1/* Copyright (C) 2017 Cavium, Inc.
  2 *
  3 * This program is free software; you can redistribute it and/or modify it
  4 * under the terms of version 2 of the GNU General Public License
  5 * as published by the Free Software Foundation.
  6 */
  7#define KBUILD_MODNAME "foo"
  8#include <uapi/linux/bpf.h>
  9#include <linux/in.h>
 10#include <linux/if_ether.h>
 11#include <linux/if_packet.h>
 12#include <linux/if_vlan.h>
 13#include <linux/ip.h>
 14#include <linux/ipv6.h>
 15#include <bpf/bpf_helpers.h>
 16#include <linux/slab.h>
 17#include <net/ip_fib.h>
 18
 19struct trie_value {
 20	__u8 prefix[4];
 21	__be64 value;
 22	int ifindex;
 23	int metric;
 24	__be32 gw;
 25};
 26
 27/* Key for lpm_trie*/
 28union key_4 {
 29	u32 b32[2];
 30	u8 b8[8];
 31};
 32
 33struct arp_entry {
 34	__be64 mac;
 35	__be32 dst;
 36};
 37
 38struct direct_map {
 39	struct arp_entry arp;
 40	int ifindex;
 41	__be64 mac;
 42};
 43
 44/* Map for trie implementation*/
 45struct {
 46	__uint(type, BPF_MAP_TYPE_LPM_TRIE);
 47	__uint(key_size, 8);
 48	__uint(value_size, sizeof(struct trie_value));
 49	__uint(max_entries, 50);
 50	__uint(map_flags, BPF_F_NO_PREALLOC);
 51} lpm_map SEC(".maps");
 52
 53/* Map for counter*/
 54struct {
 55	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
 56	__type(key, u32);
 57	__type(value, u64);
 58	__uint(max_entries, 256);
 59} rxcnt SEC(".maps");
 60
 61/* Map for ARP table*/
 62struct {
 63	__uint(type, BPF_MAP_TYPE_HASH);
 64	__type(key, __be32);
 65	__type(value, __be64);
 66	__uint(max_entries, 50);
 67} arp_table SEC(".maps");
 68
 69/* Map to keep the exact match entries in the route table*/
 70struct {
 71	__uint(type, BPF_MAP_TYPE_HASH);
 72	__type(key, __be32);
 73	__type(value, struct direct_map);
 74	__uint(max_entries, 50);
 75} exact_match SEC(".maps");
 76
 77struct {
 78	__uint(type, BPF_MAP_TYPE_DEVMAP);
 79	__uint(key_size, sizeof(int));
 80	__uint(value_size, sizeof(int));
 81	__uint(max_entries, 100);
 82} tx_port SEC(".maps");
 83
 84/* Function to set source and destination mac of the packet */
 85static inline void set_src_dst_mac(void *data, void *src, void *dst)
 86{
 87	unsigned short *source = src;
 88	unsigned short *dest  = dst;
 89	unsigned short *p = data;
 90
 91	__builtin_memcpy(p, dest, 6);
 92	__builtin_memcpy(p + 3, source, 6);
 93}
 94
 95/* Parse IPV4 packet to get SRC, DST IP and protocol */
 96static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
 97			     __be32 *src, __be32 *dest)
 98{
 99	struct iphdr *iph = data + nh_off;
100
101	if (iph + 1 > data_end)
102		return 0;
103	*src = iph->saddr;
104	*dest = iph->daddr;
105	return iph->protocol;
106}
107
108SEC("xdp_router_ipv4")
109int xdp_router_ipv4_prog(struct xdp_md *ctx)
110{
111	void *data_end = (void *)(long)ctx->data_end;
112	__be64 *dest_mac = NULL, *src_mac = NULL;
113	void *data = (void *)(long)ctx->data;
114	struct trie_value *prefix_value;
115	int rc = XDP_DROP, forward_to;
116	struct ethhdr *eth = data;
117	union key_4 key4;
118	long *value;
119	u16 h_proto;
120	u32 ipproto;
121	u64 nh_off;
122
123	nh_off = sizeof(*eth);
124	if (data + nh_off > data_end)
125		return rc;
126
127	h_proto = eth->h_proto;
128
129	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
130		struct vlan_hdr *vhdr;
131
132		vhdr = data + nh_off;
133		nh_off += sizeof(struct vlan_hdr);
134		if (data + nh_off > data_end)
135			return rc;
136		h_proto = vhdr->h_vlan_encapsulated_proto;
137	}
138	if (h_proto == htons(ETH_P_ARP)) {
139		return XDP_PASS;
140	} else if (h_proto == htons(ETH_P_IP)) {
141		struct direct_map *direct_entry;
142		__be32 src_ip = 0, dest_ip = 0;
143
144		ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
145		direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
146		/* Check for exact match, this would give a faster lookup*/
147		if (direct_entry && direct_entry->mac && direct_entry->arp.mac) {
148			src_mac = &direct_entry->mac;
149			dest_mac = &direct_entry->arp.mac;
150			forward_to = direct_entry->ifindex;
151		} else {
152			/* Look up in the trie for lpm*/
153			key4.b32[0] = 32;
154			key4.b8[4] = dest_ip & 0xff;
155			key4.b8[5] = (dest_ip >> 8) & 0xff;
156			key4.b8[6] = (dest_ip >> 16) & 0xff;
157			key4.b8[7] = (dest_ip >> 24) & 0xff;
158			prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
159			if (!prefix_value)
160				return XDP_DROP;
161			src_mac = &prefix_value->value;
162			if (!src_mac)
163				return XDP_DROP;
164			dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
165			if (!dest_mac) {
166				if (!prefix_value->gw)
167					return XDP_DROP;
168				dest_ip = prefix_value->gw;
169				dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
170			}
171			forward_to = prefix_value->ifindex;
172		}
173	} else {
174		ipproto = 0;
175	}
176	if (src_mac && dest_mac) {
177		set_src_dst_mac(data, src_mac, dest_mac);
178		value = bpf_map_lookup_elem(&rxcnt, &ipproto);
179		if (value)
180			*value += 1;
181		return  bpf_redirect_map(&tx_port, forward_to, 0);
182	}
183	return rc;
184}
185
186char _license[] SEC("license") = "GPL";