Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_subr.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 * $FreeBSD: releng/5.4/sys/netinet/tcp_subr.c 145979 2005-05-07 03:58:25Z cperciva $ 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/tcp.h> 80 #include <netinet/tcp_fsm.h> 81 #include <netinet/tcp_seq.h> 82 #include <netinet/tcp_timer.h> 83 #include <netinet/tcp_var.h> 84 #ifdef INET6 85 #include <netinet6/tcp6_var.h> 86 #endif 87 #include <netinet/tcpip.h> 88 #ifdef TCPDEBUG 89 #include <netinet/tcp_debug.h> 90 #endif 91 #include <netinet6/ip6protosw.h> 92 93 #ifdef IPSEC 94 #include <netinet6/ipsec.h> 95 #ifdef INET6 96 #include <netinet6/ipsec6.h> 97 #endif 98 #include <netkey/key.h> 99 #endif /*IPSEC*/ 100 101 #ifdef FAST_IPSEC 102 #include <netipsec/ipsec.h> 103 #include <netipsec/xform.h> 104 #ifdef INET6 105 #include <netipsec/ipsec6.h> 106 #endif 107 #include <netipsec/key.h> 108 #define IPSEC 109 #endif /*FAST_IPSEC*/ 110 111 #include <machine/in_cksum.h> 112 #include <sys/md5.h> 113 114 int tcp_mssdflt = TCP_MSS; 115 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 116 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 117 118 #ifdef INET6 119 int tcp_v6mssdflt = TCP6_MSS; 120 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 121 CTLFLAG_RW, &tcp_v6mssdflt , 0, 122 "Default TCP Maximum Segment Size for IPv6"); 123 #endif 124 125 /* 126 * Minimum MSS we accept and use. This prevents DoS attacks where 127 * we are forced to a ridiculous low MSS like 20 and send hundreds 128 * of packets instead of one. The effect scales with the available 129 * bandwidth and quickly saturates the CPU and network interface 130 * with packet generation and sending. Set to zero to disable MINMSS 131 * checking. This setting prevents us from sending too small packets. 132 */ 133 int tcp_minmss = TCP_MINMSS; 134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 135 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 136 /* 137 * Number of TCP segments per second we accept from remote host 138 * before we start to calculate average segment size. If average 139 * segment size drops below the minimum TCP MSS we assume a DoS 140 * attack and reset+drop the connection. Care has to be taken not to 141 * set this value too small to not kill interactive type connections 142 * (telnet, SSH) which send many small packets. 143 */ 144 int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW, 146 &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to" 147 "be under the MINMSS Size"); 148 149 #if 0 150 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 151 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 152 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 153 #endif 154 155 int tcp_do_rfc1323 = 1; 156 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 157 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 158 159 int tcp_do_rfc1644 = 0; 160 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 161 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); 162 163 static int tcp_tcbhashsize = 0; 164 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 165 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 166 167 static int do_tcpdrain = 1; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 169 "Enable tcp_drain routine for extra help when low on mbufs"); 170 171 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 172 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 173 174 static int icmp_may_rst = 1; 175 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 176 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 177 178 static int tcp_isn_reseed_interval = 0; 179 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 180 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 181 182 /* 183 * TCP bandwidth limiting sysctls. Note that the default lower bound of 184 * 1024 exists only for debugging. A good production default would be 185 * something like 6100. 186 */ 187 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 188 "TCP inflight data limiting"); 189 190 static int tcp_inflight_enable = 1; 191 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 192 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 193 194 static int tcp_inflight_debug = 0; 195 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 196 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 197 198 static int tcp_inflight_min = 6144; 199 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 200 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 201 202 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 203 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 204 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 205 206 static int tcp_inflight_stab = 20; 207 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 208 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 209 210 uma_zone_t sack_hole_zone; 211 212 static struct inpcb *tcp_notify(struct inpcb *, int); 213 static void tcp_discardcb(struct tcpcb *); 214 static void tcp_isn_tick(void *); 215 216 /* 217 * Target size of TCP PCB hash tables. Must be a power of two. 218 * 219 * Note that this can be overridden by the kernel environment 220 * variable net.inet.tcp.tcbhashsize 221 */ 222 #ifndef TCBHASHSIZE 223 #define TCBHASHSIZE 512 224 #endif 225 226 /* 227 * XXX 228 * Callouts should be moved into struct tcp directly. They are currently 229 * separate because the tcpcb structure is exported to userland for sysctl 230 * parsing purposes, which do not know about callouts. 231 */ 232 struct tcpcb_mem { 233 struct tcpcb tcb; 234 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 235 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 236 }; 237 238 static uma_zone_t tcpcb_zone; 239 static uma_zone_t tcptw_zone; 240 struct callout isn_callout; 241 242 /* 243 * Tcp initialization 244 */ 245 void 246 tcp_init() 247 { 248 int hashsize = TCBHASHSIZE; 249 250 tcp_ccgen = 1; 251 252 tcp_delacktime = TCPTV_DELACK; 253 tcp_keepinit = TCPTV_KEEP_INIT; 254 tcp_keepidle = TCPTV_KEEP_IDLE; 255 tcp_keepintvl = TCPTV_KEEPINTVL; 256 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 257 tcp_msl = TCPTV_MSL; 258 tcp_rexmit_min = TCPTV_MIN; 259 tcp_rexmit_slop = TCPTV_CPU_VAR; 260 261 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 262 LIST_INIT(&tcb); 263 tcbinfo.listhead = &tcb; 264 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 265 if (!powerof2(hashsize)) { 266 printf("WARNING: TCB hash size not a power of 2\n"); 267 hashsize = 512; /* safe default */ 268 } 269 tcp_tcbhashsize = hashsize; 270 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 271 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 272 &tcbinfo.porthashmask); 273 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 274 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 275 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 276 #ifdef INET6 277 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 278 #else /* INET6 */ 279 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 280 #endif /* INET6 */ 281 if (max_protohdr < TCP_MINPROTOHDR) 282 max_protohdr = TCP_MINPROTOHDR; 283 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 284 panic("tcp_init"); 285 #undef TCP_MINPROTOHDR 286 /* 287 * These have to be type stable for the benefit of the timers. 