31 */ 32 33#include "opt_compat.h" 34#include "opt_inet.h" 35#include "opt_inet6.h" 36#include "opt_ipsec.h" 37#include "opt_mac.h" 38#include "opt_tcpdebug.h" 39#include "opt_tcp_sack.h" 40 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/callout.h> 44#include <sys/kernel.h> 45#include <sys/sysctl.h> 46#include <sys/mac.h> 47#include <sys/malloc.h> 48#include <sys/mbuf.h> 49#ifdef INET6 50#include <sys/domain.h> 51#endif 52#include <sys/proc.h> 53#include <sys/socket.h> 54#include <sys/socketvar.h> 55#include <sys/protosw.h> 56#include <sys/random.h> 57 58#include <vm/uma.h> 59 60#include <net/route.h> 61#include <net/if.h> 62 63#include <netinet/in.h> 64#include <netinet/in_systm.h> 65#include <netinet/ip.h> 66#ifdef INET6 67#include <netinet/ip6.h> 68#endif 69#include <netinet/in_pcb.h> 70#ifdef INET6 71#include <netinet6/in6_pcb.h> 72#endif 73#include <netinet/in_var.h> 74#include <netinet/ip_var.h> 75#ifdef INET6 76#include <netinet6/ip6_var.h> 77#include <netinet6/scope6_var.h> 78#include <netinet6/nd6.h> 79#endif 80#include <netinet/ip_icmp.h> 81#include <netinet/tcp.h> 82#include <netinet/tcp_fsm.h> 83#include <netinet/tcp_seq.h> 84#include <netinet/tcp_timer.h> 85#include <netinet/tcp_var.h> 86#ifdef INET6 87#include <netinet6/tcp6_var.h> 88#endif 89#include <netinet/tcpip.h> 90#ifdef TCPDEBUG 91#include <netinet/tcp_debug.h> 92#endif 93#include <netinet6/ip6protosw.h> 94 95#ifdef IPSEC 96#include <netinet6/ipsec.h> 97#ifdef INET6 98#include <netinet6/ipsec6.h> 99#endif 100#include <netkey/key.h> 101#endif /*IPSEC*/ 102 103#ifdef FAST_IPSEC 104#include <netipsec/ipsec.h> 105#include <netipsec/xform.h> 106#ifdef INET6 107#include <netipsec/ipsec6.h> 108#endif 109#include <netipsec/key.h> 110#define IPSEC 111#endif /*FAST_IPSEC*/ 112 113#include <machine/in_cksum.h> 114#include <sys/md5.h> 115 116int tcp_mssdflt = TCP_MSS; 117SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 118 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 119 120#ifdef INET6 121int tcp_v6mssdflt = TCP6_MSS; 122SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 123 CTLFLAG_RW, &tcp_v6mssdflt , 0, 124 "Default TCP Maximum Segment Size for IPv6"); 125#endif 126 127/* 128 * Minimum MSS we accept and use. This prevents DoS attacks where 129 * we are forced to a ridiculous low MSS like 20 and send hundreds 130 * of packets instead of one. The effect scales with the available 131 * bandwidth and quickly saturates the CPU and network interface 132 * with packet generation and sending. Set to zero to disable MINMSS 133 * checking. This setting prevents us from sending too small packets. 134 */ 135int tcp_minmss = TCP_MINMSS; 136SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 137 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 138/* 139 * Number of TCP segments per second we accept from remote host 140 * before we start to calculate average segment size. If average 141 * segment size drops below the minimum TCP MSS we assume a DoS 142 * attack and reset+drop the connection. Care has to be taken not to 143 * set this value too small to not kill interactive type connections 144 * (telnet, SSH) which send many small packets. 145 */ 146int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 147SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW, 148 &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to" 149 "be under the MINMSS Size"); 150 151#if 0 152static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 153SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 154 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 155#endif 156 157int tcp_do_rfc1323 = 1; 158SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 159 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 160 161static int tcp_tcbhashsize = 0; 162SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 163 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 164 165static int do_tcpdrain = 1; 166SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 167 "Enable tcp_drain routine for extra help when low on mbufs"); 168 169SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 170 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 171 172static int icmp_may_rst = 1; 173SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 174 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 175 176static int tcp_isn_reseed_interval = 0; 177SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 178 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 179 180static int maxtcptw; 181SYSCTL_INT(_net_inet_tcp, OID_AUTO, maxtcptw, CTLFLAG_RDTUN, 182 &maxtcptw, 0, "Maximum number of compressed TCP TIME_WAIT entries"); 183 184/* 185 * TCP bandwidth limiting sysctls. Note that the default lower bound of 186 * 1024 exists only for debugging. A good production default would be 187 * something like 6100. 188 */ 189SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 190 "TCP inflight data limiting"); 191 192static int tcp_inflight_enable = 1; 193SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 194 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 195 196static int tcp_inflight_debug = 0; 197SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 198 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 199 200static int tcp_inflight_rttthresh; 201SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 202 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 203 "RTT threshold below which inflight will deactivate itself"); 204 205static int tcp_inflight_min = 6144; 206SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 207 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 208 209static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 210SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 211 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 212 213static int tcp_inflight_stab = 20; 214SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 215 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 216 217uma_zone_t sack_hole_zone; 218 219static struct inpcb *tcp_notify(struct inpcb *, int); 220static void tcp_isn_tick(void *); 221 222/* 223 * Target size of TCP PCB hash tables. Must be a power of two. 224 * 225 * Note that this can be overridden by the kernel environment 226 * variable net.inet.tcp.tcbhashsize 227 */ 228#ifndef TCBHASHSIZE 229#define TCBHASHSIZE 512 230#endif 231 232/* 233 * XXX 234 * Callouts should be moved into struct tcp directly. They are currently 235 * separate because the tcpcb structure is exported to userland for sysctl 236 * parsing purposes, which do not know about callouts. 237 */ 238struct tcpcb_mem { 239 struct tcpcb tcb; 240 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 241 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 242}; 243 244static uma_zone_t tcpcb_zone; 245static uma_zone_t tcptw_zone; 246struct callout isn_callout; 247 248/* 249 * TCP initialization. 250 */
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324} 325 326void 327tcp_fini(void *xtp) 328{ 329 330 callout_stop(&isn_callout); 331} 332 333/* 334 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 335 * tcp_template used to store this data in mbufs, but we now recopy it out 336 * of the tcpcb each time to conserve mbufs. 337 */ 338void 339tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 340{ 341 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 342 343 INP_LOCK_ASSERT(inp); 344 345#ifdef INET6 346 if ((inp->inp_vflag & INP_IPV6) != 0) { 347 struct ip6_hdr *ip6; 348 349 ip6 = (struct ip6_hdr *)ip_ptr; 350 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 351 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 352 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 353 (IPV6_VERSION & IPV6_VERSION_MASK); 354 ip6->ip6_nxt = IPPROTO_TCP; 355 ip6->ip6_plen = sizeof(struct tcphdr); 356 ip6->ip6_src = inp->in6p_laddr; 357 ip6->ip6_dst = inp->in6p_faddr; 358 } else 359#endif 360 { 361 struct ip *ip; 362 363 ip = (struct ip *)ip_ptr; 364 ip->ip_v = IPVERSION; 365 ip->ip_hl = 5; 366 ip->ip_tos = inp->inp_ip_tos; 367 ip->ip_len = 0; 368 ip->ip_id = 0; 369 ip->ip_off = 0; 370 ip->ip_ttl = inp->inp_ip_ttl; 371 ip->ip_sum = 0; 372 ip->ip_p = IPPROTO_TCP; 373 ip->ip_src = inp->inp_laddr; 374 ip->ip_dst = inp->inp_faddr; 375 } 376 th->th_sport = inp->inp_lport; 377 th->th_dport = inp->inp_fport; 378 th->th_seq = 0; 379 th->th_ack = 0; 380 th->th_x2 = 0; 381 th->th_off = 5; 382 th->th_flags = 0; 383 th->th_win = 0; 384 th->th_urp = 0; 385 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 386} 387 388/* 389 * Create template to be used to send tcp packets on a connection. 