1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2022 Meta */
  3#include <stddef.h>
  4#include <string.h>
  5#include <stdbool.h>
  6#include <linux/bpf.h>
  7#include <linux/if_ether.h>
  8#include <linux/if_packet.h>
  9#include <linux/ip.h>
 10#include <linux/ipv6.h>
 11#include <linux/in.h>
 12#include <linux/udp.h>
 13#include <linux/tcp.h>
 14#include <linux/pkt_cls.h>
 15#include <sys/socket.h>
 16#include <bpf/bpf_helpers.h>
 17#include <bpf/bpf_endian.h>
 18#include "test_iptunnel_common.h"
 19#include "bpf_kfuncs.h"
 20
 21#define tcphdr_sz sizeof(struct tcphdr)
 22#define udphdr_sz sizeof(struct udphdr)
 23#define ethhdr_sz sizeof(struct ethhdr)
 24#define iphdr_sz sizeof(struct iphdr)
 25#define ipv6hdr_sz sizeof(struct ipv6hdr)
 26
 27struct {
 28	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
 29	__uint(max_entries, 256);
 30	__type(key, __u32);
 31	__type(value, __u64);
 32} rxcnt SEC(".maps");
 33
 34struct {
 35	__uint(type, BPF_MAP_TYPE_HASH);
 36	__uint(max_entries, MAX_IPTNL_ENTRIES);
 37	__type(key, struct vip);
 38	__type(value, struct iptnl_info);
 39} vip2tnl SEC(".maps");
 40
 41static __always_inline void count_tx(__u32 protocol)
 42{
 43	__u64 *rxcnt_count;
 44
 45	rxcnt_count = bpf_map_lookup_elem(&rxcnt, &protocol);
 46	if (rxcnt_count)
 47		*rxcnt_count += 1;
 48}
 49
 50static __always_inline int get_dport(void *trans_data, __u8 protocol)
 51{
 52	struct tcphdr *th;
 53	struct udphdr *uh;
 54
 55	switch (protocol) {
 56	case IPPROTO_TCP:
 57		th = (struct tcphdr *)trans_data;
 58		return th->dest;
 59	case IPPROTO_UDP:
 60		uh = (struct udphdr *)trans_data;
 61		return uh->dest;
 62	default:
 63		return 0;
 64	}
 65}
 66
 67static __always_inline void set_ethhdr(struct ethhdr *new_eth,
 68				       const struct ethhdr *old_eth,
 69				       const struct iptnl_info *tnl,
 70				       __be16 h_proto)
 71{
 72	memcpy(new_eth->h_source, old_eth->h_dest, sizeof(new_eth->h_source));
 73	memcpy(new_eth->h_dest, tnl->dmac, sizeof(new_eth->h_dest));
 74	new_eth->h_proto = h_proto;
 75}
 76
 77static __always_inline int handle_ipv4(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
 78{
 79	__u8 eth_buffer[ethhdr_sz + iphdr_sz + ethhdr_sz];
 80	__u8 iph_buffer_tcp[iphdr_sz + tcphdr_sz];
 81	__u8 iph_buffer_udp[iphdr_sz + udphdr_sz];
 82	struct bpf_dynptr new_xdp_ptr;
 83	struct iptnl_info *tnl;
 84	struct ethhdr *new_eth;
 85	struct ethhdr *old_eth;
 86	struct iphdr *iph;
 87	__u16 *next_iph;
 88	__u16 payload_len;
 89	struct vip vip = {};
 90	int dport;
 91	__u32 csum = 0;
 92	int i;
 93
 94	__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
 95	__builtin_memset(iph_buffer_tcp, 0, sizeof(iph_buffer_tcp));
 96	__builtin_memset(iph_buffer_udp, 0, sizeof(iph_buffer_udp));
 97
 98	if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
 99		iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_udp, sizeof(iph_buffer_udp));
100	else
101		iph = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, iph_buffer_tcp, sizeof(iph_buffer_tcp));
102
103	if (!iph)
104		return XDP_DROP;
105
106	dport = get_dport(iph + 1, iph->protocol);
107	if (dport == -1)
108		return XDP_DROP;
109
110	vip.protocol = iph->protocol;
111	vip.family = AF_INET;
112	vip.daddr.v4 = iph->daddr;
113	vip.dport = dport;
114	payload_len = bpf_ntohs(iph->tot_len);
115
116	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
117	/* It only does v4-in-v4 */
118	if (!tnl || tnl->family != AF_INET)
119		return XDP_PASS;
120
121	if (bpf_xdp_adjust_head(xdp, 0 - (int)iphdr_sz))
122		return XDP_DROP;
123
124	bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
125	new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
126	if (!new_eth)
127		return XDP_DROP;
128
