Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_subr.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 * $FreeBSD$ 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 int tcp_do_rfc1644 = 0; 161 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 162 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); 163 164 static int tcp_tcbhashsize = 0; 165 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 166 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 167 168 static int do_tcpdrain = 1; 169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 170 "Enable tcp_drain routine for extra help when low on mbufs"); 171 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 173 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 174 175 static int icmp_may_rst = 1; 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 177 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 178 179 static int tcp_isn_reseed_interval = 0; 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 181 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 182 183 /* 184 * TCP bandwidth limiting sysctls. Note that the default lower bound of 185 * 1024 exists only for debugging. A good production default would be 186 * something like 6100. 187 */ 188 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 189 "TCP inflight data limiting"); 190 191 static int tcp_inflight_enable = 1; 192 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 193 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 194 195 static int tcp_inflight_debug = 0; 196 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 197 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 198 199 static int tcp_inflight_min = 6144; 200 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 201 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 202 203 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 204 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 205 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 206 207 static int tcp_inflight_stab = 20; 208 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 209 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 210 211 uma_zone_t sack_hole_zone; 212 213 static struct inpcb *tcp_notify(struct inpcb *, int); 214 static void tcp_discardcb(struct tcpcb *); 215 static void tcp_isn_tick(void *); 216 217 /* 218 * Target size of TCP PCB hash tables. Must be a power of two. 219 * 220 * Note that this can be overridden by the kernel environment 221 * variable net.inet.tcp.tcbhashsize 222 */ 223 #ifndef TCBHASHSIZE 224 #define TCBHASHSIZE 512 225 #endif 226 227 /* 228 * XXX 229 * Callouts should be moved into struct tcp directly. They are currently 230 * separate because the tcpcb structure is exported to userland for sysctl 231 * parsing purposes, which do not know about callouts. 232 */ 233 struct tcpcb_mem { 234 struct tcpcb tcb; 235 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 236 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 237 }; 238 239 static uma_zone_t tcpcb_zone; 240 static uma_zone_t tcptw_zone; 241 struct callout isn_callout; 242 243 /* 244 * Tcp initialization 245 */ 246 void 247 tcp_init() 248 { 249 int hashsize = TCBHASHSIZE; 250 251 tcp_ccgen = 1; 252 253 tcp_delacktime = TCPTV_DELACK; 254 tcp_keepinit = TCPTV_KEEP_INIT; 255 tcp_keepidle = TCPTV_KEEP_IDLE; 256 tcp_keepintvl = TCPTV_KEEPINTVL; 257 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 258 tcp_msl = TCPTV_MSL; 259 tcp_rexmit_min = TCPTV_MIN; 260 tcp_rexmit_slop = TCPTV_CPU_VAR; 261 262 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 263 LIST_INIT(&tcb); 264 tcbinfo.listhead = &tcb; 265 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 266 if (!powerof2(hashsize)) { 267 printf("WARNING: TCB hash size not a power of 2\n"); 268 hashsize = 512; /* safe default */ 269 } 270 tcp_tcbhashsize = hashsize; 271 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 272 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 273 &tcbinfo.porthashmask); 274 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 275 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 276 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 277 #ifdef INET6 278 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 279 #else /* INET6 */ 280 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 281 #endif /* INET6 */ 282 if (max_protohdr < TCP_MINPROTOHDR) 283 max_protohdr = TCP_MINPROTOHDR; 284 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 285 panic("tcp_init"); 286 #undef TCP_MINPROTOHDR 287 /* 288 * These have to be type stable for the benefit of the timers. 289 */ 290 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 291 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 292 uma_zone_set_max(tcpcb_zone, maxsockets); 293 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 294 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 295 uma_zone_set_max(tcptw_zone, maxsockets / 5); 296 tcp_timer_init(); 297 syncache_init(); 298 tcp_hc_init(); 299 tcp_reass_init(); 300 callout_init(&isn_callout, CALLOUT_MPSAFE); 301 tcp_isn_tick(NULL); 302 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 303 SHUTDOWN_PRI_DEFAULT); 304 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 305 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 306 } 307 308 void 309 tcp_fini(xtp) 310 void *xtp; 311 { 312 callout_stop(&isn_callout); 313 314 } 315 316 /* 317 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 318 * tcp_template used to store this data in mbufs, but we now recopy it out 319 * of the tcpcb each time to conserve mbufs. 320 */ 321 void 322 tcpip_fillheaders(inp, ip_ptr, tcp_ptr) 323 struct inpcb *inp; 324 void *ip_ptr; 325 void *tcp_ptr; 326 { 327 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 328 329 INP_LOCK_ASSERT(inp); 330 331 #ifdef INET6 332 if ((inp->inp_vflag & INP_IPV6) != 0) { 333 struct ip6_hdr *ip6; 334 335 ip6 = (struct ip6_hdr *)ip_ptr; 336 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 337 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 338 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 339 (IPV6_VERSION & IPV6_VERSION_MASK); 340 ip6->ip6_nxt = IPPROTO_TCP; 341 ip6->ip6_plen = sizeof(struct tcphdr); 342 ip6->ip6_src = inp->in6p_laddr; 343 ip6->ip6_dst = inp->in6p_faddr; 344 } else 345 #endif 346 { 347 struct ip *ip; 348 349 ip = (struct ip *)ip_ptr; 350 ip->ip_v = IPVERSION; 351 ip->ip_hl = 5; 352 ip->ip_tos = inp->inp_ip_tos; 353 ip->ip_len = 0; 354 ip->ip_id = 0; 355 ip->ip_off = 0; 356 ip->ip_ttl = inp->inp_ip_ttl; 357 ip->ip_sum = 0; 358 ip->ip_p = IPPROTO_TCP; 359 ip->ip_src = inp->inp_laddr; 360 ip->ip_dst = inp->inp_faddr; 361 } 362 th->th_sport = inp->inp_lport; 363 th->th_dport = inp->inp_fport; 364 th->th_seq = 0; 365 th->th_ack = 0; 366 th->th_x2 = 0; 367 th->th_off = 5; 368 th->th_flags = 0; 369 th->th_win = 0; 370 th->th_urp = 0; 371 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 372 } 373 374 /* 375 * Create template to be used to send tcp packets on a connection. 376 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 377 * use for this function is in keepalives, which use tcp_respond. 378 */ 379 struct tcptemp * 380 tcpip_maketemplate(inp) 381 struct inpcb *inp; 382 { 383 struct mbuf *m; 384 struct tcptemp *n; 385 386 m = m_get(M_DONTWAIT, MT_HEADER); 387 if (m == NULL) 388 return (0); 389 m->m_len = sizeof(struct tcptemp); 390 n = mtod(m, struct tcptemp *); 391 392 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 393 return (n); 394 } 395 396 /* 397 * Send a single message to the TCP at address specified by 398 * the given TCP/IP header. If m == NULL, then we make a copy 399 * of the tcpiphdr at ti and send directly to the addressed host. 400 * This is used to force keep alive messages out using the TCP 401 * template for a connection. If flags are given then we send 402 * a message back to the TCP which originated the * segment ti, 403 * and discard the mbuf containing it and any other attached mbufs. 404 * 405 * In any case the ack and sequence number of the transmitted 406 * segment are as specified by the parameters. 