288 */ 289 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 290 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 291 uma_zone_set_max(tcpcb_zone, maxsockets); 292 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 293 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 294 uma_zone_set_max(tcptw_zone, maxsockets / 5); 295 tcp_timer_init(); 296 syncache_init(); 297 tcp_hc_init(); 298 tcp_reass_init(); 299 callout_init(&isn_callout, CALLOUT_MPSAFE); 300 tcp_isn_tick(NULL); 301 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 302 SHUTDOWN_PRI_DEFAULT); 303 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 304 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 305 } 306 307 void 308 tcp_fini(xtp) 309 void *xtp; 310 { 311 callout_stop(&isn_callout); 312 313 } 314 315 /* 316 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 317 * tcp_template used to store this data in mbufs, but we now recopy it out 318 * of the tcpcb each time to conserve mbufs. 319 */ 320 void 321 tcpip_fillheaders(inp, ip_ptr, tcp_ptr) 322 struct inpcb *inp; 323 void *ip_ptr; 324 void *tcp_ptr; 325 { 326 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 327 328 INP_LOCK_ASSERT(inp); 329 330 #ifdef INET6 331 if ((inp->inp_vflag & INP_IPV6) != 0) { 332 struct ip6_hdr *ip6; 333 334 ip6 = (struct ip6_hdr *)ip_ptr; 335 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 336 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 337 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 338 (IPV6_VERSION & IPV6_VERSION_MASK); 339 ip6->ip6_nxt = IPPROTO_TCP; 340 ip6->ip6_plen = sizeof(struct tcphdr); 341 ip6->ip6_src = inp->in6p_laddr; 342 ip6->ip6_dst = inp->in6p_faddr; 343 } else 344 #endif 345 { 346 struct ip *ip; 347 348 ip = (struct ip *)ip_ptr; 349 ip->ip_v = IPVERSION; 350 ip->ip_hl = 5; 351 ip->ip_tos = inp->inp_ip_tos; 352 ip->ip_len = 0; 353 ip->ip_id = 0; 354 ip->ip_off = 0; 355 ip->ip_ttl = inp->inp_ip_ttl; 356 ip->ip_sum = 0; 357 ip->ip_p = IPPROTO_TCP; 358 ip->ip_src = inp->inp_laddr; 359 ip->ip_dst = inp->inp_faddr; 360 } 361 th->th_sport = inp->inp_lport; 362 th->th_dport = inp->inp_fport; 363 th->th_seq = 0; 364 th->th_ack = 0; 365 th->th_x2 = 0; 366 th->th_off = 5; 367 th->th_flags = 0; 368 th->th_win = 0; 369 th->th_urp = 0; 370 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 371 } 372 373 /* 374 * Create template to be used to send tcp packets on a connection. 375 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 376 * use for this function is in keepalives, which use tcp_respond. 377 */ 378 struct tcptemp * 379 tcpip_maketemplate(inp) 380 struct inpcb *inp; 381 { 382 struct mbuf *m; 383 struct tcptemp *n; 384 385 m = m_get(M_DONTWAIT, MT_HEADER); 386 if (m == NULL) 387 return (0); 388 m->m_len = sizeof(struct tcptemp); 389 n = mtod(m, struct tcptemp *); 390 391 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 392 return (n); 393 } 394 395 /* 396 * Send a single message to the TCP at address specified by 397 * the given TCP/IP header. If m == NULL, then we make a copy 398 * of the tcpiphdr at ti and send directly to the addressed host. 399 * This is used to force keep alive messages out using the TCP 400 * template for a connection. If flags are given then we send 401 * a message back to the TCP which originated the * segment ti, 402 * and discard the mbuf containing it and any other attached mbufs. 403 * 404 * In any case the ack and sequence number of the transmitted 405 * segment are as specified by the parameters. 406 * 407 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 408 */ 409 void 410 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 411 struct tcpcb *tp; 412 void *ipgen; 413 register struct tcphdr *th; 414 register struct mbuf *m; 415 tcp_seq ack, seq; 416 int flags; 417 { 418 register int tlen; 419 int win = 0; 420 struct ip *ip; 421 struct tcphdr *nth; 422 #ifdef INET6 423 struct ip6_hdr *ip6; 424 int isipv6; 425 #endif /* INET6 */ 426 int ipflags = 0; 427 struct inpcb *inp; 428 429 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 430 431 #ifdef INET6 432 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 433 ip6 = ipgen; 434 #endif /* INET6 */ 435 ip = ipgen; 436 437 if (tp != NULL) { 438 inp = tp->t_inpcb; 439 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 440 INP_INFO_WLOCK_ASSERT(&tcbinfo); 441 INP_LOCK_ASSERT(inp); 442 } else 443 inp = NULL; 444 445 if (tp != NULL) { 446 if (!(flags & TH_RST)) { 447 win = sbspace(&inp->inp_socket->so_rcv); 448 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 449 win = (long)TCP_MAXWIN << tp->rcv_scale; 450 } 451 } 452 if (m == NULL) { 453 m = m_gethdr(M_DONTWAIT, MT_HEADER); 454 if (m == NULL) 455 return; 456 tlen = 0; 457 m->m_data += max_linkhdr; 458 #ifdef INET6 459 if (isipv6) { 460 bcopy((caddr_t)ip6, mtod(m, caddr_t), 461 sizeof(struct ip6_hdr)); 462 ip6 = mtod(m, struct ip6_hdr *); 463 nth = (struct tcphdr *)(ip6 + 1); 464 } else 465 #endif /* INET6 */ 466 { 467 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 468 ip = mtod(m, struct ip *); 469 nth = (struct tcphdr *)(ip + 1); 470 } 471 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 472 flags = TH_ACK; 473 } else { 474 m_freem(m->m_next); 475 m->m_next = NULL; 476 m->m_data = (caddr_t)ipgen; 477 /* m_len is set later */ 478 tlen = 0; 479 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 480 #ifdef INET6 481 if (isipv6) { 482 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 483 nth = (struct tcphdr *)(ip6 + 1); 484 } else 485 #endif /* INET6 */ 486 { 487 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 488 nth = (struct tcphdr *)(ip + 1); 489 } 490 if (th != nth) { 491 /* 492 * this is usually a case when an extension header 493 * exists between the IPv6 header and the 494 * TCP header. 495 */ 496 nth->th_sport = th->th_sport; 497 nth->th_dport = th->th_dport; 498 } 499 xchg(nth->th_dport, nth->th_sport, n_short); 500 #undef xchg 501 } 502 #ifdef INET6 503 if (isipv6) { 504 ip6->ip6_flow = 0; 505 ip6->ip6_vfc = IPV6_VERSION; 506 ip6->ip6_nxt = IPPROTO_TCP; 507 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 508 tlen)); 509 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 510 } else 511 #endif 512 { 513 tlen += sizeof (struct tcpiphdr); 514 ip->ip_len = tlen; 515 ip->ip_ttl = ip_defttl; 516 if (path_mtu_discovery) 517 ip->ip_off |= IP_DF; 518 } 519 m->m_len = tlen; 520 m->m_pkthdr.len = tlen; 521 m->m_pkthdr.rcvif = NULL; 522 #ifdef MAC 523 if (inp != NULL) { 524 /* 525 * Packet is associated with a socket, so allow the 526 * label of the response to reflect the socket label. 527 */ 528 INP_LOCK_ASSERT(inp); 529 mac_create_mbuf_from_inpcb(inp, m); 530 } else { 531 /* 532 * Packet is not associated with a socket, so possibly 533 * update the label in place. 534 */ 535 mac_reflect_mbuf_tcp(m); 536 } 537 #endif 538 nth->th_seq = htonl(seq); 539 nth->th_ack = htonl(ack); 540 nth->th_x2 = 0; 541 nth->th_off = sizeof (struct tcphdr) >> 2; 542 nth->th_flags = flags; 543 if (tp != NULL) 544 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 545 else 546 nth->th_win = htons((u_short)win); 547 nth->th_urp = 0; 548 #ifdef INET6 549 if (isipv6) { 550 nth->th_sum = 0; 551 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 552 sizeof(struct ip6_hdr), 553 tlen - sizeof(struct ip6_hdr)); 554 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 555 NULL, NULL); 556 } else 557 #endif /* INET6 */ 558 { 559 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 560 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 561 m->m_pkthdr.csum_flags = CSUM_TCP; 562 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 563 } 564 #ifdef TCPDEBUG 565 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 566 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 567 #endif 568 #ifdef INET6 569 if (isipv6) 570 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 571 else 572 #endif /* INET6 */ 573 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 574 } 575 576 /* 577 * Create a new TCP control block, making an 578 * empty reassembly queue and hooking it to the argument 579 * protocol control block. The `inp' parameter must have 580 * come from the zone allocator set up in tcp_init(). 