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_bind_hashbucket *prev_addr_hashbucket = NULL; 49 __be32 daddr, nexthop, prev_sk_rcv_saddr; 50 struct inet_sock *inet = inet_sk(sk); 51 struct dccp_sock *dp = dccp_sk(sk); 52 __be16 orig_sport, orig_dport; 53 struct flowi4 *fl4; 54 struct rtable *rt; 55 int err; 56 struct ip_options_rcu *inet_opt; 57 58 dp->dccps_role = DCCP_ROLE_CLIENT; 59 60 if (addr_len < sizeof(struct sockaddr_in)) 61 return -EINVAL; 62 63 if (usin->sin_family != AF_INET) 64 return -EAFNOSUPPORT; 65 66 nexthop = daddr = usin->sin_addr.s_addr; 67 68 inet_opt = rcu_dereference_protected(inet->inet_opt, 69 lockdep_sock_is_held(sk)); 70 if (inet_opt != NULL && inet_opt->opt.srr) { 71 if (daddr == 0) 72 return -EINVAL; 73 nexthop = inet_opt->opt.faddr; 74 } 75 76 orig_sport = inet->inet_sport; 77 orig_dport = usin->sin_port; 78 fl4 = &inet->cork.fl.u.ip4; 79 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 80 sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport, 81 orig_dport, sk); 82 if (IS_ERR(rt)) 83 return PTR_ERR(rt); 84 85 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 86 ip_rt_put(rt); 87 return -ENETUNREACH; 88 } 89 90 if (inet_opt == NULL || !inet_opt->opt.srr) 91 daddr = fl4->daddr; 92 93 if (inet->inet_saddr == 0) { 94 if (inet_csk(sk)->icsk_bind2_hash) { 95 prev_addr_hashbucket = 96 inet_bhashfn_portaddr(&dccp_hashinfo, sk, 97 sock_net(sk), 98 inet->inet_num); 99 prev_sk_rcv_saddr = sk->sk_rcv_saddr; 100 } 101 inet->inet_saddr = fl4->saddr; 102 } 103 104 sk_rcv_saddr_set(sk, inet->inet_saddr); 105 106 if (prev_addr_hashbucket) { 107 err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk); 108 if (err) { 109 inet->inet_saddr = 0; 110 sk_rcv_saddr_set(sk, prev_sk_rcv_saddr); 111 ip_rt_put(rt); 112 return err; 113 } 114 } 115 116 inet->inet_dport = usin->sin_port; 117 sk_daddr_set(sk, daddr); 118 119 inet_csk(sk)->icsk_ext_hdr_len = 0; 120 if (inet_opt) 121 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 122 /* 123 * Socket identity is still unknown (sport may be zero). 124 * However we set state to DCCP_REQUESTING and not releasing socket 125 * lock select source port, enter ourselves into the hash tables and 126 * complete initialization after this. 127 */ 128 dccp_set_state(sk, DCCP_REQUESTING); 129 err = inet_hash_connect(&dccp_death_row, sk); 130 if (err != 0) 131 goto failure; 132 133 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 134 inet->inet_sport, inet->inet_dport, sk); 135 if (IS_ERR(rt)) { 136 err = PTR_ERR(rt); 137 rt = NULL; 138 goto failure; 139 } 140 /* OK, now commit destination to socket. */ 141 sk_setup_caps(sk, &rt->dst); 142 143 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 144 inet->inet_daddr, 145 inet->inet_sport, 146 inet->inet_dport); 147 inet->inet_id = get_random_u16(); 148 149 err = dccp_connect(sk); 150 rt = NULL; 151 if (err != 0) 152 goto failure; 153 out: 154 return err; 155 failure: 156 /* 157 * This unhashes the socket and releases the local port, if necessary. 158 */ 159 dccp_set_state(sk, DCCP_CLOSED); 160 ip_rt_put(rt); 161 sk->sk_route_caps = 0; 162 inet->inet_dport = 0; 163 goto out; 164 } 165 EXPORT_SYMBOL_GPL(dccp_v4_connect); 166 167 /* 168 * This routine does path mtu discovery as defined in RFC1191. 169 */ 170 static inline void dccp_do_pmtu_discovery(struct sock *sk, 171 const struct iphdr *iph, 172 u32 mtu) 173 { 174 struct dst_entry *dst; 175 const struct inet_sock *inet = inet_sk(sk); 176 const struct dccp_sock *dp = dccp_sk(sk); 177 178 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 179 * send out by Linux are always < 576bytes so they should go through 180 * unfragmented). 181 */ 182 if (sk->sk_state == DCCP_LISTEN) 183 return; 184 185 dst = inet_csk_update_pmtu(sk, mtu); 186 if (!dst) 187 return; 188 189 /* Something is about to be wrong... Remember soft error 190 * for the case, if this connection will not able to recover. 