Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_subr.c
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1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 */ 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 #include <sys/syslog.h> 106 #endif /*IPSEC*/ 107 108 #include <machine/in_cksum.h> 109 #include <sys/md5.h> 110 111 #include <security/mac/mac_framework.h> 112 113 int tcp_mssdflt = TCP_MSS; 114 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 115 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size"); 116 117 #ifdef INET6 118 int tcp_v6mssdflt = TCP6_MSS; 119 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 120 CTLFLAG_RW, &tcp_v6mssdflt , 0, 121 "Default TCP Maximum Segment Size for IPv6"); 122 #endif 123 124 /* 125 * Minimum MSS we accept and use. This prevents DoS attacks where 126 * we are forced to a ridiculous low MSS like 20 and send hundreds 127 * of packets instead of one. The effect scales with the available 128 * bandwidth and quickly saturates the CPU and network interface 129 * with packet generation and sending. Set to zero to disable MINMSS 130 * checking. This setting prevents us from sending too small packets. 131 */ 132 int tcp_minmss = TCP_MINMSS; 133 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 134 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 135 136 int tcp_do_rfc1323 = 1; 137 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 138 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions"); 139 140 static int tcp_log_debug = 0; 141 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW, 142 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments"); 143 144 static int tcp_tcbhashsize = 0; 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 146 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 147 148 static int do_tcpdrain = 1; 149 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, 150 &do_tcpdrain, 0, 151 "Enable tcp_drain routine for extra help when low on mbufs"); 152 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 154 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 155 156 static int icmp_may_rst = 1; 157 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, 158 &icmp_may_rst, 0, 159 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 160 161 static int tcp_isn_reseed_interval = 0; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 163 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 164 165 /* 166 * TCP bandwidth limiting sysctls. Note that the default lower bound of 167 * 1024 exists only for debugging. A good production default would be 168 * something like 6100. 169 */ 170 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 171 "TCP inflight data limiting"); 172 173 static int tcp_inflight_enable = 1; 174 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW, 175 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 176 177 static int tcp_inflight_debug = 0; 178 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 179 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 180 181 static int tcp_inflight_rttthresh; 182 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 183 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 184 "RTT threshold below which inflight will deactivate itself"); 185 186 static int tcp_inflight_min = 6144; 187 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW, 188 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 189 190 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 191 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW, 192 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 193 194 static int tcp_inflight_stab = 20; 195 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW, 196 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 197 198 uma_zone_t sack_hole_zone; 199 200 static struct inpcb *tcp_notify(struct inpcb *, int); 201 static void tcp_isn_tick(void *); 202 203 /* 204 * Target size of TCP PCB hash tables. Must be a power of two. 205 * 206 * Note that this can be overridden by the kernel environment 207 * variable net.inet.tcp.tcbhashsize 208 */ 209 #ifndef TCBHASHSIZE 210 #define TCBHASHSIZE 512 211 #endif 212 213 /* 214 * XXX 215 * Callouts should be moved into struct tcp directly. They are currently 216 * separate because the tcpcb structure is exported to userland for sysctl 217 * parsing purposes, which do not know about callouts. 218 */ 219 struct tcpcb_mem { 220 struct tcpcb tcb; 221 struct tcp_timer tt; 222 }; 223 224 static uma_zone_t tcpcb_zone; 225 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); 226 struct callout isn_callout; 227 static struct mtx isn_mtx; 228 229 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) 230 #define ISN_LOCK() mtx_lock(&isn_mtx) 231 #define ISN_UNLOCK() mtx_unlock(&isn_mtx) 232 233 /* 234 * TCP initialization. 235 */ 236 static void 237 tcp_zone_change(void *tag) 238 { 239 240 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 241 uma_zone_set_max(tcpcb_zone, maxsockets); 242 tcp_tw_zone_change(); 243 } 244 245 static int 246 tcp_inpcb_init(void *mem, int size, int flags) 247 { 248 struct inpcb *inp = mem; 249 250 INP_LOCK_INIT(inp, "inp", "tcpinp"); 251 return (0); 252 } 253 254 void 255 tcp_init(void) 256 { 257 258 int hashsize = TCBHASHSIZE; 259 tcp_delacktime = TCPTV_DELACK; 260 tcp_keepinit = TCPTV_KEEP_INIT; 261 tcp_keepidle = TCPTV_KEEP_IDLE; 262 tcp_keepintvl = TCPTV_KEEPINTVL; 263 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 264 tcp_msl = TCPTV_MSL; 265 tcp_rexmit_min = TCPTV_MIN; 266 if (tcp_rexmit_min < 1) 267 tcp_rexmit_min = 1; 268 tcp_rexmit_slop = TCPTV_CPU_VAR; 269 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 270 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT; 271 272 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 273 LIST_INIT(&tcb); 274 tcbinfo.ipi_listhead = &tcb; 275 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 276 if (!powerof2(hashsize)) { 277 printf("WARNING: TCB hash size not a power of 2\n"); 278 hashsize = 512; /* safe default */ 279 } 280 tcp_tcbhashsize = hashsize; 281 tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB, 282 &tcbinfo.ipi_hashmask); 283 tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB, 284 &tcbinfo.ipi_porthashmask); 285 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 286 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 287 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 288 #ifdef INET6 289 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 290 #else /* INET6 */ 291 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 292 #endif /* INET6 */ 293 if (max_protohdr < TCP_MINPROTOHDR) 294 max_protohdr = TCP_MINPROTOHDR; 295 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 296 panic("tcp_init"); 297 #undef TCP_MINPROTOHDR 298 /* 299 * These have to be type stable for the benefit of the timers. 300 */ 301 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 302 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 303 uma_zone_set_max(tcpcb_zone, maxsockets); 304 tcp_tw_init(); 305 syncache_init(); 306 tcp_hc_init(); 307 tcp_reass_init(); 308 ISN_LOCK_INIT(); 309 callout_init(&isn_callout, CALLOUT_MPSAFE); 310 tcp_isn_tick(NULL); 311 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 312 SHUTDOWN_PRI_DEFAULT); 313 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 314 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 315 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, 316 EVENTHANDLER_PRI_ANY); 317 } 318 319 void 320 tcp_fini(void *xtp) 321 { 322 323 callout_stop(&isn_callout); 324 } 325 326 /* 327 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 328 * tcp_template used to store this data in mbufs, but we now recopy it out 329 * of the tcpcb each time to conserve mbufs. 