1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2017 Facebook
3#include <stddef.h>
4#include <stdbool.h>
5#include <string.h>
6#include <linux/pkt_cls.h>
7#include <linux/bpf.h>
8#include <linux/in.h>
9#include <linux/if_ether.h>
10#include <linux/ip.h>
11#include <linux/ipv6.h>
12#include <linux/icmp.h>
13#include <linux/icmpv6.h>
14#include <linux/tcp.h>
15#include <linux/udp.h>
16#include <bpf/bpf_helpers.h>
17#include "test_iptunnel_common.h"
18#include <bpf/bpf_endian.h>
19
20#include "bpf_kfuncs.h"
21
22static __always_inline __u32 rol32(__u32 word, unsigned int shift)
23{
24	return (word << shift) | (word >> ((-shift) & 31));
25}
26
27/* copy paste of jhash from kernel sources to make sure llvm
28 * can compile it into valid sequence of bpf instructions
29 */
30#define __jhash_mix(a, b, c)			\
31{						\
32	a -= c;  a ^= rol32(c, 4);  c += b;	\
33	b -= a;  b ^= rol32(a, 6);  a += c;	\
34	c -= b;  c ^= rol32(b, 8);  b += a;	\
35	a -= c;  a ^= rol32(c, 16); c += b;	\
36	b -= a;  b ^= rol32(a, 19); a += c;	\
37	c -= b;  c ^= rol32(b, 4);  b += a;	\
38}
39
40#define __jhash_final(a, b, c)			\
41{						\
42	c ^= b; c -= rol32(b, 14);		\
43	a ^= c; a -= rol32(c, 11);		\
44	b ^= a; b -= rol32(a, 25);		\
45	c ^= b; c -= rol32(b, 16);		\
46	a ^= c; a -= rol32(c, 4);		\
47	b ^= a; b -= rol32(a, 14);		\
48	c ^= b; c -= rol32(b, 24);		\
49}
50
51#define JHASH_INITVAL		0xdeadbeef
52
53typedef unsigned int u32;
54
55static __noinline u32 jhash(const void *key, u32 length, u32 initval)
56{
57	u32 a, b, c;
58	const unsigned char *k = key;
59
60	a = b = c = JHASH_INITVAL + length + initval;
61
62	while (length > 12) {
63		a += *(u32 *)(k);
64		b += *(u32 *)(k + 4);
65		c += *(u32 *)(k + 8);
66		__jhash_mix(a, b, c);
67		length -= 12;
68		k += 12;
69	}
70	switch (length) {
71	case 12: c += (u32)k[11]<<24;
72	case 11: c += (u32)k[10]<<16;
73	case 10: c += (u32)k[9]<<8;
74	case 9:  c += k[8];
75	case 8:  b += (u32)k[7]<<24;
76	case 7:  b += (u32)k[6]<<16;
77	case 6:  b += (u32)k[5]<<8;
78	case 5:  b += k[4];
79	case 4:  a += (u32)k[3]<<24;
80	case 3:  a += (u32)k[2]<<16;
81	case 2:  a += (u32)k[1]<<8;
82	case 1:  a += k[0];
83		 __jhash_final(a, b, c);
84	case 0: /* Nothing left to add */
85		break;
86	}
87
88	return c;
89}
90
91static __noinline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
92{
93	a += initval;
94	b += initval;
95	c += initval;
96	__jhash_final(a, b, c);
97	return c;
98}
99
100static __noinline u32 jhash_2words(u32 a, u32 b, u32 initval)
101{
102	return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
103}
104
105#define PCKT_FRAGMENTED 65343
106#define IPV4_HDR_LEN_NO_OPT 20
107#define IPV4_PLUS_ICMP_HDR 28
108#define IPV6_PLUS_ICMP_HDR 48
109#define RING_SIZE 2
110#define MAX_VIPS 12
111#define MAX_REALS 5
112#define CTL_MAP_SIZE 16
113#define CH_RINGS_SIZE (MAX_VIPS * RING_SIZE)
114#define F_IPV6 (1 << 0)
115#define F_HASH_NO_SRC_PORT (1 << 0)
116#define F_ICMP (1 << 0)
117#define F_SYN_SET (1 << 1)
118
119struct packet_description {
120	union {
121		__be32 src;
122		__be32 srcv6[4];
123	};
124	union {
125		__be32 dst;
126		__be32 dstv6[4];
127	};
128	union {
129		__u32 ports;
130		__u16 port16[2];
131	};
