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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
27#include "ackvec.h"
28#include "ccid.h"
29#include "dccp.h"
30#include "feat.h"
31
32/*
33 * The per-net dccp.v4_ctl_sk socket is used for responding to
34 * the Out-of-the-blue (OOTB) packets. A control sock will be created
35 * for this socket at the initialization time.
36 */
37
38int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
39{
40 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
41 struct inet_sock *inet = inet_sk(sk);
42 struct dccp_sock *dp = dccp_sk(sk);
43 __be16 orig_sport, orig_dport;
44 __be32 daddr, nexthop;
45 struct flowi4 *fl4;
46 struct rtable *rt;
47 int err;
48 struct ip_options_rcu *inet_opt;
49
50 dp->dccps_role = DCCP_ROLE_CLIENT;
51
52 if (addr_len < sizeof(struct sockaddr_in))
53 return -EINVAL;
54
55 if (usin->sin_family != AF_INET)
56 return -EAFNOSUPPORT;
57
58 nexthop = daddr = usin->sin_addr.s_addr;
59
60 inet_opt = rcu_dereference_protected(inet->inet_opt,
61 lockdep_sock_is_held(sk));
62 if (inet_opt != NULL && inet_opt->opt.srr) {
63 if (daddr == 0)
64 return -EINVAL;
65 nexthop = inet_opt->opt.faddr;
66 }
67
68 orig_sport = inet->inet_sport;
69 orig_dport = usin->sin_port;
70 fl4 = &inet->cork.fl.u.ip4;
71 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
72 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
73 IPPROTO_DCCP,
74 orig_sport, orig_dport, sk);
75 if (IS_ERR(rt))
76 return PTR_ERR(rt);
77
78 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
79 ip_rt_put(rt);
80 return -ENETUNREACH;
81 }
82
83 if (inet_opt == NULL || !inet_opt->opt.srr)
84 daddr = fl4->daddr;
85
86 if (inet->inet_saddr == 0)
87 inet->inet_saddr = fl4->saddr;
88 sk_rcv_saddr_set(sk, inet->inet_saddr);
89 inet->inet_dport = usin->sin_port;
90 sk_daddr_set(sk, daddr);
91
92 inet_csk(sk)->icsk_ext_hdr_len = 0;
93 if (inet_opt)
94 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
95 /*
96 * Socket identity is still unknown (sport may be zero).
97 * However we set state to DCCP_REQUESTING and not releasing socket
98 * lock select source port, enter ourselves into the hash tables and
99 * complete initialization after this.
100 */
101 dccp_set_state(sk, DCCP_REQUESTING);
102 err = inet_hash_connect(&dccp_death_row, sk);
103 if (err != 0)
104 goto failure;
105
106 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
107 inet->inet_sport, inet->inet_dport, sk);
108 if (IS_ERR(rt)) {
109 err = PTR_ERR(rt);
110 rt = NULL;
111 goto failure;
112 }
113 /* OK, now commit destination to socket. */
114 sk_setup_caps(sk, &rt->dst);
115
116 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
117 inet->inet_daddr,
118 inet->inet_sport,
119 inet->inet_dport);
120 inet->inet_id = prandom_u32();
121
122 err = dccp_connect(sk);
123 rt = NULL;
124 if (err != 0)
125 goto failure;
126out:
127 return err;
128failure:
129 /*
130 * This unhashes the socket and releases the local port, if necessary.
131 */
132 dccp_set_state(sk, DCCP_CLOSED);
133 ip_rt_put(rt);
134 sk->sk_route_caps = 0;
135 inet->inet_dport = 0;
136 goto out;
137}
138EXPORT_SYMBOL_GPL(dccp_v4_connect);
139
140/*
141 * This routine does path mtu discovery as defined in RFC1191.
142 */
143static inline void dccp_do_pmtu_discovery(struct sock *sk,
144 const struct iphdr *iph,
145 u32 mtu)
146{
147 struct dst_entry *dst;
148 const struct inet_sock *inet = inet_sk(sk);
149 const struct dccp_sock *dp = dccp_sk(sk);
150
151 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
152 * send out by Linux are always < 576bytes so they should go through
153 * unfragmented).
154 */
155 if (sk->sk_state == DCCP_LISTEN)
156 return;
157
158 dst = inet_csk_update_pmtu(sk, mtu);
159 if (!dst)
160 return;
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 ip_sk_accept_pmtu(sk) &&
172 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
173 dccp_sync_mss(sk, mtu);
174
175 /*
176 * From RFC 4340, sec. 14.1:
177 *
178 * DCCP-Sync packets are the best choice for upward
179 * probing, since DCCP-Sync probes do not risk application
180 * data loss.
181 */
182 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
183 } /* else let the usual retransmit timer handle it */
184}
185
186static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
187{
188 struct dst_entry *dst = __sk_dst_check(sk, 0);
189
190 if (dst)
191 dst->ops->redirect(dst, sk, skb);
192}
193
194void dccp_req_err(struct sock *sk, u64 seq)
195 {
196 struct request_sock *req = inet_reqsk(sk);
197 struct net *net = sock_net(sk);
198
199 /*
200 * ICMPs are not backlogged, hence we cannot get an established
201 * socket here.
202 */
203 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
204 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
205 } else {
206 /*
207 * Still in RESPOND, just remove it silently.
208 * There is no good way to pass the error to the newly
209 * created socket, and POSIX does not want network
210 * errors returned from accept().
211 */
212 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
213 }
214 reqsk_put(req);
215}
216EXPORT_SYMBOL(dccp_req_err);
217
218/*
219 * This routine is called by the ICMP module when it gets some sort of error
220 * condition. If err < 0 then the socket should be closed and the error
221 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
222 * After adjustment header points to the first 8 bytes of the tcp header. We
223 * need to find the appropriate port.
224 *
225 * The locking strategy used here is very "optimistic". When someone else
226 * accesses the socket the ICMP is just dropped and for some paths there is no
227 * check at all. A more general error queue to queue errors for later handling
228 * is probably better.
229 */
230static int dccp_v4_err(struct sk_buff *skb, u32 info)
231{
232 const struct iphdr *iph = (struct iphdr *)skb->data;
233 const u8 offset = iph->ihl << 2;
234 const struct dccp_hdr *dh;
235 struct dccp_sock *dp;
236 struct inet_sock *inet;
237 const int type = icmp_hdr(skb)->type;
238 const int code = icmp_hdr(skb)->code;
239 struct sock *sk;
240 __u64 seq;
241 int err;
242 struct net *net = dev_net(skb->dev);
243
244 /* Only need dccph_dport & dccph_sport which are the first
245 * 4 bytes in dccp header.
246 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
247 */
248 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
249 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
250 dh = (struct dccp_hdr *)(skb->data + offset);
251
252 sk = __inet_lookup_established(net, &dccp_hashinfo,
253 iph->daddr, dh->dccph_dport,
254 iph->saddr, ntohs(dh->dccph_sport),
255 inet_iif(skb), 0);
256 if (!sk) {
257 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
258 return -ENOENT;
259 }
260
261 if (sk->sk_state == DCCP_TIME_WAIT) {
262 inet_twsk_put(inet_twsk(sk));
263 return 0;
264 }
265 seq = dccp_hdr_seq(dh);
266 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
267 dccp_req_err(sk, seq);
268 return 0;
269 }
270
271 bh_lock_sock(sk);
272 /* If too many ICMPs get dropped on busy
273 * servers this needs to be solved differently.
