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 <netinet/vinet.h> 98 #include <netinet6/ip6protosw.h> 99 #include <netinet6/vinet6.h> 100 101 #ifdef IPSEC 102 #include <netipsec/ipsec.h> 103 #include <netipsec/xform.h> 104 #ifdef INET6 105 #include <netipsec/ipsec6.h> 106 #endif 107 #include <netipsec/key.h> 108 #include <sys/syslog.h> 109 #endif /*IPSEC*/ 110 111 #include <machine/in_cksum.h> 112 #include <sys/md5.h> 113 114 #include <security/mac/mac_framework.h> 115 116 #ifdef VIMAGE_GLOBALS 117 int tcp_mssdflt; 118 #ifdef INET6 119 int tcp_v6mssdflt; 120 #endif 121 int tcp_minmss; 122 int tcp_do_rfc1323; 123 static int icmp_may_rst; 124 static int tcp_isn_reseed_interval; 125 static int tcp_inflight_enable; 126 static int tcp_inflight_rttthresh; 127 static int tcp_inflight_min; 128 static int tcp_inflight_max; 129 static int tcp_inflight_stab; 130 #endif 131 132 static int 133 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS) 134 { 135 INIT_VNET_INET(curvnet); 136 int error, new; 137 138 new = V_tcp_mssdflt; 139 error = sysctl_handle_int(oidp, &new, 0, req); 140 if (error == 0 && req->newptr) { 141 if (new < TCP_MINMSS) 142 error = EINVAL; 143 else 144 V_tcp_mssdflt = new; 145 } 146 return (error); 147 } 148 149 SYSCTL_V_PROC(V_NET, vnet_inet, _net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, 150 CTLTYPE_INT|CTLFLAG_RW, tcp_mssdflt, 0, 151 &sysctl_net_inet_tcp_mss_check, "I", 152 "Default TCP Maximum Segment Size"); 153 154 #ifdef INET6 155 static int 156 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS) 157 { 158 INIT_VNET_INET(curvnet); 159 int error, new; 160 161 new = V_tcp_v6mssdflt; 162 error = sysctl_handle_int(oidp, &new, 0, req); 163 if (error == 0 && req->newptr) { 164 if (new < TCP_MINMSS) 165 error = EINVAL; 166 else 167 V_tcp_v6mssdflt = new; 168 } 169 return (error); 170 } 171 172 SYSCTL_V_PROC(V_NET, vnet_inet, _net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 173 CTLTYPE_INT|CTLFLAG_RW, tcp_v6mssdflt, 0, 174 &sysctl_net_inet_tcp_mss_v6_check, "I", 175 "Default TCP Maximum Segment Size for IPv6"); 176 #endif 177 178 /* 179 * Minimum MSS we accept and use. This prevents DoS attacks where 180 * we are forced to a ridiculous low MSS like 20 and send hundreds 181 * of packets instead of one. The effect scales with the available 182 * bandwidth and quickly saturates the CPU and network interface 183 * with packet generation and sending. Set to zero to disable MINMSS 184 * checking. This setting prevents us from sending too small packets. 185 */ 186 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, minmss, 187 CTLFLAG_RW, tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 188 189 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, 190 CTLFLAG_RW, tcp_do_rfc1323, 0, 191 "Enable rfc1323 (high performance TCP) extensions"); 192 193 static int tcp_log_debug = 0; 194 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW, 195 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments"); 196 197 static int tcp_tcbhashsize = 0; 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 199 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 200 201 static int do_tcpdrain = 1; 202 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 203 "Enable tcp_drain routine for extra help when low on mbufs"); 204 205 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, pcbcount, 206 CTLFLAG_RD, tcbinfo.ipi_count, 0, "Number of active PCBs"); 207 208 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, icmp_may_rst, 209 CTLFLAG_RW, icmp_may_rst, 0, 210 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 211 212 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, isn_reseed_interval, 213 CTLFLAG_RW, tcp_isn_reseed_interval, 0, 214 "Seconds between reseeding of ISN secret"); 215 216 /* 217 * TCP bandwidth limiting sysctls. Note that the default lower bound of 218 * 1024 exists only for debugging. A good production default would be 219 * something like 6100. 220 */ 221 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0, 222 "TCP inflight data limiting"); 223 224 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, enable, 225 CTLFLAG_RW, tcp_inflight_enable, 0, 226 "Enable automatic TCP inflight data limiting"); 227 228 static int tcp_inflight_debug = 0; 229 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW, 230 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 231 232 SYSCTL_V_PROC(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, rttthresh, 233 CTLTYPE_INT|CTLFLAG_RW, tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, 234 "I", "RTT threshold below which inflight will deactivate itself"); 235 236 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, min, 237 CTLFLAG_RW, tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 238 239 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, max, 240 CTLFLAG_RW, tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 241 242 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_inflight, OID_AUTO, stab, 243 CTLFLAG_RW, tcp_inflight_stab, 0, 244 "Inflight Algorithm Stabilization 20 = 2 packets"); 245 246 uma_zone_t sack_hole_zone; 247 248 static struct inpcb *tcp_notify(struct inpcb *, int); 249 static void tcp_isn_tick(void *); 250 251 /* 252 * Target size of TCP PCB hash tables. Must be a power of two. 253 * 254 * Note that this can be overridden by the kernel environment 255 * variable net.inet.tcp.tcbhashsize 256 */ 257 #ifndef TCBHASHSIZE 258 #define TCBHASHSIZE 512 259 #endif 260 261 /* 262 * XXX 263 * Callouts should be moved into struct tcp directly. They are currently 264 * separate because the tcpcb structure is exported to userland for sysctl 265 * parsing purposes, which do not know about callouts. 266 */ 267 struct tcpcb_mem { 268 struct tcpcb tcb; 269 struct tcp_timer tt; 270 }; 271 272 static uma_zone_t tcpcb_zone; 273 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); 274 struct callout isn_callout; 275 static struct mtx isn_mtx; 276 277 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) 278 #define ISN_LOCK() mtx_lock(&isn_mtx) 279 #define ISN_UNLOCK() mtx_unlock(&isn_mtx) 280 281 /* 282 * TCP initialization. 283 */ 284 static void 285 tcp_zone_change(void *tag) 286 { 287 288 uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets); 289 uma_zone_set_max(tcpcb_zone, maxsockets); 290 tcp_tw_zone_change(); 291 } 292 293 static int 294 tcp_inpcb_init(void *mem, int size, int flags) 295 { 296 struct inpcb *inp = mem; 297 298 INP_LOCK_INIT(inp, "inp", "tcpinp"); 299 return (0); 300 } 301 302 void 303 tcp_init(void) 304 { 305 INIT_VNET_INET(curvnet); 306 int hashsize; 307 308 V_blackhole = 0; 309 V_tcp_delack_enabled = 1; 310 V_drop_synfin = 0; 311 V_tcp_do_rfc3042 = 1; 312 V_tcp_do_rfc3390 = 1; 313 V_tcp_do_ecn = 0; 314 V_tcp_ecn_maxretries = 1; 315 V_tcp_insecure_rst = 0; 316 V_tcp_do_autorcvbuf = 1; 317 V_tcp_autorcvbuf_inc = 16*1024; 318 V_tcp_autorcvbuf_max = 256*1024; 319 320 V_tcp_mssdflt = TCP_MSS; 321 #ifdef INET6 322 V_tcp_v6mssdflt = TCP6_MSS; 323 #endif 324 V_tcp_minmss = TCP_MINMSS; 325 V_tcp_do_rfc1323 = 1; 326 V_icmp_may_rst = 1; 327 V_tcp_isn_reseed_interval = 0; 328 V_tcp_inflight_enable = 1; 329 V_tcp_inflight_min = 6144; 330 V_tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 331 V_tcp_inflight_stab = 20; 332 333 V_path_mtu_discovery = 1; 334 V_ss_fltsz = 1; 335 V_ss_fltsz_local = 4; 336 V_tcp_do_newreno = 1; 337 V_tcp_do_tso = 1; 338 V_tcp_do_autosndbuf = 1; 339 V_tcp_autosndbuf_inc = 8*1024; 340 V_tcp_autosndbuf_max = 256*1024; 341 342 V_nolocaltimewait = 0; 343 344 V_tcp_do_sack = 1; 345 V_tcp_sack_maxholes = 128; 346 V_tcp_sack_globalmaxholes = 65536; 347 V_tcp_sack_globalholes = 0; 348 349 tcp_delacktime = TCPTV_DELACK; 350 tcp_keepinit = TCPTV_KEEP_INIT; 351 tcp_keepidle = TCPTV_KEEP_IDLE; 352 tcp_keepintvl = TCPTV_KEEPINTVL; 353 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 354 tcp_msl = TCPTV_MSL; 355 tcp_rexmit_min = TCPTV_MIN; 356 if (tcp_rexmit_min < 1) 357 tcp_rexmit_min = 1; 358 tcp_rexmit_slop = TCPTV_CPU_VAR; 359 V_tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH; 360 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT; 361 362 TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack); 363 364 INP_INFO_LOCK_INIT(&V_tcbinfo, "tcp"); 365 LIST_INIT(&V_tcb); 366 V_tcbinfo.ipi_listhead = &V_tcb; 367 hashsize = TCBHASHSIZE; 368 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 369 if (!powerof2(hashsize)) { 370 printf("WARNING: TCB hash size not a power of 2\n"); 371 hashsize = 512; /* safe default */ 372 } 373 tcp_tcbhashsize = hashsize; 374 V_tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB, 375 &V_tcbinfo.ipi_hashmask); 376 V_tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB, 377 &V_tcbinfo.ipi_porthashmask); 378 V_tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 379 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 380 uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets); 381 #ifdef INET6 382 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 383 #else /* INET6 */ 384 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 385 #endif /* INET6 */ 386 if (max_protohdr < TCP_MINPROTOHDR) 387 max_protohdr = TCP_MINPROTOHDR; 388 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 389 panic("tcp_init"); 390 #undef TCP_MINPROTOHDR 391 /* 392 * These have to be type stable for the benefit of the timers. 