683902fcc8ed746f431bd372a57cccdb694adb32
[linux-3.10.git] / net / dccp / ipv4.c
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
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  */
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         dst = inet_csk_update_pmtu(sk, mtu);
165         if (!dst)
166                 return;
167
168         /* Something is about to be wrong... Remember soft error
169          * for the case, if this connection will not able to recover.
170          */
171         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
172                 sk->sk_err_soft = EMSGSIZE;
173
174         mtu = dst_mtu(dst);
175
176         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
177             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
178                 dccp_sync_mss(sk, mtu);
179
180                 /*
181                  * From RFC 4340, sec. 14.1:
182                  *
183                  *      DCCP-Sync packets are the best choice for upward
184                  *      probing, since DCCP-Sync probes do not risk application
185                  *      data loss.
186                  */
187                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
188         } /* else let the usual retransmit timer handle it */
189 }
190
191 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
192 {
193         struct dst_entry *dst = __sk_dst_check(sk, 0);
194
195         if (dst)
196                 dst->ops->redirect(dst, skb);
197 }
198
199 /*
200  * This routine is called by the ICMP module when it gets some sort of error
201  * condition. If err < 0 then the socket should be closed and the error
202  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
203  * After adjustment header points to the first 8 bytes of the tcp header. We
204  * need to find the appropriate port.
205  *
206  * The locking strategy used here is very "optimistic". When someone else
207  * accesses the socket the ICMP is just dropped and for some paths there is no
208  * check at all. A more general error queue to queue errors for later handling
209  * is probably better.
210  */
211 static void dccp_v4_err(struct sk_buff *skb, u32 info)
212 {
213         const struct iphdr *iph = (struct iphdr *)skb->data;
214         const u8 offset = iph->ihl << 2;
215         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
216         struct dccp_sock *dp;
217         struct inet_sock *inet;
218         const int type = icmp_hdr(skb)->type;
219         const int code = icmp_hdr(skb)->code;
220         struct sock *sk;
221         __u64 seq;
222         int err;
223         struct net *net = dev_net(skb->dev);
224
225         if (skb->len < offset + sizeof(*dh) ||
226             skb->len < offset + __dccp_basic_hdr_len(dh)) {
227                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
228                 return;
229         }
230
231         sk = inet_lookup(net, &dccp_hashinfo,
232                         iph->daddr, dh->dccph_dport,
233                         iph->saddr, dh->dccph_sport, inet_iif(skb));
234         if (sk == NULL) {
235                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
236                 return;
237         }
238
239         if (sk->sk_state == DCCP_TIME_WAIT) {
240                 inet_twsk_put(inet_twsk(sk));
241                 return;
242         }
243
244         bh_lock_sock(sk);
245         /* If too many ICMPs get dropped on busy
246          * servers this needs to be solved differently.
247          */
248         if (sock_owned_by_user(sk))
249                 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
250
251         if (sk->sk_state == DCCP_CLOSED)
252                 goto out;
253
254         dp = dccp_sk(sk);
255         seq = dccp_hdr_seq(dh);
256         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
257             !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
258                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
259                 goto out;
260         }
261
262         switch (type) {
263         case ICMP_REDIRECT:
264                 dccp_do_redirect(skb, sk);
265                 goto out;
266         case ICMP_SOURCE_QUENCH:
267                 /* Just silently ignore these. */
268                 goto out;
269         case ICMP_PARAMETERPROB:
270                 err = EPROTO;
271                 break;
272         case ICMP_DEST_UNREACH:
273                 if (code > NR_ICMP_UNREACH)
274                         goto out;
275
276                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
277                         if (!sock_owned_by_user(sk))
278                                 dccp_do_pmtu_discovery(sk, iph, info);
279                         goto out;
280                 }
281
282                 err = icmp_err_convert[code].errno;
283                 break;
284         case ICMP_TIME_EXCEEDED:
285                 err = EHOSTUNREACH;
286                 break;
287         default:
288                 goto out;
289         }
290
291         switch (sk->sk_state) {
292                 struct request_sock *req , **prev;
293         case DCCP_LISTEN:
294                 if (sock_owned_by_user(sk))
295                         goto out;
296                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
297                                           iph->daddr, iph->saddr);
298                 if (!req)
299                         goto out;
300
301                 /*
302                  * ICMPs are not backlogged, hence we cannot get an established
303                  * socket here.
