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/* Copyright (C) 2017 Cavium, Inc.
*
* 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>
#include <linux/slab.h>
#include <net/ip_fib.h>
struct trie_value {
__u8 prefix[4];
__be64 value;
int ifindex;
int metric;
__be32 gw;
};
/* Key for lpm_trie*/
union key_4 {
u32 b32[2];
u8 b8[8];
};
struct arp_entry {
__be64 mac;
__be32 dst;
};
struct direct_map {
struct arp_entry arp;
int ifindex;
__be64 mac;
};
/* Map for trie implementation*/
struct {
__uint(type, BPF_MAP_TYPE_LPM_TRIE);
__uint(key_size, 8);
__uint(value_size, sizeof(struct trie_value));
__uint(max_entries, 50);
__uint(map_flags, BPF_F_NO_PREALLOC);
} lpm_map SEC(".maps");
/* Map for counter*/
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__type(key, u32);
__type(value, u64);
__uint(max_entries, 256);
} rxcnt SEC(".maps");
/* Map for ARP table*/
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, __be32);
__type(value, __be64);
__uint(max_entries, 50);
} arp_table SEC(".maps");
/* Map to keep the exact match entries in the route table*/
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, __be32);
__type(value, struct direct_map);
__uint(max_entries, 50);
} exact_match SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_DEVMAP);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(int));
__uint(max_entries, 100);
} tx_port SEC(".maps");
/* Function to set source and destination mac of the packet */
static inline void set_src_dst_mac(void *data, void *src, void *dst)
{
unsigned short *source = src;
unsigned short *dest = dst;
unsigned short *p = data;
__builtin_memcpy(p, dest, 6);
__builtin_memcpy(p + 3, source, 6);
}
/* Parse IPV4 packet to get SRC, DST IP and protocol */
static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
__be32 *src, __be32 *dest)
{
struct iphdr *iph = data + nh_off;
if (iph + 1 > data_end)
return 0;
*src = iph->saddr;
*dest = iph->daddr;
return iph->protocol;
}
SEC("xdp_router_ipv4")
int xdp_router_ipv4_prog(struct xdp_md *ctx)
{
void *data_end = (void *)(long)ctx->data_end;
__be64 *dest_mac = NULL, *src_mac = NULL;
void *data = (void *)(long)ctx->data;
struct trie_value *prefix_value;
int rc = XDP_DROP, forward_to;
struct ethhdr *eth = data;
union key_4 key4;
long *value;
u16 h_proto;
u32 ipproto;
u64 nh_off;
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_ARP)) {
return XDP_PASS;
} else if (h_proto == htons(ETH_P_IP)) {
struct direct_map *direct_entry;
__be32 src_ip = 0, dest_ip = 0;
ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
/* Check for exact match, this would give a faster lookup*/
if (direct_entry && direct_entry->mac && direct_entry->arp.mac) {
src_mac = &direct_entry->mac;
dest_mac = &direct_entry->arp.mac;
forward_to = direct_entry->ifindex;
} else {
/* Look up in the trie for lpm*/
key4.b32[0] = 32;
key4.b8[4] = dest_ip & 0xff;
key4.b8[5] = (dest_ip >> 8) & 0xff;
key4.b8[6] = (dest_ip >> 16) & 0xff;
key4.b8[7] = (dest_ip >> 24) & 0xff;
prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
if (!prefix_value)
return XDP_DROP;
src_mac = &prefix_value->value;
if (!src_mac)
return XDP_DROP;
dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
if (!dest_mac) {
if (!prefix_value->gw)
return XDP_DROP;
dest_ip = prefix_value->gw;
dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
}
forward_to = prefix_value->ifindex;
}
} else {
ipproto = 0;
}
if (src_mac && dest_mac) {
set_src_dst_mac(data, src_mac, dest_mac);
value = bpf_map_lookup_elem(&rxcnt, &ipproto);
if (value)
*value += 1;
return bpf_redirect_map(&tx_port, forward_to, 0);
}
return rc;
}
char _license[] SEC("license") = "GPL";
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