274 */
275 if (sock_owned_by_user(sk))
276 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
277
278 if (sk->sk_state == DCCP_CLOSED)
279 goto out;
280
281 dp = dccp_sk(sk);
282 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
283 !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
284 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
285 goto out;
286 }
287
288 switch (type) {
289 case ICMP_REDIRECT:
290 if (!sock_owned_by_user(sk))
291 dccp_do_redirect(skb, sk);
292 goto out;
293 case ICMP_SOURCE_QUENCH:
294 /* Just silently ignore these. */
295 goto out;
296 case ICMP_PARAMETERPROB:
297 err = EPROTO;
298 break;
299 case ICMP_DEST_UNREACH:
300 if (code > NR_ICMP_UNREACH)
301 goto out;
302
303 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
304 if (!sock_owned_by_user(sk))
305 dccp_do_pmtu_discovery(sk, iph, info);
306 goto out;
307 }
308
309 err = icmp_err_convert[code].errno;
310 break;
311 case ICMP_TIME_EXCEEDED:
312 err = EHOSTUNREACH;
313 break;
314 default:
315 goto out;
316 }
317
318 switch (sk->sk_state) {
319 case DCCP_REQUESTING:
320 case DCCP_RESPOND:
321 if (!sock_owned_by_user(sk)) {
322 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
323 sk->sk_err = err;
324
325 sk->sk_error_report(sk);
326
327 dccp_done(sk);
328 } else
329 sk->sk_err_soft = err;
330 goto out;
331 }
332
333 /* If we've already connected we will keep trying
334 * until we time out, or the user gives up.
335 *
336 * rfc1122 4.2.3.9 allows to consider as hard errors
337 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
338 * but it is obsoleted by pmtu discovery).
339 *
340 * Note, that in modern internet, where routing is unreliable
341 * and in each dark corner broken firewalls sit, sending random
342 * errors ordered by their masters even this two messages finally lose
343 * their original sense (even Linux sends invalid PORT_UNREACHs)
344 *
345 * Now we are in compliance with RFCs.
346 * --ANK (980905)
347 */
348
349 inet = inet_sk(sk);
350 if (!sock_owned_by_user(sk) && inet->recverr) {
351 sk->sk_err = err;
352 sk->sk_error_report(sk);
353 } else /* Only an error on timeout */
354 sk->sk_err_soft = err;
355out:
356 bh_unlock_sock(sk);
357 sock_put(sk);
358 return 0;
359}
360
361static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
362 __be32 src, __be32 dst)
363{
364 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
365}
366
367void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
368{
369 const struct inet_sock *inet = inet_sk(sk);
370 struct dccp_hdr *dh = dccp_hdr(skb);
371
372 dccp_csum_outgoing(skb);
373 dh->dccph_checksum = dccp_v4_csum_finish(skb,
374 inet->inet_saddr,
375 inet->inet_daddr);
376}
377EXPORT_SYMBOL_GPL(dccp_v4_send_check);
378
379static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
380{
381 return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
382 ip_hdr(skb)->saddr,
383 dccp_hdr(skb)->dccph_dport,
384 dccp_hdr(skb)->dccph_sport);
385}
386
387/*
388 * The three way handshake has completed - we got a valid ACK or DATAACK -
389 * now create the new socket.
390 *
391 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
392 */
393struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
394 struct sk_buff *skb,
395 struct request_sock *req,
396 struct dst_entry *dst,
397 struct request_sock *req_unhash,
398 bool *own_req)
399{
400 struct inet_request_sock *ireq;
401 struct inet_sock *newinet;
402 struct sock *newsk;
403
404 if (sk_acceptq_is_full(sk))
405 goto exit_overflow;
406
407 newsk = dccp_create_openreq_child(sk, req, skb);
408 if (newsk == NULL)
409 goto exit_nonewsk;
410
411 newinet = inet_sk(newsk);
412 ireq = inet_rsk(req);
413 sk_daddr_set(newsk, ireq->ir_rmt_addr);
414 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
415 newinet->inet_saddr = ireq->ir_loc_addr;
416 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
417 newinet->mc_index = inet_iif(skb);
418 newinet->mc_ttl = ip_hdr(skb)->ttl;
419 newinet->inet_id = prandom_u32();
420
421 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
422 goto put_and_exit;
423
424 sk_setup_caps(newsk, dst);
425
426 dccp_sync_mss(newsk, dst_mtu(dst));
427
428 if (__inet_inherit_port(sk, newsk) < 0)
429 goto put_and_exit;
430 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
431 if (*own_req)
432 ireq->ireq_opt = NULL;
433 else
434 newinet->inet_opt = NULL;
435 return newsk;
436
437exit_overflow:
438 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
439exit_nonewsk:
440 dst_release(dst);
441exit:
442 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
443 return NULL;
444put_and_exit:
445 newinet->inet_opt = NULL;
446 inet_csk_prepare_forced_close(newsk);
447 dccp_done(newsk);
448 goto exit;
449}
450EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
451
452static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
453 struct sk_buff *skb)
454{
455 struct rtable *rt;
456 const struct iphdr *iph = ip_hdr(skb);
457 struct flowi4 fl4 = {
458 .flowi4_oif = inet_iif(skb),
459 .daddr = iph->saddr,
460 .saddr = iph->daddr,
461 .flowi4_tos = RT_CONN_FLAGS(sk),
462 .flowi4_proto = sk->sk_protocol,
463 .fl4_sport = dccp_hdr(skb)->dccph_dport,
464 .fl4_dport = dccp_hdr(skb)->dccph_sport,
465 };
466
467 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
468 rt = ip_route_output_flow(net, &fl4, sk);
469 if (IS_ERR(rt)) {
470 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
471 return NULL;
472 }
473
474 return &rt->dst;
475}
476
477static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
478{
479 int err = -1;
480 struct sk_buff *skb;
481 struct dst_entry *dst;
482 struct flowi4 fl4;
483
484 dst = inet_csk_route_req(sk, &fl4, req);
485 if (dst == NULL)
486 goto out;
487
488 skb = dccp_make_response(sk, dst, req);
489 if (skb != NULL) {
490 const struct inet_request_sock *ireq = inet_rsk(req);
491 struct dccp_hdr *dh = dccp_hdr(skb);
492
493 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
494 ireq->ir_rmt_addr);
495 rcu_read_lock();
496 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
497 ireq->ir_rmt_addr,
498 rcu_dereference(ireq->ireq_opt));
499 rcu_read_unlock();
500 err = net_xmit_eval(err);
501 }
502
503out:
504 dst_release(dst);
505 return err;
506}
507
508static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
509{
510 int err;
511 const struct iphdr *rxiph;
512 struct sk_buff *skb;
513 struct dst_entry *dst;
514 struct net *net = dev_net(skb_dst(rxskb)->dev);
515 struct sock *ctl_sk = net->dccp.v4_ctl_sk;
516
517 /* Never send a reset in response to a reset. */
518 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
519 return;
520
521 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
522 return;
523
524 dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
525 if (dst == NULL)
526 return;
527
528 skb = dccp_ctl_make_reset(ctl_sk, rxskb);
529 if (skb == NULL)
530 goto out;
531
532 rxiph = ip_hdr(rxskb);
533 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
534 rxiph->daddr);
535 skb_dst_set(skb, dst_clone(dst));
536
537 local_bh_disable();
538 bh_lock_sock(ctl_sk);
539 err = ip_build_and_send_pkt(skb, ctl_sk,
540 rxiph->daddr, rxiph->saddr, NULL);
541 bh_unlock_sock(ctl_sk);
542
543 if (net_xmit_eval(err) == 0) {
544 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
545 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
546 }
547 local_bh_enable();
548out:
549 dst_release(dst);
550}
551
552static void dccp_v4_reqsk_destructor(struct request_sock *req)
553{
554 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
555 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
556}
557
558void dccp_syn_ack_timeout(const struct request_sock *req)
559{
560}
561EXPORT_SYMBOL(dccp_syn_ack_timeout);
562
563static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
564 .family = PF_INET,
565 .obj_size = sizeof(struct dccp_request_sock),
566 .rtx_syn_ack = dccp_v4_send_response,
567 .send_ack = dccp_reqsk_send_ack,
568 .destructor = dccp_v4_reqsk_destructor,
569 .send_reset = dccp_v4_ctl_send_reset,
570 .syn_ack_timeout = dccp_syn_ack_timeout,
571};
572
573int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
574{
575 struct inet_request_sock *ireq;
576 struct request_sock *req;
577 struct dccp_request_sock *dreq;
578 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
579 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
580
581 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
582 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
583 return 0; /* discard, don't send a reset here */
584
585 if (dccp_bad_service_code(sk, service)) {
586 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
587 goto drop;
588 }
589 /*
590 * TW buckets are converted to open requests without
591 * limitations, they conserve resources and peer is
592 * evidently real one.
