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 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 */ 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 } 199 200 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 } 207 208 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 */ 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 /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x, 258 * which is in byte 7 of the dccp header. 259 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 260 * 261 * Later on, we want to access the sequence number fields, which are 262 * beyond 8 bytes, so we have to pskb_may_pull() ourselves. 263 */ 264 dh = (struct dccp_hdr *)(skb->data + offset); 265 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) 266 return -EINVAL; 267 iph = (struct iphdr *)skb->data; 268 dh = (struct dccp_hdr *)(skb->data + offset); 269 270 sk = __inet_lookup_established(net, &dccp_hashinfo, 271 iph->daddr, dh->dccph_dport, 272 iph->saddr, ntohs(dh->dccph_sport), 273 inet_iif(skb), 0); 274 if (!sk) { 275 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 276 return -ENOENT; 277 } 278 279 if (sk->sk_state == DCCP_TIME_WAIT) { 280 inet_twsk_put(inet_twsk(sk)); 281 return 0; 282 } 283 seq = dccp_hdr_seq(dh); 284 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 285 dccp_req_err(sk, seq); 286 return 0; 287 } 288 289 bh_lock_sock(sk); 290 /* If too many ICMPs get dropped on busy 291 * servers this needs to be solved differently. 292 */ 293 if (sock_owned_by_user(sk)) 294 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 295 296 if (sk->sk_state == DCCP_CLOSED) 297 goto out; 298 299 dp = dccp_sk(sk); 300 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 301 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 302 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 303 goto out; 304 } 305 306 switch (type) { 307 case ICMP_REDIRECT: 308 if (!sock_owned_by_user(sk)) 309 dccp_do_redirect(skb, sk); 310 goto out; 311 case ICMP_SOURCE_QUENCH: 312 /* Just silently ignore these. */ 313 goto out; 314 case ICMP_PARAMETERPROB: 315 err = EPROTO; 316 break; 317 case ICMP_DEST_UNREACH: 318 if (code > NR_ICMP_UNREACH) 319 goto out; 320 321 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 322 if (!sock_owned_by_user(sk)) 323 dccp_do_pmtu_discovery(sk, iph, info); 324 goto out; 325 } 326 327 err = icmp_err_convert[code].errno; 328 break; 329 case ICMP_TIME_EXCEEDED: 330 err = EHOSTUNREACH; 331 break; 332 default: 333 goto out; 334 } 335 336 switch (sk->sk_state) { 337 case DCCP_REQUESTING: 338 case DCCP_RESPOND: 339 if (!sock_owned_by_user(sk)) { 340 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 341 sk->sk_err = err; 342 343 sk_error_report(sk); 344 345 dccp_done(sk); 346 } else { 347 WRITE_ONCE(sk->sk_err_soft, err); 348 } 349 goto out; 350 } 351 352 /* If we've already connected we will keep trying 353 * until we time out, or the user gives up. 354 * 355 * rfc1122 4.2.3.9 allows to consider as hard errors 356 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 357 * but it is obsoleted by pmtu discovery). 358 * 359 * Note, that in modern internet, where routing is unreliable 360 * and in each dark corner broken firewalls sit, sending random 361 * errors ordered by their masters even this two messages finally lose 362 * their original sense (even Linux sends invalid PORT_UNREACHs) 363 * 364 * Now we are in compliance with RFCs. 365 * --ANK (980905) 366 */ 367 368 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) { 369 sk->sk_err = err; 370 sk_error_report(sk); 371 } else { /* Only an error on timeout */ 372 WRITE_ONCE(sk->sk_err_soft, err); 373 } 374 out: 375 bh_unlock_sock(sk); 376 sock_put(sk); 377 return 0; 378 } 379 380 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 381 __be32 src, __be32 dst) 382 { 383 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 384 } 385 386 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 387 { 388 const struct inet_sock *inet = inet_sk(sk); 389 struct dccp_hdr *dh = dccp_hdr(skb); 390 391 dccp_csum_outgoing(skb); 392 dh->dccph_checksum = dccp_v4_csum_finish(skb, 393 inet->inet_saddr, 394 inet->inet_daddr); 395 } 396 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 397 398 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 399 { 400 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 401 ip_hdr(skb)->saddr, 402 dccp_hdr(skb)->dccph_dport, 403 dccp_hdr(skb)->dccph_sport); 404 } 405 406 /* 407 * The three way handshake has completed - we got a valid ACK or DATAACK - 408 * now create the new socket. 