1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * net/dccp/ipv4.c 4 * 5 * An implementation of the DCCP protocol 6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7 */ 8 9#include <linux/dccp.h> 10#include <linux/icmp.h> 11#include <linux/slab.h> 12#include <linux/module.h> 13#include <linux/skbuff.h> 14#include <linux/random.h> 15 16#include <net/icmp.h> 17#include <net/inet_common.h> 18#include <net/inet_hashtables.h> 19#include <net/inet_sock.h> 20#include <net/protocol.h> 21#include <net/sock.h> 22#include <net/timewait_sock.h> 23#include <net/tcp_states.h> 24#include <net/xfrm.h> 25#include <net/secure_seq.h> 26 27#include "ackvec.h" 28#include "ccid.h" 29#include "dccp.h" 30#include "feat.h" 31 32/* 33 * The per-net dccp.v4_ctl_sk socket is used for responding to 34 * the Out-of-the-blue (OOTB) packets. A control sock will be created 35 * for this socket at the initialization time. 36 */ 37 38int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 39{ 40 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 41 struct inet_sock *inet = inet_sk(sk); 42 struct dccp_sock *dp = dccp_sk(sk); 43 __be16 orig_sport, orig_dport; 44 __be32 daddr, nexthop; 45 struct flowi4 *fl4; 46 struct rtable *rt; 47 int err; 48 struct ip_options_rcu *inet_opt; 49 50 dp->dccps_role = DCCP_ROLE_CLIENT; 51 52 if (addr_len < sizeof(struct sockaddr_in)) 53 return -EINVAL; 54 55 if (usin->sin_family != AF_INET) 56 return -EAFNOSUPPORT; 57 58 nexthop = daddr = usin->sin_addr.s_addr; 59 60 inet_opt = rcu_dereference_protected(inet->inet_opt, 61 lockdep_sock_is_held(sk)); 62 if (inet_opt != NULL && inet_opt->opt.srr) { 63 if (daddr == 0) 64 return -EINVAL; 65 nexthop = inet_opt->opt.faddr; 66 } 67 68 orig_sport = inet->inet_sport; 69 orig_dport = usin->sin_port; 70 fl4 = &inet->cork.fl.u.ip4; 71 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 72 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 73 IPPROTO_DCCP, 74 orig_sport, orig_dport, sk); 75 if (IS_ERR(rt)) 76 return PTR_ERR(rt); 77 78 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 79 ip_rt_put(rt); 80 return -ENETUNREACH; 81 } 82 83 if (inet_opt == NULL || !inet_opt->opt.srr) 84 daddr = fl4->daddr; 85 86 if (inet->inet_saddr == 0) 87 inet->inet_saddr = fl4->saddr; 88 sk_rcv_saddr_set(sk, inet->inet_saddr); 89 inet->inet_dport = usin->sin_port; 90 sk_daddr_set(sk, daddr); 91 92 inet_csk(sk)->icsk_ext_hdr_len = 0; 93 if (inet_opt) 94 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 95 /* 96 * Socket identity is still unknown (sport may be zero). 97 * However we set state to DCCP_REQUESTING and not releasing socket 98 * lock select source port, enter ourselves into the hash tables and 99 * complete initialization after this. 100 */ 101 dccp_set_state(sk, DCCP_REQUESTING); 102 err = inet_hash_connect(&dccp_death_row, sk); 103 if (err != 0) 104 goto failure; 105 106 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 107 inet->inet_sport, inet->inet_dport, sk); 108 if (IS_ERR(rt)) { 109 err = PTR_ERR(rt); 110 rt = NULL; 111 goto failure; 112 } 113 /* OK, now commit destination to socket. */ 114 sk_setup_caps(sk, &rt->dst); 115 116 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 117 inet->inet_daddr, 118 inet->inet_sport, 119 inet->inet_dport); 120 inet->inet_id = prandom_u32(); 121 122 err = dccp_connect(sk); 123 rt = NULL; 124 if (err != 0) 125 goto failure; 126out: 127 return err; 128failure: 129 /* 130 * This unhashes the socket and releases the local port, if necessary. 131 */ 132 dccp_set_state(sk, DCCP_CLOSED); 133 if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) 134 inet_reset_saddr(sk); 135 ip_rt_put(rt); 136 sk->sk_route_caps = 0; 137 inet->inet_dport = 0; 138 goto out; 139} 140EXPORT_SYMBOL_GPL(dccp_v4_connect); 141 142/* 143 * This routine does path mtu discovery as defined in RFC1191. 