1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 * $FreeBSD$ 31 */ 32 33 #include "opt_compat.h" 34 #include "opt_inet.h" 35 #include "opt_inet6.h" 36 #include "opt_ipsec.h" 37 #include "opt_mac.h" 38 #include "opt_tcpdebug.h" 39 #include "opt_tcp_sack.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/callout.h> 44 #include <sys/kernel.h> 45 #include <sys/sysctl.h> 46 #include <sys/mac.h> 47 #include <sys/malloc.h> 48 #include <sys/mbuf.h> 49 #ifdef INET6 50 #include <sys/domain.h> 51 #endif 52 #include <sys/proc.h> 53 #include <sys/socket.h> 54 #include <sys/socketvar.h> 55 #include <sys/protosw.h> 56 #include <sys/random.h> 57 58 #include <vm/uma.h> 59 60 #include <net/route.h> 61 #include <net/if.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_systm.h> 65 #include <netinet/ip.h> 66 #ifdef INET6 67 #include <netinet/ip6.h> 68 #endif 69 #include <netinet/in_pcb.h> 70 #ifdef INET6 71 #include <netinet6/in6_pcb.h> 72 #endif 73 #include <netinet/in_var.h> 74 #include <netinet/ip_var.h> 75 #ifdef INET6 76 #include <netinet6/ip6_var.h> 77 #include <netinet6/scope6_var.h> 78 #include <netinet6/nd6.h> 79 #endif 80 #include <netinet/ip_icmp.h> 81 #include <netinet/tcp.h> 82 #include <netinet/tcp_fsm.h> 83 #include <netinet/tcp_seq.h> 84 #include <netinet/tcp_timer.h> 85 #include <netinet/tcp_var.h> 86 #ifdef INET6 87 #include <netinet6/tcp6_var.h> 88 #endif 89 #include <netinet/tcpip.h> 90 #ifdef TCPDEBUG 91 #include <netinet/tcp_debug.h> 92 #endif 93 #include <netinet6/ip6protosw.h> 94 95 #ifdef IPSEC 96 #include <netinet6/ipsec.h> 97 #ifdef INET6 98 #include <netinet6/ipsec6.h> 99 #endif 100 #include <netkey/key.h> 101 #endif /*IPSEC*/ 102 103 #ifdef FAST_IPSEC 104 #include <netipsec/ipsec.h> 105 #include <netipsec/xform.h> 106 #ifdef INET6 107 #include <netipsec/ipsec6.h> 108 #endif 109 #include <netipsec/key.h> 110 #define IPSEC 111 #endif /*FAST_IPSEC*/ 112 113 #include <machine/in_cksum.h> 114 #include <sys/md5.h> 115 116 int tcp_mssdflt = TCP_MSS; 117 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 118 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 119 120 #ifdef INET6 121 int tcp_v6mssdflt = TCP6_MSS; 122 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 123 CTLFLAG_RW, &tcp_v6mssdflt , 0, 124 "Default TCP Maximum Segment Size for IPv6"); 125 #endif 126 127 /* 128 * Minimum MSS we accept and use. This prevents DoS attacks where 129 * we are forced to a ridiculous low MSS like 20 and send hundreds 130 * of packets instead of one. The effect scales with the available 131 * bandwidth and quickly saturates the CPU and network interface 132 * with packet generation and sending. Set to zero to disable MINMSS 133 * checking. This setting prevents us from sending too small packets. 134 */ 135 int tcp_minmss = TCP_MINMSS; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 137 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 138 /* 139 * Number of TCP segments per second we accept from remote host 140 * before we start to calculate average segment size. If average 141 * segment size drops below the minimum TCP MSS we assume a DoS 142 * attack and reset+drop the connection. Care has to be taken not to 143 * set this value too small to not kill interactive type connections 144 * (telnet, SSH) which send many small packets. 145 */ 146 int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW, 148 &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to" 149 "be under the MINMSS Size"); 150 151 #if 0 152 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 153 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 154 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 155 #endif 156 157 int tcp_do_rfc1323 = 1; 158 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 159 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 160 161 static int tcp_tcbhashsize = 0; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 163 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 164 165 static int do_tcpdrain = 1; 166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 167 "Enable tcp_drain routine for extra help when low on mbufs"); 168 169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 170 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 171 172 static int icmp_may_rst = 1; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 174 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 175 176 static int tcp_isn_reseed_interval = 0; 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 178 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 179 180 /* 181 * TCP bandwidth limiting sysctls. Note that the default lower bound of 182 * 1024 exists only for debugging. A good production default would be 183 * something like 6100. 184 */ 185 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 186 "TCP inflight data limiting"); 187 188 static int tcp_inflight_enable = 1; 189 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 190 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 191 192 static int tcp_inflight_debug = 0; 193 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 194 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 195 196 static int tcp_inflight_rttthresh; 197 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 198 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 199 "RTT threshold below which inflight will deactivate itself"); 200 201 static int tcp_inflight_min = 6144; 202 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 203 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 204 205 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 206 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 207 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 208 209 static int tcp_inflight_stab = 20; 210 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 211 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 212 213 uma_zone_t sack_hole_zone; 214 215 static struct inpcb *tcp_notify(struct inpcb *, int); 216 static void tcp_discardcb(struct tcpcb *); 217 static void tcp_isn_tick(void *); 218 219 /* 220 * Target size of TCP PCB hash tables. Must be a power of two. 221 * 222 * Note that this can be overridden by the kernel environment 223 * variable net.inet.tcp.tcbhashsize 224 */ 225 #ifndef TCBHASHSIZE 226 #define TCBHASHSIZE 512 227 #endif 228 229 /* 230 * XXX 231 * Callouts should be moved into struct tcp directly. They are currently 232 * separate because the tcpcb structure is exported to userland for sysctl 233 * parsing purposes, which do not know about callouts. 234 */ 235 struct tcpcb_mem { 236 struct tcpcb tcb; 237 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 238 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 239 }; 240 241 static uma_zone_t tcpcb_zone; 242 static uma_zone_t tcptw_zone; 243 struct callout isn_callout; 244 245 /* 246 * Tcp initialization 247 */ 248 void 249 tcp_init() 250 { 251 int hashsize = TCBHASHSIZE; 252 253 tcp_delacktime = TCPTV_DELACK; 254 tcp_keepinit = TCPTV_KEEP_INIT; 255 tcp_keepidle = TCPTV_KEEP_IDLE; 256 tcp_keepintvl = TCPTV_KEEPINTVL; 257 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 258 tcp_msl = TCPTV_MSL; 259 tcp_rexmit_min = TCPTV_MIN; 260 tcp_rexmit_slop = TCPTV_CPU_VAR; 261 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 262 263 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 264 LIST_INIT(&tcb); 265 tcbinfo.listhead = &tcb; 266 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 267 if (!powerof2(hashsize)) { 268 printf("WARNING: TCB hash size not a power of 2\n"); 269 hashsize = 512; /* safe default */ 270 } 271 tcp_tcbhashsize = hashsize; 272 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 273 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 274 &tcbinfo.porthashmask); 275 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 276 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 277 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 278 #ifdef INET6 279 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 280 #else /* INET6 */ 281 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 282 #endif /* INET6 */ 283 if (max_protohdr < TCP_MINPROTOHDR) 284 max_protohdr = TCP_MINPROTOHDR; 285 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 286 panic("tcp_init"); 287 #undef TCP_MINPROTOHDR 288 /* 289 * These have to be type stable for the benefit of the timers. 