Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_subr.c
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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: releng/6.0/sys/netinet/tcp_subr.c 151169 2005-10-09 08:21:34Z maxim $ 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/nd6.h> 78 #endif 79 #include <netinet/ip_icmp.h> 80 #include <netinet/tcp.h> 81 #include <netinet/tcp_fsm.h> 82 #include <netinet/tcp_seq.h> 83 #include <netinet/tcp_timer.h> 84 #include <netinet/tcp_var.h> 85 #ifdef INET6 86 #include <netinet6/tcp6_var.h> 87 #endif 88 #include <netinet/tcpip.h> 89 #ifdef TCPDEBUG 90 #include <netinet/tcp_debug.h> 91 #endif 92 #include <netinet6/ip6protosw.h> 93 94 #ifdef IPSEC 95 #include <netinet6/ipsec.h> 96 #ifdef INET6 97 #include <netinet6/ipsec6.h> 98 #endif 99 #include <netkey/key.h> 100 #endif /*IPSEC*/ 101 102 #ifdef FAST_IPSEC 103 #include <netipsec/ipsec.h> 104 #include <netipsec/xform.h> 105 #ifdef INET6 106 #include <netipsec/ipsec6.h> 107 #endif 108 #include <netipsec/key.h> 109 #define IPSEC 110 #endif /*FAST_IPSEC*/ 111 112 #include <machine/in_cksum.h> 113 #include <sys/md5.h> 114 115 int tcp_mssdflt = TCP_MSS; 116 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 117 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 118 119 #ifdef INET6 120 int tcp_v6mssdflt = TCP6_MSS; 121 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 122 CTLFLAG_RW, &tcp_v6mssdflt , 0, 123 "Default TCP Maximum Segment Size for IPv6"); 124 #endif 125 126 /* 127 * Minimum MSS we accept and use. This prevents DoS attacks where 128 * we are forced to a ridiculous low MSS like 20 and send hundreds 129 * of packets instead of one. The effect scales with the available 130 * bandwidth and quickly saturates the CPU and network interface 131 * with packet generation and sending. Set to zero to disable MINMSS 132 * checking. This setting prevents us from sending too small packets. 133 */ 134 int tcp_minmss = TCP_MINMSS; 135 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 136 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 137 /* 138 * Number of TCP segments per second we accept from remote host 139 * before we start to calculate average segment size. If average 140 * segment size drops below the minimum TCP MSS we assume a DoS 141 * attack and reset+drop the connection. Care has to be taken not to 142 * set this value too small to not kill interactive type connections 143 * (telnet, SSH) which send many small packets. 144 */ 145 int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 146 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW, 147 &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to" 148 "be under the MINMSS Size"); 149 150 #if 0 151 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 152 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 153 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 154 #endif 155 156 int tcp_do_rfc1323 = 1; 157 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 158 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 159 160 static int tcp_tcbhashsize = 0; 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 162 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 163 164 static int do_tcpdrain = 1; 165 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 166 "Enable tcp_drain routine for extra help when low on mbufs"); 167 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 169 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 170 171 static int icmp_may_rst = 1; 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 173 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 174 175 static int tcp_isn_reseed_interval = 0; 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 177 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 178 179 /* 180 * TCP bandwidth limiting sysctls. Note that the default lower bound of 181 * 1024 exists only for debugging. A good production default would be 182 * something like 6100. 183 */ 184 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 185 "TCP inflight data limiting"); 186 187 static int tcp_inflight_enable = 1; 188 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 189 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 190 191 static int tcp_inflight_debug = 0; 192 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 193 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 194 195 static int tcp_inflight_min = 6144; 196 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 197 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 198 199 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 200 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 201 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 202 203 static int tcp_inflight_stab = 20; 204 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 205 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 206 207 uma_zone_t sack_hole_zone; 208 209 static struct inpcb *tcp_notify(struct inpcb *, int); 210 static void tcp_discardcb(struct tcpcb *); 211 static void tcp_isn_tick(void *); 212 213 /* 214 * Target size of TCP PCB hash tables. Must be a power of two. 215 * 216 * Note that this can be overridden by the kernel environment 217 * variable net.inet.tcp.tcbhashsize 218 */ 219 #ifndef TCBHASHSIZE 220 #define TCBHASHSIZE 512 221 #endif 222 223 /* 224 * XXX 225 * Callouts should be moved into struct tcp directly. They are currently 226 * separate because the tcpcb structure is exported to userland for sysctl 227 * parsing purposes, which do not know about callouts. 228 */ 229 struct tcpcb_mem { 230 struct tcpcb tcb; 231 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 232 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 233 }; 234 235 static uma_zone_t tcpcb_zone; 236 static uma_zone_t tcptw_zone; 237 struct callout isn_callout; 238 239 /* 240 * Tcp initialization 241 */ 242 void 243 tcp_init() 244 { 245 int hashsize = TCBHASHSIZE; 246 247 tcp_delacktime = TCPTV_DELACK; 248 tcp_keepinit = TCPTV_KEEP_INIT; 249 tcp_keepidle = TCPTV_KEEP_IDLE; 250 tcp_keepintvl = TCPTV_KEEPINTVL; 251 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 252 tcp_msl = TCPTV_MSL; 253 tcp_rexmit_min = TCPTV_MIN; 254 tcp_rexmit_slop = TCPTV_CPU_VAR; 255 256 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 257 LIST_INIT(&tcb); 258 tcbinfo.listhead = &tcb; 259 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 260 if (!powerof2(hashsize)) { 261 printf("WARNING: TCB hash size not a power of 2\n"); 262 hashsize = 512; /* safe default */ 263 } 264 tcp_tcbhashsize = hashsize; 265 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 266 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 267 &tcbinfo.porthashmask); 268 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 269 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 270 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 271 #ifdef INET6 272 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 273 #else /* INET6 */ 274 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 275 #endif /* INET6 */ 276 if (max_protohdr < TCP_MINPROTOHDR) 277 max_protohdr = TCP_MINPROTOHDR; 278 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 279 panic("tcp_init"); 280 #undef TCP_MINPROTOHDR 281 /* 282 * These have to be type stable for the benefit of the timers. 283 */ 284 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 285 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 286 uma_zone_set_max(tcpcb_zone, maxsockets); 287 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 288 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 289 uma_zone_set_max(tcptw_zone, maxsockets / 5); 290 tcp_timer_init(); 291 syncache_init(); 292 tcp_hc_init(); 293 tcp_reass_init(); 294 callout_init(&isn_callout, CALLOUT_MPSAFE); 295 tcp_isn_tick(NULL); 296 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 297 SHUTDOWN_PRI_DEFAULT); 298 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 299 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 300 } 301 302 void 303 tcp_fini(xtp) 304 void *xtp; 305 { 306 callout_stop(&isn_callout); 307 308 } 309 310 /* 311 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 312 * tcp_template used to store this data in mbufs, but we now recopy it out 313 * of the tcpcb each time to conserve mbufs. 