126 lines
2.6 KiB
C
126 lines
2.6 KiB
C
/* Copyright (c) 2016 PLUMgrid
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#define KBUILD_MODNAME "foo"
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#include <uapi/linux/bpf.h>
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#include <linux/in.h>
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#include <linux/if_ether.h>
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#include <linux/if_packet.h>
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#include <linux/if_vlan.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <bpf/bpf_helpers.h>
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__type(key, u32);
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__type(value, long);
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__uint(max_entries, 256);
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} rxcnt SEC(".maps");
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static void swap_src_dst_mac(void *data)
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{
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unsigned short *p = data;
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unsigned short dst[3];
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dst[0] = p[0];
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dst[1] = p[1];
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dst[2] = p[2];
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p[0] = p[3];
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p[1] = p[4];
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p[2] = p[5];
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p[3] = dst[0];
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p[4] = dst[1];
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p[5] = dst[2];
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}
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static int parse_ipv4(void *data, u64 nh_off, void *data_end)
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{
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struct iphdr *iph = data + nh_off;
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if (iph + 1 > data_end)
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return 0;
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return iph->protocol;
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}
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static int parse_ipv6(void *data, u64 nh_off, void *data_end)
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{
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struct ipv6hdr *ip6h = data + nh_off;
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if (ip6h + 1 > data_end)
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return 0;
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return ip6h->nexthdr;
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}
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#define XDPBUFSIZE 60
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SEC("xdp.frags")
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int xdp_prog1(struct xdp_md *ctx)
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{
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__u8 pkt[XDPBUFSIZE] = {};
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void *data_end = &pkt[XDPBUFSIZE-1];
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void *data = pkt;
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struct ethhdr *eth = data;
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int rc = XDP_DROP;
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long *value;
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u16 h_proto;
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u64 nh_off;
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u32 ipproto;
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if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
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return rc;
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nh_off = sizeof(*eth);
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if (data + nh_off > data_end)
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return rc;
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h_proto = eth->h_proto;
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/* Handle VLAN tagged packet */
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if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
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struct vlan_hdr *vhdr;
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vhdr = data + nh_off;
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nh_off += sizeof(struct vlan_hdr);
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if (data + nh_off > data_end)
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return rc;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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/* Handle double VLAN tagged packet */
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if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
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struct vlan_hdr *vhdr;
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vhdr = data + nh_off;
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nh_off += sizeof(struct vlan_hdr);
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if (data + nh_off > data_end)
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return rc;
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h_proto = vhdr->h_vlan_encapsulated_proto;
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}
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if (h_proto == htons(ETH_P_IP))
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ipproto = parse_ipv4(data, nh_off, data_end);
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else if (h_proto == htons(ETH_P_IPV6))
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ipproto = parse_ipv6(data, nh_off, data_end);
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else
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ipproto = 0;
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value = bpf_map_lookup_elem(&rxcnt, &ipproto);
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if (value)
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*value += 1;
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if (ipproto == IPPROTO_UDP) {
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swap_src_dst_mac(data);
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if (bpf_xdp_store_bytes(ctx, 0, pkt, sizeof(pkt)))
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return rc;
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rc = XDP_TX;
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}
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return rc;
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}
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char _license[] SEC("license") = "GPL";
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