144 */ 145static inline void dccp_do_pmtu_discovery(struct sock *sk, 146 const struct iphdr *iph, 147 u32 mtu) 148{ 149 struct dst_entry *dst; 150 const struct inet_sock *inet = inet_sk(sk); 151 const struct dccp_sock *dp = dccp_sk(sk); 152 153 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 154 * send out by Linux are always < 576bytes so they should go through 155 * unfragmented). 156 */ 157 if (sk->sk_state == DCCP_LISTEN) 158 return; 159 160 dst = inet_csk_update_pmtu(sk, mtu); 161 if (!dst) 162 return; 163 164 /* Something is about to be wrong... Remember soft error 165 * for the case, if this connection will not able to recover. 166 */ 167 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 168 sk->sk_err_soft = EMSGSIZE; 169 170 mtu = dst_mtu(dst); 171 172 if (inet->pmtudisc != IP_PMTUDISC_DONT && 173 ip_sk_accept_pmtu(sk) && 174 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 175 dccp_sync_mss(sk, mtu); 176 177 /* 178 * From RFC 4340, sec. 14.1: 179 * 180 * DCCP-Sync packets are the best choice for upward 181 * probing, since DCCP-Sync probes do not risk application 182 * data loss. 183 */ 184 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 185 } /* else let the usual retransmit timer handle it */ 186} 187 188static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 189{ 190 struct dst_entry *dst = __sk_dst_check(sk, 0); 191 192 if (dst) 193 dst->ops->redirect(dst, sk, skb); 194} 195 196void dccp_req_err(struct sock *sk, u64 seq) 197 { 198 struct request_sock *req = inet_reqsk(sk); 199 struct net *net = sock_net(sk); 200 201 /* 202 * ICMPs are not backlogged, hence we cannot get an established 203 * socket here. 204 */ 205 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 206 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 207 } else { 208 /* 209 * Still in RESPOND, just remove it silently. 210 * There is no good way to pass the error to the newly 211 * created socket, and POSIX does not want network 212 * errors returned from accept(). 213 */ 214 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 215 } 216 reqsk_put(req); 217} 218EXPORT_SYMBOL(dccp_req_err); 219 220/* 221 * This routine is called by the ICMP module when it gets some sort of error 222 * condition. If err < 0 then the socket should be closed and the error 223 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 224 * After adjustment header points to the first 8 bytes of the tcp header. We 225 * need to find the appropriate port. 226 * 227 * The locking strategy used here is very "optimistic". When someone else 228 * accesses the socket the ICMP is just dropped and for some paths there is no 229 * check at all. A more general error queue to queue errors for later handling 230 * is probably better. 231 */ 232static int dccp_v4_err(struct sk_buff *skb, u32 info) 233{ 234 const struct iphdr *iph = (struct iphdr *)skb->data; 235 const u8 offset = iph->ihl << 2; 236 const struct dccp_hdr *dh; 237 struct dccp_sock *dp; 238 struct inet_sock *inet; 239 const int type = icmp_hdr(skb)->type; 240 const int code = icmp_hdr(skb)->code; 241 struct sock *sk; 242 __u64 seq; 243 int err; 244 struct net *net = dev_net(skb->dev); 245 246 if (!pskb_may_pull(skb, offset + sizeof(*dh))) 247 return -EINVAL; 248 dh = (struct dccp_hdr *)(skb->data + offset); 249 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) 250 return -EINVAL; 251 iph = (struct iphdr *)skb->data; 252 dh = (struct dccp_hdr *)(skb->data + offset); 253 254 sk = __inet_lookup_established(net, &dccp_hashinfo, 255 iph->daddr, dh->dccph_dport, 256 iph->saddr, ntohs(dh->dccph_sport), 257 inet_iif(skb), 0); 258 if (!sk) { 259 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 260 return -ENOENT; 261 } 262 263 if (sk->sk_state == DCCP_TIME_WAIT) { 264 inet_twsk_put(inet_twsk(sk)); 265 return 0; 266 } 267 seq = dccp_hdr_seq(dh); 268 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 269 dccp_req_err(sk, seq); 270 return 0; 271 } 272 273 bh_lock_sock(sk); 274 /* If too many ICMPs get dropped on busy 275 * servers this needs to be solved differently. 