sys/netinet/tcp_subr.c

   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  * 3. 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_tcpdebug.h"
  40
  41 #include <sys/param.h>
  42 #include <sys/systm.h>
  43 #include <sys/callout.h>
  44 #include <sys/eventhandler.h>
  45 #ifdef TCP_HHOOK
  46 #include <sys/hhook.h>
  47 #endif
  48 #include <sys/kernel.h>
  49 #ifdef TCP_HHOOK
  50 #include <sys/khelp.h>
  51 #endif
  52 #include <sys/sysctl.h>
  53 #include <sys/jail.h>
  54 #include <sys/malloc.h>
  55 #include <sys/refcount.h>
  56 #include <sys/mbuf.h>
  57 #ifdef INET6
  58 #include <sys/domain.h>
  59 #endif
  60 #include <sys/priv.h>
  61 #include <sys/proc.h>
  62 #include <sys/sdt.h>
  63 #include <sys/socket.h>
  64 #include <sys/socketvar.h>
  65 #include <sys/protosw.h>
  66 #include <sys/random.h>
  67
  68 #include <vm/uma.h>
  69
  70 #include <net/route.h>
  71 #include <net/if.h>
  72 #include <net/if_var.h>
  73 #include <net/vnet.h>
  74
  75 #include <netinet/in.h>
  76 #include <netinet/in_fib.h>
  77 #include <netinet/in_kdtrace.h>
  78 #include <netinet/in_pcb.h>
  79 #include <netinet/in_systm.h>
  80 #include <netinet/in_var.h>
  81 #include <netinet/ip.h>
  82 #include <netinet/ip_icmp.h>
  83 #include <netinet/ip_var.h>
  84 #ifdef INET6
  85 #include <netinet/icmp6.h>
  86 #include <netinet/ip6.h>
  87 #include <netinet6/in6_fib.h>
  88 #include <netinet6/in6_pcb.h>
  89 #include <netinet6/ip6_var.h>
  90 #include <netinet6/scope6_var.h>
  91 #include <netinet6/nd6.h>
  92 #endif
  93
  94 #ifdef TCP_RFC7413
  95 #include <netinet/tcp_fastopen.h>
  96 #endif
  97 #include <netinet/tcp.h>
  98 #include <netinet/tcp_fsm.h>
  99 #include <netinet/tcp_seq.h>
 100 #include <netinet/tcp_timer.h>
 101 #include <netinet/tcp_var.h>
 102 #include <netinet/tcp_syncache.h>
 103 #include <netinet/cc/cc.h>
 104 #ifdef INET6
 105 #include <netinet6/tcp6_var.h>
 106 #endif
 107 #include <netinet/tcpip.h>
 108 #ifdef TCPPCAP
 109 #include <netinet/tcp_pcap.h>
 110 #endif
 111 #ifdef TCPDEBUG
 112 #include <netinet/tcp_debug.h>
 113 #endif
 114 #ifdef INET6
 115 #include <netinet6/ip6protosw.h>
 116 #endif
 117 #ifdef TCP_OFFLOAD
 118 #include <netinet/tcp_offload.h>
 119 #endif
 120
 121 #include <netipsec/ipsec_support.h>
 122
 123 #include <machine/in_cksum.h>
 124 #include <sys/md5.h>
 125
 126 #include <security/mac/mac_framework.h>
 127
 128 VNET_DEFINE(int, tcp_mssdflt) = TCP_MSS;
 129 #ifdef INET6
 130 VNET_DEFINE(int, tcp_v6mssdflt) = TCP6_MSS;
 131 #endif
 132
 133 struct rwlock tcp_function_lock;
 134
 135 static int
 136 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS)
 137 {
 138         int error, new;
 139
 140         new = V_tcp_mssdflt;
 141         error = sysctl_handle_int(oidp, &new, 0, req);
 142         if (error == 0 && req->newptr) {
 143                 if (new < TCP_MINMSS)
 144                         error = EINVAL;
 145                 else
 146                         V_tcp_mssdflt = new;
 147         }
 148         return (error);
 149 }
 150
 151 SYSCTL_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
 152     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, &VNET_NAME(tcp_mssdflt), 0,
 153     &sysctl_net_inet_tcp_mss_check, "I",
 154     "Default TCP Maximum Segment Size");
 155
 156 #ifdef INET6
 157 static int
 158 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS)
 159 {
 160         int error, new;
 161
 162         new = V_tcp_v6mssdflt;
 163         error = sysctl_handle_int(oidp, &new, 0, req);
 164         if (error == 0 && req->newptr) {
 165                 if (new < TCP_MINMSS)
 166                         error = EINVAL;
 167                 else
 168                         V_tcp_v6mssdflt = new;
 169         }
 170         return (error);
 171 }
 172
 173 SYSCTL_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
 174     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, &VNET_NAME(tcp_v6mssdflt), 0,
 175     &sysctl_net_inet_tcp_mss_v6_check, "I",
 176    "Default TCP Maximum Segment Size for IPv6");
 177 #endif /* INET6 */
 178
 179 /*
 180  * Minimum MSS we accept and use. This prevents DoS attacks where
 181  * we are forced to a ridiculous low MSS like 20 and send hundreds
 182  * of packets instead of one. The effect scales with the available
 183  * bandwidth and quickly saturates the CPU and network interface
 184  * with packet generation and sending. Set to zero to disable MINMSS
 185  * checking. This setting prevents us from sending too small packets.
 186  */
 187 VNET_DEFINE(int, tcp_minmss) = TCP_MINMSS;
 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_VNET | CTLFLAG_RW,
 189      &VNET_NAME(tcp_minmss), 0,
 190     "Minimum TCP Maximum Segment Size");
 191
 192 VNET_DEFINE(int, tcp_do_rfc1323) = 1;
 193 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_VNET | CTLFLAG_RW,
 194     &VNET_NAME(tcp_do_rfc1323), 0,
 195     "Enable rfc1323 (high performance TCP) extensions");
 196
 197 static int      tcp_log_debug = 0;
 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
 199     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
 200
 201 static int      tcp_tcbhashsize;
 202 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 203     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
 204
 205 static int      do_tcpdrain = 1;
 206 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
 207     "Enable tcp_drain routine for extra help when low on mbufs");
 208
 209 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_VNET | CTLFLAG_RD,
 210     &VNET_NAME(tcbinfo.ipi_count), 0, "Number of active PCBs");
 211
 212 static VNET_DEFINE(int, icmp_may_rst) = 1;
 213 #define V_icmp_may_rst                  VNET(icmp_may_rst)
 214 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_VNET | CTLFLAG_RW,
 215     &VNET_NAME(icmp_may_rst), 0,
 216     "Certain ICMP unreachable messages may abort connections in SYN_SENT");
 217
 218 static VNET_DEFINE(int, tcp_isn_reseed_interval) = 0;
 219 #define V_tcp_isn_reseed_interval       VNET(tcp_isn_reseed_interval)
 220 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_VNET | CTLFLAG_RW,
 221     &VNET_NAME(tcp_isn_reseed_interval), 0,
 222     "Seconds between reseeding of ISN secret");
 223
 224 static int      tcp_soreceive_stream;
 225 SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
 226     &tcp_soreceive_stream, 0, "Using soreceive_stream for TCP sockets");
 227
 228 VNET_DEFINE(uma_zone_t, sack_hole_zone);
 229 #define V_sack_hole_zone                VNET(sack_hole_zone)
 230
 231 #ifdef TCP_HHOOK
 232 VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
 233 #endif
 234
 235 static struct inpcb *tcp_notify(struct inpcb *, int);
 236 static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
 237 static void tcp_mtudisc(struct inpcb *, int);
 238 static char *   tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
 239                     void *ip4hdr, const void *ip6hdr);
 240
 241
 242 static struct tcp_function_block tcp_def_funcblk = {
 243         "default",
 244         tcp_output,
 245         tcp_do_segment,
 246         tcp_default_ctloutput,
 247         NULL,
 248         NULL,
 249         NULL,
 250         NULL,
 251         NULL,
 252         NULL,
 253         0,
 254         0
 255 };
 256
 257 int t_functions_inited = 0;
 258 struct tcp_funchead t_functions;
 259 static struct tcp_function_block *tcp_func_set_ptr = &tcp_def_funcblk;
 260
 261 static void
 262 init_tcp_functions(void)
 263 {
 264         if (t_functions_inited == 0) {
 265                 TAILQ_INIT(&t_functions);
 266                 rw_init_flags(&tcp_function_lock, "tcp_func_lock" , 0);
 267                 t_functions_inited = 1;
 268         }
 269 }
 270
 271 static struct tcp_function_block *
 272 find_tcp_functions_locked(struct tcp_function_set *fs)
 273 {
 274         struct tcp_function *f;
 275         struct tcp_function_block *blk=NULL;
 276
 277         TAILQ_FOREACH(f, &t_functions, tf_next) {
 278                 if (strcmp(f->tf_fb->tfb_tcp_block_name, fs->function_set_name) == 0) {
 279                         blk = f->tf_fb;
 280                         break;
 281                 }
 282         }
 283         return(blk);
 284 }
 285
 286 static struct tcp_function_block *
 287 find_tcp_fb_locked(struct tcp_function_block *blk, struct tcp_function **s)
 288 {
 289         struct tcp_function_block *rblk=NULL;
 290         struct tcp_function *f;
 291
 292         TAILQ_FOREACH(f, &t_functions, tf_next) {
 293                 if (f->tf_fb == blk) {
 294                         rblk = blk;
 295                         if (s) {
 296                                 *s = f;
 297                         }
 298                         break;
 299                 }
 300         }
 301         return (rblk);
 302 }
 303
 304 struct tcp_function_block *
 305 find_and_ref_tcp_functions(struct tcp_function_set *fs)
 306 {
 307         struct tcp_function_block *blk;
 308
 309         rw_rlock(&tcp_function_lock);
 310         blk = find_tcp_functions_locked(fs);
 311         if (blk)
 312                 refcount_acquire(&blk->tfb_refcnt);
 313         rw_runlock(&tcp_function_lock);
 314         return(blk);
 315 }
 316
 317 struct tcp_function_block *
 318 find_and_ref_tcp_fb(struct tcp_function_block *blk)
 319 {
 320         struct tcp_function_block *rblk;
 321
 322         rw_rlock(&tcp_function_lock);
 323         rblk = find_tcp_fb_locked(blk, NULL);
 324         if (rblk)
 325                 refcount_acquire(&rblk->tfb_refcnt);
 326         rw_runlock(&tcp_function_lock);
 327         return(rblk);
 328 }
 329
 330
 331 static int
 332 sysctl_net_inet_default_tcp_functions(SYSCTL_HANDLER_ARGS)
 333 {
 334         int error=ENOENT;
 335         struct tcp_function_set fs;
 336         struct tcp_function_block *blk;
 337
 338         memset(&fs, 0, sizeof(fs));
 339         rw_rlock(&tcp_function_lock);
 340         blk = find_tcp_fb_locked(tcp_func_set_ptr, NULL);
 341         if (blk) {
 342                 /* Found him */
 343                 strcpy(fs.function_set_name, blk->tfb_tcp_block_name);
 344                 fs.pcbcnt = blk->tfb_refcnt;
 345         }
 346         rw_runlock(&tcp_function_lock);
 347         error = sysctl_handle_string(oidp, fs.function_set_name,
 348                                      sizeof(fs.function_set_name), req);
 349
 350         /* Check for error or no change */
 351         if (error != 0 || req->newptr == NULL)
 352                 return(error);
 353
 354         rw_wlock(&tcp_function_lock);
 355         blk = find_tcp_functions_locked(&fs);
 356         if ((blk == NULL) ||
 357             (blk->tfb_flags & TCP_FUNC_BEING_REMOVED)) {
 358                 error = ENOENT;
 359                 goto done;
 360         }
 361         tcp_func_set_ptr = blk;
 362 done:
 363         rw_wunlock(&tcp_function_lock);
 364         return (error);
 365 }
 366
 367 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_default,
 368             CTLTYPE_STRING | CTLFLAG_RW,
 369             NULL, 0, sysctl_net_inet_default_tcp_functions, "A",
 370             "Set/get the default TCP functions");
 371
 372 static int
 373 sysctl_net_inet_list_available(SYSCTL_HANDLER_ARGS)
 374 {
 375         int error, cnt, linesz;
 376         struct tcp_function *f;
 377         char *buffer, *cp;
 378         size_t bufsz, outsz;
 379
 380         cnt = 0;
 381         rw_rlock(&tcp_function_lock);
 382         TAILQ_FOREACH(f, &t_functions, tf_next) {
 383                 cnt++;
 384         }
 385         rw_runlock(&tcp_function_lock);
 386
 387         bufsz = (cnt+2) * (TCP_FUNCTION_NAME_LEN_MAX + 12) + 1;
 388         buffer = malloc(bufsz, M_TEMP, M_WAITOK);
 389
 390         error = 0;
 391         cp = buffer;
 392
 393         linesz = snprintf(cp, bufsz, "\n%-32s%c %s\n", "Stack", 'D', "PCB count");
 394         cp += linesz;
 395         bufsz -= linesz;
 396         outsz = linesz;
 397
 398         rw_rlock(&tcp_function_lock);
 399         TAILQ_FOREACH(f, &t_functions, tf_next) {
 400                 linesz = snprintf(cp, bufsz, "%-32s%c %u\n",
 401                     f->tf_fb->tfb_tcp_block_name,
 402                     (f->tf_fb == tcp_func_set_ptr) ? '*' : ' ',
 403                     f->tf_fb->tfb_refcnt);
 404                 if (linesz >= bufsz) {
 405                         error = EOVERFLOW;
 406                         break;
 407                 }
 408                 cp += linesz;
 409                 bufsz -= linesz;
 410                 outsz += linesz;
 411         }
 412         rw_runlock(&tcp_function_lock);
 413         if (error == 0)
 414                 error = sysctl_handle_string(oidp, buffer, outsz + 1, req);
 415         free(buffer, M_TEMP);
 416         return (error);
 417 }
 418
 419 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_available,
 420             CTLTYPE_STRING|CTLFLAG_RD,
 421             NULL, 0, sysctl_net_inet_list_available, "A",
 422             "list available TCP Function sets");
 423
 424 /*
 425  * Target size of TCP PCB hash tables. Must be a power of two.
