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Linux 2.6.19-rc6
[cris-mirror.git] / net / dccp / ipv4.c
blobe08e7688a263c82d0aca759a0bf68afd30b12392
1 /*
2 * net/dccp/ipv4.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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
13 #include <linux/dccp.h>
14 #include <linux/icmp.h>
15 #include <linux/module.h>
16 #include <linux/skbuff.h>
17 #include <linux/random.h>
18
19 #include <net/icmp.h>
20 #include <net/inet_common.h>
21 #include <net/inet_hashtables.h>
22 #include <net/inet_sock.h>
23 #include <net/protocol.h>
24 #include <net/sock.h>
25 #include <net/timewait_sock.h>
26 #include <net/tcp_states.h>
27 #include <net/xfrm.h>
28
29 #include "ackvec.h"
30 #include "ccid.h"
31 #include "dccp.h"
32 #include "feat.h"
33
34 /*
35 * This is the global socket data structure used for responding to
36 * the Out-of-the-blue (OOTB) packets. A control sock will be created
37 * for this socket at the initialization time.
38 */
39 static struct socket *dccp_v4_ctl_socket;
40
41 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
42 {
43 return inet_csk_get_port(&dccp_hashinfo, sk, snum,
44 inet_csk_bind_conflict);
45 }
46
47 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
48 {
49 struct inet_sock *inet = inet_sk(sk);
50 struct dccp_sock *dp = dccp_sk(sk);
51 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
52 struct rtable *rt;
53 __be32 daddr, nexthop;
54 int tmp;
55 int err;
56
57 dp->dccps_role = DCCP_ROLE_CLIENT;
58
59 if (addr_len < sizeof(struct sockaddr_in))
60 return -EINVAL;
61
62 if (usin->sin_family != AF_INET)
63 return -EAFNOSUPPORT;
64
65 nexthop = daddr = usin->sin_addr.s_addr;
66 if (inet->opt != NULL && inet->opt->srr) {
67 if (daddr == 0)
68 return -EINVAL;
69 nexthop = inet->opt->faddr;
70 }
71
72 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
73 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
74 IPPROTO_DCCP,
75 inet->sport, usin->sin_port, sk);
76 if (tmp < 0)
77 return tmp;
78
79 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
80 ip_rt_put(rt);
81 return -ENETUNREACH;
82 }
83
84 if (inet->opt == NULL || !inet->opt->srr)
85 daddr = rt->rt_dst;
86
87 if (inet->saddr == 0)
88 inet->saddr = rt->rt_src;
89 inet->rcv_saddr = inet->saddr;
90
91 inet->dport = usin->sin_port;
92 inet->daddr = daddr;
93
94 inet_csk(sk)->icsk_ext_hdr_len = 0;
95 if (inet->opt != NULL)
96 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
97 /*
98 * Socket identity is still unknown (sport may be zero).
99 * However we set state to DCCP_REQUESTING and not releasing socket
100 * lock select source port, enter ourselves into the hash tables and
101 * complete initialization after this.
102 */
103 dccp_set_state(sk, DCCP_REQUESTING);
104 err = inet_hash_connect(&dccp_death_row, sk);
105 if (err != 0)
106 goto failure;
107
108 err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
109 sk);
110 if (err != 0)
111 goto failure;
112
113 /* OK, now commit destination to socket. */
114 sk_setup_caps(sk, &rt->u.dst);
115
116 dp->dccps_gar =
117 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
118 inet->daddr,
119 inet->sport,
120 usin->sin_port);
121 dccp_update_gss(sk, dp->dccps_iss);
122
123 inet->id = dp->dccps_iss ^ jiffies;
124
125 err = dccp_connect(sk);
126 rt = NULL;
127 if (err != 0)
128 goto failure;
129 out:
130 return err;
131 failure:
132 /*
133 * This unhashes the socket and releases the local port, if necessary.
134 */
135 dccp_set_state(sk, DCCP_CLOSED);
136 ip_rt_put(rt);
137 sk->sk_route_caps = 0;
138 inet->dport = 0;
139 goto out;
140 }
141
142 EXPORT_SYMBOL_GPL(dccp_v4_connect);
143
144 /*
145 * This routine does path mtu discovery as defined in RFC1191.
