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 #include <sys/vimage.h> 59 60 #include <vm/uma.h> 61 62 #include <net/route.h> 63 #include <net/if.h> 64 65 #include <netinet/in.h> 66 #include <netinet/in_systm.h> 67 #include <netinet/ip.h> 68 #ifdef INET6 69 #include <netinet/ip6.h> 70 #endif 71 #include <netinet/in_pcb.h> 72 #ifdef INET6 73 #include <netinet6/in6_pcb.h> 74 #endif 75 #include <netinet/in_var.h> 76 #include <netinet/ip_var.h> 77 #ifdef INET6 78 #include <netinet6/ip6_var.h> 79 #include <netinet6/scope6_var.h> 80 #include <netinet6/nd6.h> 81 #endif 82 #include <netinet/ip_icmp.h> 83 #include <netinet/tcp.h> 84 #include <netinet/tcp_fsm.h> 85 #include <netinet/tcp_seq.h> 86 #include <netinet/tcp_timer.h> 87 #include <netinet/tcp_var.h> 88 #include <netinet/tcp_syncache.h> 89 #include <netinet/tcp_offload.h> 90 #ifdef INET6 91 #include <netinet6/tcp6_var.h> 92 #endif 93 #include <netinet/tcpip.h> 94 #ifdef TCPDEBUG 95 #include <netinet/tcp_debug.h> 96 #endif 97 #include <netinet6/ip6protosw.h> 98 99 #ifdef IPSEC 100 #include <netipsec/ipsec.h> 101 #include <netipsec/xform.h> 102 #ifdef INET6 103 #include <netipsec/ipsec6.h> 104 #endif 105 #include <netipsec/key.h> 106 #include <sys/syslog.h> 107 #endif /*IPSEC*/ 108 109 #include <machine/in_cksum.h> 110 #include <sys/md5.h> 111 112 #include <security/mac/mac_framework.h> 113 114 int tcp_mssdflt = TCP_MSS; 115 #ifdef INET6 116 int tcp_v6mssdflt = TCP6_MSS; 117 #endif 118 119 static int 120 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS) 121 { 122 INIT_VNET_INET(TD_TO_VNET(curthread)); 123 int error, new; 124 125 new = V_tcp_mssdflt; 126 error = sysctl_handle_int(oidp, &new, 0, req); 127 if (error == 0 && req->newptr) { 128 if (new < TCP_MINMSS) 129 error = EINVAL; 130 else 131 V_tcp_mssdflt = new; 132 } 133 return (error); 134 } 135 136 SYSCTL_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLTYPE_INT|CTLFLAG_RW, 137 &tcp_mssdflt, 0, &sysctl_net_inet_tcp_mss_check, "I", 138 "Default TCP Maximum Segment Size"); 139 140 #ifdef INET6 141 static int 142 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS) 143 { 144 INIT_VNET_INET6(TD_TO_VNET(curthread)); 145 int error, new; 146 147 new = V_tcp_v6mssdflt; 148 error = sysctl_handle_int(oidp, &new, 0, req); 149 if (error == 0 && req->newptr) { 150 if (new < TCP_MINMSS) 151 error = EINVAL; 152 else 153 V_tcp_v6mssdflt = new; 154 } 155 return (error); 156 } 157 158 SYSCTL_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, CTLTYPE_INT|CTLFLAG_RW, 159 &tcp_v6mssdflt, 0, &sysctl_net_inet_tcp_mss_v6_check, "I", 160 "Default TCP Maximum Segment Size for IPv6"); 161 #endif 162 163 /* 164 * Minimum MSS we accept and use. This prevents DoS attacks where 165 * we are forced to a ridiculous low MSS like 20 and send hundreds 166 * of packets instead of one. The effect scales with the available 167 * bandwidth and quickly saturates the CPU and network interface 168 * with packet generation and sending. Set to zero to disable MINMSS 169 * checking. This setting prevents us from sending too small packets. 170 */ 171 int tcp_minmss = TCP_MINMSS; 172 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, minmss, 173 CTLFLAG_RW, tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 174 175 int tcp_do_rfc1323 = 1; 176 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, 177 CTLFLAG_RW, tcp_do_rfc1323, 0, 178 "Enable rfc1323 (high performance TCP) extensions"); 179 180 static int tcp_log_debug = 0; 181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW, 182 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments"); 183 184 static int tcp_tcbhashsize = 0; 185 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 186 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 187 188 static int do_tcpdrain = 1; 189 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 190 "Enable tcp_drain routine for extra help when low on mbufs"); 191 192 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, pcbcount, 193 CTLFLAG_RD, tcbinfo.ipi_count, 0, "Number of active PCBs"); 194 195 static int icmp_may_rst = 1; 196 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, icmp_may_rst, 197 CTLFLAG_RW, icmp_may_rst, 0, 198 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 199 200 static int tcp_isn_reseed_interval = 0; 201 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, isn_reseed_interval, 202 CTLFLAG_RW, tcp_isn_reseed_interval, 0, 203 "Seconds between reseeding of ISN secret"); 204 205 /* 206 * TCP bandwidth limiting sysctls. Note that the default lower bound of 207 * 1024 exists only for debugging. A good production default would be 208 * something like 6100. 209 */ 210 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 211 "TCP inflight data limiting"); 212 213 static int tcp_inflight_enable = 1; 214 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, enable, 215 CTLFLAG_RW, tcp_inflight_enable, 0, 216 "Enable automatic TCP inflight data limiting"); 217 218 static int tcp_inflight_debug = 0; 219 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 220 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 221 222 static int tcp_inflight_rttthresh; 223 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW, 224 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I", 225 "RTT threshold below which inflight will deactivate itself"); 226 227 static int tcp_inflight_min = 6144; 228 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, min, 229 CTLFLAG_RW, tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 230 231 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 232 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, max, 233 CTLFLAG_RW, tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 234 235 static int tcp_inflight_stab = 20; 236 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, stab, 237 CTLFLAG_RW, tcp_inflight_stab, 0, 238 "Inflight Algorithm Stabilization 20 = 2 packets"); 239 240 uma_zone_t sack_hole_zone; 241 242 static struct inpcb *tcp_notify(struct inpcb *, int); 243 static void tcp_isn_tick(void *); 244 245 /* 246 * Target size of TCP PCB hash tables. Must be a power of two. 247 * 248 * Note that this can be overridden by the kernel environment 249 * variable net.inet.tcp.tcbhashsize 250 */ 251 #ifndef TCBHASHSIZE 252 #define TCBHASHSIZE 512 253 #endif 254 255 /* 256 * XXX 257 * Callouts should be moved into struct tcp directly. They are currently 258 * separate because the tcpcb structure is exported to userland for sysctl 259 * parsing purposes, which do not know about callouts. 260 */ 261 struct tcpcb_mem { 262 struct tcpcb tcb; 263 struct tcp_timer tt; 264 }; 265 266 static uma_zone_t tcpcb_zone; 267 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); 268 struct callout isn_callout; 269 static struct mtx isn_mtx; 270 271 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) 272 #define ISN_LOCK() mtx_lock(&isn_mtx) 273 #define ISN_UNLOCK() mtx_unlock(&isn_mtx) 274 275 /* 276 * TCP initialization. 277 */ 278 static void 279 tcp_zone_change(void *tag) 280 { 281 282 uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets); 283 uma_zone_set_max(tcpcb_zone, maxsockets); 284 tcp_tw_zone_change(); 285 } 286 287 static int 288 tcp_inpcb_init(void *mem, int size, int flags) 289 { 290 struct inpcb *inp = mem; 291 292 INP_LOCK_INIT(inp, "inp", "tcpinp"); 293 return (0); 294 } 295 296 void 297 tcp_init(void) 298 { 299 INIT_VNET_INET(curvnet); 300 301 int hashsize = TCBHASHSIZE; 302 tcp_delacktime = TCPTV_DELACK; 303 tcp_keepinit = TCPTV_KEEP_INIT; 304 tcp_keepidle = TCPTV_KEEP_IDLE; 305 tcp_keepintvl = TCPTV_KEEPINTVL; 306 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 307 tcp_msl = TCPTV_MSL; 308 tcp_rexmit_min = TCPTV_MIN; 309 if (tcp_rexmit_min < 1) 310 tcp_rexmit_min = 1; 311 tcp_rexmit_slop = TCPTV_CPU_VAR; 312 V_tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 313 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT; 314 315 INP_INFO_LOCK_INIT(&V_tcbinfo, "tcp"); 316 LIST_INIT(&V_tcb); 317 V_tcbinfo.ipi_listhead = &V_tcb; 318 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 319 if (!powerof2(hashsize)) { 320 printf("WARNING: TCB hash size not a power of 2\n"); 321 hashsize = 512; /* safe default */ 322 } 323 tcp_tcbhashsize = hashsize; 324 V_tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB, 325 &V_tcbinfo.ipi_hashmask); 326 V_tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB, 327 &V_tcbinfo.ipi_porthashmask); 328 V_tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 329 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 330 uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets); 331 #ifdef INET6 332 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 333 #else /* INET6 */ 334 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 335 #endif /* INET6 */ 336 if (max_protohdr < TCP_MINPROTOHDR) 337 max_protohdr = TCP_MINPROTOHDR; 338 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 339 panic("tcp_init"); 340 #undef TCP_MINPROTOHDR 341 /* 342 * These have to be type stable for the benefit of the timers. 