393 */ 394 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 395 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 396 uma_zone_set_max(tcpcb_zone, maxsockets); 397 tcp_tw_init(); 398 syncache_init(); 399 tcp_hc_init(); 400 tcp_reass_init(); 401 ISN_LOCK_INIT(); 402 callout_init(&isn_callout, CALLOUT_MPSAFE); 403 tcp_isn_tick(NULL); 404 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, 405 SHUTDOWN_PRI_DEFAULT); 406 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole), 407 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 408 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, 409 EVENTHANDLER_PRI_ANY); 410 } 411 412 void 413 tcp_fini(void *xtp) 414 { 415 416 callout_stop(&isn_callout); 417 } 418 419 /* 420 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 421 * tcp_template used to store this data in mbufs, but we now recopy it out 422 * of the tcpcb each time to conserve mbufs. 423 */ 424 void 425 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr) 426 { 427 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 428 429 INP_WLOCK_ASSERT(inp); 430 431 #ifdef INET6 432 if ((inp->inp_vflag & INP_IPV6) != 0) { 433 struct ip6_hdr *ip6; 434 435 ip6 = (struct ip6_hdr *)ip_ptr; 436 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 437 (inp->inp_flow & IPV6_FLOWINFO_MASK); 438 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 439 (IPV6_VERSION & IPV6_VERSION_MASK); 440 ip6->ip6_nxt = IPPROTO_TCP; 441 ip6->ip6_plen = htons(sizeof(struct tcphdr)); 442 ip6->ip6_src = inp->in6p_laddr; 443 ip6->ip6_dst = inp->in6p_faddr; 444 } else 445 #endif 446 { 447 struct ip *ip; 448 449 ip = (struct ip *)ip_ptr; 450 ip->ip_v = IPVERSION; 451 ip->ip_hl = 5; 452 ip->ip_tos = inp->inp_ip_tos; 453 ip->ip_len = 0; 454 ip->ip_id = 0; 455 ip->ip_off = 0; 456 ip->ip_ttl = inp->inp_ip_ttl; 457 ip->ip_sum = 0; 458 ip->ip_p = IPPROTO_TCP; 459 ip->ip_src = inp->inp_laddr; 460 ip->ip_dst = inp->inp_faddr; 461 } 462 th->th_sport = inp->inp_lport; 463 th->th_dport = inp->inp_fport; 464 th->th_seq = 0; 465 th->th_ack = 0; 466 th->th_x2 = 0; 467 th->th_off = 5; 468 th->th_flags = 0; 469 th->th_win = 0; 470 th->th_urp = 0; 471 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 472 } 473 474 /* 475 * Create template to be used to send tcp packets on a connection. 476 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 477 * use for this function is in keepalives, which use tcp_respond. 478 */ 479 struct tcptemp * 480 tcpip_maketemplate(struct inpcb *inp) 481 { 482 struct tcptemp *t; 483 484 t = malloc(sizeof(*t), M_TEMP, M_NOWAIT); 485 if (t == NULL) 486 return (NULL); 487 tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t); 488 return (t); 489 } 490 491 /* 492 * Send a single message to the TCP at address specified by 493 * the given TCP/IP header. If m == NULL, then we make a copy 494 * of the tcpiphdr at ti and send directly to the addressed host. 495 * This is used to force keep alive messages out using the TCP 496 * template for a connection. If flags are given then we send 497 * a message back to the TCP which originated the * segment ti, 498 * and discard the mbuf containing it and any other attached mbufs. 499 * 500 * In any case the ack and sequence number of the transmitted 501 * segment are as specified by the parameters. 502 * 503 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 504 */ 505 void 506 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 507 tcp_seq ack, tcp_seq seq, int flags) 508 { 509 INIT_VNET_INET(curvnet); 510 int tlen; 511 int win = 0; 512 struct ip *ip; 513 struct tcphdr *nth; 514 #ifdef INET6 515 struct ip6_hdr *ip6; 516 int isipv6; 517 #endif /* INET6 */ 518 int ipflags = 0; 519 struct inpcb *inp; 520 521 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 522 523 #ifdef INET6 524 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 525 ip6 = ipgen; 526 #endif /* INET6 */ 527 ip = ipgen; 528 529 if (tp != NULL) { 530 inp = tp->t_inpcb; 531 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 532 INP_WLOCK_ASSERT(inp); 533 } else 534 inp = NULL; 535 536 if (tp != NULL) { 537 if (!(flags & TH_RST)) { 538 win = sbspace(&inp->inp_socket->so_rcv); 539 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 540 win = (long)TCP_MAXWIN << tp->rcv_scale; 541 } 542 } 543 if (m == NULL) { 544 m = m_gethdr(M_DONTWAIT, MT_DATA); 545 if (m == NULL) 546 return; 547 tlen = 0; 548 m->m_data += max_linkhdr; 549 #ifdef INET6 550 if (isipv6) { 551 bcopy((caddr_t)ip6, mtod(m, caddr_t), 552 sizeof(struct ip6_hdr)); 553 ip6 = mtod(m, struct ip6_hdr *); 554 nth = (struct tcphdr *)(ip6 + 1); 555 } else 556 #endif /* INET6 */ 557 { 558 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 559 ip = mtod(m, struct ip *); 560 nth = (struct tcphdr *)(ip + 1); 561 } 562 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 563 flags = TH_ACK; 564 } else { 565 /* 566 * reuse the mbuf. 567 * XXX MRT We inherrit the FIB, which is lucky. 568 */ 569 m_freem(m->m_next); 570 m->m_next = NULL; 571 m->m_data = (caddr_t)ipgen; 572 /* m_len is set later */ 573 tlen = 0; 574 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 575 #ifdef INET6 576 if (isipv6) { 577 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 578 nth = (struct tcphdr *)(ip6 + 1); 579 } else 580 #endif /* INET6 */ 581 { 582 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 583 nth = (struct tcphdr *)(ip + 1); 584 } 585 if (th != nth) { 586 /* 587 * this is usually a case when an extension header 588 * exists between the IPv6 header and the 589 * TCP header. 590 */ 591 nth->th_sport = th->th_sport; 592 nth->th_dport = th->th_dport; 593 } 594 xchg(nth->th_dport, nth->th_sport, n_short); 595 #undef xchg 596 } 597 #ifdef INET6 598 if (isipv6) { 599 ip6->ip6_flow = 0; 600 ip6->ip6_vfc = IPV6_VERSION; 601 ip6->ip6_nxt = IPPROTO_TCP; 602 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 603 tlen)); 604 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 605 } else 606 #endif 607 { 608 tlen += sizeof (struct tcpiphdr); 609 ip->ip_len = tlen; 610 ip->ip_ttl = V_ip_defttl; 611 if (V_path_mtu_discovery) 612 ip->ip_off |= IP_DF; 613 } 614 m->m_len = tlen; 615 m->m_pkthdr.len = tlen; 616 m->m_pkthdr.rcvif = NULL; 617 #ifdef MAC 618 if (inp != NULL) { 619 /* 620 * Packet is associated with a socket, so allow the 621 * label of the response to reflect the socket label. 622 */ 623 INP_WLOCK_ASSERT(inp); 624 mac_inpcb_create_mbuf(inp, m); 625 } else { 626 /* 627 * Packet is not associated with a socket, so possibly 628 * update the label in place. 629 */ 630 mac_netinet_tcp_reply(m); 631 } 632 #endif 633 nth->th_seq = htonl(seq); 634 nth->th_ack = htonl(ack); 635 nth->th_x2 = 0; 636 nth->th_off = sizeof (struct tcphdr) >> 2; 637 nth->th_flags = flags; 638 if (tp != NULL) 639 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 640 else 641 nth->th_win = htons((u_short)win); 642 nth->th_urp = 0; 643 #ifdef INET6 644 if (isipv6) { 645 nth->th_sum = 0; 646 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 647 sizeof(struct ip6_hdr), 648 tlen - sizeof(struct ip6_hdr)); 649 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb : 650 NULL, NULL); 651 } else 652 #endif /* INET6 */ 653 { 654 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 655 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 656 m->m_pkthdr.csum_flags = CSUM_TCP; 657 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 658 } 659 #ifdef TCPDEBUG 660 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 661 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 662 #endif 663 #ifdef INET6 664 if (isipv6) 665 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 666 else 667 #endif /* INET6 */ 668 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 669 } 670 671 /* 672 * Create a new TCP control block, making an 673 * empty reassembly queue and hooking it to the argument 674 * protocol control block. The `inp' parameter must have 675 * come from the zone allocator set up in tcp_init(). 