581 */ 582 struct tcpcb * 583 tcp_newtcpcb(inp) 584 struct inpcb *inp; 585 { 586 struct tcpcb_mem *tm; 587 struct tcpcb *tp; 588 #ifdef INET6 589 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 590 #endif /* INET6 */ 591 int callout_flag; 592 593 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 594 if (tm == NULL) 595 return (NULL); 596 tp = &tm->tcb; 597 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 598 tp->t_maxseg = tp->t_maxopd = 599 #ifdef INET6 600 isipv6 ? tcp_v6mssdflt : 601 #endif /* INET6 */ 602 tcp_mssdflt; 603 604 /* Set up our timeouts. */ 605 callout_flag = debug_mpsafenet ? CALLOUT_MPSAFE : 0; 606 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, callout_flag); 607 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, callout_flag); 608 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, callout_flag); 609 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, callout_flag); 610 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, callout_flag); 611 612 if (tcp_do_rfc1323) 613 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 614 if (tcp_do_rfc1644) 615 tp->t_flags |= TF_REQ_CC; 616 tp->sack_enable = tcp_do_sack; 617 tp->t_inpcb = inp; /* XXX */ 618 /* 619 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 620 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 621 * reasonable initial retransmit time. 622 */ 623 tp->t_srtt = TCPTV_SRTTBASE; 624 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 625 tp->t_rttmin = tcp_rexmit_min; 626 tp->t_rxtcur = TCPTV_RTOBASE; 627 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 628 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 629 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 630 tp->t_rcvtime = ticks; 631 tp->t_bw_rtttime = ticks; 632 /* 633 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 634 * because the socket may be bound to an IPv6 wildcard address, 635 * which may match an IPv4-mapped IPv6 address. 636 */ 637 inp->inp_ip_ttl = ip_defttl; 638 inp->inp_ppcb = (caddr_t)tp; 639 return (tp); /* XXX */ 640 } 641 642 /* 643 * Drop a TCP connection, reporting 644 * the specified error. If connection is synchronized, 645 * then send a RST to peer. 646 */ 647 struct tcpcb * 648 tcp_drop(tp, errno) 649 register struct tcpcb *tp; 650 int errno; 651 { 652 struct socket *so = tp->t_inpcb->inp_socket; 653 654 INP_LOCK_ASSERT(tp->t_inpcb); 655 if (TCPS_HAVERCVDSYN(tp->t_state)) { 656 tp->t_state = TCPS_CLOSED; 657 (void) tcp_output(tp); 658 tcpstat.tcps_drops++; 659 } else 660 tcpstat.tcps_conndrops++; 661 if (errno == ETIMEDOUT && tp->t_softerror) 662 errno = tp->t_softerror; 663 so->so_error = errno; 664 return (tcp_close(tp)); 665 } 666 667 static void 668 tcp_discardcb(tp) 669 struct tcpcb *tp; 670 { 671 struct tseg_qent *q; 672 struct inpcb *inp = tp->t_inpcb; 673 struct socket *so = inp->inp_socket; 674 #ifdef INET6 675 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 676 #endif /* INET6 */ 677 678 INP_LOCK_ASSERT(inp); 679 680 /* 681 * Make sure that all of our timers are stopped before we 682 * delete the PCB. 683 */ 684 callout_stop(tp->tt_rexmt); 685 callout_stop(tp->tt_persist); 686 callout_stop(tp->tt_keep); 687 callout_stop(tp->tt_2msl); 688 callout_stop(tp->tt_delack); 689 690 /* 691 * If we got enough samples through the srtt filter, 692 * save the rtt and rttvar in the routing entry. 693 * 'Enough' is arbitrarily defined as 4 rtt samples. 694 * 4 samples is enough for the srtt filter to converge 695 * to within enough % of the correct value; fewer samples 696 * and we could save a bogus rtt. The danger is not high 697 * as tcp quickly recovers from everything. 698 * XXX: Works very well but needs some more statistics! 699 */ 700 if (tp->t_rttupdated >= 4) { 701 struct hc_metrics_lite metrics; 702 u_long ssthresh; 703 704 bzero(&metrics, sizeof(metrics)); 705 /* 706 * Update the ssthresh always when the conditions below 707 * are satisfied. This gives us better new start value 708 * for the congestion avoidance for new connections. 709 * ssthresh is only set if packet loss occured on a session. 710 */ 711 ssthresh = tp->snd_ssthresh; 712 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 713 /* 714 * convert the limit from user data bytes to 715 * packets then to packet data bytes. 716 */ 717 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 718 if (ssthresh < 2) 719 ssthresh = 2; 720 ssthresh *= (u_long)(tp->t_maxseg + 721 #ifdef INET6 722 (isipv6 ? sizeof (struct ip6_hdr) + 723 sizeof (struct tcphdr) : 724 #endif 725 sizeof (struct tcpiphdr) 726 #ifdef INET6 727 ) 728 #endif 729 ); 730 } else 731 ssthresh = 0; 732 metrics.rmx_ssthresh = ssthresh; 733 734 metrics.rmx_rtt = tp->t_srtt; 735 metrics.rmx_rttvar = tp->t_rttvar; 736 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 737 metrics.rmx_bandwidth = tp->snd_bandwidth; 738 metrics.rmx_cwnd = tp->snd_cwnd; 739 metrics.rmx_sendpipe = 0; 740 metrics.rmx_recvpipe = 0; 741 742 tcp_hc_update(&inp->inp_inc, &metrics); 743 } 744 745 /* free the reassembly queue, if any */ 746 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 747 LIST_REMOVE(q, tqe_q); 748 m_freem(q->tqe_m); 749 uma_zfree(tcp_reass_zone, q); 750 tp->t_segqlen--; 751 tcp_reass_qsize--; 752 } 753 tcp_free_sackholes(tp); 754 inp->inp_ppcb = NULL; 755 tp->t_inpcb = NULL; 756 uma_zfree(tcpcb_zone, tp); 757 soisdisconnected(so); 758 } 759 760 /* 761 * Close a TCP control block: 762 * discard all space held by the tcp 763 * discard internet protocol block 764 * wake up any sleepers 765 */ 766 struct tcpcb * 767 tcp_close(tp) 768 struct tcpcb *tp; 769 { 770 struct inpcb *inp = tp->t_inpcb; 771 #ifdef INET6 772 struct socket *so = inp->inp_socket; 773 #endif 774 775 INP_LOCK_ASSERT(inp); 776 777 tcp_discardcb(tp); 778 #ifdef INET6 779 if (INP_CHECK_SOCKAF(so, AF_INET6)) 780 in6_pcbdetach(inp); 781 else 782 #endif 783 in_pcbdetach(inp); 784 tcpstat.tcps_closed++; 785 return (NULL); 786 } 787 788 void 789 tcp_drain() 790 { 791 if (do_tcpdrain) 792 { 793 struct inpcb *inpb; 794 struct tcpcb *tcpb; 795 struct tseg_qent *te; 796 797 /* 798 * Walk the tcpbs, if existing, and flush the reassembly queue, 799 * if there is one... 800 * XXX: The "Net/3" implementation doesn't imply that the TCP 801 * reassembly queue should be flushed, but in a situation 802 * where we're really low on mbufs, this is potentially 803 * usefull. 804 */ 805 INP_INFO_RLOCK(&tcbinfo); 806 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 807 if (inpb->inp_vflag & INP_TIMEWAIT) 808 continue; 809 INP_LOCK(inpb); 810 if ((tcpb = intotcpcb(inpb)) != NULL) { 811 while ((te = LIST_FIRST(&tcpb->t_segq)) 812 != NULL) { 813 LIST_REMOVE(te, tqe_q); 814 m_freem(te->tqe_m); 815 uma_zfree(tcp_reass_zone, te); 816 tcpb->t_segqlen--; 817 tcp_reass_qsize--; 818 } 819 } 820 INP_UNLOCK(inpb); 821 } 822 INP_INFO_RUNLOCK(&tcbinfo); 823 } 824 } 825 826 /* 827 * Notify a tcp user of an asynchronous error; 828 * store error as soft error, but wake up user 829 * (for now, won't do anything until can select for soft error). 830 * 831 * Do not wake up user since there currently is no mechanism for 832 * reporting soft errors (yet - a kqueue filter may be added). 833 */ 834 static struct inpcb * 835 tcp_notify(inp, error) 836 struct inpcb *inp; 837 int error; 838 { 839 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 840 841 INP_LOCK_ASSERT(inp); 842 843 /* 844 * Ignore some errors if we are hooked up. 845 * If connection hasn't completed, has retransmitted several times, 846 * and receives a second error, give up now. This is better 847 * than waiting a long time to establish a connection that 848 * can never complete. 