593 */
594 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
595 if (inet_csk_reqsk_queue_is_full(sk))
596 goto drop;
597
598 if (sk_acceptq_is_full(sk))
599 goto drop;
600
601 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
602 if (req == NULL)
603 goto drop;
604
605 if (dccp_reqsk_init(req, dccp_sk(sk), skb))
606 goto drop_and_free;
607
608 dreq = dccp_rsk(req);
609 if (dccp_parse_options(sk, dreq, skb))
610 goto drop_and_free;
611
612 if (security_inet_conn_request(sk, skb, req))
613 goto drop_and_free;
614
615 ireq = inet_rsk(req);
616 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
617 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
618 ireq->ir_mark = inet_request_mark(sk, skb);
619 ireq->ireq_family = AF_INET;
620 ireq->ir_iif = sk->sk_bound_dev_if;
621
622 /*
623 * Step 3: Process LISTEN state
624 *
625 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
626 *
627 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
628 */
629 dreq->dreq_isr = dcb->dccpd_seq;
630 dreq->dreq_gsr = dreq->dreq_isr;
631 dreq->dreq_iss = dccp_v4_init_sequence(skb);
632 dreq->dreq_gss = dreq->dreq_iss;
633 dreq->dreq_service = service;
634
635 if (dccp_v4_send_response(sk, req))
636 goto drop_and_free;
637
638 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
639 reqsk_put(req);
640 return 0;
641
642drop_and_free:
643 reqsk_free(req);
644drop:
645 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
646 return -1;
647}
648EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
649
650int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
651{
652 struct dccp_hdr *dh = dccp_hdr(skb);
653
654 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
655 if (dccp_rcv_established(sk, skb, dh, skb->len))
656 goto reset;
657 return 0;
658 }
659
660 /*
661 * Step 3: Process LISTEN state
662 * If P.type == Request or P contains a valid Init Cookie option,
663 * (* Must scan the packet's options to check for Init
664 * Cookies. Only Init Cookies are processed here,
665 * however; other options are processed in Step 8. This
666 * scan need only be performed if the endpoint uses Init
667 * Cookies *)
668 * (* Generate a new socket and switch to that socket *)
669 * Set S := new socket for this port pair
670 * S.state = RESPOND
671 * Choose S.ISS (initial seqno) or set from Init Cookies
672 * Initialize S.GAR := S.ISS
673 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
674 * Continue with S.state == RESPOND
675 * (* A Response packet will be generated in Step 11 *)
676 * Otherwise,
677 * Generate Reset(No Connection) unless P.type == Reset
678 * Drop packet and return
679 *
680 * NOTE: the check for the packet types is done in
681 * dccp_rcv_state_process
682 */
683
684 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
685 goto reset;
686 return 0;
687
688reset:
689 dccp_v4_ctl_send_reset(sk, skb);
690 kfree_skb(skb);
691 return 0;
692}
693EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
694
695/**
696 * dccp_invalid_packet - check for malformed packets
697 * @skb: Packet to validate
698 *
699 * Implements RFC 4340, 8.5: Step 1: Check header basics
700 * Packets that fail these checks are ignored and do not receive Resets.
701 */
702int dccp_invalid_packet(struct sk_buff *skb)
703{
704 const struct dccp_hdr *dh;
705 unsigned int cscov;
706 u8 dccph_doff;
707
708 if (skb->pkt_type != PACKET_HOST)
709 return 1;
710
711 /* If the packet is shorter than 12 bytes, drop packet and return */
712 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
713 DCCP_WARN("pskb_may_pull failed\n");
714 return 1;
715 }
716
717 dh = dccp_hdr(skb);
718
719 /* If P.type is not understood, drop packet and return */
720 if (dh->dccph_type >= DCCP_PKT_INVALID) {
721 DCCP_WARN("invalid packet type\n");
722 return 1;
723 }
724
725 /*
726 * If P.Data Offset is too small for packet type, drop packet and return
727 */
728 dccph_doff = dh->dccph_doff;
729 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
730 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
731 return 1;
732 }
733 /*
734 * If P.Data Offset is too too large for packet, drop packet and return
735 */
736 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
737 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
738 return 1;
739 }
740 dh = dccp_hdr(skb);
741 /*
742 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
743 * has short sequence numbers), drop packet and return
744 */
745 if ((dh->dccph_type < DCCP_PKT_DATA ||
746 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
747 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
748 dccp_packet_name(dh->dccph_type));
749 return 1;
750 }
751
752 /*
753 * If P.CsCov is too large for the packet size, drop packet and return.
754 * This must come _before_ checksumming (not as RFC 4340 suggests).
755 */
756 cscov = dccp_csum_coverage(skb);
757 if (cscov > skb->len) {
758 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
759 dh->dccph_cscov, skb->len);
760 return 1;
761 }
762
763 /* If header checksum is incorrect, drop packet and return.
764 * (This step is completed in the AF-dependent functions.) */
765 skb->csum = skb_checksum(skb, 0, cscov, 0);
766
767 return 0;
768}
769EXPORT_SYMBOL_GPL(dccp_invalid_packet);
770
771/* this is called when real data arrives */
772static int dccp_v4_rcv(struct sk_buff *skb)
773{
774 const struct dccp_hdr *dh;
775 const struct iphdr *iph;
776 bool refcounted;
777 struct sock *sk;
778 int min_cov;
779
780 /* Step 1: Check header basics */
781
782 if (dccp_invalid_packet(skb))
783 goto discard_it;
784
785 iph = ip_hdr(skb);
786 /* Step 1: If header checksum is incorrect, drop packet and return */
787 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
788 DCCP_WARN("dropped packet with invalid checksum\n");
789 goto discard_it;
790 }
791
792 dh = dccp_hdr(skb);
793
794 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
795 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
796
797 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
798 dccp_packet_name(dh->dccph_type),
799 &iph->saddr, ntohs(dh->dccph_sport),
800 &iph->daddr, ntohs(dh->dccph_dport),
801 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
802
803 if (dccp_packet_without_ack(skb)) {
804 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
805 dccp_pr_debug_cat("\n");
806 } else {
807 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
808 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
809 DCCP_SKB_CB(skb)->dccpd_ack_seq);
810 }
811
812lookup:
813 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
814 dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
815 if (!sk) {
816 dccp_pr_debug("failed to look up flow ID in table and "
817 "get corresponding socket\n");
818 goto no_dccp_socket;
819 }
820
821 /*
822 * Step 2:
823 * ... or S.state == TIMEWAIT,
824 * Generate Reset(No Connection) unless P.type == Reset
825 * Drop packet and return
826 */
827 if (sk->sk_state == DCCP_TIME_WAIT) {
828 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
829 inet_twsk_put(inet_twsk(sk));
830 goto no_dccp_socket;
831 }
832
833 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
834 struct request_sock *req = inet_reqsk(sk);
835 struct sock *nsk;
836
837 sk = req->rsk_listener;
838 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
839 inet_csk_reqsk_queue_drop_and_put(sk, req);
840 goto lookup;
841 }
842 sock_hold(sk);
843 refcounted = true;
844 nsk = dccp_check_req(sk, skb, req);
845 if (!nsk) {
846 reqsk_put(req);
847 goto discard_and_relse;
848 }
849 if (nsk == sk) {
850 reqsk_put(req);
851 } else if (dccp_child_process(sk, nsk, skb)) {
852 dccp_v4_ctl_send_reset(sk, skb);
853 goto discard_and_relse;
854 } else {
855 sock_put(sk);
856 return 0;
857 }
858 }
859 /*
860 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
861 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
862 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
863 */
864 min_cov = dccp_sk(sk)->dccps_pcrlen;
865 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
866 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
867 dh->dccph_cscov, min_cov);
868 /* FIXME: "Such packets SHOULD be reported using Data Dropped
869 * options (Section 11.7) with Drop Code 0, Protocol
870 * Constraints." */
871 goto discard_and_relse;
872 }
873
874 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
875 goto discard_and_relse;
876 nf_reset_ct(skb);
877
878 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
879
880no_dccp_socket:
881 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
882 goto discard_it;
883 /*
884 * Step 2:
885 * If no socket ...
