From 38d408152a86598a50680a82fe3353b506630409 Mon Sep 17 00:00:00 2001 From: Eric Biederman Date: Tue, 3 Mar 2009 23:36:04 -0800 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 Signed-off-by: David S. Miller --- drivers/net/veth.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 124fe75b8a8a..015db1cece72 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; } -- 2.30.2