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/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_HEADER); 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 if (tp->sack_enable) 609 TAILQ_INIT(&tp->snd_holes); 610 tp->t_inpcb = inp; /* XXX */ 611 /* 612 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 613 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 614 * reasonable initial retransmit time. 615 */ 616 tp->t_srtt = TCPTV_SRTTBASE; 617 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 618 tp->t_rttmin = tcp_rexmit_min; 619 tp->t_rxtcur = TCPTV_RTOBASE; 620 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 621 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 622 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 623 tp->t_rcvtime = ticks; 624 tp->t_bw_rtttime = ticks; 625 /* 626 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 627 * because the socket may be bound to an IPv6 wildcard address, 628 * which may match an IPv4-mapped IPv6 address. 629 */ 630 inp->inp_ip_ttl = ip_defttl; 631 inp->inp_ppcb = (caddr_t)tp; 632 return (tp); /* XXX */ 633 } 634 635 /* 636 * Drop a TCP connection, reporting 637 * the specified error. If connection is synchronized, 638 * then send a RST to peer. 639 */ 640 struct tcpcb * 641 tcp_drop(tp, errno) 642 register struct tcpcb *tp; 643 int errno; 644 { 645 struct socket *so = tp->t_inpcb->inp_socket; 646 647 INP_LOCK_ASSERT(tp->t_inpcb); 648 if (TCPS_HAVERCVDSYN(tp->t_state)) { 649 tp->t_state = TCPS_CLOSED; 650 (void) tcp_output(tp); 651 tcpstat.tcps_drops++; 652 } else 653 tcpstat.tcps_conndrops++; 654 if (errno == ETIMEDOUT && tp->t_softerror) 655 errno = tp->t_softerror; 656 so->so_error = errno; 657 return (tcp_close(tp)); 658 } 659 660 static void 661 tcp_discardcb(tp) 662 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 INP_LOCK_ASSERT(inp); 672 673 /* 674 * Make sure that all of our timers are stopped before we 675 * delete the PCB. 676 */ 677 callout_stop(tp->tt_rexmt); 678 callout_stop(tp->tt_persist); 679 callout_stop(tp->tt_keep); 680 callout_stop(tp->tt_2msl); 681 callout_stop(tp->tt_delack); 682 683 /* 684 * If we got enough samples through the srtt filter, 685 * save the rtt and rttvar in the routing entry. 686 * 'Enough' is arbitrarily defined as 4 rtt samples. 687 * 4 samples is enough for the srtt filter to converge 688 * to within enough % of the correct value; fewer samples 689 * and we could save a bogus rtt. The danger is not high 690 * as tcp quickly recovers from everything. 691 * XXX: Works very well but needs some more statistics! 692 */ 693 if (tp->t_rttupdated >= 4) { 694 struct hc_metrics_lite metrics; 695 u_long ssthresh; 696 697 bzero(&metrics, sizeof(metrics)); 698 /* 699 * Update the ssthresh always when the conditions below 700 * are satisfied. This gives us better new start value 701 * for the congestion avoidance for new connections. 702 * ssthresh is only set if packet loss occured on a session. 703 */ 704 ssthresh = tp->snd_ssthresh; 705 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 706 /* 707 * convert the limit from user data bytes to 708 * packets then to packet data bytes. 709 */ 710 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 711 if (ssthresh < 2) 712 ssthresh = 2; 713 ssthresh *= (u_long)(tp->t_maxseg + 714 #ifdef INET6 715 (isipv6 ? sizeof (struct ip6_hdr) + 716 sizeof (struct tcphdr) : 717 #endif 718 sizeof (struct tcpiphdr) 719 #ifdef INET6 720 ) 721 #endif 722 ); 723 } else 724 ssthresh = 0; 725 metrics.rmx_ssthresh = ssthresh; 726 727 metrics.rmx_rtt = tp->t_srtt; 728 metrics.rmx_rttvar = tp->t_rttvar; 729 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 730 metrics.rmx_bandwidth = tp->snd_bandwidth; 731 metrics.rmx_cwnd = tp->snd_cwnd; 732 metrics.rmx_sendpipe = 0; 733 metrics.rmx_recvpipe = 0; 734 735 tcp_hc_update(&inp->inp_inc, &metrics); 736 } 737 738 /* free the reassembly queue, if any */ 739 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 740 LIST_REMOVE(q, tqe_q); 741 m_freem(q->tqe_m); 742 uma_zfree(tcp_reass_zone, q); 743 tp->t_segqlen--; 744 tcp_reass_qsize--; 745 } 746 tcp_free_sackholes(tp); 747 inp->inp_ppcb = NULL; 748 tp->t_inpcb = NULL; 749 uma_zfree(tcpcb_zone, tp); 750 soisdisconnected(so); 751 } 752 753 /* 754 * Close a TCP control block: 755 * discard all space held by the tcp 756 * discard internet protocol block 757 * wake up any sleepers 758 */ 759 struct tcpcb * 760 tcp_close(tp) 761 struct tcpcb *tp; 762 { 763 struct inpcb *inp = tp->t_inpcb; 764 #ifdef INET6 765 struct socket *so = inp->inp_socket; 766 #endif 767 768 INP_LOCK_ASSERT(inp); 769 770 tcp_discardcb(tp); 771 #ifdef INET6 772 if (INP_CHECK_SOCKAF(so, AF_INET6)) 773 in6_pcbdetach(inp); 774 else 775 #endif 776 in_pcbdetach(inp); 777 tcpstat.tcps_closed++; 778 return (NULL); 779 } 780 781 void 782 tcp_drain() 783 { 784 if (do_tcpdrain) 785 { 786 struct inpcb *inpb; 787 struct tcpcb *tcpb; 788 struct tseg_qent *te; 789 790 /* 791 * Walk the tcpbs, if existing, and flush the reassembly queue, 792 * if there is one... 793 * XXX: The "Net/3" implementation doesn't imply that the TCP 794 * reassembly queue should be flushed, but in a situation 795 * where we're really low on mbufs, this is potentially 796 * usefull. 797 */ 798 INP_INFO_RLOCK(&tcbinfo); 799 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 800 if (inpb->inp_vflag & INP_TIMEWAIT) 801 continue; 802 INP_LOCK(inpb); 803 if ((tcpb = intotcpcb(inpb)) != NULL) { 804 while ((te = LIST_FIRST(&tcpb->t_segq)) 805 != NULL) { 806 LIST_REMOVE(te, tqe_q); 807 m_freem(te->tqe_m); 808 uma_zfree(tcp_reass_zone, te); 809 tcpb->t_segqlen--; 810 tcp_reass_qsize--; 811 } 812 tcp_clean_sackreport(tcpb); 813 } 814 INP_UNLOCK(inpb); 815 } 816 INP_INFO_RUNLOCK(&tcbinfo); 817 } 818 } 819 820 /* 821 * Notify a tcp user of an asynchronous error; 822 * store error as soft error, but wake up user 823 * (for now, won't do anything until can select for soft error). 824 * 825 * Do not wake up user since there currently is no mechanism for 826 * reporting soft errors (yet - a kqueue filter may be added). 