290 */ 291 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 292 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 293 uma_zone_set_max(tcpcb_zone, maxsockets); 294 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 295 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 296 uma_zone_set_max(tcptw_zone, maxsockets / 5); 297 tcp_timer_init(); 298 syncache_init(); 299 tcp_hc_init(); 300 tcp_reass_init(); 301 callout_init(&isn_callout, CALLOUT_MPSAFE); 302 tcp_isn_tick(NULL); 303 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 304 SHUTDOWN_PRI_DEFAULT); 305 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 306 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 307 } 308 309 void 310 tcp_fini(xtp) 311 void *xtp; 312 { 313 callout_stop(&isn_callout); 314 315 } 316 317 /* 318 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 319 * tcp_template used to store this data in mbufs, but we now recopy it out 320 * of the tcpcb each time to conserve mbufs. 321 */ 322 void 323 tcpip_fillheaders(inp, ip_ptr, tcp_ptr) 324 struct inpcb *inp; 325 void *ip_ptr; 326 void *tcp_ptr; 327 { 328 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 329 330 INP_LOCK_ASSERT(inp); 331 332 #ifdef INET6 333 if ((inp->inp_vflag & INP_IPV6) != 0) { 334 struct ip6_hdr *ip6; 335 336 ip6 = (struct ip6_hdr *)ip_ptr; 337 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 338 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 339 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 340 (IPV6_VERSION & IPV6_VERSION_MASK); 341 ip6->ip6_nxt = IPPROTO_TCP; 342 ip6->ip6_plen = sizeof(struct tcphdr); 343 ip6->ip6_src = inp->in6p_laddr; 344 ip6->ip6_dst = inp->in6p_faddr; 345 } else 346 #endif 347 { 348 struct ip *ip; 349 350 ip = (struct ip *)ip_ptr; 351 ip->ip_v = IPVERSION; 352 ip->ip_hl = 5; 353 ip->ip_tos = inp->inp_ip_tos; 354 ip->ip_len = 0; 355 ip->ip_id = 0; 356 ip->ip_off = 0; 357 ip->ip_ttl = inp->inp_ip_ttl; 358 ip->ip_sum = 0; 359 ip->ip_p = IPPROTO_TCP; 360 ip->ip_src = inp->inp_laddr; 361 ip->ip_dst = inp->inp_faddr; 362 } 363 th->th_sport = inp->inp_lport; 364 th->th_dport = inp->inp_fport; 365 th->th_seq = 0; 366 th->th_ack = 0; 367 th->th_x2 = 0; 368 th->th_off = 5; 369 th->th_flags = 0; 370 th->th_win = 0; 371 th->th_urp = 0; 372 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 373 } 374 375 /* 376 * Create template to be used to send tcp packets on a connection. 377 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 378 * use for this function is in keepalives, which use tcp_respond. 379 */ 380 struct tcptemp * 381 tcpip_maketemplate(inp) 382 struct inpcb *inp; 383 { 384 struct mbuf *m; 385 struct tcptemp *n; 386 387 m = m_get(M_DONTWAIT, MT_DATA); 388 if (m == NULL) 389 return (0); 390 m->m_len = sizeof(struct tcptemp); 391 n = mtod(m, struct tcptemp *); 392 393 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 394 return (n); 395 } 396 397 /* 398 * Send a single message to the TCP at address specified by 399 * the given TCP/IP header. If m == NULL, then we make a copy 400 * of the tcpiphdr at ti and send directly to the addressed host. 401 * This is used to force keep alive messages out using the TCP 402 * template for a connection. If flags are given then we send 403 * a message back to the TCP which originated the * segment ti, 404 * and discard the mbuf containing it and any other attached mbufs. 405 * 406 * In any case the ack and sequence number of the transmitted 407 * segment are as specified by the parameters. 408 * 409 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 410 */ 411 void 412 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 413 struct tcpcb *tp; 414 void *ipgen; 415 register struct tcphdr *th; 416 register struct mbuf *m; 417 tcp_seq ack, seq; 418 int flags; 419 { 420 register int tlen; 421 int win = 0; 422 struct ip *ip; 423 struct tcphdr *nth; 424 #ifdef INET6 425 struct ip6_hdr *ip6; 426 int isipv6; 427 #endif /* INET6 */ 428 int ipflags = 0; 429 struct inpcb *inp; 430 431 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 432 433 #ifdef INET6 434 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 435 ip6 = ipgen; 436 #endif /* INET6 */ 437 ip = ipgen; 438 439 if (tp != NULL) { 440 inp = tp->t_inpcb; 441 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 442 INP_INFO_WLOCK_ASSERT(&tcbinfo); 443 INP_LOCK_ASSERT(inp); 444 } else 445 inp = NULL; 446 447 if (tp != NULL) { 448 if (!(flags & TH_RST)) { 449 win = sbspace(&inp->inp_socket->so_rcv); 450 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 451 win = (long)TCP_MAXWIN << tp->rcv_scale; 452 } 453 } 454 if (m == NULL) { 455 m = m_gethdr(M_DONTWAIT, MT_DATA); 456 if (m == NULL) 457 return; 458 tlen = 0; 459 m->m_data += max_linkhdr; 460 #ifdef INET6 461 if (isipv6) { 462 bcopy((caddr_t)ip6, mtod(m, caddr_t), 463 sizeof(struct ip6_hdr)); 464 ip6 = mtod(m, struct ip6_hdr *); 465 nth = (struct tcphdr *)(ip6 + 1); 466 } else 467 #endif /* INET6 */ 468 { 469 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 470 ip = mtod(m, struct ip *); 471 nth = (struct tcphdr *)(ip + 1); 472 } 473 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 474 flags = TH_ACK; 475 } else { 476 m_freem(m->m_next); 477 m->m_next = NULL; 478 m->m_data = (caddr_t)ipgen; 479 /* m_len is set later */ 480 tlen = 0; 481 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 482 #ifdef INET6 483 if (isipv6) { 484 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 485 nth = (struct tcphdr *)(ip6 + 1); 486 } else 487 #endif /* INET6 */ 488 { 489 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 490 nth = (struct tcphdr *)(ip + 1); 491 } 492 if (th != nth) { 493 /* 494 * this is usually a case when an extension header 495 * exists between the IPv6 header and the 496 * TCP header. 497 */ 498 nth->th_sport = th->th_sport; 499 nth->th_dport = th->th_dport; 500 } 501 xchg(nth->th_dport, nth->th_sport, n_short); 502 #undef xchg 503 } 504 #ifdef INET6 505 if (isipv6) { 506 ip6->ip6_flow = 0; 507 ip6->ip6_vfc = IPV6_VERSION; 508 ip6->ip6_nxt = IPPROTO_TCP; 509 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 510 tlen)); 511 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 512 } else 513 #endif 514 { 515 tlen += sizeof (struct tcpiphdr); 516 ip->ip_len = tlen; 517 ip->ip_ttl = ip_defttl; 518 if (path_mtu_discovery) 519 ip->ip_off |= IP_DF; 520 } 521 m->m_len = tlen; 522 m->m_pkthdr.len = tlen; 523 m->m_pkthdr.rcvif = NULL; 524 #ifdef MAC 525 if (inp != NULL) { 526 /* 527 * Packet is associated with a socket, so allow the 528 * label of the response to reflect the socket label. 529 */ 530 INP_LOCK_ASSERT(inp); 531 mac_create_mbuf_from_inpcb(inp, m); 532 } else { 533 /* 534 * Packet is not associated with a socket, so possibly 535 * update the label in place. 536 */ 537 mac_reflect_mbuf_tcp(m); 538 } 539 #endif 540 nth->th_seq = htonl(seq); 541 nth->th_ack = htonl(ack); 542 nth->th_x2 = 0; 543 nth->th_off = sizeof (struct tcphdr) >> 2; 544 nth->th_flags = flags; 545 if (tp != NULL) 546 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 547 else 548 nth->th_win = htons((u_short)win); 549 nth->th_urp = 0; 550 #ifdef INET6 551 if (isipv6) { 552 nth->th_sum = 0; 553 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 554 sizeof(struct ip6_hdr), 555 tlen - sizeof(struct ip6_hdr)); 556 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 557 NULL, NULL); 558 } else 559 #endif /* INET6 */ 560 { 561 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 562 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 563 m->m_pkthdr.csum_flags = CSUM_TCP; 564 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 565 } 566 #ifdef TCPDEBUG 567 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 568 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 569 #endif 570 #ifdef INET6 571 if (isipv6) 572 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 573 else 574 #endif /* INET6 */ 575 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 576 } 577 578 /* 579 * Create a new TCP control block, making an 580 * empty reassembly queue and hooking it to the argument 581 * protocol control block. The `inp' parameter must have 582 * come from the zone allocator set up in tcp_init(). 