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 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
42 {
43 struct inet_sock *inet = inet_sk(sk);
44 struct dccp_sock *dp = dccp_sk(sk);
45 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
46 struct rtable *rt;
47 __be32 daddr, nexthop;
48 int tmp;
49 int err;
50
51 dp->dccps_role = DCCP_ROLE_CLIENT;
52
53 if (addr_len < sizeof(struct sockaddr_in))
54 return -EINVAL;
55
56 if (usin->sin_family != AF_INET)
57 return -EAFNOSUPPORT;
58
59 nexthop = daddr = usin->sin_addr.s_addr;
60 if (inet->opt != NULL && inet->opt->srr) {
61 if (daddr == 0)
62 return -EINVAL;
63 nexthop = inet->opt->faddr;
64 }
65
66 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
67 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
68 IPPROTO_DCCP,
69 inet->sport, usin->sin_port, sk, 1);
70 if (tmp < 0)
71 return tmp;
72
73 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
74 ip_rt_put(rt);
75 return -ENETUNREACH;
76 }
77
78 if (inet->opt == NULL || !inet->opt->srr)
79 daddr = rt->rt_dst;
80
81 if (inet->saddr == 0)
82 inet->saddr = rt->rt_src;
83 inet->rcv_saddr = inet->saddr;
84
85 inet->dport = usin->sin_port;
86 inet->daddr = daddr;
87
88 inet_csk(sk)->icsk_ext_hdr_len = 0;
89 if (inet->opt != NULL)
90 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
91 /*
92 * Socket identity is still unknown (sport may be zero).
93 * However we set state to DCCP_REQUESTING and not releasing socket
94 * lock select source port, enter ourselves into the hash tables and
95 * complete initialization after this.
96 */
97 dccp_set_state(sk, DCCP_REQUESTING);
98 err = inet_hash_connect(&dccp_death_row, sk);
99 if (err != 0)
100 goto failure;
101
102 err = ip_route_newports(&rt, IPPROTO_DCCP, inet->sport, inet->dport,
103 sk);
104 if (err != 0)
105 goto failure;
106
107 /* OK, now commit destination to socket. */
108 sk_setup_caps(sk, &rt->u.dst);
109
110 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr, inet->daddr,
111 inet->sport, inet->dport);
112 inet->id = dp->dccps_iss ^ jiffies;
113
114 err = dccp_connect(sk);
115 rt = NULL;
116 if (err != 0)
117 goto failure;
118 out:
119 return err;
120 failure:
121 /*
122 * This unhashes the socket and releases the local port, if necessary.
123 */
124 dccp_set_state(sk, DCCP_CLOSED);
125 ip_rt_put(rt);
126 sk->sk_route_caps = 0;
127 inet->dport = 0;
128 goto out;
129 }
130
131 EXPORT_SYMBOL_GPL(dccp_v4_connect);
132
133 /*
134 * This routine does path mtu discovery as defined in RFC1191.
135 */
136 static inline void dccp_do_pmtu_discovery(struct sock *sk,
137 const struct iphdr *iph,
138 u32 mtu)
139 {
140 struct dst_entry *dst;
141 const struct inet_sock *inet = inet_sk(sk);
142 const struct dccp_sock *dp = dccp_sk(sk);
143
144 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
145 * send out by Linux are always < 576bytes so they should go through
146 * unfragmented).
147 */
148 if (sk->sk_state == DCCP_LISTEN)
149 return;
150
151 /* We don't check in the destentry if pmtu discovery is forbidden
152 * on this route. We just assume that no packet_to_big packets
153 * are send back when pmtu discovery is not active.
154 * There is a small race when the user changes this flag in the
155 * route, but I think that's acceptable.
156 */
157 if ((dst = __sk_dst_check(sk, 0)) == NULL)
158 return;
159
160 dst->ops->update_pmtu(dst, mtu);
161
162 /* Something is about to be wrong... Remember soft error
163 * for the case, if this connection will not able to recover.
164 */
165 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
166 sk->sk_err_soft = EMSGSIZE;
167
168 mtu = dst_mtu(dst);
169
170 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
171 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
172 dccp_sync_mss(sk, mtu);
173
174 /*
175 * From RFC 4340, sec. 14.1:
176 *
177 * DCCP-Sync packets are the best choice for upward
178 * probing, since DCCP-Sync probes do not risk application
179 * data loss.
