1 /*
2 * net/dccp/ipv4.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13 #include <linux/dccp.h>
14 #include <linux/icmp.h>
15 #include <linux/slab.h>
16 #include <linux/module.h>
17 #include <linux/skbuff.h>
18 #include <linux/random.h>
19
20 #include <net/icmp.h>
21 #include <net/inet_common.h>
22 #include <net/inet_hashtables.h>
23 #include <net/inet_sock.h>
24 #include <net/protocol.h>
25 #include <net/sock.h>
26 #include <net/timewait_sock.h>
27 #include <net/tcp_states.h>
28 #include <net/xfrm.h>
29 #include <net/secure_seq.h>
30
31 #include "ackvec.h"
32 #include "ccid.h"
33 #include "dccp.h"
34 #include "feat.h"
35
36 /*
37 * The per-net dccp.v4_ctl_sk socket is used for responding to
38 * the Out-of-the-blue (OOTB) packets. A control sock will be created
39 * for this socket at the initialization time.
40 */
41
dccp_v4_connect(struct sock * sk,struct sockaddr * uaddr,int addr_len)42 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
43 {
44 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
45 struct inet_sock *inet = inet_sk(sk);
46 struct dccp_sock *dp = dccp_sk(sk);
47 __be16 orig_sport, orig_dport;
48 __be32 daddr, nexthop;
49 struct flowi4 *fl4;
50 struct rtable *rt;
51 int err;
52 struct ip_options_rcu *inet_opt;
53
54 dp->dccps_role = DCCP_ROLE_CLIENT;
55
56 if (addr_len < sizeof(struct sockaddr_in))
57 return -EINVAL;
58
59 if (usin->sin_family != AF_INET)
60 return -EAFNOSUPPORT;
61
62 nexthop = daddr = usin->sin_addr.s_addr;
63
64 inet_opt = rcu_dereference_protected(inet->inet_opt,
65 sock_owned_by_user(sk));
66 if (inet_opt != NULL && inet_opt->opt.srr) {
67 if (daddr == 0)
68 return -EINVAL;
69 nexthop = inet_opt->opt.faddr;
70 }
71
72 orig_sport = inet->inet_sport;
73 orig_dport = usin->sin_port;
74 fl4 = &inet->cork.fl.u.ip4;
75 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
76 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
77 IPPROTO_DCCP,
78 orig_sport, orig_dport, sk, true);
79 if (IS_ERR(rt))
80 return PTR_ERR(rt);
81
82 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
83 ip_rt_put(rt);
84 return -ENETUNREACH;
85 }
86
87 if (inet_opt == NULL || !inet_opt->opt.srr)
88 daddr = fl4->daddr;
89
90 if (inet->inet_saddr == 0)
91 inet->inet_saddr = fl4->saddr;
92 inet->inet_rcv_saddr = inet->inet_saddr;
93
94 inet->inet_dport = usin->sin_port;
95 inet->inet_daddr = daddr;
96
97 inet_csk(sk)->icsk_ext_hdr_len = 0;
98 if (inet_opt)
99 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
100 /*
101 * Socket identity is still unknown (sport may be zero).
102 * However we set state to DCCP_REQUESTING and not releasing socket
103 * lock select source port, enter ourselves into the hash tables and
104 * complete initialization after this.
105 */
106 dccp_set_state(sk, DCCP_REQUESTING);
107 err = inet_hash_connect(&dccp_death_row, sk);
108 if (err != 0)
109 goto failure;
110
111 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
112 inet->inet_sport, inet->inet_dport, sk);
113 if (IS_ERR(rt)) {
114 err = PTR_ERR(rt);
115 rt = NULL;
116 goto failure;
117 }
118 /* OK, now commit destination to socket. */
119 sk_setup_caps(sk, &rt->dst);
120
121 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
122 inet->inet_daddr,
123 inet->inet_sport,
124 inet->inet_dport);
125 inet->inet_id = dp->dccps_iss ^ jiffies;
126
127 err = dccp_connect(sk);
128 rt = NULL;
129 if (err != 0)
130 goto failure;
131 out:
132 return err;
133 failure:
134 /*
135 * This unhashes the socket and releases the local port, if necessary.