129	iph = (struct iphdr *)(new_eth + 1);
130	old_eth = (struct ethhdr *)(iph + 1);
131
132	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IP));
133
134	if (new_eth == eth_buffer)
135		bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
136
137	iph->version = 4;
138	iph->ihl = iphdr_sz >> 2;
139	iph->frag_off =	0;
140	iph->protocol = IPPROTO_IPIP;
141	iph->check = 0;
142	iph->tos = 0;
143	iph->tot_len = bpf_htons(payload_len + iphdr_sz);
144	iph->daddr = tnl->daddr.v4;
145	iph->saddr = tnl->saddr.v4;
146	iph->ttl = 8;
147
148	next_iph = (__u16 *)iph;
149	for (i = 0; i < iphdr_sz >> 1; i++)
150		csum += *next_iph++;
151
152	iph->check = ~((csum & 0xffff) + (csum >> 16));
153
154	count_tx(vip.protocol);
155
156	return XDP_TX;
157}
158
159static __always_inline int handle_ipv6(struct xdp_md *xdp, struct bpf_dynptr *xdp_ptr)
160{
161	__u8 eth_buffer[ethhdr_sz + ipv6hdr_sz + ethhdr_sz];
162	__u8 ip6h_buffer_tcp[ipv6hdr_sz + tcphdr_sz];
163	__u8 ip6h_buffer_udp[ipv6hdr_sz + udphdr_sz];
164	struct bpf_dynptr new_xdp_ptr;
165	struct iptnl_info *tnl;
166	struct ethhdr *new_eth;
167	struct ethhdr *old_eth;
168	struct ipv6hdr *ip6h;
169	__u16 payload_len;
170	struct vip vip = {};
171	int dport;
172
173	__builtin_memset(eth_buffer, 0, sizeof(eth_buffer));
174	__builtin_memset(ip6h_buffer_tcp, 0, sizeof(ip6h_buffer_tcp));
175	__builtin_memset(ip6h_buffer_udp, 0, sizeof(ip6h_buffer_udp));
176
177	if (ethhdr_sz + iphdr_sz + tcphdr_sz > xdp->data_end - xdp->data)
178		ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_udp, sizeof(ip6h_buffer_udp));
179	else
180		ip6h = bpf_dynptr_slice(xdp_ptr, ethhdr_sz, ip6h_buffer_tcp, sizeof(ip6h_buffer_tcp));
181
182	if (!ip6h)
183		return XDP_DROP;
184
185	dport = get_dport(ip6h + 1, ip6h->nexthdr);
186	if (dport == -1)
187		return XDP_DROP;
188
189	vip.protocol = ip6h->nexthdr;
190	vip.family = AF_INET6;
191	memcpy(vip.daddr.v6, ip6h->daddr.s6_addr32, sizeof(vip.daddr));
192	vip.dport = dport;
193	payload_len = ip6h->payload_len;
194
195	tnl = bpf_map_lookup_elem(&vip2tnl, &vip);
196	/* It only does v6-in-v6 */
197	if (!tnl || tnl->family != AF_INET6)
198		return XDP_PASS;
199
200	if (bpf_xdp_adjust_head(xdp, 0 - (int)ipv6hdr_sz))
201		return XDP_DROP;
202
203	bpf_dynptr_from_xdp(xdp, 0, &new_xdp_ptr);
204	new_eth = bpf_dynptr_slice_rdwr(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer));
205	if (!new_eth)
206		return XDP_DROP;
207
208	ip6h = (struct ipv6hdr *)(new_eth + 1);
209	old_eth = (struct ethhdr *)(ip6h + 1);
210
211	set_ethhdr(new_eth, old_eth, tnl, bpf_htons(ETH_P_IPV6));
212
213	if (new_eth == eth_buffer)
214		bpf_dynptr_write(&new_xdp_ptr, 0, eth_buffer, sizeof(eth_buffer), 0);
215
216	ip6h->version = 6;
217	ip6h->priority = 0;
218	memset(ip6h->flow_lbl, 0, sizeof(ip6h->flow_lbl));
219	ip6h->payload_len = bpf_htons(bpf_ntohs(payload_len) + ipv6hdr_sz);
220	ip6h->nexthdr = IPPROTO_IPV6;
221	ip6h->hop_limit = 8;
222	memcpy(ip6h->saddr.s6_addr32, tnl->saddr.v6, sizeof(tnl->saddr.v6));
223	memcpy(ip6h->daddr.s6_addr32, tnl->daddr.v6, sizeof(tnl->daddr.v6));
224
225	count_tx(vip.protocol);
226
227	return XDP_TX;
228}
229
230SEC("xdp")
231int _xdp_tx_iptunnel(struct xdp_md *xdp)
232{
233	__u8 buffer[ethhdr_sz];
234	struct bpf_dynptr ptr;
235	struct ethhdr *eth;
236	__u16 h_proto;
237
238	__builtin_memset(buffer, 0, sizeof(buffer));
239
240	bpf_dynptr_from_xdp(xdp, 0, &ptr);
241	eth = bpf_dynptr_slice(&ptr, 0, buffer, sizeof(buffer));
242	if (!eth)
243		return XDP_DROP;
244
245	h_proto = eth->h_proto;
246
247	if (h_proto == bpf_htons(ETH_P_IP))
248		return handle_ipv4(xdp, &ptr);
249	else if (h_proto == bpf_htons(ETH_P_IPV6))
250
251		return handle_ipv6(xdp, &ptr);
252	else
253		return XDP_DROP;
254}
255
256char _license[] SEC("license") = "GPL";