314 */ 315 void 316 tcpip_fillheaders(inp, ip_ptr, tcp_ptr) 317 struct inpcb *inp; 318 void *ip_ptr; 319 void *tcp_ptr; 320 { 321 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 322 323 INP_LOCK_ASSERT(inp); 324 325 #ifdef INET6 326 if ((inp->inp_vflag & INP_IPV6) != 0) { 327 struct ip6_hdr *ip6; 328 329 ip6 = (struct ip6_hdr *)ip_ptr; 330 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 331 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 332 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 333 (IPV6_VERSION & IPV6_VERSION_MASK); 334 ip6->ip6_nxt = IPPROTO_TCP; 335 ip6->ip6_plen = sizeof(struct tcphdr); 336 ip6->ip6_src = inp->in6p_laddr; 337 ip6->ip6_dst = inp->in6p_faddr; 338 } else 339 #endif 340 { 341 struct ip *ip; 342 343 ip = (struct ip *)ip_ptr; 344 ip->ip_v = IPVERSION; 345 ip->ip_hl = 5; 346 ip->ip_tos = inp->inp_ip_tos; 347 ip->ip_len = 0; 348 ip->ip_id = 0; 349 ip->ip_off = 0; 350 ip->ip_ttl = inp->inp_ip_ttl; 351 ip->ip_sum = 0; 352 ip->ip_p = IPPROTO_TCP; 353 ip->ip_src = inp->inp_laddr; 354 ip->ip_dst = inp->inp_faddr; 355 } 356 th->th_sport = inp->inp_lport; 357 th->th_dport = inp->inp_fport; 358 th->th_seq = 0; 359 th->th_ack = 0; 360 th->th_x2 = 0; 361 th->th_off = 5; 362 th->th_flags = 0; 363 th->th_win = 0; 364 th->th_urp = 0; 365 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 366 } 367 368 /* 369 * Create template to be used to send tcp packets on a connection. 370 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 371 * use for this function is in keepalives, which use tcp_respond. 372 */ 373 struct tcptemp * 374 tcpip_maketemplate(inp) 375 struct inpcb *inp; 376 { 377 struct mbuf *m; 378 struct tcptemp *n; 379 380 m = m_get(M_DONTWAIT, MT_DATA); 381 if (m == NULL) 382 return (0); 383 m->m_len = sizeof(struct tcptemp); 384 n = mtod(m, struct tcptemp *); 385 386 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 387 return (n); 388 } 389 390 /* 391 * Send a single message to the TCP at address specified by 392 * the given TCP/IP header. If m == NULL, then we make a copy 393 * of the tcpiphdr at ti and send directly to the addressed host. 394 * This is used to force keep alive messages out using the TCP 395 * template for a connection. If flags are given then we send 396 * a message back to the TCP which originated the * segment ti, 397 * and discard the mbuf containing it and any other attached mbufs. 398 * 399 * In any case the ack and sequence number of the transmitted 400 * segment are as specified by the parameters. 401 * 402 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 403 */ 404 void 405 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 406 struct tcpcb *tp; 407 void *ipgen; 408 register struct tcphdr *th; 409 register struct mbuf *m; 410 tcp_seq ack, seq; 411 int flags; 412 { 413 register int tlen; 414 int win = 0; 415 struct ip *ip; 416 struct tcphdr *nth; 417 #ifdef INET6 418 struct ip6_hdr *ip6; 419 int isipv6; 420 #endif /* INET6 */ 421 int ipflags = 0; 422 struct inpcb *inp; 423 424 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 425 426 #ifdef INET6 427 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 428 ip6 = ipgen; 429 #endif /* INET6 */ 430 ip = ipgen; 431 432 if (tp != NULL) { 433 inp = tp->t_inpcb; 434 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 435 INP_INFO_WLOCK_ASSERT(&tcbinfo); 436 INP_LOCK_ASSERT(inp); 437 } else 438 inp = NULL; 439 440 if (tp != NULL) { 441 if (!(flags & TH_RST)) { 442 win = sbspace(&inp->inp_socket->so_rcv); 443 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 444 win = (long)TCP_MAXWIN << tp->rcv_scale; 445 } 446 } 447 if (m == NULL) { 448 m = m_gethdr(M_DONTWAIT, MT_HEADER); 449 if (m == NULL) 450 return; 451 tlen = 0; 452 m->m_data += max_linkhdr; 453 #ifdef INET6 454 if (isipv6) { 455 bcopy((caddr_t)ip6, mtod(m, caddr_t), 456 sizeof(struct ip6_hdr)); 457 ip6 = mtod(m, struct ip6_hdr *); 458 nth = (struct tcphdr *)(ip6 + 1); 459 } else 460 #endif /* INET6 */ 461 { 462 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 463 ip = mtod(m, struct ip *); 464 nth = (struct tcphdr *)(ip + 1); 465 } 466 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 467 flags = TH_ACK; 468 } else { 469 m_freem(m->m_next); 470 m->m_next = NULL; 471 m->m_data = (caddr_t)ipgen; 472 /* m_len is set later */ 473 tlen = 0; 474 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 475 #ifdef INET6 476 if (isipv6) { 477 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 478 nth = (struct tcphdr *)(ip6 + 1); 479 } else 480 #endif /* INET6 */ 481 { 482 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 483 nth = (struct tcphdr *)(ip + 1); 484 } 485 if (th != nth) { 486 /* 487 * this is usually a case when an extension header 488 * exists between the IPv6 header and the 489 * TCP header. 490 */ 491 nth->th_sport = th->th_sport; 492 nth->th_dport = th->th_dport; 493 } 494 xchg(nth->th_dport, nth->th_sport, n_short); 495 #undef xchg 496 } 497 #ifdef INET6 498 if (isipv6) { 499 ip6->ip6_flow = 0; 500 ip6->ip6_vfc = IPV6_VERSION; 501 ip6->ip6_nxt = IPPROTO_TCP; 502 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 503 tlen)); 504 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 505 } else 506 #endif 507 { 508 tlen += sizeof (struct tcpiphdr); 509 ip->ip_len = tlen; 510 ip->ip_ttl = ip_defttl; 511 if (path_mtu_discovery) 512 ip->ip_off |= IP_DF; 513 } 514 m->m_len = tlen; 515 m->m_pkthdr.len = tlen; 516 m->m_pkthdr.rcvif = NULL; 517 #ifdef MAC 518 if (inp != NULL) { 519 /* 520 * Packet is associated with a socket, so allow the 521 * label of the response to reflect the socket label. 522 */ 523 INP_LOCK_ASSERT(inp); 524 mac_create_mbuf_from_inpcb(inp, m); 525 } else { 526 /* 527 * Packet is not associated with a socket, so possibly 528 * update the label in place. 529 */ 530 mac_reflect_mbuf_tcp(m); 531 } 532 #endif 533 nth->th_seq = htonl(seq); 534 nth->th_ack = htonl(ack); 535 nth->th_x2 = 0; 536 nth->th_off = sizeof (struct tcphdr) >> 2; 537 nth->th_flags = flags; 538 if (tp != NULL) 539 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 540 else 541 nth->th_win = htons((u_short)win); 542 nth->th_urp = 0; 543 #ifdef INET6 544 if (isipv6) { 545 nth->th_sum = 0; 546 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 547 sizeof(struct ip6_hdr), 548 tlen - sizeof(struct ip6_hdr)); 549 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 550 NULL, NULL); 551 } else 552 #endif /* INET6 */ 553 { 554 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 555 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 556 m->m_pkthdr.csum_flags = CSUM_TCP; 557 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 558 } 559 #ifdef TCPDEBUG 560 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 561 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 562 #endif 563 #ifdef INET6 564 if (isipv6) 565 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 566 else 567 #endif /* INET6 */ 568 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 569 } 570 571 /* 572 * Create a new TCP control block, making an 573 * empty reassembly queue and hooking it to the argument 574 * protocol control block. The `inp' parameter must have 575 * come from the zone allocator set up in tcp_init(). 576 */ 577 struct tcpcb * 578 tcp_newtcpcb(inp) 579 struct inpcb *inp; 580 { 581 struct tcpcb_mem *tm; 582 struct tcpcb *tp; 583 #ifdef INET6 584 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 585 #endif /* INET6 */ 586 587 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 588 if (tm == NULL) 589 return (NULL); 590 tp = &tm->tcb; 591 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 592 tp->t_maxseg = tp->t_maxopd = 593 #ifdef INET6 594 isipv6 ? tcp_v6mssdflt : 595 #endif /* INET6 */ 596 tcp_mssdflt; 597 598 /* Set up our timeouts. */ 599 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, NET_CALLOUT_MPSAFE); 600 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, NET_CALLOUT_MPSAFE); 601 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, NET_CALLOUT_MPSAFE); 602 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, NET_CALLOUT_MPSAFE); 603 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, NET_CALLOUT_MPSAFE); 604 605 if (tcp_do_rfc1323) 606 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 607 tp->sack_enable = tcp_do_sack; 608 TAILQ_INIT(&tp->snd_holes); 609 tp->t_inpcb = inp; /* XXX */ 610 /* 611 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 612 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 613 * reasonable initial retransmit time. 614 */ 615 tp->t_srtt = TCPTV_SRTTBASE; 616 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 617 tp->t_rttmin = tcp_rexmit_min; 618 tp->t_rxtcur = TCPTV_RTOBASE; 619 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 620 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 621 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 622 tp->t_rcvtime = ticks; 623 tp->t_bw_rtttime = ticks; 624 /* 625 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 626 * because the socket may be bound to an IPv6 wildcard address, 627 * which may match an IPv4-mapped IPv6 address. 