390 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 391 * use for this function is in keepalives, which use tcp_respond. 392 */ 393struct tcptemp * 394tcpip_maketemplate(struct inpcb *inp) 395{ 396 struct mbuf *m; 397 struct tcptemp *n; 398 399 m = m_get(M_DONTWAIT, MT_DATA); 400 if (m == NULL) 401 return (0); 402 m->m_len = sizeof(struct tcptemp); 403 n = mtod(m, struct tcptemp *); 404 405 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 406 return (n); 407} 408 409/* 410 * Send a single message to the TCP at address specified by 411 * the given TCP/IP header. If m == NULL, then we make a copy 412 * of the tcpiphdr at ti and send directly to the addressed host. 413 * This is used to force keep alive messages out using the TCP 414 * template for a connection. If flags are given then we send 415 * a message back to the TCP which originated the * segment ti, 416 * and discard the mbuf containing it and any other attached mbufs. 417 * 418 * In any case the ack and sequence number of the transmitted 419 * segment are as specified by the parameters. 420 * 421 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 422 */ 423void 424tcp_respond(struct tcpcb *tp, void *ipgen, register struct tcphdr *th, 425 register struct mbuf *m, tcp_seq ack, tcp_seq seq, int flags) 426{ 427 register int tlen; 428 int win = 0; 429 struct ip *ip; 430 struct tcphdr *nth; 431#ifdef INET6 432 struct ip6_hdr *ip6; 433 int isipv6; 434#endif /* INET6 */ 435 int ipflags = 0; 436 struct inpcb *inp; 437 438 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 439 440#ifdef INET6 441 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 442 ip6 = ipgen; 443#endif /* INET6 */ 444 ip = ipgen; 445 446 if (tp != NULL) { 447 inp = tp->t_inpcb; 448 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 449 INP_INFO_WLOCK_ASSERT(&tcbinfo); 450 INP_LOCK_ASSERT(inp); 451 } else 452 inp = NULL; 453 454 if (tp != NULL) { 455 if (!(flags & TH_RST)) { 456 win = sbspace(&inp->inp_socket->so_rcv); 457 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 458 win = (long)TCP_MAXWIN << tp->rcv_scale; 459 } 460 } 461 if (m == NULL) { 462 m = m_gethdr(M_DONTWAIT, MT_DATA); 463 if (m == NULL) 464 return; 465 tlen = 0; 466 m->m_data += max_linkhdr; 467#ifdef INET6 468 if (isipv6) { 469 bcopy((caddr_t)ip6, mtod(m, caddr_t), 470 sizeof(struct ip6_hdr)); 471 ip6 = mtod(m, struct ip6_hdr *); 472 nth = (struct tcphdr *)(ip6 + 1); 473 } else 474#endif /* INET6 */ 475 { 476 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 477 ip = mtod(m, struct ip *); 478 nth = (struct tcphdr *)(ip + 1); 479 } 480 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 481 flags = TH_ACK; 482 } else { 483 m_freem(m->m_next); 484 m->m_next = NULL; 485 m->m_data = (caddr_t)ipgen; 486 /* m_len is set later */ 487 tlen = 0; 488#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 489#ifdef INET6 490 if (isipv6) { 491 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 492 nth = (struct tcphdr *)(ip6 + 1); 493 } else 494#endif /* INET6 */ 495 { 496 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 497 nth = (struct tcphdr *)(ip + 1); 498 } 499 if (th != nth) { 500 /* 501 * this is usually a case when an extension header 502 * exists between the IPv6 header and the 503 * TCP header. 504 */ 505 nth->th_sport = th->th_sport; 506 nth->th_dport = th->th_dport; 507 } 508 xchg(nth->th_dport, nth->th_sport, n_short); 509#undef xchg 510 } 511#ifdef INET6 512 if (isipv6) { 513 ip6->ip6_flow = 0; 514 ip6->ip6_vfc = IPV6_VERSION; 515 ip6->ip6_nxt = IPPROTO_TCP; 516 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 517 tlen)); 518 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 519 } else 520#endif 521 { 522 tlen += sizeof (struct tcpiphdr); 523 ip->ip_len = tlen; 524 ip->ip_ttl = ip_defttl; 525 if (path_mtu_discovery) 526 ip->ip_off |= IP_DF; 527 } 528 m->m_len = tlen; 529 m->m_pkthdr.len = tlen; 530 m->m_pkthdr.rcvif = NULL; 531#ifdef MAC 532 if (inp != NULL) { 533 /* 534 * Packet is associated with a socket, so allow the 535 * label of the response to reflect the socket label. 536 */ 537 INP_LOCK_ASSERT(inp); 538 mac_create_mbuf_from_inpcb(inp, m); 539 } else { 540 /* 541 * Packet is not associated with a socket, so possibly 542 * update the label in place. 543 */ 544 mac_reflect_mbuf_tcp(m); 545 } 546#endif 547 nth->th_seq = htonl(seq); 548 nth->th_ack = htonl(ack); 549 nth->th_x2 = 0; 550 nth->th_off = sizeof (struct tcphdr) >> 2; 551 nth->th_flags = flags; 552 if (tp != NULL) 553 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 554 else 555 nth->th_win = htons((u_short)win); 556 nth->th_urp = 0; 557#ifdef INET6 558 if (isipv6) { 559 nth->th_sum = 0; 560 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 561 sizeof(struct ip6_hdr), 562 tlen - sizeof(struct ip6_hdr)); 563 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 564 NULL, NULL); 565 } else 566#endif /* INET6 */ 567 { 568 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 569 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 570 m->m_pkthdr.csum_flags = CSUM_TCP; 571 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 572 } 573#ifdef TCPDEBUG 574 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 575 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 576#endif 577#ifdef INET6 578 if (isipv6) 579 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 580 else 581#endif /* INET6 */ 582 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 583} 584 585/* 586 * Create a new TCP control block, making an 587 * empty reassembly queue and hooking it to the argument 588 * protocol control block. The `inp' parameter must have 589 * come from the zone allocator set up in tcp_init(). 590 */ 591struct tcpcb * 592tcp_newtcpcb(struct inpcb *inp) 593{ 594 struct tcpcb_mem *tm; 595 struct tcpcb *tp; 596#ifdef INET6 597 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 598#endif /* INET6 */ 599 600 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 601 if (tm == NULL) 602 return (NULL); 603 tp = &tm->tcb; 604 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 605 tp->t_maxseg = tp->t_maxopd = 606#ifdef INET6 607 isipv6 ? tcp_v6mssdflt : 608#endif /* INET6 */ 609 tcp_mssdflt; 610 611 /* Set up our timeouts. */ 612 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, NET_CALLOUT_MPSAFE); 613 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, NET_CALLOUT_MPSAFE); 614 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, NET_CALLOUT_MPSAFE); 615 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, NET_CALLOUT_MPSAFE); 616 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, NET_CALLOUT_MPSAFE); 617 618 if (tcp_do_rfc1323) 619 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 620 tp->sack_enable = tcp_do_sack; 621 TAILQ_INIT(&tp->snd_holes); 622 tp->t_inpcb = inp; /* XXX */ 623 /* 624 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 625 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 626 * reasonable initial retransmit time. 627 */ 628 tp->t_srtt = TCPTV_SRTTBASE; 629 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 630 tp->t_rttmin = tcp_rexmit_min; 631 tp->t_rxtcur = TCPTV_RTOBASE; 632 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 633 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 634 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 635 tp->t_rcvtime = ticks; 636 tp->t_bw_rtttime = ticks; 637 /* 638 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 639 * because the socket may be bound to an IPv6 wildcard address, 640 * which may match an IPv4-mapped IPv6 address. 641 */ 642 inp->inp_ip_ttl = ip_defttl; 643 inp->inp_ppcb = tp; 644 return (tp); /* XXX */ 645} 646 647/* 648 * Drop a TCP connection, reporting 649 * the specified error. If connection is synchronized, 650 * then send a RST to peer. 651 */ 652struct tcpcb * 653tcp_drop(struct tcpcb *tp, int errno) 654{ 655 struct socket *so = tp->t_inpcb->inp_socket; 656 657 INP_INFO_WLOCK_ASSERT(&tcbinfo); 658 INP_LOCK_ASSERT(tp->t_inpcb); 659 660 if (TCPS_HAVERCVDSYN(tp->t_state)) { 661 tp->t_state = TCPS_CLOSED; 662 (void) tcp_output(tp); 663 tcpstat.tcps_drops++; 664 } else 665 tcpstat.tcps_conndrops++; 666 if (errno == ETIMEDOUT && tp->t_softerror) 667 errno = tp->t_softerror; 668 so->so_error = errno; 669 return (tcp_close(tp)); 670} 671 672void 673tcp_discardcb(struct tcpcb *tp) 674{ 675 struct tseg_qent *q; 676 struct inpcb *inp = tp->t_inpcb; 677 struct socket *so = inp->inp_socket; 678#ifdef INET6 679 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 680#endif /* INET6 */ 681 682 /* 683 * XXXRW: This is all very well and good, but actually, we might be 684 * discarding the tcpcb after the socket is gone, so we can't do 685 * this: 686 KASSERT(so != NULL, ("tcp_discardcb: so == NULL")); 687 */ 688 INP_LOCK_ASSERT(inp); 689 690 /* 691 * Make sure that all of our timers are stopped before we 692 * delete the PCB. 693 */ 694 callout_stop(tp->tt_rexmt); 695 callout_stop(tp->tt_persist); 696 callout_stop(tp->tt_keep); 697 callout_stop(tp->tt_2msl); 698 callout_stop(tp->tt_delack); 699 700 /* 701 * If we got enough samples through the srtt filter, 702 * save the rtt and rttvar in the routing entry. 