 426  *
 427  * Note that this can be overridden by the kernel environment
 428  * variable net.inet.tcp.tcbhashsize
 429  */
 430 #ifndef TCBHASHSIZE
 431 #define TCBHASHSIZE     0
 432 #endif
 433
 434 /*
 435  * XXX
 436  * Callouts should be moved into struct tcp directly.  They are currently
 437  * separate because the tcpcb structure is exported to userland for sysctl
 438  * parsing purposes, which do not know about callouts.
 439  */
 440 struct tcpcb_mem {
 441         struct  tcpcb           tcb;
 442         struct  tcp_timer       tt;
 443         struct  cc_var          ccv;
 444 #ifdef TCP_HHOOK
 445         struct  osd             osd;
 446 #endif
 447 };
 448
 449 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
 450 #define V_tcpcb_zone                    VNET(tcpcb_zone)
 451
 452 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
 453 MALLOC_DEFINE(M_TCPFUNCTIONS, "tcpfunc", "TCP function set memory");
 454
 455 static struct mtx isn_mtx;
 456
 457 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
 458 #define ISN_LOCK()      mtx_lock(&isn_mtx)
 459 #define ISN_UNLOCK()    mtx_unlock(&isn_mtx)
 460
 461 /*
 462  * TCP initialization.
 463  */
 464 static void
 465 tcp_zone_change(void *tag)
 466 {
 467
 468         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
 469         uma_zone_set_max(V_tcpcb_zone, maxsockets);
 470         tcp_tw_zone_change();
 471 }
 472
 473 static int
 474 tcp_inpcb_init(void *mem, int size, int flags)
 475 {
 476         struct inpcb *inp = mem;
 477
 478         INP_LOCK_INIT(inp, "inp", "tcpinp");
 479         return (0);
 480 }
 481
 482 /*
 483  * Take a value and get the next power of 2 that doesn't overflow.
 484  * Used to size the tcp_inpcb hash buckets.
 485  */
 486 static int
 487 maketcp_hashsize(int size)
 488 {
 489         int hashsize;
 490
 491         /*
 492          * auto tune.
 493          * get the next power of 2 higher than maxsockets.
 494          */
 495         hashsize = 1 << fls(size);
 496         /* catch overflow, and just go one power of 2 smaller */
 497         if (hashsize < size) {
 498                 hashsize = 1 << (fls(size) - 1);
 499         }
 500         return (hashsize);
 501 }
 502
 503 int
 504 register_tcp_functions(struct tcp_function_block *blk, int wait)
 505 {
 506         struct tcp_function_block *lblk;
 507         struct tcp_function *n;
 508         struct tcp_function_set fs;
 509
 510         if (t_functions_inited == 0) {
 511                 init_tcp_functions();
 512         }
 513         if ((blk->tfb_tcp_output == NULL) ||
 514             (blk->tfb_tcp_do_segment == NULL) ||
 515             (blk->tfb_tcp_ctloutput == NULL) ||
 516             (strlen(blk->tfb_tcp_block_name) == 0)) {
 517                 /*
 518                  * These functions are required and you
 519                  * need a name.
 520                  */
 521                 return (EINVAL);
 522         }
 523         if (blk->tfb_tcp_timer_stop_all ||
 524             blk->tfb_tcp_timer_activate ||
 525             blk->tfb_tcp_timer_active ||
 526             blk->tfb_tcp_timer_stop) {
 527                 /*
 528                  * If you define one timer function you
 529                  * must have them all.
 530                  */
 531                 if ((blk->tfb_tcp_timer_stop_all == NULL) ||
 532                     (blk->tfb_tcp_timer_activate == NULL) ||
 533                     (blk->tfb_tcp_timer_active == NULL) ||
 534                     (blk->tfb_tcp_timer_stop == NULL)) {
 535                         return (EINVAL);
 536                 }
 537         }
 538         n = malloc(sizeof(struct tcp_function), M_TCPFUNCTIONS, wait);
 539         if (n == NULL) {
 540                 return (ENOMEM);
 541         }
 542         n->tf_fb = blk;
 543         strcpy(fs.function_set_name, blk->tfb_tcp_block_name);
 544         rw_wlock(&tcp_function_lock);
 545         lblk = find_tcp_functions_locked(&fs);
 546         if (lblk) {
 547                 /* Duplicate name space not allowed */
 548                 rw_wunlock(&tcp_function_lock);
 549                 free(n, M_TCPFUNCTIONS);
 550                 return (EALREADY);
 551         }
 552         refcount_init(&blk->tfb_refcnt, 0);
 553         blk->tfb_flags = 0;
 554         TAILQ_INSERT_TAIL(&t_functions, n, tf_next);
 555         rw_wunlock(&tcp_function_lock);
 556         return(0);
 557 }
 558
 559 int
 560 deregister_tcp_functions(struct tcp_function_block *blk)
 561 {
 562         struct tcp_function_block *lblk;
 563         struct tcp_function *f;
 564         int error=ENOENT;
 565
 566         if (strcmp(blk->tfb_tcp_block_name, "default") == 0) {
 567                 /* You can't un-register the default */
 568                 return (EPERM);
 569         }
 570         rw_wlock(&tcp_function_lock);
 571         if (blk == tcp_func_set_ptr) {
 572                 /* You can't free the current default */
 573                 rw_wunlock(&tcp_function_lock);
 574                 return (EBUSY);
 575         }
 576         if (blk->tfb_refcnt) {
 577                 /* Still tcb attached, mark it. */
 578                 blk->tfb_flags |= TCP_FUNC_BEING_REMOVED;
 579                 rw_wunlock(&tcp_function_lock);
 580                 return (EBUSY);
 581         }
 582         lblk = find_tcp_fb_locked(blk, &f);
 583         if (lblk) {
 584                 /* Found */
 585                 TAILQ_REMOVE(&t_functions, f, tf_next);
 586                 f->tf_fb = NULL;
 587                 free(f, M_TCPFUNCTIONS);
 588                 error = 0;
 589         }
 590         rw_wunlock(&tcp_function_lock);
 591         return (error);
 592 }
 593
 594 void
 595 tcp_init(void)
 596 {
 597         const char *tcbhash_tuneable;
 598         int hashsize;
 599
 600         tcbhash_tuneable = "net.inet.tcp.tcbhashsize";
 601
 602 #ifdef TCP_HHOOK
 603         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
 604             &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
 605                 printf("%s: WARNING: unable to register helper hook\n", __func__);
 606         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
 607             &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
 608                 printf("%s: WARNING: unable to register helper hook\n", __func__);
 609 #endif
 610         hashsize = TCBHASHSIZE;
 611         TUNABLE_INT_FETCH(tcbhash_tuneable, &hashsize);
 612         if (hashsize == 0) {
 613                 /*
 614                  * Auto tune the hash size based on maxsockets.
 615                  * A perfect hash would have a 1:1 mapping
 616                  * (hashsize = maxsockets) however it's been
 617                  * suggested that O(2) average is better.
 618                  */
 619                 hashsize = maketcp_hashsize(maxsockets / 4);
 620                 /*
 621                  * Our historical default is 512,
 622                  * do not autotune lower than this.
 623                  */
 624                 if (hashsize < 512)
 625                         hashsize = 512;
 626                 if (bootverbose && IS_DEFAULT_VNET(curvnet))
 627                         printf("%s: %s auto tuned to %d\n", __func__,
 628                             tcbhash_tuneable, hashsize);
 629         }
 630         /*
 631          * We require a hashsize to be a power of two.
 632          * Previously if it was not a power of two we would just reset it
 633          * back to 512, which could be a nasty surprise if you did not notice
 634          * the error message.
 635          * Instead what we do is clip it to the closest power of two lower
 636          * than the specified hash value.
 637          */
 638         if (!powerof2(hashsize)) {
 639                 int oldhashsize = hashsize;
 640
 641                 hashsize = maketcp_hashsize(hashsize);
 642                 /* prevent absurdly low value */
 643                 if (hashsize < 16)
 644                         hashsize = 16;
 645                 printf("%s: WARNING: TCB hash size not a power of 2, "
 646                     "clipped from %d to %d.\n", __func__, oldhashsize,
 647                     hashsize);
 648         }
 649         in_pcbinfo_init(&V_tcbinfo, "tcp", &V_tcb, hashsize, hashsize,
 650             "tcp_inpcb", tcp_inpcb_init, NULL, 0, IPI_HASHFIELDS_4TUPLE);
 651
 652         /*
 653          * These have to be type stable for the benefit of the timers.
 654          */
 655         V_tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
 656             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 657         uma_zone_set_max(V_tcpcb_zone, maxsockets);
 658         uma_zone_set_warning(V_tcpcb_zone, "kern.ipc.maxsockets limit reached");
 659
 660         tcp_tw_init();
 661         syncache_init();
 662         tcp_hc_init();
 663
 664         TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
 665         V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
 666             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 667
 668 #ifdef TCP_RFC7413
 669         tcp_fastopen_init();
 670 #endif
 671
 672         /* Skip initialization of globals for non-default instances. */
 673         if (!IS_DEFAULT_VNET(curvnet))
 674                 return;
 675
 676         tcp_reass_global_init();
 677
 678         /* XXX virtualize those bellow? */
 679         tcp_delacktime = TCPTV_DELACK;
 680         tcp_keepinit = TCPTV_KEEP_INIT;
 681         tcp_keepidle = TCPTV_KEEP_IDLE;
 682         tcp_keepintvl = TCPTV_KEEPINTVL;
 683         tcp_maxpersistidle = TCPTV_KEEP_IDLE;
 684         tcp_msl = TCPTV_MSL;
 685         tcp_rexmit_min = TCPTV_MIN;
 686         if (tcp_rexmit_min < 1)
 687                 tcp_rexmit_min = 1;
 688         tcp_persmin = TCPTV_PERSMIN;
 689         tcp_persmax = TCPTV_PERSMAX;
 690         tcp_rexmit_slop = TCPTV_CPU_VAR;
 691         tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
 692         tcp_tcbhashsize = hashsize;
 693         /* Setup the tcp function block list */
 694         init_tcp_functions();
 695         register_tcp_functions(&tcp_def_funcblk, M_WAITOK);
 696
 697         if (tcp_soreceive_stream) {
 698 #ifdef INET
 699                 tcp_usrreqs.pru_soreceive = soreceive_stream;
 700 #endif
 701 #ifdef INET6
 702                 tcp6_usrreqs.pru_soreceive = soreceive_stream;
 703 #endif /* INET6 */
 704         }
 705
 706 #ifdef INET6
 707 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
 708 #else /* INET6 */
 709 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
 710 #endif /* INET6 */
 711         if (max_protohdr < TCP_MINPROTOHDR)
 712                 max_protohdr = TCP_MINPROTOHDR;
 713         if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
 714                 panic("tcp_init");
 715 #undef TCP_MINPROTOHDR
 716
 717         ISN_LOCK_INIT();
 718         EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
 719                 SHUTDOWN_PRI_DEFAULT);
 720         EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
 721                 EVENTHANDLER_PRI_ANY);
 722 #ifdef TCPPCAP
 723         tcp_pcap_init();
 724 #endif
 725 }
 726
 727 #ifdef VIMAGE
 728 static void
 729 tcp_destroy(void *unused __unused)
 730 {
 731         int n;
 732 #ifdef TCP_HHOOK
 733         int error;
 734 #endif
 735
 736         /*
 737          * All our processes are gone, all our sockets should be cleaned
 738          * up, which means, we should be past the tcp_discardcb() calls.
 739          * Sleep to let all tcpcb timers really disappear and cleanup.