628 */ 629 inp->inp_ip_ttl = ip_defttl; 630 inp->inp_ppcb = (caddr_t)tp; 631 return (tp); /* XXX */ 632 } 633 634 /* 635 * Drop a TCP connection, reporting 636 * the specified error. If connection is synchronized, 637 * then send a RST to peer. 638 */ 639 struct tcpcb * 640 tcp_drop(tp, errno) 641 register struct tcpcb *tp; 642 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 static void 662 tcp_discardcb(tp) 663 struct tcpcb *tp; 664 { 665 struct tseg_qent *q; 666 struct inpcb *inp = tp->t_inpcb; 667 struct socket *so = inp->inp_socket; 668 #ifdef INET6 669 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 670 #endif /* INET6 */ 671 672 INP_LOCK_ASSERT(inp); 673 674 /* 675 * Make sure that all of our timers are stopped before we 676 * delete the PCB. 677 */ 678 callout_stop(tp->tt_rexmt); 679 callout_stop(tp->tt_persist); 680 callout_stop(tp->tt_keep); 681 callout_stop(tp->tt_2msl); 682 callout_stop(tp->tt_delack); 683 684 /* 685 * If we got enough samples through the srtt filter, 686 * save the rtt and rttvar in the routing entry. 687 * 'Enough' is arbitrarily defined as 4 rtt samples. 688 * 4 samples is enough for the srtt filter to converge 689 * to within enough % of the correct value; fewer samples 690 * and we could save a bogus rtt. The danger is not high 691 * as tcp quickly recovers from everything. 692 * XXX: Works very well but needs some more statistics! 693 */ 694 if (tp->t_rttupdated >= 4) { 695 struct hc_metrics_lite metrics; 696 u_long ssthresh; 697 698 bzero(&metrics, sizeof(metrics)); 699 /* 700 * Update the ssthresh always when the conditions below 701 * are satisfied. This gives us better new start value 702 * for the congestion avoidance for new connections. 703 * ssthresh is only set if packet loss occured on a session. 704 */ 705 ssthresh = tp->snd_ssthresh; 706 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 707 /* 708 * convert the limit from user data bytes to 709 * packets then to packet data bytes. 710 */ 711 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 712 if (ssthresh < 2) 713 ssthresh = 2; 714 ssthresh *= (u_long)(tp->t_maxseg + 715 #ifdef INET6 716 (isipv6 ? sizeof (struct ip6_hdr) + 717 sizeof (struct tcphdr) : 718 #endif 719 sizeof (struct tcpiphdr) 720 #ifdef INET6 721 ) 722 #endif 723 ); 724 } else 725 ssthresh = 0; 726 metrics.rmx_ssthresh = ssthresh; 727 728 metrics.rmx_rtt = tp->t_srtt; 729 metrics.rmx_rttvar = tp->t_rttvar; 730 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 731 metrics.rmx_bandwidth = tp->snd_bandwidth; 732 metrics.rmx_cwnd = tp->snd_cwnd; 733 metrics.rmx_sendpipe = 0; 734 metrics.rmx_recvpipe = 0; 735 736 tcp_hc_update(&inp->inp_inc, &metrics); 737 } 738 739 /* free the reassembly queue, if any */ 740 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 741 LIST_REMOVE(q, tqe_q); 742 m_freem(q->tqe_m); 743 uma_zfree(tcp_reass_zone, q); 744 tp->t_segqlen--; 745 tcp_reass_qsize--; 746 } 747 tcp_free_sackholes(tp); 748 inp->inp_ppcb = NULL; 749 tp->t_inpcb = NULL; 750 uma_zfree(tcpcb_zone, tp); 751 soisdisconnected(so); 752 } 753 754 /* 755 * Close a TCP control block: 756 * discard all space held by the tcp 757 * discard internet protocol block 758 * wake up any sleepers 759 */ 760 struct tcpcb * 761 tcp_close(tp) 762 struct tcpcb *tp; 763 { 764 struct inpcb *inp = tp->t_inpcb; 765 #ifdef INET6 766 struct socket *so = inp->inp_socket; 767 #endif 768 769 INP_INFO_WLOCK_ASSERT(&tcbinfo); 770 INP_LOCK_ASSERT(inp); 771 772 tcp_discardcb(tp); 773 #ifdef INET6 774 if (INP_CHECK_SOCKAF(so, AF_INET6)) 775 in6_pcbdetach(inp); 776 else 777 #endif 778 in_pcbdetach(inp); 779 tcpstat.tcps_closed++; 780 return (NULL); 781 } 782 783 void 784 tcp_drain() 785 { 786 if (do_tcpdrain) 787 { 788 struct inpcb *inpb; 789 struct tcpcb *tcpb; 790 struct tseg_qent *te; 791 792 /* 793 * Walk the tcpbs, if existing, and flush the reassembly queue, 794 * if there is one... 795 * XXX: The "Net/3" implementation doesn't imply that the TCP 796 * reassembly queue should be flushed, but in a situation 797 * where we're really low on mbufs, this is potentially 798 * usefull. 799 */ 800 INP_INFO_RLOCK(&tcbinfo); 801 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 802 if (inpb->inp_vflag & INP_TIMEWAIT) 803 continue; 804 INP_LOCK(inpb); 805 if ((tcpb = intotcpcb(inpb)) != NULL) { 806 while ((te = LIST_FIRST(&tcpb->t_segq)) 807 != NULL) { 808 LIST_REMOVE(te, tqe_q); 809 m_freem(te->tqe_m); 810 uma_zfree(tcp_reass_zone, te); 811 tcpb->t_segqlen--; 812 tcp_reass_qsize--; 813 } 814 tcp_clean_sackreport(tcpb); 815 } 816 INP_UNLOCK(inpb); 817 } 818 INP_INFO_RUNLOCK(&tcbinfo); 819 } 820 } 821 822 /* 823 * Notify a tcp user of an asynchronous error; 824 * store error as soft error, but wake up user 825 * (for now, won't do anything until can select for soft error). 826 * 827 * Do not wake up user since there currently is no mechanism for 828 * reporting soft errors (yet - a kqueue filter may be added). 829 */ 830 static struct inpcb * 831 tcp_notify(inp, error) 832 struct inpcb *inp; 833 int error; 834 { 835 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 836 837 INP_INFO_WLOCK_ASSERT(&tcbinfo); 838 INP_LOCK_ASSERT(inp); 839 840 /* 841 * Ignore some errors if we are hooked up. 842 * If connection hasn't completed, has retransmitted several times, 843 * and receives a second error, give up now. This is better 844 * than waiting a long time to establish a connection that 845 * can never complete. 846 */ 847 if (tp->t_state == TCPS_ESTABLISHED && 848 (error == EHOSTUNREACH || error == ENETUNREACH || 849 error == EHOSTDOWN)) { 850 return (inp); 851 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 852 tp->t_softerror) { 853 tcp_drop(tp, error); 854 return (struct inpcb *)0; 855 } else { 856 tp->t_softerror = error; 857 return (inp); 858 } 859 #if 0 860 wakeup( &so->so_timeo); 861 sorwakeup(so); 862 sowwakeup(so); 863 #endif 864 } 865 866 static int 867 tcp_pcblist(SYSCTL_HANDLER_ARGS) 868 { 869 int error, i, n; 870 struct inpcb *inp, **inp_list; 871 inp_gen_t gencnt; 872 struct xinpgen xig; 873 874 /* 875 * The process of preparing the TCB list is too time-consuming and 876 * resource-intensive to repeat twice on every request. 877 */ 878 if (req->oldptr == NULL) { 879 n = tcbinfo.ipi_count; 880 req->oldidx = 2 * (sizeof xig) 881 + (n + n/8) * sizeof(struct xtcpcb); 882 return (0); 883 } 884 885 if (req->newptr != NULL) 886 return (EPERM); 887 888 /* 889 * OK, now we're committed to doing something. 890 */ 891 INP_INFO_RLOCK(&tcbinfo); 892 gencnt = tcbinfo.ipi_gencnt; 893 n = tcbinfo.ipi_count; 894 INP_INFO_RUNLOCK(&tcbinfo); 895 896 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 897 + n * sizeof(struct xtcpcb)); 898 if (error != 0) 899 return (error); 900 901 xig.xig_len = sizeof xig; 902 xig.xig_count = n; 903 xig.xig_gen = gencnt; 904 xig.xig_sogen = so_gencnt; 905 error = SYSCTL_OUT(req, &xig, sizeof xig); 906 if (error) 907 return (error); 908 909 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 910 if (inp_list == NULL) 911 return (ENOMEM); 912 913 INP_INFO_RLOCK(&tcbinfo); 914 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 915 inp = LIST_NEXT(inp, inp_list)) { 916 INP_LOCK(inp); 917 if (inp->inp_gencnt <= gencnt) { 918 /* 919 * XXX: This use of cr_cansee(), introduced with 920 * TCP state changes, is not quite right, but for 921 * now, better than nothing. 