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

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  1 /*
  2  * ip_vs_proto_tcp.c:   TCP 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  *
 14  *              Network name space (netns) aware.
 15  *              Global data moved to netns i.e struct netns_ipvs
 16  *              tcp_timeouts table has copy per netns in a hash table per
 17  *              protocol ip_vs_proto_data and is handled by netns
 18  */
 19 
 20 #define KMSG_COMPONENT "IPVS"
 21 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 22 
 23 #include <linux/kernel.h>
 24 #include <linux/ip.h>
 25 #include <linux/tcp.h>                  /* for tcphdr */
 26 #include <net/ip.h>
 27 #include <net/tcp.h>                    /* for csum_tcpudp_magic */
 28 #include <net/ip6_checksum.h>
 29 #include <linux/netfilter.h>
 30 #include <linux/netfilter_ipv4.h>
 31 
 32 #include <net/ip_vs.h>
 33 
 34 static int
 35 tcp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
 36                   struct ip_vs_proto_data *pd,
 37                   int *verdict, struct ip_vs_conn **cpp,
 38                   struct ip_vs_iphdr *iph)
 39 {
 40         struct ip_vs_service *svc;
 41         struct tcphdr _tcph, *th;
 42         __be16 _ports[2], *ports = NULL;
 43 
 44         /* In the event of icmp, we're only guaranteed to have the first 8
 45          * bytes of the transport header, so we only check the rest of the
 46          * TCP packet for non-ICMP packets
 47          */
 48         if (likely(!ip_vs_iph_icmp(iph))) {
 49                 th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
 50                 if (th) {
 51                         if (th->rst || !(sysctl_sloppy_tcp(ipvs) || th->syn))
 52                                 return 1;
 53                         ports = &th->source;
 54                 }
 55         } else {
 56                 ports = skb_header_pointer(
 57                         skb, iph->len, sizeof(_ports), &_ports);
 58         }
 59 
 60         if (!ports) {
 61                 *verdict = NF_DROP;
 62                 return 0;
 63         }
 64 
 65         /* No !th->ack check to allow scheduling on SYN+ACK for Active FTP */
 66         rcu_read_lock();
 67 
 68         if (likely(!ip_vs_iph_inverse(iph)))
 69                 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
 70                                          &iph->daddr, ports[1]);
 71         else
 72                 svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
 73                                          &iph->saddr, ports[0]);
 74 
 75         if (svc) {
 76                 int ignored;
 77 
 78                 if (ip_vs_todrop(ipvs)) {
 79                         /*
 80                          * It seems that we are very loaded.
 81                          * We have to drop this packet :(
 82                          */
 83                         rcu_read_unlock();
 84                         *verdict = NF_DROP;
 85                         return 0;
 86                 }
 87 
 88                 /*
 89                  * Let the virtual server select a real server for the
 90                  * incoming connection, and create a connection entry.