136 */
137 dccp_set_state(sk, DCCP_CLOSED);
138 ip_rt_put(rt);
139 sk->sk_route_caps = 0;
140 inet->inet_dport = 0;
141 goto out;
142 }
143
144 EXPORT_SYMBOL_GPL(dccp_v4_connect);
145
146 /*
147 * This routine does path mtu discovery as defined in RFC1191.
148 */
dccp_do_pmtu_discovery(struct sock * sk,const struct iphdr * iph,u32 mtu)149 static inline void dccp_do_pmtu_discovery(struct sock *sk,
150 const struct iphdr *iph,
151 u32 mtu)
152 {
153 struct dst_entry *dst;
154 const struct inet_sock *inet = inet_sk(sk);
155 const struct dccp_sock *dp = dccp_sk(sk);
156
157 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
158 * send out by Linux are always < 576bytes so they should go through
159 * unfragmented).
160 */
161 if (sk->sk_state == DCCP_LISTEN)
162 return;
163
164 /* We don't check in the destentry if pmtu discovery is forbidden
165 * on this route. We just assume that no packet_to_big packets
166 * are send back when pmtu discovery is not active.
167 * There is a small race when the user changes this flag in the
168 * route, but I think that's acceptable.
169 */
170 if ((dst = __sk_dst_check(sk, 0)) == NULL)
171 return;
172
173 dst->ops->update_pmtu(dst, mtu);
174
175 /* Something is about to be wrong... Remember soft error
176 * for the case, if this connection will not able to recover.
177 */
178 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
179 sk->sk_err_soft = EMSGSIZE;
180
181 mtu = dst_mtu(dst);
182
183 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
184 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
185 dccp_sync_mss(sk, mtu);
186
187 /*
188 * From RFC 4340, sec. 14.1:
189 *
190 * DCCP-Sync packets are the best choice for upward
191 * probing, since DCCP-Sync probes do not risk application
192 * data loss.
193 */
194 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
195 } /* else let the usual retransmit timer handle it */
196 }
197
198 /*
199 * This routine is called by the ICMP module when it gets some sort of error
200 * condition. If err < 0 then the socket should be closed and the error
201 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
202 * After adjustment header points to the first 8 bytes of the tcp header. We
203 * need to find the appropriate port.
204 *
205 * The locking strategy used here is very "optimistic". When someone else
206 * accesses the socket the ICMP is just dropped and for some paths there is no
207 * check at all. A more general error queue to queue errors for later handling
208 * is probably better.
209 */
dccp_v4_err(struct sk_buff * skb,u32 info)210 static void dccp_v4_err(struct sk_buff *skb, u32 info)
211 {
212 const struct iphdr *iph = (struct iphdr *)skb->data;
213 const u8 offset = iph->ihl << 2;
214 const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
215 struct dccp_sock *dp;
216 struct inet_sock *inet;
217 const int type = icmp_hdr(skb)->type;
218 const int code = icmp_hdr(skb)->code;
219 struct sock *sk;
220 __u64 seq;
221 int err;
222 struct net *net = dev_net(skb->dev);
223
224 if (skb->len < offset + sizeof(*dh) ||
225 skb->len < offset + __dccp_basic_hdr_len(dh)) {
226 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
227 return;
228 }
229
230 sk = inet_lookup(net, &dccp_hashinfo,
231 iph->daddr, dh->dccph_dport,
232 iph->saddr, dh->dccph_sport, inet_iif(skb));
233 if (sk == NULL) {
234 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
235 return;
236 }
237
238 if (sk->sk_state == DCCP_TIME_WAIT) {
239 inet_twsk_put(inet_twsk(sk));
240 return;
241 }
242
243 bh_lock_sock(sk);
244 /* If too many ICMPs get dropped on busy
245 * servers this needs to be solved differently.