330 */ 331 void 332 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 333 { 334 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 335 336 INP_WLOCK_ASSERT(inp); 337 338 #ifdef INET6 339 if ((inp->inp_vflag & INP_IPV6) != 0) { 340 struct ip6_hdr *ip6; 341 342 ip6 = (struct ip6_hdr *)ip_ptr; 343 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 344 (inp->inp_flow & IPV6_FLOWINFO_MASK); 345 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 346 (IPV6_VERSION & IPV6_VERSION_MASK); 347 ip6->ip6_nxt = IPPROTO_TCP; 348 ip6->ip6_plen = htons(sizeof(struct tcphdr)); 349 ip6->ip6_src = inp->in6p_laddr; 350 ip6->ip6_dst = inp->in6p_faddr; 351 } else 352 #endif 353 { 354 struct ip *ip; 355 356 ip = (struct ip *)ip_ptr; 357 ip->ip_v = IPVERSION; 358 ip->ip_hl = 5; 359 ip->ip_tos = inp->inp_ip_tos; 360 ip->ip_len = 0; 361 ip->ip_id = 0; 362 ip->ip_off = 0; 363 ip->ip_ttl = inp->inp_ip_ttl; 364 ip->ip_sum = 0; 365 ip->ip_p = IPPROTO_TCP; 366 ip->ip_src = inp->inp_laddr; 367 ip->ip_dst = inp->inp_faddr; 368 } 369 th->th_sport = inp->inp_lport; 370 th->th_dport = inp->inp_fport; 371 th->th_seq = 0; 372 th->th_ack = 0; 373 th->th_x2 = 0; 374 th->th_off = 5; 375 th->th_flags = 0; 376 th->th_win = 0; 377 th->th_urp = 0; 378 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 379 } 380 381 /* 382 * Create template to be used to send tcp packets on a connection. 383 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 384 * use for this function is in keepalives, which use tcp_respond. 385 */ 386 struct tcptemp * 387 tcpip_maketemplate(struct inpcb *inp) 388 { 389 struct tcptemp *t; 390 391 t = malloc(sizeof(*t), M_TEMP, M_NOWAIT); 392 if (t == NULL) 393 return (NULL); 394 tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t); 395 return (t); 396 } 397 398 /* 399 * Send a single message to the TCP at address specified by 400 * the given TCP/IP header. If m == NULL, then we make a copy 401 * of the tcpiphdr at ti and send directly to the addressed host. 402 * This is used to force keep alive messages out using the TCP 403 * template for a connection. If flags are given then we send 404 * a message back to the TCP which originated the * segment ti, 405 * and discard the mbuf containing it and any other attached mbufs. 406 * 407 * In any case the ack and sequence number of the transmitted 408 * segment are as specified by the parameters. 409 * 410 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 411 */ 412 void 413 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 414 tcp_seq ack, tcp_seq seq, int flags) 415 { 416 int tlen; 417 int win = 0; 418 struct ip *ip; 419 struct tcphdr *nth; 420 #ifdef INET6 421 struct ip6_hdr *ip6; 422 int isipv6; 423 #endif /* INET6 */ 424 int ipflags = 0; 425 struct inpcb *inp; 426 427 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 428 429 #ifdef INET6 430 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 431 ip6 = ipgen; 432 #endif /* INET6 */ 433 ip = ipgen; 434 435 if (tp != NULL) { 436 inp = tp->t_inpcb; 437 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 438 INP_WLOCK_ASSERT(inp); 439 } else 440 inp = NULL; 441 442 if (tp != NULL) { 443 if (!(flags & TH_RST)) { 444 win = sbspace(&inp->inp_socket->so_rcv); 445 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 446 win = (long)TCP_MAXWIN << tp->rcv_scale; 447 } 448 } 449 if (m == NULL) { 450 m = m_gethdr(M_DONTWAIT, MT_DATA); 451 if (m == NULL) 452 return; 453 tlen = 0; 454 m->m_data += max_linkhdr; 455 #ifdef INET6 456 if (isipv6) { 457 bcopy((caddr_t)ip6, mtod(m, caddr_t), 458 sizeof(struct ip6_hdr)); 459 ip6 = mtod(m, struct ip6_hdr *); 460 nth = (struct tcphdr *)(ip6 + 1); 461 } else 462 #endif /* INET6 */ 463 { 464 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 465 ip = mtod(m, struct ip *); 466 nth = (struct tcphdr *)(ip + 1); 467 } 468 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 469 flags = TH_ACK; 470 } else { 471 /* 472 * reuse the mbuf. 473 * XXX MRT We inherrit the FIB, which is lucky. 474 */ 475 m_freem(m->m_next); 476 m->m_next = NULL; 477 m->m_data = (caddr_t)ipgen; 478 /* m_len is set later */ 479 tlen = 0; 480 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 481 #ifdef INET6 482 if (isipv6) { 483 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 484 nth = (struct tcphdr *)(ip6 + 1); 485 } else 486 #endif /* INET6 */ 487 { 488 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t); 489 nth = (struct tcphdr *)(ip + 1); 490 } 491 if (th != nth) { 492 /* 493 * this is usually a case when an extension header 494 * exists between the IPv6 header and the 495 * TCP header. 496 */ 497 nth->th_sport = th->th_sport; 498 nth->th_dport = th->th_dport; 499 } 500 xchg(nth->th_dport, nth->th_sport, uint16_t); 501 #undef xchg 502 } 503 #ifdef INET6 504 if (isipv6) { 505 ip6->ip6_flow = 0; 506 ip6->ip6_vfc = IPV6_VERSION; 507 ip6->ip6_nxt = IPPROTO_TCP; 508 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 509 tlen)); 510 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 511 } else 512 #endif 513 { 514 tlen += sizeof (struct tcpiphdr); 515 ip->ip_len = tlen; 516 ip->ip_ttl = ip_defttl; 517 if (path_mtu_discovery) 518 ip->ip_off |= IP_DF; 519 } 520 m->m_len = tlen; 521 m->m_pkthdr.len = tlen; 522 m->m_pkthdr.rcvif = NULL; 523 #ifdef MAC 524 if (inp != NULL) { 525 /* 526 * Packet is associated with a socket, so allow the 527 * label of the response to reflect the socket label. 528 */ 529 INP_WLOCK_ASSERT(inp); 530 mac_create_mbuf_from_inpcb(inp, m); 531 } else { 532 /* 533 * Packet is not associated with a socket, so possibly 534 * update the label in place. 535 */ 536 mac_reflect_mbuf_tcp(m); 537 } 538 #endif 539 nth->th_seq = htonl(seq); 540 nth->th_ack = htonl(ack); 541 nth->th_x2 = 0; 542 nth->th_off = sizeof (struct tcphdr) >> 2; 543 nth->th_flags = flags; 544 if (tp != NULL) 545 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 546 else 547 nth->th_win = htons((u_short)win); 548 nth->th_urp = 0; 549 #ifdef INET6 550 if (isipv6) { 551 nth->th_sum = 0; 552 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 553 sizeof(struct ip6_hdr), 554 tlen - sizeof(struct ip6_hdr)); 555 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 556 NULL, NULL); 557 } else 558 #endif /* INET6 */ 559 { 560 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 561 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 562 m->m_pkthdr.csum_flags = CSUM_TCP; 563 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 564 } 565 #ifdef TCPDEBUG 566 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 567 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 568 #endif 569 #ifdef INET6 570 if (isipv6) 571 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 572 else 573 #endif /* INET6 */ 574 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 575 } 576 577 /* 578 * Create a new TCP control block, making an 579 * empty reassembly queue and hooking it to the argument 580 * protocol control block. The `inp' parameter must have 581 * come from the zone allocator set up in tcp_init(). 582 */ 583 struct tcpcb * 584 tcp_newtcpcb(struct inpcb *inp) 585 { 586 struct tcpcb_mem *tm; 587 struct tcpcb *tp; 588 #ifdef INET6 589 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 590 #endif /* INET6 */ 591 592 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 593 if (tm == NULL) 594 return (NULL); 595 tp = &tm->tcb; 596 tp->t_timers = &tm->tt; 597 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 598 tp->t_maxseg = tp->t_maxopd = 599 #ifdef INET6 600 isipv6 ? tcp_v6mssdflt : 601 #endif /* INET6 */ 602 tcp_mssdflt; 603 604 /* Set up our timeouts. */ 605 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE); 606 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE); 607 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE); 608 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE); 609 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE); 610 611 if (tcp_do_rfc1323) 612 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 613 if (tcp_do_sack) 614 tp->t_flags |= TF_SACK_PERMIT; 615 TAILQ_INIT(&tp->snd_holes); 616 tp->t_inpcb = inp; /* XXX */ 617 /* 618 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 619 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 620 * reasonable initial retransmit time. 621 */ 622 tp->t_srtt = TCPTV_SRTTBASE; 623 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 624 tp->t_rttmin = tcp_rexmit_min; 625 tp->t_rxtcur = TCPTV_RTOBASE; 626 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 627 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 628 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 629 tp->t_rcvtime = ticks; 630 tp->t_bw_rtttime = ticks; 631 /* 632 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 633 * because the socket may be bound to an IPv6 wildcard address, 634 * which may match an IPv4-mapped IPv6 address. 