1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/dccp/ipv4.c
4 *
5 * An implementation of the DCCP protocol
6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 */
8
9 #include <linux/dccp.h>
10 #include <linux/icmp.h>
11 #include <linux/slab.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
14 #include <linux/random.h>
15
16 #include <net/icmp.h>
17 #include <net/inet_common.h>
18 #include <net/inet_hashtables.h>
19 #include <net/inet_sock.h>
20 #include <net/protocol.h>
21 #include <net/sock.h>
22 #include <net/timewait_sock.h>
23 #include <net/tcp_states.h>
24 #include <net/xfrm.h>
25 #include <net/secure_seq.h>
26 #include <net/netns/generic.h>
27 #include <net/rstreason.h>
28
29 #include "ackvec.h"
30 #include "ccid.h"
31 #include "dccp.h"
32 #include "feat.h"
33
34 struct dccp_v4_pernet {
35 struct sock *v4_ctl_sk;
36 };
37
38 static unsigned int dccp_v4_pernet_id __read_mostly;
39
40 /*
41 * The per-net v4_ctl_sk socket is used for responding to
42 * the Out-of-the-blue (OOTB) packets. A control sock will be created
43 * for this socket at the initialization time.
44 */
45
46 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
47 {
48 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
49 struct inet_sock *inet = inet_sk(sk);
50 struct dccp_sock *dp = dccp_sk(sk);
51 __be16 orig_sport, orig_dport;
52 __be32 daddr, nexthop;
53 struct flowi4 *fl4;
54 struct rtable *rt;
55 int err;
56 struct ip_options_rcu *inet_opt;
57
58 dp->dccps_role = DCCP_ROLE_CLIENT;
59
60 if (addr_len < sizeof(struct sockaddr_in))
61 return -EINVAL;
62
63 if (usin->sin_family != AF_INET)
64 return -EAFNOSUPPORT;
65
66 nexthop = daddr = usin->sin_addr.s_addr;
67
68 inet_opt = rcu_dereference_protected(inet->inet_opt,
69 lockdep_sock_is_held(sk));
70 if (inet_opt != NULL && inet_opt->opt.srr) {
71 if (daddr == 0)
72 return -EINVAL;
73 nexthop = inet_opt->opt.faddr;
74 }
75
76 orig_sport = inet->inet_sport;
77 orig_dport = usin->sin_port;
78 fl4 = &inet->cork.fl.u.ip4;
79 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
80 sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport,
81 orig_dport, sk);
82 if (IS_ERR(rt))
83 return PTR_ERR(rt);
84
85 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
86 ip_rt_put(rt);
87 return -ENETUNREACH;
88 }
89
90 if (inet_opt == NULL || !inet_opt->opt.srr)
91 daddr = fl4->daddr;
92
93 if (inet->inet_saddr == 0) {
94 err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET);
95 if (err) {
96 ip_rt_put(rt);
97 return err;
98 }
99 } else {
100 sk_rcv_saddr_set(sk, inet->inet_saddr);
101 }
102
103 inet->inet_dport = usin->sin_port;
104 sk_daddr_set(sk, daddr);
105
106 inet_csk(sk)->icsk_ext_hdr_len = 0;
107 if (inet_opt)
108 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
109 /*
110 * Socket identity is still unknown (sport may be zero).
111 * However we set state to DCCP_REQUESTING and not releasing socket
112 * lock select source port, enter ourselves into the hash tables and
113 * complete initialization after this.
114 */
115 dccp_set_state(sk, DCCP_REQUESTING);
116 err = inet_hash_connect(&dccp_death_row, sk);
117 if (err != 0)
118 goto failure;
119
120 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
121 inet->inet_sport, inet->inet_dport, sk);
122 if (IS_ERR(rt)) {
123 err = PTR_ERR(rt);
124 rt = NULL;
125 goto failure;
126 }
127 /* OK, now commit destination to socket. */
128 sk_setup_caps(sk, &rt->dst);
129
130 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
131 inet->inet_daddr,
132 inet->inet_sport,
133 inet->inet_dport);
134 atomic_set(&inet->inet_id, get_random_u16());
135
136 err = dccp_connect(sk);
137 rt = NULL;
138 if (err != 0)
139 goto failure;
140 out:
141 return err;
142 failure:
143 /*
144 * This unhashes the socket and releases the local port, if necessary.
