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; 944 945 bzero(&xt, sizeof(xt)); 946 xt.xt_len = sizeof xt; 947 /* XXX should avoid extra copy */ 948 bcopy(inp, &xt.xt_inp, sizeof *inp); 949 inp_ppcb = inp->inp_ppcb; 950 if (inp_ppcb == NULL) 951 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 952 else if (inp->inp_vflag & INP_TIMEWAIT) { 953 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 954 xt.xt_tp.t_state = TCPS_TIME_WAIT; 955 } else 956 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 957 if (inp->inp_socket != NULL) 958 sotoxsocket(inp->inp_socket, &xt.xt_socket); 959 else { 960 bzero(&xt.xt_socket, sizeof xt.xt_socket); 961 xt.xt_socket.xso_protocol = IPPROTO_TCP; 962 } 963 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 964 error = SYSCTL_OUT(req, &xt, sizeof xt); 965 } 966 } 967 if (!error) { 968 /* 969 * Give the user an updated idea of our state. 970 * If the generation differs from what we told 971 * her before, she knows that something happened 972 * while we were processing this request, and it 973 * might be necessary to retry. 974 */ 975 s = splnet(); 976 INP_INFO_RLOCK(&tcbinfo); 977 xig.xig_gen = tcbinfo.ipi_gencnt; 978 xig.xig_sogen = so_gencnt; 979 xig.xig_count = tcbinfo.ipi_count; 980 INP_INFO_RUNLOCK(&tcbinfo); 981 splx(s); 982 error = SYSCTL_OUT(req, &xig, sizeof xig); 983 } 984 free(inp_list, M_TEMP); 985 return (error); 986 } 987 988 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 989 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 990 991 static int 992 tcp_getcred(SYSCTL_HANDLER_ARGS) 993 { 994 struct xucred xuc; 995 struct sockaddr_in addrs[2]; 996 struct inpcb *inp; 997 int error, s; 998 999 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1000 if (error) 1001 return (error); 1002 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1003 if (error) 1004 return (error); 1005 s = splnet(); 1006 INP_INFO_RLOCK(&tcbinfo); 1007 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1008 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1009 if (inp == NULL) { 1010 error = ENOENT; 1011 goto outunlocked; 1012 } 1013 INP_LOCK(inp); 1014 if (inp->inp_socket == NULL) { 1015 error = ENOENT; 1016 goto out; 1017 } 1018 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1019 if (error) 1020 goto out; 1021 cru2x(inp->inp_socket->so_cred, &xuc); 1022 out: 1023 INP_UNLOCK(inp); 1024 outunlocked: 1025 INP_INFO_RUNLOCK(&tcbinfo); 1026 splx(s); 1027 if (error == 0) 1028 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1029 return (error); 1030 } 1031 1032 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1033 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1034 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1035 1036 #ifdef INET6 1037 static int 1038 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1039 { 1040 struct xucred xuc; 1041 struct sockaddr_in6 addrs[2]; 1042 struct in6_addr a6[2]; 1043 struct inpcb *inp; 1044 int error, s, mapped = 0; 1045 1046 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1047 if (error) 1048 return (error); 1049 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1050 if (error) 1051 return (error); 1052 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1053 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1054 mapped = 1; 1055 else 1056 return (EINVAL); 1057 } else { 1058 error = in6_embedscope(&a6[0], &addrs[0], NULL, NULL); 1059 if (error) 1060 return (EINVAL); 1061 error = in6_embedscope(&a6[1], &addrs[1], NULL, NULL); 1062 if (error) 1063 return (EINVAL); 1064 } 1065 s = splnet(); 1066 INP_INFO_RLOCK(&tcbinfo); 1067 if (mapped == 1) 1068 inp = in_pcblookup_hash(&tcbinfo, 1069 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1070 addrs[1].sin6_port, 1071 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1072 addrs[0].sin6_port, 1073 0, NULL); 1074 else 1075 inp = in6_pcblookup_hash(&tcbinfo, &a6[1], addrs[1].sin6_port, 1076 &a6[0], addrs[0].sin6_port, 0, NULL); 1077 if (inp == NULL) { 1078 error = ENOENT; 1079 goto outunlocked; 1080 } 1081 INP_LOCK(inp); 1082 if (inp->inp_socket == NULL) { 1083 error = ENOENT; 1084 goto out; 1085 } 1086 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1087 if (error) 1088 goto out; 1089 cru2x(inp->inp_socket->so_cred, &xuc); 1090 out: 1091 INP_UNLOCK(inp); 1092 outunlocked: 1093 INP_INFO_RUNLOCK(&tcbinfo); 1094 splx(s); 1095 if (error == 0) 1096 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1097 return (error); 1098 } 1099 1100 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1101 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1102 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1103 #endif 1104 1105 1106 void 1107 tcp_ctlinput(cmd, sa, vip) 1108 int cmd; 1109 struct sockaddr *sa; 1110 void *vip; 1111 { 1112 struct ip *ip = vip; 1113 struct tcphdr *th; 1114 struct in_addr faddr; 1115 struct inpcb *inp; 1116 struct tcpcb *tp; 1117 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1118 struct icmp *icp; 1119 struct in_conninfo inc; 1120 tcp_seq icmp_tcp_seq; 1121 int mtu, s; 1122 1123 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1124 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1125 return; 1126 1127 if (cmd == PRC_MSGSIZE) 1128 notify = tcp_mtudisc; 1129 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1130 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1131 notify = tcp_drop_syn_sent; 1132 /* 1133 * Redirects don't need to be handled up here. 1134 */ 1135 else if (PRC_IS_REDIRECT(cmd)) 1136 return; 1137 /* 1138 * Source quench is depreciated. 