146 */
147 static inline void dccp_do_pmtu_discovery(struct sock *sk,
148 const struct iphdr *iph,
149 u32 mtu)
150 {
151 struct dst_entry *dst;
152 const struct inet_sock *inet = inet_sk(sk);
153 const struct dccp_sock *dp = dccp_sk(sk);
154
155 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
156 * send out by Linux are always < 576bytes so they should go through
157 * unfragmented).
158 */
159 if (sk->sk_state == DCCP_LISTEN)
160 return;
161
162 /* We don't check in the destentry if pmtu discovery is forbidden
163 * on this route. We just assume that no packet_to_big packets
164 * are send back when pmtu discovery is not active.
165 * There is a small race when the user changes this flag in the
166 * route, but I think that's acceptable.
167 */
168 if ((dst = __sk_dst_check(sk, 0)) == NULL)
169 return;
170
171 dst->ops->update_pmtu(dst, mtu);
172
173 /* Something is about to be wrong... Remember soft error
174 * for the case, if this connection will not able to recover.
175 */
176 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
177 sk->sk_err_soft = EMSGSIZE;
178
179 mtu = dst_mtu(dst);
180
181 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
182 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
183 dccp_sync_mss(sk, mtu);
184
185 /*
186 * From RFC 4340, sec. 14.1:
187 *
188 * DCCP-Sync packets are the best choice for upward
189 * probing, since DCCP-Sync probes do not risk application
190 * data loss.
191 */
192 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
193 } /* else let the usual retransmit timer handle it */
194 }
195
196 static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
197 struct request_sock *req)
198 {
199 int err;
200 struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
201 const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
202 sizeof(struct dccp_hdr_ext) +
203 sizeof(struct dccp_hdr_ack_bits);
204 struct sk_buff *skb;
205
206 if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
207 return;
208
209 skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
210 if (skb == NULL)
211 return;
212
213 /* Reserve space for headers. */
214 skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
215
216 skb->dst = dst_clone(rxskb->dst);
217
218 skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
219 dh = dccp_hdr(skb);
220 memset(dh, 0, dccp_hdr_ack_len);
221
222 /* Build DCCP header and checksum it. */
223 dh->dccph_type = DCCP_PKT_ACK;
224 dh->dccph_sport = rxdh->dccph_dport;
225 dh->dccph_dport = rxdh->dccph_sport;
226 dh->dccph_doff = dccp_hdr_ack_len / 4;
227 dh->dccph_x = 1;
228
229 dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
230 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
231 DCCP_SKB_CB(rxskb)->dccpd_seq);
232
233 bh_lock_sock(dccp_v4_ctl_socket->sk);
234 err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
235 rxskb->nh.iph->daddr,
236 rxskb->nh.iph->saddr, NULL);
237 bh_unlock_sock(dccp_v4_ctl_socket->sk);
238
239 if (err == NET_XMIT_CN || err == 0) {
240 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
241 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
242 }
243 }
244
245 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
246 struct dst_entry *dst)
247 {
248 int err = -1;
249 struct sk_buff *skb;
250
251 /* First, grab a route. */
252
253 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
254 goto out;
255
256 skb = dccp_make_response(sk, dst, req);
257 if (skb != NULL) {
258 const struct inet_request_sock *ireq = inet_rsk(req);
259 struct dccp_hdr *dh = dccp_hdr(skb);
260
261 dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
262 ireq->rmt_addr);
263 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
264 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
265 ireq->rmt_addr,
266 ireq->opt);
267 if (err == NET_XMIT_CN)
268 err = 0;
269 }
270
271 out:
272 dst_release(dst);
273 return err;
274 }
275
276 /*
277 * This routine is called by the ICMP module when it gets some sort of error
278 * condition. If err < 0 then the socket should be closed and the error
279 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
280 * After adjustment header points to the first 8 bytes of the tcp header. We
281 * need to find the appropriate port.
282 *
283 * The locking strategy used here is very "optimistic". When someone else
284 * accesses the socket the ICMP is just dropped and for some paths there is no
285 * check at all. A more general error queue to queue errors for later handling
286 * is probably better.