886 * Generate Reset(No Connection) unless P.type == Reset
887 * Drop packet and return
888 */
889 if (dh->dccph_type != DCCP_PKT_RESET) {
890 DCCP_SKB_CB(skb)->dccpd_reset_code =
891 DCCP_RESET_CODE_NO_CONNECTION;
892 dccp_v4_ctl_send_reset(sk, skb);
893 }
894
895discard_it:
896 kfree_skb(skb);
897 return 0;
898
899discard_and_relse:
900 if (refcounted)
901 sock_put(sk);
902 goto discard_it;
903}
904
905static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
906 .queue_xmit = ip_queue_xmit,
907 .send_check = dccp_v4_send_check,
908 .rebuild_header = inet_sk_rebuild_header,
909 .conn_request = dccp_v4_conn_request,
910 .syn_recv_sock = dccp_v4_request_recv_sock,
911 .net_header_len = sizeof(struct iphdr),
912 .setsockopt = ip_setsockopt,
913 .getsockopt = ip_getsockopt,
914 .addr2sockaddr = inet_csk_addr2sockaddr,
915 .sockaddr_len = sizeof(struct sockaddr_in),
916};
917
918static int dccp_v4_init_sock(struct sock *sk)
919{
920 static __u8 dccp_v4_ctl_sock_initialized;
921 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
922
923 if (err == 0) {
924 if (unlikely(!dccp_v4_ctl_sock_initialized))
925 dccp_v4_ctl_sock_initialized = 1;
926 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
927 }
928
929 return err;
930}
931
932static struct timewait_sock_ops dccp_timewait_sock_ops = {
933 .twsk_obj_size = sizeof(struct inet_timewait_sock),
934};
935
936static struct proto dccp_v4_prot = {
937 .name = "DCCP",
938 .owner = THIS_MODULE,
939 .close = dccp_close,
940 .connect = dccp_v4_connect,
941 .disconnect = dccp_disconnect,
942 .ioctl = dccp_ioctl,
943 .init = dccp_v4_init_sock,
944 .setsockopt = dccp_setsockopt,
945 .getsockopt = dccp_getsockopt,
946 .sendmsg = dccp_sendmsg,
947 .recvmsg = dccp_recvmsg,
948 .backlog_rcv = dccp_v4_do_rcv,
949 .hash = inet_hash,
950 .unhash = inet_unhash,
951 .accept = inet_csk_accept,
952 .get_port = inet_csk_get_port,
953 .shutdown = dccp_shutdown,
954 .destroy = dccp_destroy_sock,
955 .orphan_count = &dccp_orphan_count,
956 .max_header = MAX_DCCP_HEADER,
957 .obj_size = sizeof(struct dccp_sock),
958 .slab_flags = SLAB_TYPESAFE_BY_RCU,
959 .rsk_prot = &dccp_request_sock_ops,
960 .twsk_prot = &dccp_timewait_sock_ops,
961 .h.hashinfo = &dccp_hashinfo,
962};
963
964static const struct net_protocol dccp_v4_protocol = {
965 .handler = dccp_v4_rcv,
966 .err_handler = dccp_v4_err,
967 .no_policy = 1,
968 .netns_ok = 1,
969 .icmp_strict_tag_validation = 1,
970};
971
972static const struct proto_ops inet_dccp_ops = {
973 .family = PF_INET,
974 .owner = THIS_MODULE,
975 .release = inet_release,
976 .bind = inet_bind,
977 .connect = inet_stream_connect,
978 .socketpair = sock_no_socketpair,
979 .accept = inet_accept,
980 .getname = inet_getname,
981 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
982 .poll = dccp_poll,
983 .ioctl = inet_ioctl,
984 .gettstamp = sock_gettstamp,
985 /* FIXME: work on inet_listen to rename it to sock_common_listen */
986 .listen = inet_dccp_listen,
987 .shutdown = inet_shutdown,
988 .setsockopt = sock_common_setsockopt,
989 .getsockopt = sock_common_getsockopt,
990 .sendmsg = inet_sendmsg,
991 .recvmsg = sock_common_recvmsg,
992 .mmap = sock_no_mmap,
993 .sendpage = sock_no_sendpage,
994};
995
996static struct inet_protosw dccp_v4_protosw = {
997 .type = SOCK_DCCP,
998 .protocol = IPPROTO_DCCP,
999 .prot = &dccp_v4_prot,
1000 .ops = &inet_dccp_ops,
1001 .flags = INET_PROTOSW_ICSK,
1002};
1003
1004static int __net_init dccp_v4_init_net(struct net *net)
1005{
1006 if (dccp_hashinfo.bhash == NULL)
1007 return -ESOCKTNOSUPPORT;
1008
1009 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1010 SOCK_DCCP, IPPROTO_DCCP, net);
1011}
1012
1013static void __net_exit dccp_v4_exit_net(struct net *net)
1014{
1015 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1016}
1017
1018static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1019{
1020 inet_twsk_purge(&dccp_hashinfo, AF_INET);
1021}
1022
1023static struct pernet_operations dccp_v4_ops = {
1024 .init = dccp_v4_init_net,
1025 .exit = dccp_v4_exit_net,
1026 .exit_batch = dccp_v4_exit_batch,
1027};
1028
1029static int __init dccp_v4_init(void)
1030{
1031 int err = proto_register(&dccp_v4_prot, 1);
1032
1033 if (err)
1034 goto out;
1035
1036 inet_register_protosw(&dccp_v4_protosw);
1037
1038 err = register_pernet_subsys(&dccp_v4_ops);
1039 if (err)
1040 goto out_destroy_ctl_sock;
1041
1042 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1043 if (err)
1044 goto out_proto_unregister;
1045
1046out:
1047 return err;
1048out_proto_unregister:
1049 unregister_pernet_subsys(&dccp_v4_ops);
1050out_destroy_ctl_sock:
1051 inet_unregister_protosw(&dccp_v4_protosw);
1052 proto_unregister(&dccp_v4_prot);
1053 goto out;
1054}
1055
1056static void __exit dccp_v4_exit(void)
1057{
1058 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1059 unregister_pernet_subsys(&dccp_v4_ops);
1060 inet_unregister_protosw(&dccp_v4_protosw);
1061 proto_unregister(&dccp_v4_prot);
1062}
1063
1064module_init(dccp_v4_init);
1065module_exit(dccp_v4_exit);
1066
1067/*
1068 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1069 * values directly, Also cover the case where the protocol is not specified,
1070 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1071 */
1072MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1073MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1074MODULE_LICENSE("GPL");
1075MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1076MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
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
28#include "ackvec.h"
29#include "ccid.h"
30#include "dccp.h"
31#include "feat.h"
32
33struct dccp_v4_pernet {
34 struct sock *v4_ctl_sk;
35};
36
37static unsigned int dccp_v4_pernet_id __read_mostly;
38
39/*
40 * The per-net v4_ctl_sk socket is used for responding to
41 * the Out-of-the-blue (OOTB) packets. A control sock will be created
42 * for this socket at the initialization time.
