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 #include <net/rstreason.h> 28 29 #include "ackvec.h" 30 #include "ccid.h" 31 #include "dccp.h" 32 #include "feat.h" 33 34 struct dccp_v4_pernet { 35 struct sock *v4_ctl_sk; 36 }; 37 38 static unsigned int dccp_v4_pernet_id __read_mostly; 39 40 /* 41 * The per-net v4_ctl_sk socket is used for responding to 42 * the Out-of-the-blue (OOTB) packets. A control sock will be created 43 * for this socket at the initialization time. 44 */ 45 46 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 47 { 48 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 49 struct inet_sock *inet = inet_sk(sk); 50 struct dccp_sock *dp = dccp_sk(sk); 51 __be16 orig_sport, orig_dport; 52 __be32 daddr, nexthop; 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 err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET); 95 if (err) { 96 ip_rt_put(rt); 97 return err; 98 } 99 } else { 100 sk_rcv_saddr_set(sk, inet->inet_saddr); 101 } 102 103 inet->inet_dport = usin->sin_port; 104 sk_daddr_set(sk, daddr); 105 106 inet_csk(sk)->icsk_ext_hdr_len = 0; 107 if (inet_opt) 108 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 109 /* 110 * Socket identity is still unknown (sport may be zero). 111 * However we set state to DCCP_REQUESTING and not releasing socket 112 * lock select source port, enter ourselves into the hash tables and 113 * complete initialization after this. 114 */ 115 dccp_set_state(sk, DCCP_REQUESTING); 116 err = inet_hash_connect(&dccp_death_row, sk); 117 if (err != 0) 118 goto failure; 119 120 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 121 inet->inet_sport, inet->inet_dport, sk); 122 if (IS_ERR(rt)) { 123 err = PTR_ERR(rt); 124 rt = NULL; 125 goto failure; 126 } 127 /* OK, now commit destination to socket. */ 128 sk_setup_caps(sk, &rt->dst); 129 130 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 131 inet->inet_daddr, 132 inet->inet_sport, 133 inet->inet_dport); 134 atomic_set(&inet->inet_id, get_random_u16()); 135 136 err = dccp_connect(sk); 137 rt = NULL; 138 if (err != 0) 139 goto failure; 140 out: 141 return err; 142 failure: 143 /* 144 * This unhashes the socket and releases the local port, if necessary. 145 */ 146 dccp_set_state(sk, DCCP_CLOSED); 147 inet_bhash2_reset_saddr(sk); 148 ip_rt_put(rt); 149 sk->sk_route_caps = 0; 150 inet->inet_dport = 0; 151 goto out; 152 } 153 EXPORT_SYMBOL_GPL(dccp_v4_connect); 154 155 /* 156 * This routine does path mtu discovery as defined in RFC1191. 157 */ 158 static inline void dccp_do_pmtu_discovery(struct sock *sk, 159 const struct iphdr *iph, 160 u32 mtu) 161 { 162 struct dst_entry *dst; 163 const struct inet_sock *inet = inet_sk(sk); 164 const struct dccp_sock *dp = dccp_sk(sk); 165 166 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 167 * send out by Linux are always < 576bytes so they should go through 168 * unfragmented). 169 */ 170 if (sk->sk_state == DCCP_LISTEN) 171 return; 172 173 dst = inet_csk_update_pmtu(sk, mtu); 174 if (!dst) 175 return; 176 177 /* Something is about to be wrong... Remember soft error 178 * for the case, if this connection will not able to recover. 179 */ 180 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 181 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE); 182 183 mtu = dst_mtu(dst); 184 185 if (inet->pmtudisc != IP_PMTUDISC_DONT && 186 ip_sk_accept_pmtu(sk) && 187 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 188 dccp_sync_mss(sk, mtu); 189 190 /* 191 * From RFC 4340, sec. 14.1: 192 * 193 * DCCP-Sync packets are the best choice for upward 194 * probing, since DCCP-Sync probes do not risk application 195 * data loss. 196 */ 197 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 198 } /* else let the usual retransmit timer handle it */ 199 } 200 201 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 202 { 203 struct dst_entry *dst = __sk_dst_check(sk, 0); 204 205 if (dst) 206 dst->ops->redirect(dst, sk, skb); 207 } 208 209 void dccp_req_err(struct sock *sk, u64 seq) 210 { 211 struct request_sock *req = inet_reqsk(sk); 212 struct net *net = sock_net(sk); 213 214 /* 215 * ICMPs are not backlogged, hence we cannot get an established 216 * socket here. 217 */ 218 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 219 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 220 } else { 221 /* 222 * Still in RESPOND, just remove it silently. 