343 */ 344 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 345 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 346 uma_zone_set_max(tcpcb_zone, maxsockets); 347 tcp_tw_init(); 348 syncache_init(); 349 tcp_hc_init(); 350 tcp_reass_init(); 351 ISN_LOCK_INIT(); 352 callout_init(&isn_callout, CALLOUT_MPSAFE); 353 tcp_isn_tick(NULL); 354 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 355 SHUTDOWN_PRI_DEFAULT); 356 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 357 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 358 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, 359 EVENTHANDLER_PRI_ANY); 360 } 361 362 void 363 tcp_fini(void *xtp) 364 { 365 366 callout_stop(&isn_callout); 367 } 368 369 /* 370 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 371 * tcp_template used to store this data in mbufs, but we now recopy it out 372 * of the tcpcb each time to conserve mbufs. 373 */ 374 void 375 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 376 { 377 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 378 379 INP_WLOCK_ASSERT(inp); 380 381 #ifdef INET6 382 if ((inp->inp_vflag & INP_IPV6) != 0) { 383 struct ip6_hdr *ip6; 384 385 ip6 = (struct ip6_hdr *)ip_ptr; 386 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 387 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 388 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 389 (IPV6_VERSION & IPV6_VERSION_MASK); 390 ip6->ip6_nxt = IPPROTO_TCP; 391 ip6->ip6_plen = htons(sizeof(struct tcphdr)); 392 ip6->ip6_src = inp->in6p_laddr; 393 ip6->ip6_dst = inp->in6p_faddr; 394 } else 395 #endif 396 { 397 struct ip *ip; 398 399 ip = (struct ip *)ip_ptr; 400 ip->ip_v = IPVERSION; 401 ip->ip_hl = 5; 402 ip->ip_tos = inp->inp_ip_tos; 403 ip->ip_len = 0; 404 ip->ip_id = 0; 405 ip->ip_off = 0; 406 ip->ip_ttl = inp->inp_ip_ttl; 407 ip->ip_sum = 0; 408 ip->ip_p = IPPROTO_TCP; 409 ip->ip_src = inp->inp_laddr; 410 ip->ip_dst = inp->inp_faddr; 411 } 412 th->th_sport = inp->inp_lport; 413 th->th_dport = inp->inp_fport; 414 th->th_seq = 0; 415 th->th_ack = 0; 416 th->th_x2 = 0; 417 th->th_off = 5; 418 th->th_flags = 0; 419 th->th_win = 0; 420 th->th_urp = 0; 421 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 422 } 423 424 /* 425 * Create template to be used to send tcp packets on a connection. 426 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 427 * use for this function is in keepalives, which use tcp_respond. 428 */ 429 struct tcptemp * 430 tcpip_maketemplate(struct inpcb *inp) 431 { 432 struct tcptemp *t; 433 434 t = malloc(sizeof(*t), M_TEMP, M_NOWAIT); 435 if (t == NULL) 436 return (NULL); 437 tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t); 438 return (t); 439 } 440 441 /* 442 * Send a single message to the TCP at address specified by 443 * the given TCP/IP header. If m == NULL, then we make a copy 444 * of the tcpiphdr at ti and send directly to the addressed host. 445 * This is used to force keep alive messages out using the TCP 446 * template for a connection. If flags are given then we send 447 * a message back to the TCP which originated the * segment ti, 448 * and discard the mbuf containing it and any other attached mbufs. 449 * 450 * In any case the ack and sequence number of the transmitted 451 * segment are as specified by the parameters. 452 * 453 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 454 */ 455 void 456 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 457 tcp_seq ack, tcp_seq seq, int flags) 458 { 459 INIT_VNET_INET(curvnet); 460 int tlen; 461 int win = 0; 462 struct ip *ip; 463 struct tcphdr *nth; 464 #ifdef INET6 465 struct ip6_hdr *ip6; 466 int isipv6; 467 #endif /* INET6 */ 468 int ipflags = 0; 469 struct inpcb *inp; 470 471 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 472 473 #ifdef INET6 474 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 475 ip6 = ipgen; 476 #endif /* INET6 */ 477 ip = ipgen; 478 479 if (tp != NULL) { 480 inp = tp->t_inpcb; 481 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 482 INP_WLOCK_ASSERT(inp); 483 } else 484 inp = NULL; 485 486 if (tp != NULL) { 487 if (!(flags & TH_RST)) { 488 win = sbspace(&inp->inp_socket->so_rcv); 489 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 490 win = (long)TCP_MAXWIN << tp->rcv_scale; 491 } 492 } 493 if (m == NULL) { 494 m = m_gethdr(M_DONTWAIT, MT_DATA); 495 if (m == NULL) 496 return; 497 tlen = 0; 498 m->m_data += max_linkhdr; 499 #ifdef INET6 500 if (isipv6) { 501 bcopy((caddr_t)ip6, mtod(m, caddr_t), 502 sizeof(struct ip6_hdr)); 503 ip6 = mtod(m, struct ip6_hdr *); 504 nth = (struct tcphdr *)(ip6 + 1); 505 } else 506 #endif /* INET6 */ 507 { 508 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 509 ip = mtod(m, struct ip *); 510 nth = (struct tcphdr *)(ip + 1); 511 } 512 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 513 flags = TH_ACK; 514 } else { 515 /* 516 * reuse the mbuf. 517 * XXX MRT We inherrit the FIB, which is lucky. 518 */ 519 m_freem(m->m_next); 520 m->m_next = NULL; 521 m->m_data = (caddr_t)ipgen; 522 /* m_len is set later */ 523 tlen = 0; 524 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 525 #ifdef INET6 526 if (isipv6) { 527 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 528 nth = (struct tcphdr *)(ip6 + 1); 529 } else 530 #endif /* INET6 */ 531 { 532 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 533 nth = (struct tcphdr *)(ip + 1); 534 } 535 if (th != nth) { 536 /* 537 * this is usually a case when an extension header 538 * exists between the IPv6 header and the 539 * TCP header. 540 */ 541 nth->th_sport = th->th_sport; 542 nth->th_dport = th->th_dport; 543 } 544 xchg(nth->th_dport, nth->th_sport, n_short); 545 #undef xchg 546 } 547 #ifdef INET6 548 if (isipv6) { 549 ip6->ip6_flow = 0; 550 ip6->ip6_vfc = IPV6_VERSION; 551 ip6->ip6_nxt = IPPROTO_TCP; 552 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 553 tlen)); 554 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 555 } else 556 #endif 557 { 558 tlen += sizeof (struct tcpiphdr); 559 ip->ip_len = tlen; 560 ip->ip_ttl = V_ip_defttl; 561 if (V_path_mtu_discovery) 562 ip->ip_off |= IP_DF; 563 } 564 m->m_len = tlen; 565 m->m_pkthdr.len = tlen; 566 m->m_pkthdr.rcvif = NULL; 567 #ifdef MAC 568 if (inp != NULL) { 569 /* 570 * Packet is associated with a socket, so allow the 571 * label of the response to reflect the socket label. 572 */ 573 INP_WLOCK_ASSERT(inp); 574 mac_inpcb_create_mbuf(inp, m); 575 } else { 576 /* 577 * Packet is not associated with a socket, so possibly 578 * update the label in place. 579 */ 580 mac_netinet_tcp_reply(m); 581 } 582 #endif 583 nth->th_seq = htonl(seq); 584 nth->th_ack = htonl(ack); 585 nth->th_x2 = 0; 586 nth->th_off = sizeof (struct tcphdr) >> 2; 587 nth->th_flags = flags; 588 if (tp != NULL) 589 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 590 else 591 nth->th_win = htons((u_short)win); 592 nth->th_urp = 0; 593 #ifdef INET6 594 if (isipv6) { 595 nth->th_sum = 0; 596 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 597 sizeof(struct ip6_hdr), 598 tlen - sizeof(struct ip6_hdr)); 599 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 600 NULL, NULL); 601 } else 602 #endif /* INET6 */ 603 { 604 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 605 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 606 m->m_pkthdr.csum_flags = CSUM_TCP; 607 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 608 } 609 #ifdef TCPDEBUG 610 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 611 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 612 #endif 613 #ifdef INET6 614 if (isipv6) 615 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 616 else 617 #endif /* INET6 */ 618 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 619 } 620 621 /* 622 * Create a new TCP control block, making an 623 * empty reassembly queue and hooking it to the argument 624 * protocol control block. The `inp' parameter must have 625 * come from the zone allocator set up in tcp_init(). 