145 */
146 dccp_set_state(sk, DCCP_CLOSED);
147 inet_bhash2_reset_saddr(sk);
148 ip_rt_put(rt);
149 sk->sk_route_caps = 0;
150 inet->inet_dport = 0;
151 goto out;
152 }
153 EXPORT_SYMBOL_GPL(dccp_v4_connect);
154
155 /*
156 * This routine does path mtu discovery as defined in RFC1191.
157 */
158 static inline void dccp_do_pmtu_discovery(struct sock *sk,
159 const struct iphdr *iph,
160 u32 mtu)
161 {
162 struct dst_entry *dst;
163 const struct inet_sock *inet = inet_sk(sk);
164 const struct dccp_sock *dp = dccp_sk(sk);
165
166 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
167 * send out by Linux are always < 576bytes so they should go through
168 * unfragmented).
169 */
170 if (sk->sk_state == DCCP_LISTEN)
171 return;
172
173 dst = inet_csk_update_pmtu(sk, mtu);
174 if (!dst)
175 return;
176
177 /* Something is about to be wrong... Remember soft error
178 * for the case, if this connection will not able to recover.
179 */
180 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
181 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE);
182
183 mtu = dst_mtu(dst);
184
185 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
186 ip_sk_accept_pmtu(sk) &&
187 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
188 dccp_sync_mss(sk, mtu);
189
190 /*
191 * From RFC 4340, sec. 14.1:
192 *
193 * DCCP-Sync packets are the best choice for upward
194 * probing, since DCCP-Sync probes do not risk application
195 * data loss.
196 */
197 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
198 } /* else let the usual retransmit timer handle it */
199 }
200
201 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
202 {
203 struct dst_entry *dst = __sk_dst_check(sk, 0);
204
205 if (dst)
206 dst->ops->redirect(dst, sk, skb);
207 }
208
209 void dccp_req_err(struct sock *sk, u64 seq)
210 {
211 struct request_sock *req = inet_reqsk(sk);
212 struct net *net = sock_net(sk);
213
214 /*
215 * ICMPs are not backlogged, hence we cannot get an established
216 * socket here.
217 */
218 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
219 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
220 } else {
221 /*
222 * Still in RESPOND, just remove it silently.
223 * There is no good way to pass the error to the newly
224 * created socket, and POSIX does not want network
225 * errors returned from accept().
226 */
227 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
228 }
229 reqsk_put(req);
230 }
231 EXPORT_SYMBOL(dccp_req_err);
232
233 /*
234 * This routine is called by the ICMP module when it gets some sort of error
235 * condition. If err < 0 then the socket should be closed and the error
236 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
237 * After adjustment header points to the first 8 bytes of the tcp header. We
238 * need to find the appropriate port.
239 *
240 * The locking strategy used here is very "optimistic". When someone else
241 * accesses the socket the ICMP is just dropped and for some paths there is no
242 * check at all. A more general error queue to queue errors for later handling
243 * is probably better.
244 */
245 static int dccp_v4_err(struct sk_buff *skb, u32 info)
246 {
247 const struct iphdr *iph = (struct iphdr *)skb->data;
248 const u8 offset = iph->ihl << 2;
249 const struct dccp_hdr *dh;
250 struct dccp_sock *dp;
251 const int type = icmp_hdr(skb)->type;
252 const int code = icmp_hdr(skb)->code;
253 struct sock *sk;
254 __u64 seq;
255 int err;
256 struct net *net = dev_net(skb->dev);
257
258 if (!pskb_may_pull(skb, offset + sizeof(*dh)))
259 return -EINVAL;
260 dh = (struct dccp_hdr *)(skb->data + offset);
261 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
262 return -EINVAL;
263 iph = (struct iphdr *)skb->data;
264 dh = (struct dccp_hdr *)(skb->data + offset);
265
266 sk = __inet_lookup_established(net, &dccp_hashinfo,
267 iph->daddr, dh->dccph_dport,
268 iph->saddr, ntohs(dh->dccph_sport),
269 inet_iif(skb), 0);
270 if (!sk) {
271 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
272 return -ENOENT;
273 }
274
275 if (sk->sk_state == DCCP_TIME_WAIT) {
276 inet_twsk_put(inet_twsk(sk));
277 return 0;
278 }
279 seq = dccp_hdr_seq(dh);
280 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
281 dccp_req_err(sk, seq);
282 return 0;
283 }
284
285 bh_lock_sock(sk);
286 /* If too many ICMPs get dropped on busy
287 * servers this needs to be solved differently.