287 */
288 static void dccp_v4_err(struct sk_buff *skb, u32 info)
289 {
290 const struct iphdr *iph = (struct iphdr *)skb->data;
291 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
292 (iph->ihl << 2));
293 struct dccp_sock *dp;
294 struct inet_sock *inet;
295 const int type = skb->h.icmph->type;
296 const int code = skb->h.icmph->code;
297 struct sock *sk;
298 __u64 seq;
299 int err;
300
301 if (skb->len < (iph->ihl << 2) + 8) {
302 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
303 return;
304 }
305
306 sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
307 iph->saddr, dh->dccph_sport, inet_iif(skb));
308 if (sk == NULL) {
309 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
310 return;
311 }
312
313 if (sk->sk_state == DCCP_TIME_WAIT) {
314 inet_twsk_put(inet_twsk(sk));
315 return;
316 }
317
318 bh_lock_sock(sk);
319 /* If too many ICMPs get dropped on busy
320 * servers this needs to be solved differently.
321 */
322 if (sock_owned_by_user(sk))
323 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
324
325 if (sk->sk_state == DCCP_CLOSED)
326 goto out;
327
328 dp = dccp_sk(sk);
329 seq = dccp_hdr_seq(skb);
330 if (sk->sk_state != DCCP_LISTEN &&
331 !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
332 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
333 goto out;
334 }
335
336 switch (type) {
337 case ICMP_SOURCE_QUENCH:
338 /* Just silently ignore these. */
339 goto out;
340 case ICMP_PARAMETERPROB:
341 err = EPROTO;
342 break;
343 case ICMP_DEST_UNREACH:
344 if (code > NR_ICMP_UNREACH)
345 goto out;
346
347 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
348 if (!sock_owned_by_user(sk))
349 dccp_do_pmtu_discovery(sk, iph, info);
350 goto out;
351 }
352
353 err = icmp_err_convert[code].errno;
354 break;
355 case ICMP_TIME_EXCEEDED:
356 err = EHOSTUNREACH;
357 break;
358 default:
359 goto out;
360 }
361
362 switch (sk->sk_state) {
363 struct request_sock *req , **prev;
364 case DCCP_LISTEN:
365 if (sock_owned_by_user(sk))
366 goto out;
367 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
368 iph->daddr, iph->saddr);
369 if (!req)
370 goto out;
371
372 /*
373 * ICMPs are not backlogged, hence we cannot get an established
374 * socket here.
375 */
376 BUG_TRAP(!req->sk);
377
378 if (seq != dccp_rsk(req)->dreq_iss) {
379 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
380 goto out;
381 }
382 /*
383 * Still in RESPOND, just remove it silently.
384 * There is no good way to pass the error to the newly
385 * created socket, and POSIX does not want network
386 * errors returned from accept().
387 */
388 inet_csk_reqsk_queue_drop(sk, req, prev);
389 goto out;
390
391 case DCCP_REQUESTING:
392 case DCCP_RESPOND:
393 if (!sock_owned_by_user(sk)) {
394 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
395 sk->sk_err = err;
396
397 sk->sk_error_report(sk);
398
399 dccp_done(sk);
400 } else
401 sk->sk_err_soft = err;
402 goto out;
403 }
404
405 /* If we've already connected we will keep trying
406 * until we time out, or the user gives up.
407 *
408 * rfc1122 4.2.3.9 allows to consider as hard errors
409 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
410 * but it is obsoleted by pmtu discovery).
411 *
412 * Note, that in modern internet, where routing is unreliable
413 * and in each dark corner broken firewalls sit, sending random
414 * errors ordered by their masters even this two messages finally lose
415 * their original sense (even Linux sends invalid PORT_UNREACHs)
416 *
417 * Now we are in compliance with RFCs.
418 * --ANK (980905)
419 */
420
421 inet = inet_sk(sk);
422 if (!sock_owned_by_user(sk) && inet->recverr) {
423 sk->sk_err = err;
424 sk->sk_error_report(sk);
425 } else /* Only an error on timeout */
426 sk->sk_err_soft = err;
427 out:
428 bh_unlock_sock(sk);
429 sock_put(sk);
430 }
431
432 /* This routine computes an IPv4 DCCP checksum. */
433 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
434 {
435 const struct inet_sock *inet = inet_sk(sk);
436 struct dccp_hdr *dh = dccp_hdr(skb);
437
438 dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
439 }
440
441 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
442
443 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
444 const struct sk_buff *skb)
445 {
446 return secure_dccp_sequence_number(skb->nh.iph->daddr,
447 skb->nh.iph->saddr,
448 dccp_hdr(skb)->dccph_dport,
449 dccp_hdr(skb)->dccph_sport);
450 }
451
452 static struct request_sock_ops dccp_request_sock_ops;
453
454 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
455 {
456 struct inet_request_sock *ireq;
457 struct dccp_sock dp;
458 struct request_sock *req;
459 struct dccp_request_sock *dreq;
460 const __be32 saddr = skb->nh.iph->saddr;
461 const __be32 daddr = skb->nh.iph->daddr;
462 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
463 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
464 __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
465
466 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
467 if (((struct rtable *)skb->dst)->rt_flags &
468 (RTCF_BROADCAST | RTCF_MULTICAST)) {
469 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
470 goto drop;
471 }
472
473 if (dccp_bad_service_code(sk, service)) {
474 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
475 goto drop;
476 }
477 /*
478 * TW buckets are converted to open requests without
479 * limitations, they conserve resources and peer is
480 * evidently real one.
