1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/dccp/ipv4.c 4 * 5 * An implementation of the DCCP protocol 6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7 */ 8 9 #include <linux/dccp.h> 10 #include <linux/icmp.h> 11 #include <linux/slab.h> 12 #include <linux/module.h> 13 #include <linux/skbuff.h> 14 #include <linux/random.h> 15 16 #include <net/icmp.h> 17 #include <net/inet_common.h> 18 #include <net/inet_hashtables.h> 19 #include <net/inet_sock.h> 20 #include <net/protocol.h> 21 #include <net/sock.h> 22 #include <net/timewait_sock.h> 23 #include <net/tcp_states.h> 24 #include <net/xfrm.h> 25 #include <net/secure_seq.h> 26 27 #include "ackvec.h" 28 #include "ccid.h" 29 #include "dccp.h" 30 #include "feat.h" 31 32 /* 33 * The per-net dccp.v4_ctl_sk socket is used for responding to 34 * the Out-of-the-blue (OOTB) packets. A control sock will be created 35 * for this socket at the initialization time. 36 */ 37 38 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 39 { 40 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 41 struct inet_sock *inet = inet_sk(sk); 42 struct dccp_sock *dp = dccp_sk(sk); 43 __be16 orig_sport, orig_dport; 44 __be32 daddr, nexthop; 45 struct flowi4 *fl4; 46 struct rtable *rt; 47 int err; 48 struct ip_options_rcu *inet_opt; 49 50 dp->dccps_role = DCCP_ROLE_CLIENT; 51 52 if (addr_len < sizeof(struct sockaddr_in)) 53 return -EINVAL; 54 55 if (usin->sin_family != AF_INET) 56 return -EAFNOSUPPORT; 57 58 nexthop = daddr = usin->sin_addr.s_addr; 59 60 inet_opt = rcu_dereference_protected(inet->inet_opt, 61 lockdep_sock_is_held(sk)); 62 if (inet_opt != NULL && inet_opt->opt.srr) { 63 if (daddr == 0) 64 return -EINVAL; 65 nexthop = inet_opt->opt.faddr; 66 } 67 68 orig_sport = inet->inet_sport; 69 orig_dport = usin->sin_port; 70 fl4 = &inet->cork.fl.u.ip4; 71 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 72 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 73 IPPROTO_DCCP, 74 orig_sport, orig_dport, sk); 75 if (IS_ERR(rt)) 76 return PTR_ERR(rt); 77 78 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 79 ip_rt_put(rt); 80 return -ENETUNREACH; 81 } 82 83 if (inet_opt == NULL || !inet_opt->opt.srr) 84 daddr = fl4->daddr; 85 86 if (inet->inet_saddr == 0) 87 inet->inet_saddr = fl4->saddr; 88 sk_rcv_saddr_set(sk, inet->inet_saddr); 89 inet->inet_dport = usin->sin_port; 90 sk_daddr_set(sk, daddr); 91 92 inet_csk(sk)->icsk_ext_hdr_len = 0; 93 if (inet_opt) 94 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 95 /* 96 * Socket identity is still unknown (sport may be zero). 97 * However we set state to DCCP_REQUESTING and not releasing socket 98 * lock select source port, enter ourselves into the hash tables and 99 * complete initialization after this. 100 */ 101 dccp_set_state(sk, DCCP_REQUESTING); 102 err = inet_hash_connect(&dccp_death_row, sk); 103 if (err != 0) 104 goto failure; 105 106 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 107 inet->inet_sport, inet->inet_dport, sk); 108 if (IS_ERR(rt)) { 109 err = PTR_ERR(rt); 110 rt = NULL; 111 goto failure; 112 } 113 /* OK, now commit destination to socket. */ 114 sk_setup_caps(sk, &rt->dst); 115 116 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 117 inet->inet_daddr, 118 inet->inet_sport, 119 inet->inet_dport); 120 inet->inet_id = prandom_u32(); 121 122 err = dccp_connect(sk); 123 rt = NULL; 124 if (err != 0) 125 goto failure; 126 out: 127 return err; 128 failure: 129 /* 130 * This unhashes the socket and releases the local port, if necessary. 131 */ 132 dccp_set_state(sk, DCCP_CLOSED); 133 ip_rt_put(rt); 134 sk->sk_route_caps = 0; 135 inet->inet_dport = 0; 136 goto out; 137 } 138 EXPORT_SYMBOL_GPL(dccp_v4_connect); 139 140 /* 141 * This routine does path mtu discovery as defined in RFC1191. 