276 */ 277 if (sock_owned_by_user(sk)) 278 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 279 280 if (sk->sk_state == DCCP_CLOSED) 281 goto out; 282 283 dp = dccp_sk(sk); 284 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 285 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 286 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 287 goto out; 288 } 289 290 switch (type) { 291 case ICMP_REDIRECT: 292 if (!sock_owned_by_user(sk)) 293 dccp_do_redirect(skb, sk); 294 goto out; 295 case ICMP_SOURCE_QUENCH: 296 /* Just silently ignore these. */ 297 goto out; 298 case ICMP_PARAMETERPROB: 299 err = EPROTO; 300 break; 301 case ICMP_DEST_UNREACH: 302 if (code > NR_ICMP_UNREACH) 303 goto out; 304 305 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 306 if (!sock_owned_by_user(sk)) 307 dccp_do_pmtu_discovery(sk, iph, info); 308 goto out; 309 } 310 311 err = icmp_err_convert[code].errno; 312 break; 313 case ICMP_TIME_EXCEEDED: 314 err = EHOSTUNREACH; 315 break; 316 default: 317 goto out; 318 } 319 320 switch (sk->sk_state) { 321 case DCCP_REQUESTING: 322 case DCCP_RESPOND: 323 if (!sock_owned_by_user(sk)) { 324 __DCCP_INC_STATS(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; 357out: 358 bh_unlock_sock(sk); 359 sock_put(sk); 360 return 0; 361} 362 363static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 364 __be32 src, __be32 dst) 365{ 366 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 367} 368 369void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 370{ 371 const struct inet_sock *inet = inet_sk(sk); 372 struct dccp_hdr *dh = dccp_hdr(skb); 373 374 dccp_csum_outgoing(skb); 375 dh->dccph_checksum = dccp_v4_csum_finish(skb, 376 inet->inet_saddr, 377 inet->inet_daddr); 378} 379EXPORT_SYMBOL_GPL(dccp_v4_send_check); 380 381static 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 */ 395struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 396 struct sk_buff *skb, 397 struct request_sock *req, 398 struct dst_entry *dst, 399 struct request_sock *req_unhash, 400 bool *own_req) 401{ 402 struct inet_request_sock *ireq; 403 struct inet_sock *newinet; 404 struct sock *newsk; 405 406 if (sk_acceptq_is_full(sk)) 407 goto exit_overflow; 408 409 newsk = dccp_create_openreq_child(sk, req, skb); 410 if (newsk == NULL) 411 goto exit_nonewsk; 412 413 newinet = inet_sk(newsk); 414 ireq = inet_rsk(req); 415 sk_daddr_set(newsk, ireq->ir_rmt_addr); 416 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 417 newinet->inet_saddr = ireq->ir_loc_addr; 418 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 419 newinet->mc_index = inet_iif(skb); 420 newinet->mc_ttl = ip_hdr(skb)->ttl; 421 newinet->inet_id = prandom_u32(); 422 423 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 424 goto put_and_exit; 425 426 sk_setup_caps(newsk, dst); 427 428 dccp_sync_mss(newsk, dst_mtu(dst)); 429 430 if (__inet_inherit_port(sk, newsk) < 0) 431 goto put_and_exit; 432 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 433 if (*own_req) 434 ireq->ireq_opt = NULL; 435 else 436 newinet->inet_opt = NULL; 437 return newsk; 438 439exit_overflow: 440 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 441exit_nonewsk: 442 