1 /*
2 * ip_vs_proto_udp.c: UDP load balancing support for IPVS
3 *
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
5 * Julian Anastasov <ja@ssi.bg>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 * Changes: Hans Schillstrom <hans.schillstrom@ericsson.com>
13 * Network name space (netns) aware.
14 *
15 */
16
17 #define KMSG_COMPONENT "IPVS"
18 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
19
20 #include <linux/in.h>
21 #include <linux/ip.h>
22 #include <linux/kernel.h>
23 #include <linux/netfilter.h>
24 #include <linux/netfilter_ipv4.h>
25 #include <linux/udp.h>
26
27 #include <net/ip_vs.h>
28 #include <net/ip.h>
29 #include <net/ip6_checksum.h>
30
31 static int
udp_conn_schedule(int af,struct sk_buff * skb,struct ip_vs_proto_data * pd,int * verdict,struct ip_vs_conn ** cpp,struct ip_vs_iphdr * iph)32 udp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_proto_data *pd,
33 int *verdict, struct ip_vs_conn **cpp,
34 struct ip_vs_iphdr *iph)
35 {
36 struct net *net;
37 struct ip_vs_service *svc;
38 struct udphdr _udph, *uh;
39
40 /* IPv6 fragments, only first fragment will hit this */
41 uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
42 if (uh == NULL) {
43 *verdict = NF_DROP;
44 return 0;
45 }
46 net = skb_net(skb);
47 rcu_read_lock();
48 svc = ip_vs_service_find(net, af, skb->mark, iph->protocol,
49 &iph->daddr, uh->dest);
50 if (svc) {
51 int ignored;
52
53 if (ip_vs_todrop(net_ipvs(net))) {
54 /*
55 * It seems that we are very loaded.
56 * We have to drop this packet :(
57 */
58 rcu_read_unlock();
59 *verdict = NF_DROP;
60 return 0;
61 }
62
63 /*
64 * Let the virtual server select a real server for the
65 * incoming connection, and create a connection entry.
66 */
67 *cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
68 if (!*cpp && ignored <= 0) {
69 if (!ignored)
70 *verdict = ip_vs_leave(svc, skb, pd, iph);
71 else
72 *verdict = NF_DROP;
73 rcu_read_unlock();
74 return 0;
75 }
76 }
77 rcu_read_unlock();
78 /* NF_ACCEPT */
79 return 1;
80 }
81
82
83 static inline void
udp_fast_csum_update(int af,struct udphdr * uhdr,const union nf_inet_addr * oldip,const union nf_inet_addr * newip,__be16 oldport,__be16 newport)84 udp_fast_csum_update(int af, struct udphdr *uhdr,
85 const union nf_inet_addr *oldip,
86 const union nf_inet_addr *newip,
87 __be16 oldport, __be16 newport)
88 {
89 #ifdef CONFIG_IP_VS_IPV6
90 if (af == AF_INET6)
91 uhdr->check =
92 csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
93 ip_vs_check_diff2(oldport, newport,
94 ~csum_unfold(uhdr->check))));
95 else
96 #endif
97 uhdr->check =
98 csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
99 ip_vs_check_diff2(oldport, newport,
100 ~csum_unfold(uhdr->check))));
101 if (!uhdr->check)
102 uhdr->check = CSUM_MANGLED_0;
103 }
104
105 static inline void
udp_partial_csum_update(int af,struct udphdr * uhdr,const union nf_inet_addr * oldip,const union nf_inet_addr * newip,__be16 oldlen,__be16 newlen)106 udp_partial_csum_update(int af, struct udphdr *uhdr,
107 const union nf_inet_addr *oldip,
108 const union nf_inet_addr *newip,
109 __be16 oldlen, __be16 newlen)
110 {
111 #ifdef CONFIG_IP_VS_IPV6
112 if (af == AF_INET6)
113 uhdr->check =
114 ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
115 ip_vs_check_diff2(oldlen, newlen,
116 csum_unfold(uhdr->check))));
117 else
118 #endif
119 uhdr->check =
