1 /* Copyright (c) 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 <stdbool.h>
9 #include <string.h>
10 #include <linux/pkt_cls.h>
11 #include <linux/bpf.h>
12 #include <linux/in.h>
13 #include <linux/if_ether.h>
14 #include <linux/ip.h>
15 #include <linux/ipv6.h>
16 #include <linux/icmp.h>
17 #include <linux/icmpv6.h>
18 #include <linux/tcp.h>
19 #include <linux/udp.h>
20 #include <bpf/bpf_helpers.h>
21 #include "test_iptunnel_common.h"
22 #include <bpf/bpf_endian.h>
23
24 int _version SEC("version") = 1;
25
rol32(__u32 word,unsigned int shift)26 static inline __u32 rol32(__u32 word, unsigned int shift)
27 {
28 return (word << shift) | (word >> ((-shift) & 31));
29 }
30
31 /* copy paste of jhash from kernel sources to make sure llvm
32 * can compile it into valid sequence of bpf instructions
33 */
34 #define __jhash_mix(a, b, c) \
35 { \
36 a -= c; a ^= rol32(c, 4); c += b; \
37 b -= a; b ^= rol32(a, 6); a += c; \
38 c -= b; c ^= rol32(b, 8); b += a; \
39 a -= c; a ^= rol32(c, 16); c += b; \
40 b -= a; b ^= rol32(a, 19); a += c; \
41 c -= b; c ^= rol32(b, 4); b += a; \
42 }
43
44 #define __jhash_final(a, b, c) \
45 { \
46 c ^= b; c -= rol32(b, 14); \
47 a ^= c; a -= rol32(c, 11); \
48 b ^= a; b -= rol32(a, 25); \
49 c ^= b; c -= rol32(b, 16); \
50 a ^= c; a -= rol32(c, 4); \
51 b ^= a; b -= rol32(a, 14); \
52 c ^= b; c -= rol32(b, 24); \
53 }
54
55 #define JHASH_INITVAL 0xdeadbeef
56
57 typedef unsigned int u32;
58
jhash(const void * key,u32 length,u32 initval)59 static inline u32 jhash(const void *key, u32 length, u32 initval)
60 {
61 u32 a, b, c;
62 const unsigned char *k = key;
63
64 a = b = c = JHASH_INITVAL + length + initval;
65
66 while (length > 12) {
67 a += *(u32 *)(k);
68 b += *(u32 *)(k + 4);
69 c += *(u32 *)(k + 8);
70 __jhash_mix(a, b, c);
71 length -= 12;
72 k += 12;
73 }
74 switch (length) {
75 case 12: c += (u32)k[11]<<24;
76 case 11: c += (u32)k[10]<<16;
77 case 10: c += (u32)k[9]<<8;
78 case 9: c += k[8];
79 case 8: b += (u32)k[7]<<24;
80 case 7: b += (u32)k[6]<<16;
81 case 6: b += (u32)k[5]<<8;
82 case 5: b += k[4];
83 case 4: a += (u32)k[3]<<24;
84 case 3: a += (u32)k[2]<<16;
85 case 2: a += (u32)k[1]<<8;
86 case 1: a += k[0];
87 __jhash_final(a, b, c);
88 case 0: /* Nothing left to add */
89 break;
90 }
91
92 return c;
93 }
94
__jhash_nwords(u32 a,u32 b,u32 c,u32 initval)95 static inline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
96 {
97 a += initval;
98 b += initval;
99 c += initval;
100 __jhash_final(a, b, c);
101 return c;
102 }
103
jhash_2words(u32 a,u32 b,u32 initval)104 static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
105 {
106 return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
107 }
108
109 #define PCKT_FRAGMENTED 65343
110 #define IPV4_HDR_LEN_NO_OPT 20
111 #define IPV4_PLUS_ICMP_HDR 28
112 #define IPV6_PLUS_ICMP_HDR 48
113 #define RING_SIZE 2
114 #define MAX_VIPS 12
115 #define MAX_REALS 5
116 #define CTL_MAP_SIZE 16
117 #define CH_RINGS_SIZE (MAX_VIPS * RING_SIZE)
118 #define F_IPV6 (1 << 0)
119 #define F_HASH_NO_SRC_PORT (1 << 0)
120 #define F_ICMP (1 << 0)
121 #define F_SYN_SET (1 << 1)
122
123 struct packet_description {
124 union {
125 __be32 src;