409 * 410 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 411 */ 412 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 413 struct sk_buff *skb, 414 struct request_sock *req, 415 struct dst_entry *dst, 416 struct request_sock *req_unhash, 417 bool *own_req) 418 { 419 struct inet_request_sock *ireq; 420 struct inet_sock *newinet; 421 struct sock *newsk; 422 423 if (sk_acceptq_is_full(sk)) 424 goto exit_overflow; 425 426 newsk = dccp_create_openreq_child(sk, req, skb); 427 if (newsk == NULL) 428 goto exit_nonewsk; 429 430 newinet = inet_sk(newsk); 431 ireq = inet_rsk(req); 432 sk_daddr_set(newsk, ireq->ir_rmt_addr); 433 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 434 newinet->inet_saddr = ireq->ir_loc_addr; 435 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 436 newinet->mc_index = inet_iif(skb); 437 newinet->mc_ttl = ip_hdr(skb)->ttl; 438 atomic_set(&newinet->inet_id, get_random_u16()); 439 440 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 441 goto put_and_exit; 442 443 sk_setup_caps(newsk, dst); 444 445 dccp_sync_mss(newsk, dst_mtu(dst)); 446 447 if (__inet_inherit_port(sk, newsk) < 0) 448 goto put_and_exit; 449 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 450 if (*own_req) 451 ireq->ireq_opt = NULL; 452 else 453 newinet->inet_opt = NULL; 454 return newsk; 455 456 exit_overflow: 457 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 458 exit_nonewsk: 459 dst_release(dst); 460 exit: 461 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 462 return NULL; 463 put_and_exit: 464 newinet->inet_opt = NULL; 465 inet_csk_prepare_forced_close(newsk); 466 dccp_done(newsk); 467 goto exit; 468 } 469 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 470 471 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 472 struct sk_buff *skb) 473 { 474 struct rtable *rt; 475 const struct iphdr *iph = ip_hdr(skb); 476 struct flowi4 fl4 = { 477 .flowi4_oif = inet_iif(skb), 478 .daddr = iph->saddr, 479 .saddr = iph->daddr, 480 .flowi4_tos = ip_sock_rt_tos(sk), 481 .flowi4_scope = ip_sock_rt_scope(sk), 482 .flowi4_proto = sk->sk_protocol, 483 .fl4_sport = dccp_hdr(skb)->dccph_dport, 484 .fl4_dport = dccp_hdr(skb)->dccph_sport, 485 }; 486 487 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 488 rt = ip_route_output_flow(net, &fl4, sk); 489 if (IS_ERR(rt)) { 490 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 491 return NULL; 492 } 493 494 return &rt->dst; 495 } 496 497 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 498 { 499 int err = -1; 500 struct sk_buff *skb; 501 struct dst_entry *dst; 502 struct flowi4 fl4; 503 504 dst = inet_csk_route_req(sk, &fl4, req); 505 if (dst == NULL) 506 goto out; 507 508 skb = dccp_make_response(sk, dst, req); 509 if (skb != NULL) { 510 const struct inet_request_sock *ireq = inet_rsk(req); 511 struct dccp_hdr *dh = dccp_hdr(skb); 512 513 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 514 ireq->ir_rmt_addr); 515 rcu_read_lock(); 516 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 517 ireq->ir_rmt_addr, 518 rcu_dereference(ireq->ireq_opt), 519 inet_sk(sk)->tos); 520 rcu_read_unlock(); 521 err = net_xmit_eval(err); 522 } 523 524 out: 525 dst_release(dst); 526 return err; 527 } 528 529 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 530 { 531 int err; 532 const struct iphdr *rxiph; 533 struct sk_buff *skb; 534 struct dst_entry *dst; 535 struct net *net = dev_net(skb_dst(rxskb)->dev); 536 struct dccp_v4_pernet *pn; 537 struct sock *ctl_sk; 538 539 /* Never send a reset in response to a reset. */ 540 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 541 return; 542 543 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 544 return; 545 546 pn = net_generic(net, dccp_v4_pernet_id); 547 ctl_sk = pn->v4_ctl_sk; 548 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 549 if (dst == NULL) 550 return; 551 552 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 553 if (skb == NULL) 554 goto out; 555 556 rxiph = ip_hdr(rxskb); 557 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 558 rxiph->daddr); 559 skb_dst_set(skb, dst_clone(dst)); 560 561 local_bh_disable(); 562 bh_lock_sock(ctl_sk); 563 err = ip_build_and_send_pkt(skb, ctl_sk, 564 rxiph->daddr, rxiph->saddr, NULL, 565 inet_sk(ctl_sk)->tos); 566 bh_unlock_sock(ctl_sk); 567 568 if (net_xmit_eval(err) == 0) { 569 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 570 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 571 } 572 local_bh_enable(); 573 out: 574 dst_release(dst); 575 } 576 577 static void dccp_v4_reqsk_destructor(struct request_sock *req) 578 { 579 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 580 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 581 } 582 583 void dccp_syn_ack_timeout(const struct request_sock *req) 584 { 585 } 586 EXPORT_SYMBOL(dccp_syn_ack_timeout); 587 588 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 589 .family = PF_INET, 590 .obj_size = sizeof(struct dccp_request_sock), 591 .rtx_syn_ack = dccp_v4_send_response, 592 .send_ack = dccp_reqsk_send_ack, 593 .destructor = dccp_v4_reqsk_destructor, 594 .send_reset = dccp_v4_ctl_send_reset, 595 .syn_ack_timeout = dccp_syn_ack_timeout, 596 }; 597 598 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 599 { 600 struct inet_request_sock *ireq; 601 struct request_sock *req; 602 struct dccp_request_sock *dreq; 603 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 604 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 605 606 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 607 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 608 return 0; /* discard, don't send a reset here */ 609 610 if (dccp_bad_service_code(sk, service)) { 611 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 612 goto drop; 613 } 614 /* 615 * TW buckets are converted to open requests without 616 * limitations, they conserve resources and peer is 617 * evidently real one. 618 */ 619 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 620 if (inet_csk_reqsk_queue_is_full(sk)) 621 goto drop; 622 623 if (sk_acceptq_is_full(sk)) 624 goto drop; 625 626 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 627 if (req == NULL) 628 goto drop; 629 630 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 631 goto drop_and_free; 632 633 dreq = dccp_rsk(req); 634 if (dccp_parse_options(sk, dreq, skb)) 635 goto drop_and_free; 636 637 if (security_inet_conn_request(sk, skb, req)) 638 goto drop_and_free; 639 640 ireq = inet_rsk(req); 641 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 642 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 643 ireq->ir_mark = inet_request_mark(sk, skb); 644 ireq->ireq_family = AF_INET; 645 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if); 646 647 /* 648 * Step 3: Process LISTEN state 649 * 650 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 651 * 652 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 653 */ 654 dreq->dreq_isr = dcb->dccpd_seq; 655 dreq->dreq_gsr = dreq->dreq_isr; 656 dreq->dreq_iss = dccp_v4_init_sequence(skb); 657 dreq->dreq_gss = dreq->dreq_iss; 658 dreq->dreq_service = service; 659 660 if (dccp_v4_send_response(sk, req)) 661 goto drop_and_free; 662 663 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 664 reqsk_put(req); 665 return 0; 666 667 drop_and_free: 668 reqsk_free(req); 669 drop: 670 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 671 return -1; 672 } 673 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 674 675 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 676 { 677 struct dccp_hdr *dh = dccp_hdr(skb); 678 679 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 680 if (dccp_rcv_established(sk, skb, dh, skb->len)) 681 goto reset; 682 return 0; 683 } 684 685 /* 686 * Step 3: Process LISTEN state 687 * If P.type == Request or P contains a valid Init Cookie option, 688 * (* Must scan the packet's options to check for Init 689 * Cookies. Only Init Cookies are processed here, 690 * however; other options are processed in Step 8. This 691 * scan need only be performed if the endpoint uses Init 692 * Cookies *) 693 * (* Generate a new socket and switch to that socket *) 694 * Set S := new socket for this port pair 695 * S.state = RESPOND 696 * Choose S.ISS (initial seqno) or set from Init Cookies 697 * Initialize S.GAR := S.ISS 698 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 699 * Continue with S.state == RESPOND 700 * (* A Response packet will be generated in Step 11 *) 701 * Otherwise, 702 * Generate Reset(No Connection) unless P.type == Reset 703 * Drop packet and return 704 * 705 * NOTE: the check for the packet types is done in 706 * dccp_rcv_state_process 707 */ 708 709 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 710 goto reset; 711 return 0; 712 713 reset: 714 dccp_v4_ctl_send_reset(sk, skb); 715 kfree_skb(skb); 716 return 0; 717 } 718 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 719 720 /** 721 * dccp_invalid_packet - check for malformed packets 722 * @skb: Packet to validate 723 * 724 * Implements RFC 4340, 8.5: Step 1: Check header basics 725 * Packets that fail these checks are ignored and do not receive Resets. 726 */ 727 int dccp_invalid_packet(struct sk_buff *skb) 728 { 729 const struct dccp_hdr *dh; 730 unsigned int cscov; 731 u8 dccph_doff; 732 733 if (skb->pkt_type != PACKET_HOST) 734 return 1; 735 736 /* If the packet is shorter than 12 bytes, drop packet and return */ 737 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 738 DCCP_WARN("pskb_may_pull failed\n"); 739 return 1; 740 } 741 742 dh = dccp_hdr(skb); 743 744 /* If P.type is not understood, drop packet and return */ 745 if (dh->dccph_type >= DCCP_PKT_INVALID) { 746 DCCP_WARN("invalid packet type\n"); 747 return 1; 748 } 749 750 /* 751 * If P.Data Offset is too small for packet type, drop packet and return 752 */ 753 dccph_doff = dh->dccph_doff; 754 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 755 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 756 return 1; 757 } 758 /* 759 * If P.Data Offset is too large for packet, drop packet and return 760 */ 761 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 762 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 763 return 1; 764 } 765 dh = dccp_hdr(skb); 766 /* 767 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 768 * has short sequence numbers), drop packet and return 769 */ 770 if ((dh->dccph_type < DCCP_PKT_DATA || 771 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 772 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 773 dccp_packet_name(dh->dccph_type)); 774 return 1; 775 } 776 777 /* 778 * If P.CsCov is too large for the packet size, drop packet and return. 779 * This must come _before_ checksumming (not as RFC 4340 suggests). 780 */ 781 cscov = dccp_csum_coverage(skb); 782 if (cscov > skb->len) { 783 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 784 dh->dccph_cscov, skb->len); 785 return 1; 786 } 787 788 /* If header checksum is incorrect, drop packet and return. 789 * (This step is completed in the AF-dependent functions.) */ 790 skb->csum = skb_checksum(skb, 0, cscov, 0); 791 792 return 0; 793 } 794 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 795 796 /* this is called when real data arrives */ 797 static int dccp_v4_rcv(struct sk_buff *skb) 798 { 799 const struct dccp_hdr *dh; 800 const struct iphdr *iph; 801 bool refcounted; 802 struct sock *sk; 803 int min_cov; 804 805 /* Step 1: Check header basics */ 806 807 if (dccp_invalid_packet(skb)) 808 goto discard_it; 809 810 iph = ip_hdr(skb); 811 /* Step 1: If header checksum is incorrect, drop packet and return */ 812 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 813 DCCP_WARN("dropped packet with invalid checksum\n"); 814 goto discard_it; 815 } 816 817 dh = dccp_hdr(skb); 818 819 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 820 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 821 822 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 823 