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- /* Copyright (c) 2016 John Fastabend <john.r.fastabend@intel.com>
- *
- * 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.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- */
- #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_ARRAY);
- __type(key, int);
- __type(value, int);
- __uint(max_entries, 1);
- } tx_port SEC(".maps");
- /* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
- * feedback. Redirect TX errors can be caught via a tracepoint.
- */
- struct {
- __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
- __type(key, u32);
- __type(value, long);
- __uint(max_entries, 1);
- } 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];
- }
- SEC("xdp_redirect")
- int xdp_redirect_prog(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;
- int *ifindex, port = 0;
- long *value;
- u32 key = 0;
- u64 nh_off;
- nh_off = sizeof(*eth);
- if (data + nh_off > data_end)
- return rc;
- ifindex = bpf_map_lookup_elem(&tx_port, &port);
- if (!ifindex)
- return rc;
- value = bpf_map_lookup_elem(&rxcnt, &key);
- if (value)
- *value += 1;
- swap_src_dst_mac(data);
- return bpf_redirect(*ifindex, 0);
- }
- /* Redirect require an XDP bpf_prog loaded on the TX device */
- SEC("xdp_redirect_dummy")
- int xdp_redirect_dummy_prog(struct xdp_md *ctx)
- {
- return XDP_PASS;
- }
- char _license[] SEC("license") = "GPL";
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