samples/bpf/xdp1_kern.c

   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_helpers.h"
  16
  17 struct {
  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
  24 static 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
  33 static 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
  42 SEC("xdp1")
  43 int 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         if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  61                 struct vlan_hdr *vhdr;
  62
  63                 vhdr = data + nh_off;
  64                 nh_off += sizeof(struct vlan_hdr);
  65                 if (data + nh_off > data_end)
  66                         return rc;
  67                 h_proto = vhdr->h_vlan_encapsulated_proto;
  68         }
  69         if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  70                 struct vlan_hdr *vhdr;
  71
  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
  79         if (h_proto == htons(ETH_P_IP))
  80                 ipproto = parse_ipv4(data, nh_off, data_end);
  81         else if (h_proto == htons(ETH_P_IPV6))
  82                 ipproto = parse_ipv6(data, nh_off, data_end);
  83         else
  84                 ipproto = 0;
  85
  86         value = bpf_map_lookup_elem(&rxcnt, &ipproto);
  87         if (value)
  88                 *value += 1;
  89
  90         return rc;
  91 }
  92
  93 char _license[] SEC("license") = "GPL";