1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 * $FreeBSD$ 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> 115 116 int tcp_mssdflt = TCP_MSS; 117 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 118 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 119 120 #ifdef INET6 121 int tcp_v6mssdflt = TCP6_MSS; 122 SYSCTL_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 */ 135 int tcp_minmss = TCP_MINMSS; 136 SYSCTL_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 */ 146 int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 147 SYSCTL_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 0 152 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 153 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 154 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 155 #endif 156 157 int tcp_do_rfc1323 = 1; 158 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 159 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 160 161 static int tcp_tcbhashsize = 0; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 163 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 164 165 static int do_tcpdrain = 1; 166 SYSCTL_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"); 168 169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 170 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 171 172 static int icmp_may_rst = 1; 173 SYSCTL_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"); 175 176 static int tcp_isn_reseed_interval = 0; 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 178 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 179 180 static int maxtcptw; 181 SYSCTL_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 */ 189 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 190 "TCP inflight data limiting"); 191 192 static int tcp_inflight_enable = 1; 193 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 194 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 195 196 static int tcp_inflight_debug = 0; 197 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 198 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 199 200 static int tcp_inflight_rttthresh; 201 SYSCTL_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"); 204 205 static int tcp_inflight_min = 6144; 206 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 207 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 208 209 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 210 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 211 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 212 213 static int tcp_inflight_stab = 20; 214 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 215 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 216 217 uma_zone_t sack_hole_zone; 218 219 static struct inpcb *tcp_notify(struct inpcb *, int); 220 static 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 */ 238 struct 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 }; 243 244 static uma_zone_t tcpcb_zone; 245 static uma_zone_t tcptw_zone; 246 struct callout isn_callout; 247 248 /* 249 * TCP initialization. 250 */ 251 void 252 tcp_init(void) 253 { 254 int hashsize = TCBHASHSIZE; 255 256 tcp_delacktime = TCPTV_DELACK; 257 tcp_keepinit = TCPTV_KEEP_INIT; 258 tcp_keepidle = TCPTV_KEEP_IDLE; 259 tcp_keepintvl = TCPTV_KEEPINTVL; 260 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 261 tcp_msl = TCPTV_MSL; 262 tcp_rexmit_min = TCPTV_MIN; 263 tcp_rexmit_slop = TCPTV_CPU_VAR; 264 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 265 266 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 267 LIST_INIT(&tcb); 268 tcbinfo.listhead = &tcb; 269 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 270 if (!powerof2(hashsize)) { 271 printf("WARNING: TCB hash size not a power of 2\n"); 272 hashsize = 512; /* safe default */ 273 } 274 tcp_tcbhashsize = hashsize; 275 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 276 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 277 &tcbinfo.porthashmask); 278 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 279 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 280 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 281 #ifdef INET6 282 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 283 #else /* INET6 */ 284 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 285 #endif /* INET6 */ 286 if (max_protohdr < TCP_MINPROTOHDR) 287 max_protohdr = TCP_MINPROTOHDR; 288 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 289 panic("tcp_init"); 290 #undef TCP_MINPROTOHDR 291 /* 292 * These have to be type stable for the benefit of the timers. 293 */ 294 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 295 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 296 uma_zone_set_max(tcpcb_zone, maxsockets); 297 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 298 if (maxtcptw == 0) 299 maxtcptw = maxsockets / 5; 300 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 301 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 302 uma_zone_set_max(tcptw_zone, maxtcptw); 303 tcp_timer_init(); 304 syncache_init(); 305 tcp_hc_init(); 306 tcp_reass_init(); 307 callout_init(&isn_callout, CALLOUT_MPSAFE); 308 tcp_isn_tick(NULL); 309 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 310 SHUTDOWN_PRI_DEFAULT); 311 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 312 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 313 } 314 315 void 316 tcp_fini(void *xtp) 317 { 318 319 callout_stop(&isn_callout); 320 } 321 322 /* 323 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 324 * tcp_template used to store this data in mbufs, but we now recopy it out 325 * of the tcpcb each time to conserve mbufs. 326 */ 327 void 328 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 329 { 330 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 331 332 INP_LOCK_ASSERT(inp); 333 334 #ifdef INET6 335 if ((inp->inp_vflag & INP_IPV6) != 0) { 336 struct ip6_hdr *ip6; 337 338 ip6 = (struct ip6_hdr *)ip_ptr; 339 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 340 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 341 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 342 (IPV6_VERSION & IPV6_VERSION_MASK); 343 ip6->ip6_nxt = IPPROTO_TCP; 344 ip6->ip6_plen = sizeof(struct tcphdr); 345 ip6->ip6_src = inp->in6p_laddr; 346 ip6->ip6_dst = inp->in6p_faddr; 347 } else 348 #endif 349 { 350 struct ip *ip; 351 352 ip = (struct ip *)ip_ptr; 353 ip->ip_v = IPVERSION; 354 ip->ip_hl = 5; 355 ip->ip_tos = inp->inp_ip_tos; 356 ip->ip_len = 0; 357 ip->ip_id = 0; 358 ip->ip_off = 0; 359 ip->ip_ttl = inp->inp_ip_ttl; 360 ip->ip_sum = 0; 361 ip->ip_p = IPPROTO_TCP; 362 ip->ip_src = inp->inp_laddr; 363 ip->ip_dst = inp->inp_faddr; 364 } 365 th->th_sport = inp->inp_lport; 366 th->th_dport = inp->inp_fport; 367 th->th_seq = 0; 368 th->th_ack = 0; 369 th->th_x2 = 0; 370 th->th_off = 5; 371 th->th_flags = 0; 372 th->th_win = 0; 373 th->th_urp = 0; 374 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 375 } 376 377 /* 378 * Create template to be used to send tcp packets on a connection. 379 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 380 * use for this function is in keepalives, which use tcp_respond. 381 */ 382 struct tcptemp * 383 tcpip_maketemplate(struct inpcb *inp) 384 { 385 struct mbuf *m; 386 struct tcptemp *n; 387 388 m = m_get(M_DONTWAIT, MT_DATA); 389 if (m == NULL) 390 return (0); 391 m->m_len = sizeof(struct tcptemp); 392 n = mtod(m, struct tcptemp *); 393 394 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 395 return (n); 396 } 397 398 /* 399 * Send a single message to the TCP at address specified by 400 * the given TCP/IP header. If m == NULL, then we make a copy 401 * of the tcpiphdr at ti and send directly to the addressed host. 402 * This is used to force keep alive messages out using the TCP 403 * template for a connection. If flags are given then we send 404 * a message back to the TCP which originated the * segment ti, 405 * and discard the mbuf containing it and any other attached mbufs. 406 * 407 * In any case the ack and sequence number of the transmitted 408 * segment are as specified by the parameters. 