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Linux-2.6.12-rc2
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / net / ipv4 / ipvs / ip_vs_xmit.c
blobfaa6176bbeb195eb37329964d092c377a2489890
1 /*
2 * ip_vs_xmit.c: various packet transmitters for IPVS
3 *
4 * Version: $Id: ip_vs_xmit.c,v 1.2 2002/11/30 01:50:35 wensong Exp $
5 *
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
7 * Julian Anastasov <ja@ssi.bg>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 *
14 * Changes:
15 *
16 */
17
18 #include <linux/kernel.h>
19 #include <linux/ip.h>
20 #include <linux/tcp.h> /* for tcphdr */
21 #include <net/tcp.h> /* for csum_tcpudp_magic */
22 #include <net/udp.h>
23 #include <net/icmp.h> /* for icmp_send */
24 #include <net/route.h> /* for ip_route_output */
25 #include <linux/netfilter.h>
26 #include <linux/netfilter_ipv4.h>
27
28 #include <net/ip_vs.h>
29
30
31 /*
32 * Destination cache to speed up outgoing route lookup
33 */
34 static inline void
35 __ip_vs_dst_set(struct ip_vs_dest *dest, u32 rtos, struct dst_entry *dst)
36 {
37 struct dst_entry *old_dst;
38
39 old_dst = dest->dst_cache;
40 dest->dst_cache = dst;
41 dest->dst_rtos = rtos;
42 dst_release(old_dst);
43 }
44
45 static inline struct dst_entry *
46 __ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos, u32 cookie)
47 {
48 struct dst_entry *dst = dest->dst_cache;
49
50 if (!dst)
51 return NULL;
52 if ((dst->obsolete || rtos != dest->dst_rtos) &&
53 dst->ops->check(dst, cookie) == NULL) {
54 dest->dst_cache = NULL;
55 dst_release(dst);
56 return NULL;
57 }
58 dst_hold(dst);
59 return dst;
60 }
61
62 static inline struct rtable *
63 __ip_vs_get_out_rt(struct ip_vs_conn *cp, u32 rtos)
64 {
65 struct rtable *rt; /* Route to the other host */
66 struct ip_vs_dest *dest = cp->dest;
67
68 if (dest) {
69 spin_lock(&dest->dst_lock);
70 if (!(rt = (struct rtable *)
71 __ip_vs_dst_check(dest, rtos, 0))) {
72 struct flowi fl = {
73 .oif = 0,
74 .nl_u = {
75 .ip4_u = {
76 .daddr = dest->addr,
77 .saddr = 0,
78 .tos = rtos, } },
79 };
80
81 if (ip_route_output_key(&rt, &fl)) {
82 spin_unlock(&dest->dst_lock);
83 IP_VS_DBG_RL("ip_route_output error, "
84 "dest: %u.%u.%u.%u\n",
85 NIPQUAD(dest->addr));
86 return NULL;
87 }
88 __ip_vs_dst_set(dest, rtos, dst_clone(&rt->u.dst));
89 IP_VS_DBG(10, "new dst %u.%u.%u.%u, refcnt=%d, rtos=%X\n",
90 NIPQUAD(dest->addr),
91 atomic_read(&rt->u.dst.__refcnt), rtos);
92 }
93 spin_unlock(&dest->dst_lock);
94 } else {
95 struct flowi fl = {
96 .oif = 0,
97 .nl_u = {
98 .ip4_u = {
99 .daddr = cp->daddr,
100 .saddr = 0,
101 .tos = rtos, } },
102 };
103
104 if (ip_route_output_key(&rt, &fl)) {
105 IP_VS_DBG_RL("ip_route_output error, dest: "
106 "%u.%u.%u.%u\n", NIPQUAD(cp->daddr));
107 return NULL;
108 }
109 }
110
111 return rt;
112 }
113
114
115 /*
116 * Release dest->dst_cache before a dest is removed
117 */
118 void
119 ip_vs_dst_reset(struct ip_vs_dest *dest)
120 {
121 struct dst_entry *old_dst;
122
123 old_dst = dest->dst_cache;
124 dest->dst_cache = NULL;
125 dst_release(old_dst);
126 }
127
128 #define IP_VS_XMIT(skb, rt) \
129 do { \
130 nf_reset_debug(skb); \
131 (skb)->nfcache |= NFC_IPVS_PROPERTY; \
132 (skb)->ip_summed = CHECKSUM_NONE; \
133 NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, (skb), NULL, \
134 (rt)->u.dst.dev, dst_output); \
135 } while (0)
136
137
138 /*
139 * NULL transmitter (do nothing except return NF_ACCEPT)
140 */
141 int
142 ip_vs_null_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
143 struct ip_vs_protocol *pp)
144 {
145 /* we do not touch skb and do not need pskb ptr */
146 return NF_ACCEPT;
147 }
148
149
150 /*
151 * Bypass transmitter
152 * Let packets bypass the destination when the destination is not
153 * available, it may be only used in transparent cache cluster.