1139 */ 1140 else if (cmd == PRC_QUENCH) 1141 return; 1142 /* 1143 * Hostdead is ugly because it goes linearly through all PCBs. 1144 * XXX: We never get this from ICMP, otherwise it makes an 1145 * excellent DoS attack on machines with many connections. 1146 */ 1147 else if (cmd == PRC_HOSTDEAD) 1148 ip = NULL; 1149 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1150 return; 1151 if (ip != NULL) { 1152 s = splnet(); 1153 icp = (struct icmp *)((caddr_t)ip 1154 - offsetof(struct icmp, icmp_ip)); 1155 th = (struct tcphdr *)((caddr_t)ip 1156 + (ip->ip_hl << 2)); 1157 INP_INFO_WLOCK(&tcbinfo); 1158 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1159 ip->ip_src, th->th_sport, 0, NULL); 1160 if (inp != NULL) { 1161 INP_LOCK(inp); 1162 if (inp->inp_socket != NULL) { 1163 icmp_tcp_seq = htonl(th->th_seq); 1164 tp = intotcpcb(inp); 1165 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1166 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1167 if (cmd == PRC_MSGSIZE) { 1168 /* 1169 * MTU discovery: 1170 * If we got a needfrag set the MTU 1171 * in the route to the suggested new 1172 * value (if given) and then notify. 1173 */ 1174 bzero(&inc, sizeof(inc)); 1175 inc.inc_flags = 0; /* IPv4 */ 1176 inc.inc_faddr = faddr; 1177 1178 mtu = ntohs(icp->icmp_nextmtu); 1179 /* 1180 * If no alternative MTU was 1181 * proposed, try the next smaller 1182 * one. 1183 */ 1184 if (!mtu) 1185 mtu = ip_next_mtu(ntohs(ip->ip_len), 1186 1); 1187 if (mtu < max(296, (tcp_minmss) 1188 + sizeof(struct tcpiphdr))) 1189 mtu = 0; 1190 if (!mtu) 1191 mtu = tcp_mssdflt 1192 + sizeof(struct tcpiphdr); 1193 /* 1194 * Only cache the the MTU if it 1195 * is smaller than the interface 1196 * or route MTU. tcp_mtudisc() 1197 * will do right thing by itself. 1198 */ 1199 if (mtu <= tcp_maxmtu(&inc)) 1200 tcp_hc_updatemtu(&inc, mtu); 1201 } 1202 1203 inp = (*notify)(inp, inetctlerrmap[cmd]); 1204 } 1205 } 1206 if (inp != NULL) 1207 INP_UNLOCK(inp); 1208 } else { 1209 inc.inc_fport = th->th_dport; 1210 inc.inc_lport = th->th_sport; 1211 inc.inc_faddr = faddr; 1212 inc.inc_laddr = ip->ip_src; 1213 #ifdef INET6 1214 inc.inc_isipv6 = 0; 1215 #endif 1216 syncache_unreach(&inc, th); 1217 } 1218 INP_INFO_WUNLOCK(&tcbinfo); 1219 splx(s); 1220 } else 1221 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1222 } 1223 1224 #ifdef INET6 1225 void 1226 tcp6_ctlinput(cmd, sa, d) 1227 int cmd; 1228 struct sockaddr *sa; 1229 void *d; 1230 { 1231 struct tcphdr th; 1232 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1233 struct ip6_hdr *ip6; 1234 struct mbuf *m; 1235 struct ip6ctlparam *ip6cp = NULL; 1236 const struct sockaddr_in6 *sa6_src = NULL; 1237 int off; 1238 struct tcp_portonly { 1239 u_int16_t th_sport; 1240 u_int16_t th_dport; 1241 } *thp; 1242 1243 if (sa->sa_family != AF_INET6 || 1244 sa->sa_len != sizeof(struct sockaddr_in6)) 1245 return; 1246 1247 if (cmd == PRC_MSGSIZE) 1248 notify = tcp_mtudisc; 1249 else if (!PRC_IS_REDIRECT(cmd) && 1250 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1251 return; 1252 /* Source quench is depreciated. */ 1253 else if (cmd == PRC_QUENCH) 1254 return; 1255 1256 /* if the parameter is from icmp6, decode it. */ 1257 if (d != NULL) { 1258 ip6cp = (struct ip6ctlparam *)d; 1259 m = ip6cp->ip6c_m; 1260 ip6 = ip6cp->ip6c_ip6; 1261 off = ip6cp->ip6c_off; 1262 sa6_src = ip6cp->ip6c_src; 1263 } else { 1264 m = NULL; 1265 ip6 = NULL; 1266 off = 0; /* fool gcc */ 1267 sa6_src = &sa6_any; 1268 } 1269 1270 if (ip6 != NULL) { 1271 struct in_conninfo inc; 1272 /* 1273 * XXX: We assume that when IPV6 is non NULL, 1274 * M and OFF are valid. 1275 */ 1276 1277 /* check if we can safely examine src and dst ports */ 1278 if (m->m_pkthdr.len < off + sizeof(*thp)) 1279 return; 1280 1281 bzero(&th, sizeof(th)); 1282 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1283 1284 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1285 (struct sockaddr *)ip6cp->ip6c_src, 1286 th.th_sport, cmd, NULL, notify); 1287 1288 inc.inc_fport = th.th_dport; 1289 inc.inc_lport = th.th_sport; 1290 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1291 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1292 inc.inc_isipv6 = 1; 1293 INP_INFO_WLOCK(&tcbinfo); 1294 syncache_unreach(&inc, &th); 1295 INP_INFO_WUNLOCK(&tcbinfo); 1296 } else 1297 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1298 0, cmd, NULL, notify); 1299 } 1300 #endif /* INET6 */ 1301 1302 1303 /* 1304 * Following is where TCP initial sequence number generation occurs. 