635 */ 636 inp->inp_ip_ttl = ip_defttl; 637 inp->inp_ppcb = tp; 638 return (tp); /* XXX */ 639 } 640 641 /* 642 * Drop a TCP connection, reporting 643 * the specified error. If connection is synchronized, 644 * then send a RST to peer. 645 */ 646 struct tcpcb * 647 tcp_drop(struct tcpcb *tp, int errno) 648 { 649 struct socket *so = tp->t_inpcb->inp_socket; 650 651 INP_INFO_WLOCK_ASSERT(&tcbinfo); 652 INP_WLOCK_ASSERT(tp->t_inpcb); 653 654 if (TCPS_HAVERCVDSYN(tp->t_state)) { 655 tp->t_state = TCPS_CLOSED; 656 (void) tcp_output_reset(tp); 657 tcpstat.tcps_drops++; 658 } else 659 tcpstat.tcps_conndrops++; 660 if (errno == ETIMEDOUT && tp->t_softerror) 661 errno = tp->t_softerror; 662 so->so_error = errno; 663 return (tcp_close(tp)); 664 } 665 666 void 667 tcp_discardcb(struct tcpcb *tp) 668 { 669 struct tseg_qent *q; 670 struct inpcb *inp = tp->t_inpcb; 671 struct socket *so = inp->inp_socket; 672 #ifdef INET6 673 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 674 #endif /* INET6 */ 675 676 INP_WLOCK_ASSERT(inp); 677 678 /* 679 * Make sure that all of our timers are stopped before we 680 * delete the PCB. 681 */ 682 callout_stop(&tp->t_timers->tt_rexmt); 683 callout_stop(&tp->t_timers->tt_persist); 684 callout_stop(&tp->t_timers->tt_keep); 685 callout_stop(&tp->t_timers->tt_2msl); 686 callout_stop(&tp->t_timers->tt_delack); 687 688 /* 689 * If we got enough samples through the srtt filter, 690 * save the rtt and rttvar in the routing entry. 691 * 'Enough' is arbitrarily defined as 4 rtt samples. 692 * 4 samples is enough for the srtt filter to converge 693 * to within enough % of the correct value; fewer samples 694 * and we could save a bogus rtt. The danger is not high 695 * as tcp quickly recovers from everything. 696 * XXX: Works very well but needs some more statistics! 697 */ 698 if (tp->t_rttupdated >= 4) { 699 struct hc_metrics_lite metrics; 700 u_long ssthresh; 701 702 bzero(&metrics, sizeof(metrics)); 703 /* 704 * Update the ssthresh always when the conditions below 705 * are satisfied. This gives us better new start value 706 * for the congestion avoidance for new connections. 707 * ssthresh is only set if packet loss occured on a session. 708 * 709 * XXXRW: 'so' may be NULL here, and/or socket buffer may be 710 * being torn down. Ideally this code would not use 'so'. 711 */ 712 ssthresh = tp->snd_ssthresh; 713 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 714 /* 715 * convert the limit from user data bytes to 716 * packets then to packet data bytes. 717 */ 718 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 719 if (ssthresh < 2) 720 ssthresh = 2; 721 ssthresh *= (u_long)(tp->t_maxseg + 722 #ifdef INET6 723 (isipv6 ? sizeof (struct ip6_hdr) + 724 sizeof (struct tcphdr) : 725 #endif 726 sizeof (struct tcpiphdr) 727 #ifdef INET6 728 ) 729 #endif 730 ); 731 } else 732 ssthresh = 0; 733 metrics.rmx_ssthresh = ssthresh; 734 735 metrics.rmx_rtt = tp->t_srtt; 736 metrics.rmx_rttvar = tp->t_rttvar; 737 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 738 metrics.rmx_bandwidth = tp->snd_bandwidth; 739 metrics.rmx_cwnd = tp->snd_cwnd; 740 metrics.rmx_sendpipe = 0; 741 metrics.rmx_recvpipe = 0; 742 743 tcp_hc_update(&inp->inp_inc, &metrics); 744 } 745 746 /* free the reassembly queue, if any */ 747 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 748 LIST_REMOVE(q, tqe_q); 749 m_freem(q->tqe_m); 750 uma_zfree(tcp_reass_zone, q); 751 tp->t_segqlen--; 752 tcp_reass_qsize--; 753 } 754 /* Disconnect offload device, if any. */ 755 tcp_offload_detach(tp); 756 757 tcp_free_sackholes(tp); 758 inp->inp_ppcb = NULL; 759 tp->t_inpcb = NULL; 760 uma_zfree(tcpcb_zone, tp); 761 } 762 763 /* 764 * Attempt to close a TCP control block, marking it as dropped, and freeing 765 * the socket if we hold the only reference. 766 */ 767 struct tcpcb * 768 tcp_close(struct tcpcb *tp) 769 { 770 struct inpcb *inp = tp->t_inpcb; 771 struct socket *so; 772 773 INP_INFO_WLOCK_ASSERT(&tcbinfo); 774 INP_WLOCK_ASSERT(inp); 775 776 /* Notify any offload devices of listener close */ 777 if (tp->t_state == TCPS_LISTEN) 778 tcp_offload_listen_close(tp); 779 in_pcbdrop(inp); 780 tcpstat.tcps_closed++; 781 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 782 so = inp->inp_socket; 783 soisdisconnected(so); 784 if (inp->inp_flags & INP_SOCKREF) { 785 KASSERT(so->so_state & SS_PROTOREF, 786 ("tcp_close: !SS_PROTOREF")); 787 inp->inp_flags &= ~INP_SOCKREF; 788 INP_WUNLOCK(inp); 789 ACCEPT_LOCK(); 790 SOCK_LOCK(so); 791 so->so_state &= ~SS_PROTOREF; 792 sofree(so); 793 return (NULL); 794 } 795 return (tp); 796 } 797 798 void 799 tcp_drain(void) 800 { 801 802 if (do_tcpdrain) { 803 struct inpcb *inpb; 804 struct tcpcb *tcpb; 805 struct tseg_qent *te; 806 807 /* 808 * Walk the tcpbs, if existing, and flush the reassembly queue, 809 * if there is one... 810 * XXX: The "Net/3" implementation doesn't imply that the TCP 811 * reassembly queue should be flushed, but in a situation 812 * where we're really low on mbufs, this is potentially 813 * usefull. 814 */ 815 INP_INFO_RLOCK(&tcbinfo); 816 LIST_FOREACH(inpb, tcbinfo.ipi_listhead, inp_list) { 817 if (inpb->inp_flags & INP_TIMEWAIT) 818 continue; 819 INP_WLOCK(inpb); 820 if ((tcpb = intotcpcb(inpb)) != NULL) { 821 while ((te = LIST_FIRST(&tcpb->t_segq)) 822 != NULL) { 823 LIST_REMOVE(te, tqe_q); 824 m_freem(te->tqe_m); 825 uma_zfree(tcp_reass_zone, te); 826 tcpb->t_segqlen--; 827 tcp_reass_qsize--; 828 } 829 tcp_clean_sackreport(tcpb); 830 } 831 INP_WUNLOCK(inpb); 832 } 833 INP_INFO_RUNLOCK(&tcbinfo); 834 } 835 } 836 837 /* 838 * Notify a tcp user of an asynchronous error; 839 * store error as soft error, but wake up user 840 * (for now, won't do anything until can select for soft error). 841 * 842 * Do not wake up user since there currently is no mechanism for 843 * reporting soft errors (yet - a kqueue filter may be added). 844 */ 845 static struct inpcb * 846 tcp_notify(struct inpcb *inp, int error) 847 { 848 struct tcpcb *tp; 849 850 INP_INFO_WLOCK_ASSERT(&tcbinfo); 851 INP_WLOCK_ASSERT(inp); 852 853 if ((inp->inp_flags & INP_TIMEWAIT) || 854 (inp->inp_flags & INP_DROPPED)) 855 return (inp); 856 857 tp = intotcpcb(inp); 858 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 859 860 /* 861 * Ignore some errors if we are hooked up. 862 * If connection hasn't completed, has retransmitted several times, 863 * and receives a second error, give up now. This is better 864 * than waiting a long time to establish a connection that 865 * can never complete. 866 */ 867 if (tp->t_state == TCPS_ESTABLISHED && 868 (error == EHOSTUNREACH || error == ENETUNREACH || 869 error == EHOSTDOWN)) { 870 return (inp); 871 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 872 tp->t_softerror) { 873 tp = tcp_drop(tp, error); 874 if (tp != NULL) 875 return (inp); 876 else 877 return (NULL); 878 } else { 879 tp->t_softerror = error; 880 return (inp); 881 } 882 #if 0 883 wakeup( &so->so_timeo); 884 sorwakeup(so); 885 sowwakeup(so); 886 #endif 887 } 888 889 static int 890 tcp_pcblist(SYSCTL_HANDLER_ARGS) 891 { 892 int error, i, m, n, pcb_count; 893 struct inpcb *inp, **inp_list; 894 inp_gen_t gencnt; 895 struct xinpgen xig; 896 897 /* 898 * The process of preparing the TCB list is too time-consuming and 899 * resource-intensive to repeat twice on every request. 900 */ 901 if (req->oldptr == NULL) { 902 m = syncache_pcbcount(); 903 n = tcbinfo.ipi_count; 904 req->oldidx = 2 * (sizeof xig) 905 + ((m + n) + n/8) * sizeof(struct xtcpcb); 906 return (0); 907 } 908 909 if (req->newptr != NULL) 910 return (EPERM); 911 912 /* 913 * OK, now we're committed to doing something. 