703 * 'Enough' is arbitrarily defined as 4 rtt samples. 704 * 4 samples is enough for the srtt filter to converge 705 * to within enough % of the correct value; fewer samples 706 * and we could save a bogus rtt. The danger is not high 707 * as tcp quickly recovers from everything. 708 * XXX: Works very well but needs some more statistics! 709 */ 710 if (tp->t_rttupdated >= 4) { 711 struct hc_metrics_lite metrics; 712 u_long ssthresh; 713 714 bzero(&metrics, sizeof(metrics)); 715 /* 716 * Update the ssthresh always when the conditions below 717 * are satisfied. This gives us better new start value 718 * for the congestion avoidance for new connections. 719 * ssthresh is only set if packet loss occured on a session. 720 */ 721 ssthresh = tp->snd_ssthresh; 722 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 723 /* 724 * convert the limit from user data bytes to 725 * packets then to packet data bytes. 726 */ 727 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 728 if (ssthresh < 2) 729 ssthresh = 2; 730 ssthresh *= (u_long)(tp->t_maxseg + 731#ifdef INET6 732 (isipv6 ? sizeof (struct ip6_hdr) + 733 sizeof (struct tcphdr) : 734#endif 735 sizeof (struct tcpiphdr) 736#ifdef INET6 737 ) 738#endif 739 ); 740 } else 741 ssthresh = 0; 742 metrics.rmx_ssthresh = ssthresh; 743 744 metrics.rmx_rtt = tp->t_srtt; 745 metrics.rmx_rttvar = tp->t_rttvar; 746 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 747 metrics.rmx_bandwidth = tp->snd_bandwidth; 748 metrics.rmx_cwnd = tp->snd_cwnd; 749 metrics.rmx_sendpipe = 0; 750 metrics.rmx_recvpipe = 0; 751 752 tcp_hc_update(&inp->inp_inc, &metrics); 753 } 754 755 /* free the reassembly queue, if any */ 756 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 757 LIST_REMOVE(q, tqe_q); 758 m_freem(q->tqe_m); 759 uma_zfree(tcp_reass_zone, q); 760 tp->t_segqlen--; 761 tcp_reass_qsize--; 762 } 763 tcp_free_sackholes(tp); 764 inp->inp_ppcb = NULL; 765 tp->t_inpcb = NULL; 766 uma_zfree(tcpcb_zone, tp); 767 768 /* 769 * XXXRW: This seems a bit unclean. 770 */ 771 if (so != NULL) 772 soisdisconnected(so); 773} 774 775/* 776 * Attempt to close a TCP control block, marking it as dropped, and freeing 777 * the socket if we hold the only reference. 778 */ 779struct tcpcb * 780tcp_close(struct tcpcb *tp) 781{ 782 struct inpcb *inp = tp->t_inpcb; 783 struct socket *so; 784 785 INP_INFO_WLOCK_ASSERT(&tcbinfo); 786 INP_LOCK_ASSERT(inp); 787 788 inp->inp_vflag |= INP_DROPPED; 789 790 tcpstat.tcps_closed++; 791 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 792 so = inp->inp_socket; 793 soisdisconnected(so); 794 if (inp->inp_vflag & INP_SOCKREF) { 795 KASSERT(so->so_state & SS_PROTOREF, 796 ("tcp_close: !SS_PROTOREF")); 797 inp->inp_vflag &= ~INP_SOCKREF; 798 tcp_discardcb(tp); 799#ifdef INET6 800 if (inp->inp_vflag & INP_IPV6PROTO) { 801 in6_pcbdetach(inp); 802 in6_pcbfree(inp); 803 } else { 804#endif 805 in_pcbdetach(inp); 806 in_pcbfree(inp); 807#ifdef INET6 808 } 809#endif 810 ACCEPT_LOCK(); 811 SOCK_LOCK(so); 812 so->so_state &= ~SS_PROTOREF; 813 sofree(so); 814 return (NULL); 815 } 816 return (tp); 817} 818 819void 820tcp_drain(void) 821{ 822 823 if (do_tcpdrain) { 824 struct inpcb *inpb; 825 struct tcpcb *tcpb; 826 struct tseg_qent *te; 827 828 /* 829 * Walk the tcpbs, if existing, and flush the reassembly queue, 830 * if there is one... 831 * XXX: The "Net/3" implementation doesn't imply that the TCP 832 * reassembly queue should be flushed, but in a situation 833 * where we're really low on mbufs, this is potentially 834 * usefull. 835 */ 836 INP_INFO_RLOCK(&tcbinfo); 837 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 838 if (inpb->inp_vflag & INP_TIMEWAIT) 839 continue; 840 INP_LOCK(inpb); 841 if ((tcpb = intotcpcb(inpb)) != NULL) { 842 while ((te = LIST_FIRST(&tcpb->t_segq)) 843 != NULL) { 844 LIST_REMOVE(te, tqe_q); 845 m_freem(te->tqe_m); 846 uma_zfree(tcp_reass_zone, te); 847 tcpb->t_segqlen--; 848 tcp_reass_qsize--; 849 } 850 tcp_clean_sackreport(tcpb); 851 } 852 INP_UNLOCK(inpb); 853 } 854 INP_INFO_RUNLOCK(&tcbinfo); 855 } 856} 857 858/* 859 * Notify a tcp user of an asynchronous error; 860 * store error as soft error, but wake up user 861 * (for now, won't do anything until can select for soft error). 862 * 863 * Do not wake up user since there currently is no mechanism for 864 * reporting soft errors (yet - a kqueue filter may be added). 865 */ 866static struct inpcb * 867tcp_notify(struct inpcb *inp, int error) 868{ 869 struct tcpcb *tp; 870 871 INP_INFO_WLOCK_ASSERT(&tcbinfo); 872 INP_LOCK_ASSERT(inp); 873 874 if ((inp->inp_vflag & INP_TIMEWAIT) || 875 (inp->inp_vflag & INP_DROPPED)) 876 return (inp); 877 878 tp = intotcpcb(inp); 879 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 880 881 /* 882 * Ignore some errors if we are hooked up. 883 * If connection hasn't completed, has retransmitted several times, 884 * and receives a second error, give up now. This is better 885 * than waiting a long time to establish a connection that 886 * can never complete. 887 */ 888 if (tp->t_state == TCPS_ESTABLISHED && 889 (error == EHOSTUNREACH || error == ENETUNREACH || 890 error == EHOSTDOWN)) { 891 return (inp); 892 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 893 tp->t_softerror) { 894 tp = tcp_drop(tp, error); 895 if (tp != NULL) 896 return (inp); 897 else 898 return (NULL); 899 } else { 900 tp->t_softerror = error; 901 return (inp); 902 } 903#if 0 904 wakeup( &so->so_timeo); 905 sorwakeup(so); 906 sowwakeup(so); 907#endif 908} 909 910static int 911tcp_pcblist(SYSCTL_HANDLER_ARGS) 912{ 913 int error, i, n; 914 struct inpcb *inp, **inp_list; 915 inp_gen_t gencnt; 916 struct xinpgen xig; 917 918 /* 919 * The process of preparing the TCB list is too time-consuming and 920 * resource-intensive to repeat twice on every request. 921 */ 922 if (req->oldptr == NULL) { 923 n = tcbinfo.ipi_count; 924 req->oldidx = 2 * (sizeof xig) 925 + (n + n/8) * sizeof(struct xtcpcb); 926 return (0); 927 } 928 929 if (req->newptr != NULL) 930 return (EPERM); 931 932 /* 933 * OK, now we're committed to doing something. 934 */ 935 INP_INFO_RLOCK(&tcbinfo); 936 gencnt = tcbinfo.ipi_gencnt; 937 n = tcbinfo.ipi_count; 938 INP_INFO_RUNLOCK(&tcbinfo); 939 940 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 941 + n * sizeof(struct xtcpcb)); 942 if (error != 0) 943 return (error); 944 945 xig.xig_len = sizeof xig; 946 xig.xig_count = n; 947 xig.xig_gen = gencnt; 948 xig.xig_sogen = so_gencnt; 949 error = SYSCTL_OUT(req, &xig, sizeof xig); 950 if (error) 951 return (error); 952 953 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 954 if (inp_list == NULL) 955 return (ENOMEM); 956 957 INP_INFO_RLOCK(&tcbinfo); 958 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 959 inp = LIST_NEXT(inp, inp_list)) { 960 INP_LOCK(inp); 961 if (inp->inp_gencnt <= gencnt) { 962 /* 963 * XXX: This use of cr_cansee(), introduced with 964 * TCP state changes, is not quite right, but for 965 * now, better than nothing. 966 */ 967 if (inp->inp_vflag & INP_TIMEWAIT) { 968 if (intotw(inp) != NULL) 969 error = cr_cansee(req->td->td_ucred, 970 intotw(inp)->tw_cred); 971 else 972 error = EINVAL; /* Skip this inp. */ 973 } else 974 error = cr_canseesocket(req->td->td_ucred, 975 inp->inp_socket); 976 if (error == 0) 977 inp_list[i++] = inp; 978 } 979 INP_UNLOCK(inp); 980 } 981 INP_INFO_RUNLOCK(&tcbinfo); 982 n = i; 983 984 error = 0; 985 for (i = 0; i < n; i++) { 986 inp = inp_list[i]; 987 if (inp->inp_gencnt <= gencnt) { 988 struct xtcpcb xt; 989 void *inp_ppcb; 990 991 bzero(&xt, sizeof(xt)); 992 xt.xt_len = sizeof xt; 993 /* XXX should avoid extra copy */ 994 bcopy(inp, &xt.xt_inp, sizeof *inp); 995 inp_ppcb = inp->inp_ppcb; 996 if (inp_ppcb == NULL) 997 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 998 else if (inp->inp_vflag & INP_TIMEWAIT) { 999 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 1000 xt.xt_tp.t_state = TCPS_TIME_WAIT; 1001 } else 1002 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 1003 if (inp->inp_socket != NULL) 1004 sotoxsocket(inp->inp_socket, &xt.xt_socket); 1005 else { 1006 bzero(&xt.xt_socket, sizeof xt.xt_socket); 1007 xt.xt_socket.xso_protocol = IPPROTO_TCP; 1008 } 1009 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 1010 error = SYSCTL_OUT(req, &xt, sizeof xt); 1011 } 1012 } 1013 if (!error) { 1014 /* 1015 * Give the user an updated idea of our state. 