120 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
121 ip_vs_check_diff2(oldlen, newlen,
122 csum_unfold(uhdr->check))));
123 }
124
125
126 static int
udp_snat_handler(struct sk_buff * skb,struct ip_vs_protocol * pp,struct ip_vs_conn * cp,struct ip_vs_iphdr * iph)127 udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
128 struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
129 {
130 struct udphdr *udph;
131 unsigned int udphoff = iph->len;
132 int oldlen;
133 int payload_csum = 0;
134
135 #ifdef CONFIG_IP_VS_IPV6
136 if (cp->af == AF_INET6 && iph->fragoffs)
137 return 1;
138 #endif
139 oldlen = skb->len - udphoff;
140
141 /* csum_check requires unshared skb */
142 if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
143 return 0;
144
145 if (unlikely(cp->app != NULL)) {
146 int ret;
147
148 /* Some checks before mangling */
149 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
150 return 0;
151
152 /*
153 * Call application helper if needed
154 */
155 if (!(ret = ip_vs_app_pkt_out(cp, skb)))
156 return 0;
157 /* ret=2: csum update is needed after payload mangling */
158 if (ret == 1)
159 oldlen = skb->len - udphoff;
160 else
161 payload_csum = 1;
162 }
163
164 udph = (void *)skb_network_header(skb) + udphoff;
165 udph->source = cp->vport;
166
167 /*
168 * Adjust UDP checksums
169 */
170 if (skb->ip_summed == CHECKSUM_PARTIAL) {
171 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
172 htons(oldlen),
173 htons(skb->len - udphoff));
174 } else if (!payload_csum && (udph->check != 0)) {
175 /* Only port and addr are changed, do fast csum update */
176 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
177 cp->dport, cp->vport);
178 if (skb->ip_summed == CHECKSUM_COMPLETE)
179 skb->ip_summed = (cp->app && pp->csum_check) ?
180 CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
181 } else {
182 /* full checksum calculation */
183 udph->check = 0;
184 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
185 #ifdef CONFIG_IP_VS_IPV6
186 if (cp->af == AF_INET6)
187 udph->check = csum_ipv6_magic(&cp->vaddr.in6,
188 &cp->caddr.in6,
189 skb->len - udphoff,
190 cp->protocol, skb->csum);
191 else
192 #endif
193 udph->check = csum_tcpudp_magic(cp->vaddr.ip,
194 cp->caddr.ip,
195 skb->len - udphoff,
196 cp->protocol,
197 skb->csum);
198 if (udph->check == 0)
199 udph->check = CSUM_MANGLED_0;
200 skb->ip_summed = CHECKSUM_UNNECESSARY;
201 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
202 pp->name, udph->check,
203 (char*)&(udph->check) - (char*)udph);
204 }
205 return 1;
206 }
207
208
209 static int
udp_dnat_handler(struct sk_buff * skb,struct ip_vs_protocol * pp,struct ip_vs_conn * cp,struct ip_vs_iphdr * iph)210 udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
211 struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
212 {
213 struct udphdr *udph;
214 unsigned int udphoff = iph->len;
215 int oldlen;
216 int payload_csum = 0;
217
218 #ifdef CONFIG_IP_VS_IPV6
219 if (cp->af == AF_INET6 && iph->fragoffs)
220 return 1;
221 #endif
222 oldlen = skb->len - udphoff;
223
224 /* csum_check requires unshared skb */
225 if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
226 return 0;
227
228 if (unlikely(cp->app != NULL)) {
229 int ret;
230
231 /* Some checks before mangling */
232 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
233 return 0;
234
235 /*
236 * Attempt ip_vs_app call.
