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