246 */
247 if (sock_owned_by_user(sk))
248 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
249
250 if (sk->sk_state == DCCP_CLOSED)
251 goto out;
252
253 dp = dccp_sk(sk);
254 seq = dccp_hdr_seq(dh);
255 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
256 !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
257 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
258 goto out;
259 }
260
261 switch (type) {
262 case ICMP_SOURCE_QUENCH:
263 /* Just silently ignore these. */
264 goto out;
265 case ICMP_PARAMETERPROB:
266 err = EPROTO;
267 break;
268 case ICMP_DEST_UNREACH:
269 if (code > NR_ICMP_UNREACH)
270 goto out;
271
272 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
273 if (!sock_owned_by_user(sk))
274 dccp_do_pmtu_discovery(sk, iph, info);
275 goto out;
276 }
277
278 err = icmp_err_convert[code].errno;
279 break;
280 case ICMP_TIME_EXCEEDED:
281 err = EHOSTUNREACH;
282 break;
283 default:
284 goto out;
285 }
286
287 switch (sk->sk_state) {
288 struct request_sock *req , **prev;
289 case DCCP_LISTEN:
290 if (sock_owned_by_user(sk))
291 goto out;
292 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
293 iph->daddr, iph->saddr);
294 if (!req)
295 goto out;
296
297 /*
298 * ICMPs are not backlogged, hence we cannot get an established
299 * socket here.
300 */
301 WARN_ON(req->sk);
302
303 if (!between48(seq, dccp_rsk(req)->dreq_iss,
304 dccp_rsk(req)->dreq_gss)) {
305 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
306 goto out;
307 }
308 /*
309 * Still in RESPOND, just remove it silently.
310 * There is no good way to pass the error to the newly
311 * created socket, and POSIX does not want network
312 * errors returned from accept().
313 */
314 inet_csk_reqsk_queue_drop(sk, req, prev);
315 goto out;
316
317 case DCCP_REQUESTING:
318 case DCCP_RESPOND:
319 if (!sock_owned_by_user(sk)) {
320 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
321 sk->sk_err = err;
322
323 sk->sk_error_report(sk);
324
325 dccp_done(sk);
326 } else
327 sk->sk_err_soft = err;
328 goto out;
329 }
330
331 /* If we've already connected we will keep trying
332 * until we time out, or the user gives up.
333 *
334 * rfc1122 4.2.3.9 allows to consider as hard errors
335 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
336 * but it is obsoleted by pmtu discovery).
337 *
338 * Note, that in modern internet, where routing is unreliable
339 * and in each dark corner broken firewalls sit, sending random
340 * errors ordered by their masters even this two messages finally lose
341 * their original sense (even Linux sends invalid PORT_UNREACHs)
342 *
343 * Now we are in compliance with RFCs.
344 * --ANK (980905)
345 */
346
347 inet = inet_sk(sk);
348 if (!sock_owned_by_user(sk) && inet->recverr) {
349 sk->sk_err = err;
350 sk->sk_error_report(sk);
351 } else /* Only an error on timeout */
352 sk->sk_err_soft = err;
353 out:
354 bh_unlock_sock(sk);
355 sock_put(sk);
356 }
357
dccp_v4_csum_finish(struct sk_buff * skb,__be32 src,__be32 dst)358 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
359 __be32 src, __be32 dst)
360 {
361 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
362 }
363
dccp_v4_send_check(struct sock * sk,struct sk_buff * skb)364 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
365 {
366 const struct inet_sock *inet = inet_sk(sk);
367 struct dccp_hdr *dh = dccp_hdr(skb);
368
369 dccp_csum_outgoing(skb);
370 dh->dccph_checksum = dccp_v4_csum_finish(skb,
371 inet->inet_saddr,
372 inet->inet_daddr);
373 }
374
375 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
376
dccp_v4_init_sequence(const struct sk_buff * skb)377 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
378 {
379 return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
380 ip_hdr(skb)->saddr,
381 dccp_hdr(skb)->dccph_dport,
382 dccp_hdr(skb)->dccph_sport);
383 }
384
385 /*
386 * The three way handshake has completed - we got a valid ACK or DATAACK -
387 * now create the new socket.