626 */ 627 struct tcpcb * 628 tcp_newtcpcb(struct inpcb *inp) 629 { 630 INIT_VNET_INET(inp->inp_vnet); 631 struct tcpcb_mem *tm; 632 struct tcpcb *tp; 633 #ifdef INET6 634 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 635 #endif /* INET6 */ 636 637 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 638 if (tm == NULL) 639 return (NULL); 640 tp = &tm->tcb; 641 tp->t_timers = &tm->tt; 642 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 643 tp->t_maxseg = tp->t_maxopd = 644 #ifdef INET6 645 isipv6 ? V_tcp_v6mssdflt : 646 #endif /* INET6 */ 647 V_tcp_mssdflt; 648 649 /* Set up our timeouts. */ 650 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE); 651 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE); 652 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE); 653 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE); 654 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE); 655 656 if (V_tcp_do_rfc1323) 657 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 658 if (V_tcp_do_sack) 659 tp->t_flags |= TF_SACK_PERMIT; 660 TAILQ_INIT(&tp->snd_holes); 661 tp->t_inpcb = inp; /* XXX */ 662 /* 663 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 664 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 665 * reasonable initial retransmit time. 666 */ 667 tp->t_srtt = TCPTV_SRTTBASE; 668 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 669 tp->t_rttmin = tcp_rexmit_min; 670 tp->t_rxtcur = TCPTV_RTOBASE; 671 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 672 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 673 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 674 tp->t_rcvtime = ticks; 675 tp->t_bw_rtttime = ticks; 676 /* 677 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 678 * because the socket may be bound to an IPv6 wildcard address, 679 * which may match an IPv4-mapped IPv6 address. 680 */ 681 inp->inp_ip_ttl = V_ip_defttl; 682 inp->inp_ppcb = tp; 683 return (tp); /* XXX */ 684 } 685 686 /* 687 * Drop a TCP connection, reporting 688 * the specified error. If connection is synchronized, 689 * then send a RST to peer. 690 */ 691 struct tcpcb * 692 tcp_drop(struct tcpcb *tp, int errno) 693 { 694 INIT_VNET_INET(tp->t_inpcb->inp_vnet); 695 struct socket *so = tp->t_inpcb->inp_socket; 696 697 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 698 INP_WLOCK_ASSERT(tp->t_inpcb); 699 700 if (TCPS_HAVERCVDSYN(tp->t_state)) { 701 tp->t_state = TCPS_CLOSED; 702 (void) tcp_output_reset(tp); 703 V_tcpstat.tcps_drops++; 704 } else 705 V_tcpstat.tcps_conndrops++; 706 if (errno == ETIMEDOUT && tp->t_softerror) 707 errno = tp->t_softerror; 708 so->so_error = errno; 709 return (tcp_close(tp)); 710 } 711 712 void 713 tcp_discardcb(struct tcpcb *tp) 714 { 715 INIT_VNET_INET(tp->t_vnet); 716 struct tseg_qent *q; 717 struct inpcb *inp = tp->t_inpcb; 718 struct socket *so = inp->inp_socket; 719 #ifdef INET6 720 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 721 #endif /* INET6 */ 722 723 INP_WLOCK_ASSERT(inp); 724 725 /* 726 * Make sure that all of our timers are stopped before we 727 * delete the PCB. 728 */ 729 callout_stop(&tp->t_timers->tt_rexmt); 730 callout_stop(&tp->t_timers->tt_persist); 731 callout_stop(&tp->t_timers->tt_keep); 732 callout_stop(&tp->t_timers->tt_2msl); 733 callout_stop(&tp->t_timers->tt_delack); 734 735 /* 736 * If we got enough samples through the srtt filter, 737 * save the rtt and rttvar in the routing entry. 738 * 'Enough' is arbitrarily defined as 4 rtt samples. 739 * 4 samples is enough for the srtt filter to converge 740 * to within enough % of the correct value; fewer samples 741 * and we could save a bogus rtt. The danger is not high 742 * as tcp quickly recovers from everything. 743 * XXX: Works very well but needs some more statistics! 744 */ 745 if (tp->t_rttupdated >= 4) { 746 struct hc_metrics_lite metrics; 747 u_long ssthresh; 748 749 bzero(&metrics, sizeof(metrics)); 750 /* 751 * Update the ssthresh always when the conditions below 752 * are satisfied. This gives us better new start value 753 * for the congestion avoidance for new connections. 754 * ssthresh is only set if packet loss occured on a session. 755 * 756 * XXXRW: 'so' may be NULL here, and/or socket buffer may be 757 * being torn down. Ideally this code would not use 'so'. 758 */ 759 ssthresh = tp->snd_ssthresh; 760 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 761 /* 762 * convert the limit from user data bytes to 763 * packets then to packet data bytes. 764 */ 765 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 766 if (ssthresh < 2) 767 ssthresh = 2; 768 ssthresh *= (u_long)(tp->t_maxseg + 769 #ifdef INET6 770 (isipv6 ? sizeof (struct ip6_hdr) + 771 sizeof (struct tcphdr) : 772 #endif 773 sizeof (struct tcpiphdr) 774 #ifdef INET6 775 ) 776 #endif 777 ); 778 } else 779 ssthresh = 0; 780 metrics.rmx_ssthresh = ssthresh; 781 782 metrics.rmx_rtt = tp->t_srtt; 783 metrics.rmx_rttvar = tp->t_rttvar; 784 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 785 metrics.rmx_bandwidth = tp->snd_bandwidth; 786 metrics.rmx_cwnd = tp->snd_cwnd; 787 metrics.rmx_sendpipe = 0; 788 metrics.rmx_recvpipe = 0; 789 790 tcp_hc_update(&inp->inp_inc, &metrics); 791 } 792 793 /* free the reassembly queue, if any */ 794 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 795 LIST_REMOVE(q, tqe_q); 796 m_freem(q->tqe_m); 797 uma_zfree(tcp_reass_zone, q); 798 tp->t_segqlen--; 799 V_tcp_reass_qsize--; 800 } 801 /* Disconnect offload device, if any. */ 802 tcp_offload_detach(tp); 803 804 tcp_free_sackholes(tp); 805 inp->inp_ppcb = NULL; 806 tp->t_inpcb = NULL; 807 uma_zfree(tcpcb_zone, tp); 808 } 809 810 /* 811 * Attempt to close a TCP control block, marking it as dropped, and freeing 812 * the socket if we hold the only reference. 813 */ 814 struct tcpcb * 815 tcp_close(struct tcpcb *tp) 816 { 817 INIT_VNET_INET(tp->t_inpcb->inp_vnet); 818 struct inpcb *inp = tp->t_inpcb; 819 struct socket *so; 820 821 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 822 INP_WLOCK_ASSERT(inp); 823 824 /* Notify any offload devices of listener close */ 825 if (tp->t_state == TCPS_LISTEN) 826 tcp_offload_listen_close(tp); 827 in_pcbdrop(inp); 828 V_tcpstat.tcps_closed++; 829 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 830 so = inp->inp_socket; 831 soisdisconnected(so); 832 if (inp->inp_vflag & INP_SOCKREF) { 833 KASSERT(so->so_state & SS_PROTOREF, 834 ("tcp_close: !SS_PROTOREF")); 835 inp->inp_vflag &= ~INP_SOCKREF; 836 INP_WUNLOCK(inp); 837 ACCEPT_LOCK(); 838 SOCK_LOCK(so); 839 so->so_state &= ~SS_PROTOREF; 840 sofree(so); 841 return (NULL); 842 } 843 return (tp); 844 } 845 846 void 847 tcp_drain(void) 848 { 849 VNET_ITERATOR_DECL(vnet_iter); 850 851 if (!do_tcpdrain) 852 return; 853 854 VNET_LIST_RLOCK(); 855 VNET_FOREACH(vnet_iter) { 856 CURVNET_SET(vnet_iter); 857 INIT_VNET_INET(vnet_iter); 858 struct inpcb *inpb; 859 struct tcpcb *tcpb; 860 struct tseg_qent *te; 861 862 /* 863 * Walk the tcpbs, if existing, and flush the reassembly queue, 864 * if there is one... 865 * XXX: The "Net/3" implementation doesn't imply that the TCP 866 * reassembly queue should be flushed, but in a situation 867 * where we're really low on mbufs, this is potentially 868 * usefull. 869 */ 870 INP_INFO_RLOCK(&V_tcbinfo); 871 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) { 872 if (inpb->inp_vflag & INP_TIMEWAIT) 873 continue; 874 INP_WLOCK(inpb); 875 if ((tcpb = intotcpcb(inpb)) != NULL) { 876 while ((te = LIST_FIRST(&tcpb->t_segq)) 877 != NULL) { 878 LIST_REMOVE(te, tqe_q); 879 m_freem(te->tqe_m); 880 uma_zfree(tcp_reass_zone, te); 881 tcpb->t_segqlen--; 882 V_tcp_reass_qsize--; 883 } 884 tcp_clean_sackreport(tcpb); 885 } 886 INP_WUNLOCK(inpb); 887 } 888 INP_INFO_RUNLOCK(&V_tcbinfo); 889 CURVNET_RESTORE(); 890 } 891 VNET_LIST_RUNLOCK(); 892 } 893 894 /* 895 * Notify a tcp user of an asynchronous error; 896 * store error as soft error, but wake up user 897 * (for now, won't do anything until can select for soft error). 898 * 899 * Do not wake up user since there currently is no mechanism for 900 * reporting soft errors (yet - a kqueue filter may be added). 