LXR linux/samples/bpf/xdp1

   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
  17struct {
  18        __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
  19        __type(key, u32);
  20        __type(value, long);
  21        __uint(max_entries, 256);
  22} rxcnt SEC(".maps");
  23
  24static int parse_ipv4(void *data, u64 nh_off, void *data_end)
  25{
  26        struct iphdr *iph = data + nh_off;
  27
  28        if (iph + 1 > data_end)
  29                return 0;
  30        return iph->protocol;
  31}
  32
  33static int parse_ipv6(void *data, u64 nh_off, void *data_end)
  34{
  35        struct ipv6hdr *ip6h = data + nh_off;
  36
  37        if (ip6h + 1 > data_end)
  38                return 0;
  39        return ip6h->nexthdr;
  40}
  41
  42SEC("xdp1")
  43int xdp_prog1(struct xdp_md *ctx)
  44{
  45        void *data_end = (void *)(long)ctx->data_end;
  46        void *data = (void *)(long)ctx->data;
  47        struct ethhdr *eth = data;
  48        int rc = XDP_DROP;
  49        long *value;
  50        u16 h_proto;
  51        u64 nh_off;
  52        u32 ipproto;
  53
  54        nh_off = sizeof(*eth);
  55        if (data + nh_off > data_end)
  56                return rc;
  57
  58        h_proto = eth->h_proto;
  59
  60        /* Handle VLAN tagged packet */
  61        if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  62                struct vlan_hdr *vhdr;
  63
  64                vhdr = data + nh_off;
  65                nh_off += sizeof(struct vlan_hdr);
  66                if (data + nh_off > data_end)
  67                        return rc;
  68                h_proto = vhdr->h_vlan_encapsulated_proto;
  69        }
  70        /* Handle double VLAN tagged packet */
  71        if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  72                struct vlan_hdr *vhdr;
  73
  74                vhdr = data + nh_off;
  75                nh_off += sizeof(struct vlan_hdr);
  76                if (data + nh_off > data_end)
  77                        return rc;
  78                h_proto = vhdr->h_vlan_encapsulated_proto;
  79        }
  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
  88        value = bpf_map_lookup_elem(&rxcnt, &ipproto);
  89        if (value)
  90                *value += 1;
  91
  92        return rc;
  93}
  94
  95char _license[] SEC("license") = "GPL";
  96