1305 * 1306 * There are two places where we must use initial sequence numbers: 1307 * 1. In SYN-ACK packets. 1308 * 2. In SYN packets. 1309 * 1310 * All ISNs for SYN-ACK packets are generated by the syncache. See 1311 * tcp_syncache.c for details. 1312 * 1313 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1314 * depends on this property. In addition, these ISNs should be 1315 * unguessable so as to prevent connection hijacking. To satisfy 1316 * the requirements of this situation, the algorithm outlined in 1317 * RFC 1948 is used, with only small modifications. 1318 * 1319 * Implementation details: 1320 * 1321 * Time is based off the system timer, and is corrected so that it 1322 * increases by one megabyte per second. This allows for proper 1323 * recycling on high speed LANs while still leaving over an hour 1324 * before rollover. 1325 * 1326 * As reading the *exact* system time is too expensive to be done 1327 * whenever setting up a TCP connection, we increment the time 1328 * offset in two ways. First, a small random positive increment 1329 * is added to isn_offset for each connection that is set up. 1330 * Second, the function tcp_isn_tick fires once per clock tick 1331 * and increments isn_offset as necessary so that sequence numbers 1332 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1333 * random positive increments serve only to ensure that the same 1334 * exact sequence number is never sent out twice (as could otherwise 1335 * happen when a port is recycled in less than the system tick 1336 * interval.) 1337 * 1338 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1339 * between seeding of isn_secret. This is normally set to zero, 1340 * as reseeding should not be necessary. 1341 * 1342 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1343 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1344 * general, this means holding an exclusive (write) lock. 1345 */ 1346 1347 #define ISN_BYTES_PER_SECOND 1048576 1348 #define ISN_STATIC_INCREMENT 4096 1349 #define ISN_RANDOM_INCREMENT (4096 - 1) 1350 1351 static u_char isn_secret[32]; 1352 static int isn_last_reseed; 1353 static u_int32_t isn_offset, isn_offset_old; 1354 static MD5_CTX isn_ctx; 1355 1356 tcp_seq 1357 tcp_new_isn(tp) 1358 struct tcpcb *tp; 1359 { 1360 u_int32_t md5_buffer[4]; 1361 tcp_seq new_isn; 1362 1363 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1364 INP_LOCK_ASSERT(tp->t_inpcb); 1365 1366 /* Seed if this is the first use, reseed if requested. */ 1367 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1368 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1369 < (u_int)ticks))) { 1370 read_random(&isn_secret, sizeof(isn_secret)); 1371 isn_last_reseed = ticks; 1372 } 1373 1374 /* Compute the md5 hash and return the ISN. */ 1375 MD5Init(&isn_ctx); 1376 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1377 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1378 #ifdef INET6 1379 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1380 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1381 sizeof(struct in6_addr)); 1382 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1383 sizeof(struct in6_addr)); 1384 } else 1385 #endif 1386 { 1387 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1388 sizeof(struct in_addr)); 1389 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1390 sizeof(struct in_addr)); 1391 } 1392 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1393 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1394 new_isn = (tcp_seq) md5_buffer[0]; 1395 isn_offset += ISN_STATIC_INCREMENT + 1396 (arc4random() & ISN_RANDOM_INCREMENT); 1397 new_isn += isn_offset; 1398 return (new_isn); 1399 } 1400 1401 /* 1402 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1403 * to keep time flowing at a relatively constant rate. If the random 1404 * increments have already pushed us past the projected offset, do nothing. 1405 */ 1406 static void 1407 tcp_isn_tick(xtp) 1408 void *xtp; 1409 { 1410 u_int32_t projected_offset; 1411 1412 INP_INFO_WLOCK(&tcbinfo); 1413 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1414 1415 if (projected_offset > isn_offset) 1416 isn_offset = projected_offset; 1417 1418 isn_offset_old = isn_offset; 1419 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1420 INP_INFO_WUNLOCK(&tcbinfo); 1421 } 1422 1423 /* 1424 * When a specific ICMP unreachable message is received and the 1425 * connection state is SYN-SENT, drop the connection. This behavior 1426 * is controlled by the icmp_may_rst sysctl. 