/* Copyright (c) 2016 PLUMgrid * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #define KBUILD_MODNAME "foo" #include <uapi/linux/bpf.h> #include <linux/in.h> #include <linux/if_ether.h> #include <linux/if_packet.h> #include <linux/if_vlan.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <bpf/bpf_helpers.h> struct { __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); __type(key, u32); __type(value, long); __uint(max_entries, 256); } rxcnt SEC(".maps"); static void swap_src_dst_mac(void *data) { unsigned short *p = data; unsigned short dst[3]; dst[0] = p[0]; dst[1] = p[1]; dst[2] = p[2]; p[0] = p[3]; p[1] = p[4]; p[2] = p[5]; p[3] = dst[0]; p[4] = dst[1]; p[5] = dst[2]; } static int parse_ipv4(void *data, u64 nh_off, void *data_end) { struct iphdr *iph = data + nh_off; if (iph + 1 > data_end) return 0; return iph->protocol; } static int parse_ipv6(void *data, u64 nh_off, void *data_end) { struct ipv6hdr *ip6h = data + nh_off; if (ip6h + 1 > data_end) return 0; return ip6h->nexthdr; } SEC("xdp1") int xdp_prog1(struct xdp_md *ctx) { void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; struct ethhdr *eth = data; int rc = XDP_DROP; long *value; u16 h_proto; u64 nh_off; u32 ipproto; nh_off = sizeof(*eth); if (data + nh_off > data_end) return rc; h_proto = eth->h_proto; if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return rc; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return rc; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == htons(ETH_P_IP)) ipproto = parse_ipv4(data, nh_off, data_end); else if (h_proto == htons(ETH_P_IPV6)) ipproto = parse_ipv6(data, nh_off, data_end); else ipproto = 0; value = bpf_map_lookup_elem(&rxcnt, &ipproto); if (value) *value += 1; if (ipproto == IPPROTO_UDP) { swap_src_dst_mac(data); rc = XDP_TX; } return rc; } char _license[] SEC("license") = "GPL";