154 */
155 int
156 ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
157 struct ip_vs_protocol *pp)
158 {
159 struct rtable *rt; /* Route to the other host */
160 struct iphdr *iph = skb->nh.iph;
161 u8 tos = iph->tos;
162 int mtu;
163 struct flowi fl = {
164 .oif = 0,
165 .nl_u = {
166 .ip4_u = {
167 .daddr = iph->daddr,
168 .saddr = 0,
169 .tos = RT_TOS(tos), } },
170 };
171
172 EnterFunction(10);
173
174 if (ip_route_output_key(&rt, &fl)) {
175 IP_VS_DBG_RL("ip_vs_bypass_xmit(): ip_route_output error, "
176 "dest: %u.%u.%u.%u\n", NIPQUAD(iph->daddr));
177 goto tx_error_icmp;
178 }
179
180 /* MTU checking */
181 mtu = dst_mtu(&rt->u.dst);
182 if ((skb->len > mtu) && (iph->frag_off&__constant_htons(IP_DF))) {
183 ip_rt_put(rt);
184 icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
185 IP_VS_DBG_RL("ip_vs_bypass_xmit(): frag needed\n");
186 goto tx_error;
187 }
188
189 /*
190 * Call ip_send_check because we are not sure it is called
191 * after ip_defrag. Is copy-on-write needed?
192 */
193 if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
194 ip_rt_put(rt);
195 return NF_STOLEN;
196 }
197 ip_send_check(skb->nh.iph);
198
199 /* drop old route */
200 dst_release(skb->dst);
201 skb->dst = &rt->u.dst;
202
203 /* Another hack: avoid icmp_send in ip_fragment */
204 skb->local_df = 1;
205
206 IP_VS_XMIT(skb, rt);
207
208 LeaveFunction(10);
209 return NF_STOLEN;
210
211 tx_error_icmp:
212 dst_link_failure(skb);
213 tx_error:
214 kfree_skb(skb);
215 LeaveFunction(10);
216 return NF_STOLEN;
217 }
218
219
220 /*
221 * NAT transmitter (only for outside-to-inside nat forwarding)
222 * Not used for related ICMP
223 */
224 int
225 ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
226 struct ip_vs_protocol *pp)
227 {
228 struct rtable *rt; /* Route to the other host */
229 int mtu;
230 struct iphdr *iph = skb->nh.iph;
231
232 EnterFunction(10);
233
234 /* check if it is a connection of no-client-port */
235 if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
236 __u16 _pt, *p;
237 p = skb_header_pointer(skb, iph->ihl*4, sizeof(_pt), &_pt);
238 if (p == NULL)
239 goto tx_error;
240 ip_vs_conn_fill_cport(cp, *p);
241 IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p));
242 }
243
244 if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
245 goto tx_error_icmp;
246
247 /* MTU checking */
248 mtu = dst_mtu(&rt->u.dst);
249 if ((skb->len > mtu) && (iph->frag_off&__constant_htons(IP_DF))) {
250 ip_rt_put(rt);
251 icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
252 IP_VS_DBG_RL_PKT(0, pp, skb, 0, "ip_vs_nat_xmit(): frag needed for");
253 goto tx_error;
254 }
255
256 /* copy-on-write the packet before mangling it */
257 if (!ip_vs_make_skb_writable(&skb, sizeof(struct iphdr)))
258 goto tx_error_put;
259
260 if (skb_cow(skb, rt->u.dst.dev->hard_header_len))
261 goto tx_error_put;
262
263 /* drop old route */
264 dst_release(skb->dst);
265 skb->dst = &rt->u.dst;
266
267 /* mangle the packet */
268 if (pp->dnat_handler && !pp->dnat_handler(&skb, pp, cp))
269 goto tx_error;
270 skb->nh.iph->daddr = cp->daddr;
271 ip_send_check(skb->nh.iph);
272
273 IP_VS_DBG_PKT(10, pp, skb, 0, "After DNAT");
274
275 /* FIXME: when application helper enlarges the packet and the length
276 is larger than the MTU of outgoing device, there will be still
277 MTU problem. */
278
279 /* Another hack: avoid icmp_send in ip_fragment */
280 skb->local_df = 1;
281
282 IP_VS_XMIT(skb, rt);
283
284 LeaveFunction(10);
285 return NF_STOLEN;
286
287 tx_error_icmp:
288 dst_link_failure(skb);
289 tx_error:
290 LeaveFunction(10);
291 kfree_skb(skb);
292 return NF_STOLEN;
293 tx_error_put:
294 ip_rt_put(rt);
295 goto tx_error;
296 }
297
298
299 /*
300 * IP Tunneling transmitter
301 *
302 * This function encapsulates the packet in a new IP packet, its
303 * destination will be set to cp->daddr. Most code of this function
304 * is taken from ipip.c.
