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_dscp.h> 19 #include <net/inet_hashtables.h> 20 #include <net/inet_sock.h> 21 #include <net/protocol.h> 22 #include <net/sock.h> 23 #include <net/timewait_sock.h> 24 #include <net/tcp_states.h> 25 #include <net/xfrm.h> 26 #include <net/secure_seq.h> 27 #include <net/netns/generic.h> 28 #include <net/rstreason.h> 29 30 #include "ackvec.h" 31 #include "ccid.h" 32 #include "dccp.h" 33 #include "feat.h" 34 35 struct dccp_v4_pernet { 36 struct sock *v4_ctl_sk; 37 }; 38 39 static unsigned int dccp_v4_pernet_id __read_mostly; 40 41 /* 42 * The per-net v4_ctl_sk socket is used for responding to 43 * the Out-of-the-blue (OOTB) packets. A control sock will be created 44 * for this socket at the initialization time. 45 */ 46 47 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 48 { 49 const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 50 struct inet_sock *inet = inet_sk(sk); 51 struct dccp_sock *dp = dccp_sk(sk); 52 __be16 orig_sport, orig_dport; 53 __be32 daddr, nexthop; 54 struct flowi4 *fl4; 55 struct rtable *rt; 56 int err; 57 struct ip_options_rcu *inet_opt; 58 59 dp->dccps_role = DCCP_ROLE_CLIENT; 60 61 if (addr_len < sizeof(struct sockaddr_in)) 62 return -EINVAL; 63 64 if (usin->sin_family != AF_INET) 65 return -EAFNOSUPPORT; 66 67 nexthop = daddr = usin->sin_addr.s_addr; 68 69 inet_opt = rcu_dereference_protected(inet->inet_opt, 70 lockdep_sock_is_held(sk)); 71 if (inet_opt != NULL && inet_opt->opt.srr) { 72 if (daddr == 0) 73 return -EINVAL; 74 nexthop = inet_opt->opt.faddr; 75 } 76 77 orig_sport = inet->inet_sport; 78 orig_dport = usin->sin_port; 79 fl4 = &inet->cork.fl.u.ip4; 80 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 81 sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport, 82 orig_dport, sk); 83 if (IS_ERR(rt)) 84 return PTR_ERR(rt); 85 86 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 87 ip_rt_put(rt); 88 return -ENETUNREACH; 89 } 90 91 if (inet_opt == NULL || !inet_opt->opt.srr) 92 daddr = fl4->daddr; 93 94 if (inet->inet_saddr == 0) { 95 err = inet_bhash2_update_saddr(sk, &fl4->saddr, AF_INET); 96 if (err) { 97 ip_rt_put(rt); 98 return err; 99 } 100 } else { 101 sk_rcv_saddr_set(sk, inet->inet_saddr); 102 } 103 104 inet->inet_dport = usin->sin_port; 105 sk_daddr_set(sk, daddr); 106 107 inet_csk(sk)->icsk_ext_hdr_len = 0; 108 if (inet_opt) 109 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 110 /* 111 * Socket identity is still unknown (sport may be zero). 112 * However we set state to DCCP_REQUESTING and not releasing socket 113 * lock select source port, enter ourselves into the hash tables and 114 * complete initialization after this. 115 */ 116 dccp_set_state(sk, DCCP_REQUESTING); 117 err = inet_hash_connect(&dccp_death_row, sk); 118 if (err != 0) 119 goto failure; 120 121 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 122 inet->inet_sport, inet->inet_dport, sk); 123 if (IS_ERR(rt)) { 124 err = PTR_ERR(rt); 125 rt = NULL; 126 goto failure; 127 } 128 /* OK, now commit destination to socket. */ 129 sk_setup_caps(sk, &rt->dst); 130 131 dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr, 132 inet->inet_daddr, 133 inet->inet_sport, 134 inet->inet_dport); 135 atomic_set(&inet->inet_id, get_random_u16()); 136 137 err = dccp_connect(sk); 138 rt = NULL; 139 if (err != 0) 140 goto failure; 141 out: 142 return err; 143 failure: 144 /* 145 * This unhashes the socket and releases the local port, if necessary. 146 */ 147 dccp_set_state(sk, DCCP_CLOSED); 148 inet_bhash2_reset_saddr(sk); 149 ip_rt_put(rt); 150 sk->sk_route_caps = 0; 151 inet->inet_dport = 0; 152 goto out; 153 } 154 EXPORT_SYMBOL_GPL(dccp_v4_connect); 155 156 /* 157 * This routine does path mtu discovery as defined in RFC1191. 158 */ 159 static inline void dccp_do_pmtu_discovery(struct sock *sk, 160 const struct iphdr *iph, 161 u32 mtu) 162 { 163 struct dst_entry *dst; 164 const struct inet_sock *inet = inet_sk(sk); 165 const struct dccp_sock *dp = dccp_sk(sk); 166 167 /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs 168 * send out by Linux are always < 576bytes so they should go through 169 * unfragmented). 