142 */ 143 static inline void dccp_do_pmtu_discovery(struct sock *sk, 144 const struct iphdr *iph, 145 u32 mtu) 146 { 147 struct dst_entry *dst; 148 const struct inet_sock *inet = inet_sk(sk); 149 const struct dccp_sock *dp = dccp_sk(sk); 150 151 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 152 * send out by Linux are always < 576bytes so they should go through 153 * unfragmented). 154 */ 155 if (sk->sk_state == DCCP_LISTEN) 156 return; 157 158 dst = inet_csk_update_pmtu(sk, mtu); 159 if (!dst) 160 return; 161 162 /* Something is about to be wrong... Remember soft error 163 * for the case, if this connection will not able to recover. 164 */ 165 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 166 sk->sk_err_soft = EMSGSIZE; 167 168 mtu = dst_mtu(dst); 169 170 if (inet->pmtudisc != IP_PMTUDISC_DONT && 171 ip_sk_accept_pmtu(sk) && 172 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 173 dccp_sync_mss(sk, mtu); 174 175 /* 176 * From RFC 4340, sec. 14.1: 177 * 178 * DCCP-Sync packets are the best choice for upward 179 * probing, since DCCP-Sync probes do not risk application 180 * data loss. 181 */ 182 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 183 } /* else let the usual retransmit timer handle it */ 184 } 185 186 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 187 { 188 struct dst_entry *dst = __sk_dst_check(sk, 0); 189 190 if (dst) 191 dst->ops->redirect(dst, sk, skb); 192 } 193 194 void dccp_req_err(struct sock *sk, u64 seq) 195 { 196 struct request_sock *req = inet_reqsk(sk); 197 struct net *net = sock_net(sk); 198 199 /* 200 * ICMPs are not backlogged, hence we cannot get an established 201 * socket here. 202 */ 203 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 204 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 205 } else { 206 /* 207 * Still in RESPOND, just remove it silently. 208 * There is no good way to pass the error to the newly 209 * created socket, and POSIX does not want network 210 * errors returned from accept(). 211 */ 212 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 213 } 214 reqsk_put(req); 215 } 216 EXPORT_SYMBOL(dccp_req_err); 217 218 /* 219 * This routine is called by the ICMP module when it gets some sort of error 220 * condition. If err < 0 then the socket should be closed and the error 221 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 222 * After adjustment header points to the first 8 bytes of the tcp header. We 223 * need to find the appropriate port. 224 * 225 * The locking strategy used here is very "optimistic". When someone else 226 * accesses the socket the ICMP is just dropped and for some paths there is no 227 * check at all. A more general error queue to queue errors for later handling 228 * is probably better. 229 */ 230 static int dccp_v4_err(struct sk_buff *skb, u32 info) 231 { 232 const struct iphdr *iph = (struct iphdr *)skb->data; 233 const u8 offset = iph->ihl << 2; 234 const struct dccp_hdr *dh; 235 struct dccp_sock *dp; 236 struct inet_sock *inet; 237 const int type = icmp_hdr(skb)->type; 238 const int code = icmp_hdr(skb)->code; 239 struct sock *sk; 240 __u64 seq; 241 int err; 242 struct net *net = dev_net(skb->dev); 243 244 /* Only need dccph_dport & dccph_sport which are the first 245 * 4 bytes in dccp header. 246 * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us. 247 */ 248 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8); 249 BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8); 250 dh = (struct dccp_hdr *)(skb->data + offset); 251 252 sk = __inet_lookup_established(net, &dccp_hashinfo, 253 iph->daddr, dh->dccph_dport, 254 iph->saddr, ntohs(dh->dccph_sport), 255 inet_iif(skb), 0); 256 if (!sk) { 257 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 258 return -ENOENT; 259 } 260 261 if (sk->sk_state == DCCP_TIME_WAIT) { 262 inet_twsk_put(inet_twsk(sk)); 263 return 0; 264 } 265 seq = dccp_hdr_seq(dh); 266 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 267 dccp_req_err(sk, seq); 268 return 0; 269 } 270 271 bh_lock_sock(sk); 272 /* If too many ICMPs get dropped on busy 273 * servers this needs to be solved differently. 