1427 */ 1428 struct inpcb * 1429 tcp_drop_syn_sent(inp, errno) 1430 struct inpcb *inp; 1431 int errno; 1432 { 1433 struct tcpcb *tp = intotcpcb(inp); 1434 1435 INP_LOCK_ASSERT(inp); 1436 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1437 tcp_drop(tp, errno); 1438 return (NULL); 1439 } 1440 return (inp); 1441 } 1442 1443 /* 1444 * When `need fragmentation' ICMP is received, update our idea of the MSS 1445 * based on the new value in the route. Also nudge TCP to send something, 1446 * since we know the packet we just sent was dropped. 1447 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1448 */ 1449 struct inpcb * 1450 tcp_mtudisc(inp, errno) 1451 struct inpcb *inp; 1452 int errno; 1453 { 1454 struct tcpcb *tp = intotcpcb(inp); 1455 struct socket *so = inp->inp_socket; 1456 u_int maxmtu; 1457 u_int romtu; 1458 int mss; 1459 #ifdef INET6 1460 int isipv6; 1461 #endif /* INET6 */ 1462 1463 INP_LOCK_ASSERT(inp); 1464 if (tp != NULL) { 1465 #ifdef INET6 1466 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1467 #endif 1468 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1469 romtu = 1470 #ifdef INET6 1471 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1472 #endif /* INET6 */ 1473 tcp_maxmtu(&inp->inp_inc); 1474 if (!maxmtu) 1475 maxmtu = romtu; 1476 else 1477 maxmtu = min(maxmtu, romtu); 1478 if (!maxmtu) { 1479 tp->t_maxopd = tp->t_maxseg = 1480 #ifdef INET6 1481 isipv6 ? tcp_v6mssdflt : 1482 #endif /* INET6 */ 1483 tcp_mssdflt; 1484 return (inp); 1485 } 1486 mss = maxmtu - 1487 #ifdef INET6 1488 (isipv6 ? 1489 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1490 #endif /* INET6 */ 1491 sizeof(struct tcpiphdr) 1492 #ifdef INET6 1493 ) 1494 #endif /* INET6 */ 1495 ; 1496 1497 /* 1498 * XXX - The above conditional probably violates the TCP 1499 * spec. The problem is that, since we don't know the 1500 * other end's MSS, we are supposed to use a conservative 1501 * default. But, if we do that, then MTU discovery will 1502 * never actually take place, because the conservative 1503 * default is much less than the MTUs typically seen 1504 * on the Internet today. For the moment, we'll sweep 1505 * this under the carpet. 1506 * 1507 * The conservative default might not actually be a problem 1508 * if the only case this occurs is when sending an initial 1509 * SYN with options and data to a host we've never talked 1510 * to before. Then, they will reply with an MSS value which 1511 * will get recorded and the new parameters should get 1512 * recomputed. For Further Study. 1513 */ 1514 if (tp->t_maxopd <= mss) 1515 return (inp); 1516 tp->t_maxopd = mss; 1517 1518 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1519 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1520 mss -= TCPOLEN_TSTAMP_APPA; 1521 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1522 if (mss > MCLBYTES) 1523 mss &= ~(MCLBYTES-1); 1524 #else 1525 if (mss > MCLBYTES) 1526 mss = mss / MCLBYTES * MCLBYTES; 1527 #endif 1528 if (so->so_snd.sb_hiwat < mss) 1529 mss = so->so_snd.sb_hiwat; 1530 1531 tp->t_maxseg = mss; 1532 1533 tcpstat.tcps_mturesent++; 1534 tp->t_rtttime = 0; 1535 tp->snd_nxt = tp->snd_una; 1536 tcp_output(tp); 1537 } 1538 return (inp); 1539 } 1540 1541 /* 1542 * Look-up the routing entry to the peer of this inpcb. If no route 1543 * is found and it cannot be allocated, then return NULL. This routine 1544 * is called by TCP routines that access the rmx structure and by tcp_mss 1545 * to get the interface MTU. 1546 */ 1547 u_long 1548 tcp_maxmtu(inc) 1549 struct in_conninfo *inc; 1550 { 1551 struct route sro; 1552 struct sockaddr_in *dst; 1553 struct ifnet *ifp; 1554 u_long maxmtu = 0; 1555 1556 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1557 1558 bzero(&sro, sizeof(sro)); 1559 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1560 dst = (struct sockaddr_in *)&sro.ro_dst; 1561 dst->sin_family = AF_INET; 1562 dst->sin_len = sizeof(*dst); 1563 dst->sin_addr = inc->inc_faddr; 1564 rtalloc_ign(&sro, RTF_CLONING); 1565 } 1566 if (sro.ro_rt != NULL) { 1567 ifp = sro.ro_rt->rt_ifp; 1568 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1569 maxmtu = ifp->if_mtu; 1570 else 1571 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1572 RTFREE(sro.ro_rt); 1573 } 1574 return (maxmtu); 1575 } 1576 1577 #ifdef INET6 1578 u_long 1579 tcp_maxmtu6(inc) 1580 struct in_conninfo *inc; 1581 { 1582 struct route_in6 sro6; 1583 struct ifnet *ifp; 1584 u_long maxmtu = 0; 1585 1586 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1587 1588 bzero(&sro6, sizeof(sro6)); 1589 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1590 sro6.ro_dst.sin6_family = AF_INET6; 1591 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1592 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1593 