849 */ 850 if (tp->t_state == TCPS_ESTABLISHED && 851 (error == EHOSTUNREACH || error == ENETUNREACH || 852 error == EHOSTDOWN)) { 853 return (inp); 854 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 855 tp->t_softerror) { 856 tcp_drop(tp, error); 857 return (struct inpcb *)0; 858 } else { 859 tp->t_softerror = error; 860 return (inp); 861 } 862 #if 0 863 wakeup( &so->so_timeo); 864 sorwakeup(so); 865 sowwakeup(so); 866 #endif 867 } 868 869 static int 870 tcp_pcblist(SYSCTL_HANDLER_ARGS) 871 { 872 int error, i, n, s; 873 struct inpcb *inp, **inp_list; 874 inp_gen_t gencnt; 875 struct xinpgen xig; 876 877 /* 878 * The process of preparing the TCB list is too time-consuming and 879 * resource-intensive to repeat twice on every request. 880 */ 881 if (req->oldptr == NULL) { 882 n = tcbinfo.ipi_count; 883 req->oldidx = 2 * (sizeof xig) 884 + (n + n/8) * sizeof(struct xtcpcb); 885 return (0); 886 } 887 888 if (req->newptr != NULL) 889 return (EPERM); 890 891 /* 892 * OK, now we're committed to doing something. 893 */ 894 s = splnet(); 895 INP_INFO_RLOCK(&tcbinfo); 896 gencnt = tcbinfo.ipi_gencnt; 897 n = tcbinfo.ipi_count; 898 INP_INFO_RUNLOCK(&tcbinfo); 899 splx(s); 900 901 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 902 + n * sizeof(struct xtcpcb)); 903 if (error != 0) 904 return (error); 905 906 xig.xig_len = sizeof xig; 907 xig.xig_count = n; 908 xig.xig_gen = gencnt; 909 xig.xig_sogen = so_gencnt; 910 error = SYSCTL_OUT(req, &xig, sizeof xig); 911 if (error) 912 return (error); 913 914 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 915 if (inp_list == NULL) 916 return (ENOMEM); 917 918 s = splnet(); 919 INP_INFO_RLOCK(&tcbinfo); 920 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 921 inp = LIST_NEXT(inp, inp_list)) { 922 INP_LOCK(inp); 923 if (inp->inp_gencnt <= gencnt) { 924 /* 925 * XXX: This use of cr_cansee(), introduced with 926 * TCP state changes, is not quite right, but for 927 * now, better than nothing. 928 */ 929 if (inp->inp_vflag & INP_TIMEWAIT) 930 error = cr_cansee(req->td->td_ucred, 931 intotw(inp)->tw_cred); 932 else 933 error = cr_canseesocket(req->td->td_ucred, 934 inp->inp_socket); 935 if (error == 0) 936 inp_list[i++] = inp; 937 } 938 INP_UNLOCK(inp); 939 } 940 INP_INFO_RUNLOCK(&tcbinfo); 941 splx(s); 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 s = splnet(); 982 INP_INFO_RLOCK(&tcbinfo); 983 xig.xig_gen = tcbinfo.ipi_gencnt; 984 xig.xig_sogen = so_gencnt; 985 xig.xig_count = tcbinfo.ipi_count; 986 INP_INFO_RUNLOCK(&tcbinfo); 987 splx(s); 988 error = SYSCTL_OUT(req, &xig, sizeof xig); 989 } 990 free(inp_list, M_TEMP); 991 return (error); 992 } 993 994 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 995 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 996 997 static int 998 tcp_getcred(SYSCTL_HANDLER_ARGS) 999 { 1000 struct xucred xuc; 1001 struct sockaddr_in addrs[2]; 1002 struct inpcb *inp; 1003 int error, s; 1004 1005 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1006 if (error) 1007 return (error); 1008 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1009 if (error) 1010 return (error); 1011 s = splnet(); 1012 INP_INFO_RLOCK(&tcbinfo); 1013 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1014 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1015 if (inp == NULL) { 1016 error = ENOENT; 1017 goto outunlocked; 1018 } 1019 INP_LOCK(inp); 1020 if (inp->inp_socket == NULL) { 1021 error = ENOENT; 1022 goto out; 1023 } 1024 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1025 if (error) 1026 goto out; 1027 cru2x(inp->inp_socket->so_cred, &xuc); 1028 out: 1029 INP_UNLOCK(inp); 1030 outunlocked: 1031 INP_INFO_RUNLOCK(&tcbinfo); 1032 splx(s); 1033 if (error == 0) 1034 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1035 return (error); 1036 } 1037 1038 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1039 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1040 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1041 1042 #ifdef INET6 1043 static int 1044 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1045 { 1046 struct xucred xuc; 1047 struct sockaddr_in6 addrs[2]; 1048 struct in6_addr a6[2]; 1049 struct inpcb *inp; 1050 int error, s, mapped = 0; 1051 1052 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1053 if (error) 1054 return (error); 1055 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1056 if (error) 1057 return (error); 1058 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1059 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1060 mapped = 1; 1061 else 1062 return (EINVAL); 1063 } else { 1064 error = in6_embedscope(&a6[0], &addrs[0], NULL, NULL); 1065 if (error) 1066 return (EINVAL); 1067 error = in6_embedscope(&a6[1], &addrs[1], NULL, NULL); 1068 if (error) 1069 return (EINVAL); 1070 } 1071 s = splnet(); 1072 INP_INFO_RLOCK(&tcbinfo); 1073 if (mapped == 1) 1074 inp = in_pcblookup_hash(&tcbinfo, 1075 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1076 addrs[1].sin6_port, 1077 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1078 addrs[0].sin6_port, 1079 0, NULL); 1080 else 1081 inp = in6_pcblookup_hash(&tcbinfo, &a6[1], addrs[1].sin6_port, 1082 &a6[0], addrs[0].sin6_port, 0, NULL); 1083 if (inp == NULL) { 1084 error = ENOENT; 1085 goto outunlocked; 1086 } 1087 INP_LOCK(inp); 1088 if (inp->inp_socket == NULL) { 1089 error = ENOENT; 1090 goto out; 1091 } 1092 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1093 if (error) 1094 goto out; 1095 cru2x(inp->inp_socket->so_cred, &xuc); 1096 out: 1097 INP_UNLOCK(inp); 1098 outunlocked: 1099 INP_INFO_RUNLOCK(&tcbinfo); 1100 splx(s); 1101 if (error == 0) 1102 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1103 return (error); 1104 } 1105 1106 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1107 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1108 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1109 #endif 1110 1111 1112 void 1113 tcp_ctlinput(cmd, sa, vip) 1114 int cmd; 1115 struct sockaddr *sa; 1116 void *vip; 1117 { 1118 struct ip *ip = vip; 1119 struct tcphdr *th; 1120 struct in_addr faddr; 1121 struct inpcb *inp; 1122 struct tcpcb *tp; 1123 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1124 tcp_seq icmp_seq; 1125 int s; 1126 1127 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1128 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1129 return; 1130 1131 if (cmd == PRC_QUENCH) 1132 notify = tcp_quench; 1133 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1134 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1135 notify = tcp_drop_syn_sent; 1136 else if (cmd == PRC_MSGSIZE) 1137 notify = tcp_mtudisc; 1138 /* 1139 * Redirects don't need to be handled up here. 1140 */ 1141 else if (PRC_IS_REDIRECT(cmd)) 1142 return; 1143 /* 1144 * Hostdead is ugly because it goes linearly through all PCBs. 1145 * XXX: We never get this from ICMP, otherwise it makes an 1146 * excellent DoS attack on machines with many connections. 