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Message-ID: <m1ab813ox1.fsf@fess.ebiederm.org>
Date: Tue, 03 Mar 2009 20:14:18 -0800
From: ebiederm@...ssion.com (Eric W. Biederman)
To: David Miller <davem@...emloft.net>
Cc: <netdev@...r.kernel.org>,
Linux Containers <containers@...ts.osdl.org>,
Daniel Lezcano <dlezcano@...ibm.com>,
Pavel Emelyanov <xemul@...nvz.org>
Subject: [PATCH] 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: Eric Biederman <ebiederm@...stanetworks.com>
---
drivers/net/veth.c | 45 +++++++++++++++++++++++++++++++++++++++------
1 files changed, 39 insertions(+), 6 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 124fe75..015db1c 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -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;
}
--
1.6.1.2.350.g88cc
--
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