274 */ 275 if (sock_owned_by_user(sk)) 276 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 277 278 if (sk->sk_state == DCCP_CLOSED) 279 goto out; 280 281 dp = dccp_sk(sk); 282 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 283 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 284 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 285 goto out; 286 } 287 288 switch (type) { 289 case ICMP_REDIRECT: 290 if (!sock_owned_by_user(sk)) 291 dccp_do_redirect(skb, sk); 292 goto out; 293 case ICMP_SOURCE_QUENCH: 294 /* Just silently ignore these. */ 295 goto out; 296 case ICMP_PARAMETERPROB: 297 err = EPROTO; 298 break; 299 case ICMP_DEST_UNREACH: 300 if (code > NR_ICMP_UNREACH) 301 goto out; 302 303 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 304 if (!sock_owned_by_user(sk)) 305 dccp_do_pmtu_discovery(sk, iph, info); 306 goto out; 307 } 308 309 err = icmp_err_convert[code].errno; 310 break; 311 case ICMP_TIME_EXCEEDED: 312 err = EHOSTUNREACH; 313 break; 314 default: 315 goto out; 316 } 317 318 switch (sk->sk_state) { 319 case DCCP_REQUESTING: 320 case DCCP_RESPOND: 321 if (!sock_owned_by_user(sk)) { 322 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 323 sk->sk_err = err; 324 325 sk->sk_error_report(sk); 326 327 dccp_done(sk); 328 } else 329 sk->sk_err_soft = err; 330 goto out; 331 } 332 333 /* If we've already connected we will keep trying 334 * until we time out, or the user gives up. 335 * 336 * rfc1122 4.2.3.9 allows to consider as hard errors 337 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 338 * but it is obsoleted by pmtu discovery). 339 * 340 * Note, that in modern internet, where routing is unreliable 341 * and in each dark corner broken firewalls sit, sending random 342 * errors ordered by their masters even this two messages finally lose 343 * their original sense (even Linux sends invalid PORT_UNREACHs) 344 * 345 * Now we are in compliance with RFCs. 346 * --ANK (980905) 347 */ 348 349 inet = inet_sk(sk); 350 if (!sock_owned_by_user(sk) && inet->recverr) { 351 sk->sk_err = err; 352 sk->sk_error_report(sk); 353 } else /* Only an error on timeout */ 354 sk->sk_err_soft = err; 355 out: 356 bh_unlock_sock(sk); 357 sock_put(sk); 358 return 0; 359 } 360 361 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 362 __be32 src, __be32 dst) 363 { 364 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 365 } 366 367 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 368 { 369 const struct inet_sock *inet = inet_sk(sk); 370 struct dccp_hdr *dh = dccp_hdr(skb); 371 372 dccp_csum_outgoing(skb); 373 dh->dccph_checksum = dccp_v4_csum_finish(skb, 374 inet->inet_saddr, 375 inet->inet_daddr); 376 } 377 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 378 379 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 380 { 381 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 382 ip_hdr(skb)->saddr, 383 dccp_hdr(skb)->dccph_dport, 384 dccp_hdr(skb)->dccph_sport); 385 } 386 387 /* 388 * The three way handshake has completed - we got a valid ACK or DATAACK - 389 * now create the new socket. 390 * 391 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 392 */ 393 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 394 struct sk_buff *skb, 395 struct request_sock *req, 396 struct dst_entry *dst, 397 struct request_sock *req_unhash, 398 bool *own_req) 399 { 400 struct inet_request_sock *ireq; 401 struct inet_sock *newinet; 402 struct sock *newsk; 403 404 if (sk_acceptq_is_full(sk)) 405 goto exit_overflow; 406 407 newsk = dccp_create_openreq_child(sk, req, skb); 408 if (newsk == NULL) 409 goto exit_nonewsk; 410 411 newinet = inet_sk(newsk); 412 ireq = inet_rsk(req); 413 