 91                  */
 92                 *cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
 93                 if (!*cpp && ignored <= 0) {
 94                         if (!ignored)
 95                                 *verdict = ip_vs_leave(svc, skb, pd, iph);
 96                         else
 97                                 *verdict = NF_DROP;
 98                         rcu_read_unlock();
 99                         return 0;
100                 }
101         }
102         rcu_read_unlock();
103         /* NF_ACCEPT */
104         return 1;
105 }
106 
107 
108 static inline void
109 tcp_fast_csum_update(int af, struct tcphdr *tcph,
110                      const union nf_inet_addr *oldip,
111                      const union nf_inet_addr *newip,
112                      __be16 oldport, __be16 newport)
113 {
114 #ifdef CONFIG_IP_VS_IPV6
115         if (af == AF_INET6)
116                 tcph->check =
117                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
118                                          ip_vs_check_diff2(oldport, newport,
119                                                 ~csum_unfold(tcph->check))));
120         else
121 #endif
122         tcph->check =
123                 csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
124                                  ip_vs_check_diff2(oldport, newport,
125                                                 ~csum_unfold(tcph->check))));
126 }
127 
128 
129 static inline void
130 tcp_partial_csum_update(int af, struct tcphdr *tcph,
131                      const union nf_inet_addr *oldip,
132                      const union nf_inet_addr *newip,
133                      __be16 oldlen, __be16 newlen)
134 {
135 #ifdef CONFIG_IP_VS_IPV6
136         if (af == AF_INET6)
137                 tcph->check =
138                         ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
139                                          ip_vs_check_diff2(oldlen, newlen,
140                                                 csum_unfold(tcph->check))));
141         else
142 #endif
143         tcph->check =
144                 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
145                                 ip_vs_check_diff2(oldlen, newlen,
146                                                 csum_unfold(tcph->check))));
147 }
148 
149 
150 static int
151 tcp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
152                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
153 {
154         struct tcphdr *tcph;
155         unsigned int tcphoff = iph->len;
156         int oldlen;
157         int payload_csum = 0;
158 
159 #ifdef CONFIG_IP_VS_IPV6
160         if (cp->af == AF_INET6 && iph->fragoffs)
161                 return 1;
162 #endif
163         oldlen = skb->len - tcphoff;
164 
165         /* csum_check requires unshared skb */
166         if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
167                 return 0;
168 
169         if (unlikely(cp->app != NULL)) {
170                 int ret;
171 
172                 /* Some checks before mangling */
173                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
174                         return 0;
175 
176                 /* Call application helper if needed */
177                 if (!(ret = ip_vs_app_pkt_out(cp, skb)))
178                         return 0;
179                 /* ret=2: csum update is needed after payload mangling */
180                 if (ret == 1)
181                         oldlen = skb->len - tcphoff;
182                 else
183                         payload_csum = 1;
184         }
185 
186         tcph = (void *)skb_network_header(skb) + tcphoff;
187         tcph->source = cp->vport;
188 
189         /* Adjust TCP checksums */
190         if (skb->ip_summed == CHECKSUM_PARTIAL) {
191                 tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
192                                         htons(oldlen),
193                                         htons(skb->len - tcphoff));
194         } else if (!payload_csum) {
195                 /* Only port and addr are changed, do fast csum update */
196                 tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
197                                      cp->dport, cp->vport);
198                 if (skb->ip_summed == CHECKSUM_COMPLETE)
199                         skb->ip_summed = (cp->app && pp->csum_check) ?
200                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
201         } else {
202                 /* full checksum calculation */
203                 tcph->check = 0;
204                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
205 #ifdef CONFIG_IP_VS_IPV6
206                 if (cp->af == AF_INET6)
207                         tcph->check = csum_ipv6_magic(&cp->vaddr.in6,
208                                                       &cp->caddr.in6,
209                                                       skb->len - tcphoff,
210                                                       cp->protocol, skb->csum);
211                 else
212 #endif
213                         tcph->check = csum_tcpudp_magic(cp->vaddr.ip,
214                                                         cp->caddr.ip,
215                                                         skb->len - tcphoff,
216                                                         cp->protocol,
217                                                         skb->csum);
218                 skb->ip_summed = CHECKSUM_UNNECESSARY;
219 
220                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
221                           pp->name, tcph->check,
222                           (char*)&(tcph->check) - (char*)tcph);
223         }
224         return 1;
225 }
226 
227 
228 static int
229 tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
230                  struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
231 {
232         struct tcphdr *tcph;
233         unsigned int tcphoff = iph->len;
234         int oldlen;
235         int payload_csum = 0;
236 
237 #ifdef CONFIG_IP_VS_IPV6
238         if (cp->af == AF_INET6 && iph->fragoffs)
239                 return 1;
240 #endif
241         oldlen = skb->len - tcphoff;
242 
243         /* csum_check requires unshared skb */
244         if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
245                 return 0;
246 
247         if (unlikely(cp->app != NULL)) {
248                 int ret;
249 
250                 /* Some checks before mangling */
251                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
252                         return 0;
253 
254                 /*
255                  *      Attempt ip_vs_app call.