 740          */
 741         for (;;) {
 742                 INP_LIST_RLOCK(&V_tcbinfo);
 743                 n = V_tcbinfo.ipi_count;
 744                 INP_LIST_RUNLOCK(&V_tcbinfo);
 745                 if (n == 0)
 746                         break;
 747                 pause("tcpdes", hz / 10);
 748         }
 749         tcp_hc_destroy();
 750         syncache_destroy();
 751         tcp_tw_destroy();
 752         in_pcbinfo_destroy(&V_tcbinfo);
 753         /* tcp_discardcb() clears the sack_holes up. */
 754         uma_zdestroy(V_sack_hole_zone);
 755         uma_zdestroy(V_tcpcb_zone);
 756
 757 #ifdef TCP_RFC7413
 758         /*
 759          * Cannot free the zone until all tcpcbs are released as we attach
 760          * the allocations to them.
 761          */
 762         tcp_fastopen_destroy();
 763 #endif
 764
 765 #ifdef TCP_HHOOK
 766         error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_IN]);
 767         if (error != 0) {
 768                 printf("%s: WARNING: unable to deregister helper hook "
 769                     "type=%d, id=%d: error %d returned\n", __func__,
 770                     HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN, error);
 771         }
 772         error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_OUT]);
 773         if (error != 0) {
 774                 printf("%s: WARNING: unable to deregister helper hook "
 775                     "type=%d, id=%d: error %d returned\n", __func__,
 776                     HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT, error);
 777         }
 778 #endif
 779 }
 780 VNET_SYSUNINIT(tcp, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH, tcp_destroy, NULL);
 781 #endif
 782
 783 void
 784 tcp_fini(void *xtp)
 785 {
 786
 787 }
 788
 789 /*
 790  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
 791  * tcp_template used to store this data in mbufs, but we now recopy it out
 792  * of the tcpcb each time to conserve mbufs.
 793  */
 794 void
 795 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
 796 {
 797         struct tcphdr *th = (struct tcphdr *)tcp_ptr;
 798
 799         INP_WLOCK_ASSERT(inp);
 800
 801 #ifdef INET6
 802         if ((inp->inp_vflag & INP_IPV6) != 0) {
 803                 struct ip6_hdr *ip6;
 804
 805                 ip6 = (struct ip6_hdr *)ip_ptr;
 806                 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
 807                         (inp->inp_flow & IPV6_FLOWINFO_MASK);
 808                 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
 809                         (IPV6_VERSION & IPV6_VERSION_MASK);
 810                 ip6->ip6_nxt = IPPROTO_TCP;
 811                 ip6->ip6_plen = htons(sizeof(struct tcphdr));
 812                 ip6->ip6_src = inp->in6p_laddr;
 813                 ip6->ip6_dst = inp->in6p_faddr;
 814         }
 815 #endif /* INET6 */
 816 #if defined(INET6) && defined(INET)
 817         else
 818 #endif
 819 #ifdef INET
 820         {
 821                 struct ip *ip;
 822
 823                 ip = (struct ip *)ip_ptr;
 824                 ip->ip_v = IPVERSION;
 825                 ip->ip_hl = 5;
 826                 ip->ip_tos = inp->inp_ip_tos;
 827                 ip->ip_len = 0;
 828                 ip->ip_id = 0;
 829                 ip->ip_off = 0;
 830                 ip->ip_ttl = inp->inp_ip_ttl;
 831                 ip->ip_sum = 0;
 832                 ip->ip_p = IPPROTO_TCP;
 833                 ip->ip_src = inp->inp_laddr;
 834                 ip->ip_dst = inp->inp_faddr;
 835         }
 836 #endif /* INET */
 837         th->th_sport = inp->inp_lport;
 838         th->th_dport = inp->inp_fport;
 839         th->th_seq = 0;
 840         th->th_ack = 0;
 841         th->th_x2 = 0;
 842         th->th_off = 5;
 843         th->th_flags = 0;
 844         th->th_win = 0;
 845         th->th_urp = 0;
 846         th->th_sum = 0;         /* in_pseudo() is called later for ipv4 */
 847 }
 848
 849 /*
 850  * Create template to be used to send tcp packets on a connection.
 851  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
 852  * use for this function is in keepalives, which use tcp_respond.
 853  */
 854 struct tcptemp *
 855 tcpip_maketemplate(struct inpcb *inp)
 856 {
 857         struct tcptemp *t;
 858
 859         t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
 860         if (t == NULL)
 861                 return (NULL);
 862         tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t);
 863         return (t);
 864 }
 865
 866 /*
 867  * Send a single message to the TCP at address specified by
 868  * the given TCP/IP header.  If m == NULL, then we make a copy
 869  * of the tcpiphdr at th and send directly to the addressed host.
 870  * This is used to force keep alive messages out using the TCP
 871  * template for a connection.  If flags are given then we send
 872  * a message back to the TCP which originated the segment th,
 873  * and discard the mbuf containing it and any other attached mbufs.
 874  *
 875  * In any case the ack and sequence number of the transmitted
 876  * segment are as specified by the parameters.
 877  *
 878  * NOTE: If m != NULL, then th must point to *inside* the mbuf.
 879  */
 880 void
 881 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
 882     tcp_seq ack, tcp_seq seq, int flags)
 883 {
 884         struct tcpopt to;
 885         struct inpcb *inp;
 886         struct ip *ip;
 887         struct mbuf *optm;
 888         struct tcphdr *nth;
 889         u_char *optp;
 890 #ifdef INET6
 891         struct ip6_hdr *ip6;
 892         int isipv6;
 893 #endif /* INET6 */
 894         int optlen, tlen, win;
 895         bool incl_opts;
 896
 897         KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
 898
 899 #ifdef INET6
 900         isipv6 = ((struct ip *)ipgen)->ip_v == (IPV6_VERSION >> 4);
 901         ip6 = ipgen;
 902 #endif /* INET6 */
 903         ip = ipgen;
 904
 905         if (tp != NULL) {
 906                 inp = tp->t_inpcb;
 907                 KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
 908                 INP_WLOCK_ASSERT(inp);
 909         } else
 910                 inp = NULL;
 911
 912         incl_opts = false;
 913         win = 0;
 914         if (tp != NULL) {
 915                 if (!(flags & TH_RST)) {
 916                         win = sbspace(&inp->inp_socket->so_rcv);
 917                         if (win > TCP_MAXWIN << tp->rcv_scale)
 918                                 win = TCP_MAXWIN << tp->rcv_scale;
 919                 }
 920                 if ((tp->t_flags & TF_NOOPT) == 0)
 921                         incl_opts = true;
 922         }
 923         if (m == NULL) {
 924                 m = m_gethdr(M_NOWAIT, MT_DATA);
 925                 if (m == NULL)
 926                         return;
 927                 m->m_data += max_linkhdr;
 928 #ifdef INET6
 929                 if (isipv6) {
 930                         bcopy((caddr_t)ip6, mtod(m, caddr_t),
 931                               sizeof(struct ip6_hdr));
 932                         ip6 = mtod(m, struct ip6_hdr *);
 933                         nth = (struct tcphdr *)(ip6 + 1);
 934                 } else
 935 #endif /* INET6 */
 936                 {
 937                         bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
 938                         ip = mtod(m, struct ip *);
 939                         nth = (struct tcphdr *)(ip + 1);
 940                 }
 941                 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
 942                 flags = TH_ACK;
 943         } else if (!M_WRITABLE(m)) {
 944                 struct mbuf *n;
 945
 946                 /* Can't reuse 'm', allocate a new mbuf. */
 947                 n = m_gethdr(M_NOWAIT, MT_DATA);
 948                 if (n == NULL) {
 949                         m_freem(m);
 950                         return;
 951                 }
 952
 953                 if (!m_dup_pkthdr(n, m, M_NOWAIT)) {
 954                         m_freem(m);
 955                         m_freem(n);
 956                         return;
 957                 }
 958
 959                 n->m_data += max_linkhdr;
 960                 /* m_len is set later */
 961 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
 962 #ifdef INET6
 963                 if (isipv6) {
 964                         bcopy((caddr_t)ip6, mtod(n, caddr_t),
 965                               sizeof(struct ip6_hdr));
 966                         ip6 = mtod(n, struct ip6_hdr *);
 967                         xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
 968                         nth = (struct tcphdr *)(ip6 + 1);
 969                 } else
 970 #endif /* INET6 */
 971                 {
 972                         bcopy((caddr_t)ip, mtod(n, caddr_t), sizeof(struct ip));
 973                         ip = mtod(n, struct ip *);
 974                         xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
 975                         nth = (struct tcphdr *)(ip + 1);
 976                 }
 977                 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
 978                 xchg(nth->th_dport, nth->th_sport, uint16_t);
 979                 th = nth;
 980                 m_freem(m);
 981                 m = n;
 982         } else {
 983                 /*
 984                  *  reuse the mbuf.
 985                  * XXX MRT We inherit the FIB, which is lucky.
 986                  */
 987                 m_freem(m->m_next);
 988                 m->m_next = NULL;
 989                 m->m_data = (caddr_t)ipgen;
 990                 /* m_len is set later */
 991 #ifdef INET6
 992                 if (isipv6) {
 993                         xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
 994                         nth = (struct tcphdr *)(ip6 + 1);
 995                 } else
 996 #endif /* INET6 */
 997                 {
 998                         xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
 999                         nth = (struct tcphdr *)(ip + 1);
1000                 }
1001                 if (th != nth) {
1002                         /*
1003                          * this is usually a case when an extension header
1004                          * exists between the IPv6 header and the
1005                          * TCP header.
1006                          */
1007                         nth->th_sport = th->th_sport;
1008                         nth->th_dport = th->th_dport;
1009                 }
1010                 xchg(nth->th_dport, nth->th_sport, uint16_t);
1011 #undef xchg
1012         }
1013         tlen = 0;
1014 #ifdef INET6
1015         if (isipv6)
1016                 tlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
1017 #endif
1018 #if defined(INET) && defined(INET6)
1019         else
1020 #endif
1021 #ifdef INET
1022                 tlen = sizeof (struct tcpiphdr);
1023 #endif
1024 #ifdef INVARIANTS
1025         m->m_len = 0;
1026         KASSERT(M_TRAILINGSPACE(m) >= tlen,
1027             ("Not enough trailing space for message (m=%p, need=%d, have=%ld)",
1028             m, tlen, (long)M_TRAILINGSPACE(m)));
1029 #endif
1030         m->m_len = tlen;
1031         to.to_flags = 0;
1032         if (incl_opts) {
1033                 /* Make sure we have room. */
1034                 if (M_TRAILINGSPACE(m) < TCP_MAXOLEN) {
1035                         m->m_next = m_get(M_NOWAIT, MT_DATA);
1036                         if (m->m_next) {
1037                                 optp = mtod(m->m_next, u_char *);
1038                                 optm = m->m_next;
1039                         } else
1040                                 incl_opts = false;
1041                 } else {
1042                         optp = (u_char *) (nth + 1);
1043                         optm = m;
1044                 }
1045         }
1046         if (incl_opts) {
1047                 /* Timestamps. */
1048                 if (tp->t_flags & TF_RCVD_TSTMP) {
1049                         to.to_tsval = tcp_ts_getticks() + tp->ts_offset;
1050                         to.to_tsecr = tp->ts_recent;
1051                         to.to_flags |= TOF_TS;
1052                 }
1053 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
1054                 /* TCP-MD5 (RFC2385). */
1055                 if (tp->t_flags & TF_SIGNATURE)
1056                         to.to_flags |= TOF_SIGNATURE;
1057 #endif
1058                 /* Add the options. */
1059                 tlen += optlen = tcp_addoptions(&to, optp);
1060
1061                 /* Update m_len in the correct mbuf. */
1062                 optm->m_len += optlen;
1063         } else
1064                 optlen = 0;
1065 #ifdef INET6
1066         if (isipv6) {
1067                 ip6->ip6_flow = 0;
1068                 ip6->ip6_vfc = IPV6_VERSION;
1069                 ip6->ip6_nxt = IPPROTO_TCP;
1070                 ip6->ip6_plen = htons(tlen - sizeof(*ip6));
1071         }
1072 #endif
1073 #if defined(INET) && defined(INET6)
1074         else
1075 #endif
1076 #ifdef INET
1077         {
1078                 ip->ip_len = htons(tlen);
1079                 ip->ip_ttl = V_ip_defttl;
1080                 if (V_path_mtu_discovery)
1081                         ip->ip_off |= htons(IP_DF);
1082         }
1083 #endif
1084         m->m_pkthdr.len = tlen;
1085         m->m_pkthdr.rcvif = NULL;
1086 #ifdef MAC
1087         if (inp != NULL) {
1088                 /*
1089                  * Packet is associated with a socket, so allow the
1090                  * label of the response to reflect the socket label.
1091                  */
1092                 INP_WLOCK_ASSERT(inp);
1093                 mac_inpcb_create_mbuf(inp, m);
1094         } else {
1095                 /*
1096                  * Packet is not associated with a socket, so possibly
1097                  * update the label in place.
