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 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_compat.h" 36 #include "opt_inet.h" 37 #include "opt_inet6.h" 38 #include "opt_ipsec.h" 39 #include "opt_mac.h" 40 #include "opt_tcpdebug.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/callout.h> 45 #include <sys/kernel.h> 46 #include <sys/sysctl.h> 47 #include <sys/malloc.h> 48 #include <sys/mbuf.h> 49 #ifdef INET6 50 #include <sys/domain.h> 51 #endif 52 #include <sys/priv.h> 53 #include <sys/proc.h> 54 #include <sys/socket.h> 55 #include <sys/socketvar.h> 56 #include <sys/protosw.h> 57 #include <sys/random.h> 58 59 #include <vm/uma.h> 60 61 #include <net/route.h> 62 #include <net/if.h> 63 64 #include <netinet/in.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/ip.h> 67 #ifdef INET6 68 #include <netinet/ip6.h> 69 #endif 70 #include <netinet/in_pcb.h> 71 #ifdef INET6 72 #include <netinet6/in6_pcb.h> 73 #endif 74 #include <netinet/in_var.h> 75 #include <netinet/ip_var.h> 76 #ifdef INET6 77 #include <netinet6/ip6_var.h> 78 #include <netinet6/scope6_var.h> 79 #include <netinet6/nd6.h> 80 #endif 81 #include <netinet/ip_icmp.h> 82 #include <netinet/tcp.h> 83 #include <netinet/tcp_fsm.h> 84 #include <netinet/tcp_seq.h> 85 #include <netinet/tcp_timer.h> 86 #include <netinet/tcp_var.h> 87 #include <netinet/tcp_syncache.h> 88 #ifdef INET6 89 #include <netinet6/tcp6_var.h> 90 #endif 91 #include <netinet/tcpip.h> 92 #ifdef TCPDEBUG 93 #include <netinet/tcp_debug.h> 94 #endif 95 #include <netinet6/ip6protosw.h> 96 97 #ifdef IPSEC 98 #include <netipsec/ipsec.h> 99 #include <netipsec/xform.h> 100 #ifdef INET6 101 #include <netipsec/ipsec6.h> 102 #endif 103 #include <netipsec/key.h> 104 #endif /*IPSEC*/ 105 106 #include <machine/in_cksum.h> 107 #include <sys/md5.h> 108 109 #include <security/mac/mac_framework.h> 110 111 int tcp_mssdflt = TCP_MSS; 112 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 113 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size"); 114 115 #ifdef INET6 116 int tcp_v6mssdflt = TCP6_MSS; 117 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 118 CTLFLAG_RW, &tcp_v6mssdflt , 0, 119 "Default TCP Maximum Segment Size for IPv6"); 120 #endif 121 122 /* 123 * Minimum MSS we accept and use. This prevents DoS attacks where 124 * we are forced to a ridiculous low MSS like 20 and send hundreds 125 * of packets instead of one. The effect scales with the available 126 * bandwidth and quickly saturates the CPU and network interface 127 * with packet generation and sending. Set to zero to disable MINMSS 128 * checking. This setting prevents us from sending too small packets. 129 */ 130 int tcp_minmss = TCP_MINMSS; 131 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 132 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 133 134 int tcp_do_rfc1323 = 1; 135 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 136 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions"); 137 138 static int tcp_log_debug = 0; 139 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW, 140 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments"); 141 142 static int tcp_tcbhashsize = 0; 143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 144 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 145 146 static int do_tcpdrain = 1; 147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, 148 &do_tcpdrain, 0, 149 "Enable tcp_drain routine for extra help when low on mbufs"); 150 151 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 152 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 153 154 static int icmp_may_rst = 1; 155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, 156 &icmp_may_rst, 0, 157 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 158 159 static int tcp_isn_reseed_interval = 0; 160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 161 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 162 163 /* 164 * TCP bandwidth limiting sysctls. Note that the default lower bound of 165 * 1024 exists only for debugging. A good production default would be 166 * something like 6100. 167 */ 168 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 169 "TCP inflight data limiting"); 170 171 static int tcp_inflight_enable = 1; 172 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 173 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 174 175 static int tcp_inflight_debug = 0; 176 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 177 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 178 179 static int tcp_inflight_rttthresh; 180 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 181 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 182 "RTT threshold below which inflight will deactivate itself"); 183 184 static int tcp_inflight_min = 6144; 185 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 186 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 187 188 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 189 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 190 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 191 192 static int tcp_inflight_stab = 20; 193 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 194 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 195 196 uma_zone_t sack_hole_zone; 197 198 static struct inpcb *tcp_notify(struct inpcb *, int); 199 static void tcp_isn_tick(void *); 200 201 /* 202 * Target size of TCP PCB hash tables. Must be a power of two. 203 * 204 * Note that this can be overridden by the kernel environment 205 * variable net.inet.tcp.tcbhashsize 206 */ 207 #ifndef TCBHASHSIZE 208 #define TCBHASHSIZE 512 209 #endif 210 211 /* 212 * XXX 213 * Callouts should be moved into struct tcp directly. They are currently 214 * separate because the tcpcb structure is exported to userland for sysctl 215 * parsing purposes, which do not know about callouts. 216 */ 217 struct tcpcb_mem { 218 struct tcpcb tcb; 219 struct tcp_timer tt; 220 }; 221 222 static uma_zone_t tcpcb_zone; 223 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); 224 struct callout isn_callout; 225 static struct mtx isn_mtx; 226 227 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) 228 #define ISN_LOCK() mtx_lock(&isn_mtx) 229 #define ISN_UNLOCK() mtx_unlock(&isn_mtx) 230 231 /* 232 * TCP initialization. 233 */ 234 static void 235 tcp_zone_change(void *tag) 236 { 237 238 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 239 uma_zone_set_max(tcpcb_zone, maxsockets); 240 tcp_tw_zone_change(); 241 } 242 243 static int 244 tcp_inpcb_init(void *mem, int size, int flags) 245 { 246 struct inpcb *inp = mem; 247 248 INP_LOCK_INIT(inp, "inp", "tcpinp"); 249 return (0); 250 } 251 252 void 253 tcp_init(void) 254 { 255 256 int hashsize = TCBHASHSIZE; 257 tcp_delacktime = TCPTV_DELACK; 258 tcp_keepinit = TCPTV_KEEP_INIT; 259 tcp_keepidle = TCPTV_KEEP_IDLE; 260 tcp_keepintvl = TCPTV_KEEPINTVL; 261 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 262 tcp_msl = TCPTV_MSL; 263 tcp_rexmit_min = TCPTV_MIN; 264 if (tcp_rexmit_min < 1) 265 tcp_rexmit_min = 1; 266 tcp_rexmit_slop = TCPTV_CPU_VAR; 267 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 268 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT; 269 270 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 271 LIST_INIT(&tcb); 272 tcbinfo.ipi_listhead = &tcb; 273 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 274 if (!powerof2(hashsize)) { 275 printf("WARNING: TCB hash size not a power of 2\n"); 276 hashsize = 512; /* safe default */ 277 } 278 tcp_tcbhashsize = hashsize; 279 tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB, 280 &tcbinfo.ipi_hashmask); 281 tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB, 282 &tcbinfo.ipi_porthashmask); 283 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 284 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 285 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 286 #ifdef INET6 287 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 288 #else /* INET6 */ 289 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 290 #endif /* INET6 */ 291 if (max_protohdr < TCP_MINPROTOHDR) 292 max_protohdr = TCP_MINPROTOHDR; 293 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 294 panic("tcp_init"); 295 #undef TCP_MINPROTOHDR 296 /* 297 * These have to be type stable for the benefit of the timers. 