223 * There is no good way to pass the error to the newly 224 * created socket, and POSIX does not want network 225 * errors returned from accept(). 226 */ 227 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 228 } 229 reqsk_put(req); 230 } 231 EXPORT_SYMBOL(dccp_req_err); 232 233 /* 234 * This routine is called by the ICMP module when it gets some sort of error 235 * condition. If err < 0 then the socket should be closed and the error 236 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 237 * After adjustment header points to the first 8 bytes of the tcp header. We 238 * need to find the appropriate port. 239 * 240 * The locking strategy used here is very "optimistic". When someone else 241 * accesses the socket the ICMP is just dropped and for some paths there is no 242 * check at all. A more general error queue to queue errors for later handling 243 * is probably better. 244 */ 245 static int dccp_v4_err(struct sk_buff *skb, u32 info) 246 { 247 const struct iphdr *iph = (struct iphdr *)skb->data; 248 const u8 offset = iph->ihl << 2; 249 const struct dccp_hdr *dh; 250 struct dccp_sock *dp; 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 if (!pskb_may_pull(skb, offset + sizeof(*dh))) 259 return -EINVAL; 260 dh = (struct dccp_hdr *)(skb->data + offset); 261 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) 262 return -EINVAL; 263 iph = (struct iphdr *)skb->data; 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 WRITE_ONCE(sk->sk_err_soft, err); 344 } 345 goto out; 346 } 347 348 /* If we've already connected we will keep trying 349 * until we time out, or the user gives up. 350 * 351 * rfc1122 4.2.3.9 allows to consider as hard errors 352 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 353 * but it is obsoleted by pmtu discovery). 354 * 355 * Note, that in modern internet, where routing is unreliable 356 * and in each dark corner broken firewalls sit, sending random 357 * errors ordered by their masters even this two messages finally lose 358 * their original sense (even Linux sends invalid PORT_UNREACHs) 359 * 360 * Now we are in compliance with RFCs. 361 * --ANK (980905) 362 */ 363 364 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) { 365 sk->sk_err = err; 366 sk_error_report(sk); 367 } else { /* Only an error on timeout */ 368 WRITE_ONCE(sk->sk_err_soft, err); 369 } 370 out: 371 bh_unlock_sock(sk); 372 sock_put(sk); 373 return 0; 374 } 375 376 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 377 __be32 src, __be32 dst) 378 { 379 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 380 } 381 382 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 383 { 384 const struct inet_sock *inet = inet_sk(sk); 385 struct dccp_hdr *dh = dccp_hdr(skb); 386 387 dccp_csum_outgoing(skb); 388 dh->dccph_checksum = dccp_v4_csum_finish(skb, 389 inet->inet_saddr, 390 inet->inet_daddr); 391 } 392 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 393 394 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 395 { 396 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 397 ip_hdr(skb)->saddr, 398 dccp_hdr(skb)->dccph_dport, 399 dccp_hdr(skb)->dccph_sport); 400 } 401 402 /* 403 * The three way handshake has completed - we got a valid ACK or DATAACK - 404 * now create the new socket. 