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 #include <netinet/tcp_offload.h> 89 #ifdef INET6 90 #include <netinet6/tcp6_var.h> 91 #endif 92 #include <netinet/tcpip.h> 93 #ifdef TCPDEBUG 94 #include <netinet/tcp_debug.h> 95 #endif 96 #include <netinet6/ip6protosw.h> 97 98 #ifdef IPSEC 99 #include <netipsec/ipsec.h> 100 #include <netipsec/xform.h> 101 #ifdef INET6 102 #include <netipsec/ipsec6.h> 103 #endif 104 #include <netipsec/key.h> 105 #endif /*IPSEC*/ 106 107 #include <machine/in_cksum.h> 108 #include <sys/md5.h> 109 110 #include <security/mac/mac_framework.h> 111 112 int tcp_mssdflt = TCP_MSS; 113 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 114 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size"); 115 116 #ifdef INET6 117 int tcp_v6mssdflt = TCP6_MSS; 118 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 119 CTLFLAG_RW, &tcp_v6mssdflt , 0, 120 "Default TCP Maximum Segment Size for IPv6"); 121 #endif 122 123 /* 124 * Minimum MSS we accept and use. This prevents DoS attacks where 125 * we are forced to a ridiculous low MSS like 20 and send hundreds 126 * of packets instead of one. The effect scales with the available 127 * bandwidth and quickly saturates the CPU and network interface 128 * with packet generation and sending. Set to zero to disable MINMSS 129 * checking. This setting prevents us from sending too small packets. 130 */ 131 int tcp_minmss = TCP_MINMSS; 132 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 133 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 134 135 int tcp_do_rfc1323 = 1; 136 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 137 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions"); 138 139 static int tcp_log_debug = 0; 140 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW, 141 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments"); 142 143 static int tcp_tcbhashsize = 0; 144 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 145 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 146 147 static int do_tcpdrain = 1; 148 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, 149 &do_tcpdrain, 0, 150 "Enable tcp_drain routine for extra help when low on mbufs"); 151 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 153 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 154 155 static int icmp_may_rst = 1; 156 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, 157 &icmp_may_rst, 0, 158 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 159 160 static int tcp_isn_reseed_interval = 0; 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 162 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 163 164 /* 165 * TCP bandwidth limiting sysctls. Note that the default lower bound of 166 * 1024 exists only for debugging. A good production default would be 167 * something like 6100. 168 */ 169 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 170 "TCP inflight data limiting"); 171 172 static int tcp_inflight_enable = 1; 173 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 174 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 175 176 static int tcp_inflight_debug = 0; 177 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 178 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 179 180 static int tcp_inflight_rttthresh; 181 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 182 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 183 "RTT threshold below which inflight will deactivate itself"); 184 185 static int tcp_inflight_min = 6144; 186 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 187 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 188 189 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 190 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 191 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 192 193 static int tcp_inflight_stab = 20; 194 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 195 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 196 197 uma_zone_t sack_hole_zone; 198 199 static struct inpcb *tcp_notify(struct inpcb *, int); 200 static void tcp_isn_tick(void *); 201 202 /* 203 * Target size of TCP PCB hash tables. Must be a power of two. 204 * 205 * Note that this can be overridden by the kernel environment 206 * variable net.inet.tcp.tcbhashsize 207 */ 208 #ifndef TCBHASHSIZE 209 #define TCBHASHSIZE 512 210 #endif 211 212 /* 213 * XXX 214 * Callouts should be moved into struct tcp directly. They are currently 215 * separate because the tcpcb structure is exported to userland for sysctl 216 * parsing purposes, which do not know about callouts. 217 */ 218 struct tcpcb_mem { 219 struct tcpcb tcb; 220 struct tcp_timer tt; 221 }; 222 223 static uma_zone_t tcpcb_zone; 224 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); 225 struct callout isn_callout; 226 static struct mtx isn_mtx; 227 228 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) 229 #define ISN_LOCK() mtx_lock(&isn_mtx) 230 #define ISN_UNLOCK() mtx_unlock(&isn_mtx) 231 232 /* 233 * TCP initialization. 234 */ 235 static void 236 tcp_zone_change(void *tag) 237 { 238 239 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 240 uma_zone_set_max(tcpcb_zone, maxsockets); 241 tcp_tw_zone_change(); 242 } 243 244 static int 245 tcp_inpcb_init(void *mem, int size, int flags) 246 { 247 struct inpcb *inp = mem; 248 249 INP_LOCK_INIT(inp, "inp", "tcpinp"); 250 return (0); 251 } 252 253 void 254 tcp_init(void) 255 { 256 257 int hashsize = TCBHASHSIZE; 258 tcp_delacktime = TCPTV_DELACK; 259 tcp_keepinit = TCPTV_KEEP_INIT; 260 tcp_keepidle = TCPTV_KEEP_IDLE; 261 tcp_keepintvl = TCPTV_KEEPINTVL; 262 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 263 tcp_msl = TCPTV_MSL; 264 tcp_rexmit_min = TCPTV_MIN; 265 if (tcp_rexmit_min < 1) 266 tcp_rexmit_min = 1; 267 tcp_rexmit_slop = TCPTV_CPU_VAR; 268 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 269 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT; 270 271 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 272 LIST_INIT(&tcb); 273 tcbinfo.ipi_listhead = &tcb; 274 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 275 if (!powerof2(hashsize)) { 276 printf("WARNING: TCB hash size not a power of 2\n"); 277 hashsize = 512; /* safe default */ 278 } 279 tcp_tcbhashsize = hashsize; 280 tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB, 281 &tcbinfo.ipi_hashmask); 282 tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB, 283 &tcbinfo.ipi_porthashmask); 284 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 285 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 286 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 287 #ifdef INET6 288 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 289 #else /* INET6 */ 290 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 291 #endif /* INET6 */ 292 if (max_protohdr < TCP_MINPROTOHDR) 293 max_protohdr = TCP_MINPROTOHDR; 294 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 295 panic("tcp_init"); 296 #undef TCP_MINPROTOHDR 297 /* 298 * These have to be type stable for the benefit of the timers. 299 */ 300 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 301 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 302 uma_zone_set_max(tcpcb_zone, maxsockets); 303 tcp_tw_init(); 304 syncache_init(); 305 tcp_hc_init(); 306 tcp_reass_init(); 307 ISN_LOCK_INIT(); 308 callout_init(&isn_callout, CALLOUT_MPSAFE); 309 tcp_isn_tick(NULL); 310 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 311 SHUTDOWN_PRI_DEFAULT); 312 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 313 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 314 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, 315 EVENTHANDLER_PRI_ANY); 316 } 317 318 void 319 tcp_fini(void *xtp) 320 { 321 322 callout_stop(&isn_callout); 323 } 324 325 /* 326 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 327 * tcp_template used to store this data in mbufs, but we now recopy it out 328 * of the tcpcb each time to conserve mbufs. 