182 lines
3.9 KiB
C
182 lines
3.9 KiB
C
#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/netlink.h>
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#include <net/net_namespace.h>
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#include <linux/if_arp.h>
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#include <net/rtnetlink.h>
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struct pcpu_lstats {
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u64 packets;
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u64 bytes;
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struct u64_stats_sync syncp;
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};
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static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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int len = skb->len;
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struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
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u64_stats_update_begin(&stats->syncp);
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stats->bytes += len;
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stats->packets++;
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u64_stats_update_end(&stats->syncp);
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dev_kfree_skb(skb);
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return NETDEV_TX_OK;
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}
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static int nlmon_is_valid_mtu(int new_mtu)
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{
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/* Note that in netlink we do not really have an upper limit. On
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* default, we use NLMSG_GOODSIZE. Here at least we should make
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* sure that it's at least the header size.
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*/
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return new_mtu >= (int) sizeof(struct nlmsghdr);
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}
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static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
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{
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if (!nlmon_is_valid_mtu(new_mtu))
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return -EINVAL;
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dev->mtu = new_mtu;
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return 0;
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}
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static int nlmon_dev_init(struct net_device *dev)
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{
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dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
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return dev->lstats == NULL ? -ENOMEM : 0;
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}
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static void nlmon_dev_uninit(struct net_device *dev)
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{
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free_percpu(dev->lstats);
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}
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struct nlmon {
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struct netlink_tap nt;
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};
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static int nlmon_open(struct net_device *dev)
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{
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struct nlmon *nlmon = netdev_priv(dev);
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nlmon->nt.dev = dev;
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nlmon->nt.module = THIS_MODULE;
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return netlink_add_tap(&nlmon->nt);
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}
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static int nlmon_close(struct net_device *dev)
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{
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struct nlmon *nlmon = netdev_priv(dev);
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return netlink_remove_tap(&nlmon->nt);
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}
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static struct rtnl_link_stats64 *
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nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
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{
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int i;
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u64 bytes = 0, packets = 0;
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for_each_possible_cpu(i) {
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const struct pcpu_lstats *nl_stats;
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u64 tbytes, tpackets;
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unsigned int start;
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nl_stats = per_cpu_ptr(dev->lstats, i);
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do {
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start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
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tbytes = nl_stats->bytes;
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tpackets = nl_stats->packets;
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} while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
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packets += tpackets;
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bytes += tbytes;
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}
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stats->rx_packets = packets;
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stats->tx_packets = 0;
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stats->rx_bytes = bytes;
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stats->tx_bytes = 0;
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return stats;
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}
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static u32 always_on(struct net_device *dev)
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{
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return 1;
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}
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static const struct ethtool_ops nlmon_ethtool_ops = {
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.get_link = always_on,
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};
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static const struct net_device_ops nlmon_ops = {
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.ndo_init = nlmon_dev_init,
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.ndo_uninit = nlmon_dev_uninit,
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.ndo_open = nlmon_open,
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.ndo_stop = nlmon_close,
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.ndo_start_xmit = nlmon_xmit,
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.ndo_get_stats64 = nlmon_get_stats64,
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.ndo_change_mtu = nlmon_change_mtu,
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};
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static void nlmon_setup(struct net_device *dev)
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{
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dev->type = ARPHRD_NETLINK;
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dev->tx_queue_len = 0;
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dev->netdev_ops = &nlmon_ops;
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dev->ethtool_ops = &nlmon_ethtool_ops;
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dev->destructor = free_netdev;
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dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
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NETIF_F_HIGHDMA | NETIF_F_LLTX;
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dev->flags = IFF_NOARP;
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/* That's rather a softlimit here, which, of course,
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* can be altered. Not a real MTU, but what is to be
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* expected in most cases.
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*/
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dev->mtu = NLMSG_GOODSIZE;
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}
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static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
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{
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if (tb[IFLA_ADDRESS])
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return -EINVAL;
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return 0;
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}
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static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
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.kind = "nlmon",
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.priv_size = sizeof(struct nlmon),
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.setup = nlmon_setup,
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.validate = nlmon_validate,
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};
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static __init int nlmon_register(void)
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{
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return rtnl_link_register(&nlmon_link_ops);
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}
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static __exit void nlmon_unregister(void)
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{
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rtnl_link_unregister(&nlmon_link_ops);
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}
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module_init(nlmon_register);
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module_exit(nlmon_unregister);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
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MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
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MODULE_DESCRIPTION("Netlink monitoring device");
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MODULE_ALIAS_RTNL_LINK("nlmon");
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