132	__u8 proto;
133	__u8 flags;
134};
135
136struct ctl_value {
137	union {
138		__u64 value;
139		__u32 ifindex;
140		__u8 mac[6];
141	};
142};
143
144struct vip_meta {
145	__u32 flags;
146	__u32 vip_num;
147};
148
149struct real_definition {
150	union {
151		__be32 dst;
152		__be32 dstv6[4];
153	};
154	__u8 flags;
155};
156
157struct vip_stats {
158	__u64 bytes;
159	__u64 pkts;
160};
161
162struct eth_hdr {
163	unsigned char eth_dest[ETH_ALEN];
164	unsigned char eth_source[ETH_ALEN];
165	unsigned short eth_proto;
166};
167
168struct {
169	__uint(type, BPF_MAP_TYPE_HASH);
170	__uint(max_entries, MAX_VIPS);
171	__type(key, struct vip);
172	__type(value, struct vip_meta);
173} vip_map SEC(".maps");
174
175struct {
176	__uint(type, BPF_MAP_TYPE_ARRAY);
177	__uint(max_entries, CH_RINGS_SIZE);
178	__type(key, __u32);
179	__type(value, __u32);
180} ch_rings SEC(".maps");
181
182struct {
183	__uint(type, BPF_MAP_TYPE_ARRAY);
184	__uint(max_entries, MAX_REALS);
185	__type(key, __u32);
186	__type(value, struct real_definition);
187} reals SEC(".maps");
188
189struct {
190	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
191	__uint(max_entries, MAX_VIPS);
192	__type(key, __u32);
193	__type(value, struct vip_stats);
194} stats SEC(".maps");
195
196struct {
197	__uint(type, BPF_MAP_TYPE_ARRAY);
198	__uint(max_entries, CTL_MAP_SIZE);
199	__type(key, __u32);
200	__type(value, struct ctl_value);
201} ctl_array SEC(".maps");
202
203static __noinline __u32 get_packet_hash(struct packet_description *pckt, bool ipv6)
204{
205	if (ipv6)
206		return jhash_2words(jhash(pckt->srcv6, 16, MAX_VIPS),
207				    pckt->ports, CH_RINGS_SIZE);
208	else
209		return jhash_2words(pckt->src, pckt->ports, CH_RINGS_SIZE);
210}
211
212static __noinline bool get_packet_dst(struct real_definition **real,
213				      struct packet_description *pckt,
214				      struct vip_meta *vip_info,
215				      bool is_ipv6)
216{
217	__u32 hash = get_packet_hash(pckt, is_ipv6);
218	__u32 key = RING_SIZE * vip_info->vip_num + hash % RING_SIZE;
219	__u32 *real_pos;
220
221	if (hash != 0x358459b7 /* jhash of ipv4 packet */  &&
222	    hash != 0x2f4bc6bb /* jhash of ipv6 packet */)
223		return false;
224
225	real_pos = bpf_map_lookup_elem(&ch_rings, &key);
226	if (!real_pos)
227		return false;
228	key = *real_pos;
229	*real = bpf_map_lookup_elem(&reals, &key);
230	if (!(*real))
231		return false;
232	return true;
233}
234
235static __noinline int parse_icmpv6(struct bpf_dynptr *skb_ptr, __u64 off,
236				   struct packet_description *pckt)
237{
238	__u8 buffer[sizeof(struct ipv6hdr)] = {};
239	struct icmp6hdr *icmp_hdr;
240	struct ipv6hdr *ip6h;
241
242	icmp_hdr = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
243	if (!icmp_hdr)
244		return TC_ACT_SHOT;
245
246	if (icmp_hdr->icmp6_type != ICMPV6_PKT_TOOBIG)
247		return TC_ACT_OK;
248	off += sizeof(struct icmp6hdr);
249	ip6h = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
250	if (!ip6h)
251		return TC_ACT_SHOT;
252	pckt->proto = ip6h->nexthdr;
253	pckt->flags |= F_ICMP;
254	memcpy(pckt->srcv6, ip6h->daddr.s6_addr32, 16);
255	memcpy(pckt->dstv6, ip6h->saddr.s6_addr32, 16);
256	return TC_ACT_UNSPEC;
257}
258