305 *
306 * It is used in VS/TUN cluster. The load balancer selects a real
307 * server from a cluster based on a scheduling algorithm,
308 * encapsulates the request packet and forwards it to the selected
309 * server. For example, all real servers are configured with
310 * "ifconfig tunl0 <Virtual IP Address> up". When the server receives
311 * the encapsulated packet, it will decapsulate the packet, processe
312 * the request and return the response packets directly to the client
313 * without passing the load balancer. This can greatly increase the
314 * scalability of virtual server.
315 *
316 * Used for ANY protocol
317 */
318 int
319 ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
320 struct ip_vs_protocol *pp)
321 {
322 struct rtable *rt; /* Route to the other host */
323 struct net_device *tdev; /* Device to other host */
324 struct iphdr *old_iph = skb->nh.iph;
325 u8 tos = old_iph->tos;
326 u16 df = old_iph->frag_off;
327 struct iphdr *iph; /* Our new IP header */
328 int max_headroom; /* The extra header space needed */
329 int mtu;
330
331 EnterFunction(10);
332
333 if (skb->protocol != __constant_htons(ETH_P_IP)) {
334 IP_VS_DBG_RL("ip_vs_tunnel_xmit(): protocol error, "
335 "ETH_P_IP: %d, skb protocol: %d\n",
336 __constant_htons(ETH_P_IP), skb->protocol);
337 goto tx_error;
338 }
339
340 if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(tos))))
341 goto tx_error_icmp;
342
343 tdev = rt->u.dst.dev;
344
345 mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
346 if (mtu < 68) {
347 ip_rt_put(rt);
348 IP_VS_DBG_RL("ip_vs_tunnel_xmit(): mtu less than 68\n");
349 goto tx_error;
350 }
351 if (skb->dst)
352 skb->dst->ops->update_pmtu(skb->dst, mtu);
353
354 df |= (old_iph->frag_off&__constant_htons(IP_DF));
355
356 if ((old_iph->frag_off&__constant_htons(IP_DF))
357 && mtu < ntohs(old_iph->tot_len)) {
358 icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
359 ip_rt_put(rt);
360 IP_VS_DBG_RL("ip_vs_tunnel_xmit(): frag needed\n");
361 goto tx_error;
362 }
363
364 /*
365 * Okay, now see if we can stuff it in the buffer as-is.
366 */
367 max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
368
369 if (skb_headroom(skb) < max_headroom
370 || skb_cloned(skb) || skb_shared(skb)) {
371 struct sk_buff *new_skb =
372 skb_realloc_headroom(skb, max_headroom);
373 if (!new_skb) {
374 ip_rt_put(rt);
375 kfree_skb(skb);
376 IP_VS_ERR_RL("ip_vs_tunnel_xmit(): no memory\n");
377 return NF_STOLEN;
378 }
379 kfree_skb(skb);
380 skb = new_skb;
381 old_iph = skb->nh.iph;
382 }
383
384 skb->h.raw = (void *) old_iph;
385
386 /* fix old IP header checksum */
387 ip_send_check(old_iph);
388
389 skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
390 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
391
392 /* drop old route */
393 dst_release(skb->dst);
394 skb->dst = &rt->u.dst;
395
396 /*
397 * Push down and install the IPIP header.