407 * 408 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 409 */ 410 void 411 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 412 struct tcpcb *tp; 413 void *ipgen; 414 register struct tcphdr *th; 415 register struct mbuf *m; 416 tcp_seq ack, seq; 417 int flags; 418 { 419 register int tlen; 420 int win = 0; 421 struct ip *ip; 422 struct tcphdr *nth; 423 #ifdef INET6 424 struct ip6_hdr *ip6; 425 int isipv6; 426 #endif /* INET6 */ 427 int ipflags = 0; 428 struct inpcb *inp; 429 430 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 431 432 #ifdef INET6 433 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 434 ip6 = ipgen; 435 #endif /* INET6 */ 436 ip = ipgen; 437 438 if (tp != NULL) { 439 inp = tp->t_inpcb; 440 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 441 INP_INFO_WLOCK_ASSERT(&tcbinfo); 442 INP_LOCK_ASSERT(inp); 443 } else 444 inp = NULL; 445 446 if (tp != NULL) { 447 if (!(flags & TH_RST)) { 448 win = sbspace(&inp->inp_socket->so_rcv); 449 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 450 win = (long)TCP_MAXWIN << tp->rcv_scale; 451 } 452 } 453 if (m == NULL) { 454 m = m_gethdr(M_DONTWAIT, MT_HEADER); 455 if (m == NULL) 456 return; 457 tlen = 0; 458 m->m_data += max_linkhdr; 459 #ifdef INET6 460 if (isipv6) { 461 bcopy((caddr_t)ip6, mtod(m, caddr_t), 462 sizeof(struct ip6_hdr)); 463 ip6 = mtod(m, struct ip6_hdr *); 464 nth = (struct tcphdr *)(ip6 + 1); 465 } else 466 #endif /* INET6 */ 467 { 468 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 469 ip = mtod(m, struct ip *); 470 nth = (struct tcphdr *)(ip + 1); 471 } 472 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 473 flags = TH_ACK; 474 } else { 475 m_freem(m->m_next); 476 m->m_next = NULL; 477 m->m_data = (caddr_t)ipgen; 478 /* m_len is set later */ 479 tlen = 0; 480 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 481 #ifdef INET6 482 if (isipv6) { 483 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 484 nth = (struct tcphdr *)(ip6 + 1); 485 } else 486 #endif /* INET6 */ 487 { 488 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 489 nth = (struct tcphdr *)(ip + 1); 490 } 491 if (th != nth) { 492 /* 493 * this is usually a case when an extension header 494 * exists between the IPv6 header and the 495 * TCP header. 496 */ 497 nth->th_sport = th->th_sport; 498 nth->th_dport = th->th_dport; 499 } 500 xchg(nth->th_dport, nth->th_sport, n_short); 501 #undef xchg 502 } 503 #ifdef INET6 504 if (isipv6) { 505 ip6->ip6_flow = 0; 506 ip6->ip6_vfc = IPV6_VERSION; 507 ip6->ip6_nxt = IPPROTO_TCP; 508 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 509 tlen)); 510 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 511 } else 512 #endif 513 { 514 tlen += sizeof (struct tcpiphdr); 515 ip->ip_len = tlen; 516 ip->ip_ttl = ip_defttl; 517 if (path_mtu_discovery) 518 ip->ip_off |= IP_DF; 519 } 520 m->m_len = tlen; 521 m->m_pkthdr.len = tlen; 522 m->m_pkthdr.rcvif = NULL; 523 #ifdef MAC 524 if (inp != NULL) { 525 /* 526 * Packet is associated with a socket, so allow the 527 * label of the response to reflect the socket label. 528 */ 529 INP_LOCK_ASSERT(inp); 530 mac_create_mbuf_from_inpcb(inp, m); 531 } else { 532 /* 533 * Packet is not associated with a socket, so possibly 534 * update the label in place. 535 */ 536 mac_reflect_mbuf_tcp(m); 537 } 538 #endif 539 nth->th_seq = htonl(seq); 540 nth->th_ack = htonl(ack); 541 nth->th_x2 = 0; 542 nth->th_off = sizeof (struct tcphdr) >> 2; 543 nth->th_flags = flags; 544 if (tp != NULL) 545 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 546 else 547 nth->th_win = htons((u_short)win); 548 nth->th_urp = 0; 549 #ifdef INET6 550 if (isipv6) { 551 nth->th_sum = 0; 552 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 553 sizeof(struct ip6_hdr), 554 tlen - sizeof(struct ip6_hdr)); 555 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 556 NULL, NULL); 557 } else 558 #endif /* INET6 */ 559 { 560 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 561 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 562 m->m_pkthdr.csum_flags = CSUM_TCP; 563 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 564 } 565 #ifdef TCPDEBUG 566 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 567 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 568 #endif 569 #ifdef INET6 570 if (isipv6) 571 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 572 else 573 #endif /* INET6 */ 574 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 575 } 576 577 /* 578 * Create a new TCP control block, making an 579 * empty reassembly queue and hooking it to the argument 580 * protocol control block. The `inp' parameter must have 581 * come from the zone allocator set up in tcp_init(). 582 */ 583 struct tcpcb * 584 tcp_newtcpcb(inp) 585 struct inpcb *inp; 586 { 587 struct tcpcb_mem *tm; 588 struct tcpcb *tp; 589 #ifdef INET6 590 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 591 #endif /* INET6 */ 592 int callout_flag; 593 594 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 595 if (tm == NULL) 596 return (NULL); 597 tp = &tm->tcb; 598 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 599 tp->t_maxseg = tp->t_maxopd = 600 #ifdef INET6 601 isipv6 ? tcp_v6mssdflt : 602 #endif /* INET6 */ 603 tcp_mssdflt; 604 605 /* Set up our timeouts. */ 606 callout_flag = debug_mpsafenet ? CALLOUT_MPSAFE : 0; 607 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, callout_flag); 608 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, callout_flag); 609 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, callout_flag); 610 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, callout_flag); 611 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, callout_flag); 612 613 if (tcp_do_rfc1323) 614 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 615 if (tcp_do_rfc1644) 616 tp->t_flags |= TF_REQ_CC; 617 tp->sack_enable = tcp_do_sack; 618 tp->t_inpcb = inp; /* XXX */ 619 /* 620 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 621 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 622 * reasonable initial retransmit time. 623 */ 624 tp->t_srtt = TCPTV_SRTTBASE; 625 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 626 tp->t_rttmin = tcp_rexmit_min; 627 tp->t_rxtcur = TCPTV_RTOBASE; 628 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 629 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 630 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 631 tp->t_rcvtime = ticks; 632 tp->t_bw_rtttime = ticks; 633 /* 634 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 635 * because the socket may be bound to an IPv6 wildcard address, 636 * which may match an IPv4-mapped IPv6 address. 637 */ 638 inp->inp_ip_ttl = ip_defttl; 639 inp->inp_ppcb = (caddr_t)tp; 640 return (tp); /* XXX */ 641 } 642 643 /* 644 * Drop a TCP connection, reporting 645 * the specified error. If connection is synchronized, 646 * then send a RST to peer. 647 */ 648 struct tcpcb * 649 tcp_drop(tp, errno) 650 register struct tcpcb *tp; 651 int errno; 652 { 653 struct socket *so = tp->t_inpcb->inp_socket; 654 655 INP_INFO_WLOCK_ASSERT(&tcbinfo); 656 INP_LOCK_ASSERT(tp->t_inpcb); 657 658 if (TCPS_HAVERCVDSYN(tp->t_state)) { 659 tp->t_state = TCPS_CLOSED; 660 (void) tcp_output(tp); 661 tcpstat.tcps_drops++; 662 } else 663 tcpstat.tcps_conndrops++; 664 if (errno == ETIMEDOUT && tp->t_softerror) 665 errno = tp->t_softerror; 666 so->so_error = errno; 667 return (tcp_close(tp)); 668 } 669 670 static void 671 tcp_discardcb(tp) 672 struct tcpcb *tp; 673 { 674 struct tseg_qent *q; 675 struct inpcb *inp = tp->t_inpcb; 676 struct socket *so = inp->inp_socket; 677 #ifdef INET6 678 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 679 #endif /* INET6 */ 680 681 INP_LOCK_ASSERT(inp); 682 683 /* 684 * Make sure that all of our timers are stopped before we 685 * delete the PCB. 686 */ 687 callout_stop(tp->tt_rexmt); 688 callout_stop(tp->tt_persist); 689 callout_stop(tp->tt_keep); 690 callout_stop(tp->tt_2msl); 691 callout_stop(tp->tt_delack); 692 693 /* 694 * If we got enough samples through the srtt filter, 695 * save the rtt and rttvar in the routing entry. 