405 * 406 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 407 */ 408 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 409 struct sk_buff *skb, 410 struct request_sock *req, 411 struct dst_entry *dst, 412 struct request_sock *req_unhash, 413 bool *own_req) 414 { 415 struct inet_request_sock *ireq; 416 struct inet_sock *newinet; 417 struct sock *newsk; 418 419 if (sk_acceptq_is_full(sk)) 420 goto exit_overflow; 421 422 newsk = dccp_create_openreq_child(sk, req, skb); 423 if (newsk == NULL) 424 goto exit_nonewsk; 425 426 newinet = inet_sk(newsk); 427 ireq = inet_rsk(req); 428 sk_daddr_set(newsk, ireq->ir_rmt_addr); 429 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 430 newinet->inet_saddr = ireq->ir_loc_addr; 431 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 432 newinet->mc_index = inet_iif(skb); 433 newinet->mc_ttl = ip_hdr(skb)->ttl; 434 atomic_set(&newinet->inet_id, get_random_u16()); 435 436 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 437 goto put_and_exit; 438 439 sk_setup_caps(newsk, dst); 440 441 dccp_sync_mss(newsk, dst_mtu(dst)); 442 443 if (__inet_inherit_port(sk, newsk) < 0) 444 goto put_and_exit; 445 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 446 if (*own_req) 447 ireq->ireq_opt = NULL; 448 else 449 newinet->inet_opt = NULL; 450 return newsk; 451 452 exit_overflow: 453 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 454 exit_nonewsk: 455 dst_release(dst); 456 exit: 457 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 458 return NULL; 459 put_and_exit: 460 newinet->inet_opt = NULL; 461 inet_csk_prepare_forced_close(newsk); 462 dccp_done(newsk); 463 goto exit; 464 } 465 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 466 467 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 468 struct sk_buff *skb) 469 { 470 struct rtable *rt; 471 const struct iphdr *iph = ip_hdr(skb); 472 struct flowi4 fl4 = { 473 .flowi4_oif = inet_iif(skb), 474 .daddr = iph->saddr, 475 .saddr = iph->daddr, 476 .flowi4_tos = ip_sock_rt_tos(sk), 477 .flowi4_scope = ip_sock_rt_scope(sk), 478 .flowi4_proto = sk->sk_protocol, 479 .fl4_sport = dccp_hdr(skb)->dccph_dport, 480 .fl4_dport = dccp_hdr(skb)->dccph_sport, 481 }; 482 483 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 484 rt = ip_route_output_flow(net, &fl4, sk); 485 if (IS_ERR(rt)) { 486 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 487 return NULL; 488 } 489 490 return &rt->dst; 491 } 492 493 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 494 { 495 int err = -1; 496 struct sk_buff *skb; 497 struct dst_entry *dst; 498 struct flowi4 fl4; 499 500 dst = inet_csk_route_req(sk, &fl4, req); 501 if (dst == NULL) 502 goto out; 503 504 skb = dccp_make_response(sk, dst, req); 505 if (skb != NULL) { 506 const struct inet_request_sock *ireq = inet_rsk(req); 507 struct dccp_hdr *dh = dccp_hdr(skb); 508 509 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 510 ireq->ir_rmt_addr); 511 rcu_read_lock(); 512 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 513 ireq->ir_rmt_addr, 514 rcu_dereference(ireq->ireq_opt), 515 READ_ONCE(inet_sk(sk)->tos)); 516 rcu_read_unlock(); 517 err = net_xmit_eval(err); 518 } 519 520 out: 521 dst_release(dst); 522 return err; 523 } 524 525 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb, 526 enum sk_rst_reason reason) 527 { 528 int err; 529 const struct iphdr *rxiph; 530 struct sk_buff *skb; 531 struct dst_entry *dst; 532 struct net *net = dev_net(skb_dst(rxskb)->dev); 533 struct dccp_v4_pernet *pn; 534 struct sock *ctl_sk; 535 536 /* Never send a reset in response to a reset. */ 537 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 538 return; 539 540 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 541 return; 542 543 pn = net_generic(net, dccp_v4_pernet_id); 544 ctl_sk = pn->v4_ctl_sk; 545 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 546 if (dst == NULL) 547 return; 548 549 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 550 if (skb == NULL) 551 goto out; 552 553 rxiph = ip_hdr(rxskb); 554 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 555 rxiph->daddr); 556 skb_dst_set(skb, dst_clone(dst)); 557 558 local_bh_disable(); 559 bh_lock_sock(ctl_sk); 560 err = ip_build_and_send_pkt(skb, ctl_sk, 