388 *
389 * This is the equivalent of TCP's tcp_v4_syn_recv_sock
390 */
dccp_v4_request_recv_sock(struct sock * sk,struct sk_buff * skb,struct request_sock * req,struct dst_entry * dst)391 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
392 struct request_sock *req,
393 struct dst_entry *dst)
394 {
395 struct inet_request_sock *ireq;
396 struct inet_sock *newinet;
397 struct sock *newsk;
398
399 if (sk_acceptq_is_full(sk))
400 goto exit_overflow;
401
402 newsk = dccp_create_openreq_child(sk, req, skb);
403 if (newsk == NULL)
404 goto exit_nonewsk;
405
406 newinet = inet_sk(newsk);
407 ireq = inet_rsk(req);
408 newinet->inet_daddr = ireq->rmt_addr;
409 newinet->inet_rcv_saddr = ireq->loc_addr;
410 newinet->inet_saddr = ireq->loc_addr;
411 newinet->inet_opt = ireq->opt;
412 ireq->opt = NULL;
413 newinet->mc_index = inet_iif(skb);
414 newinet->mc_ttl = ip_hdr(skb)->ttl;
415 newinet->inet_id = jiffies;
416
417 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
418 goto put_and_exit;
419
420 sk_setup_caps(newsk, dst);
421
422 dccp_sync_mss(newsk, dst_mtu(dst));
423
424 if (__inet_inherit_port(sk, newsk) < 0)
425 goto put_and_exit;
426 __inet_hash_nolisten(newsk, NULL);
427
428 return newsk;
429
430 exit_overflow:
431 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
432 exit_nonewsk:
433 dst_release(dst);
434 exit:
435 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
436 return NULL;
437 put_and_exit:
438 inet_csk_prepare_forced_close(newsk);
439 dccp_done(newsk);
440 goto exit;
441 }
442
443 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
444
dccp_v4_hnd_req(struct sock * sk,struct sk_buff * skb)445 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
446 {
447 const struct dccp_hdr *dh = dccp_hdr(skb);
448 const struct iphdr *iph = ip_hdr(skb);
449 struct sock *nsk;
450 struct request_sock **prev;
451 /* Find possible connection requests. */
452 struct request_sock *req = inet_csk_search_req(sk, &prev,
453 dh->dccph_sport,
454 iph->saddr, iph->daddr);
455 if (req != NULL)
456 return dccp_check_req(sk, skb, req, prev);
457
458 nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
459 iph->saddr, dh->dccph_sport,
460 iph->daddr, dh->dccph_dport,
461 inet_iif(skb));
462 if (nsk != NULL) {
463 if (nsk->sk_state != DCCP_TIME_WAIT) {
464 bh_lock_sock(nsk);
465 return nsk;
466 }
467 inet_twsk_put(inet_twsk(nsk));
468 return NULL;
469 }
470
471 return sk;
472 }
473
dccp_v4_route_skb(struct net * net,struct sock * sk,struct sk_buff * skb)474 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
475 struct sk_buff *skb)
476 {
477 struct rtable *rt;
478 const struct iphdr *iph = ip_hdr(skb);
479 struct flowi4 fl4 = {
480 .flowi4_oif = skb_rtable(skb)->rt_iif,
481 .daddr = iph->saddr,
482 .saddr = iph->daddr,
483 .flowi4_tos = RT_CONN_FLAGS(sk),
484 .flowi4_proto = sk->sk_protocol,
485 .fl4_sport = dccp_hdr(skb)->dccph_dport,
486 .fl4_dport = dccp_hdr(skb)->dccph_sport,
487 };
488
489 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
490 rt = ip_route_output_flow(net, &fl4, sk);
491 if (IS_ERR(rt)) {
492 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
493 return NULL;
494 }
495
496 return &rt->dst;
497 }
498
dccp_v4_send_response(struct sock * sk,struct request_sock * req,struct request_values * rv_unused)499 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
500 struct request_values *rv_unused)
501 {
502 int err = -1;
503 struct sk_buff *skb;
504 struct dst_entry *dst;
505 struct flowi4 fl4;
506
507 dst = inet_csk_route_req(sk, &fl4, req);
508 if (dst == NULL)
509 goto out;
510
511 skb = dccp_make_response(sk, dst, req);
512 if (skb != NULL) {
513 const struct inet_request_sock *ireq = inet_rsk(req);
514 struct dccp_hdr *dh = dccp_hdr(skb);
515
516 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
517 ireq->rmt_addr);
518 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
519 ireq->rmt_addr,
520 ireq->opt);
521 err = net_xmit_eval(err);
522 }
523
524 out:
525 dst_release(dst);
526 return err;
527 }
528
dccp_v4_ctl_send_reset(struct sock * sk,struct sk_buff * rxskb)529 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
530 {
531 int err;
532 const struct iphdr *rxiph;
533 struct sk_buff *skb;
534 struct dst_entry *dst;
535 struct net *net = dev_net(skb_dst(rxskb)->dev);
536 struct sock *ctl_sk = net->dccp.v4_ctl_sk;
537
538 /* Never send a reset in response to a reset. */
539 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
540 return;
541
542 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
543 return;
544
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 bh_lock_sock(ctl_sk);
559 err = ip_build_and_send_pkt(skb, ctl_sk,
560 rxiph->daddr, rxiph->saddr, NULL);
561 bh_unlock_sock(ctl_sk);
562
563 if (net_xmit_eval(err) == 0) {
564 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
565 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
566 }
567 out:
568 dst_release(dst);