914 */ 915 INP_INFO_RLOCK(&tcbinfo); 916 gencnt = tcbinfo.ipi_gencnt; 917 n = tcbinfo.ipi_count; 918 INP_INFO_RUNLOCK(&tcbinfo); 919 920 m = syncache_pcbcount(); 921 922 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 923 + (n + m) * sizeof(struct xtcpcb)); 924 if (error != 0) 925 return (error); 926 927 xig.xig_len = sizeof xig; 928 xig.xig_count = n + m; 929 xig.xig_gen = gencnt; 930 xig.xig_sogen = so_gencnt; 931 error = SYSCTL_OUT(req, &xig, sizeof xig); 932 if (error) 933 return (error); 934 935 error = syncache_pcblist(req, m, &pcb_count); 936 if (error) 937 return (error); 938 939 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 940 if (inp_list == NULL) 941 return (ENOMEM); 942 943 INP_INFO_RLOCK(&tcbinfo); 944 for (inp = LIST_FIRST(tcbinfo.ipi_listhead), i = 0; inp != NULL && i 945 < n; inp = LIST_NEXT(inp, inp_list)) { 946 INP_RLOCK(inp); 947 if (inp->inp_gencnt <= gencnt) { 948 /* 949 * XXX: This use of cr_cansee(), introduced with 950 * TCP state changes, is not quite right, but for 951 * now, better than nothing. 952 */ 953 if (inp->inp_flags & INP_TIMEWAIT) { 954 if (intotw(inp) != NULL) 955 error = cr_cansee(req->td->td_ucred, 956 intotw(inp)->tw_cred); 957 else 958 error = EINVAL; /* Skip this inp. */ 959 } else 960 error = cr_canseeinpcb(req->td->td_ucred, inp); 961 if (error == 0) 962 inp_list[i++] = inp; 963 } 964 INP_RUNLOCK(inp); 965 } 966 INP_INFO_RUNLOCK(&tcbinfo); 967 n = i; 968 969 error = 0; 970 for (i = 0; i < n; i++) { 971 inp = inp_list[i]; 972 INP_RLOCK(inp); 973 if (inp->inp_gencnt <= gencnt) { 974 struct xtcpcb xt; 975 void *inp_ppcb; 976 977 bzero(&xt, sizeof(xt)); 978 xt.xt_len = sizeof xt; 979 /* XXX should avoid extra copy */ 980 bcopy(inp, &xt.xt_inp, sizeof *inp); 981 inp_ppcb = inp->inp_ppcb; 982 if (inp_ppcb == NULL) 983 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 984 else if (inp->inp_flags & INP_TIMEWAIT) { 985 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 986 xt.xt_tp.t_state = TCPS_TIME_WAIT; 987 } else 988 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 989 if (inp->inp_socket != NULL) 990 sotoxsocket(inp->inp_socket, &xt.xt_socket); 991 else { 992 bzero(&xt.xt_socket, sizeof xt.xt_socket); 993 xt.xt_socket.xso_protocol = IPPROTO_TCP; 994 } 995 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 996 INP_RUNLOCK(inp); 997 error = SYSCTL_OUT(req, &xt, sizeof xt); 998 } else 999 INP_RUNLOCK(inp); 1000 1001 } 1002 if (!error) { 1003 /* 1004 * Give the user an updated idea of our state. 1005 * If the generation differs from what we told 1006 * her before, she knows that something happened 1007 * while we were processing this request, and it 1008 * might be necessary to retry. 1009 */ 1010 INP_INFO_RLOCK(&tcbinfo); 1011 xig.xig_gen = tcbinfo.ipi_gencnt; 1012 xig.xig_sogen = so_gencnt; 1013 xig.xig_count = tcbinfo.ipi_count + pcb_count; 1014 INP_INFO_RUNLOCK(&tcbinfo); 1015 error = SYSCTL_OUT(req, &xig, sizeof xig); 1016 } 1017 free(inp_list, M_TEMP); 1018 return (error); 1019 } 1020 1021 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1022 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1023 1024 static int 1025 tcp_getcred(SYSCTL_HANDLER_ARGS) 1026 { 1027 struct xucred xuc; 1028 struct sockaddr_in addrs[2]; 1029 struct inpcb *inp; 1030 int error; 1031 1032 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1033 if (error) 1034 return (error); 1035 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1036 if (error) 1037 return (error); 1038 INP_INFO_RLOCK(&tcbinfo); 1039 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 1040 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1041 if (inp != NULL) { 1042 INP_RLOCK(inp); 1043 INP_INFO_RUNLOCK(&tcbinfo); 1044 if (inp->inp_socket == NULL) 1045 error = ENOENT; 1046 if (error == 0) 1047 error = cr_canseeinpcb(req->td->td_ucred, inp); 1048 if (error == 0) 1049 cru2x(inp->inp_cred, &xuc); 1050 INP_RUNLOCK(inp); 1051 } else { 1052 INP_INFO_RUNLOCK(&tcbinfo); 1053 error = ENOENT; 1054 } 1055 if (error == 0) 1056 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1057 return (error); 1058 } 1059 1060 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1061 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1062 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1063 1064 #ifdef INET6 1065 static int 1066 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1067 { 1068 struct xucred xuc; 1069 struct sockaddr_in6 addrs[2]; 1070 struct inpcb *inp; 1071 int error, mapped = 0; 1072 1073 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1074 if (error) 1075 return (error); 1076 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1077 if (error) 1078 return (error); 1079 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 || 1080 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) { 1081 return (error); 1082 } 1083 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1084 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1085 mapped = 1; 1086 else 1087 return (EINVAL); 1088 } 1089 1090 INP_INFO_RLOCK(&tcbinfo); 1091 if (mapped == 1) 1092 inp = in_pcblookup_hash(&tcbinfo, 1093 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1094 addrs[1].sin6_port, 1095 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1096 addrs[0].sin6_port, 1097 0, NULL); 1098 else 1099 inp = in6_pcblookup_hash(&tcbinfo, 1100 &addrs[1].sin6_addr, addrs[1].sin6_port, 1101 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1102 if (inp != NULL) { 1103 INP_RLOCK(inp); 1104 INP_INFO_RUNLOCK(&tcbinfo); 1105 if (inp->inp_socket == NULL) 1106 error = ENOENT; 1107 if (error == 0) 1108 error = cr_canseeinpcb(req->td->td_ucred, inp); 1109 if (error == 0) 1110 cru2x(inp->inp_cred, &xuc); 1111 INP_RUNLOCK(inp); 1112 } else { 1113 INP_INFO_RUNLOCK(&tcbinfo); 1114 error = ENOENT; 1115 } 1116 if (error == 0) 1117 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1118 return (error); 1119 } 1120 1121 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1122 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1123 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1124 #endif 1125 1126 1127 void 1128 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1129 { 1130 struct ip *ip = vip; 1131 struct tcphdr *th; 1132 struct in_addr faddr; 1133 struct inpcb *inp; 1134 struct tcpcb *tp; 1135 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1136 struct icmp *icp; 1137 struct in_conninfo inc; 1138 tcp_seq icmp_tcp_seq; 1139 int mtu; 1140 1141 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1142 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1143 return; 1144 1145 if (cmd == PRC_MSGSIZE) 1146 notify = tcp_mtudisc; 1147 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1148 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1149 notify = tcp_drop_syn_sent; 1150 /* 1151 * Redirects don't need to be handled up here. 1152 */ 1153 else if (PRC_IS_REDIRECT(cmd)) 1154 return; 1155 /* 1156 * Source quench is depreciated. 1157 */ 1158 else if (cmd == PRC_QUENCH) 1159 return; 1160 /* 1161 * Hostdead is ugly because it goes linearly through all PCBs. 1162 * XXX: We never get this from ICMP, otherwise it makes an 1163 * excellent DoS attack on machines with many connections. 1164 */ 1165 else if (cmd == PRC_HOSTDEAD) 1166 ip = NULL; 1167 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1168 return; 1169 if (ip != NULL) { 1170 icp = (struct icmp *)((caddr_t)ip 1171 - offsetof(struct icmp, icmp_ip)); 1172 th = (struct tcphdr *)((caddr_t)ip 1173 + (ip->ip_hl << 2)); 1174 INP_INFO_WLOCK(&tcbinfo); 1175 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1176 ip->ip_src, th->th_sport, 0, NULL); 1177 if (inp != NULL) { 1178 INP_WLOCK(inp); 1179 if (!(inp->inp_flags & INP_TIMEWAIT) && 1180 !(inp->inp_flags & INP_DROPPED) && 1181 !(inp->inp_socket == NULL)) { 1182 icmp_tcp_seq = htonl(th->th_seq); 1183 tp = intotcpcb(inp); 1184 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1185 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1186 if (cmd == PRC_MSGSIZE) { 1187 /* 1188 * MTU discovery: 1189 * If we got a needfrag set the MTU 1190 * in the route to the suggested new 1191 * value (if given) and then notify. 