696 * 'Enough' is arbitrarily defined as 4 rtt samples. 697 * 4 samples is enough for the srtt filter to converge 698 * to within enough % of the correct value; fewer samples 699 * and we could save a bogus rtt. The danger is not high 700 * as tcp quickly recovers from everything. 701 * XXX: Works very well but needs some more statistics! 702 */ 703 if (tp->t_rttupdated >= 4) { 704 struct hc_metrics_lite metrics; 705 u_long ssthresh; 706 707 bzero(&metrics, sizeof(metrics)); 708 /* 709 * Update the ssthresh always when the conditions below 710 * are satisfied. This gives us better new start value 711 * for the congestion avoidance for new connections. 712 * ssthresh is only set if packet loss occured on a session. 713 */ 714 ssthresh = tp->snd_ssthresh; 715 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 716 /* 717 * convert the limit from user data bytes to 718 * packets then to packet data bytes. 719 */ 720 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 721 if (ssthresh < 2) 722 ssthresh = 2; 723 ssthresh *= (u_long)(tp->t_maxseg + 724 #ifdef INET6 725 (isipv6 ? sizeof (struct ip6_hdr) + 726 sizeof (struct tcphdr) : 727 #endif 728 sizeof (struct tcpiphdr) 729 #ifdef INET6 730 ) 731 #endif 732 ); 733 } else 734 ssthresh = 0; 735 metrics.rmx_ssthresh = ssthresh; 736 737 metrics.rmx_rtt = tp->t_srtt; 738 metrics.rmx_rttvar = tp->t_rttvar; 739 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 740 metrics.rmx_bandwidth = tp->snd_bandwidth; 741 metrics.rmx_cwnd = tp->snd_cwnd; 742 metrics.rmx_sendpipe = 0; 743 metrics.rmx_recvpipe = 0; 744 745 tcp_hc_update(&inp->inp_inc, &metrics); 746 } 747 748 /* free the reassembly queue, if any */ 749 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 750 LIST_REMOVE(q, tqe_q); 751 m_freem(q->tqe_m); 752 uma_zfree(tcp_reass_zone, q); 753 tp->t_segqlen--; 754 tcp_reass_qsize--; 755 } 756 tcp_free_sackholes(tp); 757 inp->inp_ppcb = NULL; 758 tp->t_inpcb = NULL; 759 uma_zfree(tcpcb_zone, tp); 760 soisdisconnected(so); 761 } 762 763 /* 764 * Close a TCP control block: 765 * discard all space held by the tcp 766 * discard internet protocol block 767 * wake up any sleepers 768 */ 769 struct tcpcb * 770 tcp_close(tp) 771 struct tcpcb *tp; 772 { 773 struct inpcb *inp = tp->t_inpcb; 774 #ifdef INET6 775 struct socket *so = inp->inp_socket; 776 #endif 777 778 INP_INFO_WLOCK_ASSERT(&tcbinfo); 779 INP_LOCK_ASSERT(inp); 780 781 tcp_discardcb(tp); 782 #ifdef INET6 783 if (INP_CHECK_SOCKAF(so, AF_INET6)) 784 in6_pcbdetach(inp); 785 else 786 #endif 787 in_pcbdetach(inp); 788 tcpstat.tcps_closed++; 789 return (NULL); 790 } 791 792 void 793 tcp_drain() 794 { 795 if (do_tcpdrain) 796 { 797 struct inpcb *inpb; 798 struct tcpcb *tcpb; 799 struct tseg_qent *te; 800 801 /* 802 * Walk the tcpbs, if existing, and flush the reassembly queue, 803 * if there is one... 804 * XXX: The "Net/3" implementation doesn't imply that the TCP 805 * reassembly queue should be flushed, but in a situation 806 * where we're really low on mbufs, this is potentially 807 * usefull. 808 */ 809 INP_INFO_RLOCK(&tcbinfo); 810 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 811 if (inpb->inp_vflag & INP_TIMEWAIT) 812 continue; 813 INP_LOCK(inpb); 814 if ((tcpb = intotcpcb(inpb)) != NULL) { 815 while ((te = LIST_FIRST(&tcpb->t_segq)) 816 != NULL) { 817 LIST_REMOVE(te, tqe_q); 818 m_freem(te->tqe_m); 819 uma_zfree(tcp_reass_zone, te); 820 tcpb->t_segqlen--; 821 tcp_reass_qsize--; 822 } 823 tcp_clean_sackreport(tcpb); 824 } 825 INP_UNLOCK(inpb); 826 } 827 INP_INFO_RUNLOCK(&tcbinfo); 828 } 829 } 830 831 /* 832 * Notify a tcp user of an asynchronous error; 833 * store error as soft error, but wake up user 834 * (for now, won't do anything until can select for soft error). 835 * 836 * Do not wake up user since there currently is no mechanism for 837 * reporting soft errors (yet - a kqueue filter may be added). 838 */ 839 static struct inpcb * 840 tcp_notify(inp, error) 841 struct inpcb *inp; 842 int error; 843 { 844 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 845 846 INP_INFO_WLOCK_ASSERT(&tcbinfo); 847 INP_LOCK_ASSERT(inp); 848 849 /* 850 * Ignore some errors if we are hooked up. 851 * If connection hasn't completed, has retransmitted several times, 852 * and receives a second error, give up now. This is better 853 * than waiting a long time to establish a connection that 854 * can never complete. 855 */ 856 if (tp->t_state == TCPS_ESTABLISHED && 857 (error == EHOSTUNREACH || error == ENETUNREACH || 858 error == EHOSTDOWN)) { 859 return (inp); 860 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 861 tp->t_softerror) { 862 tcp_drop(tp, error); 863 return (struct inpcb *)0; 864 } else { 865 tp->t_softerror = error; 866 return (inp); 867 } 868 #if 0 869 wakeup( &so->so_timeo); 870 sorwakeup(so); 871 sowwakeup(so); 872 #endif 873 } 874 875 static int 876 tcp_pcblist(SYSCTL_HANDLER_ARGS) 877 { 878 int error, i, n, s; 879 struct inpcb *inp, **inp_list; 880 inp_gen_t gencnt; 881 struct xinpgen xig; 882 883 /* 884 * The process of preparing the TCB list is too time-consuming and 885 * resource-intensive to repeat twice on every request. 886 */ 887 if (req->oldptr == NULL) { 888 n = tcbinfo.ipi_count; 889 req->oldidx = 2 * (sizeof xig) 890 + (n + n/8) * sizeof(struct xtcpcb); 891 return (0); 892 } 893 894 if (req->newptr != NULL) 895 return (EPERM); 896 897 /* 898 * OK, now we're committed to doing something. 899 */ 900 s = splnet(); 901 INP_INFO_RLOCK(&tcbinfo); 902 gencnt = tcbinfo.ipi_gencnt; 903 n = tcbinfo.ipi_count; 904 INP_INFO_RUNLOCK(&tcbinfo); 905 splx(s); 906 907 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 908 + n * sizeof(struct xtcpcb)); 909 if (error != 0) 910 return (error); 911 912 xig.xig_len = sizeof xig; 913 xig.xig_count = n; 914 xig.xig_gen = gencnt; 915 xig.xig_sogen = so_gencnt; 916 error = SYSCTL_OUT(req, &xig, sizeof xig); 917 if (error) 918 return (error); 919 920 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 921 if (inp_list == NULL) 922 return (ENOMEM); 923 924 s = splnet(); 925 INP_INFO_RLOCK(&tcbinfo); 926 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp != NULL && i < n; 927 inp = LIST_NEXT(inp, inp_list)) { 928 INP_LOCK(inp); 929 if (inp->inp_gencnt <= gencnt) { 930 /* 931 * XXX: This use of cr_cansee(), introduced with 932 * TCP state changes, is not quite right, but for 933 * now, better than nothing. 934 */ 935 if (inp->inp_vflag & INP_TIMEWAIT) 936 error = cr_cansee(req->td->td_ucred, 937 intotw(inp)->tw_cred); 938 else 939 error = cr_canseesocket(req->td->td_ucred, 940 inp->inp_socket); 941 if (error == 0) 942 inp_list[i++] = inp; 943 } 944 INP_UNLOCK(inp); 945 } 946 INP_INFO_RUNLOCK(&tcbinfo); 947 splx(s); 948 n = i; 949 950 error = 0; 951 for (i = 0; i < n; i++) { 952 inp = inp_list[i]; 953 if (inp->inp_gencnt <= gencnt) { 954 struct xtcpcb xt; 955 caddr_t inp_ppcb; 956 957 bzero(&xt, sizeof(xt)); 958 xt.xt_len = sizeof xt; 959 /* XXX should avoid extra copy */ 960 bcopy(inp, &xt.xt_inp, sizeof *inp); 961 inp_ppcb = inp->inp_ppcb; 962 if (inp_ppcb == NULL) 963 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 964 else if (inp->inp_vflag & INP_TIMEWAIT) { 965 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 966 xt.xt_tp.t_state = TCPS_TIME_WAIT; 967 } else 968 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 969 if (inp->inp_socket != NULL) 970 sotoxsocket(inp->inp_socket, &xt.xt_socket); 971 else { 972 bzero(&xt.xt_socket, sizeof xt.xt_socket); 973 xt.xt_socket.xso_protocol = IPPROTO_TCP; 974 } 975 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 976 error = SYSCTL_OUT(req, &xt, sizeof xt); 977 } 978 } 979 if (!error) { 980 /* 981 * Give the user an updated idea of our state. 982 * If the generation differs from what we told 983 * her before, she knows that something happened 984 * while we were processing this request, and it 985 * might be necessary to retry. 