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
dccp_v4_connect(struct sock * sk,struct sockaddr * uaddr,int addr_len)38 int 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;
126 out:
127 return err;
128 failure:
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 }
138 EXPORT_SYMBOL_GPL(dccp_v4_connect);
139
140 /*
141 * This routine does path mtu discovery as defined in RFC1191.
142 */
dccp_do_pmtu_discovery(struct sock * sk,const struct iphdr * iph,u32 mtu)143 static 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
dccp_do_redirect(struct sk_buff * skb,struct sock * sk)186 static 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
dccp_req_err(struct sock * sk,u64 seq)194 void 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 }
216 EXPORT_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 */
dccp_v4_err(struct sk_buff * skb,u32 info)230 static 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;
355 out:
356 bh_unlock_sock(sk);
357 sock_put(sk);
358 return 0;
359 }
360
dccp_v4_csum_finish(struct sk_buff * skb,__be32 src,__be32 dst)361 static 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
dccp_v4_send_check(struct sock * sk,struct sk_buff * skb)367 void 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 }
377 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
378
dccp_v4_init_sequence(const struct sk_buff * skb)379 static 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 */
dccp_v4_request_recv_sock(const struct sock * sk,struct sk_buff * skb,struct request_sock * req,struct dst_entry * dst,struct request_sock * req_unhash,bool * own_req)393 struct 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), NULL);
431 if (*own_req)
432 ireq->ireq_opt = NULL;
433 else
434 newinet->inet_opt = NULL;
435 return newsk;
436
437 exit_overflow:
438 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
439 exit_nonewsk:
440 dst_release(dst);
441 exit:
442 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
443 return NULL;
444 put_and_exit:
445 newinet->inet_opt = NULL;
446 inet_csk_prepare_forced_close(newsk);
447 dccp_done(newsk);
448 goto exit;
449 }
450 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
451
dccp_v4_route_skb(struct net * net,struct sock * sk,struct sk_buff * skb)452 static 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
dccp_v4_send_response(const struct sock * sk,struct request_sock * req)477 static 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 inet_sk(sk)->tos);
500 rcu_read_unlock();
501 err = net_xmit_eval(err);
502 }
503
504 out:
505 dst_release(dst);
506 return err;
507 }
508
dccp_v4_ctl_send_reset(const struct sock * sk,struct sk_buff * rxskb)509 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
510 {
511 int err;
512 const struct iphdr *rxiph;
513 struct sk_buff *skb;
514 struct dst_entry *dst;
515 struct net *net = dev_net(skb_dst(rxskb)->dev);
516 struct sock *ctl_sk = net->dccp.v4_ctl_sk;
517
518 /* Never send a reset in response to a reset. */
519 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
520 return;
521
522 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
523 return;
524
525 dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
526 if (dst == NULL)
527 return;
528
529 skb = dccp_ctl_make_reset(ctl_sk, rxskb);
530 if (skb == NULL)
531 goto out;
532
533 rxiph = ip_hdr(rxskb);
534 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
535 rxiph->daddr);
536 skb_dst_set(skb, dst_clone(dst));
537
538 local_bh_disable();
539 bh_lock_sock(ctl_sk);
540 err = ip_build_and_send_pkt(skb, ctl_sk,
541 rxiph->daddr, rxiph->saddr, NULL,
542 inet_sk(ctl_sk)->tos);
543 bh_unlock_sock(ctl_sk);
544
545 if (net_xmit_eval(err) == 0) {
546 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
547 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
548 }
549 local_bh_enable();
550 out:
551 dst_release(dst);
552 }
553
dccp_v4_reqsk_destructor(struct request_sock * req)554 static void dccp_v4_reqsk_destructor(struct request_sock *req)
555 {
556 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
557 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1));
558 }
559
dccp_syn_ack_timeout(const struct request_sock * req)560 void dccp_syn_ack_timeout(const struct request_sock *req)
561 {
562 }
563 EXPORT_SYMBOL(dccp_syn_ack_timeout);
564
565 static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
566 .family = PF_INET,
567 .obj_size = sizeof(struct dccp_request_sock),
568 .rtx_syn_ack = dccp_v4_send_response,
569 .send_ack = dccp_reqsk_send_ack,
570 .destructor = dccp_v4_reqsk_destructor,
571 .send_reset = dccp_v4_ctl_send_reset,
572 .syn_ack_timeout = dccp_syn_ack_timeout,
573 };
574
dccp_v4_conn_request(struct sock * sk,struct sk_buff * skb)575 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
576 {
577 struct inet_request_sock *ireq;
578 struct request_sock *req;
579 struct dccp_request_sock *dreq;
580 const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
581 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
582
583 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
584 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
585 return 0; /* discard, don't send a reset here */
586
587 if (dccp_bad_service_code(sk, service)) {
588 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
589 goto drop;
590 }
591 /*
592 * TW buckets are converted to open requests without
593 * limitations, they conserve resources and peer is
594 * evidently real one.