409 * 410 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 411 */ 412 void 413 tcp_respond(struct tcpcb *tp, void *ipgen, register struct tcphdr *th, 414 register struct mbuf *m, tcp_seq ack, tcp_seq seq, int flags) 415 { 416 register int tlen; 417 int win = 0; 418 struct ip *ip; 419 struct tcphdr *nth; 420 #ifdef INET6 421 struct ip6_hdr *ip6; 422 int isipv6; 423 #endif /* INET6 */ 424 int ipflags = 0; 425 struct inpcb *inp; 426 427 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 428 429 #ifdef INET6 430 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 431 ip6 = ipgen; 432 #endif /* INET6 */ 433 ip = ipgen; 434 435 if (tp != NULL) { 436 inp = tp->t_inpcb; 437 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 438 INP_INFO_WLOCK_ASSERT(&tcbinfo); 439 INP_LOCK_ASSERT(inp); 440 } else 441 inp = NULL; 442 443 if (tp != NULL) { 444 if (!(flags & TH_RST)) { 445 win = sbspace(&inp->inp_socket->so_rcv); 446 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 447 win = (long)TCP_MAXWIN << tp->rcv_scale; 448 } 449 } 450 if (m == NULL) { 451 m = m_gethdr(M_DONTWAIT, MT_DATA); 452 if (m == NULL) 453 return; 454 tlen = 0; 455 m->m_data += max_linkhdr; 456 #ifdef INET6 457 if (isipv6) { 458 bcopy((caddr_t)ip6, mtod(m, caddr_t), 459 sizeof(struct ip6_hdr)); 460 ip6 = mtod(m, struct ip6_hdr *); 461 nth = (struct tcphdr *)(ip6 + 1); 462 } else 463 #endif /* INET6 */ 464 { 465 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 466 ip = mtod(m, struct ip *); 467 nth = (struct tcphdr *)(ip + 1); 468 } 469 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 470 flags = TH_ACK; 471 } else { 472 m_freem(m->m_next); 473 m->m_next = NULL; 474 m->m_data = (caddr_t)ipgen; 475 /* m_len is set later */ 476 tlen = 0; 477 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 478 #ifdef INET6 479 if (isipv6) { 480 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 481 nth = (struct tcphdr *)(ip6 + 1); 482 } else 483 #endif /* INET6 */ 484 { 485 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 486 nth = (struct tcphdr *)(ip + 1); 487 } 488 if (th != nth) { 489 /* 490 * this is usually a case when an extension header 491 * exists between the IPv6 header and the 492 * TCP header. 493 */ 494 nth->th_sport = th->th_sport; 495 nth->th_dport = th->th_dport; 496 } 497 xchg(nth->th_dport, nth->th_sport, n_short); 498 #undef xchg 499 } 500 #ifdef INET6 501 if (isipv6) { 502 ip6->ip6_flow = 0; 503 ip6->ip6_vfc = IPV6_VERSION; 504 ip6->ip6_nxt = IPPROTO_TCP; 505 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 506 tlen)); 507 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 508 } else 509 #endif 510 { 511 tlen += sizeof (struct tcpiphdr); 512 ip->ip_len = tlen; 513 ip->ip_ttl = ip_defttl; 514 if (path_mtu_discovery) 515 ip->ip_off |= IP_DF; 516 } 517 m->m_len = tlen; 518 m->m_pkthdr.len = tlen; 519 m->m_pkthdr.rcvif = NULL; 520 #ifdef MAC 521 if (inp != NULL) { 522 /* 523 * Packet is associated with a socket, so allow the 524 * label of the response to reflect the socket label. 525 */ 526 INP_LOCK_ASSERT(inp); 527 mac_create_mbuf_from_inpcb(inp, m); 528 } else { 529 /* 530 * Packet is not associated with a socket, so possibly 531 * update the label in place. 532 */ 533 mac_reflect_mbuf_tcp(m); 534 } 535 #endif 536 nth->th_seq = htonl(seq); 537 nth->th_ack = htonl(ack); 538 nth->th_x2 = 0; 539 nth->th_off = sizeof (struct tcphdr) >> 2; 540 nth->th_flags = flags; 541 if (tp != NULL) 542 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 543 else 544 nth->th_win = htons((u_short)win); 545 nth->th_urp = 0; 546 #ifdef INET6 547 if (isipv6) { 548 nth->th_sum = 0; 549 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 550 sizeof(struct ip6_hdr), 551 tlen - sizeof(struct ip6_hdr)); 552 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 553 NULL, NULL); 554 } else 555 #endif /* INET6 */ 556 { 557 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 558 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 559 m->m_pkthdr.csum_flags = CSUM_TCP; 560 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 561 } 562 #ifdef TCPDEBUG 563 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 564 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 565 #endif 566 #ifdef INET6 567 if (isipv6) 568 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 569 else 570 #endif /* INET6 */ 571 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 572 } 573 574 /* 575 * Create a new TCP control block, making an 576 * empty reassembly queue and hooking it to the argument 577 * protocol control block. The `inp' parameter must have 578 * come from the zone allocator set up in tcp_init(). 579 */ 580 struct tcpcb * 581 tcp_newtcpcb(struct inpcb *inp) 582 { 583 struct tcpcb_mem *tm; 584 struct tcpcb *tp; 585 #ifdef INET6 586 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 587 #endif /* INET6 */ 588 589 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 590 if (tm == NULL) 591 return (NULL); 592 tp = &tm->tcb; 593 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 594 tp->t_maxseg = tp->t_maxopd = 595 #ifdef INET6 596 isipv6 ? tcp_v6mssdflt : 597 #endif /* INET6 */ 598 tcp_mssdflt; 599 600 /* Set up our timeouts. */ 601 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, NET_CALLOUT_MPSAFE); 602 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, NET_CALLOUT_MPSAFE); 603 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, NET_CALLOUT_MPSAFE); 604 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, NET_CALLOUT_MPSAFE); 605 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, NET_CALLOUT_MPSAFE); 606 607 if (tcp_do_rfc1323) 608 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 609 tp->sack_enable = tcp_do_sack; 610 TAILQ_INIT(&tp->snd_holes); 611 tp->t_inpcb = inp; /* XXX */ 612 /* 613 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 614 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 615 * reasonable initial retransmit time. 616 */ 617 tp->t_srtt = TCPTV_SRTTBASE; 618 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 619 tp->t_rttmin = tcp_rexmit_min; 620 tp->t_rxtcur = TCPTV_RTOBASE; 621 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 622 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 623 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 624 tp->t_rcvtime = ticks; 625 tp->t_bw_rtttime = ticks; 626 /* 627 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 628 * because the socket may be bound to an IPv6 wildcard address, 629 * which may match an IPv4-mapped IPv6 address. 630 */ 631 inp->inp_ip_ttl = ip_defttl; 632 inp->inp_ppcb = tp; 633 return (tp); /* XXX */ 634 } 635 636 /* 637 * Drop a TCP connection, reporting 638 * the specified error. If connection is synchronized, 639 * then send a RST to peer. 640 */ 641 struct tcpcb * 642 tcp_drop(struct tcpcb *tp, int errno) 643 { 644 struct socket *so = tp->t_inpcb->inp_socket; 645 646 INP_INFO_WLOCK_ASSERT(&tcbinfo); 647 INP_LOCK_ASSERT(tp->t_inpcb); 648 649 if (TCPS_HAVERCVDSYN(tp->t_state)) { 650 tp->t_state = TCPS_CLOSED; 651 (void) tcp_output(tp); 652 tcpstat.tcps_drops++; 653 } else 654 tcpstat.tcps_conndrops++; 655 if (errno == ETIMEDOUT && tp->t_softerror) 656 errno = tp->t_softerror; 657 so->so_error = errno; 658 return (tcp_close(tp)); 659 } 660 661 void 662 tcp_discardcb(struct tcpcb *tp) 663 { 664 struct tseg_qent *q; 665 struct inpcb *inp = tp->t_inpcb; 666 struct socket *so = inp->inp_socket; 667 #ifdef INET6 668 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 669 #endif /* INET6 */ 670 671 /* 672 * XXXRW: This is all very well and good, but actually, we might be 673 * discarding the tcpcb after the socket is gone, so we can't do 674 * this: 675 KASSERT(so != NULL, ("tcp_discardcb: so == NULL")); 676 */ 677 INP_LOCK_ASSERT(inp); 678 679 /* 680 * Make sure that all of our timers are stopped before we 681 * delete the PCB. 682 */ 683 callout_stop(tp->tt_rexmt); 684 callout_stop(tp->tt_persist); 685 callout_stop(tp->tt_keep); 686 callout_stop(tp->tt_2msl); 687 callout_stop(tp->tt_delack); 688 689 /* 690 * If we got enough samples through the srtt filter, 691 * save the rtt and rttvar in the routing entry. 692 * 'Enough' is arbitrarily defined as 4 rtt samples. 693 * 4 samples is enough for the srtt filter to converge 694 * to within enough % of the correct value; fewer samples 695 * and we could save a bogus rtt. The danger is not high 696 * as tcp quickly recovers from everything. 697 * XXX: Works very well but needs some more statistics! 