191 */ 192 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 193 sk->sk_err_soft = EMSGSIZE; 194 195 mtu = dst_mtu(dst); 196 197 if (inet->pmtudisc != IP_PMTUDISC_DONT && 198 ip_sk_accept_pmtu(sk) && 199 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 200 dccp_sync_mss(sk, mtu); 201 202 /* 203 * From RFC 4340, sec. 14.1: 204 * 205 * DCCP-Sync packets are the best choice for upward 206 * probing, since DCCP-Sync probes do not risk application 207 * data loss. 208 */ 209 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 210 } /* else let the usual retransmit timer handle it */ 211 } 212 213 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 214 { 215 struct dst_entry *dst = __sk_dst_check(sk, 0); 216 217 if (dst) 218 dst->ops->redirect(dst, sk, skb); 219 } 220 221 void dccp_req_err(struct sock *sk, u64 seq) 222 { 223 struct request_sock *req = inet_reqsk(sk); 224 struct net *net = sock_net(sk); 225 226 /* 227 * ICMPs are not backlogged, hence we cannot get an established 228 * socket here. 229 */ 230 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 231 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 232 } else { 233 /* 234 * Still in RESPOND, just remove it silently. 235 * There is no good way to pass the error to the newly 236 * created socket, and POSIX does not want network 237 * errors returned from accept(). 238 */ 239 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 240 } 241 reqsk_put(req); 242 } 243 EXPORT_SYMBOL(dccp_req_err); 244 245 /* 246 * This routine is called by the ICMP module when it gets some sort of error 247 * condition. If err < 0 then the socket should be closed and the error 248 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 249 * After adjustment header points to the first 8 bytes of the tcp header. We 250 * need to find the appropriate port. 251 * 252 * The locking strategy used here is very "optimistic". When someone else 253 * accesses the socket the ICMP is just dropped and for some paths there is no 254 * check at all. A more general error queue to queue errors for later handling 255 * is probably better. 256 */ 257 static int dccp_v4_err(struct sk_buff *skb, u32 info) 258 { 259 const struct iphdr *iph = (struct iphdr *)skb->data; 260 const u8 offset = iph->ihl << 2; 261 const struct dccp_hdr *dh; 262 struct dccp_sock *dp; 263 struct inet_sock *inet; 264 const int type = icmp_hdr(skb)->type; 265 const int code = icmp_hdr(skb)->code; 266 struct sock *sk; 267 __u64 seq; 268 int err; 269 struct net *net = dev_net(skb->dev); 270 271 /* Only need dccph_dport & dccph_sport which are the first 272 * 4 bytes in dccp header. 273 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 274 */ 275 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 276 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 277 dh = (struct dccp_hdr *)(skb->data + offset); 278 279 sk = __inet_lookup_established(net, &dccp_hashinfo, 280 iph->daddr, dh->dccph_dport, 281 iph->saddr, ntohs(dh->dccph_sport), 282 inet_iif(skb), 0); 283 if (!sk) { 284 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 285 return -ENOENT; 286 } 287 288 if (sk->sk_state == DCCP_TIME_WAIT) { 289 inet_twsk_put(inet_twsk(sk)); 290 return 0; 291 } 292 seq = dccp_hdr_seq(dh); 293 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 294 dccp_req_err(sk, seq); 295 return 0; 296 } 297 298 bh_lock_sock(sk); 299 /* If too many ICMPs get dropped on busy 300 * servers this needs to be solved differently. 