329 */ 330 void 331 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 332 { 333 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 334 335 INP_WLOCK_ASSERT(inp); 336 337 #ifdef INET6 338 if ((inp->inp_vflag & INP_IPV6) != 0) { 339 struct ip6_hdr *ip6; 340 341 ip6 = (struct ip6_hdr *)ip_ptr; 342 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 343 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 344 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 345 (IPV6_VERSION & IPV6_VERSION_MASK); 346 ip6->ip6_nxt = IPPROTO_TCP; 347 ip6->ip6_plen = sizeof(struct tcphdr); 348 ip6->ip6_src = inp->in6p_laddr; 349 ip6->ip6_dst = inp->in6p_faddr; 350 } else 351 #endif 352 { 353 struct ip *ip; 354 355 ip = (struct ip *)ip_ptr; 356 ip->ip_v = IPVERSION; 357 ip->ip_hl = 5; 358 ip->ip_tos = inp->inp_ip_tos; 359 ip->ip_len = 0; 360 ip->ip_id = 0; 361 ip->ip_off = 0; 362 ip->ip_ttl = inp->inp_ip_ttl; 363 ip->ip_sum = 0; 364 ip->ip_p = IPPROTO_TCP; 365 ip->ip_src = inp->inp_laddr; 366 ip->ip_dst = inp->inp_faddr; 367 } 368 th->th_sport = inp->inp_lport; 369 th->th_dport = inp->inp_fport; 370 th->th_seq = 0; 371 th->th_ack = 0; 372 th->th_x2 = 0; 373 th->th_off = 5; 374 th->th_flags = 0; 375 th->th_win = 0; 376 th->th_urp = 0; 377 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 378 } 379 380 /* 381 * Create template to be used to send tcp packets on a connection. 382 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 383 * use for this function is in keepalives, which use tcp_respond. 384 */ 385 struct tcptemp * 386 tcpip_maketemplate(struct inpcb *inp) 387 { 388 struct mbuf *m; 389 struct tcptemp *n; 390 391 m = m_get(M_DONTWAIT, MT_DATA); 392 if (m == NULL) 393 return (0); 394 m->m_len = sizeof(struct tcptemp); 395 n = mtod(m, struct tcptemp *); 396 397 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 398 return (n); 399 } 400 401 /* 402 * Send a single message to the TCP at address specified by 403 * the given TCP/IP header. If m == NULL, then we make a copy 404 * of the tcpiphdr at ti and send directly to the addressed host. 405 * This is used to force keep alive messages out using the TCP 406 * template for a connection. If flags are given then we send 407 * a message back to the TCP which originated the * segment ti, 408 * and discard the mbuf containing it and any other attached mbufs. 409 * 410 * In any case the ack and sequence number of the transmitted 411 * segment are as specified by the parameters. 412 * 413 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 414 */ 415 void 416 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 417 tcp_seq ack, tcp_seq seq, int flags) 418 { 419 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_WLOCK_ASSERT(inp); 442 } else 443 inp = NULL; 444 445 if (tp != NULL) { 446 if (!(flags & TH_RST)) { 447 win = sbspace(&inp->inp_socket->so_rcv); 448 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 449 win = (long)TCP_MAXWIN << tp->rcv_scale; 450 } 451 } 452 if (m == NULL) { 453 m = m_gethdr(M_DONTWAIT, MT_DATA); 454 if (m == NULL) 455 return; 456 tlen = 0; 457 m->m_data += max_linkhdr; 458 #ifdef INET6 459 if (isipv6) { 460 bcopy((caddr_t)ip6, mtod(m, caddr_t), 461 sizeof(struct ip6_hdr)); 462 ip6 = mtod(m, struct ip6_hdr *); 463 nth = (struct tcphdr *)(ip6 + 1); 464 } else 465 #endif /* INET6 */ 466 { 467 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 468 ip = mtod(m, struct ip *); 469 nth = (struct tcphdr *)(ip + 1); 470 } 471 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 472 flags = TH_ACK; 473 } else { 474 /* 475 * reuse the mbuf. 476 * XXX MRT We inherrit the FIB, which is lucky. 477 */ 478 m_freem(m->m_next); 479 m->m_next = NULL; 480 m->m_data = (caddr_t)ipgen; 481 /* m_len is set later */ 482 tlen = 0; 483 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 484 #ifdef INET6 485 if (isipv6) { 486 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 487 nth = (struct tcphdr *)(ip6 + 1); 488 } else 489 #endif /* INET6 */ 490 { 491 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 492 nth = (struct tcphdr *)(ip + 1); 493 } 494 if (th != nth) { 495 /* 496 * this is usually a case when an extension header 497 * exists between the IPv6 header and the 498 * TCP header. 499 */ 500 nth->th_sport = th->th_sport; 501 nth->th_dport = th->th_dport; 502 } 503 xchg(nth->th_dport, nth->th_sport, n_short); 504 #undef xchg 505 } 506 #ifdef INET6 507 if (isipv6) { 508 ip6->ip6_flow = 0; 509 ip6->ip6_vfc = IPV6_VERSION; 510 ip6->ip6_nxt = IPPROTO_TCP; 511 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 512 tlen)); 513 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 514 } else 515 #endif 516 { 517 tlen += sizeof (struct tcpiphdr); 518 ip->ip_len = tlen; 519 ip->ip_ttl = ip_defttl; 520 if (path_mtu_discovery) 521 ip->ip_off |= IP_DF; 522 } 523 m->m_len = tlen; 524 m->m_pkthdr.len = tlen; 525 m->m_pkthdr.rcvif = NULL; 526 #ifdef MAC 527 if (inp != NULL) { 528 /* 529 * Packet is associated with a socket, so allow the 530 * label of the response to reflect the socket label. 531 */ 532 INP_WLOCK_ASSERT(inp); 533 mac_inpcb_create_mbuf(inp, m); 534 } else { 535 /* 536 * Packet is not associated with a socket, so possibly 537 * update the label in place. 538 */ 539 mac_netinet_tcp_reply(m); 540 } 541 #endif 542 nth->th_seq = htonl(seq); 543 nth->th_ack = htonl(ack); 544 nth->th_x2 = 0; 545 nth->th_off = sizeof (struct tcphdr) >> 2; 546 nth->th_flags = flags; 547 if (tp != NULL) 548 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 549 else 550 nth->th_win = htons((u_short)win); 551 nth->th_urp = 0; 552 #ifdef INET6 553 if (isipv6) { 554 nth->th_sum = 0; 555 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 556 sizeof(struct ip6_hdr), 557 tlen - sizeof(struct ip6_hdr)); 558 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 559 NULL, NULL); 560 } else 561 #endif /* INET6 */ 562 { 563 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 564 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 565 m->m_pkthdr.csum_flags = CSUM_TCP; 566 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 567 } 568 #ifdef TCPDEBUG 569 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 570 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 571 #endif 572 #ifdef INET6 573 if (isipv6) 574 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 575 else 576 #endif /* INET6 */ 577 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 578 } 579 580 /* 581 * Create a new TCP control block, making an 582 * empty reassembly queue and hooking it to the argument 583 * protocol control block. The `inp' parameter must have 584 * come from the zone allocator set up in tcp_init(). 585 */ 586 struct tcpcb * 587 tcp_newtcpcb(struct inpcb *inp) 588 { 589 struct tcpcb_mem *tm; 590 struct tcpcb *tp; 591 #ifdef INET6 592 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 593 #endif /* INET6 */ 594 595 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 596 if (tm == NULL) 597 return (NULL); 598 tp = &tm->tcb; 599 tp->t_timers = &tm->tt; 600 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 601 tp->t_maxseg = tp->t_maxopd = 602 #ifdef INET6 603 isipv6 ? tcp_v6mssdflt : 604 #endif /* INET6 */ 605 tcp_mssdflt; 606 607 /* Set up our timeouts. */ 608 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE); 609 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE); 610 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE); 611 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE); 612 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE); 613 614 if (tcp_do_rfc1323) 615 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 616 if (tcp_do_sack) 617 tp->t_flags |= TF_SACK_PERMIT; 618 TAILQ_INIT(&tp->snd_holes); 619 tp->t_inpcb = inp; /* XXX */ 620 /* 621 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 622 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 623 * reasonable initial retransmit time. 624 */ 625 tp->t_srtt = TCPTV_SRTTBASE; 626 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 627 tp->t_rttmin = tcp_rexmit_min; 628 tp->t_rxtcur = TCPTV_RTOBASE; 629 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 630 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 631 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 632 tp->t_rcvtime = ticks; 633 tp->t_bw_rtttime = ticks; 634 /* 635 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 636 * because the socket may be bound to an IPv6 wildcard address, 637 * which may match an IPv4-mapped IPv6 address. 