1147 */ 1148 else if (cmd == PRC_HOSTDEAD) 1149 ip = NULL; 1150 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1151 return; 1152 if (ip != NULL) { 1153 s = splnet(); 1154 th = (struct tcphdr *)((caddr_t)ip 1155 + (ip->ip_hl << 2)); 1156 INP_INFO_WLOCK(&tcbinfo); 1157 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1158 ip->ip_src, th->th_sport, 0, NULL); 1159 if (inp != NULL) { 1160 INP_LOCK(inp); 1161 if (inp->inp_socket != NULL) { 1162 icmp_seq = htonl(th->th_seq); 1163 tp = intotcpcb(inp); 1164 if (SEQ_GEQ(icmp_seq, tp->snd_una) && 1165 SEQ_LT(icmp_seq, tp->snd_max)) 1166 inp = (*notify)(inp, inetctlerrmap[cmd]); 1167 } 1168 if (inp != NULL) 1169 INP_UNLOCK(inp); 1170 } else { 1171 struct in_conninfo inc; 1172 1173 inc.inc_fport = th->th_dport; 1174 inc.inc_lport = th->th_sport; 1175 inc.inc_faddr = faddr; 1176 inc.inc_laddr = ip->ip_src; 1177 #ifdef INET6 1178 inc.inc_isipv6 = 0; 1179 #endif 1180 syncache_unreach(&inc, th); 1181 } 1182 INP_INFO_WUNLOCK(&tcbinfo); 1183 splx(s); 1184 } else 1185 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1186 } 1187 1188 #ifdef INET6 1189 void 1190 tcp6_ctlinput(cmd, sa, d) 1191 int cmd; 1192 struct sockaddr *sa; 1193 void *d; 1194 { 1195 struct tcphdr th; 1196 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1197 struct ip6_hdr *ip6; 1198 struct mbuf *m; 1199 struct ip6ctlparam *ip6cp = NULL; 1200 const struct sockaddr_in6 *sa6_src = NULL; 1201 int off; 1202 struct tcp_portonly { 1203 u_int16_t th_sport; 1204 u_int16_t th_dport; 1205 } *thp; 1206 1207 if (sa->sa_family != AF_INET6 || 1208 sa->sa_len != sizeof(struct sockaddr_in6)) 1209 return; 1210 1211 if (cmd == PRC_QUENCH) 1212 notify = tcp_quench; 1213 else if (cmd == PRC_MSGSIZE) 1214 notify = tcp_mtudisc; 1215 else if (!PRC_IS_REDIRECT(cmd) && 1216 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1217 return; 1218 1219 /* if the parameter is from icmp6, decode it. */ 1220 if (d != NULL) { 1221 ip6cp = (struct ip6ctlparam *)d; 1222 m = ip6cp->ip6c_m; 1223 ip6 = ip6cp->ip6c_ip6; 1224 off = ip6cp->ip6c_off; 1225 sa6_src = ip6cp->ip6c_src; 1226 } else { 1227 m = NULL; 1228 ip6 = NULL; 1229 off = 0; /* fool gcc */ 1230 sa6_src = &sa6_any; 1231 } 1232 1233 if (ip6 != NULL) { 1234 struct in_conninfo inc; 1235 /* 1236 * XXX: We assume that when IPV6 is non NULL, 1237 * M and OFF are valid. 1238 */ 1239 1240 /* check if we can safely examine src and dst ports */ 1241 if (m->m_pkthdr.len < off + sizeof(*thp)) 1242 return; 1243 1244 bzero(&th, sizeof(th)); 1245 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1246 1247 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1248 (struct sockaddr *)ip6cp->ip6c_src, 1249 th.th_sport, cmd, NULL, notify); 1250 1251 inc.inc_fport = th.th_dport; 1252 inc.inc_lport = th.th_sport; 1253 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1254 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1255 inc.inc_isipv6 = 1; 1256 INP_INFO_WLOCK(&tcbinfo); 1257 syncache_unreach(&inc, &th); 1258 INP_INFO_WUNLOCK(&tcbinfo); 1259 } else 1260 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1261 0, cmd, NULL, notify); 1262 } 1263 #endif /* INET6 */ 1264 1265 1266 /* 1267 * Following is where TCP initial sequence number generation occurs. 1268 * 1269 * There are two places where we must use initial sequence numbers: 1270 * 1. In SYN-ACK packets. 1271 * 2. In SYN packets. 1272 * 1273 * All ISNs for SYN-ACK packets are generated by the syncache. See 1274 * tcp_syncache.c for details. 1275 * 1276 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1277 * depends on this property. In addition, these ISNs should be 1278 * unguessable so as to prevent connection hijacking. To satisfy 1279 * the requirements of this situation, the algorithm outlined in 1280 * RFC 1948 is used, with only small modifications. 1281 * 1282 * Implementation details: 1283 * 1284 * Time is based off the system timer, and is corrected so that it 1285 * increases by one megabyte per second. This allows for proper 1286 * recycling on high speed LANs while still leaving over an hour 1287 * before rollover. 1288 * 1289 * As reading the *exact* system time is too expensive to be done 1290 * whenever setting up a TCP connection, we increment the time 1291 * offset in two ways. First, a small random positive increment 1292 * is added to isn_offset for each connection that is set up. 1293 * Second, the function tcp_isn_tick fires once per clock tick 1294 * and increments isn_offset as necessary so that sequence numbers 1295 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1296 * random positive increments serve only to ensure that the same 1297 * exact sequence number is never sent out twice (as could otherwise 1298 * happen when a port is recycled in less than the system tick 1299 * interval.) 1300 * 1301 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1302 * between seeding of isn_secret. This is normally set to zero, 1303 * as reseeding should not be necessary. 1304 * 1305 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1306 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1307 * general, this means holding an exclusive (write) lock. 1308 */ 1309 1310 #define ISN_BYTES_PER_SECOND 1048576 1311 #define ISN_STATIC_INCREMENT 4096 1312 #define ISN_RANDOM_INCREMENT (4096 - 1) 1313 1314 static u_char isn_secret[32]; 1315 static int isn_last_reseed; 1316 static u_int32_t isn_offset, isn_offset_old; 1317 static MD5_CTX isn_ctx; 1318 1319 tcp_seq 1320 tcp_new_isn(tp) 1321 struct tcpcb *tp; 1322 { 1323 u_int32_t md5_buffer[4]; 1324 tcp_seq new_isn; 1325 1326 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1327 INP_LOCK_ASSERT(tp->t_inpcb); 1328 1329 /* Seed if this is the first use, reseed if requested. */ 1330 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1331 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1332 < (u_int)ticks))) { 1333 read_random(&isn_secret, sizeof(isn_secret)); 1334 isn_last_reseed = ticks; 1335 } 1336 1337 /* Compute the md5 hash and return the ISN. */ 1338 MD5Init(&isn_ctx); 1339 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1340 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1341 #ifdef INET6 1342 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1343 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1344 sizeof(struct in6_addr)); 1345 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1346 sizeof(struct in6_addr)); 1347 } else 1348 #endif 1349 { 1350 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1351 sizeof(struct in_addr)); 1352 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1353 sizeof(struct in_addr)); 1354 } 1355 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1356 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1357 new_isn = (tcp_seq) md5_buffer[0]; 1358 isn_offset += ISN_STATIC_INCREMENT + 1359 (arc4random() & ISN_RANDOM_INCREMENT); 1360 new_isn += isn_offset; 1361 return (new_isn); 1362 } 1363 1364 /* 1365 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1366 * to keep time flowing at a relatively constant rate. If the random 1367 * increments have already pushed us past the projected offset, do nothing. 1368 */ 1369 static void 1370 tcp_isn_tick(xtp) 1371 void *xtp; 1372 { 1373 u_int32_t projected_offset; 1374 1375 INP_INFO_WLOCK(&tcbinfo); 1376 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1377 1378 if (projected_offset > isn_offset) 1379 isn_offset = projected_offset; 1380 1381 isn_offset_old = isn_offset; 1382 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1383 INP_INFO_WUNLOCK(&tcbinfo); 1384 } 1385 1386 /* 1387 * When a source quench is received, close congestion window 1388 * to one segment. We will gradually open it again as we proceed. 1389 */ 1390 struct inpcb * 1391 tcp_quench(inp, errno) 1392 struct inpcb *inp; 1393 int errno; 1394 { 1395 struct tcpcb *tp = intotcpcb(inp); 1396 1397 INP_LOCK_ASSERT(inp); 1398 if (tp != NULL) 1399 tp->snd_cwnd = tp->t_maxseg; 1400 return (inp); 1401 } 1402 1403 /* 1404 * When a specific ICMP unreachable message is received and the 1405 * connection state is SYN-SENT, drop the connection. This behavior 1406 * is controlled by the icmp_may_rst sysctl. 1407 */ 1408 struct inpcb * 1409 tcp_drop_syn_sent(inp, errno) 1410 struct inpcb *inp; 1411 int errno; 1412 { 1413 struct tcpcb *tp = intotcpcb(inp); 1414 1415 INP_LOCK_ASSERT(inp); 1416 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1417 tcp_drop(tp, errno); 1418 return (NULL); 1419 } 1420 return (inp); 1421 } 1422 1423 /* 1424 * When `need fragmentation' ICMP is received, update our idea of the MSS 1425 * based on the new value in the route. Also nudge TCP to send something, 1426 * since we know the packet we just sent was dropped. 