1098                  */
1099                 mac_netinet_tcp_reply(m);
1100         }
1101 #endif
1102         nth->th_seq = htonl(seq);
1103         nth->th_ack = htonl(ack);
1104         nth->th_x2 = 0;
1105         nth->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
1106         nth->th_flags = flags;
1107         if (tp != NULL)
1108                 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
1109         else
1110                 nth->th_win = htons((u_short)win);
1111         nth->th_urp = 0;
1112
1113 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
1114         if (to.to_flags & TOF_SIGNATURE) {
1115                 if (!TCPMD5_ENABLED() ||
1116                     TCPMD5_OUTPUT(m, nth, to.to_signature) != 0) {
1117                         m_freem(m);
1118                         return;
1119                 }
1120         }
1121 #endif
1122
1123         m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1124 #ifdef INET6
1125         if (isipv6) {
1126                 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
1127                 nth->th_sum = in6_cksum_pseudo(ip6,
1128                     tlen - sizeof(struct ip6_hdr), IPPROTO_TCP, 0);
1129                 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
1130                     NULL, NULL);
1131         }
1132 #endif /* INET6 */
1133 #if defined(INET6) && defined(INET)
1134         else
1135 #endif
1136 #ifdef INET
1137         {
1138                 m->m_pkthdr.csum_flags = CSUM_TCP;
1139                 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1140                     htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
1141         }
1142 #endif /* INET */
1143 #ifdef TCPDEBUG
1144         if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
1145                 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
1146 #endif
1147         TCP_PROBE3(debug__output, tp, th, m);
1148         if (flags & TH_RST)
1149                 TCP_PROBE5(accept__refused, NULL, NULL, m, tp, nth);
1150
1151         TCP_PROBE5(send, NULL, tp, m, tp, nth);
1152 #ifdef INET6
1153         if (isipv6)
1154                 (void) ip6_output(m, NULL, NULL, 0, NULL, NULL, inp);
1155 #endif /* INET6 */
1156 #if defined(INET) && defined(INET6)
1157         else
1158 #endif
1159 #ifdef INET
1160                 (void) ip_output(m, NULL, NULL, 0, NULL, inp);
1161 #endif
1162 }
1163
1164 /*
1165  * Create a new TCP control block, making an
1166  * empty reassembly queue and hooking it to the argument
1167  * protocol control block.  The `inp' parameter must have
1168  * come from the zone allocator set up in tcp_init().
1169  */
1170 struct tcpcb *
1171 tcp_newtcpcb(struct inpcb *inp)
1172 {
1173         struct tcpcb_mem *tm;
1174         struct tcpcb *tp;
1175 #ifdef INET6
1176         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
1177 #endif /* INET6 */
1178
1179         tm = uma_zalloc(V_tcpcb_zone, M_NOWAIT | M_ZERO);
1180         if (tm == NULL)
1181                 return (NULL);
1182         tp = &tm->tcb;
1183
1184         /* Initialise cc_var struct for this tcpcb. */
1185         tp->ccv = &tm->ccv;
1186         tp->ccv->type = IPPROTO_TCP;
1187         tp->ccv->ccvc.tcp = tp;
1188         rw_rlock(&tcp_function_lock);
1189         tp->t_fb = tcp_func_set_ptr;
1190         refcount_acquire(&tp->t_fb->tfb_refcnt);
1191         rw_runlock(&tcp_function_lock);
1192         /*
1193          * Use the current system default CC algorithm.
1194          */
1195         CC_LIST_RLOCK();
1196         KASSERT(!STAILQ_EMPTY(&cc_list), ("cc_list is empty!"));
1197         CC_ALGO(tp) = CC_DEFAULT();
1198         CC_LIST_RUNLOCK();
1199
1200         if (CC_ALGO(tp)->cb_init != NULL)
1201                 if (CC_ALGO(tp)->cb_init(tp->ccv) > 0) {
1202                         if (tp->t_fb->tfb_tcp_fb_fini)
1203                                 (*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
1204                         refcount_release(&tp->t_fb->tfb_refcnt);
1205                         uma_zfree(V_tcpcb_zone, tm);
1206                         return (NULL);
1207                 }
1208
1209 #ifdef TCP_HHOOK
1210         tp->osd = &tm->osd;
1211         if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
1212                 if (tp->t_fb->tfb_tcp_fb_fini)
1213                         (*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
1214                 refcount_release(&tp->t_fb->tfb_refcnt);
1215                 uma_zfree(V_tcpcb_zone, tm);
1216                 return (NULL);
1217         }
1218 #endif
1219
1220 #ifdef VIMAGE
1221         tp->t_vnet = inp->inp_vnet;
1222 #endif
1223         tp->t_timers = &tm->tt;
1224         /*      LIST_INIT(&tp->t_segq); */      /* XXX covered by M_ZERO */
1225         tp->t_maxseg =
1226 #ifdef INET6
1227                 isipv6 ? V_tcp_v6mssdflt :
1228 #endif /* INET6 */
1229                 V_tcp_mssdflt;
1230
1231         /* Set up our timeouts. */
1232         callout_init(&tp->t_timers->tt_rexmt, 1);
1233         callout_init(&tp->t_timers->tt_persist, 1);
1234         callout_init(&tp->t_timers->tt_keep, 1);
1235         callout_init(&tp->t_timers->tt_2msl, 1);
1236         callout_init(&tp->t_timers->tt_delack, 1);
1237
1238         if (V_tcp_do_rfc1323)
1239                 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
1240         if (V_tcp_do_sack)
1241                 tp->t_flags |= TF_SACK_PERMIT;
1242         TAILQ_INIT(&tp->snd_holes);
1243         /*
1244          * The tcpcb will hold a reference on its inpcb until tcp_discardcb()
1245          * is called.
1246          */
1247         in_pcbref(inp); /* Reference for tcpcb */
1248         tp->t_inpcb = inp;
1249
1250         /*
1251          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
1252          * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
1253          * reasonable initial retransmit time.
1254          */
1255         tp->t_srtt = TCPTV_SRTTBASE;
1256         tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
1257         tp->t_rttmin = tcp_rexmit_min;
1258         tp->t_rxtcur = TCPTV_RTOBASE;
1259         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1260         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1261         tp->t_rcvtime = ticks;
1262         /*
1263          * IPv4 TTL initialization is necessary for an IPv6 socket as well,
1264          * because the socket may be bound to an IPv6 wildcard address,
1265          * which may match an IPv4-mapped IPv6 address.
1266          */
1267         inp->inp_ip_ttl = V_ip_defttl;
1268         inp->inp_ppcb = tp;
1269 #ifdef TCPPCAP
1270         /*
1271          * Init the TCP PCAP queues.
1272          */
1273         tcp_pcap_tcpcb_init(tp);
1274 #endif
1275         if (tp->t_fb->tfb_tcp_fb_init) {
1276                 (*tp->t_fb->tfb_tcp_fb_init)(tp);
1277         }
1278         return (tp);            /* XXX */
1279 }
1280
1281 /*
1282  * Switch the congestion control algorithm back to NewReno for any active
1283  * control blocks using an algorithm which is about to go away.
1284  * This ensures the CC framework can allow the unload to proceed without leaving
1285  * any dangling pointers which would trigger a panic.
1286  * Returning non-zero would inform the CC framework that something went wrong
1287  * and it would be unsafe to allow the unload to proceed. However, there is no
1288  * way for this to occur with this implementation so we always return zero.
1289  */
1290 int
1291 tcp_ccalgounload(struct cc_algo *unload_algo)
1292 {
1293         struct cc_algo *tmpalgo;
1294         struct inpcb *inp;
1295         struct tcpcb *tp;
1296         VNET_ITERATOR_DECL(vnet_iter);
1297
1298         /*
1299          * Check all active control blocks across all network stacks and change
1300          * any that are using "unload_algo" back to NewReno. If "unload_algo"
1301          * requires cleanup code to be run, call it.
1302          */
1303         VNET_LIST_RLOCK();
1304         VNET_FOREACH(vnet_iter) {
1305                 CURVNET_SET(vnet_iter);
1306                 INP_INFO_WLOCK(&V_tcbinfo);
1307                 /*
1308                  * New connections already part way through being initialised
1309                  * with the CC algo we're removing will not race with this code
1310                  * because the INP_INFO_WLOCK is held during initialisation. We
1311                  * therefore don't enter the loop below until the connection
1312                  * list has stabilised.
1313                  */
1314                 LIST_FOREACH(inp, &V_tcb, inp_list) {
1315                         INP_WLOCK(inp);
1316                         /* Important to skip tcptw structs. */
1317                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
1318                             (tp = intotcpcb(inp)) != NULL) {
1319                                 /*
1320                                  * By holding INP_WLOCK here, we are assured
1321                                  * that the connection is not currently
1322                                  * executing inside the CC module's functions
1323                                  * i.e. it is safe to make the switch back to
1324                                  * NewReno.
1325                                  */
1326                                 if (CC_ALGO(tp) == unload_algo) {
1327                                         tmpalgo = CC_ALGO(tp);
1328                                         /* NewReno does not require any init. */
1329                                         CC_ALGO(tp) = &newreno_cc_algo;
1330                                         if (tmpalgo->cb_destroy != NULL)
1331                                                 tmpalgo->cb_destroy(tp->ccv);
1332                                 }
1333                         }
1334                         INP_WUNLOCK(inp);
1335                 }
1336                 INP_INFO_WUNLOCK(&V_tcbinfo);
1337                 CURVNET_RESTORE();
1338         }
1339         VNET_LIST_RUNLOCK();
1340
1341         return (0);
1342 }
1343
1344 /*
1345  * Drop a TCP connection, reporting
1346  * the specified error.  If connection is synchronized,
1347  * then send a RST to peer.
1348  */
1349 struct tcpcb *
1350 tcp_drop(struct tcpcb *tp, int errno)
1351 {
1352         struct socket *so = tp->t_inpcb->inp_socket;
1353
1354         INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1355         INP_WLOCK_ASSERT(tp->t_inpcb);
1356
1357         if (TCPS_HAVERCVDSYN(tp->t_state)) {
1358                 tcp_state_change(tp, TCPS_CLOSED);
1359                 (void) tp->t_fb->tfb_tcp_output(tp);
1360                 TCPSTAT_INC(tcps_drops);
1361         } else
1362                 TCPSTAT_INC(tcps_conndrops);
1363         if (errno == ETIMEDOUT && tp->t_softerror)
1364                 errno = tp->t_softerror;
1365         so->so_error = errno;
1366         return (tcp_close(tp));
1367 }
1368
1369 void
1370 tcp_discardcb(struct tcpcb *tp)
1371 {
1372         struct inpcb *inp = tp->t_inpcb;
1373         struct socket *so = inp->inp_socket;
1374 #ifdef INET6
1375         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
1376 #endif /* INET6 */
1377         int released;
1378
1379         INP_WLOCK_ASSERT(inp);
1380
1381         /*
1382          * Make sure that all of our timers are stopped before we delete the
1383          * PCB.
1384          *
1385          * If stopping a timer fails, we schedule a discard function in same
1386          * callout, and the last discard function called will take care of
1387          * deleting the tcpcb.
1388          */
1389         tp->t_timers->tt_draincnt = 0;
1390         tcp_timer_stop(tp, TT_REXMT);
1391         tcp_timer_stop(tp, TT_PERSIST);
1392         tcp_timer_stop(tp, TT_KEEP);
1393         tcp_timer_stop(tp, TT_2MSL);
1394         tcp_timer_stop(tp, TT_DELACK);
1395         if (tp->t_fb->tfb_tcp_timer_stop_all) {
1396                 /*
1397                  * Call the stop-all function of the methods,
1398                  * this function should call the tcp_timer_stop()
1399                  * method with each of the function specific timeouts.
1400                  * That stop will be called via the tfb_tcp_timer_stop()
1401                  * which should use the async drain function of the
1402                  * callout system (see tcp_var.h).
1403                  */
1404                 tp->t_fb->tfb_tcp_timer_stop_all(tp);
1405         }
1406
1407         /*
1408          * If we got enough samples through the srtt filter,
1409          * save the rtt and rttvar in the routing entry.
1410          * 'Enough' is arbitrarily defined as 4 rtt samples.
1411          * 4 samples is enough for the srtt filter to converge
1412          * to within enough % of the correct value; fewer samples
1413          * and we could save a bogus rtt. The danger is not high
1414          * as tcp quickly recovers from everything.
1415          * XXX: Works very well but needs some more statistics!
1416          */
1417         if (tp->t_rttupdated >= 4) {
1418                 struct hc_metrics_lite metrics;
1419                 uint32_t ssthresh;
1420
1421                 bzero(&metrics, sizeof(metrics));
1422                 /*
1423                  * Update the ssthresh always when the conditions below
1424                  * are satisfied. This gives us better new start value
1425                  * for the congestion avoidance for new connections.
1426                  * ssthresh is only set if packet loss occurred on a session.