1192 */ 1193 bzero(&inc, sizeof(inc)); 1194 inc.inc_faddr = faddr; 1195 inc.inc_fibnum = 1196 inp->inp_inc.inc_fibnum; 1197 1198 mtu = ntohs(icp->icmp_nextmtu); 1199 /* 1200 * If no alternative MTU was 1201 * proposed, try the next smaller 1202 * one. ip->ip_len has already 1203 * been swapped in icmp_input(). 1204 */ 1205 if (!mtu) 1206 mtu = ip_next_mtu(ip->ip_len, 1207 1); 1208 if (mtu < max(296, (tcp_minmss) 1209 + sizeof(struct tcpiphdr))) 1210 mtu = 0; 1211 if (!mtu) 1212 mtu = tcp_mssdflt 1213 + sizeof(struct tcpiphdr); 1214 /* 1215 * Only cache the the MTU if it 1216 * is smaller than the interface 1217 * or route MTU. tcp_mtudisc() 1218 * will do right thing by itself. 1219 */ 1220 if (mtu <= tcp_maxmtu(&inc, NULL)) 1221 tcp_hc_updatemtu(&inc, mtu); 1222 } 1223 1224 inp = (*notify)(inp, inetctlerrmap[cmd]); 1225 } 1226 } 1227 if (inp != NULL) 1228 INP_WUNLOCK(inp); 1229 } else { 1230 bzero(&inc, sizeof(inc)); 1231 inc.inc_fport = th->th_dport; 1232 inc.inc_lport = th->th_sport; 1233 inc.inc_faddr = faddr; 1234 inc.inc_laddr = ip->ip_src; 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 bzero(&inc, sizeof(inc)); 1304 inc.inc_fport = th.th_dport; 1305 inc.inc_lport = th.th_sport; 1306 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1307 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1308 inc.inc_flags |= INC_ISIPV6; 1309 INP_INFO_WLOCK(&tcbinfo); 1310 syncache_unreach(&inc, &th); 1311 INP_INFO_WUNLOCK(&tcbinfo); 1312 } else 1313 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1314 0, cmd, NULL, notify); 1315 } 1316 #endif /* INET6 */ 1317 1318 1319 /* 1320 * Following is where TCP initial sequence number generation occurs. 1321 * 1322 * There are two places where we must use initial sequence numbers: 1323 * 1. In SYN-ACK packets. 1324 * 2. In SYN packets. 1325 * 1326 * All ISNs for SYN-ACK packets are generated by the syncache. See 1327 * tcp_syncache.c for details. 1328 * 1329 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1330 * depends on this property. In addition, these ISNs should be 1331 * unguessable so as to prevent connection hijacking. To satisfy 1332 * the requirements of this situation, the algorithm outlined in 1333 * RFC 1948 is used, with only small modifications. 1334 * 1335 * Implementation details: 1336 * 1337 * Time is based off the system timer, and is corrected so that it 1338 * increases by one megabyte per second. This allows for proper 1339 * recycling on high speed LANs while still leaving over an hour 1340 * before rollover. 1341 * 1342 * As reading the *exact* system time is too expensive to be done 1343 * whenever setting up a TCP connection, we increment the time 1344 * offset in two ways. First, a small random positive increment 1345 * is added to isn_offset for each connection that is set up. 1346 * Second, the function tcp_isn_tick fires once per clock tick 1347 * and increments isn_offset as necessary so that sequence numbers 1348 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1349 * random positive increments serve only to ensure that the same 1350 * exact sequence number is never sent out twice (as could otherwise 1351 * happen when a port is recycled in less than the system tick 1352 * interval.) 1353 * 1354 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1355 * between seeding of isn_secret. This is normally set to zero, 1356 * as reseeding should not be necessary. 1357 * 1358 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1359 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1360 * general, this means holding an exclusive (write) lock. 1361 */ 1362 1363 #define ISN_BYTES_PER_SECOND 1048576 1364 #define ISN_STATIC_INCREMENT 4096 1365 #define ISN_RANDOM_INCREMENT (4096 - 1) 1366 1367 static u_char isn_secret[32]; 1368 static int isn_last_reseed; 1369 static u_int32_t isn_offset, isn_offset_old; 1370 static MD5_CTX isn_ctx; 1371 1372 tcp_seq 1373 tcp_new_isn(struct tcpcb *tp) 1374 { 1375 u_int32_t md5_buffer[4]; 1376 tcp_seq new_isn; 1377 1378 INP_WLOCK_ASSERT(tp->t_inpcb); 1379 1380 ISN_LOCK(); 1381 /* Seed if this is the first use, reseed if requested. */ 1382 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1383 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1384 < (u_int)ticks))) { 1385 read_random(&isn_secret, sizeof(isn_secret)); 1386 isn_last_reseed = ticks; 1387 } 1388 1389 /* Compute the md5 hash and return the ISN. */ 1390 MD5Init(&isn_ctx); 1391 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1392 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1393 #ifdef INET6 1394 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1395 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1396 sizeof(struct in6_addr)); 1397 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1398 sizeof(struct in6_addr)); 1399 } else 1400 #endif 1401 { 1402 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1403 sizeof(struct in_addr)); 1404 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1405 sizeof(struct in_addr)); 1406 } 1407 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1408 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1409 new_isn = (tcp_seq) md5_buffer[0]; 1410 isn_offset += ISN_STATIC_INCREMENT + 1411 (arc4random() & ISN_RANDOM_INCREMENT); 1412 new_isn += isn_offset; 1413 ISN_UNLOCK(); 1414 return (new_isn); 1415 } 1416 1417 /* 1418 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary 1419 * to keep time flowing at a relatively constant rate. If the random 1420 * increments have already pushed us past the projected offset, do nothing. 1421 */ 1422 static void 1423 tcp_isn_tick(void *xtp) 1424 { 1425 u_int32_t projected_offset; 1426 1427 ISN_LOCK(); 1428 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1429 1430 if (SEQ_GT(projected_offset, isn_offset)) 1431 isn_offset = projected_offset; 1432 1433 isn_offset_old = isn_offset; 1434 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1435 ISN_UNLOCK(); 1436 } 1437 1438 /* 1439 * When a specific ICMP unreachable message is received and the 1440 * connection state is SYN-SENT, drop the connection. This behavior 1441 * is controlled by the icmp_may_rst sysctl. 1442 */ 1443 struct inpcb * 1444 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1445 { 1446 struct tcpcb *tp; 1447 1448 INP_INFO_WLOCK_ASSERT(&tcbinfo); 1449 INP_WLOCK_ASSERT(inp); 1450 1451 if ((inp->inp_flags & INP_TIMEWAIT) || 1452 (inp->inp_flags & INP_DROPPED)) 1453 return (inp); 1454 1455 tp = intotcpcb(inp); 1456 if (tp->t_state != TCPS_SYN_SENT) 1457 return (inp); 1458 1459 tp = tcp_drop(tp, errno); 1460 if (tp != NULL) 1461 return (inp); 1462 else 1463 return (NULL); 1464 } 1465 1466 /* 1467 * When `need fragmentation' ICMP is received, update our idea of the MSS 1468 * based on the new value in the route. Also nudge TCP to send something, 1469 * since we know the packet we just sent was dropped. 1470 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1471 */ 1472 struct inpcb * 1473 tcp_mtudisc(struct inpcb *inp, int errno) 1474 { 1475 struct tcpcb *tp; 1476 struct socket *so = inp->inp_socket; 1477 u_int maxmtu; 1478 u_int romtu; 1479 int mss; 1480 #ifdef INET6 1481 int isipv6; 1482 #endif /* INET6 */ 1483 1484 INP_WLOCK_ASSERT(inp); 1485 if ((inp->inp_flags & INP_TIMEWAIT) || 1486 (inp->inp_flags & INP_DROPPED)) 1487 return (inp); 1488 1489 tp = intotcpcb(inp); 1490 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1491 1492 #ifdef INET6 1493 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1494 #endif 1495 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1496 romtu = 1497 #ifdef INET6 1498 isipv6 ? tcp_maxmtu6(&inp->inp_inc, NULL) : 1499 #endif /* INET6 */ 1500 tcp_maxmtu(&inp->inp_inc, NULL); 1501 if (!maxmtu) 1502 maxmtu = romtu; 1503 else 1504 maxmtu = min(maxmtu, romtu); 1505 if (!maxmtu) { 1506 tp->t_maxopd = tp->t_maxseg = 1507 #ifdef INET6 1508 isipv6 ? tcp_v6mssdflt : 1509 #endif /* INET6 */ 1510 tcp_mssdflt; 1511 return (inp); 1512 } 1513 mss = maxmtu - 1514 #ifdef INET6 1515 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1516 #endif /* INET6 */ 1517 sizeof(struct tcpiphdr) 1518 #ifdef INET6 1519 ) 1520 #endif /* INET6 */ 1521 ; 1522 1523 /* 1524 * XXX - The above conditional probably violates the TCP 1525 * spec. The problem is that, since we don't know the 1526 * other end's MSS, we are supposed to use a conservative 1527 * default. But, if we do that, then MTU discovery will 1528 * never actually take place, because the conservative 1529 * default is much less than the MTUs typically seen 1530 * on the Internet today. For the moment, we'll sweep 1531 * this under the carpet. 