259static __noinline int parse_icmp(struct bpf_dynptr *skb_ptr, __u64 off,
260				 struct packet_description *pckt)
261{
262	__u8 buffer_icmp[sizeof(struct iphdr)] = {};
263	__u8 buffer_ip[sizeof(struct iphdr)] = {};
264	struct icmphdr *icmp_hdr;
265	struct iphdr *iph;
266
267	icmp_hdr = bpf_dynptr_slice(skb_ptr, off, buffer_icmp, sizeof(buffer_icmp));
268	if (!icmp_hdr)
269		return TC_ACT_SHOT;
270	if (icmp_hdr->type != ICMP_DEST_UNREACH ||
271	    icmp_hdr->code != ICMP_FRAG_NEEDED)
272		return TC_ACT_OK;
273	off += sizeof(struct icmphdr);
274	iph = bpf_dynptr_slice(skb_ptr, off, buffer_ip, sizeof(buffer_ip));
275	if (!iph || iph->ihl != 5)
276		return TC_ACT_SHOT;
277	pckt->proto = iph->protocol;
278	pckt->flags |= F_ICMP;
279	pckt->src = iph->daddr;
280	pckt->dst = iph->saddr;
281	return TC_ACT_UNSPEC;
282}
283
284static __noinline bool parse_udp(struct bpf_dynptr *skb_ptr, __u64 off,
285				 struct packet_description *pckt)
286{
287	__u8 buffer[sizeof(struct udphdr)] = {};
288	struct udphdr *udp;
289
290	udp = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
291	if (!udp)
292		return false;
293
294	if (!(pckt->flags & F_ICMP)) {
295		pckt->port16[0] = udp->source;
296		pckt->port16[1] = udp->dest;
297	} else {
298		pckt->port16[0] = udp->dest;
299		pckt->port16[1] = udp->source;
300	}
301	return true;
302}
303
304static __noinline bool parse_tcp(struct bpf_dynptr *skb_ptr, __u64 off,
305				 struct packet_description *pckt)
306{
307	__u8 buffer[sizeof(struct tcphdr)] = {};
308	struct tcphdr *tcp;
309
310	tcp = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
311	if (!tcp)
312		return false;
313
314	if (tcp->syn)
315		pckt->flags |= F_SYN_SET;
316
317	if (!(pckt->flags & F_ICMP)) {
318		pckt->port16[0] = tcp->source;
319		pckt->port16[1] = tcp->dest;
320	} else {
321		pckt->port16[0] = tcp->dest;
322		pckt->port16[1] = tcp->source;
323	}
324	return true;
325}
326
327static __noinline int process_packet(struct bpf_dynptr *skb_ptr,
328				     struct eth_hdr *eth, __u64 off,
329				     bool is_ipv6, struct __sk_buff *skb)
330{
331	struct packet_description pckt = {};
332	struct bpf_tunnel_key tkey = {};
333	struct vip_stats *data_stats;
334	struct real_definition *dst;
335	struct vip_meta *vip_info;
336	struct ctl_value *cval;
337	__u32 v4_intf_pos = 1;
338	__u32 v6_intf_pos = 2;
339	struct ipv6hdr *ip6h;
340	struct vip vip = {};
341	struct iphdr *iph;
342	int tun_flag = 0;
343	__u16 pkt_bytes;
344	__u64 iph_len;
345	__u32 ifindex;
346	__u8 protocol;
347	__u32 vip_num;
348	int action;
349
350	tkey.tunnel_ttl = 64;
351	if (is_ipv6) {
352		__u8 buffer[sizeof(struct ipv6hdr)] = {};
353
354		ip6h = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
355		if (!ip6h)
356			return TC_ACT_SHOT;
357
358		iph_len = sizeof(struct ipv6hdr);
359		protocol = ip6h->nexthdr;
360		pckt.proto = protocol;
361		pkt_bytes = bpf_ntohs(ip6h->payload_len);
362		off += iph_len;
363		if (protocol == IPPROTO_FRAGMENT) {
364			return TC_ACT_SHOT;
365		} else if (protocol == IPPROTO_ICMPV6) {
366			action = parse_icmpv6(skb_ptr, off, &pckt);
367			if (action >= 0)
368				return action;
369			off += IPV6_PLUS_ICMP_HDR;
370		} else {
371			memcpy(pckt.srcv6, ip6h->saddr.s6_addr32, 16);
