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