237 * It will fix ip_vs_conn
238 */
239 if (!(ret = ip_vs_app_pkt_in(cp, skb)))
240 return 0;
241 /* ret=2: csum update is needed after payload mangling */
242 if (ret == 1)
243 oldlen = skb->len - udphoff;
244 else
245 payload_csum = 1;
246 }
247
248 udph = (void *)skb_network_header(skb) + udphoff;
249 udph->dest = cp->dport;
250
251 /*
252 * Adjust UDP checksums
253 */
254 if (skb->ip_summed == CHECKSUM_PARTIAL) {
255 udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
256 htons(oldlen),
257 htons(skb->len - udphoff));
258 } else if (!payload_csum && (udph->check != 0)) {
259 /* Only port and addr are changed, do fast csum update */
260 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
261 cp->vport, cp->dport);
262 if (skb->ip_summed == CHECKSUM_COMPLETE)
263 skb->ip_summed = (cp->app && pp->csum_check) ?
264 CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
265 } else {
266 /* full checksum calculation */
267 udph->check = 0;
268 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
269 #ifdef CONFIG_IP_VS_IPV6
270 if (cp->af == AF_INET6)
271 udph->check = csum_ipv6_magic(&cp->caddr.in6,
272 &cp->daddr.in6,
273 skb->len - udphoff,
274 cp->protocol, skb->csum);
275 else
276 #endif
277 udph->check = csum_tcpudp_magic(cp->caddr.ip,
278 cp->daddr.ip,
279 skb->len - udphoff,
280 cp->protocol,
281 skb->csum);
282 if (udph->check == 0)
283 udph->check = CSUM_MANGLED_0;
284 skb->ip_summed = CHECKSUM_UNNECESSARY;
285 }
286 return 1;
287 }
288
289
290 static int
udp_csum_check(int af,struct sk_buff * skb,struct ip_vs_protocol * pp)291 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
292 {
293 struct udphdr _udph, *uh;
294 unsigned int udphoff;
295
296 #ifdef CONFIG_IP_VS_IPV6
297 if (af == AF_INET6)
298 udphoff = sizeof(struct ipv6hdr);
299 else
300 #endif
301 udphoff = ip_hdrlen(skb);
302
303 uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
304 if (uh == NULL)
305 return 0;
306
307 if (uh->check != 0) {
308 switch (skb->ip_summed) {
309 case CHECKSUM_NONE:
310 skb->csum = skb_checksum(skb, udphoff,
311 skb->len - udphoff, 0);
312 case CHECKSUM_COMPLETE:
313 #ifdef CONFIG_IP_VS_IPV6
314 if (af == AF_INET6) {
315 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
316 &ipv6_hdr(skb)->daddr,
317 skb->len - udphoff,
318 ipv6_hdr(skb)->nexthdr,
319 skb->csum)) {
320 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
321 "Failed checksum for");
322 return 0;
323 }
324 } else
325 #endif
326 if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
327 ip_hdr(skb)->daddr,
328 skb->len - udphoff,
329 ip_hdr(skb)->protocol,
330 skb->csum)) {
331 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
332 "Failed checksum for");
333 return 0;
334 }
335 break;
336 default:
337 /* No need to checksum. */
338 break;
339 }
340 }
341 return 1;
342 }
343
udp_app_hashkey(__be16 port)344 static inline __u16 udp_app_hashkey(__be16 port)
345 {
346 return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
347 & UDP_APP_TAB_MASK;
348 }
349
350
udp_register_app(struct net * net,struct ip_vs_app * inc)351 static int udp_register_app(struct net *net, struct ip_vs_app *inc)
352 {
353 struct ip_vs_app *i;
354 __u16 hash;
355 __be16 port = inc->port;
356 int ret = 0;
357 struct netns_ipvs *ipvs = net_ipvs(net);
358 struct ip_vs_proto_data *pd = ip_vs_proto_data_get(net, IPPROTO_UDP);
359
360 hash = udp_app_hashkey(port);
361
362 list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) {
363 if (i->port == port) {
364 ret = -EEXIST;
365 goto out;
366 }
367 }
368 list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]);
369 atomic_inc(&pd->appcnt);
370
371 out:
372 return ret;
373 }
374
375
376 static void