180 */
181 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
182 } /* else let the usual retransmit timer handle it */
183 }
184
185 /*
186 * This routine is called by the ICMP module when it gets some sort of error
187 * condition. If err < 0 then the socket should be closed and the error
188 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
189 * After adjustment header points to the first 8 bytes of the tcp header. We
190 * need to find the appropriate port.
191 *
192 * The locking strategy used here is very "optimistic". When someone else
193 * accesses the socket the ICMP is just dropped and for some paths there is no
194 * check at all. A more general error queue to queue errors for later handling
195 * is probably better.
196 */
197 static void dccp_v4_err(struct sk_buff *skb, u32 info)
198 {
199 const struct iphdr *iph = (struct iphdr *)skb->data;
200 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
201 (iph->ihl << 2));
202 struct dccp_sock *dp;
203 struct inet_sock *inet;
204 const int type = icmp_hdr(skb)->type;
205 const int code = icmp_hdr(skb)->code;
206 struct sock *sk;
207 __u64 seq;
208 int err;
209
210 if (skb->len < (iph->ihl << 2) + 8) {
211 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
212 return;
213 }
214
215 sk = inet_lookup(&init_net, &dccp_hashinfo, iph->daddr, dh->dccph_dport,
216 iph->saddr, dh->dccph_sport, inet_iif(skb));
217 if (sk == NULL) {
218 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
219 return;
220 }
221
222 if (sk->sk_state == DCCP_TIME_WAIT) {
223 inet_twsk_put(inet_twsk(sk));
224 return;
225 }
226
227 bh_lock_sock(sk);
228 /* If too many ICMPs get dropped on busy
229 * servers this needs to be solved differently.
230 */
231 if (sock_owned_by_user(sk))
232 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
233
234 if (sk->sk_state == DCCP_CLOSED)
235 goto out;
236
237 dp = dccp_sk(sk);
238 seq = dccp_hdr_seq(dh);
239 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
240 !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
241 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
242 goto out;
243 }
244
245 switch (type) {
246 case ICMP_SOURCE_QUENCH:
247 /* Just silently ignore these. */
248 goto out;
249 case ICMP_PARAMETERPROB:
250 err = EPROTO;
251 break;
252 case ICMP_DEST_UNREACH:
253 if (code > NR_ICMP_UNREACH)
254 goto out;
255
256 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
257 if (!sock_owned_by_user(sk))
258 dccp_do_pmtu_discovery(sk, iph, info);
259 goto out;
260 }
261
262 err = icmp_err_convert[code].errno;
263 break;
264 case ICMP_TIME_EXCEEDED:
265 err = EHOSTUNREACH;
266 break;
267 default:
268 goto out;
269 }
270
271 switch (sk->sk_state) {
272 struct request_sock *req , **prev;
273 case DCCP_LISTEN:
274 if (sock_owned_by_user(sk))
275 goto out;
276 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
277 iph->daddr, iph->saddr);
278 if (!req)
279 goto out;
280
281 /*
282 * ICMPs are not backlogged, hence we cannot get an established
283 * socket here.
284 */
285 BUG_TRAP(!req->sk);
286
287 if (seq != dccp_rsk(req)->dreq_iss) {
288 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
289 goto out;
290 }
291 /*
292 * Still in RESPOND, just remove it silently.
293 * There is no good way to pass the error to the newly
294 * created socket, and POSIX does not want network
295 * errors returned from accept().
296 */
297 inet_csk_reqsk_queue_drop(sk, req, prev);
298 goto out;
299
300 case DCCP_REQUESTING:
301 case DCCP_RESPOND:
302 if (!sock_owned_by_user(sk)) {
303 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
304 sk->sk_err = err;
305
306 sk->sk_error_report(sk);
307
308 dccp_done(sk);
309 } else
310 sk->sk_err_soft = err;
311 goto out;
312 }
313
314 /* If we've already connected we will keep trying
315 * until we time out, or the user gives up.
316 *
317 * rfc1122 4.2.3.9 allows to consider as hard errors
318 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
319 * but it is obsoleted by pmtu discovery).
320 *
321 * Note, that in modern internet, where routing is unreliable
322 * and in each dark corner broken firewalls sit, sending random
323 * errors ordered by their masters even this two messages finally lose
324 * their original sense (even Linux sends invalid PORT_UNREACHs)
325 *
326 * Now we are in compliance with RFCs.