126 __be32 srcv6[4];
127 };
128 union {
129 __be32 dst;
130 __be32 dstv6[4];
131 };
132 union {
133 __u32 ports;
134 __u16 port16[2];
135 };
136 __u8 proto;
137 __u8 flags;
138 };
139
140 struct ctl_value {
141 union {
142 __u64 value;
143 __u32 ifindex;
144 __u8 mac[6];
145 };
146 };
147
148 struct vip_meta {
149 __u32 flags;
150 __u32 vip_num;
151 };
152
153 struct real_definition {
154 union {
155 __be32 dst;
156 __be32 dstv6[4];
157 };
158 __u8 flags;
159 };
160
161 struct vip_stats {
162 __u64 bytes;
163 __u64 pkts;
164 };
165
166 struct eth_hdr {
167 unsigned char eth_dest[ETH_ALEN];
168 unsigned char eth_source[ETH_ALEN];
169 unsigned short eth_proto;
170 };
171
172 struct {
173 __uint(type, BPF_MAP_TYPE_HASH);
174 __uint(max_entries, MAX_VIPS);
175 __type(key, struct vip);
176 __type(value, struct vip_meta);
177 } vip_map SEC(".maps");
178
179 struct {
180 __uint(type, BPF_MAP_TYPE_ARRAY);
181 __uint(max_entries, CH_RINGS_SIZE);
182 __type(key, __u32);
183 __type(value, __u32);
184 } ch_rings SEC(".maps");
185
186 struct {
187 __uint(type, BPF_MAP_TYPE_ARRAY);
188 __uint(max_entries, MAX_REALS);
189 __type(key, __u32);
190 __type(value, struct real_definition);
191 } reals SEC(".maps");
192
193 struct {
194 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
195 __uint(max_entries, MAX_VIPS);
196 __type(key, __u32);
197 __type(value, struct vip_stats);
198 } stats SEC(".maps");
199
200 struct {
201 __uint(type, BPF_MAP_TYPE_ARRAY);
202 __uint(max_entries, CTL_MAP_SIZE);
203 __type(key, __u32);
204 __type(value, struct ctl_value);
205 } ctl_array SEC(".maps");
206
get_packet_hash(struct packet_description * pckt,bool ipv6)207 static __always_inline __u32 get_packet_hash(struct packet_description *pckt,
208 bool ipv6)
209 {
210 if (ipv6)
211 return jhash_2words(jhash(pckt->srcv6, 16, MAX_VIPS),
212 pckt->ports, CH_RINGS_SIZE);
213 else
214 return jhash_2words(pckt->src, pckt->ports, CH_RINGS_SIZE);
215 }
216
get_packet_dst(struct real_definition ** real,struct packet_description * pckt,struct vip_meta * vip_info,bool is_ipv6)217 static __always_inline bool get_packet_dst(struct real_definition **real,
218 struct packet_description *pckt,
219 struct vip_meta *vip_info,
220 bool is_ipv6)
221 {
222 __u32 hash = get_packet_hash(pckt, is_ipv6) % RING_SIZE;
223 __u32 key = RING_SIZE * vip_info->vip_num + hash;
224 __u32 *real_pos;
225
226 real_pos = bpf_map_lookup_elem(&ch_rings, &key);
227 if (!real_pos)
228 return false;
229 key = *real_pos;
230 *real = bpf_map_lookup_elem(&reals, &key);
231 if (!(*real))
232 return false;
233 return true;
234 }
235
parse_icmpv6(void * data,void * data_end,__u64 off,struct packet_description * pckt)236 static __always_inline int parse_icmpv6(void *data, void *data_end, __u64 off,
237 struct packet_description *pckt)
238 {
239 struct icmp6hdr *icmp_hdr;
240 struct ipv6hdr *ip6h;
241
242 icmp_hdr = data + off;
243 if (icmp_hdr + 1 > data_end)
244 return TC_ACT_SHOT;
245 if (icmp_hdr->icmp6_type != ICMPV6_PKT_TOOBIG)
246 return TC_ACT_OK;
247 off += sizeof(struct icmp6hdr);
248 ip6h = data + off;
249 if (ip6h + 1 > data_end)
250 return TC_ACT_SHOT;
251 pckt->proto = ip6h->nexthdr;