481 */
482 if (inet_csk_reqsk_queue_is_full(sk))
483 goto drop;
484
485 /*
486 * Accept backlog is full. If we have already queued enough
487 * of warm entries in syn queue, drop request. It is better than
488 * clogging syn queue with openreqs with exponentially increasing
489 * timeout.
490 */
491 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
492 goto drop;
493
494 req = reqsk_alloc(&dccp_request_sock_ops);
495 if (req == NULL)
496 goto drop;
497
498 if (dccp_parse_options(sk, skb))
499 goto drop_and_free;
500
501 dccp_openreq_init(req, &dp, skb);
502
503 if (security_inet_conn_request(sk, skb, req))
504 goto drop_and_free;
505
506 ireq = inet_rsk(req);
507 ireq->loc_addr = daddr;
508 ireq->rmt_addr = saddr;
509 req->rcv_wnd = dccp_feat_default_sequence_window;
510 ireq->opt = NULL;
511
512 /*
513 * Step 3: Process LISTEN state
514 *
515 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
516 *
517 * In fact we defer setting S.GSR, S.SWL, S.SWH to
518 * dccp_create_openreq_child.
519 */
520 dreq = dccp_rsk(req);
521 dreq->dreq_isr = dcb->dccpd_seq;
522 dreq->dreq_iss = dccp_v4_init_sequence(sk, skb);
523 dreq->dreq_service = service;
524
525 if (dccp_v4_send_response(sk, req, NULL))
526 goto drop_and_free;
527
528 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
529 return 0;
530
531 drop_and_free:
532 reqsk_free(req);
533 drop:
534 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
535 dcb->dccpd_reset_code = reset_code;
536 return -1;
537 }
538
539 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
540
541 /*
542 * The three way handshake has completed - we got a valid ACK or DATAACK -
543 * now create the new socket.
544 *
545 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
546 */
547 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
548 struct request_sock *req,
549 struct dst_entry *dst)
550 {
551 struct inet_request_sock *ireq;
552 struct inet_sock *newinet;
553 struct dccp_sock *newdp;
554 struct sock *newsk;
555
556 if (sk_acceptq_is_full(sk))
557 goto exit_overflow;
558
559 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
560 goto exit;
561
562 newsk = dccp_create_openreq_child(sk, req, skb);
563 if (newsk == NULL)
564 goto exit;
565
566 sk_setup_caps(newsk, dst);
567
568 newdp = dccp_sk(newsk);
569 newinet = inet_sk(newsk);
570 ireq = inet_rsk(req);
571 newinet->daddr = ireq->rmt_addr;
572 newinet->rcv_saddr = ireq->loc_addr;
573 newinet->saddr = ireq->loc_addr;
574 newinet->opt = ireq->opt;
575 ireq->opt = NULL;
576 newinet->mc_index = inet_iif(skb);
577 newinet->mc_ttl = skb->nh.iph->ttl;
578 newinet->id = jiffies;
579
580 dccp_sync_mss(newsk, dst_mtu(dst));
581
582 __inet_hash(&dccp_hashinfo, newsk, 0);
583 __inet_inherit_port(&dccp_hashinfo, sk, newsk);
584
585 return newsk;
586
587 exit_overflow:
588 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
589 exit:
590 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
591 dst_release(dst);
592 return NULL;
593 }
594
595 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
596
597 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
598 {
599 const struct dccp_hdr *dh = dccp_hdr(skb);
600 const struct iphdr *iph = skb->nh.iph;
601 struct sock *nsk;
602 struct request_sock **prev;
603 /* Find possible connection requests. */
604 struct request_sock *req = inet_csk_search_req(sk, &prev,
605 dh->dccph_sport,
606 iph->saddr, iph->daddr);
607 if (req != NULL)
608 return dccp_check_req(sk, skb, req, prev);
609
610 nsk = inet_lookup_established(&dccp_hashinfo,
611 iph->saddr, dh->dccph_sport,
612 iph->daddr, dh->dccph_dport,
613 inet_iif(skb));
614 if (nsk != NULL) {
615 if (nsk->sk_state != DCCP_TIME_WAIT) {
616 bh_lock_sock(nsk);
617 return nsk;
618 }
619 inet_twsk_put(inet_twsk(nsk));
620 return NULL;
621 }
622
623 return sk;
624 }
625
626 int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
627 const __be32 daddr)
628 {
629 const struct dccp_hdr* dh = dccp_hdr(skb);
630 int checksum_len;
631 u32 tmp;
632
633 if (dh->dccph_cscov == 0)
634 checksum_len = skb->len;
635 else {
636 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
637 checksum_len = checksum_len < skb->len ? checksum_len :
638 skb->len;
639 }
640