583 */ 584 struct tcpcb * 585 tcp_newtcpcb(inp) 586 struct inpcb *inp; 587 { 588 struct tcpcb_mem *tm; 589 struct tcpcb *tp; 590 #ifdef INET6 591 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 592 #endif /* INET6 */ 593 594 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 595 if (tm == NULL) 596 return (NULL); 597 tp = &tm->tcb; 598 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 599 tp->t_maxseg = tp->t_maxopd = 600 #ifdef INET6 601 isipv6 ? tcp_v6mssdflt : 602 #endif /* INET6 */ 603 tcp_mssdflt; 604 605 /* Set up our timeouts. */ 606 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, NET_CALLOUT_MPSAFE); 607 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, NET_CALLOUT_MPSAFE); 608 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, NET_CALLOUT_MPSAFE); 609 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, NET_CALLOUT_MPSAFE); 610 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, NET_CALLOUT_MPSAFE); 611 612 if (tcp_do_rfc1323) 613 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 614 tp->sack_enable = tcp_do_sack; 615 TAILQ_INIT(&tp->snd_holes); 616 tp->t_inpcb = inp; /* XXX */ 617 /* 618 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 619 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 620 * reasonable initial retransmit time. 621 */ 622 tp->t_srtt = TCPTV_SRTTBASE; 623 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 624 tp->t_rttmin = tcp_rexmit_min; 625 tp->t_rxtcur = TCPTV_RTOBASE; 626 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 627 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 628 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 629 tp->t_rcvtime = ticks; 630 tp->t_bw_rtttime = ticks; 631 /* 632 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 633 * because the socket may be bound to an IPv6 wildcard address, 634 * which may match an IPv4-mapped IPv6 address. 635 */ 636 inp->inp_ip_ttl = ip_defttl; 637 inp->inp_ppcb = (caddr_t)tp; 638 return (tp); /* XXX */ 639 } 640 641 /* 642 * Drop a TCP connection, reporting 643 * the specified error. If connection is synchronized, 644 * then send a RST to peer. 645 */ 646 struct tcpcb * 647 tcp_drop(tp, errno) 648 register struct tcpcb *tp; 649 int errno; 650 { 651 struct socket *so = tp->t_inpcb->inp_socket; 652 653 INP_INFO_WLOCK_ASSERT(&tcbinfo); 654 INP_LOCK_ASSERT(tp->t_inpcb); 655 656 if (TCPS_HAVERCVDSYN(tp->t_state)) { 657 tp->t_state = TCPS_CLOSED; 658 (void) tcp_output(tp); 659 tcpstat.tcps_drops++; 660 } else 661 tcpstat.tcps_conndrops++; 662 if (errno == ETIMEDOUT && tp->t_softerror) 663 errno = tp->t_softerror; 664 so->so_error = errno; 665 return (tcp_close(tp)); 666 } 667 668 static void 669 tcp_discardcb(tp) 670 struct tcpcb *tp; 671 { 672 struct tseg_qent *q; 673 struct inpcb *inp = tp->t_inpcb; 674 struct socket *so = inp->inp_socket; 675 #ifdef INET6 676 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 677 #endif /* INET6 */ 678 679 INP_LOCK_ASSERT(inp); 680 681 /* 682 * Make sure that all of our timers are stopped before we 683 * delete the PCB. 684 */ 685 callout_stop(tp->tt_rexmt); 686 callout_stop(tp->tt_persist); 687 callout_stop(tp->tt_keep); 688 callout_stop(tp->tt_2msl); 689 callout_stop(tp->tt_delack); 690 691 /* 692 * If we got enough samples through the srtt filter, 693 * save the rtt and rttvar in the routing entry. 694 * 'Enough' is arbitrarily defined as 4 rtt samples. 695 * 4 samples is enough for the srtt filter to converge 696 * to within enough % of the correct value; fewer samples 697 * and we could save a bogus rtt. The danger is not high 698 * as tcp quickly recovers from everything. 699 * XXX: Works very well but needs some more statistics! 700 */ 701 if (tp->t_rttupdated >= 4) { 702 struct hc_metrics_lite metrics; 703 u_long ssthresh; 704 705 bzero(&metrics, sizeof(metrics)); 706 /* 707 * Update the ssthresh always when the conditions below 708 * are satisfied. This gives us better new start value 709 * for the congestion avoidance for new connections. 710 * ssthresh is only set if packet loss occured on a session. 711 */ 712 ssthresh = tp->snd_ssthresh; 713 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 714 /* 715 * convert the limit from user data bytes to 716 * packets then to packet data bytes. 717 */ 718 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 719 if (ssthresh < 2) 720 ssthresh = 2; 721 ssthresh *= (u_long)(tp->t_maxseg + 722 #ifdef INET6 723 (isipv6 ? sizeof (struct ip6_hdr) + 724 sizeof (struct tcphdr) : 725 #endif 726 sizeof (struct tcpiphdr) 727 #ifdef INET6 728 ) 729 #endif 730 ); 731 } else 732 ssthresh = 0; 733 metrics.rmx_ssthresh = ssthresh; 734 735 metrics.rmx_rtt = tp->t_srtt; 736 metrics.rmx_rttvar = tp->t_rttvar; 737 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 738 metrics.rmx_bandwidth = tp->snd_bandwidth; 739 metrics.rmx_cwnd = tp->snd_cwnd; 740 metrics.rmx_sendpipe = 0; 741 metrics.rmx_recvpipe = 0; 742 743 tcp_hc_update(&inp->inp_inc, &metrics); 744 } 745 746 /* free the reassembly queue, if any */ 747 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 748 LIST_REMOVE(q, tqe_q); 749 m_freem(q->tqe_m); 750 uma_zfree(tcp_reass_zone, q); 751 tp->t_segqlen--; 752 tcp_reass_qsize--; 753 } 754 tcp_free_sackholes(tp); 755 inp->inp_ppcb = NULL; 756 tp->t_inpcb = NULL; 757 uma_zfree(tcpcb_zone, tp); 758 soisdisconnected(so); 759 } 760 761 /* 762 * Close a TCP control block: 763 * discard all space held by the tcp 764 * discard internet protocol block 765 * wake up any sleepers 766 */ 767 struct tcpcb * 768 tcp_close(tp) 769 struct tcpcb *tp; 770 { 771 struct inpcb *inp = tp->t_inpcb; 772 #ifdef INET6 773 struct socket *so = inp->inp_socket; 774 #endif 775 776 INP_INFO_WLOCK_ASSERT(&tcbinfo); 777 INP_LOCK_ASSERT(inp); 778 779 tcp_discardcb(tp); 780 #ifdef INET6 781 if (INP_CHECK_SOCKAF(so, AF_INET6)) 782 in6_pcbdetach(inp); 783 else 784 #endif 785 in_pcbdetach(inp); 786 tcpstat.tcps_closed++; 787 return (NULL); 788 } 789 790 void 791 tcp_drain() 792 { 793 if (do_tcpdrain) 794 { 795 struct inpcb *inpb; 796 struct tcpcb *tcpb; 797 struct tseg_qent *te; 798 799 /* 800 * Walk the tcpbs, if existing, and flush the reassembly queue, 801 * if there is one... 802 * XXX: The "Net/3" implementation doesn't imply that the TCP 803 * reassembly queue should be flushed, but in a situation 804 * where we're really low on mbufs, this is potentially 805 * usefull. 806 */ 807 INP_INFO_RLOCK(&tcbinfo); 808 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 809 if (inpb->inp_vflag & INP_TIMEWAIT) 810 continue; 811 INP_LOCK(inpb); 812 if ((tcpb = intotcpcb(inpb)) != NULL) { 813 while ((te = LIST_FIRST(&tcpb->t_segq)) 814 != NULL) { 815 LIST_REMOVE(te, tqe_q); 816 m_freem(te->tqe_m); 817 uma_zfree(tcp_reass_zone, te); 818 tcpb->t_segqlen--; 819 tcp_reass_qsize--; 820 } 821 tcp_clean_sackreport(tcpb); 822 } 823 INP_UNLOCK(inpb); 824 } 825 INP_INFO_RUNLOCK(&tcbinfo); 826 } 827 } 828 829 /* 830 * Notify a tcp user of an asynchronous error; 831 * store error as soft error, but wake up user 832 * (for now, won't do anything until can select for soft error). 833 * 834 * Do not wake up user since there currently is no mechanism for 835 * reporting soft errors (yet - a kqueue filter may be added). 836 */ 837 static struct inpcb * 838 tcp_notify(inp, error) 839 struct inpcb *inp; 840 int error; 841 { 842 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 843 844 INP_INFO_WLOCK_ASSERT(&tcbinfo); 845 INP_LOCK_ASSERT(inp); 846 847 /* 848 * Ignore some errors if we are hooked up. 849 * If connection hasn't completed, has retransmitted several times, 850 * and receives a second error, give up now. This is better 851 * than waiting a long time to establish a connection that 852 * can never complete. 