1016 * If the generation differs from what we told 1017 * her before, she knows that something happened 1018 * while we were processing this request, and it 1019 * might be necessary to retry. 1020 */ 1021 INP_INFO_RLOCK(&tcbinfo); 1022 xig.xig_gen = tcbinfo.ipi_gencnt; 1023 xig.xig_sogen = so_gencnt; 1024 xig.xig_count = tcbinfo.ipi_count; 1025 INP_INFO_RUNLOCK(&tcbinfo); 1026 error = SYSCTL_OUT(req, &xig, sizeof xig); 1027 } 1028 free(inp_list, M_TEMP); 1029 return (error); 1030} 1031 1032SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1033 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1034 1035static int 1036tcp_getcred(SYSCTL_HANDLER_ARGS) 1037{ 1038 struct xucred xuc; 1039 struct sockaddr_in addrs[2]; 1040 struct inpcb *inp; 1041 int error; 1042 1043 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1044 if (error) 1045 return (error); 1046 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1047 if (error) 1048 return (error); 1049 INP_INFO_RLOCK(&tcbinfo); 1050 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1051 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1052 if (inp == NULL) { 1053 error = ENOENT; 1054 goto outunlocked; 1055 } 1056 INP_LOCK(inp); 1057 if (inp->inp_socket == NULL) { 1058 error = ENOENT; 1059 goto out; 1060 } 1061 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1062 if (error) 1063 goto out; 1064 cru2x(inp->inp_socket->so_cred, &xuc); 1065out: 1066 INP_UNLOCK(inp); 1067outunlocked: 1068 INP_INFO_RUNLOCK(&tcbinfo); 1069 if (error == 0) 1070 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1071 return (error); 1072} 1073 1074SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1075 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1076 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1077 1078#ifdef INET6 1079static int 1080tcp6_getcred(SYSCTL_HANDLER_ARGS) 1081{ 1082 struct xucred xuc; 1083 struct sockaddr_in6 addrs[2]; 1084 struct inpcb *inp; 1085 int error, mapped = 0; 1086 1087 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1088 if (error) 1089 return (error); 1090 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1091 if (error) 1092 return (error); 1093 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1094 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1095 return (error); 1096 } 1097 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1098 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1099 mapped = 1; 1100 else 1101 return (EINVAL); 1102 } 1103 1104 INP_INFO_RLOCK(&tcbinfo); 1105 if (mapped == 1) 1106 inp = in_pcblookup_hash(&tcbinfo, 1107 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1108 addrs[1].sin6_port, 1109 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1110 addrs[0].sin6_port, 1111 0, NULL); 1112 else 1113 inp = in6_pcblookup_hash(&tcbinfo, 1114 &addrs[1].sin6_addr, addrs[1].sin6_port, 1115 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1116 if (inp == NULL) { 1117 error = ENOENT; 1118 goto outunlocked; 1119 } 1120 INP_LOCK(inp); 1121 if (inp->inp_socket == NULL) { 1122 error = ENOENT; 1123 goto out; 1124 } 1125 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1126 if (error) 1127 goto out; 1128 cru2x(inp->inp_socket->so_cred, &xuc); 1129out: 1130 INP_UNLOCK(inp); 1131outunlocked: 1132 INP_INFO_RUNLOCK(&tcbinfo); 1133 if (error == 0) 1134 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1135 return (error); 1136} 1137 1138SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1139 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1140 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1141#endif 1142 1143 1144void 1145tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1146{ 1147 struct ip *ip = vip; 1148 struct tcphdr *th; 1149 struct in_addr faddr; 1150 struct inpcb *inp; 1151 struct tcpcb *tp; 1152 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1153 struct icmp *icp; 1154 struct in_conninfo inc; 1155 tcp_seq icmp_tcp_seq; 1156 int mtu; 1157 1158 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1159 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1160 return; 1161 1162 if (cmd == PRC_MSGSIZE) 1163 notify = tcp_mtudisc; 1164 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1165 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1166 notify = tcp_drop_syn_sent; 1167 /* 1168 * Redirects don't need to be handled up here. 1169 */ 1170 else if (PRC_IS_REDIRECT(cmd)) 1171 return; 1172 /* 1173 * Source quench is depreciated. 1174 */ 1175 else if (cmd == PRC_QUENCH) 1176 return; 1177 /* 1178 * Hostdead is ugly because it goes linearly through all PCBs. 1179 * XXX: We never get this from ICMP, otherwise it makes an 1180 * excellent DoS attack on machines with many connections. 1181 */ 1182 else if (cmd == PRC_HOSTDEAD) 1183 ip = NULL; 1184 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1185 return; 1186 if (ip != NULL) { 1187 icp = (struct icmp *)((caddr_t)ip 1188 - offsetof(struct icmp, icmp_ip)); 1189 th = (struct tcphdr *)((caddr_t)ip 1190 + (ip->ip_hl << 2)); 1191 INP_INFO_WLOCK(&tcbinfo); 1192 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1193 ip->ip_src, th->th_sport, 0, NULL); 1194 if (inp != NULL) { 1195 INP_LOCK(inp); 1196 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1197 !(inp->inp_vflag & INP_DROPPED) && 1198 !(inp->inp_socket == NULL)) { 1199 icmp_tcp_seq = htonl(th->th_seq); 1200 tp = intotcpcb(inp); 1201 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1202 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1203 if (cmd == PRC_MSGSIZE) { 1204 /* 1205 * MTU discovery: 1206 * If we got a needfrag set the MTU 1207 * in the route to the suggested new 1208 * value (if given) and then notify. 1209 */ 1210 bzero(&inc, sizeof(inc)); 1211 inc.inc_flags = 0; /* IPv4 */ 1212 inc.inc_faddr = faddr; 1213 1214 mtu = ntohs(icp->icmp_nextmtu); 1215 /* 1216 * If no alternative MTU was 1217 * proposed, try the next smaller 1218 * one. ip->ip_len has already 1219 * been swapped in icmp_input(). 1220 */ 1221 if (!mtu) 1222 mtu = ip_next_mtu(ip->ip_len, 1223 1); 1224 if (mtu < max(296, (tcp_minmss) 1225 + sizeof(struct tcpiphdr))) 1226 mtu = 0; 1227 if (!mtu) 1228 mtu = tcp_mssdflt 1229 + sizeof(struct tcpiphdr); 1230 /* 1231 * Only cache the the MTU if it 1232 * is smaller than the interface 1233 * or route MTU. tcp_mtudisc() 1234 * will do right thing by itself. 1235 */ 1236 if (mtu <= tcp_maxmtu(&inc)) 1237 tcp_hc_updatemtu(&inc, mtu); 1238 } 1239 1240 inp = (*notify)(inp, inetctlerrmap[cmd]); 1241 } 1242 } 1243 if (inp != NULL) 1244 INP_UNLOCK(inp); 1245 } else { 1246 inc.inc_fport = th->th_dport; 1247 inc.inc_lport = th->th_sport; 1248 inc.inc_faddr = faddr; 1249 inc.inc_laddr = ip->ip_src; 1250#ifdef INET6 1251 inc.inc_isipv6 = 0; 1252#endif 1253 syncache_unreach(&inc, th); 1254 } 1255 INP_INFO_WUNLOCK(&tcbinfo); 1256 } else 1257 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1258} 1259 1260#ifdef INET6 1261void 1262tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1263{ 1264 struct tcphdr th; 1265 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1266 struct ip6_hdr *ip6; 1267 struct mbuf *m; 1268 struct ip6ctlparam *ip6cp = NULL; 1269 const struct sockaddr_in6 *sa6_src = NULL; 1270 int off; 1271 struct tcp_portonly { 1272 u_int16_t th_sport; 1273 u_int16_t th_dport; 1274 } *thp; 1275 1276 if (sa->sa_family != AF_INET6 || 1277 sa->sa_len != sizeof(struct sockaddr_in6)) 1278 return; 1279 1280 if (cmd == PRC_MSGSIZE) 1281 notify = tcp_mtudisc; 1282 else if (!PRC_IS_REDIRECT(cmd) && 1283 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1284 return; 1285 /* Source quench is depreciated. */ 1286 else if (cmd == PRC_QUENCH) 1287 return; 1288 1289 /* if the parameter is from icmp6, decode it. */ 1290 if (d != NULL) { 1291 ip6cp = (struct ip6ctlparam *)d; 1292 m = ip6cp->ip6c_m; 1293 ip6 = ip6cp->ip6c_ip6; 1294 off = ip6cp->ip6c_off; 1295 sa6_src = ip6cp->ip6c_src; 1296 } else { 1297 m = NULL; 1298 ip6 = NULL; 1299 off = 0; /* fool gcc */ 1300 sa6_src = &sa6_any; 1301 } 1302 1303 if (ip6 != NULL) { 1304 struct in_conninfo inc; 1305 /* 1306 * XXX: We assume that when IPV6 is non NULL, 1307 * M and OFF are valid. 