43 */
44
45int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
46{
47 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
48 struct inet_sock *inet = inet_sk(sk);
49 struct dccp_sock *dp = dccp_sk(sk);
50 __be16 orig_sport, orig_dport;
51 __be32 daddr, nexthop;
52 struct flowi4 *fl4;
53 struct rtable *rt;
54 int err;
55 struct ip_options_rcu *inet_opt;
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
67 inet_opt = rcu_dereference_protected(inet->inet_opt,
68 lockdep_sock_is_held(sk));
69 if (inet_opt != NULL && inet_opt->opt.srr) {
70 if (daddr == 0)
71 return -EINVAL;
72 nexthop = inet_opt->opt.faddr;
73 }
74
75 orig_sport = inet->inet_sport;
76 orig_dport = usin->sin_port;
77 fl4 = &inet->cork.fl.u.ip4;
78 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
79 sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport,
80 orig_dport, sk);
81 if (IS_ERR(rt))
82 return PTR_ERR(rt);
83
84 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
85 ip_rt_put(rt);
86 return -ENETUNREACH;
87 }
88
89 if (inet_opt == NULL || !inet_opt->opt.srr)
90 daddr = fl4->daddr;
91
92 if (inet->inet_saddr == 0) {
93 err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET);
94 if (err) {
95 ip_rt_put(rt);
96 return err;
97 }
98 } else {
99 sk_rcv_saddr_set(sk, inet->inet_saddr);
100 }
101
102 inet->inet_dport = usin->sin_port;
103 sk_daddr_set(sk, daddr);
104
105 inet_csk(sk)->icsk_ext_hdr_len = 0;
106 if (inet_opt)
107 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
108 /*
109 * Socket identity is still unknown (sport may be zero).
110 * However we set state to DCCP_REQUESTING and not releasing socket
111 * lock select source port, enter ourselves into the hash tables and
112 * complete initialization after this.
113 */
114 dccp_set_state(sk, DCCP_REQUESTING);
115 err = inet_hash_connect(&dccp_death_row, sk);
116 if (err != 0)
117 goto failure;
118
119 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
120 inet->inet_sport, inet->inet_dport, sk);
121 if (IS_ERR(rt)) {
122 err = PTR_ERR(rt);
123 rt = NULL;
124 goto failure;
125 }
126 /* OK, now commit destination to socket. */
127 sk_setup_caps(sk, &rt->dst);
128
129 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
130 inet->inet_daddr,
131 inet->inet_sport,
132 inet->inet_dport);
133 atomic_set(&inet->inet_id, get_random_u16());
134
135 err = dccp_connect(sk);
136 rt = NULL;
137 if (err != 0)
138 goto failure;
139out:
140 return err;
141failure:
142 /*
143 * This unhashes the socket and releases the local port, if necessary.
144 */
145 dccp_set_state(sk, DCCP_CLOSED);
146 inet_bhash2_reset_saddr(sk);
147 ip_rt_put(rt);
148 sk->sk_route_caps = 0;
149 inet->inet_dport = 0;
150 goto out;
151}
152EXPORT_SYMBOL_GPL(dccp_v4_connect);
153
154/*
155 * This routine does path mtu discovery as defined in RFC1191.
156 */
157static inline void dccp_do_pmtu_discovery(struct sock *sk,
158 const struct iphdr *iph,
159 u32 mtu)
160{
161 struct dst_entry *dst;
162 const struct inet_sock *inet = inet_sk(sk);
163 const struct dccp_sock *dp = dccp_sk(sk);
164
165 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
166 * send out by Linux are always < 576bytes so they should go through
167 * unfragmented).
168 */
169 if (sk->sk_state == DCCP_LISTEN)
170 return;
171
172 dst = inet_csk_update_pmtu(sk, mtu);
173 if (!dst)
174 return;
175
176 /* Something is about to be wrong... Remember soft error
177 * for the case, if this connection will not able to recover.
178 */
179 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
180 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE);
181
182 mtu = dst_mtu(dst);
183
184 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
185 ip_sk_accept_pmtu(sk) &&
186 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
187 dccp_sync_mss(sk, mtu);
188
189 /*
190 * From RFC 4340, sec. 14.1:
191 *
192 * DCCP-Sync packets are the best choice for upward
193 * probing, since DCCP-Sync probes do not risk application
194 * data loss.
195 */
196 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
197 } /* else let the usual retransmit timer handle it */
198}
199
200static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
201{
202 struct dst_entry *dst = __sk_dst_check(sk, 0);
203
204 if (dst)
205 dst->ops->redirect(dst, sk, skb);
206}
207
208void dccp_req_err(struct sock *sk, u64 seq)
209 {
210 struct request_sock *req = inet_reqsk(sk);
211 struct net *net = sock_net(sk);
212
213 /*
214 * ICMPs are not backlogged, hence we cannot get an established
215 * socket here.
216 */
217 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) {
218 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
219 } else {
220 /*
221 * Still in RESPOND, just remove it silently.
222 * There is no good way to pass the error to the newly
223 * created socket, and POSIX does not want network
224 * errors returned from accept().
225 */
226 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
227 }
228 reqsk_put(req);
229}
230EXPORT_SYMBOL(dccp_req_err);
231
232/*
233 * This routine is called by the ICMP module when it gets some sort of error
234 * condition. If err < 0 then the socket should be closed and the error
235 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
236 * After adjustment header points to the first 8 bytes of the tcp header. We
237 * need to find the appropriate port.
238 *
239 * The locking strategy used here is very "optimistic". When someone else
240 * accesses the socket the ICMP is just dropped and for some paths there is no
241 * check at all. A more general error queue to queue errors for later handling
242 * is probably better.
243 */
244static int dccp_v4_err(struct sk_buff *skb, u32 info)
245{
246 const struct iphdr *iph = (struct iphdr *)skb->data;
247 const u8 offset = iph->ihl << 2;
248 const struct dccp_hdr *dh;
249 struct dccp_sock *dp;
250 const int type = icmp_hdr(skb)->type;
251 const int code = icmp_hdr(skb)->code;
252 struct sock *sk;
253 __u64 seq;
254 int err;
255 struct net *net = dev_net(skb->dev);
256
257 if (!pskb_may_pull(skb, offset + sizeof(*dh)))
258 return -EINVAL;
259 dh = (struct dccp_hdr *)(skb->data + offset);
260 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
261 return -EINVAL;
262 iph = (struct iphdr *)skb->data;
263 dh = (struct dccp_hdr *)(skb->data + offset);
264
265 sk = __inet_lookup_established(net, &dccp_hashinfo,
266 iph->daddr, dh->dccph_dport,
267 iph->saddr, ntohs(dh->dccph_sport),
268 inet_iif(skb), 0);
269 if (!sk) {
270 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
271 return -ENOENT;
272 }
273
274 if (sk->sk_state == DCCP_TIME_WAIT) {
275 inet_twsk_put(inet_twsk(sk));
276 return 0;
277 }
278 seq = dccp_hdr_seq(dh);
279 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
280 dccp_req_err(sk, seq);
281 return 0;
282 }
283
284 bh_lock_sock(sk);
285 /* If too many ICMPs get dropped on busy
286 * servers this needs to be solved differently.