256                  *      It will fix ip_vs_conn and iph ack_seq stuff
257                  */
258                 if (!(ret = ip_vs_app_pkt_in(cp, skb)))
259                         return 0;
260                 /* ret=2: csum update is needed after payload mangling */
261                 if (ret == 1)
262                         oldlen = skb->len - tcphoff;
263                 else
264                         payload_csum = 1;
265         }
266 
267         tcph = (void *)skb_network_header(skb) + tcphoff;
268         tcph->dest = cp->dport;
269 
270         /*
271          *      Adjust TCP checksums
272          */
273         if (skb->ip_summed == CHECKSUM_PARTIAL) {
274                 tcp_partial_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
275                                         htons(oldlen),
276                                         htons(skb->len - tcphoff));
277         } else if (!payload_csum) {
278                 /* Only port and addr are changed, do fast csum update */
279                 tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
280                                      cp->vport, cp->dport);
281                 if (skb->ip_summed == CHECKSUM_COMPLETE)
282                         skb->ip_summed = (cp->app && pp->csum_check) ?
283                                          CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
284         } else {
285                 /* full checksum calculation */
286                 tcph->check = 0;
287                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
288 #ifdef CONFIG_IP_VS_IPV6
289                 if (cp->af == AF_INET6)
290                         tcph->check = csum_ipv6_magic(&cp->caddr.in6,
291                                                       &cp->daddr.in6,
292                                                       skb->len - tcphoff,
293                                                       cp->protocol, skb->csum);
294                 else
295 #endif
296                         tcph->check = csum_tcpudp_magic(cp->caddr.ip,
297                                                         cp->daddr.ip,
298                                                         skb->len - tcphoff,
299                                                         cp->protocol,
300                                                         skb->csum);
301                 skb->ip_summed = CHECKSUM_UNNECESSARY;
302         }
303         return 1;
304 }
305 
306 
307 static int
308 tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
309 {
310         unsigned int tcphoff;
311 
312 #ifdef CONFIG_IP_VS_IPV6
313         if (af == AF_INET6)
314                 tcphoff = sizeof(struct ipv6hdr);
315         else
316 #endif
317                 tcphoff = ip_hdrlen(skb);
318 
319         switch (skb->ip_summed) {
320         case CHECKSUM_NONE:
321                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
322         case CHECKSUM_COMPLETE:
323 #ifdef CONFIG_IP_VS_IPV6
324                 if (af == AF_INET6) {
325                         if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
326                                             &ipv6_hdr(skb)->daddr,
327                                             skb->len - tcphoff,
328                                             ipv6_hdr(skb)->nexthdr,
329                                             skb->csum)) {
330                                 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
331                                                  "Failed checksum for");
332                                 return 0;
333                         }
334                 } else
335 #endif
336                         if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
337                                               ip_hdr(skb)->daddr,
338                                               skb->len - tcphoff,
339                                               ip_hdr(skb)->protocol,
340                                               skb->csum)) {
341                                 IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
342                                                  "Failed checksum for");