569 }
570
dccp_v4_reqsk_destructor(struct request_sock * req)571 static void dccp_v4_reqsk_destructor(struct request_sock *req)
572 {
573 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
574 kfree(inet_rsk(req)->opt);
575 }
576
577 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
578 .family = PF_INET,
579 .obj_size = sizeof(struct dccp_request_sock),
580 .rtx_syn_ack = dccp_v4_send_response,
581 .send_ack = dccp_reqsk_send_ack,
582 .destructor = dccp_v4_reqsk_destructor,
583 .send_reset = dccp_v4_ctl_send_reset,
584 };
585
dccp_v4_conn_request(struct sock * sk,struct sk_buff * skb)586 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
587 {
588 struct inet_request_sock *ireq;
589 struct request_sock *req;
590 struct dccp_request_sock *dreq;
591 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
592 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
593
594 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
595 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
596 return 0; /* discard, don't send a reset here */
597
598 if (dccp_bad_service_code(sk, service)) {
599 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
600 goto drop;
601 }
602 /*
603 * TW buckets are converted to open requests without
604 * limitations, they conserve resources and peer is
605 * evidently real one.
606 */
607 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
608 if (inet_csk_reqsk_queue_is_full(sk))
609 goto drop;
610
611 /*
612 * Accept backlog is full. If we have already queued enough
613 * of warm entries in syn queue, drop request. It is better than
614 * clogging syn queue with openreqs with exponentially increasing
615 * timeout.
616 */
617 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
618 goto drop;
619
620 req = inet_reqsk_alloc(&dccp_request_sock_ops);
621 if (req == NULL)
622 goto drop;
623
624 if (dccp_reqsk_init(req, dccp_sk(sk), skb))
625 goto drop_and_free;
626
627 dreq = dccp_rsk(req);
628 if (dccp_parse_options(sk, dreq, skb))
629 goto drop_and_free;
630
631 if (security_inet_conn_request(sk, skb, req))
632 goto drop_and_free;
633
634 ireq = inet_rsk(req);
635 ireq->loc_addr = ip_hdr(skb)->daddr;
636 ireq->rmt_addr = ip_hdr(skb)->saddr;
637
638 /*
639 * Step 3: Process LISTEN state
640 *
641 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
642 *
643 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
644 */
645 dreq->dreq_isr = dcb->dccpd_seq;
646 dreq->dreq_gsr = dreq->dreq_isr;
647 dreq->dreq_iss = dccp_v4_init_sequence(skb);
648 dreq->dreq_gss = dreq->dreq_iss;
649 dreq->dreq_service = service;
650
651 if (dccp_v4_send_response(sk, req, NULL))
652 goto drop_and_free;
653
654 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
655 return 0;
656
657 drop_and_free:
658 reqsk_free(req);
659 drop:
660 DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
661 return -1;
662 }
663
664 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
665
dccp_v4_do_rcv(struct sock * sk,struct sk_buff * skb)666 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
667 {
668 struct dccp_hdr *dh = dccp_hdr(skb);
669
670 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
671 if (dccp_rcv_established(sk, skb, dh, skb->len))
672 goto reset;
673 return 0;
674 }
675
676 /*
677 * Step 3: Process LISTEN state
678 * If P.type == Request or P contains a valid Init Cookie option,
679 * (* Must scan the packet's options to check for Init
680 * Cookies. Only Init Cookies are processed here,
681 * however; other options are processed in Step 8. This
682 * scan need only be performed if the endpoint uses Init
683 * Cookies *)
684 * (* Generate a new socket and switch to that socket *)
685 * Set S := new socket for this port pair
686 * S.state = RESPOND
687 * Choose S.ISS (initial seqno) or set from Init Cookies
688 * Initialize S.GAR := S.ISS
689 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
690 * Continue with S.state == RESPOND
691 * (* A Response packet will be generated in Step 11 *)
692 * Otherwise,
693 * Generate Reset(No Connection) unless P.type == Reset
694 * Drop packet and return
695 *
696 * NOTE: the check for the packet types is done in
697 * dccp_rcv_state_process
698 */
699 if (sk->sk_state == DCCP_LISTEN) {
700 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
701
702 if (nsk == NULL)
703 goto discard;
704
705 if (nsk != sk) {
706 if (dccp_child_process(sk, nsk, skb))
707 goto reset;
708 return 0;
709 }
710 }
711
712 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
713 goto reset;
714 return 0;
715
716 reset:
717 dccp_v4_ctl_send_reset(sk, skb);
718 discard:
719 kfree_skb(skb);
720 return 0;
721 }
722
723 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
724
725 /**
726 * dccp_invalid_packet - check for malformed packets
727 * Implements RFC 4340, 8.5: Step 1: Check header basics
728 * Packets that fail these checks are ignored and do not receive Resets.