298 */ 299 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 300 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 301 uma_zone_set_max(tcpcb_zone, maxsockets); 302 tcp_tw_init(); 303 syncache_init(); 304 tcp_hc_init(); 305 tcp_reass_init(); 306 ISN_LOCK_INIT(); 307 callout_init(&isn_callout, CALLOUT_MPSAFE); 308 tcp_isn_tick(NULL); 309 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 310 SHUTDOWN_PRI_DEFAULT); 311 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 312 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 313 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, 314 EVENTHANDLER_PRI_ANY); 315 } 316 317 void 318 tcp_fini(void *xtp) 319 { 320 321 callout_stop(&isn_callout); 322 } 323 324 /* 325 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 326 * tcp_template used to store this data in mbufs, but we now recopy it out 327 * of the tcpcb each time to conserve mbufs. 328 */ 329 void 330 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 331 { 332 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 333 334 INP_LOCK_ASSERT(inp); 335 336 #ifdef INET6 337 if ((inp->inp_vflag & INP_IPV6) != 0) { 338 struct ip6_hdr *ip6; 339 340 ip6 = (struct ip6_hdr *)ip_ptr; 341 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 342 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 343 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 344 (IPV6_VERSION & IPV6_VERSION_MASK); 345 ip6->ip6_nxt = IPPROTO_TCP; 346 ip6->ip6_plen = sizeof(struct tcphdr); 347 ip6->ip6_src = inp->in6p_laddr; 348 ip6->ip6_dst = inp->in6p_faddr; 349 } else 350 #endif 351 { 352 struct ip *ip; 353 354 ip = (struct ip *)ip_ptr; 355 ip->ip_v = IPVERSION; 356 ip->ip_hl = 5; 357 ip->ip_tos = inp->inp_ip_tos; 358 ip->ip_len = 0; 359 ip->ip_id = 0; 360 ip->ip_off = 0; 361 ip->ip_ttl = inp->inp_ip_ttl; 362 ip->ip_sum = 0; 363 ip->ip_p = IPPROTO_TCP; 364 ip->ip_src = inp->inp_laddr; 365 ip->ip_dst = inp->inp_faddr; 366 } 367 th->th_sport = inp->inp_lport; 368 th->th_dport = inp->inp_fport; 369 th->th_seq = 0; 370 th->th_ack = 0; 371 th->th_x2 = 0; 372 th->th_off = 5; 373 th->th_flags = 0; 374 th->th_win = 0; 375 th->th_urp = 0; 376 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 377 } 378 379 /* 380 * Create template to be used to send tcp packets on a connection. 381 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 382 * use for this function is in keepalives, which use tcp_respond. 383 */ 384 struct tcptemp * 385 tcpip_maketemplate(struct inpcb *inp) 386 { 387 struct mbuf *m; 388 struct tcptemp *n; 389 390 m = m_get(M_DONTWAIT, MT_DATA); 391 if (m == NULL) 392 return (0); 393 m->m_len = sizeof(struct tcptemp); 394 n = mtod(m, struct tcptemp *); 395 396 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 397 return (n); 398 } 399 400 /* 401 * Send a single message to the TCP at address specified by 402 * the given TCP/IP header. If m == NULL, then we make a copy 403 * of the tcpiphdr at ti and send directly to the addressed host. 404 * This is used to force keep alive messages out using the TCP 405 * template for a connection. If flags are given then we send 406 * a message back to the TCP which originated the * segment ti, 407 * and discard the mbuf containing it and any other attached mbufs. 408 * 409 * In any case the ack and sequence number of the transmitted 410 * segment are as specified by the parameters. 411 * 412 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 413 */ 414 void 415 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 416 tcp_seq ack, tcp_seq seq, int flags) 417 { 418 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_LOCK_ASSERT(inp); 441 } else 442 inp = NULL; 443 444 if (tp != NULL) { 445 if (!(flags & TH_RST)) { 446 win = sbspace(&inp->inp_socket->so_rcv); 447 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 448 win = (long)TCP_MAXWIN << tp->rcv_scale; 449 } 450 } 451 if (m == NULL) { 452 m = m_gethdr(M_DONTWAIT, MT_DATA); 453 if (m == NULL) 454 return; 455 tlen = 0; 456 m->m_data += max_linkhdr; 457 #ifdef INET6 458 if (isipv6) { 459 bcopy((caddr_t)ip6, mtod(m, caddr_t), 460 sizeof(struct ip6_hdr)); 461 ip6 = mtod(m, struct ip6_hdr *); 462 nth = (struct tcphdr *)(ip6 + 1); 463 } else 464 #endif /* INET6 */ 465 { 466 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 467 ip = mtod(m, struct ip *); 468 nth = (struct tcphdr *)(ip + 1); 469 } 470 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 471 flags = TH_ACK; 472 } else { 473 m_freem(m->m_next); 474 m->m_next = NULL; 475 m->m_data = (caddr_t)ipgen; 476 /* m_len is set later */ 477 tlen = 0; 478 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 479 #ifdef INET6 480 if (isipv6) { 481 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 482 nth = (struct tcphdr *)(ip6 + 1); 483 } else 484 #endif /* INET6 */ 485 { 486 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 487 nth = (struct tcphdr *)(ip + 1); 488 } 489 if (th != nth) { 490 /* 491 * this is usually a case when an extension header 492 * exists between the IPv6 header and the 493 * TCP header. 494 */ 495 nth->th_sport = th->th_sport; 496 nth->th_dport = th->th_dport; 497 } 498 xchg(nth->th_dport, nth->th_sport, n_short); 499 #undef xchg 500 } 501 #ifdef INET6 502 if (isipv6) { 503 ip6->ip6_flow = 0; 504 ip6->ip6_vfc = IPV6_VERSION; 505 ip6->ip6_nxt = IPPROTO_TCP; 506 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 507 tlen)); 508 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 509 } else 510 #endif 511 { 512 tlen += sizeof (struct tcpiphdr); 513 ip->ip_len = tlen; 514 ip->ip_ttl = ip_defttl; 515 if (path_mtu_discovery) 516 ip->ip_off |= IP_DF; 517 } 518 m->m_len = tlen; 519 m->m_pkthdr.len = tlen; 520 m->m_pkthdr.rcvif = NULL; 521 #ifdef MAC 522 if (inp != NULL) { 523 /* 524 * Packet is associated with a socket, so allow the 525 * label of the response to reflect the socket label. 526 */ 527 INP_LOCK_ASSERT(inp); 528 mac_create_mbuf_from_inpcb(inp, m); 529 } else { 530 /* 531 * Packet is not associated with a socket, so possibly 532 * update the label in place. 533 */ 534 mac_reflect_mbuf_tcp(m); 535 } 536 #endif 537 nth->th_seq = htonl(seq); 538 nth->th_ack = htonl(ack); 539 nth->th_x2 = 0; 540 nth->th_off = sizeof (struct tcphdr) >> 2; 541 nth->th_flags = flags; 542 if (tp != NULL) 543 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 544 else 545 nth->th_win = htons((u_short)win); 546 nth->th_urp = 0; 547 #ifdef INET6 548 if (isipv6) { 549 nth->th_sum = 0; 550 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 551 sizeof(struct ip6_hdr), 552 tlen - sizeof(struct ip6_hdr)); 553 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 554 NULL, NULL); 555 } else 556 #endif /* INET6 */ 557 { 558 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 559 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 560 m->m_pkthdr.csum_flags = CSUM_TCP; 561 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 562 } 563 #ifdef TCPDEBUG 564 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 565 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 566 #endif 567 #ifdef INET6 568 if (isipv6) 569 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 570 else 571 #endif /* INET6 */ 572 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 573 } 574 575 /* 576 * Create a new TCP control block, making an 577 * empty reassembly queue and hooking it to the argument 578 * protocol control block. The `inp' parameter must have 579 * come from the zone allocator set up in tcp_init(). 