170 */ 171 if (sk->sk_state == DCCP_LISTEN) 172 return; 173 174 dst = inet_csk_update_pmtu(sk, mtu); 175 if (!dst) 176 return; 177 178 /* Something is about to be wrong... Remember soft error 179 * for the case, if this connection will not able to recover. 180 */ 181 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 182 WRITE_ONCE(sk->sk_err_soft, EMSGSIZE); 183 184 mtu = dst_mtu(dst); 185 186 if (inet->pmtudisc != IP_PMTUDISC_DONT && 187 ip_sk_accept_pmtu(sk) && 188 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 189 dccp_sync_mss(sk, mtu); 190 191 /* 192 * From RFC 4340, sec. 14.1: 193 * 194 * DCCP-Sync packets are the best choice for upward 195 * probing, since DCCP-Sync probes do not risk application 196 * data loss. 197 */ 198 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC); 199 } /* else let the usual retransmit timer handle it */ 200 } 201 202 static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk) 203 { 204 struct dst_entry *dst = __sk_dst_check(sk, 0); 205 206 if (dst) 207 dst->ops->redirect(dst, sk, skb); 208 } 209 210 void dccp_req_err(struct sock *sk, u64 seq) 211 { 212 struct request_sock *req = inet_reqsk(sk); 213 struct net *net = sock_net(sk); 214 215 /* 216 * ICMPs are not backlogged, hence we cannot get an established 217 * socket here. 218 */ 219 if (!between48(seq, dccp_rsk(req)->dreq_iss, dccp_rsk(req)->dreq_gss)) { 220 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 221 } else { 222 /* 223 * Still in RESPOND, just remove it silently. 224 * There is no good way to pass the error to the newly 225 * created socket, and POSIX does not want network 226 * errors returned from accept(). 227 */ 228 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 229 } 230 reqsk_put(req); 231 } 232 EXPORT_SYMBOL(dccp_req_err); 233 234 /* 235 * This routine is called by the ICMP module when it gets some sort of error 236 * condition. If err < 0 then the socket should be closed and the error 237 * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code. 238 * After adjustment header points to the first 8 bytes of the tcp header. We 239 * need to find the appropriate port. 240 * 241 * The locking strategy used here is very "optimistic". When someone else 242 * accesses the socket the ICMP is just dropped and for some paths there is no 243 * check at all. A more general error queue to queue errors for later handling 244 * is probably better. 245 */ 246 static int dccp_v4_err(struct sk_buff *skb, u32 info) 247 { 248 const struct iphdr *iph = (struct iphdr *)skb->data; 249 const u8 offset = iph->ihl << 2; 250 const struct dccp_hdr *dh; 251 struct dccp_sock *dp; 252 const int type = icmp_hdr(skb)->type; 253 const int code = icmp_hdr(skb)->code; 254 struct sock *sk; 255 __u64 seq; 256 int err; 257 struct net *net = dev_net(skb->dev); 258 259 if (!pskb_may_pull(skb, offset + sizeof(*dh))) 260 return -EINVAL; 261 dh = (struct dccp_hdr *)(skb->data + offset); 262 if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh))) 263 return -EINVAL; 264 iph = (struct iphdr *)skb->data; 265 dh = (struct dccp_hdr *)(skb->data + offset); 266 267 sk = __inet_lookup_established(net, &dccp_hashinfo, 268 iph->daddr, dh->dccph_dport, 269 iph->saddr, ntohs(dh->dccph_sport), 270 inet_iif(skb), 0); 271 if (!sk) { 272 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 273 return -ENOENT; 274 } 275 276 if (sk->sk_state == DCCP_TIME_WAIT) { 277 inet_twsk_put(inet_twsk(sk)); 278 return 0; 279 } 280 seq = dccp_hdr_seq(dh); 281 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 282 dccp_req_err(sk, seq); 283 return 0; 284 } 285 286 bh_lock_sock(sk); 287 /* If too many ICMPs get dropped on busy 288 * servers this needs to be solved differently. 