595 */
596 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
597 if (inet_csk_reqsk_queue_is_full(sk))
598 goto drop;
599
600 if (sk_acceptq_is_full(sk))
601 goto drop;
602
603 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true);
604 if (req == NULL)
605 goto drop;
606
607 if (dccp_reqsk_init(req, dccp_sk(sk), skb))
608 goto drop_and_free;
609
610 dreq = dccp_rsk(req);
611 if (dccp_parse_options(sk, dreq, skb))
612 goto drop_and_free;
613
614 if (security_inet_conn_request(sk, skb, req))
615 goto drop_and_free;
616
617 ireq = inet_rsk(req);
618 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
619 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
620 ireq->ir_mark = inet_request_mark(sk, skb);
621 ireq->ireq_family = AF_INET;
622 ireq->ir_iif = sk->sk_bound_dev_if;
623
624 /*
625 * Step 3: Process LISTEN state
626 *
627 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
628 *
629 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
630 */
631 dreq->dreq_isr = dcb->dccpd_seq;
632 dreq->dreq_gsr = dreq->dreq_isr;
633 dreq->dreq_iss = dccp_v4_init_sequence(skb);
634 dreq->dreq_gss = dreq->dreq_iss;
635 dreq->dreq_service = service;
636
637 if (dccp_v4_send_response(sk, req))
638 goto drop_and_free;
639
640 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
641 reqsk_put(req);
642 return 0;
643
644 drop_and_free:
645 reqsk_free(req);
646 drop:
647 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
648 return -1;
649 }
650 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
651
dccp_v4_do_rcv(struct sock * sk,struct sk_buff * skb)652 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
653 {
654 struct dccp_hdr *dh = dccp_hdr(skb);
655
656 if (sk->sk_state == DCCP_OPEN) { /* Fast path */
657 if (dccp_rcv_established(sk, skb, dh, skb->len))
658 goto reset;
659 return 0;
660 }
661
662 /*
663 * Step 3: Process LISTEN state
664 * If P.type == Request or P contains a valid Init Cookie option,
665 * (* Must scan the packet's options to check for Init
666 * Cookies. Only Init Cookies are processed here,
667 * however; other options are processed in Step 8. This
668 * scan need only be performed if the endpoint uses Init
669 * Cookies *)
670 * (* Generate a new socket and switch to that socket *)
671 * Set S := new socket for this port pair
672 * S.state = RESPOND
673 * Choose S.ISS (initial seqno) or set from Init Cookies
674 * Initialize S.GAR := S.ISS
675 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
676 * Continue with S.state == RESPOND
677 * (* A Response packet will be generated in Step 11 *)
678 * Otherwise,
679 * Generate Reset(No Connection) unless P.type == Reset
680 * Drop packet and return
681 *
682 * NOTE: the check for the packet types is done in
683 * dccp_rcv_state_process
684 */
685
686 if (dccp_rcv_state_process(sk, skb, dh, skb->len))
687 goto reset;
688 return 0;
689
690 reset:
691 dccp_v4_ctl_send_reset(sk, skb);
692 kfree_skb(skb);
693 return 0;
694 }
695 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
696
697 /**
698 * dccp_invalid_packet - check for malformed packets
699 * @skb: Packet to validate
700 *
701 * Implements RFC 4340, 8.5: Step 1: Check header basics
702 * Packets that fail these checks are ignored and do not receive Resets.