288 */
289 if (sock_owned_by_user(sk))
290 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
291
292 if (sk->sk_state == DCCP_CLOSED)
293 goto out;
294
295 dp = dccp_sk(sk);
296 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
297 !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
298 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
299 goto out;
300 }
301
302 switch (type) {
303 case ICMP_REDIRECT:
304 if (!sock_owned_by_user(sk))
305 dccp_do_redirect(skb, sk);
306 goto out;
307 case ICMP_SOURCE_QUENCH:
308 /* Just silently ignore these. */
309 goto out;
310 case ICMP_PARAMETERPROB:
311 err = EPROTO;
312 break;
313 case ICMP_DEST_UNREACH:
314 if (code > NR_ICMP_UNREACH)
315 goto out;
316
317 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
318 if (!sock_owned_by_user(sk))
319 dccp_do_pmtu_discovery(sk, iph, info);
320 goto out;
321 }
322
323 err = icmp_err_convert[code].errno;
324 break;
325 case ICMP_TIME_EXCEEDED:
326 err = EHOSTUNREACH;
327 break;
328 default:
329 goto out;
330 }
331
332 switch (sk->sk_state) {
333 case DCCP_REQUESTING:
334 case DCCP_RESPOND:
335 if (!sock_owned_by_user(sk)) {
336 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
337 sk->sk_err = err;
338
339 sk_error_report(sk);
340
341 dccp_done(sk);
342 } else {
343 WRITE_ONCE(sk->sk_err_soft, err);
344 }
345 goto out;
346 }
347
348 /* If we've already connected we will keep trying
349 * until we time out, or the user gives up.
350 *
351 * rfc1122 4.2.3.9 allows to consider as hard errors
352 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
353 * but it is obsoleted by pmtu discovery).
354 *
355 * Note, that in modern internet, where routing is unreliable
356 * and in each dark corner broken firewalls sit, sending random
357 * errors ordered by their masters even this two messages finally lose
358 * their original sense (even Linux sends invalid PORT_UNREACHs)
359 *
360 * Now we are in compliance with RFCs.
361 * --ANK (980905)
362 */
363
364 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
365 sk->sk_err = err;
366 sk_error_report(sk);
367 } else { /* Only an error on timeout */
368 WRITE_ONCE(sk->sk_err_soft, err);
369 }
370 out:
371 bh_unlock_sock(sk);
372 sock_put(sk);
373 return 0;
374 }
375
376 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
377 __be32 src, __be32 dst)
378 {
379 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
380 }
381
382 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
383 {
384 const struct inet_sock *inet = inet_sk(sk);
385 struct dccp_hdr *dh = dccp_hdr(skb);
386
387 dccp_csum_outgoing(skb);
388 dh->dccph_checksum = dccp_v4_csum_finish(skb,
389 inet->inet_saddr,
390 inet->inet_daddr);
391 }
392 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
393
394 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
395 {
396 return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
397 ip_hdr(skb)->saddr,
398 dccp_hdr(skb)->dccph_dport,
399 dccp_hdr(skb)->dccph_sport);
400 }
401
402 /*
403 * The three way handshake has completed - we got a valid ACK or DATAACK -
404 * now create the new socket.