304                  */
305                 WARN_ON(req->sk);
306
307                 if (!between48(seq, dccp_rsk(req)->dreq_iss,
308                                     dccp_rsk(req)->dreq_gss)) {
309                         NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
310                         goto out;
311                 }
312                 /*
313                  * Still in RESPOND, just remove it silently.
314                  * There is no good way to pass the error to the newly
315                  * created socket, and POSIX does not want network
316                  * errors returned from accept().
317                  */
318                 inet_csk_reqsk_queue_drop(sk, req, prev);
319                 goto out;
320
321         case DCCP_REQUESTING:
322         case DCCP_RESPOND:
323                 if (!sock_owned_by_user(sk)) {
324                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
325                         sk->sk_err = err;
326
327                         sk->sk_error_report(sk);
328
329                         dccp_done(sk);
330                 } else
331                         sk->sk_err_soft = err;
332                 goto out;
333         }
334
335         /* If we've already connected we will keep trying
336          * until we time out, or the user gives up.
337          *
338          * rfc1122 4.2.3.9 allows to consider as hard errors
339          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
340          * but it is obsoleted by pmtu discovery).
341          *
342          * Note, that in modern internet, where routing is unreliable
343          * and in each dark corner broken firewalls sit, sending random
344          * errors ordered by their masters even this two messages finally lose
345          * their original sense (even Linux sends invalid PORT_UNREACHs)
346          *
347          * Now we are in compliance with RFCs.
348          *                                                      --ANK (980905)
349          */
350
351         inet = inet_sk(sk);
352         if (!sock_owned_by_user(sk) && inet->recverr) {
353                 sk->sk_err = err;
354                 sk->sk_error_report(sk);
355         } else /* Only an error on timeout */
356                 sk->sk_err_soft = err;
357 out:
358         bh_unlock_sock(sk);
359         sock_put(sk);
360 }
361
362 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
363                                       __be32 src, __be32 dst)
364 {
365         return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
366 }
367
368 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
369 {
370         const struct inet_sock *inet = inet_sk(sk);
371         struct dccp_hdr *dh = dccp_hdr(skb);
372
373         dccp_csum_outgoing(skb);
374         dh->dccph_checksum = dccp_v4_csum_finish(skb,
375                                                  inet->inet_saddr,
376                                                  inet->inet_daddr);
377 }
378
379 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
380
381 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
382 {
383         return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
384                                            ip_hdr(skb)->saddr,
385                                            dccp_hdr(skb)->dccph_dport,
386                                            dccp_hdr(skb)->dccph_sport);
387 }
388
389 /*
390  * The three way handshake has completed - we got a valid ACK or DATAACK -
391  * now create the new socket.