287 */
288 if (sock_owned_by_user(sk))
289 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
290
291 if (sk->sk_state == DCCP_CLOSED)
292 goto out;
293
294 dp = dccp_sk(sk);
295 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
296 !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
297 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
298 goto out;
299 }
300
301 switch (type) {
302 case ICMP_REDIRECT:
303 if (!sock_owned_by_user(sk))
304 dccp_do_redirect(skb, sk);
305 goto out;
306 case ICMP_SOURCE_QUENCH:
307 /* Just silently ignore these. */
308 goto out;
309 case ICMP_PARAMETERPROB:
310 err = EPROTO;
311 break;
312 case ICMP_DEST_UNREACH:
313 if (code > NR_ICMP_UNREACH)
314 goto out;
315
316 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
317 if (!sock_owned_by_user(sk))
318 dccp_do_pmtu_discovery(sk, iph, info);
319 goto out;
320 }
321
322 err = icmp_err_convert[code].errno;
323 break;
324 case ICMP_TIME_EXCEEDED:
325 err = EHOSTUNREACH;
326 break;
327 default:
328 goto out;
329 }
330
331 switch (sk->sk_state) {
332 case DCCP_REQUESTING:
333 case DCCP_RESPOND:
334 if (!sock_owned_by_user(sk)) {
335 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
336 sk->sk_err = err;
337
338 sk_error_report(sk);
339
340 dccp_done(sk);
341 } else {
342 WRITE_ONCE(sk->sk_err_soft, err);
343 }
344 goto out;
345 }
346
347 /* If we've already connected we will keep trying
348 * until we time out, or the user gives up.
349 *
350 * rfc1122 4.2.3.9 allows to consider as hard errors
351 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
352 * but it is obsoleted by pmtu discovery).
353 *
354 * Note, that in modern internet, where routing is unreliable
355 * and in each dark corner broken firewalls sit, sending random
356 * errors ordered by their masters even this two messages finally lose
357 * their original sense (even Linux sends invalid PORT_UNREACHs)
358 *
359 * Now we are in compliance with RFCs.
360 * --ANK (980905)
361 */
362
363 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
364 sk->sk_err = err;
365 sk_error_report(sk);
366 } else { /* Only an error on timeout */
367 WRITE_ONCE(sk->sk_err_soft, err);
368 }
369out:
370 bh_unlock_sock(sk);
371 sock_put(sk);
372 return 0;
373}
374
375static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
376 __be32 src, __be32 dst)
377{
378 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
379}
380
381void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
382{
383 const struct inet_sock *inet = inet_sk(sk);
384 struct dccp_hdr *dh = dccp_hdr(skb);
385
386 dccp_csum_outgoing(skb);
387 dh->dccph_checksum = dccp_v4_csum_finish(skb,
388 inet->inet_saddr,
389 inet->inet_daddr);
390}
391EXPORT_SYMBOL_GPL(dccp_v4_send_check);
392
393static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
394{
395 return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
396 ip_hdr(skb)->saddr,
397 dccp_hdr(skb)->dccph_dport,
398 dccp_hdr(skb)->dccph_sport);
399}
400
401/*
402 * The three way handshake has completed - we got a valid ACK or DATAACK -
403 * now create the new socket.
404 *
405 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
406 */
407struct sock *dccp_v4_request_recv_sock(const struct sock *sk,
408 struct sk_buff *skb,
409 struct request_sock *req,
410 struct dst_entry *dst,
411 struct request_sock *req_unhash,
412 bool *own_req)
413{
414 struct inet_request_sock *ireq;
415 struct inet_sock *newinet;
416 struct sock *newsk;
417
418 if (sk_acceptq_is_full(sk))
419 goto exit_overflow;
420
421 newsk = dccp_create_openreq_child(sk, req, skb);
422 if (newsk == NULL)
423 goto exit_nonewsk;
424
425 newinet = inet_sk(newsk);
426 ireq = inet_rsk(req);
427 sk_daddr_set(newsk, ireq->ir_rmt_addr);
428 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
429 newinet->inet_saddr = ireq->ir_loc_addr;
430 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt));
431 newinet->mc_index = inet_iif(skb);
432 newinet->mc_ttl = ip_hdr(skb)->ttl;
433 atomic_set(&newinet->inet_id, get_random_u16());
434
435 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
436 goto put_and_exit;
437
438 sk_setup_caps(newsk, dst);
439
440 dccp_sync_mss(newsk, dst_mtu(dst));
441
442 if (__inet_inherit_port(sk, newsk) < 0)
443 goto put_and_exit;
444 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
445 if (*own_req)
446 ireq->ireq_opt = NULL;
447 else
448 newinet->inet_opt = NULL;
449 return newsk;
450
451exit_overflow:
452 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
453exit_nonewsk:
454 dst_release(dst);
455exit:
456 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
457 return NULL;
458put_and_exit:
459 newinet->inet_opt = NULL;
460 inet_csk_prepare_forced_close(newsk);
461 dccp_done(newsk);
462 goto exit;
463}
464EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
465
466static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
467 struct sk_buff *skb)
468{
469 struct rtable *rt;
470 const struct iphdr *iph = ip_hdr(skb);
471 struct flowi4 fl4 = {
472 .flowi4_oif = inet_iif(skb),
473 .daddr = iph->saddr,
474 .saddr = iph->daddr,
475 .flowi4_tos = ip_sock_rt_tos(sk),
476 .flowi4_scope = ip_sock_rt_scope(sk),
477 .flowi4_proto = sk->sk_protocol,
478 .fl4_sport = dccp_hdr(skb)->dccph_dport,
479 .fl4_dport = dccp_hdr(skb)->dccph_sport,
480 };
481
482 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
483 rt = ip_route_output_flow(net, &fl4, sk);
484 if (IS_ERR(rt)) {
485 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
486 return NULL;
487 }
488
489 return &rt->dst;
490}
491
492static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req)
493{
494 int err = -1;
495 struct sk_buff *skb;
496 struct dst_entry *dst;
497 struct flowi4 fl4;
498
499 dst = inet_csk_route_req(sk, &fl4, req);
500 if (dst == NULL)
501 goto out;
502
503 skb = dccp_make_response(sk, dst, req);
504 if (skb != NULL) {
505 const struct inet_request_sock *ireq = inet_rsk(req);
506 struct dccp_hdr *dh = dccp_hdr(skb);
507
508 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
509 ireq->ir_rmt_addr);
510 rcu_read_lock();
511 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
512 ireq->ir_rmt_addr,
513 rcu_dereference(ireq->ireq_opt),
514 READ_ONCE(inet_sk(sk)->tos));
515 rcu_read_unlock();
516 err = net_xmit_eval(err);
517 }
518
519out:
520 dst_release(dst);
521 return err;
522}
523
524static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
525{
526 int err;
527 const struct iphdr *rxiph;
528 struct sk_buff *skb;
529 struct dst_entry *dst;
530 struct net *net = dev_net(skb_dst(rxskb)->dev);
531 struct dccp_v4_pernet *pn;
532 struct sock *ctl_sk;
533
534 /* Never send a reset in response to a reset. */
535 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
536 return;
537
538 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
539 return;
540
541 pn = net_generic(net, dccp_v4_pernet_id);
542 ctl_sk = pn->v4_ctl_sk;
543 dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
544 if (dst == NULL)
545 return;
546
547 skb = dccp_ctl_make_reset(ctl_sk, rxskb);
548 if (skb == NULL)
549 goto out;
550
551 rxiph = ip_hdr(rxskb);
552 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
553 rxiph->daddr);
554 skb_dst_set(skb, dst_clone(dst));
555
556 local_bh_disable();
557 bh_lock_sock(ctl_sk);
558 err = ip_build_and_send_pkt(skb, ctl_sk,
559 rxiph->daddr, rxiph->saddr, NULL,
560 inet_sk(ctl_sk)->tos);
561 bh_unlock_sock(ctl_sk);
562
563 if (net_xmit_eval(err) == 0) {
564 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
565 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
566 }
567 local_bh_enable();
568out:
569 dst_release(dst);
570}
571
572static void dccp_v4_reqsk_destructor(struct request_sock *req)
573{
574 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
575 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
576}
577
578void dccp_syn_ack_timeout(const struct request_sock *req)
579{
580}
581EXPORT_SYMBOL(dccp_syn_ack_timeout);
582
583static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
584 .family = PF_INET,
585 .obj_size = sizeof(struct dccp_request_sock),
586 .rtx_syn_ack = dccp_v4_send_response,
587 .send_ack = dccp_reqsk_send_ack,
588 .destructor = dccp_v4_reqsk_destructor,
589 .send_reset = dccp_v4_ctl_send_reset,
590 .syn_ack_timeout = dccp_syn_ack_timeout,
591};
592
593int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
594{
595 struct inet_request_sock *ireq;
596 struct request_sock *req;
597 struct dccp_request_sock *dreq;
598 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
599 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
600
601 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
602 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
603 return 0; /* discard, don't send a reset here */
604
605 if (dccp_bad_service_code(sk, service)) {
606 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
607 goto drop;
608 }
609 /*
610 * TW buckets are converted to open requests without
611 * limitations, they conserve resources and peer is
612 * evidently real one.
