1/* Copyright (c) 2016,2017 Facebook
  2 *
  3 * This program is free software; you can redistribute it and/or
  4 * modify it under the terms of version 2 of the GNU General Public
  5 * License as published by the Free Software Foundation.
  6 */
  7#include <stddef.h>
  8#include <string.h>
  9#include <linux/bpf.h>
 10#include <linux/if_ether.h>
 11#include <linux/if_packet.h>
 12#include <linux/ip.h>
 13#include <linux/ipv6.h>
 14#include <linux/in.h>
 15#include <linux/udp.h>
 16#include <linux/tcp.h>
 17#include <linux/pkt_cls.h>
 18#include <sys/socket.h>
 19#include "bpf_helpers.h"
 20#include "bpf_endian.h"
 21#include "test_iptunnel_common.h"
 22
 23int _version SEC("version") = 1;
 24
 25struct bpf_map_def SEC("maps") rxcnt = {
 26	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
 27	.key_size = sizeof(__u32),
 28	.value_size = sizeof(__u64),
 29	.max_entries = 256,
 30};
 31
 32struct bpf_map_def SEC("maps") vip2tnl = {
 33	.type = BPF_MAP_TYPE_HASH,
 34	.key_size = sizeof(struct vip),
 35	.value_size = sizeof(struct iptnl_info),
 36	.max_entries = MAX_IPTNL_ENTRIES,
 37};
 38
 39static __always_inline void count_tx(__u32 protocol)
 40{
 41	__u64 *rxcnt_count;
 42
 43	rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
 44	if (rxcnt_count)
 45		*rxcnt_count += 1;
 46}
 47
 48static __always_inline int get_dport(void *trans_data, void *data_end,
 49				     __u8 protocol)
 50{
 51	struct tcphdr *th;
 52	struct udphdr *uh;
 53
 54	switch (protocol) {
 55	case IPPROTO_TCP:
 56		th = (struct tcphdr *)trans_data;
 57		if (th + 1 > data_end)
 58			return -1;
 59		return th->dest;
 60	case IPPROTO_UDP:
 61		uh = (struct udphdr *)trans_data;
 62		if (uh + 1 > data_end)
 63			return -1;
 64		return uh->dest;
 65	default:
 66		return 0;
 67	}
 68}
 69
 70static __always_inline void set_ethhdr(struct ethhdr *new_eth,
 71				       const struct ethhdr *old_eth,
 72				       const struct iptnl_info *tnl,
 73				       __be16 h_proto)
 74{
 75	memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
 76	memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
 77	new_eth->h_proto = h_proto;
 78}
 79
 80static __always_inline int handle_ipv4(struct xdp_md *xdp)
 81{
 82	void *data_end = (void *)(long)xdp->data_end;
 83	void *data = (void *)(long)xdp->data;
 84	struct iptnl_info *tnl;
 85	struct ethhdr *new_eth;
 86	struct ethhdr *old_eth;
 87	struct iphdr *iph = data + sizeof(struct ethhdr);
 88	__u16 *next_iph;
 89	__u16 payload_len;
 90	struct vip vip = {};
 91	int dport;
 92	__u32 csum = 0;
 93	int i;
 94
 95	if (iph + 1 > data_end)
 96		return XDP_DROP;
 97
 98	dport = get_dport(iph + 1, data_end, iph->protocol);
 99	if (dport == -1)
100		return XDP_DROP;
101
102	vip.protocol = iph->protocol;
103	vip.family = AF_INET;
104	vip.daddr.v4 = iph->daddr;
105	vip.dport = dport;
106	payload_len = bpf_ntohs(iph->tot_len);
107
108	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
109	/* It only does v4-in-v4 */
110	if (!tnl || tnl->family != AF_INET)
111		return XDP_PASS;
112
113	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
114		return XDP_DROP;
115
116	data = (void *)(long)xdp->data;
117	data_end = (void *)(long)xdp->data_end;
118
119	new_eth = data;
120	iph = data + sizeof(*new_eth);
121	old_eth = data + sizeof(*iph);
122
123	if (new_eth + 1 > data_end ||
124	    old_eth + 1 > data_end ||
125	    iph + 1 > data_end)
126		return XDP_DROP;
127
128	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
129
130	iph->version = 4;
131	iph->ihl = sizeof(*iph) >> 2;
132	iph->frag_off =	0;
133	iph->protocol = IPPROTO_IPIP;
134	iph->check = 0;
135	iph->tos = 0;
136	iph->tot_len = bpf_htons(payload_len + sizeof(*iph));
137	iph->daddr = tnl->daddr.v4;
138	iph->saddr = tnl->saddr.v4;
139	iph->ttl = 8;
140
141	next_iph = (__u16 *)iph;
142#pragma clang loop unroll(full)
143	for (i = 0; i < sizeof(*iph) >> 1; i++)
144		csum += *next_iph++;
145
146	iph->check = ~((csum & 0xffff) + (csum >> 16));
147
148	count_tx(vip.protocol);
149
150	return XDP_TX;
151}
152
153static __always_inline int handle_ipv6(struct xdp_md *xdp)
154{
155	void *data_end = (void *)(long)xdp->data_end;
156	void *data = (void *)(long)xdp->data;
157	struct iptnl_info *tnl;
158	struct ethhdr *new_eth;
159	struct ethhdr *old_eth;
160	struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
161	__u16 payload_len;
162	struct vip vip = {};
163	int dport;
164
165	if (ip6h + 1 > data_end)
166		return XDP_DROP;
167
168	dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
169	if (dport == -1)
170		return XDP_DROP;
171
172	vip.protocol = ip6h->nexthdr;
173	vip.family = AF_INET6;
174	memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
175	vip.dport = dport;
176	payload_len = ip6h->payload_len;
177
178	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
179	/* It only does v6-in-v6 */
180	if (!tnl || tnl->family != AF_INET6)
181		return XDP_PASS;
182
183	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
184		return XDP_DROP;
185
186	data = (void *)(long)xdp->data;
187	data_end = (void *)(long)xdp->data_end;
188
189	new_eth = data;
190	ip6h = data + sizeof(*new_eth);
191	old_eth = data + sizeof(*ip6h);
192
193	if (new_eth + 1 > data_end || old_eth + 1 > data_end ||
194	    ip6h + 1 > data_end)
195		return XDP_DROP;
196
197	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
198
199	ip6h->version = 6;
200	ip6h->priority = 0;
201	memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
202	ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + sizeof(*ip6h));
203	ip6h->nexthdr = IPPROTO_IPV6;
204	ip6h->hop_limit = 8;
205	memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
206	memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
207
208	count_tx(vip.protocol);
209
210	return XDP_TX;
211}
212
213SEC("xdp_tx_iptunnel")
214int _xdp_tx_iptunnel(struct xdp_md *xdp)
215{
216	void *data_end = (void *)(long)xdp->data_end;
217	void *data = (void *)(long)xdp->data;
218	struct ethhdr *eth = data;
219	__u16 h_proto;
220
221	if (eth + 1 > data_end)
222		return XDP_DROP;
223
224	h_proto = eth->h_proto;
225
226	if (h_proto == bpf_htons(ETH_P_IP))
227		return handle_ipv4(xdp);
228	else if (h_proto == bpf_htons(ETH_P_IPV6))
229
230		return handle_ipv6(xdp);
231	else
232		return XDP_DROP;
233}
234
235char _license[] SEC("license") = "GPL";