327 * --ANK (980905)
328 */
329
330 inet = inet_sk(sk);
331 if (!sock_owned_by_user(sk) && inet->recverr) {
332 sk->sk_err = err;
333 sk->sk_error_report(sk);
334 } else /* Only an error on timeout */
335 sk->sk_err_soft = err;
336 out:
337 bh_unlock_sock(sk);
338 sock_put(sk);
339 }
340
341 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
342 __be32 src, __be32 dst)
343 {
344 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
345 }
346
347 void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
348 {
349 const struct inet_sock *inet = inet_sk(sk);
350 struct dccp_hdr *dh = dccp_hdr(skb);
351
352 dccp_csum_outgoing(skb);
353 dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
354 }
355
356 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
357
358 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
359 {
360 return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
361 ip_hdr(skb)->saddr,
362 dccp_hdr(skb)->dccph_dport,
363 dccp_hdr(skb)->dccph_sport);
364 }
365
366 /*
367 * The three way handshake has completed - we got a valid ACK or DATAACK -
368 * now create the new socket.
369 *
370 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
371 */
372 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
373 struct request_sock *req,
374 struct dst_entry *dst)
375 {
376 struct inet_request_sock *ireq;
377 struct inet_sock *newinet;
378 struct sock *newsk;
379
380 if (sk_acceptq_is_full(sk))
381 goto exit_overflow;
382
383 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
384 goto exit;
385
386 newsk = dccp_create_openreq_child(sk, req, skb);
387 if (newsk == NULL)
388 goto exit;
389
390 sk_setup_caps(newsk, dst);
391
392 newinet = inet_sk(newsk);
393 ireq = inet_rsk(req);
394 newinet->daddr = ireq->rmt_addr;
395 newinet->rcv_saddr = ireq->loc_addr;
396 newinet->saddr = ireq->loc_addr;
397 newinet->opt = ireq->opt;
398 ireq->opt = NULL;
399 newinet->mc_index = inet_iif(skb);
400 newinet->mc_ttl = ip_hdr(skb)->ttl;
401 newinet->id = jiffies;
402
403 dccp_sync_mss(newsk, dst_mtu(dst));
404
405 __inet_hash_nolisten(newsk);
406 __inet_inherit_port(sk, newsk);
407
408 return newsk;
409
410 exit_overflow:
411 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
412 exit:
413 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
414 dst_release(dst);
415 return NULL;
416 }
417
418 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
419
420 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
421 {
422 const struct dccp_hdr *dh = dccp_hdr(skb);
423 const struct iphdr *iph = ip_hdr(skb);
424 struct sock *nsk;
425 struct request_sock **prev;
426 /* Find possible connection requests. */
427 struct request_sock *req = inet_csk_search_req(sk, &prev,
428 dh->dccph_sport,
429 iph->saddr, iph->daddr);
430 if (req != NULL)
431 return dccp_check_req(sk, skb, req, prev);
432
433 nsk = inet_lookup_established(&init_net, &dccp_hashinfo,
434 iph->saddr, dh->dccph_sport,
435 iph->daddr, dh->dccph_dport,
436 inet_iif(skb));
437 if (nsk != NULL) {
438 if (nsk->sk_state != DCCP_TIME_WAIT) {
439 bh_lock_sock(nsk);
440 return nsk;
441 }
442 inet_twsk_put(inet_twsk(nsk));
443 return NULL;
444 }
445
446 return sk;
447 }
448
449 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
450 struct sk_buff *skb)
451 {
452 struct rtable *rt;
453 struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
454 .nl_u = { .ip4_u =
455 { .daddr = ip_hdr(skb)->saddr,
456 .saddr = ip_hdr(skb)->daddr,
457 .tos = RT_CONN_FLAGS(sk) } },
458 .proto = sk->sk_protocol,
459 .uli_u = { .ports =
460 { .sport = dccp_hdr(skb)->dccph_dport,
461 .dport = dccp_hdr(skb)->dccph_sport }
462 }
463 };
464
465 security_skb_classify_flow(skb, &fl);
466 if (ip_route_output_flow(&init_net, &rt, &fl, sk, 0)) {
467 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
468 return NULL;
469 }
470
471 return &rt->u.dst;
472 }
473
474 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
475 struct dst_entry *dst)