580 */ 581 struct tcpcb * 582 tcp_newtcpcb(struct inpcb *inp) 583 { 584 struct tcpcb_mem *tm; 585 struct tcpcb *tp; 586 #ifdef INET6 587 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 588 #endif /* INET6 */ 589 590 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 591 if (tm == NULL) 592 return (NULL); 593 tp = &tm->tcb; 594 tp->t_timers = &tm->tt; 595 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 596 tp->t_maxseg = tp->t_maxopd = 597 #ifdef INET6 598 isipv6 ? tcp_v6mssdflt : 599 #endif /* INET6 */ 600 tcp_mssdflt; 601 602 /* Set up our timeouts. */ 603 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE); 604 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE); 605 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE); 606 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE); 607 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE); 608 609 if (tcp_do_rfc1323) 610 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 611 if (tcp_do_sack) 612 tp->t_flags |= TF_SACK_PERMIT; 613 TAILQ_INIT(&tp->snd_holes); 614 tp->t_inpcb = inp; /* XXX */ 615 /* 616 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 617 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 618 * reasonable initial retransmit time. 619 */ 620 tp->t_srtt = TCPTV_SRTTBASE; 621 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 622 tp->t_rttmin = tcp_rexmit_min; 623 tp->t_rxtcur = TCPTV_RTOBASE; 624 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 625 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 626 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 627 tp->t_rcvtime = ticks; 628 tp->t_bw_rtttime = ticks; 629 /* 630 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 631 * because the socket may be bound to an IPv6 wildcard address, 632 * which may match an IPv4-mapped IPv6 address. 633 */ 634 inp->inp_ip_ttl = ip_defttl; 635 inp->inp_ppcb = tp; 636 return (tp); /* XXX */ 637 } 638 639 /* 640 * Drop a TCP connection, reporting 641 * the specified error. If connection is synchronized, 642 * then send a RST to peer. 643 */ 644 struct tcpcb * 645 tcp_drop(struct tcpcb *tp, int errno) 646 { 647 struct socket *so = tp->t_inpcb->inp_socket; 648 649 INP_INFO_WLOCK_ASSERT(&tcbinfo); 650 INP_LOCK_ASSERT(tp->t_inpcb); 651 652 if (TCPS_HAVERCVDSYN(tp->t_state)) { 653 tp->t_state = TCPS_CLOSED; 654 (void) tcp_output(tp); 655 tcpstat.tcps_drops++; 656 } else 657 tcpstat.tcps_conndrops++; 658 if (errno == ETIMEDOUT && tp->t_softerror) 659 errno = tp->t_softerror; 660 so->so_error = errno; 661 return (tcp_close(tp)); 662 } 663 664 void 665 tcp_discardcb(struct tcpcb *tp) 666 { 667 struct tseg_qent *q; 668 struct inpcb *inp = tp->t_inpcb; 669 struct socket *so = inp->inp_socket; 670 #ifdef INET6 671 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 672 #endif /* INET6 */ 673 674 INP_LOCK_ASSERT(inp); 675 676 /* 677 * Make sure that all of our timers are stopped before we 678 * delete the PCB. 679 */ 680 callout_stop(&tp->t_timers->tt_rexmt); 681 callout_stop(&tp->t_timers->tt_persist); 682 callout_stop(&tp->t_timers->tt_keep); 683 callout_stop(&tp->t_timers->tt_2msl); 684 callout_stop(&tp->t_timers->tt_delack); 685 686 /* 687 * If we got enough samples through the srtt filter, 688 * save the rtt and rttvar in the routing entry. 689 * 'Enough' is arbitrarily defined as 4 rtt samples. 690 * 4 samples is enough for the srtt filter to converge 691 * to within enough % of the correct value; fewer samples 692 * and we could save a bogus rtt. The danger is not high 693 * as tcp quickly recovers from everything. 694 * XXX: Works very well but needs some more statistics! 695 */ 696 if (tp->t_rttupdated >= 4) { 697 struct hc_metrics_lite metrics; 698 u_long ssthresh; 699 700 bzero(&metrics, sizeof(metrics)); 701 /* 702 * Update the ssthresh always when the conditions below 703 * are satisfied. This gives us better new start value 704 * for the congestion avoidance for new connections. 705 * ssthresh is only set if packet loss occured on a session. 706 * 707 * XXXRW: 'so' may be NULL here, and/or socket buffer may be 708 * being torn down. Ideally this code would not use 'so'. 709 */ 710 ssthresh = tp->snd_ssthresh; 711 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 712 /* 713 * convert the limit from user data bytes to 714 * packets then to packet data bytes. 715 */ 716 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 717 if (ssthresh < 2) 718 ssthresh = 2; 719 ssthresh *= (u_long)(tp->t_maxseg + 720 #ifdef INET6 721 (isipv6 ? sizeof (struct ip6_hdr) + 722 sizeof (struct tcphdr) : 723 #endif 724 sizeof (struct tcpiphdr) 725 #ifdef INET6 726 ) 727 #endif 728 ); 729 } else 730 ssthresh = 0; 731 metrics.rmx_ssthresh = ssthresh; 732 733 metrics.rmx_rtt = tp->t_srtt; 734 metrics.rmx_rttvar = tp->t_rttvar; 735 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 736 metrics.rmx_bandwidth = tp->snd_bandwidth; 737 metrics.rmx_cwnd = tp->snd_cwnd; 738 metrics.rmx_sendpipe = 0; 739 metrics.rmx_recvpipe = 0; 740 741 tcp_hc_update(&inp->inp_inc, &metrics); 742 } 743 744 /* free the reassembly queue, if any */ 745 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 746 LIST_REMOVE(q, tqe_q); 747 m_freem(q->tqe_m); 748 uma_zfree(tcp_reass_zone, q); 749 tp->t_segqlen--; 750 tcp_reass_qsize--; 751 } 752 tcp_free_sackholes(tp); 753 inp->inp_ppcb = NULL; 754 tp->t_inpcb = NULL; 755 uma_zfree(tcpcb_zone, tp); 756 } 757 758 /* 759 * Attempt to close a TCP control block, marking it as dropped, and freeing 760 * the socket if we hold the only reference. 761 */ 762 struct tcpcb * 763 tcp_close(struct tcpcb *tp) 764 { 765 struct inpcb *inp = tp->t_inpcb; 766 struct socket *so; 767 768 INP_INFO_WLOCK_ASSERT(&tcbinfo); 769 INP_LOCK_ASSERT(inp); 770 771 in_pcbdrop(inp); 772 tcpstat.tcps_closed++; 773 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 774 so = inp->inp_socket; 775 soisdisconnected(so); 776 if (inp->inp_vflag & INP_SOCKREF) { 777 KASSERT(so->so_state & SS_PROTOREF, 778 ("tcp_close: !SS_PROTOREF")); 779 inp->inp_vflag &= ~INP_SOCKREF; 780 INP_UNLOCK(inp); 781 ACCEPT_LOCK(); 782 SOCK_LOCK(so); 783 so->so_state &= ~SS_PROTOREF; 784 sofree(so); 785 return (NULL); 786 } 787 return (tp); 788 } 789 790 void 791 tcp_drain(void) 792 { 793 794 if (do_tcpdrain) { 795 struct inpcb *inpb; 796 struct tcpcb *tcpb; 797 struct tseg_qent *te; 798 799 /* 800 * Walk the tcpbs, if existing, and flush the reassembly queue, 801 * if there is one... 802 * XXX: The "Net/3" implementation doesn't imply that the TCP 803 * reassembly queue should be flushed, but in a situation 804 * where we're really low on mbufs, this is potentially 805 * usefull. 806 */ 807 INP_INFO_RLOCK(&tcbinfo); 808 LIST_FOREACH(inpb, tcbinfo.ipi_listhead, inp_list) { 809 if (inpb->inp_vflag & INP_TIMEWAIT) 810 continue; 811 INP_LOCK(inpb); 812 if ((tcpb = intotcpcb(inpb)) != NULL) { 813 while ((te = LIST_FIRST(&tcpb->t_segq)) 814 != NULL) { 815 LIST_REMOVE(te, tqe_q); 816 m_freem(te->tqe_m); 817 uma_zfree(tcp_reass_zone, te); 818 tcpb->t_segqlen--; 819 tcp_reass_qsize--; 820 } 821 tcp_clean_sackreport(tcpb); 822 } 823 INP_UNLOCK(inpb); 824 } 825 INP_INFO_RUNLOCK(&tcbinfo); 826 } 827 } 828 829 /* 830 * Notify a tcp user of an asynchronous error; 831 * store error as soft error, but wake up user 832 * (for now, won't do anything until can select for soft error). 833 * 834 * Do not wake up user since there currently is no mechanism for 835 * reporting soft errors (yet - a kqueue filter may be added). 836 */ 837 static struct inpcb * 838 tcp_notify(struct inpcb *inp, int error) 839 { 840 struct tcpcb *tp; 841 842 INP_INFO_WLOCK_ASSERT(&tcbinfo); 843 INP_LOCK_ASSERT(inp); 844 845 if ((inp->inp_vflag & INP_TIMEWAIT) || 846 (inp->inp_vflag & INP_DROPPED)) 847 return (inp); 848 849 tp = intotcpcb(inp); 850 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 851 852 /* 853 * Ignore some errors if we are hooked up. 854 * If connection hasn't completed, has retransmitted several times, 855 * and receives a second error, give up now. This is better 856 * than waiting a long time to establish a connection that 857 * can never complete. 