343                                 return 0;
344                         }
345                 break;
346         default:
347                 /* No need to checksum. */
348                 break;
349         }
350 
351         return 1;
352 }
353 
354 
355 #define TCP_DIR_INPUT           0
356 #define TCP_DIR_OUTPUT          4
357 #define TCP_DIR_INPUT_ONLY      8
358 
359 static const int tcp_state_off[IP_VS_DIR_LAST] = {
360         [IP_VS_DIR_INPUT]               =       TCP_DIR_INPUT,
361         [IP_VS_DIR_OUTPUT]              =       TCP_DIR_OUTPUT,
362         [IP_VS_DIR_INPUT_ONLY]          =       TCP_DIR_INPUT_ONLY,
363 };
364 
365 /*
366  *      Timeout table[state]
367  */
368 static const int tcp_timeouts[IP_VS_TCP_S_LAST+1] = {
369         [IP_VS_TCP_S_NONE]              =       2*HZ,
370         [IP_VS_TCP_S_ESTABLISHED]       =       15*60*HZ,
371         [IP_VS_TCP_S_SYN_SENT]          =       2*60*HZ,
372         [IP_VS_TCP_S_SYN_RECV]          =       1*60*HZ,
373         [IP_VS_TCP_S_FIN_WAIT]          =       2*60*HZ,
374         [IP_VS_TCP_S_TIME_WAIT]         =       2*60*HZ,
375         [IP_VS_TCP_S_CLOSE]             =       10*HZ,
376         [IP_VS_TCP_S_CLOSE_WAIT]        =       60*HZ,
377         [IP_VS_TCP_S_LAST_ACK]          =       30*HZ,
378         [IP_VS_TCP_S_LISTEN]            =       2*60*HZ,
379         [IP_VS_TCP_S_SYNACK]            =       120*HZ,
380         [IP_VS_TCP_S_LAST]              =       2*HZ,
381 };
382 
383 static const char *const tcp_state_name_table[IP_VS_TCP_S_LAST+1] = {
384         [IP_VS_TCP_S_NONE]              =       "NONE",
385         [IP_VS_TCP_S_ESTABLISHED]       =       "ESTABLISHED",
386         [IP_VS_TCP_S_SYN_SENT]          =       "SYN_SENT",
387         [IP_VS_TCP_S_SYN_RECV]          =       "SYN_RECV",
388         [IP_VS_TCP_S_FIN_WAIT]          =       "FIN_WAIT",
389         [IP_VS_TCP_S_TIME_WAIT]         =       "TIME_WAIT",
390         [IP_VS_TCP_S_CLOSE]             =       "CLOSE",
391         [IP_VS_TCP_S_CLOSE_WAIT]        =       "CLOSE_WAIT",
392         [IP_VS_TCP_S_LAST_ACK]          =       "LAST_ACK",
393         [IP_VS_TCP_S_LISTEN]            =       "LISTEN",
394         [IP_VS_TCP_S_SYNACK]            =       "SYNACK",
395         [IP_VS_TCP_S_LAST]              =       "BUG!",
396 };
397 
398 static const bool tcp_state_active_table[IP_VS_TCP_S_LAST] = {
399         [IP_VS_TCP_S_NONE]              =       false,
400         [IP_VS_TCP_S_ESTABLISHED]       =       true,
401         [IP_VS_TCP_S_SYN_SENT]          =       true,
402         [IP_VS_TCP_S_SYN_RECV]          =       true,
403         [IP_VS_TCP_S_FIN_WAIT]          =       false,
404         [IP_VS_TCP_S_TIME_WAIT]         =       false,
405         [IP_VS_TCP_S_CLOSE]             =       false,
406         [IP_VS_TCP_S_CLOSE_WAIT]        =       false,
407         [IP_VS_TCP_S_LAST_ACK]          =       false,
408         [IP_VS_TCP_S_LISTEN]            =       false,
409         [IP_VS_TCP_S_SYNACK]            =       true,
410 };
411 
412 #define sNO IP_VS_TCP_S_NONE
413 #define sES IP_VS_TCP_S_ESTABLISHED
414 #define sSS IP_VS_TCP_S_SYN_SENT
415 #define sSR IP_VS_TCP_S_SYN_RECV
416 #define sFW IP_VS_TCP_S_FIN_WAIT
417 #define sTW IP_VS_TCP_S_TIME_WAIT
418 #define sCL IP_VS_TCP_S_CLOSE
419 #define sCW IP_VS_TCP_S_CLOSE_WAIT
420 #define sLA IP_VS_TCP_S_LAST_ACK
421 #define sLI IP_VS_TCP_S_LISTEN
422 #define sSA IP_VS_TCP_S_SYNACK
423 
424 struct tcp_states_t {
425         int next_state[IP_VS_TCP_S_LAST];
426 };
427 
428 static const char * tcp_state_name(int state)
429 {
430         if (state >= IP_VS_TCP_S_LAST)
431                 return "ERR!";
432         return tcp_state_name_table[state] ? tcp_state_name_table[state] : "?";
433 }
434 
435 static bool tcp_state_active(int state)
436 {
437         if (state >= IP_VS_TCP_S_LAST)
438                 return false;
439         return tcp_state_active_table[state];
440 }
441 
442 static struct tcp_states_t tcp_states [] = {
443 /*      INPUT */
444 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
445 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