301 */ 302 if (sock_owned_by_user(sk)) 303 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 304 305 if (sk->sk_state == DCCP_CLOSED) 306 goto out; 307 308 dp = dccp_sk(sk); 309 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 310 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 311 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 312 goto out; 313 } 314 315 switch (type) { 316 case ICMP_REDIRECT: 317 if (!sock_owned_by_user(sk)) 318 dccp_do_redirect(skb, sk); 319 goto out; 320 case ICMP_SOURCE_QUENCH: 321 /* Just silently ignore these. */ 322 goto out; 323 case ICMP_PARAMETERPROB: 324 err = EPROTO; 325 break; 326 case ICMP_DEST_UNREACH: 327 if (code > NR_ICMP_UNREACH) 328 goto out; 329 330 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 331 if (!sock_owned_by_user(sk)) 332 dccp_do_pmtu_discovery(sk, iph, info); 333 goto out; 334 } 335 336 err = icmp_err_convert[code].errno; 337 break; 338 case ICMP_TIME_EXCEEDED: 339 err = EHOSTUNREACH; 340 break; 341 default: 342 goto out; 343 } 344 345 switch (sk->sk_state) { 346 case DCCP_REQUESTING: 347 case DCCP_RESPOND: 348 if (!sock_owned_by_user(sk)) { 349 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 350 sk->sk_err = err; 351 352 sk_error_report(sk); 353 354 dccp_done(sk); 355 } else 356 sk->sk_err_soft = err; 357 goto out; 358 } 359 360 /* If we've already connected we will keep trying 361 * until we time out, or the user gives up. 362 * 363 * rfc1122 4.2.3.9 allows to consider as hard errors 364 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 365 * but it is obsoleted by pmtu discovery). 366 * 367 * Note, that in modern internet, where routing is unreliable 368 * and in each dark corner broken firewalls sit, sending random 369 * errors ordered by their masters even this two messages finally lose 370 * their original sense (even Linux sends invalid PORT_UNREACHs) 371 * 372 * Now we are in compliance with RFCs. 373 * --ANK (980905) 374 */ 375 376 inet = inet_sk(sk); 377 if (!sock_owned_by_user(sk) && inet->recverr) { 378 sk->sk_err = err; 379 sk_error_report(sk); 380 } else /* Only an error on timeout */ 381 sk->sk_err_soft = err; 382 out: 383 bh_unlock_sock(sk); 384 sock_put(sk); 385 return 0; 386 } 387 388 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 389 __be32 src, __be32 dst) 390 { 391 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 392 } 393 394 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 395 { 396 const struct inet_sock *inet = inet_sk(sk); 397 struct dccp_hdr *dh = dccp_hdr(skb); 398 399 dccp_csum_outgoing(skb); 400 dh->dccph_checksum = dccp_v4_csum_finish(skb, 401 inet->inet_saddr, 402 inet->inet_daddr); 403 } 404 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 405 406 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 407 { 408 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 409 ip_hdr(skb)->saddr, 410 dccp_hdr(skb)->dccph_dport, 411 dccp_hdr(skb)->dccph_sport); 412 } 413 414 /* 415 * The three way handshake has completed - we got a valid ACK or DATAACK - 416 * now create the new socket. 417 * 418 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 419 */ 420 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 421 struct sk_buff *skb, 422 struct request_sock *req, 423 struct dst_entry *dst, 424 struct request_sock *req_unhash, 425 bool *own_req) 426 { 427 struct inet_request_sock *ireq; 428 struct inet_sock *newinet; 429 struct sock *newsk; 430 431 if (sk_acceptq_is_full(sk)) 432 goto exit_overflow; 433 434 newsk = dccp_create_openreq_child(sk, req, skb); 435 if (newsk == NULL) 436 goto exit_nonewsk; 437 438 newinet = inet_sk(newsk); 439 ireq = inet_rsk(req); 440 sk_daddr_set(newsk, ireq->ir_rmt_addr); 441 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 442 newinet->inet_saddr = ireq->ir_loc_addr; 443 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 444 newinet->mc_index = inet_iif(skb); 445 newinet->mc_ttl = ip_hdr(skb)->ttl; 446 newinet->inet_id = get_random_u16(); 447 448 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 449 goto put_and_exit; 450 451 sk_setup_caps(newsk, dst); 452 453 