698 */ 699 if (tp->t_rttupdated >= 4) { 700 struct hc_metrics_lite metrics; 701 u_long ssthresh; 702 703 bzero(&metrics, sizeof(metrics)); 704 /* 705 * Update the ssthresh always when the conditions below 706 * are satisfied. This gives us better new start value 707 * for the congestion avoidance for new connections. 708 * ssthresh is only set if packet loss occured on a session. 709 */ 710 ssthresh = tp->snd_ssthresh; 711 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 712 /* 713 * convert the limit from user data bytes to 714 * packets then to packet data bytes. 715 */ 716 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 717 if (ssthresh < 2) 718 ssthresh = 2; 719 ssthresh *= (u_long)(tp->t_maxseg + 720 #ifdef INET6 721 (isipv6 ? sizeof (struct ip6_hdr) + 722 sizeof (struct tcphdr) : 723 #endif 724 sizeof (struct tcpiphdr) 725 #ifdef INET6 726 ) 727 #endif 728 ); 729 } else 730 ssthresh = 0; 731 metrics.rmx_ssthresh = ssthresh; 732 733 metrics.rmx_rtt = tp->t_srtt; 734 metrics.rmx_rttvar = tp->t_rttvar; 735 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 736 metrics.rmx_bandwidth = tp->snd_bandwidth; 737 metrics.rmx_cwnd = tp->snd_cwnd; 738 metrics.rmx_sendpipe = 0; 739 metrics.rmx_recvpipe = 0; 740 741 tcp_hc_update(&inp->inp_inc, &metrics); 742 } 743 744 /* free the reassembly queue, if any */ 745 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 746 LIST_REMOVE(q, tqe_q); 747 m_freem(q->tqe_m); 748 uma_zfree(tcp_reass_zone, q); 749 tp->t_segqlen--; 750 tcp_reass_qsize--; 751 } 752 tcp_free_sackholes(tp); 753 inp->inp_ppcb = NULL; 754 tp->t_inpcb = NULL; 755 uma_zfree(tcpcb_zone, tp); 756 757 /* 758 * XXXRW: This seems a bit unclean. 759 */ 760 if (so != NULL) 761 soisdisconnected(so); 762 } 763 764 /* 765 * Attempt to close a TCP control block, marking it as dropped, and freeing 766 * the socket if we hold the only reference. 767 */ 768 struct tcpcb * 769 tcp_close(struct tcpcb *tp) 770 { 771 struct inpcb *inp = tp->t_inpcb; 772 struct socket *so; 773 774 INP_INFO_WLOCK_ASSERT(&tcbinfo); 775 INP_LOCK_ASSERT(inp); 776 777 inp->inp_vflag |= INP_DROPPED; 778 779 tcpstat.tcps_closed++; 780 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 781 so = inp->inp_socket; 782 soisdisconnected(so); 783 if (inp->inp_vflag & INP_SOCKREF) { 784 KASSERT(so->so_state & SS_PROTOREF, 785 ("tcp_close: !SS_PROTOREF")); 786 inp->inp_vflag &= ~INP_SOCKREF; 787 tcp_discardcb(tp); 788 #ifdef INET6 789 if (inp->inp_vflag & INP_IPV6PROTO) { 790 in6_pcbdetach(inp); 791 in6_pcbfree(inp); 792 } else { 793 #endif 794 in_pcbdetach(inp); 795 in_pcbfree(inp); 796 #ifdef INET6 797 } 798 #endif 799 ACCEPT_LOCK(); 800 SOCK_LOCK(so); 801 so->so_state &= ~SS_PROTOREF; 802 sofree(so); 803 return (NULL); 804 } 805 return (tp); 806 } 807 808 void 809 tcp_drain(void) 810 { 811 812 if (do_tcpdrain) { 813 struct inpcb *inpb; 814 struct tcpcb *tcpb; 815 struct tseg_qent *te; 816 817 /* 818 * Walk the tcpbs, if existing, and flush the reassembly queue, 819 * if there is one... 820 * XXX: The "Net/3" implementation doesn't imply that the TCP 821 * reassembly queue should be flushed, but in a situation 822 * where we're really low on mbufs, this is potentially 823 * usefull. 824 */ 825 INP_INFO_RLOCK(&tcbinfo); 826 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 827 if (inpb->inp_vflag & INP_TIMEWAIT) 828 continue; 829 INP_LOCK(inpb); 830 if ((tcpb = intotcpcb(inpb)) != NULL) { 831 while ((te = LIST_FIRST(&tcpb->t_segq)) 832 != NULL) { 833 LIST_REMOVE(te, tqe_q); 834 m_freem(te->tqe_m); 835 uma_zfree(tcp_reass_zone, te); 836 tcpb->t_segqlen--; 837 tcp_reass_qsize--; 838 } 839 tcp_clean_sackreport(tcpb); 840 } 841 INP_UNLOCK(inpb); 842 } 843 INP_INFO_RUNLOCK(&tcbinfo); 844 } 845 } 846 847 /* 848 * Notify a tcp user of an asynchronous error; 849 * store error as soft error, but wake up user 850 * (for now, won't do anything until can select for soft error). 851 * 852 * Do not wake up user since there currently is no mechanism for 853 * reporting soft errors (yet - a kqueue filter may be added). 854 */ 855 static struct inpcb * 856 tcp_notify(struct inpcb *inp, int error) 857 { 858 struct tcpcb *tp; 859 860 INP_INFO_WLOCK_ASSERT(&tcbinfo); 861 INP_LOCK_ASSERT(inp); 862 863 if ((inp->inp_vflag & INP_TIMEWAIT) || 864 (inp->inp_vflag & INP_DROPPED)) 865 return (inp); 866 867 tp = intotcpcb(inp); 868 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 869 870 /* 871 * Ignore some errors if we are hooked up. 872 * If connection hasn't completed, has retransmitted several times, 873 * and receives a second error, give up now. This is better 874 * than waiting a long time to establish a connection that 875 * can never complete. 876 */ 877 if (tp->t_state == TCPS_ESTABLISHED && 878 (error == EHOSTUNREACH || error == ENETUNREACH || 879 error == EHOSTDOWN)) { 880 return (inp); 881 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 882 tp->t_softerror) { 883 tp = tcp_drop(tp, error); 884 if (tp != NULL) 885 return (inp); 886 else 887 return (NULL); 888 } else { 889 tp->t_softerror = error; 890 return (inp); 891 } 892 #if 0 893 wakeup( &so->so_timeo); 894 sorwakeup(so); 895 sowwakeup(so); 896 #endif 897 } 898 899 static int 900 tcp_pcblist(SYSCTL_HANDLER_ARGS) 901 { 902 int error, i, n; 903 struct inpcb *inp, **inp_list; 904 inp_gen_t gencnt; 905 struct xinpgen xig; 906 907 /* 908 * The process of preparing the TCB list is too time-consuming and 909 * resource-intensive to repeat twice on every request. 910 */ 911 if (req->oldptr == NULL) { 912 n = tcbinfo.ipi_count; 913 req->oldidx = 2 * (sizeof xig) 914 + (n + n/8) * sizeof(struct xtcpcb); 915 return (0); 916 } 917 918 if (req->newptr != NULL) 919 return (EPERM); 920 921 /* 922 * OK, now we're committed to doing something. 923 */ 924 INP_INFO_RLOCK(&tcbinfo); 925 gencnt = tcbinfo.ipi_gencnt; 926 n = tcbinfo.ipi_count; 927 INP_INFO_RUNLOCK(&tcbinfo); 928 929 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 930 + n * sizeof(struct xtcpcb)); 931 if (error != 0) 932 return (error); 933 934 xig.xig_len = sizeof xig; 935 xig.xig_count = n; 936 xig.xig_gen = gencnt; 937 xig.xig_sogen = so_gencnt; 938 error = SYSCTL_OUT(req, &xig, sizeof xig); 939 if (error) 940 return (error); 941 942 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 943 if (inp_list == NULL) 944 return (ENOMEM); 945 946 INP_INFO_RLOCK(&tcbinfo); 947 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 948 inp = LIST_NEXT(inp, inp_list)) { 949 INP_LOCK(inp); 950 if (inp->inp_gencnt <= gencnt) { 951 /* 952 * XXX: This use of cr_cansee(), introduced with 953 * TCP state changes, is not quite right, but for 954 * now, better than nothing. 955 */ 956 if (inp->inp_vflag & INP_TIMEWAIT) { 957 if (intotw(inp) != NULL) 958 error = cr_cansee(req->td->td_ucred, 959 intotw(inp)->tw_cred); 960 else 961 error = EINVAL; /* Skip this inp. */ 962 } else 963 error = cr_canseesocket(req->td->td_ucred, 964 inp->inp_socket); 965 if (error == 0) 966 inp_list[i++] = inp; 967 } 968 INP_UNLOCK(inp); 969 } 970 INP_INFO_RUNLOCK(&tcbinfo); 971 n = i; 972 973 error = 0; 974 for (i = 0; i < n; i++) { 975 inp = inp_list[i]; 976 if (inp->inp_gencnt <= gencnt) { 977 struct xtcpcb xt; 978 void *inp_ppcb; 979 980 bzero(&xt, sizeof(xt)); 981 xt.xt_len = sizeof xt; 982 /* XXX should avoid extra copy */ 983 bcopy(inp, &xt.xt_inp, sizeof *inp); 984 inp_ppcb = inp->inp_ppcb; 985 if (inp_ppcb == NULL) 986 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 987 else if (inp->inp_vflag & INP_TIMEWAIT) { 988 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 989 xt.xt_tp.t_state = TCPS_TIME_WAIT; 990 } else 991 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 992 if (inp->inp_socket != NULL) 993 sotoxsocket(inp->inp_socket, &xt.xt_socket); 994 else { 995 bzero(&xt.xt_socket, sizeof xt.xt_socket); 996 xt.xt_socket.xso_protocol = IPPROTO_TCP; 997 } 998 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 999 error = SYSCTL_OUT(req, &xt, sizeof xt); 1000 } 1001 } 1002 if (!error) { 1003 /* 1004 * Give the user an updated idea of our state. 1005 * If the generation differs from what we told 1006 * her before, she knows that something happened 1007 * while we were processing this request, and it 1008 * might be necessary to retry. 