446 /*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sTW }},
447 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
448 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sSR }},
449 
450 /*      OUTPUT */
451 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
452 /*syn*/ {{sSS, sES, sSS, sSR, sSS, sSS, sSS, sSS, sSS, sLI, sSR }},
453 /*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
454 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
455 /*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
456 
457 /*      INPUT-ONLY */
458 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
459 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
460 /*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
461 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
462 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
463 };
464 
465 static struct tcp_states_t tcp_states_dos [] = {
466 /*      INPUT */
467 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
468 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSA }},
469 /*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sSA }},
470 /*ack*/ {{sES, sES, sSS, sSR, sFW, sTW, sCL, sCW, sCL, sLI, sSA }},
471 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
472 
473 /*      OUTPUT */
474 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
475 /*syn*/ {{sSS, sES, sSS, sSA, sSS, sSS, sSS, sSS, sSS, sLI, sSA }},
476 /*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
477 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
478 /*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
479 
480 /*      INPUT-ONLY */
481 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
482 /*syn*/ {{sSA, sES, sES, sSR, sSA, sSA, sSA, sSA, sSA, sSA, sSA }},
483 /*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
484 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
485 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
486 };
487 
488 static void tcp_timeout_change(struct ip_vs_proto_data *pd, int flags)
489 {
490         int on = (flags & 1);           /* secure_tcp */
491 
492         /*
493         ** FIXME: change secure_tcp to independent sysctl var
494         ** or make it per-service or per-app because it is valid
495         ** for most if not for all of the applications. Something
496         ** like "capabilities" (flags) for each object.
497         */
498         pd->tcp_state_table = (on ? tcp_states_dos : tcp_states);
499 }
500 
501 static inline int tcp_state_idx(struct tcphdr *th)
502 {
503         if (th->rst)
504                 return 3;
505         if (th->syn)
506                 return 0;
507         if (th->fin)
508                 return 1;
509         if (th->ack)
510                 return 2;
511         return -1;
512 }
513 
514 static inline void
515 set_tcp_state(struct ip_vs_proto_data *pd, struct ip_vs_conn *cp,
516               int direction, struct tcphdr *th)
517 {
518         int state_idx;
519         int new_state = IP_VS_TCP_S_CLOSE;
520         int state_off = tcp_state_off[direction];
521 
522         /*
523          *    Update state offset to INPUT_ONLY if necessary
524          *    or delete NO_OUTPUT flag if output packet detected
525          */
526         if (cp->flags & IP_VS_CONN_F_NOOUTPUT) {
527                 if (state_off == TCP_DIR_OUTPUT)
528                         cp->flags &= ~IP_VS_CONN_F_NOOUTPUT;
529                 else
530                         state_off = TCP_DIR_INPUT_ONLY;
531         }
532 
533         if ((state_idx = tcp_state_idx(th)) < 0) {
534                 IP_VS_DBG(8, "tcp_state_idx=%d!!!\n", state_idx);
535                 goto tcp_state_out;
536         }
537 
538         new_state =
539                 pd->tcp_state_table[state_off+state_idx].next_state[cp->state];
540 
541   tcp_state_out:
542         if (new_state != cp->state) {
543                 struct ip_vs_dest *dest = cp->dest;
544 
545                 IP_VS_DBG_BUF(8, "%s %s [%c%c%c%c] %s:%d->"
546                               "%s:%d state: %s->%s conn->refcnt:%d\n",
547                               pd->pp->name,
548                               ((state_off == TCP_DIR_OUTPUT) ?
