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#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <net/net_namespace.h>
#include <linux/if_arp.h>
struct pcpu_lstats {
u64 packets;
u64 bytes;
struct u64_stats_sync syncp;
};
static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
{
int len = skb->len;
struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
u64_stats_update_begin(&stats->syncp);
stats->bytes += len;
stats->packets++;
u64_stats_update_end(&stats->syncp);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static int nlmon_is_valid_mtu(int new_mtu)
{
/* Note that in netlink we do not really have an upper limit. On
* default, we use NLMSG_GOODSIZE. Here at least we should make
* sure that it's at least the header size.
*/
return new_mtu >= (int) sizeof(struct nlmsghdr);
}
static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
{
if (!nlmon_is_valid_mtu(new_mtu))
return -EINVAL;
dev->mtu = new_mtu;
return 0;
}
static int nlmon_dev_init(struct net_device *dev)
{
dev->lstats = alloc_percpu(struct pcpu_lstats);
return dev->lstats == NULL ? -ENOMEM : 0;
}
static void nlmon_dev_uninit(struct net_device *dev)
{
free_percpu(dev->lstats);
}
static struct netlink_tap nlmon_tap;
static int nlmon_open(struct net_device *dev)
{
return netlink_add_tap(&nlmon_tap);
}
static int nlmon_close(struct net_device *dev)
{
return netlink_remove_tap(&nlmon_tap);
}
static struct rtnl_link_stats64 *
nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
{
int i;
u64 bytes = 0, packets = 0;
for_each_possible_cpu(i) {
const struct pcpu_lstats *nl_stats;
u64 tbytes, tpackets;
unsigned int start;
nl_stats = per_cpu_ptr(dev->lstats, i);
do {
start = u64_stats_fetch_begin_bh(&nl_stats->syncp);
tbytes = nl_stats->bytes;
tpackets = nl_stats->packets;
} while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start));
packets += tpackets;
bytes += tbytes;
}
stats->rx_packets = packets;
stats->tx_packets = 0;
stats->rx_bytes = bytes;
stats->tx_bytes = 0;
return stats;
}
static u32 always_on(struct net_device *dev)
{
return 1;
}
static const struct ethtool_ops nlmon_ethtool_ops = {
.get_link = always_on,
};
static const struct net_device_ops nlmon_ops = {
.ndo_init = nlmon_dev_init,
.ndo_uninit = nlmon_dev_uninit,
.ndo_open = nlmon_open,
.ndo_stop = nlmon_close,
.ndo_start_xmit = nlmon_xmit,
.ndo_get_stats64 = nlmon_get_stats64,
.ndo_change_mtu = nlmon_change_mtu,
};
static struct netlink_tap nlmon_tap __read_mostly = {
.module = THIS_MODULE,
};
static void nlmon_setup(struct net_device *dev)
{
dev->type = ARPHRD_NETLINK;
dev->tx_queue_len = 0;
dev->netdev_ops = &nlmon_ops;
dev->ethtool_ops = &nlmon_ethtool_ops;
dev->destructor = free_netdev;
dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;
dev->flags = IFF_NOARP;
/* That's rather a softlimit here, which, of course,
* can be altered. Not a real MTU, but what is to be
* expected in most cases.
*/
dev->mtu = NLMSG_GOODSIZE;
}
static __init int nlmon_register(void)
{
int err;
struct net_device *nldev;
nldev = nlmon_tap.dev = alloc_netdev(0, "netlink", nlmon_setup);
if (unlikely(nldev == NULL))
return -ENOMEM;
err = register_netdev(nldev);
if (unlikely(err))
free_netdev(nldev);
return err;
}
static __exit void nlmon_unregister(void)
{
struct net_device *nldev = nlmon_tap.dev;
unregister_netdev(nldev);
}
module_init(nlmon_register);
module_exit(nlmon_unregister);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
MODULE_DESCRIPTION("Netlink monitoring device");
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