1427 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1428 */ 1429 struct inpcb * 1430 tcp_mtudisc(inp, errno) 1431 struct inpcb *inp; 1432 int errno; 1433 { 1434 struct tcpcb *tp = intotcpcb(inp); 1435 struct rmxp_tao tao; 1436 struct socket *so = inp->inp_socket; 1437 u_int maxmtu; 1438 u_int romtu; 1439 int mss; 1440 #ifdef INET6 1441 int isipv6; 1442 #endif /* INET6 */ 1443 bzero(&tao, sizeof(tao)); 1444 1445 INP_LOCK_ASSERT(inp); 1446 if (tp != NULL) { 1447 #ifdef INET6 1448 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1449 #endif 1450 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1451 romtu = 1452 #ifdef INET6 1453 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1454 #endif /* INET6 */ 1455 tcp_maxmtu(&inp->inp_inc); 1456 if (!maxmtu) 1457 maxmtu = romtu; 1458 else 1459 maxmtu = min(maxmtu, romtu); 1460 if (!maxmtu) { 1461 tp->t_maxopd = tp->t_maxseg = 1462 #ifdef INET6 1463 isipv6 ? tcp_v6mssdflt : 1464 #endif /* INET6 */ 1465 tcp_mssdflt; 1466 return (inp); 1467 } 1468 mss = maxmtu - 1469 #ifdef INET6 1470 (isipv6 ? 1471 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1472 #endif /* INET6 */ 1473 sizeof(struct tcpiphdr) 1474 #ifdef INET6 1475 ) 1476 #endif /* INET6 */ 1477 ; 1478 1479 if (tcp_do_rfc1644) { 1480 tcp_hc_gettao(&inp->inp_inc, &tao); 1481 if (tao.tao_mssopt) 1482 mss = min(mss, tao.tao_mssopt); 1483 } 1484 /* 1485 * XXX - The above conditional probably violates the TCP 1486 * spec. The problem is that, since we don't know the 1487 * other end's MSS, we are supposed to use a conservative 1488 * default. But, if we do that, then MTU discovery will 1489 * never actually take place, because the conservative 1490 * default is much less than the MTUs typically seen 1491 * on the Internet today. For the moment, we'll sweep 1492 * this under the carpet. 1493 * 1494 * The conservative default might not actually be a problem 1495 * if the only case this occurs is when sending an initial 1496 * SYN with options and data to a host we've never talked 1497 * to before. Then, they will reply with an MSS value which 1498 * will get recorded and the new parameters should get 1499 * recomputed. For Further Study. 1500 */ 1501 if (tp->t_maxopd <= mss) 1502 return (inp); 1503 tp->t_maxopd = mss; 1504 1505 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1506 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1507 mss -= TCPOLEN_TSTAMP_APPA; 1508 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 1509 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1510 mss -= TCPOLEN_CC_APPA; 1511 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1512 if (mss > MCLBYTES) 1513 mss &= ~(MCLBYTES-1); 1514 #else 1515 if (mss > MCLBYTES) 1516 mss = mss / MCLBYTES * MCLBYTES; 1517 #endif 1518 if (so->so_snd.sb_hiwat < mss) 1519 mss = so->so_snd.sb_hiwat; 1520 1521 tp->t_maxseg = mss; 1522 1523 tcpstat.tcps_mturesent++; 1524 tp->t_rtttime = 0; 1525 tp->snd_nxt = tp->snd_una; 1526 tcp_output(tp); 1527 } 1528 return (inp); 1529 } 1530 1531 /* 1532 * Look-up the routing entry to the peer of this inpcb. If no route 1533 * is found and it cannot be allocated, then return NULL. This routine 1534 * is called by TCP routines that access the rmx structure and by tcp_mss 1535 * to get the interface MTU. 1536 */ 1537 u_long 1538 tcp_maxmtu(inc) 1539 struct in_conninfo *inc; 1540 { 1541 struct route sro; 1542 struct sockaddr_in *dst; 1543 struct ifnet *ifp; 1544 u_long maxmtu = 0; 1545 1546 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1547 1548 bzero(&sro, sizeof(sro)); 1549 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1550 dst = (struct sockaddr_in *)&sro.ro_dst; 1551 dst->sin_family = AF_INET; 1552 dst->sin_len = sizeof(*dst); 1553 dst->sin_addr = inc->inc_faddr; 1554 rtalloc_ign(&sro, RTF_CLONING); 1555 } 1556 if (sro.ro_rt != NULL) { 1557 ifp = sro.ro_rt->rt_ifp; 1558 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1559 maxmtu = ifp->if_mtu; 1560 else 1561 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1562 RTFREE(sro.ro_rt); 1563 } 1564 return (maxmtu); 1565 } 1566 1567 #ifdef INET6 1568 u_long 1569 tcp_maxmtu6(inc) 1570 struct in_conninfo *inc; 1571 { 1572 struct route_in6 sro6; 1573 struct ifnet *ifp; 1574 u_long maxmtu = 0; 1575 1576 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1577 1578 bzero(&sro6, sizeof(sro6)); 1579 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1580 sro6.ro_dst.sin6_family = AF_INET6; 1581 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1582 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1583 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1584 } 1585 if (sro6.ro_rt != NULL) { 1586 ifp = sro6.ro_rt->rt_ifp; 1587 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1588 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1589 else 1590 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1591 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1592 RTFREE(sro6.ro_rt); 1593 } 1594 1595 return (maxmtu); 1596 } 1597 #endif /* INET6 */ 1598 1599 #ifdef IPSEC 1600 /* compute ESP/AH header size for TCP, including outer IP header. */ 1601 size_t 1602 ipsec_hdrsiz_tcp(tp) 1603 struct tcpcb *tp; 1604 { 1605 struct inpcb *inp; 1606 struct mbuf *m; 1607 size_t hdrsiz; 1608 struct ip *ip; 1609 #ifdef INET6 1610 struct ip6_hdr *ip6; 1611 #endif 1612 struct tcphdr *th; 1613 1614 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1615 return (0); 1616 MGETHDR(m, M_DONTWAIT, MT_DATA); 1617 if (!m) 1618 return (0); 1619 1620 #ifdef INET6 1621 if ((inp->inp_vflag & INP_IPV6) != 0) { 1622 ip6 = mtod(m, struct ip6_hdr *); 1623 th = (struct tcphdr *)(ip6 + 1); 1624 m->m_pkthdr.len = m->m_len = 1625 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1626 tcpip_fillheaders(inp, ip6, th); 1627 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1628 } else 1629 #endif /* INET6 */ 1630 { 1631 ip = mtod(m, struct ip *); 1632 th = (struct tcphdr *)(ip + 1); 1633 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1634 tcpip_fillheaders(inp, ip, th); 1635 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1636 } 1637 1638 m_free(m); 1639 return (hdrsiz); 1640 } 1641 #endif /*IPSEC*/ 1642 1643 /* 1644 * Move a TCP connection into TIME_WAIT state. 1645 * tcbinfo is locked. 1646 * inp is locked, and is unlocked before returning. 1647 */ 1648 void 1649 tcp_twstart(tp) 1650 struct tcpcb *tp; 1651 { 1652 struct tcptw *tw; 1653 struct inpcb *inp; 1654 int tw_time, acknow; 1655 struct socket *so; 1656 1657 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1658 INP_LOCK_ASSERT(tp->t_inpcb); 1659 1660 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1661 if (tw == NULL) { 1662 tw = tcp_timer_2msl_tw(1); 1663 if (tw == NULL) { 1664 tcp_close(tp); 1665 return; 1666 } 1667 } 1668 inp = tp->t_inpcb; 1669 tw->tw_inpcb = inp; 1670 1671 /* 1672 * Recover last window size sent. 1673 */ 1674 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1675 1676 /* 1677 * Set t_recent if timestamps are used on the connection. 1678 */ 1679 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1680 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1681 tw->t_recent = tp->ts_recent; 1682 else 1683 tw->t_recent = 0; 1684 1685 tw->snd_nxt = tp->snd_nxt; 1686 tw->rcv_nxt = tp->rcv_nxt; 1687 tw->iss = tp->iss; 1688 tw->irs = tp->irs; 1689 tw->cc_recv = tp->cc_recv; 1690 tw->cc_send = tp->cc_send; 1691 tw->t_starttime = tp->t_starttime; 1692 tw->tw_time = 0; 1693 1694 /* XXX 1695 * If this code will 1696 * be used for fin-wait-2 state also, then we may need 1697 * a ts_recent from the last segment. 