392  *
393  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
394  */
395 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
396                                        struct request_sock *req,
397                                        struct dst_entry *dst)
398 {
399         struct inet_request_sock *ireq;
400         struct inet_sock *newinet;
401         struct sock *newsk;
402
403         if (sk_acceptq_is_full(sk))
404                 goto exit_overflow;
405
406         newsk = dccp_create_openreq_child(sk, req, skb);
407         if (newsk == NULL)
408                 goto exit_nonewsk;
409
410         newinet            = inet_sk(newsk);
411         ireq               = inet_rsk(req);
412         newinet->inet_daddr     = ireq->rmt_addr;
413         newinet->inet_rcv_saddr = ireq->loc_addr;
414         newinet->inet_saddr     = ireq->loc_addr;
415         newinet->inet_opt       = ireq->opt;
416         ireq->opt          = NULL;
417         newinet->mc_index  = inet_iif(skb);
418         newinet->mc_ttl    = ip_hdr(skb)->ttl;
419         newinet->inet_id   = jiffies;
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         __inet_hash_nolisten(newsk, NULL);
431
432         return newsk;
433
434 exit_overflow:
435         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
436 exit_nonewsk:
437         dst_release(dst);
438 exit:
439         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
440         return NULL;
441 put_and_exit:
442         bh_unlock_sock(newsk);
443         sock_put(newsk);
444         goto exit;
445 }
446
447 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
448
449 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
450 {
451         const struct dccp_hdr *dh = dccp_hdr(skb);
452         const struct iphdr *iph = ip_hdr(skb);
453         struct sock *nsk;
454         struct request_sock **prev;
455         /* Find possible connection requests. */
456         struct request_sock *req = inet_csk_search_req(sk, &prev,
457                                                        dh->dccph_sport,
458                                                        iph->saddr, iph->daddr);
459         if (req != NULL)
460                 return dccp_check_req(sk, skb, req, prev);
461
462         nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
463                                       iph->saddr, dh->dccph_sport,
464                                       iph->daddr, dh->dccph_dport,
465                                       inet_iif(skb));
466         if (nsk != NULL) {
467                 if (nsk->sk_state != DCCP_TIME_WAIT) {
468                         bh_lock_sock(nsk);
469                         return nsk;
470                 }
471                 inet_twsk_put(inet_twsk(nsk));
472                 return NULL;
473         }
474
475         return sk;
476 }
477
478 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
479                                            struct sk_buff *skb)
480 {
481         struct rtable *rt;
482         const struct iphdr *iph = ip_hdr(skb);
483         struct flowi4 fl4 = {
484                 .flowi4_oif = skb_rtable(skb)->rt_iif,
485                 .daddr = iph->saddr,
486                 .saddr = iph->daddr,
487                 .flowi4_tos = RT_CONN_FLAGS(sk),
488                 .flowi4_proto = sk->sk_protocol,
489                 .fl4_sport = dccp_hdr(skb)->dccph_dport,
490                 .fl4_dport = dccp_hdr(skb)->dccph_sport,
491         };
492
493         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
494         rt = ip_route_output_flow(net, &fl4, sk);
495         if (IS_ERR(rt)) {
496                 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
497                 return NULL;
498         }
499
500         return &rt->dst;
501 }
502
503 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
504                                  struct request_values *rv_unused)
505 {
506         int err = -1;
507         struct sk_buff *skb;
508         struct dst_entry *dst;
509         struct flowi4 fl4;
510
511         dst = inet_csk_route_req(sk, &fl4, req, false);
512         if (dst == NULL)
513                 goto out;
514
515         skb = dccp_make_response(sk, dst, req);
516         if (skb != NULL) {
517                 const struct inet_request_sock *ireq = inet_rsk(req);
518                 struct dccp_hdr *dh = dccp_hdr(skb);
519
520                 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
521                                                               ireq->rmt_addr);
522                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
523                                             ireq->rmt_addr,
524                                             ireq->opt);
525                 err = net_xmit_eval(err);
526         }
527
528 out:
529         dst_release(dst);
530         return err;
531 }
532
533 static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
534 {
535         int err;
536         const struct iphdr *rxiph;
537         struct sk_buff *skb;
538         struct dst_entry *dst;
539         struct net *net = dev_net(skb_dst(rxskb)->dev);
540         struct sock *ctl_sk = net->dccp.v4_ctl_sk;
541
542         /* Never send a reset in response to a reset. */
543         if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
544                 return;
545
546         if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
547                 return;
548
549         dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
550         if (dst == NULL)
551                 return;
552
553         skb = dccp_ctl_make_reset(ctl_sk, rxskb);
554         if (skb == NULL)
555                 goto out;
556
557         rxiph = ip_hdr(rxskb);
558         dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
559                                                                  rxiph->daddr);
560         skb_dst_set(skb, dst_clone(dst));
561
562         bh_lock_sock(ctl_sk);
563         err = ip_build_and_send_pkt(skb, ctl_sk,
564                                     rxiph->daddr, rxiph->saddr, NULL);
565         bh_unlock_sock(ctl_sk);
566
567         if (net_xmit_eval(err) == 0) {
568                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
569                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
570         }
571 out:
572          dst_release(dst);
573 }
574
575 static void dccp_v4_reqsk_destructor(struct request_sock *req)
576 {
577         dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
578         kfree(inet_rsk(req)->opt);
579 }
580
581 void dccp_syn_ack_timeout(struct sock *sk, struct request_sock *req)
582 {
583 }
584 EXPORT_SYMBOL(dccp_syn_ack_timeout);
585
586 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
587         .family         = PF_INET,
588         .obj_size       = sizeof(struct dccp_request_sock),
589         .rtx_syn_ack    = dccp_v4_send_response,
590         .send_ack       = dccp_reqsk_send_ack,
591         .destructor     = dccp_v4_reqsk_destructor,
592         .send_reset     = dccp_v4_ctl_send_reset,
593         .syn_ack_timeout = dccp_syn_ack_timeout,
594 };
595
596 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
597 {
598         struct inet_request_sock *ireq;
599         struct request_sock *req;
600         struct dccp_request_sock *dreq;
601         const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
602         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
603
604         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
605         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
606                 return 0;       /* discard, don't send a reset here */
607
608         if (dccp_bad_service_code(sk, service)) {
609                 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
610                 goto drop;
611         }
612         /*
613          * TW buckets are converted to open requests without
614          * limitations, they conserve resources and peer is
615          * evidently real one.