641 tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
642 return csum_tcpudp_magic(saddr, daddr, checksum_len,
643 IPPROTO_DCCP, tmp);
644 }
645
646 EXPORT_SYMBOL_GPL(dccp_v4_checksum);
647
648 static int dccp_v4_verify_checksum(struct sk_buff *skb,
649 const __be32 saddr, const __be32 daddr)
650 {
651 struct dccp_hdr *dh = dccp_hdr(skb);
652 int checksum_len;
653 u32 tmp;
654
655 if (dh->dccph_cscov == 0)
656 checksum_len = skb->len;
657 else {
658 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
659 checksum_len = checksum_len < skb->len ? checksum_len :
660 skb->len;
661 }
662 tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
663 return csum_tcpudp_magic(saddr, daddr, checksum_len,
664 IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
665 }
666
667 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
668 struct sk_buff *skb)
669 {
670 struct rtable *rt;
671 struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
672 .nl_u = { .ip4_u =
673 { .daddr = skb->nh.iph->saddr,
674 .saddr = skb->nh.iph->daddr,
675 .tos = RT_CONN_FLAGS(sk) } },
676 .proto = sk->sk_protocol,
677 .uli_u = { .ports =
678 { .sport = dccp_hdr(skb)->dccph_dport,
679 .dport = dccp_hdr(skb)->dccph_sport }
680 }
681 };
682
683 security_skb_classify_flow(skb, &fl);
684 if (ip_route_output_flow(&rt, &fl, sk, 0)) {
685 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
686 return NULL;
687 }
688
689 return &rt->u.dst;
690 }
691
692 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
693 {
694 int err;
695 struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
696 const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
697 sizeof(struct dccp_hdr_ext) +
698 sizeof(struct dccp_hdr_reset);
699 struct sk_buff *skb;
700 struct dst_entry *dst;
701 u64 seqno;
702
703 /* Never send a reset in response to a reset. */
704 if (rxdh->dccph_type == DCCP_PKT_RESET)
705 return;
706
707 if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
708 return;
709
710 dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
711 if (dst == NULL)
712 return;
713
714 skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header,
715 GFP_ATOMIC);
716 if (skb == NULL)
717 goto out;
718
719 /* Reserve space for headers. */
720 skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
721 skb->dst = dst_clone(dst);
722
723 skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
724 dh = dccp_hdr(skb);
725 memset(dh, 0, dccp_hdr_reset_len);
726
727 /* Build DCCP header and checksum it. */
728 dh->dccph_type = DCCP_PKT_RESET;
729 dh->dccph_sport = rxdh->dccph_dport;
730 dh->dccph_dport = rxdh->dccph_sport;
731 dh->dccph_doff = dccp_hdr_reset_len / 4;
732 dh->dccph_x = 1;
733 dccp_hdr_reset(skb)->dccph_reset_code =
734 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
735
736 /* See "8.3.1. Abnormal Termination" in RFC 4340 */
737 seqno = 0;
738 if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
739 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
740
741 dccp_hdr_set_seq(dh, seqno);
742 dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
743 DCCP_SKB_CB(rxskb)->dccpd_seq);
744
745 dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
746 rxskb->nh.iph->daddr);
747
748 bh_lock_sock(dccp_v4_ctl_socket->sk);
749 err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
750 rxskb->nh.iph->daddr,
751 rxskb->nh.iph->saddr, NULL);
752 bh_unlock_sock(dccp_v4_ctl_socket->sk);
753
754 if (err == NET_XMIT_CN || err == 0) {
755 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
756 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
757 }
758 out:
759 dst_release(dst);
760 }
761
762 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
763 {
764 struct dccp_hdr *dh = dccp_hdr(skb);
765
766 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
767 if (dccp_rcv_established(sk, skb, dh, skb->len))
768 goto reset;
769 return 0;
770 }
771
772 /*
773 * Step 3: Process LISTEN state
774 * If S.state == LISTEN,
775 * If P.type == Request or P contains a valid Init Cookie
776 * option,
777 * * Must scan the packet's options to check for an Init
778 * Cookie. Only the Init Cookie is processed here,
779 * however; other options are processed in Step 8. This