405 *
406 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
407 */
408 struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
409 struct sk_buff *skb,
410 struct request_sock *req,
411 struct dst_entry *dst,
412 struct request_sock *req_unhash,
413 bool *own_req)
414 {
415 struct inet_request_sock *ireq;
416 struct inet_sock *newinet;
417 struct sock *newsk;
418
419 if (sk_acceptq_is_full(sk))
420 goto exit_overflow;
421
422 newsk = dccp_create_openreq_child(sk, req, skb);
423 if (newsk == NULL)
424 goto exit_nonewsk;
425
426 newinet = inet_sk(newsk);
427 ireq = inet_rsk(req);
428 sk_daddr_set(newsk, ireq->ir_rmt_addr);
429 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
430 newinet->inet_saddr = ireq->ir_loc_addr;
431 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
432 newinet->mc_index = inet_iif(skb);
433 newinet->mc_ttl = ip_hdr(skb)->ttl;
434 atomic_set(&newinet->inet_id, get_random_u16());
435
436 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
437 goto put_and_exit;
438
439 sk_setup_caps(newsk, dst);
440
441 dccp_sync_mss(newsk, dst_mtu(dst));
442
443 if (__inet_inherit_port(sk, newsk) < 0)
444 goto put_and_exit;
445 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
446 if (*own_req)
447 ireq->ireq_opt = NULL;
448 else
449 newinet->inet_opt = NULL;
450 return newsk;
451
452 exit_overflow:
453 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
454 exit_nonewsk:
455 dst_release(dst);
456 exit:
457 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
458 return NULL;
459 put_and_exit:
460 newinet->inet_opt = NULL;
461 inet_csk_prepare_forced_close(newsk);
462 dccp_done(newsk);
463 goto exit;
464 }
465 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
466
467 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
468 struct sk_buff *skb)
469 {
470 struct rtable *rt;
471 const struct iphdr *iph = ip_hdr(skb);
472 struct flowi4 fl4 = {
473 .flowi4_oif = inet_iif(skb),
474 .daddr = iph->saddr,
475 .saddr = iph->daddr,
476 .flowi4_tos = ip_sock_rt_tos(sk),
477 .flowi4_scope = ip_sock_rt_scope(sk),
478 .flowi4_proto = sk->sk_protocol,
479 .fl4_sport = dccp_hdr(skb)->dccph_dport,
480 .fl4_dport = dccp_hdr(skb)->dccph_sport,
481 };
482
483 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
484 rt = ip_route_output_flow(net, &fl4, sk);
485 if (IS_ERR(rt)) {
486 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
487 return NULL;
488 }
489
490 return &rt->dst;
491 }
492
493 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
494 {
495 int err = -1;
496 struct sk_buff *skb;
497 struct dst_entry *dst;
498 struct flowi4 fl4;
499
500 dst = inet_csk_route_req(sk, &fl4, req);
501 if (dst == NULL)
502 goto out;
503
504 skb = dccp_make_response(sk, dst, req);
505 if (skb != NULL) {
506 const struct inet_request_sock *ireq = inet_rsk(req);
507 struct dccp_hdr *dh = dccp_hdr(skb);
508
509 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
510 ireq->ir_rmt_addr);
511 rcu_read_lock();
512 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
513 ireq->ir_rmt_addr,
514 rcu_dereference(ireq->ireq_opt),
515 READ_ONCE(inet_sk(sk)->tos));
516 rcu_read_unlock();
517 err = net_xmit_eval(err);
518 }
519
520 out:
521 dst_release(dst);
522 return err;
523 }
524
525 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb,
526 enum sk_rst_reason reason)
527 {
528 int err;
529 const struct iphdr *rxiph;
530 struct sk_buff *skb;
531 struct dst_entry *dst;
532 struct net *net = dev_net(skb_dst(rxskb)->dev);
533 struct dccp_v4_pernet *pn;
534 struct sock *ctl_sk;
535
536 /* Never send a reset in response to a reset. */
537 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
538 return;
539
540 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
541 return;
542
543 pn = net_generic(net, dccp_v4_pernet_id);
544 ctl_sk = pn->v4_ctl_sk;
545 dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
546 if (dst == NULL)
547 return;
548
549 skb = dccp_ctl_make_reset(ctl_sk, rxskb);
550 if (skb == NULL)
551 goto out;
552
553 rxiph = ip_hdr(rxskb);
554 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
555 rxiph->daddr);
556 skb_dst_set(skb, dst_clone(dst));
557
558 local_bh_disable();
559 bh_lock_sock(ctl_sk);
560 err = ip_build_and_send_pkt(skb, ctl_sk,
561 rxiph->daddr, rxiph->saddr, NULL,
562 inet_sk(ctl_sk)->tos);
563 bh_unlock_sock(ctl_sk);
564
565 if (net_xmit_eval(err) == 0) {
566 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
567 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
568 }
569 local_bh_enable();
570 out:
571 dst_release(dst);
572 }
573
574 static void dccp_v4_reqsk_destructor(struct request_sock *req)