616          */
617         dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
618         if (inet_csk_reqsk_queue_is_full(sk))
619                 goto drop;
620
621         /*
622          * Accept backlog is full. If we have already queued enough
623          * of warm entries in syn queue, drop request. It is better than
624          * clogging syn queue with openreqs with exponentially increasing
625          * timeout.
626          */
627         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
628                 goto drop;
629
630         req = inet_reqsk_alloc(&dccp_request_sock_ops);
631         if (req == NULL)
632                 goto drop;
633
634         if (dccp_reqsk_init(req, dccp_sk(sk), skb))
635                 goto drop_and_free;
636
637         dreq = dccp_rsk(req);
638         if (dccp_parse_options(sk, dreq, skb))
639                 goto drop_and_free;
640
641         if (security_inet_conn_request(sk, skb, req))
642                 goto drop_and_free;
643
644         ireq = inet_rsk(req);
645         ireq->loc_addr = ip_hdr(skb)->daddr;
646         ireq->rmt_addr = ip_hdr(skb)->saddr;
647
648         /*
649          * Step 3: Process LISTEN state
650          *
651          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
652          *
653          * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
654          */
655         dreq->dreq_isr     = dcb->dccpd_seq;
656         dreq->dreq_gsr     = dreq->dreq_isr;
657         dreq->dreq_iss     = dccp_v4_init_sequence(skb);
658         dreq->dreq_gss     = dreq->dreq_iss;
659         dreq->dreq_service = service;
660
661         if (dccp_v4_send_response(sk, req, NULL))
662                 goto drop_and_free;
663
664         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
665         return 0;
666
667 drop_and_free:
668         reqsk_free(req);
669 drop:
670         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
671         return -1;
672 }
673
674 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
675
676 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
677 {
678         struct dccp_hdr *dh = dccp_hdr(skb);
679
680         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
681                 if (dccp_rcv_established(sk, skb, dh, skb->len))
682                         goto reset;
683                 return 0;
684         }
685
686         /*
687          *  Step 3: Process LISTEN state
688          *       If P.type == Request or P contains a valid Init Cookie option,
689          *            (* Must scan the packet's options to check for Init
690          *               Cookies.  Only Init Cookies are processed here,
691          *               however; other options are processed in Step 8.  This
692          *               scan need only be performed if the endpoint uses Init
693          *               Cookies *)
694          *            (* Generate a new socket and switch to that socket *)
695          *            Set S := new socket for this port pair
696          *            S.state = RESPOND
697          *            Choose S.ISS (initial seqno) or set from Init Cookies
698          *            Initialize S.GAR := S.ISS
699          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
700          *            Continue with S.state == RESPOND
701          *            (* A Response packet will be generated in Step 11 *)
702          *       Otherwise,
703          *            Generate Reset(No Connection) unless P.type == Reset
704          *            Drop packet and return
705          *
706          * NOTE: the check for the packet types is done in
707          *       dccp_rcv_state_process
708          */
709         if (sk->sk_state == DCCP_LISTEN) {
710                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
711
712                 if (nsk == NULL)
713                         goto discard;
714
715                 if (nsk != sk) {
716                         if (dccp_child_process(sk, nsk, skb))
717                                 goto reset;
718                         return 0;
719                 }
720         }
721
722         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
723                 goto reset;
724         return 0;
725
726 reset:
727         dccp_v4_ctl_send_reset(sk, skb);
728 discard:
729         kfree_skb(skb);
730         return 0;
731 }
732
733 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
734
735 /**
736  *      dccp_invalid_packet  -  check for malformed packets
737  *      Implements RFC 4340, 8.5:  Step 1: Check header basics
738  *      Packets that fail these checks are ignored and do not receive Resets.