858 */ 859 if (tp->t_state == TCPS_ESTABLISHED && 860 (error == EHOSTUNREACH || error == ENETUNREACH || 861 error == EHOSTDOWN)) { 862 return (inp); 863 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 864 tp->t_softerror) { 865 tp = tcp_drop(tp, error); 866 if (tp != NULL) 867 return (inp); 868 else 869 return (NULL); 870 } else { 871 tp->t_softerror = error; 872 return (inp); 873 } 874 #if 0 875 wakeup( &so->so_timeo); 876 sorwakeup(so); 877 sowwakeup(so); 878 #endif 879 } 880 881 static int 882 tcp_pcblist(SYSCTL_HANDLER_ARGS) 883 { 884 int error, i, m, n, pcb_count; 885 struct inpcb *inp, **inp_list; 886 inp_gen_t gencnt; 887 struct xinpgen xig; 888 889 /* 890 * The process of preparing the TCB list is too time-consuming and 891 * resource-intensive to repeat twice on every request. 892 */ 893 if (req->oldptr == NULL) { 894 m = syncache_pcbcount(); 895 n = tcbinfo.ipi_count; 896 req->oldidx = 2 * (sizeof xig) 897 + ((m + n) + n/8) * sizeof(struct xtcpcb); 898 return (0); 899 } 900 901 if (req->newptr != NULL) 902 return (EPERM); 903 904 /* 905 * OK, now we're committed to doing something. 906 */ 907 INP_INFO_RLOCK(&tcbinfo); 908 gencnt = tcbinfo.ipi_gencnt; 909 n = tcbinfo.ipi_count; 910 INP_INFO_RUNLOCK(&tcbinfo); 911 912 m = syncache_pcbcount(); 913 914 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 915 + (n + m) * sizeof(struct xtcpcb)); 916 if (error != 0) 917 return (error); 918 919 xig.xig_len = sizeof xig; 920 xig.xig_count = n + m; 921 xig.xig_gen = gencnt; 922 xig.xig_sogen = so_gencnt; 923 error = SYSCTL_OUT(req, &xig, sizeof xig); 924 if (error) 925 return (error); 926 927 error = syncache_pcblist(req, m, &pcb_count); 928 if (error) 929 return (error); 930 931 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 932 if (inp_list == NULL) 933 return (ENOMEM); 934 935 INP_INFO_RLOCK(&tcbinfo); 936 for (inp = LIST_FIRST(tcbinfo.ipi_listhead), i = 0; inp != NULL && i 937 < n; inp = LIST_NEXT(inp, inp_list)) { 938 INP_LOCK(inp); 939 if (inp->inp_gencnt <= gencnt) { 940 /* 941 * XXX: This use of cr_cansee(), introduced with 942 * TCP state changes, is not quite right, but for 943 * now, better than nothing. 944 */ 945 if (inp->inp_vflag & INP_TIMEWAIT) { 946 if (intotw(inp) != NULL) 947 error = cr_cansee(req->td->td_ucred, 948 intotw(inp)->tw_cred); 949 else 950 error = EINVAL; /* Skip this inp. */ 951 } else 952 error = cr_canseesocket(req->td->td_ucred, 953 inp->inp_socket); 954 if (error == 0) 955 inp_list[i++] = inp; 956 } 957 INP_UNLOCK(inp); 958 } 959 INP_INFO_RUNLOCK(&tcbinfo); 960 n = i; 961 962 error = 0; 963 for (i = 0; i < n; i++) { 964 inp = inp_list[i]; 965 INP_LOCK(inp); 966 if (inp->inp_gencnt <= gencnt) { 967 struct xtcpcb xt; 968 void *inp_ppcb; 969 970 bzero(&xt, sizeof(xt)); 971 xt.xt_len = sizeof xt; 972 /* XXX should avoid extra copy */ 973 bcopy(inp, &xt.xt_inp, sizeof *inp); 974 inp_ppcb = inp->inp_ppcb; 975 if (inp_ppcb == NULL) 976 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 977 else if (inp->inp_vflag & INP_TIMEWAIT) { 978 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 979 xt.xt_tp.t_state = TCPS_TIME_WAIT; 980 } else 981 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 982 if (inp->inp_socket != NULL) 983 sotoxsocket(inp->inp_socket, &xt.xt_socket); 984 else { 985 bzero(&xt.xt_socket, sizeof xt.xt_socket); 986 xt.xt_socket.xso_protocol = IPPROTO_TCP; 987 } 988 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 989 INP_UNLOCK(inp); 990 error = SYSCTL_OUT(req, &xt, sizeof xt); 991 } else 992 INP_UNLOCK(inp); 993 994 } 995 if (!error) { 996 /* 997 * Give the user an updated idea of our state. 998 * If the generation differs from what we told 999 * her before, she knows that something happened 1000 * while we were processing this request, and it 1001 * might be necessary to retry. 1002 */ 1003 INP_INFO_RLOCK(&tcbinfo); 1004 xig.xig_gen = tcbinfo.ipi_gencnt; 1005 xig.xig_sogen = so_gencnt; 1006 xig.xig_count = tcbinfo.ipi_count + pcb_count; 1007 INP_INFO_RUNLOCK(&tcbinfo); 1008 error = SYSCTL_OUT(req, &xig, sizeof xig); 1009 } 1010 free(inp_list, M_TEMP); 1011 return (error); 1012 } 1013 1014 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1015 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1016 1017 static int 1018 tcp_getcred(SYSCTL_HANDLER_ARGS) 1019 { 1020 struct xucred xuc; 1021 struct sockaddr_in addrs[2]; 1022 struct inpcb *inp; 1023 int error; 1024 1025 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1026 if (error) 1027 return (error); 1028 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1029 if (error) 1030 return (error); 1031 INP_INFO_RLOCK(&tcbinfo); 1032 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1033 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1034 if (inp == NULL) { 1035 error = ENOENT; 1036 goto outunlocked; 1037 } 1038 INP_LOCK(inp); 1039 if (inp->inp_socket == NULL) { 1040 error = ENOENT; 1041 goto out; 1042 } 1043 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1044 if (error) 1045 goto out; 1046 cru2x(inp->inp_socket->so_cred, &xuc); 1047 out: 1048 INP_UNLOCK(inp); 1049 outunlocked: 1050 INP_INFO_RUNLOCK(&tcbinfo); 1051 if (error == 0) 1052 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1053 return (error); 1054 } 1055 1056 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1057 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1058 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1059 1060 #ifdef INET6 1061 static int 1062 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1063 { 1064 struct xucred xuc; 1065 struct sockaddr_in6 addrs[2]; 1066 struct inpcb *inp; 1067 int error, mapped = 0; 1068 1069 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1070 if (error) 1071 return (error); 1072 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1073 if (error) 1074 return (error); 1075 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1076 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1077 return (error); 1078 } 1079 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1080 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1081 mapped = 1; 1082 else 1083 return (EINVAL); 1084 } 1085 1086 INP_INFO_RLOCK(&tcbinfo); 1087 if (mapped == 1) 1088 inp = in_pcblookup_hash(&tcbinfo, 1089 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1090 addrs[1].sin6_port, 1091 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1092 addrs[0].sin6_port, 1093 0, NULL); 1094 else 1095 inp = in6_pcblookup_hash(&tcbinfo, 1096 &addrs[1].sin6_addr, addrs[1].sin6_port, 1097 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1098 if (inp == NULL) { 1099 error = ENOENT; 1100 goto outunlocked; 1101 } 1102 INP_LOCK(inp); 1103 if (inp->inp_socket == NULL) { 1104 error = ENOENT; 1105 goto out; 1106 } 1107 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1108 if (error) 1109 goto out; 1110 cru2x(inp->inp_socket->so_cred, &xuc); 1111 out: 1112 INP_UNLOCK(inp); 1113 outunlocked: 1114 INP_INFO_RUNLOCK(&tcbinfo); 1115 if (error == 0) 1116 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1117 return (error); 1118 } 1119 1120 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1121 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1122 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1123 #endif 1124 1125 1126 void 1127 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1128 { 1129 struct ip *ip = vip; 1130 struct tcphdr *th; 1131 struct in_addr faddr; 1132 struct inpcb *inp; 1133 struct tcpcb *tp; 1134 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1135 struct icmp *icp; 1136 struct in_conninfo inc; 1137 tcp_seq icmp_tcp_seq; 1138 int mtu; 1139 1140 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1141 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1142 return; 1143 1144 if (cmd == PRC_MSGSIZE) 1145 notify = tcp_mtudisc; 1146 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1147 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1148 notify = tcp_drop_syn_sent; 1149 /* 1150 * Redirects don't need to be handled up here. 1151 */ 1152 else if (PRC_IS_REDIRECT(cmd)) 1153 return; 1154 /* 1155 * Source quench is depreciated. 1156 */ 1157 else if (cmd == PRC_QUENCH) 1158 return; 1159 /* 1160 * Hostdead is ugly because it goes linearly through all PCBs. 1161 * XXX: We never get this from ICMP, otherwise it makes an 1162 * excellent DoS attack on machines with many connections. 