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1594 } 1595 if (sro6.ro_rt != NULL) { 1596 ifp = sro6.ro_rt->rt_ifp; 1597 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1598 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1599 else 1600 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1601 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1602 RTFREE(sro6.ro_rt); 1603 } 1604 1605 return (maxmtu); 1606 } 1607 #endif /* INET6 */ 1608 1609 #ifdef IPSEC 1610 /* compute ESP/AH header size for TCP, including outer IP header. */ 1611 size_t 1612 ipsec_hdrsiz_tcp(tp) 1613 struct tcpcb *tp; 1614 { 1615 struct inpcb *inp; 1616 struct mbuf *m; 1617 size_t hdrsiz; 1618 struct ip *ip; 1619 #ifdef INET6 1620 struct ip6_hdr *ip6; 1621 #endif 1622 struct tcphdr *th; 1623 1624 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1625 return (0); 1626 MGETHDR(m, M_DONTWAIT, MT_DATA); 1627 if (!m) 1628 return (0); 1629 1630 #ifdef INET6 1631 if ((inp->inp_vflag & INP_IPV6) != 0) { 1632 ip6 = mtod(m, struct ip6_hdr *); 1633 th = (struct tcphdr *)(ip6 + 1); 1634 m->m_pkthdr.len = m->m_len = 1635 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1636 tcpip_fillheaders(inp, ip6, th); 1637 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1638 } else 1639 #endif /* INET6 */ 1640 { 1641 ip = mtod(m, struct ip *); 1642 th = (struct tcphdr *)(ip + 1); 1643 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1644 tcpip_fillheaders(inp, ip, th); 1645 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1646 } 1647 1648 m_free(m); 1649 return (hdrsiz); 1650 } 1651 #endif /*IPSEC*/ 1652 1653 /* 1654 * Move a TCP connection into TIME_WAIT state. 1655 * tcbinfo is locked. 1656 * inp is locked, and is unlocked before returning. 1657 */ 1658 void 1659 tcp_twstart(tp) 1660 struct tcpcb *tp; 1661 { 1662 struct tcptw *tw; 1663 struct inpcb *inp; 1664 int tw_time, acknow; 1665 struct socket *so; 1666 1667 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1668 INP_LOCK_ASSERT(tp->t_inpcb); 1669 1670 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1671 if (tw == NULL) { 1672 tw = tcp_timer_2msl_tw(1); 1673 if (tw == NULL) { 1674 tcp_close(tp); 1675 return; 1676 } 1677 } 1678 inp = tp->t_inpcb; 1679 tw->tw_inpcb = inp; 1680 1681 /* 1682 * Recover last window size sent. 1683 */ 1684 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1685 1686 /* 1687 * Set t_recent if timestamps are used on the connection. 1688 */ 1689 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1690 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1691 tw->t_recent = tp->ts_recent; 1692 else 1693 tw->t_recent = 0; 1694 1695 tw->snd_nxt = tp->snd_nxt; 1696 tw->rcv_nxt = tp->rcv_nxt; 1697 tw->iss = tp->iss; 1698 tw->irs = tp->irs; 1699 tw->t_starttime = tp->t_starttime; 1700 tw->tw_time = 0; 1701 1702 /* XXX 1703 * If this code will 1704 * be used for fin-wait-2 state also, then we may need 1705 * a ts_recent from the last segment. 1706 */ 1707 tw_time = 2 * tcp_msl; 1708 acknow = tp->t_flags & TF_ACKNOW; 1709 tcp_discardcb(tp); 1710 so = inp->inp_socket; 1711 ACCEPT_LOCK(); 1712 SOCK_LOCK(so); 1713 so->so_pcb = NULL; 1714 tw->tw_cred = crhold(so->so_cred); 1715 tw->tw_so_options = so->so_options; 1716 sotryfree(so); 1717 inp->inp_socket = NULL; 1718 if (acknow) 1719 tcp_twrespond(tw, TH_ACK); 1720 inp->inp_ppcb = (caddr_t)tw; 1721 inp->inp_vflag |= INP_TIMEWAIT; 1722 tcp_timer_2msl_reset(tw, tw_time); 1723 INP_UNLOCK(inp); 1724 } 1725 1726 /* 1727 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1728 * the actual rate is slightly higher due to the addition of 1729 * random positive increments. 1730 * 1731 * Most other new OSes use semi-randomized ISN values, so we 1732 * do not need to worry about them. 1733 */ 1734 #define MS_ISN_BYTES_PER_SECOND 250000 1735 1736 /* 1737 * Determine if the ISN we will generate has advanced beyond the last 1738 * sequence number used by the previous connection. If so, indicate 1739 * that it is safe to recycle this tw socket by returning 1. 1740 * 1741 * XXXRW: This function should assert the inpcb lock as it does multiple 1742 * non-atomic reads from the tcptw, but is currently called without it from 1743 * in_pcb.c:in_pcblookup_local(). 