1698 */ 1699 /* Shorten TIME_WAIT [RFC-1644, p.28] */ 1700 if (tp->cc_recv != 0 && (ticks - tp->t_starttime) < tcp_msl) { 1701 tw_time = tp->t_rxtcur * TCPTV_TWTRUNC; 1702 /* For T/TCP client, force ACK now. */ 1703 acknow = 1; 1704 } else { 1705 tw_time = 2 * tcp_msl; 1706 acknow = tp->t_flags & TF_ACKNOW; 1707 } 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_HEADER); 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 /* 1843 * Send `CC-family' options if needed, and it's not a RST. 1844 */ 1845 if (tw->cc_recv != 0 && flags == TH_ACK) { 1846 u_int32_t *lp = (u_int32_t *)optp; 1847 1848 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC)); 1849 *lp = htonl(tw->cc_send); 1850 optp += TCPOLEN_CC_APPA; 1851 } 1852 optlen = optp - (u_int8_t *)(th + 1); 1853 1854 m->m_len = hdrlen + optlen; 1855 m->m_pkthdr.len = m->m_len; 1856 1857 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1858 1859 th->th_seq = htonl(tw->snd_nxt); 1860 th->th_ack = htonl(tw->rcv_nxt); 1861 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1862 th->th_flags = flags; 1863 th->th_win = htons(tw->last_win); 1864 1865 #ifdef INET6 1866 if (isipv6) { 1867 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1868 sizeof(struct tcphdr) + optlen); 1869 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1870 error = ip6_output(m, inp->in6p_outputopts, NULL, 1871 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1872 } else 1873 #endif 1874 { 1875 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1876 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1877 m->m_pkthdr.csum_flags = CSUM_TCP; 1878 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1879 ip->ip_len = m->m_pkthdr.len; 1880 if (path_mtu_discovery) 1881 ip->ip_off |= IP_DF; 1882 error = ip_output(m, inp->inp_options, NULL, 1883 (tw->tw_so_options & SO_DONTROUTE), NULL, inp); 1884 } 1885 if (flags & TH_ACK) 1886 tcpstat.tcps_sndacks++; 1887 else 1888 tcpstat.tcps_sndctrl++; 1889 tcpstat.tcps_sndtotal++; 1890 return (error); 1891 } 1892 1893 /* 1894 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1895 * 1896 * This code attempts to calculate the bandwidth-delay product as a 1897 * means of determining the optimal window size to maximize bandwidth, 1898 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1899 * routers. This code also does a fairly good job keeping RTTs in check 1900 * across slow links like modems. We implement an algorithm which is very 1901 * similar (but not meant to be) TCP/Vegas. The code operates on the 1902 * transmitter side of a TCP connection and so only effects the transmit 1903 * side of the connection. 1904 * 1905 * BACKGROUND: TCP makes no provision for the management of buffer space 1906 * at the end points or at the intermediate routers and switches. A TCP 1907 * stream, whether using NewReno or not, will eventually buffer as 1908 * many packets as it is able and the only reason this typically works is 1909 * due to the fairly small default buffers made available for a connection 1910 * (typicaly 16K or 32K). As machines use larger windows and/or window 1911 * scaling it is now fairly easy for even a single TCP connection to blow-out 1912 * all available buffer space not only on the local interface, but on 1913 * intermediate routers and switches as well. NewReno makes a misguided 1914 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1915 * then backing off, then steadily increasing the window again until another 1916 * failure occurs, ad-infinitum. This results in terrible oscillation that 1917 * is only made worse as network loads increase and the idea of intentionally 1918 * blowing out network buffers is, frankly, a terrible way to manage network 1919 * resources. 1920 * 1921 * It is far better to limit the transmit window prior to the failure 1922 * condition being achieved. There are two general ways to do this: First 1923 * you can 'scan' through different transmit window sizes and locate the 1924 * point where the RTT stops increasing, indicating that you have filled the 1925 * pipe, then scan backwards until you note that RTT stops decreasing, then 1926 * repeat ad-infinitum. This method works in principle but has severe 1927 * implementation issues due to RTT variances, timer granularity, and 1928 * instability in the algorithm which can lead to many false positives and 1929 * create oscillations as well as interact badly with other TCP streams 1930 * implementing the same algorithm. 1931 * 1932 * The second method is to limit the window to the bandwidth delay product 1933 * of the link. This is the method we implement. RTT variances and our 1934 * own manipulation of the congestion window, bwnd, can potentially 1935 * destabilize the algorithm. For this reason we have to stabilize the 1936 * elements used to calculate the window. We do this by using the minimum 1937 * observed RTT, the long term average of the observed bandwidth, and 1938 * by adding two segments worth of slop. It isn't perfect but it is able 1939 * to react to changing conditions and gives us a very stable basis on 1940 * which to extend the algorithm. 1941 */ 1942 void 1943 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1944 { 1945 u_long bw; 1946 u_long bwnd; 1947 int save_ticks; 1948 1949 INP_LOCK_ASSERT(tp->t_inpcb); 1950 1951 /* 1952 * If inflight_enable is disabled in the middle of a tcp connection, 1953 * make sure snd_bwnd is effectively disabled. 1954 */ 1955 if (tcp_inflight_enable == 0) { 1956 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1957 tp->snd_bandwidth = 0; 1958 return; 1959 } 1960 1961 /* 1962 * Figure out the bandwidth. Due to the tick granularity this 1963 * is a very rough number and it MUST be averaged over a fairly 1964 * long period of time. XXX we need to take into account a link 1965 * that is not using all available bandwidth, but for now our 1966 * slop will ramp us up if this case occurs and the bandwidth later 1967 * increases. 1968 * 1969 * Note: if ticks rollover 'bw' may wind up negative. We must 1970 * effectively reset t_bw_rtttime for this case. 1971 */ 1972 save_ticks = ticks; 1973 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1974 return; 1975 1976 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1977 (save_ticks - tp->t_bw_rtttime); 1978 tp->t_bw_rtttime = save_ticks; 1979 tp->t_bw_rtseq = ack_seq; 1980 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1981 return; 1982 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1983 1984 tp->snd_bandwidth = bw; 1985 1986 /* 1987 * Calculate the semi-static bandwidth delay product, plus two maximal 1988 * segments. The additional slop puts us squarely in the sweet 1989 * spot and also handles the bandwidth run-up case and stabilization. 1990 * Without the slop we could be locking ourselves into a lower 1991 * bandwidth. 1992 * 1993 * Situations Handled: 1994 * (1) Prevents over-queueing of packets on LANs, especially on 1995 * high speed LANs, allowing larger TCP buffers to be 1996 * specified, and also does a good job preventing 1997 * over-queueing of packets over choke points like modems 1998 * (at least for the transmit side). 1999 * 2000 * (2) Is able to handle changing network loads (bandwidth 2001 * drops so bwnd drops, bandwidth increases so bwnd 2002 * increases). 2003 * 2004 * (3) Theoretically should stabilize in the face of multiple 2005 * connections implementing the same algorithm (this may need 2006 * a little work). 2007 * 2008 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2009 * be adjusted with a sysctl but typically only needs to be 2010 * on very slow connections. A value no smaller then 5 2011 * should be used, but only reduce this default if you have 2012 * no other choice. 