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TOMOYO Linux Cross Reference
Linux/net/netfilter/ipvs/ip_vs_proto_udp.c

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  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
 32 udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
 33                   struct ip_vs_proto_data *pd,
 34                   int *verdict, struct ip_vs_conn **cpp,
 35                   struct ip_vs_iphdr *iph)
 36 {
 37         struct ip_vs_service *svc;
 38         struct udphdr _udph, *uh;
 39         __be16 _ports[2], *ports = NULL;
 40 
 41         if (likely(!ip_vs_iph_icmp(iph))) {
 42                 /* IPv6 fragments, only first fragment will hit this */
 43                 uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
 44                 if (uh)
 45                         ports = &uh->source;
 46         } else {
 47                 ports = skb_header_pointer(
 48                         skb, iph->len, sizeof(_ports), &_ports);
 49         }
 50 
 51         if (!ports) {
 52                 *verdict = NF_DROP;
 53                 return 0;
 54         }
 55 
 56         rcu_read_lock();
 57         if (likely(!ip_vs_iph_inverse(iph)))
 58                 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
 59                                          &iph->daddr, ports[1]);
 60         else
 61                 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
 62                                          &iph->saddr, ports[0]);
 63 
 64         if (svc) {
 65                 int ignored;
 66 
 67                 if (ip_vs_todrop(ipvs)) {
 68                         /*
 69                          * It seems that we are very loaded.
 70                          * We have to drop this packet :(
 71                          */
 72                         rcu_read_unlock();
 73                         *verdict = NF_DROP;
 74                         return 0;
 75                 }
 76 
 77                 /*
 78                  * Let the virtual server select a real server for the
 79                  * incoming connection, and create a connection entry.
 80                  */
 81                 *cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
 82                 if (!*cpp && ignored <= 0) {
 83                         if (!ignored)
 84                                 *verdict = ip_vs_leave(svc, skb, pd, iph);
 85                         else
 86                                 *verdict = NF_DROP;
 87                         rcu_read_unlock();
 88                         return 0;
 89                 }
 90         }
 91         rcu_read_unlock();
 92         /* NF_ACCEPT */
 93         return 1;
 94 }
 95 
 96 
 97 static inline void
 98 udp_fast_csum_update(int af, struct udphdr *uhdr,
 99                      const union nf_inet_addr *oldip,
100                      const union nf_inet_addr *newip,
101                      __be16 oldport, __be16 newport)
102 {
103 #ifdef CONFIG_IP_VS_IPV6
104         if (af == AF_INET6)
105                 uhdr->check =
106                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
107                                          ip_vs_check_diff2(oldport, newport,
108                                                 ~csum_unfold(uhdr->check))));
109         else
110 #endif
111                 uhdr->check =
112                         csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
113                                          ip_vs_check_diff2(oldport, newport,
114                                                 ~csum_unfold(uhdr->check))));
115         if (!uhdr->check)
116                 uhdr->check = CSUM_MANGLED_0;
117 }
118 
119 static inline void
120 udp_partial_csum_update(int af, struct udphdr *uhdr,
121                      const union nf_inet_addr *oldip,
122                      const union nf_inet_addr *newip,
123                      __be16 oldlen, __be16 newlen)
124 {
125 #ifdef CONFIG_IP_VS_IPV6
126         if (af == AF_INET6)
127                 uhdr->check =
128                         ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
129                                          ip_vs_check_diff2(oldlen, newlen,
130                                                 csum_unfold(uhdr->check))));
131         else
132 #endif
133         uhdr->check =
134                 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
135                                 ip_vs_check_diff2(oldlen, newlen,
136                                                 csum_unfold(uhdr->check))));
137 }
138 
139 
140 static int
141 udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
142                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
143 {
144         struct udphdr *udph;
145         unsigned int udphoff = iph->len;
146         int oldlen;
147         int payload_csum = 0;
148 
149 #ifdef CONFIG_IP_VS_IPV6
150         if (cp->af == AF_INET6 && iph->fragoffs)
151                 return 1;
152 #endif
153         oldlen = skb->len - udphoff;
154 
155         /* csum_check requires unshared skb */
156         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
157                 return 0;
158 
159         if (unlikely(cp->app != NULL)) {
160                 int ret;
161 
162                 /* Some checks before mangling */
163                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
164                         return 0;
165 
166                 /*
167                  *      Call application helper if needed
168                  */
169                 if (!(ret = ip_vs_app_pkt_out(cp, skb)))
170                         return 0;
171                 /* ret=2: csum update is needed after payload mangling */
172                 if (ret == 1)
173                         oldlen = skb->len - udphoff;
174                 else
175                         payload_csum = 1;
176         }
177 
178         udph = (void *)skb_network_header(skb) + udphoff;
179         udph->source = cp->vport;
180 
181         /*
182          *      Adjust UDP checksums
183          */
184         if (skb->ip_summed == CHECKSUM_PARTIAL) {
185                 udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
186                                         htons(oldlen),
187                                         htons(skb->len - udphoff));
188         } else if (!payload_csum && (udph->check != 0)) {
189                 /* Only port and addr are changed, do fast csum update */
190                 udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
191                                      cp->dport, cp->vport);
192                 if (skb->ip_summed == CHECKSUM_COMPLETE)
193                         skb->ip_summed = (cp->app && pp->csum_check) ?