729 */
dccp_invalid_packet(struct sk_buff * skb)730 int dccp_invalid_packet(struct sk_buff *skb)
731 {
732 const struct dccp_hdr *dh;
733 unsigned int cscov;
734
735 if (skb->pkt_type != PACKET_HOST)
736 return 1;
737
738 /* If the packet is shorter than 12 bytes, drop packet and return */
739 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
740 DCCP_WARN("pskb_may_pull failed\n");
741 return 1;
742 }
743
744 dh = dccp_hdr(skb);
745
746 /* If P.type is not understood, drop packet and return */
747 if (dh->dccph_type >= DCCP_PKT_INVALID) {
748 DCCP_WARN("invalid packet type\n");
749 return 1;
750 }
751
752 /*
753 * If P.Data Offset is too small for packet type, drop packet and return
754 */
755 if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
756 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
757 return 1;
758 }
759 /*
760 * If P.Data Offset is too too large for packet, drop packet and return
761 */
762 if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
763 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
764 return 1;
765 }
766
767 /*
768 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
769 * has short sequence numbers), drop packet and return
770 */
771 if ((dh->dccph_type < DCCP_PKT_DATA ||
772 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
773 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
774 dccp_packet_name(dh->dccph_type));
775 return 1;
776 }
777
778 /*
779 * If P.CsCov is too large for the packet size, drop packet and return.
780 * This must come _before_ checksumming (not as RFC 4340 suggests).
781 */
782 cscov = dccp_csum_coverage(skb);
783 if (cscov > skb->len) {
784 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
785 dh->dccph_cscov, skb->len);
786 return 1;
787 }
788
789 /* If header checksum is incorrect, drop packet and return.
790 * (This step is completed in the AF-dependent functions.) */
791 skb->csum = skb_checksum(skb, 0, cscov, 0);
792
793 return 0;
794 }
795
796 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
797
798 /* this is called when real data arrives */
dccp_v4_rcv(struct sk_buff * skb)799 static int dccp_v4_rcv(struct sk_buff *skb)
800 {
801 const struct dccp_hdr *dh;
802 const struct iphdr *iph;
803 struct sock *sk;
804 int min_cov;
805
806 /* Step 1: Check header basics */
807
808 if (dccp_invalid_packet(skb))
809 goto discard_it;
810
811 iph = ip_hdr(skb);
812 /* Step 1: If header checksum is incorrect, drop packet and return */
813 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
814 DCCP_WARN("dropped packet with invalid checksum\n");
815 goto discard_it;
816 }
817
818 dh = dccp_hdr(skb);
819
820 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
821 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
822
823 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
824 dccp_packet_name(dh->dccph_type),
825 &iph->saddr, ntohs(dh->dccph_sport),
826 &iph->daddr, ntohs(dh->dccph_dport),
827 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
828
829 if (dccp_packet_without_ack(skb)) {
830 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
831 dccp_pr_debug_cat("\n");
832 } else {
833 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
834 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
835 DCCP_SKB_CB(skb)->dccpd_ack_seq);
836 }
837
838 /* Step 2:
839 * Look up flow ID in table and get corresponding socket */
840 sk = __inet_lookup_skb(&dccp_hashinfo, skb,
841 dh->dccph_sport, dh->dccph_dport);
842 /*
843 * Step 2:
844 * If no socket ...