289 */ 290 if (sock_owned_by_user(sk)) 291 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 292 293 if (sk->sk_state == DCCP_CLOSED) 294 goto out; 295 296 dp = dccp_sk(sk); 297 if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) && 298 !between48(seq, dp->dccps_awl, dp->dccps_awh)) { 299 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 300 goto out; 301 } 302 303 switch (type) { 304 case ICMP_REDIRECT: 305 if (!sock_owned_by_user(sk)) 306 dccp_do_redirect(skb, sk); 307 goto out; 308 case ICMP_SOURCE_QUENCH: 309 /* Just silently ignore these. */ 310 goto out; 311 case ICMP_PARAMETERPROB: 312 err = EPROTO; 313 break; 314 case ICMP_DEST_UNREACH: 315 if (code > NR_ICMP_UNREACH) 316 goto out; 317 318 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 319 if (!sock_owned_by_user(sk)) 320 dccp_do_pmtu_discovery(sk, iph, info); 321 goto out; 322 } 323 324 err = icmp_err_convert[code].errno; 325 break; 326 case ICMP_TIME_EXCEEDED: 327 err = EHOSTUNREACH; 328 break; 329 default: 330 goto out; 331 } 332 333 switch (sk->sk_state) { 334 case DCCP_REQUESTING: 335 case DCCP_RESPOND: 336 if (!sock_owned_by_user(sk)) { 337 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 338 sk->sk_err = err; 339 340 sk_error_report(sk); 341 342 dccp_done(sk); 343 } else { 344 WRITE_ONCE(sk->sk_err_soft, err); 345 } 346 goto out; 347 } 348 349 /* If we've already connected we will keep trying 350 * until we time out, or the user gives up. 351 * 352 * rfc1122 4.2.3.9 allows to consider as hard errors 353 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 354 * but it is obsoleted by pmtu discovery). 355 * 356 * Note, that in modern internet, where routing is unreliable 357 * and in each dark corner broken firewalls sit, sending random 358 * errors ordered by their masters even this two messages finally lose 359 * their original sense (even Linux sends invalid PORT_UNREACHs) 360 * 361 * Now we are in compliance with RFCs. 362 * --ANK (980905) 363 */ 364 365 if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) { 366 sk->sk_err = err; 367 sk_error_report(sk); 368 } else { /* Only an error on timeout */ 369 WRITE_ONCE(sk->sk_err_soft, err); 370 } 371 out: 372 bh_unlock_sock(sk); 373 sock_put(sk); 374 return 0; 375 } 376 377 static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb, 378 __be32 src, __be32 dst) 379 { 380 return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum); 381 } 382 383 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb) 384 { 385 const struct inet_sock *inet = inet_sk(sk); 386 struct dccp_hdr *dh = dccp_hdr(skb); 387 388 dccp_csum_outgoing(skb); 389 dh->dccph_checksum = dccp_v4_csum_finish(skb, 390 inet->inet_saddr, 391 inet->inet_daddr); 392 } 393 EXPORT_SYMBOL_GPL(dccp_v4_send_check); 394 395 static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb) 396 { 397 return secure_dccp_sequence_number(ip_hdr(skb)->daddr, 398 ip_hdr(skb)->saddr, 399 dccp_hdr(skb)->dccph_dport, 400 dccp_hdr(skb)->dccph_sport); 401 } 402 403 /* 404 * The three way handshake has completed - we got a valid ACK or DATAACK - 405 * now create the new socket. 406 * 407 * This is the equivalent of TCP's tcp_v4_syn_recv_sock 408 */ 409 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, 410 struct sk_buff *skb, 411 struct request_sock *req, 412 struct dst_entry *dst, 413 struct request_sock *req_unhash, 414 bool *own_req) 415 { 416 struct inet_request_sock *ireq; 417 struct inet_sock *newinet; 418 struct sock *newsk; 419 420 if (sk_acceptq_is_full(sk)) 421 goto exit_overflow; 422 423 newsk = dccp_create_openreq_child(sk, req, skb); 424 if (newsk == NULL) 425 goto exit_nonewsk; 426 427 newinet = inet_sk(newsk); 428 ireq = inet_rsk(req); 429 sk_daddr_set(newsk, ireq->ir_rmt_addr); 430 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 431 newinet->inet_saddr = ireq->ir_loc_addr; 432 RCU_INIT_POINTER(newinet->inet_opt, rcu_dereference(ireq->ireq_opt)); 433 newinet->mc_index = inet_iif(skb); 434 newinet->mc_ttl = ip_hdr(skb)->ttl; 435 