986 */ 987 s = splnet(); 988 INP_INFO_RLOCK(&tcbinfo); 989 xig.xig_gen = tcbinfo.ipi_gencnt; 990 xig.xig_sogen = so_gencnt; 991 xig.xig_count = tcbinfo.ipi_count; 992 INP_INFO_RUNLOCK(&tcbinfo); 993 splx(s); 994 error = SYSCTL_OUT(req, &xig, sizeof xig); 995 } 996 free(inp_list, M_TEMP); 997 return (error); 998 } 999 1000 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1001 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1002 1003 static int 1004 tcp_getcred(SYSCTL_HANDLER_ARGS) 1005 { 1006 struct xucred xuc; 1007 struct sockaddr_in addrs[2]; 1008 struct inpcb *inp; 1009 int error, s; 1010 1011 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1012 if (error) 1013 return (error); 1014 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1015 if (error) 1016 return (error); 1017 s = splnet(); 1018 INP_INFO_RLOCK(&tcbinfo); 1019 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1020 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1021 if (inp == NULL) { 1022 error = ENOENT; 1023 goto outunlocked; 1024 } 1025 INP_LOCK(inp); 1026 if (inp->inp_socket == NULL) { 1027 error = ENOENT; 1028 goto out; 1029 } 1030 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1031 if (error) 1032 goto out; 1033 cru2x(inp->inp_socket->so_cred, &xuc); 1034 out: 1035 INP_UNLOCK(inp); 1036 outunlocked: 1037 INP_INFO_RUNLOCK(&tcbinfo); 1038 splx(s); 1039 if (error == 0) 1040 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1041 return (error); 1042 } 1043 1044 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1045 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1046 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1047 1048 #ifdef INET6 1049 static int 1050 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1051 { 1052 struct xucred xuc; 1053 struct sockaddr_in6 addrs[2]; 1054 struct in6_addr a6[2]; 1055 struct inpcb *inp; 1056 int error, s, mapped = 0; 1057 1058 error = suser_cred(req->td->td_ucred, SUSER_ALLOWJAIL); 1059 if (error) 1060 return (error); 1061 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1062 if (error) 1063 return (error); 1064 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1065 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1066 mapped = 1; 1067 else 1068 return (EINVAL); 1069 } else { 1070 error = in6_embedscope(&a6[0], &addrs[0], NULL, NULL); 1071 if (error) 1072 return (EINVAL); 1073 error = in6_embedscope(&a6[1], &addrs[1], NULL, NULL); 1074 if (error) 1075 return (EINVAL); 1076 } 1077 s = splnet(); 1078 INP_INFO_RLOCK(&tcbinfo); 1079 if (mapped == 1) 1080 inp = in_pcblookup_hash(&tcbinfo, 1081 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1082 addrs[1].sin6_port, 1083 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1084 addrs[0].sin6_port, 1085 0, NULL); 1086 else 1087 inp = in6_pcblookup_hash(&tcbinfo, &a6[1], addrs[1].sin6_port, 1088 &a6[0], addrs[0].sin6_port, 0, NULL); 1089 if (inp == NULL) { 1090 error = ENOENT; 1091 goto outunlocked; 1092 } 1093 INP_LOCK(inp); 1094 if (inp->inp_socket == NULL) { 1095 error = ENOENT; 1096 goto out; 1097 } 1098 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1099 if (error) 1100 goto out; 1101 cru2x(inp->inp_socket->so_cred, &xuc); 1102 out: 1103 INP_UNLOCK(inp); 1104 outunlocked: 1105 INP_INFO_RUNLOCK(&tcbinfo); 1106 splx(s); 1107 if (error == 0) 1108 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1109 return (error); 1110 } 1111 1112 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1113 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1114 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1115 #endif 1116 1117 1118 void 1119 tcp_ctlinput(cmd, sa, vip) 1120 int cmd; 1121 struct sockaddr *sa; 1122 void *vip; 1123 { 1124 struct ip *ip = vip; 1125 struct tcphdr *th; 1126 struct in_addr faddr; 1127 struct inpcb *inp; 1128 struct tcpcb *tp; 1129 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1130 struct icmp *icp; 1131 struct in_conninfo inc; 1132 tcp_seq icmp_tcp_seq; 1133 int mtu, s; 1134 1135 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1136 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1137 return; 1138 1139 if (cmd == PRC_MSGSIZE) 1140 notify = tcp_mtudisc; 1141 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1142 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1143 notify = tcp_drop_syn_sent; 1144 /* 1145 * Redirects don't need to be handled up here. 1146 */ 1147 else if (PRC_IS_REDIRECT(cmd)) 1148 return; 1149 /* 1150 * Source quench is depreciated. 1151 */ 1152 else if (cmd == PRC_QUENCH) 1153 return; 1154 /* 1155 * Hostdead is ugly because it goes linearly through all PCBs. 1156 * XXX: We never get this from ICMP, otherwise it makes an 1157 * excellent DoS attack on machines with many connections. 1158 */ 1159 else if (cmd == PRC_HOSTDEAD) 1160 ip = NULL; 1161 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1162 return; 1163 if (ip != NULL) { 1164 s = splnet(); 1165 icp = (struct icmp *)((caddr_t)ip 1166 - offsetof(struct icmp, icmp_ip)); 1167 th = (struct tcphdr *)((caddr_t)ip 1168 + (ip->ip_hl << 2)); 1169 INP_INFO_WLOCK(&tcbinfo); 1170 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1171 ip->ip_src, th->th_sport, 0, NULL); 1172 if (inp != NULL) { 1173 INP_LOCK(inp); 1174 if (inp->inp_socket != NULL) { 1175 icmp_tcp_seq = htonl(th->th_seq); 1176 tp = intotcpcb(inp); 1177 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1178 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1179 if (cmd == PRC_MSGSIZE) { 1180 /* 1181 * MTU discovery: 1182 * If we got a needfrag set the MTU 1183 * in the route to the suggested new 1184 * value (if given) and then notify. 1185 */ 1186 bzero(&inc, sizeof(inc)); 1187 inc.inc_flags = 0; /* IPv4 */ 1188 inc.inc_faddr = faddr; 1189 1190 mtu = ntohs(icp->icmp_nextmtu); 1191 /* 1192 * If no alternative MTU was 1193 * proposed, try the next smaller 1194 * one. ip->ip_len has already 1195 * been swapped in icmp_input(). 1196 */ 1197 if (!mtu) 1198 mtu = ip_next_mtu(ip->ip_len, 1199 1); 1200 if (mtu < max(296, (tcp_minmss) 1201 + sizeof(struct tcpiphdr))) 1202 mtu = 0; 1203 if (!mtu) 1204 mtu = tcp_mssdflt 1205 + sizeof(struct tcpiphdr); 1206 /* 1207 * Only cache the the MTU if it 1208 * is smaller than the interface 1209 * or route MTU. tcp_mtudisc() 1210 * will do right thing by itself. 1211 */ 1212 if (mtu <= tcp_maxmtu(&inc)) 1213 tcp_hc_updatemtu(&inc, mtu); 1214 } 1215 1216 inp = (*notify)(inp, inetctlerrmap[cmd]); 1217 } 1218 } 1219 if (inp != NULL) 1220 INP_UNLOCK(inp); 1221 } else { 1222 inc.inc_fport = th->th_dport; 1223 inc.inc_lport = th->th_sport; 1224 inc.inc_faddr = faddr; 1225 inc.inc_laddr = ip->ip_src; 1226 #ifdef INET6 1227 inc.inc_isipv6 = 0; 1228 #endif 1229 syncache_unreach(&inc, th); 1230 } 1231 INP_INFO_WUNLOCK(&tcbinfo); 1232 splx(s); 1233 } else 1234 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1235 } 1236 1237 #ifdef INET6 1238 void 1239 tcp6_ctlinput(cmd, sa, d) 1240 int cmd; 1241 struct sockaddr *sa; 1242 void *d; 1243 { 1244 struct tcphdr th; 1245 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1246 struct ip6_hdr *ip6; 1247 struct mbuf *m; 1248 struct ip6ctlparam *ip6cp = NULL; 1249 const struct sockaddr_in6 *sa6_src = NULL; 1250 int off; 1251 struct tcp_portonly { 1252 u_int16_t th_sport; 1253 u_int16_t th_dport; 1254 } *thp; 1255 1256 if (sa->sa_family != AF_INET6 || 1257 sa->sa_len != sizeof(struct sockaddr_in6)) 1258 return; 1259 1260 if (cmd == PRC_MSGSIZE) 1261 notify = tcp_mtudisc; 1262 else if (!PRC_IS_REDIRECT(cmd) && 1263 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1264 return; 1265 /* Source quench is depreciated. */ 1266 else if (cmd == PRC_QUENCH) 1267 return; 1268 1269 /* if the parameter is from icmp6, decode it. */ 1270 if (d != NULL) { 1271 ip6cp = (struct ip6ctlparam *)d; 1272 m = ip6cp->ip6c_m; 1273 ip6 = ip6cp->ip6c_ip6; 1274 off = ip6cp->ip6c_off; 1275 sa6_src = ip6cp->ip6c_src; 1276 } else { 1277 m = NULL; 1278 ip6 = NULL; 1279 off = 0; /* fool gcc */ 1280 sa6_src = &sa6_any; 1281 } 1282 1283 if (ip6 != NULL) { 1284 struct in_conninfo inc; 1285 /* 1286 * XXX: We assume that when IPV6 is non NULL, 1287 * M and OFF are valid. 