1163 */ 1164 else if (cmd == PRC_HOSTDEAD) 1165 ip = NULL; 1166 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1167 return; 1168 if (ip != NULL) { 1169 icp = (struct icmp *)((caddr_t)ip 1170 - offsetof(struct icmp, icmp_ip)); 1171 th = (struct tcphdr *)((caddr_t)ip 1172 + (ip->ip_hl << 2)); 1173 INP_INFO_WLOCK(&tcbinfo); 1174 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1175 ip->ip_src, th->th_sport, 0, NULL); 1176 if (inp != NULL) { 1177 INP_LOCK(inp); 1178 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1179 !(inp->inp_vflag & INP_DROPPED) && 1180 !(inp->inp_socket == NULL)) { 1181 icmp_tcp_seq = htonl(th->th_seq); 1182 tp = intotcpcb(inp); 1183 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1184 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1185 if (cmd == PRC_MSGSIZE) { 1186 /* 1187 * MTU discovery: 1188 * If we got a needfrag set the MTU 1189 * in the route to the suggested new 1190 * value (if given) and then notify. 1191 */ 1192 bzero(&inc, sizeof(inc)); 1193 inc.inc_flags = 0; /* IPv4 */ 1194 inc.inc_faddr = faddr; 1195 1196 mtu = ntohs(icp->icmp_nextmtu); 1197 /* 1198 * If no alternative MTU was 1199 * proposed, try the next smaller 1200 * one. ip->ip_len has already 1201 * been swapped in icmp_input(). 1202 */ 1203 if (!mtu) 1204 mtu = ip_next_mtu(ip->ip_len, 1205 1); 1206 if (mtu < max(296, (tcp_minmss) 1207 + sizeof(struct tcpiphdr))) 1208 mtu = 0; 1209 if (!mtu) 1210 mtu = tcp_mssdflt 1211 + sizeof(struct tcpiphdr); 1212 /* 1213 * Only cache the the MTU if it 1214 * is smaller than the interface 1215 * or route MTU. tcp_mtudisc() 1216 * will do right thing by itself. 1217 */ 1218 if (mtu <= tcp_maxmtu(&inc, NULL)) 1219 tcp_hc_updatemtu(&inc, mtu); 1220 } 1221 1222 inp = (*notify)(inp, inetctlerrmap[cmd]); 1223 } 1224 } 1225 if (inp != NULL) 1226 INP_UNLOCK(inp); 1227 } else { 1228 inc.inc_fport = th->th_dport; 1229 inc.inc_lport = th->th_sport; 1230 inc.inc_faddr = faddr; 1231 inc.inc_laddr = ip->ip_src; 1232 #ifdef INET6 1233 inc.inc_isipv6 = 0; 1234 #endif 1235 syncache_unreach(&inc, th); 1236 } 1237 INP_INFO_WUNLOCK(&tcbinfo); 1238 } else 1239 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1240 } 1241 1242 #ifdef INET6 1243 void 1244 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1245 { 1246 struct tcphdr th; 1247 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1248 struct ip6_hdr *ip6; 1249 struct mbuf *m; 1250 struct ip6ctlparam *ip6cp = NULL; 1251 const struct sockaddr_in6 *sa6_src = NULL; 1252 int off; 1253 struct tcp_portonly { 1254 u_int16_t th_sport; 1255 u_int16_t th_dport; 1256 } *thp; 1257 1258 if (sa->sa_family != AF_INET6 || 1259 sa->sa_len != sizeof(struct sockaddr_in6)) 1260 return; 1261 1262 if (cmd == PRC_MSGSIZE) 1263 notify = tcp_mtudisc; 1264 else if (!PRC_IS_REDIRECT(cmd) && 1265 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1266 return; 1267 /* Source quench is depreciated. */ 1268 else if (cmd == PRC_QUENCH) 1269 return; 1270 1271 /* if the parameter is from icmp6, decode it. */ 1272 if (d != NULL) { 1273 ip6cp = (struct ip6ctlparam *)d; 1274 m = ip6cp->ip6c_m; 1275 ip6 = ip6cp->ip6c_ip6; 1276 off = ip6cp->ip6c_off; 1277 sa6_src = ip6cp->ip6c_src; 1278 } else { 1279 m = NULL; 1280 ip6 = NULL; 1281 off = 0; /* fool gcc */ 1282 sa6_src = &sa6_any; 1283 } 1284 1285 if (ip6 != NULL) { 1286 struct in_conninfo inc; 1287 /* 1288 * XXX: We assume that when IPV6 is non NULL, 1289 * M and OFF are valid. 1290 */ 1291 1292 /* check if we can safely examine src and dst ports */ 1293 if (m->m_pkthdr.len < off + sizeof(*thp)) 1294 return; 1295 1296 bzero(&th, sizeof(th)); 1297 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1298 1299 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1300 (struct sockaddr *)ip6cp->ip6c_src, 1301 th.th_sport, cmd, NULL, notify); 1302 1303 inc.inc_fport = th.th_dport; 1304 inc.inc_lport = th.th_sport; 1305 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1306 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1307 inc.inc_isipv6 = 1; 1308 INP_INFO_WLOCK(&tcbinfo); 1309 syncache_unreach(&inc, &th); 1310 INP_INFO_WUNLOCK(&tcbinfo); 1311 } else 1312 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1313 0, cmd, NULL, notify); 1314 } 1315 #endif /* INET6 */ 1316 1317 1318 /* 1319 * Following is where TCP initial sequence number generation occurs. 1320 * 1321 * There are two places where we must use initial sequence numbers: 1322 * 1. In SYN-ACK packets. 1323 * 2. In SYN packets. 1324 * 1325 * All ISNs for SYN-ACK packets are generated by the syncache. See 1326 * tcp_syncache.c for details. 1327 * 1328 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1329 * depends on this property. In addition, these ISNs should be 1330 * unguessable so as to prevent connection hijacking. To satisfy 1331 * the requirements of this situation, the algorithm outlined in 1332 * RFC 1948 is used, with only small modifications. 1333 * 1334 * Implementation details: 1335 * 1336 * Time is based off the system timer, and is corrected so that it 1337 * increases by one megabyte per second. This allows for proper 1338 * recycling on high speed LANs while still leaving over an hour 1339 * before rollover. 1340 * 1341 * As reading the *exact* system time is too expensive to be done 1342 * whenever setting up a TCP connection, we increment the time 1343 * offset in two ways. First, a small random positive increment 1344 * is added to isn_offset for each connection that is set up. 1345 * Second, the function tcp_isn_tick fires once per clock tick 1346 * and increments isn_offset as necessary so that sequence numbers 1347 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1348 * random positive increments serve only to ensure that the same 1349 * exact sequence number is never sent out twice (as could otherwise 1350 * happen when a port is recycled in less than the system tick 1351 * interval.) 1352 * 1353 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1354 * between seeding of isn_secret. This is normally set to zero, 1355 * as reseeding should not be necessary. 1356 * 1357 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1358 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1359 * general, this means holding an exclusive (write) lock. 1360 */ 1361 1362 #define ISN_BYTES_PER_SECOND 1048576 1363 #define ISN_STATIC_INCREMENT 4096 1364 #define ISN_RANDOM_INCREMENT (4096 - 1) 1365 1366 static u_char isn_secret[32]; 1367 static int isn_last_reseed; 1368 static u_int32_t isn_offset, isn_offset_old; 1369 static MD5_CTX isn_ctx; 1370 1371 tcp_seq 1372 tcp_new_isn(struct tcpcb *tp) 1373 { 1374 u_int32_t md5_buffer[4]; 1375 tcp_seq new_isn; 1376 1377 INP_LOCK_ASSERT(tp->t_inpcb); 1378 1379 ISN_LOCK(); 1380 /* Seed if this is the first use, reseed if requested. */ 1381 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1382 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1383 < (u_int)ticks))) { 1384 read_random(&isn_secret, sizeof(isn_secret)); 1385 isn_last_reseed = ticks; 1386 } 1387 1388 /* Compute the md5 hash and return the ISN. */ 1389 MD5Init(&isn_ctx); 1390 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1391 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1392 #ifdef INET6 1393 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1394 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1395 sizeof(struct in6_addr)); 1396 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1397 sizeof(struct in6_addr)); 1398 } else 1399 #endif 1400 { 1401 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1402 sizeof(struct in_addr)); 1403 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1404 sizeof(struct in_addr)); 1405 } 1406 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1407 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1408 new_isn = (tcp_seq) md5_buffer[0]; 1409 isn_offset += ISN_STATIC_INCREMENT + 1410 (arc4random() & ISN_RANDOM_INCREMENT); 1411 new_isn += isn_offset; 1412 ISN_UNLOCK(); 1413 return (new_isn); 1414 } 1415 1416 /* 1417 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary 1418 * to keep time flowing at a relatively constant rate. If the random 1419 * increments have already pushed us past the projected offset, do nothing. 