676 */ 677 struct tcpcb * 678 tcp_newtcpcb(struct inpcb *inp) 679 { 680 INIT_VNET_INET(inp->inp_vnet); 681 struct tcpcb_mem *tm; 682 struct tcpcb *tp; 683 #ifdef INET6 684 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 685 #endif /* INET6 */ 686 687 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 688 if (tm == NULL) 689 return (NULL); 690 tp = &tm->tcb; 691 tp->t_timers = &tm->tt; 692 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 693 tp->t_maxseg = tp->t_maxopd = 694 #ifdef INET6 695 isipv6 ? V_tcp_v6mssdflt : 696 #endif /* INET6 */ 697 V_tcp_mssdflt; 698 699 /* Set up our timeouts. */ 700 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE); 701 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE); 702 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE); 703 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE); 704 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE); 705 706 if (V_tcp_do_rfc1323) 707 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 708 if (V_tcp_do_sack) 709 tp->t_flags |= TF_SACK_PERMIT; 710 TAILQ_INIT(&tp->snd_holes); 711 tp->t_inpcb = inp; /* XXX */ 712 /* 713 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 714 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 715 * reasonable initial retransmit time. 716 */ 717 tp->t_srtt = TCPTV_SRTTBASE; 718 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 719 tp->t_rttmin = tcp_rexmit_min; 720 tp->t_rxtcur = TCPTV_RTOBASE; 721 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 722 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 723 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 724 tp->t_rcvtime = ticks; 725 tp->t_bw_rtttime = ticks; 726 /* 727 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 728 * because the socket may be bound to an IPv6 wildcard address, 729 * which may match an IPv4-mapped IPv6 address. 730 */ 731 inp->inp_ip_ttl = V_ip_defttl; 732 inp->inp_ppcb = tp; 733 return (tp); /* XXX */ 734 } 735 736 /* 737 * Drop a TCP connection, reporting 738 * the specified error. If connection is synchronized, 739 * then send a RST to peer. 740 */ 741 struct tcpcb * 742 tcp_drop(struct tcpcb *tp, int errno) 743 { 744 INIT_VNET_INET(tp->t_inpcb->inp_vnet); 745 struct socket *so = tp->t_inpcb->inp_socket; 746 747 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 748 INP_WLOCK_ASSERT(tp->t_inpcb); 749 750 if (TCPS_HAVERCVDSYN(tp->t_state)) { 751 tp->t_state = TCPS_CLOSED; 752 (void) tcp_output_reset(tp); 753 V_tcpstat.tcps_drops++; 754 } else 755 V_tcpstat.tcps_conndrops++; 756 if (errno == ETIMEDOUT && tp->t_softerror) 757 errno = tp->t_softerror; 758 so->so_error = errno; 759 return (tcp_close(tp)); 760 } 761 762 void 763 tcp_discardcb(struct tcpcb *tp) 764 { 765 INIT_VNET_INET(tp->t_vnet); 766 struct tseg_qent *q; 767 struct inpcb *inp = tp->t_inpcb; 768 struct socket *so = inp->inp_socket; 769 #ifdef INET6 770 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 771 #endif /* INET6 */ 772 773 INP_WLOCK_ASSERT(inp); 774 775 /* 776 * Make sure that all of our timers are stopped before we 777 * delete the PCB. 778 */ 779 callout_stop(&tp->t_timers->tt_rexmt); 780 callout_stop(&tp->t_timers->tt_persist); 781 callout_stop(&tp->t_timers->tt_keep); 782 callout_stop(&tp->t_timers->tt_2msl); 783 callout_stop(&tp->t_timers->tt_delack); 784 785 /* 786 * If we got enough samples through the srtt filter, 787 * save the rtt and rttvar in the routing entry. 788 * 'Enough' is arbitrarily defined as 4 rtt samples. 789 * 4 samples is enough for the srtt filter to converge 790 * to within enough % of the correct value; fewer samples 791 * and we could save a bogus rtt. The danger is not high 792 * as tcp quickly recovers from everything. 793 * XXX: Works very well but needs some more statistics! 794 */ 795 if (tp->t_rttupdated >= 4) { 796 struct hc_metrics_lite metrics; 797 u_long ssthresh; 798 799 bzero(&metrics, sizeof(metrics)); 800 /* 801 * Update the ssthresh always when the conditions below 802 * are satisfied. This gives us better new start value 803 * for the congestion avoidance for new connections. 804 * ssthresh is only set if packet loss occured on a session. 805 * 806 * XXXRW: 'so' may be NULL here, and/or socket buffer may be 807 * being torn down. Ideally this code would not use 'so'. 808 */ 809 ssthresh = tp->snd_ssthresh; 810 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 811 /* 812 * convert the limit from user data bytes to 813 * packets then to packet data bytes. 814 */ 815 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 816 if (ssthresh < 2) 817 ssthresh = 2; 818 ssthresh *= (u_long)(tp->t_maxseg + 819 #ifdef INET6 820 (isipv6 ? sizeof (struct ip6_hdr) + 821 sizeof (struct tcphdr) : 822 #endif 823 sizeof (struct tcpiphdr) 824 #ifdef INET6 825 ) 826 #endif 827 ); 828 } else 829 ssthresh = 0; 830 metrics.rmx_ssthresh = ssthresh; 831 832 metrics.rmx_rtt = tp->t_srtt; 833 metrics.rmx_rttvar = tp->t_rttvar; 834 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 835 metrics.rmx_bandwidth = tp->snd_bandwidth; 836 metrics.rmx_cwnd = tp->snd_cwnd; 837 metrics.rmx_sendpipe = 0; 838 metrics.rmx_recvpipe = 0; 839 840 tcp_hc_update(&inp->inp_inc, &metrics); 841 } 842 843 /* free the reassembly queue, if any */ 844 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 845 LIST_REMOVE(q, tqe_q); 846 m_freem(q->tqe_m); 847 uma_zfree(tcp_reass_zone, q); 848 tp->t_segqlen--; 849 V_tcp_reass_qsize--; 850 } 851 /* Disconnect offload device, if any. */ 852 tcp_offload_detach(tp); 853 854 tcp_free_sackholes(tp); 855 inp->inp_ppcb = NULL; 856 tp->t_inpcb = NULL; 857 uma_zfree(tcpcb_zone, tp); 858 } 859 860 /* 861 * Attempt to close a TCP control block, marking it as dropped, and freeing 862 * the socket if we hold the only reference. 863 */ 864 struct tcpcb * 865 tcp_close(struct tcpcb *tp) 866 { 867 INIT_VNET_INET(tp->t_inpcb->inp_vnet); 868 struct inpcb *inp = tp->t_inpcb; 869 struct socket *so; 870 871 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 872 INP_WLOCK_ASSERT(inp); 873 874 /* Notify any offload devices of listener close */ 875 if (tp->t_state == TCPS_LISTEN) 876 tcp_offload_listen_close(tp); 877 in_pcbdrop(inp); 878 V_tcpstat.tcps_closed++; 879 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL")); 880 so = inp->inp_socket; 881 soisdisconnected(so); 882 if (inp->inp_vflag & INP_SOCKREF) { 883 KASSERT(so->so_state & SS_PROTOREF, 884 ("tcp_close: !SS_PROTOREF")); 885 inp->inp_vflag &= ~INP_SOCKREF; 886 INP_WUNLOCK(inp); 887 ACCEPT_LOCK(); 888 SOCK_LOCK(so); 889 so->so_state &= ~SS_PROTOREF; 890 sofree(so); 891 return (NULL); 892 } 893 return (tp); 894 } 895 896 void 897 tcp_drain(void) 898 { 899 VNET_ITERATOR_DECL(vnet_iter); 900 901 if (!do_tcpdrain) 902 return; 903 904 VNET_LIST_RLOCK(); 905 VNET_FOREACH(vnet_iter) { 906 CURVNET_SET(vnet_iter); 907 INIT_VNET_INET(vnet_iter); 908 struct inpcb *inpb; 909 struct tcpcb *tcpb; 910 struct tseg_qent *te; 911 912 /* 913 * Walk the tcpbs, if existing, and flush the reassembly queue, 914 * if there is one... 915 * XXX: The "Net/3" implementation doesn't imply that the TCP 916 * reassembly queue should be flushed, but in a situation 917 * where we're really low on mbufs, this is potentially 918 * usefull. 919 */ 920 INP_INFO_RLOCK(&V_tcbinfo); 921 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) { 922 if (inpb->inp_vflag & INP_TIMEWAIT) 923 continue; 924 INP_WLOCK(inpb); 925 if ((tcpb = intotcpcb(inpb)) != NULL) { 926 while ((te = LIST_FIRST(&tcpb->t_segq)) 927 != NULL) { 928 LIST_REMOVE(te, tqe_q); 929 m_freem(te->tqe_m); 930 uma_zfree(tcp_reass_zone, te); 931 tcpb->t_segqlen--; 932 V_tcp_reass_qsize--; 933 } 934 tcp_clean_sackreport(tcpb); 935 } 936 INP_WUNLOCK(inpb); 937 } 938 INP_INFO_RUNLOCK(&V_tcbinfo); 939 CURVNET_RESTORE(); 940 } 941 VNET_LIST_RUNLOCK(); 942 } 943 944 /* 945 * Notify a tcp user of an asynchronous error; 946 * store error as soft error, but wake up user 947 * (for now, won't do anything until can select for soft error). 948 * 949 * Do not wake up user since there currently is no mechanism for 950 * reporting soft errors (yet - a kqueue filter may be added). 