252 pckt->flags |= F_ICMP;
253 memcpy(pckt->srcv6, ip6h->daddr.s6_addr32, 16);
254 memcpy(pckt->dstv6, ip6h->saddr.s6_addr32, 16);
255 return TC_ACT_UNSPEC;
256 }
257
parse_icmp(void * data,void * data_end,__u64 off,struct packet_description * pckt)258 static __always_inline int parse_icmp(void *data, void *data_end, __u64 off,
259 struct packet_description *pckt)
260 {
261 struct icmphdr *icmp_hdr;
262 struct iphdr *iph;
263
264 icmp_hdr = data + off;
265 if (icmp_hdr + 1 > data_end)
266 return TC_ACT_SHOT;
267 if (icmp_hdr->type != ICMP_DEST_UNREACH ||
268 icmp_hdr->code != ICMP_FRAG_NEEDED)
269 return TC_ACT_OK;
270 off += sizeof(struct icmphdr);
271 iph = data + off;
272 if (iph + 1 > data_end)
273 return TC_ACT_SHOT;
274 if (iph->ihl != 5)
275 return TC_ACT_SHOT;
276 pckt->proto = iph->protocol;
277 pckt->flags |= F_ICMP;
278 pckt->src = iph->daddr;
279 pckt->dst = iph->saddr;
280 return TC_ACT_UNSPEC;
281 }
282
parse_udp(void * data,__u64 off,void * data_end,struct packet_description * pckt)283 static __always_inline bool parse_udp(void *data, __u64 off, void *data_end,
284 struct packet_description *pckt)
285 {
286 struct udphdr *udp;
287 udp = data + off;
288
289 if (udp + 1 > data_end)
290 return false;
291
292 if (!(pckt->flags & F_ICMP)) {
293 pckt->port16[0] = udp->source;
294 pckt->port16[1] = udp->dest;
295 } else {
296 pckt->port16[0] = udp->dest;
297 pckt->port16[1] = udp->source;
298 }
299 return true;
300 }
301
parse_tcp(void * data,__u64 off,void * data_end,struct packet_description * pckt)302 static __always_inline bool parse_tcp(void *data, __u64 off, void *data_end,
303 struct packet_description *pckt)
304 {
305 struct tcphdr *tcp;
306
307 tcp = data + off;
308 if (tcp + 1 > data_end)
309 return false;
310
311 if (tcp->syn)
312 pckt->flags |= F_SYN_SET;
313
314 if (!(pckt->flags & F_ICMP)) {
315 pckt->port16[0] = tcp->source;
316 pckt->port16[1] = tcp->dest;
317 } else {
318 pckt->port16[0] = tcp->dest;
319 pckt->port16[1] = tcp->source;
320 }
321 return true;
322 }
323
process_packet(void * data,__u64 off,void * data_end,bool is_ipv6,struct __sk_buff * skb)324 static __always_inline int process_packet(void *data, __u64 off, void *data_end,
325 bool is_ipv6, struct __sk_buff *skb)
326 {
327 void *pkt_start = (void *)(long)skb->data;
328 struct packet_description pckt = {};
329 struct eth_hdr *eth = pkt_start;
330 struct bpf_tunnel_key tkey = {};
331 struct vip_stats *data_stats;
332 struct real_definition *dst;
333 struct vip_meta *vip_info;
334 struct ctl_value *cval;
335 __u32 v4_intf_pos = 1;
336 __u32 v6_intf_pos = 2;
337 struct ipv6hdr *ip6h;
338 struct vip vip = {};
339 struct iphdr *iph;
340 int tun_flag = 0;
341 __u16 pkt_bytes;
342 __u64 iph_len;
343 __u32 ifindex;
344 __u8 protocol;
345 __u32 vip_num;
346 int action;
347
348 tkey.tunnel_ttl = 64;
349 if (is_ipv6) {
350 ip6h = data + off;
351 if (ip6h + 1 > data_end)
352 return TC_ACT_SHOT;
353
354 iph_len = sizeof(struct ipv6hdr);
355 protocol = ip6h->nexthdr;
356 pckt.proto = protocol;
357 pkt_bytes = bpf_ntohs(ip6h->payload_len);
358 off += iph_len;
359 if (protocol == IPPROTO_FRAGMENT) {
360 return TC_ACT_SHOT;