922 */ 923 if (inp->inp_vflag & INP_TIMEWAIT) 924 error = cr_cansee(req->td->td_ucred, 925 intotw(inp)->tw_cred); 926 else 927 error = cr_canseesocket(req->td->td_ucred, 928 inp->inp_socket); 929 if (error == 0) 930 inp_list[i++] = inp; 931 } 932 INP_UNLOCK(inp); 933 } 934 INP_INFO_RUNLOCK(&tcbinfo); 935 n = i; 936 937 error = 0; 938 for (i = 0; i < n; i++) { 939 inp = inp_list[i]; 940 if (inp->inp_gencnt <= gencnt) { 941 struct xtcpcb xt; 942 caddr_t inp_ppcb; 943 944 bzero(&xt, sizeof(xt)); 945 xt.xt_len = sizeof xt; 946 /* XXX should avoid extra copy */ 947 bcopy(inp, &xt.xt_inp, sizeof *inp); 948 inp_ppcb = inp->inp_ppcb; 949 if (inp_ppcb == NULL) 950 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 951 else if (inp->inp_vflag & INP_TIMEWAIT) { 952 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 953 xt.xt_tp.t_state = TCPS_TIME_WAIT; 954 } else 955 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 956 if (inp->inp_socket != NULL) 957 sotoxsocket(inp->inp_socket, &xt.xt_socket); 958 else { 959 bzero(&xt.xt_socket, sizeof xt.xt_socket); 960 xt.xt_socket.xso_protocol = IPPROTO_TCP; 961 } 962 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 963 error = SYSCTL_OUT(req, &xt, sizeof xt); 964 } 965 } 966 if (!error) { 967 /* 968 * Give the user an updated idea of our state. 969 * If the generation differs from what we told 970 * her before, she knows that something happened 971 * while we were processing this request, and it 972 * might be necessary to retry. 973 */ 974 INP_INFO_RLOCK(&tcbinfo); 975 xig.xig_gen = tcbinfo.ipi_gencnt; 976 xig.xig_sogen = so_gencnt; 977 xig.xig_count = tcbinfo.ipi_count; 978 INP_INFO_RUNLOCK(&tcbinfo); 979 error = SYSCTL_OUT(req, &xig, sizeof xig); 980 } 981 free(inp_list, M_TEMP); 982 return (error); 983 } 984 985 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 986 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 987 988 static int 989 tcp_getcred(SYSCTL_HANDLER_ARGS) 990 { 991 struct xucred xuc; 992 struct sockaddr_in addrs[2]; 993 struct inpcb *inp; 994 int error; 995 996 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 997 if (error) 998 return (error); 999 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1000 if (error) 1001 return (error); 1002 INP_INFO_RLOCK(&tcbinfo); 1003 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1004 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1005 if (inp == NULL) { 1006 error = ENOENT; 1007 goto outunlocked; 1008 } 1009 INP_LOCK(inp); 1010 if (inp->inp_socket == NULL) { 1011 error = ENOENT; 1012 goto out; 1013 } 1014 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1015 if (error) 1016 goto out; 1017 cru2x(inp->inp_socket->so_cred, &xuc); 1018 out: 1019 INP_UNLOCK(inp); 1020 outunlocked: 1021 INP_INFO_RUNLOCK(&tcbinfo); 1022 if (error == 0) 1023 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1024 return (error); 1025 } 1026 1027 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1028 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1029 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1030 1031 #ifdef INET6 1032 static int 1033 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1034 { 1035 struct xucred xuc; 1036 struct sockaddr_in6 addrs[2]; 1037 struct in6_addr a6[2]; 1038 struct inpcb *inp; 1039 int error, mapped = 0; 1040 1041 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1042 if (error) 1043 return (error); 1044 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1045 if (error) 1046 return (error); 1047 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1048 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1049 mapped = 1; 1050 else 1051 return (EINVAL); 1052 } else { 1053 error = in6_embedscope(&a6[0], &addrs[0], NULL, NULL); 1054 if (error) 1055 return (EINVAL); 1056 error = in6_embedscope(&a6[1], &addrs[1], NULL, NULL); 1057 if (error) 1058 return (EINVAL); 1059 } 1060 INP_INFO_RLOCK(&tcbinfo); 1061 if (mapped == 1) 1062 inp = in_pcblookup_hash(&tcbinfo, 1063 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1064 addrs[1].sin6_port, 1065 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1066 addrs[0].sin6_port, 1067 0, NULL); 1068 else 1069 inp = in6_pcblookup_hash(&tcbinfo, &a6[1], addrs[1].sin6_port, 1070 &a6[0], addrs[0].sin6_port, 0, NULL); 1071 if (inp == NULL) { 1072 error = ENOENT; 1073 goto outunlocked; 1074 } 1075 INP_LOCK(inp); 1076 if (inp->inp_socket == NULL) { 1077 error = ENOENT; 1078 goto out; 1079 } 1080 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1081 if (error) 1082 goto out; 1083 cru2x(inp->inp_socket->so_cred, &xuc); 1084 out: 1085 INP_UNLOCK(inp); 1086 outunlocked: 1087 INP_INFO_RUNLOCK(&tcbinfo); 1088 if (error == 0) 1089 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1090 return (error); 1091 } 1092 1093 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1094 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1095 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1096 #endif 1097 1098 1099 void 1100 tcp_ctlinput(cmd, sa, vip) 1101 int cmd; 1102 struct sockaddr *sa; 1103 void *vip; 1104 { 1105 struct ip *ip = vip; 1106 struct tcphdr *th; 1107 struct in_addr faddr; 1108 struct inpcb *inp; 1109 struct tcpcb *tp; 1110 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1111 struct icmp *icp; 1112 struct in_conninfo inc; 1113 tcp_seq icmp_tcp_seq; 1114 int mtu; 1115 1116 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1117 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1118 return; 1119 1120 if (cmd == PRC_MSGSIZE) 1121 notify = tcp_mtudisc; 1122 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1123 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1124 notify = tcp_drop_syn_sent; 1125 /* 1126 * Redirects don't need to be handled up here. 1127 */ 1128 else if (PRC_IS_REDIRECT(cmd)) 1129 return; 1130 /* 1131 * Source quench is depreciated. 1132 */ 1133 else if (cmd == PRC_QUENCH) 1134 return; 1135 /* 1136 * Hostdead is ugly because it goes linearly through all PCBs. 1137 * XXX: We never get this from ICMP, otherwise it makes an 1138 * excellent DoS attack on machines with many connections. 1139 */ 1140 else if (cmd == PRC_HOSTDEAD) 1141 ip = NULL; 1142 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1143 return; 1144 if (ip != NULL) { 1145 icp = (struct icmp *)((caddr_t)ip 1146 - offsetof(struct icmp, icmp_ip)); 1147 th = (struct tcphdr *)((caddr_t)ip 1148 + (ip->ip_hl << 2)); 1149 INP_INFO_WLOCK(&tcbinfo); 1150 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1151 ip->ip_src, th->th_sport, 0, NULL); 1152 if (inp != NULL) { 1153 INP_LOCK(inp); 1154 if (inp->inp_socket != NULL) { 1155 icmp_tcp_seq = htonl(th->th_seq); 1156 tp = intotcpcb(inp); 1157 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1158 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1159 if (cmd == PRC_MSGSIZE) { 1160 /* 1161 * MTU discovery: 1162 * If we got a needfrag set the MTU 1163 * in the route to the suggested new 1164 * value (if given) and then notify. 1165 */ 1166 bzero(&inc, sizeof(inc)); 1167 inc.inc_flags = 0; /* IPv4 */ 1168 inc.inc_faddr = faddr; 1169 1170 mtu = ntohs(icp->icmp_nextmtu); 1171 /* 1172 * If no alternative MTU was 1173 * proposed, try the next smaller 1174 * one. ip->ip_len has already 1175 * been swapped in icmp_input(). 1176 */ 1177 if (!mtu) 1178 mtu = ip_next_mtu(ip->ip_len, 1179 1); 1180 if (mtu < max(296, (tcp_minmss) 1181 + sizeof(struct tcpiphdr))) 1182 mtu = 0; 1183 if (!mtu) 1184 mtu = tcp_mssdflt 1185 + sizeof(struct tcpiphdr); 1186 /* 1187 * Only cache the the MTU if it 1188 * is smaller than the interface 1189 * or route MTU. tcp_mtudisc() 1190 * will do right thing by itself. 