613 */
614 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
615 if (inet_csk_reqsk_queue_is_full(sk))
616 goto drop;
617
618 if (sk_acceptq_is_full(sk))
619 goto drop;
620
621 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
622 if (req == NULL)
623 goto drop;
624
625 if (dccp_reqsk_init(req, dccp_sk(sk), skb))
626 goto drop_and_free;
627
628 dreq = dccp_rsk(req);
629 if (dccp_parse_options(sk, dreq, skb))
630 goto drop_and_free;
631
632 ireq = inet_rsk(req);
633 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
634 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
635 ireq->ir_mark = inet_request_mark(sk, skb);
636 ireq->ireq_family = AF_INET;
637 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
638
639 if (security_inet_conn_request(sk, skb, req))
640 goto drop_and_free;
641
642 /*
643 * Step 3: Process LISTEN state
644 *
645 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
646 *
647 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
648 */
649 dreq->dreq_isr = dcb->dccpd_seq;
650 dreq->dreq_gsr = dreq->dreq_isr;
651 dreq->dreq_iss = dccp_v4_init_sequence(skb);
652 dreq->dreq_gss = dreq->dreq_iss;
653 dreq->dreq_service = service;
654
655 if (dccp_v4_send_response(sk, req))
656 goto drop_and_free;
657
658 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
659 reqsk_put(req);
660 return 0;
661
662drop_and_free:
663 reqsk_free(req);
664drop:
665 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
666 return -1;
667}
668EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
669
670int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
671{
672 struct dccp_hdr *dh = dccp_hdr(skb);
673
674 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
675 if (dccp_rcv_established(sk, skb, dh, skb->len))
676 goto reset;
677 return 0;
678 }
679
680 /*
681 * Step 3: Process LISTEN state
682 * If P.type == Request or P contains a valid Init Cookie option,
683 * (* Must scan the packet's options to check for Init
684 * Cookies. Only Init Cookies are processed here,
685 * however; other options are processed in Step 8. This
686 * scan need only be performed if the endpoint uses Init
687 * Cookies *)
688 * (* Generate a new socket and switch to that socket *)
689 * Set S := new socket for this port pair
690 * S.state = RESPOND
691 * Choose S.ISS (initial seqno) or set from Init Cookies
692 * Initialize S.GAR := S.ISS
693 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
694 * Continue with S.state == RESPOND
695 * (* A Response packet will be generated in Step 11 *)
696 * Otherwise,
697 * Generate Reset(No Connection) unless P.type == Reset
698 * Drop packet and return
699 *
700 * NOTE: the check for the packet types is done in
701 * dccp_rcv_state_process
702 */
703
704 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
705 goto reset;
706 return 0;
707
708reset:
709 dccp_v4_ctl_send_reset(sk, skb);
710 kfree_skb(skb);
711 return 0;
712}
713EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
714
715/**
716 * dccp_invalid_packet - check for malformed packets
717 * @skb: Packet to validate
718 *
719 * Implements RFC 4340, 8.5: Step 1: Check header basics
720 * Packets that fail these checks are ignored and do not receive Resets.
721 */
722int dccp_invalid_packet(struct sk_buff *skb)
723{
724 const struct dccp_hdr *dh;
725 unsigned int cscov;
726 u8 dccph_doff;
727
728 if (skb->pkt_type != PACKET_HOST)
729 return 1;
730
731 /* If the packet is shorter than 12 bytes, drop packet and return */
732 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
733 DCCP_WARN("pskb_may_pull failed\n");
734 return 1;
735 }
736
737 dh = dccp_hdr(skb);
738
739 /* If P.type is not understood, drop packet and return */
740 if (dh->dccph_type >= DCCP_PKT_INVALID) {
741 DCCP_WARN("invalid packet type\n");
742 return 1;
743 }
744
745 /*
746 * If P.Data Offset is too small for packet type, drop packet and return
747 */
748 dccph_doff = dh->dccph_doff;
749 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
750 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
751 return 1;
752 }
753 /*
754 * If P.Data Offset is too large for packet, drop packet and return
755 */
756 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
757 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
758 return 1;
759 }
760 dh = dccp_hdr(skb);
761 /*
762 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
763 * has short sequence numbers), drop packet and return
764 */
765 if ((dh->dccph_type < DCCP_PKT_DATA ||
766 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
767 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
768 dccp_packet_name(dh->dccph_type));
769 return 1;
770 }
771
772 /*
773 * If P.CsCov is too large for the packet size, drop packet and return.
774 * This must come _before_ checksumming (not as RFC 4340 suggests).
775 */
776 cscov = dccp_csum_coverage(skb);
777 if (cscov > skb->len) {
778 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
779 dh->dccph_cscov, skb->len);
780 return 1;
781 }
782
783 /* If header checksum is incorrect, drop packet and return.
784 * (This step is completed in the AF-dependent functions.) */
785 skb->csum = skb_checksum(skb, 0, cscov, 0);
786
787 return 0;
788}
789EXPORT_SYMBOL_GPL(dccp_invalid_packet);
790
791/* this is called when real data arrives */
792static int dccp_v4_rcv(struct sk_buff *skb)
793{
794 const struct dccp_hdr *dh;
795 const struct iphdr *iph;
796 bool refcounted;
797 struct sock *sk;
798 int min_cov;
799
800 /* Step 1: Check header basics */
801
802 if (dccp_invalid_packet(skb))
803 goto discard_it;
804
805 iph = ip_hdr(skb);
806 /* Step 1: If header checksum is incorrect, drop packet and return */
807 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
808 DCCP_WARN("dropped packet with invalid checksum\n");
809 goto discard_it;
810 }
811
812 dh = dccp_hdr(skb);
813
814 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
815 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
816
817 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
818 dccp_packet_name(dh->dccph_type),
819 &iph->saddr, ntohs(dh->dccph_sport),
820 &iph->daddr, ntohs(dh->dccph_dport),
821 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
822
823 if (dccp_packet_without_ack(skb)) {
824 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
825 dccp_pr_debug_cat("\n");
826 } else {
827 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
828 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
829 DCCP_SKB_CB(skb)->dccpd_ack_seq);
830 }
831
832lookup:
833 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
834 dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
835 if (!sk) {
836 dccp_pr_debug("failed to look up flow ID in table and "
837 "get corresponding socket\n");
838 goto no_dccp_socket;
839 }
840
841 /*
842 * Step 2:
843 * ... or S.state == TIMEWAIT,
844 * Generate Reset(No Connection) unless P.type == Reset
845 * Drop packet and return
846 */
847 if (sk->sk_state == DCCP_TIME_WAIT) {
848 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
849 inet_twsk_put(inet_twsk(sk));
850 goto no_dccp_socket;
851 }
852
853 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
854 struct request_sock *req = inet_reqsk(sk);
855 struct sock *nsk;
856
857 sk = req->rsk_listener;
858 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
859 inet_csk_reqsk_queue_drop_and_put(sk, req);
860 goto lookup;
861 }
862 sock_hold(sk);
863 refcounted = true;
864 nsk = dccp_check_req(sk, skb, req);
865 if (!nsk) {
866 reqsk_put(req);
867 goto discard_and_relse;
868 }
869 if (nsk == sk) {
870 reqsk_put(req);
871 } else if (dccp_child_process(sk, nsk, skb)) {
872 dccp_v4_ctl_send_reset(sk, skb);
873 goto discard_and_relse;
874 } else {
875 sock_put(sk);
876 return 0;
877 }
878 }
879 /*
880 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
881 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
882 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
883 */
884 min_cov = dccp_sk(sk)->dccps_pcrlen;
885 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
886 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
887 dh->dccph_cscov, min_cov);
888 /* FIXME: "Such packets SHOULD be reported using Data Dropped
889 * options (Section 11.7) with Drop Code 0, Protocol
890 * Constraints." */
891 goto discard_and_relse;
892 }
893
894 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
895 goto discard_and_relse;
896 nf_reset_ct(skb);
897
898 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
899
900no_dccp_socket:
901 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
902 goto discard_it;
903 /*
904 * Step 2:
905 * If no socket ...