845 */
846 if (sk == NULL) {
847 dccp_pr_debug("failed to look up flow ID in table and "
848 "get corresponding socket\n");
849 goto no_dccp_socket;
850 }
851
852 /*
853 * Step 2:
854 * ... or S.state == TIMEWAIT,
855 * Generate Reset(No Connection) unless P.type == Reset
856 * Drop packet and return
857 */
858 if (sk->sk_state == DCCP_TIME_WAIT) {
859 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
860 inet_twsk_put(inet_twsk(sk));
861 goto no_dccp_socket;
862 }
863
864 /*
865 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
866 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
867 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
868 */
869 min_cov = dccp_sk(sk)->dccps_pcrlen;
870 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
871 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
872 dh->dccph_cscov, min_cov);
873 /* FIXME: "Such packets SHOULD be reported using Data Dropped
874 * options (Section 11.7) with Drop Code 0, Protocol
875 * Constraints." */
876 goto discard_and_relse;
877 }
878
879 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
880 goto discard_and_relse;
881 nf_reset(skb);
882
883 return sk_receive_skb(sk, skb, 1);
884
885 no_dccp_socket:
886 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
887 goto discard_it;
888 /*
889 * Step 2:
890 * If no socket ...
891 * Generate Reset(No Connection) unless P.type == Reset
892 * Drop packet and return
893 */
894 if (dh->dccph_type != DCCP_PKT_RESET) {
895 DCCP_SKB_CB(skb)->dccpd_reset_code =
896 DCCP_RESET_CODE_NO_CONNECTION;
897 dccp_v4_ctl_send_reset(sk, skb);
898 }
899
900 discard_it:
901 kfree_skb(skb);
902 return 0;
903
904 discard_and_relse:
905 sock_put(sk);
906 goto discard_it;
907 }
908
909 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
910 .queue_xmit = ip_queue_xmit,
911 .send_check = dccp_v4_send_check,
912 .rebuild_header = inet_sk_rebuild_header,
913 .conn_request = dccp_v4_conn_request,
914 .syn_recv_sock = dccp_v4_request_recv_sock,
915 .net_header_len = sizeof(struct iphdr),
916 .setsockopt = ip_setsockopt,
917 .getsockopt = ip_getsockopt,
918 .addr2sockaddr = inet_csk_addr2sockaddr,
919 .sockaddr_len = sizeof(struct sockaddr_in),
920 .bind_conflict = inet_csk_bind_conflict,
921 #ifdef CONFIG_COMPAT
922 .compat_setsockopt = compat_ip_setsockopt,
923 .compat_getsockopt = compat_ip_getsockopt,
924 #endif
925 };
926
dccp_v4_init_sock(struct sock * sk)927 static int dccp_v4_init_sock(struct sock *sk)
928 {
929 static __u8 dccp_v4_ctl_sock_initialized;
930 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
931
932 if (err == 0) {
933 if (unlikely(!dccp_v4_ctl_sock_initialized))
934 dccp_v4_ctl_sock_initialized = 1;
935 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
936 }
937
938 return err;
939 }
940
941 static struct timewait_sock_ops dccp_timewait_sock_ops = {
942 .twsk_obj_size = sizeof(struct inet_timewait_sock),
943 };
944
945 static struct proto dccp_v4_prot = {
946 .name = "DCCP",
947 .owner = THIS_MODULE,
948 .close = dccp_close,
949 .connect = dccp_v4_connect,
950 .disconnect = dccp_disconnect,
951 .ioctl = dccp_ioctl,
952 .init = dccp_v4_init_sock,
953 .setsockopt = dccp_setsockopt,
954 .getsockopt = dccp_getsockopt,
955 .sendmsg = dccp_sendmsg,
956 .recvmsg = dccp_recvmsg,
957 .backlog_rcv = dccp_v4_do_rcv,
958 .hash = inet_hash,
959 .unhash = inet_unhash,
960 .accept = inet_csk_accept,
961 .get_port = inet_csk_get_port,
962 .shutdown = dccp_shutdown,
963 .destroy = dccp_destroy_sock,
964 .orphan_count = &dccp_orphan_count,
965 .max_header = MAX_DCCP_HEADER,
966 .obj_size = sizeof(struct dccp_sock),
967 .slab_flags = SLAB_DESTROY_BY_RCU,