1191 */ 1192 if (mtu <= tcp_maxmtu(&inc)) 1193 tcp_hc_updatemtu(&inc, mtu); 1194 } 1195 1196 inp = (*notify)(inp, inetctlerrmap[cmd]); 1197 } 1198 } 1199 if (inp != NULL) 1200 INP_UNLOCK(inp); 1201 } else { 1202 inc.inc_fport = th->th_dport; 1203 inc.inc_lport = th->th_sport; 1204 inc.inc_faddr = faddr; 1205 inc.inc_laddr = ip->ip_src; 1206 #ifdef INET6 1207 inc.inc_isipv6 = 0; 1208 #endif 1209 syncache_unreach(&inc, th); 1210 } 1211 INP_INFO_WUNLOCK(&tcbinfo); 1212 } else 1213 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1214 } 1215 1216 #ifdef INET6 1217 void 1218 tcp6_ctlinput(cmd, sa, d) 1219 int cmd; 1220 struct sockaddr *sa; 1221 void *d; 1222 { 1223 struct tcphdr th; 1224 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1225 struct ip6_hdr *ip6; 1226 struct mbuf *m; 1227 struct ip6ctlparam *ip6cp = NULL; 1228 const struct sockaddr_in6 *sa6_src = NULL; 1229 int off; 1230 struct tcp_portonly { 1231 u_int16_t th_sport; 1232 u_int16_t th_dport; 1233 } *thp; 1234 1235 if (sa->sa_family != AF_INET6 || 1236 sa->sa_len != sizeof(struct sockaddr_in6)) 1237 return; 1238 1239 if (cmd == PRC_MSGSIZE) 1240 notify = tcp_mtudisc; 1241 else if (!PRC_IS_REDIRECT(cmd) && 1242 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1243 return; 1244 /* Source quench is depreciated. */ 1245 else if (cmd == PRC_QUENCH) 1246 return; 1247 1248 /* if the parameter is from icmp6, decode it. */ 1249 if (d != NULL) { 1250 ip6cp = (struct ip6ctlparam *)d; 1251 m = ip6cp->ip6c_m; 1252 ip6 = ip6cp->ip6c_ip6; 1253 off = ip6cp->ip6c_off; 1254 sa6_src = ip6cp->ip6c_src; 1255 } else { 1256 m = NULL; 1257 ip6 = NULL; 1258 off = 0; /* fool gcc */ 1259 sa6_src = &sa6_any; 1260 } 1261 1262 if (ip6 != NULL) { 1263 struct in_conninfo inc; 1264 /* 1265 * XXX: We assume that when IPV6 is non NULL, 1266 * M and OFF are valid. 1267 */ 1268 1269 /* check if we can safely examine src and dst ports */ 1270 if (m->m_pkthdr.len < off + sizeof(*thp)) 1271 return; 1272 1273 bzero(&th, sizeof(th)); 1274 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1275 1276 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1277 (struct sockaddr *)ip6cp->ip6c_src, 1278 th.th_sport, cmd, NULL, notify); 1279 1280 inc.inc_fport = th.th_dport; 1281 inc.inc_lport = th.th_sport; 1282 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1283 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1284 inc.inc_isipv6 = 1; 1285 INP_INFO_WLOCK(&tcbinfo); 1286 syncache_unreach(&inc, &th); 1287 INP_INFO_WUNLOCK(&tcbinfo); 1288 } else 1289 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1290 0, cmd, NULL, notify); 1291 } 1292 #endif /* INET6 */ 1293 1294 1295 /* 1296 * Following is where TCP initial sequence number generation occurs. 1297 * 1298 * There are two places where we must use initial sequence numbers: 1299 * 1. In SYN-ACK packets. 1300 * 2. In SYN packets. 1301 * 1302 * All ISNs for SYN-ACK packets are generated by the syncache. See 1303 * tcp_syncache.c for details. 1304 * 1305 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1306 * depends on this property. In addition, these ISNs should be 1307 * unguessable so as to prevent connection hijacking. To satisfy 1308 * the requirements of this situation, the algorithm outlined in 1309 * RFC 1948 is used, with only small modifications. 1310 * 1311 * Implementation details: 1312 * 1313 * Time is based off the system timer, and is corrected so that it 1314 * increases by one megabyte per second. This allows for proper 1315 * recycling on high speed LANs while still leaving over an hour 1316 * before rollover. 1317 * 1318 * As reading the *exact* system time is too expensive to be done 1319 * whenever setting up a TCP connection, we increment the time 1320 * offset in two ways. First, a small random positive increment 1321 * is added to isn_offset for each connection that is set up. 1322 * Second, the function tcp_isn_tick fires once per clock tick 1323 * and increments isn_offset as necessary so that sequence numbers 1324 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1325 * random positive increments serve only to ensure that the same 1326 * exact sequence number is never sent out twice (as could otherwise 1327 * happen when a port is recycled in less than the system tick 1328 * interval.) 1329 * 1330 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1331 * between seeding of isn_secret. This is normally set to zero, 1332 * as reseeding should not be necessary. 1333 * 1334 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1335 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1336 * general, this means holding an exclusive (write) lock. 1337 */ 1338 1339 #define ISN_BYTES_PER_SECOND 1048576 1340 #define ISN_STATIC_INCREMENT 4096 1341 #define ISN_RANDOM_INCREMENT (4096 - 1) 1342 1343 static u_char isn_secret[32]; 1344 static int isn_last_reseed; 1345 static u_int32_t isn_offset, isn_offset_old; 1346 static MD5_CTX isn_ctx; 1347 1348 tcp_seq 1349 tcp_new_isn(tp) 1350 struct tcpcb *tp; 1351 { 1352 u_int32_t md5_buffer[4]; 1353 tcp_seq new_isn; 1354 1355 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1356 INP_LOCK_ASSERT(tp->t_inpcb); 1357 1358 /* Seed if this is the first use, reseed if requested. */ 1359 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1360 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1361 < (u_int)ticks))) { 1362 read_random(&isn_secret, sizeof(isn_secret)); 1363 isn_last_reseed = ticks; 1364 } 1365 1366 /* Compute the md5 hash and return the ISN. */ 1367 MD5Init(&isn_ctx); 1368 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1369 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1370 #ifdef INET6 1371 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1372 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1373 sizeof(struct in6_addr)); 1374 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1375 sizeof(struct in6_addr)); 1376 } else 1377 #endif 1378 { 1379 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1380 sizeof(struct in_addr)); 1381 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1382 sizeof(struct in_addr)); 1383 } 1384 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1385 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1386 new_isn = (tcp_seq) md5_buffer[0]; 1387 isn_offset += ISN_STATIC_INCREMENT + 1388 (arc4random() & ISN_RANDOM_INCREMENT); 1389 new_isn += isn_offset; 1390 return (new_isn); 1391 } 1392 1393 /* 1394 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1395 * to keep time flowing at a relatively constant rate. If the random 1396 * increments have already pushed us past the projected offset, do nothing. 1397 */ 1398 static void 1399 tcp_isn_tick(xtp) 1400 void *xtp; 1401 { 1402 u_int32_t projected_offset; 1403 1404 INP_INFO_WLOCK(&tcbinfo); 1405 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1406 1407 if (projected_offset > isn_offset) 1408 isn_offset = projected_offset; 1409 1410 isn_offset_old = isn_offset; 1411 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1412 INP_INFO_WUNLOCK(&tcbinfo); 1413 } 1414 1415 /* 1416 * When a specific ICMP unreachable message is received and the 1417 * connection state is SYN-SENT, drop the connection. This behavior 1418 * is controlled by the icmp_may_rst sysctl. 1419 */ 1420 struct inpcb * 1421 tcp_drop_syn_sent(inp, errno) 1422 struct inpcb *inp; 1423 int errno; 1424 { 1425 struct tcpcb *tp = intotcpcb(inp); 1426 1427 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1428 INP_LOCK_ASSERT(inp); 1429 1430 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1431 tcp_drop(tp, errno); 1432 return (NULL); 1433 } 1434 return (inp); 1435 } 1436 1437 /* 1438 * When `need fragmentation' ICMP is received, update our idea of the MSS 1439 * based on the new value in the route. Also nudge TCP to send something, 1440 * since we know the packet we just sent was dropped. 1441 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1442 */ 1443 struct inpcb * 1444 tcp_mtudisc(inp, errno) 1445 struct inpcb *inp; 1446 int errno; 1447 { 1448 struct tcpcb *tp = intotcpcb(inp); 1449 struct socket *so = inp->inp_socket; 1450 u_int maxmtu; 1451 u_int romtu; 1452 int mss; 1453 #ifdef INET6 1454 int isipv6; 1455 #endif /* INET6 */ 1456 1457 INP_LOCK_ASSERT(inp); 1458 if (tp != NULL) { 1459 #ifdef INET6 1460 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1461 #endif 1462 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1463 romtu = 1464 #ifdef INET6 1465 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1466 #endif /* INET6 */ 1467 tcp_maxmtu(&inp->inp_inc); 1468 if (!maxmtu) 1469 maxmtu = romtu; 1470 else 1471 maxmtu = min(maxmtu, romtu); 1472 if (!maxmtu) { 1473 tp->t_maxopd = tp->t_maxseg = 1474 #ifdef INET6 1475 isipv6 ? tcp_v6mssdflt : 1476 #endif /* INET6 */ 1477 tcp_mssdflt; 1478 return (inp); 1479 } 1480 mss = maxmtu - 1481 #ifdef INET6 1482 (isipv6 ? 