1427                  *
1428                  * XXXRW: 'so' may be NULL here, and/or socket buffer may be
1429                  * being torn down.  Ideally this code would not use 'so'.
1430                  */
1431                 ssthresh = tp->snd_ssthresh;
1432                 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
1433                         /*
1434                          * convert the limit from user data bytes to
1435                          * packets then to packet data bytes.
1436                          */
1437                         ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
1438                         if (ssthresh < 2)
1439                                 ssthresh = 2;
1440                         ssthresh *= (tp->t_maxseg +
1441 #ifdef INET6
1442                             (isipv6 ? sizeof (struct ip6_hdr) +
1443                                 sizeof (struct tcphdr) :
1444 #endif
1445                                 sizeof (struct tcpiphdr)
1446 #ifdef INET6
1447                             )
1448 #endif
1449                             );
1450                 } else
1451                         ssthresh = 0;
1452                 metrics.rmx_ssthresh = ssthresh;
1453
1454                 metrics.rmx_rtt = tp->t_srtt;
1455                 metrics.rmx_rttvar = tp->t_rttvar;
1456                 metrics.rmx_cwnd = tp->snd_cwnd;
1457                 metrics.rmx_sendpipe = 0;
1458                 metrics.rmx_recvpipe = 0;
1459
1460                 tcp_hc_update(&inp->inp_inc, &metrics);
1461         }
1462
1463         /* free the reassembly queue, if any */
1464         tcp_reass_flush(tp);
1465
1466 #ifdef TCP_OFFLOAD
1467         /* Disconnect offload device, if any. */
1468         if (tp->t_flags & TF_TOE)
1469                 tcp_offload_detach(tp);
1470 #endif
1471
1472         tcp_free_sackholes(tp);
1473
1474 #ifdef TCPPCAP
1475         /* Free the TCP PCAP queues. */
1476         tcp_pcap_drain(&(tp->t_inpkts));
1477         tcp_pcap_drain(&(tp->t_outpkts));
1478 #endif
1479
1480         /* Allow the CC algorithm to clean up after itself. */
1481         if (CC_ALGO(tp)->cb_destroy != NULL)
1482                 CC_ALGO(tp)->cb_destroy(tp->ccv);
1483
1484 #ifdef TCP_HHOOK
1485         khelp_destroy_osd(tp->osd);
1486 #endif
1487
1488         CC_ALGO(tp) = NULL;
1489         inp->inp_ppcb = NULL;
1490         if (tp->t_timers->tt_draincnt == 0) {
1491                 /* We own the last reference on tcpcb, let's free it. */
1492                 TCPSTATES_DEC(tp->t_state);
1493                 if (tp->t_fb->tfb_tcp_fb_fini)
1494                         (*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
1495                 refcount_release(&tp->t_fb->tfb_refcnt);
1496                 tp->t_inpcb = NULL;
1497                 uma_zfree(V_tcpcb_zone, tp);
1498                 released = in_pcbrele_wlocked(inp);
1499                 KASSERT(!released, ("%s: inp %p should not have been released "
1500                         "here", __func__, inp));
1501         }
1502 }
1503
1504 void
1505 tcp_timer_discard(void *ptp)
1506 {
1507         struct inpcb *inp;
1508         struct tcpcb *tp;
1509
1510         tp = (struct tcpcb *)ptp;
1511         CURVNET_SET(tp->t_vnet);
1512         INP_INFO_RLOCK(&V_tcbinfo);
1513         inp = tp->t_inpcb;
1514         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL",
1515                 __func__, tp));
1516         INP_WLOCK(inp);
1517         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) != 0,
1518                 ("%s: tcpcb has to be stopped here", __func__));
1519         tp->t_timers->tt_draincnt--;
1520         if (tp->t_timers->tt_draincnt == 0) {
1521                 /* We own the last reference on this tcpcb, let's free it. */
1522                 TCPSTATES_DEC(tp->t_state);
1523                 if (tp->t_fb->tfb_tcp_fb_fini)
1524                         (*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
1525                 refcount_release(&tp->t_fb->tfb_refcnt);
1526                 tp->t_inpcb = NULL;
1527                 uma_zfree(V_tcpcb_zone, tp);
1528                 if (in_pcbrele_wlocked(inp)) {
1529                         INP_INFO_RUNLOCK(&V_tcbinfo);
1530                         CURVNET_RESTORE();
1531                         return;
1532                 }
1533         }
1534         INP_WUNLOCK(inp);
1535         INP_INFO_RUNLOCK(&V_tcbinfo);
1536         CURVNET_RESTORE();
1537 }
1538
1539 /*
1540  * Attempt to close a TCP control block, marking it as dropped, and freeing
1541  * the socket if we hold the only reference.
1542  */
1543 struct tcpcb *
1544 tcp_close(struct tcpcb *tp)
1545 {
1546         struct inpcb *inp = tp->t_inpcb;
1547         struct socket *so;
1548
1549         INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1550         INP_WLOCK_ASSERT(inp);
1551
1552 #ifdef TCP_OFFLOAD
1553         if (tp->t_state == TCPS_LISTEN)
1554                 tcp_offload_listen_stop(tp);
1555 #endif
1556 #ifdef TCP_RFC7413
1557         /*
1558          * This releases the TFO pending counter resource for TFO listen
1559          * sockets as well as passively-created TFO sockets that transition
1560          * from SYN_RECEIVED to CLOSED.
1561          */
1562         if (tp->t_tfo_pending) {
1563                 tcp_fastopen_decrement_counter(tp->t_tfo_pending);
1564                 tp->t_tfo_pending = NULL;
1565         }
1566 #endif
1567         in_pcbdrop(inp);
1568         TCPSTAT_INC(tcps_closed);
1569         if (tp->t_state != TCPS_CLOSED)
1570                 tcp_state_change(tp, TCPS_CLOSED);
1571         KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
1572         so = inp->inp_socket;
1573         soisdisconnected(so);
1574         if (inp->inp_flags & INP_SOCKREF) {
1575                 KASSERT(so->so_state & SS_PROTOREF,
1576                     ("tcp_close: !SS_PROTOREF"));
1577                 inp->inp_flags &= ~INP_SOCKREF;
1578                 INP_WUNLOCK(inp);
1579                 ACCEPT_LOCK();
1580                 SOCK_LOCK(so);
1581                 so->so_state &= ~SS_PROTOREF;
1582                 sofree(so);
1583                 return (NULL);
1584         }
1585         return (tp);
1586 }
1587
1588 void
1589 tcp_drain(void)
1590 {
1591         VNET_ITERATOR_DECL(vnet_iter);
1592
1593         if (!do_tcpdrain)
1594                 return;
1595
1596         VNET_LIST_RLOCK_NOSLEEP();
1597         VNET_FOREACH(vnet_iter) {
1598                 CURVNET_SET(vnet_iter);
1599                 struct inpcb *inpb;
1600                 struct tcpcb *tcpb;
1601
1602         /*
1603          * Walk the tcpbs, if existing, and flush the reassembly queue,
1604          * if there is one...
1605          * XXX: The "Net/3" implementation doesn't imply that the TCP
1606          *      reassembly queue should be flushed, but in a situation
1607          *      where we're really low on mbufs, this is potentially
1608          *      useful.
1609          */
1610                 INP_INFO_WLOCK(&V_tcbinfo);
1611                 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) {
1612                         if (inpb->inp_flags & INP_TIMEWAIT)
1613                                 continue;
1614                         INP_WLOCK(inpb);
1615                         if ((tcpb = intotcpcb(inpb)) != NULL) {
1616                                 tcp_reass_flush(tcpb);
1617                                 tcp_clean_sackreport(tcpb);
1618 #ifdef TCPPCAP
1619                                 if (tcp_pcap_aggressive_free) {
1620                                         /* Free the TCP PCAP queues. */
1621                                         tcp_pcap_drain(&(tcpb->t_inpkts));
1622                                         tcp_pcap_drain(&(tcpb->t_outpkts));
1623                                 }
1624 #endif
1625                         }
1626                         INP_WUNLOCK(inpb);
1627                 }
1628                 INP_INFO_WUNLOCK(&V_tcbinfo);
1629                 CURVNET_RESTORE();
1630         }
1631         VNET_LIST_RUNLOCK_NOSLEEP();
1632 }
1633
1634 /*
1635  * Notify a tcp user of an asynchronous error;
1636  * store error as soft error, but wake up user
1637  * (for now, won't do anything until can select for soft error).
1638  *
1639  * Do not wake up user since there currently is no mechanism for
1640  * reporting soft errors (yet - a kqueue filter may be added).
1641  */
1642 static struct inpcb *
1643 tcp_notify(struct inpcb *inp, int error)
1644 {
1645         struct tcpcb *tp;
1646
1647         INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1648         INP_WLOCK_ASSERT(inp);
1649
1650         if ((inp->inp_flags & INP_TIMEWAIT) ||
1651             (inp->inp_flags & INP_DROPPED))
1652                 return (inp);
1653
1654         tp = intotcpcb(inp);
1655         KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
1656
1657         /*
1658          * Ignore some errors if we are hooked up.
1659          * If connection hasn't completed, has retransmitted several times,
1660          * and receives a second error, give up now.  This is better
1661          * than waiting a long time to establish a connection that
1662          * can never complete.
1663          */
1664         if (tp->t_state == TCPS_ESTABLISHED &&
1665             (error == EHOSTUNREACH || error == ENETUNREACH ||
1666              error == EHOSTDOWN)) {
1667                 if (inp->inp_route.ro_rt) {
1668                         RTFREE(inp->inp_route.ro_rt);
1669                         inp->inp_route.ro_rt = (struct rtentry *)NULL;
1670                 }
1671                 return (inp);
1672         } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
1673             tp->t_softerror) {
1674                 tp = tcp_drop(tp, error);
1675                 if (tp != NULL)
1676                         return (inp);
1677                 else
1678                         return (NULL);
1679         } else {
1680                 tp->t_softerror = error;
1681                 return (inp);
1682         }
1683 #if 0
1684         wakeup( &so->so_timeo);
1685         sorwakeup(so);
1686         sowwakeup(so);
1687 #endif
1688 }
1689
1690 static int
1691 tcp_pcblist(SYSCTL_HANDLER_ARGS)
1692 {
1693         int error, i, m, n, pcb_count;
1694         struct inpcb *inp, **inp_list;
1695         inp_gen_t gencnt;
1696         struct xinpgen xig;
1697
1698         /*
1699          * The process of preparing the TCB list is too time-consuming and
1700          * resource-intensive to repeat twice on every request.
1701          */
1702         if (req->oldptr == NULL) {
1703                 n = V_tcbinfo.ipi_count +
1704                     counter_u64_fetch(V_tcps_states[TCPS_SYN_RECEIVED]);
1705                 n += imax(n / 8, 10);
1706                 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
1707                 return (0);
1708         }
1709
1710         if (req->newptr != NULL)
1711                 return (EPERM);
1712
1713         /*
1714          * OK, now we're committed to doing something.
1715          */
1716         INP_LIST_RLOCK(&V_tcbinfo);
1717         gencnt = V_tcbinfo.ipi_gencnt;
1718         n = V_tcbinfo.ipi_count;
1719         INP_LIST_RUNLOCK(&V_tcbinfo);
1720
1721         m = counter_u64_fetch(V_tcps_states[TCPS_SYN_RECEIVED]);
1722
1723         error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
1724                 + (n + m) * sizeof(struct xtcpcb));
1725         if (error != 0)
1726                 return (error);
1727
1728         xig.xig_len = sizeof xig;
1729         xig.xig_count = n + m;
1730         xig.xig_gen = gencnt;
1731         xig.xig_sogen = so_gencnt;
1732         error = SYSCTL_OUT(req, &xig, sizeof xig);
1733         if (error)
1734                 return (error);
1735
1736         error = syncache_pcblist(req, m, &pcb_count);
1737         if (error)
1738                 return (error);
1739
1740         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
1741
1742         INP_INFO_WLOCK(&V_tcbinfo);
1743         for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0;
1744             inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) {
1745                 INP_WLOCK(inp);
1746                 if (inp->inp_gencnt <= gencnt) {
1747                         /*
1748                          * XXX: This use of cr_cansee(), introduced with
1749                          * TCP state changes, is not quite right, but for
1750                          * now, better than nothing.
