0;

	dev_stats->tx_dropped = 0;

	dev_stats->rx_dropped = 0;



	for_each_online_cpu(cpu) {

		stats = per_cpu_ptr(priv->stats, cpu);
@@ -219,6 +233,7 @@ static struct net_device_stats *veth_get_stats(struct net_device *dev) 
		dev_stats->rx_bytes += stats->rx_bytes;

		dev_stats->tx_bytes += stats->tx_bytes;

		dev_stats->tx_dropped += stats->tx_dropped;

		dev_stats->rx_dropped += stats->rx_dropped;

	}



	return dev_stats;
@@ -249,6 +264,19 @@ static int veth_close(struct net_device *dev) 
	return 0;

}



static int is_valid_veth_mtu(int new_mtu)

{

	return (new_mtu >= MIN_MTU && new_mtu <= MAX_MTU);

}



static int veth_change_mtu(struct net_device *dev, int new_mtu)

{

	if (!is_valid_veth_mtu(new_mtu))

		return -EINVAL;

	dev->mtu = new_mtu;

	return 0;

}



static int veth_dev_init(struct net_device *dev)

{

	struct veth_net_stats *stats;
@@ -277,6 +305,7 @@ static const struct net_device_ops veth_netdev_ops = { 
	.ndo_open            = veth_open,

	.ndo_stop            = veth_close,

	.ndo_start_xmit      = veth_xmit,

	.ndo_change_mtu      = veth_change_mtu,

	.ndo_get_stats       = veth_get_stats,

	.ndo_set_mac_address = eth_mac_addr,

};
@@ -303,6 +332,10 @@ static int veth_validate(struct nlattr *tb[], struct nlattr *data[]) 
		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))

			return -EADDRNOTAVAIL;

	}

	if (tb[IFLA_MTU]) {

		if (!is_valid_veth_mtu(nla_get_u32(tb[IFLA_MTU])))

			return -EINVAL;

	}

	return 0;

}

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