1744 */ 1745 int 1746 tcp_twrecycleable(struct tcptw *tw) 1747 { 1748 tcp_seq new_iss = tw->iss; 1749 tcp_seq new_irs = tw->irs; 1750 1751 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1752 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1753 1754 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1755 return (1); 1756 else 1757 return (0); 1758 } 1759 1760 struct tcptw * 1761 tcp_twclose(struct tcptw *tw, int reuse) 1762 { 1763 struct inpcb *inp; 1764 1765 inp = tw->tw_inpcb; 1766 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1767 INP_LOCK_ASSERT(inp); 1768 1769 tw->tw_inpcb = NULL; 1770 tcp_timer_2msl_stop(tw); 1771 inp->inp_ppcb = NULL; 1772 #ifdef INET6 1773 if (inp->inp_vflag & INP_IPV6PROTO) 1774 in6_pcbdetach(inp); 1775 else 1776 #endif 1777 in_pcbdetach(inp); 1778 tcpstat.tcps_closed++; 1779 crfree(tw->tw_cred); 1780 tw->tw_cred = NULL; 1781 if (reuse) 1782 return (tw); 1783 uma_zfree(tcptw_zone, tw); 1784 return (NULL); 1785 } 1786 1787 int 1788 tcp_twrespond(struct tcptw *tw, int flags) 1789 { 1790 struct inpcb *inp = tw->tw_inpcb; 1791 struct tcphdr *th; 1792 struct mbuf *m; 1793 struct ip *ip = NULL; 1794 u_int8_t *optp; 1795 u_int hdrlen, optlen; 1796 int error; 1797 #ifdef INET6 1798 struct ip6_hdr *ip6 = NULL; 1799 int isipv6 = inp->inp_inc.inc_isipv6; 1800 #endif 1801 1802 INP_LOCK_ASSERT(inp); 1803 1804 m = m_gethdr(M_DONTWAIT, MT_HEADER); 1805 if (m == NULL) 1806 return (ENOBUFS); 1807 m->m_data += max_linkhdr; 1808 1809 #ifdef MAC 1810 mac_create_mbuf_from_inpcb(inp, m); 1811 #endif 1812 1813 #ifdef INET6 1814 if (isipv6) { 1815 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1816 ip6 = mtod(m, struct ip6_hdr *); 1817 th = (struct tcphdr *)(ip6 + 1); 1818 tcpip_fillheaders(inp, ip6, th); 1819 } else 1820 #endif 1821 { 1822 hdrlen = sizeof(struct tcpiphdr); 1823 ip = mtod(m, struct ip *); 1824 th = (struct tcphdr *)(ip + 1); 1825 tcpip_fillheaders(inp, ip, th); 1826 } 1827 optp = (u_int8_t *)(th + 1); 1828 1829 /* 1830 * Send a timestamp and echo-reply if both our side and our peer 1831 * have sent timestamps in our SYN's and this is not a RST. 1832 */ 1833 if (tw->t_recent && flags == TH_ACK) { 1834 u_int32_t *lp = (u_int32_t *)optp; 1835 1836 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1837 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1838 *lp++ = htonl(ticks); 1839 *lp = htonl(tw->t_recent); 1840 optp += TCPOLEN_TSTAMP_APPA; 1841 } 1842 1843 optlen = optp - (u_int8_t *)(th + 1); 1844 1845 m->m_len = hdrlen + optlen; 1846 m->m_pkthdr.len = m->m_len; 1847 1848 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1849 1850 th->th_seq = htonl(tw->snd_nxt); 1851 th->th_ack = htonl(tw->rcv_nxt); 1852 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1853 th->th_flags = flags; 1854 th->th_win = htons(tw->last_win); 1855 1856 #ifdef INET6 1857 if (isipv6) { 1858 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1859 sizeof(struct tcphdr) + optlen); 1860 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1861 error = ip6_output(m, inp->in6p_outputopts, NULL, 1862 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1863 } else 1864 #endif 1865 { 1866 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1867 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1868 m->m_pkthdr.csum_flags = CSUM_TCP; 1869 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1870 ip->ip_len = m->m_pkthdr.len; 1871 if (path_mtu_discovery) 1872 ip->ip_off |= IP_DF; 1873 error = ip_output(m, inp->inp_options, NULL, 1874 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1875 NULL, inp); 1876 } 1877 if (flags & TH_ACK) 1878 tcpstat.tcps_sndacks++; 1879 else 1880 tcpstat.tcps_sndctrl++; 1881 tcpstat.tcps_sndtotal++; 1882 return (error); 1883 } 1884 1885 /* 1886 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1887 * 1888 * This code attempts to calculate the bandwidth-delay product as a 1889 * means of determining the optimal window size to maximize bandwidth, 1890 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1891 * routers. This code also does a fairly good job keeping RTTs in check 1892 * across slow links like modems. We implement an algorithm which is very 1893 * similar (but not meant to be) TCP/Vegas. The code operates on the 1894 * transmitter side of a TCP connection and so only effects the transmit 1895 * side of the connection. 1896 * 1897 * BACKGROUND: TCP makes no provision for the management of buffer space 1898 * at the end points or at the intermediate routers and switches. A TCP 1899 * stream, whether using NewReno or not, will eventually buffer as 1900 * many packets as it is able and the only reason this typically works is 1901 * due to the fairly small default buffers made available for a connection 1902 * (typicaly 16K or 32K). As machines use larger windows and/or window 1903 * scaling it is now fairly easy for even a single TCP connection to blow-out 1904 * all available buffer space not only on the local interface, but on 1905 * intermediate routers and switches as well. NewReno makes a misguided 1906 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1907 * then backing off, then steadily increasing the window again until another 1908 * failure occurs, ad-infinitum. This results in terrible oscillation that 1909 * is only made worse as network loads increase and the idea of intentionally 1910 * blowing out network buffers is, frankly, a terrible way to manage network 1911 * resources. 