1308 */ 1309 1310 /* check if we can safely examine src and dst ports */ 1311 if (m->m_pkthdr.len < off + sizeof(*thp)) 1312 return; 1313 1314 bzero(&th, sizeof(th)); 1315 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1316 1317 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1318 (struct sockaddr *)ip6cp->ip6c_src, 1319 th.th_sport, cmd, NULL, notify); 1320 1321 inc.inc_fport = th.th_dport; 1322 inc.inc_lport = th.th_sport; 1323 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1324 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1325 inc.inc_isipv6 = 1; 1326 INP_INFO_WLOCK(&tcbinfo); 1327 syncache_unreach(&inc, &th); 1328 INP_INFO_WUNLOCK(&tcbinfo); 1329 } else 1330 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1331 0, cmd, NULL, notify); 1332} 1333#endif /* INET6 */ 1334 1335 1336/* 1337 * Following is where TCP initial sequence number generation occurs. 1338 * 1339 * There are two places where we must use initial sequence numbers: 1340 * 1. In SYN-ACK packets. 1341 * 2. In SYN packets. 1342 * 1343 * All ISNs for SYN-ACK packets are generated by the syncache. See 1344 * tcp_syncache.c for details. 1345 * 1346 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1347 * depends on this property. In addition, these ISNs should be 1348 * unguessable so as to prevent connection hijacking. To satisfy 1349 * the requirements of this situation, the algorithm outlined in 1350 * RFC 1948 is used, with only small modifications. 1351 * 1352 * Implementation details: 1353 * 1354 * Time is based off the system timer, and is corrected so that it 1355 * increases by one megabyte per second. This allows for proper 1356 * recycling on high speed LANs while still leaving over an hour 1357 * before rollover. 1358 * 1359 * As reading the *exact* system time is too expensive to be done 1360 * whenever setting up a TCP connection, we increment the time 1361 * offset in two ways. First, a small random positive increment 1362 * is added to isn_offset for each connection that is set up. 1363 * Second, the function tcp_isn_tick fires once per clock tick 1364 * and increments isn_offset as necessary so that sequence numbers 1365 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1366 * random positive increments serve only to ensure that the same 1367 * exact sequence number is never sent out twice (as could otherwise 1368 * happen when a port is recycled in less than the system tick 1369 * interval.) 1370 * 1371 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1372 * between seeding of isn_secret. This is normally set to zero, 1373 * as reseeding should not be necessary. 1374 * 1375 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1376 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1377 * general, this means holding an exclusive (write) lock. 1378 */ 1379 1380#define ISN_BYTES_PER_SECOND 1048576 1381#define ISN_STATIC_INCREMENT 4096 1382#define ISN_RANDOM_INCREMENT (4096 - 1) 1383 1384static u_char isn_secret[32]; 1385static int isn_last_reseed; 1386static u_int32_t isn_offset, isn_offset_old; 1387static MD5_CTX isn_ctx; 1388 1389tcp_seq 1390tcp_new_isn(struct tcpcb *tp) 1391{ 1392 u_int32_t md5_buffer[4]; 1393 tcp_seq new_isn; 1394 1395 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1396 INP_LOCK_ASSERT(tp->t_inpcb); 1397 1398 /* Seed if this is the first use, reseed if requested. */ 1399 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1400 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1401 < (u_int)ticks))) { 1402 read_random(&isn_secret, sizeof(isn_secret)); 1403 isn_last_reseed = ticks; 1404 } 1405 1406 /* Compute the md5 hash and return the ISN. */ 1407 MD5Init(&isn_ctx); 1408 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1409 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1410#ifdef INET6 1411 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1412 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1413 sizeof(struct in6_addr)); 1414 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1415 sizeof(struct in6_addr)); 1416 } else 1417#endif 1418 { 1419 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1420 sizeof(struct in_addr)); 1421 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1422 sizeof(struct in_addr)); 1423 } 1424 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1425 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1426 new_isn = (tcp_seq) md5_buffer[0]; 1427 isn_offset += ISN_STATIC_INCREMENT + 1428 (arc4random() & ISN_RANDOM_INCREMENT); 1429 new_isn += isn_offset; 1430 return (new_isn); 1431} 1432 1433/* 1434 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1435 * to keep time flowing at a relatively constant rate. If the random 1436 * increments have already pushed us past the projected offset, do nothing. 1437 */ 1438static void 1439tcp_isn_tick(void *xtp) 1440{ 1441 u_int32_t projected_offset; 1442 1443 INP_INFO_WLOCK(&tcbinfo); 1444 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1445 1446 if (projected_offset > isn_offset) 1447 isn_offset = projected_offset; 1448 1449 isn_offset_old = isn_offset; 1450 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1451 INP_INFO_WUNLOCK(&tcbinfo); 1452} 1453 1454/* 1455 * When a specific ICMP unreachable message is received and the 1456 * connection state is SYN-SENT, drop the connection. This behavior 1457 * is controlled by the icmp_may_rst sysctl. 1458 */ 1459struct inpcb * 1460tcp_drop_syn_sent(struct inpcb *inp, int errno) 1461{ 1462 struct tcpcb *tp; 1463 1464 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1465 INP_LOCK_ASSERT(inp); 1466 1467 if ((inp->inp_vflag & INP_TIMEWAIT) || 1468 (inp->inp_vflag & INP_DROPPED)) 1469 return (inp); 1470 1471 tp = intotcpcb(inp); 1472 if (tp->t_state != TCPS_SYN_SENT) 1473 return (inp); 1474 1475 tp = tcp_drop(tp, errno); 1476 if (tp != NULL) 1477 return (inp); 1478 else 1479 return (NULL); 1480} 1481 1482/* 1483 * When `need fragmentation' ICMP is received, update our idea of the MSS 1484 * based on the new value in the route. Also nudge TCP to send something, 1485 * since we know the packet we just sent was dropped. 1486 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1487 */ 1488struct inpcb * 1489tcp_mtudisc(struct inpcb *inp, int errno) 1490{ 1491 struct tcpcb *tp; 1492 struct socket *so = inp->inp_socket; 1493 u_int maxmtu; 1494 u_int romtu; 1495 int mss; 1496#ifdef INET6 1497 int isipv6; 1498#endif /* INET6 */ 1499 1500 INP_LOCK_ASSERT(inp); 1501 if ((inp->inp_vflag & INP_TIMEWAIT) || 1502 (inp->inp_vflag & INP_DROPPED)) 1503 return (inp); 1504 1505 tp = intotcpcb(inp); 1506 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1507 1508#ifdef INET6 1509 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1510#endif 1511 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1512 romtu = 1513#ifdef INET6 1514 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1515#endif /* INET6 */ 1516 tcp_maxmtu(&inp->inp_inc); 1517 if (!maxmtu) 1518 maxmtu = romtu; 1519 else 1520 maxmtu = min(maxmtu, romtu); 1521 if (!maxmtu) { 1522 tp->t_maxopd = tp->t_maxseg = 1523#ifdef INET6 1524 isipv6 ? tcp_v6mssdflt : 1525#endif /* INET6 */ 1526 tcp_mssdflt; 1527 return (inp); 1528 } 1529 mss = maxmtu - 1530#ifdef INET6 1531 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1532#endif /* INET6 */ 1533 sizeof(struct tcpiphdr) 1534#ifdef INET6 1535 ) 1536#endif /* INET6 */ 1537 ; 1538 1539 /* 1540 * XXX - The above conditional probably violates the TCP 1541 * spec. The problem is that, since we don't know the 1542 * other end's MSS, we are supposed to use a conservative 1543 * default. But, if we do that, then MTU discovery will 1544 * never actually take place, because the conservative 1545 * default is much less than the MTUs typically seen 1546 * on the Internet today. For the moment, we'll sweep 1547 * this under the carpet. 1548 * 1549 * The conservative default might not actually be a problem 1550 * if the only case this occurs is when sending an initial 1551 * SYN with options and data to a host we've never talked 1552 * to before. Then, they will reply with an MSS value which 1553 * will get recorded and the new parameters should get 1554 * recomputed. For Further Study. 