361 } else if (protocol == IPPROTO_ICMPV6) {
362 action = parse_icmpv6(data, data_end, off, &pckt);
363 if (action >= 0)
364 return action;
365 off += IPV6_PLUS_ICMP_HDR;
366 } else {
367 memcpy(pckt.srcv6, ip6h->saddr.s6_addr32, 16);
368 memcpy(pckt.dstv6, ip6h->daddr.s6_addr32, 16);
369 }
370 } else {
371 iph = data + off;
372 if (iph + 1 > data_end)
373 return TC_ACT_SHOT;
374 if (iph->ihl != 5)
375 return TC_ACT_SHOT;
376
377 protocol = iph->protocol;
378 pckt.proto = protocol;
379 pkt_bytes = bpf_ntohs(iph->tot_len);
380 off += IPV4_HDR_LEN_NO_OPT;
381
382 if (iph->frag_off & PCKT_FRAGMENTED)
383 return TC_ACT_SHOT;
384 if (protocol == IPPROTO_ICMP) {
385 action = parse_icmp(data, data_end, off, &pckt);
386 if (action >= 0)
387 return action;
388 off += IPV4_PLUS_ICMP_HDR;
389 } else {
390 pckt.src = iph->saddr;
391 pckt.dst = iph->daddr;
392 }
393 }
394 protocol = pckt.proto;
395
396 if (protocol == IPPROTO_TCP) {
397 if (!parse_tcp(data, off, data_end, &pckt))
398 return TC_ACT_SHOT;
399 } else if (protocol == IPPROTO_UDP) {
400 if (!parse_udp(data, off, data_end, &pckt))
401 return TC_ACT_SHOT;
402 } else {
403 return TC_ACT_SHOT;
404 }
405
406 if (is_ipv6)
407 memcpy(vip.daddr.v6, pckt.dstv6, 16);
408 else
409 vip.daddr.v4 = pckt.dst;
410
411 vip.dport = pckt.port16[1];
412 vip.protocol = pckt.proto;
413 vip_info = bpf_map_lookup_elem(&vip_map, &vip);
414 if (!vip_info) {
415 vip.dport = 0;
416 vip_info = bpf_map_lookup_elem(&vip_map, &vip);
417 if (!vip_info)
418 return TC_ACT_SHOT;
419 pckt.port16[1] = 0;
420 }
421
422 if (vip_info->flags & F_HASH_NO_SRC_PORT)
423 pckt.port16[0] = 0;
424
425 if (!get_packet_dst(&dst, &pckt, vip_info, is_ipv6))
426 return TC_ACT_SHOT;
427
428 if (dst->flags & F_IPV6) {
429 cval = bpf_map_lookup_elem(&ctl_array, &v6_intf_pos);
430 if (!cval)
431 return TC_ACT_SHOT;
432 ifindex = cval->ifindex;
433 memcpy(tkey.remote_ipv6, dst->dstv6, 16);
434 tun_flag = BPF_F_TUNINFO_IPV6;
435 } else {
436 cval = bpf_map_lookup_elem(&ctl_array, &v4_intf_pos);
437 if (!cval)
438 return TC_ACT_SHOT;
439 ifindex = cval->ifindex;
440 tkey.remote_ipv4 = dst->dst;
441 }
442 vip_num = vip_info->vip_num;
443 data_stats = bpf_map_lookup_elem(&stats, &vip_num);
444 if (!data_stats)
445 return TC_ACT_SHOT;
446 data_stats->pkts++;
447 data_stats->bytes += pkt_bytes;
448 bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), tun_flag);
449 *(u32 *)eth->eth_dest = tkey.remote_ipv4;
450 return bpf_redirect(ifindex, 0);
451 }
452
453 SEC("l4lb-demo")
balancer_ingress(struct __sk_buff * ctx)454 int balancer_ingress(struct __sk_buff *ctx)
455 {
456 void *data_end = (void *)(long)ctx->data_end;
457 void *data = (void *)(long)ctx->data;
458 struct eth_hdr *eth = data;
459 __u32 eth_proto;
460 __u32 nh_off;
461
462 nh_off = sizeof(struct eth_hdr);
463 if (data + nh_off > data_end)
464 return TC_ACT_SHOT;
465 eth_proto = eth->eth_proto;
466 if (eth_proto == bpf_htons(ETH_P_IP))
467 return process_packet(data, nh_off, data_end, false, ctx);
468 else if (eth_proto == bpf_htons(ETH_P_IPV6))
469 return process_packet(data, nh_off, data_end, true, ctx);
470 else
471 return TC_ACT_SHOT;
472 }
473 char _license[] SEC("license") = "GPL";
474