703 */
dccp_invalid_packet(struct sk_buff * skb)704 int dccp_invalid_packet(struct sk_buff *skb)
705 {
706 const struct dccp_hdr *dh;
707 unsigned int cscov;
708 u8 dccph_doff;
709
710 if (skb->pkt_type != PACKET_HOST)
711 return 1;
712
713 /* If the packet is shorter than 12 bytes, drop packet and return */
714 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
715 DCCP_WARN("pskb_may_pull failed\n");
716 return 1;
717 }
718
719 dh = dccp_hdr(skb);
720
721 /* If P.type is not understood, drop packet and return */
722 if (dh->dccph_type >= DCCP_PKT_INVALID) {
723 DCCP_WARN("invalid packet type\n");
724 return 1;
725 }
726
727 /*
728 * If P.Data Offset is too small for packet type, drop packet and return
729 */
730 dccph_doff = dh->dccph_doff;
731 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
732 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
733 return 1;
734 }
735 /*
736 * If P.Data Offset is too large for packet, drop packet and return
737 */
738 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
739 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
740 return 1;
741 }
742 dh = dccp_hdr(skb);
743 /*
744 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
745 * has short sequence numbers), drop packet and return
746 */
747 if ((dh->dccph_type < DCCP_PKT_DATA ||
748 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
749 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
750 dccp_packet_name(dh->dccph_type));
751 return 1;
752 }
753
754 /*
755 * If P.CsCov is too large for the packet size, drop packet and return.
756 * This must come _before_ checksumming (not as RFC 4340 suggests).
757 */
758 cscov = dccp_csum_coverage(skb);
759 if (cscov > skb->len) {
760 DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
761 dh->dccph_cscov, skb->len);
762 return 1;
763 }
764
765 /* If header checksum is incorrect, drop packet and return.
766 * (This step is completed in the AF-dependent functions.) */
767 skb->csum = skb_checksum(skb, 0, cscov, 0);
768
769 return 0;
770 }
771 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
772
773 /* this is called when real data arrives */
dccp_v4_rcv(struct sk_buff * skb)774 static int dccp_v4_rcv(struct sk_buff *skb)
775 {
776 const struct dccp_hdr *dh;
777 const struct iphdr *iph;
778 bool refcounted;
779 struct sock *sk;
780 int min_cov;
781
782 /* Step 1: Check header basics */
783
784 if (dccp_invalid_packet(skb))
785 goto discard_it;
786
787 iph = ip_hdr(skb);
788 /* Step 1: If header checksum is incorrect, drop packet and return */
789 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
790 DCCP_WARN("dropped packet with invalid checksum\n");
791 goto discard_it;
792 }
793
794 dh = dccp_hdr(skb);
795
796 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
797 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
798
799 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
800 dccp_packet_name(dh->dccph_type),
801 &iph->saddr, ntohs(dh->dccph_sport),
802 &iph->daddr, ntohs(dh->dccph_dport),
803 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
804
805 if (dccp_packet_without_ack(skb)) {
806 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
807 dccp_pr_debug_cat("\n");
808 } else {
809 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
810 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
811 DCCP_SKB_CB(skb)->dccpd_ack_seq);
812 }
813
814 lookup:
815 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
816 dh->dccph_sport, dh->dccph_dport, 0, &refcounted);
817 if (!sk) {
818 dccp_pr_debug("failed to look up flow ID in table and "
819 "get corresponding socket\n");
820 goto no_dccp_socket;
821 }
822
823 /*
824 * Step 2:
825 * ... or S.state == TIMEWAIT,
826 * Generate Reset(No Connection) unless P.type == Reset