1420 */ 1421 static void 1422 tcp_isn_tick(void *xtp) 1423 { 1424 u_int32_t projected_offset; 1425 1426 ISN_LOCK(); 1427 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1428 1429 if (SEQ_GT(projected_offset, isn_offset)) 1430 isn_offset = projected_offset; 1431 1432 isn_offset_old = isn_offset; 1433 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1434 ISN_UNLOCK(); 1435 } 1436 1437 /* 1438 * When a specific ICMP unreachable message is received and the 1439 * connection state is SYN-SENT, drop the connection. This behavior 1440 * is controlled by the icmp_may_rst sysctl. 1441 */ 1442 struct inpcb * 1443 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1444 { 1445 struct tcpcb *tp; 1446 1447 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1448 INP_LOCK_ASSERT(inp); 1449 1450 if ((inp->inp_vflag & INP_TIMEWAIT) || 1451 (inp->inp_vflag & INP_DROPPED)) 1452 return (inp); 1453 1454 tp = intotcpcb(inp); 1455 if (tp->t_state != TCPS_SYN_SENT) 1456 return (inp); 1457 1458 tp = tcp_drop(tp, errno); 1459 if (tp != NULL) 1460 return (inp); 1461 else 1462 return (NULL); 1463 } 1464 1465 /* 1466 * When `need fragmentation' ICMP is received, update our idea of the MSS 1467 * based on the new value in the route. Also nudge TCP to send something, 1468 * since we know the packet we just sent was dropped. 1469 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1470 */ 1471 struct inpcb * 1472 tcp_mtudisc(struct inpcb *inp, int errno) 1473 { 1474 struct tcpcb *tp; 1475 struct socket *so = inp->inp_socket; 1476 u_int maxmtu; 1477 u_int romtu; 1478 int mss; 1479 #ifdef INET6 1480 int isipv6; 1481 #endif /* INET6 */ 1482 1483 INP_LOCK_ASSERT(inp); 1484 if ((inp->inp_vflag & INP_TIMEWAIT) || 1485 (inp->inp_vflag & INP_DROPPED)) 1486 return (inp); 1487 1488 tp = intotcpcb(inp); 1489 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1490 1491 #ifdef INET6 1492 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1493 #endif 1494 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1495 romtu = 1496 #ifdef INET6 1497 isipv6 ? tcp_maxmtu6(&inp->inp_inc, NULL) : 1498 #endif /* INET6 */ 1499 tcp_maxmtu(&inp->inp_inc, NULL); 1500 if (!maxmtu) 1501 maxmtu = romtu; 1502 else 1503 maxmtu = min(maxmtu, romtu); 1504 if (!maxmtu) { 1505 tp->t_maxopd = tp->t_maxseg = 1506 #ifdef INET6 1507 isipv6 ? tcp_v6mssdflt : 1508 #endif /* INET6 */ 1509 tcp_mssdflt; 1510 return (inp); 1511 } 1512 mss = maxmtu - 1513 #ifdef INET6 1514 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1515 #endif /* INET6 */ 1516 sizeof(struct tcpiphdr) 1517 #ifdef INET6 1518 ) 1519 #endif /* INET6 */ 1520 ; 1521 1522 /* 1523 * XXX - The above conditional probably violates the TCP 1524 * spec. The problem is that, since we don't know the 1525 * other end's MSS, we are supposed to use a conservative 1526 * default. But, if we do that, then MTU discovery will 1527 * never actually take place, because the conservative 1528 * default is much less than the MTUs typically seen 1529 * on the Internet today. For the moment, we'll sweep 1530 * this under the carpet. 1531 * 1532 * The conservative default might not actually be a problem 1533 * if the only case this occurs is when sending an initial 1534 * SYN with options and data to a host we've never talked 1535 * to before. Then, they will reply with an MSS value which 1536 * will get recorded and the new parameters should get 1537 * recomputed. For Further Study. 1538 */ 1539 if (tp->t_maxopd <= mss) 1540 return (inp); 1541 tp->t_maxopd = mss; 1542 1543 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1544 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1545 mss -= TCPOLEN_TSTAMP_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_free_sackholes(tp); 1562 tp->snd_recover = tp->snd_max; 1563 if (tp->t_flags & TF_SACK_PERMIT) 1564 EXIT_FASTRECOVERY(tp); 1565 tcp_output(tp); 1566 return (inp); 1567 } 1568 1569 /* 1570 * Look-up the routing entry to the peer of this inpcb. If no route 1571 * is found and it cannot be allocated, then return NULL. This routine 1572 * is called by TCP routines that access the rmx structure and by tcp_mss 1573 * to get the interface MTU. 1574 */ 1575 u_long 1576 tcp_maxmtu(struct in_conninfo *inc, int *flags) 1577 { 1578 struct route sro; 1579 struct sockaddr_in *dst; 1580 struct ifnet *ifp; 1581 u_long maxmtu = 0; 1582 1583 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1584 1585 bzero(&sro, sizeof(sro)); 1586 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1587 dst = (struct sockaddr_in *)&sro.ro_dst; 1588 dst->sin_family = AF_INET; 1589 dst->sin_len = sizeof(*dst); 1590 dst->sin_addr = inc->inc_faddr; 1591 rtalloc_ign(&sro, RTF_CLONING); 1592 } 1593 if (sro.ro_rt != NULL) { 1594 ifp = sro.ro_rt->rt_ifp; 1595 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1596 maxmtu = ifp->if_mtu; 1597 else 1598 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1599 1600 /* Report additional interface capabilities. */ 1601 if (flags != NULL) { 1602 if (ifp->if_capenable & IFCAP_TSO4 && 1603 ifp->if_hwassist & CSUM_TSO) 1604 *flags |= CSUM_TSO; 1605 } 1606 RTFREE(sro.ro_rt); 1607 } 1608 return (maxmtu); 1609 } 1610 1611 #ifdef INET6 1612 u_long 1613 tcp_maxmtu6(struct in_conninfo *inc, int *flags) 1614 { 1615 struct route_in6 sro6; 1616 struct ifnet *ifp; 1617 u_long maxmtu = 0; 1618 1619 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1620 1621 bzero(&sro6, sizeof(sro6)); 1622 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1623 sro6.ro_dst.sin6_family = AF_INET6; 1624 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1625 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1626 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1627 } 1628 if (sro6.ro_rt != NULL) { 1629 ifp = sro6.ro_rt->rt_ifp; 1630 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1631 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1632 else 1633 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1634 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1635 1636 /* Report additional interface capabilities. */ 1637 if (flags != NULL) { 1638 if (ifp->if_capenable & IFCAP_TSO6 && 1639 ifp->if_hwassist & CSUM_TSO) 1640 *flags |= CSUM_TSO; 1641 } 1642 RTFREE(sro6.ro_rt); 1643 } 1644 1645 return (maxmtu); 1646 } 1647 #endif /* INET6 */ 1648 1649 #ifdef IPSEC 1650 /* compute ESP/AH header size for TCP, including outer IP header. */ 1651 size_t 1652 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1653 { 1654 struct inpcb *inp; 1655 struct mbuf *m; 1656 size_t hdrsiz; 1657 struct ip *ip; 1658 #ifdef INET6 1659 struct ip6_hdr *ip6; 1660 #endif 1661 struct tcphdr *th; 1662 1663 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1664 return (0); 1665 MGETHDR(m, M_DONTWAIT, MT_DATA); 1666 if (!m) 1667 return (0); 1668 1669 #ifdef INET6 1670 if ((inp->inp_vflag & INP_IPV6) != 0) { 1671 ip6 = mtod(m, struct ip6_hdr *); 1672 th = (struct tcphdr *)(ip6 + 1); 1673 m->m_pkthdr.len = m->m_len = 1674 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1675 tcpip_fillheaders(inp, ip6, th); 1676 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1677 } else 1678 #endif /* INET6 */ 1679 { 1680 ip = mtod(m, struct ip *); 1681 th = (struct tcphdr *)(ip + 1); 1682 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1683 tcpip_fillheaders(inp, ip, th); 1684 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1685 } 1686 1687 m_free(m); 1688 return (hdrsiz); 1689 } 1690 #endif /* IPSEC */ 1691 1692 /* 1693 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1694 * 1695 * This code attempts to calculate the bandwidth-delay product as a 1696 * means of determining the optimal window size to maximize bandwidth, 1697 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1698 * routers. This code also does a fairly good job keeping RTTs in check 1699 * across slow links like modems. We implement an algorithm which is very 1700 * similar (but not meant to be) TCP/Vegas. The code operates on the 1701 * transmitter side of a TCP connection and so only effects the transmit 1702 * side of the connection. 