476 {
477 int err = -1;
478 struct sk_buff *skb;
479
480 /* First, grab a route. */
481
482 if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
483 goto out;
484
485 skb = dccp_make_response(sk, dst, req);
486 if (skb != NULL) {
487 const struct inet_request_sock *ireq = inet_rsk(req);
488 struct dccp_hdr *dh = dccp_hdr(skb);
489
490 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
491 ireq->rmt_addr);
492 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
493 ireq->rmt_addr,
494 ireq->opt);
495 err = net_xmit_eval(err);
496 }
497
498 out:
499 dst_release(dst);
500 return err;
501 }
502
503 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
504 {
505 int err;
506 const struct iphdr *rxiph;
507 struct sk_buff *skb;
508 struct dst_entry *dst;
509
510 /* Never send a reset in response to a reset. */
511 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
512 return;
513
514 if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
515 return;
516
517 dst = dccp_v4_route_skb(dccp_v4_ctl_socket->sk, rxskb);
518 if (dst == NULL)
519 return;
520
521 skb = dccp_ctl_make_reset(dccp_v4_ctl_socket, rxskb);
522 if (skb == NULL)
523 goto out;
524
525 rxiph = ip_hdr(rxskb);
526 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
527 rxiph->daddr);
528 skb->dst = dst_clone(dst);
529
530 bh_lock_sock(dccp_v4_ctl_socket->sk);
531 err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
532 rxiph->daddr, rxiph->saddr, NULL);
533 bh_unlock_sock(dccp_v4_ctl_socket->sk);
534
535 if (net_xmit_eval(err) == 0) {
536 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
537 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
538 }
539 out:
540 dst_release(dst);
541 }
542
543 static void dccp_v4_reqsk_destructor(struct request_sock *req)
544 {
545 kfree(inet_rsk(req)->opt);
546 }
547
548 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
549 .family = PF_INET,
550 .obj_size = sizeof(struct dccp_request_sock),
551 .rtx_syn_ack = dccp_v4_send_response,
552 .send_ack = dccp_reqsk_send_ack,
553 .destructor = dccp_v4_reqsk_destructor,
554 .send_reset = dccp_v4_ctl_send_reset,
555 };
556
557 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
558 {
559 struct inet_request_sock *ireq;
560 struct request_sock *req;
561 struct dccp_request_sock *dreq;
562 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
563 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
564
565 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
566 if (((struct rtable *)skb->dst)->rt_flags &
567 (RTCF_BROADCAST | RTCF_MULTICAST))
568 return 0; /* discard, don't send a reset here */
569
570 if (dccp_bad_service_code(sk, service)) {
571 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
572 goto drop;
573 }
574 /*
575 * TW buckets are converted to open requests without
576 * limitations, they conserve resources and peer is
577 * evidently real one.
578 */
579 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
580 if (inet_csk_reqsk_queue_is_full(sk))
581 goto drop;
582
583 /*
584 * Accept backlog is full. If we have already queued enough
585 * of warm entries in syn queue, drop request. It is better than
586 * clogging syn queue with openreqs with exponentially increasing
587 * timeout.
588 */
589 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
590 goto drop;
591
592 req = reqsk_alloc(&dccp_request_sock_ops);
593 if (req == NULL)
594 goto drop;
595
596 dccp_reqsk_init(req, skb);
597
598 dreq = dccp_rsk(req);
599 if (dccp_parse_options(sk, dreq, skb))
600 goto drop_and_free;
601
602 if (security_inet_conn_request(sk, skb, req))
603 goto drop_and_free;
604
605 ireq = inet_rsk(req);
606 ireq->loc_addr = ip_hdr(skb)->daddr;
607 ireq->rmt_addr = ip_hdr(skb)->saddr;
608 ireq->opt = NULL;
609
610 /*
611 * Step 3: Process LISTEN state
612 *
613 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
614 *
615 * In fact we defer setting S.GSR, S.SWL, S.SWH to
616 * dccp_create_openreq_child.