827 * Drop packet and return
828 */
829 if (sk->sk_state == DCCP_TIME_WAIT) {
830 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
831 inet_twsk_put(inet_twsk(sk));
832 goto no_dccp_socket;
833 }
834
835 if (sk->sk_state == DCCP_NEW_SYN_RECV) {
836 struct request_sock *req = inet_reqsk(sk);
837 struct sock *nsk;
838
839 sk = req->rsk_listener;
840 if (unlikely(sk->sk_state != DCCP_LISTEN)) {
841 inet_csk_reqsk_queue_drop_and_put(sk, req);
842 goto lookup;
843 }
844 sock_hold(sk);
845 refcounted = true;
846 nsk = dccp_check_req(sk, skb, req);
847 if (!nsk) {
848 reqsk_put(req);
849 goto discard_and_relse;
850 }
851 if (nsk == sk) {
852 reqsk_put(req);
853 } else if (dccp_child_process(sk, nsk, skb)) {
854 dccp_v4_ctl_send_reset(sk, skb);
855 goto discard_and_relse;
856 } else {
857 sock_put(sk);
858 return 0;
859 }
860 }
861 /*
862 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
863 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
864 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
865 */
866 min_cov = dccp_sk(sk)->dccps_pcrlen;
867 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
868 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
869 dh->dccph_cscov, min_cov);
870 /* FIXME: "Such packets SHOULD be reported using Data Dropped
871 * options (Section 11.7) with Drop Code 0, Protocol
872 * Constraints." */
873 goto discard_and_relse;
874 }
875
876 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
877 goto discard_and_relse;
878 nf_reset_ct(skb);
879
880 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted);
881
882 no_dccp_socket:
883 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
884 goto discard_it;
885 /*
886 * Step 2:
887 * If no socket ...
888 * Generate Reset(No Connection) unless P.type == Reset
889 * Drop packet and return
890 */
891 if (dh->dccph_type != DCCP_PKT_RESET) {
892 DCCP_SKB_CB(skb)->dccpd_reset_code =
893 DCCP_RESET_CODE_NO_CONNECTION;
894 dccp_v4_ctl_send_reset(sk, skb);
895 }
896
897 discard_it:
898 kfree_skb(skb);
899 return 0;
900
901 discard_and_relse:
902 if (refcounted)
903 sock_put(sk);
904 goto discard_it;
905 }
906
907 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
908 .queue_xmit = ip_queue_xmit,
909 .send_check = dccp_v4_send_check,
910 .rebuild_header = inet_sk_rebuild_header,
911 .conn_request = dccp_v4_conn_request,
912 .syn_recv_sock = dccp_v4_request_recv_sock,
913 .net_header_len = sizeof(struct iphdr),
914 .setsockopt = ip_setsockopt,
915 .getsockopt = ip_getsockopt,
916 .addr2sockaddr = inet_csk_addr2sockaddr,
917 .sockaddr_len = sizeof(struct sockaddr_in),
918 };
919
dccp_v4_init_sock(struct sock * sk)920 static int dccp_v4_init_sock(struct sock *sk)
921 {
922 static __u8 dccp_v4_ctl_sock_initialized;
923 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
924
925 if (err == 0) {
926 if (unlikely(!dccp_v4_ctl_sock_initialized))
927 dccp_v4_ctl_sock_initialized = 1;
928 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
929 }
930
931 return err;
932 }
933
934 static struct timewait_sock_ops dccp_timewait_sock_ops = {
935 .twsk_obj_size = sizeof(struct inet_timewait_sock),
936 };
937
938 static struct proto dccp_v4_prot = {
939 .name = "DCCP",
940 .owner = THIS_MODULE,
941 .close = dccp_close,
942 .connect = dccp_v4_connect,
943 .disconnect = dccp_disconnect,
944 .ioctl = dccp_ioctl,
945 .init = dccp_v4_init_sock,
946 .setsockopt = dccp_setsockopt,
947 .getsockopt = dccp_getsockopt,
948 .sendmsg = dccp_sendmsg,
949 .recvmsg = dccp_recvmsg,
950 .backlog_rcv = dccp_v4_do_rcv,
951 .hash = inet_hash,
952 .unhash = inet_unhash,
953 .accept = inet_csk_accept,
954 .get_port = inet_csk_get_port,
955 .shutdown = dccp_shutdown,
956 .destroy = dccp_destroy_sock,