561 rxiph->daddr, rxiph->saddr, NULL, 562 inet_sk(ctl_sk)->tos); 563 bh_unlock_sock(ctl_sk); 564 565 if (net_xmit_eval(err) == 0) { 566 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 567 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 568 } 569 local_bh_enable(); 570 out: 571 dst_release(dst); 572 } 573 574 static void dccp_v4_reqsk_destructor(struct request_sock *req) 575 { 576 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 577 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 578 } 579 580 void dccp_syn_ack_timeout(const struct request_sock *req) 581 { 582 } 583 EXPORT_SYMBOL(dccp_syn_ack_timeout); 584 585 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 586 .family = PF_INET, 587 .obj_size = sizeof(struct dccp_request_sock), 588 .rtx_syn_ack = dccp_v4_send_response, 589 .send_ack = dccp_reqsk_send_ack, 590 .destructor = dccp_v4_reqsk_destructor, 591 .send_reset = dccp_v4_ctl_send_reset, 592 .syn_ack_timeout = dccp_syn_ack_timeout, 593 }; 594 595 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 596 { 597 struct inet_request_sock *ireq; 598 struct request_sock *req; 599 struct dccp_request_sock *dreq; 600 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 601 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 602 603 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 604 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 605 return 0; /* discard, don't send a reset here */ 606 607 if (dccp_bad_service_code(sk, service)) { 608 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 609 goto drop; 610 } 611 /* 612 * TW buckets are converted to open requests without 613 * limitations, they conserve resources and peer is 614 * evidently real one. 615 */ 616 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 617 if (inet_csk_reqsk_queue_is_full(sk)) 618 goto drop; 619 620 if (sk_acceptq_is_full(sk)) 621 goto drop; 622 623 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 624 if (req == NULL) 625 goto drop; 626 627 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 628 goto drop_and_free; 629 630 dreq = dccp_rsk(req); 631 if (dccp_parse_options(sk, dreq, skb)) 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 if (security_inet_conn_request(sk, skb, req)) 642 goto drop_and_free; 643 644 /* 645 * Step 3: Process LISTEN state 646 * 647 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 648 * 649 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 650 */ 651 dreq->dreq_isr = dcb->dccpd_seq; 652 dreq->dreq_gsr = dreq->dreq_isr; 653 dreq->dreq_iss = dccp_v4_init_sequence(skb); 654 dreq->dreq_gss = dreq->dreq_iss; 655 dreq->dreq_service = service; 656 657 if (dccp_v4_send_response(sk, req)) 658 goto drop_and_free; 659 660 inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT); 661 reqsk_put(req); 662 return 0; 663 664 drop_and_free: 665 reqsk_free(req); 666 drop: 667 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 668 return -1; 669 } 670 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 671 672 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 673 { 674 struct dccp_hdr *dh = dccp_hdr(skb); 675 676 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 677 if (dccp_rcv_established(sk, skb, dh, skb->len)) 678 goto reset; 679 return 0; 680 } 681 682 /* 683 * Step 3: Process LISTEN state 684 * If P.type == Request or P contains a valid Init Cookie option, 685 * (* Must scan the packet's options to check for Init 686 * Cookies. Only Init Cookies are processed here, 687 * however; other options are processed in Step 8. This 688 * scan need only be performed if the endpoint uses Init 689 * Cookies *) 690 * (* Generate a new socket and switch to that socket *) 691 * Set S := new socket for this port pair 692 * S.state = RESPOND 693 * Choose S.ISS (initial seqno) or set from Init Cookies 694 * Initialize S.GAR := S.ISS 695 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 696 * Continue with S.state == RESPOND 697 * (* A