nlmon.c 2.9 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. #include <linux/module.h>
  3. #include <linux/kernel.h>
  4. #include <linux/netdevice.h>
  5. #include <linux/netlink.h>
  6. #include <net/net_namespace.h>
  7. #include <linux/if_arp.h>
  8. #include <net/rtnetlink.h>
  9. static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
  10. {
  11. dev_lstats_add(dev, skb->len);
  12. dev_kfree_skb(skb);
  13. return NETDEV_TX_OK;
  14. }
  15. static int nlmon_dev_init(struct net_device *dev)
  16. {
  17. dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  18. return dev->lstats == NULL ? -ENOMEM : 0;
  19. }
  20. static void nlmon_dev_uninit(struct net_device *dev)
  21. {
  22. free_percpu(dev->lstats);
  23. }
  24. struct nlmon {
  25. struct netlink_tap nt;
  26. };
  27. static int nlmon_open(struct net_device *dev)
  28. {
  29. struct nlmon *nlmon = netdev_priv(dev);
  30. nlmon->nt.dev = dev;
  31. nlmon->nt.module = THIS_MODULE;
  32. return netlink_add_tap(&nlmon->nt);
  33. }
  34. static int nlmon_close(struct net_device *dev)
  35. {
  36. struct nlmon *nlmon = netdev_priv(dev);
  37. return netlink_remove_tap(&nlmon->nt);
  38. }
  39. static void
  40. nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  41. {
  42. u64 packets, bytes;
  43. dev_lstats_read(dev, &packets, &bytes);
  44. stats->rx_packets = packets;
  45. stats->tx_packets = 0;
  46. stats->rx_bytes = bytes;
  47. stats->tx_bytes = 0;
  48. }
  49. static u32 always_on(struct net_device *dev)
  50. {
  51. return 1;
  52. }
  53. static const struct ethtool_ops nlmon_ethtool_ops = {
  54. .get_link = always_on,
  55. };
  56. static const struct net_device_ops nlmon_ops = {
  57. .ndo_init = nlmon_dev_init,
  58. .ndo_uninit = nlmon_dev_uninit,
  59. .ndo_open = nlmon_open,
  60. .ndo_stop = nlmon_close,
  61. .ndo_start_xmit = nlmon_xmit,
  62. .ndo_get_stats64 = nlmon_get_stats64,
  63. };
  64. static void nlmon_setup(struct net_device *dev)
  65. {
  66. dev->type = ARPHRD_NETLINK;
  67. dev->priv_flags |= IFF_NO_QUEUE;
  68. dev->netdev_ops = &nlmon_ops;
  69. dev->ethtool_ops = &nlmon_ethtool_ops;
  70. dev->needs_free_netdev = true;
  71. dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
  72. NETIF_F_HIGHDMA | NETIF_F_LLTX;
  73. dev->flags = IFF_NOARP;
  74. /* That's rather a softlimit here, which, of course,
  75. * can be altered. Not a real MTU, but what is to be
  76. * expected in most cases.
  77. */
  78. dev->mtu = NLMSG_GOODSIZE;
  79. dev->min_mtu = sizeof(struct nlmsghdr);
  80. }
  81. static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
  82. struct netlink_ext_ack *extack)
  83. {
  84. if (tb[IFLA_ADDRESS])
  85. return -EINVAL;
  86. return 0;
  87. }
  88. static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
  89. .kind = "nlmon",
  90. .priv_size = sizeof(struct nlmon),
  91. .setup = nlmon_setup,
  92. .validate = nlmon_validate,
  93. };
  94. static __init int nlmon_register(void)
  95. {
  96. return rtnl_link_register(&nlmon_link_ops);
  97. }
  98. static __exit void nlmon_unregister(void)
  99. {
  100. rtnl_link_unregister(&nlmon_link_ops);
  101. }
  102. module_init(nlmon_register);
  103. module_exit(nlmon_unregister);
  104. MODULE_LICENSE("GPL v2");
  105. MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
  106. MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
  107. MODULE_DESCRIPTION("Netlink monitoring device");
  108. MODULE_ALIAS_RTNL_LINK("nlmon");