1912 * 1913 * It is far better to limit the transmit window prior to the failure 1914 * condition being achieved. There are two general ways to do this: First 1915 * you can 'scan' through different transmit window sizes and locate the 1916 * point where the RTT stops increasing, indicating that you have filled the 1917 * pipe, then scan backwards until you note that RTT stops decreasing, then 1918 * repeat ad-infinitum. This method works in principle but has severe 1919 * implementation issues due to RTT variances, timer granularity, and 1920 * instability in the algorithm which can lead to many false positives and 1921 * create oscillations as well as interact badly with other TCP streams 1922 * implementing the same algorithm. 1923 * 1924 * The second method is to limit the window to the bandwidth delay product 1925 * of the link. This is the method we implement. RTT variances and our 1926 * own manipulation of the congestion window, bwnd, can potentially 1927 * destabilize the algorithm. For this reason we have to stabilize the 1928 * elements used to calculate the window. We do this by using the minimum 1929 * observed RTT, the long term average of the observed bandwidth, and 1930 * by adding two segments worth of slop. It isn't perfect but it is able 1931 * to react to changing conditions and gives us a very stable basis on 1932 * which to extend the algorithm. 1933 */ 1934 void 1935 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1936 { 1937 u_long bw; 1938 u_long bwnd; 1939 int save_ticks; 1940 1941 INP_LOCK_ASSERT(tp->t_inpcb); 1942 1943 /* 1944 * If inflight_enable is disabled in the middle of a tcp connection, 1945 * make sure snd_bwnd is effectively disabled. 1946 */ 1947 if (tcp_inflight_enable == 0) { 1948 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1949 tp->snd_bandwidth = 0; 1950 return; 1951 } 1952 1953 /* 1954 * Figure out the bandwidth. Due to the tick granularity this 1955 * is a very rough number and it MUST be averaged over a fairly 1956 * long period of time. XXX we need to take into account a link 1957 * that is not using all available bandwidth, but for now our 1958 * slop will ramp us up if this case occurs and the bandwidth later 1959 * increases. 1960 * 1961 * Note: if ticks rollover 'bw' may wind up negative. We must 1962 * effectively reset t_bw_rtttime for this case. 1963 */ 1964 save_ticks = ticks; 1965 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1966 return; 1967 1968 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1969 (save_ticks - tp->t_bw_rtttime); 1970 tp->t_bw_rtttime = save_ticks; 1971 tp->t_bw_rtseq = ack_seq; 1972 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1973 return; 1974 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1975 1976 tp->snd_bandwidth = bw; 1977 1978 /* 1979 * Calculate the semi-static bandwidth delay product, plus two maximal 1980 * segments. The additional slop puts us squarely in the sweet 1981 * spot and also handles the bandwidth run-up case and stabilization. 1982 * Without the slop we could be locking ourselves into a lower 1983 * bandwidth. 1984 * 1985 * Situations Handled: 1986 * (1) Prevents over-queueing of packets on LANs, especially on 1987 * high speed LANs, allowing larger TCP buffers to be 1988 * specified, and also does a good job preventing 1989 * over-queueing of packets over choke points like modems 1990 * (at least for the transmit side). 1991 * 1992 * (2) Is able to handle changing network loads (bandwidth 1993 * drops so bwnd drops, bandwidth increases so bwnd 1994 * increases). 1995 * 1996 * (3) Theoretically should stabilize in the face of multiple 1997 * connections implementing the same algorithm (this may need 1998 * a little work). 1999 * 2000 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2001 * be adjusted with a sysctl but typically only needs to be 2002 * on very slow connections. A value no smaller then 5 2003 * should be used, but only reduce this default if you have 2004 * no other choice. 2005 */ 2006 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2007 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2008 #undef USERTT 2009 2010 if (tcp_inflight_debug > 0) { 2011 static int ltime; 2012 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2013 ltime = ticks; 2014 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2015 tp, 2016 bw, 2017 tp->t_rttbest, 2018 tp->t_srtt, 2019 bwnd 2020 ); 2021 } 2022 } 2023 if ((long)bwnd < tcp_inflight_min) 2024 bwnd = tcp_inflight_min; 2025 if (bwnd > tcp_inflight_max) 2026 bwnd = tcp_inflight_max; 2027 if ((long)bwnd < tp->t_maxseg * 2) 2028 bwnd = tp->t_maxseg * 2; 2029 tp->snd_bwnd = bwnd; 2030 } 2031 2032 #ifdef TCP_SIGNATURE 2033 /* 2034 * Callback function invoked by m_apply() to digest TCP segment data 2035 * contained within an mbuf chain. 