853 */ 854 if (tp->t_state == TCPS_ESTABLISHED && 855 (error == EHOSTUNREACH || error == ENETUNREACH || 856 error == EHOSTDOWN)) { 857 return (inp); 858 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 859 tp->t_softerror) { 860 tcp_drop(tp, error); 861 return (struct inpcb *)0; 862 } else { 863 tp->t_softerror = error; 864 return (inp); 865 } 866 #if 0 867 wakeup( &so->so_timeo); 868 sorwakeup(so); 869 sowwakeup(so); 870 #endif 871 } 872 873 static int 874 tcp_pcblist(SYSCTL_HANDLER_ARGS) 875 { 876 int error, i, n; 877 struct inpcb *inp, **inp_list; 878 inp_gen_t gencnt; 879 struct xinpgen xig; 880 881 /* 882 * The process of preparing the TCB list is too time-consuming and 883 * resource-intensive to repeat twice on every request. 884 */ 885 if (req->oldptr == NULL) { 886 n = tcbinfo.ipi_count; 887 req->oldidx = 2 * (sizeof xig) 888 + (n + n/8) * sizeof(struct xtcpcb); 889 return (0); 890 } 891 892 if (req->newptr != NULL) 893 return (EPERM); 894 895 /* 896 * OK, now we're committed to doing something. 897 */ 898 INP_INFO_RLOCK(&tcbinfo); 899 gencnt = tcbinfo.ipi_gencnt; 900 n = tcbinfo.ipi_count; 901 INP_INFO_RUNLOCK(&tcbinfo); 902 903 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 904 + n * sizeof(struct xtcpcb)); 905 if (error != 0) 906 return (error); 907 908 xig.xig_len = sizeof xig; 909 xig.xig_count = n; 910 xig.xig_gen = gencnt; 911 xig.xig_sogen = so_gencnt; 912 error = SYSCTL_OUT(req, &xig, sizeof xig); 913 if (error) 914 return (error); 915 916 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 917 if (inp_list == NULL) 918 return (ENOMEM); 919 920 INP_INFO_RLOCK(&tcbinfo); 921 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 922 inp = LIST_NEXT(inp, inp_list)) { 923 INP_LOCK(inp); 924 if (inp->inp_gencnt <= gencnt) { 925 /* 926 * XXX: This use of cr_cansee(), introduced with 927 * TCP state changes, is not quite right, but for 928 * now, better than nothing. 929 */ 930 if (inp->inp_vflag & INP_TIMEWAIT) 931 error = cr_cansee(req->td->td_ucred, 932 intotw(inp)->tw_cred); 933 else 934 error = cr_canseesocket(req->td->td_ucred, 935 inp->inp_socket); 936 if (error == 0) 937 inp_list[i++] = inp; 938 } 939 INP_UNLOCK(inp); 940 } 941 INP_INFO_RUNLOCK(&tcbinfo); 942 n = i; 943 944 error = 0; 945 for (i = 0; i < n; i++) { 946 inp = inp_list[i]; 947 if (inp->inp_gencnt <= gencnt) { 948 struct xtcpcb xt; 949 caddr_t inp_ppcb; 950 951 bzero(&xt, sizeof(xt)); 952 xt.xt_len = sizeof xt; 953 /* XXX should avoid extra copy */ 954 bcopy(inp, &xt.xt_inp, sizeof *inp); 955 inp_ppcb = inp->inp_ppcb; 956 if (inp_ppcb == NULL) 957 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 958 else if (inp->inp_vflag & INP_TIMEWAIT) { 959 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 960 xt.xt_tp.t_state = TCPS_TIME_WAIT; 961 } else 962 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 963 if (inp->inp_socket != NULL) 964 sotoxsocket(inp->inp_socket, &xt.xt_socket); 965 else { 966 bzero(&xt.xt_socket, sizeof xt.xt_socket); 967 xt.xt_socket.xso_protocol = IPPROTO_TCP; 968 } 969 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 970 error = SYSCTL_OUT(req, &xt, sizeof xt); 971 } 972 } 973 if (!error) { 974 /* 975 * Give the user an updated idea of our state. 976 * If the generation differs from what we told 977 * her before, she knows that something happened 978 * while we were processing this request, and it 979 * might be necessary to retry. 980 */ 981 INP_INFO_RLOCK(&tcbinfo); 982 xig.xig_gen = tcbinfo.ipi_gencnt; 983 xig.xig_sogen = so_gencnt; 984 xig.xig_count = tcbinfo.ipi_count; 985 INP_INFO_RUNLOCK(&tcbinfo); 986 error = SYSCTL_OUT(req, &xig, sizeof xig); 987 } 988 free(inp_list, M_TEMP); 989 return (error); 990 } 991 992 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 993 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 994 995 static int 996 tcp_getcred(SYSCTL_HANDLER_ARGS) 997 { 998 struct xucred xuc; 999 struct sockaddr_in addrs[2]; 1000 struct inpcb *inp; 1001 int error; 1002 1003 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1004 if (error) 1005 return (error); 1006 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1007 if (error) 1008 return (error); 1009 INP_INFO_RLOCK(&tcbinfo); 1010 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1011 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1012 if (inp == NULL) { 1013 error = ENOENT; 1014 goto outunlocked; 1015 } 1016 INP_LOCK(inp); 1017 if (inp->inp_socket == NULL) { 1018 error = ENOENT; 1019 goto out; 1020 } 1021 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1022 if (error) 1023 goto out; 1024 cru2x(inp->inp_socket->so_cred, &xuc); 1025 out: 1026 INP_UNLOCK(inp); 1027 outunlocked: 1028 INP_INFO_RUNLOCK(&tcbinfo); 1029 if (error == 0) 1030 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1031 return (error); 1032 } 1033 1034 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1035 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1036 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1037 1038 #ifdef INET6 1039 static int 1040 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1041 { 1042 struct xucred xuc; 1043 struct sockaddr_in6 addrs[2]; 1044 struct inpcb *inp; 1045 int error, mapped = 0; 1046 1047 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1048 if (error) 1049 return (error); 1050 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1051 if (error) 1052 return (error); 1053 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1054 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1055 return (error); 1056 } 1057 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1058 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1059 mapped = 1; 1060 else 1061 return (EINVAL); 1062 } 1063 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, 1074 &addrs[1].sin6_addr, addrs[1].sin6_port, 1075 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1076 if (inp == NULL) { 1077 error = ENOENT; 1078 goto outunlocked; 1079 } 1080 INP_LOCK(inp); 1081 if (inp->inp_socket == NULL) { 1082 error = ENOENT; 1083 goto out; 1084 } 1085 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1086 if (error) 1087 goto out; 1088 cru2x(inp->inp_socket->so_cred, &xuc); 1089 out: 1090 INP_UNLOCK(inp); 1091 outunlocked: 1092 INP_INFO_RUNLOCK(&tcbinfo); 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; 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 icp = (struct icmp *)((caddr_t)ip 1151 - offsetof(struct icmp, icmp_ip)); 1152 th = (struct tcphdr *)((caddr_t)ip 1153 + (ip->ip_hl << 2)); 1154 INP_INFO_WLOCK(&tcbinfo); 1155 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1156 ip->ip_src, th->th_sport, 0, NULL); 1157 if (inp != NULL) { 1158 INP_LOCK(inp); 1159 if (inp->inp_socket != NULL) { 1160 icmp_tcp_seq = htonl(th->th_seq); 1161 tp = intotcpcb(inp); 1162 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1163 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1164 if (cmd == PRC_MSGSIZE) { 1165 /* 1166 * MTU discovery: 1167 * If we got a needfrag set the MTU 1168 * in the route to the suggested new 1169 * value (if given) and then notify. 1170 */ 1171 bzero(&inc, sizeof(inc)); 1172 inc.inc_flags = 0; /* IPv4 */ 1173 inc.inc_faddr = faddr; 1174 1175 mtu = ntohs(icp->icmp_nextmtu); 1176 /* 1177 * If no alternative MTU was 1178 * proposed, try the next smaller 1179 * one. ip->ip_len has already 1180 * been swapped in icmp_input(). 1181 */ 1182 if (!mtu) 1183 mtu = ip_next_mtu(ip->ip_len, 1184 1); 1185 if (mtu < max(296, (tcp_minmss) 1186 + sizeof(struct tcpiphdr))) 1187 mtu = 0; 1188 if (!mtu) 1189 mtu = tcp_mssdflt 1190 + sizeof(struct tcpiphdr); 1191 /* 1192 * Only cache the the MTU if it 1193 * is smaller than the interface 1194 * or route MTU. tcp_mtudisc() 1195 * will do right thing by itself. 