1532 * 1533 * The conservative default might not actually be a problem 1534 * if the only case this occurs is when sending an initial 1535 * SYN with options and data to a host we've never talked 1536 * to before. Then, they will reply with an MSS value which 1537 * will get recorded and the new parameters should get 1538 * recomputed. For Further Study. 1539 */ 1540 if (tp->t_maxopd <= mss) 1541 return (inp); 1542 tp->t_maxopd = mss; 1543 1544 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1545 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1546 mss -= TCPOLEN_TSTAMP_APPA; 1547 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1548 if (mss > MCLBYTES) 1549 mss &= ~(MCLBYTES-1); 1550 #else 1551 if (mss > MCLBYTES) 1552 mss = mss / MCLBYTES * MCLBYTES; 1553 #endif 1554 if (so->so_snd.sb_hiwat < mss) 1555 mss = so->so_snd.sb_hiwat; 1556 1557 tp->t_maxseg = mss; 1558 1559 tcpstat.tcps_mturesent++; 1560 tp->t_rtttime = 0; 1561 tp->snd_nxt = tp->snd_una; 1562 tcp_free_sackholes(tp); 1563 tp->snd_recover = tp->snd_max; 1564 if (tp->t_flags & TF_SACK_PERMIT) 1565 EXIT_FASTRECOVERY(tp); 1566 tcp_output_send(tp); 1567 return (inp); 1568 } 1569 1570 /* 1571 * Look-up the routing entry to the peer of this inpcb. If no route 1572 * is found and it cannot be allocated, then return NULL. This routine 1573 * is called by TCP routines that access the rmx structure and by tcp_mss 1574 * to get the interface MTU. 1575 */ 1576 u_long 1577 tcp_maxmtu(struct in_conninfo *inc, int *flags) 1578 { 1579 struct route sro; 1580 struct sockaddr_in *dst; 1581 struct ifnet *ifp; 1582 u_long maxmtu = 0; 1583 1584 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1585 1586 bzero(&sro, sizeof(sro)); 1587 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1588 dst = (struct sockaddr_in *)&sro.ro_dst; 1589 dst->sin_family = AF_INET; 1590 dst->sin_len = sizeof(*dst); 1591 dst->sin_addr = inc->inc_faddr; 1592 in_rtalloc_ign(&sro, RTF_CLONING, inc->inc_fibnum); 1593 } 1594 if (sro.ro_rt != NULL) { 1595 ifp = sro.ro_rt->rt_ifp; 1596 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1597 maxmtu = ifp->if_mtu; 1598 else 1599 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1600 1601 /* Report additional interface capabilities. */ 1602 if (flags != NULL) { 1603 if (ifp->if_capenable & IFCAP_TSO4 && 1604 ifp->if_hwassist & CSUM_TSO) 1605 *flags |= CSUM_TSO; 1606 } 1607 RTFREE(sro.ro_rt); 1608 } 1609 return (maxmtu); 1610 } 1611 1612 #ifdef INET6 1613 u_long 1614 tcp_maxmtu6(struct in_conninfo *inc, int *flags) 1615 { 1616 struct route_in6 sro6; 1617 struct ifnet *ifp; 1618 u_long maxmtu = 0; 1619 1620 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1621 1622 bzero(&sro6, sizeof(sro6)); 1623 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1624 sro6.ro_dst.sin6_family = AF_INET6; 1625 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1626 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1627 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1628 } 1629 if (sro6.ro_rt != NULL) { 1630 ifp = sro6.ro_rt->rt_ifp; 1631 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1632 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1633 else 1634 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1635 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1636 1637 /* Report additional interface capabilities. */ 1638 if (flags != NULL) { 1639 if (ifp->if_capenable & IFCAP_TSO6 && 1640 ifp->if_hwassist & CSUM_TSO) 1641 *flags |= CSUM_TSO; 1642 } 1643 RTFREE(sro6.ro_rt); 1644 } 1645 1646 return (maxmtu); 1647 } 1648 #endif /* INET6 */ 1649 1650 #ifdef IPSEC 1651 /* compute ESP/AH header size for TCP, including outer IP header. */ 1652 size_t 1653 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1654 { 1655 struct inpcb *inp; 1656 struct mbuf *m; 1657 size_t hdrsiz; 1658 struct ip *ip; 1659 #ifdef INET6 1660 struct ip6_hdr *ip6; 1661 #endif 1662 struct tcphdr *th; 1663 1664 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1665 return (0); 1666 MGETHDR(m, M_DONTWAIT, MT_DATA); 1667 if (!m) 1668 return (0); 1669 1670 #ifdef INET6 1671 if ((inp->inp_vflag & INP_IPV6) != 0) { 1672 ip6 = mtod(m, struct ip6_hdr *); 1673 th = (struct tcphdr *)(ip6 + 1); 1674 m->m_pkthdr.len = m->m_len = 1675 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1676 tcpip_fillheaders(inp, ip6, th); 1677 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1678 } else 1679 #endif /* INET6 */ 1680 { 1681 ip = mtod(m, struct ip *); 1682 th = (struct tcphdr *)(ip + 1); 1683 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1684 tcpip_fillheaders(inp, ip, th); 1685 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1686 } 1687 1688 m_free(m); 1689 return (hdrsiz); 1690 } 1691 #endif /* IPSEC */ 1692 1693 /* 1694 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1695 * 1696 * This code attempts to calculate the bandwidth-delay product as a 1697 * means of determining the optimal window size to maximize bandwidth, 1698 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1699 * routers. This code also does a fairly good job keeping RTTs in check 1700 * across slow links like modems. We implement an algorithm which is very 1701 * similar (but not meant to be) TCP/Vegas. The code operates on the 1702 * transmitter side of a TCP connection and so only effects the transmit 1703 * side of the connection. 1704 * 1705 * BACKGROUND: TCP makes no provision for the management of buffer space 1706 * at the end points or at the intermediate routers and switches. A TCP 1707 * stream, whether using NewReno or not, will eventually buffer as 1708 * many packets as it is able and the only reason this typically works is 1709 * due to the fairly small default buffers made available for a connection 1710 * (typicaly 16K or 32K). As machines use larger windows and/or window 1711 * scaling it is now fairly easy for even a single TCP connection to blow-out 1712 * all available buffer space not only on the local interface, but on 1713 * intermediate routers and switches as well. NewReno makes a misguided 1714 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1715 * then backing off, then steadily increasing the window again until another 1716 * failure occurs, ad-infinitum. This results in terrible oscillation that 1717 * is only made worse as network loads increase and the idea of intentionally 1718 * blowing out network buffers is, frankly, a terrible way to manage network 1719 * resources. 1720 * 1721 * It is far better to limit the transmit window prior to the failure 1722 * condition being achieved. There are two general ways to do this: First 1723 * you can 'scan' through different transmit window sizes and locate the 1724 * point where the RTT stops increasing, indicating that you have filled the 1725 * pipe, then scan backwards until you note that RTT stops decreasing, then 1726 * repeat ad-infinitum. This method works in principle but has severe 1727 * implementation issues due to RTT variances, timer granularity, and 1728 * instability in the algorithm which can lead to many false positives and 1729 * create oscillations as well as interact badly with other TCP streams 1730 * implementing the same algorithm. 