1288 */ 1289 1290 /* check if we can safely examine src and dst ports */ 1291 if (m->m_pkthdr.len < off + sizeof(*thp)) 1292 return; 1293 1294 bzero(&th, sizeof(th)); 1295 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1296 1297 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1298 (struct sockaddr *)ip6cp->ip6c_src, 1299 th.th_sport, cmd, NULL, notify); 1300 1301 inc.inc_fport = th.th_dport; 1302 inc.inc_lport = th.th_sport; 1303 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1304 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1305 inc.inc_isipv6 = 1; 1306 INP_INFO_WLOCK(&tcbinfo); 1307 syncache_unreach(&inc, &th); 1308 INP_INFO_WUNLOCK(&tcbinfo); 1309 } else 1310 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1311 0, cmd, NULL, notify); 1312 } 1313 #endif /* INET6 */ 1314 1315 1316 /* 1317 * Following is where TCP initial sequence number generation occurs. 1318 * 1319 * There are two places where we must use initial sequence numbers: 1320 * 1. In SYN-ACK packets. 1321 * 2. In SYN packets. 1322 * 1323 * All ISNs for SYN-ACK packets are generated by the syncache. See 1324 * tcp_syncache.c for details. 1325 * 1326 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1327 * depends on this property. In addition, these ISNs should be 1328 * unguessable so as to prevent connection hijacking. To satisfy 1329 * the requirements of this situation, the algorithm outlined in 1330 * RFC 1948 is used, with only small modifications. 1331 * 1332 * Implementation details: 1333 * 1334 * Time is based off the system timer, and is corrected so that it 1335 * increases by one megabyte per second. This allows for proper 1336 * recycling on high speed LANs while still leaving over an hour 1337 * before rollover. 1338 * 1339 * As reading the *exact* system time is too expensive to be done 1340 * whenever setting up a TCP connection, we increment the time 1341 * offset in two ways. First, a small random positive increment 1342 * is added to isn_offset for each connection that is set up. 1343 * Second, the function tcp_isn_tick fires once per clock tick 1344 * and increments isn_offset as necessary so that sequence numbers 1345 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1346 * random positive increments serve only to ensure that the same 1347 * exact sequence number is never sent out twice (as could otherwise 1348 * happen when a port is recycled in less than the system tick 1349 * interval.) 1350 * 1351 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1352 * between seeding of isn_secret. This is normally set to zero, 1353 * as reseeding should not be necessary. 1354 * 1355 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1356 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1357 * general, this means holding an exclusive (write) lock. 1358 */ 1359 1360 #define ISN_BYTES_PER_SECOND 1048576 1361 #define ISN_STATIC_INCREMENT 4096 1362 #define ISN_RANDOM_INCREMENT (4096 - 1) 1363 1364 static u_char isn_secret[32]; 1365 static int isn_last_reseed; 1366 static u_int32_t isn_offset, isn_offset_old; 1367 static MD5_CTX isn_ctx; 1368 1369 tcp_seq 1370 tcp_new_isn(tp) 1371 struct tcpcb *tp; 1372 { 1373 u_int32_t md5_buffer[4]; 1374 tcp_seq new_isn; 1375 1376 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1377 INP_LOCK_ASSERT(tp->t_inpcb); 1378 1379 /* Seed if this is the first use, reseed if requested. */ 1380 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1381 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1382 < (u_int)ticks))) { 1383 read_random(&isn_secret, sizeof(isn_secret)); 1384 isn_last_reseed = ticks; 1385 } 1386 1387 /* Compute the md5 hash and return the ISN. */ 1388 MD5Init(&isn_ctx); 1389 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1390 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1391 #ifdef INET6 1392 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1393 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1394 sizeof(struct in6_addr)); 1395 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1396 sizeof(struct in6_addr)); 1397 } else 1398 #endif 1399 { 1400 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1401 sizeof(struct in_addr)); 1402 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1403 sizeof(struct in_addr)); 1404 } 1405 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1406 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1407 new_isn = (tcp_seq) md5_buffer[0]; 1408 isn_offset += ISN_STATIC_INCREMENT + 1409 (arc4random() & ISN_RANDOM_INCREMENT); 1410 new_isn += isn_offset; 1411 return (new_isn); 1412 } 1413 1414 /* 1415 * Increment the offset to the next ISN_BYTES_PER_SECOND / hz boundary 1416 * to keep time flowing at a relatively constant rate. If the random 1417 * increments have already pushed us past the projected offset, do nothing. 1418 */ 1419 static void 1420 tcp_isn_tick(xtp) 1421 void *xtp; 1422 { 1423 u_int32_t projected_offset; 1424 1425 INP_INFO_WLOCK(&tcbinfo); 1426 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1427 1428 if (projected_offset > isn_offset) 1429 isn_offset = projected_offset; 1430 1431 isn_offset_old = isn_offset; 1432 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1433 INP_INFO_WUNLOCK(&tcbinfo); 1434 } 1435 1436 /* 1437 * When a specific ICMP unreachable message is received and the 1438 * connection state is SYN-SENT, drop the connection. This behavior 1439 * is controlled by the icmp_may_rst sysctl. 1440 */ 1441 struct inpcb * 1442 tcp_drop_syn_sent(inp, errno) 1443 struct inpcb *inp; 1444 int errno; 1445 { 1446 struct tcpcb *tp = intotcpcb(inp); 1447 1448 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1449 INP_LOCK_ASSERT(inp); 1450 1451 if (tp != NULL && tp->t_state == TCPS_SYN_SENT) { 1452 tcp_drop(tp, errno); 1453 return (NULL); 1454 } 1455 return (inp); 1456 } 1457 1458 /* 1459 * When `need fragmentation' ICMP is received, update our idea of the MSS 1460 * based on the new value in the route. Also nudge TCP to send something, 1461 * since we know the packet we just sent was dropped. 1462 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1463 */ 1464 struct inpcb * 1465 tcp_mtudisc(inp, errno) 1466 struct inpcb *inp; 1467 int errno; 1468 { 1469 struct tcpcb *tp = intotcpcb(inp); 1470 struct rmxp_tao tao; 1471 struct socket *so = inp->inp_socket; 1472 u_int maxmtu; 1473 u_int romtu; 1474 int mss; 1475 #ifdef INET6 1476 int isipv6; 1477 #endif /* INET6 */ 1478 bzero(&tao, sizeof(tao)); 1479 1480 INP_LOCK_ASSERT(inp); 1481 if (tp != NULL) { 1482 #ifdef INET6 1483 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1484 #endif 1485 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1486 romtu = 1487 #ifdef INET6 1488 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1489 #endif /* INET6 */ 1490 tcp_maxmtu(&inp->inp_inc); 1491 if (!maxmtu) 1492 maxmtu = romtu; 1493 else 1494 maxmtu = min(maxmtu, romtu); 1495 if (!maxmtu) { 1496 tp->t_maxopd = tp->t_maxseg = 1497 #ifdef INET6 1498 isipv6 ? tcp_v6mssdflt : 1499 #endif /* INET6 */ 1500 tcp_mssdflt; 1501 return (inp); 1502 } 1503 mss = maxmtu - 1504 #ifdef INET6 1505 (isipv6 ? 1506 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1507 #endif /* INET6 */ 1508 sizeof(struct tcpiphdr) 1509 #ifdef INET6 1510 ) 1511 #endif /* INET6 */ 1512 ; 1513 1514 if (tcp_do_rfc1644) { 1515 tcp_hc_gettao(&inp->inp_inc, &tao); 1516 if (tao.tao_mssopt) 1517 mss = min(mss, tao.tao_mssopt); 1518 } 1519 /* 1520 * XXX - The above conditional probably violates the TCP 1521 * spec. The problem is that, since we don't know the 1522 * other end's MSS, we are supposed to use a conservative 1523 * default. But, if we do that, then MTU discovery will 1524 * never actually take place, because the conservative 1525 * default is much less than the MTUs typically seen 1526 * on the Internet today. For the moment, we'll sweep 1527 * this under the carpet. 1528 * 1529 * The conservative default might not actually be a problem 1530 * if the only case this occurs is when sending an initial 1531 * SYN with options and data to a host we've never talked 1532 * to before. Then, they will reply with an MSS value which 1533 * will get recorded and the new parameters should get 1534 * recomputed. For Further Study. 