638 */ 639 inp->inp_ip_ttl = ip_defttl; 640 inp->inp_ppcb = tp; 641 return (tp); /* XXX */ 642 } 643 644 /* 645 * Drop a TCP connection, reporting 646 * the specified error. If connection is synchronized, 647 * then send a RST to peer. 648 */ 649 struct tcpcb * 650 tcp_drop(struct tcpcb *tp, int errno) 651 { 652 struct socket *so = tp->t_inpcb->inp_socket; 653 654 INP_INFO_WLOCK_ASSERT(&tcbinfo); 655 INP_WLOCK_ASSERT(tp->t_inpcb); 656 657 if (TCPS_HAVERCVDSYN(tp->t_state)) { 658 tp->t_state = TCPS_CLOSED; 659 (void) tcp_output_reset(tp); 660 tcpstat.tcps_drops++; 661 } else 662 tcpstat.tcps_conndrops++; 663 if (errno == ETIMEDOUT && tp->t_softerror) 664 errno = tp->t_softerror; 665 so->so_error = errno; 666 return (tcp_close(tp)); 667 } 668 669 void 670 tcp_discardcb(struct tcpcb *tp) 671 { 672 struct tseg_qent *q; 673 struct inpcb *inp = tp->t_inpcb; 674 struct socket *so = inp->inp_socket; 675 #ifdef INET6 676 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 677 #endif /* INET6 */ 678 679 INP_WLOCK_ASSERT(inp); 680 681 /* 682 * Make sure that all of our timers are stopped before we 683 * delete the PCB. 684 */ 685 callout_stop(&tp->t_timers->tt_rexmt); 686 callout_stop(&tp->t_timers->tt_persist); 687 callout_stop(&tp->t_timers->tt_keep); 688 callout_stop(&tp->t_timers->tt_2msl); 689 callout_stop(&tp->t_timers->tt_delack); 690 691 /* 692 * If we got enough samples through the srtt filter, 693 * save the rtt and rttvar in the routing entry. 694 * 'Enough' is arbitrarily defined as 4 rtt samples. 695 * 4 samples is enough for the srtt filter to converge 696 * to within enough % of the correct value; fewer samples 697 * and we could save a bogus rtt. The danger is not high 698 * as tcp quickly recovers from everything. 699 * XXX: Works very well but needs some more statistics! 700 */ 701 if (tp->t_rttupdated >= 4) { 702 struct hc_metrics_lite metrics; 703 u_long ssthresh; 704 705 bzero(&metrics, sizeof(metrics)); 706 /* 707 * Update the ssthresh always when the conditions below 708 * are satisfied. This gives us better new start value 709 * for the congestion avoidance for new connections. 710 * ssthresh is only set if packet loss occured on a session. 711 * 712 * XXXRW: 'so' may be NULL here, and/or socket buffer may be 713 * being torn down. Ideally this code would not use 'so'. 714 */ 715 ssthresh = tp->snd_ssthresh; 716 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 717 /* 718 * convert the limit from user data bytes to 719 * packets then to packet data bytes. 720 */ 721 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 722 if (ssthresh < 2) 723 ssthresh = 2; 724 ssthresh *= (u_long)(tp->t_maxseg + 725 #ifdef INET6 726 (isipv6 ? sizeof (struct ip6_hdr) + 727 sizeof (struct tcphdr) : 728 #endif 729 sizeof (struct tcpiphdr) 730 #ifdef INET6 731 ) 732 #endif 733 ); 734 } else 735 ssthresh = 0; 736 metrics.rmx_ssthresh = ssthresh; 737 738 metrics.rmx_rtt = tp->t_srtt; 739 metrics.rmx_rttvar = tp->t_rttvar; 740 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 741 metrics.rmx_bandwidth = tp->snd_bandwidth; 742 metrics.rmx_cwnd = tp->snd_cwnd; 743 metrics.rmx_sendpipe = 0; 744 metrics.rmx_recvpipe = 0; 745 746 tcp_hc_update(&inp->inp_inc, &metrics); 747 } 748 749 /* free the reassembly queue, if any */ 750 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 751 LIST_REMOVE(q, tqe_q); 752 m_freem(q->tqe_m); 753 uma_zfree(tcp_reass_zone, q); 754 tp->t_segqlen--; 755 tcp_reass_qsize--; 756 } 757 /* Disconnect offload device, if any. */ 758 tcp_offload_detach(tp); 759 760 tcp_free_sackholes(tp); 761 inp->inp_ppcb = NULL; 762 tp->t_inpcb = NULL; 763 uma_zfree(tcpcb_zone, tp); 764 } 765 766 /* 767 * Attempt to close a TCP control block, marking it as dropped, and freeing 768 * the socket if we hold the only reference. 769 */ 770 struct tcpcb * 771 tcp_close(struct tcpcb *tp) 772 { 773 struct inpcb *inp = tp->t_inpcb; 774 struct socket *so; 775 776 INP_INFO_WLOCK_ASSERT(&tcbinfo); 777 INP_WLOCK_ASSERT(inp); 778 779 /* Notify any offload devices of listener close */ 780 if (tp->t_state == TCPS_LISTEN) 781 tcp_offload_listen_close(tp); 782 in_pcbdrop(inp); 783 tcpstat.tcps_closed++; 784 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 785 so = inp->inp_socket; 786 soisdisconnected(so); 787 if (inp->inp_vflag & INP_SOCKREF) { 788 KASSERT(so->so_state & SS_PROTOREF, 789 ("tcp_close: !SS_PROTOREF")); 790 inp->inp_vflag &= ~INP_SOCKREF; 791 INP_WUNLOCK(inp); 792 ACCEPT_LOCK(); 793 SOCK_LOCK(so); 794 so->so_state &= ~SS_PROTOREF; 795 sofree(so); 796 return (NULL); 797 } 798 return (tp); 799 } 800 801 void 802 tcp_drain(void) 803 { 804 805 if (do_tcpdrain) { 806 struct inpcb *inpb; 807 struct tcpcb *tcpb; 808 struct tseg_qent *te; 809 810 /* 811 * Walk the tcpbs, if existing, and flush the reassembly queue, 812 * if there is one... 813 * XXX: The "Net/3" implementation doesn't imply that the TCP 814 * reassembly queue should be flushed, but in a situation 815 * where we're really low on mbufs, this is potentially 816 * usefull. 817 */ 818 INP_INFO_RLOCK(&tcbinfo); 819 LIST_FOREACH(inpb, tcbinfo.ipi_listhead, inp_list) { 820 if (inpb->inp_vflag & INP_TIMEWAIT) 821 continue; 822 INP_WLOCK(inpb); 823 if ((tcpb = intotcpcb(inpb)) != NULL) { 824 while ((te = LIST_FIRST(&tcpb->t_segq)) 825 != NULL) { 826 LIST_REMOVE(te, tqe_q); 827 m_freem(te->tqe_m); 828 uma_zfree(tcp_reass_zone, te); 829 tcpb->t_segqlen--; 830 tcp_reass_qsize--; 831 } 832 tcp_clean_sackreport(tcpb); 833 } 834 INP_WUNLOCK(inpb); 835 } 836 INP_INFO_RUNLOCK(&tcbinfo); 837 } 838 } 839 840 /* 841 * Notify a tcp user of an asynchronous error; 842 * store error as soft error, but wake up user 843 * (for now, won't do anything until can select for soft error). 844 * 845 * Do not wake up user since there currently is no mechanism for 846 * reporting soft errors (yet - a kqueue filter may be added). 847 */ 848 static struct inpcb * 849 tcp_notify(struct inpcb *inp, int error) 850 { 851 struct tcpcb *tp; 852 853 INP_INFO_WLOCK_ASSERT(&tcbinfo); 854 INP_WLOCK_ASSERT(inp); 855 856 if ((inp->inp_vflag & INP_TIMEWAIT) || 857 (inp->inp_vflag & INP_DROPPED)) 858 return (inp); 859 860 tp = intotcpcb(inp); 861 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 862 863 /* 864 * Ignore some errors if we are hooked up. 865 * If connection hasn't completed, has retransmitted several times, 866 * and receives a second error, give up now. This is better 867 * than waiting a long time to establish a connection that 868 * can never complete. 869 */ 870 if (tp->t_state == TCPS_ESTABLISHED && 871 (error == EHOSTUNREACH || error == ENETUNREACH || 872 error == EHOSTDOWN)) { 873 return (inp); 874 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 875 tp->t_softerror) { 876 tp = tcp_drop(tp, error); 877 if (tp != NULL) 878 return (inp); 879 else 880 return (NULL); 881 } else { 882 tp->t_softerror = error; 883 return (inp); 884 } 885 #if 0 886 wakeup( &so->so_timeo); 887 sorwakeup(so); 888 sowwakeup(so); 889 #endif 890 } 891 892 static int 893 tcp_pcblist(SYSCTL_HANDLER_ARGS) 894 { 895 int error, i, m, n, pcb_count; 896 struct inpcb *inp, **inp_list; 897 inp_gen_t gencnt; 898 struct xinpgen xig; 899 900 /* 901 * The process of preparing the TCB list is too time-consuming and 902 * resource-intensive to repeat twice on every request. 903 */ 904 if (req->oldptr == NULL) { 905 m = syncache_pcbcount(); 906 n = tcbinfo.ipi_count; 907 req->oldidx = 2 * (sizeof xig) 908 + ((m + n) + n/8) * sizeof(struct xtcpcb); 909 return (0); 910 } 911 912 if (req->newptr != NULL) 913 return (EPERM); 914 915 /* 916 * OK, now we're committed to doing something. 