1731 * 1732 * The second method is to limit the window to the bandwidth delay product 1733 * of the link. This is the method we implement. RTT variances and our 1734 * own manipulation of the congestion window, bwnd, can potentially 1735 * destabilize the algorithm. For this reason we have to stabilize the 1736 * elements used to calculate the window. We do this by using the minimum 1737 * observed RTT, the long term average of the observed bandwidth, and 1738 * by adding two segments worth of slop. It isn't perfect but it is able 1739 * to react to changing conditions and gives us a very stable basis on 1740 * which to extend the algorithm. 1741 */ 1742 void 1743 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1744 { 1745 u_long bw; 1746 u_long bwnd; 1747 int save_ticks; 1748 1749 INP_WLOCK_ASSERT(tp->t_inpcb); 1750 1751 /* 1752 * If inflight_enable is disabled in the middle of a tcp connection, 1753 * make sure snd_bwnd is effectively disabled. 1754 */ 1755 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) { 1756 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1757 tp->snd_bandwidth = 0; 1758 return; 1759 } 1760 1761 /* 1762 * Figure out the bandwidth. Due to the tick granularity this 1763 * is a very rough number and it MUST be averaged over a fairly 1764 * long period of time. XXX we need to take into account a link 1765 * that is not using all available bandwidth, but for now our 1766 * slop will ramp us up if this case occurs and the bandwidth later 1767 * increases. 1768 * 1769 * Note: if ticks rollover 'bw' may wind up negative. We must 1770 * effectively reset t_bw_rtttime for this case. 1771 */ 1772 save_ticks = ticks; 1773 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1774 return; 1775 1776 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1777 (save_ticks - tp->t_bw_rtttime); 1778 tp->t_bw_rtttime = save_ticks; 1779 tp->t_bw_rtseq = ack_seq; 1780 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1781 return; 1782 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1783 1784 tp->snd_bandwidth = bw; 1785 1786 /* 1787 * Calculate the semi-static bandwidth delay product, plus two maximal 1788 * segments. The additional slop puts us squarely in the sweet 1789 * spot and also handles the bandwidth run-up case and stabilization. 1790 * Without the slop we could be locking ourselves into a lower 1791 * bandwidth. 1792 * 1793 * Situations Handled: 1794 * (1) Prevents over-queueing of packets on LANs, especially on 1795 * high speed LANs, allowing larger TCP buffers to be 1796 * specified, and also does a good job preventing 1797 * over-queueing of packets over choke points like modems 1798 * (at least for the transmit side). 1799 * 1800 * (2) Is able to handle changing network loads (bandwidth 1801 * drops so bwnd drops, bandwidth increases so bwnd 1802 * increases). 1803 * 1804 * (3) Theoretically should stabilize in the face of multiple 1805 * connections implementing the same algorithm (this may need 1806 * a little work). 1807 * 1808 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1809 * be adjusted with a sysctl but typically only needs to be 1810 * on very slow connections. A value no smaller then 5 1811 * should be used, but only reduce this default if you have 1812 * no other choice. 1813 */ 1814 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1815 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 1816 #undef USERTT 1817 1818 if (tcp_inflight_debug > 0) { 1819 static int ltime; 1820 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1821 ltime = ticks; 1822 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1823 tp, 1824 bw, 1825 tp->t_rttbest, 1826 tp->t_srtt, 1827 bwnd 1828 ); 1829 } 1830 } 1831 if ((long)bwnd < tcp_inflight_min) 1832 bwnd = tcp_inflight_min; 1833 if (bwnd > tcp_inflight_max) 1834 bwnd = tcp_inflight_max; 1835 if ((long)bwnd < tp->t_maxseg * 2) 1836 bwnd = tp->t_maxseg * 2; 1837 tp->snd_bwnd = bwnd; 1838 } 1839 1840 #ifdef TCP_SIGNATURE 1841 /* 1842 * Callback function invoked by m_apply() to digest TCP segment data 1843 * contained within an mbuf chain. 1844 */ 1845 static int 1846 tcp_signature_apply(void *fstate, void *data, u_int len) 1847 { 1848 1849 MD5Update(fstate, (u_char *)data, len); 1850 return (0); 1851 } 1852 1853 /* 1854 * Compute TCP-MD5 hash of a TCP segment. (RFC2385) 1855 * 1856 * Parameters: 1857 * m pointer to head of mbuf chain 1858 * _unused 1859 * len length of TCP segment data, excluding options 1860 * optlen length of TCP segment options 1861 * buf pointer to storage for computed MD5 digest 1862 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1863 * 1864 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1865 * When called from tcp_input(), we can be sure that th_sum has been 1866 * zeroed out and verified already. 1867 * 1868 * Return 0 if successful, otherwise return -1. 1869 * 1870 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1871 * search with the destination IP address, and a 'magic SPI' to be 1872 * determined by the application. This is hardcoded elsewhere to 1179 1873 * right now. Another branch of this code exists which uses the SPD to 1874 * specify per-application flows but it is unstable. 1875 */ 1876 int 1877 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen, 1878 u_char *buf, u_int direction) 1879 { 1880 union sockaddr_union dst; 1881 struct ippseudo ippseudo; 1882 MD5_CTX ctx; 1883 int doff; 1884 struct ip *ip; 1885 struct ipovly *ipovly; 1886 struct secasvar *sav; 1887 struct tcphdr *th; 1888 #ifdef INET6 1889 struct ip6_hdr *ip6; 1890 struct in6_addr in6; 1891 char ip6buf[INET6_ADDRSTRLEN]; 1892 uint32_t plen; 1893 uint16_t nhdr; 1894 #endif 1895 u_short savecsum; 1896 1897 KASSERT(m != NULL, ("NULL mbuf chain")); 1898 KASSERT(buf != NULL, ("NULL signature pointer")); 1899 1900 /* Extract the destination from the IP header in the mbuf. */ 1901 bzero(&dst, sizeof(union sockaddr_union)); 1902 ip = mtod(m, struct ip *); 1903 #ifdef INET6 1904 ip6 = NULL; /* Make the compiler happy. */ 1905 #endif 1906 switch (ip->ip_v) { 1907 case IPVERSION: 1908 dst.sa.sa_len = sizeof(struct sockaddr_in); 1909 dst.sa.sa_family = AF_INET; 1910 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1911 ip->ip_src : ip->ip_dst; 1912 break; 1913 #ifdef INET6 1914 case (IPV6_VERSION >> 4): 1915 ip6 = mtod(m, struct ip6_hdr *); 1916 dst.sa.sa_len = sizeof(struct sockaddr_in6); 1917 dst.sa.sa_family = AF_INET6; 1918 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ? 1919 ip6->ip6_src : ip6->ip6_dst; 1920 break; 1921 #endif 1922 default: 1923 return (EINVAL); 1924 /* NOTREACHED */ 1925 break; 1926 } 1927 1928 /* Look up an SADB entry which matches the address of the peer. */ 1929 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 1930 if (sav == NULL) { 1931 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__, 1932 (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) : 1933 #ifdef INET6 1934 (ip->ip_v == (IPV6_VERSION >> 4)) ? 1935 ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) : 1936 #endif 1937 "(unsupported)")); 1938 return (EINVAL); 1939 } 1940 1941 MD5Init(&ctx); 1942 /* 1943 * Step 1: Update MD5 hash with IP(v6) pseudo-header. 1944 * 1945 * XXX The ippseudo header MUST be digested in network byte order, 1946 * or else we'll fail the regression test. Assume all fields we've 1947 * been doing arithmetic on have been in host byte order. 1948 * XXX One cannot depend on ipovly->ih_len here. When called from 1949 * tcp_output(), the underlying ip_len member has not yet been set. 1950 */ 1951 switch (ip->ip_v) { 1952 case IPVERSION: 1953 ipovly = (struct ipovly *)ip; 1954 ippseudo.ippseudo_src = ipovly->ih_src; 1955 ippseudo.ippseudo_dst = ipovly->ih_dst; 1956 ippseudo.ippseudo_pad = 0; 1957 ippseudo.ippseudo_p = IPPROTO_TCP; 1958 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + 1959 optlen); 1960 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 1961 1962 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip)); 1963 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen; 1964 break; 1965 #ifdef INET6 1966 /* 1967 * RFC 2385, 2.0 Proposal 1968 * For IPv6, the pseudo-header is as described in RFC 2460, namely the 1969 * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero- 1970 * extended next header value (to form 32 bits), and 32-bit segment 1971 * length. 