951 */ 952 static struct inpcb * 953 tcp_notify(struct inpcb *inp, int error) 954 { 955 struct tcpcb *tp; 956 #ifdef INVARIANTS 957 INIT_VNET_INET(inp->inp_vnet); /* V_tcbinfo WLOCK ASSERT */ 958 #endif 959 960 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 961 INP_WLOCK_ASSERT(inp); 962 963 if ((inp->inp_vflag & INP_TIMEWAIT) || 964 (inp->inp_vflag & INP_DROPPED)) 965 return (inp); 966 967 tp = intotcpcb(inp); 968 KASSERT(tp != NULL, ("tcp_notify: tp == NULL")); 969 970 /* 971 * Ignore some errors if we are hooked up. 972 * If connection hasn't completed, has retransmitted several times, 973 * and receives a second error, give up now. This is better 974 * than waiting a long time to establish a connection that 975 * can never complete. 976 */ 977 if (tp->t_state == TCPS_ESTABLISHED && 978 (error == EHOSTUNREACH || error == ENETUNREACH || 979 error == EHOSTDOWN)) { 980 return (inp); 981 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 982 tp->t_softerror) { 983 tp = tcp_drop(tp, error); 984 if (tp != NULL) 985 return (inp); 986 else 987 return (NULL); 988 } else { 989 tp->t_softerror = error; 990 return (inp); 991 } 992 #if 0 993 wakeup( &so->so_timeo); 994 sorwakeup(so); 995 sowwakeup(so); 996 #endif 997 } 998 999 static int 1000 tcp_pcblist(SYSCTL_HANDLER_ARGS) 1001 { 1002 INIT_VNET_INET(curvnet); 1003 int error, i, m, n, pcb_count; 1004 struct inpcb *inp, **inp_list; 1005 inp_gen_t gencnt; 1006 struct xinpgen xig; 1007 1008 /* 1009 * The process of preparing the TCB list is too time-consuming and 1010 * resource-intensive to repeat twice on every request. 1011 */ 1012 if (req->oldptr == NULL) { 1013 m = syncache_pcbcount(); 1014 n = V_tcbinfo.ipi_count; 1015 req->oldidx = 2 * (sizeof xig) 1016 + ((m + n) + n/8) * sizeof(struct xtcpcb); 1017 return (0); 1018 } 1019 1020 if (req->newptr != NULL) 1021 return (EPERM); 1022 1023 /* 1024 * OK, now we're committed to doing something. 1025 */ 1026 INP_INFO_RLOCK(&V_tcbinfo); 1027 gencnt = V_tcbinfo.ipi_gencnt; 1028 n = V_tcbinfo.ipi_count; 1029 INP_INFO_RUNLOCK(&V_tcbinfo); 1030 1031 m = syncache_pcbcount(); 1032 1033 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig) 1034 + (n + m) * sizeof(struct xtcpcb)); 1035 if (error != 0) 1036 return (error); 1037 1038 xig.xig_len = sizeof xig; 1039 xig.xig_count = n + m; 1040 xig.xig_gen = gencnt; 1041 xig.xig_sogen = so_gencnt; 1042 error = SYSCTL_OUT(req, &xig, sizeof xig); 1043 if (error) 1044 return (error); 1045 1046 error = syncache_pcblist(req, m, &pcb_count); 1047 if (error) 1048 return (error); 1049 1050 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 1051 if (inp_list == NULL) 1052 return (ENOMEM); 1053 1054 INP_INFO_RLOCK(&V_tcbinfo); 1055 for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0; 1056 inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) { 1057 INP_RLOCK(inp); 1058 if (inp->inp_gencnt <= gencnt) { 1059 /* 1060 * XXX: This use of cr_cansee(), introduced with 1061 * TCP state changes, is not quite right, but for 1062 * now, better than nothing. 1063 */ 1064 if (inp->inp_vflag & INP_TIMEWAIT) { 1065 if (intotw(inp) != NULL) 1066 error = cr_cansee(req->td->td_ucred, 1067 intotw(inp)->tw_cred); 1068 else 1069 error = EINVAL; /* Skip this inp. */ 1070 } else 1071 error = cr_canseeinpcb(req->td->td_ucred, inp); 1072 if (error == 0) 1073 inp_list[i++] = inp; 1074 } 1075 INP_RUNLOCK(inp); 1076 } 1077 INP_INFO_RUNLOCK(&V_tcbinfo); 1078 n = i; 1079 1080 error = 0; 1081 for (i = 0; i < n; i++) { 1082 inp = inp_list[i]; 1083 INP_RLOCK(inp); 1084 if (inp->inp_gencnt <= gencnt) { 1085 struct xtcpcb xt; 1086 void *inp_ppcb; 1087 1088 bzero(&xt, sizeof(xt)); 1089 xt.xt_len = sizeof xt; 1090 /* XXX should avoid extra copy */ 1091 bcopy(inp, &xt.xt_inp, sizeof *inp); 1092 inp_ppcb = inp->inp_ppcb; 1093 if (inp_ppcb == NULL) 1094 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 1095 else if (inp->inp_vflag & INP_TIMEWAIT) { 1096 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 1097 xt.xt_tp.t_state = TCPS_TIME_WAIT; 1098 } else 1099 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 1100 if (inp->inp_socket != NULL) 1101 sotoxsocket(inp->inp_socket, &xt.xt_socket); 1102 else { 1103 bzero(&xt.xt_socket, sizeof xt.xt_socket); 1104 xt.xt_socket.xso_protocol = IPPROTO_TCP; 1105 } 1106 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 1107 INP_RUNLOCK(inp); 1108 error = SYSCTL_OUT(req, &xt, sizeof xt); 1109 } else 1110 INP_RUNLOCK(inp); 1111 1112 } 1113 if (!error) { 1114 /* 1115 * Give the user an updated idea of our state. 1116 * If the generation differs from what we told 1117 * her before, she knows that something happened 1118 * while we were processing this request, and it 1119 * might be necessary to retry. 1120 */ 1121 INP_INFO_RLOCK(&V_tcbinfo); 1122 xig.xig_gen = V_tcbinfo.ipi_gencnt; 1123 xig.xig_sogen = so_gencnt; 1124 xig.xig_count = V_tcbinfo.ipi_count + pcb_count; 1125 INP_INFO_RUNLOCK(&V_tcbinfo); 1126 error = SYSCTL_OUT(req, &xig, sizeof xig); 1127 } 1128 free(inp_list, M_TEMP); 1129 return (error); 1130 } 1131 1132 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1133 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1134 1135 static int 1136 tcp_getcred(SYSCTL_HANDLER_ARGS) 1137 { 1138 INIT_VNET_INET(curvnet); 1139 struct xucred xuc; 1140 struct sockaddr_in addrs[2]; 1141 struct inpcb *inp; 1142 int error; 1143 1144 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1145 if (error) 1146 return (error); 1147 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1148 if (error) 1149 return (error); 1150 INP_INFO_RLOCK(&V_tcbinfo); 1151 inp = in_pcblookup_hash(&V_tcbinfo, addrs[1].sin_addr, 1152 addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1153 if (inp != NULL) { 1154 INP_RLOCK(inp); 1155 INP_INFO_RUNLOCK(&V_tcbinfo); 1156 if (inp->inp_socket == NULL) 1157 error = ENOENT; 1158 if (error == 0) 1159 error = cr_canseeinpcb(req->td->td_ucred, inp); 1160 if (error == 0) 1161 cru2x(inp->inp_cred, &xuc); 1162 INP_RUNLOCK(inp); 1163 } else { 1164 INP_INFO_RUNLOCK(&V_tcbinfo); 1165 error = ENOENT; 1166 } 1167 if (error == 0) 1168 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1169 return (error); 1170 } 1171 1172 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 1173 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1174 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 1175 1176 #ifdef INET6 1177 static int 1178 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1179 { 1180 INIT_VNET_INET(curvnet); 1181 INIT_VNET_INET6(curvnet); 1182 struct xucred xuc; 1183 struct sockaddr_in6 addrs[2]; 1184 struct inpcb *inp; 1185 int error, mapped = 0; 1186 1187 error = priv_check(req->td, PRIV_NETINET_GETCRED); 1188 if (error) 1189 return (error); 1190 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1191 if (error) 1192 return (error); 1193 if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 || 1194 (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) { 1195 return (error); 1196 } 1197 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1198 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1199 mapped = 1; 1200 else 1201 return (EINVAL); 1202 } 1203 1204 INP_INFO_RLOCK(&V_tcbinfo); 1205 if (mapped == 1) 1206 inp = in_pcblookup_hash(&V_tcbinfo, 1207 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1208 addrs[1].sin6_port, 1209 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1210 addrs[0].sin6_port, 1211 0, NULL); 1212 else 1213 inp = in6_pcblookup_hash(&V_tcbinfo, 1214 &addrs[1].sin6_addr, addrs[1].sin6_port, 1215 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL); 1216 if (inp != NULL) { 1217 INP_RLOCK(inp); 1218 INP_INFO_RUNLOCK(&V_tcbinfo); 1219 if (inp->inp_socket == NULL) 1220 error = ENOENT; 1221 if (error == 0) 1222 error = cr_canseeinpcb(req->td->td_ucred, inp); 1223 if (error == 0) 1224 cru2x(inp->inp_cred, &xuc); 1225 INP_RUNLOCK(inp); 1226 } else { 1227 INP_INFO_RUNLOCK(&V_tcbinfo); 1228 error = ENOENT; 1229 } 1230 if (error == 0) 1231 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1232 return (error); 1233 } 1234 1235 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1236 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1237 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1238 #endif 1239 1240 1241 void 1242 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1243 { 1244 INIT_VNET_INET(curvnet); 1245 struct ip *ip = vip; 1246 struct tcphdr *th; 1247 struct in_addr faddr; 1248 struct inpcb *inp; 1249 struct tcpcb *tp; 1250 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1251 struct icmp *icp; 1252 struct in_conninfo inc; 1253 tcp_seq icmp_tcp_seq; 1254 int mtu; 1255 1256 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1257 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1258 return; 1259 1260 if (cmd == PRC_MSGSIZE) 1261 notify = tcp_mtudisc; 1262 else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1263 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1264 notify = tcp_drop_syn_sent; 1265 /* 1266 * Redirects don't need to be handled up here. 1267 */ 1268 else if (PRC_IS_REDIRECT(cmd)) 1269 return; 1270 /* 1271 * Source quench is depreciated. 