780 * scan need only be performed if the endpoint uses Init
781 * Cookies *
782 * * Generate a new socket and switch to that socket *
783 * Set S := new socket for this port pair
784 * S.state = RESPOND
785 * Choose S.ISS (initial seqno) or set from Init Cookie
786 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
787 * Continue with S.state == RESPOND
788 * * A Response packet will be generated in Step 11 *
789 * Otherwise,
790 * Generate Reset(No Connection) unless P.type == Reset
791 * Drop packet and return
792 *
793 * NOTE: the check for the packet types is done in
794 * dccp_rcv_state_process
795 */
796 if (sk->sk_state == DCCP_LISTEN) {
797 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
798
799 if (nsk == NULL)
800 goto discard;
801
802 if (nsk != sk) {
803 if (dccp_child_process(sk, nsk, skb))
804 goto reset;
805 return 0;
806 }
807 }
808
809 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
810 goto reset;
811 return 0;
812
813 reset:
814 dccp_v4_ctl_send_reset(skb);
815 discard:
816 kfree_skb(skb);
817 return 0;
818 }
819
820 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
821
822 int dccp_invalid_packet(struct sk_buff *skb)
823 {
824 const struct dccp_hdr *dh;
825
826 if (skb->pkt_type != PACKET_HOST)
827 return 1;
828
829 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
830 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
831 return 1;
832 }
833
834 dh = dccp_hdr(skb);
835
836 /* If the packet type is not understood, drop packet and return */
837 if (dh->dccph_type >= DCCP_PKT_INVALID) {
838 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
839 return 1;
840 }
841
842 /*
843 * If P.Data Offset is too small for packet type, or too large for
844 * packet, drop packet and return
845 */
846 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
847 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
848 "too small 1\n",
849 dh->dccph_doff);
850 return 1;
851 }
852
853 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
854 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
855 "too small 2\n",
856 dh->dccph_doff);
857 return 1;
858 }
859
860 dh = dccp_hdr(skb);
861
862 /*
863 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
864 * has short sequence numbers), drop packet and return
865 */
866 if (dh->dccph_x == 0 &&
867 dh->dccph_type != DCCP_PKT_DATA &&
868 dh->dccph_type != DCCP_PKT_ACK &&
869 dh->dccph_type != DCCP_PKT_DATAACK) {
870 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
871 "nor DataAck and P.X == 0\n",
872 dccp_packet_name(dh->dccph_type));
873 return 1;
874 }
875
876 return 0;
877 }
878
879 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
880
881 /* this is called when real data arrives */
882 static int dccp_v4_rcv(struct sk_buff *skb)
883 {
884 const struct dccp_hdr *dh;
885 struct sock *sk;
886
887 /* Step 1: Check header basics: */
888
889 if (dccp_invalid_packet(skb))
890 goto discard_it;
891
892 /* If the header checksum is incorrect, drop packet and return */
893 if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
894 skb->nh.iph->daddr) < 0) {
895 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
896 __FUNCTION__);
897 goto discard_it;
898 }
899
900 dh = dccp_hdr(skb);
901
902 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(skb);
903 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
904
905 dccp_pr_debug("%8.8s "
906 "src=%u.%u.%u.%u@%-5d "
907 "dst=%u.%u.%u.%u@%-5d seq=%llu",
908 dccp_packet_name(dh->dccph_type),
909 NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
910 NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
911 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
912
913 if (dccp_packet_without_ack(skb)) {
914 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
915 dccp_pr_debug_cat("\n");
916 } else {
917 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
918 dccp_pr_debug_cat(", ack=%llu\n",
919 (unsigned long long)
920 DCCP_SKB_CB(skb)->dccpd_ack_seq);
921 }
922
923 /* Step 2:
924 * Look up flow ID in table and get corresponding socket */
925 sk = __inet_lookup(&dccp_hashinfo,
926 skb->nh.iph->saddr, dh->dccph_sport,
927 skb->nh.iph->daddr, dh->dccph_dport,
928 inet_iif(skb));
929
930 /*
931 * Step 2:
932 * If no socket ...