1555 */ 1556 if (tp->t_maxopd <= mss) 1557 return (inp); 1558 tp->t_maxopd = mss; 1559 1560 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1561 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1562 mss -= TCPOLEN_TSTAMP_APPA; 1563#if (MCLBYTES & (MCLBYTES - 1)) == 0 1564 if (mss > MCLBYTES) 1565 mss &= ~(MCLBYTES-1); 1566#else 1567 if (mss > MCLBYTES) 1568 mss = mss / MCLBYTES * MCLBYTES; 1569#endif 1570 if (so->so_snd.sb_hiwat < mss) 1571 mss = so->so_snd.sb_hiwat; 1572 1573 tp->t_maxseg = mss; 1574 1575 tcpstat.tcps_mturesent++; 1576 tp->t_rtttime = 0; 1577 tp->snd_nxt = tp->snd_una; 1578 tcp_output(tp); 1579 return (inp); 1580} 1581 1582/* 1583 * Look-up the routing entry to the peer of this inpcb. If no route 1584 * is found and it cannot be allocated, then return NULL. This routine 1585 * is called by TCP routines that access the rmx structure and by tcp_mss 1586 * to get the interface MTU. 1587 */ 1588u_long 1589tcp_maxmtu(struct in_conninfo *inc) 1590{ 1591 struct route sro; 1592 struct sockaddr_in *dst; 1593 struct ifnet *ifp; 1594 u_long maxmtu = 0; 1595 1596 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1597 1598 bzero(&sro, sizeof(sro)); 1599 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1600 dst = (struct sockaddr_in *)&sro.ro_dst; 1601 dst->sin_family = AF_INET; 1602 dst->sin_len = sizeof(*dst); 1603 dst->sin_addr = inc->inc_faddr; 1604 rtalloc_ign(&sro, RTF_CLONING); 1605 } 1606 if (sro.ro_rt != NULL) { 1607 ifp = sro.ro_rt->rt_ifp; 1608 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1609 maxmtu = ifp->if_mtu; 1610 else 1611 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1612 RTFREE(sro.ro_rt); 1613 } 1614 return (maxmtu); 1615} 1616 1617#ifdef INET6 1618u_long 1619tcp_maxmtu6(struct in_conninfo *inc) 1620{ 1621 struct route_in6 sro6; 1622 struct ifnet *ifp; 1623 u_long maxmtu = 0; 1624 1625 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1626 1627 bzero(&sro6, sizeof(sro6)); 1628 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1629 sro6.ro_dst.sin6_family = AF_INET6; 1630 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1631 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1632 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1633 } 1634 if (sro6.ro_rt != NULL) { 1635 ifp = sro6.ro_rt->rt_ifp; 1636 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1637 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1638 else 1639 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1640 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1641 RTFREE(sro6.ro_rt); 1642 } 1643 1644 return (maxmtu); 1645} 1646#endif /* INET6 */ 1647 1648#ifdef IPSEC 1649/* compute ESP/AH header size for TCP, including outer IP header. */ 1650size_t 1651ipsec_hdrsiz_tcp(struct tcpcb *tp) 1652{ 1653 struct inpcb *inp; 1654 struct mbuf *m; 1655 size_t hdrsiz; 1656 struct ip *ip; 1657#ifdef INET6 1658 struct ip6_hdr *ip6; 1659#endif 1660 struct tcphdr *th; 1661 1662 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1663 return (0); 1664 MGETHDR(m, M_DONTWAIT, MT_DATA); 1665 if (!m) 1666 return (0); 1667 1668#ifdef INET6 1669 if ((inp->inp_vflag & INP_IPV6) != 0) { 1670 ip6 = mtod(m, struct ip6_hdr *); 1671 th = (struct tcphdr *)(ip6 + 1); 1672 m->m_pkthdr.len = m->m_len = 1673 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1674 tcpip_fillheaders(inp, ip6, th); 1675 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1676 } else 1677#endif /* INET6 */ 1678 { 1679 ip = mtod(m, struct ip *); 1680 th = (struct tcphdr *)(ip + 1); 1681 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1682 tcpip_fillheaders(inp, ip, th); 1683 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1684 } 1685 1686 m_free(m); 1687 return (hdrsiz); 1688} 1689#endif /*IPSEC*/ 1690 1691/* 1692 * Move a TCP connection into TIME_WAIT state. 1693 * tcbinfo is locked. 1694 * inp is locked, and is unlocked before returning. 1695 */ 1696void 1697tcp_twstart(struct tcpcb *tp) 1698{ 1699 struct tcptw *tw; 1700 struct inpcb *inp; 1701 int tw_time, acknow; 1702 struct socket *so; 1703 1704 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1705 INP_LOCK_ASSERT(tp->t_inpcb); 1706 1707 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1708 if (tw == NULL) { 1709 tw = tcp_timer_2msl_tw(1); 1710 if (tw == NULL) { 1711 tp = tcp_close(tp); 1712 if (tp != NULL) 1713 INP_UNLOCK(tp->t_inpcb); 1714 return; 1715 } 1716 } 1717 inp = tp->t_inpcb; 1718 tw->tw_inpcb = inp; 1719 1720 /* 1721 * Recover last window size sent. 1722 */ 1723 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1724 1725 /* 1726 * Set t_recent if timestamps are used on the connection. 1727 */ 1728 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1729 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1730 tw->t_recent = tp->ts_recent; 1731 else 1732 tw->t_recent = 0; 1733 1734 tw->snd_nxt = tp->snd_nxt; 1735 tw->rcv_nxt = tp->rcv_nxt; 1736 tw->iss = tp->iss; 1737 tw->irs = tp->irs; 1738 tw->t_starttime = tp->t_starttime; 1739 tw->tw_time = 0; 1740 1741/* XXX 1742 * If this code will 1743 * be used for fin-wait-2 state also, then we may need 1744 * a ts_recent from the last segment. 1745 */ 1746 tw_time = 2 * tcp_msl; 1747 acknow = tp->t_flags & TF_ACKNOW; 1748 1749 /* 1750 * First, discard tcpcb state, which includes stopping its timers and 1751 * freeing it. tcp_discardcb() used to also release the inpcb, but 1752 * that work is now done in the caller. 1753 */ 1754 tcp_discardcb(tp); 1755 so = inp->inp_socket; 1756 SOCK_LOCK(so); 1757 tw->tw_cred = crhold(so->so_cred); 1758 tw->tw_so_options = so->so_options; 1759 SOCK_UNLOCK(so); 1760 if (acknow) 1761 tcp_twrespond(tw, TH_ACK); 1762 inp->inp_ppcb = tw; 1763 inp->inp_vflag |= INP_TIMEWAIT; 1764 tcp_timer_2msl_reset(tw, tw_time); 1765 1766 /* 1767 * If the inpcb owns the sole reference to the socket, then we can 1768 * detach and free the socket as it is not needed in time wait. 1769 */ 1770 if (inp->inp_vflag & INP_SOCKREF) { 1771 KASSERT(so->so_state & SS_PROTOREF, 1772 ("tcp_twstart: !SS_PROTOREF")); 1773 inp->inp_vflag &= ~INP_SOCKREF; 1774#ifdef INET6 1775 if (inp->inp_vflag & INP_IPV6PROTO) 1776 in6_pcbdetach(inp); 1777 else 1778#endif 1779 in_pcbdetach(inp); 1780 INP_UNLOCK(inp); 1781 ACCEPT_LOCK(); 1782 SOCK_LOCK(so); 1783 so->so_state &= ~SS_PROTOREF; 1784 sofree(so); 1785 } else 1786 INP_UNLOCK(inp); 1787} 1788 1789/* 1790 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1791 * the actual rate is slightly higher due to the addition of 1792 * random positive increments. 1793 * 1794 * Most other new OSes use semi-randomized ISN values, so we 1795 * do not need to worry about them. 1796 */ 1797#define MS_ISN_BYTES_PER_SECOND 250000 1798 1799/* 1800 * Determine if the ISN we will generate has advanced beyond the last 1801 * sequence number used by the previous connection. If so, indicate 1802 * that it is safe to recycle this tw socket by returning 1. 1803 * 1804 * XXXRW: This function should assert the inpcb lock as it does multiple 1805 * non-atomic reads from the tcptw, but is currently called without it from 1806 * in_pcb.c:in_pcblookup_local(). 1807 */ 1808int 1809tcp_twrecycleable(struct tcptw *tw) 1810{ 1811 tcp_seq new_iss = tw->iss; 1812 tcp_seq new_irs = tw->irs; 1813 1814 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1815 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1816 1817 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1818 return (1); 1819 else 1820 return (0); 1821} 1822 1823void 1824tcp_twclose(struct tcptw *tw, int reuse) 1825{ 1826 struct socket *so; 1827 struct inpcb *inp; 1828 1829 /* 1830 * At this point, we are in one of two situations: 1831 * 1832 * (1) We have no socket, just an inpcb<->twtcp pair. Release it all 1833 * after validating. 1834 * 1835 * (2) We have a socket, which we may or may now own the reference 1836 * for. If we own the reference, release all the state after 1837 * validating. If not, leave it for the socket close to clean up. 1838 */ 1839 inp = tw->tw_inpcb; 1840 KASSERT((inp->inp_vflag & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 1841 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 1842 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1843 INP_LOCK_ASSERT(inp); 1844 1845 tw->tw_inpcb = NULL; 1846 tcp_timer_2msl_stop(tw); 1847 inp->inp_ppcb = NULL; 1848 inp->inp_vflag |= INP_DROPPED; 1849 1850 so = inp->inp_socket; 1851 if (so != NULL) { 1852 if (inp->inp_vflag & INP_SOCKREF) { 1853 /* 1854 * If a socket is present, and we own the only 1855 * reference, we need to tear down the socket and the 1856 * inpcb. 