dst_release(dst); 443exit: 444 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 445 return NULL; 446put_and_exit: 447 newinet->inet_opt = NULL; 448 inet_csk_prepare_forced_close(newsk); 449 dccp_done(newsk); 450 goto exit; 451} 452EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 453 454static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 455 struct sk_buff *skb) 456{ 457 struct rtable *rt; 458 const struct iphdr *iph = ip_hdr(skb); 459 struct flowi4 fl4 = { 460 .flowi4_oif = inet_iif(skb), 461 .daddr = iph->saddr, 462 .saddr = iph->daddr, 463 .flowi4_tos = RT_CONN_FLAGS(sk), 464 .flowi4_proto = sk->sk_protocol, 465 .fl4_sport = dccp_hdr(skb)->dccph_dport, 466 .fl4_dport = dccp_hdr(skb)->dccph_sport, 467 }; 468 469 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 470 rt = ip_route_output_flow(net, &fl4, sk); 471 if (IS_ERR(rt)) { 472 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 473 return NULL; 474 } 475 476 return &rt->dst; 477} 478 479static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 480{ 481 int err = -1; 482 struct sk_buff *skb; 483 struct dst_entry *dst; 484 struct flowi4 fl4; 485 486 dst = inet_csk_route_req(sk, &fl4, req); 487 if (dst == NULL) 488 goto out; 489 490 skb = dccp_make_response(sk, dst, req); 491 if (skb != NULL) { 492 const struct inet_request_sock *ireq = inet_rsk(req); 493 struct dccp_hdr *dh = dccp_hdr(skb); 494 495 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 496 ireq->ir_rmt_addr); 497 rcu_read_lock(); 498 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 499 ireq->ir_rmt_addr, 500 rcu_dereference(ireq->ireq_opt), 501 inet_sk(sk)->tos); 502 rcu_read_unlock(); 503 err = net_xmit_eval(err); 504 } 505 506out: 507 dst_release(dst); 508 return err; 509} 510 511static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 512{ 513 int err; 514 const struct iphdr *rxiph; 515 struct sk_buff *skb; 516 struct dst_entry *dst; 517 struct net *net = dev_net(skb_dst(rxskb)->dev); 518 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 519 520 /* Never send a reset in response to a reset. */ 521 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 522 return; 523 524 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 525 return; 526 527 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 528 if (dst == NULL) 529 return; 530 531 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 532 if (skb == NULL) 533 goto out; 534 535 rxiph = ip_hdr(rxskb); 536 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 537 rxiph->daddr); 538 skb_dst_set(skb, dst_clone(dst)); 539 540 local_bh_disable(); 541 bh_lock_sock(ctl_sk); 542 err = ip_build_and_send_pkt(skb, ctl_sk, 543 rxiph->daddr, rxiph->saddr, NULL, 544 inet_sk(ctl_sk)->tos); 545 bh_unlock_sock(ctl_sk); 546 547 if (net_xmit_eval(err) == 0) { 548 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 549 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 550 } 551 local_bh_enable(); 552out: 553 dst_release(dst); 554} 555 556static void dccp_v4_reqsk_destructor(struct request_sock *req) 557{ 558 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 559 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 560} 561 562void dccp_syn_ack_timeout(const struct request_sock *req) 563{ 564} 565EXPORT_SYMBOL(dccp_syn_ack_timeout); 566 567static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 568 .family = PF_INET, 569 .obj_size = sizeof(struct dccp_request_sock), 570 .rtx_syn_ack = dccp_v4_send_response, 571 .send_ack = dccp_reqsk_send_ack, 572 .destructor = dccp_v4_reqsk_destructor, 573 .send_reset = dccp_v4_ctl_send_reset, 574 .syn_ack_timeout = dccp_syn_ack_timeout, 575}; 576 577int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 