2036 */ 2037 static int 2038 tcp_signature_apply(void *fstate, void *data, u_int len) 2039 { 2040 2041 MD5Update(fstate, (u_char *)data, len); 2042 return (0); 2043 } 2044 2045 /* 2046 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2047 * 2048 * Parameters: 2049 * m pointer to head of mbuf chain 2050 * off0 offset to TCP header within the mbuf chain 2051 * len length of TCP segment data, excluding options 2052 * optlen length of TCP segment options 2053 * buf pointer to storage for computed MD5 digest 2054 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2055 * 2056 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2057 * When called from tcp_input(), we can be sure that th_sum has been 2058 * zeroed out and verified already. 2059 * 2060 * This function is for IPv4 use only. Calling this function with an 2061 * IPv6 packet in the mbuf chain will yield undefined results. 2062 * 2063 * Return 0 if successful, otherwise return -1. 2064 * 2065 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2066 * search with the destination IP address, and a 'magic SPI' to be 2067 * determined by the application. This is hardcoded elsewhere to 1179 2068 * right now. Another branch of this code exists which uses the SPD to 2069 * specify per-application flows but it is unstable. 2070 */ 2071 int 2072 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2073 u_char *buf, u_int direction) 2074 { 2075 union sockaddr_union dst; 2076 struct ippseudo ippseudo; 2077 MD5_CTX ctx; 2078 int doff; 2079 struct ip *ip; 2080 struct ipovly *ipovly; 2081 struct secasvar *sav; 2082 struct tcphdr *th; 2083 u_short savecsum; 2084 2085 KASSERT(m != NULL, ("NULL mbuf chain")); 2086 KASSERT(buf != NULL, ("NULL signature pointer")); 2087 2088 /* Extract the destination from the IP header in the mbuf. */ 2089 ip = mtod(m, struct ip *); 2090 bzero(&dst, sizeof(union sockaddr_union)); 2091 dst.sa.sa_len = sizeof(struct sockaddr_in); 2092 dst.sa.sa_family = AF_INET; 2093 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2094 ip->ip_src : ip->ip_dst; 2095 2096 /* Look up an SADB entry which matches the address of the peer. */ 2097 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2098 if (sav == NULL) { 2099 printf("%s: SADB lookup failed for %s\n", __func__, 2100 inet_ntoa(dst.sin.sin_addr)); 2101 return (EINVAL); 2102 } 2103 2104 MD5Init(&ctx); 2105 ipovly = (struct ipovly *)ip; 2106 th = (struct tcphdr *)((u_char *)ip + off0); 2107 doff = off0 + sizeof(struct tcphdr) + optlen; 2108 2109 /* 2110 * Step 1: Update MD5 hash with IP pseudo-header. 2111 * 2112 * XXX The ippseudo header MUST be digested in network byte order, 2113 * or else we'll fail the regression test. Assume all fields we've 2114 * been doing arithmetic on have been in host byte order. 2115 * XXX One cannot depend on ipovly->ih_len here. When called from 2116 * tcp_output(), the underlying ip_len member has not yet been set. 2117 */ 2118 ippseudo.ippseudo_src = ipovly->ih_src; 2119 ippseudo.ippseudo_dst = ipovly->ih_dst; 2120 ippseudo.ippseudo_pad = 0; 2121 ippseudo.ippseudo_p = IPPROTO_TCP; 2122 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2123 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2124 2125 /* 2126 * Step 2: Update MD5 hash with TCP header, excluding options. 2127 * The TCP checksum must be set to zero. 2128 */ 2129 savecsum = th->th_sum; 2130 th->th_sum = 0; 2131 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2132 th->th_sum = savecsum; 2133 2134 /* 2135 * Step 3: Update MD5 hash with TCP segment data. 2136 * Use m_apply() to avoid an early m_pullup(). 2137 */ 2138 if (len > 0) 2139 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2140 2141 /* 2142 * Step 4: Update MD5 hash with shared secret. 2143 */ 2144 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2145 MD5Final(buf, &ctx); 2146 2147 key_sa_recordxfer(sav, m); 2148 KEY_FREESAV(&sav); 2149 return (0); 2150 } 2151 #endif /* TCP_SIGNATURE */ 2152 2153 static int 2154 sysctl_drop(SYSCTL_HANDLER_ARGS) 2155 { 2156 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2157 struct sockaddr_storage addrs[2]; 2158 struct inpcb *inp; 2159 struct tcpcb *tp; 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 = in6_embedscope(&f6, fin6, NULL, NULL); 2202 if (error) 2203 return (EINVAL); 2204 error = in6_embedscope(&l6, lin6, NULL, NULL); 2205 if (error) 2206 return (EINVAL); 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 ((tp = intotcpcb(inp)) && 2235 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2236 tp = tcp_drop(tp, ECONNABORTED); 2237 if (tp != NULL) 2238 INP_UNLOCK(inp); 2239 } else 2240 INP_UNLOCK(inp); 2241 } else 2242 error = ESRCH; 2243 INP_INFO_WUNLOCK(&tcbinfo); 2244 return (error); 2245 } 2246 2247 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2248 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2249 0, sysctl_drop, "", "Drop TCP connection"); 2250