1009 */ 1010 INP_INFO_RLOCK(&tcbinfo); 1011 xig.xig_gen = tcbinfo.ipi_gencnt; 1012 xig.xig_sogen = so_gencnt; 1013 xig.xig_count = tcbinfo.ipi_count; 1014 INP_INFO_RUNLOCK(&tcbinfo); 1015 error = SYSCTL_OUT(req, &xig, sizeof xig); 1016 } 1017 free(inp_list, M_TEMP); 1018 return (error); 1019 } 1020 1021 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1022 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1023 1024 static int 1025 tcp_getcred(SYSCTL_HANDLER_ARGS) 1026 { 1027 struct xucred xuc; 1028 struct sockaddr_in addrs[2]; 1029 struct inpcb *inp; 1030 int error; 1031 1032 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1033 if (error) 1034 return (error); 1035 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1036 if (error) 1037 return (error); 1038 INP_INFO_RLOCK(&tcbinfo); 1039 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1040 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1041 if (inp == NULL) { 1042 error = ENOENT; 1043 goto outunlocked; 1044 } 1045 INP_LOCK(inp); 1046 if (inp->inp_socket == NULL) { 1047 error = ENOENT; 1048 goto out; 1049 } 1050 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1051 if (error) 1052 goto out; 1053 cru2x(inp->inp_socket->so_cred, &xuc); 1054 out: 1055 INP_UNLOCK(inp); 1056 outunlocked: 1057 INP_INFO_RUNLOCK(&tcbinfo); 1058 if (error == 0) 1059 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1060 return (error); 1061 } 1062 1063 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1064 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1065 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1066 1067 #ifdef INET6 1068 static int 1069 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1070 { 1071 struct xucred xuc; 1072 struct sockaddr_in6 addrs[2]; 1073 struct inpcb *inp; 1074 int error, mapped = 0; 1075 1076 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1077 if (error) 1078 return (error); 1079 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1080 if (error) 1081 return (error); 1082 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1083 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1084 return (error); 1085 } 1086 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1087 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1088 mapped = 1; 1089 else 1090 return (EINVAL); 1091 } 1092 1093 INP_INFO_RLOCK(&tcbinfo); 1094 if (mapped == 1) 1095 inp = in_pcblookup_hash(&tcbinfo, 1096 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1097 addrs[1].sin6_port, 1098 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1099 addrs[0].sin6_port, 1100 0, NULL); 1101 else 1102 inp = in6_pcblookup_hash(&tcbinfo, 1103 &addrs[1].sin6_addr, addrs[1].sin6_port, 1104 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1105 if (inp == NULL) { 1106 error = ENOENT; 1107 goto outunlocked; 1108 } 1109 INP_LOCK(inp); 1110 if (inp->inp_socket == NULL) { 1111 error = ENOENT; 1112 goto out; 1113 } 1114 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1115 if (error) 1116 goto out; 1117 cru2x(inp->inp_socket->so_cred, &xuc); 1118 out: 1119 INP_UNLOCK(inp); 1120 outunlocked: 1121 INP_INFO_RUNLOCK(&tcbinfo); 1122 if (error == 0) 1123 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1124 return (error); 1125 } 1126 1127 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1128 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1129 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1130 #endif 1131 1132 1133 void 1134 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1135 { 1136 struct ip *ip = vip; 1137 struct tcphdr *th; 1138 struct in_addr faddr; 1139 struct inpcb *inp; 1140 struct tcpcb *tp; 1141 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1142 struct icmp *icp; 1143 struct in_conninfo inc; 1144 tcp_seq icmp_tcp_seq; 1145 int mtu; 1146 1147 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1148 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1149 return; 1150 1151 if (cmd == PRC_MSGSIZE) 1152 notify = tcp_mtudisc; 1153 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1154 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1155 notify = tcp_drop_syn_sent; 1156 /* 1157 * Redirects don't need to be handled up here. 1158 */ 1159 else if (PRC_IS_REDIRECT(cmd)) 1160 return; 1161 /* 1162 * Source quench is depreciated. 1163 */ 1164 else if (cmd == PRC_QUENCH) 1165 return; 1166 /* 1167 * Hostdead is ugly because it goes linearly through all PCBs. 1168 * XXX: We never get this from ICMP, otherwise it makes an 1169 * excellent DoS attack on machines with many connections. 1170 */ 1171 else if (cmd == PRC_HOSTDEAD) 1172 ip = NULL; 1173 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1174 return; 1175 if (ip != NULL) { 1176 icp = (struct icmp *)((caddr_t)ip 1177 - offsetof(struct icmp, icmp_ip)); 1178 th = (struct tcphdr *)((caddr_t)ip 1179 + (ip->ip_hl << 2)); 1180 INP_INFO_WLOCK(&tcbinfo); 1181 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1182 ip->ip_src, th->th_sport, 0, NULL); 1183 if (inp != NULL) { 1184 INP_LOCK(inp); 1185 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1186 !(inp->inp_vflag & INP_DROPPED) && 1187 !(inp->inp_socket == NULL)) { 1188 icmp_tcp_seq = htonl(th->th_seq); 1189 tp = intotcpcb(inp); 1190 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1191 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1192 if (cmd == PRC_MSGSIZE) { 1193 /* 1194 * MTU discovery: 1195 * If we got a needfrag set the MTU 1196 * in the route to the suggested new 1197 * value (if given) and then notify. 1198 */ 1199 bzero(&inc, sizeof(inc)); 1200 inc.inc_flags = 0; /* IPv4 */ 1201 inc.inc_faddr = faddr; 1202 1203 mtu = ntohs(icp->icmp_nextmtu); 1204 /* 1205 * If no alternative MTU was 1206 * proposed, try the next smaller 1207 * one. ip->ip_len has already 1208 * been swapped in icmp_input(). 1209 */ 1210 if (!mtu) 1211 mtu = ip_next_mtu(ip->ip_len, 1212 1); 1213 if (mtu < max(296, (tcp_minmss) 1214 + sizeof(struct tcpiphdr))) 1215 mtu = 0; 1216 if (!mtu) 1217 mtu = tcp_mssdflt 1218 + sizeof(struct tcpiphdr); 1219 /* 1220 * Only cache the the MTU if it 1221 * is smaller than the interface 1222 * or route MTU. tcp_mtudisc() 1223 * will do right thing by itself. 1224 */ 1225 if (mtu <= tcp_maxmtu(&inc)) 1226 tcp_hc_updatemtu(&inc, mtu); 1227 } 1228 1229 inp = (*notify)(inp, inetctlerrmap[cmd]); 1230 } 1231 } 1232 if (inp != NULL) 1233 INP_UNLOCK(inp); 1234 } else { 1235 inc.inc_fport = th->th_dport; 1236 inc.inc_lport = th->th_sport; 1237 inc.inc_faddr = faddr; 1238 inc.inc_laddr = ip->ip_src; 1239 #ifdef INET6 1240 inc.inc_isipv6 = 0; 1241 #endif 1242 syncache_unreach(&inc, th); 1243 } 1244 INP_INFO_WUNLOCK(&tcbinfo); 1245 } else 1246 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1247 } 1248 1249 #ifdef INET6 1250 void 1251 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1252 { 1253 struct tcphdr th; 1254 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1255 struct ip6_hdr *ip6; 1256 struct mbuf *m; 1257 struct ip6ctlparam *ip6cp = NULL; 1258 const struct sockaddr_in6 *sa6_src = NULL; 1259 int off; 1260 struct tcp_portonly { 1261 u_int16_t th_sport; 1262 u_int16_t th_dport; 1263 } *thp; 1264 1265 if (sa->sa_family != AF_INET6 || 1266 sa->sa_len != sizeof(struct sockaddr_in6)) 1267 return; 1268 1269 if (cmd == PRC_MSGSIZE) 1270 notify = tcp_mtudisc; 1271 else if (!PRC_IS_REDIRECT(cmd) && 1272 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1273 return; 1274 /* Source quench is depreciated. */ 1275 else if (cmd == PRC_QUENCH) 1276 return; 1277 1278 /* if the parameter is from icmp6, decode it. */ 1279 if (d != NULL) { 1280 ip6cp = (struct ip6ctlparam *)d; 1281 m = ip6cp->ip6c_m; 1282 ip6 = ip6cp->ip6c_ip6; 1283 off = ip6cp->ip6c_off; 1284 sa6_src = ip6cp->ip6c_src; 1285 } else { 1286 m = NULL; 1287 ip6 = NULL; 1288 off = 0; /* fool gcc */ 1289 sa6_src = &sa6_any; 1290 } 1291 1292 if (ip6 != NULL) { 1293 struct in_conninfo inc; 1294 /* 1295 * XXX: We assume that when IPV6 is non NULL, 1296 * M and OFF are valid. 1297 */ 1298 1299 /* check if we can safely examine src and dst ports */ 1300 if (m->m_pkthdr.len < off + sizeof(*thp)) 1301 return; 1302 1303 bzero(&th, sizeof(th)); 1304 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1305 1306 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1307 (struct sockaddr *)ip6cp->ip6c_src, 1308 th.th_sport, cmd, NULL, notify); 1309 1310 inc.inc_fport = th.th_dport; 1311 inc.inc_lport = th.th_sport; 1312 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1313 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1314 inc.inc_isipv6 = 1; 1315 INP_INFO_WLOCK(&tcbinfo); 1316 syncache_unreach(&inc, &th); 1317 INP_INFO_WUNLOCK(&tcbinfo); 1318 } else 1319 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1320 0, cmd, NULL, notify); 1321 } 1322 #endif /* INET6 */ 1323 1324 1325 /* 1326 * Following is where TCP initial sequence number generation occurs. 