827 */ 828 static struct inpcb * 829 tcp_notify(inp, error) 830 struct inpcb *inp; 831 int error; 832 { 833 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 834 835 INP_LOCK_ASSERT(inp); 836 837 /* 838 * Ignore some errors if we are hooked up. 839 * If connection hasn't completed, has retransmitted several times, 840 * and receives a second error, give up now. This is better 841 * than waiting a long time to establish a connection that 842 * can never complete. 843 */ 844 if (tp->t_state == TCPS_ESTABLISHED && 845 (error == EHOSTUNREACH || error == ENETUNREACH || 846 error == EHOSTDOWN)) { 847 return (inp); 848 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 849 tp->t_softerror) { 850 tcp_drop(tp, error); 851 return (struct inpcb *)0; 852 } else { 853 tp->t_softerror = error; 854 return (inp); 855 } 856 #if 0 857 wakeup( &so->so_timeo); 858 sorwakeup(so); 859 sowwakeup(so); 860 #endif 861 } 862 863 static int 864 tcp_pcblist(SYSCTL_HANDLER_ARGS) 865 { 866 int error, i, n, s; 867 struct inpcb *inp, **inp_list; 868 inp_gen_t gencnt; 869 struct xinpgen xig; 870 871 /* 872 * The process of preparing the TCB list is too time-consuming and 873 * resource-intensive to repeat twice on every request. 874 */ 875 if (req->oldptr == NULL) { 876 n = tcbinfo.ipi_count; 877 req->oldidx = 2 * (sizeof xig) 878 + (n + n/8) * sizeof(struct xtcpcb); 879 return (0); 880 } 881 882 if (req->newptr != NULL) 883 return (EPERM); 884 885 /* 886 * OK, now we're committed to doing something. 887 */ 888 s = splnet(); 889 INP_INFO_RLOCK(&tcbinfo); 890 gencnt = tcbinfo.ipi_gencnt; 891 n = tcbinfo.ipi_count; 892 INP_INFO_RUNLOCK(&tcbinfo); 893 splx(s); 894 895 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 896 + n * sizeof(struct xtcpcb)); 897 if (error != 0) 898 return (error); 899 900 xig.xig_len = sizeof xig; 901 xig.xig_count = n; 902 xig.xig_gen = gencnt; 903 xig.xig_sogen = so_gencnt; 904 error = SYSCTL_OUT(req, &xig, sizeof xig); 905 if (error) 906 return (error); 907 908 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 909 if (inp_list == NULL) 910 return (ENOMEM); 911 912 s = splnet(); 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 splx(s); 936 n = i; 937 938 error = 0; 939 for (i = 0; i < n; i++) { 940 inp = inp_list[i]; 941 if (inp->inp_gencnt <= gencnt) { 942 struct xtcpcb xt; 943 caddr_t inp_ppcb; 944 xt.xt_len = sizeof xt; 945 /* XXX should avoid extra copy */ 946 bcopy(inp, &xt.xt_inp, sizeof *inp); 947 inp_ppcb = inp->inp_ppcb; 948 if (inp_ppcb == NULL) 949 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 950 else if (inp->inp_vflag & INP_TIMEWAIT) { 951 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 952 xt.xt_tp.t_state = TCPS_TIME_WAIT; 953 } else 954 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 955 if (inp->inp_socket != NULL) 956 sotoxsocket(inp->inp_socket, &xt.xt_socket); 957 else { 958 bzero(&xt.xt_socket, sizeof xt.xt_socket); 959 xt.xt_socket.xso_protocol = IPPROTO_TCP; 960 } 961 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 962 error = SYSCTL_OUT(req, &xt, sizeof xt); 963 } 964 } 965 if (!error) { 966 /* 967 * Give the user an updated idea of our state. 968 * If the generation differs from what we told 969 * her before, she knows that something happened 970 * while we were processing this request, and it 971 * might be necessary to retry. 972 */ 973 s = splnet(); 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 splx(s); 980 error = SYSCTL_OUT(req, &xig, sizeof xig); 981 } 982 free(inp_list, M_TEMP); 983 return (error); 984 } 985 986 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 987 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 988 989 static int 990 tcp_getcred(SYSCTL_HANDLER_ARGS) 991 { 992 struct xucred xuc; 993 struct sockaddr_in addrs[2]; 994 struct inpcb *inp; 995 int error, s; 996 997 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 998 if (error) 999 return (error); 1000 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1001 if (error) 1002 return (error); 1003 s = splnet(); 1004 INP_INFO_RLOCK(&tcbinfo); 1005 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1006 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1007 if (inp == NULL) { 1008 error = ENOENT; 1009 goto outunlocked; 1010 } 1011 INP_LOCK(inp); 1012 if (inp->inp_socket == NULL) { 1013 error = ENOENT; 1014 goto out; 1015 } 1016 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1017 if (error) 1018 goto out; 1019 cru2x(inp->inp_socket->so_cred, &xuc); 1020 out: 1021 INP_UNLOCK(inp); 1022 outunlocked: 1023 INP_INFO_RUNLOCK(&tcbinfo); 1024 splx(s); 1025 if (error == 0) 1026 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1027 return (error); 1028 } 1029 1030 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1031 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1032 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1033 1034 #ifdef INET6 1035 static int 1036 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1037 { 1038 struct xucred xuc; 1039 struct sockaddr_in6 addrs[2]; 1040 struct in6_addr a6[2]; 1041 struct inpcb *inp; 1042 int error, s, mapped = 0; 1043 1044 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1045 if (error) 1046 return (error); 1047 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1048 if (error) 1049 return (error); 1050 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1051 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1052 mapped = 1; 1053 else 1054 return (EINVAL); 1055 } else { 1056 error = in6_embedscope(&a6[0], &addrs[0], NULL, NULL); 1057 if (error) 1058 return (EINVAL); 1059 error = in6_embedscope(&a6[1], &addrs[1], NULL, NULL); 1060 if (error) 1061 return (EINVAL); 1062 } 1063 s = splnet(); 1064 INP_INFO_RLOCK(&tcbinfo); 1065 if (mapped == 1) 1066 inp = in_pcblookup_hash(&tcbinfo, 1067 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1068 addrs[1].sin6_port, 1069 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1070 addrs[0].sin6_port, 1071 0, NULL); 1072 else 1073 inp = in6_pcblookup_hash(&tcbinfo, &a6[1], addrs[1].sin6_port, 1074 &a6[0], addrs[0].sin6_port, 