atomic_set(&newinet->inet_id, get_random_u16()); 436 437 if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL) 438 goto put_and_exit; 439 440 sk_setup_caps(newsk, dst); 441 442 dccp_sync_mss(newsk, dst_mtu(dst)); 443 444 if (__inet_inherit_port(sk, newsk) < 0) 445 goto put_and_exit; 446 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL); 447 if (*own_req) 448 ireq->ireq_opt = NULL; 449 else 450 newinet->inet_opt = NULL; 451 return newsk; 452 453 exit_overflow: 454 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 455 exit_nonewsk: 456 dst_release(dst); 457 exit: 458 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 459 return NULL; 460 put_and_exit: 461 newinet->inet_opt = NULL; 462 inet_csk_prepare_forced_close(newsk); 463 dccp_done(newsk); 464 goto exit; 465 } 466 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock); 467 468 static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, 469 struct sk_buff *skb) 470 { 471 struct rtable *rt; 472 const struct iphdr *iph = ip_hdr(skb); 473 struct flowi4 fl4 = { 474 .flowi4_oif = inet_iif(skb), 475 .daddr = iph->saddr, 476 .saddr = iph->daddr, 477 .flowi4_tos = inet_dscp_to_dsfield(inet_sk_dscp(inet_sk(sk))), 478 .flowi4_scope = ip_sock_rt_scope(sk), 479 .flowi4_proto = sk->sk_protocol, 480 .fl4_sport = dccp_hdr(skb)->dccph_dport, 481 .fl4_dport = dccp_hdr(skb)->dccph_sport, 482 }; 483 484 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 485 rt = ip_route_output_flow(net, &fl4, sk); 486 if (IS_ERR(rt)) { 487 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 488 return NULL; 489 } 490 491 return &rt->dst; 492 } 493 494 static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req) 495 { 496 int err = -1; 497 struct sk_buff *skb; 498 struct dst_entry *dst; 499 struct flowi4 fl4; 500 501 dst = inet_csk_route_req(sk, &fl4, req); 502 if (dst == NULL) 503 goto out; 504 505 skb = dccp_make_response(sk, dst, req); 506 if (skb != NULL) { 507 const struct inet_request_sock *ireq = inet_rsk(req); 508 struct dccp_hdr *dh = dccp_hdr(skb); 509 510 dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr, 511 ireq->ir_rmt_addr); 512 rcu_read_lock(); 513 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 514 ireq->ir_rmt_addr, 515 rcu_dereference(ireq->ireq_opt), 516 READ_ONCE(inet_sk(sk)->tos)); 517 rcu_read_unlock(); 518 err = net_xmit_eval(err); 519 } 520 521 out: 522 dst_release(dst); 523 return err; 524 } 525 526 static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb, 527 enum sk_rst_reason reason) 528 { 529 int err; 530 const struct iphdr *rxiph; 531 struct sk_buff *skb; 532 struct dst_entry *dst; 533 struct net *net = dev_net(skb_dst(rxskb)->dev); 534 struct dccp_v4_pernet *pn; 535 struct sock *ctl_sk; 536 537 /* Never send a reset in response to a reset. */ 538 if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET) 539 return; 540 541 if (skb_rtable(rxskb)->rt_type != RTN_LOCAL) 542 return; 543 544 pn = net_generic(net, dccp_v4_pernet_id); 545 ctl_sk = pn->v4_ctl_sk; 546 dst = dccp_v4_route_skb(net, ctl_sk, rxskb); 547 if (dst == NULL) 548 return; 549 550 skb = dccp_ctl_make_reset(ctl_sk, rxskb); 551 if (skb == NULL) 552 goto out; 553 554 rxiph = ip_hdr(rxskb); 555 dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr, 556 rxiph->daddr); 557 skb_dst_set(skb, dst_clone(dst)); 558 559 local_bh_disable(); 560 bh_lock_sock(ctl_sk); 561 err = ip_build_and_send_pkt(skb, ctl_sk, 562 rxiph->daddr, rxiph->saddr, NULL, 563 inet_sk(ctl_sk)->tos); 564 bh_unlock_sock(ctl_sk); 565 566 if (net_xmit_eval(err) == 0) { 567 __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); 568 __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); 569 } 570 local_bh_enable(); 571 out: 572 dst_release(dst); 573 } 574 575 static void dccp_v4_reqsk_destructor(struct request_sock *req) 576 { 577 dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg); 578 kfree(rcu_dereference_protected(inet_rsk(req)->ireq_opt, 1)); 579 } 580 581 void