1327 * 1328 * There are two places where we must use initial sequence numbers: 1329 * 1. In SYN-ACK packets. 1330 * 2. In SYN packets. 1331 * 1332 * All ISNs for SYN-ACK packets are generated by the syncache. See 1333 * tcp_syncache.c for details. 1334 * 1335 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1336 * depends on this property. In addition, these ISNs should be 1337 * unguessable so as to prevent connection hijacking. To satisfy 1338 * the requirements of this situation, the algorithm outlined in 1339 * RFC 1948 is used, with only small modifications. 1340 * 1341 * Implementation details: 1342 * 1343 * Time is based off the system timer, and is corrected so that it 1344 * increases by one megabyte per second. This allows for proper 1345 * recycling on high speed LANs while still leaving over an hour 1346 * before rollover. 1347 * 1348 * As reading the *exact* system time is too expensive to be done 1349 * whenever setting up a TCP connection, we increment the time 1350 * offset in two ways. First, a small random positive increment 1351 * is added to isn_offset for each connection that is set up. 1352 * Second, the function tcp_isn_tick fires once per clock tick 1353 * and increments isn_offset as necessary so that sequence numbers 1354 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1355 * random positive increments serve only to ensure that the same 1356 * exact sequence number is never sent out twice (as could otherwise 1357 * happen when a port is recycled in less than the system tick 1358 * interval.) 1359 * 1360 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1361 * between seeding of isn_secret. This is normally set to zero, 1362 * as reseeding should not be necessary. 1363 * 1364 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1365 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1366 * general, this means holding an exclusive (write) lock. 1367 */ 1368 1369 #define ISN_BYTES_PER_SECOND 1048576 1370 #define ISN_STATIC_INCREMENT 4096 1371 #define ISN_RANDOM_INCREMENT (4096 - 1) 1372 1373 static u_char isn_secret[32]; 1374 static int isn_last_reseed; 1375 static u_int32_t isn_offset, isn_offset_old; 1376 static MD5_CTX isn_ctx; 1377 1378 tcp_seq 1379 tcp_new_isn(struct tcpcb *tp) 1380 { 1381 u_int32_t md5_buffer[4]; 1382 tcp_seq new_isn; 1383 1384 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1385 INP_LOCK_ASSERT(tp->t_inpcb); 1386 1387 /* Seed if this is the first use, reseed if requested. */ 1388 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1389 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1390 < (u_int)ticks))) { 1391 read_random(&isn_secret, sizeof(isn_secret)); 1392 isn_last_reseed = ticks; 1393 } 1394 1395 /* Compute the md5 hash and return the ISN. */ 1396 MD5Init(&isn_ctx); 1397 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1398 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1399 #ifdef INET6 1400 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1401 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1402 sizeof(struct in6_addr)); 1403 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1404 sizeof(struct in6_addr)); 1405 } else 1406 #endif 1407 { 1408 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1409 sizeof(struct in_addr)); 1410 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1411 sizeof(struct in_addr)); 1412 } 1413 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1414 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1415 new_isn = (tcp_seq) md5_buffer[0]; 1416 isn_offset += ISN_STATIC_INCREMENT + 1417 (arc4random() & ISN_RANDOM_INCREMENT); 1418 new_isn += isn_offset; 1419 return (new_isn); 1420 } 1421 1422 /* 1423 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1424 * to keep time flowing at a relatively constant rate. If the random 1425 * increments have already pushed us past the projected offset, do nothing. 1426 */ 1427 static void 1428 tcp_isn_tick(void *xtp) 1429 { 1430 u_int32_t projected_offset; 1431 1432 INP_INFO_WLOCK(&tcbinfo); 1433 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1434 1435 if (projected_offset > isn_offset) 1436 isn_offset = projected_offset; 1437 1438 isn_offset_old = isn_offset; 1439 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1440 INP_INFO_WUNLOCK(&tcbinfo); 1441 } 1442 1443 /* 1444 * When a specific ICMP unreachable message is received and the 1445 * connection state is SYN-SENT, drop the connection. This behavior 1446 * is controlled by the icmp_may_rst sysctl. 1447 */ 1448 struct inpcb * 1449 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1450 { 1451 struct tcpcb *tp; 1452 1453 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1454 INP_LOCK_ASSERT(inp); 1455 1456 if ((inp->inp_vflag & INP_TIMEWAIT) || 1457 (inp->inp_vflag & INP_DROPPED)) 1458 return (inp); 1459 1460 tp = intotcpcb(inp); 1461 if (tp->t_state != TCPS_SYN_SENT) 1462 return (inp); 1463 1464 tp = tcp_drop(tp, errno); 1465 if (tp != NULL) 1466 return (inp); 1467 else 1468 return (NULL); 1469 } 1470 1471 /* 1472 * When `need fragmentation' ICMP is received, update our idea of the MSS 1473 * based on the new value in the route. Also nudge TCP to send something, 1474 * since we know the packet we just sent was dropped. 1475 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1476 */ 1477 struct inpcb * 1478 tcp_mtudisc(struct inpcb *inp, int errno) 1479 { 1480 struct tcpcb *tp; 1481 struct socket *so = inp->inp_socket; 1482 u_int maxmtu; 1483 u_int romtu; 1484 int mss; 1485 #ifdef INET6 1486 int isipv6; 1487 #endif /* INET6 */ 1488 1489 INP_LOCK_ASSERT(inp); 1490 if ((inp->inp_vflag & INP_TIMEWAIT) || 1491 (inp->inp_vflag & INP_DROPPED)) 1492 return (inp); 1493 1494 tp = intotcpcb(inp); 1495 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1496 1497 #ifdef INET6 1498 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1499 #endif 1500 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1501 romtu = 1502 #ifdef INET6 1503 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1504 #endif /* INET6 */ 1505 tcp_maxmtu(&inp->inp_inc); 1506 if (!maxmtu) 1507 maxmtu = romtu; 1508 else 1509 maxmtu = min(maxmtu, romtu); 1510 if (!maxmtu) { 1511 tp->t_maxopd = tp->t_maxseg = 1512 #ifdef INET6 1513 isipv6 ? tcp_v6mssdflt : 1514 #endif /* INET6 */ 1515 tcp_mssdflt; 1516 return (inp); 1517 } 1518 mss = maxmtu - 1519 #ifdef INET6 1520 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1521 #endif /* INET6 */ 1522 sizeof(struct tcpiphdr) 1523 #ifdef INET6 1524 ) 1525 #endif /* INET6 */ 1526 ; 1527 1528 /* 1529 * XXX - The above conditional probably violates the TCP 1530 * spec. The problem is that, since we don't know the 1531 * other end's MSS, we are supposed to use a conservative 1532 * default. But, if we do that, then MTU discovery will 1533 * never actually take place, because the conservative 1534 * default is much less than the MTUs typically seen 1535 * on the Internet today. For the moment, we'll sweep 1536 * this under the carpet. 1537 * 1538 * The conservative default might not actually be a problem 1539 * if the only case this occurs is when sending an initial 1540 * SYN with options and data to a host we've never talked 1541 * to before. Then, they will reply with an MSS value which 1542 * will get recorded and the new parameters should get 1543 * recomputed. For Further Study. 