575 {
576 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
577 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
578 }
579
580 void dccp_syn_ack_timeout(const struct request_sock *req)
581 {
582 }
583 EXPORT_SYMBOL(dccp_syn_ack_timeout);
584
585 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
586 .family = PF_INET,
587 .obj_size = sizeof(struct dccp_request_sock),
588 .rtx_syn_ack = dccp_v4_send_response,
589 .send_ack = dccp_reqsk_send_ack,
590 .destructor = dccp_v4_reqsk_destructor,
591 .send_reset = dccp_v4_ctl_send_reset,
592 .syn_ack_timeout = dccp_syn_ack_timeout,
593 };
594
595 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
596 {
597 struct inet_request_sock *ireq;
598 struct request_sock *req;
599 struct dccp_request_sock *dreq;
600 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
601 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
602
603 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
604 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
605 return 0; /* discard, don't send a reset here */
606
607 if (dccp_bad_service_code(sk, service)) {
608 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
609 goto drop;
610 }
611 /*
612 * TW buckets are converted to open requests without
613 * limitations, they conserve resources and peer is
614 * evidently real one.
615 */
616 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
617 if (inet_csk_reqsk_queue_is_full(sk))
618 goto drop;
619
620 if (sk_acceptq_is_full(sk))
621 goto drop;
622
623 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
624 if (req == NULL)
625 goto drop;
626
627 if (dccp_reqsk_init(req, dccp_sk(sk), skb))
628 goto drop_and_free;
629
630 dreq = dccp_rsk(req);
631 if (dccp_parse_options(sk, dreq, skb))
632 goto drop_and_free;
633
634 ireq = inet_rsk(req);
635 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
636 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
637 ireq->ir_mark = inet_request_mark(sk, skb);
638 ireq->ireq_family = AF_INET;
639 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
640
641 if (security_inet_conn_request(sk, skb, req))
642 goto drop_and_free;
643
644 /*
645 * Step 3: Process LISTEN state
646 *
647 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
648 *
649 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
650 */
651 dreq->dreq_isr = dcb->dccpd_seq;
652 dreq->dreq_gsr = dreq->dreq_isr;
653 dreq->dreq_iss = dccp_v4_init_sequence(skb);
654 dreq->dreq_gss = dreq->dreq_iss;
655 dreq->dreq_service = service;
656
657 if (dccp_v4_send_response(sk, req))
658 goto drop_and_free;
659
660 if (unlikely(!inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT)))
661 reqsk_free(req);
662 else
663 reqsk_put(req);
664
665 return 0;
666
667 drop_and_free:
668 reqsk_free(req);
669 drop:
670 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
671 return -1;
672 }
673 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
674
675 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
676 {
677 struct dccp_hdr *dh = dccp_hdr(skb);
678
679 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
680 if (dccp_rcv_established(sk, skb, dh, skb->len))
681 goto reset;
682 return 0;
683 }
684
685 /*
686 * Step 3: Process LISTEN state
687 * If P.type == Request or P contains a valid Init Cookie option,
688 * (* Must scan the packet's options to check for Init
689 * Cookies. Only Init Cookies are processed here,
690 * however; other options are processed in Step 8. This
691 * scan need only be performed if the endpoint uses Init
692 * Cookies *)
693 * (* Generate a new socket and switch to that socket *)
694 * Set S := new socket for this port pair
695 * S.state = RESPOND
696 * Choose S.ISS (initial seqno) or set from Init Cookies
697 * Initialize S.GAR := S.ISS
698 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
699 * Continue with S.state == RESPOND
700 * (* A Response packet will be generated in Step 11 *)
701 * Otherwise,
702 * Generate Reset(No Connection) unless P.type == Reset
703 * Drop packet and return
704 *
705 * NOTE: the check for the packet types is done in
706 * dccp_rcv_state_process
707 */
708
709 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
710 goto reset;
711 return 0;
712
713 reset:
714 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
715 kfree_skb(skb);
716 return 0;
717 }
718 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
719
720 /**
721 * dccp_invalid_packet - check for malformed packets
722 * @skb: Packet to validate
723 *
724 * Implements RFC 4340, 8.5: Step 1: Check header basics
725 * Packets that fail these checks are ignored and do not receive Resets.
