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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.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_helpers.h"
#define IPV6_FLOWINFO_MASK cpu_to_be32(0x0FFFFFFF)
struct bpf_map_def SEC("maps") tx_port = {
.type = BPF_MAP_TYPE_DEVMAP,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 64,
};
static __always_inline int xdp_fwd_flags(struct xdp_md *ctx, u32 flags)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct bpf_fib_lookup fib_params;
struct ethhdr *eth = data;
int out_index;
u16 h_proto;
u64 nh_off;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return XDP_DROP;
__builtin_memset(&fib_params, 0, sizeof(fib_params));
h_proto = eth->h_proto;
if (h_proto == htons(ETH_P_IP)) {
struct iphdr *iph = data + nh_off;
if (iph + 1 > data_end)
return XDP_DROP;
fib_params.family = AF_INET;
fib_params.tos = iph->tos;
fib_params.l4_protocol = iph->protocol;
fib_params.sport = 0;
fib_params.dport = 0;
fib_params.tot_len = ntohs(iph->tot_len);
fib_params.ipv4_src = iph->saddr;
fib_params.ipv4_dst = iph->daddr;
} else if (h_proto == htons(ETH_P_IPV6)) {
struct in6_addr *src = (struct in6_addr *) fib_params.ipv6_src;
struct in6_addr *dst = (struct in6_addr *) fib_params.ipv6_dst;
struct ipv6hdr *iph = data + nh_off;
if (iph + 1 > data_end)
return XDP_DROP;
fib_params.family = AF_INET6;
fib_params.flowlabel = *(__be32 *)iph & IPV6_FLOWINFO_MASK;
fib_params.l4_protocol = iph->nexthdr;
fib_params.sport = 0;
fib_params.dport = 0;
fib_params.tot_len = ntohs(iph->payload_len);
*src = iph->saddr;
*dst = iph->daddr;
} else {
return XDP_PASS;
}
fib_params.ifindex = ctx->ingress_ifindex;
out_index = bpf_fib_lookup(ctx, &fib_params, sizeof(fib_params), flags);
/* verify egress index has xdp support
* TO-DO bpf_map_lookup_elem(&tx_port, &key) fails with
* cannot pass map_type 14 into func bpf_map_lookup_elem#1:
* NOTE: without verification that egress index supports XDP
* forwarding packets are dropped.
*/
if (out_index > 0) {
memcpy(eth->h_dest, fib_params.dmac, ETH_ALEN);
memcpy(eth->h_source, fib_params.smac, ETH_ALEN);
return bpf_redirect_map(&tx_port, out_index, 0);
}
return XDP_PASS;
}
SEC("xdp_fwd")
int xdp_fwd_prog(struct xdp_md *ctx)
{
return xdp_fwd_flags(ctx, 0);
}
SEC("xdp_fwd_direct")
int xdp_fwd_direct_prog(struct xdp_md *ctx)
{
return xdp_fwd_flags(ctx, BPF_FIB_LOOKUP_DIRECT);
}
char _license[] SEC("license") = "GPL";
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