Response packet will be generated in Step 11 *) 698 * Otherwise, 699 * Generate Reset(No Connection) unless P.type == Reset 700 * Drop packet and return 701 * 702 * NOTE: the check for the packet types is done in 703 * dccp_rcv_state_process 704 */ 705 706 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 707 goto reset; 708 return 0; 709 710 reset: 711 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 712 kfree_skb(skb); 713 return 0; 714 } 715 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 716 717 /** 718 * dccp_invalid_packet - check for malformed packets 719 * @skb: Packet to validate 720 * 721 * Implements RFC 4340, 8.5: Step 1: Check header basics 722 * Packets that fail these checks are ignored and do not receive Resets. 723 */ 724 int dccp_invalid_packet(struct sk_buff *skb) 725 { 726 const struct dccp_hdr *dh; 727 unsigned int cscov; 728 u8 dccph_doff; 729 730 if (skb->pkt_type != PACKET_HOST) 731 return 1; 732 733 /* If the packet is shorter than 12 bytes, drop packet and return */ 734 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 735 DCCP_WARN("pskb_may_pull failed\n"); 736 return 1; 737 } 738 739 dh = dccp_hdr(skb); 740 741 /* If P.type is not understood, drop packet and return */ 742 if (dh->dccph_type >= DCCP_PKT_INVALID) { 743 DCCP_WARN("invalid packet type\n"); 744 return 1; 745 } 746 747 /* 748 * If P.Data Offset is too small for packet type, drop packet and return 749 */ 750 dccph_doff = dh->dccph_doff; 751 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 752 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 753 return 1; 754 } 755 /* 756 * If P.Data Offset is too large for packet, drop packet and return 757 */ 758 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 759 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 760 return 1; 761 } 762 dh = dccp_hdr(skb); 763 /* 764 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 765 * has short sequence numbers), drop packet and return 766 */ 767 if ((dh->dccph_type < DCCP_PKT_DATA || 768 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 769 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 770 dccp_packet_name(dh->dccph_type)); 771 return 1; 772 } 773 774 /* 775 * If P.CsCov is too large for the packet size, drop packet and return. 776 * This must come _before_ checksumming (not as RFC 4340 suggests). 777 */ 778 cscov = dccp_csum_coverage(skb); 779 if (cscov > skb->len) { 780 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 781 dh->dccph_cscov, skb->len); 782 return 1; 783 } 784 785 /* If header checksum is incorrect, drop packet and return. 786 * (This step is completed in the AF-dependent functions.) */ 787 skb->csum = skb_checksum(skb, 0, cscov, 0); 788 789 return 0; 790 } 791 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 792 793 /* this is called when real data arrives */ 794 static int dccp_v4_rcv(struct sk_buff *skb) 795 { 796 const struct dccp_hdr *dh; 797 const struct iphdr *iph; 798 bool refcounted; 799 struct sock *sk; 800 int min_cov; 801 802 /* Step 1: Check header basics */ 803 804 if (dccp_invalid_packet(skb)) 805 goto discard_it; 806 807 iph = ip_hdr(skb); 808 /* Step 1: If header checksum is incorrect, drop packet and return */ 809 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 810 DCCP_WARN("dropped packet with invalid checksum\n"); 811 goto discard_it; 812 } 813 814 dh = dccp_hdr(skb); 815 816 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 817 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 818 819 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 820 dccp_packet_name(dh->dccph_type), 821 &iph->saddr, ntohs(dh->dccph_sport), 822 &iph->daddr, ntohs(dh->dccph_dport), 823 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 824 825 if (dccp_packet_without_ack(skb)) { 826 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 827 dccp_pr_debug_cat("\n"); 828 } else { 829 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 830 