sk_daddr_set(newsk, ireq->ir_rmt_addr); 414 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 415 newinet->inet_saddr = ireq->ir_loc_addr; 416 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 417 newinet->mc_index = inet_iif(skb); 418 newinet->mc_ttl = ip_hdr(skb)->ttl; 419 newinet->inet_id = prandom_u32(); 420 421 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 422 goto put_and_exit; 423 424 sk_setup_caps(newsk, dst); 425 426 dccp_sync_mss(newsk, dst_mtu(dst)); 427 428 if (__inet_inherit_port(sk, newsk) < 0) 429 goto put_and_exit; 430 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 431 if (*own_req) 432 ireq->ireq_opt = NULL; 433 else 434 newinet->inet_opt = NULL; 435 return newsk; 436 437 exit_overflow: 438 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 439 exit_nonewsk: 440 dst_release(dst); 441 exit: 442 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 443 return NULL; 444 put_and_exit: 445 newinet->inet_opt = NULL; 446 inet_csk_prepare_forced_close(newsk); 447 dccp_done(newsk); 448 goto exit; 449 } 450 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 451 452 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 453 struct sk_buff *skb) 454 { 455 struct rtable *rt; 456 const struct iphdr *iph = ip_hdr(skb); 457 struct flowi4 fl4 = { 458 .flowi4_oif = inet_iif(skb), 459 .daddr = iph->saddr, 460 .saddr = iph->daddr, 461 .flowi4_tos = RT_CONN_FLAGS(sk), 462 .flowi4_proto = sk->sk_protocol, 463 .fl4_sport = dccp_hdr(skb)->dccph_dport, 464 .fl4_dport = dccp_hdr(skb)->dccph_sport, 465 }; 466 467 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 468 rt = ip_route_output_flow(net, &fl4, sk); 469 if (IS_ERR(rt)) { 470 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 471 return NULL; 472 } 473 474 return &rt->dst; 475 } 476 477 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 478 { 479 int err = -1; 480 struct sk_buff *skb; 481 struct dst_entry *dst; 482 struct flowi4 fl4; 483 484 dst = inet_csk_route_req(sk, &fl4, req); 485 if (dst == NULL) 486 goto out; 487 488 skb = dccp_make_response(sk, dst, req); 489 if (skb != NULL) { 490 const struct inet_request_sock *ireq = inet_rsk(req); 491 struct dccp_hdr *dh = dccp_hdr(skb); 492 493 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 494 ireq->ir_rmt_addr); 495 rcu_read_lock(); 496 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 497 ireq->ir_rmt_addr, 498 rcu_dereference(ireq->ireq_opt)); 499 rcu_read_unlock(); 500 err = net_xmit_eval(err); 501 } 502 503 out: 504 dst_release(dst); 505 return err; 506 } 507 508 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) 509 { 510 int err; 511 const struct iphdr *rxiph; 512 struct sk_buff *skb; 513 struct dst_entry *dst; 514 struct net *net = dev_net(skb_dst(rxskb)->dev); 515 struct sock *ctl_sk = net->dccp.v4_ctl_sk; 516 517 /* Never send a reset in response to a reset. */ 518 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 519 return; 520 521 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 522 return; 523 524 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 525 if (dst == NULL) 526 return; 527 528 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 529 if (skb == NULL) 530 goto out; 531 532 rxiph = ip_hdr(rxskb); 533 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 534 rxiph->daddr); 535 skb_dst_set(skb, dst_clone(dst)); 536 537 local_bh_disable(); 538 bh_lock_sock(ctl_sk); 539 err = ip_build_and_send_pkt(skb, ctl_sk, 540 rxiph->daddr, rxiph->saddr, NULL); 541 bh_unlock_sock(ctl_sk); 542 543 if (net_xmit_eval(err) == 0) { 544 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 545 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 546 } 547 local_bh_enable(); 548 out: 549 dst_release(dst); 550 } 551 552 static void dccp_v4_reqsk_destructor(struct request_sock *req) 553 { 554 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 