901 */ 902 static struct inpcb * 903 tcp_notify(struct inpcb *inp, int error) 904 { 905 struct tcpcb *tp; 906 907 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 908 INP_WLOCK_ASSERT(inp); 909 910 if ((inp->inp_vflag & INP_TIMEWAIT) || 911 (inp->inp_vflag & INP_DROPPED)) 912 return (inp); 913 914 tp = intotcpcb(inp); 915 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 916 917 /* 918 * Ignore some errors if we are hooked up. 919 * If connection hasn't completed, has retransmitted several times, 920 * and receives a second error, give up now. This is better 921 * than waiting a long time to establish a connection that 922 * can never complete. 923 */ 924 if (tp->t_state == TCPS_ESTABLISHED && 925 (error == EHOSTUNREACH || error == ENETUNREACH || 926 error == EHOSTDOWN)) { 927 return (inp); 928 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 929 tp->t_softerror) { 930 tp = tcp_drop(tp, error); 931 if (tp != NULL) 932 return (inp); 933 else 934 return (NULL); 935 } else { 936 tp->t_softerror = error; 937 return (inp); 938 } 939 #if 0 940 wakeup( &so->so_timeo); 941 sorwakeup(so); 942 sowwakeup(so); 943 #endif 944 } 945 946 static int 947 tcp_pcblist(SYSCTL_HANDLER_ARGS) 948 { 949 INIT_VNET_INET(curvnet); 950 int error, i, m, n, pcb_count; 951 struct inpcb *inp, **inp_list; 952 inp_gen_t gencnt; 953 struct xinpgen xig; 954 955 /* 956 * The process of preparing the TCB list is too time-consuming and 957 * resource-intensive to repeat twice on every request. 958 */ 959 if (req->oldptr == NULL) { 960 m = syncache_pcbcount(); 961 n = V_tcbinfo.ipi_count; 962 req->oldidx = 2 * (sizeof xig) 963 + ((m + n) + n/8) * sizeof(struct xtcpcb); 964 return (0); 965 } 966 967 if (req->newptr != NULL) 968 return (EPERM); 969 970 /* 971 * OK, now we're committed to doing something. 972 */ 973 INP_INFO_RLOCK(&V_tcbinfo); 974 gencnt = V_tcbinfo.ipi_gencnt; 975 n = V_tcbinfo.ipi_count; 976 INP_INFO_RUNLOCK(&V_tcbinfo); 977 978 m = syncache_pcbcount(); 979 980 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 981 + (n + m) * sizeof(struct xtcpcb)); 982 if (error != 0) 983 return (error); 984 985 xig.xig_len = sizeof xig; 986 xig.xig_count = n + m; 987 xig.xig_gen = gencnt; 988 xig.xig_sogen = so_gencnt; 989 error = SYSCTL_OUT(req, &xig, sizeof xig); 990 if (error) 991 return (error); 992 993 error = syncache_pcblist(req, m, &pcb_count); 994 if (error) 995 return (error); 996 997 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 998 if (inp_list == NULL) 999 return (ENOMEM); 1000 1001 INP_INFO_RLOCK(&V_tcbinfo); 1002 for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0; 1003 inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) { 1004 INP_RLOCK(inp); 1005 if (inp->inp_gencnt <= gencnt) { 1006 /* 1007 * XXX: This use of cr_cansee(), introduced with 1008 * TCP state changes, is not quite right, but for 1009 * now, better than nothing. 1010 */ 1011 if (inp->inp_vflag & INP_TIMEWAIT) { 1012 if (intotw(inp) != NULL) 1013 error = cr_cansee(req->td->td_ucred, 1014 intotw(inp)->tw_cred); 1015 else 1016 error = EINVAL; /* Skip this inp. */ 1017 } else 1018 error = cr_canseeinpcb(req->td->td_ucred, inp); 1019 if (error == 0) 1020 inp_list[i++] = inp; 1021 } 1022 INP_RUNLOCK(inp); 1023 } 1024 INP_INFO_RUNLOCK(&V_tcbinfo); 1025 n = i; 1026 1027 error = 0; 1028 for (i = 0; i < n; i++) { 1029 inp = inp_list[i]; 1030 INP_RLOCK(inp); 1031 if (inp->inp_gencnt <= gencnt) { 1032 struct xtcpcb xt; 1033 void *inp_ppcb; 1034 1035 bzero(&xt, sizeof(xt)); 1036 xt.xt_len = sizeof xt; 1037 /* XXX should avoid extra copy */ 1038 bcopy(inp, &xt.xt_inp, sizeof *inp); 1039 inp_ppcb = inp->inp_ppcb; 1040 if (inp_ppcb == NULL) 1041 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 1042 else if (inp->inp_vflag & INP_TIMEWAIT) { 1043 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 1044 xt.xt_tp.t_state = TCPS_TIME_WAIT; 1045 } else 1046 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 1047 if (inp->inp_socket != NULL) 1048 sotoxsocket(inp->inp_socket, &xt.xt_socket); 1049 else { 1050 bzero(&xt.xt_socket, sizeof xt.xt_socket); 1051 xt.xt_socket.xso_protocol = IPPROTO_TCP; 1052 } 1053 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 1054 INP_RUNLOCK(inp); 1055 error = SYSCTL_OUT(req, &xt, sizeof xt); 1056 } else 1057 INP_RUNLOCK(inp); 1058 1059 } 1060 if (!error) { 1061 /* 1062 * Give the user an updated idea of our state. 1063 * If the generation differs from what we told 1064 * her before, she knows that something happened 1065 * while we were processing this request, and it 1066 * might be necessary to retry. 1067 */ 1068 INP_INFO_RLOCK(&V_tcbinfo); 1069 xig.xig_gen = V_tcbinfo.ipi_gencnt; 1070 xig.xig_sogen = so_gencnt; 1071 xig.xig_count = V_tcbinfo.ipi_count + pcb_count; 1072 INP_INFO_RUNLOCK(&V_tcbinfo); 1073 error = SYSCTL_OUT(req, &xig, sizeof xig); 1074 } 1075 free(inp_list, M_TEMP); 1076 return (error); 1077 } 1078 1079 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1080 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1081 1082 static int 1083 tcp_getcred(SYSCTL_HANDLER_ARGS) 1084 { 1085 INIT_VNET_INET(curvnet); 1086 struct xucred xuc; 1087 struct sockaddr_in addrs[2]; 1088 struct inpcb *inp; 1089 int error; 1090 1091 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1092 if (error) 1093 return (error); 1094 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1095 if (error) 1096 return (error); 1097 INP_INFO_RLOCK(&V_tcbinfo); 1098 inp = in_pcblookup_hash(&V_tcbinfo, addrs[1].sin_addr, 1099 addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1100 if (inp != NULL) { 1101 INP_RLOCK(inp); 1102 INP_INFO_RUNLOCK(&V_tcbinfo); 1103 if (inp->inp_socket == NULL) 1104 error = ENOENT; 1105 if (error == 0) 1106 error = cr_canseeinpcb(req->td->td_ucred, inp); 1107 if (error == 0) 1108 cru2x(inp->inp_cred, &xuc); 1109 INP_RUNLOCK(inp); 1110 } else { 1111 INP_INFO_RUNLOCK(&V_tcbinfo); 1112 error = ENOENT; 1113 } 1114 if (error == 0) 1115 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1116 return (error); 1117 } 1118 1119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1120 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1121 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1122 1123 #ifdef INET6 1124 static int 1125 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1126 { 1127 INIT_VNET_INET(curvnet); 1128 INIT_VNET_INET6(curvnet); 1129 struct xucred xuc; 1130 struct sockaddr_in6 addrs[2]; 1131 struct inpcb *inp; 1132 int error, mapped = 0; 1133 1134 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1135 if (error) 1136 return (error); 1137 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1138 if (error) 1139 return (error); 1140 if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 || 1141 (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) { 1142 return (error); 1143 } 1144 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1145 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1146 mapped = 1; 1147 else 1148 return (EINVAL); 1149 } 1150 1151 INP_INFO_RLOCK(&V_tcbinfo); 1152 if (mapped == 1) 1153 inp = in_pcblookup_hash(&V_tcbinfo, 1154 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1155 addrs[1].sin6_port, 1156 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1157 addrs[0].sin6_port, 1158 0, NULL); 1159 else 1160 inp = in6_pcblookup_hash(&V_tcbinfo, 1161 &addrs[1].sin6_addr, addrs[1].sin6_port, 1162 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1163 if (inp != NULL) { 1164 INP_RLOCK(inp); 1165 INP_INFO_RUNLOCK(&V_tcbinfo); 1166 if (inp->inp_socket == NULL) 1167 error = ENOENT; 1168 if (error == 0) 1169 error = cr_canseeinpcb(req->td->td_ucred, inp); 1170 if (error == 0) 1171 cru2x(inp->inp_cred, &xuc); 1172 INP_RUNLOCK(inp); 1173 } else { 1174 INP_INFO_RUNLOCK(&V_tcbinfo); 1175 error = ENOENT; 1176 } 1177 if (error == 0) 1178 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1179 return (error); 1180 } 1181 1182 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1183 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1184 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1185 #endif 1186 1187 1188 void 1189 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1190 { 1191 INIT_VNET_INET(curvnet); 1192 struct ip *ip = vip; 1193 struct tcphdr *th; 1194 struct in_addr faddr; 1195 struct inpcb *inp; 1196 struct tcpcb *tp; 1197 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1198 struct icmp *icp; 1199 struct in_conninfo inc; 1200 tcp_seq icmp_tcp_seq; 1201 int mtu; 1202 1203 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1204 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1205 return; 1206 1207 if (cmd == PRC_MSGSIZE) 1208 notify = tcp_mtudisc; 1209 else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1210 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1211 notify = tcp_drop_syn_sent; 1212 /* 1213 * Redirects don't need to be handled up here. 1214 */ 1215 else if (PRC_IS_REDIRECT(cmd)) 1216 return; 1217 /* 1218 * Source quench is depreciated. 