917 */ 918 INP_INFO_RLOCK(&tcbinfo); 919 gencnt = tcbinfo.ipi_gencnt; 920 n = tcbinfo.ipi_count; 921 INP_INFO_RUNLOCK(&tcbinfo); 922 923 m = syncache_pcbcount(); 924 925 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 926 + (n + m) * sizeof(struct xtcpcb)); 927 if (error != 0) 928 return (error); 929 930 xig.xig_len = sizeof xig; 931 xig.xig_count = n + m; 932 xig.xig_gen = gencnt; 933 xig.xig_sogen = so_gencnt; 934 error = SYSCTL_OUT(req, &xig, sizeof xig); 935 if (error) 936 return (error); 937 938 error = syncache_pcblist(req, m, &pcb_count); 939 if (error) 940 return (error); 941 942 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 943 if (inp_list == NULL) 944 return (ENOMEM); 945 946 INP_INFO_RLOCK(&tcbinfo); 947 for (inp = LIST_FIRST(tcbinfo.ipi_listhead), i = 0; inp != NULL && i 948 < n; inp = LIST_NEXT(inp, inp_list)) { 949 INP_WLOCK(inp); 950 if (inp->inp_gencnt <= gencnt) { 951 /* 952 * XXX: This use of cr_cansee(), introduced with 953 * TCP state changes, is not quite right, but for 954 * now, better than nothing. 955 */ 956 if (inp->inp_vflag & INP_TIMEWAIT) { 957 if (intotw(inp) != NULL) 958 error = cr_cansee(req->td->td_ucred, 959 intotw(inp)->tw_cred); 960 else 961 error = EINVAL; /* Skip this inp. */ 962 } else 963 error = cr_canseesocket(req->td->td_ucred, 964 inp->inp_socket); 965 if (error == 0) 966 inp_list[i++] = inp; 967 } 968 INP_WUNLOCK(inp); 969 } 970 INP_INFO_RUNLOCK(&tcbinfo); 971 n = i; 972 973 error = 0; 974 for (i = 0; i < n; i++) { 975 inp = inp_list[i]; 976 INP_WLOCK(inp); 977 if (inp->inp_gencnt <= gencnt) { 978 struct xtcpcb xt; 979 void *inp_ppcb; 980 981 bzero(&xt, sizeof(xt)); 982 xt.xt_len = sizeof xt; 983 /* XXX should avoid extra copy */ 984 bcopy(inp, &xt.xt_inp, sizeof *inp); 985 inp_ppcb = inp->inp_ppcb; 986 if (inp_ppcb == NULL) 987 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 988 else if (inp->inp_vflag & INP_TIMEWAIT) { 989 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 990 xt.xt_tp.t_state = TCPS_TIME_WAIT; 991 } else 992 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 993 if (inp->inp_socket != NULL) 994 sotoxsocket(inp->inp_socket, &xt.xt_socket); 995 else { 996 bzero(&xt.xt_socket, sizeof xt.xt_socket); 997 xt.xt_socket.xso_protocol = IPPROTO_TCP; 998 } 999 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 1000 INP_WUNLOCK(inp); 1001 error = SYSCTL_OUT(req, &xt, sizeof xt); 1002 } else 1003 INP_WUNLOCK(inp); 1004 1005 } 1006 if (!error) { 1007 /* 1008 * Give the user an updated idea of our state. 1009 * If the generation differs from what we told 1010 * her before, she knows that something happened 1011 * while we were processing this request, and it 1012 * might be necessary to retry. 1013 */ 1014 INP_INFO_RLOCK(&tcbinfo); 1015 xig.xig_gen = tcbinfo.ipi_gencnt; 1016 xig.xig_sogen = so_gencnt; 1017 xig.xig_count = tcbinfo.ipi_count + pcb_count; 1018 INP_INFO_RUNLOCK(&tcbinfo); 1019 error = SYSCTL_OUT(req, &xig, sizeof xig); 1020 } 1021 free(inp_list, M_TEMP); 1022 return (error); 1023 } 1024 1025 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1026 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1027 1028 static int 1029 tcp_getcred(SYSCTL_HANDLER_ARGS) 1030 { 1031 struct xucred xuc; 1032 struct sockaddr_in addrs[2]; 1033 struct inpcb *inp; 1034 int error; 1035 1036 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1037 if (error) 1038 return (error); 1039 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1040 if (error) 1041 return (error); 1042 INP_INFO_RLOCK(&tcbinfo); 1043 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1044 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1045 if (inp == NULL) { 1046 error = ENOENT; 1047 goto outunlocked; 1048 } 1049 INP_WLOCK(inp); 1050 if (inp->inp_socket == NULL) { 1051 error = ENOENT; 1052 goto out; 1053 } 1054 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1055 if (error) 1056 goto out; 1057 cru2x(inp->inp_socket->so_cred, &xuc); 1058 out: 1059 INP_WUNLOCK(inp); 1060 outunlocked: 1061 INP_INFO_RUNLOCK(&tcbinfo); 1062 if (error == 0) 1063 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1064 return (error); 1065 } 1066 1067 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1068 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1069 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1070 1071 #ifdef INET6 1072 static int 1073 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1074 { 1075 struct xucred xuc; 1076 struct sockaddr_in6 addrs[2]; 1077 struct inpcb *inp; 1078 int error, mapped = 0; 1079 1080 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1081 if (error) 1082 return (error); 1083 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1084 if (error) 1085 return (error); 1086 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1087 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1088 return (error); 1089 } 1090 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1091 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1092 mapped = 1; 1093 else 1094 return (EINVAL); 1095 } 1096 1097 INP_INFO_RLOCK(&tcbinfo); 1098 if (mapped == 1) 1099 inp = in_pcblookup_hash(&tcbinfo, 1100 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1101 addrs[1].sin6_port, 1102 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1103 addrs[0].sin6_port, 1104 0, NULL); 1105 else 1106 inp = in6_pcblookup_hash(&tcbinfo, 1107 &addrs[1].sin6_addr, addrs[1].sin6_port, 1108 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1109 if (inp == NULL) { 1110 error = ENOENT; 1111 goto outunlocked; 1112 } 1113 INP_WLOCK(inp); 1114 if (inp->inp_socket == NULL) { 1115 error = ENOENT; 1116 goto out; 1117 } 1118 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1119 if (error) 1120 goto out; 1121 cru2x(inp->inp_socket->so_cred, &xuc); 1122 out: 1123 INP_WUNLOCK(inp); 1124 outunlocked: 1125 INP_INFO_RUNLOCK(&tcbinfo); 1126 if (error == 0) 1127 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1128 return (error); 1129 } 1130 1131 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1132 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1133 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1134 #endif 1135 1136 1137 void 1138 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1139 { 1140 struct ip *ip = vip; 1141 struct tcphdr *th; 1142 struct in_addr faddr; 1143 struct inpcb *inp; 1144 struct tcpcb *tp; 1145 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1146 struct icmp *icp; 1147 struct in_conninfo inc; 1148 tcp_seq icmp_tcp_seq; 1149 int mtu; 1150 1151 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1152 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1153 return; 1154 1155 if (cmd == PRC_MSGSIZE) 1156 notify = tcp_mtudisc; 1157 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1158 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1159 notify = tcp_drop_syn_sent; 1160 /* 1161 * Redirects don't need to be handled up here. 1162 */ 1163 else if (PRC_IS_REDIRECT(cmd)) 1164 return; 1165 /* 1166 * Source quench is depreciated. 1167 */ 1168 else if (cmd == PRC_QUENCH) 1169 return; 1170 /* 1171 * Hostdead is ugly because it goes linearly through all PCBs. 1172 * XXX: We never get this from ICMP, otherwise it makes an 1173 * excellent DoS attack on machines with many connections. 1174 */ 1175 else if (cmd == PRC_HOSTDEAD) 1176 ip = NULL; 1177 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1178 return; 1179 if (ip != NULL) { 1180 icp = (struct icmp *)((caddr_t)ip 1181 - offsetof(struct icmp, icmp_ip)); 1182 th = (struct tcphdr *)((caddr_t)ip 1183 + (ip->ip_hl << 2)); 1184 INP_INFO_WLOCK(&tcbinfo); 1185 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1186 ip->ip_src, th->th_sport, 0, NULL); 1187 if (inp != NULL) { 1188 INP_WLOCK(inp); 1189 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1190 !(inp->inp_vflag & INP_DROPPED) && 1191 !