617 */
618 dreq->dreq_isr = dcb->dccpd_seq;
619 dreq->dreq_iss = dccp_v4_init_sequence(skb);
620 dreq->dreq_service = service;
621
622 if (dccp_v4_send_response(sk, req, NULL))
623 goto drop_and_free;
624
625 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
626 return 0;
627
628 drop_and_free:
629 reqsk_free(req);
630 drop:
631 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
632 return -1;
633 }
634
635 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
636
637 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
638 {
639 struct dccp_hdr *dh = dccp_hdr(skb);
640
641 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
642 if (dccp_rcv_established(sk, skb, dh, skb->len))
643 goto reset;
644 return 0;
645 }
646
647 /*
648 * Step 3: Process LISTEN state
649 * If P.type == Request or P contains a valid Init Cookie option,
650 * (* Must scan the packet's options to check for Init
651 * Cookies. Only Init Cookies are processed here,
652 * however; other options are processed in Step 8. This
653 * scan need only be performed if the endpoint uses Init
654 * Cookies *)
655 * (* Generate a new socket and switch to that socket *)
656 * Set S := new socket for this port pair
657 * S.state = RESPOND
658 * Choose S.ISS (initial seqno) or set from Init Cookies
659 * Initialize S.GAR := S.ISS
660 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
661 * Continue with S.state == RESPOND
662 * (* A Response packet will be generated in Step 11 *)
663 * Otherwise,
664 * Generate Reset(No Connection) unless P.type == Reset
665 * Drop packet and return
666 *
667 * NOTE: the check for the packet types is done in
668 * dccp_rcv_state_process
669 */
670 if (sk->sk_state == DCCP_LISTEN) {
671 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
672
673 if (nsk == NULL)
674 goto discard;
675
676 if (nsk != sk) {
677 if (dccp_child_process(sk, nsk, skb))
678 goto reset;
679 return 0;
680 }
681 }
682
683 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
684 goto reset;
685 return 0;
686
687 reset:
688 dccp_v4_ctl_send_reset(sk, skb);
689 discard:
690 kfree_skb(skb);
691 return 0;
692 }
693
694 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
695
696 /**
697 * dccp_invalid_packet - check for malformed packets
698 * Implements RFC 4340, 8.5: Step 1: Check header basics
699 * Packets that fail these checks are ignored and do not receive Resets.
700 */
701 int dccp_invalid_packet(struct sk_buff *skb)
702 {
703 const struct dccp_hdr *dh;
704 unsigned int cscov;
705
706 if (skb->pkt_type != PACKET_HOST)
707 return 1;
708
709 /* If the packet is shorter than 12 bytes, drop packet and return */
710 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
711 DCCP_WARN("pskb_may_pull failed\n");
712 return 1;
713 }
714
715 dh = dccp_hdr(skb);
716
717 /* If P.type is not understood, drop packet and return */
718 if (dh->dccph_type >= DCCP_PKT_INVALID) {
719 DCCP_WARN("invalid packet type\n");
720 return 1;
721 }
722
723 /*
724 * If P.Data Offset is too small for packet type, drop packet and return
725 */
726 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
727 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
728 return 1;
729 }
730 /*
731 * If P.Data Offset is too too large for packet, drop packet and return
732 */
733 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
734 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
735 return 1;
736 }
737
738 /*
739 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
740 * has short sequence numbers), drop packet and return
741 */
742 if (dh->dccph_type >= DCCP_PKT_DATA &&
743 dh->dccph_type <= DCCP_PKT_DATAACK && dh->dccph_x == 0) {
744 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
745 dccp_packet_name(dh->dccph_type));
746 return 1;
747 }
748
749 /*
750 * If P.CsCov is too large for the packet size, drop packet and return.
751 * This must come _before_ checksumming (not as RFC 4340 suggests).
752 */
753 cscov = dccp_csum_coverage(skb);
754 if (cscov > skb->len) {
755 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
756 dh->dccph_cscov, skb->len);
757 return 1;
758 }
759
760 /* If header checksum is incorrect, drop packet and return.
