summaryrefslogtreecommitdiff
path: root/samples/bpf/xdp_tx_iptunnel_kern.c
blob: 0f4f6e8c8611e3dea0e758215a65cc185ecdae02 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
/* Copyright (c) 2016 Facebook
 *
 * 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 shows how to use bpf_xdp_adjust_head() by
 * encapsulating the incoming packet in an IPv4/v6 header
 * and then XDP_TX it out.
 */
#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"
#include "xdp_tx_iptunnel_common.h"

struct bpf_map_def SEC("maps") rxcnt = {
	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
	.key_size = sizeof(__u32),
	.value_size = sizeof(__u64),
	.max_entries = 256,
};

struct bpf_map_def SEC("maps") vip2tnl = {
	.type = BPF_MAP_TYPE_HASH,
	.key_size = sizeof(struct vip),
	.value_size = sizeof(struct iptnl_info),
	.max_entries = MAX_IPTNL_ENTRIES,
};

static __always_inline void count_tx(u32 protocol)
{
	u64 *rxcnt_count;

	rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
	if (rxcnt_count)
		*rxcnt_count += 1;
}

static __always_inline int get_dport(void *trans_data, void *data_end,
				     u8 protocol)
{
	struct tcphdr *th;
	struct udphdr *uh;

	switch (protocol) {
	case IPPROTO_TCP:
		th = (struct tcphdr *)trans_data;
		if (th + 1 > data_end)
			return -1;
		return th->dest;
	case IPPROTO_UDP:
		uh = (struct udphdr *)trans_data;
		if (uh + 1 > data_end)
			return -1;
		return uh->dest;
	default:
		return 0;
	}
}

static __always_inline void set_ethhdr(struct ethhdr *new_eth,
				       const struct ethhdr *old_eth,
				       const struct iptnl_info *tnl,
				       __be16 h_proto)
{
	memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
	memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
	new_eth->h_proto = h_proto;
}

static __always_inline int handle_ipv4(struct xdp_md *xdp)
{
	void *data_end = (void *)(long)xdp->data_end;
	void *data = (void *)(long)xdp->data;
	struct iptnl_info *tnl;
	struct ethhdr *new_eth;
	struct ethhdr *old_eth;
	struct iphdr *iph = data + sizeof(struct ethhdr);
	u16 *next_iph_u16;
	u16 payload_len;
	struct vip vip = {};
	int dport;
	u32 csum = 0;
	int i;

	if (iph + 1 > data_end)
		return XDP_DROP;

	dport = get_dport(iph + 1, data_end, iph->protocol);
	if (dport == -1)
		return XDP_DROP;

	vip.protocol = iph->protocol;
	vip.family = AF_INET;
	vip.daddr.v4 = iph->daddr;
	vip.dport = dport;
	payload_len = ntohs(iph->tot_len);

	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
	/* It only does v4-in-v4 */
	if (!tnl || tnl->family != AF_INET)
		return XDP_PASS;

	/* The vip key is found.  Add an IP header and send it out */

	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
		return XDP_DROP;

	data = (void *)(long)xdp->data;
	data_end = (void *)(long)xdp->data_end;

	new_eth = data;
	iph = data + sizeof(*new_eth);
	old_eth = data + sizeof(*iph);

	if (new_eth + 1 > data_end ||
	    old_eth + 1 > data_end ||
	    iph + 1 > data_end)
		return XDP_DROP;

	set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IP));

	iph->version = 4;
	iph->ihl = sizeof(*iph) >> 2;
	iph->frag_off =	0;
	iph->protocol = IPPROTO_IPIP;
	iph->check = 0;
	iph->tos = 0;
	iph->tot_len = htons(payload_len + sizeof(*iph));
	iph->daddr = tnl->daddr.v4;
	iph->saddr = tnl->saddr.v4;
	iph->ttl = 8;

	next_iph_u16 = (u16 *)iph;
#pragma clang loop unroll(full)
	for (i = 0; i < sizeof(*iph) >> 1; i++)
		csum += *next_iph_u16++;

	iph->check = ~((csum & 0xffff) + (csum >> 16));

	count_tx(vip.protocol);

	return XDP_TX;
}

static __always_inline int handle_ipv6(struct xdp_md *xdp)
{
	void *data_end = (void *)(long)xdp->data_end;
	void *data = (void *)(long)xdp->data;
	struct iptnl_info *tnl;
	struct ethhdr *new_eth;
	struct ethhdr *old_eth;
	struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
	__u16 payload_len;
	struct vip vip = {};
	int dport;

	if (ip6h + 1 > data_end)
		return XDP_DROP;

	dport = get_dport(ip6h + 1, data_end, ip6h->nexthdr);
	if (dport == -1)
		return XDP_DROP;

	vip.protocol = ip6h->nexthdr;
	vip.family = AF_INET6;
	memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
	vip.dport = dport;
	payload_len = ip6h->payload_len;

	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
	/* It only does v6-in-v6 */
	if (!tnl || tnl->family != AF_INET6)
		return XDP_PASS;

	/* The vip key is found.  Add an IP header and send it out */

	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
		return XDP_DROP;

	data = (void *)(long)xdp->data;
	data_end = (void *)(long)xdp->data_end;

	new_eth = data;
	ip6h = data + sizeof(*new_eth);
	old_eth = data + sizeof(*ip6h);

	if (new_eth + 1 > data_end ||
	    old_eth + 1 > data_end ||
	    ip6h + 1 > data_end)
		return XDP_DROP;

	set_ethhdr(new_eth, old_eth, tnl, htons(ETH_P_IPV6));

	ip6h->version = 6;
	ip6h->priority = 0;
	memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
	ip6h->payload_len = htons(ntohs(payload_len) + sizeof(*ip6h));
	ip6h->nexthdr = IPPROTO_IPV6;
	ip6h->hop_limit = 8;
	memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
	memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));

	count_tx(vip.protocol);

	return XDP_TX;
}

SEC("xdp_tx_iptunnel")
int _xdp_tx_iptunnel(struct xdp_md *xdp)
{
	void *data_end = (void *)(long)xdp->data_end;
	void *data = (void *)(long)xdp->data;
	struct ethhdr *eth = data;
	__u16 h_proto;

	if (eth + 1 > data_end)
		return XDP_DROP;

	h_proto = eth->h_proto;

	if (h_proto == htons(ETH_P_IP))
		return handle_ipv4(xdp);
	else if (h_proto == htons(ETH_P_IPV6))

		return handle_ipv6(xdp);
	else
		return XDP_PASS;
}

char _license[] SEC("license") = "GPL";