dccp_syn_ack_timeout(const struct request_sock *req) 582 { 583 } 584 EXPORT_SYMBOL(dccp_syn_ack_timeout); 585 586 static struct request_sock_ops dccp_request_sock_ops __read_mostly = { 587 .family = PF_INET, 588 .obj_size = sizeof(struct dccp_request_sock), 589 .rtx_syn_ack = dccp_v4_send_response, 590 .send_ack = dccp_reqsk_send_ack, 591 .destructor = dccp_v4_reqsk_destructor, 592 .send_reset = dccp_v4_ctl_send_reset, 593 .syn_ack_timeout = dccp_syn_ack_timeout, 594 }; 595 596 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 597 { 598 struct inet_request_sock *ireq; 599 struct request_sock *req; 600 struct dccp_request_sock *dreq; 601 const __be32 service = dccp_hdr_request(skb)->dccph_req_service; 602 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); 603 604 /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */ 605 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 606 return 0; /* discard, don't send a reset here */ 607 608 if (dccp_bad_service_code(sk, service)) { 609 dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE; 610 goto drop; 611 } 612 /* 613 * TW buckets are converted to open requests without 614 * limitations, they conserve resources and peer is 615 * evidently real one. 616 */ 617 dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY; 618 if (inet_csk_reqsk_queue_is_full(sk)) 619 goto drop; 620 621 if (sk_acceptq_is_full(sk)) 622 goto drop; 623 624 req = inet_reqsk_alloc(&dccp_request_sock_ops, sk, true); 625 if (req == NULL) 626 goto drop; 627 628 if (dccp_reqsk_init(req, dccp_sk(sk), skb)) 629 goto drop_and_free; 630 631 dreq = dccp_rsk(req); 632 if (dccp_parse_options(sk, dreq, skb)) 633 goto drop_and_free; 634 635 ireq = inet_rsk(req); 636 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 637 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 638 ireq->ir_mark = inet_request_mark(sk, skb); 639 ireq->ireq_family = AF_INET; 640 ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if); 641 642 if (security_inet_conn_request(sk, skb, req)) 643 goto drop_and_free; 644 645 /* 646 * Step 3: Process LISTEN state 647 * 648 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie 649 * 650 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child(). 651 */ 652 dreq->dreq_isr = dcb->dccpd_seq; 653 dreq->dreq_gsr = dreq->dreq_isr; 654 dreq->dreq_iss = dccp_v4_init_sequence(skb); 655 dreq->dreq_gss = dreq->dreq_iss; 656 dreq->dreq_service = service; 657 658 if (dccp_v4_send_response(sk, req)) 659 goto drop_and_free; 660 661 if (unlikely(!inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT))) 662 reqsk_free(req); 663 else 664 reqsk_put(req); 665 666 return 0; 667 668 drop_and_free: 669 reqsk_free(req); 670 drop: 671 __DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS); 672 return -1; 673 } 674 EXPORT_SYMBOL_GPL(dccp_v4_conn_request); 675 676 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 677 { 678 struct dccp_hdr *dh = dccp_hdr(skb); 679 680 if (sk->sk_state == DCCP_OPEN) { /* Fast path */ 681 if (dccp_rcv_established(sk, skb, dh, skb->len)) 682 goto reset; 683 return 0; 684 } 685 686 /* 687 * Step 3: Process LISTEN state 688 * If P.type == Request or P contains a valid Init Cookie option, 689 * (* Must scan the packet's options to check for Init 690 * Cookies. Only Init Cookies are processed here, 691 * however; other options are processed in Step 8. This 692 * scan need only be performed if the endpoint uses Init 693 * Cookies *) 694 * (* Generate a new socket and switch to that socket *) 695 * Set S := new socket for this port pair 696 * S.state = RESPOND 697 * Choose S.ISS (initial seqno) or set from Init Cookies 698 * Initialize S.GAR := S.ISS 699 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies 700 * Continue with S.state == RESPOND 701 * (* A Response packet will be generated in Step 11 *) 702 * Otherwise, 703 * Generate Reset(No Connection) unless P.type == Reset 704 * Drop packet and return 705 * 706 * NOTE: the check for the packet types is done in 707 * dccp_rcv_state_process 708 */ 709 710 if (dccp_rcv_state_process(sk, skb, dh, skb->len)) 711 goto reset; 712 return 0; 713 714 reset: 715 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 716 kfree_skb(skb); 717 return 0; 718 } 719 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv); 720 721 /** 722 * dccp_invalid_packet - check for malformed packets 723 * @skb: Packet to validate 724 * 725 * Implements RFC 4340, 8.5: Step 1: Check header basics 726 * Packets that fail these checks are ignored and do not receive Resets. 