578{ 579 struct inet_request_sock *ireq; 580 struct request_sock *req; 581 struct dccp_request_sock *dreq; 582 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 583 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 584 585 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 586 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 587 return 0; /* discard, don't send a reset here */ 588 589 if (dccp_bad_service_code(sk, service)) { 590 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 591 goto drop; 592 } 593 /* 594 * TW buckets are converted to open requests without 595 * limitations, they conserve resources and peer is 596 * evidently real one. 597 */ 598 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 599 if (inet_csk_reqsk_queue_is_full(sk)) 600 goto drop; 601 602 if (sk_acceptq_is_full(sk)) 603 goto drop; 604 605 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 606 if (req == NULL) 607 goto drop; 608 609 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 610 goto drop_and_free; 611 612 dreq = dccp_rsk(req); 613 if (dccp_parse_options(sk, dreq, skb)) 614 goto drop_and_free; 615 616 ireq = inet_rsk(req); 617 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 618 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 619 ireq->ir_mark = inet_request_mark(sk, skb); 620 ireq->ireq_family = AF_INET; 621 ireq->ir_iif = sk->sk_bound_dev_if; 622 623 if (security_inet_conn_request(sk, skb, req)) 624 goto drop_and_free; 625 626 /* 627 * Step 3: Process LISTEN state 628 * 629 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 630 * 631 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 632 */ 633 dreq->dreq_isr = dcb->dccpd_seq; 634 dreq->dreq_gsr = dreq->dreq_isr; 635 dreq->dreq_iss = dccp_v4_init_sequence(skb); 636 dreq->dreq_gss = dreq->dreq_iss; 637 dreq->dreq_service = service; 638 639 if (dccp_v4_send_response(sk, req)) 640 goto drop_and_free; 641 642 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 643 reqsk_put(req); 644 return 0; 645 646drop_and_free: 647 reqsk_free(req); 648drop: 649 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 650 return -1; 651} 652EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 653 654int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 655{ 656 struct dccp_hdr *dh = dccp_hdr(skb); 657 658 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 659 if (dccp_rcv_established(sk, skb, dh, skb->len)) 660 goto reset; 661 return 0; 662 } 663 664 /* 665 * Step 3: Process LISTEN state 666 * If P.type == Request or P contains a valid Init Cookie option, 667 * (* Must scan the packet's options to check for Init 668 * Cookies. Only Init Cookies are processed here, 669 * however; other options are processed in Step 8. This 670 * scan need only be performed if the endpoint uses Init 671 * Cookies *) 672 * (* Generate a new socket and switch to that socket *) 673 * Set S := new socket for this port pair 674 * S.state = RESPOND 675 * Choose S.ISS (initial seqno) or set from Init Cookies 676 * Initialize S.GAR := S.ISS 677 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 678 * Continue with S.state == RESPOND 679 * (* A Response packet will be generated in Step 11 *) 680 * Otherwise, 681 * Generate Reset(No Connection) unless P.type == Reset 682 * Drop packet and return 683 * 684 * NOTE: the check for the packet types is done in 685 * dccp_rcv_state_process 686 */ 687 688 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 689 goto reset; 690 return 0; 691 692reset: 693 dccp_v4_ctl_send_reset(sk, skb); 694 kfree_skb(skb); 695 return 0; 696} 697EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 698 699/** 700 * dccp_invalid_packet - check for malformed packets 701 * @skb: Packet to validate 702 * 703 * Implements RFC 4340, 8.5: Step 1: Check header basics 704 * Packets that fail these checks are ignored and do not receive Resets. 