1483 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1484 #endif /* INET6 */ 1485 sizeof(struct tcpiphdr) 1486 #ifdef INET6 1487 ) 1488 #endif /* INET6 */ 1489 ; 1490 1491 /* 1492 * XXX - The above conditional probably violates the TCP 1493 * spec. The problem is that, since we don't know the 1494 * other end's MSS, we are supposed to use a conservative 1495 * default. But, if we do that, then MTU discovery will 1496 * never actually take place, because the conservative 1497 * default is much less than the MTUs typically seen 1498 * on the Internet today. For the moment, we'll sweep 1499 * this under the carpet. 1500 * 1501 * The conservative default might not actually be a problem 1502 * if the only case this occurs is when sending an initial 1503 * SYN with options and data to a host we've never talked 1504 * to before. Then, they will reply with an MSS value which 1505 * will get recorded and the new parameters should get 1506 * recomputed. For Further Study. 1507 */ 1508 if (tp->t_maxopd <= mss) 1509 return (inp); 1510 tp->t_maxopd = mss; 1511 1512 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1513 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1514 mss -= TCPOLEN_TSTAMP_APPA; 1515 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1516 if (mss > MCLBYTES) 1517 mss &= ~(MCLBYTES-1); 1518 #else 1519 if (mss > MCLBYTES) 1520 mss = mss / MCLBYTES * MCLBYTES; 1521 #endif 1522 if (so->so_snd.sb_hiwat < mss) 1523 mss = so->so_snd.sb_hiwat; 1524 1525 tp->t_maxseg = mss; 1526 1527 tcpstat.tcps_mturesent++; 1528 tp->t_rtttime = 0; 1529 tp->snd_nxt = tp->snd_una; 1530 tcp_output(tp); 1531 } 1532 return (inp); 1533 } 1534 1535 /* 1536 * Look-up the routing entry to the peer of this inpcb. If no route 1537 * is found and it cannot be allocated, then return NULL. This routine 1538 * is called by TCP routines that access the rmx structure and by tcp_mss 1539 * to get the interface MTU. 1540 */ 1541 u_long 1542 tcp_maxmtu(inc) 1543 struct in_conninfo *inc; 1544 { 1545 struct route sro; 1546 struct sockaddr_in *dst; 1547 struct ifnet *ifp; 1548 u_long maxmtu = 0; 1549 1550 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1551 1552 bzero(&sro, sizeof(sro)); 1553 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1554 dst = (struct sockaddr_in *)&sro.ro_dst; 1555 dst->sin_family = AF_INET; 1556 dst->sin_len = sizeof(*dst); 1557 dst->sin_addr = inc->inc_faddr; 1558 rtalloc_ign(&sro, RTF_CLONING); 1559 } 1560 if (sro.ro_rt != NULL) { 1561 ifp = sro.ro_rt->rt_ifp; 1562 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1563 maxmtu = ifp->if_mtu; 1564 else 1565 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1566 RTFREE(sro.ro_rt); 1567 } 1568 return (maxmtu); 1569 } 1570 1571 #ifdef INET6 1572 u_long 1573 tcp_maxmtu6(inc) 1574 struct in_conninfo *inc; 1575 { 1576 struct route_in6 sro6; 1577 struct ifnet *ifp; 1578 u_long maxmtu = 0; 1579 1580 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1581 1582 bzero(&sro6, sizeof(sro6)); 1583 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1584 sro6.ro_dst.sin6_family = AF_INET6; 1585 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1586 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1587 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1588 } 1589 if (sro6.ro_rt != NULL) { 1590 ifp = sro6.ro_rt->rt_ifp; 1591 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1592 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1593 else 1594 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1595 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1596 RTFREE(sro6.ro_rt); 1597 } 1598 1599 return (maxmtu); 1600 } 1601 #endif /* INET6 */ 1602 1603 #ifdef IPSEC 1604 /* compute ESP/AH header size for TCP, including outer IP header. */ 1605 size_t 1606 ipsec_hdrsiz_tcp(tp) 1607 struct tcpcb *tp; 1608 { 1609 struct inpcb *inp; 1610 struct mbuf *m; 1611 size_t hdrsiz; 1612 struct ip *ip; 1613 #ifdef INET6 1614 struct ip6_hdr *ip6; 1615 #endif 1616 struct tcphdr *th; 1617 1618 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1619 return (0); 1620 MGETHDR(m, M_DONTWAIT, MT_DATA); 1621 if (!m) 1622 return (0); 1623 1624 #ifdef INET6 1625 if ((inp->inp_vflag & INP_IPV6) != 0) { 1626 ip6 = mtod(m, struct ip6_hdr *); 1627 th = (struct tcphdr *)(ip6 + 1); 1628 m->m_pkthdr.len = m->m_len = 1629 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1630 tcpip_fillheaders(inp, ip6, th); 1631 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1632 } else 1633 #endif /* INET6 */ 1634 { 1635 ip = mtod(m, struct ip *); 1636 th = (struct tcphdr *)(ip + 1); 1637 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1638 tcpip_fillheaders(inp, ip, th); 1639 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1640 } 1641 1642 m_free(m); 1643 return (hdrsiz); 1644 } 1645 #endif /*IPSEC*/ 1646 1647 /* 1648 * Move a TCP connection into TIME_WAIT state. 1649 * tcbinfo is locked. 1650 * inp is locked, and is unlocked before returning. 1651 */ 1652 void 1653 tcp_twstart(tp) 1654 struct tcpcb *tp; 1655 { 1656 struct tcptw *tw; 1657 struct inpcb *inp; 1658 int tw_time, acknow; 1659 struct socket *so; 1660 1661 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1662 INP_LOCK_ASSERT(tp->t_inpcb); 1663 1664 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1665 if (tw == NULL) { 1666 tw = tcp_timer_2msl_tw(1); 1667 if (tw == NULL) { 1668 tcp_close(tp); 1669 return; 1670 } 1671 } 1672 inp = tp->t_inpcb; 1673 tw->tw_inpcb = inp; 1674 1675 /* 1676 * Recover last window size sent. 1677 */ 1678 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1679 1680 /* 1681 * Set t_recent if timestamps are used on the connection. 1682 */ 1683 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1684 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1685 tw->t_recent = tp->ts_recent; 1686 else 1687 tw->t_recent = 0; 1688 1689 tw->snd_nxt = tp->snd_nxt; 1690 tw->rcv_nxt = tp->rcv_nxt; 1691 tw->iss = tp->iss; 1692 tw->irs = tp->irs; 1693 tw->t_starttime = tp->t_starttime; 1694 tw->tw_time = 0; 1695 1696 /* XXX 1697 * If this code will 1698 * be used for fin-wait-2 state also, then we may need 1699 * a ts_recent from the last segment. 1700 */ 1701 tw_time = 2 * tcp_msl; 1702 acknow = tp->t_flags & TF_ACKNOW; 1703 tcp_discardcb(tp); 1704 so = inp->inp_socket; 1705 ACCEPT_LOCK(); 1706 SOCK_LOCK(so); 1707 so->so_pcb = NULL; 1708 tw->tw_cred = crhold(so->so_cred); 1709 tw->tw_so_options = so->so_options; 1710 sotryfree(so); 1711 inp->inp_socket = NULL; 1712 if (acknow) 1713 tcp_twrespond(tw, TH_ACK); 1714 inp->inp_ppcb = (caddr_t)tw; 1715 inp->inp_vflag |= INP_TIMEWAIT; 1716 tcp_timer_2msl_reset(tw, tw_time); 1717 INP_UNLOCK(inp); 1718 } 1719 1720 /* 1721 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1722 * the actual rate is slightly higher due to the addition of 1723 * random positive increments. 1724 * 1725 * Most other new OSes use semi-randomized ISN values, so we 1726 * do not need to worry about them. 1727 */ 1728 #define MS_ISN_BYTES_PER_SECOND 250000 1729 1730 /* 1731 * Determine if the ISN we will generate has advanced beyond the last 1732 * sequence number used by the previous connection. If so, indicate 1733 * that it is safe to recycle this tw socket by returning 1. 1734 * 1735 * XXXRW: This function should assert the inpcb lock as it does multiple 1736 * non-atomic reads from the tcptw, but is currently called without it from 1737 * in_pcb.c:in_pcblookup_local(). 