(inp->inp_socket == NULL)) { 1192 icmp_tcp_seq = htonl(th->th_seq); 1193 tp = intotcpcb(inp); 1194 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1195 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1196 if (cmd == PRC_MSGSIZE) { 1197 /* 1198 * MTU discovery: 1199 * If we got a needfrag set the MTU 1200 * in the route to the suggested new 1201 * value (if given) and then notify. 1202 */ 1203 bzero(&inc, sizeof(inc)); 1204 inc.inc_flags = 0; /* IPv4 */ 1205 inc.inc_faddr = faddr; 1206 inc.inc_fibnum = 1207 inp->inp_inc.inc_fibnum; 1208 1209 mtu = ntohs(icp->icmp_nextmtu); 1210 /* 1211 * If no alternative MTU was 1212 * proposed, try the next smaller 1213 * one. ip->ip_len has already 1214 * been swapped in icmp_input(). 1215 */ 1216 if (!mtu) 1217 mtu = ip_next_mtu(ip->ip_len, 1218 1); 1219 if (mtu < max(296, (tcp_minmss) 1220 + sizeof(struct tcpiphdr))) 1221 mtu = 0; 1222 if (!mtu) 1223 mtu = tcp_mssdflt 1224 + sizeof(struct tcpiphdr); 1225 /* 1226 * Only cache the the MTU if it 1227 * is smaller than the interface 1228 * or route MTU. tcp_mtudisc() 1229 * will do right thing by itself. 1230 */ 1231 if (mtu <= tcp_maxmtu(&inc, NULL)) 1232 tcp_hc_updatemtu(&inc, mtu); 1233 } 1234 1235 inp = (*notify)(inp, inetctlerrmap[cmd]); 1236 } 1237 } 1238 if (inp != NULL) 1239 INP_WUNLOCK(inp); 1240 } else { 1241 inc.inc_fport = th->th_dport; 1242 inc.inc_lport = th->th_sport; 1243 inc.inc_faddr = faddr; 1244 inc.inc_laddr = ip->ip_src; 1245 #ifdef INET6 1246 inc.inc_isipv6 = 0; 1247 #endif 1248 syncache_unreach(&inc, th); 1249 } 1250 INP_INFO_WUNLOCK(&tcbinfo); 1251 } else 1252 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1253 } 1254 1255 #ifdef INET6 1256 void 1257 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1258 { 1259 struct tcphdr th; 1260 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1261 struct ip6_hdr *ip6; 1262 struct mbuf *m; 1263 struct ip6ctlparam *ip6cp = NULL; 1264 const struct sockaddr_in6 *sa6_src = NULL; 1265 int off; 1266 struct tcp_portonly { 1267 u_int16_t th_sport; 1268 u_int16_t th_dport; 1269 } *thp; 1270 1271 if (sa->sa_family != AF_INET6 || 1272 sa->sa_len != sizeof(struct sockaddr_in6)) 1273 return; 1274 1275 if (cmd == PRC_MSGSIZE) 1276 notify = tcp_mtudisc; 1277 else if (!PRC_IS_REDIRECT(cmd) && 1278 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1279 return; 1280 /* Source quench is depreciated. */ 1281 else if (cmd == PRC_QUENCH) 1282 return; 1283 1284 /* if the parameter is from icmp6, decode it. */ 1285 if (d != NULL) { 1286 ip6cp = (struct ip6ctlparam *)d; 1287 m = ip6cp->ip6c_m; 1288 ip6 = ip6cp->ip6c_ip6; 1289 off = ip6cp->ip6c_off; 1290 sa6_src = ip6cp->ip6c_src; 1291 } else { 1292 m = NULL; 1293 ip6 = NULL; 1294 off = 0; /* fool gcc */ 1295 sa6_src = &sa6_any; 1296 } 1297 1298 if (ip6 != NULL) { 1299 struct in_conninfo inc; 1300 /* 1301 * XXX: We assume that when IPV6 is non NULL, 1302 * M and OFF are valid. 1303 */ 1304 1305 /* check if we can safely examine src and dst ports */ 1306 if (m->m_pkthdr.len < off + sizeof(*thp)) 1307 return; 1308 1309 bzero(&th, sizeof(th)); 1310 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1311 1312 in6_pcbnotify(&tcbinfo, sa, th.th_dport, 1313 (struct sockaddr *)ip6cp->ip6c_src, 1314 th.th_sport, cmd, NULL, notify); 1315 1316 inc.inc_fport = th.th_dport; 1317 inc.inc_lport = th.th_sport; 1318 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1319 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1320 inc.inc_isipv6 = 1; 1321 INP_INFO_WLOCK(&tcbinfo); 1322 syncache_unreach(&inc, &th); 1323 INP_INFO_WUNLOCK(&tcbinfo); 1324 } else 1325 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1326 0, cmd, NULL, notify); 1327 } 1328 #endif /* INET6 */ 1329 1330 1331 /* 1332 * Following is where TCP initial sequence number generation occurs. 1333 * 1334 * There are two places where we must use initial sequence numbers: 1335 * 1. In SYN-ACK packets. 1336 * 2. In SYN packets. 1337 * 1338 * All ISNs for SYN-ACK packets are generated by the syncache. See 1339 * tcp_syncache.c for details. 1340 * 1341 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1342 * depends on this property. In addition, these ISNs should be 1343 * unguessable so as to prevent connection hijacking. To satisfy 1344 * the requirements of this situation, the algorithm outlined in 1345 * RFC 1948 is used, with only small modifications. 1346 * 1347 * Implementation details: 1348 * 1349 * Time is based off the system timer, and is corrected so that it 1350 * increases by one megabyte per second. This allows for proper 1351 * recycling on high speed LANs while still leaving over an hour 1352 * before rollover. 1353 * 1354 * As reading the *exact* system time is too expensive to be done 1355 * whenever setting up a TCP connection, we increment the time 1356 * offset in two ways. First, a small random positive increment 1357 * is added to isn_offset for each connection that is set up. 1358 * Second, the function tcp_isn_tick fires once per clock tick 1359 * and increments isn_offset as necessary so that sequence numbers 1360 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1361 * random positive increments serve only to ensure that the same 1362 * exact sequence number is never sent out twice (as could otherwise 1363 * happen when a port is recycled in less than the system tick 1364 * interval.) 1365 * 1366 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1367 * between seeding of isn_secret. This is normally set to zero, 1368 * as reseeding should not be necessary. 1369 * 1370 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1371 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1372 * general, this means holding an exclusive (write) lock. 1373 */ 1374 1375 #define ISN_BYTES_PER_SECOND 1048576 1376 #define ISN_STATIC_INCREMENT 4096 1377 #define ISN_RANDOM_INCREMENT (4096 - 1) 1378 1379 static u_char isn_secret[32]; 1380 static int isn_last_reseed; 1381 static u_int32_t isn_offset, isn_offset_old; 1382 static MD5_CTX isn_ctx; 1383 1384 tcp_seq 1385 tcp_new_isn(struct tcpcb *tp) 1386 { 1387 u_int32_t md5_buffer[4]; 1388 tcp_seq new_isn; 1389 1390 INP_WLOCK_ASSERT(tp->t_inpcb); 1391 1392 ISN_LOCK(); 1393 /* Seed if this is the first use, reseed if requested. */ 1394 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1395 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1396 < (u_int)ticks))) { 1397 read_random(&isn_secret, sizeof(isn_secret)); 1398 isn_last_reseed = ticks; 1399 } 1400 1401 /* Compute the md5 hash and return the ISN. */ 1402 MD5Init(&isn_ctx); 1403 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1404 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1405 #ifdef INET6 1406 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1407 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1408 sizeof(struct in6_addr)); 1409 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1410 sizeof(struct in6_addr)); 1411 } else 1412 #endif 1413 { 1414 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1415 sizeof(struct in_addr)); 1416 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1417 sizeof(struct in_addr)); 1418 } 1419 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1420 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1421 new_isn = (tcp_seq) md5_buffer[0]; 1422 isn_offset += ISN_STATIC_INCREMENT + 1423 (arc4random() & ISN_RANDOM_INCREMENT); 1424 new_isn += isn_offset; 1425 ISN_UNLOCK(); 1426 return (new_isn); 1427 } 1428 1429 /* 1430 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary 1431 * to keep time flowing at a relatively constant rate. If the random 1432 * increments have already pushed us past the projected offset, do nothing. 1433 */ 1434 static void 1435 tcp_isn_tick(void *xtp) 1436 { 1437 u_int32_t projected_offset; 1438 1439 ISN_LOCK(); 1440 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1441 1442 if (SEQ_GT(projected_offset, isn_offset)) 1443 isn_offset = projected_offset; 1444 1445 isn_offset_old = isn_offset; 1446 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1447 ISN_UNLOCK(); 1448 } 1449 1450 /* 1451 * When a specific ICMP unreachable message is received and the 1452 * connection state is SYN-SENT, drop the connection. This behavior 1453 * is controlled by the icmp_may_rst sysctl. 