726 */
727 int dccp_invalid_packet(struct sk_buff *skb)
728 {
729 const struct dccp_hdr *dh;
730 unsigned int cscov;
731 u8 dccph_doff;
732
733 if (skb->pkt_type != PACKET_HOST)
734 return 1;
735
736 /* If the packet is shorter than 12 bytes, drop packet and return */
737 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
738 DCCP_WARN("pskb_may_pull failed\n");
739 return 1;
740 }
741
742 dh = dccp_hdr(skb);
743
744 /* If P.type is not understood, drop packet and return */
745 if (dh->dccph_type >= DCCP_PKT_INVALID) {
746 DCCP_WARN("invalid packet type\n");
747 return 1;
748 }
749
750 /*
751 * If P.Data Offset is too small for packet type, drop packet and return
752 */
753 dccph_doff = dh->dccph_doff;
754 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
755 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
756 return 1;
757 }
758 /*
759 * If P.Data Offset is too large for packet, drop packet and return
760 */
761 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
762 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
763 return 1;
764 }
765 dh = dccp_hdr(skb);
766 /*
767 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
768 * has short sequence numbers), drop packet and return
769 */
770 if ((dh->dccph_type < DCCP_PKT_DATA ||
771 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
772 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
773 dccp_packet_name(dh->dccph_type));
774 return 1;
775 }
776
777 /*
778 * If P.CsCov is too large for the packet size, drop packet and return.
779 * This must come _before_ checksumming (not as RFC 4340 suggests).
780 */
781 cscov = dccp_csum_coverage(skb);
782 if (cscov > skb->len) {
783 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
784 dh->dccph_cscov, skb->len);
785 return 1;
786 }
787
788 /* If header checksum is incorrect, drop packet and return.
789 * (This step is completed in the AF-dependent functions.) */
790 skb->csum = skb_checksum(skb, 0, cscov, 0);
791
792 return 0;
793 }
794 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
795
796 /* this is called when real data arrives */
797 static int dccp_v4_rcv(struct sk_buff *skb)
798 {
799 const struct dccp_hdr *dh;
800 const struct iphdr *iph;
801 bool refcounted;
802 struct sock *sk;
803 int min_cov;
804
805 /* Step 1: Check header basics */
806
807 if (dccp_invalid_packet(skb))
808 goto discard_it;
809
810 iph = ip_hdr(skb);
811 /* Step 1: If header checksum is incorrect, drop packet and return */
812 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
813 DCCP_WARN("dropped packet with invalid checksum\n");
814 goto discard_it;
815 }
816
817 dh = dccp_hdr(skb);
818
819 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
820 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
821
822 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
823 dccp_packet_name(dh->dccph_type),
824 &iph->saddr, ntohs(dh->dccph_sport),
825 &iph->daddr, ntohs(dh->dccph_dport),
826 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
827
828 if (dccp_packet_without_ack(skb)) {
829 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
830 dccp_pr_debug_cat("\n");
831 } else {
832 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
833 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
834 DCCP_SKB_CB(skb)->dccpd_ack_seq);
835 }
836
837 lookup:
838 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
839 dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
840 if (!sk) {
841 dccp_pr_debug("failed to look up flow ID in table and "
842 "get corresponding socket\n");
843 goto no_dccp_socket;
844 }
845
846 /*
847 * Step 2:
848 * ... or S.state == TIMEWAIT,
849 * Generate Reset(No Connection) unless P.type == Reset
850 * Drop packet and return
851 */