1738 */ 1739 int 1740 tcp_twrecycleable(struct tcptw *tw) 1741 { 1742 tcp_seq new_iss = tw->iss; 1743 tcp_seq new_irs = tw->irs; 1744 1745 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1746 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1747 1748 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1749 return (1); 1750 else 1751 return (0); 1752 } 1753 1754 struct tcptw * 1755 tcp_twclose(struct tcptw *tw, int reuse) 1756 { 1757 struct inpcb *inp; 1758 1759 inp = tw->tw_inpcb; 1760 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1761 INP_LOCK_ASSERT(inp); 1762 1763 tw->tw_inpcb = NULL; 1764 tcp_timer_2msl_stop(tw); 1765 inp->inp_ppcb = NULL; 1766 #ifdef INET6 1767 if (inp->inp_vflag & INP_IPV6PROTO) 1768 in6_pcbdetach(inp); 1769 else 1770 #endif 1771 in_pcbdetach(inp); 1772 tcpstat.tcps_closed++; 1773 crfree(tw->tw_cred); 1774 tw->tw_cred = NULL; 1775 if (reuse) 1776 return (tw); 1777 uma_zfree(tcptw_zone, tw); 1778 return (NULL); 1779 } 1780 1781 int 1782 tcp_twrespond(struct tcptw *tw, int flags) 1783 { 1784 struct inpcb *inp = tw->tw_inpcb; 1785 struct tcphdr *th; 1786 struct mbuf *m; 1787 struct ip *ip = NULL; 1788 u_int8_t *optp; 1789 u_int hdrlen, optlen; 1790 int error; 1791 #ifdef INET6 1792 struct ip6_hdr *ip6 = NULL; 1793 int isipv6 = inp->inp_inc.inc_isipv6; 1794 #endif 1795 1796 INP_LOCK_ASSERT(inp); 1797 1798 m = m_gethdr(M_DONTWAIT, MT_HEADER); 1799 if (m == NULL) 1800 return (ENOBUFS); 1801 m->m_data += max_linkhdr; 1802 1803 #ifdef MAC 1804 mac_create_mbuf_from_inpcb(inp, m); 1805 #endif 1806 1807 #ifdef INET6 1808 if (isipv6) { 1809 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1810 ip6 = mtod(m, struct ip6_hdr *); 1811 th = (struct tcphdr *)(ip6 + 1); 1812 tcpip_fillheaders(inp, ip6, th); 1813 } else 1814 #endif 1815 { 1816 hdrlen = sizeof(struct tcpiphdr); 1817 ip = mtod(m, struct ip *); 1818 th = (struct tcphdr *)(ip + 1); 1819 tcpip_fillheaders(inp, ip, th); 1820 } 1821 optp = (u_int8_t *)(th + 1); 1822 1823 /* 1824 * Send a timestamp and echo-reply if both our side and our peer 1825 * have sent timestamps in our SYN's and this is not a RST. 1826 */ 1827 if (tw->t_recent && flags == TH_ACK) { 1828 u_int32_t *lp = (u_int32_t *)optp; 1829 1830 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1831 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1832 *lp++ = htonl(ticks); 1833 *lp = htonl(tw->t_recent); 1834 optp += TCPOLEN_TSTAMP_APPA; 1835 } 1836 1837 optlen = optp - (u_int8_t *)(th + 1); 1838 1839 m->m_len = hdrlen + optlen; 1840 m->m_pkthdr.len = m->m_len; 1841 1842 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1843 1844 th->th_seq = htonl(tw->snd_nxt); 1845 th->th_ack = htonl(tw->rcv_nxt); 1846 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1847 th->th_flags = flags; 1848 th->th_win = htons(tw->last_win); 1849 1850 #ifdef INET6 1851 if (isipv6) { 1852 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1853 sizeof(struct tcphdr) + optlen); 1854 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1855 error = ip6_output(m, inp->in6p_outputopts, NULL, 1856 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1857 } else 1858 #endif 1859 { 1860 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1861 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1862 m->m_pkthdr.csum_flags = CSUM_TCP; 1863 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1864 ip->ip_len = m->m_pkthdr.len; 1865 if (path_mtu_discovery) 1866 ip->ip_off |= IP_DF; 1867 error = ip_output(m, inp->inp_options, NULL, 1868 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1869 NULL, inp); 1870 } 1871 if (flags & TH_ACK) 1872 tcpstat.tcps_sndacks++; 1873 else 1874 tcpstat.tcps_sndctrl++; 1875 tcpstat.tcps_sndtotal++; 1876 return (error); 1877 } 1878 1879 /* 1880 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1881 * 1882 * This code attempts to calculate the bandwidth-delay product as a 1883 * means of determining the optimal window size to maximize bandwidth, 1884 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1885 * routers. This code also does a fairly good job keeping RTTs in check 1886 * across slow links like modems. We implement an algorithm which is very 1887 * similar (but not meant to be) TCP/Vegas. The code operates on the 1888 * transmitter side of a TCP connection and so only effects the transmit 1889 * side of the connection. 1890 * 1891 * BACKGROUND: TCP makes no provision for the management of buffer space 1892 * at the end points or at the intermediate routers and switches. A TCP 1893 * stream, whether using NewReno or not, will eventually buffer as 1894 * many packets as it is able and the only reason this typically works is 1895 * due to the fairly small default buffers made available for a connection 1896 * (typicaly 16K or 32K). As machines use larger windows and/or window 1897 * scaling it is now fairly easy for even a single TCP connection to blow-out 1898 * all available buffer space not only on the local interface, but on 1899 * intermediate routers and switches as well. NewReno makes a misguided 1900 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1901 * then backing off, then steadily increasing the window again until another 1902 * failure occurs, ad-infinitum. This results in terrible oscillation that 1903 * is only made worse as network loads increase and the idea of intentionally 1904 * blowing out network buffers is, frankly, a terrible way to manage network 1905 * resources. 1906 * 1907 * It is far better to limit the transmit window prior to the failure 1908 * condition being achieved. There are two general ways to do this: First 1909 * you can 'scan' through different transmit window sizes and locate the 1910 * point where the RTT stops increasing, indicating that you have filled the 1911 * pipe, then scan backwards until you note that RTT stops decreasing, then 1912 * repeat ad-infinitum. This method works in principle but has severe 1913 * implementation issues due to RTT variances, timer granularity, and 1914 * instability in the algorithm which can lead to many false positives and 1915 * create oscillations as well as interact badly with other TCP streams 1916 * implementing the same algorithm. 1917 * 1918 * The second method is to limit the window to the bandwidth delay product 1919 * of the link. This is the method we implement. RTT variances and our 1920 * own manipulation of the congestion window, bwnd, can potentially 1921 * destabilize the algorithm. For this reason we have to stabilize the 1922 * elements used to calculate the window. We do this by using the minimum 1923 * observed RTT, the long term average of the observed bandwidth, and 1924 * by adding two segments worth of slop. It isn't perfect but it is able 1925 * to react to changing conditions and gives us a very stable basis on 1926 * which to extend the algorithm. 1927 */ 1928 void 1929 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1930 { 1931 u_long bw; 1932 u_long bwnd; 1933 int save_ticks; 1934 1935 INP_LOCK_ASSERT(tp->t_inpcb); 1936 1937 /* 1938 * If inflight_enable is disabled in the middle of a tcp connection, 1939 * make sure snd_bwnd is effectively disabled. 1940 */ 1941 if (tcp_inflight_enable == 0) { 1942 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1943 tp->snd_bandwidth = 0; 1944 return; 1945 } 1946 1947 /* 1948 * Figure out the bandwidth. Due to the tick granularity this 1949 * is a very rough number and it MUST be averaged over a fairly 1950 * long period of time. XXX we need to take into account a link 1951 * that is not using all available bandwidth, but for now our 1952 * slop will ramp us up if this case occurs and the bandwidth later 1953 * increases. 1954 * 1955 * Note: if ticks rollover 'bw' may wind up negative. We must 1956 * effectively reset t_bw_rtttime for this case. 1957 */ 1958 save_ticks = ticks; 1959 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1960 return; 1961 1962 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1963 (save_ticks - tp->t_bw_rtttime); 1964 tp->t_bw_rtttime = save_ticks; 1965 tp->t_bw_rtseq = ack_seq; 1966 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1967 return; 1968 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1969 1970 tp->snd_bandwidth = bw; 1971 1972 /* 1973 * Calculate the semi-static bandwidth delay product, plus two maximal 1974 * segments. The additional slop puts us squarely in the sweet 1975 * spot and also handles the bandwidth run-up case and stabilization. 1976 * Without the slop we could be locking ourselves into a lower 1977 * bandwidth. 1978 * 1979 * Situations Handled: 1980 * (1) Prevents over-queueing of packets on LANs, especially on 1981 * high speed LANs, allowing larger TCP buffers to be 1982 * specified, and also does a good job preventing 1983 * over-queueing of packets over choke points like modems 1984 * (at least for the transmit side). 1985 * 1986 * (2) Is able to handle changing network loads (bandwidth 1987 * drops so bwnd drops, bandwidth increases so bwnd 1988 * increases). 