739  */
740 int dccp_invalid_packet(struct sk_buff *skb)
741 {
742         const struct dccp_hdr *dh;
743         unsigned int cscov;
744
745         if (skb->pkt_type != PACKET_HOST)
746                 return 1;
747
748         /* If the packet is shorter than 12 bytes, drop packet and return */
749         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
750                 DCCP_WARN("pskb_may_pull failed\n");
751                 return 1;
752         }
753
754         dh = dccp_hdr(skb);
755
756         /* If P.type is not understood, drop packet and return */
757         if (dh->dccph_type >= DCCP_PKT_INVALID) {
758                 DCCP_WARN("invalid packet type\n");
759                 return 1;
760         }
761
762         /*
763          * If P.Data Offset is too small for packet type, drop packet and return
764          */
765         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
766                 DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
767                 return 1;
768         }
769         /*
770          * If P.Data Offset is too too large for packet, drop packet and return
771          */
772         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
773                 DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
774                 return 1;
775         }
776
777         /*
778          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
779          * has short sequence numbers), drop packet and return
780          */
781         if ((dh->dccph_type < DCCP_PKT_DATA    ||
782             dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
783                 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
784                           dccp_packet_name(dh->dccph_type));
785                 return 1;
786         }
787
788         /*
789          * If P.CsCov is too large for the packet size, drop packet and return.
790          * This must come _before_ checksumming (not as RFC 4340 suggests).
791          */
792         cscov = dccp_csum_coverage(skb);
793         if (cscov > skb->len) {
794                 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
795                           dh->dccph_cscov, skb->len);
796                 return 1;
797         }
798
799         /* If header checksum is incorrect, drop packet and return.
800          * (This step is completed in the AF-dependent functions.) */
801         skb->csum = skb_checksum(skb, 0, cscov, 0);
802
803         return 0;
804 }
805
806 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
807
808 /* this is called when real data arrives */
809 static int dccp_v4_rcv(struct sk_buff *skb)
810 {
811         const struct dccp_hdr *dh;
812         const struct iphdr *iph;
813         struct sock *sk;
814         int min_cov;
815
816         /* Step 1: Check header basics */
817
818         if (dccp_invalid_packet(skb))
819                 goto discard_it;
820
821         iph = ip_hdr(skb);
822         /* Step 1: If header checksum is incorrect, drop packet and return */
823         if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
824                 DCCP_WARN("dropped packet with invalid checksum\n");
825                 goto discard_it;
826         }
827
828         dh = dccp_hdr(skb);
829
830         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
831         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
832
833         dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
834                       dccp_packet_name(dh->dccph_type),
835                       &iph->saddr, ntohs(dh->dccph_sport),
836                       &iph->daddr, ntohs(dh->dccph_dport),
837                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
838
839         if (dccp_packet_without_ack(skb)) {
840                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
841                 dccp_pr_debug_cat("\n");
842         } else {
843                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
844                 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
845                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
846         }
847
848         /* Step 2:
849          *      Look up flow ID in table and get corresponding socket */
850         sk = __inet_lookup_skb(&dccp_hashinfo, skb,
851                                dh->dccph_sport, dh->dccph_dport);
852         /*
853          * Step 2:
854          *      If no socket ...