549                                "output " : "input "),
550                               th->syn ? 'S' : '.',
551                               th->fin ? 'F' : '.',
552                               th->ack ? 'A' : '.',
553                               th->rst ? 'R' : '.',
554                               IP_VS_DBG_ADDR(cp->daf, &cp->daddr),
555                               ntohs(cp->dport),
556                               IP_VS_DBG_ADDR(cp->af, &cp->caddr),
557                               ntohs(cp->cport),
558                               tcp_state_name(cp->state),
559                               tcp_state_name(new_state),
560                               atomic_read(&cp->refcnt));
561 
562                 if (dest) {
563                         if (!(cp->flags & IP_VS_CONN_F_INACTIVE) &&
564                             !tcp_state_active(new_state)) {
565                                 atomic_dec(&dest->activeconns);
566                                 atomic_inc(&dest->inactconns);
567                                 cp->flags |= IP_VS_CONN_F_INACTIVE;
568                         } else if ((cp->flags & IP_VS_CONN_F_INACTIVE) &&
569                                    tcp_state_active(new_state)) {
570                                 atomic_inc(&dest->activeconns);
571                                 atomic_dec(&dest->inactconns);
572                                 cp->flags &= ~IP_VS_CONN_F_INACTIVE;
573                         }
574                 }
575         }
576 
577         if (likely(pd))
578                 cp->timeout = pd->timeout_table[cp->state = new_state];
579         else    /* What to do ? */
580                 cp->timeout = tcp_timeouts[cp->state = new_state];
581 }
582 
583 /*
584  *      Handle state transitions
585  */
586 static void
587 tcp_state_transition(struct ip_vs_conn *cp, int direction,
588                      const struct sk_buff *skb,
589                      struct ip_vs_proto_data *pd)
590 {
591         struct tcphdr _tcph, *th;
592 
593 #ifdef CONFIG_IP_VS_IPV6
594         int ihl = cp->af == AF_INET ? ip_hdrlen(skb) : sizeof(struct ipv6hdr);
595 #else
596         int ihl = ip_hdrlen(skb);
597 #endif
598 
599         th = skb_header_pointer(skb, ihl, sizeof(_tcph), &_tcph);
600         if (th == NULL)
601                 return;
602 
603         spin_lock_bh(&cp->lock);
604         set_tcp_state(pd, cp, direction, th);
605         spin_unlock_bh(&cp->lock);
606 }
607 
608 static inline __u16 tcp_app_hashkey(__be16 port)
609 {
610         return (((__force u16)port >> TCP_APP_TAB_BITS) ^ (__force u16)port)
611                 & TCP_APP_TAB_MASK;
612 }
613 
614 
615 static int tcp_register_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
616 {
617         struct ip_vs_app *i;
618         __u16 hash;
619         __be16 port = inc->port;
620         int ret = 0;
621         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_TCP);
622 
623         hash = tcp_app_hashkey(port);
624 
625         list_for_each_entry(i, &ipvs->tcp_apps[hash], p_list) {
626                 if (i->port == port) {
627                         ret = -EEXIST;
628                         goto out;
629                 }
630         }
631         list_add_rcu(&inc->p_list, &ipvs->tcp_apps[hash]);
632         atomic_inc(&pd->appcnt);
633 
634   out:
635         return ret;
636 }
637 
638 
639 static void
640 tcp_unregister_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
641 {
642         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_TCP);
643 
644         atomic_dec(&pd->appcnt);
645         list_del_rcu(&inc->p_list);
646 }
647 
648 
649 static int
650 tcp_app_conn_bind(struct ip_vs_conn *cp)
651 {
652         struct netns_ipvs *ipvs = cp->ipvs;
653         int hash;
654         struct ip_vs_app *inc;
655         int result = 0;
656 
657         /* Default binding: bind app only for NAT */