761 * (This step is completed in the AF-dependent functions.) */
762 skb->csum = skb_checksum(skb, 0, cscov, 0);
763
764 return 0;
765 }
766
767 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
768
769 /* this is called when real data arrives */
770 static int dccp_v4_rcv(struct sk_buff *skb)
771 {
772 const struct dccp_hdr *dh;
773 const struct iphdr *iph;
774 struct sock *sk;
775 int min_cov;
776
777 /* Step 1: Check header basics */
778
779 if (dccp_invalid_packet(skb))
780 goto discard_it;
781
782 iph = ip_hdr(skb);
783 /* Step 1: If header checksum is incorrect, drop packet and return */
784 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
785 DCCP_WARN("dropped packet with invalid checksum\n");
786 goto discard_it;
787 }
788
789 dh = dccp_hdr(skb);
790
791 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
792 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
793
794 dccp_pr_debug("%8.8s "
795 "src=%u.%u.%u.%u@%-5d "
796 "dst=%u.%u.%u.%u@%-5d seq=%llu",
797 dccp_packet_name(dh->dccph_type),
798 NIPQUAD(iph->saddr), ntohs(dh->dccph_sport),
799 NIPQUAD(iph->daddr), ntohs(dh->dccph_dport),
800 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
801
802 if (dccp_packet_without_ack(skb)) {
803 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
804 dccp_pr_debug_cat("\n");
805 } else {
806 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
807 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
808 DCCP_SKB_CB(skb)->dccpd_ack_seq);
809 }
810
811 /* Step 2:
812 * Look up flow ID in table and get corresponding socket */
813 sk = __inet_lookup(&init_net, &dccp_hashinfo,
814 iph->saddr, dh->dccph_sport,
815 iph->daddr, dh->dccph_dport, inet_iif(skb));
816 /*
817 * Step 2:
818 * If no socket ...
819 */
820 if (sk == NULL) {
821 dccp_pr_debug("failed to look up flow ID in table and "
822 "get corresponding socket\n");
823 goto no_dccp_socket;
824 }
825
826 /*
827 * Step 2:
828 * ... or S.state == TIMEWAIT,
829 * Generate Reset(No Connection) unless P.type == Reset
830 * Drop packet and return
831 */
832 if (sk->sk_state == DCCP_TIME_WAIT) {
833 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
834 inet_twsk_put(inet_twsk(sk));
835 goto no_dccp_socket;
836 }
837
838 /*
839 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
840 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
841 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
842 */
843 min_cov = dccp_sk(sk)->dccps_pcrlen;
844 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
845 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
846 dh->dccph_cscov, min_cov);
847 /* FIXME: "Such packets SHOULD be reported using Data Dropped
848 * options (Section 11.7) with Drop Code 0, Protocol
849 * Constraints." */
850 goto discard_and_relse;
851 }
852
853 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
854 goto discard_and_relse;
855 nf_reset(skb);
856
857 return sk_receive_skb(sk, skb, 1);
858
859 no_dccp_socket:
860 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
861 goto discard_it;
862 /*
863 * Step 2:
864 * If no socket ...
865 * Generate Reset(No Connection) unless P.type == Reset
866 * Drop packet and return
867 */
868 if (dh->dccph_type != DCCP_PKT_RESET) {
869 DCCP_SKB_CB(skb)->dccpd_reset_code =
870 DCCP_RESET_CODE_NO_CONNECTION;
871 dccp_v4_ctl_send_reset(sk, skb);
872 }
873
874 discard_it:
875 kfree_skb(skb);
876 return 0;
877
878 discard_and_relse:
879 sock_put(sk);
880 goto discard_it;
881 }
882
883 static struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
884 .queue_xmit = ip_queue_xmit,
885 .send_check = dccp_v4_send_check,
886 .rebuild_header = inet_sk_rebuild_header,
887 .conn_request = dccp_v4_conn_request,
888 .syn_recv_sock = dccp_v4_request_recv_sock,
889 .net_header_len = sizeof(struct iphdr),
890 .setsockopt = ip_setsockopt,
891 .getsockopt = ip_getsockopt,
892 .addr2sockaddr = inet_csk_addr2sockaddr,
893 .sockaddr_len = sizeof(struct sockaddr_in),
894 .bind_conflict = inet_csk_bind_conflict,
895 #ifdef CONFIG_COMPAT
896 .compat_setsockopt = compat_ip_setsockopt,
897 .compat_getsockopt = compat_ip_getsockopt,
898 #endif
899 };
900
901 static int dccp_v4_init_sock(struct sock *sk)
902 {
903 static __u8 dccp_v4_ctl_sock_initialized;