705 */ 706int dccp_invalid_packet(struct sk_buff *skb) 707{ 708 const struct dccp_hdr *dh; 709 unsigned int cscov; 710 u8 dccph_doff; 711 712 if (skb->pkt_type != PACKET_HOST) 713 return 1; 714 715 /* If the packet is shorter than 12 bytes, drop packet and return */ 716 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 717 DCCP_WARN("pskb_may_pull failed\n"); 718 return 1; 719 } 720 721 dh = dccp_hdr(skb); 722 723 /* If P.type is not understood, drop packet and return */ 724 if (dh->dccph_type >= DCCP_PKT_INVALID) { 725 DCCP_WARN("invalid packet type\n"); 726 return 1; 727 } 728 729 /* 730 * If P.Data Offset is too small for packet type, drop packet and return 731 */ 732 dccph_doff = dh->dccph_doff; 733 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 734 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 735 return 1; 736 } 737 /* 738 * If P.Data Offset is too large for packet, drop packet and return 739 */ 740 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 741 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 742 return 1; 743 } 744 dh = dccp_hdr(skb); 745 /* 746 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 747 * has short sequence numbers), drop packet and return 748 */ 749 if ((dh->dccph_type < DCCP_PKT_DATA || 750 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 751 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 752 dccp_packet_name(dh->dccph_type)); 753 return 1; 754 } 755 756 /* 757 * If P.CsCov is too large for the packet size, drop packet and return. 758 * This must come _before_ checksumming (not as RFC 4340 suggests). 759 */ 760 cscov = dccp_csum_coverage(skb); 761 if (cscov > skb->len) { 762 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 763 dh->dccph_cscov, skb->len); 764 return 1; 765 } 766 767 /* If header checksum is incorrect, drop packet and return. 768 * (This step is completed in the AF-dependent functions.) */ 769 skb->csum = skb_checksum(skb, 0, cscov, 0); 770 771 return 0; 772} 773EXPORT_SYMBOL_GPL(dccp_invalid_packet); 774 775/* this is called when real data arrives */ 776static int dccp_v4_rcv(struct sk_buff *skb) 777{ 778 const struct dccp_hdr *dh; 779 const struct iphdr *iph; 780 bool refcounted; 781 struct sock *sk; 782 int min_cov; 783 784 /* Step 1: Check header basics */ 785 786 if (dccp_invalid_packet(skb)) 787 goto discard_it; 788 789 iph = ip_hdr(skb); 790 /* Step 1: If header checksum is incorrect, drop packet and return */ 791 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 792 DCCP_WARN("dropped packet with invalid checksum\n"); 793 goto discard_it; 794 } 795 796 dh = dccp_hdr(skb); 797 798 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 799 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 800 801 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 802 dccp_packet_name(dh->dccph_type), 803 &iph->saddr, ntohs(dh->dccph_sport), 804 &iph->daddr, ntohs(dh->dccph_dport), 805 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 806 807 if (dccp_packet_without_ack(skb)) { 808 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 809 dccp_pr_debug_cat("\n"); 810 } else { 811 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 812 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 813 DCCP_SKB_CB(skb)->dccpd_ack_seq); 814 } 815 816lookup: 817 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 818 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 819 if (!sk) { 820 dccp_pr_debug("failed to look up flow ID in table and " 821 "get corresponding