0, NULL); 1075 if (inp == NULL) { 1076 error = ENOENT; 1077 goto outunlocked; 1078 } 1079 INP_LOCK(inp); 1080 if (inp->inp_socket == NULL) { 1081 error = ENOENT; 1082 goto out; 1083 } 1084 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1085 if (error) 1086 goto out; 1087 cru2x(inp->inp_socket->so_cred, &xuc); 1088 out: 1089 INP_UNLOCK(inp); 1090 outunlocked: 1091 INP_INFO_RUNLOCK(&tcbinfo); 1092 splx(s); 1093 if (error == 0) 1094 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1095 return (error); 1096 } 1097 1098 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1099 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1100 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1101 #endif 1102 1103 1104 void 1105 tcp_ctlinput(cmd, sa, vip) 1106 int cmd; 1107 struct sockaddr *sa; 1108 void *vip; 1109 { 1110 struct ip *ip = vip; 1111 struct tcphdr *th; 1112 struct in_addr faddr; 1113 struct inpcb *inp; 1114 struct tcpcb *tp; 1115 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1116 struct icmp *icp; 1117 struct in_conninfo inc; 1118 tcp_seq icmp_tcp_seq; 1119 int mtu, s; 1120 1121 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1122 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1123 return; 1124 1125 if (cmd == PRC_MSGSIZE) 1126 notify = tcp_mtudisc; 1127 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1128 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1129 notify = tcp_drop_syn_sent; 1130 /* 1131 * Redirects don't need to be handled up here. 1132 */ 1133 else if (PRC_IS_REDIRECT(cmd)) 1134 return; 1135 /* 1136 * Source quench is depreciated. 1137 */ 1138 else if (cmd == PRC_QUENCH) 1139 return; 1140 /* 1141 * Hostdead is ugly because it goes linearly through all PCBs. 1142 * XXX: We never get this from ICMP, otherwise it makes an 1143 * excellent DoS attack on machines with many connections. 1144 */ 1145 else if (cmd == PRC_HOSTDEAD) 1146 ip = NULL; 1147 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1148 return; 1149 if (ip != NULL) { 1150 s = splnet(); 1151 icp = (struct icmp *)((caddr_t)ip 1152 - offsetof(struct icmp, icmp_ip)); 1153 th = (struct tcphdr *)((caddr_t)ip 1154 + (ip->ip_hl << 2)); 1155 INP_INFO_WLOCK(&tcbinfo); 1156 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1157 ip->ip_src, th->th_sport, 0, NULL); 1158 if (inp != NULL) { 1159 INP_LOCK(inp); 1160 if (inp->inp_socket != NULL) { 1161 icmp_tcp_seq = htonl(th->th_seq); 1162 tp = intotcpcb(inp); 1163 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1164 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1165 if (cmd == PRC_MSGSIZE) { 1166 /* 1167 * MTU discovery: 1168 * If we got a needfrag set the MTU 1169 * in the route to the suggested new 1170 * value (if given) and then notify. 1171 * If no new MTU was suggested, then 1172 * we guess a new one less than the 1173 * current value. 1174 * If the new MTU is unreasonably 1175 * small (defined by sysctl tcp_minmss), 1176 * then we up the MTU value to minimum. 1177 */ 1178 bzero(&inc, sizeof(inc)); 1179 inc.inc_flags = 0; /* IPv4 */ 1180 inc.inc_faddr = faddr; 1181 1182 mtu = ntohs(icp->icmp_nextmtu); 1183 if (!mtu) 1184 mtu = ip_next_mtu(mtu, 1); 1185 if (mtu >= max(296, (tcp_minmss 1186 + sizeof(struct tcpiphdr)))) 1187 tcp_hc_updatemtu(&inc, mtu); 1188 } 1189 1190 inp = (*notify)(inp, inetctlerrmap[cmd]); 1191 } 1192 } 1193 if (inp != NULL) 1194 INP_UNLOCK(inp); 1195 } else { 1196 inc.inc_fport = th->th_dport; 1197 inc.inc_lport = th->th_sport; 1198 inc.inc_faddr = faddr; 1199 inc.inc_laddr = ip->ip_src; 1200 #ifdef INET6 1201 inc.inc_isipv6 = 0; 1202 #endif 1203 syncache_unreach(&inc, th); 1204 } 1205 INP_INFO_WUNLOCK(&tcbinfo); 1206 splx(s); 1207 } else 1208 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1209 } 1210 1211 #ifdef INET6 1212 void 1213 tcp6_ctlinput(cmd, sa, d) 1214 int cmd; 1215 struct sockaddr *sa; 1216 void *d; 1217 { 1218 struct tcphdr th; 1219 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1220 struct ip6_hdr *ip6; 1221 struct mbuf *m; 1222 struct ip6ctlparam *ip6cp = NULL; 1223 const struct sockaddr_in6 *sa6_src = NULL; 1224 int off; 1225 struct tcp_portonly { 1226 u_int16_t th_sport; 1227 u_int16_t th_dport; 1228 } *thp; 1229 1230 if (sa->sa_family != AF_INET6 || 1231 sa->sa_len != sizeof(struct sockaddr_in6)) 1232 return; 1233 1234 if (cmd == PRC_MSGSIZE) 1235 notify = tcp_mtudisc; 1236 else if (!PRC_IS_REDIRECT(cmd) && 1237 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1238 return; 1239 /* Source quench is depreciated. */ 1240 else if (cmd == PRC_QUENCH) 1241 return; 1242 1243 /* if the parameter is from icmp6, decode it. */ 1244 if (d != NULL) { 1245 ip6cp = (struct ip6ctlparam *)d; 1246 m = ip6cp->ip6c_m; 1247 ip6 = ip6cp->ip6c_ip6; 1248 off = ip6cp->ip6c_off; 1249 sa6_src = ip6cp->ip6c_src; 1250 } else { 1251 m = NULL; 1252 ip6 = NULL; 1253 off = 0; /* fool gcc */ 1254 sa6_src = &sa6_any; 1255 } 1256 1257 if (ip6 != NULL) { 1258 struct in_conninfo inc; 1259 /* 1260 * XXX: We assume that when IPV6 is non NULL, 1261 * M and OFF are valid. 1262 */ 1263 1264 /* check if we can safely examine src and dst ports */ 1265 if (m->m_pkthdr.len < off + sizeof(*thp)) 1266 return; 1267 1268 bzero(&th, sizeof(th)); 1269 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1270 1271 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1272 (struct sockaddr *)ip6cp->ip6c_src, 1273 th.th_sport, cmd, NULL, notify); 1274 1275 inc.inc_fport = th.th_dport; 1276 inc.inc_lport = th.th_sport; 1277 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1278 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1279 inc.inc_isipv6 = 1; 1280 INP_INFO_WLOCK(&tcbinfo); 1281 syncache_unreach(&inc, &th); 1282 INP_INFO_WUNLOCK(&tcbinfo); 1283 } else 1284 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1285 0, cmd, NULL, notify); 1286 } 1287 #endif /* INET6 */ 1288 1289 1290 /* 1291 * Following is where TCP initial sequence number generation occurs. 1292 * 1293 * There are two places where we must use initial sequence numbers: 1294 * 1. In SYN-ACK packets. 1295 * 2. In SYN packets. 