727 */ 728 int dccp_invalid_packet(struct sk_buff *skb) 729 { 730 const struct dccp_hdr *dh; 731 unsigned int cscov; 732 u8 dccph_doff; 733 734 if (skb->pkt_type != PACKET_HOST) 735 return 1; 736 737 /* If the packet is shorter than 12 bytes, drop packet and return */ 738 if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) { 739 DCCP_WARN("pskb_may_pull failed\n"); 740 return 1; 741 } 742 743 dh = dccp_hdr(skb); 744 745 /* If P.type is not understood, drop packet and return */ 746 if (dh->dccph_type >= DCCP_PKT_INVALID) { 747 DCCP_WARN("invalid packet type\n"); 748 return 1; 749 } 750 751 /* 752 * If P.Data Offset is too small for packet type, drop packet and return 753 */ 754 dccph_doff = dh->dccph_doff; 755 if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { 756 DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); 757 return 1; 758 } 759 /* 760 * If P.Data Offset is too large for packet, drop packet and return 761 */ 762 if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { 763 DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); 764 return 1; 765 } 766 dh = dccp_hdr(skb); 767 /* 768 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet 769 * has short sequence numbers), drop packet and return 770 */ 771 if ((dh->dccph_type < DCCP_PKT_DATA || 772 dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) { 773 DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n", 774 dccp_packet_name(dh->dccph_type)); 775 return 1; 776 } 777 778 /* 779 * If P.CsCov is too large for the packet size, drop packet and return. 780 * This must come _before_ checksumming (not as RFC 4340 suggests). 781 */ 782 cscov = dccp_csum_coverage(skb); 783 if (cscov > skb->len) { 784 DCCP_WARN("P.CsCov %u exceeds packet length %d\n", 785 dh->dccph_cscov, skb->len); 786 return 1; 787 } 788 789 /* If header checksum is incorrect, drop packet and return. 790 * (This step is completed in the AF-dependent functions.) */ 791 skb->csum = skb_checksum(skb, 0, cscov, 0); 792 793 return 0; 794 } 795 EXPORT_SYMBOL_GPL(dccp_invalid_packet); 796 797 /* this is called when real data arrives */ 798 static int dccp_v4_rcv(struct sk_buff *skb) 799 { 800 const struct dccp_hdr *dh; 801 const struct iphdr *iph; 802 bool refcounted; 803 struct sock *sk; 804 int min_cov; 805 806 /* Step 1: Check header basics */ 807 808 if (dccp_invalid_packet(skb)) 809 goto discard_it; 810 811 iph = ip_hdr(skb); 812 /* Step 1: If header checksum is incorrect, drop packet and return */ 813 if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) { 814 DCCP_WARN("dropped packet with invalid checksum\n"); 815 goto discard_it; 816 } 817 818 dh = dccp_hdr(skb); 819 820 DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh); 821 DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type; 822 823 dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu", 824 dccp_packet_name(dh->dccph_type), 825 &iph->saddr, ntohs(dh->dccph_sport), 826 &iph->daddr, ntohs(dh->dccph_dport), 827 (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq); 828 829 if (dccp_packet_without_ack(skb)) { 830 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ; 831 dccp_pr_debug_cat("\n"); 832 } else { 833 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb); 834 dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long) 835 DCCP_SKB_CB(skb)->dccpd_ack_seq); 836 } 837 838 lookup: 839 sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh), 