1272 */ 1273 else if (cmd == PRC_QUENCH) 1274 return; 1275 /* 1276 * Hostdead is ugly because it goes linearly through all PCBs. 1277 * XXX: We never get this from ICMP, otherwise it makes an 1278 * excellent DoS attack on machines with many connections. 1279 */ 1280 else if (cmd == PRC_HOSTDEAD) 1281 ip = NULL; 1282 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1283 return; 1284 if (ip != NULL) { 1285 icp = (struct icmp *)((caddr_t)ip 1286 - offsetof(struct icmp, icmp_ip)); 1287 th = (struct tcphdr *)((caddr_t)ip 1288 + (ip->ip_hl << 2)); 1289 INP_INFO_WLOCK(&V_tcbinfo); 1290 inp = in_pcblookup_hash(&V_tcbinfo, faddr, th->th_dport, 1291 ip->ip_src, th->th_sport, 0, NULL); 1292 if (inp != NULL) { 1293 INP_WLOCK(inp); 1294 if (!(inp->inp_vflag & INP_TIMEWAIT) && 1295 !(inp->inp_vflag & INP_DROPPED) && 1296 !(inp->inp_socket == NULL)) { 1297 icmp_tcp_seq = htonl(th->th_seq); 1298 tp = intotcpcb(inp); 1299 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) && 1300 SEQ_LT(icmp_tcp_seq, tp->snd_max)) { 1301 if (cmd == PRC_MSGSIZE) { 1302 /* 1303 * MTU discovery: 1304 * If we got a needfrag set the MTU 1305 * in the route to the suggested new 1306 * value (if given) and then notify. 1307 */ 1308 bzero(&inc, sizeof(inc)); 1309 inc.inc_faddr = faddr; 1310 inc.inc_fibnum = 1311 inp->inp_inc.inc_fibnum; 1312 1313 mtu = ntohs(icp->icmp_nextmtu); 1314 /* 1315 * If no alternative MTU was 1316 * proposed, try the next smaller 1317 * one. ip->ip_len has already 1318 * been swapped in icmp_input(). 1319 */ 1320 if (!mtu) 1321 mtu = ip_next_mtu(ip->ip_len, 1322 1); 1323 if (mtu < max(296, V_tcp_minmss 1324 + sizeof(struct tcpiphdr))) 1325 mtu = 0; 1326 if (!mtu) 1327 mtu = V_tcp_mssdflt 1328 + sizeof(struct tcpiphdr); 1329 /* 1330 * Only cache the the MTU if it 1331 * is smaller than the interface 1332 * or route MTU. tcp_mtudisc() 1333 * will do right thing by itself. 1334 */ 1335 if (mtu <= tcp_maxmtu(&inc, NULL)) 1336 tcp_hc_updatemtu(&inc, mtu); 1337 } 1338 1339 inp = (*notify)(inp, inetctlerrmap[cmd]); 1340 } 1341 } 1342 if (inp != NULL) 1343 INP_WUNLOCK(inp); 1344 } else { 1345 bzero(&inc, sizeof(inc)); 1346 inc.inc_fport = th->th_dport; 1347 inc.inc_lport = th->th_sport; 1348 inc.inc_faddr = faddr; 1349 inc.inc_laddr = ip->ip_src; 1350 syncache_unreach(&inc, th); 1351 } 1352 INP_INFO_WUNLOCK(&V_tcbinfo); 1353 } else 1354 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify); 1355 } 1356 1357 #ifdef INET6 1358 void 1359 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1360 { 1361 INIT_VNET_INET(curvnet); 1362 struct tcphdr th; 1363 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1364 struct ip6_hdr *ip6; 1365 struct mbuf *m; 1366 struct ip6ctlparam *ip6cp = NULL; 1367 const struct sockaddr_in6 *sa6_src = NULL; 1368 int off; 1369 struct tcp_portonly { 1370 u_int16_t th_sport; 1371 u_int16_t th_dport; 1372 } *thp; 1373 1374 if (sa->sa_family != AF_INET6 || 1375 sa->sa_len != sizeof(struct sockaddr_in6)) 1376 return; 1377 1378 if (cmd == PRC_MSGSIZE) 1379 notify = tcp_mtudisc; 1380 else if (!PRC_IS_REDIRECT(cmd) && 1381 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1382 return; 1383 /* Source quench is depreciated. */ 1384 else if (cmd == PRC_QUENCH) 1385 return; 1386 1387 /* if the parameter is from icmp6, decode it. */ 1388 if (d != NULL) { 1389 ip6cp = (struct ip6ctlparam *)d; 1390 m = ip6cp->ip6c_m; 1391 ip6 = ip6cp->ip6c_ip6; 1392 off = ip6cp->ip6c_off; 1393 sa6_src = ip6cp->ip6c_src; 1394 } else { 1395 m = NULL; 1396 ip6 = NULL; 1397 off = 0; /* fool gcc */ 1398 sa6_src = &sa6_any; 1399 } 1400 1401 if (ip6 != NULL) { 1402 struct in_conninfo inc; 1403 /* 1404 * XXX: We assume that when IPV6 is non NULL, 1405 * M and OFF are valid. 1406 */ 1407 1408 /* check if we can safely examine src and dst ports */ 1409 if (m->m_pkthdr.len < off + sizeof(*thp)) 1410 return; 1411 1412 bzero(&th, sizeof(th)); 1413 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1414 1415 in6_pcbnotify(&V_tcbinfo, sa, th.th_dport, 1416 (struct sockaddr *)ip6cp->ip6c_src, 1417 th.th_sport, cmd, NULL, notify); 1418 1419 bzero(&inc, sizeof(inc)); 1420 inc.inc_fport = th.th_dport; 1421 inc.inc_lport = th.th_sport; 1422 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1423 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1424 inc.inc_flags |= INC_ISIPV6; 1425 INP_INFO_WLOCK(&V_tcbinfo); 1426 syncache_unreach(&inc, &th); 1427 INP_INFO_WUNLOCK(&V_tcbinfo); 1428 } else 1429 in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src, 1430 0, cmd, NULL, notify); 1431 } 1432 #endif /* INET6 */ 1433 1434 1435 /* 1436 * Following is where TCP initial sequence number generation occurs. 1437 * 1438 * There are two places where we must use initial sequence numbers: 1439 * 1. In SYN-ACK packets. 1440 * 2. In SYN packets. 1441 * 1442 * All ISNs for SYN-ACK packets are generated by the syncache. See 1443 * tcp_syncache.c for details. 1444 * 1445 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1446 * depends on this property. In addition, these ISNs should be 1447 * unguessable so as to prevent connection hijacking. To satisfy 1448 * the requirements of this situation, the algorithm outlined in 1449 * RFC 1948 is used, with only small modifications. 1450 * 1451 * Implementation details: 1452 * 1453 * Time is based off the system timer, and is corrected so that it 1454 * increases by one megabyte per second. This allows for proper 1455 * recycling on high speed LANs while still leaving over an hour 1456 * before rollover. 1457 * 1458 * As reading the *exact* system time is too expensive to be done 1459 * whenever setting up a TCP connection, we increment the time 1460 * offset in two ways. First, a small random positive increment 1461 * is added to isn_offset for each connection that is set up. 1462 * Second, the function tcp_isn_tick fires once per clock tick 1463 * and increments isn_offset as necessary so that sequence numbers 1464 * are incremented at approximately ISN_BYTES_PER_SECOND. The 1465 * random positive increments serve only to ensure that the same 1466 * exact sequence number is never sent out twice (as could otherwise 1467 * happen when a port is recycled in less than the system tick 1468 * interval.) 1469 * 1470 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1471 * between seeding of isn_secret. This is normally set to zero, 1472 * as reseeding should not be necessary. 1473 * 1474 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset, 1475 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In 1476 * general, this means holding an exclusive (write) lock. 1477 */ 1478 1479 #define ISN_BYTES_PER_SECOND 1048576 1480 #define ISN_STATIC_INCREMENT 4096 1481 #define ISN_RANDOM_INCREMENT (4096 - 1) 1482 1483 #ifdef VIMAGE_GLOBALS 1484 static u_char isn_secret[32]; 1485 static int isn_last_reseed; 1486 static u_int32_t isn_offset, isn_offset_old; 1487 #endif 1488 1489 tcp_seq 1490 tcp_new_isn(struct tcpcb *tp) 1491 { 1492 INIT_VNET_INET(tp->t_vnet); 1493 MD5_CTX isn_ctx; 1494 u_int32_t md5_buffer[4]; 1495 tcp_seq new_isn; 1496 1497 INP_WLOCK_ASSERT(tp->t_inpcb); 1498 1499 ISN_LOCK(); 1500 /* Seed if this is the first use, reseed if requested. */ 1501 if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) && 1502 (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz) 1503 < (u_int)ticks))) { 1504 read_random(&V_isn_secret, sizeof(V_isn_secret)); 1505 V_isn_last_reseed = ticks; 1506 } 1507 1508 /* Compute the md5 hash and return the ISN. */ 1509 MD5Init(&isn_ctx); 1510 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1511 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1512 #ifdef INET6 1513 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1514 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1515 sizeof(struct in6_addr)); 1516 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1517 sizeof(struct in6_addr)); 1518 } else 1519 #endif 1520 { 1521 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1522 sizeof(struct in_addr)); 1523 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1524 sizeof(struct in_addr)); 1525 } 1526 MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret)); 1527 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1528 new_isn = (tcp_seq) md5_buffer[0]; 1529 V_isn_offset += ISN_STATIC_INCREMENT + 1530 (arc4random() & ISN_RANDOM_INCREMENT); 1531 new_isn += V_isn_offset; 1532 ISN_UNLOCK(); 1533 return (new_isn); 1534 } 1535 1536 /* 1537 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary 1538 * to keep time flowing at a relatively constant rate. If the random 1539 * increments have already pushed us past the projected offset, do nothing. 