855          */
856         if (sk == NULL) {
857                 dccp_pr_debug("failed to look up flow ID in table and "
858                               "get corresponding socket\n");
859                 goto no_dccp_socket;
860         }
861
862         /*
863          * Step 2:
864          *      ... or S.state == TIMEWAIT,
865          *              Generate Reset(No Connection) unless P.type == Reset
866          *              Drop packet and return
867          */
868         if (sk->sk_state == DCCP_TIME_WAIT) {
869                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
870                 inet_twsk_put(inet_twsk(sk));
871                 goto no_dccp_socket;
872         }
873
874         /*
875          * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
876          *      o if MinCsCov = 0, only packets with CsCov = 0 are accepted
877          *      o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
878          */
879         min_cov = dccp_sk(sk)->dccps_pcrlen;
880         if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov))  {
881                 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
882                               dh->dccph_cscov, min_cov);
883                 /* FIXME: "Such packets SHOULD be reported using Data Dropped
884                  *         options (Section 11.7) with Drop Code 0, Protocol
885                  *         Constraints."                                     */
886                 goto discard_and_relse;
887         }
888
889         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
890                 goto discard_and_relse;
891         nf_reset(skb);
892
893         return sk_receive_skb(sk, skb, 1);
894
895 no_dccp_socket:
896         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
897                 goto discard_it;
898         /*
899          * Step 2:
900          *      If no socket ...
901          *              Generate Reset(No Connection) unless P.type == Reset
902          *              Drop packet and return
903          */
904         if (dh->dccph_type != DCCP_PKT_RESET) {
905                 DCCP_SKB_CB(skb)->dccpd_reset_code =
906                                         DCCP_RESET_CODE_NO_CONNECTION;
907                 dccp_v4_ctl_send_reset(sk, skb);
908         }
909
910 discard_it:
911         kfree_skb(skb);
912         return 0;
913
914 discard_and_relse:
915         sock_put(sk);
916         goto discard_it;
917 }
918
919 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
920         .queue_xmit        = ip_queue_xmit,
921         .send_check        = dccp_v4_send_check,
922         .rebuild_header    = inet_sk_rebuild_header,
923         .conn_request      = dccp_v4_conn_request,
924         .syn_recv_sock     = dccp_v4_request_recv_sock,
925         .net_header_len    = sizeof(struct iphdr),
926         .setsockopt        = ip_setsockopt,
927         .getsockopt        = ip_getsockopt,
928         .addr2sockaddr     = inet_csk_addr2sockaddr,
929         .sockaddr_len      = sizeof(struct sockaddr_in),
930         .bind_conflict     = inet_csk_bind_conflict,
931 #ifdef CONFIG_COMPAT
932         .compat_setsockopt = compat_ip_setsockopt,
933         .compat_getsockopt = compat_ip_getsockopt,
934 #endif
935 };
936
937 static int dccp_v4_init_sock(struct sock *sk)
938 {
939         static __u8 dccp_v4_ctl_sock_initialized;
940         int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
941
942         if (err == 0) {
943                 if (unlikely(!dccp_v4_ctl_sock_initialized))
944                         dccp_v4_ctl_sock_initialized = 1;
945                 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
946         }
947
948         return err;
949 }
950
951 static struct timewait_sock_ops dccp_timewait_sock_ops = {
952         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
953 };
954
955 static struct proto dccp_v4_prot = {
956         .name                   = "DCCP",
957         .owner                  = THIS_MODULE,
958         .close                  = dccp_close,
959         .connect                = dccp_v4_connect,
960         .disconnect             = dccp_disconnect,
961         .ioctl                  = dccp_ioctl,
962         .init                   = dccp_v4_init_sock,
963         .setsockopt             = dccp_setsockopt,
964         .getsockopt             = dccp_getsockopt,
965         .sendmsg                = dccp_sendmsg,
966         .recvmsg                = dccp_recvmsg,
967         .backlog_rcv            = dccp_v4_do_rcv,
968         .hash                   = inet_hash,
969         .unhash                 = inet_unhash,
970         .accept                 = inet_csk_accept,
