xdp2_kern.c 2.6 KB

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  1. /* Copyright (c) 2016 PLUMgrid
  2. *
  3. * This program is free software; you can redistribute it and/or
  4. * modify it under the terms of version 2 of the GNU General Public
  5. * License as published by the Free Software Foundation.
  6. */
  7. #define KBUILD_MODNAME "foo"
  8. #include <uapi/linux/bpf.h>
  9. #include <linux/in.h>
  10. #include <linux/if_ether.h>
  11. #include <linux/if_packet.h>
  12. #include <linux/if_vlan.h>
  13. #include <linux/ip.h>
  14. #include <linux/ipv6.h>
  15. #include <bpf/bpf_helpers.h>
  16. struct {
  17. __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  18. __type(key, u32);
  19. __type(value, long);
  20. __uint(max_entries, 256);
  21. } rxcnt SEC(".maps");
  22. static void swap_src_dst_mac(void *data)
  23. {
  24. unsigned short *p = data;
  25. unsigned short dst[3];
  26. dst[0] = p[0];
  27. dst[1] = p[1];
  28. dst[2] = p[2];
  29. p[0] = p[3];
  30. p[1] = p[4];
  31. p[2] = p[5];
  32. p[3] = dst[0];
  33. p[4] = dst[1];
  34. p[5] = dst[2];
  35. }
  36. static int parse_ipv4(void *data, u64 nh_off, void *data_end)
  37. {
  38. struct iphdr *iph = data + nh_off;
  39. if (iph + 1 > data_end)
  40. return 0;
  41. return iph->protocol;
  42. }
  43. static int parse_ipv6(void *data, u64 nh_off, void *data_end)
  44. {
  45. struct ipv6hdr *ip6h = data + nh_off;
  46. if (ip6h + 1 > data_end)
  47. return 0;
  48. return ip6h->nexthdr;
  49. }
  50. #define XDPBUFSIZE 60
  51. SEC("xdp.frags")
  52. int xdp_prog1(struct xdp_md *ctx)
  53. {
  54. __u8 pkt[XDPBUFSIZE] = {};
  55. void *data_end = &pkt[XDPBUFSIZE-1];
  56. void *data = pkt;
  57. struct ethhdr *eth = data;
  58. int rc = XDP_DROP;
  59. long *value;
  60. u16 h_proto;
  61. u64 nh_off;
  62. u32 ipproto;
  63. if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
  64. return rc;
  65. nh_off = sizeof(*eth);
  66. if (data + nh_off > data_end)
  67. return rc;
  68. h_proto = eth->h_proto;
  69. /* Handle VLAN tagged packet */
  70. if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  71. struct vlan_hdr *vhdr;
  72. vhdr = data + nh_off;
  73. nh_off += sizeof(struct vlan_hdr);
  74. if (data + nh_off > data_end)
  75. return rc;
  76. h_proto = vhdr->h_vlan_encapsulated_proto;
  77. }
  78. /* Handle double VLAN tagged packet */
  79. if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  80. struct vlan_hdr *vhdr;
  81. vhdr = data + nh_off;
  82. nh_off += sizeof(struct vlan_hdr);
  83. if (data + nh_off > data_end)
  84. return rc;
  85. h_proto = vhdr->h_vlan_encapsulated_proto;
  86. }
  87. if (h_proto == htons(ETH_P_IP))
  88. ipproto = parse_ipv4(data, nh_off, data_end);
  89. else if (h_proto == htons(ETH_P_IPV6))
  90. ipproto = parse_ipv6(data, nh_off, data_end);
  91. else
  92. ipproto = 0;
  93. value = bpf_map_lookup_elem(&rxcnt, &ipproto);
  94. if (value)
  95. *value += 1;
  96. if (ipproto == IPPROTO_UDP) {
  97. swap_src_dst_mac(data);
  98. if (bpf_xdp_store_bytes(ctx, 0, pkt, sizeof(pkt)))
  99. return rc;
  100. rc = XDP_TX;
  101. }
  102. return rc;
  103. }
  104. char _license[] SEC("license") = "GPL";