1296 * 1297 * All ISNs for SYN-ACK packets are generated by the syncache. See 1298 * tcp_syncache.c for details. 1299 * 1300 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1301 * depends on this property. In addition, these ISNs should be 1302 * unguessable so as to prevent connection hijacking. To satisfy 1303 * the requirements of this situation, the algorithm outlined in 1304 * RFC 1948 is used, with only small modifications. 1305 * 1306 * Implementation details: 1307 * 1308 * Time is based off the system timer, and is corrected so that it 1309 * increases by one megabyte per second. This allows for proper 1310 * recycling on high speed LANs while still leaving over an hour 1311 * before rollover. 1312 * 1313 * As reading the *exact* system time is too expensive to be done 1314 * whenever setting up a TCP connection, we increment the time 1315 * offset in two ways. First, a small random positive increment 1316 * is added to isn_offset for each connection that is set up. 1317 * Second, the function tcp_isn_tick fires once per clock tick 1318 * and increments isn_offset as necessary so that sequence numbers 1319 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1320 * random positive increments serve only to ensure that the same 1321 * exact sequence number is never sent out twice (as could otherwise 1322 * happen when a port is recycled in less than the system tick 1323 * interval.) 1324 * 1325 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1326 * between seeding of isn_secret. This is normally set to zero, 1327 * as reseeding should not be necessary. 1328 * 1329 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1330 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1331 * general, this means holding an exclusive (write) lock. 1332 */ 1333 1334 #define ISN_BYTES_PER_SECOND 1048576 1335 #define ISN_STATIC_INCREMENT 4096 1336 #define ISN_RANDOM_INCREMENT (4096 - 1) 1337 1338 static u_char isn_secret[32]; 1339 static int isn_last_reseed; 1340 static u_int32_t isn_offset, isn_offset_old; 1341 static MD5_CTX isn_ctx; 1342 1343 tcp_seq 1344 tcp_new_isn(tp) 1345 struct tcpcb *tp; 1346 { 1347 u_int32_t md5_buffer[4]; 1348 tcp_seq new_isn; 1349 1350 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1351 INP_LOCK_ASSERT(tp->t_inpcb); 1352 1353 /* Seed if this is the first use, reseed if requested. */ 1354 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1355 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1356 < (u_int)ticks))) { 1357 read_random(&isn_secret, sizeof(isn_secret)); 1358 isn_last_reseed = ticks; 1359 } 1360 1361 /* Compute the md5 hash and return the ISN. */ 1362 MD5Init(&isn_ctx); 1363 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1364 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1365 #ifdef INET6 1366 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1367 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1368 sizeof(struct in6_addr)); 1369 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1370 sizeof(struct in6_addr)); 1371 } else 1372 #endif 1373 { 1374 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1375 sizeof(struct in_addr)); 1376 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1377 sizeof(struct in_addr)); 1378 } 1379 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1380 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1381 new_isn = (tcp_seq) md5_buffer[0]; 1382 isn_offset += ISN_STATIC_INCREMENT + 1383 (arc4random() & ISN_RANDOM_INCREMENT); 1384 new_isn += isn_offset; 1385 return (new_isn); 1386 } 1387 1388 /* 1389 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1390 * to keep time flowing at a relatively constant rate. If the random 1391 * increments have already pushed us past the projected offset, do nothing. 1392 */ 1393 static void 1394 tcp_isn_tick(xtp) 1395 void *xtp; 1396 { 1397 u_int32_t projected_offset; 1398 1399 INP_INFO_WLOCK(&tcbinfo); 1400 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1401 1402 if (projected_offset > isn_offset) 1403 isn_offset = projected_offset; 1404 1405 isn_offset_old = isn_offset; 1406 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1407 INP_INFO_WUNLOCK(&tcbinfo); 1408 } 1409 1410 /* 1411 * When a specific ICMP unreachable message is received and the 1412 * connection state is SYN-SENT, drop the connection. This behavior 1413 * is controlled by the icmp_may_rst sysctl. 1414 */ 1415 struct inpcb * 1416 tcp_drop_syn_sent(inp, errno) 1417 struct inpcb *inp; 1418 int errno; 1419 { 1420 struct tcpcb *tp = intotcpcb(inp); 1421 1422 INP_LOCK_ASSERT(inp); 1423 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1424 tcp_drop(tp, errno); 1425 return (NULL); 1426 } 1427 return (inp); 1428 } 1429 1430 /* 1431 * When `need fragmentation' ICMP is received, update our idea of the MSS 1432 * based on the new value in the route. Also nudge TCP to send something, 1433 * since we know the packet we just sent was dropped. 1434 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1435 */ 1436 struct inpcb * 1437 tcp_mtudisc(inp, errno) 1438 struct inpcb *inp; 1439 int errno; 1440 { 1441 struct tcpcb *tp = intotcpcb(inp); 1442 struct socket *so = inp->inp_socket; 1443 u_int maxmtu; 1444 u_int romtu; 1445 int mss; 1446 #ifdef INET6 1447 int isipv6; 1448 #endif /* INET6 */ 1449 1450 INP_LOCK_ASSERT(inp); 1451 if (tp != NULL) { 1452 #ifdef INET6 1453 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1454 #endif 1455 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1456 romtu = 1457 #ifdef INET6 1458 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1459 #endif /* INET6 */ 1460 tcp_maxmtu(&inp->inp_inc); 1461 if (!maxmtu) 1462 maxmtu = romtu; 1463 else 1464 maxmtu = min(maxmtu, romtu); 1465 if (!maxmtu) { 1466 tp->t_maxopd = tp->t_maxseg = 1467 #ifdef INET6 1468 isipv6 ? tcp_v6mssdflt : 1469 #endif /* INET6 */ 1470 tcp_mssdflt; 1471 return (inp); 1472 } 1473 mss = maxmtu - 1474 #ifdef INET6 1475 (isipv6 ? 