dccp_sync_mss(newsk, dst_mtu(dst)); 454 455 if (__inet_inherit_port(sk, newsk) < 0) 456 goto put_and_exit; 457 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 458 if (*own_req) 459 ireq->ireq_opt = NULL; 460 else 461 newinet->inet_opt = NULL; 462 return newsk; 463 464 exit_overflow: 465 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 466 exit_nonewsk: 467 dst_release(dst); 468 exit: 469 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 470 return NULL; 471 put_and_exit: 472 newinet->inet_opt = NULL; 473 inet_csk_prepare_forced_close(newsk); 474 dccp_done(newsk); 475 goto exit; 476 } 477 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 478 479 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 480 struct sk_buff *skb) 481 { 482 struct rtable *rt; 483 const struct iphdr *iph = ip_hdr(skb); 484 struct flowi4 fl4 = { 485 .flowi4_oif = inet_iif(skb), 486 .daddr = iph->saddr, 487 .saddr = iph->daddr, 488 .flowi4_tos = RT_CONN_FLAGS(sk), 489 .flowi4_proto = sk->sk_protocol, 490 .fl4_sport = dccp_hdr(skb)->dccph_dport, 491 .fl4_dport = dccp_hdr(skb)->dccph_sport, 492 }; 493 494 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 495 rt = ip_route_output_flow(net, &fl4, sk); 496 if (IS_ERR(rt)) { 497 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 498 return NULL; 499 } 500 501 return &rt->dst; 502 } 503 504 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 505 { 506 int err = -1; 507 struct sk_buff *skb; 508 struct dst_entry *dst; 509 struct flowi4 fl4; 510 511 dst = inet_csk_route_req(sk, &fl4, req); 512 if (dst == NULL) 513 goto out; 514 515 skb = dccp_make_response(sk, dst, req); 516 if (skb != NULL) { 517 const struct inet_request_sock *ireq = inet_rsk(req); 518 struct dccp_hdr *dh = dccp_hdr(skb); 519 520 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 521 ireq->ir_rmt_addr); 522 rcu_read_lock(); 523 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 524 ireq->ir_rmt_addr, 525 rcu_dereference(ireq->ireq_opt), 526 inet_sk(sk)->tos); 527 rcu_read_unlock(); 528 err = net_xmit_eval(err); 529 } 530 531 out: 532 dst_release(dst); 533 return err; 534 } 535 536 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 537 { 538 int err; 539 const struct iphdr *rxiph; 540 struct sk_buff *skb; 541 struct dst_entry *dst; 542 struct net *net = dev_net(skb_dst(rxskb)->dev); 543 struct dccp_v4_pernet *pn; 544 struct sock *ctl_sk; 545 546 /* Never send a reset in response to a reset. */ 547 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 548 return; 549 550 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 551 return; 552 553 pn = net_generic(net, dccp_v4_pernet_id); 554 ctl_sk = pn->v4_ctl_sk; 555 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 556 if (dst == NULL) 557 return; 558 559 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 560 if (skb == NULL) 561 goto out; 562 563 rxiph = ip_hdr(rxskb); 564 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 565 rxiph->daddr); 566 skb_dst_set(skb, dst_clone(dst)); 567 568 local_bh_disable(); 569 bh_lock_sock(ctl_sk); 570 err = ip_build_and_send_pkt(skb, ctl_sk, 571 rxiph->daddr, rxiph->saddr, NULL, 572 inet_sk(ctl_sk)->tos); 573 bh_unlock_sock(ctl_sk); 574 575 if (net_xmit_eval(err) == 0) { 576 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 577 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 578 } 579 local_bh_enable(); 580 out: 581 dst_release(dst); 582 } 583 584 static void dccp_v4_reqsk_destructor(struct request_sock *req) 585 { 586 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 587 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 588 } 589 590 void dccp_syn_ack_timeout(const struct request_sock *req) 591 { 592 } 593 EXPORT_SYMBOL(dccp_syn_ack_timeout); 594 595 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 596 .family = PF_INET, 597 .obj_size = sizeof(struct