udp_unregister_app(struct net * net,struct ip_vs_app * inc)377 udp_unregister_app(struct net *net, struct ip_vs_app *inc)
378 {
379 struct ip_vs_proto_data *pd = ip_vs_proto_data_get(net, IPPROTO_UDP);
380
381 atomic_dec(&pd->appcnt);
382 list_del_rcu(&inc->p_list);
383 }
384
385
udp_app_conn_bind(struct ip_vs_conn * cp)386 static int udp_app_conn_bind(struct ip_vs_conn *cp)
387 {
388 struct netns_ipvs *ipvs = net_ipvs(ip_vs_conn_net(cp));
389 int hash;
390 struct ip_vs_app *inc;
391 int result = 0;
392
393 /* Default binding: bind app only for NAT */
394 if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
395 return 0;
396
397 /* Lookup application incarnations and bind the right one */
398 hash = udp_app_hashkey(cp->vport);
399
400 rcu_read_lock();
401 list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) {
402 if (inc->port == cp->vport) {
403 if (unlikely(!ip_vs_app_inc_get(inc)))
404 break;
405 rcu_read_unlock();
406
407 IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
408 "%s:%u to app %s on port %u\n",
409 __func__,
410 IP_VS_DBG_ADDR(cp->af, &cp->caddr),
411 ntohs(cp->cport),
412 IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
413 ntohs(cp->vport),
414 inc->name, ntohs(inc->port));
415
416 cp->app = inc;
417 if (inc->init_conn)
418 result = inc->init_conn(inc, cp);
419 goto out;
420 }
421 }
422 rcu_read_unlock();
423
424 out:
425 return result;
426 }
427
428
429 static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
430 [IP_VS_UDP_S_NORMAL] = 5*60*HZ,
431 [IP_VS_UDP_S_LAST] = 2*HZ,
432 };
433
434 static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
435 [IP_VS_UDP_S_NORMAL] = "UDP",
436 [IP_VS_UDP_S_LAST] = "BUG!",
437 };
438
udp_state_name(int state)439 static const char * udp_state_name(int state)
440 {
441 if (state >= IP_VS_UDP_S_LAST)
442 return "ERR!";
443 return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
444 }
445
446 static void
udp_state_transition(struct ip_vs_conn * cp,int direction,const struct sk_buff * skb,struct ip_vs_proto_data * pd)447 udp_state_transition(struct ip_vs_conn *cp, int direction,
448 const struct sk_buff *skb,
449 struct ip_vs_proto_data *pd)
450 {
451 if (unlikely(!pd)) {
452 pr_err("UDP no ns data\n");
453 return;
454 }
455
456 cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL];
457 }
458
__udp_init(struct net * net,struct ip_vs_proto_data * pd)459 static int __udp_init(struct net *net, struct ip_vs_proto_data *pd)
460 {
461 struct netns_ipvs *ipvs = net_ipvs(net);
462
463 ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE);
464 pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts,
465 sizeof(udp_timeouts));
466 if (!pd->timeout_table)
467 return -ENOMEM;
468 return 0;
469 }
470
__udp_exit(struct net * net,struct ip_vs_proto_data * pd)471 static void __udp_exit(struct net *net, struct ip_vs_proto_data *pd)
472 {
473 kfree(pd->timeout_table);
474 }
475
476
477 struct ip_vs_protocol ip_vs_protocol_udp = {
478 .name = "UDP",
479 .protocol = IPPROTO_UDP,
480 .num_states = IP_VS_UDP_S_LAST,
481 .dont_defrag = 0,
482 .init = NULL,
483 .exit = NULL,
484 .init_netns = __udp_init,
485 .exit_netns = __udp_exit,
486 .conn_schedule = udp_conn_schedule,
487 .conn_in_get = ip_vs_conn_in_get_proto,
488 .conn_out_get = ip_vs_conn_out_get_proto,
489 .snat_handler = udp_snat_handler,
490 .dnat_handler = udp_dnat_handler,
491 .csum_check = udp_csum_check,
492 .state_transition = udp_state_transition,
493 .state_name = udp_state_name,
494 .register_app = udp_register_app,
495 .unregister_app = udp_unregister_app,
496 .app_conn_bind = udp_app_conn_bind,
497 .debug_packet = ip_vs_tcpudp_debug_packet,
498 .timeout_change = NULL,
499 };
500