1989 * 1990 * (3) Theoretically should stabilize in the face of multiple 1991 * connections implementing the same algorithm (this may need 1992 * a little work). 1993 * 1994 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1995 * be adjusted with a sysctl but typically only needs to be 1996 * on very slow connections. A value no smaller then 5 1997 * should be used, but only reduce this default if you have 1998 * no other choice. 1999 */ 2000 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2001 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2002 #undef USERTT 2003 2004 if (tcp_inflight_debug > 0) { 2005 static int ltime; 2006 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2007 ltime = ticks; 2008 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2009 tp, 2010 bw, 2011 tp->t_rttbest, 2012 tp->t_srtt, 2013 bwnd 2014 ); 2015 } 2016 } 2017 if ((long)bwnd < tcp_inflight_min) 2018 bwnd = tcp_inflight_min; 2019 if (bwnd > tcp_inflight_max) 2020 bwnd = tcp_inflight_max; 2021 if ((long)bwnd < tp->t_maxseg * 2) 2022 bwnd = tp->t_maxseg * 2; 2023 tp->snd_bwnd = bwnd; 2024 } 2025 2026 #ifdef TCP_SIGNATURE 2027 /* 2028 * Callback function invoked by m_apply() to digest TCP segment data 2029 * contained within an mbuf chain. 2030 */ 2031 static int 2032 tcp_signature_apply(void *fstate, void *data, u_int len) 2033 { 2034 2035 MD5Update(fstate, (u_char *)data, len); 2036 return (0); 2037 } 2038 2039 /* 2040 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2041 * 2042 * Parameters: 2043 * m pointer to head of mbuf chain 2044 * off0 offset to TCP header within the mbuf chain 2045 * len length of TCP segment data, excluding options 2046 * optlen length of TCP segment options 2047 * buf pointer to storage for computed MD5 digest 2048 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2049 * 2050 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2051 * When called from tcp_input(), we can be sure that th_sum has been 2052 * zeroed out and verified already. 2053 * 2054 * This function is for IPv4 use only. Calling this function with an 2055 * IPv6 packet in the mbuf chain will yield undefined results. 2056 * 2057 * Return 0 if successful, otherwise return -1. 2058 * 2059 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2060 * search with the destination IP address, and a 'magic SPI' to be 2061 * determined by the application. This is hardcoded elsewhere to 1179 2062 * right now. Another branch of this code exists which uses the SPD to 2063 * specify per-application flows but it is unstable. 2064 */ 2065 int 2066 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2067 u_char *buf, u_int direction) 2068 { 2069 union sockaddr_union dst; 2070 struct ippseudo ippseudo; 2071 MD5_CTX ctx; 2072 int doff; 2073 struct ip *ip; 2074 struct ipovly *ipovly; 2075 struct secasvar *sav; 2076 struct tcphdr *th; 2077 u_short savecsum; 2078 2079 KASSERT(m != NULL, ("NULL mbuf chain")); 2080 KASSERT(buf != NULL, ("NULL signature pointer")); 2081 2082 /* Extract the destination from the IP header in the mbuf. */ 2083 ip = mtod(m, struct ip *); 2084 bzero(&dst, sizeof(union sockaddr_union)); 2085 dst.sa.sa_len = sizeof(struct sockaddr_in); 2086 dst.sa.sa_family = AF_INET; 2087 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2088 ip->ip_src : ip->ip_dst; 2089 2090 /* Look up an SADB entry which matches the address of the peer. */ 2091 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2092 if (sav == NULL) { 2093 printf("%s: SADB lookup failed for %s\n", __func__, 2094 inet_ntoa(dst.sin.sin_addr)); 2095 return (EINVAL); 2096 } 2097 2098 MD5Init(&ctx); 2099 ipovly = (struct ipovly *)ip; 2100 th = (struct tcphdr *)((u_char *)ip + off0); 2101 doff = off0 + sizeof(struct tcphdr) + optlen; 2102 2103 /* 2104 * Step 1: Update MD5 hash with IP pseudo-header. 2105 * 2106 * XXX The ippseudo header MUST be digested in network byte order, 2107 * or else we'll fail the regression test. Assume all fields we've 2108 * been doing arithmetic on have been in host byte order. 2109 * XXX One cannot depend on ipovly->ih_len here. When called from 2110 * tcp_output(), the underlying ip_len member has not yet been set. 2111 */ 2112 ippseudo.ippseudo_src = ipovly->ih_src; 2113 ippseudo.ippseudo_dst = ipovly->ih_dst; 2114 ippseudo.ippseudo_pad = 0; 2115 ippseudo.ippseudo_p = IPPROTO_TCP; 2116 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2117 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2118 2119 /* 2120 * Step 2: Update MD5 hash with TCP header, excluding options. 2121 * The TCP checksum must be set to zero. 2122 */ 2123 savecsum = th->th_sum; 2124 th->th_sum = 0; 2125 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2126 th->th_sum = savecsum; 2127 2128 /* 2129 * Step 3: Update MD5 hash with TCP segment data. 2130 * Use m_apply() to avoid an early m_pullup(). 2131 */ 2132 if (len > 0) 2133 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2134 2135 /* 2136 * Step 4: Update MD5 hash with shared secret. 2137 */ 2138 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2139 MD5Final(buf, &ctx); 2140 2141 key_sa_recordxfer(sav, m); 2142 KEY_FREESAV(&sav); 2143 return (0); 2144 } 2145 #endif /* TCP_SIGNATURE */ 2146 2147 static int 2148 sysctl_drop(SYSCTL_HANDLER_ARGS) 2149 { 2150 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2151 struct sockaddr_storage addrs[2]; 2152 struct inpcb *inp; 2153 struct tcpcb *tp; 2154 struct tcptw *tw; 2155 struct sockaddr_in *fin, *lin; 2156 #ifdef INET6 2157 struct sockaddr_in6 *fin6, *lin6; 2158 struct in6_addr f6, l6; 2159 #endif 2160 int error; 2161 2162 inp = NULL; 2163 fin = lin = NULL; 2164 #ifdef INET6 2165 fin6 = lin6 = NULL; 2166 #endif 2167 error = 0; 2168 2169 if (req->oldptr != NULL || req->oldlen != 0) 2170 return (EINVAL); 2171 if (req->newptr == NULL) 2172 return (EPERM); 2173 if (req->newlen < sizeof(addrs)) 2174 return (ENOMEM); 2175 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2176 if (error) 2177 return (error); 2178 2179 switch (addrs[0].ss_family) { 2180 #ifdef INET6 2181 case AF_INET6: 2182 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2183 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2184 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2185 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2186 return (EINVAL); 2187 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2188 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2189 return (EINVAL); 2190 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2191 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2192 fin = (struct sockaddr_in *)&addrs[0]; 2193 lin = (struct sockaddr_in *)&addrs[1]; 2194 break; 2195 } 2196 error = in6_embedscope(&f6, fin6, NULL, NULL); 2197 if (error) 2198 return (EINVAL); 2199 error = in6_embedscope(&l6, lin6, NULL, NULL); 2200 if (error) 2201 return (EINVAL); 2202 break; 2203 #endif 2204 case AF_INET: 2205 fin = (struct sockaddr_in *)&addrs[0]; 2206 lin = (struct sockaddr_in *)&addrs[1]; 2207 if (fin->sin_len != sizeof(struct sockaddr_in) || 2208 lin->sin_len != sizeof(struct sockaddr_in)) 2209 return (EINVAL); 2210 break; 2211 default: 2212 return (EINVAL); 2213 } 2214 INP_INFO_WLOCK(&tcbinfo); 2215 switch (addrs[0].ss_family) { 2216 #ifdef INET6 2217 case AF_INET6: 2218 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2219 &l6, lin6->sin6_port, 0, NULL); 2220 break; 2221 #endif 2222 case AF_INET: 2223 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2224 lin->sin_addr, lin->sin_port, 0, NULL); 2225 break; 2226 } 2227 if (inp != NULL) { 2228 INP_LOCK(inp); 2229 if ((tw = intotw(inp)) && 2230 (inp->inp_vflag & INP_TIMEWAIT) != 0) { 2231 (void) tcp_twclose(tw, 0); 2232 } else if ((tp = intotcpcb(inp)) && 2233 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2234 tp = tcp_drop(tp, ECONNABORTED); 2235 if (tp != NULL) 2236 INP_UNLOCK(inp); 2237 } else 2238 INP_UNLOCK(inp); 2239 } else 2240 error = ESRCH; 2241 INP_INFO_WUNLOCK(&tcbinfo); 2242 return (error); 2243 } 2244 2245 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2246 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2247 0, sysctl_drop, "", "Drop TCP connection");
Cache object: 1d7433c45b2cb528c2bd615f1b26b979
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