1544 */ 1545 if (tp->t_maxopd <= mss) 1546 return (inp); 1547 tp->t_maxopd = mss; 1548 1549 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1550 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1551 mss -= TCPOLEN_TSTAMP_APPA; 1552 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1553 if (mss > MCLBYTES) 1554 mss &= ~(MCLBYTES-1); 1555 #else 1556 if (mss > MCLBYTES) 1557 mss = mss / MCLBYTES * MCLBYTES; 1558 #endif 1559 if (so->so_snd.sb_hiwat < mss) 1560 mss = so->so_snd.sb_hiwat; 1561 1562 tp->t_maxseg = mss; 1563 1564 tcpstat.tcps_mturesent++; 1565 tp->t_rtttime = 0; 1566 tp->snd_nxt = tp->snd_una; 1567 tcp_output(tp); 1568 return (inp); 1569 } 1570 1571 /* 1572 * Look-up the routing entry to the peer of this inpcb. If no route 1573 * is found and it cannot be allocated, then return NULL. This routine 1574 * is called by TCP routines that access the rmx structure and by tcp_mss 1575 * to get the interface MTU. 1576 */ 1577 u_long 1578 tcp_maxmtu(struct in_conninfo *inc) 1579 { 1580 struct route sro; 1581 struct sockaddr_in *dst; 1582 struct ifnet *ifp; 1583 u_long maxmtu = 0; 1584 1585 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1586 1587 bzero(&sro, sizeof(sro)); 1588 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1589 dst = (struct sockaddr_in *)&sro.ro_dst; 1590 dst->sin_family = AF_INET; 1591 dst->sin_len = sizeof(*dst); 1592 dst->sin_addr = inc->inc_faddr; 1593 rtalloc_ign(&sro, RTF_CLONING); 1594 } 1595 if (sro.ro_rt != NULL) { 1596 ifp = sro.ro_rt->rt_ifp; 1597 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1598 maxmtu = ifp->if_mtu; 1599 else 1600 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1601 RTFREE(sro.ro_rt); 1602 } 1603 return (maxmtu); 1604 } 1605 1606 #ifdef INET6 1607 u_long 1608 tcp_maxmtu6(struct in_conninfo *inc) 1609 { 1610 struct route_in6 sro6; 1611 struct ifnet *ifp; 1612 u_long maxmtu = 0; 1613 1614 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1615 1616 bzero(&sro6, sizeof(sro6)); 1617 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1618 sro6.ro_dst.sin6_family = AF_INET6; 1619 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1620 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1621 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1622 } 1623 if (sro6.ro_rt != NULL) { 1624 ifp = sro6.ro_rt->rt_ifp; 1625 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1626 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1627 else 1628 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1629 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1630 RTFREE(sro6.ro_rt); 1631 } 1632 1633 return (maxmtu); 1634 } 1635 #endif /* INET6 */ 1636 1637 #ifdef IPSEC 1638 /* compute ESP/AH header size for TCP, including outer IP header. */ 1639 size_t 1640 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1641 { 1642 struct inpcb *inp; 1643 struct mbuf *m; 1644 size_t hdrsiz; 1645 struct ip *ip; 1646 #ifdef INET6 1647 struct ip6_hdr *ip6; 1648 #endif 1649 struct tcphdr *th; 1650 1651 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1652 return (0); 1653 MGETHDR(m, M_DONTWAIT, MT_DATA); 1654 if (!m) 1655 return (0); 1656 1657 #ifdef INET6 1658 if ((inp->inp_vflag & INP_IPV6) != 0) { 1659 ip6 = mtod(m, struct ip6_hdr *); 1660 th = (struct tcphdr *)(ip6 + 1); 1661 m->m_pkthdr.len = m->m_len = 1662 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1663 tcpip_fillheaders(inp, ip6, th); 1664 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1665 } else 1666 #endif /* INET6 */ 1667 { 1668 ip = mtod(m, struct ip *); 1669 th = (struct tcphdr *)(ip + 1); 1670 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1671 tcpip_fillheaders(inp, ip, th); 1672 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1673 } 1674 1675 m_free(m); 1676 return (hdrsiz); 1677 } 1678 #endif /*IPSEC*/ 1679 1680 /* 1681 * Move a TCP connection into TIME_WAIT state. 1682 * tcbinfo is locked. 1683 * inp is locked, and is unlocked before returning. 1684 */ 1685 void 1686 tcp_twstart(struct tcpcb *tp) 1687 { 1688 struct tcptw *tw; 1689 struct inpcb *inp; 1690 int tw_time, acknow; 1691 struct socket *so; 1692 1693 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1694 INP_LOCK_ASSERT(tp->t_inpcb); 1695 1696 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1697 if (tw == NULL) { 1698 tw = tcp_timer_2msl_tw(1); 1699 if (tw == NULL) { 1700 tp = tcp_close(tp); 1701 if (tp != NULL) 1702 INP_UNLOCK(tp->t_inpcb); 1703 return; 1704 } 1705 } 1706 inp = tp->t_inpcb; 1707 tw->tw_inpcb = inp; 1708 1709 /* 1710 * Recover last window size sent. 1711 */ 1712 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1713 1714 /* 1715 * Set t_recent if timestamps are used on the connection. 1716 */ 1717 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1718 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1719 tw->t_recent = tp->ts_recent; 1720 else 1721 tw->t_recent = 0; 1722 1723 tw->snd_nxt = tp->snd_nxt; 1724 tw->rcv_nxt = tp->rcv_nxt; 1725 tw->iss = tp->iss; 1726 tw->irs = tp->irs; 1727 tw->t_starttime = tp->t_starttime; 1728 tw->tw_time = 0; 1729 1730 /* XXX 1731 * If this code will 1732 * be used for fin-wait-2 state also, then we may need 1733 * a ts_recent from the last segment. 1734 */ 1735 tw_time = 2 * tcp_msl; 1736 acknow = tp->t_flags & TF_ACKNOW; 1737 1738 /* 1739 * First, discard tcpcb state, which includes stopping its timers and 1740 * freeing it. tcp_discardcb() used to also release the inpcb, but 1741 * that work is now done in the caller. 1742 */ 1743 tcp_discardcb(tp); 1744 so = inp->inp_socket; 1745 SOCK_LOCK(so); 1746 tw->tw_cred = crhold(so->so_cred); 1747 tw->tw_so_options = so->so_options; 1748 SOCK_UNLOCK(so); 1749 if (acknow) 1750 tcp_twrespond(tw, TH_ACK); 1751 inp->inp_ppcb = tw; 1752 inp->inp_vflag |= INP_TIMEWAIT; 1753 tcp_timer_2msl_reset(tw, tw_time); 1754 1755 /* 1756 * If the inpcb owns the sole reference to the socket, then we can 1757 * detach and free the socket as it is not needed in time wait. 1758 */ 1759 if (inp->inp_vflag & INP_SOCKREF) { 1760 KASSERT(so->so_state & SS_PROTOREF, 1761 ("tcp_twstart: !SS_PROTOREF")); 1762 inp->inp_vflag &= ~INP_SOCKREF; 1763 #ifdef INET6 1764 if (inp->inp_vflag & INP_IPV6PROTO) 1765 in6_pcbdetach(inp); 1766 else 1767 #endif 1768 in_pcbdetach(inp); 1769 INP_UNLOCK(inp); 1770 ACCEPT_LOCK(); 1771 SOCK_LOCK(so); 1772 so->so_state &= ~SS_PROTOREF; 1773 sofree(so); 1774 } else 1775 INP_UNLOCK(inp); 1776 } 1777 1778 /* 1779 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1780 * the actual rate is slightly higher due to the addition of 1781 * random positive increments. 1782 * 1783 * Most other new OSes use semi-randomized ISN values, so we 1784 * do not need to worry about them. 1785 */ 1786 #define MS_ISN_BYTES_PER_SECOND 250000 1787 1788 /* 1789 * Determine if the ISN we will generate has advanced beyond the last 1790 * sequence number used by the previous connection. If so, indicate 1791 * that it is safe to recycle this tw socket by returning 1. 1792 * 1793 * XXXRW: This function should assert the inpcb lock as it does multiple 1794 * non-atomic reads from the tcptw, but is currently called without it from 1795 * in_pcb.c:in_pcblookup_local(). 1796 */ 1797 int 1798 tcp_twrecycleable(struct tcptw *tw) 1799 { 1800 tcp_seq new_iss = tw->iss; 1801 tcp_seq new_irs = tw->irs; 1802 1803 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1804 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1805 1806 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1807 return (1); 1808 else 1809 return (0); 1810 } 1811 1812 void 1813 tcp_twclose(struct tcptw *tw, int reuse) 1814 { 1815 struct socket *so; 1816 struct inpcb *inp; 1817 1818 /* 1819 * At this point, we are in one of two situations: 1820 * 1821 * (1) We have no socket, just an inpcb<->twtcp pair. Release it all 1822 * after validating. 1823 * 1824 * (2) We have a socket, which we may or may now own the reference 1825 * for. If we own the reference, release all the state after 1826 * validating. If not, leave it for the socket close to clean up. 1827 */ 1828 inp = tw->tw_inpcb; 1829 KASSERT((inp->inp_vflag & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 1830 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 1831 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1832 INP_LOCK_ASSERT(inp); 1833 1834 tw->tw_inpcb = NULL; 1835 tcp_timer_2msl_stop(tw); 1836 inp->inp_ppcb = NULL; 1837 inp->inp_vflag |= INP_DROPPED; 1838 1839 so = inp->inp_socket; 1840 if (so != NULL) { 1841 if (inp->inp_vflag & INP_SOCKREF) { 1842 /* 1843 * If a socket is present, and we own the only 1844 * reference, we need to tear down the socket and the 1845 * inpcb. 1846 */ 1847 inp->inp_vflag &= ~INP_SOCKREF; 1848 #ifdef INET6 1849 if (inp->inp_vflag & INP_IPV6PROTO) { 1850 in6_pcbdetach(inp); 1851 in6_pcbfree(inp); 1852 } else { 1853 in_pcbdetach(inp); 1854 in_pcbfree(inp); 1855 } 1856 #endif 1857 ACCEPT_LOCK(); 1858 SOCK_LOCK(so); 1859 KASSERT(so->so_state & SS_PROTOREF, 1860 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 1861 so->so_state &= ~SS_PROTOREF; 1862 sofree(so); 1863 } else { 1864 /* 1865 * If we don't own the only reference, the socket and 1866 * inpcb need to be left around to be handled by 1867 * tcp_usr_detach() later. 