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 831 DCCP_SKB_CB(skb)->dccpd_ack_seq); 832 } 833 834 lookup: 835 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 836 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 837 if (!sk) { 838 dccp_pr_debug("failed to look up flow ID in table and " 839 "get corresponding socket\n"); 840 goto no_dccp_socket; 841 } 842 843 /* 844 * Step 2: 845 * ... or S.state == TIMEWAIT, 846 * Generate Reset(No Connection) unless P.type == Reset 847 * Drop packet and return 848 */ 849 if (sk->sk_state == DCCP_TIME_WAIT) { 850 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 851 inet_twsk_put(inet_twsk(sk)); 852 goto no_dccp_socket; 853 } 854 855 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 856 struct request_sock *req = inet_reqsk(sk); 857 struct sock *nsk; 858 859 sk = req->rsk_listener; 860 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 861 inet_csk_reqsk_queue_drop_and_put(sk, req); 862 goto lookup; 863 } 864 sock_hold(sk); 865 refcounted = true; 866 nsk = dccp_check_req(sk, skb, req); 867 if (!nsk) { 868 reqsk_put(req); 869 goto discard_and_relse; 870 } 871 if (nsk == sk) { 872 reqsk_put(req); 873 } else if (dccp_child_process(sk, nsk, skb)) { 874 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 875 goto discard_and_relse; 876 } else { 877 sock_put(sk); 878 return 0; 879 } 880 } 881 /* 882 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 883 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 884 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 885 */ 886 min_cov = dccp_sk(sk)->dccps_pcrlen; 887 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 888 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 889 dh->dccph_cscov, min_cov); 890 /* FIXME: "Such packets SHOULD be reported using Data Dropped 891 * options (Section 11.7) with Drop Code 0, Protocol 892 * Constraints." */ 893 goto discard_and_relse; 894 } 895 896 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 897 goto discard_and_relse; 898 nf_reset_ct(skb); 899 900 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 901 902 no_dccp_socket: 903 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 904 goto discard_it; 905 /* 906 * Step 2: 907 * If no socket ... 908 * Generate Reset(No Connection) unless P.type == Reset 909 * Drop packet and return 910 */ 911 if (dh->dccph_type != DCCP_PKT_RESET) { 912 DCCP_SKB_CB(skb)->dccpd_reset_code = 913 DCCP_RESET_CODE_NO_CONNECTION; 914 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 915 } 916 917 discard_it: 918 kfree_skb(skb); 919 return 0; 920 921 discard_and_relse: 922 if (refcounted) 923 sock_put(sk); 924 goto discard_it; 925 } 926 927 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 928 .queue_xmit = ip_queue_xmit, 929 .send_check = dccp_v4_send_check, 930 .rebuild_header = inet_sk_rebuild_header, 931 .conn_request = dccp_v4_conn_request, 932 .syn_recv_sock = dccp_v4_request_recv_sock, 933 .net_header_len = sizeof(struct iphdr), 934 .setsockopt = ip_setsockopt, 935 .getsockopt = ip_getsockopt, 936 .addr2sockaddr = inet_csk_addr2sockaddr, 937 .sockaddr_len = sizeof(struct sockaddr_in), 938 }; 939 940 static int dccp_v4_init_sock(struct sock *sk) 941 { 942 static __u8 dccp_v4_ctl_sock_initialized; 943 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 944 945 if (err == 0) { 946 if (unlikely(!dccp_v4_ctl_sock_initialized)) 947 dccp_v4_ctl_sock_initialized = 1; 948 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 949 } 950 951 return err; 952 } 953 954 static struct timewait_sock_ops dccp_timewait_sock_ops = { 955 .twsk_obj_size = sizeof(struct inet_timewait_sock), 956 }; 957 958 static struct proto dccp_v4_prot = { 959 .name = "DCCP", 960 .owner = THIS_MODULE, 961 .close = dccp_close, 962 .connect = dccp_v4_connect, 963 .disconnect = dccp_disconnect, 964 .ioctl = dccp_ioctl, 965 .init = dccp_v4_init_sock, 966 .setsockopt = dccp_setsockopt, 967 .getsockopt = dccp_getsockopt, 968 .sendmsg = dccp_sendmsg, 969 .recvmsg = dccp_recvmsg, 970 .backlog_rcv = dccp_v4_do_rcv, 971 .hash = inet_hash, 972 .unhash = inet_unhash, 973 .accept = inet_csk_accept, 974 .get_port = inet_csk_get_port, 975 .shutdown = dccp_shutdown, 976 .destroy = dccp_destroy_sock, 977 .orphan_count = &dccp_orphan_count, 978 .max_header = MAX_DCCP_HEADER, 979 .obj_size = sizeof(struct dccp_sock), 980 .slab_flags = SLAB_TYPESAFE_BY_RCU, 981 .rsk_prot = &dccp_request_sock_ops, 982 .twsk_prot = &dccp_timewait_sock_ops, 983 .h.hashinfo = &dccp_hashinfo, 984 }; 985 986 static const struct net_protocol dccp_v4_protocol = { 987 .handler = dccp_v4_rcv, 988 .err_handler = dccp_v4_err, 989 .no_policy = 1, 990 .icmp_strict_tag_validation = 1, 991 }; 992 993 static const struct proto_ops inet_dccp_ops = { 994 .family = PF_INET, 995 .owner = THIS_MODULE, 996 .release = inet_release, 997 .bind = inet_bind, 998 .connect = inet_stream_connect, 999 .socketpair = sock_no_socketpair, 1000 .accept = inet_accept, 1001 .getname = inet_getname, 1002 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1003 .poll = dccp_poll, 1004 .ioctl = inet_ioctl, 1005 .gettstamp = sock_gettstamp, 1006 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1007 .listen = inet_dccp_listen, 1008 .shutdown = inet_shutdown, 1009 .setsockopt = sock_common_setsockopt, 1010 .getsockopt = sock_common_getsockopt, 1011 .sendmsg = inet_sendmsg, 1012 .recvmsg = sock_common_recvmsg, 1013 .mmap = sock_no_mmap, 1014 }; 1015 1016 static struct inet_protosw dccp_v4_protosw = { 1017 .type = SOCK_DCCP, 1018 .protocol = IPPROTO_DCCP, 1019 .prot = &dccp_v4_prot, 1020 .ops = &inet_dccp_ops, 1021 .flags = INET_PROTOSW_ICSK, 1022 }; 1023 1024 static int __net_init dccp_v4_init_net(struct net *net) 1025 { 1026 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1027 1028 if (dccp_hashinfo.bhash == NULL) 1029 return -ESOCKTNOSUPPORT; 1030 1031 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1032 SOCK_DCCP, IPPROTO_DCCP, net); 1033 } 1034 1035 static void __net_exit dccp_v4_exit_net(struct net *net) 1036 { 1037 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1038 1039 inet_ctl_sock_destroy(pn->v4_ctl_sk); 1040 } 1041 1042 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1043 { 1044 inet_twsk_purge(&dccp_hashinfo); 1045 } 1046 1047 static struct pernet_operations dccp_v4_ops = { 1048 .init = dccp_v4_init_net, 1049 .exit = dccp_v4_exit_net, 1050 .exit_batch = dccp_v4_exit_batch, 1051 .id = &dccp_v4_pernet_id, 1052 .size = sizeof(struct dccp_v4_pernet), 1053 }; 1054 1055 static int __init dccp_v4_init(void) 1056 { 1057 int err = proto_register(&dccp_v4_prot, 1); 1058 1059 if (err) 1060 goto out; 1061 1062 inet_register_protosw(&dccp_v4_protosw); 1063 1064 err = register_pernet_subsys(&dccp_v4_ops); 1065 if (err) 1066 goto out_destroy_ctl_sock; 1067 1068 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1069 if (err) 1070 goto out_proto_unregister; 1071 1072 out: 1073 return err; 1074 out_proto_unregister: 1075 unregister_pernet_subsys(&dccp_v4_ops); 1076 out_destroy_ctl_sock: 1077 inet_unregister_protosw(&dccp_v4_protosw); 1078 proto_unregister(&dccp_v4_prot); 1079 goto out; 1080 } 1081 1082 static void __exit dccp_v4_exit(void) 1083 { 1084 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1085 unregister_pernet_subsys(&dccp_v4_ops); 1086 inet_unregister_protosw(&dccp_v4_protosw); 1087 proto_unregister(&dccp_v4_prot); 1088 } 1089 1090 module_init(dccp_v4_init); 1091 module_exit(dccp_v4_exit); 1092 1093 /* 1094 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1095 * values directly, Also cover the case where the protocol is not specified, 1096 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1097 */ 1098 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1099 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1100 MODULE_LICENSE("GPL"); 1101 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1102 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1103