555 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 556 } 557 558 void dccp_syn_ack_timeout(const struct request_sock *req) 559 { 560 } 561 EXPORT_SYMBOL(dccp_syn_ack_timeout); 562 563 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 564 .family = PF_INET, 565 .obj_size = sizeof(struct dccp_request_sock), 566 .rtx_syn_ack = dccp_v4_send_response, 567 .send_ack = dccp_reqsk_send_ack, 568 .destructor = dccp_v4_reqsk_destructor, 569 .send_reset = dccp_v4_ctl_send_reset, 570 .syn_ack_timeout = dccp_syn_ack_timeout, 571 }; 572 573 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 574 { 575 struct inet_request_sock *ireq; 576 struct request_sock *req; 577 struct dccp_request_sock *dreq; 578 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 579 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 580 581 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 582 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 583 return 0; /* discard, don't send a reset here */ 584 585 if (dccp_bad_service_code(sk, service)) { 586 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 587 goto drop; 588 } 589 /* 590 * TW buckets are converted to open requests without 591 * limitations, they conserve resources and peer is 592 * evidently real one. 593 */ 594 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 595 if (inet_csk_reqsk_queue_is_full(sk)) 596 goto drop; 597 598 if (sk_acceptq_is_full(sk)) 599 goto drop; 600 601 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 602 if (req == NULL) 603 goto drop; 604 605 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 606 goto drop_and_free; 607 608 dreq = dccp_rsk(req); 609 if (dccp_parse_options(sk, dreq, skb)) 610 goto drop_and_free; 611 612 if (security_inet_conn_request(sk, skb, req)) 613 goto drop_and_free; 614 615 ireq = inet_rsk(req); 616 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 617 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 618 ireq->ir_mark = inet_request_mark(sk, skb); 619 ireq->ireq_family = AF_INET; 620 ireq->ir_iif = sk->sk_bound_dev_if; 621 622 /* 623 * Step 3: Process LISTEN state 624 * 625 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 626 * 627 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 628 */ 629 dreq->dreq_isr = dcb->dccpd_seq; 630 dreq->dreq_gsr = dreq->dreq_isr; 631 dreq->dreq_iss = dccp_v4_init_sequence(skb); 632 dreq->dreq_gss = dreq->dreq_iss; 633 dreq->dreq_service = service; 634 635 if (dccp_v4_send_response(sk, req)) 636 goto drop_and_free; 637 638 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 639 reqsk_put(req); 640 return 0; 641 642 drop_and_free: 643 reqsk_free(req); 644 drop: 645 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 646 return -1; 647 } 648 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 649 650 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 651 { 652 struct dccp_hdr *dh = dccp_hdr(skb); 653 654 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 655 if (dccp_rcv_established(sk, skb, dh, skb->len)) 656 goto reset; 657 return 0; 658 } 659 660 /* 661 * Step 3: Process LISTEN state 662 * If P.type == Request or P contains a valid Init Cookie option, 663 * (* Must scan the packet's options to check for Init 664 * Cookies. Only Init Cookies are processed here, 665 * however; other options are processed in Step 8. This 666 * scan need only be performed if the endpoint uses Init 667 * Cookies *) 668 * (* Generate a new socket and switch to that socket *) 669 * Set S := new socket for this port pair 670 * S.state = RESPOND 671 * Choose S.ISS (initial seqno) or set from Init Cookies 672 * Initialize S.GAR := S.ISS 673 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 674 * Continue with S.state == RESPOND 675 * (* A Response packet will be generated in Step 11 *) 676 * Otherwise, 677 * Generate Reset(No Connection) unless P.type == Reset 678 * Drop packet and return 679 * 680 * NOTE: the check for the packet types is done in 681 * dccp_rcv_state_process 682 */ 683 684 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 685 goto reset; 686 return 0; 687 688 reset: 689 dccp_v4_ctl_send_reset(sk, skb); 690 kfree_skb(skb); 691 return 0; 692 } 693 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 694 695 /** 696 * dccp_invalid_packet - check for malformed packets 697 * @skb: Packet to validate 698 * 699 * Implements RFC 4340, 8.5: Step 1: Check header basics 700 * Packets that fail these checks are ignored and do not receive Resets. 701 */ 702 int dccp_invalid_packet(struct sk_buff *skb) 703 { 704 const struct dccp_hdr *dh; 705 unsigned int cscov; 706 u8 dccph_doff; 707 708 if (skb->pkt_type != PACKET_HOST) 709 return 1; 710 711 /* If the packet is shorter than 12 bytes, drop packet and return */ 712 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 713 DCCP_WARN("pskb_may_pull failed\n"); 714 return 1; 715 } 716 717 dh = dccp_hdr(skb); 718 719 /* If P.type is not understood, drop packet and return */ 720 if (dh->dccph_type >= DCCP_PKT_INVALID) { 721 DCCP_WARN("invalid packet type\n"); 722 return 1; 723 } 724 725 /* 726 * If P.Data Offset is too small for packet type, drop packet and return 727 */ 728 dccph_doff = dh->dccph_doff; 729 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 730 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 731 return 1; 732 } 733 /* 734 * If P.Data Offset is too too large for packet, drop packet and return 735 */ 736 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 737 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 738 return 1; 739 } 740 dh = dccp_hdr(skb); 741 /* 742 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 743 * has short sequence numbers), drop packet and return 744 */ 745 if ((dh->dccph_type < DCCP_PKT_DATA || 746 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 747 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 748 dccp_packet_name(dh->dccph_type)); 749 return 1; 750 } 751 752 /* 753 * If P.CsCov is too large for the packet size, drop packet and return. 754 * This must come _before_ checksumming (not as RFC 4340 suggests). 755 */ 756 cscov = dccp_csum_coverage(skb); 757 if (cscov > skb->len) { 758 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 759 dh->dccph_cscov, skb->len); 760 return 1; 761 } 762 763 /* If header checksum is incorrect, drop packet and return. 764 * (This step is completed in the AF-dependent functions.) */ 765 skb->csum = skb_checksum(skb, 0, cscov, 0); 766 767 return 0; 768 } 769 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 770 771 /* this is called when real data arrives */ 772 static int dccp_v4_rcv(struct sk_buff *skb) 773 { 774 const struct dccp_hdr *dh; 775 const struct iphdr *iph; 776 bool refcounted; 777 struct sock *sk; 778 int min_cov; 779 780 /* Step 1: Check header basics */ 781 782 if (dccp_invalid_packet(skb)) 783 goto discard_it; 784 785 iph = ip_hdr(skb); 786 /* Step 1: If header checksum is incorrect, drop packet and return */ 787 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 788 DCCP_WARN("dropped packet with invalid checksum\n"); 789 goto discard_it; 790 } 791 792 dh = dccp_hdr(skb); 793 794 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 795 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 796 797 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 798 dccp_packet_name(dh->dccph_type), 799 &iph->saddr, ntohs(dh->dccph_sport), 800 &iph->daddr, ntohs(dh->dccph_dport), 801 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 802 803 if (dccp_packet_without_ack(skb)) { 804 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 805 dccp_pr_debug_cat("\n"); 806 } else { 807 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 808 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 