1476 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1477 #endif /* INET6 */ 1478 sizeof(struct tcpiphdr) 1479 #ifdef INET6 1480 ) 1481 #endif /* INET6 */ 1482 ; 1483 1484 /* 1485 * XXX - The above conditional probably violates the TCP 1486 * spec. The problem is that, since we don't know the 1487 * other end's MSS, we are supposed to use a conservative 1488 * default. But, if we do that, then MTU discovery will 1489 * never actually take place, because the conservative 1490 * default is much less than the MTUs typically seen 1491 * on the Internet today. For the moment, we'll sweep 1492 * this under the carpet. 1493 * 1494 * The conservative default might not actually be a problem 1495 * if the only case this occurs is when sending an initial 1496 * SYN with options and data to a host we've never talked 1497 * to before. Then, they will reply with an MSS value which 1498 * will get recorded and the new parameters should get 1499 * recomputed. For Further Study. 1500 */ 1501 if (tp->t_maxopd <= mss) 1502 return (inp); 1503 tp->t_maxopd = mss; 1504 1505 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1506 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1507 mss -= TCPOLEN_TSTAMP_APPA; 1508 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1509 if (mss > MCLBYTES) 1510 mss &= ~(MCLBYTES-1); 1511 #else 1512 if (mss > MCLBYTES) 1513 mss = mss / MCLBYTES * MCLBYTES; 1514 #endif 1515 if (so->so_snd.sb_hiwat < mss) 1516 mss = so->so_snd.sb_hiwat; 1517 1518 tp->t_maxseg = mss; 1519 1520 tcpstat.tcps_mturesent++; 1521 tp->t_rtttime = 0; 1522 tp->snd_nxt = tp->snd_una; 1523 tcp_output(tp); 1524 } 1525 return (inp); 1526 } 1527 1528 /* 1529 * Look-up the routing entry to the peer of this inpcb. If no route 1530 * is found and it cannot be allocated, then return NULL. This routine 1531 * is called by TCP routines that access the rmx structure and by tcp_mss 1532 * to get the interface MTU. 1533 */ 1534 u_long 1535 tcp_maxmtu(inc) 1536 struct in_conninfo *inc; 1537 { 1538 struct route sro; 1539 struct sockaddr_in *dst; 1540 struct ifnet *ifp; 1541 u_long maxmtu = 0; 1542 1543 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1544 1545 bzero(&sro, sizeof(sro)); 1546 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1547 dst = (struct sockaddr_in *)&sro.ro_dst; 1548 dst->sin_family = AF_INET; 1549 dst->sin_len = sizeof(*dst); 1550 dst->sin_addr = inc->inc_faddr; 1551 rtalloc_ign(&sro, RTF_CLONING); 1552 } 1553 if (sro.ro_rt != NULL) { 1554 ifp = sro.ro_rt->rt_ifp; 1555 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1556 maxmtu = ifp->if_mtu; 1557 else 1558 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1559 RTFREE(sro.ro_rt); 1560 } 1561 return (maxmtu); 1562 } 1563 1564 #ifdef INET6 1565 u_long 1566 tcp_maxmtu6(inc) 1567 struct in_conninfo *inc; 1568 { 1569 struct route_in6 sro6; 1570 struct ifnet *ifp; 1571 u_long maxmtu = 0; 1572 1573 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1574 1575 bzero(&sro6, sizeof(sro6)); 1576 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1577 sro6.ro_dst.sin6_family = AF_INET6; 1578 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1579 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1580 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1581 } 1582 if (sro6.ro_rt != NULL) { 1583 ifp = sro6.ro_rt->rt_ifp; 1584 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1585 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1586 else 1587 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1588 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1589 RTFREE(sro6.ro_rt); 1590 } 1591 1592 return (maxmtu); 1593 } 1594 #endif /* INET6 */ 1595 1596 #ifdef IPSEC 1597 /* compute ESP/AH header size for TCP, including outer IP header. */ 1598 size_t 1599 ipsec_hdrsiz_tcp(tp) 1600 struct tcpcb *tp; 1601 { 1602 struct inpcb *inp; 1603 struct mbuf *m; 1604 size_t hdrsiz; 1605 struct ip *ip; 1606 #ifdef INET6 1607 struct ip6_hdr *ip6; 1608 #endif 1609 struct tcphdr *th; 1610 1611 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1612 return (0); 1613 MGETHDR(m, M_DONTWAIT, MT_DATA); 1614 if (!m) 1615 return (0); 1616 1617 #ifdef INET6 1618 if ((inp->inp_vflag & INP_IPV6) != 0) { 1619 ip6 = mtod(m, struct ip6_hdr *); 1620 th = (struct tcphdr *)(ip6 + 1); 1621 m->m_pkthdr.len = m->m_len = 1622 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1623 tcpip_fillheaders(inp, ip6, th); 1624 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1625 } else 1626 #endif /* INET6 */ 1627 { 1628 ip = mtod(m, struct ip *); 1629 th = (struct tcphdr *)(ip + 1); 1630 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1631 tcpip_fillheaders(inp, ip, th); 1632 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1633 } 1634 1635 m_free(m); 1636 return (hdrsiz); 1637 } 1638 #endif /*IPSEC*/ 1639 1640 /* 1641 * Move a TCP connection into TIME_WAIT state. 1642 * tcbinfo is locked. 1643 * inp is locked, and is unlocked before returning. 1644 */ 1645 void 1646 tcp_twstart(tp) 1647 struct tcpcb *tp; 1648 { 1649 struct tcptw *tw; 1650 struct inpcb *inp; 1651 int tw_time, acknow; 1652 struct socket *so; 1653 1654 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1655 INP_LOCK_ASSERT(tp->t_inpcb); 1656 1657 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1658 if (tw == NULL) { 1659 tw = tcp_timer_2msl_tw(1); 1660 if (tw == NULL) { 1661 tcp_close(tp); 1662 return; 1663 } 1664 } 1665 inp = tp->t_inpcb; 1666 tw->tw_inpcb = inp; 1667 1668 /* 1669 * Recover last window size sent. 1670 */ 1671 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1672 1673 /* 1674 * Set t_recent if timestamps are used on the connection. 1675 */ 1676 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1677 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1678 tw->t_recent = tp->ts_recent; 1679 else 1680 tw->t_recent = 0; 1681 1682 tw->snd_nxt = tp->snd_nxt; 1683 tw->rcv_nxt = tp->rcv_nxt; 1684 tw->iss = tp->iss; 1685 tw->irs = tp->irs; 1686 tw->t_starttime = tp->t_starttime; 1687 tw->tw_time = 0; 1688 1689 /* XXX 1690 * If this code will 1691 * be used for fin-wait-2 state also, then we may need 1692 * a ts_recent from the last segment. 