933 * Generate Reset(No Connection) unless P.type == Reset
934 * Drop packet and return
935 */
936 if (sk == NULL) {
937 dccp_pr_debug("failed to look up flow ID in table and "
938 "get corresponding socket\n");
939 goto no_dccp_socket;
940 }
941
942 /*
943 * Step 2:
944 * ... or S.state == TIMEWAIT,
945 * Generate Reset(No Connection) unless P.type == Reset
946 * Drop packet and return
947 */
948
949 if (sk->sk_state == DCCP_TIME_WAIT) {
950 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
951 "do_time_wait\n");
952 goto do_time_wait;
953 }
954
955 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
956 goto discard_and_relse;
957 nf_reset(skb);
958
959 return sk_receive_skb(sk, skb);
960
961 no_dccp_socket:
962 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
963 goto discard_it;
964 /*
965 * Step 2:
966 * Generate Reset(No Connection) unless P.type == Reset
967 * Drop packet and return
968 */
969 if (dh->dccph_type != DCCP_PKT_RESET) {
970 DCCP_SKB_CB(skb)->dccpd_reset_code =
971 DCCP_RESET_CODE_NO_CONNECTION;
972 dccp_v4_ctl_send_reset(skb);
973 }
974
975 discard_it:
976 /* Discard frame. */
977 kfree_skb(skb);
978 return 0;
979
980 discard_and_relse:
981 sock_put(sk);
982 goto discard_it;
983
984 do_time_wait:
985 inet_twsk_put(inet_twsk(sk));
986 goto no_dccp_socket;
987 }
988
989 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
990 .queue_xmit = ip_queue_xmit,
991 .send_check = dccp_v4_send_check,
992 .rebuild_header = inet_sk_rebuild_header,
993 .conn_request = dccp_v4_conn_request,
994 .syn_recv_sock = dccp_v4_request_recv_sock,
995 .net_header_len = sizeof(struct iphdr),
996 .setsockopt = ip_setsockopt,
997 .getsockopt = ip_getsockopt,
998 .addr2sockaddr = inet_csk_addr2sockaddr,
999 .sockaddr_len = sizeof(struct sockaddr_in),
1000 #ifdef CONFIG_COMPAT
1001 .compat_setsockopt = compat_ip_setsockopt,
1002 .compat_getsockopt = compat_ip_getsockopt,
1003 #endif
1004 };
1005
1006 static int dccp_v4_init_sock(struct sock *sk)
1007 {
1008 static __u8 dccp_v4_ctl_sock_initialized;
1009 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
1010
1011 if (err == 0) {
1012 if (unlikely(!dccp_v4_ctl_sock_initialized))
1013 dccp_v4_ctl_sock_initialized = 1;
1014 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
1015 }
1016
1017 return err;
1018 }
1019
1020 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1021 {
1022 kfree(inet_rsk(req)->opt);
1023 }
1024
1025 static struct request_sock_ops dccp_request_sock_ops = {
1026 .family = PF_INET,
1027 .obj_size = sizeof(struct dccp_request_sock),
1028 .rtx_syn_ack = dccp_v4_send_response,
1029 .send_ack = dccp_v4_reqsk_send_ack,
1030 .destructor = dccp_v4_reqsk_destructor,
1031 .send_reset = dccp_v4_ctl_send_reset,
1032 };
1033
1034 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1035 .twsk_obj_size = sizeof(struct inet_timewait_sock),
1036 };
1037
1038 static struct proto dccp_v4_prot = {
1039 .name = "DCCP",
1040 .owner = THIS_MODULE,
1041 .close = dccp_close,
1042 .connect = dccp_v4_connect,
1043 .disconnect = dccp_disconnect,
1044 .ioctl = dccp_ioctl,
1045 .init = dccp_v4_init_sock,
1046 .setsockopt = dccp_setsockopt,
1047 .getsockopt = dccp_getsockopt,
1048 .sendmsg = dccp_sendmsg,
1049 .recvmsg = dccp_recvmsg,
1050 .backlog_rcv = dccp_v4_do_rcv,
1051 .hash = dccp_hash,
1052 .unhash = dccp_unhash,