957 .orphan_count = &dccp_orphan_count,
958 .max_header = MAX_DCCP_HEADER,
959 .obj_size = sizeof(struct dccp_sock),
960 .slab_flags = SLAB_TYPESAFE_BY_RCU,
961 .rsk_prot = &dccp_request_sock_ops,
962 .twsk_prot = &dccp_timewait_sock_ops,
963 .h.hashinfo = &dccp_hashinfo,
964 };
965
966 static const struct net_protocol dccp_v4_protocol = {
967 .handler = dccp_v4_rcv,
968 .err_handler = dccp_v4_err,
969 .no_policy = 1,
970 .netns_ok = 1,
971 .icmp_strict_tag_validation = 1,
972 };
973
974 static const struct proto_ops inet_dccp_ops = {
975 .family = PF_INET,
976 .owner = THIS_MODULE,
977 .release = inet_release,
978 .bind = inet_bind,
979 .connect = inet_stream_connect,
980 .socketpair = sock_no_socketpair,
981 .accept = inet_accept,
982 .getname = inet_getname,
983 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */
984 .poll = dccp_poll,
985 .ioctl = inet_ioctl,
986 .gettstamp = sock_gettstamp,
987 /* FIXME: work on inet_listen to rename it to sock_common_listen */
988 .listen = inet_dccp_listen,
989 .shutdown = inet_shutdown,
990 .setsockopt = sock_common_setsockopt,
991 .getsockopt = sock_common_getsockopt,
992 .sendmsg = inet_sendmsg,
993 .recvmsg = sock_common_recvmsg,
994 .mmap = sock_no_mmap,
995 .sendpage = sock_no_sendpage,
996 };
997
998 static struct inet_protosw dccp_v4_protosw = {
999 .type = SOCK_DCCP,
1000 .protocol = IPPROTO_DCCP,
1001 .prot = &dccp_v4_prot,
1002 .ops = &inet_dccp_ops,
1003 .flags = INET_PROTOSW_ICSK,
1004 };
1005
dccp_v4_init_net(struct net * net)1006 static int __net_init dccp_v4_init_net(struct net *net)
1007 {
1008 if (dccp_hashinfo.bhash == NULL)
1009 return -ESOCKTNOSUPPORT;
1010
1011 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
1012 SOCK_DCCP, IPPROTO_DCCP, net);
1013 }
1014
dccp_v4_exit_net(struct net * net)1015 static void __net_exit dccp_v4_exit_net(struct net *net)
1016 {
1017 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
1018 }
1019
dccp_v4_exit_batch(struct list_head * net_exit_list)1020 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
1021 {
1022 inet_twsk_purge(&dccp_hashinfo, AF_INET);
1023 }
1024
1025 static struct pernet_operations dccp_v4_ops = {
1026 .init = dccp_v4_init_net,
1027 .exit = dccp_v4_exit_net,
1028 .exit_batch = dccp_v4_exit_batch,
1029 };
1030
dccp_v4_init(void)1031 static int __init dccp_v4_init(void)
1032 {
1033 int err = proto_register(&dccp_v4_prot, 1);
1034
1035 if (err)
1036 goto out;
1037
1038 inet_register_protosw(&dccp_v4_protosw);
1039
1040 err = register_pernet_subsys(&dccp_v4_ops);
1041 if (err)
1042 goto out_destroy_ctl_sock;
1043
1044 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1045 if (err)
1046 goto out_proto_unregister;
1047
1048 out:
1049 return err;
1050 out_proto_unregister:
1051 unregister_pernet_subsys(&dccp_v4_ops);
1052 out_destroy_ctl_sock:
1053 inet_unregister_protosw(&dccp_v4_protosw);
1054 proto_unregister(&dccp_v4_prot);
1055 goto out;
1056 }
1057
dccp_v4_exit(void)1058 static void __exit dccp_v4_exit(void)
1059 {
1060 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
1061 unregister_pernet_subsys(&dccp_v4_ops);
1062 inet_unregister_protosw(&dccp_v4_protosw);
1063 proto_unregister(&dccp_v4_prot);
1064 }
1065
1066 module_init(dccp_v4_init);
1067 module_exit(dccp_v4_exit);
1068
1069 /*
1070 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
1071 * values directly, Also cover the case where the protocol is not specified,
1072 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
1073 */
1074 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
1075 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
1076 MODULE_LICENSE("GPL");
1077 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
1078 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");
1079