1693 */ 1694 tw_time = 2 * tcp_msl; 1695 acknow = tp->t_flags & TF_ACKNOW; 1696 tcp_discardcb(tp); 1697 so = inp->inp_socket; 1698 ACCEPT_LOCK(); 1699 SOCK_LOCK(so); 1700 so->so_pcb = NULL; 1701 tw->tw_cred = crhold(so->so_cred); 1702 tw->tw_so_options = so->so_options; 1703 sotryfree(so); 1704 inp->inp_socket = NULL; 1705 if (acknow) 1706 tcp_twrespond(tw, TH_ACK); 1707 inp->inp_ppcb = (caddr_t)tw; 1708 inp->inp_vflag |= INP_TIMEWAIT; 1709 tcp_timer_2msl_reset(tw, tw_time); 1710 INP_UNLOCK(inp); 1711 } 1712 1713 /* 1714 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1715 * the actual rate is slightly higher due to the addition of 1716 * random positive increments. 1717 * 1718 * Most other new OSes use semi-randomized ISN values, so we 1719 * do not need to worry about them. 1720 */ 1721 #define MS_ISN_BYTES_PER_SECOND 250000 1722 1723 /* 1724 * Determine if the ISN we will generate has advanced beyond the last 1725 * sequence number used by the previous connection. If so, indicate 1726 * that it is safe to recycle this tw socket by returning 1. 1727 * 1728 * XXXRW: This function should assert the inpcb lock as it does multiple 1729 * non-atomic reads from the tcptw, but is currently called without it from 1730 * in_pcb.c:in_pcblookup_local(). 1731 */ 1732 int 1733 tcp_twrecycleable(struct tcptw *tw) 1734 { 1735 tcp_seq new_iss = tw->iss; 1736 tcp_seq new_irs = tw->irs; 1737 1738 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1739 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1740 1741 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1742 return (1); 1743 else 1744 return (0); 1745 } 1746 1747 struct tcptw * 1748 tcp_twclose(struct tcptw *tw, int reuse) 1749 { 1750 struct inpcb *inp; 1751 1752 inp = tw->tw_inpcb; 1753 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1754 INP_LOCK_ASSERT(inp); 1755 1756 tw->tw_inpcb = NULL; 1757 tcp_timer_2msl_stop(tw); 1758 inp->inp_ppcb = NULL; 1759 #ifdef INET6 1760 if (inp->inp_vflag & INP_IPV6PROTO) 1761 in6_pcbdetach(inp); 1762 else 1763 #endif 1764 in_pcbdetach(inp); 1765 tcpstat.tcps_closed++; 1766 crfree(tw->tw_cred); 1767 tw->tw_cred = NULL; 1768 if (reuse) 1769 return (tw); 1770 uma_zfree(tcptw_zone, tw); 1771 return (NULL); 1772 } 1773 1774 int 1775 tcp_twrespond(struct tcptw *tw, int flags) 1776 { 1777 struct inpcb *inp = tw->tw_inpcb; 1778 struct tcphdr *th; 1779 struct mbuf *m; 1780 struct ip *ip = NULL; 1781 u_int8_t *optp; 1782 u_int hdrlen, optlen; 1783 int error; 1784 #ifdef INET6 1785 struct ip6_hdr *ip6 = NULL; 1786 int isipv6 = inp->inp_inc.inc_isipv6; 1787 #endif 1788 1789 INP_LOCK_ASSERT(inp); 1790 1791 m = m_gethdr(M_DONTWAIT, MT_HEADER); 1792 if (m == NULL) 1793 return (ENOBUFS); 1794 m->m_data += max_linkhdr; 1795 1796 #ifdef MAC 1797 mac_create_mbuf_from_inpcb(inp, m); 1798 #endif 1799 1800 #ifdef INET6 1801 if (isipv6) { 1802 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1803 ip6 = mtod(m, struct ip6_hdr *); 1804 th = (struct tcphdr *)(ip6 + 1); 1805 tcpip_fillheaders(inp, ip6, th); 1806 } else 1807 #endif 1808 { 1809 hdrlen = sizeof(struct tcpiphdr); 1810 ip = mtod(m, struct ip *); 1811 th = (struct tcphdr *)(ip + 1); 1812 tcpip_fillheaders(inp, ip, th); 1813 } 1814 optp = (u_int8_t *)(th + 1); 1815 1816 /* 1817 * Send a timestamp and echo-reply if both our side and our peer 1818 * have sent timestamps in our SYN's and this is not a RST. 1819 */ 1820 if (tw->t_recent && flags == TH_ACK) { 1821 u_int32_t *lp = (u_int32_t *)optp; 1822 1823 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1824 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1825 *lp++ = htonl(ticks); 1826 *lp = htonl(tw->t_recent); 1827 optp += TCPOLEN_TSTAMP_APPA; 1828 } 1829 1830 optlen = optp - (u_int8_t *)(th + 1); 1831 1832 m->m_len = hdrlen + optlen; 1833 m->m_pkthdr.len = m->m_len; 1834 1835 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1836 1837 th->th_seq = htonl(tw->snd_nxt); 1838 th->th_ack = htonl(tw->rcv_nxt); 1839 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1840 th->th_flags = flags; 1841 th->th_win = htons(tw->last_win); 1842 1843 #ifdef INET6 1844 if (isipv6) { 1845 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1846 sizeof(struct tcphdr) + optlen); 1847 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1848 error = ip6_output(m, inp->in6p_outputopts, NULL, 1849 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1850 } else 1851 #endif 1852 { 1853 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1854 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1855 m->m_pkthdr.csum_flags = CSUM_TCP; 1856 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1857 ip->ip_len = m->m_pkthdr.len; 1858 if (path_mtu_discovery) 1859 ip->ip_off |= IP_DF; 1860 error = ip_output(m, inp->inp_options, NULL, 1861 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1862 NULL, inp); 1863 } 1864 if (flags & TH_ACK) 1865 tcpstat.tcps_sndacks++; 1866 else 1867 tcpstat.tcps_sndctrl++; 1868 tcpstat.tcps_sndtotal++; 1869 return (error); 1870 } 1871 1872 /* 1873 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1874 * 1875 * This code attempts to calculate the bandwidth-delay product as a 1876 * means of determining the optimal window size to maximize bandwidth, 1877 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1878 * routers. This code also does a fairly good job keeping RTTs in check 1879 * across slow links like modems. We implement an algorithm which is very 1880 * similar (but not meant to be) TCP/Vegas. The code operates on the 1881 * transmitter side of a TCP connection and so only effects the transmit 1882 * side of the connection. 