840 dh->dccph_sport, dh->dccph_dport, 0, &refcounted); 841 if (!sk) { 842 dccp_pr_debug("failed to look up flow ID in table and " 843 "get corresponding socket\n"); 844 goto no_dccp_socket; 845 } 846 847 /* 848 * Step 2: 849 * ... or S.state == TIMEWAIT, 850 * Generate Reset(No Connection) unless P.type == Reset 851 * Drop packet and return 852 */ 853 if (sk->sk_state == DCCP_TIME_WAIT) { 854 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n"); 855 inet_twsk_put(inet_twsk(sk)); 856 goto no_dccp_socket; 857 } 858 859 if (sk->sk_state == DCCP_NEW_SYN_RECV) { 860 struct request_sock *req = inet_reqsk(sk); 861 struct sock *nsk; 862 863 sk = req->rsk_listener; 864 if (unlikely(sk->sk_state != DCCP_LISTEN)) { 865 inet_csk_reqsk_queue_drop_and_put(sk, req); 866 goto lookup; 867 } 868 sock_hold(sk); 869 refcounted = true; 870 nsk = dccp_check_req(sk, skb, req); 871 if (!nsk) { 872 reqsk_put(req); 873 goto discard_and_relse; 874 } 875 if (nsk == sk) { 876 reqsk_put(req); 877 } else if (dccp_child_process(sk, nsk, skb)) { 878 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 879 goto discard_and_relse; 880 } else { 881 sock_put(sk); 882 return 0; 883 } 884 } 885 /* 886 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage 887 * o if MinCsCov = 0, only packets with CsCov = 0 are accepted 888 * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov 889 */ 890 min_cov = dccp_sk(sk)->dccps_pcrlen; 891 if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) { 892 dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n", 893 dh->dccph_cscov, min_cov); 894 /* FIXME: "Such packets SHOULD be reported using Data Dropped 895 * options (Section 11.7) with Drop Code 0, Protocol 896 * Constraints." */ 897 goto discard_and_relse; 898 } 899 900 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 901 goto discard_and_relse; 902 nf_reset_ct(skb); 903 904 return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4, refcounted); 905 906 no_dccp_socket: 907 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 908 goto discard_it; 909 /* 910 * Step 2: 911 * If no socket ... 912 * Generate Reset(No Connection) unless P.type == Reset 913 * Drop packet and return 914 */ 915 if (dh->dccph_type != DCCP_PKT_RESET) { 916 DCCP_SKB_CB(skb)->dccpd_reset_code = 917 DCCP_RESET_CODE_NO_CONNECTION; 918 dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED); 919 } 920 921 discard_it: 922 kfree_skb(skb); 923 return 0; 924 925 discard_and_relse: 926 if (refcounted) 927 sock_put(sk); 928 goto discard_it; 929 } 930 931 static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = { 932 .queue_xmit = ip_queue_xmit, 933 .send_check = dccp_v4_send_check, 934 .rebuild_header = inet_sk_rebuild_header, 935 .conn_request = dccp_v4_conn_request, 936 .syn_recv_sock = dccp_v4_request_recv_sock, 937 .net_header_len = sizeof(struct iphdr), 938 .setsockopt = ip_setsockopt, 939 .getsockopt = ip_getsockopt, 940 .addr2sockaddr = inet_csk_addr2sockaddr, 941 .sockaddr_len = sizeof(struct sockaddr_in), 942 }; 943 944 static int dccp_v4_init_sock(struct sock *sk) 945 { 946 static __u8 dccp_v4_ctl_sock_initialized; 947 int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized); 948 949 if (err == 0) { 950 if (unlikely(!dccp_v4_ctl_sock_initialized)) 951 dccp_v4_ctl_sock_initialized = 1; 952 inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops; 953 } 954 955 return err; 956 } 957 958 static struct timewait_sock_ops dccp_timewait_sock_ops = { 959 .twsk_obj_size = sizeof(struct inet_timewait_sock), 960 }; 961 962 static struct proto dccp_v4_prot = { 963 .name = "DCCP", 964 .owner = THIS_MODULE, 965 .close = dccp_close, 966 .connect = dccp_v4_connect, 967 .disconnect = dccp_disconnect, 968 .ioctl = dccp_ioctl, 969 .init = dccp_v4_init_sock, 970 .setsockopt = dccp_setsockopt, 971 .getsockopt = dccp_getsockopt, 972 .sendmsg = dccp_sendmsg, 973 .recvmsg = dccp_recvmsg, 974 .backlog_rcv = dccp_v4_do_rcv, 975 .hash = inet_hash, 976 .unhash = inet_unhash, 977 .accept = inet_csk_accept, 978 .get_port = inet_csk_get_port, 979 .shutdown = dccp_shutdown, 980 .destroy = dccp_destroy_sock, 981 .orphan_count = &dccp_orphan_count, 982 .max_header = MAX_DCCP_HEADER, 983 .obj_size = sizeof(struct dccp_sock), 984 .slab_flags = SLAB_TYPESAFE_BY_RCU, 985 .rsk_prot = &dccp_request_sock_ops, 986 .twsk_prot = &dccp_timewait_sock_ops, 987 .h.hashinfo = &dccp_hashinfo, 988 }; 989 990 static const struct net_protocol dccp_v4_protocol = { 991 .handler = dccp_v4_rcv, 992 .err_handler = dccp_v4_err, 993 .no_policy = 1, 994 .icmp_strict_tag_validation = 1, 995 }; 996 997 static const struct proto_ops inet_dccp_ops = { 998 .family = PF_INET, 999 .owner = THIS_MODULE, 1000 .release = inet_release, 1001 .bind = inet_bind, 1002 .connect = inet_stream_connect, 1003 .socketpair = sock_no_socketpair, 1004 .accept = inet_accept, 1005 .getname = inet_getname, 1006 /* FIXME: work on tcp_poll to rename it to inet_csk_poll */ 1007 .poll = dccp_poll, 1008 .ioctl = inet_ioctl, 1009 .gettstamp = sock_gettstamp, 1010 /* FIXME: work on inet_listen to rename it to sock_common_listen */ 1011 .listen = inet_dccp_listen, 1012 .shutdown = inet_shutdown, 1013 .setsockopt = sock_common_setsockopt, 1014 .getsockopt = sock_common_getsockopt, 1015 .sendmsg = inet_sendmsg, 1016 .recvmsg = sock_common_recvmsg, 1017 .mmap = sock_no_mmap, 1018 }; 1019 1020 static struct inet_protosw dccp_v4_protosw = { 1021 .type = SOCK_DCCP, 1022 .protocol = IPPROTO_DCCP, 1023 .prot = &dccp_v4_prot, 1024 .ops = &inet_dccp_ops, 1025 .flags = INET_PROTOSW_ICSK, 1026 }; 1027 1028 static int __net_init dccp_v4_init_net(struct net *net) 1029 { 1030 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1031 1032 if (dccp_hashinfo.bhash == NULL) 1033 return -ESOCKTNOSUPPORT; 1034 1035 return inet_ctl_sock_create(&pn->v4_ctl_sk, PF_INET, 1036 SOCK_DCCP, IPPROTO_DCCP, net); 1037 } 1038 1039 static void __net_exit dccp_v4_exit_net(struct net *net) 1040 { 1041 struct dccp_v4_pernet *pn = net_generic(net, dccp_v4_pernet_id); 1042 1043 inet_ctl_sock_destroy(pn->v4_ctl_sk); 1044 } 1045 1046 static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list) 1047 { 1048 inet_twsk_purge(&dccp_hashinfo); 1049 } 1050 1051 static struct pernet_operations dccp_v4_ops = { 1052 .init = dccp_v4_init_net, 1053 .exit = dccp_v4_exit_net, 1054 .exit_batch = dccp_v4_exit_batch, 1055 .id = &dccp_v4_pernet_id, 1056 .size = sizeof(struct dccp_v4_pernet), 1057 }; 1058 1059 static int __init dccp_v4_init(void) 1060 { 1061 int err = proto_register(&dccp_v4_prot, 1); 1062 1063 if (err) 1064 goto out; 1065 1066 inet_register_protosw(&dccp_v4_protosw); 1067 1068 err = register_pernet_subsys(&dccp_v4_ops); 1069 if (err) 1070 goto out_destroy_ctl_sock; 1071 1072 err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1073 if (err) 1074 goto out_proto_unregister; 1075 1076 out: 1077 return err; 1078 out_proto_unregister: 1079 unregister_pernet_subsys(&dccp_v4_ops); 1080 out_destroy_ctl_sock: 1081 inet_unregister_protosw(&dccp_v4_protosw); 1082 proto_unregister(&dccp_v4_prot); 1083 goto out; 1084 } 1085 1086 static void __exit dccp_v4_exit(void) 1087 { 1088 inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP); 1089 unregister_pernet_subsys(&dccp_v4_ops); 1090 inet_unregister_protosw(&dccp_v4_protosw); 1091 proto_unregister(&dccp_v4_prot); 1092 } 1093 1094 module_init(dccp_v4_init); 1095 module_exit(dccp_v4_exit); 1096 1097 /* 1098 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33) 1099 * values directly, Also cover the case where the protocol is not specified, 1100 * i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP 1101 */ 1102 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6); 1103 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6); 1104 MODULE_LICENSE("GPL"); 1105 MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>"); 1106 MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol"); 1107