1540 */ 1541 static void 1542 tcp_isn_tick(void *xtp) 1543 { 1544 VNET_ITERATOR_DECL(vnet_iter); 1545 u_int32_t projected_offset; 1546 1547 ISN_LOCK(); 1548 VNET_LIST_RLOCK(); 1549 VNET_FOREACH(vnet_iter) { 1550 CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS */ 1551 INIT_VNET_INET(curvnet); 1552 projected_offset = 1553 V_isn_offset_old + ISN_BYTES_PER_SECOND / 100; 1554 1555 if (SEQ_GT(projected_offset, V_isn_offset)) 1556 V_isn_offset = projected_offset; 1557 1558 V_isn_offset_old = V_isn_offset; 1559 CURVNET_RESTORE(); 1560 } 1561 VNET_LIST_RUNLOCK(); 1562 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); 1563 ISN_UNLOCK(); 1564 } 1565 1566 /* 1567 * When a specific ICMP unreachable message is received and the 1568 * connection state is SYN-SENT, drop the connection. This behavior 1569 * is controlled by the icmp_may_rst sysctl. 1570 */ 1571 struct inpcb * 1572 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1573 { 1574 #ifdef INVARIANTS 1575 INIT_VNET_INET(inp->inp_vnet); 1576 #endif 1577 struct tcpcb *tp; 1578 1579 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1580 INP_WLOCK_ASSERT(inp); 1581 1582 if ((inp->inp_vflag & INP_TIMEWAIT) || 1583 (inp->inp_vflag & INP_DROPPED)) 1584 return (inp); 1585 1586 tp = intotcpcb(inp); 1587 if (tp->t_state != TCPS_SYN_SENT) 1588 return (inp); 1589 1590 tp = tcp_drop(tp, errno); 1591 if (tp != NULL) 1592 return (inp); 1593 else 1594 return (NULL); 1595 } 1596 1597 /* 1598 * When `need fragmentation' ICMP is received, update our idea of the MSS 1599 * based on the new value in the route. Also nudge TCP to send something, 1600 * since we know the packet we just sent was dropped. 1601 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1602 */ 1603 struct inpcb * 1604 tcp_mtudisc(struct inpcb *inp, int errno) 1605 { 1606 INIT_VNET_INET(inp->inp_vnet); 1607 struct tcpcb *tp; 1608 struct socket *so; 1609 1610 INP_WLOCK_ASSERT(inp); 1611 if ((inp->inp_vflag & INP_TIMEWAIT) || 1612 (inp->inp_vflag & INP_DROPPED)) 1613 return (inp); 1614 1615 tp = intotcpcb(inp); 1616 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL")); 1617 1618 tcp_mss_update(tp, -1, NULL, NULL); 1619 1620 so = inp->inp_socket; 1621 SOCKBUF_LOCK(&so->so_snd); 1622 /* If the mss is larger than the socket buffer, decrease the mss. */ 1623 if (so->so_snd.sb_hiwat < tp->t_maxseg) 1624 tp->t_maxseg = so->so_snd.sb_hiwat; 1625 SOCKBUF_UNLOCK(&so->so_snd); 1626 1627 V_tcpstat.tcps_mturesent++; 1628 tp->t_rtttime = 0; 1629 tp->snd_nxt = tp->snd_una; 1630 tcp_free_sackholes(tp); 1631 tp->snd_recover = tp->snd_max; 1632 if (tp->t_flags & TF_SACK_PERMIT) 1633 EXIT_FASTRECOVERY(tp); 1634 tcp_output_send(tp); 1635 return (inp); 1636 } 1637 1638 /* 1639 * Look-up the routing entry to the peer of this inpcb. If no route 1640 * is found and it cannot be allocated, then return 0. This routine 1641 * is called by TCP routines that access the rmx structure and by 1642 * tcp_mss_update to get the peer/interface MTU. 1643 */ 1644 u_long 1645 tcp_maxmtu(struct in_conninfo *inc, int *flags) 1646 { 1647 struct route sro; 1648 struct sockaddr_in *dst; 1649 struct ifnet *ifp; 1650 u_long maxmtu = 0; 1651 1652 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1653 1654 bzero(&sro, sizeof(sro)); 1655 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1656 dst = (struct sockaddr_in *)&sro.ro_dst; 1657 dst->sin_family = AF_INET; 1658 dst->sin_len = sizeof(*dst); 1659 dst->sin_addr = inc->inc_faddr; 1660 in_rtalloc_ign(&sro, 0, inc->inc_fibnum); 1661 } 1662 if (sro.ro_rt != NULL) { 1663 ifp = sro.ro_rt->rt_ifp; 1664 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1665 maxmtu = ifp->if_mtu; 1666 else 1667 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1668 1669 /* Report additional interface capabilities. */ 1670 if (flags != NULL) { 1671 if (ifp->if_capenable & IFCAP_TSO4 && 1672 ifp->if_hwassist & CSUM_TSO) 1673 *flags |= CSUM_TSO; 1674 } 1675 RTFREE(sro.ro_rt); 1676 } 1677 return (maxmtu); 1678 } 1679 1680 #ifdef INET6 1681 u_long 1682 tcp_maxmtu6(struct in_conninfo *inc, int *flags) 1683 { 1684 struct route_in6 sro6; 1685 struct ifnet *ifp; 1686 u_long maxmtu = 0; 1687 1688 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1689 1690 bzero(&sro6, sizeof(sro6)); 1691 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1692 sro6.ro_dst.sin6_family = AF_INET6; 1693 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1694 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1695 rtalloc_ign((struct route *)&sro6, 0); 1696 } 1697 if (sro6.ro_rt != NULL) { 1698 ifp = sro6.ro_rt->rt_ifp; 1699 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1700 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1701 else 1702 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1703 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1704 1705 /* Report additional interface capabilities. */ 1706 if (flags != NULL) { 1707 if (ifp->if_capenable & IFCAP_TSO6 && 1708 ifp->if_hwassist & CSUM_TSO) 1709 *flags |= CSUM_TSO; 1710 } 1711 RTFREE(sro6.ro_rt); 1712 } 1713 1714 return (maxmtu); 1715 } 1716 #endif /* INET6 */ 1717 1718 #ifdef IPSEC 1719 /* compute ESP/AH header size for TCP, including outer IP header. */ 1720 size_t 1721 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1722 { 1723 struct inpcb *inp; 1724 struct mbuf *m; 1725 size_t hdrsiz; 1726 struct ip *ip; 1727 #ifdef INET6 1728 struct ip6_hdr *ip6; 1729 #endif 1730 struct tcphdr *th; 1731 1732 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1733 return (0); 1734 MGETHDR(m, M_DONTWAIT, MT_DATA); 1735 if (!m) 1736 return (0); 1737 1738 #ifdef INET6 1739 if ((inp->inp_vflag & INP_IPV6) != 0) { 1740 ip6 = mtod(m, struct ip6_hdr *); 1741 th = (struct tcphdr *)(ip6 + 1); 1742 m->m_pkthdr.len = m->m_len = 1743 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1744 tcpip_fillheaders(inp, ip6, th); 1745 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1746 } else 1747 #endif /* INET6 */ 1748 { 1749 ip = mtod(m, struct ip *); 1750 th = (struct tcphdr *)(ip + 1); 1751 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1752 tcpip_fillheaders(inp, ip, th); 1753 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1754 } 1755 1756 m_free(m); 1757 return (hdrsiz); 1758 } 1759 #endif /* IPSEC */ 1760 1761 /* 1762 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1763 * 1764 * This code attempts to calculate the bandwidth-delay product as a 1765 * means of determining the optimal window size to maximize bandwidth, 1766 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1767 * routers. This code also does a fairly good job keeping RTTs in check 1768 * across slow links like modems. We implement an algorithm which is very 1769 * similar (but not meant to be) TCP/Vegas. The code operates on the 1770 * transmitter side of a TCP connection and so only effects the transmit 1771 * side of the connection. 1772 * 1773 * BACKGROUND: TCP makes no provision for the management of buffer space 1774 * at the end points or at the intermediate routers and switches. A TCP 1775 * stream, whether using NewReno or not, will eventually buffer as 1776 * many packets as it is able and the only reason this typically works is 1777 * due to the fairly small default buffers made available for a connection 1778 * (typicaly 16K or 32K). As machines use larger windows and/or window 1779 * scaling it is now fairly easy for even a single TCP connection to blow-out 1780 * all available buffer space not only on the local interface, but on 1781 * intermediate routers and switches as well. NewReno makes a misguided 1782 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1783 * then backing off, then steadily increasing the window again until another 1784 * failure occurs, ad-infinitum. This results in terrible oscillation that 1785 * is only made worse as network loads increase and the idea of intentionally 1786 * blowing out network buffers is, frankly, a terrible way to manage network 1787 * resources. 