1196 */ 1197 if (mtu <= tcp_maxmtu(&inc)) 1198 tcp_hc_updatemtu(&inc, mtu); 1199 } 1200 1201 inp = (*notify)(inp, inetctlerrmap[cmd]); 1202 } 1203 } 1204 if (inp != NULL) 1205 INP_UNLOCK(inp); 1206 } else { 1207 inc.inc_fport = th->th_dport; 1208 inc.inc_lport = th->th_sport; 1209 inc.inc_faddr = faddr; 1210 inc.inc_laddr = ip->ip_src; 1211 #ifdef INET6 1212 inc.inc_isipv6 = 0; 1213 #endif 1214 syncache_unreach(&inc, th); 1215 } 1216 INP_INFO_WUNLOCK(&tcbinfo); 1217 } else 1218 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1219 } 1220 1221 #ifdef INET6 1222 void 1223 tcp6_ctlinput(cmd, sa, d) 1224 int cmd; 1225 struct sockaddr *sa; 1226 void *d; 1227 { 1228 struct tcphdr th; 1229 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1230 struct ip6_hdr *ip6; 1231 struct mbuf *m; 1232 struct ip6ctlparam *ip6cp = NULL; 1233 const struct sockaddr_in6 *sa6_src = NULL; 1234 int off; 1235 struct tcp_portonly { 1236 u_int16_t th_sport; 1237 u_int16_t th_dport; 1238 } *thp; 1239 1240 if (sa->sa_family != AF_INET6 || 1241 sa->sa_len != sizeof(struct sockaddr_in6)) 1242 return; 1243 1244 if (cmd == PRC_MSGSIZE) 1245 notify = tcp_mtudisc; 1246 else if (!PRC_IS_REDIRECT(cmd) && 1247 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1248 return; 1249 /* Source quench is depreciated. */ 1250 else if (cmd == PRC_QUENCH) 1251 return; 1252 1253 /* if the parameter is from icmp6, decode it. */ 1254 if (d != NULL) { 1255 ip6cp = (struct ip6ctlparam *)d; 1256 m = ip6cp->ip6c_m; 1257 ip6 = ip6cp->ip6c_ip6; 1258 off = ip6cp->ip6c_off; 1259 sa6_src = ip6cp->ip6c_src; 1260 } else { 1261 m = NULL; 1262 ip6 = NULL; 1263 off = 0; /* fool gcc */ 1264 sa6_src = &sa6_any; 1265 } 1266 1267 if (ip6 != NULL) { 1268 struct in_conninfo inc; 1269 /* 1270 * XXX: We assume that when IPV6 is non NULL, 1271 * M and OFF are valid. 1272 */ 1273 1274 /* check if we can safely examine src and dst ports */ 1275 if (m->m_pkthdr.len < off + sizeof(*thp)) 1276 return; 1277 1278 bzero(&th, sizeof(th)); 1279 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1280 1281 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1282 (struct sockaddr *)ip6cp->ip6c_src, 1283 th.th_sport, cmd, NULL, notify); 1284 1285 inc.inc_fport = th.th_dport; 1286 inc.inc_lport = th.th_sport; 1287 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1288 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1289 inc.inc_isipv6 = 1; 1290 INP_INFO_WLOCK(&tcbinfo); 1291 syncache_unreach(&inc, &th); 1292 INP_INFO_WUNLOCK(&tcbinfo); 1293 } else 1294 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1295 0, cmd, NULL, notify); 1296 } 1297 #endif /* INET6 */ 1298 1299 1300 /* 1301 * Following is where TCP initial sequence number generation occurs. 1302 * 1303 * There are two places where we must use initial sequence numbers: 1304 * 1. In SYN-ACK packets. 1305 * 2. In SYN packets. 1306 * 1307 * All ISNs for SYN-ACK packets are generated by the syncache. See 1308 * tcp_syncache.c for details. 1309 * 1310 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1311 * depends on this property. In addition, these ISNs should be 1312 * unguessable so as to prevent connection hijacking. To satisfy 1313 * the requirements of this situation, the algorithm outlined in 1314 * RFC 1948 is used, with only small modifications. 1315 * 1316 * Implementation details: 1317 * 1318 * Time is based off the system timer, and is corrected so that it 1319 * increases by one megabyte per second. This allows for proper 1320 * recycling on high speed LANs while still leaving over an hour 1321 * before rollover. 1322 * 1323 * As reading the *exact* system time is too expensive to be done 1324 * whenever setting up a TCP connection, we increment the time 1325 * offset in two ways. First, a small random positive increment 1326 * is added to isn_offset for each connection that is set up. 1327 * Second, the function tcp_isn_tick fires once per clock tick 1328 * and increments isn_offset as necessary so that sequence numbers 1329 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1330 * random positive increments serve only to ensure that the same 1331 * exact sequence number is never sent out twice (as could otherwise 1332 * happen when a port is recycled in less than the system tick 1333 * interval.) 1334 * 1335 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1336 * between seeding of isn_secret. This is normally set to zero, 1337 * as reseeding should not be necessary. 1338 * 1339 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1340 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1341 * general, this means holding an exclusive (write) lock. 1342 */ 1343 1344 #define ISN_BYTES_PER_SECOND 1048576 1345 #define ISN_STATIC_INCREMENT 4096 1346 #define ISN_RANDOM_INCREMENT (4096 - 1) 1347 1348 static u_char isn_secret[32]; 1349 static int isn_last_reseed; 1350 static u_int32_t isn_offset, isn_offset_old; 1351 static MD5_CTX isn_ctx; 1352 1353 tcp_seq 1354 tcp_new_isn(tp) 1355 struct tcpcb *tp; 1356 { 1357 u_int32_t md5_buffer[4]; 1358 tcp_seq new_isn; 1359 1360 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1361 INP_LOCK_ASSERT(tp->t_inpcb); 1362 1363 /* Seed if this is the first use, reseed if requested. */ 1364 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1365 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1366 < (u_int)ticks))) { 1367 read_random(&isn_secret, sizeof(isn_secret)); 1368 isn_last_reseed = ticks; 1369 } 1370 1371 /* Compute the md5 hash and return the ISN. */ 1372 MD5Init(&isn_ctx); 1373 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1374 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1375 #ifdef INET6 1376 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1377 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1378 sizeof(struct in6_addr)); 1379 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1380 sizeof(struct in6_addr)); 1381 } else 1382 #endif 1383 { 1384 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1385 sizeof(struct in_addr)); 1386 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1387 sizeof(struct in_addr)); 1388 } 1389 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1390 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1391 new_isn = (tcp_seq) md5_buffer[0]; 1392 isn_offset += ISN_STATIC_INCREMENT + 1393 (arc4random() & ISN_RANDOM_INCREMENT); 1394 new_isn += isn_offset; 1395 return (new_isn); 1396 } 1397 1398 /* 1399 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1400 * to keep time flowing at a relatively constant rate. If the random 1401 * increments have already pushed us past the projected offset, do nothing. 1402 */ 1403 static void 1404 tcp_isn_tick(xtp) 1405 void *xtp; 1406 { 1407 u_int32_t projected_offset; 1408 1409 INP_INFO_WLOCK(&tcbinfo); 1410 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1411 1412 if (projected_offset > isn_offset) 1413 isn_offset = projected_offset; 1414 1415 isn_offset_old = isn_offset; 1416 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1417 INP_INFO_WUNLOCK(&tcbinfo); 1418 } 1419 1420 /* 1421 * When a specific ICMP unreachable message is received and the 1422 * connection state is SYN-SENT, drop the connection. This behavior 1423 * is controlled by the icmp_may_rst sysctl. 1424 */ 1425 struct inpcb * 1426 tcp_drop_syn_sent(inp, errno) 1427 struct inpcb *inp; 1428 int errno; 1429 { 1430 struct tcpcb *tp = intotcpcb(inp); 1431 1432 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1433 INP_LOCK_ASSERT(inp); 1434 1435 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1436 tcp_drop(tp, errno); 1437 return (NULL); 1438 } 1439 return (inp); 1440 } 1441 1442 /* 1443 * When `need fragmentation' ICMP is received, update our idea of the MSS 1444 * based on the new value in the route. Also nudge TCP to send something, 1445 * since we know the packet we just sent was dropped. 1446 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1447 */ 1448 struct inpcb * 1449 tcp_mtudisc(inp, errno) 1450 struct inpcb *inp; 1451 int errno; 1452 { 1453 struct tcpcb *tp = intotcpcb(inp); 1454 struct socket *so = inp->inp_socket; 1455 u_int maxmtu; 1456 u_int romtu; 1457 int mss; 1458 #ifdef INET6 1459 int isipv6; 1460 #endif /* INET6 */ 1461 1462 INP_LOCK_ASSERT(inp); 1463 if (tp != NULL) { 1464 #ifdef INET6 1465 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1466 #endif 1467 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1468 romtu = 1469 #ifdef INET6 1470 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1471 #endif /* INET6 */ 1472 tcp_maxmtu(&inp->inp_inc); 1473 if (!maxmtu) 1474 maxmtu = romtu; 1475 else 1476 maxmtu = min(maxmtu, romtu); 1477 if (!maxmtu) { 1478 tp->t_maxopd = tp->t_maxseg = 1479 #ifdef INET6 1480 isipv6 ? tcp_v6mssdflt : 1481 #endif /* INET6 */ 1482 tcp_mssdflt; 1483 return (inp); 1484 } 1485 mss = maxmtu - 1486 #ifdef INET6 1487 (isipv6 ? 