1703 * 1704 * BACKGROUND: TCP makes no provision for the management of buffer space 1705 * at the end points or at the intermediate routers and switches. A TCP 1706 * stream, whether using NewReno or not, will eventually buffer as 1707 * many packets as it is able and the only reason this typically works is 1708 * due to the fairly small default buffers made available for a connection 1709 * (typicaly 16K or 32K). As machines use larger windows and/or window 1710 * scaling it is now fairly easy for even a single TCP connection to blow-out 1711 * all available buffer space not only on the local interface, but on 1712 * intermediate routers and switches as well. NewReno makes a misguided 1713 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1714 * then backing off, then steadily increasing the window again until another 1715 * failure occurs, ad-infinitum. This results in terrible oscillation that 1716 * is only made worse as network loads increase and the idea of intentionally 1717 * blowing out network buffers is, frankly, a terrible way to manage network 1718 * resources. 1719 * 1720 * It is far better to limit the transmit window prior to the failure 1721 * condition being achieved. There are two general ways to do this: First 1722 * you can 'scan' through different transmit window sizes and locate the 1723 * point where the RTT stops increasing, indicating that you have filled the 1724 * pipe, then scan backwards until you note that RTT stops decreasing, then 1725 * repeat ad-infinitum. This method works in principle but has severe 1726 * implementation issues due to RTT variances, timer granularity, and 1727 * instability in the algorithm which can lead to many false positives and 1728 * create oscillations as well as interact badly with other TCP streams 1729 * implementing the same algorithm. 1730 * 1731 * The second method is to limit the window to the bandwidth delay product 1732 * of the link. This is the method we implement. RTT variances and our 1733 * own manipulation of the congestion window, bwnd, can potentially 1734 * destabilize the algorithm. For this reason we have to stabilize the 1735 * elements used to calculate the window. We do this by using the minimum 1736 * observed RTT, the long term average of the observed bandwidth, and 1737 * by adding two segments worth of slop. It isn't perfect but it is able 1738 * to react to changing conditions and gives us a very stable basis on 1739 * which to extend the algorithm. 1740 */ 1741 void 1742 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1743 { 1744 u_long bw; 1745 u_long bwnd; 1746 int save_ticks; 1747 1748 INP_LOCK_ASSERT(tp->t_inpcb); 1749 1750 /* 1751 * If inflight_enable is disabled in the middle of a tcp connection, 1752 * make sure snd_bwnd is effectively disabled. 1753 */ 1754 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 1755 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1756 tp->snd_bandwidth = 0; 1757 return; 1758 } 1759 1760 /* 1761 * Figure out the bandwidth. Due to the tick granularity this 1762 * is a very rough number and it MUST be averaged over a fairly 1763 * long period of time. XXX we need to take into account a link 1764 * that is not using all available bandwidth, but for now our 1765 * slop will ramp us up if this case occurs and the bandwidth later 1766 * increases. 1767 * 1768 * Note: if ticks rollover 'bw' may wind up negative. We must 1769 * effectively reset t_bw_rtttime for this case. 1770 */ 1771 save_ticks = ticks; 1772 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1773 return; 1774 1775 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1776 (save_ticks - tp->t_bw_rtttime); 1777 tp->t_bw_rtttime = save_ticks; 1778 tp->t_bw_rtseq = ack_seq; 1779 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1780 return; 1781 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1782 1783 tp->snd_bandwidth = bw; 1784 1785 /* 1786 * Calculate the semi-static bandwidth delay product, plus two maximal 1787 * segments. The additional slop puts us squarely in the sweet 1788 * spot and also handles the bandwidth run-up case and stabilization. 1789 * Without the slop we could be locking ourselves into a lower 1790 * bandwidth. 1791 * 1792 * Situations Handled: 1793 * (1) Prevents over-queueing of packets on LANs, especially on 1794 * high speed LANs, allowing larger TCP buffers to be 1795 * specified, and also does a good job preventing 1796 * over-queueing of packets over choke points like modems 1797 * (at least for the transmit side). 1798 * 1799 * (2) Is able to handle changing network loads (bandwidth 1800 * drops so bwnd drops, bandwidth increases so bwnd 1801 * increases). 1802 * 1803 * (3) Theoretically should stabilize in the face of multiple 1804 * connections implementing the same algorithm (this may need 1805 * a little work). 1806 * 1807 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1808 * be adjusted with a sysctl but typically only needs to be 1809 * on very slow connections. A value no smaller then 5 1810 * should be used, but only reduce this default if you have 1811 * no other choice. 1812 */ 1813 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1814 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 1815 #undef USERTT 1816 1817 if (tcp_inflight_debug > 0) { 1818 static int ltime; 1819 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1820 ltime = ticks; 1821 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1822 tp, 1823 bw, 1824 tp->t_rttbest, 1825 tp->t_srtt, 1826 bwnd 1827 ); 1828 } 1829 } 1830 if ((long)bwnd < tcp_inflight_min) 1831 bwnd = tcp_inflight_min; 1832 if (bwnd > tcp_inflight_max) 1833 bwnd = tcp_inflight_max; 1834 if ((long)bwnd < tp->t_maxseg * 2) 1835 bwnd = tp->t_maxseg * 2; 1836 tp->snd_bwnd = bwnd; 1837 } 1838 1839 #ifdef TCP_SIGNATURE 1840 /* 1841 * Callback function invoked by m_apply() to digest TCP segment data 1842 * contained within an mbuf chain. 1843 */ 1844 static int 1845 tcp_signature_apply(void *fstate, void *data, u_int len) 1846 { 1847 1848 MD5Update(fstate, (u_char *)data, len); 1849 return (0); 1850 } 1851 1852 /* 1853 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 1854 * 1855 * Parameters: 1856 * m pointer to head of mbuf chain 1857 * off0 offset to TCP header within the mbuf chain 1858 * len length of TCP segment data, excluding options 1859 * optlen length of TCP segment options 1860 * buf pointer to storage for computed MD5 digest 1861 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1862 * 1863 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1864 * When called from tcp_input(), we can be sure that th_sum has been 1865 * zeroed out and verified already. 1866 * 1867 * This function is for IPv4 use only. Calling this function with an 1868 * IPv6 packet in the mbuf chain will yield undefined results. 1869 * 1870 * Return 0 if successful, otherwise return -1. 1871 * 1872 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1873 * search with the destination IP address, and a 'magic SPI' to be 1874 * determined by the application. This is hardcoded elsewhere to 1179 1875 * right now. Another branch of this code exists which uses the SPD to 1876 * specify per-application flows but it is unstable. 1877 */ 1878 int 1879 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 1880 u_char *buf, u_int direction) 1881 { 1882 union sockaddr_union dst; 1883 struct ippseudo ippseudo; 1884 MD5_CTX ctx; 1885 int doff; 1886 struct ip *ip; 1887 struct ipovly *ipovly; 1888 struct secasvar *sav; 1889 struct tcphdr *th; 1890 u_short savecsum; 1891 1892 KASSERT(m != NULL, ("NULL mbuf chain")); 1893 KASSERT(buf != NULL, ("NULL signature pointer")); 1894 1895 /* Extract the destination from the IP header in the mbuf. */ 1896 ip = mtod(m, struct ip *); 1897 bzero(&dst, sizeof(union sockaddr_union)); 1898 dst.sa.sa_len = sizeof(struct sockaddr_in); 1899 dst.sa.sa_family = AF_INET; 1900 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1901 ip->ip_src : ip->ip_dst; 1902 1903 /* Look up an SADB entry which matches the address of the peer. */ 1904 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 1905 if (sav == NULL) { 1906 printf("%s: SADB lookup failed for %s\n", __func__, 1907 inet_ntoa(dst.sin.sin_addr)); 1908 return (EINVAL); 1909 } 1910 1911 MD5Init(&ctx); 1912 ipovly = (struct ipovly *)ip; 1913 th = (struct tcphdr *)((u_char *)ip + off0); 1914 doff = off0 + sizeof(struct tcphdr) + optlen; 1915 1916 /* 1917 * Step 1: Update MD5 hash with IP pseudo-header. 