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