1488 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1489 #endif /* INET6 */ 1490 sizeof(struct tcpiphdr) 1491 #ifdef INET6 1492 ) 1493 #endif /* INET6 */ 1494 ; 1495 1496 /* 1497 * XXX - The above conditional probably violates the TCP 1498 * spec. The problem is that, since we don't know the 1499 * other end's MSS, we are supposed to use a conservative 1500 * default. But, if we do that, then MTU discovery will 1501 * never actually take place, because the conservative 1502 * default is much less than the MTUs typically seen 1503 * on the Internet today. For the moment, we'll sweep 1504 * this under the carpet. 1505 * 1506 * The conservative default might not actually be a problem 1507 * if the only case this occurs is when sending an initial 1508 * SYN with options and data to a host we've never talked 1509 * to before. Then, they will reply with an MSS value which 1510 * will get recorded and the new parameters should get 1511 * recomputed. For Further Study. 1512 */ 1513 if (tp->t_maxopd <= mss) 1514 return (inp); 1515 tp->t_maxopd = mss; 1516 1517 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1518 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1519 mss -= TCPOLEN_TSTAMP_APPA; 1520 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1521 if (mss > MCLBYTES) 1522 mss &= ~(MCLBYTES-1); 1523 #else 1524 if (mss > MCLBYTES) 1525 mss = mss / MCLBYTES * MCLBYTES; 1526 #endif 1527 if (so->so_snd.sb_hiwat < mss) 1528 mss = so->so_snd.sb_hiwat; 1529 1530 tp->t_maxseg = mss; 1531 1532 tcpstat.tcps_mturesent++; 1533 tp->t_rtttime = 0; 1534 tp->snd_nxt = tp->snd_una; 1535 tcp_output(tp); 1536 } 1537 return (inp); 1538 } 1539 1540 /* 1541 * Look-up the routing entry to the peer of this inpcb. If no route 1542 * is found and it cannot be allocated, then return NULL. This routine 1543 * is called by TCP routines that access the rmx structure and by tcp_mss 1544 * to get the interface MTU. 1545 */ 1546 u_long 1547 tcp_maxmtu(inc) 1548 struct in_conninfo *inc; 1549 { 1550 struct route sro; 1551 struct sockaddr_in *dst; 1552 struct ifnet *ifp; 1553 u_long maxmtu = 0; 1554 1555 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1556 1557 bzero(&sro, sizeof(sro)); 1558 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1559 dst = (struct sockaddr_in *)&sro.ro_dst; 1560 dst->sin_family = AF_INET; 1561 dst->sin_len = sizeof(*dst); 1562 dst->sin_addr = inc->inc_faddr; 1563 rtalloc_ign(&sro, RTF_CLONING); 1564 } 1565 if (sro.ro_rt != NULL) { 1566 ifp = sro.ro_rt->rt_ifp; 1567 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1568 maxmtu = ifp->if_mtu; 1569 else 1570 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1571 RTFREE(sro.ro_rt); 1572 } 1573 return (maxmtu); 1574 } 1575 1576 #ifdef INET6 1577 u_long 1578 tcp_maxmtu6(inc) 1579 struct in_conninfo *inc; 1580 { 1581 struct route_in6 sro6; 1582 struct ifnet *ifp; 1583 u_long maxmtu = 0; 1584 1585 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1586 1587 bzero(&sro6, sizeof(sro6)); 1588 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1589 sro6.ro_dst.sin6_family = AF_INET6; 1590 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1591 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1592 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1593 } 1594 if (sro6.ro_rt != NULL) { 1595 ifp = sro6.ro_rt->rt_ifp; 1596 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1597 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1598 else 1599 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1600 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1601 RTFREE(sro6.ro_rt); 1602 } 1603 1604 return (maxmtu); 1605 } 1606 #endif /* INET6 */ 1607 1608 #ifdef IPSEC 1609 /* compute ESP/AH header size for TCP, including outer IP header. */ 1610 size_t 1611 ipsec_hdrsiz_tcp(tp) 1612 struct tcpcb *tp; 1613 { 1614 struct inpcb *inp; 1615 struct mbuf *m; 1616 size_t hdrsiz; 1617 struct ip *ip; 1618 #ifdef INET6 1619 struct ip6_hdr *ip6; 1620 #endif 1621 struct tcphdr *th; 1622 1623 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1624 return (0); 1625 MGETHDR(m, M_DONTWAIT, MT_DATA); 1626 if (!m) 1627 return (0); 1628 1629 #ifdef INET6 1630 if ((inp->inp_vflag & INP_IPV6) != 0) { 1631 ip6 = mtod(m, struct ip6_hdr *); 1632 th = (struct tcphdr *)(ip6 + 1); 1633 m->m_pkthdr.len = m->m_len = 1634 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1635 tcpip_fillheaders(inp, ip6, th); 1636 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1637 } else 1638 #endif /* INET6 */ 1639 { 1640 ip = mtod(m, struct ip *); 1641 th = (struct tcphdr *)(ip + 1); 1642 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1643 tcpip_fillheaders(inp, ip, th); 1644 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1645 } 1646 1647 m_free(m); 1648 return (hdrsiz); 1649 } 1650 #endif /*IPSEC*/ 1651 1652 /* 1653 * Move a TCP connection into TIME_WAIT state. 1654 * tcbinfo is locked. 1655 * inp is locked, and is unlocked before returning. 1656 */ 1657 void 1658 tcp_twstart(tp) 1659 struct tcpcb *tp; 1660 { 1661 struct tcptw *tw; 1662 struct inpcb *inp; 1663 int tw_time, acknow; 1664 struct socket *so; 1665 1666 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1667 INP_LOCK_ASSERT(tp->t_inpcb); 1668 1669 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1670 if (tw == NULL) { 1671 tw = tcp_timer_2msl_tw(1); 1672 if (tw == NULL) { 1673 tcp_close(tp); 1674 return; 1675 } 1676 } 1677 inp = tp->t_inpcb; 1678 tw->tw_inpcb = inp; 1679 1680 /* 1681 * Recover last window size sent. 1682 */ 1683 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1684 1685 /* 1686 * Set t_recent if timestamps are used on the connection. 1687 */ 1688 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1689 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1690 tw->t_recent = tp->ts_recent; 1691 else 1692 tw->t_recent = 0; 1693 1694 tw->snd_nxt = tp->snd_nxt; 1695 tw->rcv_nxt = tp->rcv_nxt; 1696 tw->iss = tp->iss; 1697 tw->irs = tp->irs; 1698 tw->t_starttime = tp->t_starttime; 1699 tw->tw_time = 0; 1700 1701 /* XXX 1702 * If this code will 1703 * be used for fin-wait-2 state also, then we may need 1704 * a ts_recent from the last segment. 1705 */ 1706 tw_time = 2 * tcp_msl; 1707 acknow = tp->t_flags & TF_ACKNOW; 1708 tcp_discardcb(tp); 1709 so = inp->inp_socket; 1710 ACCEPT_LOCK(); 1711 SOCK_LOCK(so); 1712 so->so_pcb = NULL; 1713 tw->tw_cred = crhold(so->so_cred); 1714 tw->tw_so_options = so->so_options; 1715 sotryfree(so); 1716 inp->inp_socket = NULL; 1717 if (acknow) 1718 tcp_twrespond(tw, TH_ACK); 1719 inp->inp_ppcb = (caddr_t)tw; 1720 inp->inp_vflag |= INP_TIMEWAIT; 1721 tcp_timer_2msl_reset(tw, tw_time); 1722 INP_UNLOCK(inp); 1723 } 1724 1725 /* 1726 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1727 * the actual rate is slightly higher due to the addition of 1728 * random positive increments. 1729 * 1730 * Most other new OSes use semi-randomized ISN values, so we 1731 * do not need to worry about them. 1732 */ 1733 #define MS_ISN_BYTES_PER_SECOND 250000 1734 1735 /* 1736 * Determine if the ISN we will generate has advanced beyond the last 1737 * sequence number used by the previous connection. If so, indicate 1738 * that it is safe to recycle this tw socket by returning 1. 1739 * 1740 * XXXRW: This function should assert the inpcb lock as it does multiple 1741 * non-atomic reads from the tcptw, but is currently called without it from 1742 * in_pcb.c:in_pcblookup_local(). 