904 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
905
906 if (err == 0) {
907 if (unlikely(!dccp_v4_ctl_sock_initialized))
908 dccp_v4_ctl_sock_initialized = 1;
909 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
910 }
911
912 return err;
913 }
914
915 static struct timewait_sock_ops dccp_timewait_sock_ops = {
916 .twsk_obj_size = sizeof(struct inet_timewait_sock),
917 };
918
919 DEFINE_PROTO_INUSE(dccp_v4)
920
921 static struct proto dccp_v4_prot = {
922 .name = "DCCP",
923 .owner = THIS_MODULE,
924 .close = dccp_close,
925 .connect = dccp_v4_connect,
926 .disconnect = dccp_disconnect,
927 .ioctl = dccp_ioctl,
928 .init = dccp_v4_init_sock,
929 .setsockopt = dccp_setsockopt,
930 .getsockopt = dccp_getsockopt,
931 .sendmsg = dccp_sendmsg,
932 .recvmsg = dccp_recvmsg,
933 .backlog_rcv = dccp_v4_do_rcv,
934 .hash = inet_hash,
935 .unhash = inet_unhash,
936 .accept = inet_csk_accept,
937 .get_port = inet_csk_get_port,
938 .shutdown = dccp_shutdown,
939 .destroy = dccp_destroy_sock,
940 .orphan_count = &dccp_orphan_count,
941 .max_header = MAX_DCCP_HEADER,
942 .obj_size = sizeof(struct dccp_sock),
943 .rsk_prot = &dccp_request_sock_ops,
944 .twsk_prot = &dccp_timewait_sock_ops,
945 .hashinfo = &dccp_hashinfo,
946 #ifdef CONFIG_COMPAT
947 .compat_setsockopt = compat_dccp_setsockopt,
948 .compat_getsockopt = compat_dccp_getsockopt,
949 #endif
950 REF_PROTO_INUSE(dccp_v4)
951 };
952
953 static struct net_protocol dccp_v4_protocol = {
954 .handler = dccp_v4_rcv,
955 .err_handler = dccp_v4_err,
956 .no_policy = 1,
957 };
958
959 static const struct proto_ops inet_dccp_ops = {
960 .family = PF_INET,
961 .owner = THIS_MODULE,
962 .release = inet_release,
963 .bind = inet_bind,
964 .connect = inet_stream_connect,
965 .socketpair = sock_no_socketpair,
966 .accept = inet_accept,
967 .getname = inet_getname,
968 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
969 .poll = dccp_poll,
970 .ioctl = inet_ioctl,
971 /* FIXME: work on inet_listen to rename it to sock_common_listen */
972 .listen = inet_dccp_listen,
973 .shutdown = inet_shutdown,
974 .setsockopt = sock_common_setsockopt,
975 .getsockopt = sock_common_getsockopt,
976 .sendmsg = inet_sendmsg,
977 .recvmsg = sock_common_recvmsg,
978 .mmap = sock_no_mmap,
979 .sendpage = sock_no_sendpage,
980 #ifdef CONFIG_COMPAT
981 .compat_setsockopt = compat_sock_common_setsockopt,
982 .compat_getsockopt = compat_sock_common_getsockopt,
983 #endif
984 };
985
986 static struct inet_protosw dccp_v4_protosw = {
987 .type = SOCK_DCCP,
988 .protocol = IPPROTO_DCCP,
989 .prot = &dccp_v4_prot,
990 .ops = &inet_dccp_ops,
991 .capability = -1,
992 .no_check = 0,
993 .flags = INET_PROTOSW_ICSK,
994 };
995
996 static int __init dccp_v4_init(void)
997 {
998 int err = proto_register(&dccp_v4_prot, 1);
999
1000 if (err != 0)
1001 goto out;
1002
1003 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1004 if (err != 0)
1005 goto out_proto_unregister;
1006
1007 inet_register_protosw(&dccp_v4_protosw);
1008
1009 err = inet_csk_ctl_sock_create(&dccp_v4_ctl_socket, PF_INET,
1010 SOCK_DCCP, IPPROTO_DCCP);
1011 if (err)
1012 goto out_unregister_protosw;
1013 out:
1014 return err;
1015 out_unregister_protosw:
1016 inet_unregister_protosw(&dccp_v4_protosw);
1017 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1018 out_proto_unregister:
1019 proto_unregister(&dccp_v4_prot);
1020 goto out;
1021 }
1022
1023 static void __exit dccp_v4_exit(void)
1024 {
1025 inet_unregister_protosw(&dccp_v4_protosw);
1026 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1027 proto_unregister(&dccp_v4_prot);
1028 }
1029
1030 module_init(dccp_v4_init);
1031 module_exit(dccp_v4_exit);
1032
1033 /*
1034 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1035 * values directly, Also cover the case where the protocol is not specified,
1036 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1037 */
1038 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1039 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1040 MODULE_LICENSE("GPL");
1041 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1042 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
1043
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