1857 */ 1858 inp->inp_vflag &= ~INP_SOCKREF; 1859#ifdef INET6 1860 if (inp->inp_vflag & INP_IPV6PROTO) { 1861 in6_pcbdetach(inp); 1862 in6_pcbfree(inp); 1863 } else { 1864 in_pcbdetach(inp); 1865 in_pcbfree(inp); 1866 } 1867#endif 1868 ACCEPT_LOCK(); 1869 SOCK_LOCK(so); 1870 KASSERT(so->so_state & SS_PROTOREF, 1871 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 1872 so->so_state &= ~SS_PROTOREF; 1873 sofree(so); 1874 } else { 1875 /* 1876 * If we don't own the only reference, the socket and 1877 * inpcb need to be left around to be handled by 1878 * tcp_usr_detach() later. 1879 */ 1880 INP_UNLOCK(inp); 1881 } 1882 } else { 1883#ifdef INET6 1884 if (inp->inp_vflag & INP_IPV6PROTO) 1885 in6_pcbfree(inp); 1886 else 1887#endif 1888 in_pcbfree(inp); 1889 } 1890 tcpstat.tcps_closed++; 1891 crfree(tw->tw_cred); 1892 tw->tw_cred = NULL; 1893 if (reuse) 1894 return; 1895 uma_zfree(tcptw_zone, tw); 1896} 1897 1898int 1899tcp_twrespond(struct tcptw *tw, int flags) 1900{ 1901 struct inpcb *inp = tw->tw_inpcb; 1902 struct tcphdr *th; 1903 struct mbuf *m; 1904 struct ip *ip = NULL; 1905 u_int8_t *optp; 1906 u_int hdrlen, optlen; 1907 int error; 1908#ifdef INET6 1909 struct ip6_hdr *ip6 = NULL; 1910 int isipv6 = inp->inp_inc.inc_isipv6; 1911#endif 1912 1913 INP_LOCK_ASSERT(inp); 1914 1915 m = m_gethdr(M_DONTWAIT, MT_DATA); 1916 if (m == NULL) 1917 return (ENOBUFS); 1918 m->m_data += max_linkhdr; 1919 1920#ifdef MAC 1921 mac_create_mbuf_from_inpcb(inp, m); 1922#endif 1923 1924#ifdef INET6 1925 if (isipv6) { 1926 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1927 ip6 = mtod(m, struct ip6_hdr *); 1928 th = (struct tcphdr *)(ip6 + 1); 1929 tcpip_fillheaders(inp, ip6, th); 1930 } else 1931#endif 1932 { 1933 hdrlen = sizeof(struct tcpiphdr); 1934 ip = mtod(m, struct ip *); 1935 th = (struct tcphdr *)(ip + 1); 1936 tcpip_fillheaders(inp, ip, th); 1937 } 1938 optp = (u_int8_t *)(th + 1); 1939 1940 /* 1941 * Send a timestamp and echo-reply if both our side and our peer 1942 * have sent timestamps in our SYN's and this is not a RST. 1943 */ 1944 if (tw->t_recent && flags == TH_ACK) { 1945 u_int32_t *lp = (u_int32_t *)optp; 1946 1947 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1948 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1949 *lp++ = htonl(ticks); 1950 *lp = htonl(tw->t_recent); 1951 optp += TCPOLEN_TSTAMP_APPA; 1952 } 1953 1954 optlen = optp - (u_int8_t *)(th + 1); 1955 1956 m->m_len = hdrlen + optlen; 1957 m->m_pkthdr.len = m->m_len; 1958 1959 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1960 1961 th->th_seq = htonl(tw->snd_nxt); 1962 th->th_ack = htonl(tw->rcv_nxt); 1963 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1964 th->th_flags = flags; 1965 th->th_win = htons(tw->last_win); 1966 1967#ifdef INET6 1968 if (isipv6) { 1969 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1970 sizeof(struct tcphdr) + optlen); 1971 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1972 error = ip6_output(m, inp->in6p_outputopts, NULL, 1973 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1974 } else 1975#endif 1976 { 1977 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1978 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1979 m->m_pkthdr.csum_flags = CSUM_TCP; 1980 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1981 ip->ip_len = m->m_pkthdr.len; 1982 if (path_mtu_discovery) 1983 ip->ip_off |= IP_DF; 1984 error = ip_output(m, inp->inp_options, NULL, 1985 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1986 NULL, inp); 1987 } 1988 if (flags & TH_ACK) 1989 tcpstat.tcps_sndacks++; 1990 else 1991 tcpstat.tcps_sndctrl++; 1992 tcpstat.tcps_sndtotal++; 1993 return (error); 1994} 1995 1996/* 1997 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1998 * 1999 * This code attempts to calculate the bandwidth-delay product as a 2000 * means of determining the optimal window size to maximize bandwidth, 2001 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 2002 * routers. This code also does a fairly good job keeping RTTs in check 2003 * across slow links like modems. We implement an algorithm which is very 2004 * similar (but not meant to be) TCP/Vegas. The code operates on the 2005 * transmitter side of a TCP connection and so only effects the transmit 2006 * side of the connection. 2007 * 2008 * BACKGROUND: TCP makes no provision for the management of buffer space 2009 * at the end points or at the intermediate routers and switches. A TCP 2010 * stream, whether using NewReno or not, will eventually buffer as 2011 * many packets as it is able and the only reason this typically works is 2012 * due to the fairly small default buffers made available for a connection 2013 * (typicaly 16K or 32K). As machines use larger windows and/or window 2014 * scaling it is now fairly easy for even a single TCP connection to blow-out 2015 * all available buffer space not only on the local interface, but on 2016 * intermediate routers and switches as well. NewReno makes a misguided 2017 * attempt to 'solve' this problem by waiting for an actual failure to occur, 2018 * then backing off, then steadily increasing the window again until another 2019 * failure occurs, ad-infinitum. This results in terrible oscillation that 2020 * is only made worse as network loads increase and the idea of intentionally 2021 * blowing out network buffers is, frankly, a terrible way to manage network 2022 * resources. 2023 * 2024 * It is far better to limit the transmit window prior to the failure 2025 * condition being achieved. There are two general ways to do this: First 2026 * you can 'scan' through different transmit window sizes and locate the 2027 * point where the RTT stops increasing, indicating that you have filled the 2028 * pipe, then scan backwards until you note that RTT stops decreasing, then 2029 * repeat ad-infinitum. This method works in principle but has severe 2030 * implementation issues due to RTT variances, timer granularity, and 2031 * instability in the algorithm which can lead to many false positives and 2032 * create oscillations as well as interact badly with other TCP streams 2033 * implementing the same algorithm. 2034 * 2035 * The second method is to limit the window to the bandwidth delay product 2036 * of the link. This is the method we implement. RTT variances and our 2037 * own manipulation of the congestion window, bwnd, can potentially 2038 * destabilize the algorithm. For this reason we have to stabilize the 2039 * elements used to calculate the window. We do this by using the minimum 2040 * observed RTT, the long term average of the observed bandwidth, and 2041 * by adding two segments worth of slop. It isn't perfect but it is able 2042 * to react to changing conditions and gives us a very stable basis on 2043 * which to extend the algorithm. 2044 */ 2045void 2046tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 2047{ 2048 u_long bw; 2049 u_long bwnd; 2050 int save_ticks; 2051 2052 INP_LOCK_ASSERT(tp->t_inpcb); 2053 2054 /* 2055 * If inflight_enable is disabled in the middle of a tcp connection, 2056 * make sure snd_bwnd is effectively disabled. 2057 */ 2058 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 2059 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 2060 tp->snd_bandwidth = 0; 2061 return; 2062 } 2063 2064 /* 2065 * Figure out the bandwidth. Due to the tick granularity this 2066 * is a very rough number and it MUST be averaged over a fairly 2067 * long period of time. XXX we need to take into account a link 2068 * that is not using all available bandwidth, but for now our 2069 * slop will ramp us up if this case occurs and the bandwidth later 2070 * increases. 2071 * 2072 * Note: if ticks rollover 'bw' may wind up negative. We must 2073 * effectively reset t_bw_rtttime for this case. 2074 */ 2075 save_ticks = ticks; 2076 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 2077 return; 2078 2079 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 2080 (save_ticks - tp->t_bw_rtttime); 2081 tp->t_bw_rtttime = save_ticks; 2082 tp->t_bw_rtseq = ack_seq; 2083 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 2084 return; 2085 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 2086 2087 tp->snd_bandwidth = bw; 2088 2089 /* 2090 * Calculate the semi-static bandwidth delay product, plus two maximal 2091 * segments. The additional slop puts us squarely in the sweet 2092 * spot and also handles the bandwidth run-up case and stabilization. 2093 * Without the slop we could be locking ourselves into a lower 2094 * bandwidth. 2095 * 2096 * Situations Handled: 2097 * (1) Prevents over-queueing of packets on LANs, especially on 2098 * high speed LANs, allowing larger TCP buffers to be 2099 * specified, and also does a good job preventing 2100 * over-queueing of packets over choke points like modems 2101 * (at least for the transmit side). 