1918 * 1919 * XXX The ippseudo header MUST be digested in network byte order, 1920 * or else we'll fail the regression test. Assume all fields we've 1921 * been doing arithmetic on have been in host byte order. 1922 * XXX One cannot depend on ipovly->ih_len here. When called from 1923 * tcp_output(), the underlying ip_len member has not yet been set. 1924 */ 1925 ippseudo.ippseudo_src = ipovly->ih_src; 1926 ippseudo.ippseudo_dst = ipovly->ih_dst; 1927 ippseudo.ippseudo_pad = 0; 1928 ippseudo.ippseudo_p = IPPROTO_TCP; 1929 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 1930 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 1931 1932 /* 1933 * Step 2: Update MD5 hash with TCP header, excluding options. 1934 * The TCP checksum must be set to zero. 1935 */ 1936 savecsum = th->th_sum; 1937 th->th_sum = 0; 1938 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 1939 th->th_sum = savecsum; 1940 1941 /* 1942 * Step 3: Update MD5 hash with TCP segment data. 1943 * Use m_apply() to avoid an early m_pullup(). 1944 */ 1945 if (len > 0) 1946 m_apply(m, doff, len, tcp_signature_apply, &ctx); 1947 1948 /* 1949 * Step 4: Update MD5 hash with shared secret. 1950 */ 1951 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth)); 1952 MD5Final(buf, &ctx); 1953 1954 key_sa_recordxfer(sav, m); 1955 KEY_FREESAV(&sav); 1956 return (0); 1957 } 1958 #endif /* TCP_SIGNATURE */ 1959 1960 static int 1961 sysctl_drop(SYSCTL_HANDLER_ARGS) 1962 { 1963 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 1964 struct sockaddr_storage addrs[2]; 1965 struct inpcb *inp; 1966 struct tcpcb *tp; 1967 struct tcptw *tw; 1968 struct sockaddr_in *fin, *lin; 1969 #ifdef INET6 1970 struct sockaddr_in6 *fin6, *lin6; 1971 struct in6_addr f6, l6; 1972 #endif 1973 int error; 1974 1975 inp = NULL; 1976 fin = lin = NULL; 1977 #ifdef INET6 1978 fin6 = lin6 = NULL; 1979 #endif 1980 error = 0; 1981 1982 if (req->oldptr != NULL || req->oldlen != 0) 1983 return (EINVAL); 1984 if (req->newptr == NULL) 1985 return (EPERM); 1986 if (req->newlen < sizeof(addrs)) 1987 return (ENOMEM); 1988 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 1989 if (error) 1990 return (error); 1991 1992 switch (addrs[0].ss_family) { 1993 #ifdef INET6 1994 case AF_INET6: 1995 fin6 = (struct sockaddr_in6 *)&addrs[0]; 1996 lin6 = (struct sockaddr_in6 *)&addrs[1]; 1997 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 1998 lin6->sin6_len != sizeof(struct sockaddr_in6)) 1999 return (EINVAL); 2000 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2001 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2002 return (EINVAL); 2003 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2004 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2005 fin = (struct sockaddr_in *)&addrs[0]; 2006 lin = (struct sockaddr_in *)&addrs[1]; 2007 break; 2008 } 2009 error = sa6_embedscope(fin6, ip6_use_defzone); 2010 if (error) 2011 return (error); 2012 error = sa6_embedscope(lin6, ip6_use_defzone); 2013 if (error) 2014 return (error); 2015 break; 2016 #endif 2017 case AF_INET: 2018 fin = (struct sockaddr_in *)&addrs[0]; 2019 lin = (struct sockaddr_in *)&addrs[1]; 2020 if (fin->sin_len != sizeof(struct sockaddr_in) || 2021 lin->sin_len != sizeof(struct sockaddr_in)) 2022 return (EINVAL); 2023 break; 2024 default: 2025 return (EINVAL); 2026 } 2027 INP_INFO_WLOCK(&tcbinfo); 2028 switch (addrs[0].ss_family) { 2029 #ifdef INET6 2030 case AF_INET6: 2031 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2032 &l6, lin6->sin6_port, 0, NULL); 2033 break; 2034 #endif 2035 case AF_INET: 2036 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2037 lin->sin_addr, lin->sin_port, 0, NULL); 2038 break; 2039 } 2040 if (inp != NULL) { 2041 INP_LOCK(inp); 2042 if (inp->inp_vflag & INP_TIMEWAIT) { 2043 /* 2044 * XXXRW: There currently exists a state where an 2045 * inpcb is present, but its timewait state has been 2046 * discarded. For now, don't allow dropping of this 2047 * type of inpcb. 2048 */ 2049 tw = intotw(inp); 2050 if (tw != NULL) 2051 tcp_twclose(tw, 0); 2052 else 2053 INP_UNLOCK(inp); 2054 } else if (!(inp->inp_vflag & INP_DROPPED) && 2055 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2056 tp = intotcpcb(inp); 2057 tp = tcp_drop(tp, ECONNABORTED); 2058 if (tp != NULL) 2059 INP_UNLOCK(inp); 2060 } else 2061 INP_UNLOCK(inp); 2062 } else 2063 error = ESRCH; 2064 INP_INFO_WUNLOCK(&tcbinfo); 2065 return (error); 2066 } 2067 2068 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2069 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2070 0, sysctl_drop, "", "Drop TCP connection"); 2071 2072 /* 2073 * Generate a standardized TCP log line for use throughout the 2074 * tcp subsystem. Memory allocation is done with M_NOWAIT to 2075 * allow use in the interrupt context. 2076 * 2077 * NB: The caller MUST free(s, M_TCPLOG) the returned string. 2078 * NB: The function may return NULL if memory allocation failed. 2079 * 2080 * Due to header inclusion and ordering limitations the struct ip 2081 * and ip6_hdr pointers have to be passed as void pointers. 2082 */ 2083 char * 2084 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, 2085 const void *ip6hdr) 2086 { 2087 char *s, *sp; 2088 size_t size; 2089 struct ip *ip; 2090 #ifdef INET6 2091 const struct ip6_hdr *ip6; 2092 2093 ip6 = (const struct ip6_hdr *)ip6hdr; 2094 #endif /* INET6 */ 2095 ip = (struct ip *)ip4hdr; 2096 2097 /* 2098 * The log line looks like this: 2099 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>" 2100 */ 2101 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") + 2102 sizeof(PRINT_TH_FLAGS) + 1 + 2103 #ifdef INET6 2104 2 * INET6_ADDRSTRLEN; 2105 #else 2106 2 * INET_ADDRSTRLEN; 2107 #endif /* INET6 */ 2108 2109 /* Is logging enabled? */ 2110 if (tcp_log_debug == 0 && tcp_log_in_vain == 0) 2111 return (NULL); 2112 2113 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT); 2114 if (s == NULL) 2115 return (NULL); 2116 2117 strcat(s, "TCP: ["); 2118 sp = s + strlen(s); 2119 2120 if (inc && inc->inc_isipv6 == 0) { 2121 inet_ntoa_r(inc->inc_faddr, sp); 2122 sp = s + strlen(s); 2123 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2124 sp = s + strlen(s); 2125 inet_ntoa_r(inc->inc_laddr, sp); 2126 sp = s + strlen(s); 2127 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2128 #ifdef INET6 2129 } else if (inc) { 2130 ip6_sprintf(sp, &inc->inc6_faddr); 2131 sp = s + strlen(s); 2132 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2133 sp = s + strlen(s); 2134 ip6_sprintf(sp, &inc->inc6_laddr); 2135 sp = s + strlen(s); 2136 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2137 } else if (ip6 && th) { 2138 ip6_sprintf(sp, &ip6->ip6_src); 2139 sp = s + strlen(s); 2140 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2141 sp = s + strlen(s); 2142 ip6_sprintf(sp, &ip6->ip6_dst); 2143 sp = s + strlen(s); 2144 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2145 #endif /* INET6 */ 2146 } else if (ip && th) { 2147 inet_ntoa_r(ip->ip_src, sp); 2148 sp = s + strlen(s); 2149 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2150 sp = s + strlen(s); 2151 inet_ntoa_r(ip->ip_dst, sp); 2152 sp = s + strlen(s); 2153 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2154 } else { 2155 free(s, M_TCPLOG); 2156 return (NULL); 2157 } 2158 sp = s + strlen(s); 2159 if (th) 2160 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS); 2161 if (*(s + size - 1) != '\0') 2162 panic("%s: string too long", __func__); 2163 return (s); 2164 }
Cache object: f761325f9b195df2f2f71d4b5a561796
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]