809 DCCP_SKB_CB(skb)->dccpd_ack_seq); 810 } 811 812 lookup: 813 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 814 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 815 if (!sk) { 816 dccp_pr_debug("failed to look up flow ID in table and " 817 "get corresponding socket\n"); 818 goto no_dccp_socket; 819 } 820 821 /* 822 * Step 2: 823 * ... or S.state == TIMEWAIT, 824 * Generate Reset(No Connection) unless P.type == Reset 825 * Drop packet and return 826 */ 827 if (sk->sk_state == DCCP_TIME_WAIT) { 828 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 829 inet_twsk_put(inet_twsk(sk)); 830 goto no_dccp_socket; 831 } 832 833 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 834 struct request_sock *req = inet_reqsk(sk); 835 struct sock *nsk; 836 837 sk = req->rsk_listener; 838 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 839 inet_csk_reqsk_queue_drop_and_put(sk, req); 840 goto lookup; 841 } 842 sock_hold(sk); 843 refcounted = true; 844 nsk = dccp_check_req(sk, skb, req); 845 if (!nsk) { 846 reqsk_put(req); 847 goto discard_and_relse; 848 } 849 if (nsk == sk) { 850 reqsk_put(req); 851 } else if (dccp_child_process(sk, nsk, skb)) { 852 dccp_v4_ctl_send_reset(sk, skb); 853 goto discard_and_relse; 854 } else { 855 sock_put(sk); 856 return 0; 857 } 858 } 859 /* 860 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 861 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 862 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 863 */ 864 min_cov = dccp_sk(sk)->dccps_pcrlen; 865 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 866 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 867 dh->dccph_cscov, min_cov); 868 /* FIXME: "Such packets SHOULD be reported using Data Dropped 869 * options (Section 11.7) with Drop Code 0, Protocol 870 * Constraints." */ 871 goto discard_and_relse; 872 } 873 874 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 875 goto discard_and_relse; 876 nf_reset_ct(skb); 877 878 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 879 880 no_dccp_socket: 881 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 882 goto discard_it; 883 /* 884 * Step 2: 885 * If no socket ... 886 * Generate Reset(No Connection) unless P.type == Reset 887 * Drop packet and return 888 */ 889 if (dh->dccph_type != DCCP_PKT_RESET) { 890 DCCP_SKB_CB(skb)->dccpd_reset_code = 891 DCCP_RESET_CODE_NO_CONNECTION; 892 dccp_v4_ctl_send_reset(sk, skb); 893 } 894 895 discard_it: 896 kfree_skb(skb); 897 return 0; 898 899 discard_and_relse: 900 if (refcounted) 901 sock_put(sk); 902 goto discard_it; 903 } 904 905 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 906 .queue_xmit = ip_queue_xmit, 907 .send_check = dccp_v4_send_check, 908 .rebuild_header = inet_sk_rebuild_header, 909 .conn_request = dccp_v4_conn_request, 910 .syn_recv_sock = dccp_v4_request_recv_sock, 911 .net_header_len = sizeof(struct iphdr), 912 .setsockopt = ip_setsockopt, 913 .getsockopt = ip_getsockopt, 914 .addr2sockaddr = inet_csk_addr2sockaddr, 915 .sockaddr_len = sizeof(struct sockaddr_in), 916 }; 917 918 static int dccp_v4_init_sock(struct sock *sk) 919 { 920 static __u8 dccp_v4_ctl_sock_initialized; 921 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 922 923 if (err == 0) { 924 if (unlikely(!dccp_v4_ctl_sock_initialized)) 925 dccp_v4_ctl_sock_initialized = 1; 926 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 927 } 928 929 return err; 930 } 931 932 static struct timewait_sock_ops dccp_timewait_sock_ops = { 933 .twsk_obj_size = sizeof(struct inet_timewait_sock), 934 }; 935 936 static struct proto dccp_v4_prot = { 937 .name = "DCCP", 938 .owner = THIS_MODULE, 939 .close = dccp_close, 940 .connect = dccp_v4_connect, 941 .disconnect = dccp_disconnect, 942 .ioctl = dccp_ioctl, 943 .init = dccp_v4_init_sock, 944 .setsockopt = dccp_setsockopt, 945 .getsockopt = dccp_getsockopt, 946 .sendmsg = dccp_sendmsg, 947 .recvmsg = dccp_recvmsg, 948 .backlog_rcv = dccp_v4_do_rcv, 949 .hash = inet_hash, 950 .unhash = inet_unhash, 951 .accept = inet_csk_accept, 952 .get_port = inet_csk_get_port, 953 .shutdown = dccp_shutdown, 954 .destroy = dccp_destroy_sock, 955 .orphan_count = &dccp_orphan_count, 956 .max_header = MAX_DCCP_HEADER, 957 .obj_size = sizeof(struct dccp_sock), 958 .slab_flags = SLAB_TYPESAFE_BY_RCU, 959 .rsk_prot = &dccp_request_sock_ops, 960 .twsk_prot = &dccp_timewait_sock_ops, 961 .h.hashinfo = &dccp_hashinfo, 962 }; 963 964 static const struct net_protocol dccp_v4_protocol = { 965 .handler = dccp_v4_rcv, 966 .err_handler = dccp_v4_err, 967 .no_policy = 1, 968 .netns_ok = 1, 969 .icmp_strict_tag_validation = 1, 970 }; 971 972 static const struct proto_ops inet_dccp_ops = { 973 .family = PF_INET, 974 .owner = THIS_MODULE, 975 .release = inet_release, 976 .bind = inet_bind, 977 .connect = inet_stream_connect, 978 .socketpair = sock_no_socketpair, 979 .accept = inet_accept, 980 .getname = inet_getname, 981 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 982 .poll = dccp_poll, 983 .ioctl = inet_ioctl, 984 .gettstamp = sock_gettstamp, 985 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 986 .listen = inet_dccp_listen, 987 .shutdown = inet_shutdown, 988 .setsockopt = sock_common_setsockopt, 989 .getsockopt = sock_common_getsockopt, 990 .sendmsg = inet_sendmsg, 991 .recvmsg = sock_common_recvmsg, 992 .mmap = sock_no_mmap, 993 .sendpage = sock_no_sendpage, 994 }; 995 996 static struct inet_protosw dccp_v4_protosw = { 997 .type = SOCK_DCCP, 998 .protocol = IPPROTO_DCCP, 999 .prot = &dccp_v4_prot, 1000 .ops = &inet_dccp_ops, 1001 .flags = INET_PROTOSW_ICSK, 1002 }; 1003 1004 static int __net_init dccp_v4_init_net(struct net *net) 1005 { 1006 if (dccp_hashinfo.bhash == NULL) 1007 return -ESOCKTNOSUPPORT; 1008 1009 return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET, 1010 SOCK_DCCP, IPPROTO_DCCP, net); 1011 } 1012 1013 static void __net_exit dccp_v4_exit_net(struct net *net) 1014 { 1015 inet_ctl_sock_destroy(net->dccp.v4_ctl_sk); 1016 } 1017 1018 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1019 { 1020 inet_twsk_purge(&dccp_hashinfo, AF_INET); 1021 } 1022 1023 static struct pernet_operations dccp_v4_ops = { 1024 .init = dccp_v4_init_net, 1025 .exit = dccp_v4_exit_net, 1026 .exit_batch = dccp_v4_exit_batch, 1027 }; 1028 1029 static int __init dccp_v4_init(void) 1030 { 1031 int err = proto_register(&dccp_v4_prot, 1); 1032 1033 if (err) 1034 goto out; 1035 1036 inet_register_protosw(&dccp_v4_protosw); 1037 1038 err = register_pernet_subsys(&dccp_v4_ops); 1039 if (err) 1040 goto out_destroy_ctl_sock; 1041 1042 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1043 if (err) 1044 goto out_proto_unregister; 1045 1046 out: 1047 return err; 1048 out_proto_unregister: 1049 unregister_pernet_subsys(&dccp_v4_ops); 1050 out_destroy_ctl_sock: 1051 inet_unregister_protosw(&dccp_v4_protosw); 1052 proto_unregister(&dccp_v4_prot); 1053 goto out; 1054 } 1055 1056 static void __exit dccp_v4_exit(void) 1057 { 1058 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1059 unregister_pernet_subsys(&dccp_v4_ops); 1060 inet_unregister_protosw(&dccp_v4_protosw); 1061 proto_unregister(&dccp_v4_prot); 1062 } 1063 1064 module_init(dccp_v4_init); 1065 module_exit(dccp_v4_exit); 1066 1067 /* 1068 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1069 * values directly, Also cover the case where the protocol is not specified, 1070 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1071 */ 1072 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1073 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1074 MODULE_LICENSE("GPL"); 1075 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1076 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1077