1454 */ 1455 struct inpcb * 1456 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1457 { 1458 struct tcpcb *tp; 1459 1460 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1461 INP_WLOCK_ASSERT(inp); 1462 1463 if ((inp->inp_vflag & INP_TIMEWAIT) || 1464 (inp->inp_vflag & INP_DROPPED)) 1465 return (inp); 1466 1467 tp = intotcpcb(inp); 1468 if (tp->t_state != TCPS_SYN_SENT) 1469 return (inp); 1470 1471 tp = tcp_drop(tp, errno); 1472 if (tp != NULL) 1473 return (inp); 1474 else 1475 return (NULL); 1476 } 1477 1478 /* 1479 * When `need fragmentation' ICMP is received, update our idea of the MSS 1480 * based on the new value in the route. Also nudge TCP to send something, 1481 * since we know the packet we just sent was dropped. 1482 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1483 */ 1484 struct inpcb * 1485 tcp_mtudisc(struct inpcb *inp, int errno) 1486 { 1487 struct tcpcb *tp; 1488 struct socket *so = inp->inp_socket; 1489 u_int maxmtu; 1490 u_int romtu; 1491 int mss; 1492 #ifdef INET6 1493 int isipv6; 1494 #endif /* INET6 */ 1495 1496 INP_WLOCK_ASSERT(inp); 1497 if ((inp->inp_vflag & INP_TIMEWAIT) || 1498 (inp->inp_vflag & INP_DROPPED)) 1499 return (inp); 1500 1501 tp = intotcpcb(inp); 1502 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1503 1504 #ifdef INET6 1505 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1506 #endif 1507 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1508 romtu = 1509 #ifdef INET6 1510 isipv6 ? tcp_maxmtu6(&inp->inp_inc, NULL) : 1511 #endif /* INET6 */ 1512 tcp_maxmtu(&inp->inp_inc, NULL); 1513 if (!maxmtu) 1514 maxmtu = romtu; 1515 else 1516 maxmtu = min(maxmtu, romtu); 1517 if (!maxmtu) { 1518 tp->t_maxopd = tp->t_maxseg = 1519 #ifdef INET6 1520 isipv6 ? tcp_v6mssdflt : 1521 #endif /* INET6 */ 1522 tcp_mssdflt; 1523 return (inp); 1524 } 1525 mss = maxmtu - 1526 #ifdef INET6 1527 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1528 #endif /* INET6 */ 1529 sizeof(struct tcpiphdr) 1530 #ifdef INET6 1531 ) 1532 #endif /* INET6 */ 1533 ; 1534 1535 /* 1536 * XXX - The above conditional probably violates the TCP 1537 * spec. The problem is that, since we don't know the 1538 * other end's MSS, we are supposed to use a conservative 1539 * default. But, if we do that, then MTU discovery will 1540 * never actually take place, because the conservative 1541 * default is much less than the MTUs typically seen 1542 * on the Internet today. For the moment, we'll sweep 1543 * this under the carpet. 1544 * 1545 * The conservative default might not actually be a problem 1546 * if the only case this occurs is when sending an initial 1547 * SYN with options and data to a host we've never talked 1548 * to before. Then, they will reply with an MSS value which 1549 * will get recorded and the new parameters should get 1550 * recomputed. For Further Study. 1551 */ 1552 if (tp->t_maxopd <= mss) 1553 return (inp); 1554 tp->t_maxopd = mss; 1555 1556 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1557 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1558 mss -= TCPOLEN_TSTAMP_APPA; 1559 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1560 if (mss > MCLBYTES) 1561 mss &= ~(MCLBYTES-1); 1562 #else 1563 if (mss > MCLBYTES) 1564 mss = mss / MCLBYTES * MCLBYTES; 1565 #endif 1566 if (so->so_snd.sb_hiwat < mss) 1567 mss = so->so_snd.sb_hiwat; 1568 1569 tp->t_maxseg = mss; 1570 1571 tcpstat.tcps_mturesent++; 1572 tp->t_rtttime = 0; 1573 tp->snd_nxt = tp->snd_una; 1574 tcp_free_sackholes(tp); 1575 tp->snd_recover = tp->snd_max; 1576 if (tp->t_flags & TF_SACK_PERMIT) 1577 EXIT_FASTRECOVERY(tp); 1578 tcp_output_send(tp); 1579 return (inp); 1580 } 1581 1582 /* 1583 * Look-up the routing entry to the peer of this inpcb. If no route 1584 * is found and it cannot be allocated, then return NULL. This routine 1585 * is called by TCP routines that access the rmx structure and by tcp_mss 1586 * to get the interface MTU. 1587 */ 1588 u_long 1589 tcp_maxmtu(struct in_conninfo *inc, int *flags) 1590 { 1591 struct route sro; 1592 struct sockaddr_in *dst; 1593 struct ifnet *ifp; 1594 u_long maxmtu = 0; 1595 1596 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1597 1598 bzero(&sro, sizeof(sro)); 1599 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1600 dst = (struct sockaddr_in *)&sro.ro_dst; 1601 dst->sin_family = AF_INET; 1602 dst->sin_len = sizeof(*dst); 1603 dst->sin_addr = inc->inc_faddr; 1604 in_rtalloc_ign(&sro, RTF_CLONING, inc->inc_fibnum); 1605 } 1606 if (sro.ro_rt != NULL) { 1607 ifp = sro.ro_rt->rt_ifp; 1608 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1609 maxmtu = ifp->if_mtu; 1610 else 1611 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1612 1613 /* Report additional interface capabilities. */ 1614 if (flags != NULL) { 1615 if (ifp->if_capenable & IFCAP_TSO4 && 1616 ifp->if_hwassist & CSUM_TSO) 1617 *flags |= CSUM_TSO; 1618 } 1619 RTFREE(sro.ro_rt); 1620 } 1621 return (maxmtu); 1622 } 1623 1624 #ifdef INET6 1625 u_long 1626 tcp_maxmtu6(struct in_conninfo *inc, int *flags) 1627 { 1628 struct route_in6 sro6; 1629 struct ifnet *ifp; 1630 u_long maxmtu = 0; 1631 1632 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1633 1634 bzero(&sro6, sizeof(sro6)); 1635 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1636 sro6.ro_dst.sin6_family = AF_INET6; 1637 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1638 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1639 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1640 } 1641 if (sro6.ro_rt != NULL) { 1642 ifp = sro6.ro_rt->rt_ifp; 1643 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1644 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1645 else 1646 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1647 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1648 1649 /* Report additional interface capabilities. */ 1650 if (flags != NULL) { 1651 if (ifp->if_capenable & IFCAP_TSO6 && 1652 ifp->if_hwassist & CSUM_TSO) 1653 *flags |= CSUM_TSO; 1654 } 1655 RTFREE(sro6.ro_rt); 1656 } 1657 1658 return (maxmtu); 1659 } 1660 #endif /* INET6 */ 1661 1662 #ifdef IPSEC 1663 /* compute ESP/AH header size for TCP, including outer IP header. */ 1664 size_t 1665 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1666 { 1667 struct inpcb *inp; 1668 struct mbuf *m; 1669 size_t hdrsiz; 1670 struct ip *ip; 1671 #ifdef INET6 1672 struct ip6_hdr *ip6; 1673 #endif 1674 struct tcphdr *th; 1675 1676 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1677 return (0); 1678 MGETHDR(m, M_DONTWAIT, MT_DATA); 1679 if (!m) 1680 return (0); 1681 1682 #ifdef INET6 1683 if ((inp->inp_vflag & INP_IPV6) != 0) { 1684 ip6 = mtod(m, struct ip6_hdr *); 1685 th = (struct tcphdr *)(ip6 + 1); 1686 m->m_pkthdr.len = m->m_len = 1687 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1688 tcpip_fillheaders(inp, ip6, th); 1689 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1690 } else 1691 #endif /* INET6 */ 1692 { 1693 ip = mtod(m, struct ip *); 1694 th = (struct tcphdr *)(ip + 1); 1695 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1696 tcpip_fillheaders(inp, ip, th); 1697 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1698 } 1699 1700 m_free(m); 1701 return (hdrsiz); 1702 } 1703 #endif /* IPSEC */ 1704 1705 /* 1706 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1707 * 1708 * This code attempts to calculate the bandwidth-delay product as a 1709 * means of determining the optimal window size to maximize bandwidth, 1710 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1711 * routers. This code also does a fairly good job keeping RTTs in check 1712 * across slow links like modems. We implement an algorithm which is very 1713 * similar (but not meant to be) TCP/Vegas. The code operates on the 1714 * transmitter side of a TCP connection and so only effects the transmit 1715 * side of the connection. 