2013 */ 2014 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2015 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2016 #undef USERTT 2017 2018 if (tcp_inflight_debug > 0) { 2019 static int ltime; 2020 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2021 ltime = ticks; 2022 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2023 tp, 2024 bw, 2025 tp->t_rttbest, 2026 tp->t_srtt, 2027 bwnd 2028 ); 2029 } 2030 } 2031 if ((long)bwnd < tcp_inflight_min) 2032 bwnd = tcp_inflight_min; 2033 if (bwnd > tcp_inflight_max) 2034 bwnd = tcp_inflight_max; 2035 if ((long)bwnd < tp->t_maxseg * 2) 2036 bwnd = tp->t_maxseg * 2; 2037 tp->snd_bwnd = bwnd; 2038 } 2039 2040 #ifdef TCP_SIGNATURE 2041 /* 2042 * Callback function invoked by m_apply() to digest TCP segment data 2043 * contained within an mbuf chain. 2044 */ 2045 static int 2046 tcp_signature_apply(void *fstate, void *data, u_int len) 2047 { 2048 2049 MD5Update(fstate, (u_char *)data, len); 2050 return (0); 2051 } 2052 2053 /* 2054 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2055 * 2056 * Parameters: 2057 * m pointer to head of mbuf chain 2058 * off0 offset to TCP header within the mbuf chain 2059 * len length of TCP segment data, excluding options 2060 * optlen length of TCP segment options 2061 * buf pointer to storage for computed MD5 digest 2062 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2063 * 2064 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2065 * When called from tcp_input(), we can be sure that th_sum has been 2066 * zeroed out and verified already. 2067 * 2068 * This function is for IPv4 use only. Calling this function with an 2069 * IPv6 packet in the mbuf chain will yield undefined results. 2070 * 2071 * Return 0 if successful, otherwise return -1. 2072 * 2073 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2074 * search with the destination IP address, and a 'magic SPI' to be 2075 * determined by the application. This is hardcoded elsewhere to 1179 2076 * right now. Another branch of this code exists which uses the SPD to 2077 * specify per-application flows but it is unstable. 2078 */ 2079 int 2080 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2081 u_char *buf, u_int direction) 2082 { 2083 union sockaddr_union dst; 2084 struct ippseudo ippseudo; 2085 MD5_CTX ctx; 2086 int doff; 2087 struct ip *ip; 2088 struct ipovly *ipovly; 2089 struct secasvar *sav; 2090 struct tcphdr *th; 2091 u_short savecsum; 2092 2093 KASSERT(m != NULL, ("NULL mbuf chain")); 2094 KASSERT(buf != NULL, ("NULL signature pointer")); 2095 2096 /* Extract the destination from the IP header in the mbuf. */ 2097 ip = mtod(m, struct ip *); 2098 bzero(&dst, sizeof(union sockaddr_union)); 2099 dst.sa.sa_len = sizeof(struct sockaddr_in); 2100 dst.sa.sa_family = AF_INET; 2101 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2102 ip->ip_src : ip->ip_dst; 2103 2104 /* Look up an SADB entry which matches the address of the peer. */ 2105 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2106 if (sav == NULL) { 2107 printf("%s: SADB lookup failed for %s\n", __func__, 2108 inet_ntoa(dst.sin.sin_addr)); 2109 return (EINVAL); 2110 } 2111 2112 MD5Init(&ctx); 2113 ipovly = (struct ipovly *)ip; 2114 th = (struct tcphdr *)((u_char *)ip + off0); 2115 doff = off0 + sizeof(struct tcphdr) + optlen; 2116 2117 /* 2118 * Step 1: Update MD5 hash with IP pseudo-header. 2119 * 2120 * XXX The ippseudo header MUST be digested in network byte order, 2121 * or else we'll fail the regression test. Assume all fields we've 2122 * been doing arithmetic on have been in host byte order. 2123 * XXX One cannot depend on ipovly->ih_len here. When called from 2124 * tcp_output(), the underlying ip_len member has not yet been set. 2125 */ 2126 ippseudo.ippseudo_src = ipovly->ih_src; 2127 ippseudo.ippseudo_dst = ipovly->ih_dst; 2128 ippseudo.ippseudo_pad = 0; 2129 ippseudo.ippseudo_p = IPPROTO_TCP; 2130 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2131 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2132 2133 /* 2134 * Step 2: Update MD5 hash with TCP header, excluding options. 2135 * The TCP checksum must be set to zero. 2136 */ 2137 savecsum = th->th_sum; 2138 th->th_sum = 0; 2139 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2140 th->th_sum = savecsum; 2141 2142 /* 2143 * Step 3: Update MD5 hash with TCP segment data. 2144 * Use m_apply() to avoid an early m_pullup(). 2145 */ 2146 if (len > 0) 2147 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2148 2149 /* 2150 * Step 4: Update MD5 hash with shared secret. 2151 */ 2152 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2153 MD5Final(buf, &ctx); 2154 2155 key_sa_recordxfer(sav, m); 2156 KEY_FREESAV(&sav); 2157 return (0); 2158 } 2159 #endif /* TCP_SIGNATURE */ 2160 2161 static int 2162 sysctl_drop(SYSCTL_HANDLER_ARGS) 2163 { 2164 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2165 struct sockaddr_storage addrs[2]; 2166 struct inpcb *inp; 2167 struct tcpcb *tp; 2168 struct sockaddr_in *fin, *lin; 2169 #ifdef INET6 2170 struct sockaddr_in6 *fin6, *lin6; 2171 struct in6_addr f6, l6; 2172 #endif 2173 int error; 2174 2175 inp = NULL; 2176 fin = lin = NULL; 2177 #ifdef INET6 2178 fin6 = lin6 = NULL; 2179 #endif 2180 error = 0; 2181 2182 if (req->oldptr != NULL || req->oldlen != 0) 2183 return (EINVAL); 2184 if (req->newptr == NULL) 2185 return (EPERM); 2186 if (req->newlen < sizeof(addrs)) 2187 return (ENOMEM); 2188 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2189 if (error) 2190 return (error); 2191 2192 switch (addrs[0].ss_family) { 2193 #ifdef INET6 2194 case AF_INET6: 2195 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2196 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2197 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2198 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2199 return (EINVAL); 2200 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2201 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2202 return (EINVAL); 2203 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2204 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2205 fin = (struct sockaddr_in *)&addrs[0]; 2206 lin = (struct sockaddr_in *)&addrs[1]; 2207 break; 2208 } 2209 error = in6_embedscope(&f6, fin6, NULL, NULL); 2210 if (error) 2211 return (EINVAL); 2212 error = in6_embedscope(&l6, lin6, NULL, NULL); 2213 if (error) 2214 return (EINVAL); 2215 break; 2216 #endif 2217 case AF_INET: 2218 fin = (struct sockaddr_in *)&addrs[0]; 2219 lin = (struct sockaddr_in *)&addrs[1]; 2220 if (fin->sin_len != sizeof(struct sockaddr_in) || 2221 lin->sin_len != sizeof(struct sockaddr_in)) 2222 return (EINVAL); 2223 break; 2224 default: 2225 return (EINVAL); 2226 } 2227 INP_INFO_WLOCK(&tcbinfo); 2228 switch (addrs[0].ss_family) { 2229 #ifdef INET6 2230 case AF_INET6: 2231 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2232 &l6, lin6->sin6_port, 0, NULL); 2233 break; 2234 #endif 2235 case AF_INET: 2236 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2237 lin->sin_addr, lin->sin_port, 0, NULL); 2238 break; 2239 } 2240 if (inp != NULL) { 2241 INP_LOCK(inp); 2242 if ((tp = intotcpcb(inp)) && 2243 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2244 tp = tcp_drop(tp, ECONNABORTED); 2245 if (tp != NULL) 2246 INP_UNLOCK(inp); 2247 } else 2248 INP_UNLOCK(inp); 2249 } else 2250 error = ESRCH; 2251 INP_INFO_WUNLOCK(&tcbinfo); 2252 return (error); 2253 } 2254 2255 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2256 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2257 0, sysctl_drop, "", "Drop TCP connection");
Cache object: 0408dc8a010403b1e606fb4847b68fda
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]