852 if (sk->sk_state == DCCP_TIME_WAIT) {
853 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
854 inet_twsk_put(inet_twsk(sk));
855 goto no_dccp_socket;
856 }
857
858 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
859 struct request_sock *req = inet_reqsk(sk);
860 struct sock *nsk;
861
862 sk = req->rsk_listener;
863 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
864 inet_csk_reqsk_queue_drop_and_put(sk, req);
865 goto lookup;
866 }
867 sock_hold(sk);
868 refcounted = true;
869 nsk = dccp_check_req(sk, skb, req);
870 if (!nsk) {
871 reqsk_put(req);
872 goto discard_and_relse;
873 }
874 if (nsk == sk) {
875 reqsk_put(req);
876 } else if (dccp_child_process(sk, nsk, skb)) {
877 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
878 goto discard_and_relse;
879 } else {
880 sock_put(sk);
881 return 0;
882 }
883 }
884 /*
885 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
886 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
887 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
888 */
889 min_cov = dccp_sk(sk)->dccps_pcrlen;
890 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
891 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
892 dh->dccph_cscov, min_cov);
893 /* FIXME: "Such packets SHOULD be reported using Data Dropped
894 * options (Section 11.7) with Drop Code 0, Protocol
895 * Constraints." */
896 goto discard_and_relse;
897 }
898
899 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
900 goto discard_and_relse;
901 nf_reset_ct(skb);
902
903 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
904
905 no_dccp_socket:
906 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
907 goto discard_it;
908 /*
909 * Step 2:
910 * If no socket ...
911 * Generate Reset(No Connection) unless P.type == Reset
912 * Drop packet and return
913 */
914 if (dh->dccph_type != DCCP_PKT_RESET) {
915 DCCP_SKB_CB(skb)->dccpd_reset_code =
916 DCCP_RESET_CODE_NO_CONNECTION;
917 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
918 }
919
920 discard_it:
921 kfree_skb(skb);
922 return 0;
923
924 discard_and_relse:
925 if (refcounted)
926 sock_put(sk);
927 goto discard_it;
928 }
929
930 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
931 .queue_xmit = ip_queue_xmit,
932 .send_check = dccp_v4_send_check,
933 .rebuild_header = inet_sk_rebuild_header,
934 .conn_request = dccp_v4_conn_request,
935 .syn_recv_sock = dccp_v4_request_recv_sock,
936 .net_header_len = sizeof(struct iphdr),
937 .setsockopt = ip_setsockopt,
938 .getsockopt = ip_getsockopt,
939 .addr2sockaddr = inet_csk_addr2sockaddr,
940 .sockaddr_len = sizeof(struct sockaddr_in),
941 };
942
943 static int dccp_v4_init_sock(struct sock *sk)
944 {
945 static __u8 dccp_v4_ctl_sock_initialized;
946 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
947
948 if (err == 0) {
949 if (unlikely(!dccp_v4_ctl_sock_initialized))
950 dccp_v4_ctl_sock_initialized = 1;
951 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
952 }
953
954 return err;
955 }
956
957 static struct timewait_sock_ops dccp_timewait_sock_ops = {
958 .twsk_obj_size = sizeof(struct inet_timewait_sock),
959 };
960
961 static struct proto dccp_v4_prot = {
962 .name = "DCCP",
963 .owner = THIS_MODULE,
964 .close = dccp_close,
965 .connect = dccp_v4_connect,
966 .disconnect = dccp_disconnect,
967 .ioctl = dccp_ioctl,
968 .init = dccp_v4_init_sock,
969 .setsockopt = dccp_setsockopt,
970 .getsockopt = dccp_getsockopt,
971 .sendmsg = dccp_sendmsg,
972 .recvmsg = dccp_recvmsg,
973 .backlog_rcv = dccp_v4_do_rcv,
974 .hash = inet_hash,
975 .unhash = inet_unhash,
976 .accept = inet_csk_accept,
977 .get_port = inet_csk_get_port,
978 .shutdown = dccp_shutdown,
979 .destroy = dccp_destroy_sock,
980 .orphan_count = &dccp_orphan_count,