1535 */ 1536 if (tp->t_maxopd <= mss) 1537 return (inp); 1538 tp->t_maxopd = mss; 1539 1540 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1541 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1542 mss -= TCPOLEN_TSTAMP_APPA; 1543 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 1544 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1545 mss -= TCPOLEN_CC_APPA; 1546 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1547 if (mss > MCLBYTES) 1548 mss &= ~(MCLBYTES-1); 1549 #else 1550 if (mss > MCLBYTES) 1551 mss = mss / MCLBYTES * MCLBYTES; 1552 #endif 1553 if (so->so_snd.sb_hiwat < mss) 1554 mss = so->so_snd.sb_hiwat; 1555 1556 tp->t_maxseg = mss; 1557 1558 tcpstat.tcps_mturesent++; 1559 tp->t_rtttime = 0; 1560 tp->snd_nxt = tp->snd_una; 1561 tcp_output(tp); 1562 } 1563 return (inp); 1564 } 1565 1566 /* 1567 * Look-up the routing entry to the peer of this inpcb. If no route 1568 * is found and it cannot be allocated, then return NULL. This routine 1569 * is called by TCP routines that access the rmx structure and by tcp_mss 1570 * to get the interface MTU. 1571 */ 1572 u_long 1573 tcp_maxmtu(inc) 1574 struct in_conninfo *inc; 1575 { 1576 struct route sro; 1577 struct sockaddr_in *dst; 1578 struct ifnet *ifp; 1579 u_long maxmtu = 0; 1580 1581 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1582 1583 bzero(&sro, sizeof(sro)); 1584 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1585 dst = (struct sockaddr_in *)&sro.ro_dst; 1586 dst->sin_family = AF_INET; 1587 dst->sin_len = sizeof(*dst); 1588 dst->sin_addr = inc->inc_faddr; 1589 rtalloc_ign(&sro, RTF_CLONING); 1590 } 1591 if (sro.ro_rt != NULL) { 1592 ifp = sro.ro_rt->rt_ifp; 1593 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1594 maxmtu = ifp->if_mtu; 1595 else 1596 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1597 RTFREE(sro.ro_rt); 1598 } 1599 return (maxmtu); 1600 } 1601 1602 #ifdef INET6 1603 u_long 1604 tcp_maxmtu6(inc) 1605 struct in_conninfo *inc; 1606 { 1607 struct route_in6 sro6; 1608 struct ifnet *ifp; 1609 u_long maxmtu = 0; 1610 1611 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1612 1613 bzero(&sro6, sizeof(sro6)); 1614 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1615 sro6.ro_dst.sin6_family = AF_INET6; 1616 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1617 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1618 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1619 } 1620 if (sro6.ro_rt != NULL) { 1621 ifp = sro6.ro_rt->rt_ifp; 1622 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1623 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1624 else 1625 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1626 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1627 RTFREE(sro6.ro_rt); 1628 } 1629 1630 return (maxmtu); 1631 } 1632 #endif /* INET6 */ 1633 1634 #ifdef IPSEC 1635 /* compute ESP/AH header size for TCP, including outer IP header. */ 1636 size_t 1637 ipsec_hdrsiz_tcp(tp) 1638 struct tcpcb *tp; 1639 { 1640 struct inpcb *inp; 1641 struct mbuf *m; 1642 size_t hdrsiz; 1643 struct ip *ip; 1644 #ifdef INET6 1645 struct ip6_hdr *ip6; 1646 #endif 1647 struct tcphdr *th; 1648 1649 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1650 return (0); 1651 MGETHDR(m, M_DONTWAIT, MT_DATA); 1652 if (!m) 1653 return (0); 1654 1655 #ifdef INET6 1656 if ((inp->inp_vflag & INP_IPV6) != 0) { 1657 ip6 = mtod(m, struct ip6_hdr *); 1658 th = (struct tcphdr *)(ip6 + 1); 1659 m->m_pkthdr.len = m->m_len = 1660 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1661 tcpip_fillheaders(inp, ip6, th); 1662 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1663 } else 1664 #endif /* INET6 */ 1665 { 1666 ip = mtod(m, struct ip *); 1667 th = (struct tcphdr *)(ip + 1); 1668 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1669 tcpip_fillheaders(inp, ip, th); 1670 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1671 } 1672 1673 m_free(m); 1674 return (hdrsiz); 1675 } 1676 #endif /*IPSEC*/ 1677 1678 /* 1679 * Move a TCP connection into TIME_WAIT state. 1680 * tcbinfo is locked. 1681 * inp is locked, and is unlocked before returning. 1682 */ 1683 void 1684 tcp_twstart(tp) 1685 struct tcpcb *tp; 1686 { 1687 struct tcptw *tw; 1688 struct inpcb *inp; 1689 int tw_time, acknow; 1690 struct socket *so; 1691 1692 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_reset(). */ 1693 INP_LOCK_ASSERT(tp->t_inpcb); 1694 1695 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1696 if (tw == NULL) { 1697 tw = tcp_timer_2msl_tw(1); 1698 if (tw == NULL) { 1699 tcp_close(tp); 1700 return; 1701 } 1702 } 1703 inp = tp->t_inpcb; 1704 tw->tw_inpcb = inp; 1705 1706 /* 1707 * Recover last window size sent. 1708 */ 1709 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1710 1711 /* 1712 * Set t_recent if timestamps are used on the connection. 1713 */ 1714 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1715 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1716 tw->t_recent = tp->ts_recent; 1717 else 1718 tw->t_recent = 0; 1719 1720 tw->snd_nxt = tp->snd_nxt; 1721 tw->rcv_nxt = tp->rcv_nxt; 1722 tw->iss = tp->iss; 1723 tw->irs = tp->irs; 1724 tw->cc_recv = tp->cc_recv; 1725 tw->cc_send = tp->cc_send; 1726 tw->t_starttime = tp->t_starttime; 1727 tw->tw_time = 0; 1728 1729 /* XXX 1730 * If this code will 1731 * be used for fin-wait-2 state also, then we may need 1732 * a ts_recent from the last segment. 1733 */ 1734 /* Shorten TIME_WAIT [RFC-1644, p.28] */ 1735 if (tp->cc_recv != 0 && (ticks - tp->t_starttime) < tcp_msl) { 1736 tw_time = tp->t_rxtcur * TCPTV_TWTRUNC; 1737 /* For T/TCP client, force ACK now. */ 1738 acknow = 1; 1739 } else { 1740 tw_time = 2 * tcp_msl; 1741 acknow = tp->t_flags & TF_ACKNOW; 1742 } 1743 tcp_discardcb(tp); 1744 so = inp->inp_socket; 1745 ACCEPT_LOCK(); 1746 SOCK_LOCK(so); 1747 so->so_pcb = NULL; 1748 tw->tw_cred = crhold(so->so_cred); 1749 tw->tw_so_options = so->so_options; 1750 sotryfree(so); 1751 inp->inp_socket = NULL; 1752 if (acknow) 1753 tcp_twrespond(tw, TH_ACK); 1754 inp->inp_ppcb = (caddr_t)tw; 1755 inp->inp_vflag |= INP_TIMEWAIT; 1756 tcp_timer_2msl_reset(tw, tw_time); 1757 INP_UNLOCK(inp); 1758 } 1759 1760 /* 1761 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1762 * the actual rate is slightly higher due to the addition of 1763 * random positive increments. 1764 * 1765 * Most other new OSes use semi-randomized ISN values, so we 1766 * do not need to worry about them. 1767 */ 1768 #define MS_ISN_BYTES_PER_SECOND 250000 1769 1770 /* 1771 * Determine if the ISN we will generate has advanced beyond the last 1772 * sequence number used by the previous connection. If so, indicate 1773 * that it is safe to recycle this tw socket by returning 1. 1774 * 1775 * XXXRW: This function should assert the inpcb lock as it does multiple 1776 * non-atomic reads from the tcptw, but is currently called without it from 1777 * in_pcb.c:in_pcblookup_local(). 1778 */ 1779 int 1780 tcp_twrecycleable(struct tcptw *tw) 1781 { 1782 tcp_seq new_iss = tw->iss; 1783 tcp_seq new_irs = tw->irs; 1784 1785 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1786 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1787 1788 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1789 return (1); 1790 else 1791 return (0); 1792 } 1793 1794 struct tcptw * 1795 tcp_twclose(struct tcptw *tw, int reuse) 1796 { 1797 struct inpcb *inp; 1798 1799 inp = tw->tw_inpcb; 1800 INP_INFO_WLOCK_ASSERT(&tcbinfo); /* tcp_timer_2msl_stop(). */ 1801 INP_LOCK_ASSERT(inp); 1802 1803 tw->tw_inpcb = NULL; 1804 tcp_timer_2msl_stop(tw); 1805 inp->inp_ppcb = NULL; 1806 #ifdef INET6 1807 if (inp->inp_vflag & INP_IPV6PROTO) 1808 in6_pcbdetach(inp); 1809 else 1810 #endif 1811 in_pcbdetach(inp); 1812 tcpstat.tcps_closed++; 1813 crfree(tw->tw_cred); 1814 tw->tw_cred = NULL; 1815 if (reuse) 1816 return (tw); 1817 uma_zfree(tcptw_zone, tw); 1818 return (NULL); 1819 } 1820 1821 int 1822 tcp_twrespond(struct tcptw *tw, int flags) 1823 { 1824 struct inpcb *inp = tw->tw_inpcb; 1825 struct tcphdr *th; 1826 struct mbuf *m; 1827 struct ip *ip = NULL; 1828 u_int8_t *optp; 1829 u_int hdrlen, optlen; 1830 int error; 1831 #ifdef INET6 1832 struct ip6_hdr *ip6 = NULL; 1833 int isipv6 = inp->inp_inc.inc_isipv6; 1834 #endif 1835 1836 