dccp_request_sock), 598 .rtx_syn_ack = dccp_v4_send_response, 599 .send_ack = dccp_reqsk_send_ack, 600 .destructor = dccp_v4_reqsk_destructor, 601 .send_reset = dccp_v4_ctl_send_reset, 602 .syn_ack_timeout = dccp_syn_ack_timeout, 603 }; 604 605 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 606 { 607 struct inet_request_sock *ireq; 608 struct request_sock *req; 609 struct dccp_request_sock *dreq; 610 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 611 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 612 613 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 614 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 615 return 0; /* discard, don't send a reset here */ 616 617 if (dccp_bad_service_code(sk, service)) { 618 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 619 goto drop; 620 } 621 /* 622 * TW buckets are converted to open requests without 623 * limitations, they conserve resources and peer is 624 * evidently real one. 625 */ 626 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 627 if (inet_csk_reqsk_queue_is_full(sk)) 628 goto drop; 629 630 if (sk_acceptq_is_full(sk)) 631 goto drop; 632 633 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 634 if (req == NULL) 635 goto drop; 636 637 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 638 goto drop_and_free; 639 640 dreq = dccp_rsk(req); 641 if (dccp_parse_options(sk, dreq, skb)) 642 goto drop_and_free; 643 644 if (security_inet_conn_request(sk, skb, req)) 645 goto drop_and_free; 646 647 ireq = inet_rsk(req); 648 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 649 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 650 ireq->ir_mark = inet_request_mark(sk, skb); 651 ireq->ireq_family = AF_INET; 652 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if); 653 654 /* 655 * Step 3: Process LISTEN state 656 * 657 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 658 * 659 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 660 */ 661 dreq->dreq_isr = dcb->dccpd_seq; 662 dreq->dreq_gsr = dreq->dreq_isr; 663 dreq->dreq_iss = dccp_v4_init_sequence(skb); 664 dreq->dreq_gss = dreq->dreq_iss; 665 dreq->dreq_service = service; 666 667 if (dccp_v4_send_response(sk, req)) 668 goto drop_and_free; 669 670 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 671 reqsk_put(req); 672 return 0; 673 674 drop_and_free: 675 reqsk_free(req); 676 drop: 677 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 678 return -1; 679 } 680 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 681 682 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 683 { 684 struct dccp_hdr *dh = dccp_hdr(skb); 685 686 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 687 if (dccp_rcv_established(sk, skb, dh, skb->len)) 688 goto reset; 689 return 0; 690 } 691 692 /* 693 * Step 3: Process LISTEN state 694 * If P.type == Request or P contains a valid Init Cookie option, 695 * (* Must scan the packet's options to check for Init 696 * Cookies. Only Init Cookies are processed here, 697 * however; other options are processed in Step 8. This 698 * scan need only be performed if the endpoint uses Init 699 * Cookies *) 700 * (* Generate a new socket and switch to that socket *) 701 * Set S := new socket for this port pair 702 * S.state = RESPOND 703 * Choose S.ISS (initial seqno) or set from Init Cookies 704 * Initialize S.GAR := S.ISS 705 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 706 * Continue with S.state == RESPOND 707 * (* A Response packet will be generated in Step 11 *) 708 * Otherwise, 709 * Generate Reset(No Connection) unless P.type == Reset 710 * Drop packet and return 711 * 712 * NOTE: the check for the packet types is done in 713 * dccp_rcv_state_process 714 */ 715 716 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 717 goto reset; 718 return 0; 719 720 reset: 721 dccp_v4_ctl_send_reset(sk, skb); 722 kfree_skb(skb); 723 return 0; 724 } 725 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 726 727 /** 728 * dccp_invalid_packet - check for malformed packets 729 * @skb: Packet to validate 730 * 731 * Implements RFC 4340, 8.5: Step 1: Check header basics 732 * Packets that fail these checks are ignored and do not receive Resets. 