981 .max_header = MAX_DCCP_HEADER,
982 .obj_size = sizeof(struct dccp_sock),
983 .slab_flags = SLAB_TYPESAFE_BY_RCU,
984 .rsk_prot = &dccp_request_sock_ops,
985 .twsk_prot = &dccp_timewait_sock_ops,
986 .h.hashinfo = &dccp_hashinfo,
987 };
988
989 static const struct net_protocol dccp_v4_protocol = {
990 .handler = dccp_v4_rcv,
991 .err_handler = dccp_v4_err,
992 .no_policy = 1,
993 .icmp_strict_tag_validation = 1,
994 };
995
996 static const struct proto_ops inet_dccp_ops = {
997 .family = PF_INET,
998 .owner = THIS_MODULE,
999 .release = inet_release,
1000 .bind = inet_bind,
1001 .connect = inet_stream_connect,
1002 .socketpair = sock_no_socketpair,
1003 .accept = inet_accept,
1004 .getname = inet_getname,
1005 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1006 .poll = dccp_poll,
1007 .ioctl = inet_ioctl,
1008 .gettstamp = sock_gettstamp,
1009 /* FIXME: work on inet_listen to rename it to sock_common_listen */
1010 .listen = inet_dccp_listen,
1011 .shutdown = inet_shutdown,
1012 .setsockopt = sock_common_setsockopt,
1013 .getsockopt = sock_common_getsockopt,
1014 .sendmsg = inet_sendmsg,
1015 .recvmsg = sock_common_recvmsg,
1016 .mmap = sock_no_mmap,
1017 };
1018
1019 static struct inet_protosw dccp_v4_protosw = {
1020 .type = SOCK_DCCP,
1021 .protocol = IPPROTO_DCCP,
1022 .prot = &dccp_v4_prot,
1023 .ops = &inet_dccp_ops,
1024 .flags = INET_PROTOSW_ICSK,
1025 };
1026
1027 static int __net_init dccp_v4_init_net(struct net *net)
1028 {
1029 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1030
1031 if (dccp_hashinfo.bhash == NULL)
1032 return -ESOCKTNOSUPPORT;
1033
1034 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET,
1035 SOCK_DCCP, IPPROTO_DCCP, net);
1036 }
1037
1038 static void __net_exit dccp_v4_exit_net(struct net *net)
1039 {
1040 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1041
1042 inet_ctl_sock_destroy(pn->v4_ctl_sk);
1043 }
1044
1045 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1046 {
1047 inet_twsk_purge(&dccp_hashinfo);
1048 }
1049
1050 static struct pernet_operations dccp_v4_ops = {
1051 .init = dccp_v4_init_net,
1052 .exit = dccp_v4_exit_net,
1053 .exit_batch = dccp_v4_exit_batch,
1054 .id = &dccp_v4_pernet_id,
1055 .size = sizeof(struct dccp_v4_pernet),
1056 };
1057
1058 static int __init dccp_v4_init(void)
1059 {
1060 int err = proto_register(&dccp_v4_prot, 1);
1061
1062 if (err)
1063 goto out;
1064
1065 inet_register_protosw(&dccp_v4_protosw);
1066
1067 err = register_pernet_subsys(&dccp_v4_ops);
1068 if (err)
1069 goto out_destroy_ctl_sock;
1070
1071 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1072 if (err)
1073 goto out_proto_unregister;
1074
1075 out:
1076 return err;
1077 out_proto_unregister:
1078 unregister_pernet_subsys(&dccp_v4_ops);
1079 out_destroy_ctl_sock:
1080 inet_unregister_protosw(&dccp_v4_protosw);
1081 proto_unregister(&dccp_v4_prot);
1082 goto out;
1083 }
1084
1085 static void __exit dccp_v4_exit(void)
1086 {
1087 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1088 unregister_pernet_subsys(&dccp_v4_ops);
1089 inet_unregister_protosw(&dccp_v4_protosw);
1090 proto_unregister(&dccp_v4_prot);
1091 }
1092
1093 module_init(dccp_v4_init);
1094 module_exit(dccp_v4_exit);
1095
1096 /*
1097 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1098 * values directly, Also cover the case where the protocol is not specified,
1099 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1100 */
1101 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1102 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1103 MODULE_LICENSE("GPL");
1104 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1105 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
1106
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