1883 * 1884 * BACKGROUND: TCP makes no provision for the management of buffer space 1885 * at the end points or at the intermediate routers and switches. A TCP 1886 * stream, whether using NewReno or not, will eventually buffer as 1887 * many packets as it is able and the only reason this typically works is 1888 * due to the fairly small default buffers made available for a connection 1889 * (typicaly 16K or 32K). As machines use larger windows and/or window 1890 * scaling it is now fairly easy for even a single TCP connection to blow-out 1891 * all available buffer space not only on the local interface, but on 1892 * intermediate routers and switches as well. NewReno makes a misguided 1893 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1894 * then backing off, then steadily increasing the window again until another 1895 * failure occurs, ad-infinitum. This results in terrible oscillation that 1896 * is only made worse as network loads increase and the idea of intentionally 1897 * blowing out network buffers is, frankly, a terrible way to manage network 1898 * resources. 1899 * 1900 * It is far better to limit the transmit window prior to the failure 1901 * condition being achieved. There are two general ways to do this: First 1902 * you can 'scan' through different transmit window sizes and locate the 1903 * point where the RTT stops increasing, indicating that you have filled the 1904 * pipe, then scan backwards until you note that RTT stops decreasing, then 1905 * repeat ad-infinitum. This method works in principle but has severe 1906 * implementation issues due to RTT variances, timer granularity, and 1907 * instability in the algorithm which can lead to many false positives and 1908 * create oscillations as well as interact badly with other TCP streams 1909 * implementing the same algorithm. 1910 * 1911 * The second method is to limit the window to the bandwidth delay product 1912 * of the link. This is the method we implement. RTT variances and our 1913 * own manipulation of the congestion window, bwnd, can potentially 1914 * destabilize the algorithm. For this reason we have to stabilize the 1915 * elements used to calculate the window. We do this by using the minimum 1916 * observed RTT, the long term average of the observed bandwidth, and 1917 * by adding two segments worth of slop. It isn't perfect but it is able 1918 * to react to changing conditions and gives us a very stable basis on 1919 * which to extend the algorithm. 1920 */ 1921 void 1922 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1923 { 1924 u_long bw; 1925 u_long bwnd; 1926 int save_ticks; 1927 1928 INP_LOCK_ASSERT(tp->t_inpcb); 1929 1930 /* 1931 * If inflight_enable is disabled in the middle of a tcp connection, 1932 * make sure snd_bwnd is effectively disabled. 1933 */ 1934 if (tcp_inflight_enable == 0) { 1935 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1936 tp->snd_bandwidth = 0; 1937 return; 1938 } 1939 1940 /* 1941 * Figure out the bandwidth. Due to the tick granularity this 1942 * is a very rough number and it MUST be averaged over a fairly 1943 * long period of time. XXX we need to take into account a link 1944 * that is not using all available bandwidth, but for now our 1945 * slop will ramp us up if this case occurs and the bandwidth later 1946 * increases. 1947 * 1948 * Note: if ticks rollover 'bw' may wind up negative. We must 1949 * effectively reset t_bw_rtttime for this case. 1950 */ 1951 save_ticks = ticks; 1952 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1953 return; 1954 1955 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1956 (save_ticks - tp->t_bw_rtttime); 1957 tp->t_bw_rtttime = save_ticks; 1958 tp->t_bw_rtseq = ack_seq; 1959 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1960 return; 1961 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1962 1963 tp->snd_bandwidth = bw; 1964 1965 /* 1966 * Calculate the semi-static bandwidth delay product, plus two maximal 1967 * segments. The additional slop puts us squarely in the sweet 1968 * spot and also handles the bandwidth run-up case and stabilization. 1969 * Without the slop we could be locking ourselves into a lower 1970 * bandwidth. 1971 * 1972 * Situations Handled: 1973 * (1) Prevents over-queueing of packets on LANs, especially on 1974 * high speed LANs, allowing larger TCP buffers to be 1975 * specified, and also does a good job preventing 1976 * over-queueing of packets over choke points like modems 1977 * (at least for the transmit side). 1978 * 1979 * (2) Is able to handle changing network loads (bandwidth 1980 * drops so bwnd drops, bandwidth increases so bwnd 1981 * increases). 1982 * 1983 * (3) Theoretically should stabilize in the face of multiple 1984 * connections implementing the same algorithm (this may need 1985 * a little work). 1986 * 1987 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1988 * be adjusted with a sysctl but typically only needs to be 1989 * on very slow connections. A value no smaller then 5 1990 * should be used, but only reduce this default if you have 1991 * no other choice. 1992 */ 1993 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1994 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 1995 #undef USERTT 1996 1997 if (tcp_inflight_debug > 0) { 1998 static int ltime; 1999 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2000 ltime = ticks; 2001 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2002 tp, 2003 bw, 2004 tp->t_rttbest, 2005 tp->t_srtt, 2006 bwnd 2007 ); 2008 } 2009 } 2010 if ((long)bwnd < tcp_inflight_min) 2011 bwnd = tcp_inflight_min; 2012 if (bwnd > tcp_inflight_max) 2013 bwnd = tcp_inflight_max; 2014 if ((long)bwnd < tp->t_maxseg * 2) 2015 bwnd = tp->t_maxseg * 2; 2016 tp->snd_bwnd = bwnd; 2017 } 2018 2019 #ifdef TCP_SIGNATURE 2020 /* 2021 * Callback function invoked by m_apply() to digest TCP segment data 2022 * contained within an mbuf chain. 2023 */ 2024 static int 2025 tcp_signature_apply(void *fstate, void *data, u_int len) 2026 { 2027 2028 MD5Update(fstate, (u_char *)data, len); 2029 return (0); 2030 } 2031 2032 /* 2033 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2034 * 2035 * Parameters: 2036 * m pointer to head of mbuf chain 2037 * off0 offset to TCP header within the mbuf chain 2038 * len length of TCP segment data, excluding options 2039 * optlen length of TCP segment options 2040 * buf pointer to storage for computed MD5 digest 2041 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2042 * 2043 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2044 * When called from tcp_input(), we can be sure that th_sum has been 2045 * zeroed out and verified already. 