INP_LOCK_ASSERT(inp); 1837 1838 m = m_gethdr(M_DONTWAIT, MT_HEADER); 1839 if (m == NULL) 1840 return (ENOBUFS); 1841 m->m_data += max_linkhdr; 1842 1843 #ifdef MAC 1844 mac_create_mbuf_from_inpcb(inp, m); 1845 #endif 1846 1847 #ifdef INET6 1848 if (isipv6) { 1849 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1850 ip6 = mtod(m, struct ip6_hdr *); 1851 th = (struct tcphdr *)(ip6 + 1); 1852 tcpip_fillheaders(inp, ip6, th); 1853 } else 1854 #endif 1855 { 1856 hdrlen = sizeof(struct tcpiphdr); 1857 ip = mtod(m, struct ip *); 1858 th = (struct tcphdr *)(ip + 1); 1859 tcpip_fillheaders(inp, ip, th); 1860 } 1861 optp = (u_int8_t *)(th + 1); 1862 1863 /* 1864 * Send a timestamp and echo-reply if both our side and our peer 1865 * have sent timestamps in our SYN's and this is not a RST. 1866 */ 1867 if (tw->t_recent && flags == TH_ACK) { 1868 u_int32_t *lp = (u_int32_t *)optp; 1869 1870 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1871 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1872 *lp++ = htonl(ticks); 1873 *lp = htonl(tw->t_recent); 1874 optp += TCPOLEN_TSTAMP_APPA; 1875 } 1876 1877 /* 1878 * Send `CC-family' options if needed, and it's not a RST. 1879 */ 1880 if (tw->cc_recv != 0 && flags == TH_ACK) { 1881 u_int32_t *lp = (u_int32_t *)optp; 1882 1883 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC)); 1884 *lp = htonl(tw->cc_send); 1885 optp += TCPOLEN_CC_APPA; 1886 } 1887 optlen = optp - (u_int8_t *)(th + 1); 1888 1889 m->m_len = hdrlen + optlen; 1890 m->m_pkthdr.len = m->m_len; 1891 1892 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1893 1894 th->th_seq = htonl(tw->snd_nxt); 1895 th->th_ack = htonl(tw->rcv_nxt); 1896 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1897 th->th_flags = flags; 1898 th->th_win = htons(tw->last_win); 1899 1900 #ifdef INET6 1901 if (isipv6) { 1902 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1903 sizeof(struct tcphdr) + optlen); 1904 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1905 error = ip6_output(m, inp->in6p_outputopts, NULL, 1906 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1907 } else 1908 #endif 1909 { 1910 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1911 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1912 m->m_pkthdr.csum_flags = CSUM_TCP; 1913 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1914 ip->ip_len = m->m_pkthdr.len; 1915 if (path_mtu_discovery) 1916 ip->ip_off |= IP_DF; 1917 error = ip_output(m, inp->inp_options, NULL, 1918 (tw->tw_so_options & SO_DONTROUTE), NULL, inp); 1919 } 1920 if (flags & TH_ACK) 1921 tcpstat.tcps_sndacks++; 1922 else 1923 tcpstat.tcps_sndctrl++; 1924 tcpstat.tcps_sndtotal++; 1925 return (error); 1926 } 1927 1928 /* 1929 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1930 * 1931 * This code attempts to calculate the bandwidth-delay product as a 1932 * means of determining the optimal window size to maximize bandwidth, 1933 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1934 * routers. This code also does a fairly good job keeping RTTs in check 1935 * across slow links like modems. We implement an algorithm which is very 1936 * similar (but not meant to be) TCP/Vegas. The code operates on the 1937 * transmitter side of a TCP connection and so only effects the transmit 1938 * side of the connection. 1939 * 1940 * BACKGROUND: TCP makes no provision for the management of buffer space 1941 * at the end points or at the intermediate routers and switches. A TCP 1942 * stream, whether using NewReno or not, will eventually buffer as 1943 * many packets as it is able and the only reason this typically works is 1944 * due to the fairly small default buffers made available for a connection 1945 * (typicaly 16K or 32K). As machines use larger windows and/or window 1946 * scaling it is now fairly easy for even a single TCP connection to blow-out 1947 * all available buffer space not only on the local interface, but on 1948 * intermediate routers and switches as well. NewReno makes a misguided 1949 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1950 * then backing off, then steadily increasing the window again until another 1951 * failure occurs, ad-infinitum. This results in terrible oscillation that 1952 * is only made worse as network loads increase and the idea of intentionally 1953 * blowing out network buffers is, frankly, a terrible way to manage network 1954 * resources. 1955 * 1956 * It is far better to limit the transmit window prior to the failure 1957 * condition being achieved. There are two general ways to do this: First 1958 * you can 'scan' through different transmit window sizes and locate the 1959 * point where the RTT stops increasing, indicating that you have filled the 1960 * pipe, then scan backwards until you note that RTT stops decreasing, then 1961 * repeat ad-infinitum. This method works in principle but has severe 1962 * implementation issues due to RTT variances, timer granularity, and 1963 * instability in the algorithm which can lead to many false positives and 1964 * create oscillations as well as interact badly with other TCP streams 1965 * implementing the same algorithm. 1966 * 1967 * The second method is to limit the window to the bandwidth delay product 1968 * of the link. This is the method we implement. RTT variances and our 1969 * own manipulation of the congestion window, bwnd, can potentially 1970 * destabilize the algorithm. For this reason we have to stabilize the 1971 * elements used to calculate the window. We do this by using the minimum 1972 * observed RTT, the long term average of the observed bandwidth, and 1973 * by adding two segments worth of slop. It isn't perfect but it is able 1974 * to react to changing conditions and gives us a very stable basis on 1975 * which to extend the algorithm. 1976 */ 1977 void 1978 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1979 { 1980 u_long bw; 1981 u_long bwnd; 1982 int save_ticks; 1983 1984 INP_LOCK_ASSERT(tp->t_inpcb); 1985 1986 /* 1987 * If inflight_enable is disabled in the middle of a tcp connection, 1988 * make sure snd_bwnd is effectively disabled. 1989 */ 1990 if (tcp_inflight_enable == 0) { 1991 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1992 tp->snd_bandwidth = 0; 1993 return; 1994 } 1995 1996 /* 1997 * Figure out the bandwidth. Due to the tick granularity this 1998 * is a very rough number and it MUST be averaged over a fairly 1999 * long period of time. XXX we need to take into account a link 2000 * that is not using all available bandwidth, but for now our 2001 * slop will ramp us up if this case occurs and the bandwidth later 2002 * increases. 2003 * 2004 * Note: if ticks rollover 'bw' may wind up negative. We must 2005 * effectively reset t_bw_rtttime for this case. 2006 */ 2007 save_ticks = ticks; 2008 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 2009 return; 2010 2011 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 2012 (save_ticks - tp->t_bw_rtttime); 2013 tp->t_bw_rtttime = save_ticks; 2014 tp->t_bw_rtseq = ack_seq; 2015 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 2016 return; 2017 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 2018 2019 tp->snd_bandwidth = bw; 2020 2021 /* 2022 * Calculate the semi-static bandwidth delay product, plus two maximal 2023 * segments. The additional slop puts us squarely in the sweet 2024 * spot and also handles the bandwidth run-up case and stabilization. 2025 * Without the slop we could be locking ourselves into a lower 2026 * bandwidth. 2027 * 2028 * Situations Handled: 2029 * (1) Prevents over-queueing of packets on LANs, especially on 2030 * high speed LANs, allowing larger TCP buffers to be 2031 * specified, and also does a good job preventing 2032 * over-queueing of packets over choke points like modems 2033 * (at least for the transmit side). 2034 * 2035 * (2) Is able to handle changing network loads (bandwidth 2036 * drops so bwnd drops, bandwidth increases so bwnd 2037 * increases). 2038 * 2039 * (3) Theoretically should stabilize in the face of multiple 2040 * connections implementing the same algorithm (this may need 2041 * a little work). 