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/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
*
* 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>
/* The 2nd xdp prog on egress does not support skb mode, so we define two
* maps, tx_port_general and tx_port_native.
*/
struct {
__uint(type, BPF_MAP_TYPE_DEVMAP);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(int));
__uint(max_entries, 100);
} tx_port_general SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_DEVMAP);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(struct bpf_devmap_val));
__uint(max_entries, 100);
} tx_port_native 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");
/* map to store egress interface mac address */
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, __be64);
__uint(max_entries, 1);
} tx_mac 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 __always_inline int xdp_redirect_map(struct xdp_md *ctx, void *redirect_map)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct ethhdr *eth = data;
int rc = XDP_DROP;
long *value;
u32 key = 0;
u64 nh_off;
int vport;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return rc;
/* constant virtual port */
vport = 0;
/* count packet in global counter */
value = bpf_map_lookup_elem(&rxcnt, &key);
if (value)
*value += 1;
swap_src_dst_mac(data);
/* send packet out physical port */
return bpf_redirect_map(redirect_map, vport, 0);
}
SEC("xdp_redirect_general")
int xdp_redirect_map_general(struct xdp_md *ctx)
{
return xdp_redirect_map(ctx, &tx_port_general);
}
SEC("xdp_redirect_native")
int xdp_redirect_map_native(struct xdp_md *ctx)
{
return xdp_redirect_map(ctx, &tx_port_native);
}
SEC("xdp_devmap/map_prog")
int xdp_redirect_map_egress(struct xdp_md *ctx)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct ethhdr *eth = data;
__be64 *mac;
u32 key = 0;
u64 nh_off;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return XDP_DROP;
mac = bpf_map_lookup_elem(&tx_mac, &key);
if (mac)
__builtin_memcpy(eth->h_source, mac, ETH_ALEN);
return XDP_PASS;
}
/* 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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