2102 * 2103 * (2) Is able to handle changing network loads (bandwidth 2104 * drops so bwnd drops, bandwidth increases so bwnd 2105 * increases). 2106 * 2107 * (3) Theoretically should stabilize in the face of multiple 2108 * connections implementing the same algorithm (this may need 2109 * a little work). 2110 * 2111 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2112 * be adjusted with a sysctl but typically only needs to be 2113 * on very slow connections. A value no smaller then 5 2114 * should be used, but only reduce this default if you have 2115 * no other choice. 2116 */ 2117#define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2118 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2119#undef USERTT 2120 2121 if (tcp_inflight_debug > 0) { 2122 static int ltime; 2123 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2124 ltime = ticks; 2125 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2126 tp, 2127 bw, 2128 tp->t_rttbest, 2129 tp->t_srtt, 2130 bwnd 2131 ); 2132 } 2133 } 2134 if ((long)bwnd < tcp_inflight_min) 2135 bwnd = tcp_inflight_min; 2136 if (bwnd > tcp_inflight_max) 2137 bwnd = tcp_inflight_max; 2138 if ((long)bwnd < tp->t_maxseg * 2) 2139 bwnd = tp->t_maxseg * 2; 2140 tp->snd_bwnd = bwnd; 2141} 2142 2143#ifdef TCP_SIGNATURE 2144/* 2145 * Callback function invoked by m_apply() to digest TCP segment data 2146 * contained within an mbuf chain. 2147 */ 2148static int 2149tcp_signature_apply(void *fstate, void *data, u_int len) 2150{ 2151 2152 MD5Update(fstate, (u_char *)data, len); 2153 return (0); 2154} 2155 2156/* 2157 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2158 * 2159 * Parameters: 2160 * m pointer to head of mbuf chain 2161 * off0 offset to TCP header within the mbuf chain 2162 * len length of TCP segment data, excluding options 2163 * optlen length of TCP segment options 2164 * buf pointer to storage for computed MD5 digest 2165 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2166 * 2167 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2168 * When called from tcp_input(), we can be sure that th_sum has been 2169 * zeroed out and verified already. 2170 * 2171 * This function is for IPv4 use only. Calling this function with an 2172 * IPv6 packet in the mbuf chain will yield undefined results. 2173 * 2174 * Return 0 if successful, otherwise return -1. 2175 * 2176 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2177 * search with the destination IP address, and a 'magic SPI' to be 2178 * determined by the application. This is hardcoded elsewhere to 1179 2179 * right now. Another branch of this code exists which uses the SPD to 2180 * specify per-application flows but it is unstable. 2181 */ 2182int 2183tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2184 u_char *buf, u_int direction) 2185{ 2186 union sockaddr_union dst; 2187 struct ippseudo ippseudo; 2188 MD5_CTX ctx; 2189 int doff; 2190 struct ip *ip; 2191 struct ipovly *ipovly; 2192 struct secasvar *sav; 2193 struct tcphdr *th; 2194 u_short savecsum; 2195 2196 KASSERT(m != NULL, ("NULL mbuf chain")); 2197 KASSERT(buf != NULL, ("NULL signature pointer")); 2198 2199 /* Extract the destination from the IP header in the mbuf. */ 2200 ip = mtod(m, struct ip *); 2201 bzero(&dst, sizeof(union sockaddr_union)); 2202 dst.sa.sa_len = sizeof(struct sockaddr_in); 2203 dst.sa.sa_family = AF_INET; 2204 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2205 ip->ip_src : ip->ip_dst; 2206 2207 /* Look up an SADB entry which matches the address of the peer. */ 2208 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2209 if (sav == NULL) { 2210 printf("%s: SADB lookup failed for %s\n", __func__, 2211 inet_ntoa(dst.sin.sin_addr)); 2212 return (EINVAL); 2213 } 2214 2215 MD5Init(&ctx); 2216 ipovly = (struct ipovly *)ip; 2217 th = (struct tcphdr *)((u_char *)ip + off0); 2218 doff = off0 + sizeof(struct tcphdr) + optlen; 2219 2220 /* 2221 * Step 1: Update MD5 hash with IP pseudo-header. 2222 * 2223 * XXX The ippseudo header MUST be digested in network byte order, 2224 * or else we'll fail the regression test. Assume all fields we've 2225 * been doing arithmetic on have been in host byte order. 2226 * XXX One cannot depend on ipovly->ih_len here. When called from 2227 * tcp_output(), the underlying ip_len member has not yet been set. 2228 */ 2229 ippseudo.ippseudo_src = ipovly->ih_src; 2230 ippseudo.ippseudo_dst = ipovly->ih_dst; 2231 ippseudo.ippseudo_pad = 0; 2232 ippseudo.ippseudo_p = IPPROTO_TCP; 2233 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2234 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2235 2236 /* 2237 * Step 2: Update MD5 hash with TCP header, excluding options. 2238 * The TCP checksum must be set to zero. 2239 */ 2240 savecsum = th->th_sum; 2241 th->th_sum = 0; 2242 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2243 th->th_sum = savecsum; 2244 2245 /* 2246 * Step 3: Update MD5 hash with TCP segment data. 2247 * Use m_apply() to avoid an early m_pullup(). 2248 */ 2249 if (len > 0) 2250 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2251 2252 /* 2253 * Step 4: Update MD5 hash with shared secret. 2254 */ 2255 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2256 MD5Final(buf, &ctx); 2257 2258 key_sa_recordxfer(sav, m); 2259 KEY_FREESAV(&sav); 2260 return (0); 2261} 2262#endif /* TCP_SIGNATURE */ 2263 2264static int 2265sysctl_drop(SYSCTL_HANDLER_ARGS) 2266{ 2267 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2268 struct sockaddr_storage addrs[2]; 2269 struct inpcb *inp; 2270 struct tcpcb *tp; 2271 struct tcptw *tw; 2272 struct sockaddr_in *fin, *lin; 2273#ifdef INET6 2274 struct sockaddr_in6 *fin6, *lin6; 2275 struct in6_addr f6, l6; 2276#endif 2277 int error; 2278 2279 inp = NULL; 2280 fin = lin = NULL; 2281#ifdef INET6 2282 fin6 = lin6 = NULL; 2283#endif 2284 error = 0; 2285 2286 if (req->oldptr != NULL || req->oldlen != 0) 2287 return (EINVAL); 2288 if (req->newptr == NULL) 2289 return (EPERM); 2290 if (req->newlen < sizeof(addrs)) 2291 return (ENOMEM); 2292 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2293 if (error) 2294 return (error); 2295 2296 switch (addrs[0].ss_family) { 2297#ifdef INET6 2298 case AF_INET6: 2299 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2300 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2301 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2302 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2303 return (EINVAL); 2304 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2305 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2306 return (EINVAL); 2307 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2308 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2309 fin = (struct sockaddr_in *)&addrs[0]; 2310 lin = (struct sockaddr_in *)&addrs[1]; 2311 break; 2312 } 2313 error = sa6_embedscope(fin6, ip6_use_defzone); 2314 if (error) 2315 return (error); 2316 error = sa6_embedscope(lin6, ip6_use_defzone); 2317 if (error) 2318 return (error); 2319 break; 2320#endif 2321 case AF_INET: 2322 fin = (struct sockaddr_in *)&addrs[0]; 2323 lin = (struct sockaddr_in *)&addrs[1]; 2324 if (fin->sin_len != sizeof(struct sockaddr_in) || 2325 lin->sin_len != sizeof(struct sockaddr_in)) 2326 return (EINVAL); 2327 break; 2328 default: 2329 return (EINVAL); 2330 } 2331 INP_INFO_WLOCK(&tcbinfo); 2332 switch (addrs[0].ss_family) { 2333#ifdef INET6 2334 case AF_INET6: 2335 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2336 &l6, lin6->sin6_port, 0, NULL); 2337 break; 2338#endif 2339 case AF_INET: 2340 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2341 lin->sin_addr, lin->sin_port, 0, NULL); 2342 break; 2343 } 2344 if (inp != NULL) { 2345 INP_LOCK(inp); 2346 if (inp->inp_vflag & INP_TIMEWAIT) { 2347 /* 2348 * XXXRW: There currently exists a state where an 2349 * inpcb is present, but its timewait state has been 2350 * discarded. For now, don't allow dropping of this 2351 * type of inpcb. 2352 */ 2353 tw = intotw(inp); 2354 if (tw != NULL) 2355 tcp_twclose(tw, 0); 2356 } else if (!(inp->inp_vflag & INP_DROPPED) && 2357 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2358 tp = intotcpcb(inp); 2359 tcp_drop(tp, ECONNABORTED); 2360 } 2361 INP_UNLOCK(inp); 2362 } else 2363 error = ESRCH; 2364 INP_INFO_WUNLOCK(&tcbinfo); 2365 return (error); 2366} 2367 2368SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2369 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2370 0, sysctl_drop, "", "Drop TCP connection");
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