372			memcpy(pckt.dstv6, ip6h->daddr.s6_addr32, 16);
373		}
374	} else {
375		__u8 buffer[sizeof(struct iphdr)] = {};
376
377		iph = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer));
378		if (!iph || iph->ihl != 5)
379			return TC_ACT_SHOT;
380
381		protocol = iph->protocol;
382		pckt.proto = protocol;
383		pkt_bytes = bpf_ntohs(iph->tot_len);
384		off += IPV4_HDR_LEN_NO_OPT;
385
386		if (iph->frag_off & PCKT_FRAGMENTED)
387			return TC_ACT_SHOT;
388		if (protocol == IPPROTO_ICMP) {
389			action = parse_icmp(skb_ptr, off, &pckt);
390			if (action >= 0)
391				return action;
392			off += IPV4_PLUS_ICMP_HDR;
393		} else {
394			pckt.src = iph->saddr;
395			pckt.dst = iph->daddr;
396		}
397	}
398	protocol = pckt.proto;
399
400	if (protocol == IPPROTO_TCP) {
401		if (!parse_tcp(skb_ptr, off, &pckt))
402			return TC_ACT_SHOT;
403	} else if (protocol == IPPROTO_UDP) {
404		if (!parse_udp(skb_ptr, off, &pckt))
405			return TC_ACT_SHOT;
406	} else {
407		return TC_ACT_SHOT;
408	}
409
410	if (is_ipv6)
411		memcpy(vip.daddr.v6, pckt.dstv6, 16);
412	else
413		vip.daddr.v4 = pckt.dst;
414
415	vip.dport = pckt.port16[1];
416	vip.protocol = pckt.proto;
417	vip_info = bpf_map_lookup_elem(&vip_map, &vip);
418	if (!vip_info) {
419		vip.dport = 0;
420		vip_info = bpf_map_lookup_elem(&vip_map, &vip);
421		if (!vip_info)
422			return TC_ACT_SHOT;
423		pckt.port16[1] = 0;
424	}
425
426	if (vip_info->flags & F_HASH_NO_SRC_PORT)
427		pckt.port16[0] = 0;
428
429	if (!get_packet_dst(&dst, &pckt, vip_info, is_ipv6))
430		return TC_ACT_SHOT;
431
432	if (dst->flags & F_IPV6) {
433		cval = bpf_map_lookup_elem(&ctl_array, &v6_intf_pos);
434		if (!cval)
435			return TC_ACT_SHOT;
436		ifindex = cval->ifindex;
437		memcpy(tkey.remote_ipv6, dst->dstv6, 16);
438		tun_flag = BPF_F_TUNINFO_IPV6;
439	} else {
440		cval = bpf_map_lookup_elem(&ctl_array, &v4_intf_pos);
441		if (!cval)
442			return TC_ACT_SHOT;
443		ifindex = cval->ifindex;
444		tkey.remote_ipv4 = dst->dst;
445	}
446	vip_num = vip_info->vip_num;
447	data_stats = bpf_map_lookup_elem(&stats, &vip_num);
448	if (!data_stats)
449		return TC_ACT_SHOT;
450	data_stats->pkts++;
451	data_stats->bytes += pkt_bytes;
452	bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), tun_flag);
453	*(u32 *)eth->eth_dest = tkey.remote_ipv4;
454	return bpf_redirect(ifindex, 0);
455}
456
457SEC("tc")
458int balancer_ingress(struct __sk_buff *ctx)
459{
460	__u8 buffer[sizeof(struct eth_hdr)] = {};
461	struct bpf_dynptr ptr;
462	struct eth_hdr *eth;
463	__u32 eth_proto;
464	__u32 nh_off;
465	int err;
466
467	nh_off = sizeof(struct eth_hdr);
468
469	bpf_dynptr_from_skb(ctx, 0, &ptr);
470	eth = bpf_dynptr_slice_rdwr(&ptr, 0, buffer, sizeof(buffer));
471	if (!eth)
472		return TC_ACT_SHOT;
473	eth_proto = eth->eth_proto;
474	if (eth_proto == bpf_htons(ETH_P_IP))
475		err = process_packet(&ptr, eth, nh_off, false, ctx);
476	else if (eth_proto == bpf_htons(ETH_P_IPV6))
477		err = process_packet(&ptr, eth, nh_off, true, ctx);
478	else
479		return TC_ACT_SHOT;
480
481	if (eth == buffer)
482		bpf_dynptr_write(&ptr, 0, buffer, sizeof(buffer), 0);
483
484	return err;
485}
486
487char _license[] SEC("license") = "GPL";
488