2042 * 2043 * (4) Stability value (defaults to 20 = 2 maximal packets) can 2044 * be adjusted with a sysctl but typically only needs to be 2045 * on very slow connections. A value no smaller then 5 2046 * should be used, but only reduce this default if you have 2047 * no other choice. 2048 */ 2049 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 2050 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 2051 #undef USERTT 2052 2053 if (tcp_inflight_debug > 0) { 2054 static int ltime; 2055 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 2056 ltime = ticks; 2057 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 2058 tp, 2059 bw, 2060 tp->t_rttbest, 2061 tp->t_srtt, 2062 bwnd 2063 ); 2064 } 2065 } 2066 if ((long)bwnd < tcp_inflight_min) 2067 bwnd = tcp_inflight_min; 2068 if (bwnd > tcp_inflight_max) 2069 bwnd = tcp_inflight_max; 2070 if ((long)bwnd < tp->t_maxseg * 2) 2071 bwnd = tp->t_maxseg * 2; 2072 tp->snd_bwnd = bwnd; 2073 } 2074 2075 #ifdef TCP_SIGNATURE 2076 /* 2077 * Callback function invoked by m_apply() to digest TCP segment data 2078 * contained within an mbuf chain. 2079 */ 2080 static int 2081 tcp_signature_apply(void *fstate, void *data, u_int len) 2082 { 2083 2084 MD5Update(fstate, (u_char *)data, len); 2085 return (0); 2086 } 2087 2088 /* 2089 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 2090 * 2091 * Parameters: 2092 * m pointer to head of mbuf chain 2093 * off0 offset to TCP header within the mbuf chain 2094 * len length of TCP segment data, excluding options 2095 * optlen length of TCP segment options 2096 * buf pointer to storage for computed MD5 digest 2097 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 2098 * 2099 * We do this over ip, tcphdr, segment data, and the key in the SADB. 2100 * When called from tcp_input(), we can be sure that th_sum has been 2101 * zeroed out and verified already. 2102 * 2103 * This function is for IPv4 use only. Calling this function with an 2104 * IPv6 packet in the mbuf chain will yield undefined results. 2105 * 2106 * Return 0 if successful, otherwise return -1. 2107 * 2108 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 2109 * search with the destination IP address, and a 'magic SPI' to be 2110 * determined by the application. This is hardcoded elsewhere to 1179 2111 * right now. Another branch of this code exists which uses the SPD to 2112 * specify per-application flows but it is unstable. 2113 */ 2114 int 2115 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 2116 u_char *buf, u_int direction) 2117 { 2118 union sockaddr_union dst; 2119 struct ippseudo ippseudo; 2120 MD5_CTX ctx; 2121 int doff; 2122 struct ip *ip; 2123 struct ipovly *ipovly; 2124 struct secasvar *sav; 2125 struct tcphdr *th; 2126 u_short savecsum; 2127 2128 KASSERT(m != NULL, ("NULL mbuf chain")); 2129 KASSERT(buf != NULL, ("NULL signature pointer")); 2130 2131 /* Extract the destination from the IP header in the mbuf. */ 2132 ip = mtod(m, struct ip *); 2133 bzero(&dst, sizeof(union sockaddr_union)); 2134 dst.sa.sa_len = sizeof(struct sockaddr_in); 2135 dst.sa.sa_family = AF_INET; 2136 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 2137 ip->ip_src : ip->ip_dst; 2138 2139 /* Look up an SADB entry which matches the address of the peer. */ 2140 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2141 if (sav == NULL) { 2142 printf("%s: SADB lookup failed for %s\n", __func__, 2143 inet_ntoa(dst.sin.sin_addr)); 2144 return (EINVAL); 2145 } 2146 2147 MD5Init(&ctx); 2148 ipovly = (struct ipovly *)ip; 2149 th = (struct tcphdr *)((u_char *)ip + off0); 2150 doff = off0 + sizeof(struct tcphdr) + optlen; 2151 2152 /* 2153 * Step 1: Update MD5 hash with IP pseudo-header. 2154 * 2155 * XXX The ippseudo header MUST be digested in network byte order, 2156 * or else we'll fail the regression test. Assume all fields we've 2157 * been doing arithmetic on have been in host byte order. 2158 * XXX One cannot depend on ipovly->ih_len here. When called from 2159 * tcp_output(), the underlying ip_len member has not yet been set. 2160 */ 2161 ippseudo.ippseudo_src = ipovly->ih_src; 2162 ippseudo.ippseudo_dst = ipovly->ih_dst; 2163 ippseudo.ippseudo_pad = 0; 2164 ippseudo.ippseudo_p = IPPROTO_TCP; 2165 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2166 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2167 2168 /* 2169 * Step 2: Update MD5 hash with TCP header, excluding options. 2170 * The TCP checksum must be set to zero. 2171 */ 2172 savecsum = th->th_sum; 2173 th->th_sum = 0; 2174 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2175 th->th_sum = savecsum; 2176 2177 /* 2178 * Step 3: Update MD5 hash with TCP segment data. 2179 * Use m_apply() to avoid an early m_pullup(). 2180 */ 2181 if (len > 0) 2182 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2183 2184 /* 2185 * Step 4: Update MD5 hash with shared secret. 2186 */ 2187 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2188 MD5Final(buf, &ctx); 2189 2190 key_sa_recordxfer(sav, m); 2191 KEY_FREESAV(&sav); 2192 return (0); 2193 } 2194 #endif /* TCP_SIGNATURE */ 2195 2196 static int 2197 sysctl_drop(SYSCTL_HANDLER_ARGS) 2198 { 2199 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2200 struct sockaddr_storage addrs[2]; 2201 struct inpcb *inp; 2202 struct tcpcb *tp; 2203 struct tcptw *tw; 2204 struct sockaddr_in *fin, *lin; 2205 #ifdef INET6 2206 struct sockaddr_in6 *fin6, *lin6; 2207 struct in6_addr f6, l6; 2208 #endif 2209 int error; 2210 2211 inp = NULL; 2212 fin = lin = NULL; 2213 #ifdef INET6 2214 fin6 = lin6 = NULL; 2215 #endif 2216 error = 0; 2217 2218 if (req->oldptr != NULL || req->oldlen != 0) 2219 return (EINVAL); 2220 if (req->newptr == NULL) 2221 return (EPERM); 2222 if (req->newlen < sizeof(addrs)) 2223 return (ENOMEM); 2224 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2225 if (error) 2226 return (error); 2227 2228 switch (addrs[0].ss_family) { 2229 #ifdef INET6 2230 case AF_INET6: 2231 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2232 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2233 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2234 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2235 return (EINVAL); 2236 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2237 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2238 return (EINVAL); 2239 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2240 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2241 fin = (struct sockaddr_in *)&addrs[0]; 2242 lin = (struct sockaddr_in *)&addrs[1]; 2243 break; 2244 } 2245 error = in6_embedscope(&f6, fin6, NULL, NULL); 2246 if (error) 2247 return (EINVAL); 2248 error = in6_embedscope(&l6, lin6, NULL, NULL); 2249 if (error) 2250 return (EINVAL); 2251 break; 2252 #endif 2253 case AF_INET: 2254 fin = (struct sockaddr_in *)&addrs[0]; 2255 lin = (struct sockaddr_in *)&addrs[1]; 2256 if (fin->sin_len != sizeof(struct sockaddr_in) || 2257 lin->sin_len != sizeof(struct sockaddr_in)) 2258 return (EINVAL); 2259 break; 2260 default: 2261 return (EINVAL); 2262 } 2263 INP_INFO_WLOCK(&tcbinfo); 2264 switch (addrs[0].ss_family) { 2265 #ifdef INET6 2266 case AF_INET6: 2267 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2268 &l6, lin6->sin6_port, 0, NULL); 2269 break; 2270 #endif 2271 case AF_INET: 2272 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2273 lin->sin_addr, lin->sin_port, 0, NULL); 2274 break; 2275 } 2276 if (inp != NULL) { 2277 INP_LOCK(inp); 2278 if ((tw = intotw(inp)) && 2279 (inp->inp_vflag & INP_TIMEWAIT) != 0) { 2280 (void) tcp_twclose(tw, 0); 2281 } else if ((tp = intotcpcb(inp)) && 2282 ((inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 2283 tp = tcp_drop(tp, ECONNABORTED); 2284 if (tp != NULL) 2285 INP_UNLOCK(inp); 2286 } else 2287 INP_UNLOCK(inp); 2288 } else 2289 error = ESRCH; 2290 INP_INFO_WUNLOCK(&tcbinfo); 2291 return (error); 2292 } 2293 2294 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2295 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2296 0, sysctl_drop, "", "Drop TCP connection");
Cache object: e2a783cee173ed4aa7b3db30a6275c0a
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