1868 */ 1869 INP_UNLOCK(inp); 1870 } 1871 } else { 1872 #ifdef INET6 1873 if (inp->inp_vflag & INP_IPV6PROTO) 1874 in6_pcbfree(inp); 1875 else 1876 #endif 1877 in_pcbfree(inp); 1878 } 1879 tcpstat.tcps_closed++; 1880 crfree(tw->tw_cred); 1881 tw->tw_cred = NULL; 1882 if (reuse) 1883 return; 1884 uma_zfree(tcptw_zone, tw); 1885 } 1886 1887 int 1888 tcp_twrespond(struct tcptw *tw, int flags) 1889 { 1890 struct inpcb *inp = tw->tw_inpcb; 1891 struct tcphdr *th; 1892 struct mbuf *m; 1893 struct ip *ip = NULL; 1894 u_int8_t *optp; 1895 u_int hdrlen, optlen; 1896 int error; 1897 #ifdef INET6 1898 struct ip6_hdr *ip6 = NULL; 1899 int isipv6 = inp->inp_inc.inc_isipv6; 1900 #endif 1901 1902 INP_LOCK_ASSERT(inp); 1903 1904 m = m_gethdr(M_DONTWAIT, MT_DATA); 1905 if (m == NULL) 1906 return (ENOBUFS); 1907 m->m_data += max_linkhdr; 1908 1909 #ifdef MAC 1910 mac_create_mbuf_from_inpcb(inp, m); 1911 #endif 1912 1913 #ifdef INET6 1914 if (isipv6) { 1915 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1916 ip6 = mtod(m, struct ip6_hdr *); 1917 th = (struct tcphdr *)(ip6 + 1); 1918 tcpip_fillheaders(inp, ip6, th); 1919 } else 1920 #endif 1921 { 1922 hdrlen = sizeof(struct tcpiphdr); 1923 ip = mtod(m, struct ip *); 1924 th = (struct tcphdr *)(ip + 1); 1925 tcpip_fillheaders(inp, ip, th); 1926 } 1927 optp = (u_int8_t *)(th + 1); 1928 1929 /* 1930 * Send a timestamp and echo-reply if both our side and our peer 1931 * have sent timestamps in our SYN's and this is not a RST. 1932 */ 1933 if (tw->t_recent && flags == TH_ACK) { 1934 u_int32_t *lp = (u_int32_t *)optp; 1935 1936 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1937 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1938 *lp++ = htonl(ticks); 1939 *lp = htonl(tw->t_recent); 1940 optp += TCPOLEN_TSTAMP_APPA; 1941 } 1942 1943 optlen = optp - (u_int8_t *)(th + 1); 1944 1945 m->m_len = hdrlen + optlen; 1946 m->m_pkthdr.len = m->m_len; 1947 1948 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1949 1950 th->th_seq = htonl(tw->snd_nxt); 1951 th->th_ack = htonl(tw->rcv_nxt); 1952 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1953 th->th_flags = flags; 1954 th->th_win = htons(tw->last_win); 1955 1956 #ifdef INET6 1957 if (isipv6) { 1958 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1959 sizeof(struct tcphdr) + optlen); 1960 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1961 error = ip6_output(m, inp->in6p_outputopts, NULL, 1962 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1963 } else 1964 #endif 1965 { 1966 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1967 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1968 m->m_pkthdr.csum_flags = CSUM_TCP; 1969 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1970 ip->ip_len = m->m_pkthdr.len; 1971 if (path_mtu_discovery) 1972 ip->ip_off |= IP_DF; 1973 error = ip_output(m, inp->inp_options, NULL, 1974 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1975 NULL, inp); 1976 } 1977 if (flags & TH_ACK) 1978 tcpstat.tcps_sndacks++; 1979 else 1980 tcpstat.tcps_sndctrl++; 1981 tcpstat.tcps_sndtotal++; 1982 return (error); 1983 } 1984 1985 /* 1986 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1987 * 1988 * This code attempts to calculate the bandwidth-delay product as a 1989 * means of determining the optimal window size to maximize bandwidth, 1990 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1991 * routers. This code also does a fairly good job keeping RTTs in check 1992 * across slow links like modems. We implement an algorithm which is very 1993 * similar (but not meant to be) TCP/Vegas. The code operates on the 1994 * transmitter side of a TCP connection and so only effects the transmit 1995 * side of the connection. 1996 * 1997 * BACKGROUND: TCP makes no provision for the management of buffer space 1998 * at the end points or at the intermediate routers and switches. A TCP 1999 * stream, whether using NewReno or not, will eventually buffer as 2000 * many packets as it is able and the only reason this typically works is 2001 * due to the fairly small default buffers made available for a connection 2002 * (typicaly 16K or 32K). As machines use larger windows and/or window 2003 * scaling it is now fairly easy for even a single TCP connection to blow-out 2004 * all available buffer space not only on the local interface, but on 2005 * intermediate routers and switches as well. NewReno makes a misguided 2006 * attempt to 'solve' this problem by waiting for an actual failure to occur, 2007 * then backing off, then steadily increasing the window again until another 2008 * failure occurs, ad-infinitum. This results in terrible oscillation that 2009 * is only made worse as network loads increase and the idea of intentionally 2010 * blowing out network buffers is, frankly, a terrible way to manage network 2011 * resources. 2012 * 2013 * It is far better to limit the transmit window prior to the failure 2014 * condition being achieved. There are two general ways to do this: First 2015 * you can 'scan' through different transmit window sizes and locate the 2016 * point where the RTT stops increasing, indicating that you have filled the 2017 * pipe, then scan backwards until you note that RTT stops decreasing, then 2018 * repeat ad-infinitum. This method works in principle but has severe 2019 * implementation issues due to RTT variances, timer granularity, and 2020 * instability in the algorithm which can lead to many false positives and 2021 * create oscillations as well as interact badly with other TCP streams 2022 * implementing the same algorithm. 2023 * 2024 * The second method is to limit the window to the bandwidth delay product 2025 * of the link. This is the method we implement. RTT variances and our 2026 * own manipulation of the congestion window, bwnd, can potentially 2027 * destabilize the algorithm. For this reason we have to stabilize the 2028 * elements used to calculate the window. We do this by using the minimum 2029 * observed RTT, the long term average of the observed bandwidth, and 2030 * by adding two segments worth of slop. It isn't perfect but it is able 2031 * to react to changing conditions and gives us a very stable basis on 2032 * which to extend the algorithm. 2033 */ 2034 void 2035 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 2036 { 2037 u_long bw; 2038 u_long bwnd; 2039 int save_ticks; 2040 2041 INP_LOCK_ASSERT(tp->t_inpcb); 2042 2043 /* 2044 * If inflight_enable is disabled in the middle of a tcp connection, 2045 * make sure snd_bwnd is effectively disabled. 2046 */ 2047 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 2048 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 2049 tp->snd_bandwidth = 0; 2050 return; 2051 } 2052 2053 /* 2054 * Figure out the bandwidth. Due to the tick granularity this 2055 * is a very rough number and it MUST be averaged over a fairly 2056 * long period of time. XXX we need to take into account a link 2057 * that is not using all available bandwidth, but for now our 2058 * slop will ramp us up if this case occurs and the bandwidth later 2059 * increases. 2060 * 2061 * Note: if ticks rollover 'bw' may wind up negative. We must 2062 * effectively reset t_bw_rtttime for this case. 2063 */ 2064 save_ticks = ticks; 2065 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 2066 return; 2067 2068 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 2069 (save_ticks - tp->t_bw_rtttime); 2070 tp->t_bw_rtttime = save_ticks; 2071 tp->t_bw_rtseq = ack_seq; 2072 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 2073 return; 2074 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 2075 2076 tp->snd_bandwidth = bw; 2077 2078 /* 2079 * Calculate the semi-static bandwidth delay product, plus two maximal 2080 * segments. The additional slop puts us squarely in the sweet 2081 * spot and also handles the bandwidth run-up case and stabilization. 2082 * Without the slop we could be locking ourselves into a lower 2083 * bandwidth. 2084 * 2085 * Situations Handled: 2086 * (1) Prevents over-queueing of packets on LANs, especially on 2087 * high speed LANs, allowing larger TCP buffers to be 2088 * specified, and also does a good job preventing 2089 * over-queueing of packets over choke points like modems 2090 * (at least for the transmit side). 2091 * 2092 * (2) Is able to handle changing network loads (bandwidth 2093 * drops so bwnd drops, bandwidth increases so bwnd 2094 * increases). 