1219 */ 1220 else if (cmd == PRC_QUENCH) 1221 return; 1222 /* 1223 * Hostdead is ugly because it goes linearly through all PCBs. 1224 * XXX: We never get this from ICMP, otherwise it makes an 1225 * excellent DoS attack on machines with many connections. 1226 */ 1227 else if (cmd == PRC_HOSTDEAD) 1228 ip = NULL; 1229 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1230 return; 1231 if (ip != NULL) { 1232 icp = (struct icmp *)((caddr_t)ip 1233 - offsetof(struct icmp, icmp_ip)); 1234 th = (struct tcphdr *)((caddr_t)ip 1235 + (ip->ip_hl << 2)); 1236 INP_INFO_WLOCK(&V_tcbinfo); 1237 inp = in_pcblookup_hash(&V_tcbinfo, faddr, th->th_dport, 1238 ip->ip_src, th->th_sport, 0, NULL); 1239 if (inp != NULL) { 1240 INP_WLOCK(inp); 1241 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1242 !(inp->inp_vflag & INP_DROPPED) && 1243 !(inp->inp_socket == NULL)) { 1244 icmp_tcp_seq = htonl(th->th_seq); 1245 tp = intotcpcb(inp); 1246 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1247 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1248 if (cmd == PRC_MSGSIZE) { 1249 /* 1250 * MTU discovery: 1251 * If we got a needfrag set the MTU 1252 * in the route to the suggested new 1253 * value (if given) and then notify. 1254 */ 1255 bzero(&inc, sizeof(inc)); 1256 inc.inc_flags = 0; /* IPv4 */ 1257 inc.inc_faddr = faddr; 1258 inc.inc_fibnum = 1259 inp->inp_inc.inc_fibnum; 1260 1261 mtu = ntohs(icp->icmp_nextmtu); 1262 /* 1263 * If no alternative MTU was 1264 * proposed, try the next smaller 1265 * one. ip->ip_len has already 1266 * been swapped in icmp_input(). 1267 */ 1268 if (!mtu) 1269 mtu = ip_next_mtu(ip->ip_len, 1270 1); 1271 if (mtu < max(296, V_tcp_minmss 1272 + sizeof(struct tcpiphdr))) 1273 mtu = 0; 1274 if (!mtu) 1275 mtu = V_tcp_mssdflt 1276 + sizeof(struct tcpiphdr); 1277 /* 1278 * Only cache the the MTU if it 1279 * is smaller than the interface 1280 * or route MTU. tcp_mtudisc() 1281 * will do right thing by itself. 1282 */ 1283 if (mtu <= tcp_maxmtu(&inc, NULL)) 1284 tcp_hc_updatemtu(&inc, mtu); 1285 } 1286 1287 inp = (*notify)(inp, inetctlerrmap[cmd]); 1288 } 1289 } 1290 if (inp != NULL) 1291 INP_WUNLOCK(inp); 1292 } else { 1293 inc.inc_fport = th->th_dport; 1294 inc.inc_lport = th->th_sport; 1295 inc.inc_faddr = faddr; 1296 inc.inc_laddr = ip->ip_src; 1297 #ifdef INET6 1298 inc.inc_isipv6 = 0; 1299 #endif 1300 syncache_unreach(&inc, th); 1301 } 1302 INP_INFO_WUNLOCK(&V_tcbinfo); 1303 } else 1304 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify); 1305 } 1306 1307 #ifdef INET6 1308 void 1309 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1310 { 1311 INIT_VNET_INET(curvnet); 1312 struct tcphdr th; 1313 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1314 struct ip6_hdr *ip6; 1315 struct mbuf *m; 1316 struct ip6ctlparam *ip6cp = NULL; 1317 const struct sockaddr_in6 *sa6_src = NULL; 1318 int off; 1319 struct tcp_portonly { 1320 u_int16_t th_sport; 1321 u_int16_t th_dport; 1322 } *thp; 1323 1324 if (sa->sa_family != AF_INET6 || 1325 sa->sa_len != sizeof(struct sockaddr_in6)) 1326 return; 1327 1328 if (cmd == PRC_MSGSIZE) 1329 notify = tcp_mtudisc; 1330 else if (!PRC_IS_REDIRECT(cmd) && 1331 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1332 return; 1333 /* Source quench is depreciated. */ 1334 else if (cmd == PRC_QUENCH) 1335 return; 1336 1337 /* if the parameter is from icmp6, decode it. */ 1338 if (d != NULL) { 1339 ip6cp = (struct ip6ctlparam *)d; 1340 m = ip6cp->ip6c_m; 1341 ip6 = ip6cp->ip6c_ip6; 1342 off = ip6cp->ip6c_off; 1343 sa6_src = ip6cp->ip6c_src; 1344 } else { 1345 m = NULL; 1346 ip6 = NULL; 1347 off = 0; /* fool gcc */ 1348 sa6_src = &sa6_any; 1349 } 1350 1351 if (ip6 != NULL) { 1352 struct in_conninfo inc; 1353 /* 1354 * XXX: We assume that when IPV6 is non NULL, 1355 * M and OFF are valid. 1356 */ 1357 1358 /* check if we can safely examine src and dst ports */ 1359 if (m->m_pkthdr.len < off + sizeof(*thp)) 1360 return; 1361 1362 bzero(&th, sizeof(th)); 1363 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1364 1365 in6_pcbnotify(&V_tcbinfo, sa, th.th_dport, 1366 (struct sockaddr *)ip6cp->ip6c_src, 1367 th.th_sport, cmd, NULL, notify); 1368 1369 inc.inc_fport = th.th_dport; 1370 inc.inc_lport = th.th_sport; 1371 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1372 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1373 inc.inc_isipv6 = 1; 1374 INP_INFO_WLOCK(&V_tcbinfo); 1375 syncache_unreach(&inc, &th); 1376 INP_INFO_WUNLOCK(&V_tcbinfo); 1377 } else 1378 in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1379 0, cmd, NULL, notify); 1380 } 1381 #endif /* INET6 */ 1382 1383 1384 /* 1385 * Following is where TCP initial sequence number generation occurs. 1386 * 1387 * There are two places where we must use initial sequence numbers: 1388 * 1. In SYN-ACK packets. 1389 * 2. In SYN packets. 1390 * 1391 * All ISNs for SYN-ACK packets are generated by the syncache. See 1392 * tcp_syncache.c for details. 1393 * 1394 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1395 * depends on this property. In addition, these ISNs should be 1396 * unguessable so as to prevent connection hijacking. To satisfy 1397 * the requirements of this situation, the algorithm outlined in 1398 * RFC 1948 is used, with only small modifications. 1399 * 1400 * Implementation details: 1401 * 1402 * Time is based off the system timer, and is corrected so that it 1403 * increases by one megabyte per second. This allows for proper 1404 * recycling on high speed LANs while still leaving over an hour 1405 * before rollover. 1406 * 1407 * As reading the *exact* system time is too expensive to be done 1408 * whenever setting up a TCP connection, we increment the time 1409 * offset in two ways. First, a small random positive increment 1410 * is added to isn_offset for each connection that is set up. 1411 * Second, the function tcp_isn_tick fires once per clock tick 1412 * and increments isn_offset as necessary so that sequence numbers 1413 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1414 * random positive increments serve only to ensure that the same 1415 * exact sequence number is never sent out twice (as could otherwise 1416 * happen when a port is recycled in less than the system tick 1417 * interval.) 1418 * 1419 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1420 * between seeding of isn_secret. This is normally set to zero, 1421 * as reseeding should not be necessary. 1422 * 1423 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1424 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1425 * general, this means holding an exclusive (write) lock. 1426 */ 1427 1428 #define ISN_BYTES_PER_SECOND 1048576 1429 #define ISN_STATIC_INCREMENT 4096 1430 #define ISN_RANDOM_INCREMENT (4096 - 1) 1431 1432 static u_char isn_secret[32]; 1433 static int isn_last_reseed; 1434 static u_int32_t isn_offset, isn_offset_old; 1435 static MD5_CTX isn_ctx; 1436 1437 tcp_seq 1438 tcp_new_isn(struct tcpcb *tp) 1439 { 1440 INIT_VNET_INET(tp->t_vnet); 1441 u_int32_t md5_buffer[4]; 1442 tcp_seq new_isn; 1443 1444 INP_WLOCK_ASSERT(tp->t_inpcb); 1445 1446 ISN_LOCK(); 1447 /* Seed if this is the first use, reseed if requested. */ 1448 if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) && 1449 (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz) 1450 < (u_int)ticks))) { 1451 read_random(&V_isn_secret, sizeof(V_isn_secret)); 1452 V_isn_last_reseed = ticks; 1453 } 1454 1455 /* Compute the md5 hash and return the ISN. */ 1456 MD5Init(&V_isn_ctx); 1457 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1458 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1459 #ifdef INET6 1460 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1461 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1462 sizeof(struct in6_addr)); 1463 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1464 sizeof(struct in6_addr)); 1465 } else 1466 #endif 1467 { 1468 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1469 sizeof(struct in_addr)); 1470 MD5Update(&V_isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1471 sizeof(struct in_addr)); 1472 } 1473 MD5Update(&V_isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret)); 1474 MD5Final((u_char *) &md5_buffer, &V_isn_ctx); 1475 new_isn = (tcp_seq) md5_buffer[0]; 1476 V_isn_offset += ISN_STATIC_INCREMENT + 1477 (arc4random() & ISN_RANDOM_INCREMENT); 1478 new_isn += V_isn_offset; 1479 ISN_UNLOCK(); 1480 return (new_isn); 1481 } 1482 1483 /* 1484 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary 1485 * to keep time flowing at a relatively constant rate. If the random 1486 * increments have already pushed us past the projected offset, do nothing. 