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
  8#include "vmlinux.h"
  9#include "xdp_sample.bpf.h"
 10#include "xdp_sample_shared.h"
 11
 12#define ETH_ALEN	6
 13#define ETH_P_8021Q	0x8100
 14#define ETH_P_8021AD	0x88A8
 15
 16struct trie_value {
 17	__u8 prefix[4];
 18	__be64 value;
 19	int ifindex;
 20	int metric;
 21	__be32 gw;
 22};
 23
 24/* Key for lpm_trie */
 25union key_4 {
 26	u32 b32[2];
 27	u8 b8[8];
 28};
 29
 30struct arp_entry {
 31	__be64 mac;
 32	__be32 dst;
 33};
 34
 35struct direct_map {
 36	struct arp_entry arp;
 37	int ifindex;
 38	__be64 mac;
 39};
 40
 41/* Map for trie implementation */
 42struct {
 43	__uint(type, BPF_MAP_TYPE_LPM_TRIE);
 44	__uint(key_size, 8);
 45	__uint(value_size, sizeof(struct trie_value));
 46	__uint(max_entries, 50);
 47	__uint(map_flags, BPF_F_NO_PREALLOC);
 48} lpm_map SEC(".maps");
 49
 50/* Map for ARP table */
 51struct {
 52	__uint(type, BPF_MAP_TYPE_HASH);
 53	__type(key, __be32);
 54	__type(value, __be64);
 55	__uint(max_entries, 50);
 56} arp_table SEC(".maps");
 57
 58/* Map to keep the exact match entries in the route table */
 59struct {
 60	__uint(type, BPF_MAP_TYPE_HASH);
 61	__type(key, __be32);
 62	__type(value, struct direct_map);
 63	__uint(max_entries, 50);
 64} exact_match SEC(".maps");
 65
 66struct {
 67	__uint(type, BPF_MAP_TYPE_DEVMAP);
 68	__uint(key_size, sizeof(int));
 69	__uint(value_size, sizeof(int));
 70	__uint(max_entries, 100);
 71} tx_port SEC(".maps");
 72
 73SEC("xdp")
 74int xdp_router_ipv4_prog(struct xdp_md *ctx)
 75{
 76	void *data_end = (void *)(long)ctx->data_end;
 77	void *data = (void *)(long)ctx->data;
 78	struct ethhdr *eth = data;
 79	u64 nh_off = sizeof(*eth);
 80	struct datarec *rec;
 81	__be16 h_proto;
 82	u32 key = 0;
 83
 84	rec = bpf_map_lookup_elem(&rx_cnt, &key);
 85	if (rec)
 86		NO_TEAR_INC(rec->processed);
 87
 88	if (data + nh_off > data_end)
 89		goto drop;
 90
 91	h_proto = eth->h_proto;
 92	if (h_proto == bpf_htons(ETH_P_8021Q) ||
 93	    h_proto == bpf_htons(ETH_P_8021AD)) {
 94		struct vlan_hdr *vhdr;
 95
 96		vhdr = data + nh_off;
 97		nh_off += sizeof(struct vlan_hdr);
 98		if (data + nh_off > data_end)
 99			goto drop;
100
101		h_proto = vhdr->h_vlan_encapsulated_proto;
102	}
103
104	switch (bpf_ntohs(h_proto)) {
105	case ETH_P_ARP:
106		if (rec)
107			NO_TEAR_INC(rec->xdp_pass);
108		return XDP_PASS;
109	case ETH_P_IP: {
110		struct iphdr *iph = data + nh_off;
111		struct direct_map *direct_entry;
112		__be64 *dest_mac, *src_mac;
113		int forward_to;
114
115		if (iph + 1 > data_end)
116			goto drop;
117
118		direct_entry = bpf_map_lookup_elem(&exact_match, &iph->daddr);
119
120		/* Check for exact match, this would give a faster lookup */
121		if (direct_entry && direct_entry->mac &&
122		    direct_entry->arp.mac) {
123			src_mac = &direct_entry->mac;
124			dest_mac = &direct_entry->arp.mac;
125			forward_to = direct_entry->ifindex;
126		} else {
127			struct trie_value *prefix_value;
128			union key_4 key4;
129
130			/* Look up in the trie for lpm */
131			key4.b32[0] = 32;
132			key4.b8[4] = iph->daddr & 0xff;
133			key4.b8[5] = (iph->daddr >> 8) & 0xff;
134			key4.b8[6] = (iph->daddr >> 16) & 0xff;
135			key4.b8[7] = (iph->daddr >> 24) & 0xff;
136
137			prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
138			if (!prefix_value)
139				goto drop;
140
141			forward_to = prefix_value->ifindex;
142			src_mac = &prefix_value->value;
143			if (!src_mac)
144				goto drop;
145
146			dest_mac = bpf_map_lookup_elem(&arp_table, &iph->daddr);
147			if (!dest_mac) {
148				if (!prefix_value->gw)
149					goto drop;
150
151				dest_mac = bpf_map_lookup_elem(&arp_table,
152							       &prefix_value->gw);
153				if (!dest_mac) {
154					/* Forward the packet to the kernel in
155					 * order to trigger ARP discovery for
156					 * the default gw.
157					 */
158					if (rec)
159						NO_TEAR_INC(rec->xdp_pass);
160					return XDP_PASS;
161				}
162			}
163		}
164
165		if (src_mac && dest_mac) {
166			int ret;
167
168			__builtin_memcpy(eth->h_dest, dest_mac, ETH_ALEN);
169			__builtin_memcpy(eth->h_source, src_mac, ETH_ALEN);
170
171			ret = bpf_redirect_map(&tx_port, forward_to, 0);
172			if (ret == XDP_REDIRECT) {
173				if (rec)
174					NO_TEAR_INC(rec->xdp_redirect);
175				return ret;
176			}
177		}
178	}
179	default:
180		break;
181	}
182drop:
183	if (rec)
184		NO_TEAR_INC(rec->xdp_drop);
185
186	return XDP_DROP;
187}
188
189char _license[] SEC("license") = "GPL";