1751                          */
1752                         if (inp->inp_flags & INP_TIMEWAIT) {
1753                                 if (intotw(inp) != NULL)
1754                                         error = cr_cansee(req->td->td_ucred,
1755                                             intotw(inp)->tw_cred);
1756                                 else
1757                                         error = EINVAL; /* Skip this inp. */
1758                         } else
1759                                 error = cr_canseeinpcb(req->td->td_ucred, inp);
1760                         if (error == 0) {
1761                                 in_pcbref(inp);
1762                                 inp_list[i++] = inp;
1763                         }
1764                 }
1765                 INP_WUNLOCK(inp);
1766         }
1767         INP_INFO_WUNLOCK(&V_tcbinfo);
1768         n = i;
1769
1770         error = 0;
1771         for (i = 0; i < n; i++) {
1772                 inp = inp_list[i];
1773                 INP_RLOCK(inp);
1774                 if (inp->inp_gencnt <= gencnt) {
1775                         struct xtcpcb xt;
1776
1777                         tcp_inptoxtp(inp, &xt);
1778                         INP_RUNLOCK(inp);
1779                         error = SYSCTL_OUT(req, &xt, sizeof xt);
1780                 } else
1781                         INP_RUNLOCK(inp);
1782         }
1783         INP_INFO_RLOCK(&V_tcbinfo);
1784         for (i = 0; i < n; i++) {
1785                 inp = inp_list[i];
1786                 INP_RLOCK(inp);
1787                 if (!in_pcbrele_rlocked(inp))
1788                         INP_RUNLOCK(inp);
1789         }
1790         INP_INFO_RUNLOCK(&V_tcbinfo);
1791
1792         if (!error) {
1793                 /*
1794                  * Give the user an updated idea of our state.
1795                  * If the generation differs from what we told
1796                  * her before, she knows that something happened
1797                  * while we were processing this request, and it
1798                  * might be necessary to retry.
1799                  */
1800                 INP_LIST_RLOCK(&V_tcbinfo);
1801                 xig.xig_gen = V_tcbinfo.ipi_gencnt;
1802                 xig.xig_sogen = so_gencnt;
1803                 xig.xig_count = V_tcbinfo.ipi_count + pcb_count;
1804                 INP_LIST_RUNLOCK(&V_tcbinfo);
1805                 error = SYSCTL_OUT(req, &xig, sizeof xig);
1806         }
1807         free(inp_list, M_TEMP);
1808         return (error);
1809 }
1810
1811 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
1812     CTLTYPE_OPAQUE | CTLFLAG_RD, NULL, 0,
1813     tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1814
1815 #ifdef INET
1816 static int
1817 tcp_getcred(SYSCTL_HANDLER_ARGS)
1818 {
1819         struct xucred xuc;
1820         struct sockaddr_in addrs[2];
1821         struct inpcb *inp;
1822         int error;
1823
1824         error = priv_check(req->td, PRIV_NETINET_GETCRED);
1825         if (error)
1826                 return (error);
1827         error = SYSCTL_IN(req, addrs, sizeof(addrs));
1828         if (error)
1829                 return (error);
1830         inp = in_pcblookup(&V_tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
1831             addrs[0].sin_addr, addrs[0].sin_port, INPLOOKUP_RLOCKPCB, NULL);
1832         if (inp != NULL) {
1833                 if (inp->inp_socket == NULL)
1834                         error = ENOENT;
1835                 if (error == 0)
1836                         error = cr_canseeinpcb(req->td->td_ucred, inp);
1837                 if (error == 0)
1838                         cru2x(inp->inp_cred, &xuc);
1839                 INP_RUNLOCK(inp);
1840         } else
1841                 error = ENOENT;
1842         if (error == 0)
1843                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1844         return (error);
1845 }
1846
1847 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
1848     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1849     tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
1850 #endif /* INET */
1851
1852 #ifdef INET6
1853 static int
1854 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1855 {
1856         struct xucred xuc;
1857         struct sockaddr_in6 addrs[2];
1858         struct inpcb *inp;
1859         int error;
1860 #ifdef INET
1861         int mapped = 0;
1862 #endif
1863
1864         error = priv_check(req->td, PRIV_NETINET_GETCRED);
1865         if (error)
1866                 return (error);
1867         error = SYSCTL_IN(req, addrs, sizeof(addrs));
1868         if (error)
1869                 return (error);
1870         if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
1871             (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
1872                 return (error);
1873         }
1874         if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1875 #ifdef INET
1876                 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1877                         mapped = 1;
1878                 else
1879 #endif
1880                         return (EINVAL);
1881         }
1882
1883 #ifdef INET
1884         if (mapped == 1)
1885                 inp = in_pcblookup(&V_tcbinfo,
1886                         *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1887                         addrs[1].sin6_port,
1888                         *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1889                         addrs[0].sin6_port, INPLOOKUP_RLOCKPCB, NULL);
1890         else
1891 #endif
1892                 inp = in6_pcblookup(&V_tcbinfo,
1893                         &addrs[1].sin6_addr, addrs[1].sin6_port,
1894                         &addrs[0].sin6_addr, addrs[0].sin6_port,
1895                         INPLOOKUP_RLOCKPCB, NULL);
1896         if (inp != NULL) {
1897                 if (inp->inp_socket == NULL)
1898                         error = ENOENT;
1899                 if (error == 0)
1900                         error = cr_canseeinpcb(req->td->td_ucred, inp);
1901                 if (error == 0)
1902                         cru2x(inp->inp_cred, &xuc);
1903                 INP_RUNLOCK(inp);
1904         } else
1905                 error = ENOENT;
1906         if (error == 0)
1907                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1908         return (error);
1909 }
1910
1911 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
1912     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1913     tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
1914 #endif /* INET6 */
1915
1916
1917 #ifdef INET
1918 void
1919 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
1920 {
1921         struct ip *ip = vip;
1922         struct tcphdr *th;
1923         struct in_addr faddr;
1924         struct inpcb *inp;
1925         struct tcpcb *tp;
1926         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1927         struct icmp *icp;
1928         struct in_conninfo inc;
1929         tcp_seq icmp_tcp_seq;
1930         int mtu;
1931
1932         faddr = ((struct sockaddr_in *)sa)->sin_addr;
1933         if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1934                 return;
1935
1936         if (cmd == PRC_MSGSIZE)
1937                 notify = tcp_mtudisc_notify;
1938         else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1939                 cmd == PRC_UNREACH_PORT || cmd == PRC_UNREACH_PROTOCOL ||
1940                 cmd == PRC_TIMXCEED_INTRANS) && ip)
1941                 notify = tcp_drop_syn_sent;
1942
1943         /*
1944          * Hostdead is ugly because it goes linearly through all PCBs.
1945          * XXX: We never get this from ICMP, otherwise it makes an
1946          * excellent DoS attack on machines with many connections.
1947          */
1948         else if (cmd == PRC_HOSTDEAD)
1949                 ip = NULL;
1950         else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
1951                 return;
1952
1953         if (ip == NULL) {
1954                 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify);
1955                 return;
1956         }
1957
1958         icp = (struct icmp *)((caddr_t)ip - offsetof(struct icmp, icmp_ip));
1959         th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2));
1960         INP_INFO_RLOCK(&V_tcbinfo);
1961         inp = in_pcblookup(&V_tcbinfo, faddr, th->th_dport, ip->ip_src,
1962             th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
1963         if (inp != NULL && PRC_IS_REDIRECT(cmd)) {
1964                 /* signal EHOSTDOWN, as it flushes the cached route */
1965                 inp = (*notify)(inp, EHOSTDOWN);
1966                 if (inp != NULL)
1967                         INP_WUNLOCK(inp);
1968         } else if (inp != NULL)  {
1969                 if (!(inp->inp_flags & INP_TIMEWAIT) &&
1970                     !(inp->inp_flags & INP_DROPPED) &&
1971                     !(inp->inp_socket == NULL)) {
1972                         icmp_tcp_seq = ntohl(th->th_seq);
1973                         tp = intotcpcb(inp);
1974                         if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
1975                             SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
1976                                 if (cmd == PRC_MSGSIZE) {
1977                                         /*
1978                                          * MTU discovery:
1979                                          * If we got a needfrag set the MTU
1980                                          * in the route to the suggested new
1981                                          * value (if given) and then notify.
1982                                          */
1983                                         mtu = ntohs(icp->icmp_nextmtu);
1984                                         /*
1985                                          * If no alternative MTU was
1986                                          * proposed, try the next smaller
1987                                          * one.
1988                                          */
1989                                         if (!mtu)
1990                                                 mtu = ip_next_mtu(
1991                                                     ntohs(ip->ip_len), 1);
1992                                         if (mtu < V_tcp_minmss +
1993                                             sizeof(struct tcpiphdr))
1994                                                 mtu = V_tcp_minmss +
1995                                                     sizeof(struct tcpiphdr);
1996                                         /*
1997                                          * Only process the offered MTU if it
1998                                          * is smaller than the current one.
1999                                          */
2000                                         if (mtu < tp->t_maxseg +
2001                                             sizeof(struct tcpiphdr)) {
2002                                                 bzero(&inc, sizeof(inc));
2003                                                 inc.inc_faddr = faddr;
2004                                                 inc.inc_fibnum =
2005                                                     inp->inp_inc.inc_fibnum;
2006                                                 tcp_hc_updatemtu(&inc, mtu);
2007                                                 tcp_mtudisc(inp, mtu);
2008                                         }
2009                                 } else
2010                                         inp = (*notify)(inp,
2011                                             inetctlerrmap[cmd]);
2012                         }
2013                 }
2014                 if (inp != NULL)
2015                         INP_WUNLOCK(inp);
2016         } else {
2017                 bzero(&inc, sizeof(inc));
2018                 inc.inc_fport = th->th_dport;
2019                 inc.inc_lport = th->th_sport;
2020                 inc.inc_faddr = faddr;
2021                 inc.inc_laddr = ip->ip_src;
2022                 syncache_unreach(&inc, th);
2023         }
2024         INP_INFO_RUNLOCK(&V_tcbinfo);
2025 }
2026 #endif /* INET */
2027
2028 #ifdef INET6
2029 void
2030 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
2031 {
2032         struct in6_addr *dst;
2033         struct tcphdr *th;
2034         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
2035         struct ip6_hdr *ip6;
2036         struct mbuf *m;
2037         struct inpcb *inp;
2038         struct tcpcb *tp;
2039         struct icmp6_hdr *icmp6;
2040         struct ip6ctlparam *ip6cp = NULL;
2041         const struct sockaddr_in6 *sa6_src = NULL;
2042         struct in_conninfo inc;
2043         tcp_seq icmp_tcp_seq;
2044         unsigned int mtu;
2045         unsigned int off;
2046
2047
2048         if (sa->sa_family != AF_INET6 ||
2049             sa->sa_len != sizeof(struct sockaddr_in6))
2050                 return;
2051
2052         /* if the parameter is from icmp6, decode it. */
2053         if (d != NULL) {
2054                 ip6cp = (struct ip6ctlparam *)d;
2055                 icmp6 = ip6cp->ip6c_icmp6;
2056                 m = ip6cp->ip6c_m;
2057                 ip6 = ip6cp->ip6c_ip6;
2058                 off = ip6cp->ip6c_off;
2059                 sa6_src = ip6cp->ip6c_src;
2060                 dst = ip6cp->ip6c_finaldst;
2061         } else {
2062                 m = NULL;
2063                 ip6 = NULL;
2064                 off = 0;        /* fool gcc */
2065                 sa6_src = &sa6_any;
2066                 dst = NULL;
2067         }
2068
2069         if (cmd == PRC_MSGSIZE)
2070                 notify = tcp_mtudisc_notify;
2071         else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
2072                 cmd == PRC_UNREACH_PORT || cmd == PRC_UNREACH_PROTOCOL ||
2073                 cmd == PRC_TIMXCEED_INTRANS) && ip6 != NULL)
2074                 notify = tcp_drop_syn_sent;
2075
2076         /*
2077          * Hostdead is ugly because it goes linearly through all PCBs.
2078          * XXX: We never get this from ICMP, otherwise it makes an
2079          * excellent DoS attack on machines with many connections.
2080          */
2081         else if (cmd == PRC_HOSTDEAD)
2082                 ip6 = NULL;
2083         else if ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)
2084                 return;
2085
2086         if (ip6 == NULL) {
2087                 in6_pcbnotify(&V_tcbinfo, sa, 0,
2088                               (const struct sockaddr *)sa6_src,
2089                               0, cmd, NULL, notify);
2090                 return;
2091         }
2092
2093         /* Check if we can safely get the ports from the tcp hdr */
2094         if (m == NULL ||
2095             (m->m_pkthdr.len <
2096                 (int32_t) (off + offsetof(struct tcphdr, th_seq)))) {
2097                 return;
2098         }
2099
2100         th = (struct tcphdr *) mtodo(ip6cp->ip6c_m, ip6cp->ip6c_off);
2101         INP_INFO_RLOCK(&V_tcbinfo);
2102         inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_dst, th->th_dport,
2103             &ip6->ip6_src, th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
2104         if (inp != NULL && PRC_IS_REDIRECT(cmd)) {
2105                 /* signal EHOSTDOWN, as it flushes the cached route */
2106                 inp = (*notify)(inp, EHOSTDOWN);
2107                 if (inp != NULL)
2108                         INP_WUNLOCK(inp);
2109         } else if (inp != NULL)  {
2110                 if (!(inp->inp_flags & INP_TIMEWAIT) &&
2111                     !(inp->inp_flags & INP_DROPPED) &&
2112                     !(inp->inp_socket == NULL)) {
2113                         icmp_tcp_seq = ntohl(th->th_seq);
2114                         tp = intotcpcb(inp);
2115                         if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
2116                             SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
2117                                 if (cmd == PRC_MSGSIZE) {
2118                                         /*
2119                                          * MTU discovery:
2120                                          * If we got a needfrag set the MTU
2121                                          * in the route to the suggested new
2122                                          * value (if given) and then notify.