971         .get_port               = inet_csk_get_port,
972         .shutdown               = dccp_shutdown,
973         .destroy                = dccp_destroy_sock,
974         .orphan_count           = &dccp_orphan_count,
975         .max_header             = MAX_DCCP_HEADER,
976         .obj_size               = sizeof(struct dccp_sock),
977         .slab_flags             = SLAB_DESTROY_BY_RCU,
978         .rsk_prot               = &dccp_request_sock_ops,
979         .twsk_prot              = &dccp_timewait_sock_ops,
980         .h.hashinfo             = &dccp_hashinfo,
981 #ifdef CONFIG_COMPAT
982         .compat_setsockopt      = compat_dccp_setsockopt,
983         .compat_getsockopt      = compat_dccp_getsockopt,
984 #endif
985 };
986
987 static const struct net_protocol dccp_v4_protocol = {
988         .handler        = dccp_v4_rcv,
989         .err_handler    = dccp_v4_err,
990         .no_policy      = 1,
991         .netns_ok       = 1,
992 };
993
994 static const struct proto_ops inet_dccp_ops = {
995         .family            = PF_INET,
996         .owner             = THIS_MODULE,
997         .release           = inet_release,
998         .bind              = inet_bind,
999         .connect           = inet_stream_connect,
1000         .socketpair        = sock_no_socketpair,
1001         .accept            = inet_accept,
1002         .getname           = inet_getname,
1003         /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
1004         .poll              = dccp_poll,
1005         .ioctl             = inet_ioctl,
1006         /* FIXME: work on inet_listen to rename it to sock_common_listen */
1007         .listen            = inet_dccp_listen,
1008         .shutdown          = inet_shutdown,
1009         .setsockopt        = sock_common_setsockopt,
1010         .getsockopt        = sock_common_getsockopt,
1011         .sendmsg           = inet_sendmsg,
1012         .recvmsg           = sock_common_recvmsg,
1013         .mmap              = sock_no_mmap,
1014         .sendpage          = sock_no_sendpage,
1015 #ifdef CONFIG_COMPAT
1016         .compat_setsockopt = compat_sock_common_setsockopt,
1017         .compat_getsockopt = compat_sock_common_getsockopt,
1018 #endif
1019 };
1020
1021 static struct inet_protosw dccp_v4_protosw = {
1022         .type           = SOCK_DCCP,
1023         .protocol       = IPPROTO_DCCP,
1024         .prot           = &dccp_v4_prot,
1025         .ops            = &inet_dccp_ops,
1026         .no_check       = 0,
1027         .flags          = INET_PROTOSW_ICSK,
1028 };
1029
1030 static int __net_init dccp_v4_init_net(struct net *net)
1031 {
1032         if (dccp_hashinfo.bhash == NULL)
1033                 return -ESOCKTNOSUPPORT;
1034
1035         return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1036                                     SOCK_DCCP, IPPROTO_DCCP, net);
1037 }
1038
1039 static void __net_exit dccp_v4_exit_net(struct net *net)
1040 {
1041         inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1042 }
1043
1044 static struct pernet_operations dccp_v4_ops = {
1045         .init   = dccp_v4_init_net,
1046         .exit   = dccp_v4_exit_net,
1047 };
1048
1049 static int __init dccp_v4_init(void)
1050 {
1051         int err = proto_register(&dccp_v4_prot, 1);
1052
1053         if (err != 0)
1054                 goto out;
1055
1056         err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1057         if (err != 0)
1058                 goto out_proto_unregister;
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 out:
1066         return err;
1067 out_destroy_ctl_sock:
1068         inet_unregister_protosw(&dccp_v4_protosw);
1069         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1070 out_proto_unregister:
1071         proto_unregister(&dccp_v4_prot);
1072         goto out;
1073 }
1074
1075 static void __exit dccp_v4_exit(void)
1076 {
1077         unregister_pernet_subsys(&dccp_v4_ops);
1078         inet_unregister_protosw(&dccp_v4_protosw);
1079         inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1080         proto_unregister(&dccp_v4_prot);
1081 }
1082
1083 module_init(dccp_v4_init);
1084 module_exit(dccp_v4_exit);
1085
1086 /*
1087  * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1088  * values directly, Also cover the case where the protocol is not specified,
1089  * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1090  */
1091 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1092 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1093 MODULE_LICENSE("GPL");
1094 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1095 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");