1743 */ 1744 int 1745 tcp_twrecycleable(struct tcptw *tw) 1746 { 1747 tcp_seq new_iss = tw->iss; 1748 tcp_seq new_irs = tw->irs; 1749 1750 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1751 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1752 1753 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1754 return (1); 1755 else 1756 return (0); 1757 } 1758 1759 struct tcptw * 1760 tcp_twclose(struct tcptw *tw, int reuse) 1761 { 1762 struct inpcb *inp; 1763 1764 inp = tw->tw_inpcb; 1765 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1766 INP_LOCK_ASSERT(inp); 1767 1768 tw->tw_inpcb = NULL; 1769 tcp_timer_2msl_stop(tw); 1770 inp->inp_ppcb = NULL; 1771 #ifdef INET6 1772 if (inp->inp_vflag & INP_IPV6PROTO) 1773 in6_pcbdetach(inp); 1774 else 1775 #endif 1776 in_pcbdetach(inp); 1777 tcpstat.tcps_closed++; 1778 crfree(tw->tw_cred); 1779 tw->tw_cred = NULL; 1780 if (reuse) 1781 return (tw); 1782 uma_zfree(tcptw_zone, tw); 1783 return (NULL); 1784 } 1785 1786 int 1787 tcp_twrespond(struct tcptw *tw, int flags) 1788 { 1789 struct inpcb *inp = tw->tw_inpcb; 1790 struct tcphdr *th; 1791 struct mbuf *m; 1792 struct ip *ip = NULL; 1793 u_int8_t *optp; 1794 u_int hdrlen, optlen; 1795 int error; 1796 #ifdef INET6 1797 struct ip6_hdr *ip6 = NULL; 1798 int isipv6 = inp->inp_inc.inc_isipv6; 1799 #endif 1800 1801 INP_LOCK_ASSERT(inp); 1802 1803 m = m_gethdr(M_DONTWAIT, MT_DATA); 1804 if (m == NULL) 1805 return (ENOBUFS); 1806 m->m_data += max_linkhdr; 1807 1808 #ifdef MAC 1809 mac_create_mbuf_from_inpcb(inp, m); 1810 #endif 1811 1812 #ifdef INET6 1813 if (isipv6) { 1814 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1815 ip6 = mtod(m, struct ip6_hdr *); 1816 th = (struct tcphdr *)(ip6 + 1); 1817 tcpip_fillheaders(inp, ip6, th); 1818 } else 1819 #endif 1820 { 1821 hdrlen = sizeof(struct tcpiphdr); 1822 ip = mtod(m, struct ip *); 1823 th = (struct tcphdr *)(ip + 1); 1824 tcpip_fillheaders(inp, ip, th); 1825 } 1826 optp = (u_int8_t *)(th + 1); 1827 1828 /* 1829 * Send a timestamp and echo-reply if both our side and our peer 1830 * have sent timestamps in our SYN's and this is not a RST. 1831 */ 1832 if (tw->t_recent && flags == TH_ACK) { 1833 u_int32_t *lp = (u_int32_t *)optp; 1834 1835 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1836 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1837 *lp++ = htonl(ticks); 1838 *lp = htonl(tw->t_recent); 1839 optp += TCPOLEN_TSTAMP_APPA; 1840 } 1841 1842 optlen = optp - (u_int8_t *)(th + 1); 1843 1844 m->m_len = hdrlen + optlen; 1845 m->m_pkthdr.len = m->m_len; 1846 1847 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1848 1849 th->th_seq = htonl(tw->snd_nxt); 1850 th->th_ack = htonl(tw->rcv_nxt); 1851 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1852 th->th_flags = flags; 1853 th->th_win = htons(tw->last_win); 1854 1855 #ifdef INET6 1856 if (isipv6) { 1857 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1858 sizeof(struct tcphdr) + optlen); 1859 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1860 error = ip6_output(m, inp->in6p_outputopts, NULL, 1861 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1862 } else 1863 #endif 1864 { 1865 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1866 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1867 m->m_pkthdr.csum_flags = CSUM_TCP; 1868 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1869 ip->ip_len = m->m_pkthdr.len; 1870 if (path_mtu_discovery) 1871 ip->ip_off |= IP_DF; 1872 error = ip_output(m, inp->inp_options, NULL, 1873 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1874 NULL, inp); 1875 } 1876 if (flags & TH_ACK) 1877 tcpstat.tcps_sndacks++; 1878 else 1879 tcpstat.tcps_sndctrl++; 1880 tcpstat.tcps_sndtotal++; 1881 return (error); 1882 } 1883 1884 /* 1885 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1886 * 1887 * This code attempts to calculate the bandwidth-delay product as a 1888 * means of determining the optimal window size to maximize bandwidth, 1889 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1890 * routers. This code also does a fairly good job keeping RTTs in check 1891 * across slow links like modems. We implement an algorithm which is very 1892 * similar (but not meant to be) TCP/Vegas. The code operates on the 1893 * transmitter side of a TCP connection and so only effects the transmit 1894 * side of the connection. 1895 * 1896 * BACKGROUND: TCP makes no provision for the management of buffer space 1897 * at the end points or at the intermediate routers and switches. A TCP 1898 * stream, whether using NewReno or not, will eventually buffer as 1899 * many packets as it is able and the only reason this typically works is 1900 * due to the fairly small default buffers made available for a connection 1901 * (typicaly 16K or 32K). As machines use larger windows and/or window 1902 * scaling it is now fairly easy for even a single TCP connection to blow-out 1903 * all available buffer space not only on the local interface, but on 1904 * intermediate routers and switches as well. NewReno makes a misguided 1905 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1906 * then backing off, then steadily increasing the window again until another 1907 * failure occurs, ad-infinitum. This results in terrible oscillation that 1908 * is only made worse as network loads increase and the idea of intentionally 1909 * blowing out network buffers is, frankly, a terrible way to manage network 1910 * resources. 1911 * 1912 * It is far better to limit the transmit window prior to the failure 1913 * condition being achieved. There are two general ways to do this: First 1914 * you can 'scan' through different transmit window sizes and locate the 1915 * point where the RTT stops increasing, indicating that you have filled the 1916 * pipe, then scan backwards until you note that RTT stops decreasing, then 1917 * repeat ad-infinitum. This method works in principle but has severe 1918 * implementation issues due to RTT variances, timer granularity, and 1919 * instability in the algorithm which can lead to many false positives and 1920 * create oscillations as well as interact badly with other TCP streams 1921 * implementing the same algorithm. 1922 * 1923 * The second method is to limit the window to the bandwidth delay product 1924 * of the link. This is the method we implement. RTT variances and our 1925 * own manipulation of the congestion window, bwnd, can potentially 1926 * destabilize the algorithm. For this reason we have to stabilize the 1927 * elements used to calculate the window. We do this by using the minimum 1928 * observed RTT, the long term average of the observed bandwidth, and 1929 * by adding two segments worth of slop. It isn't perfect but it is able 1930 * to react to changing conditions and gives us a very stable basis on 1931 * which to extend the algorithm. 1932 */ 1933 void 1934 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1935 { 1936 u_long bw; 1937 u_long bwnd; 1938 int save_ticks; 1939 1940 INP_LOCK_ASSERT(tp->t_inpcb); 1941 1942 /* 1943 * If inflight_enable is disabled in the middle of a tcp connection, 1944 * make sure snd_bwnd is effectively disabled. 1945 */ 1946 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 1947 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1948 tp->snd_bandwidth = 0; 1949 return; 1950 } 1951 1952 /* 1953 * Figure out the bandwidth. Due to the tick granularity this 1954 * is a very rough number and it MUST be averaged over a fairly 1955 * long period of time. XXX we need to take into account a link 1956 * that is not using all available bandwidth, but for now our 1957 * slop will ramp us up if this case occurs and the bandwidth later 1958 * increases. 1959 * 1960 * Note: if ticks rollover 'bw' may wind up negative. We must 1961 * effectively reset t_bw_rtttime for this case. 1962 */ 1963 save_ticks = ticks; 1964 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1965 return; 1966 1967 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1968 (save_ticks - tp->t_bw_rtttime); 1969 tp->t_bw_rtttime = save_ticks; 1970 tp->t_bw_rtseq = ack_seq; 1971 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1972 return; 1973 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1974 1975 tp->snd_bandwidth = bw; 1976 1977 /* 1978 * Calculate the semi-static bandwidth delay product, plus two maximal 1979 * segments. The additional slop puts us squarely in the sweet 1980 * spot and also handles the bandwidth run-up case and stabilization. 1981 * Without the slop we could be locking ourselves into a lower 1982 * bandwidth. 1983 * 1984 * Situations Handled: 1985 * (1) Prevents over-queueing of packets on LANs, especially on 1986 * high speed LANs, allowing larger TCP buffers to be 1987 * specified, and also does a good job preventing 1988 * over-queueing of packets over choke points like modems 1989 * (at least for the transmit side). 1990 * 1991 * (2) Is able to handle changing network loads (bandwidth 1992 * drops so bwnd drops, bandwidth increases so bwnd 1993 * increases). 