968 .rsk_prot = &dccp_request_sock_ops,
969 .twsk_prot = &dccp_timewait_sock_ops,
970 .h.hashinfo = &dccp_hashinfo,
971 #ifdef CONFIG_COMPAT
972 .compat_setsockopt = compat_dccp_setsockopt,
973 .compat_getsockopt = compat_dccp_getsockopt,
974 #endif
975 };
976
977 static const struct net_protocol dccp_v4_protocol = {
978 .handler = dccp_v4_rcv,
979 .err_handler = dccp_v4_err,
980 .no_policy = 1,
981 .netns_ok = 1,
982 };
983
984 static const struct proto_ops inet_dccp_ops = {
985 .family = PF_INET,
986 .owner = THIS_MODULE,
987 .release = inet_release,
988 .bind = inet_bind,
989 .connect = inet_stream_connect,
990 .socketpair = sock_no_socketpair,
991 .accept = inet_accept,
992 .getname = inet_getname,
993 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
994 .poll = dccp_poll,
995 .ioctl = inet_ioctl,
996 /* FIXME: work on inet_listen to rename it to sock_common_listen */
997 .listen = inet_dccp_listen,
998 .shutdown = inet_shutdown,
999 .setsockopt = sock_common_setsockopt,
1000 .getsockopt = sock_common_getsockopt,
1001 .sendmsg = inet_sendmsg,
1002 .recvmsg = sock_common_recvmsg,
1003 .mmap = sock_no_mmap,
1004 .sendpage = sock_no_sendpage,
1005 #ifdef CONFIG_COMPAT
1006 .compat_setsockopt = compat_sock_common_setsockopt,
1007 .compat_getsockopt = compat_sock_common_getsockopt,
1008 #endif
1009 };
1010
1011 static struct inet_protosw dccp_v4_protosw = {
1012 .type = SOCK_DCCP,
1013 .protocol = IPPROTO_DCCP,
1014 .prot = &dccp_v4_prot,
1015 .ops = &inet_dccp_ops,
1016 .no_check = 0,
1017 .flags = INET_PROTOSW_ICSK,
1018 };
1019
dccp_v4_init_net(struct net * net)1020 static int __net_init dccp_v4_init_net(struct net *net)
1021 {
1022 if (dccp_hashinfo.bhash == NULL)
1023 return -ESOCKTNOSUPPORT;
1024
1025 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1026 SOCK_DCCP, IPPROTO_DCCP, net);
1027 }
1028
dccp_v4_exit_net(struct net * net)1029 static void __net_exit dccp_v4_exit_net(struct net *net)
1030 {
1031 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1032 }
1033
1034 static struct pernet_operations dccp_v4_ops = {
1035 .init = dccp_v4_init_net,
1036 .exit = dccp_v4_exit_net,
1037 };
1038
dccp_v4_init(void)1039 static int __init dccp_v4_init(void)
1040 {
1041 int err = proto_register(&dccp_v4_prot, 1);
1042
1043 if (err != 0)
1044 goto out;
1045
1046 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1047 if (err != 0)
1048 goto out_proto_unregister;
1049
1050 inet_register_protosw(&dccp_v4_protosw);
1051
1052 err = register_pernet_subsys(&dccp_v4_ops);
1053 if (err)
1054 goto out_destroy_ctl_sock;
1055 out:
1056 return err;
1057 out_destroy_ctl_sock:
1058 inet_unregister_protosw(&dccp_v4_protosw);
1059 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1060 out_proto_unregister:
1061 proto_unregister(&dccp_v4_prot);
1062 goto out;
1063 }
1064
dccp_v4_exit(void)1065 static void __exit dccp_v4_exit(void)
1066 {
1067 unregister_pernet_subsys(&dccp_v4_ops);
1068 inet_unregister_protosw(&dccp_v4_protosw);
1069 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1070 proto_unregister(&dccp_v4_prot);
1071 }
1072
1073 module_init(dccp_v4_init);
1074 module_exit(dccp_v4_exit);
1075
1076 /*
1077 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1078 * values directly, Also cover the case where the protocol is not specified,
1079 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1080 */
1081 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1082 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1083 MODULE_LICENSE("GPL");
1084 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1085 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
1086