398 */
399 iph = skb->nh.iph;
400 iph->version = 4;
401 iph->ihl = sizeof(struct iphdr)>>2;
402 iph->frag_off = df;
403 iph->protocol = IPPROTO_IPIP;
404 iph->tos = tos;
405 iph->daddr = rt->rt_dst;
406 iph->saddr = rt->rt_src;
407 iph->ttl = old_iph->ttl;
408 iph->tot_len = htons(skb->len);
409 ip_select_ident(iph, &rt->u.dst, NULL);
410 ip_send_check(iph);
411
412 /* Another hack: avoid icmp_send in ip_fragment */
413 skb->local_df = 1;
414
415 IP_VS_XMIT(skb, rt);
416
417 LeaveFunction(10);
418
419 return NF_STOLEN;
420
421 tx_error_icmp:
422 dst_link_failure(skb);
423 tx_error:
424 kfree_skb(skb);
425 LeaveFunction(10);
426 return NF_STOLEN;
427 }
428
429
430 /*
431 * Direct Routing transmitter
432 * Used for ANY protocol
433 */
434 int
435 ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
436 struct ip_vs_protocol *pp)
437 {
438 struct rtable *rt; /* Route to the other host */
439 struct iphdr *iph = skb->nh.iph;
440 int mtu;
441
442 EnterFunction(10);
443
444 if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(iph->tos))))
445 goto tx_error_icmp;
446
447 /* MTU checking */
448 mtu = dst_mtu(&rt->u.dst);
449 if ((iph->frag_off&__constant_htons(IP_DF)) && skb->len > mtu) {
450 icmp_send(skb, ICMP_DEST_UNREACH,ICMP_FRAG_NEEDED, htonl(mtu));
451 ip_rt_put(rt);
452 IP_VS_DBG_RL("ip_vs_dr_xmit(): frag needed\n");
453 goto tx_error;
454 }
455
456 /*
457 * Call ip_send_check because we are not sure it is called
458 * after ip_defrag. Is copy-on-write needed?
459 */
460 if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
461 ip_rt_put(rt);
462 return NF_STOLEN;
463 }
464 ip_send_check(skb->nh.iph);
465
466 /* drop old route */
467 dst_release(skb->dst);
468 skb->dst = &rt->u.dst;
469
470 /* Another hack: avoid icmp_send in ip_fragment */
471 skb->local_df = 1;
472
473 IP_VS_XMIT(skb, rt);
474
475 LeaveFunction(10);
476 return NF_STOLEN;
477
478 tx_error_icmp:
479 dst_link_failure(skb);
480 tx_error:
481 kfree_skb(skb);
482 LeaveFunction(10);
483 return NF_STOLEN;
484 }
485
486
487 /*
488 * ICMP packet transmitter
489 * called by the ip_vs_in_icmp
490 */
491 int
492 ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
493 struct ip_vs_protocol *pp, int offset)
494 {
495 struct rtable *rt; /* Route to the other host */
496 int mtu;
497 int rc;
498
499 EnterFunction(10);
500
501 /* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
502 forwarded directly here, because there is no need to
503 translate address/port back */
504 if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) {
505 if (cp->packet_xmit)
506 rc = cp->packet_xmit(skb, cp, pp);
507 else
508 rc = NF_ACCEPT;
509 /* do not touch skb anymore */
510 atomic_inc(&cp->in_pkts);
511 __ip_vs_conn_put(cp);
512 goto out;
513 }
514
515 /*
516 * mangle and send the packet here (only for VS/NAT)
517 */
518
519 if (!(rt = __ip_vs_get_out_rt(cp, RT_TOS(skb->nh.iph->tos))))
520 goto tx_error_icmp;
521
522 /* MTU checking */
523 mtu = dst_mtu(&rt->u.dst);
524 if ((skb->len > mtu) && (skb->nh.iph->frag_off&__constant_htons(IP_DF))) {
525 ip_rt_put(rt);
526 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
527 IP_VS_DBG_RL("ip_vs_in_icmp(): frag needed\n");
528 goto tx_error;
529 }
530
531 /* copy-on-write the packet before mangling it */
532 if (!ip_vs_make_skb_writable(&skb, offset))
533 goto tx_error_put;
534
535 if (skb_cow(skb, rt->u.dst.dev->hard_header_len))
536 goto tx_error_put;
537
538 /* drop the old route when skb is not shared */
539 dst_release(skb->dst);
540 skb->dst = &rt->u.dst;
541
542 ip_vs_nat_icmp(skb, pp, cp, 0);
543
544 /* Another hack: avoid icmp_send in ip_fragment */
545 skb->local_df = 1;
546
547 IP_VS_XMIT(skb, rt);
548
549 rc = NF_STOLEN;
550 goto out;
551
552 tx_error_icmp:
553 dst_link_failure(skb);
554 tx_error:
555 dev_kfree_skb(skb);
556 rc = NF_STOLEN;
557 out:
558 LeaveFunction(10);
559 return rc;
560 tx_error_put:
561 ip_rt_put(rt);
562 goto tx_error;
563 }
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