194                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
195         } else {
196                 /* full checksum calculation */
197                 udph->check = 0;
198                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
199 #ifdef CONFIG_IP_VS_IPV6
200                 if (cp->af == AF_INET6)
201                         udph->check = csum_ipv6_magic(&cp->vaddr.in6,
202                                                       &cp->caddr.in6,
203                                                       skb->len - udphoff,
204                                                       cp->protocol, skb->csum);
205                 else
206 #endif
207                         udph->check = csum_tcpudp_magic(cp->vaddr.ip,
208                                                         cp->caddr.ip,
209                                                         skb->len - udphoff,
210                                                         cp->protocol,
211                                                         skb->csum);
212                 if (udph->check == 0)
213                         udph->check = CSUM_MANGLED_0;
214                 skb->ip_summed = CHECKSUM_UNNECESSARY;
215                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
216                           pp->name, udph->check,
217                           (char*)&(udph->check) - (char*)udph);
218         }
219         return 1;
220 }
221 
222 
223 static int
224 udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
225                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
226 {
227         struct udphdr *udph;
228         unsigned int udphoff = iph->len;
229         int oldlen;
230         int payload_csum = 0;
231 
232 #ifdef CONFIG_IP_VS_IPV6
233         if (cp->af == AF_INET6 && iph->fragoffs)
234                 return 1;
235 #endif
236         oldlen = skb->len - udphoff;
237 
238         /* csum_check requires unshared skb */
239         if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
240                 return 0;
241 
242         if (unlikely(cp->app != NULL)) {
243                 int ret;
244 
245                 /* Some checks before mangling */
246                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
247                         return 0;
248 
249                 /*
250                  *      Attempt ip_vs_app call.
251                  *      It will fix ip_vs_conn
252                  */
253                 if (!(ret = ip_vs_app_pkt_in(cp, skb)))
254                         return 0;
255                 /* ret=2: csum update is needed after payload mangling */
256                 if (ret == 1)
257                         oldlen = skb->len - udphoff;
258                 else
259                         payload_csum = 1;
260         }
261 
262         udph = (void *)skb_network_header(skb) + udphoff;
263         udph->dest = cp->dport;
264 
265         /*
266          *      Adjust UDP checksums
267          */
268         if (skb->ip_summed == CHECKSUM_PARTIAL) {
269                 udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
270                                         htons(oldlen),
271                                         htons(skb->len - udphoff));
272         } else if (!payload_csum && (udph->check != 0)) {
273                 /* Only port and addr are changed, do fast csum update */
274                 udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
275                                      cp->vport, cp->dport);
276                 if (skb->ip_summed == CHECKSUM_COMPLETE)
277                         skb->ip_summed = (cp->app && pp->csum_check) ?
278                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
279         } else {
280                 /* full checksum calculation */
281                 udph->check = 0;
282                 skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
283 #ifdef CONFIG_IP_VS_IPV6
284                 if (cp->af == AF_INET6)
285                         udph->check = csum_ipv6_magic(&cp->caddr.in6,
286                                                       &cp->daddr.in6,
287                                                       skb->len - udphoff,
288                                                       cp->protocol, skb->csum);
289                 else
290 #endif
291                         udph->check = csum_tcpudp_magic(cp->caddr.ip,
292                                                         cp->daddr.ip,
293                                                         skb->len - udphoff,
294                                                         cp->protocol,
295                                                         skb->csum);
296                 if (udph->check == 0)
297                         udph->check = CSUM_MANGLED_0;
298                 skb->ip_summed = CHECKSUM_UNNECESSARY;
299         }
300         return 1;
301 }
302 
303 
304 static int
305 udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
306 {
307         struct udphdr _udph, *uh;
308         unsigned int udphoff;
309 
310 #ifdef CONFIG_IP_VS_IPV6
311         if (af == AF_INET6)
312                 udphoff = sizeof(struct ipv6hdr);
313         else
314 #endif
315                 udphoff = ip_hdrlen(skb);
316 
317         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
318         if (uh == NULL)
319                 return 0;
320 
321         if (uh->check != 0) {
322                 switch (skb->ip_summed) {
323                 case CHECKSUM_NONE:
324                         skb->csum = skb_checksum(skb, udphoff,
325                                                  skb->len - udphoff, 0);
326                 case CHECKSUM_COMPLETE:
327 #ifdef CONFIG_IP_VS_IPV6
328                         if (af == AF_INET6) {
329                                 if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
330                                                     &ipv6_hdr(skb)->daddr,
331                                                     skb->len - udphoff,
332                                                     ipv6_hdr(skb)->nexthdr,
333                                                     skb->csum)) {
334                                         IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
335                                                          "Failed checksum for");
336                                         return 0;
337                                 }
338                         } else
339 #endif