906 * Generate Reset(No Connection) unless P.type == Reset
907 * Drop packet and return
908 */
909 if (dh->dccph_type != DCCP_PKT_RESET) {
910 DCCP_SKB_CB(skb)->dccpd_reset_code =
911 DCCP_RESET_CODE_NO_CONNECTION;
912 dccp_v4_ctl_send_reset(sk, skb);
913 }
914
915discard_it:
916 kfree_skb(skb);
917 return 0;
918
919discard_and_relse:
920 if (refcounted)
921 sock_put(sk);
922 goto discard_it;
923}
924
925static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
926 .queue_xmit = ip_queue_xmit,
927 .send_check = dccp_v4_send_check,
928 .rebuild_header = inet_sk_rebuild_header,
929 .conn_request = dccp_v4_conn_request,
930 .syn_recv_sock = dccp_v4_request_recv_sock,
931 .net_header_len = sizeof(struct iphdr),
932 .setsockopt = ip_setsockopt,
933 .getsockopt = ip_getsockopt,
934 .addr2sockaddr = inet_csk_addr2sockaddr,
935 .sockaddr_len = sizeof(struct sockaddr_in),
936};
937
938static int dccp_v4_init_sock(struct sock *sk)
939{
940 static __u8 dccp_v4_ctl_sock_initialized;
941 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
942
943 if (err == 0) {
944 if (unlikely(!dccp_v4_ctl_sock_initialized))
945 dccp_v4_ctl_sock_initialized = 1;
946 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
947 }
948
949 return err;
950}
951
952static struct timewait_sock_ops dccp_timewait_sock_ops = {
953 .twsk_obj_size = sizeof(struct inet_timewait_sock),
954};
955
956static struct proto dccp_v4_prot = {
957 .name = "DCCP",
958 .owner = THIS_MODULE,
959 .close = dccp_close,
960 .connect = dccp_v4_connect,
961 .disconnect = dccp_disconnect,
962 .ioctl = dccp_ioctl,
963 .init = dccp_v4_init_sock,
964 .setsockopt = dccp_setsockopt,
965 .getsockopt = dccp_getsockopt,
966 .sendmsg = dccp_sendmsg,
967 .recvmsg = dccp_recvmsg,
968 .backlog_rcv = dccp_v4_do_rcv,
969 .hash = inet_hash,
970 .unhash = inet_unhash,
971 .accept = inet_csk_accept,
972 .get_port = inet_csk_get_port,
973 .shutdown = dccp_shutdown,
974 .destroy = dccp_destroy_sock,
975 .orphan_count = &dccp_orphan_count,
976 .max_header = MAX_DCCP_HEADER,
977 .obj_size = sizeof(struct dccp_sock),
978 .slab_flags = SLAB_TYPESAFE_BY_RCU,
979 .rsk_prot = &dccp_request_sock_ops,
980 .twsk_prot = &dccp_timewait_sock_ops,
981 .h.hashinfo = &dccp_hashinfo,
982};
983
984static const struct net_protocol dccp_v4_protocol = {
985 .handler = dccp_v4_rcv,
986 .err_handler = dccp_v4_err,
987 .no_policy = 1,
988 .icmp_strict_tag_validation = 1,
989};
990
991static const struct proto_ops inet_dccp_ops = {
992 .family = PF_INET,
993 .owner = THIS_MODULE,
994 .release = inet_release,
995 .bind = inet_bind,
996 .connect = inet_stream_connect,
997 .socketpair = sock_no_socketpair,
998 .accept = inet_accept,
999 .getname = inet_getname,
1000 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1001 .poll = dccp_poll,
1002 .ioctl = inet_ioctl,
1003 .gettstamp = sock_gettstamp,
1004 /* FIXME: work on inet_listen to rename it to sock_common_listen */
1005 .listen = inet_dccp_listen,
1006 .shutdown = inet_shutdown,
1007 .setsockopt = sock_common_setsockopt,
1008 .getsockopt = sock_common_getsockopt,
1009 .sendmsg = inet_sendmsg,
1010 .recvmsg = sock_common_recvmsg,
1011 .mmap = sock_no_mmap,
1012};
1013
1014static struct inet_protosw dccp_v4_protosw = {
1015 .type = SOCK_DCCP,
1016 .protocol = IPPROTO_DCCP,
1017 .prot = &dccp_v4_prot,
1018 .ops = &inet_dccp_ops,
1019 .flags = INET_PROTOSW_ICSK,
1020};
1021
1022static int __net_init dccp_v4_init_net(struct net *net)
1023{
1024 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1025
1026 if (dccp_hashinfo.bhash == NULL)
1027 return -ESOCKTNOSUPPORT;
1028
1029 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET,
1030 SOCK_DCCP, IPPROTO_DCCP, net);
1031}
1032
1033static void __net_exit dccp_v4_exit_net(struct net *net)
1034{
1035 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id);
1036
1037 inet_ctl_sock_destroy(pn->v4_ctl_sk);
1038}
1039
1040static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1041{
1042 inet_twsk_purge(&dccp_hashinfo, AF_INET);
1043}
1044
1045static struct pernet_operations dccp_v4_ops = {
1046 .init = dccp_v4_init_net,
1047 .exit = dccp_v4_exit_net,
1048 .exit_batch = dccp_v4_exit_batch,
1049 .id = &dccp_v4_pernet_id,
1050 .size = sizeof(struct dccp_v4_pernet),
1051};
1052
1053static int __init dccp_v4_init(void)
1054{
1055 int err = proto_register(&dccp_v4_prot, 1);
1056
1057 if (err)
1058 goto out;
1059
1060 inet_register_protosw(&dccp_v4_protosw);
1061
1062 err = register_pernet_subsys(&dccp_v4_ops);
1063 if (err)
1064 goto out_destroy_ctl_sock;
1065
1066 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1067 if (err)
1068 goto out_proto_unregister;
1069
1070out:
1071 return err;
1072out_proto_unregister:
1073 unregister_pernet_subsys(&dccp_v4_ops);
1074out_destroy_ctl_sock:
1075 inet_unregister_protosw(&dccp_v4_protosw);
1076 proto_unregister(&dccp_v4_prot);
1077 goto out;
1078}
1079
1080static void __exit dccp_v4_exit(void)
1081{
1082 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1083 unregister_pernet_subsys(&dccp_v4_ops);
1084 inet_unregister_protosw(&dccp_v4_protosw);
1085 proto_unregister(&dccp_v4_prot);
1086}
1087
1088module_init(dccp_v4_init);
1089module_exit(dccp_v4_exit);
1090
1091/*
1092 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1093 * values directly, Also cover the case where the protocol is not specified,
1094 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1095 */
1096MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1097MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1098MODULE_LICENSE("GPL");
1099MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1100MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");