2123                                          */
2124                                         mtu = ntohl(icmp6->icmp6_mtu);
2125                                         /*
2126                                          * If no alternative MTU was
2127                                          * proposed, or the proposed
2128                                          * MTU was too small, set to
2129                                          * the min.
2130                                          */
2131                                         if (mtu < IPV6_MMTU)
2132                                                 mtu = IPV6_MMTU - 8;
2133
2134
2135                                         bzero(&inc, sizeof(inc));
2136                                         inc.inc_fibnum = M_GETFIB(m);
2137                                         inc.inc_flags |= INC_ISIPV6;
2138                                         inc.inc6_faddr = *dst;
2139                                         if (in6_setscope(&inc.inc6_faddr,
2140                                                 m->m_pkthdr.rcvif, NULL))
2141                                                 goto unlock_inp;
2142
2143                                         /*
2144                                          * Only process the offered MTU if it
2145                                          * is smaller than the current one.
2146                                          */
2147                                         if (mtu < tp->t_maxseg +
2148                                             (sizeof (*th) + sizeof (*ip6))) {
2149                                                 tcp_hc_updatemtu(&inc, mtu);
2150                                                 tcp_mtudisc(inp, mtu);
2151                                                 ICMP6STAT_INC(icp6s_pmtuchg);
2152                                         }
2153                                 } else
2154                                         inp = (*notify)(inp,
2155                                             inet6ctlerrmap[cmd]);
2156                         }
2157                 }
2158 unlock_inp:
2159                 if (inp != NULL)
2160                         INP_WUNLOCK(inp);
2161         } else {
2162                 bzero(&inc, sizeof(inc));
2163                 inc.inc_fibnum = M_GETFIB(m);
2164                 inc.inc_flags |= INC_ISIPV6;
2165                 inc.inc_fport = th->th_dport;
2166                 inc.inc_lport = th->th_sport;
2167                 inc.inc6_faddr = *dst;
2168                 inc.inc6_laddr = ip6->ip6_src;
2169                 syncache_unreach(&inc, th);
2170         }
2171         INP_INFO_RUNLOCK(&V_tcbinfo);
2172 }
2173 #endif /* INET6 */
2174
2175
2176 /*
2177  * Following is where TCP initial sequence number generation occurs.
2178  *
2179  * There are two places where we must use initial sequence numbers:
2180  * 1.  In SYN-ACK packets.
2181  * 2.  In SYN packets.
2182  *
2183  * All ISNs for SYN-ACK packets are generated by the syncache.  See
2184  * tcp_syncache.c for details.
2185  *
2186  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
2187  * depends on this property.  In addition, these ISNs should be
2188  * unguessable so as to prevent connection hijacking.  To satisfy
2189  * the requirements of this situation, the algorithm outlined in
2190  * RFC 1948 is used, with only small modifications.
2191  *
2192  * Implementation details:
2193  *
2194  * Time is based off the system timer, and is corrected so that it
2195  * increases by one megabyte per second.  This allows for proper
2196  * recycling on high speed LANs while still leaving over an hour
2197  * before rollover.
2198  *
2199  * As reading the *exact* system time is too expensive to be done
2200  * whenever setting up a TCP connection, we increment the time
2201  * offset in two ways.  First, a small random positive increment
2202  * is added to isn_offset for each connection that is set up.
2203  * Second, the function tcp_isn_tick fires once per clock tick
2204  * and increments isn_offset as necessary so that sequence numbers
2205  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
2206  * random positive increments serve only to ensure that the same
2207  * exact sequence number is never sent out twice (as could otherwise
2208  * happen when a port is recycled in less than the system tick
2209  * interval.)
2210  *
2211  * net.inet.tcp.isn_reseed_interval controls the number of seconds
2212  * between seeding of isn_secret.  This is normally set to zero,
2213  * as reseeding should not be necessary.
2214  *
2215  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
2216  * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock.  In
2217  * general, this means holding an exclusive (write) lock.
2218  */
2219
2220 #define ISN_BYTES_PER_SECOND 1048576
2221 #define ISN_STATIC_INCREMENT 4096
2222 #define ISN_RANDOM_INCREMENT (4096 - 1)
2223
2224 static VNET_DEFINE(u_char, isn_secret[32]);
2225 static VNET_DEFINE(int, isn_last);
2226 static VNET_DEFINE(int, isn_last_reseed);
2227 static VNET_DEFINE(u_int32_t, isn_offset);
2228 static VNET_DEFINE(u_int32_t, isn_offset_old);
2229
2230 #define V_isn_secret                    VNET(isn_secret)
2231 #define V_isn_last                      VNET(isn_last)
2232 #define V_isn_last_reseed               VNET(isn_last_reseed)
2233 #define V_isn_offset                    VNET(isn_offset)
2234 #define V_isn_offset_old                VNET(isn_offset_old)
2235
2236 tcp_seq
2237 tcp_new_isn(struct tcpcb *tp)
2238 {
2239         MD5_CTX isn_ctx;
2240         u_int32_t md5_buffer[4];
2241         tcp_seq new_isn;
2242         u_int32_t projected_offset;
2243
2244         INP_WLOCK_ASSERT(tp->t_inpcb);
2245
2246         ISN_LOCK();
2247         /* Seed if this is the first use, reseed if requested. */
2248         if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
2249              (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
2250                 < (u_int)ticks))) {
2251                 read_random(&V_isn_secret, sizeof(V_isn_secret));
2252                 V_isn_last_reseed = ticks;
2253         }
2254
2255         /* Compute the md5 hash and return the ISN. */
2256         MD5Init(&isn_ctx);
2257         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
2258         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
2259 #ifdef INET6
2260         if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
2261                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
2262                           sizeof(struct in6_addr));
2263                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
2264                           sizeof(struct in6_addr));
2265         } else
2266 #endif
2267         {
2268                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
2269                           sizeof(struct in_addr));
2270                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
2271                           sizeof(struct in_addr));
2272         }
2273         MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret));
2274         MD5Final((u_char *) &md5_buffer, &isn_ctx);
2275         new_isn = (tcp_seq) md5_buffer[0];
2276         V_isn_offset += ISN_STATIC_INCREMENT +
2277                 (arc4random() & ISN_RANDOM_INCREMENT);
2278         if (ticks != V_isn_last) {
2279                 projected_offset = V_isn_offset_old +
2280                     ISN_BYTES_PER_SECOND / hz * (ticks - V_isn_last);
2281                 if (SEQ_GT(projected_offset, V_isn_offset))
2282                         V_isn_offset = projected_offset;
2283                 V_isn_offset_old = V_isn_offset;
2284                 V_isn_last = ticks;
2285         }
2286         new_isn += V_isn_offset;
2287         ISN_UNLOCK();
2288         return (new_isn);
2289 }
2290
2291 /*
2292  * When a specific ICMP unreachable message is received and the
2293  * connection state is SYN-SENT, drop the connection.  This behavior
2294  * is controlled by the icmp_may_rst sysctl.
2295  */
2296 struct inpcb *
2297 tcp_drop_syn_sent(struct inpcb *inp, int errno)
2298 {
2299         struct tcpcb *tp;
2300
2301         INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
2302         INP_WLOCK_ASSERT(inp);
2303
2304         if ((inp->inp_flags & INP_TIMEWAIT) ||
2305             (inp->inp_flags & INP_DROPPED))
2306                 return (inp);
2307
2308         tp = intotcpcb(inp);
2309         if (tp->t_state != TCPS_SYN_SENT)
2310                 return (inp);
2311
2312         tp = tcp_drop(tp, errno);
2313         if (tp != NULL)
2314                 return (inp);
2315         else
2316                 return (NULL);
2317 }
2318
2319 /*
2320  * When `need fragmentation' ICMP is received, update our idea of the MSS
2321  * based on the new value. Also nudge TCP to send something, since we
2322  * know the packet we just sent was dropped.
2323  * This duplicates some code in the tcp_mss() function in tcp_input.c.
2324  */
2325 static struct inpcb *
2326 tcp_mtudisc_notify(struct inpcb *inp, int error)
2327 {
2328
2329         tcp_mtudisc(inp, -1);
2330         return (inp);
2331 }
2332
2333 static void
2334 tcp_mtudisc(struct inpcb *inp, int mtuoffer)
2335 {
2336         struct tcpcb *tp;
2337         struct socket *so;
2338
2339         INP_WLOCK_ASSERT(inp);
2340         if ((inp->inp_flags & INP_TIMEWAIT) ||
2341             (inp->inp_flags & INP_DROPPED))
2342                 return;
2343
2344         tp = intotcpcb(inp);
2345         KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
2346
2347         tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
2348
2349         so = inp->inp_socket;
2350         SOCKBUF_LOCK(&so->so_snd);
2351         /* If the mss is larger than the socket buffer, decrease the mss. */
2352         if (so->so_snd.sb_hiwat < tp->t_maxseg)
2353                 tp->t_maxseg = so->so_snd.sb_hiwat;
2354         SOCKBUF_UNLOCK(&so->so_snd);
2355
2356         TCPSTAT_INC(tcps_mturesent);
2357         tp->t_rtttime = 0;
2358         tp->snd_nxt = tp->snd_una;
2359         tcp_free_sackholes(tp);
2360         tp->snd_recover = tp->snd_max;
2361         if (tp->t_flags & TF_SACK_PERMIT)
2362                 EXIT_FASTRECOVERY(tp->t_flags);
2363         tp->t_fb->tfb_tcp_output(tp);
2364 }
2365
2366 #ifdef INET
2367 /*
2368  * Look-up the routing entry to the peer of this inpcb.  If no route
2369  * is found and it cannot be allocated, then return 0.  This routine
2370  * is called by TCP routines that access the rmx structure and by
2371  * tcp_mss_update to get the peer/interface MTU.
2372  */
2373 uint32_t
2374 tcp_maxmtu(struct in_conninfo *inc, struct tcp_ifcap *cap)
2375 {
2376         struct nhop4_extended nh4;
2377         struct ifnet *ifp;
2378         uint32_t maxmtu = 0;
2379
2380         KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
2381
2382         if (inc->inc_faddr.s_addr != INADDR_ANY) {
2383
2384                 if (fib4_lookup_nh_ext(inc->inc_fibnum, inc->inc_faddr,
2385                     NHR_REF, 0, &nh4) != 0)
2386                         return (0);
2387
2388                 ifp = nh4.nh_ifp;
2389                 maxmtu = nh4.nh_mtu;
2390
2391                 /* Report additional interface capabilities. */
2392                 if (cap != NULL) {
2393                         if (ifp->if_capenable & IFCAP_TSO4 &&
2394                             ifp->if_hwassist & CSUM_TSO) {
2395                                 cap->ifcap |= CSUM_TSO;
2396                                 cap->tsomax = ifp->if_hw_tsomax;
2397                                 cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
2398                                 cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
2399                         }
2400                 }
2401                 fib4_free_nh_ext(inc->inc_fibnum, &nh4);
2402         }
2403         return (maxmtu);
2404 }
2405 #endif /* INET */
2406
2407 #ifdef INET6
2408 uint32_t
2409 tcp_maxmtu6(struct in_conninfo *inc, struct tcp_ifcap *cap)
2410 {
2411         struct nhop6_extended nh6;
2412         struct in6_addr dst6;
2413         uint32_t scopeid;
2414         struct ifnet *ifp;
2415         uint32_t maxmtu = 0;
2416
2417         KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
2418
2419         if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
2420                 in6_splitscope(&inc->inc6_faddr, &dst6, &scopeid);
2421                 if (fib6_lookup_nh_ext(inc->inc_fibnum, &dst6, scopeid, 0,
2422                     0, &nh6) != 0)
2423                         return (0);
2424
2425                 ifp = nh6.nh_ifp;
2426                 maxmtu = nh6.nh_mtu;
2427
2428                 /* Report additional interface capabilities. */
2429                 if (cap != NULL) {
2430                         if (ifp->if_capenable & IFCAP_TSO6 &&
2431                             ifp->if_hwassist & CSUM_TSO) {
2432                                 cap->ifcap |= CSUM_TSO;
2433                                 cap->tsomax = ifp->if_hw_tsomax;
2434                                 cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
2435                                 cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
2436                         }
2437                 }
2438                 fib6_free_nh_ext(inc->inc_fibnum, &nh6);
2439         }
2440
2441         return (maxmtu);
2442 }
2443 #endif /* INET6 */
2444
2445 /*
2446  * Calculate effective SMSS per RFC5681 definition for a given TCP
2447  * connection at its current state, taking into account SACK and etc.