1788 * 1789 * It is far better to limit the transmit window prior to the failure 1790 * condition being achieved. There are two general ways to do this: First 1791 * you can 'scan' through different transmit window sizes and locate the 1792 * point where the RTT stops increasing, indicating that you have filled the 1793 * pipe, then scan backwards until you note that RTT stops decreasing, then 1794 * repeat ad-infinitum. This method works in principle but has severe 1795 * implementation issues due to RTT variances, timer granularity, and 1796 * instability in the algorithm which can lead to many false positives and 1797 * create oscillations as well as interact badly with other TCP streams 1798 * implementing the same algorithm. 1799 * 1800 * The second method is to limit the window to the bandwidth delay product 1801 * of the link. This is the method we implement. RTT variances and our 1802 * own manipulation of the congestion window, bwnd, can potentially 1803 * destabilize the algorithm. For this reason we have to stabilize the 1804 * elements used to calculate the window. We do this by using the minimum 1805 * observed RTT, the long term average of the observed bandwidth, and 1806 * by adding two segments worth of slop. It isn't perfect but it is able 1807 * to react to changing conditions and gives us a very stable basis on 1808 * which to extend the algorithm. 1809 */ 1810 void 1811 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1812 { 1813 INIT_VNET_INET(tp->t_vnet); 1814 u_long bw; 1815 u_long bwnd; 1816 int save_ticks; 1817 1818 INP_WLOCK_ASSERT(tp->t_inpcb); 1819 1820 /* 1821 * If inflight_enable is disabled in the middle of a tcp connection, 1822 * make sure snd_bwnd is effectively disabled. 1823 */ 1824 if (V_tcp_inflight_enable == 0 || 1825 tp->t_rttlow < V_tcp_inflight_rttthresh) { 1826 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1827 tp->snd_bandwidth = 0; 1828 return; 1829 } 1830 1831 /* 1832 * Figure out the bandwidth. Due to the tick granularity this 1833 * is a very rough number and it MUST be averaged over a fairly 1834 * long period of time. XXX we need to take into account a link 1835 * that is not using all available bandwidth, but for now our 1836 * slop will ramp us up if this case occurs and the bandwidth later 1837 * increases. 1838 * 1839 * Note: if ticks rollover 'bw' may wind up negative. We must 1840 * effectively reset t_bw_rtttime for this case. 1841 */ 1842 save_ticks = ticks; 1843 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1844 return; 1845 1846 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1847 (save_ticks - tp->t_bw_rtttime); 1848 tp->t_bw_rtttime = save_ticks; 1849 tp->t_bw_rtseq = ack_seq; 1850 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1851 return; 1852 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1853 1854 tp->snd_bandwidth = bw; 1855 1856 /* 1857 * Calculate the semi-static bandwidth delay product, plus two maximal 1858 * segments. The additional slop puts us squarely in the sweet 1859 * spot and also handles the bandwidth run-up case and stabilization. 1860 * Without the slop we could be locking ourselves into a lower 1861 * bandwidth. 1862 * 1863 * Situations Handled: 1864 * (1) Prevents over-queueing of packets on LANs, especially on 1865 * high speed LANs, allowing larger TCP buffers to be 1866 * specified, and also does a good job preventing 1867 * over-queueing of packets over choke points like modems 1868 * (at least for the transmit side). 1869 * 1870 * (2) Is able to handle changing network loads (bandwidth 1871 * drops so bwnd drops, bandwidth increases so bwnd 1872 * increases). 1873 * 1874 * (3) Theoretically should stabilize in the face of multiple 1875 * connections implementing the same algorithm (this may need 1876 * a little work). 1877 * 1878 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1879 * be adjusted with a sysctl but typically only needs to be 1880 * on very slow connections. A value no smaller then 5 1881 * should be used, but only reduce this default if you have 1882 * no other choice. 1883 */ 1884 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1885 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + V_tcp_inflight_stab * tp->t_maxseg / 10; 1886 #undef USERTT 1887 1888 if (tcp_inflight_debug > 0) { 1889 static int ltime; 1890 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1891 ltime = ticks; 1892 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1893 tp, 1894 bw, 1895 tp->t_rttbest, 1896 tp->t_srtt, 1897 bwnd 1898 ); 1899 } 1900 } 1901 if ((long)bwnd < V_tcp_inflight_min) 1902 bwnd = V_tcp_inflight_min; 1903 if (bwnd > V_tcp_inflight_max) 1904 bwnd = V_tcp_inflight_max; 1905 if ((long)bwnd < tp->t_maxseg * 2) 1906 bwnd = tp->t_maxseg * 2; 1907 tp->snd_bwnd = bwnd; 1908 } 1909 1910 #ifdef TCP_SIGNATURE 1911 /* 1912 * Callback function invoked by m_apply() to digest TCP segment data 1913 * contained within an mbuf chain. 1914 */ 1915 static int 1916 tcp_signature_apply(void *fstate, void *data, u_int len) 1917 { 1918 1919 MD5Update(fstate, (u_char *)data, len); 1920 return (0); 1921 } 1922 1923 /* 1924 * Compute TCP-MD5 hash of a TCP segment. (RFC2385) 1925 * 1926 * Parameters: 1927 * m pointer to head of mbuf chain 1928 * _unused 1929 * len length of TCP segment data, excluding options 1930 * optlen length of TCP segment options 1931 * buf pointer to storage for computed MD5 digest 1932 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1933 * 1934 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1935 * When called from tcp_input(), we can be sure that th_sum has been 1936 * zeroed out and verified already. 1937 * 1938 * Return 0 if successful, otherwise return -1. 1939 * 1940 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1941 * search with the destination IP address, and a 'magic SPI' to be 1942 * determined by the application. This is hardcoded elsewhere to 1179 1943 * right now. Another branch of this code exists which uses the SPD to 1944 * specify per-application flows but it is unstable. 1945 */ 1946 int 1947 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen, 1948 u_char *buf, u_int direction) 1949 { 1950 INIT_VNET_IPSEC(curvnet); 1951 union sockaddr_union dst; 1952 struct ippseudo ippseudo; 1953 MD5_CTX ctx; 1954 int doff; 1955 struct ip *ip; 1956 struct ipovly *ipovly; 1957 struct secasvar *sav; 1958 struct tcphdr *th; 1959 #ifdef INET6 1960 struct ip6_hdr *ip6; 1961 struct in6_addr in6; 1962 char ip6buf[INET6_ADDRSTRLEN]; 1963 uint32_t plen; 1964 uint16_t nhdr; 1965 #endif 1966 u_short savecsum; 1967 1968 KASSERT(m != NULL, ("NULL mbuf chain")); 1969 KASSERT(buf != NULL, ("NULL signature pointer")); 1970 1971 /* Extract the destination from the IP header in the mbuf. */ 1972 bzero(&dst, sizeof(union sockaddr_union)); 1973 ip = mtod(m, struct ip *); 1974 #ifdef INET6 1975 ip6 = NULL; /* Make the compiler happy. */ 1976 #endif 1977 switch (ip->ip_v) { 1978 case IPVERSION: 1979 dst.sa.sa_len = sizeof(struct sockaddr_in); 1980 dst.sa.sa_family = AF_INET; 1981 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1982 ip->ip_src : ip->ip_dst; 1983 break; 1984 #ifdef INET6 1985 case (IPV6_VERSION >> 4): 1986 ip6 = mtod(m, struct ip6_hdr *); 1987 dst.sa.sa_len = sizeof(struct sockaddr_in6); 1988 dst.sa.sa_family = AF_INET6; 1989 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ? 1990 ip6->ip6_src : ip6->ip6_dst; 1991 break; 1992 #endif 1993 default: 1994 return (EINVAL); 1995 /* NOTREACHED */ 1996 break; 1997 } 1998 1999 /* Look up an SADB entry which matches the address of the peer. */ 2000 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2001 if (sav == NULL) { 2002 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__, 2003 (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) : 2004 #ifdef INET6 2005 (ip->ip_v == (IPV6_VERSION >> 4)) ? 2006 ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) : 2007 #endif 2008 "(unsupported)")); 2009 return (EINVAL); 2010 } 2011 2012 MD5Init(&ctx); 2013 /* 2014 * Step 1: Update MD5 hash with IP(v6) pseudo-header. 2015 * 2016 * XXX The ippseudo header MUST be digested in network byte order, 2017 * or else we'll fail the regression test. Assume all fields we've 2018 * been doing arithmetic on have been in host byte order. 