1053 .accept = inet_csk_accept,
1054 .get_port = dccp_v4_get_port,
1055 .shutdown = dccp_shutdown,
1056 .destroy = dccp_destroy_sock,
1057 .orphan_count = &dccp_orphan_count,
1058 .max_header = MAX_DCCP_HEADER,
1059 .obj_size = sizeof(struct dccp_sock),
1060 .rsk_prot = &dccp_request_sock_ops,
1061 .twsk_prot = &dccp_timewait_sock_ops,
1062 #ifdef CONFIG_COMPAT
1063 .compat_setsockopt = compat_dccp_setsockopt,
1064 .compat_getsockopt = compat_dccp_getsockopt,
1065 #endif
1066 };
1067
1068 static struct net_protocol dccp_v4_protocol = {
1069 .handler = dccp_v4_rcv,
1070 .err_handler = dccp_v4_err,
1071 .no_policy = 1,
1072 };
1073
1074 static const struct proto_ops inet_dccp_ops = {
1075 .family = PF_INET,
1076 .owner = THIS_MODULE,
1077 .release = inet_release,
1078 .bind = inet_bind,
1079 .connect = inet_stream_connect,
1080 .socketpair = sock_no_socketpair,
1081 .accept = inet_accept,
1082 .getname = inet_getname,
1083 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1084 .poll = dccp_poll,
1085 .ioctl = inet_ioctl,
1086 /* FIXME: work on inet_listen to rename it to sock_common_listen */
1087 .listen = inet_dccp_listen,
1088 .shutdown = inet_shutdown,
1089 .setsockopt = sock_common_setsockopt,
1090 .getsockopt = sock_common_getsockopt,
1091 .sendmsg = inet_sendmsg,
1092 .recvmsg = sock_common_recvmsg,
1093 .mmap = sock_no_mmap,
1094 .sendpage = sock_no_sendpage,
1095 #ifdef CONFIG_COMPAT
1096 .compat_setsockopt = compat_sock_common_setsockopt,
1097 .compat_getsockopt = compat_sock_common_getsockopt,
1098 #endif
1099 };
1100
1101 static struct inet_protosw dccp_v4_protosw = {
1102 .type = SOCK_DCCP,
1103 .protocol = IPPROTO_DCCP,
1104 .prot = &dccp_v4_prot,
1105 .ops = &inet_dccp_ops,
1106 .capability = -1,
1107 .no_check = 0,
1108 .flags = INET_PROTOSW_ICSK,
1109 };
1110
1111 static int __init dccp_v4_init(void)
1112 {
1113 int err = proto_register(&dccp_v4_prot, 1);
1114
1115 if (err != 0)
1116 goto out;
1117
1118 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1119 if (err != 0)
1120 goto out_proto_unregister;
1121
1122 inet_register_protosw(&dccp_v4_protosw);
1123
1124 err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1125 SOCK_DCCP, IPPROTO_DCCP);
1126 if (err)
1127 goto out_unregister_protosw;
1128 out:
1129 return err;
1130 out_unregister_protosw:
1131 inet_unregister_protosw(&dccp_v4_protosw);
1132 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1133 out_proto_unregister:
1134 proto_unregister(&dccp_v4_prot);
1135 goto out;
1136 }
1137
1138 static void __exit dccp_v4_exit(void)
1139 {
1140 inet_unregister_protosw(&dccp_v4_protosw);
1141 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1142 proto_unregister(&dccp_v4_prot);
1143 }
1144
1145 module_init(dccp_v4_init);
1146 module_exit(dccp_v4_exit);
1147
1148 /*
1149 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1150 * values directly, Also cover the case where the protocol is not specified,
1151 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1152 */
1153 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-33-type-6");
1154 MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-0-type-6");
1155 MODULE_LICENSE("GPL");
1156 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1157 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
CRIS linux kernel tree