dccp_packet_name(dh->dccph_type), 824 &iph->saddr, ntohs(dh->dccph_sport), 825 &iph->daddr, ntohs(dh->dccph_dport), 826 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 827 828 if (dccp_packet_without_ack(skb)) { 829 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 830 dccp_pr_debug_cat("\n"); 831 } else { 832 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 833 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 834 DCCP_SKB_CB(skb)->dccpd_ack_seq); 835 } 836 837 lookup: 838 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 839 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 840 if (!sk) { 841 dccp_pr_debug("failed to look up flow ID in table and " 842 "get corresponding socket\n"); 843 goto no_dccp_socket; 844 } 845 846 /* 847 * Step 2: 848 * ... or S.state == TIMEWAIT, 849 * Generate Reset(No Connection) unless P.type == Reset 850 * Drop packet and return 851 */ 852 if (sk->sk_state == DCCP_TIME_WAIT) { 853 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 854 inet_twsk_put(inet_twsk(sk)); 855 goto no_dccp_socket; 856 } 857 858 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 859 struct request_sock *req = inet_reqsk(sk); 860 struct sock *nsk; 861 862 sk = req->rsk_listener; 863 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 864 inet_csk_reqsk_queue_drop_and_put(sk, req); 865 goto lookup; 866 } 867 sock_hold(sk); 868 refcounted = true; 869 nsk = dccp_check_req(sk, skb, req); 870 if (!nsk) { 871 reqsk_put(req); 872 goto discard_and_relse; 873 } 874 if (nsk == sk) { 875 reqsk_put(req); 876 } else if (dccp_child_process(sk, nsk, skb)) { 877 dccp_v4_ctl_send_reset(sk, skb); 878 goto discard_and_relse; 879 } else { 880 sock_put(sk); 881 return 0; 882 } 883 } 884 /* 885 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 886 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 887 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 888 */ 889 min_cov = dccp_sk(sk)->dccps_pcrlen; 890 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 891 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 892 dh->dccph_cscov, min_cov); 893 /* FIXME: "Such packets SHOULD be reported using Data Dropped 894 * options (Section 11.7) with Drop Code 0, Protocol 895 * Constraints." */ 896 goto discard_and_relse; 897 } 898 899 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 900 goto discard_and_relse; 901 nf_reset_ct(skb); 902 903 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 904 905 no_dccp_socket: 906 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 907 goto discard_it; 908 /* 909 * Step 2: 910 * If no socket ... 911 * Generate Reset(No Connection) unless P.type == Reset 912 * Drop packet and return 913 */ 914 if (dh->dccph_type != DCCP_PKT_RESET) { 915 DCCP_SKB_CB(skb)->dccpd_reset_code = 916 DCCP_RESET_CODE_NO_CONNECTION; 917 dccp_v4_ctl_send_reset(sk, skb); 918 } 919 920 discard_it: 921 kfree_skb(skb); 922 return 0; 923 924 discard_and_relse: 925 if (refcounted) 926 sock_put(sk); 927 goto discard_it; 928 } 929 930 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 931 .queue_xmit = ip_queue_xmit, 932 .send_check = dccp_v4_send_check, 933 .rebuild_header = inet_sk_rebuild_header, 934 .conn_request = dccp_v4_conn_request, 935 .syn_recv_sock = dccp_v4_request_recv_sock, 936 .net_header_len = sizeof(struct iphdr), 937 .setsockopt = ip_setsockopt, 938 .getsockopt = ip_getsockopt, 939 .addr2sockaddr = inet_csk_addr2sockaddr, 940 .sockaddr_len = sizeof(struct sockaddr_in), 941 }; 942 943 static int dccp_v4_init_sock(struct sock *sk) 944 { 945 static __u8 dccp_v4_ctl_sock_initialized; 946 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 947 948 if (err == 0) { 949 if (unlikely(!dccp_v4_ctl_sock_initialized)) 950 dccp_v4_ctl_sock_initialized = 1; 951 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 952 } 953 954 return err; 955 } 956 957 static struct timewait_sock_ops dccp_timewait_sock_ops = { 958 .twsk_obj_size = sizeof(struct inet_timewait_sock), 959 }; 960 961 static struct proto dccp_v4_prot = { 962 .name = "DCCP", 963 .owner = THIS_MODULE, 964 .close = dccp_close, 965 .connect = dccp_v4_connect, 966 .disconnect = dccp_disconnect, 967 .ioctl = dccp_ioctl, 968 .init = dccp_v4_init_sock, 969 .setsockopt = dccp_setsockopt, 970 .getsockopt = dccp_getsockopt, 971 .sendmsg = dccp_sendmsg, 972 .recvmsg = dccp_recvmsg, 973 .backlog_rcv = dccp_v4_do_rcv, 974 .hash = inet_hash, 975 .unhash = inet_unhash, 976 .accept = inet_csk_accept, 977 .get_port = inet_csk_get_port, 978 .shutdown = dccp_shutdown, 979 .destroy = dccp_destroy_sock, 980 .orphan_count = &dccp_orphan_count, 981 .max_header = MAX_DCCP_HEADER, 982 .obj_size = sizeof(struct dccp_sock), 983 .slab_flags = SLAB_TYPESAFE_BY_RCU, 984 .rsk_prot = &dccp_request_sock_ops, 985 .twsk_prot = &dccp_timewait_sock_ops, 986 .h.hashinfo = &dccp_hashinfo, 987 }; 988 989 static const struct net_protocol dccp_v4_protocol = { 990 .handler = dccp_v4_rcv, 991 .err_handler = dccp_v4_err, 992 .no_policy = 1, 993 .icmp_strict_tag_validation = 1, 994 }; 995 996 static const struct proto_ops inet_dccp_ops = { 997 .family = PF_INET, 998 .owner = THIS_MODULE, 999 .release = inet_release, 1000 .bind = inet_bind, 1001 .connect = inet_stream_connect, 1002 .socketpair = sock_no_socketpair, 1003 .accept = inet_accept, 1004 .getname = inet_getname, 1005 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1006 .poll = dccp_poll, 1007 .ioctl = inet_ioctl, 1008 .gettstamp = sock_gettstamp, 1009 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1010 .listen = inet_dccp_listen, 1011 .shutdown = inet_shutdown, 1012 .setsockopt = sock_common_setsockopt, 1013 .getsockopt = sock_common_getsockopt, 1014 .sendmsg = inet_sendmsg, 1015 .recvmsg = sock_common_recvmsg, 1016 .mmap = sock_no_mmap, 1017 }; 1018 1019 static struct inet_protosw dccp_v4_protosw = { 1020 .type = SOCK_DCCP, 1021 .protocol = IPPROTO_DCCP, 1022 .prot = &dccp_v4_prot, 1023 .ops = &inet_dccp_ops, 1024 .flags = INET_PROTOSW_ICSK, 1025 }; 1026 1027 static int __net_init dccp_v4_init_net(struct net *net) 1028 { 1029 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1030 1031 if (dccp_hashinfo.bhash == NULL) 1032 return -ESOCKTNOSUPPORT; 1033 1034 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1035 SOCK_DCCP, IPPROTO_DCCP, net); 1036 } 1037 1038 static void __net_exit dccp_v4_exit_net(struct net *net) 1039 { 1040 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1041 1042 inet_ctl_sock_destroy(pn->v4_ctl_sk); 1043 } 1044 1045 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1046 { 1047 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1048 } 1049 1050 static struct pernet_operations dccp_v4_ops = { 1051 .init = dccp_v4_init_net, 1052 .exit = dccp_v4_exit_net, 1053 .exit_batch = dccp_v4_exit_batch, 1054 .id = &dccp_v4_pernet_id, 1055 .size = sizeof(struct dccp_v4_pernet), 1056 }; 1057 1058 static int __init dccp_v4_init(void) 1059 { 1060 int err = proto_register(&dccp_v4_prot, 1); 1061 1062 if (err) 1063 goto out; 1064 1065 inet_register_protosw(&dccp_v4_protosw); 1066 1067 err = register_pernet_subsys(&dccp_v4_ops); 1068 if (err) 1069 goto out_destroy_ctl_sock; 1070 1071 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1072 if (err) 1073 goto out_proto_unregister; 1074 1075 out: 1076 return err; 1077 out_proto_unregister: 1078 unregister_pernet_subsys(&dccp_v4_ops); 1079 out_destroy_ctl_sock: 1080 inet_unregister_protosw(&dccp_v4_protosw); 1081 proto_unregister(&dccp_v4_prot); 1082 goto out; 1083 } 1084 1085 static void __exit dccp_v4_exit(void) 1086 { 1087 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1088 unregister_pernet_subsys(&dccp_v4_ops); 1089 inet_unregister_protosw(&dccp_v4_protosw); 1090 proto_unregister(&dccp_v4_prot); 1091 } 1092 1093 module_init(dccp_v4_init); 1094 module_exit(dccp_v4_exit); 1095 1096 /* 1097 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1098 * values directly, Also cover the case where the protocol is not specified, 1099 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1100 */ 1101 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1102 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1103 MODULE_LICENSE("GPL"); 1104 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1105 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1106