1716 * 1717 * BACKGROUND: TCP makes no provision for the management of buffer space 1718 * at the end points or at the intermediate routers and switches. A TCP 1719 * stream, whether using NewReno or not, will eventually buffer as 1720 * many packets as it is able and the only reason this typically works is 1721 * due to the fairly small default buffers made available for a connection 1722 * (typicaly 16K or 32K). As machines use larger windows and/or window 1723 * scaling it is now fairly easy for even a single TCP connection to blow-out 1724 * all available buffer space not only on the local interface, but on 1725 * intermediate routers and switches as well. NewReno makes a misguided 1726 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1727 * then backing off, then steadily increasing the window again until another 1728 * failure occurs, ad-infinitum. This results in terrible oscillation that 1729 * is only made worse as network loads increase and the idea of intentionally 1730 * blowing out network buffers is, frankly, a terrible way to manage network 1731 * resources. 1732 * 1733 * It is far better to limit the transmit window prior to the failure 1734 * condition being achieved. There are two general ways to do this: First 1735 * you can 'scan' through different transmit window sizes and locate the 1736 * point where the RTT stops increasing, indicating that you have filled the 1737 * pipe, then scan backwards until you note that RTT stops decreasing, then 1738 * repeat ad-infinitum. This method works in principle but has severe 1739 * implementation issues due to RTT variances, timer granularity, and 1740 * instability in the algorithm which can lead to many false positives and 1741 * create oscillations as well as interact badly with other TCP streams 1742 * implementing the same algorithm. 1743 * 1744 * The second method is to limit the window to the bandwidth delay product 1745 * of the link. This is the method we implement. RTT variances and our 1746 * own manipulation of the congestion window, bwnd, can potentially 1747 * destabilize the algorithm. For this reason we have to stabilize the 1748 * elements used to calculate the window. We do this by using the minimum 1749 * observed RTT, the long term average of the observed bandwidth, and 1750 * by adding two segments worth of slop. It isn't perfect but it is able 1751 * to react to changing conditions and gives us a very stable basis on 1752 * which to extend the algorithm. 1753 */ 1754 void 1755 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1756 { 1757 u_long bw; 1758 u_long bwnd; 1759 int save_ticks; 1760 1761 INP_WLOCK_ASSERT(tp->t_inpcb); 1762 1763 /* 1764 * If inflight_enable is disabled in the middle of a tcp connection, 1765 * make sure snd_bwnd is effectively disabled. 1766 */ 1767 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 1768 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1769 tp->snd_bandwidth = 0; 1770 return; 1771 } 1772 1773 /* 1774 * Figure out the bandwidth. Due to the tick granularity this 1775 * is a very rough number and it MUST be averaged over a fairly 1776 * long period of time. XXX we need to take into account a link 1777 * that is not using all available bandwidth, but for now our 1778 * slop will ramp us up if this case occurs and the bandwidth later 1779 * increases. 1780 * 1781 * Note: if ticks rollover 'bw' may wind up negative. We must 1782 * effectively reset t_bw_rtttime for this case. 1783 */ 1784 save_ticks = ticks; 1785 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1786 return; 1787 1788 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1789 (save_ticks - tp->t_bw_rtttime); 1790 tp->t_bw_rtttime = save_ticks; 1791 tp->t_bw_rtseq = ack_seq; 1792 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1793 return; 1794 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1795 1796 tp->snd_bandwidth = bw; 1797 1798 /* 1799 * Calculate the semi-static bandwidth delay product, plus two maximal 1800 * segments. The additional slop puts us squarely in the sweet 1801 * spot and also handles the bandwidth run-up case and stabilization. 1802 * Without the slop we could be locking ourselves into a lower 1803 * bandwidth. 1804 * 1805 * Situations Handled: 1806 * (1) Prevents over-queueing of packets on LANs, especially on 1807 * high speed LANs, allowing larger TCP buffers to be 1808 * specified, and also does a good job preventing 1809 * over-queueing of packets over choke points like modems 1810 * (at least for the transmit side). 1811 * 1812 * (2) Is able to handle changing network loads (bandwidth 1813 * drops so bwnd drops, bandwidth increases so bwnd 1814 * increases). 1815 * 1816 * (3) Theoretically should stabilize in the face of multiple 1817 * connections implementing the same algorithm (this may need 1818 * a little work). 1819 * 1820 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1821 * be adjusted with a sysctl but typically only needs to be 1822 * on very slow connections. A value no smaller then 5 1823 * should be used, but only reduce this default if you have 1824 * no other choice. 1825 */ 1826 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1827 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 1828 #undef USERTT 1829 1830 if (tcp_inflight_debug > 0) { 1831 static int ltime; 1832 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1833 ltime = ticks; 1834 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1835 tp, 1836 bw, 1837 tp->t_rttbest, 1838 tp->t_srtt, 1839 bwnd 1840 ); 1841 } 1842 } 1843 if ((long)bwnd < tcp_inflight_min) 1844 bwnd = tcp_inflight_min; 1845 if (bwnd > tcp_inflight_max) 1846 bwnd = tcp_inflight_max; 1847 if ((long)bwnd < tp->t_maxseg * 2) 1848 bwnd = tp->t_maxseg * 2; 1849 tp->snd_bwnd = bwnd; 1850 } 1851 1852 #ifdef TCP_SIGNATURE 1853 /* 1854 * Callback function invoked by m_apply() to digest TCP segment data 1855 * contained within an mbuf chain. 1856 */ 1857 static int 1858 tcp_signature_apply(void *fstate, void *data, u_int len) 1859 { 1860 1861 MD5Update(fstate, (u_char *)data, len); 1862 return (0); 1863 } 1864 1865 /* 1866 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 1867 * 1868 * Parameters: 1869 * m pointer to head of mbuf chain 1870 * off0 offset to TCP header within the mbuf chain 1871 * len length of TCP segment data, excluding options 1872 * optlen length of TCP segment options 1873 * buf pointer to storage for computed MD5 digest 1874 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1875 * 1876 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1877 * When called from tcp_input(), we can be sure that th_sum has been 1878 * zeroed out and verified already. 1879 * 1880 * This function is for IPv4 use only. Calling this function with an 1881 * IPv6 packet in the mbuf chain will yield undefined results. 1882 * 1883 * Return 0 if successful, otherwise return -1. 1884 * 1885 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1886 * search with the destination IP address, and a 'magic SPI' to be 1887 * determined by the application. This is hardcoded elsewhere to 1179 1888 * right now. Another branch of this code exists which uses the SPD to 1889 * specify per-application flows but it is unstable. 1890 */ 1891 int 1892 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 1893 u_char *buf, u_int direction) 1894 { 1895 union sockaddr_union dst; 1896 struct ippseudo ippseudo; 1897 MD5_CTX ctx; 1898 int doff; 1899 struct ip *ip; 1900 struct ipovly *ipovly; 1901 struct secasvar *sav; 1902 struct tcphdr *th; 1903 u_short savecsum; 1904 1905 KASSERT(m != NULL, ("NULL mbuf chain")); 1906 KASSERT(buf != NULL, ("NULL signature pointer")); 1907 1908 /* Extract the destination from the IP header in the mbuf. */ 1909 ip = mtod(m, struct ip *); 1910 bzero(&dst, sizeof(union sockaddr_union)); 1911 dst.sa.sa_len = sizeof(struct sockaddr_in); 1912 dst.sa.sa_family = AF_INET; 1913 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1914 ip->ip_src : ip->ip_dst; 1915 1916 /* Look up an SADB entry which matches the address of the peer. */ 1917 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 1918 if (sav == NULL) { 1919 printf("%s: SADB lookup failed for %s\n", __func__, 1920 inet_ntoa(dst.sin.sin_addr)); 1921 return (EINVAL); 1922 } 1923 1924 MD5Init(&ctx); 1925 ipovly = (struct ipovly *)ip; 1926 th = (struct tcphdr *)((u_char *)ip + off0); 1927 doff = off0 + sizeof(struct tcphdr) + optlen; 1928 1929 /* 1930 * Step 1: Update MD5 hash with IP pseudo-header. 