socket\n"); 822 goto no_dccp_socket; 823 } 824 825 /* 826 * Step 2: 827 * ... or S.state == TIMEWAIT, 828 * Generate Reset(No Connection) unless P.type == Reset 829 * Drop packet and return 830 */ 831 if (sk->sk_state == DCCP_TIME_WAIT) { 832 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 833 inet_twsk_put(inet_twsk(sk)); 834 goto no_dccp_socket; 835 } 836 837 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 838 struct request_sock *req = inet_reqsk(sk); 839 struct sock *nsk; 840 841 sk = req->rsk_listener; 842 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 843 inet_csk_reqsk_queue_drop_and_put(sk, req); 844 goto lookup; 845 } 846 sock_hold(sk); 847 refcounted = true; 848 nsk = dccp_check_req(sk, skb, req); 849 if (!nsk) { 850 reqsk_put(req); 851 goto discard_and_relse; 852 } 853 if (nsk == sk) { 854 reqsk_put(req); 855 } else if (dccp_child_process(sk, nsk, skb)) { 856 dccp_v4_ctl_send_reset(sk, skb); 857 goto discard_and_relse; 858 } else { 859 sock_put(sk); 860 return 0; 861 } 862 } 863 /* 864 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 865 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 866 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 867 */ 868 min_cov = dccp_sk(sk)->dccps_pcrlen; 869 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 870 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 871 dh->dccph_cscov, min_cov); 872 /* FIXME: "Such packets SHOULD be reported using Data Dropped 873 * options (Section 11.7) with Drop Code 0, Protocol 874 * Constraints." */ 875 goto discard_and_relse; 876 } 877 878 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 879 goto discard_and_relse; 880 nf_reset_ct(skb); 881 882 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 883 884no_dccp_socket: 885 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 886 goto discard_it; 887 /* 888 * Step 2: 889 * If no socket ... 890 * Generate Reset(No Connection) unless P.type == Reset 891 * Drop packet and return 892 */ 893 if (dh->dccph_type != DCCP_PKT_RESET) { 894 DCCP_SKB_CB(skb)->dccpd_reset_code = 895 DCCP_RESET_CODE_NO_CONNECTION; 896 dccp_v4_ctl_send_reset(sk, skb); 897 } 898 899discard_it: 900 kfree_skb(skb); 901 return 0; 902 903discard_and_relse: 904 if (refcounted) 905 sock_put(sk); 906 goto discard_it; 907} 908 909static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 910 .queue_xmit = ip_queue_xmit, 911 .send_check = dccp_v4_send_check, 912 .rebuild_header = inet_sk_rebuild_header, 913 .conn_request = dccp_v4_conn_request, 914 .syn_recv_sock = dccp_v4_request_recv_sock, 915 .net_header_len = sizeof(struct iphdr), 916 .setsockopt = ip_setsockopt, 917 .getsockopt = ip_getsockopt, 918 .addr2sockaddr = inet_csk_addr2sockaddr, 919 .sockaddr_len = sizeof(struct sockaddr_in), 920}; 921 922static int dccp_v4_init_sock(struct sock *sk) 923{ 924 static __u8 dccp_v4_ctl_sock_initialized; 925 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 926 927 if (err == 0) { 928 if (unlikely(!dccp_v4_ctl_sock_initialized)) 929 dccp_v4_ctl_sock_initialized = 1; 930 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 931 } 932 933 return err; 934} 935 936static struct timewait_sock_ops dccp_timewait_sock_ops = { 937 .twsk_obj_size = sizeof(struct inet_timewait_sock), 938}; 939 940static struct proto dccp_v4_prot = { 941 .name = "DCCP", 942 .owner = THIS_MODULE, 943 .close = dccp_close, 944 .connect = dccp_v4_connect, 945 .disconnect = dccp_disconnect, 946 .ioctl = dccp_ioctl, 947 .init = dccp_v4_init_sock, 948 .setsockopt = dccp_setsockopt, 949 .getsockopt = dccp_getsockopt, 950 .sendmsg = dccp_sendmsg, 951 .recvmsg = dccp_recvmsg, 952 .backlog_rcv = dccp_v4_do_rcv, 953 .hash = inet_hash, 954 .unhash = inet_unhash, 955 .accept = inet_csk_accept, 956 .get_port = inet_csk_get_port, 957 .shutdown = dccp_shutdown, 958 .destroy = dccp_destroy_sock, 959 .orphan_count = &dccp_orphan_count, 960 .max_header = MAX_DCCP_HEADER, 961 .obj_size = sizeof(struct dccp_sock), 962 .slab_flags = SLAB_TYPESAFE_BY_RCU, 963 .rsk_prot = &dccp_request_sock_ops, 964 .twsk_prot = &dccp_timewait_sock_ops, 965 .h.hashinfo = &dccp_hashinfo, 966}; 967 968static const struct net_protocol dccp_v4_protocol = { 969 .handler = dccp_v4_rcv, 970 .err_handler = dccp_v4_err, 971 .no_policy = 1, 972 .netns_ok = 1, 973 .icmp_strict_tag_validation = 1, 974}; 975 976static const struct proto_ops inet_dccp_ops = { 977 .family = PF_INET, 978 .owner = THIS_MODULE, 979 .release = inet_release, 980 .bind = inet_bind, 981 .connect = inet_stream_connect, 982 .socketpair = sock_no_socketpair, 983 .accept = inet_accept, 984 .getname = inet_getname, 985 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 986 .poll = dccp_poll, 987 .ioctl = inet_ioctl, 988 .gettstamp = sock_gettstamp, 989 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 990 .listen = inet_dccp_listen, 991 .shutdown = inet_shutdown, 992 .setsockopt = sock_common_setsockopt, 993 .getsockopt = sock_common_getsockopt, 994 .sendmsg = inet_sendmsg, 995 .recvmsg = sock_common_recvmsg, 996 .mmap = sock_no_mmap, 997 .sendpage = sock_no_sendpage, 998}; 999 1000static struct inet_protosw dccp_v4_protosw = { 1001 .type = SOCK_DCCP, 1002 .protocol = IPPROTO_DCCP, 1003 .prot = &dccp_v4_prot, 1004 .ops = &inet_dccp_ops, 1005 .flags = INET_PROTOSW_ICSK, 1006}; 1007 1008static int __net_init dccp_v4_init_net(struct net *net) 1009{ 1010 if (dccp_hashinfo.bhash == NULL) 1011 return -ESOCKTNOSUPPORT; 1012 1013 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1014 SOCK_DCCP, IPPROTO_DCCP, net); 1015} 1016 1017static void __net_exit dccp_v4_exit_net(struct net *net) 1018{ 1019 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1020} 1021 1022static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1023{ 1024 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1025} 1026 1027static struct pernet_operations dccp_v4_ops = { 1028 .init = dccp_v4_init_net, 1029 .exit = dccp_v4_exit_net, 1030 .exit_batch = dccp_v4_exit_batch, 1031}; 1032 1033static int __init dccp_v4_init(void) 1034{ 1035 int err = proto_register(&dccp_v4_prot, 1); 1036 1037 if (err) 1038 goto out; 1039 1040 inet_register_protosw(&dccp_v4_protosw); 1041 1042 err = register_pernet_subsys(&dccp_v4_ops); 1043 if (err) 1044 goto out_destroy_ctl_sock; 1045 1046 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1047 if (err) 1048 goto out_proto_unregister; 1049 1050out: 1051 return err; 1052out_proto_unregister: 1053 unregister_pernet_subsys(&dccp_v4_ops); 1054out_destroy_ctl_sock: 1055 inet_unregister_protosw(&dccp_v4_protosw); 1056 proto_unregister(&dccp_v4_prot); 1057 goto out; 1058} 1059 1060static void __exit dccp_v4_exit(void) 1061{ 1062 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1063 unregister_pernet_subsys(&dccp_v4_ops); 1064 inet_unregister_protosw(&dccp_v4_protosw); 1065 proto_unregister(&dccp_v4_prot); 1066} 1067 1068module_init(dccp_v4_init); 1069module_exit(dccp_v4_exit); 1070 1071/* 1072 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1073 * values directly, Also cover the case where the protocol is not specified, 1074 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1075 */ 1076MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1077MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1078MODULE_LICENSE("GPL"); 1079MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1080MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1081