1487 */ 1488 static void 1489 tcp_isn_tick(void *xtp) 1490 { 1491 VNET_ITERATOR_DECL(vnet_iter); 1492 u_int32_t projected_offset; 1493 1494 ISN_LOCK(); 1495 VNET_LIST_RLOCK(); 1496 VNET_FOREACH(vnet_iter) { 1497 CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS */ 1498 INIT_VNET_INET(curvnet); 1499 projected_offset = 1500 V_isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1501 1502 if (SEQ_GT(projected_offset, V_isn_offset)) 1503 V_isn_offset = projected_offset; 1504 1505 V_isn_offset_old = V_isn_offset; 1506 CURVNET_RESTORE(); 1507 } 1508 VNET_LIST_RUNLOCK(); 1509 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1510 ISN_UNLOCK(); 1511 } 1512 1513 /* 1514 * When a specific ICMP unreachable message is received and the 1515 * connection state is SYN-SENT, drop the connection. This behavior 1516 * is controlled by the icmp_may_rst sysctl. 1517 */ 1518 struct inpcb * 1519 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1520 { 1521 #ifdef INVARIANTS 1522 INIT_VNET_INET(inp->inp_vnet); 1523 #endif 1524 struct tcpcb *tp; 1525 1526 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1527 INP_WLOCK_ASSERT(inp); 1528 1529 if ((inp->inp_vflag & INP_TIMEWAIT) || 1530 (inp->inp_vflag & INP_DROPPED)) 1531 return (inp); 1532 1533 tp = intotcpcb(inp); 1534 if (tp->t_state != TCPS_SYN_SENT) 1535 return (inp); 1536 1537 tp = tcp_drop(tp, errno); 1538 if (tp != NULL) 1539 return (inp); 1540 else 1541 return (NULL); 1542 } 1543 1544 /* 1545 * When `need fragmentation' ICMP is received, update our idea of the MSS 1546 * based on the new value in the route. Also nudge TCP to send something, 1547 * since we know the packet we just sent was dropped. 1548 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1549 */ 1550 struct inpcb * 1551 tcp_mtudisc(struct inpcb *inp, int errno) 1552 { 1553 INIT_VNET_INET(inp->inp_vnet); 1554 struct tcpcb *tp; 1555 struct socket *so; 1556 1557 INP_WLOCK_ASSERT(inp); 1558 if ((inp->inp_vflag & INP_TIMEWAIT) || 1559 (inp->inp_vflag & INP_DROPPED)) 1560 return (inp); 1561 1562 tp = intotcpcb(inp); 1563 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1564 1565 tcp_mss_update(tp, -1, NULL, NULL); 1566 1567 so = inp->inp_socket; 1568 SOCKBUF_LOCK(&so->so_snd); 1569 /* If the mss is larger than the socket buffer, decrease the mss. */ 1570 if (so->so_snd.sb_hiwat < tp->t_maxseg) 1571 tp->t_maxseg = so->so_snd.sb_hiwat; 1572 SOCKBUF_UNLOCK(&so->so_snd); 1573 1574 V_tcpstat.tcps_mturesent++; 1575 tp->t_rtttime = 0; 1576 tp->snd_nxt = tp->snd_una; 1577 tcp_free_sackholes(tp); 1578 tp->snd_recover = tp->snd_max; 1579 if (tp->t_flags & TF_SACK_PERMIT) 1580 EXIT_FASTRECOVERY(tp); 1581 tcp_output_send(tp); 1582 return (inp); 1583 } 1584 1585 /* 1586 * Look-up the routing entry to the peer of this inpcb. If no route 1587 * is found and it cannot be allocated, then return 0. This routine 1588 * is called by TCP routines that access the rmx structure and by 1589 * tcp_mss_update to get the peer/interface MTU. 1590 */ 1591 u_long 1592 tcp_maxmtu(struct in_conninfo *inc, int *flags) 1593 { 1594 struct route sro; 1595 struct sockaddr_in *dst; 1596 struct ifnet *ifp; 1597 u_long maxmtu = 0; 1598 1599 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1600 1601 bzero(&sro, sizeof(sro)); 1602 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1603 dst = (struct sockaddr_in *)&sro.ro_dst; 1604 dst->sin_family = AF_INET; 1605 dst->sin_len = sizeof(*dst); 1606 dst->sin_addr = inc->inc_faddr; 1607 in_rtalloc_ign(&sro, RTF_CLONING, inc->inc_fibnum); 1608 } 1609 if (sro.ro_rt != NULL) { 1610 ifp = sro.ro_rt->rt_ifp; 1611 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1612 maxmtu = ifp->if_mtu; 1613 else 1614 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1615 1616 /* Report additional interface capabilities. */ 1617 if (flags != NULL) { 1618 if (ifp->if_capenable & IFCAP_TSO4 && 1619 ifp->if_hwassist & CSUM_TSO) 1620 *flags |= CSUM_TSO; 1621 } 1622 RTFREE(sro.ro_rt); 1623 } 1624 return (maxmtu); 1625 } 1626 1627 #ifdef INET6 1628 u_long 1629 tcp_maxmtu6(struct in_conninfo *inc, int *flags) 1630 { 1631 struct route_in6 sro6; 1632 struct ifnet *ifp; 1633 u_long maxmtu = 0; 1634 1635 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1636 1637 bzero(&sro6, sizeof(sro6)); 1638 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1639 sro6.ro_dst.sin6_family = AF_INET6; 1640 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1641 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1642 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1643 } 1644 if (sro6.ro_rt != NULL) { 1645 ifp = sro6.ro_rt->rt_ifp; 1646 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1647 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1648 else 1649 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1650 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1651 1652 /* Report additional interface capabilities. */ 1653 if (flags != NULL) { 1654 if (ifp->if_capenable & IFCAP_TSO6 && 1655 ifp->if_hwassist & CSUM_TSO) 1656 *flags |= CSUM_TSO; 1657 } 1658 RTFREE(sro6.ro_rt); 1659 } 1660 1661 return (maxmtu); 1662 } 1663 #endif /* INET6 */ 1664 1665 #ifdef IPSEC 1666 /* compute ESP/AH header size for TCP, including outer IP header. */ 1667 size_t 1668 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1669 { 1670 struct inpcb *inp; 1671 struct mbuf *m; 1672 size_t hdrsiz; 1673 struct ip *ip; 1674 #ifdef INET6 1675 struct ip6_hdr *ip6; 1676 #endif 1677 struct tcphdr *th; 1678 1679 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1680 return (0); 1681 MGETHDR(m, M_DONTWAIT, MT_DATA); 1682 if (!m) 1683 return (0); 1684 1685 #ifdef INET6 1686 if ((inp->inp_vflag & INP_IPV6) != 0) { 1687 ip6 = mtod(m, struct ip6_hdr *); 1688 th = (struct tcphdr *)(ip6 + 1); 1689 m->m_pkthdr.len = m->m_len = 1690 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1691 tcpip_fillheaders(inp, ip6, th); 1692 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1693 } else 1694 #endif /* INET6 */ 1695 { 1696 ip = mtod(m, struct ip *); 1697 th = (struct tcphdr *)(ip + 1); 1698 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1699 tcpip_fillheaders(inp, ip, th); 1700 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1701 } 1702 1703 m_free(m); 1704 return (hdrsiz); 1705 } 1706 #endif /* IPSEC */ 1707 1708 /* 1709 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1710 * 1711 * This code attempts to calculate the bandwidth-delay product as a 1712 * means of determining the optimal window size to maximize bandwidth, 1713 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1714 * routers. This code also does a fairly good job keeping RTTs in check 1715 * across slow links like modems. We implement an algorithm which is very 1716 * similar (but not meant to be) TCP/Vegas. The code operates on the 1717 * transmitter side of a TCP connection and so only effects the transmit 1718 * side of the connection. 1719 * 1720 * BACKGROUND: TCP makes no provision for the management of buffer space 1721 * at the end points or at the intermediate routers and switches. A TCP 1722 * stream, whether using NewReno or not, will eventually buffer as 1723 * many packets as it is able and the only reason this typically works is 1724 * due to the fairly small default buffers made available for a connection 1725 * (typicaly 16K or 32K). As machines use larger windows and/or window 1726 * scaling it is now fairly easy for even a single TCP connection to blow-out 1727 * all available buffer space not only on the local interface, but on 1728 * intermediate routers and switches as well. NewReno makes a misguided 1729 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1730 * then backing off, then steadily increasing the window again until another 1731 * failure occurs, ad-infinitum. This results in terrible oscillation that 1732 * is only made worse as network loads increase and the idea of intentionally 1733 * blowing out network buffers is, frankly, a terrible way to manage network 1734 * resources. 