1972 * Note: Upper-Layer Packet Length comes before Next Header. 1973 */ 1974 case (IPV6_VERSION >> 4): 1975 in6 = ip6->ip6_src; 1976 in6_clearscope(&in6); 1977 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 1978 in6 = ip6->ip6_dst; 1979 in6_clearscope(&in6); 1980 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 1981 plen = htonl(len + sizeof(struct tcphdr) + optlen); 1982 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t)); 1983 nhdr = 0; 1984 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 1985 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 1986 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 1987 nhdr = IPPROTO_TCP; 1988 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 1989 1990 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr)); 1991 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen; 1992 break; 1993 #endif 1994 default: 1995 return (EINVAL); 1996 /* NOTREACHED */ 1997 break; 1998 } 1999 2000 2001 /* 2002 * Step 2: Update MD5 hash with TCP header, excluding options. 2003 * The TCP checksum must be set to zero. 2004 */ 2005 savecsum = th->th_sum; 2006 th->th_sum = 0; 2007 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2008 th->th_sum = savecsum; 2009 2010 /* 2011 * Step 3: Update MD5 hash with TCP segment data. 2012 * Use m_apply() to avoid an early m_pullup(). 2013 */ 2014 if (len > 0) 2015 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2016 2017 /* 2018 * Step 4: Update MD5 hash with shared secret. 2019 */ 2020 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth)); 2021 MD5Final(buf, &ctx); 2022 2023 key_sa_recordxfer(sav, m); 2024 KEY_FREESAV(&sav); 2025 return (0); 2026 } 2027 #endif /* TCP_SIGNATURE */ 2028 2029 static int 2030 sysctl_drop(SYSCTL_HANDLER_ARGS) 2031 { 2032 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2033 struct sockaddr_storage addrs[2]; 2034 struct inpcb *inp; 2035 struct tcpcb *tp; 2036 struct tcptw *tw; 2037 struct sockaddr_in *fin, *lin; 2038 #ifdef INET6 2039 struct sockaddr_in6 *fin6, *lin6; 2040 struct in6_addr f6, l6; 2041 #endif 2042 int error; 2043 2044 inp = NULL; 2045 fin = lin = NULL; 2046 #ifdef INET6 2047 fin6 = lin6 = NULL; 2048 #endif 2049 error = 0; 2050 2051 if (req->oldptr != NULL || req->oldlen != 0) 2052 return (EINVAL); 2053 if (req->newptr == NULL) 2054 return (EPERM); 2055 if (req->newlen < sizeof(addrs)) 2056 return (ENOMEM); 2057 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2058 if (error) 2059 return (error); 2060 2061 switch (addrs[0].ss_family) { 2062 #ifdef INET6 2063 case AF_INET6: 2064 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2065 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2066 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2067 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2068 return (EINVAL); 2069 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2070 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2071 return (EINVAL); 2072 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2073 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2074 fin = (struct sockaddr_in *)&addrs[0]; 2075 lin = (struct sockaddr_in *)&addrs[1]; 2076 break; 2077 } 2078 error = sa6_embedscope(fin6, ip6_use_defzone); 2079 if (error) 2080 return (error); 2081 error = sa6_embedscope(lin6, ip6_use_defzone); 2082 if (error) 2083 return (error); 2084 break; 2085 #endif 2086 case AF_INET: 2087 fin = (struct sockaddr_in *)&addrs[0]; 2088 lin = (struct sockaddr_in *)&addrs[1]; 2089 if (fin->sin_len != sizeof(struct sockaddr_in) || 2090 lin->sin_len != sizeof(struct sockaddr_in)) 2091 return (EINVAL); 2092 break; 2093 default: 2094 return (EINVAL); 2095 } 2096 INP_INFO_WLOCK(&tcbinfo); 2097 switch (addrs[0].ss_family) { 2098 #ifdef INET6 2099 case AF_INET6: 2100 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port, 2101 &l6, lin6->sin6_port, 0, NULL); 2102 break; 2103 #endif 2104 case AF_INET: 2105 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port, 2106 lin->sin_addr, lin->sin_port, 0, NULL); 2107 break; 2108 } 2109 if (inp != NULL) { 2110 INP_WLOCK(inp); 2111 if (inp->inp_flags & INP_TIMEWAIT) { 2112 /* 2113 * XXXRW: There currently exists a state where an 2114 * inpcb is present, but its timewait state has been 2115 * discarded. For now, don't allow dropping of this 2116 * type of inpcb. 2117 */ 2118 tw = intotw(inp); 2119 if (tw != NULL) 2120 tcp_twclose(tw, 0); 2121 else 2122 INP_WUNLOCK(inp); 2123 } else if (!(inp->inp_flags & INP_DROPPED) && 2124 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2125 tp = intotcpcb(inp); 2126 tp = tcp_drop(tp, ECONNABORTED); 2127 if (tp != NULL) 2128 INP_WUNLOCK(inp); 2129 } else 2130 INP_WUNLOCK(inp); 2131 } else 2132 error = ESRCH; 2133 INP_INFO_WUNLOCK(&tcbinfo); 2134 return (error); 2135 } 2136 2137 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2138 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2139 0, sysctl_drop, "", "Drop TCP connection"); 2140 2141 /* 2142 * Generate a standardized TCP log line for use throughout the 2143 * tcp subsystem. Memory allocation is done with M_NOWAIT to 2144 * allow use in the interrupt context. 2145 * 2146 * NB: The caller MUST free(s, M_TCPLOG) the returned string. 2147 * NB: The function may return NULL if memory allocation failed. 2148 * 2149 * Due to header inclusion and ordering limitations the struct ip 2150 * and ip6_hdr pointers have to be passed as void pointers. 2151 */ 2152 char * 2153 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, 2154 const void *ip6hdr) 2155 { 2156 char *s, *sp; 2157 size_t size; 2158 struct ip *ip; 2159 #ifdef INET6 2160 const struct ip6_hdr *ip6; 2161 2162 ip6 = (const struct ip6_hdr *)ip6hdr; 2163 #endif /* INET6 */ 2164 ip = (struct ip *)ip4hdr; 2165 2166 /* 2167 * The log line looks like this: 2168 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>" 2169 */ 2170 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") + 2171 sizeof(PRINT_TH_FLAGS) + 1 + 2172 #ifdef INET6 2173 2 * INET6_ADDRSTRLEN; 2174 #else 2175 2 * INET_ADDRSTRLEN; 2176 #endif /* INET6 */ 2177 2178 /* Is logging enabled? */ 2179 if (tcp_log_debug == 0 && tcp_log_in_vain == 0) 2180 return (NULL); 2181 2182 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT); 2183 if (s == NULL) 2184 return (NULL); 2185 2186 strcat(s, "TCP: ["); 2187 sp = s + strlen(s); 2188 2189 if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) { 2190 inet_ntoa_r(inc->inc_faddr, sp); 2191 sp = s + strlen(s); 2192 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2193 sp = s + strlen(s); 2194 inet_ntoa_r(inc->inc_laddr, sp); 2195 sp = s + strlen(s); 2196 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2197 #ifdef INET6 2198 } else if (inc) { 2199 ip6_sprintf(sp, &inc->inc6_faddr); 2200 sp = s + strlen(s); 2201 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2202 sp = s + strlen(s); 2203 ip6_sprintf(sp, &inc->inc6_laddr); 2204 sp = s + strlen(s); 2205 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2206 } else if (ip6 && th) { 2207 ip6_sprintf(sp, &ip6->ip6_src); 2208 sp = s + strlen(s); 2209 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2210 sp = s + strlen(s); 2211 ip6_sprintf(sp, &ip6->ip6_dst); 2212 sp = s + strlen(s); 2213 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2214 #endif /* INET6 */ 2215 } else if (ip && th) { 2216 inet_ntoa_r(ip->ip_src, sp); 2217 sp = s + strlen(s); 2218 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2219 sp = s + strlen(s); 2220 inet_ntoa_r(ip->ip_dst, sp); 2221 sp = s + strlen(s); 2222 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2223 } else { 2224 free(s, M_TCPLOG); 2225 return (NULL); 2226 } 2227 sp = s + strlen(s); 2228 if (th) 2229 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS); 2230 if (*(s + size - 1) != '\0') 2231 panic("%s: string too long", __func__); 2232 return (s); 2233 }
Cache object: abfe32edf121b1ab5e52954b5acefc1a
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