1931 * 1932 * XXX The ippseudo header MUST be digested in network byte order, 1933 * or else we'll fail the regression test. Assume all fields we've 1934 * been doing arithmetic on have been in host byte order. 1935 * XXX One cannot depend on ipovly->ih_len here. When called from 1936 * tcp_output(), the underlying ip_len member has not yet been set. 1937 */ 1938 ippseudo.ippseudo_src = ipovly->ih_src; 1939 ippseudo.ippseudo_dst = ipovly->ih_dst; 1940 ippseudo.ippseudo_pad = 0; 1941 ippseudo.ippseudo_p = IPPROTO_TCP; 1942 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 1943 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 1944 1945 /* 1946 * Step 2: Update MD5 hash with TCP header, excluding options. 1947 * The TCP checksum must be set to zero. 1948 */ 1949 savecsum = th->th_sum; 1950 th->th_sum = 0; 1951 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 1952 th->th_sum = savecsum; 1953 1954 /* 1955 * Step 3: Update MD5 hash with TCP segment data. 1956 * Use m_apply() to avoid an early m_pullup(). 1957 */ 1958 if (len > 0) 1959 m_apply(m, doff, len, tcp_signature_apply, &ctx); 1960 1961 /* 1962 * Step 4: Update MD5 hash with shared secret. 1963 */ 1964 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth)); 1965 MD5Final(buf, &ctx); 1966 1967 key_sa_recordxfer(sav, m); 1968 KEY_FREESAV(&sav); 1969 return (0); 1970 } 1971 #endif /* TCP_SIGNATURE */ 1972 1973 static int 1974 sysctl_drop(SYSCTL_HANDLER_ARGS) 1975 { 1976 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 1977 struct sockaddr_storage addrs[2]; 1978 struct inpcb *inp; 1979 struct tcpcb *tp; 1980 struct tcptw *tw; 1981 struct sockaddr_in *fin, *lin; 1982 #ifdef INET6 1983 struct sockaddr_in6 *fin6, *lin6; 1984 struct in6_addr f6, l6; 1985 #endif 1986 int error; 1987 1988 inp = NULL; 1989 fin = lin = NULL; 1990 #ifdef INET6 1991 fin6 = lin6 = NULL; 1992 #endif 1993 error = 0; 1994 1995 if (req->oldptr != NULL || req->oldlen != 0) 1996 return (EINVAL); 1997 if (req->newptr == NULL) 1998 return (EPERM); 1999 if (req->newlen < sizeof(addrs)) 2000 return (ENOMEM); 2001 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2002 if (error) 2003 return (error); 2004 2005 switch (addrs[0].ss_family) { 2006 #ifdef INET6 2007 case AF_INET6: 2008 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2009 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2010 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2011 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2012 return (EINVAL); 2013 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2014 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2015 return (EINVAL); 2016 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2017 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2018 fin = (struct sockaddr_in *)&addrs[0]; 2019 lin = (struct sockaddr_in *)&addrs[1]; 2020 break; 2021 } 2022 error = sa6_embedscope(fin6, ip6_use_defzone); 2023 if (error) 2024 return (error); 2025 error = sa6_embedscope(lin6, ip6_use_defzone); 2026 if (error) 2027 return (error); 2028 break; 2029 #endif 2030 case AF_INET: 2031 fin = (struct sockaddr_in *)&addrs[0]; 2032 lin = (struct sockaddr_in *)&addrs[1]; 2033 if (fin->sin_len != sizeof(struct sockaddr_in) || 2034 lin->sin_len != sizeof(struct sockaddr_in)) 2035 return (EINVAL); 2036 break; 2037 default: 2038 return (EINVAL); 2039 } 2040 INP_INFO_WLOCK(&tcbinfo); 2041 switch (addrs[0].ss_family) { 2042 #ifdef INET6 2043 case AF_INET6: 2044 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2045 &l6, lin6->sin6_port, 0, NULL); 2046 break; 2047 #endif 2048 case AF_INET: 2049 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2050 lin->sin_addr, lin->sin_port, 0, NULL); 2051 break; 2052 } 2053 if (inp != NULL) { 2054 INP_WLOCK(inp); 2055 if (inp->inp_vflag & INP_TIMEWAIT) { 2056 /* 2057 * XXXRW: There currently exists a state where an 2058 * inpcb is present, but its timewait state has been 2059 * discarded. For now, don't allow dropping of this 2060 * type of inpcb. 2061 */ 2062 tw = intotw(inp); 2063 if (tw != NULL) 2064 tcp_twclose(tw, 0); 2065 else 2066 INP_WUNLOCK(inp); 2067 } else if (!(inp->inp_vflag & INP_DROPPED) && 2068 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2069 tp = intotcpcb(inp); 2070 tp = tcp_drop(tp, ECONNABORTED); 2071 if (tp != NULL) 2072 INP_WUNLOCK(inp); 2073 } else 2074 INP_WUNLOCK(inp); 2075 } else 2076 error = ESRCH; 2077 INP_INFO_WUNLOCK(&tcbinfo); 2078 return (error); 2079 } 2080 2081 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2082 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2083 0, sysctl_drop, "", "Drop TCP connection"); 2084 2085 /* 2086 * Generate a standardized TCP log line for use throughout the 2087 * tcp subsystem. Memory allocation is done with M_NOWAIT to 2088 * allow use in the interrupt context. 2089 * 2090 * NB: The caller MUST free(s, M_TCPLOG) the returned string. 2091 * NB: The function may return NULL if memory allocation failed. 2092 * 2093 * Due to header inclusion and ordering limitations the struct ip 2094 * and ip6_hdr pointers have to be passed as void pointers. 2095 */ 2096 char * 2097 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, 2098 const void *ip6hdr) 2099 { 2100 char *s, *sp; 2101 size_t size; 2102 struct ip *ip; 2103 #ifdef INET6 2104 const struct ip6_hdr *ip6; 2105 2106 ip6 = (const struct ip6_hdr *)ip6hdr; 2107 #endif /* INET6 */ 2108 ip = (struct ip *)ip4hdr; 2109 2110 /* 2111 * The log line looks like this: 2112 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>" 2113 */ 2114 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") + 2115 sizeof(PRINT_TH_FLAGS) + 1 + 2116 #ifdef INET6 2117 2 * INET6_ADDRSTRLEN; 2118 #else 2119 2 * INET_ADDRSTRLEN; 2120 #endif /* INET6 */ 2121 2122 /* Is logging enabled? */ 2123 if (tcp_log_debug == 0 && tcp_log_in_vain == 0) 2124 return (NULL); 2125 2126 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT); 2127 if (s == NULL) 2128 return (NULL); 2129 2130 strcat(s, "TCP: ["); 2131 sp = s + strlen(s); 2132 2133 if (inc && inc->inc_isipv6 == 0) { 2134 inet_ntoa_r(inc->inc_faddr, sp); 2135 sp = s + strlen(s); 2136 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2137 sp = s + strlen(s); 2138 inet_ntoa_r(inc->inc_laddr, sp); 2139 sp = s + strlen(s); 2140 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2141 #ifdef INET6 2142 } else if (inc) { 2143 ip6_sprintf(sp, &inc->inc6_faddr); 2144 sp = s + strlen(s); 2145 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2146 sp = s + strlen(s); 2147 ip6_sprintf(sp, &inc->inc6_laddr); 2148 sp = s + strlen(s); 2149 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2150 } else if (ip6 && th) { 2151 ip6_sprintf(sp, &ip6->ip6_src); 2152 sp = s + strlen(s); 2153 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2154 sp = s + strlen(s); 2155 ip6_sprintf(sp, &ip6->ip6_dst); 2156 sp = s + strlen(s); 2157 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2158 #endif /* INET6 */ 2159 } else if (ip && th) { 2160 inet_ntoa_r(ip->ip_src, sp); 2161 sp = s + strlen(s); 2162 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2163 sp = s + strlen(s); 2164 inet_ntoa_r(ip->ip_dst, sp); 2165 sp = s + strlen(s); 2166 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2167 } else { 2168 free(s, M_TCPLOG); 2169 return (NULL); 2170 } 2171 sp = s + strlen(s); 2172 if (th) 2173 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS); 2174 if (*(s + size - 1) != '\0') 2175 panic("%s: string too long", __func__); 2176 return (s); 2177 } 2178