2095 * 2096 * (3) Theoretically should stabilize in the face of multiple 2097 * connections implementing the same algorithm (this may need 2098 * a little work). 2099 * 2100 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2101 * be adjusted with a sysctl but typically only needs to be 2102 * on very slow connections. A value no smaller then 5 2103 * should be used, but only reduce this default if you have 2104 * no other choice. 2105 */ 2106 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2107 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2108 #undef USERTT 2109 2110 if (tcp_inflight_debug > 0) { 2111 static int ltime; 2112 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2113 ltime = ticks; 2114 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2115 tp, 2116 bw, 2117 tp->t_rttbest, 2118 tp->t_srtt, 2119 bwnd 2120 ); 2121 } 2122 } 2123 if ((long)bwnd < tcp_inflight_min) 2124 bwnd = tcp_inflight_min; 2125 if (bwnd > tcp_inflight_max) 2126 bwnd = tcp_inflight_max; 2127 if ((long)bwnd < tp->t_maxseg * 2) 2128 bwnd = tp->t_maxseg * 2; 2129 tp->snd_bwnd = bwnd; 2130 } 2131 2132 #ifdef TCP_SIGNATURE 2133 /* 2134 * Callback function invoked by m_apply() to digest TCP segment data 2135 * contained within an mbuf chain. 2136 */ 2137 static int 2138 tcp_signature_apply(void *fstate, void *data, u_int len) 2139 { 2140 2141 MD5Update(fstate, (u_char *)data, len); 2142 return (0); 2143 } 2144 2145 /* 2146 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2147 * 2148 * Parameters: 2149 * m pointer to head of mbuf chain 2150 * off0 offset to TCP header within the mbuf chain 2151 * len length of TCP segment data, excluding options 2152 * optlen length of TCP segment options 2153 * buf pointer to storage for computed MD5 digest 2154 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2155 * 2156 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2157 * When called from tcp_input(), we can be sure that th_sum has been 2158 * zeroed out and verified already. 2159 * 2160 * This function is for IPv4 use only. Calling this function with an 2161 * IPv6 packet in the mbuf chain will yield undefined results. 2162 * 2163 * Return 0 if successful, otherwise return -1. 2164 * 2165 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2166 * search with the destination IP address, and a 'magic SPI' to be 2167 * determined by the application. This is hardcoded elsewhere to 1179 2168 * right now. Another branch of this code exists which uses the SPD to 2169 * specify per-application flows but it is unstable. 2170 */ 2171 int 2172 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2173 u_char *buf, u_int direction) 2174 { 2175 union sockaddr_union dst; 2176 struct ippseudo ippseudo; 2177 MD5_CTX ctx; 2178 int doff; 2179 struct ip *ip; 2180 struct ipovly *ipovly; 2181 struct secasvar *sav; 2182 struct tcphdr *th; 2183 u_short savecsum; 2184 2185 KASSERT(m != NULL, ("NULL mbuf chain")); 2186 KASSERT(buf != NULL, ("NULL signature pointer")); 2187 2188 /* Extract the destination from the IP header in the mbuf. */ 2189 ip = mtod(m, struct ip *); 2190 bzero(&dst, sizeof(union sockaddr_union)); 2191 dst.sa.sa_len = sizeof(struct sockaddr_in); 2192 dst.sa.sa_family = AF_INET; 2193 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2194 ip->ip_src : ip->ip_dst; 2195 2196 /* Look up an SADB entry which matches the address of the peer. */ 2197 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2198 if (sav == NULL) { 2199 printf("%s: SADB lookup failed for %s\n", __func__, 2200 inet_ntoa(dst.sin.sin_addr)); 2201 return (EINVAL); 2202 } 2203 2204 MD5Init(&ctx); 2205 ipovly = (struct ipovly *)ip; 2206 th = (struct tcphdr *)((u_char *)ip + off0); 2207 doff = off0 + sizeof(struct tcphdr) + optlen; 2208 2209 /* 2210 * Step 1: Update MD5 hash with IP pseudo-header. 2211 * 2212 * XXX The ippseudo header MUST be digested in network byte order, 2213 * or else we'll fail the regression test. Assume all fields we've 2214 * been doing arithmetic on have been in host byte order. 2215 * XXX One cannot depend on ipovly->ih_len here. When called from 2216 * tcp_output(), the underlying ip_len member has not yet been set. 2217 */ 2218 ippseudo.ippseudo_src = ipovly->ih_src; 2219 ippseudo.ippseudo_dst = ipovly->ih_dst; 2220 ippseudo.ippseudo_pad = 0; 2221 ippseudo.ippseudo_p = IPPROTO_TCP; 2222 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2223 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2224 2225 /* 2226 * Step 2: Update MD5 hash with TCP header, excluding options. 2227 * The TCP checksum must be set to zero. 2228 */ 2229 savecsum = th->th_sum; 2230 th->th_sum = 0; 2231 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2232 th->th_sum = savecsum; 2233 2234 /* 2235 * Step 3: Update MD5 hash with TCP segment data. 2236 * Use m_apply() to avoid an early m_pullup(). 2237 */ 2238 if (len > 0) 2239 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2240 2241 /* 2242 * Step 4: Update MD5 hash with shared secret. 2243 */ 2244 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2245 MD5Final(buf, &ctx); 2246 2247 key_sa_recordxfer(sav, m); 2248 KEY_FREESAV(&sav); 2249 return (0); 2250 } 2251 #endif /* TCP_SIGNATURE */ 2252 2253 static int 2254 sysctl_drop(SYSCTL_HANDLER_ARGS) 2255 { 2256 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2257 struct sockaddr_storage addrs[2]; 2258 struct inpcb *inp; 2259 struct tcpcb *tp; 2260 struct tcptw *tw; 2261 struct sockaddr_in *fin, *lin; 2262 #ifdef INET6 2263 struct sockaddr_in6 *fin6, *lin6; 2264 struct in6_addr f6, l6; 2265 #endif 2266 int error; 2267 2268 inp = NULL; 2269 fin = lin = NULL; 2270 #ifdef INET6 2271 fin6 = lin6 = NULL; 2272 #endif 2273 error = 0; 2274 2275 if (req->oldptr != NULL || req->oldlen != 0) 2276 return (EINVAL); 2277 if (req->newptr == NULL) 2278 return (EPERM); 2279 if (req->newlen < sizeof(addrs)) 2280 return (ENOMEM); 2281 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2282 if (error) 2283 return (error); 2284 2285 switch (addrs[0].ss_family) { 2286 #ifdef INET6 2287 case AF_INET6: 2288 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2289 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2290 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2291 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2292 return (EINVAL); 2293 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2294 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2295 return (EINVAL); 2296 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2297 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2298 fin = (struct sockaddr_in *)&addrs[0]; 2299 lin = (struct sockaddr_in *)&addrs[1]; 2300 break; 2301 } 2302 error = sa6_embedscope(fin6, ip6_use_defzone); 2303 if (error) 2304 return (error); 2305 error = sa6_embedscope(lin6, ip6_use_defzone); 2306 if (error) 2307 return (error); 2308 break; 2309 #endif 2310 case AF_INET: 2311 fin = (struct sockaddr_in *)&addrs[0]; 2312 lin = (struct sockaddr_in *)&addrs[1]; 2313 if (fin->sin_len != sizeof(struct sockaddr_in) || 2314 lin->sin_len != sizeof(struct sockaddr_in)) 2315 return (EINVAL); 2316 break; 2317 default: 2318 return (EINVAL); 2319 } 2320 INP_INFO_WLOCK(&tcbinfo); 2321 switch (addrs[0].ss_family) { 2322 #ifdef INET6 2323 case AF_INET6: 2324 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2325 &l6, lin6->sin6_port, 0, NULL); 2326 break; 2327 #endif 2328 case AF_INET: 2329 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2330 lin->sin_addr, lin->sin_port, 0, NULL); 2331 break; 2332 } 2333 if (inp != NULL) { 2334 INP_LOCK(inp); 2335 if (inp->inp_vflag & INP_TIMEWAIT) { 2336 /* 2337 * XXXRW: There currently exists a state where an 2338 * inpcb is present, but its timewait state has been 2339 * discarded. For now, don't allow dropping of this 2340 * type of inpcb. 2341 */ 2342 tw = intotw(inp); 2343 if (tw != NULL) 2344 tcp_twclose(tw, 0); 2345 } else if (!(inp->inp_vflag & INP_DROPPED) && 2346 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2347 tp = intotcpcb(inp); 2348 tcp_drop(tp, ECONNABORTED); 2349 } 2350 INP_UNLOCK(inp); 2351 } else 2352 error = ESRCH; 2353 INP_INFO_WUNLOCK(&tcbinfo); 2354 return (error); 2355 } 2356 2357 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2358 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2359 0, sysctl_drop, "", "Drop TCP connection"); 2360