2046 * 2047 * This function is for IPv4 use only. Calling this function with an 2048 * IPv6 packet in the mbuf chain will yield undefined results. 2049 * 2050 * Return 0 if successful, otherwise return -1. 2051 * 2052 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2053 * search with the destination IP address, and a 'magic SPI' to be 2054 * determined by the application. This is hardcoded elsewhere to 1179 2055 * right now. Another branch of this code exists which uses the SPD to 2056 * specify per-application flows but it is unstable. 2057 */ 2058 int 2059 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2060 u_char *buf, u_int direction) 2061 { 2062 union sockaddr_union dst; 2063 struct ippseudo ippseudo; 2064 MD5_CTX ctx; 2065 int doff; 2066 struct ip *ip; 2067 struct ipovly *ipovly; 2068 struct secasvar *sav; 2069 struct tcphdr *th; 2070 u_short savecsum; 2071 2072 KASSERT(m != NULL, ("NULL mbuf chain")); 2073 KASSERT(buf != NULL, ("NULL signature pointer")); 2074 2075 /* Extract the destination from the IP header in the mbuf. */ 2076 ip = mtod(m, struct ip *); 2077 bzero(&dst, sizeof(union sockaddr_union)); 2078 dst.sa.sa_len = sizeof(struct sockaddr_in); 2079 dst.sa.sa_family = AF_INET; 2080 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2081 ip->ip_src : ip->ip_dst; 2082 2083 /* Look up an SADB entry which matches the address of the peer. */ 2084 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2085 if (sav == NULL) { 2086 printf("%s: SADB lookup failed for %s\n", __func__, 2087 inet_ntoa(dst.sin.sin_addr)); 2088 return (EINVAL); 2089 } 2090 2091 MD5Init(&ctx); 2092 ipovly = (struct ipovly *)ip; 2093 th = (struct tcphdr *)((u_char *)ip + off0); 2094 doff = off0 + sizeof(struct tcphdr) + optlen; 2095 2096 /* 2097 * Step 1: Update MD5 hash with IP pseudo-header. 2098 * 2099 * XXX The ippseudo header MUST be digested in network byte order, 2100 * or else we'll fail the regression test. Assume all fields we've 2101 * been doing arithmetic on have been in host byte order. 2102 * XXX One cannot depend on ipovly->ih_len here. When called from 2103 * tcp_output(), the underlying ip_len member has not yet been set. 2104 */ 2105 ippseudo.ippseudo_src = ipovly->ih_src; 2106 ippseudo.ippseudo_dst = ipovly->ih_dst; 2107 ippseudo.ippseudo_pad = 0; 2108 ippseudo.ippseudo_p = IPPROTO_TCP; 2109 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2110 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2111 2112 /* 2113 * Step 2: Update MD5 hash with TCP header, excluding options. 2114 * The TCP checksum must be set to zero. 2115 */ 2116 savecsum = th->th_sum; 2117 th->th_sum = 0; 2118 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2119 th->th_sum = savecsum; 2120 2121 /* 2122 * Step 3: Update MD5 hash with TCP segment data. 2123 * Use m_apply() to avoid an early m_pullup(). 2124 */ 2125 if (len > 0) 2126 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2127 2128 /* 2129 * Step 4: Update MD5 hash with shared secret. 2130 */ 2131 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2132 MD5Final(buf, &ctx); 2133 2134 key_sa_recordxfer(sav, m); 2135 KEY_FREESAV(&sav); 2136 return (0); 2137 } 2138 #endif /* TCP_SIGNATURE */ 2139 2140 static int 2141 sysctl_drop(SYSCTL_HANDLER_ARGS) 2142 { 2143 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2144 struct sockaddr_storage addrs[2]; 2145 struct inpcb *inp; 2146 struct tcpcb *tp; 2147 struct sockaddr_in *fin, *lin; 2148 #ifdef INET6 2149 struct sockaddr_in6 *fin6, *lin6; 2150 struct in6_addr f6, l6; 2151 #endif 2152 int error; 2153 2154 inp = NULL; 2155 fin = lin = NULL; 2156 #ifdef INET6 2157 fin6 = lin6 = NULL; 2158 #endif 2159 error = 0; 2160 2161 if (req->oldptr != NULL || req->oldlen != 0) 2162 return (EINVAL); 2163 if (req->newptr == NULL) 2164 return (EPERM); 2165 if (req->newlen < sizeof(addrs)) 2166 return (ENOMEM); 2167 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2168 if (error) 2169 return (error); 2170 2171 switch (addrs[0].ss_family) { 2172 #ifdef INET6 2173 case AF_INET6: 2174 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2175 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2176 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2177 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2178 return (EINVAL); 2179 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2180 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2181 return (EINVAL); 2182 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2183 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2184 fin = (struct sockaddr_in *)&addrs[0]; 2185 lin = (struct sockaddr_in *)&addrs[1]; 2186 break; 2187 } 2188 error = in6_embedscope(&f6, fin6, NULL, NULL); 2189 if (error) 2190 return (EINVAL); 2191 error = in6_embedscope(&l6, lin6, NULL, NULL); 2192 if (error) 2193 return (EINVAL); 2194 break; 2195 #endif 2196 case AF_INET: 2197 fin = (struct sockaddr_in *)&addrs[0]; 2198 lin = (struct sockaddr_in *)&addrs[1]; 2199 if (fin->sin_len != sizeof(struct sockaddr_in) || 2200 lin->sin_len != sizeof(struct sockaddr_in)) 2201 return (EINVAL); 2202 break; 2203 default: 2204 return (EINVAL); 2205 } 2206 INP_INFO_WLOCK(&tcbinfo); 2207 switch (addrs[0].ss_family) { 2208 #ifdef INET6 2209 case AF_INET6: 2210 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2211 &l6, lin6->sin6_port, 0, NULL); 2212 break; 2213 #endif 2214 case AF_INET: 2215 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2216 lin->sin_addr, lin->sin_port, 0, NULL); 2217 break; 2218 } 2219 if (inp != NULL) { 2220 INP_LOCK(inp); 2221 if ((tp = intotcpcb(inp)) && 2222 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2223 tp = tcp_drop(tp, ECONNABORTED); 2224 if (tp != NULL) 2225 INP_UNLOCK(inp); 2226 } else 2227 INP_UNLOCK(inp); 2228 } else 2229 error = ESRCH; 2230 INP_INFO_WUNLOCK(&tcbinfo); 2231 return (error); 2232 } 2233 2234 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2235 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2236 0, sysctl_drop, "", "Drop TCP connection"); 2237