2448  */
2449 u_int
2450 tcp_maxseg(const struct tcpcb *tp)
2451 {
2452         u_int optlen;
2453
2454         if (tp->t_flags & TF_NOOPT)
2455                 return (tp->t_maxseg);
2456
2457         /*
2458          * Here we have a simplified code from tcp_addoptions(),
2459          * without a proper loop, and having most of paddings hardcoded.
2460          * We might make mistakes with padding here in some edge cases,
2461          * but this is harmless, since result of tcp_maxseg() is used
2462          * only in cwnd and ssthresh estimations.
2463          */
2464 #define PAD(len)        ((((len) / 4) + !!((len) % 4)) * 4)
2465         if (TCPS_HAVEESTABLISHED(tp->t_state)) {
2466                 if (tp->t_flags & TF_RCVD_TSTMP)
2467                         optlen = TCPOLEN_TSTAMP_APPA;
2468                 else
2469                         optlen = 0;
2470 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
2471                 if (tp->t_flags & TF_SIGNATURE)
2472                         optlen += PAD(TCPOLEN_SIGNATURE);
2473 #endif
2474                 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks > 0) {
2475                         optlen += TCPOLEN_SACKHDR;
2476                         optlen += tp->rcv_numsacks * TCPOLEN_SACK;
2477                         optlen = PAD(optlen);
2478                 }
2479         } else {
2480                 if (tp->t_flags & TF_REQ_TSTMP)
2481                         optlen = TCPOLEN_TSTAMP_APPA;
2482                 else
2483                         optlen = PAD(TCPOLEN_MAXSEG);
2484                 if (tp->t_flags & TF_REQ_SCALE)
2485                         optlen += PAD(TCPOLEN_WINDOW);
2486 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
2487                 if (tp->t_flags & TF_SIGNATURE)
2488                         optlen += PAD(TCPOLEN_SIGNATURE);
2489 #endif
2490                 if (tp->t_flags & TF_SACK_PERMIT)
2491                         optlen += PAD(TCPOLEN_SACK_PERMITTED);
2492         }
2493 #undef PAD
2494         optlen = min(optlen, TCP_MAXOLEN);
2495         return (tp->t_maxseg - optlen);
2496 }
2497
2498 static int
2499 sysctl_drop(SYSCTL_HANDLER_ARGS)
2500 {
2501         /* addrs[0] is a foreign socket, addrs[1] is a local one. */
2502         struct sockaddr_storage addrs[2];
2503         struct inpcb *inp;
2504         struct tcpcb *tp;
2505         struct tcptw *tw;
2506         struct sockaddr_in *fin, *lin;
2507 #ifdef INET6
2508         struct sockaddr_in6 *fin6, *lin6;
2509 #endif
2510         int error;
2511
2512         inp = NULL;
2513         fin = lin = NULL;
2514 #ifdef INET6
2515         fin6 = lin6 = NULL;
2516 #endif
2517         error = 0;
2518
2519         if (req->oldptr != NULL || req->oldlen != 0)
2520                 return (EINVAL);
2521         if (req->newptr == NULL)
2522                 return (EPERM);
2523         if (req->newlen < sizeof(addrs))
2524                 return (ENOMEM);
2525         error = SYSCTL_IN(req, &addrs, sizeof(addrs));
2526         if (error)
2527                 return (error);
2528
2529         switch (addrs[0].ss_family) {
2530 #ifdef INET6
2531         case AF_INET6:
2532                 fin6 = (struct sockaddr_in6 *)&addrs[0];
2533                 lin6 = (struct sockaddr_in6 *)&addrs[1];
2534                 if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
2535                     lin6->sin6_len != sizeof(struct sockaddr_in6))
2536                         return (EINVAL);
2537                 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
2538                         if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
2539                                 return (EINVAL);
2540                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
2541                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
2542                         fin = (struct sockaddr_in *)&addrs[0];
2543                         lin = (struct sockaddr_in *)&addrs[1];
2544                         break;
2545                 }
2546                 error = sa6_embedscope(fin6, V_ip6_use_defzone);
2547                 if (error)
2548                         return (error);
2549                 error = sa6_embedscope(lin6, V_ip6_use_defzone);
2550                 if (error)
2551                         return (error);
2552                 break;
2553 #endif
2554 #ifdef INET
2555         case AF_INET:
2556                 fin = (struct sockaddr_in *)&addrs[0];
2557                 lin = (struct sockaddr_in *)&addrs[1];
2558                 if (fin->sin_len != sizeof(struct sockaddr_in) ||
2559                     lin->sin_len != sizeof(struct sockaddr_in))
2560                         return (EINVAL);
2561                 break;
2562 #endif
2563         default:
2564                 return (EINVAL);
2565         }
2566         INP_INFO_RLOCK(&V_tcbinfo);
2567         switch (addrs[0].ss_family) {
2568 #ifdef INET6
2569         case AF_INET6:
2570                 inp = in6_pcblookup(&V_tcbinfo, &fin6->sin6_addr,
2571                     fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port,
2572                     INPLOOKUP_WLOCKPCB, NULL);
2573                 break;
2574 #endif
2575 #ifdef INET
2576         case AF_INET:
2577                 inp = in_pcblookup(&V_tcbinfo, fin->sin_addr, fin->sin_port,
2578                     lin->sin_addr, lin->sin_port, INPLOOKUP_WLOCKPCB, NULL);
2579                 break;
2580 #endif
2581         }
2582         if (inp != NULL) {
2583                 if (inp->inp_flags & INP_TIMEWAIT) {
2584                         /*
2585                          * XXXRW: There currently exists a state where an
2586                          * inpcb is present, but its timewait state has been
2587                          * discarded.  For now, don't allow dropping of this
2588                          * type of inpcb.
2589                          */
2590                         tw = intotw(inp);
2591                         if (tw != NULL)
2592                                 tcp_twclose(tw, 0);
2593                         else
2594                                 INP_WUNLOCK(inp);
2595                 } else if (!(inp->inp_flags & INP_DROPPED) &&
2596                            !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
2597                         tp = intotcpcb(inp);
2598                         tp = tcp_drop(tp, ECONNABORTED);
2599                         if (tp != NULL)
2600                                 INP_WUNLOCK(inp);
2601                 } else
2602                         INP_WUNLOCK(inp);
2603         } else
2604                 error = ESRCH;
2605         INP_INFO_RUNLOCK(&V_tcbinfo);
2606         return (error);
2607 }
2608
2609 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
2610     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP, NULL,
2611     0, sysctl_drop, "", "Drop TCP connection");
2612
2613 /*
2614  * Generate a standardized TCP log line for use throughout the
2615  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
2616  * allow use in the interrupt context.
2617  *
2618  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
2619  * NB: The function may return NULL if memory allocation failed.
2620  *
2621  * Due to header inclusion and ordering limitations the struct ip
2622  * and ip6_hdr pointers have to be passed as void pointers.
2623  */
2624 char *
2625 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2626     const void *ip6hdr)
2627 {
2628
2629         /* Is logging enabled? */
2630         if (tcp_log_in_vain == 0)
2631                 return (NULL);
2632
2633         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
2634 }
2635
2636 char *
2637 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2638     const void *ip6hdr)
2639 {
2640
2641         /* Is logging enabled? */
2642         if (tcp_log_debug == 0)
2643                 return (NULL);
2644
2645         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
2646 }
2647
2648 static char *
2649 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2650     const void *ip6hdr)
2651 {
2652         char *s, *sp;
2653         size_t size;
2654         struct ip *ip;
2655 #ifdef INET6
2656         const struct ip6_hdr *ip6;
2657
2658         ip6 = (const struct ip6_hdr *)ip6hdr;
2659 #endif /* INET6 */
2660         ip = (struct ip *)ip4hdr;
2661
2662         /*
2663          * The log line looks like this:
2664          * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
2665          */
2666         size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
2667             sizeof(PRINT_TH_FLAGS) + 1 +
2668 #ifdef INET6
2669             2 * INET6_ADDRSTRLEN;
2670 #else
2671             2 * INET_ADDRSTRLEN;
2672 #endif /* INET6 */
2673
2674         s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
2675         if (s == NULL)
2676                 return (NULL);
2677
2678         strcat(s, "TCP: [");
2679         sp = s + strlen(s);
2680
2681         if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
2682                 inet_ntoa_r(inc->inc_faddr, sp);
2683                 sp = s + strlen(s);
2684                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2685                 sp = s + strlen(s);
2686                 inet_ntoa_r(inc->inc_laddr, sp);
2687                 sp = s + strlen(s);
2688                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2689 #ifdef INET6
2690         } else if (inc) {
2691                 ip6_sprintf(sp, &inc->inc6_faddr);
2692                 sp = s + strlen(s);
2693                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2694                 sp = s + strlen(s);
2695                 ip6_sprintf(sp, &inc->inc6_laddr);
2696                 sp = s + strlen(s);
2697                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2698         } else if (ip6 && th) {
2699                 ip6_sprintf(sp, &ip6->ip6_src);
2700                 sp = s + strlen(s);
2701                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2702                 sp = s + strlen(s);
2703                 ip6_sprintf(sp, &ip6->ip6_dst);
2704                 sp = s + strlen(s);
2705                 sprintf(sp, "]:%i", ntohs(th->th_dport));
2706 #endif /* INET6 */
2707 #ifdef INET
2708         } else if (ip && th) {
2709                 inet_ntoa_r(ip->ip_src, sp);
2710                 sp = s + strlen(s);
2711                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2712                 sp = s + strlen(s);
2713                 inet_ntoa_r(ip->ip_dst, sp);
2714                 sp = s + strlen(s);
2715                 sprintf(sp, "]:%i", ntohs(th->th_dport));
2716 #endif /* INET */
2717         } else {
2718                 free(s, M_TCPLOG);
2719                 return (NULL);
2720         }
2721         sp = s + strlen(s);
2722         if (th)
2723                 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
2724         if (*(s + size - 1) != '\0')
2725                 panic("%s: string too long", __func__);
2726         return (s);
2727 }
2728
2729 /*
2730  * A subroutine which makes it easy to track TCP state changes with DTrace.
2731  * This function shouldn't be called for t_state initializations that don't
2732  * correspond to actual TCP state transitions.
2733  */
2734 void
2735 tcp_state_change(struct tcpcb *tp, int newstate)
2736 {
2737 #if defined(KDTRACE_HOOKS)
2738         int pstate = tp->t_state;
2739 #endif
2740
2741         TCPSTATES_DEC(tp->t_state);
2742         TCPSTATES_INC(newstate);
2743         tp->t_state = newstate;
2744         TCP_PROBE6(state__change, NULL, tp, NULL, tp, NULL, pstate);
2745 }
2746
2747 /*
2748  * Create an external-format (``xtcpcb'') structure using the information in
2749  * the kernel-format tcpcb structure pointed to by tp.  This is done to
2750  * reduce the spew of irrelevant information over this interface, to isolate
2751  * user code from changes in the kernel structure, and potentially to provide
2752  * information-hiding if we decide that some of this information should be
2753  * hidden from users.
2754  */
2755 void
2756 tcp_inptoxtp(const struct inpcb *inp, struct xtcpcb *xt)
2757 {
2758         struct tcpcb *tp = intotcpcb(inp);
2759         sbintime_t now;
2760
2761         if (inp->inp_flags & INP_TIMEWAIT) {
2762                 bzero(xt, sizeof(struct xtcpcb));
2763                 xt->t_state = TCPS_TIME_WAIT;
2764         } else {
2765                 xt->t_state = tp->t_state;
2766                 xt->t_flags = tp->t_flags;
2767                 xt->t_sndzerowin = tp->t_sndzerowin;
2768                 xt->t_sndrexmitpack = tp->t_sndrexmitpack;
2769                 xt->t_rcvoopack = tp->t_rcvoopack;
2770
2771                 now = getsbinuptime();
2772 #define COPYTIMER(ttt)  do {                                            \
2773                 if (callout_active(&tp->t_timers->ttt))                 \
2774                         xt->ttt = (tp->t_timers->ttt.c_time - now) /    \
2775                             SBT_1MS;                                    \
2776                 else                                                    \
2777                         xt->ttt = 0;                                    \
2778 } while (0)
2779                 COPYTIMER(tt_delack);
2780                 COPYTIMER(tt_rexmt);
2781                 COPYTIMER(tt_persist);
2782                 COPYTIMER(tt_keep);
2783                 COPYTIMER(tt_2msl);
2784 #undef COPYTIMER
2785                 xt->t_rcvtime = 1000 * (ticks - tp->t_rcvtime) / hz;
2786
2787                 bcopy(tp->t_fb->tfb_tcp_block_name, xt->xt_stack,
2788                     TCP_FUNCTION_NAME_LEN_MAX);
2789         }
2790
2791         xt->xt_len = sizeof(struct xtcpcb);
2792         in_pcbtoxinpcb(inp, &xt->xt_inp);
2793         if (inp->inp_socket == NULL)
2794                 xt->xt_inp.xi_socket.xso_protocol = IPPROTO_TCP;
2795 }