xdp2_kern.c 2.4 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. SEC("xdp1")
  51. int xdp_prog1(struct xdp_md *ctx)
  52. {
  53. void *data_end = (void *)(long)ctx->data_end;
  54. void *data = (void *)(long)ctx->data;
  55. struct ethhdr *eth = data;
  56. int rc = XDP_DROP;
  57. long *value;
  58. u16 h_proto;
  59. u64 nh_off;
  60. u32 ipproto;
  61. nh_off = sizeof(*eth);
  62. if (data + nh_off > data_end)
  63. return rc;
  64. h_proto = eth->h_proto;
  65. if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  66. struct vlan_hdr *vhdr;
  67. vhdr = data + nh_off;
  68. nh_off += sizeof(struct vlan_hdr);
  69. if (data + nh_off > data_end)
  70. return rc;
  71. h_proto = vhdr->h_vlan_encapsulated_proto;
  72. }
  73. if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  74. struct vlan_hdr *vhdr;
  75. vhdr = data + nh_off;
  76. nh_off += sizeof(struct vlan_hdr);
  77. if (data + nh_off > data_end)
  78. return rc;
  79. h_proto = vhdr->h_vlan_encapsulated_proto;
  80. }
  81. if (h_proto == htons(ETH_P_IP))
  82. ipproto = parse_ipv4(data, nh_off, data_end);
  83. else if (h_proto == htons(ETH_P_IPV6))
  84. ipproto = parse_ipv6(data, nh_off, data_end);
  85. else
  86. ipproto = 0;
  87. value = bpf_map_lookup_elem(&rxcnt, &ipproto);
  88. if (value)
  89. *value += 1;
  90. if (ipproto == IPPROTO_UDP) {
  91. swap_src_dst_mac(data);
  92. rc = XDP_TX;
  93. }
  94. return rc;
  95. }
  96. char _license[] SEC("license") = "GPL";