1735 * 1736 * It is far better to limit the transmit window prior to the failure 1737 * condition being achieved. There are two general ways to do this: First 1738 * you can 'scan' through different transmit window sizes and locate the 1739 * point where the RTT stops increasing, indicating that you have filled the 1740 * pipe, then scan backwards until you note that RTT stops decreasing, then 1741 * repeat ad-infinitum. This method works in principle but has severe 1742 * implementation issues due to RTT variances, timer granularity, and 1743 * instability in the algorithm which can lead to many false positives and 1744 * create oscillations as well as interact badly with other TCP streams 1745 * implementing the same algorithm. 1746 * 1747 * The second method is to limit the window to the bandwidth delay product 1748 * of the link. This is the method we implement. RTT variances and our 1749 * own manipulation of the congestion window, bwnd, can potentially 1750 * destabilize the algorithm. For this reason we have to stabilize the 1751 * elements used to calculate the window. We do this by using the minimum 1752 * observed RTT, the long term average of the observed bandwidth, and 1753 * by adding two segments worth of slop. It isn't perfect but it is able 1754 * to react to changing conditions and gives us a very stable basis on 1755 * which to extend the algorithm. 1756 */ 1757 void 1758 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1759 { 1760 INIT_VNET_INET(tp->t_vnet); 1761 u_long bw; 1762 u_long bwnd; 1763 int save_ticks; 1764 1765 INP_WLOCK_ASSERT(tp->t_inpcb); 1766 1767 /* 1768 * If inflight_enable is disabled in the middle of a tcp connection, 1769 * make sure snd_bwnd is effectively disabled. 1770 */ 1771 if (V_tcp_inflight_enable == 0 || 1772 tp->t_rttlow < V_tcp_inflight_rttthresh) { 1773 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1774 tp->snd_bandwidth = 0; 1775 return; 1776 } 1777 1778 /* 1779 * Figure out the bandwidth. Due to the tick granularity this 1780 * is a very rough number and it MUST be averaged over a fairly 1781 * long period of time. XXX we need to take into account a link 1782 * that is not using all available bandwidth, but for now our 1783 * slop will ramp us up if this case occurs and the bandwidth later 1784 * increases. 1785 * 1786 * Note: if ticks rollover 'bw' may wind up negative. We must 1787 * effectively reset t_bw_rtttime for this case. 1788 */ 1789 save_ticks = ticks; 1790 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1791 return; 1792 1793 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1794 (save_ticks - tp->t_bw_rtttime); 1795 tp->t_bw_rtttime = save_ticks; 1796 tp->t_bw_rtseq = ack_seq; 1797 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1798 return; 1799 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1800 1801 tp->snd_bandwidth = bw; 1802 1803 /* 1804 * Calculate the semi-static bandwidth delay product, plus two maximal 1805 * segments. The additional slop puts us squarely in the sweet 1806 * spot and also handles the bandwidth run-up case and stabilization. 1807 * Without the slop we could be locking ourselves into a lower 1808 * bandwidth. 1809 * 1810 * Situations Handled: 1811 * (1) Prevents over-queueing of packets on LANs, especially on 1812 * high speed LANs, allowing larger TCP buffers to be 1813 * specified, and also does a good job preventing 1814 * over-queueing of packets over choke points like modems 1815 * (at least for the transmit side). 1816 * 1817 * (2) Is able to handle changing network loads (bandwidth 1818 * drops so bwnd drops, bandwidth increases so bwnd 1819 * increases). 1820 * 1821 * (3) Theoretically should stabilize in the face of multiple 1822 * connections implementing the same algorithm (this may need 1823 * a little work). 1824 * 1825 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1826 * be adjusted with a sysctl but typically only needs to be 1827 * on very slow connections. A value no smaller then 5 1828 * should be used, but only reduce this default if you have 1829 * no other choice. 1830 */ 1831 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1832 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + V_tcp_inflight_stab * tp->t_maxseg / 10; 1833 #undef USERTT 1834 1835 if (tcp_inflight_debug > 0) { 1836 static int ltime; 1837 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1838 ltime = ticks; 1839 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1840 tp, 1841 bw, 1842 tp->t_rttbest, 1843 tp->t_srtt, 1844 bwnd 1845 ); 1846 } 1847 } 1848 if ((long)bwnd < V_tcp_inflight_min) 1849 bwnd = V_tcp_inflight_min; 1850 if (bwnd > V_tcp_inflight_max) 1851 bwnd = V_tcp_inflight_max; 1852 if ((long)bwnd < tp->t_maxseg * 2) 1853 bwnd = tp->t_maxseg * 2; 1854 tp->snd_bwnd = bwnd; 1855 } 1856 1857 #ifdef TCP_SIGNATURE 1858 /* 1859 * Callback function invoked by m_apply() to digest TCP segment data 1860 * contained within an mbuf chain. 1861 */ 1862 static int 1863 tcp_signature_apply(void *fstate, void *data, u_int len) 1864 { 1865 1866 MD5Update(fstate, (u_char *)data, len); 1867 return (0); 1868 } 1869 1870 /* 1871 * Compute TCP-MD5 hash of a TCP segment. (RFC2385) 1872 * 1873 * Parameters: 1874 * m pointer to head of mbuf chain 1875 * _unused 1876 * len length of TCP segment data, excluding options 1877 * optlen length of TCP segment options 1878 * buf pointer to storage for computed MD5 digest 1879 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1880 * 1881 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1882 * When called from tcp_input(), we can be sure that th_sum has been 1883 * zeroed out and verified already. 1884 * 1885 * Return 0 if successful, otherwise return -1. 1886 * 1887 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1888 * search with the destination IP address, and a 'magic SPI' to be 1889 * determined by the application. This is hardcoded elsewhere to 1179 1890 * right now. Another branch of this code exists which uses the SPD to 1891 * specify per-application flows but it is unstable. 1892 */ 1893 int 1894 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen, 1895 u_char *buf, u_int direction) 1896 { 1897 union sockaddr_union dst; 1898 struct ippseudo ippseudo; 1899 MD5_CTX ctx; 1900 int doff; 1901 struct ip *ip; 1902 struct ipovly *ipovly; 1903 struct secasvar *sav; 1904 struct tcphdr *th; 1905 #ifdef INET6 1906 struct ip6_hdr *ip6; 1907 struct in6_addr in6; 1908 char ip6buf[INET6_ADDRSTRLEN]; 1909 uint32_t plen; 1910 uint16_t nhdr; 1911 #endif 1912 u_short savecsum; 1913 1914 KASSERT(m != NULL, ("NULL mbuf chain")); 1915 KASSERT(buf != NULL, ("NULL signature pointer")); 1916 1917 /* Extract the destination from the IP header in the mbuf. */ 1918 bzero(&dst, sizeof(union sockaddr_union)); 1919 ip = mtod(m, struct ip *); 1920 #ifdef INET6 1921 ip6 = NULL; /* Make the compiler happy. */ 1922 #endif 1923 switch (ip->ip_v) { 1924 case IPVERSION: 1925 dst.sa.sa_len = sizeof(struct sockaddr_in); 1926 dst.sa.sa_family = AF_INET; 1927 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1928 ip->ip_src : ip->ip_dst; 1929 break; 1930 #ifdef INET6 1931 case (IPV6_VERSION >> 4): 1932 ip6 = mtod(m, struct ip6_hdr *); 1933 dst.sa.sa_len = sizeof(struct sockaddr_in6); 1934 dst.sa.sa_family = AF_INET6; 1935 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ? 1936 ip6->ip6_src : ip6->ip6_dst; 1937 break; 1938 #endif 1939 default: 1940 return (EINVAL); 1941 /* NOTREACHED */ 1942 break; 1943 } 1944 1945 /* Look up an SADB entry which matches the address of the peer. */ 1946 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 1947 if (sav == NULL) { 1948 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__, 1949 (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) : 1950 #ifdef INET6 1951 (ip->ip_v == (IPV6_VERSION >> 4)) ? 1952 ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) : 1953 #endif 1954 "(unsupported)")); 1955 return (EINVAL); 1956 } 1957 1958 MD5Init(&ctx); 1959 /* 1960 * Step 1: Update MD5 hash with IP(v6) pseudo-header. 1961 * 1962 * XXX The ippseudo header MUST be digested in network byte order, 1963 * or else we'll fail the regression test. Assume all fields we've 1964 * been doing arithmetic on have been in host byte order. 