733 */ 734 int dccp_invalid_packet(struct sk_buff *skb) 735 { 736 const struct dccp_hdr *dh; 737 unsigned int cscov; 738 u8 dccph_doff; 739 740 if (skb->pkt_type != PACKET_HOST) 741 return 1; 742 743 /* If the packet is shorter than 12 bytes, drop packet and return */ 744 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 745 DCCP_WARN("pskb_may_pull failed\n"); 746 return 1; 747 } 748 749 dh = dccp_hdr(skb); 750 751 /* If P.type is not understood, drop packet and return */ 752 if (dh->dccph_type >= DCCP_PKT_INVALID) { 753 DCCP_WARN("invalid packet type\n"); 754 return 1; 755 } 756 757 /* 758 * If P.Data Offset is too small for packet type, drop packet and return 759 */ 760 dccph_doff = dh->dccph_doff; 761 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 762 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 763 return 1; 764 } 765 /* 766 * If P.Data Offset is too large for packet, drop packet and return 767 */ 768 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 769 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 770 return 1; 771 } 772 dh = dccp_hdr(skb); 773 /* 774 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 775 * has short sequence numbers), drop packet and return 776 */ 777 if ((dh->dccph_type < DCCP_PKT_DATA || 778 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 779 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 780 dccp_packet_name(dh->dccph_type)); 781 return 1; 782 } 783 784 /* 785 * If P.CsCov is too large for the packet size, drop packet and return. 786 * This must come _before_ checksumming (not as RFC 4340 suggests). 787 */ 788 cscov = dccp_csum_coverage(skb); 789 if (cscov > skb->len) { 790 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 791 dh->dccph_cscov, skb->len); 792 return 1; 793 } 794 795 /* If header checksum is incorrect, drop packet and return. 796 * (This step is completed in the AF-dependent functions.) */ 797 skb->csum = skb_checksum(skb, 0, cscov, 0); 798 799 return 0; 800 } 801 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 802 803 /* this is called when real data arrives */ 804 static int dccp_v4_rcv(struct sk_buff *skb) 805 { 806 const struct dccp_hdr *dh; 807 const struct iphdr *iph; 808 bool refcounted; 809 struct sock *sk; 810 int min_cov; 811 812 /* Step 1: Check header basics */ 813 814 if (dccp_invalid_packet(skb)) 815 goto discard_it; 816 817 iph = ip_hdr(skb); 818 /* Step 1: If header checksum is incorrect, drop packet and return */ 819 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 820 DCCP_WARN("dropped packet with invalid checksum\n"); 821 goto discard_it; 822 } 823 824 dh = dccp_hdr(skb); 825 826 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 827 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 828 829 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 830 dccp_packet_name(dh->dccph_type), 831 &iph->saddr, ntohs(dh->dccph_sport), 832 &iph->daddr, ntohs(dh->dccph_dport), 833 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 834 835 if (dccp_packet_without_ack(skb)) { 836 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 837 dccp_pr_debug_cat("\n"); 838 } else { 839 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 840 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 841 DCCP_SKB_CB(skb)->dccpd_ack_seq); 842 } 843 844 lookup: 845 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 846 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 847 if (!sk) { 848 dccp_pr_debug("failed to