340                                 if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
341                                                       ip_hdr(skb)->daddr,
342                                                       skb->len - udphoff,
343                                                       ip_hdr(skb)->protocol,
344                                                       skb->csum)) {
345                                         IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
346                                                          "Failed checksum for");
347                                         return 0;
348                                 }
349                         break;
350                 default:
351                         /* No need to checksum. */
352                         break;
353                 }
354         }
355         return 1;
356 }
357 
358 static inline __u16 udp_app_hashkey(__be16 port)
359 {
360         return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
361                 & UDP_APP_TAB_MASK;
362 }
363 
364 
365 static int udp_register_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
366 {
367         struct ip_vs_app *i;
368         __u16 hash;
369         __be16 port = inc->port;
370         int ret = 0;
371         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
372 
373         hash = udp_app_hashkey(port);
374 
375         list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) {
376                 if (i->port == port) {
377                         ret = -EEXIST;
378                         goto out;
379                 }
380         }
381         list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]);
382         atomic_inc(&pd->appcnt);
383 
384   out:
385         return ret;
386 }
387 
388 
389 static void
390 udp_unregister_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
391 {
392         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
393 
394         atomic_dec(&pd->appcnt);
395         list_del_rcu(&inc->p_list);
396 }
397 
398 
399 static int udp_app_conn_bind(struct ip_vs_conn *cp)
400 {
401         struct netns_ipvs *ipvs = cp->ipvs;
402         int hash;
403         struct ip_vs_app *inc;
404         int result = 0;
405 
406         /* Default binding: bind app only for NAT */
407         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
408                 return 0;
409 
410         /* Lookup application incarnations and bind the right one */
411         hash = udp_app_hashkey(cp->vport);
412 
413         rcu_read_lock();
414         list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) {
415                 if (inc->port == cp->vport) {
416                         if (unlikely(!ip_vs_app_inc_get(inc)))
417                                 break;
418                         rcu_read_unlock();
419 
420                         IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
421                                       "%s:%u to app %s on port %u\n",
422                                       __func__,
423                                       IP_VS_DBG_ADDR(cp->af, &cp->caddr),
424                                       ntohs(cp->cport),
425                                       IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
426                                       ntohs(cp->vport),
427                                       inc->name, ntohs(inc->port));
428 
429                         cp->app = inc;
430                         if (inc->init_conn)
431                                 result = inc->init_conn(inc, cp);
432                         goto out;
433                 }
434         }
435         rcu_read_unlock();
436 
437   out:
438         return result;
439 }
440 
441 
442 static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
443         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
444         [IP_VS_UDP_S_LAST]              =       2*HZ,
445 };
446 
447 static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
448         [IP_VS_UDP_S_NORMAL]            =       "UDP",
449         [IP_VS_UDP_S_LAST]              =       "BUG!",
450 };
451 
452 static const char * udp_state_name(int state)
453 {
454         if (state >= IP_VS_UDP_S_LAST)
455                 return "ERR!";
456         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
457 }
458 
459 static void
460 udp_state_transition(struct ip_vs_conn *cp, int direction,
461                      const struct sk_buff *skb,
462                      struct ip_vs_proto_data *pd)
463 {
464         if (unlikely(!pd)) {
465                 pr_err("UDP no ns data\n");
466                 return;
467         }
468 
469         cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL];
470 }
471 
472 static int __udp_init(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
473 {
474         ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE);
475         pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts,
476                                                         sizeof(udp_timeouts));
477         if (!pd->timeout_table)
478                 return -ENOMEM;
479         return 0;
480 }
481 
482 static void __udp_exit(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
483 {
484         kfree(pd->timeout_table);
485 }
486 
487 
488 struct ip_vs_protocol ip_vs_protocol_udp = {
489         .name =                 "UDP",
490         .protocol =             IPPROTO_UDP,
491         .num_states =           IP_VS_UDP_S_LAST,
492         .dont_defrag =          0,
493         .init =                 NULL,
494         .exit =                 NULL,
495         .init_netns =           __udp_init,
496         .exit_netns =           __udp_exit,
497         .conn_schedule =        udp_conn_schedule,
498         .conn_in_get =          ip_vs_conn_in_get_proto,
499         .conn_out_get =         ip_vs_conn_out_get_proto,
500         .snat_handler =         udp_snat_handler,
501         .dnat_handler =         udp_dnat_handler,
502         .csum_check =           udp_csum_check,
503         .state_transition =     udp_state_transition,
504         .state_name =           udp_state_name,
505         .register_app =         udp_register_app,
506         .unregister_app =       udp_unregister_app,
507         .app_conn_bind =        udp_app_conn_bind,
508         .debug_packet =         ip_vs_tcpudp_debug_packet,
509         .timeout_change =       NULL,
510 };
511 

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