1965 * XXX One cannot depend on ipovly->ih_len here. When called from 1966 * tcp_output(), the underlying ip_len member has not yet been set. 1967 */ 1968 switch (ip->ip_v) { 1969 case IPVERSION: 1970 ipovly = (struct ipovly *)ip; 1971 ippseudo.ippseudo_src = ipovly->ih_src; 1972 ippseudo.ippseudo_dst = ipovly->ih_dst; 1973 ippseudo.ippseudo_pad = 0; 1974 ippseudo.ippseudo_p = IPPROTO_TCP; 1975 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + 1976 optlen); 1977 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 1978 1979 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip)); 1980 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen; 1981 break; 1982 #ifdef INET6 1983 /* 1984 * RFC 2385, 2.0 Proposal 1985 * For IPv6, the pseudo-header is as described in RFC 2460, namely the 1986 * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero- 1987 * extended next header value (to form 32 bits), and 32-bit segment 1988 * length. 1989 * Note: Upper-Layer Packet Length comes before Next Header. 1990 */ 1991 case (IPV6_VERSION >> 4): 1992 in6 = ip6->ip6_src; 1993 in6_clearscope(&in6); 1994 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 1995 in6 = ip6->ip6_dst; 1996 in6_clearscope(&in6); 1997 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 1998 plen = htonl(len + sizeof(struct tcphdr) + optlen); 1999 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t)); 2000 nhdr = 0; 2001 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2002 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2003 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2004 nhdr = IPPROTO_TCP; 2005 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2006 2007 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr)); 2008 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen; 2009 break; 2010 #endif 2011 default: 2012 return (EINVAL); 2013 /* NOTREACHED */ 2014 break; 2015 } 2016 2017 2018 /* 2019 * Step 2: Update MD5 hash with TCP header, excluding options. 2020 * The TCP checksum must be set to zero. 2021 */ 2022 savecsum = th->th_sum; 2023 th->th_sum = 0; 2024 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2025 th->th_sum = savecsum; 2026 2027 /* 2028 * Step 3: Update MD5 hash with TCP segment data. 2029 * Use m_apply() to avoid an early m_pullup(). 2030 */ 2031 if (len > 0) 2032 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2033 2034 /* 2035 * Step 4: Update MD5 hash with shared secret. 2036 */ 2037 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth)); 2038 MD5Final(buf, &ctx); 2039 2040 key_sa_recordxfer(sav, m); 2041 KEY_FREESAV(&sav); 2042 return (0); 2043 } 2044 #endif /* TCP_SIGNATURE */ 2045 2046 static int 2047 sysctl_drop(SYSCTL_HANDLER_ARGS) 2048 { 2049 INIT_VNET_INET(curvnet); 2050 #ifdef INET6 2051 INIT_VNET_INET6(curvnet); 2052 #endif 2053 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2054 struct sockaddr_storage addrs[2]; 2055 struct inpcb *inp; 2056 struct tcpcb *tp; 2057 struct tcptw *tw; 2058 struct sockaddr_in *fin, *lin; 2059 #ifdef INET6 2060 struct sockaddr_in6 *fin6, *lin6; 2061 struct in6_addr f6, l6; 2062 #endif 2063 int error; 2064 2065 inp = NULL; 2066 fin = lin = NULL; 2067 #ifdef INET6 2068 fin6 = lin6 = NULL; 2069 #endif 2070 error = 0; 2071 2072 if (req->oldptr != NULL || req->oldlen != 0) 2073 return (EINVAL); 2074 if (req->newptr == NULL) 2075 return (EPERM); 2076 if (req->newlen < sizeof(addrs)) 2077 return (ENOMEM); 2078 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2079 if (error) 2080 return (error); 2081 2082 switch (addrs[0].ss_family) { 2083 #ifdef INET6 2084 case AF_INET6: 2085 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2086 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2087 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2088 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2089 return (EINVAL); 2090 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2091 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2092 return (EINVAL); 2093 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2094 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2095 fin = (struct sockaddr_in *)&addrs[0]; 2096 lin = (struct sockaddr_in *)&addrs[1]; 2097 break; 2098 } 2099 error = sa6_embedscope(fin6, V_ip6_use_defzone); 2100 if (error) 2101 return (error); 2102 error = sa6_embedscope(lin6, V_ip6_use_defzone); 2103 if (error) 2104 return (error); 2105 break; 2106 #endif 2107 case AF_INET: 2108 fin = (struct sockaddr_in *)&addrs[0]; 2109 lin = (struct sockaddr_in *)&addrs[1]; 2110 if (fin->sin_len != sizeof(struct sockaddr_in) || 2111 lin->sin_len != sizeof(struct sockaddr_in)) 2112 return (EINVAL); 2113 break; 2114 default: 2115 return (EINVAL); 2116 } 2117 INP_INFO_WLOCK(&V_tcbinfo); 2118 switch (addrs[0].ss_family) { 2119 #ifdef INET6 2120 case AF_INET6: 2121 inp = in6_pcblookup_hash(&V_tcbinfo, &f6, fin6->sin6_port, 2122 &l6, lin6->sin6_port, 0, NULL); 2123 break; 2124 #endif 2125 case AF_INET: 2126 inp = in_pcblookup_hash(&V_tcbinfo, fin->sin_addr, 2127 fin->sin_port, lin->sin_addr, lin->sin_port, 0, NULL); 2128 break; 2129 } 2130 if (inp != NULL) { 2131 INP_WLOCK(inp); 2132 if (inp->inp_vflag & INP_TIMEWAIT) { 2133 /* 2134 * XXXRW: There currently exists a state where an 2135 * inpcb is present, but its timewait state has been 2136 * discarded. For now, don't allow dropping of this 2137 * type of inpcb. 2138 */ 2139 tw = intotw(inp); 2140 if (tw != NULL) 2141 tcp_twclose(tw, 0); 2142 else 2143 INP_WUNLOCK(inp); 2144 } else if (!(inp->inp_vflag & INP_DROPPED) && 2145 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2146 tp = intotcpcb(inp); 2147 tp = tcp_drop(tp, ECONNABORTED); 2148 if (tp != NULL) 2149 INP_WUNLOCK(inp); 2150 } else 2151 INP_WUNLOCK(inp); 2152 } else 2153 error = ESRCH; 2154 INP_INFO_WUNLOCK(&V_tcbinfo); 2155 return (error); 2156 } 2157 2158 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2159 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2160 0, sysctl_drop, "", "Drop TCP connection"); 2161 2162 /* 2163 * Generate a standardized TCP log line for use throughout the 2164 * tcp subsystem. Memory allocation is done with M_NOWAIT to 2165 * allow use in the interrupt context. 2166 * 2167 * NB: The caller MUST free(s, M_TCPLOG) the returned string. 2168 * NB: The function may return NULL if memory allocation failed. 2169 * 2170 * Due to header inclusion and ordering limitations the struct ip 2171 * and ip6_hdr pointers have to be passed as void pointers. 2172 */ 2173 char * 2174 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, 2175 const void *ip6hdr) 2176 { 2177 char *s, *sp; 2178 size_t size; 2179 struct ip *ip; 2180 #ifdef INET6 2181 const struct ip6_hdr *ip6; 2182 2183 ip6 = (const struct ip6_hdr *)ip6hdr; 2184 #endif /* INET6 */ 2185 ip = (struct ip *)ip4hdr; 2186 2187 /* 2188 * The log line looks like this: 2189 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>" 2190 */ 2191 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") + 2192 sizeof(PRINT_TH_FLAGS) + 1 + 2193 #ifdef INET6 2194 2 * INET6_ADDRSTRLEN; 2195 #else 2196 2 * INET_ADDRSTRLEN; 2197 #endif /* INET6 */ 2198 2199 /* Is logging enabled? */ 2200 if (tcp_log_debug == 0 && tcp_log_in_vain == 0) 2201 return (NULL); 2202 2203 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT); 2204 if (s == NULL) 2205 return (NULL); 2206 2207 strcat(s, "TCP: ["); 2208 sp = s + strlen(s); 2209 2210 if (inc && inc->inc_isipv6 == 0) { 2211 inet_ntoa_r(inc->inc_faddr, sp); 2212 sp = s + strlen(s); 2213 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2214 sp = s + strlen(s); 2215 inet_ntoa_r(inc->inc_laddr, sp); 2216 sp = s + strlen(s); 2217 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2218 #ifdef INET6 2219 } else if (inc) { 2220 ip6_sprintf(sp, &inc->inc6_faddr); 2221 sp = s + strlen(s); 2222 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2223 sp = s + strlen(s); 2224 ip6_sprintf(sp, &inc->inc6_laddr); 2225 sp = s + strlen(s); 2226 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2227 } else if (ip6 && th) { 2228 ip6_sprintf(sp, &ip6->ip6_src); 2229 sp = s + strlen(s); 2230 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2231 sp = s + strlen(s); 2232 ip6_sprintf(sp, &ip6->ip6_dst); 2233 sp = s + strlen(s); 2234 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2235 #endif /* INET6 */ 2236 } else if (ip && th) { 2237 inet_ntoa_r(ip->ip_src, sp); 2238 sp = s + strlen(s); 2239 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2240 sp = s + strlen(s); 2241 inet_ntoa_r(ip->ip_dst, sp); 2242 sp = s + strlen(s); 2243 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2244 } else { 2245 free(s, M_TCPLOG); 2246 return (NULL); 2247 } 2248 sp = s + strlen(s); 2249 if (th) 2250 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS); 2251 if (*(s + size - 1) != '\0') 2252 panic("%s: string too long", __func__); 2253 return (s); 2254 } 2255