look up flow ID in table and " 849 "get corresponding socket\n"); 850 goto no_dccp_socket; 851 } 852 853 /* 854 * Step 2: 855 * ... or S.state == TIMEWAIT, 856 * Generate Reset(No Connection) unless P.type == Reset 857 * Drop packet and return 858 */ 859 if (sk->sk_state == DCCP_TIME_WAIT) { 860 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 861 inet_twsk_put(inet_twsk(sk)); 862 goto no_dccp_socket; 863 } 864 865 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 866 struct request_sock *req = inet_reqsk(sk); 867 struct sock *nsk; 868 869 sk = req->rsk_listener; 870 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 871 inet_csk_reqsk_queue_drop_and_put(sk, req); 872 goto lookup; 873 } 874 sock_hold(sk); 875 refcounted = true; 876 nsk = dccp_check_req(sk, skb, req); 877 if (!nsk) { 878 reqsk_put(req); 879 goto discard_and_relse; 880 } 881 if (nsk == sk) { 882 reqsk_put(req); 883 } else if (dccp_child_process(sk, nsk, skb)) { 884 dccp_v4_ctl_send_reset(sk, skb); 885 goto discard_and_relse; 886 } else { 887 sock_put(sk); 888 return 0; 889 } 890 } 891 /* 892 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 893 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 894 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 895 */ 896 min_cov = dccp_sk(sk)->dccps_pcrlen; 897 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 898 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 899 dh->dccph_cscov, min_cov); 900 /* FIXME: "Such packets SHOULD be reported using Data Dropped 901 * options (Section 11.7) with Drop Code 0, Protocol 902 * Constraints." */ 903 goto discard_and_relse; 904 } 905 906 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 907 goto discard_and_relse; 908 nf_reset_ct(skb); 909 910 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 911 912 no_dccp_socket: 913 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 914 goto discard_it; 915 /* 916 * Step 2: 917 * If no socket ... 918 * Generate Reset(No Connection) unless P.type == Reset 919 * Drop packet and return 920 */ 921 if (dh->dccph_type != DCCP_PKT_RESET) { 922 DCCP_SKB_CB(skb)->dccpd_reset_code = 923 DCCP_RESET_CODE_NO_CONNECTION; 924 dccp_v4_ctl_send_reset(sk, skb); 925 } 926 927 discard_it: 928 kfree_skb(skb); 929 return 0; 930 931 discard_and_relse: 932 if (refcounted) 933 sock_put(sk); 934 goto discard_it; 935 } 936 937 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 938 .queue_xmit = ip_queue_xmit, 939 .send_check = dccp_v4_send_check, 940 .rebuild_header = inet_sk_rebuild_header, 941 .conn_request = dccp_v4_conn_request, 942 .syn_recv_sock = dccp_v4_request_recv_sock, 943 .net_header_len = sizeof(struct iphdr), 944 .setsockopt = ip_setsockopt, 945 .getsockopt = ip_getsockopt, 946 .addr2sockaddr = inet_csk_addr2sockaddr, 947 .sockaddr_len = sizeof(struct sockaddr_in), 948 }; 949 950 static int dccp_v4_init_sock(struct sock *sk) 951 { 952 static __u8 dccp_v4_ctl_sock_initialized; 953 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 954 955 if (err == 0) { 956 if (unlikely(!dccp_v4_ctl_sock_initialized)) 957 dccp_v4_ctl_sock_initialized = 1; 958 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 959 } 960 961 return err; 962 } 963 964 static struct timewait_sock_ops dccp_timewait_sock_ops = { 965 .twsk_obj_size = sizeof(struct inet_timewait_sock), 966 }; 967 968 static struct proto dccp_v4_prot = { 969 .name = "DCCP", 970 .owner = THIS_MODULE, 971 .close = dccp_close, 972 .connect = dccp_v4_connect, 973 .disconnect = dccp_disconnect, 974 .ioctl = dccp_ioctl, 975 .init = dccp_v4_init_sock, 976 .setsockopt = dccp_setsockopt, 977 .getsockopt = dccp_getsockopt, 978 .sendmsg = dccp_sendmsg, 979 .recvmsg = dccp_recvmsg, 980 .backlog_rcv = dccp_v4_do_rcv, 981 .hash = inet_hash, 982 .unhash = inet_unhash, 983 .accept = inet_csk_accept, 984 .get_port = inet_csk_get_port, 