1994 * 1995 * (3) Theoretically should stabilize in the face of multiple 1996 * connections implementing the same algorithm (this may need 1997 * a little work). 1998 * 1999 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2000 * be adjusted with a sysctl but typically only needs to be 2001 * on very slow connections. A value no smaller then 5 2002 * should be used, but only reduce this default if you have 2003 * no other choice. 2004 */ 2005 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2006 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2007 #undef USERTT 2008 2009 if (tcp_inflight_debug > 0) { 2010 static int ltime; 2011 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2012 ltime = ticks; 2013 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2014 tp, 2015 bw, 2016 tp->t_rttbest, 2017 tp->t_srtt, 2018 bwnd 2019 ); 2020 } 2021 } 2022 if ((long)bwnd < tcp_inflight_min) 2023 bwnd = tcp_inflight_min; 2024 if (bwnd > tcp_inflight_max) 2025 bwnd = tcp_inflight_max; 2026 if ((long)bwnd < tp->t_maxseg * 2) 2027 bwnd = tp->t_maxseg * 2; 2028 tp->snd_bwnd = bwnd; 2029 } 2030 2031 #ifdef TCP_SIGNATURE 2032 /* 2033 * Callback function invoked by m_apply() to digest TCP segment data 2034 * contained within an mbuf chain. 2035 */ 2036 static int 2037 tcp_signature_apply(void *fstate, void *data, u_int len) 2038 { 2039 2040 MD5Update(fstate, (u_char *)data, len); 2041 return (0); 2042 } 2043 2044 /* 2045 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2046 * 2047 * Parameters: 2048 * m pointer to head of mbuf chain 2049 * off0 offset to TCP header within the mbuf chain 2050 * len length of TCP segment data, excluding options 2051 * optlen length of TCP segment options 2052 * buf pointer to storage for computed MD5 digest 2053 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2054 * 2055 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2056 * When called from tcp_input(), we can be sure that th_sum has been 2057 * zeroed out and verified already. 2058 * 2059 * This function is for IPv4 use only. Calling this function with an 2060 * IPv6 packet in the mbuf chain will yield undefined results. 2061 * 2062 * Return 0 if successful, otherwise return -1. 2063 * 2064 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2065 * search with the destination IP address, and a 'magic SPI' to be 2066 * determined by the application. This is hardcoded elsewhere to 1179 2067 * right now. Another branch of this code exists which uses the SPD to 2068 * specify per-application flows but it is unstable. 2069 */ 2070 int 2071 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2072 u_char *buf, u_int direction) 2073 { 2074 union sockaddr_union dst; 2075 struct ippseudo ippseudo; 2076 MD5_CTX ctx; 2077 int doff; 2078 struct ip *ip; 2079 struct ipovly *ipovly; 2080 struct secasvar *sav; 2081 struct tcphdr *th; 2082 u_short savecsum; 2083 2084 KASSERT(m != NULL, ("NULL mbuf chain")); 2085 KASSERT(buf != NULL, ("NULL signature pointer")); 2086 2087 /* Extract the destination from the IP header in the mbuf. */ 2088 ip = mtod(m, struct ip *); 2089 bzero(&dst, sizeof(union sockaddr_union)); 2090 dst.sa.sa_len = sizeof(struct sockaddr_in); 2091 dst.sa.sa_family = AF_INET; 2092 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2093 ip->ip_src : ip->ip_dst; 2094 2095 /* Look up an SADB entry which matches the address of the peer. */ 2096 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2097 if (sav == NULL) { 2098 printf("%s: SADB lookup failed for %s\n", __func__, 2099 inet_ntoa(dst.sin.sin_addr)); 2100 return (EINVAL); 2101 } 2102 2103 MD5Init(&ctx); 2104 ipovly = (struct ipovly *)ip; 2105 th = (struct tcphdr *)((u_char *)ip + off0); 2106 doff = off0 + sizeof(struct tcphdr) + optlen; 2107 2108 /* 2109 * Step 1: Update MD5 hash with IP pseudo-header. 2110 * 2111 * XXX The ippseudo header MUST be digested in network byte order, 2112 * or else we'll fail the regression test. Assume all fields we've 2113 * been doing arithmetic on have been in host byte order. 2114 * XXX One cannot depend on ipovly->ih_len here. When called from 2115 * tcp_output(), the underlying ip_len member has not yet been set. 2116 */ 2117 ippseudo.ippseudo_src = ipovly->ih_src; 2118 ippseudo.ippseudo_dst = ipovly->ih_dst; 2119 ippseudo.ippseudo_pad = 0; 2120 ippseudo.ippseudo_p = IPPROTO_TCP; 2121 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2122 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2123 2124 /* 2125 * Step 2: Update MD5 hash with TCP header, excluding options. 2126 * The TCP checksum must be set to zero. 2127 */ 2128 savecsum = th->th_sum; 2129 th->th_sum = 0; 2130 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2131 th->th_sum = savecsum; 2132 2133 /* 2134 * Step 3: Update MD5 hash with TCP segment data. 2135 * Use m_apply() to avoid an early m_pullup(). 2136 */ 2137 if (len > 0) 2138 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2139 2140 /* 2141 * Step 4: Update MD5 hash with shared secret. 2142 */ 2143 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2144 MD5Final(buf, &ctx); 2145 2146 key_sa_recordxfer(sav, m); 2147 KEY_FREESAV(&sav); 2148 return (0); 2149 } 2150 #endif /* TCP_SIGNATURE */ 2151 2152 static int 2153 sysctl_drop(SYSCTL_HANDLER_ARGS) 2154 { 2155 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2156 struct sockaddr_storage addrs[2]; 2157 struct inpcb *inp; 2158 struct tcpcb *tp; 2159 struct tcptw *tw; 2160 struct sockaddr_in *fin, *lin; 2161 #ifdef INET6 2162 struct sockaddr_in6 *fin6, *lin6; 2163 struct in6_addr f6, l6; 2164 #endif 2165 int error; 2166 2167 inp = NULL; 2168 fin = lin = NULL; 2169 #ifdef INET6 2170 fin6 = lin6 = NULL; 2171 #endif 2172 error = 0; 2173 2174 if (req->oldptr != NULL || req->oldlen != 0) 2175 return (EINVAL); 2176 if (req->newptr == NULL) 2177 return (EPERM); 2178 if (req->newlen < sizeof(addrs)) 2179 return (ENOMEM); 2180 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2181 if (error) 2182 return (error); 2183 2184 switch (addrs[0].ss_family) { 2185 #ifdef INET6 2186 case AF_INET6: 2187 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2188 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2189 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2190 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2191 return (EINVAL); 2192 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2193 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2194 return (EINVAL); 2195 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2196 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2197 fin = (struct sockaddr_in *)&addrs[0]; 2198 lin = (struct sockaddr_in *)&addrs[1]; 2199 break; 2200 } 2201 error = sa6_embedscope(fin6, ip6_use_defzone); 2202 if (error) 2203 return (error); 2204 error = sa6_embedscope(lin6, ip6_use_defzone); 2205 if (error) 2206 return (error); 2207 break; 2208 #endif 2209 case AF_INET: 2210 fin = (struct sockaddr_in *)&addrs[0]; 2211 lin = (struct sockaddr_in *)&addrs[1]; 2212 if (fin->sin_len != sizeof(struct sockaddr_in) || 2213 lin->sin_len != sizeof(struct sockaddr_in)) 2214 return (EINVAL); 2215 break; 2216 default: 2217 return (EINVAL); 2218 } 2219 INP_INFO_WLOCK(&tcbinfo); 2220 switch (addrs[0].ss_family) { 2221 #ifdef INET6 2222 case AF_INET6: 2223 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2224 &l6, lin6->sin6_port, 0, NULL); 2225 break; 2226 #endif 2227 case AF_INET: 2228 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2229 lin->sin_addr, lin->sin_port, 0, NULL); 2230 break; 2231 } 2232 if (inp != NULL) { 2233 INP_LOCK(inp); 2234 if ((tw = intotw(inp)) && 2235 (inp->inp_vflag & INP_TIMEWAIT) != 0) { 2236 (void) tcp_twclose(tw, 0); 2237 } else if ((tp = intotcpcb(inp)) && 2238 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2239 tp = tcp_drop(tp, ECONNABORTED); 2240 if (tp != NULL) 2241 INP_UNLOCK(inp); 2242 } else 2243 INP_UNLOCK(inp); 2244 } else 2245 error = ESRCH; 2246 INP_INFO_WUNLOCK(&tcbinfo); 2247 return (error); 2248 } 2249 2250 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2251 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2252 0, sysctl_drop, "", "Drop TCP connection"); 2253