2019 * XXX One cannot depend on ipovly->ih_len here. When called from 2020 * tcp_output(), the underlying ip_len member has not yet been set. 2021 */ 2022 switch (ip->ip_v) { 2023 case IPVERSION: 2024 ipovly = (struct ipovly *)ip; 2025 ippseudo.ippseudo_src = ipovly->ih_src; 2026 ippseudo.ippseudo_dst = ipovly->ih_dst; 2027 ippseudo.ippseudo_pad = 0; 2028 ippseudo.ippseudo_p = IPPROTO_TCP; 2029 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + 2030 optlen); 2031 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2032 2033 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip)); 2034 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen; 2035 break; 2036 #ifdef INET6 2037 /* 2038 * RFC 2385, 2.0 Proposal 2039 * For IPv6, the pseudo-header is as described in RFC 2460, namely the 2040 * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero- 2041 * extended next header value (to form 32 bits), and 32-bit segment 2042 * length. 2043 * Note: Upper-Layer Packet Length comes before Next Header. 2044 */ 2045 case (IPV6_VERSION >> 4): 2046 in6 = ip6->ip6_src; 2047 in6_clearscope(&in6); 2048 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 2049 in6 = ip6->ip6_dst; 2050 in6_clearscope(&in6); 2051 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr)); 2052 plen = htonl(len + sizeof(struct tcphdr) + optlen); 2053 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t)); 2054 nhdr = 0; 2055 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2056 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2057 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2058 nhdr = IPPROTO_TCP; 2059 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t)); 2060 2061 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr)); 2062 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen; 2063 break; 2064 #endif 2065 default: 2066 return (EINVAL); 2067 /* NOTREACHED */ 2068 break; 2069 } 2070 2071 2072 /* 2073 * Step 2: Update MD5 hash with TCP header, excluding options. 2074 * The TCP checksum must be set to zero. 2075 */ 2076 savecsum = th->th_sum; 2077 th->th_sum = 0; 2078 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2079 th->th_sum = savecsum; 2080 2081 /* 2082 * Step 3: Update MD5 hash with TCP segment data. 2083 * Use m_apply() to avoid an early m_pullup(). 2084 */ 2085 if (len > 0) 2086 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2087 2088 /* 2089 * Step 4: Update MD5 hash with shared secret. 2090 */ 2091 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth)); 2092 MD5Final(buf, &ctx); 2093 2094 key_sa_recordxfer(sav, m); 2095 KEY_FREESAV(&sav); 2096 return (0); 2097 } 2098 #endif /* TCP_SIGNATURE */ 2099 2100 static int 2101 sysctl_drop(SYSCTL_HANDLER_ARGS) 2102 { 2103 INIT_VNET_INET(curvnet); 2104 #ifdef INET6 2105 INIT_VNET_INET6(curvnet); 2106 #endif 2107 /* addrs[0] is a foreign socket, addrs[1] is a local one. */ 2108 struct sockaddr_storage addrs[2]; 2109 struct inpcb *inp; 2110 struct tcpcb *tp; 2111 struct tcptw *tw; 2112 struct sockaddr_in *fin, *lin; 2113 #ifdef INET6 2114 struct sockaddr_in6 *fin6, *lin6; 2115 struct in6_addr f6, l6; 2116 #endif 2117 int error; 2118 2119 inp = NULL; 2120 fin = lin = NULL; 2121 #ifdef INET6 2122 fin6 = lin6 = NULL; 2123 #endif 2124 error = 0; 2125 2126 if (req->oldptr != NULL || req->oldlen != 0) 2127 return (EINVAL); 2128 if (req->newptr == NULL) 2129 return (EPERM); 2130 if (req->newlen < sizeof(addrs)) 2131 return (ENOMEM); 2132 error = SYSCTL_IN(req, &addrs, sizeof(addrs)); 2133 if (error) 2134 return (error); 2135 2136 switch (addrs[0].ss_family) { 2137 #ifdef INET6 2138 case AF_INET6: 2139 fin6 = (struct sockaddr_in6 *)&addrs[0]; 2140 lin6 = (struct sockaddr_in6 *)&addrs[1]; 2141 if (fin6->sin6_len != sizeof(struct sockaddr_in6) || 2142 lin6->sin6_len != sizeof(struct sockaddr_in6)) 2143 return (EINVAL); 2144 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) { 2145 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr)) 2146 return (EINVAL); 2147 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]); 2148 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]); 2149 fin = (struct sockaddr_in *)&addrs[0]; 2150 lin = (struct sockaddr_in *)&addrs[1]; 2151 break; 2152 } 2153 error = sa6_embedscope(fin6, V_ip6_use_defzone); 2154 if (error) 2155 return (error); 2156 error = sa6_embedscope(lin6, V_ip6_use_defzone); 2157 if (error) 2158 return (error); 2159 break; 2160 #endif 2161 case AF_INET: 2162 fin = (struct sockaddr_in *)&addrs[0]; 2163 lin = (struct sockaddr_in *)&addrs[1]; 2164 if (fin->sin_len != sizeof(struct sockaddr_in) || 2165 lin->sin_len != sizeof(struct sockaddr_in)) 2166 return (EINVAL); 2167 break; 2168 default: 2169 return (EINVAL); 2170 } 2171 INP_INFO_WLOCK(&V_tcbinfo); 2172 switch (addrs[0].ss_family) { 2173 #ifdef INET6 2174 case AF_INET6: 2175 inp = in6_pcblookup_hash(&V_tcbinfo, &f6, fin6->sin6_port, 2176 &l6, lin6->sin6_port, 0, NULL); 2177 break; 2178 #endif 2179 case AF_INET: 2180 inp = in_pcblookup_hash(&V_tcbinfo, fin->sin_addr, 2181 fin->sin_port, lin->sin_addr, lin->sin_port, 0, NULL); 2182 break; 2183 } 2184 if (inp != NULL) { 2185 INP_WLOCK(inp); 2186 if (inp->inp_vflag & INP_TIMEWAIT) { 2187 /* 2188 * XXXRW: There currently exists a state where an 2189 * inpcb is present, but its timewait state has been 2190 * discarded. For now, don't allow dropping of this 2191 * type of inpcb. 2192 */ 2193 tw = intotw(inp); 2194 if (tw != NULL) 2195 tcp_twclose(tw, 0); 2196 else 2197 INP_WUNLOCK(inp); 2198 } else if (!(inp->inp_vflag & INP_DROPPED) && 2199 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) { 2200 tp = intotcpcb(inp); 2201 tp = tcp_drop(tp, ECONNABORTED); 2202 if (tp != NULL) 2203 INP_WUNLOCK(inp); 2204 } else 2205 INP_WUNLOCK(inp); 2206 } else 2207 error = ESRCH; 2208 INP_INFO_WUNLOCK(&V_tcbinfo); 2209 return (error); 2210 } 2211 2212 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop, 2213 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL, 2214 0, sysctl_drop, "", "Drop TCP connection"); 2215 2216 /* 2217 * Generate a standardized TCP log line for use throughout the 2218 * tcp subsystem. Memory allocation is done with M_NOWAIT to 2219 * allow use in the interrupt context. 2220 * 2221 * NB: The caller MUST free(s, M_TCPLOG) the returned string. 2222 * NB: The function may return NULL if memory allocation failed. 2223 * 2224 * Due to header inclusion and ordering limitations the struct ip 2225 * and ip6_hdr pointers have to be passed as void pointers. 2226 */ 2227 char * 2228 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, 2229 const void *ip6hdr) 2230 { 2231 char *s, *sp; 2232 size_t size; 2233 struct ip *ip; 2234 #ifdef INET6 2235 const struct ip6_hdr *ip6; 2236 2237 ip6 = (const struct ip6_hdr *)ip6hdr; 2238 #endif /* INET6 */ 2239 ip = (struct ip *)ip4hdr; 2240 2241 /* 2242 * The log line looks like this: 2243 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>" 2244 */ 2245 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") + 2246 sizeof(PRINT_TH_FLAGS) + 1 + 2247 #ifdef INET6 2248 2 * INET6_ADDRSTRLEN; 2249 #else 2250 2 * INET_ADDRSTRLEN; 2251 #endif /* INET6 */ 2252 2253 /* Is logging enabled? */ 2254 if (tcp_log_debug == 0 && tcp_log_in_vain == 0) 2255 return (NULL); 2256 2257 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT); 2258 if (s == NULL) 2259 return (NULL); 2260 2261 strcat(s, "TCP: ["); 2262 sp = s + strlen(s); 2263 2264 if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) { 2265 inet_ntoa_r(inc->inc_faddr, sp); 2266 sp = s + strlen(s); 2267 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2268 sp = s + strlen(s); 2269 inet_ntoa_r(inc->inc_laddr, sp); 2270 sp = s + strlen(s); 2271 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2272 #ifdef INET6 2273 } else if (inc) { 2274 ip6_sprintf(sp, &inc->inc6_faddr); 2275 sp = s + strlen(s); 2276 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport)); 2277 sp = s + strlen(s); 2278 ip6_sprintf(sp, &inc->inc6_laddr); 2279 sp = s + strlen(s); 2280 sprintf(sp, "]:%i", ntohs(inc->inc_lport)); 2281 } else if (ip6 && th) { 2282 ip6_sprintf(sp, &ip6->ip6_src); 2283 sp = s + strlen(s); 2284 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2285 sp = s + strlen(s); 2286 ip6_sprintf(sp, &ip6->ip6_dst); 2287 sp = s + strlen(s); 2288 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2289 #endif /* INET6 */ 2290 } else if (ip && th) { 2291 inet_ntoa_r(ip->ip_src, sp); 2292 sp = s + strlen(s); 2293 sprintf(sp, "]:%i to [", ntohs(th->th_sport)); 2294 sp = s + strlen(s); 2295 inet_ntoa_r(ip->ip_dst, sp); 2296 sp = s + strlen(s); 2297 sprintf(sp, "]:%i", ntohs(th->th_dport)); 2298 } else { 2299 free(s, M_TCPLOG); 2300 return (NULL); 2301 } 2302 sp = s + strlen(s); 2303 if (th) 2304 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS); 2305 if (*(s + size - 1) != '\0') 2306 panic("%s: string too long", __func__); 2307 return (s); 2308 } 2309