985 .shutdown = dccp_shutdown, 986 .destroy = dccp_destroy_sock, 987 .orphan_count = &dccp_orphan_count, 988 .max_header = MAX_DCCP_HEADER, 989 .obj_size = sizeof(struct dccp_sock), 990 .slab_flags = SLAB_TYPESAFE_BY_RCU, 991 .rsk_prot = &dccp_request_sock_ops, 992 .twsk_prot = &dccp_timewait_sock_ops, 993 .h.hashinfo = &dccp_hashinfo, 994 }; 995 996 static const struct net_protocol dccp_v4_protocol = { 997 .handler = dccp_v4_rcv, 998 .err_handler = dccp_v4_err, 999 .no_policy = 1, 1000 .icmp_strict_tag_validation = 1, 1001 }; 1002 1003 static const struct proto_ops inet_dccp_ops = { 1004 .family = PF_INET, 1005 .owner = THIS_MODULE, 1006 .release = inet_release, 1007 .bind = inet_bind, 1008 .connect = inet_stream_connect, 1009 .socketpair = sock_no_socketpair, 1010 .accept = inet_accept, 1011 .getname = inet_getname, 1012 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1013 .poll = dccp_poll, 1014 .ioctl = inet_ioctl, 1015 .gettstamp = sock_gettstamp, 1016 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1017 .listen = inet_dccp_listen, 1018 .shutdown = inet_shutdown, 1019 .setsockopt = sock_common_setsockopt, 1020 .getsockopt = sock_common_getsockopt, 1021 .sendmsg = inet_sendmsg, 1022 .recvmsg = sock_common_recvmsg, 1023 .mmap = sock_no_mmap, 1024 .sendpage = sock_no_sendpage, 1025 }; 1026 1027 static struct inet_protosw dccp_v4_protosw = { 1028 .type = SOCK_DCCP, 1029 .protocol = IPPROTO_DCCP, 1030 .prot = &dccp_v4_prot, 1031 .ops = &inet_dccp_ops, 1032 .flags = INET_PROTOSW_ICSK, 1033 }; 1034 1035 static int __net_init dccp_v4_init_net(struct net *net) 1036 { 1037 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1038 1039 if (dccp_hashinfo.bhash == NULL) 1040 return -ESOCKTNOSUPPORT; 1041 1042 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1043 SOCK_DCCP, IPPROTO_DCCP, net); 1044 } 1045 1046 static void __net_exit dccp_v4_exit_net(struct net *net) 1047 { 1048 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1049 1050 inet_ctl_sock_destroy(pn->v4_ctl_sk); 1051 } 1052 1053 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1054 { 1055 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1056 } 1057 1058 static struct pernet_operations dccp_v4_ops = { 1059 .init = dccp_v4_init_net, 1060 .exit = dccp_v4_exit_net, 1061 .exit_batch = dccp_v4_exit_batch, 1062 .id = &dccp_v4_pernet_id, 1063 .size = sizeof(struct dccp_v4_pernet), 1064 }; 1065 1066 static int __init dccp_v4_init(void) 1067 { 1068 int err = proto_register(&dccp_v4_prot, 1); 1069 1070 if (err) 1071 goto out; 1072 1073 inet_register_protosw(&dccp_v4_protosw); 1074 1075 err = register_pernet_subsys(&dccp_v4_ops); 1076 if (err) 1077 goto out_destroy_ctl_sock; 1078 1079 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1080 if (err) 1081 goto out_proto_unregister; 1082 1083 out: 1084 return err; 1085 out_proto_unregister: 1086 unregister_pernet_subsys(&dccp_v4_ops); 1087 out_destroy_ctl_sock: 1088 inet_unregister_protosw(&dccp_v4_protosw); 1089 proto_unregister(&dccp_v4_prot); 1090 goto out; 1091 } 1092 1093 static void __exit dccp_v4_exit(void) 1094 { 1095 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1096 unregister_pernet_subsys(&dccp_v4_ops); 1097 inet_unregister_protosw(&dccp_v4_protosw); 1098 proto_unregister(&dccp_v4_prot); 1099 } 1100 1101 module_init(dccp_v4_init); 1102 module_exit(dccp_v4_exit); 1103 1104 /* 1105 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1106 * values directly, Also cover the case where the protocol is not specified, 1107 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1108 */ 1109 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1110 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1111 MODULE_LICENSE("GPL"); 1112 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1113 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1114