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