658         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
659                 return 0;
660 
661         /* Lookup application incarnations and bind the right one */
662         hash = tcp_app_hashkey(cp->vport);
663 
664         rcu_read_lock();
665         list_for_each_entry_rcu(inc, &ipvs->tcp_apps[hash], p_list) {
666                 if (inc->port == cp->vport) {
667                         if (unlikely(!ip_vs_app_inc_get(inc)))
668                                 break;
669                         rcu_read_unlock();
670 
671                         IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
672                                       "%s:%u to app %s on port %u\n",
673                                       __func__,
674                                       IP_VS_DBG_ADDR(cp->af, &cp->caddr),
675                                       ntohs(cp->cport),
676                                       IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
677                                       ntohs(cp->vport),
678                                       inc->name, ntohs(inc->port));
679 
680                         cp->app = inc;
681                         if (inc->init_conn)
682                                 result = inc->init_conn(inc, cp);
683                         goto out;
684                 }
685         }
686         rcu_read_unlock();
687 
688   out:
689         return result;
690 }
691 
692 
693 /*
694  *      Set LISTEN timeout. (ip_vs_conn_put will setup timer)
695  */
696 void ip_vs_tcp_conn_listen(struct ip_vs_conn *cp)
697 {
698         struct ip_vs_proto_data *pd = ip_vs_proto_data_get(cp->ipvs, IPPROTO_TCP);
699 
700         spin_lock_bh(&cp->lock);
701         cp->state = IP_VS_TCP_S_LISTEN;
702         cp->timeout = (pd ? pd->timeout_table[IP_VS_TCP_S_LISTEN]
703                            : tcp_timeouts[IP_VS_TCP_S_LISTEN]);
704         spin_unlock_bh(&cp->lock);
705 }
706 
707 /* ---------------------------------------------
708  *   timeouts is netns related now.
709  * ---------------------------------------------
710  */
711 static int __ip_vs_tcp_init(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
712 {
713         ip_vs_init_hash_table(ipvs->tcp_apps, TCP_APP_TAB_SIZE);
714         pd->timeout_table = ip_vs_create_timeout_table((int *)tcp_timeouts,
715                                                         sizeof(tcp_timeouts));
716         if (!pd->timeout_table)
717                 return -ENOMEM;
718         pd->tcp_state_table =  tcp_states;
719         return 0;
720 }
721 
722 static void __ip_vs_tcp_exit(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
723 {
724         kfree(pd->timeout_table);
725 }
726 
727 
728 struct ip_vs_protocol ip_vs_protocol_tcp = {
729         .name =                 "TCP",
730         .protocol =             IPPROTO_TCP,
731         .num_states =           IP_VS_TCP_S_LAST,
732         .dont_defrag =          0,
733         .init =                 NULL,
734         .exit =                 NULL,
735         .init_netns =           __ip_vs_tcp_init,
736         .exit_netns =           __ip_vs_tcp_exit,
737         .register_app =         tcp_register_app,
738         .unregister_app =       tcp_unregister_app,
739         .conn_schedule =        tcp_conn_schedule,
740         .conn_in_get =          ip_vs_conn_in_get_proto,
741         .conn_out_get =         ip_vs_conn_out_get_proto,
742         .snat_handler =         tcp_snat_handler,
743         .dnat_handler =         tcp_dnat_handler,
744         .csum_check =           tcp_csum_check,
745         .state_name =           tcp_state_name,
746         .state_transition =     tcp_state_transition,
747         .app_conn_bind =        tcp_app_conn_bind,
748         .debug_packet =         ip_vs_tcpudp_debug_packet,
749         .timeout_change =       tcp_timeout_change,
750 };
751 

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