1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32#include <sys/cdefs.h> 33#include "opt_inet.h" 34#include "opt_inet6.h" 35 36/* For debugging we want counters and BB logging */ 37/* #define TCP_REASS_COUNTERS 1 */ 38/* #define TCP_REASS_LOGGING 1 */ 39 40#include <sys/param.h> 41#include <sys/kernel.h> 42#include <sys/eventhandler.h> 43#include <sys/malloc.h> 44#include <sys/mbuf.h> 45#include <sys/socket.h> 46#include <sys/socketvar.h> 47#include <sys/sysctl.h> 48#include <sys/syslog.h> 49#include <sys/systm.h> 50 51#include <vm/uma.h> 52 53#include <net/if.h> 54#include <net/if_var.h> 55#include <net/route.h> 56#include <net/vnet.h> 57 58#include <netinet/in.h> 59#include <netinet/in_pcb.h> 60#include <netinet/in_systm.h> 61#include <netinet/in_var.h> 62#include <netinet/ip.h> 63#include <netinet/ip_var.h> 64#include <netinet/ip_options.h> 65#include <netinet/ip6.h> 66#include <netinet6/in6_pcb.h> 67#include <netinet6/ip6_var.h> 68#include <netinet6/nd6.h> 69#include <netinet/tcp.h> 70#include <netinet/tcp_fsm.h> 71#include <netinet/tcp_seq.h> 72#include <netinet/tcp_timer.h> 73#include <netinet/tcp_var.h> 74#ifdef TCP_REASS_LOGGING 75#include <netinet/tcp_log_buf.h> 76#include <netinet/tcp_hpts.h> 77#endif 78#include <netinet/tcpip.h> 79 80#define TCP_R_LOG_ADD 1 81#define TCP_R_LOG_LIMIT_REACHED 2 82#define TCP_R_LOG_APPEND 3 83#define TCP_R_LOG_PREPEND 4 84#define TCP_R_LOG_REPLACE 5 85#define TCP_R_LOG_MERGE_INTO 6 86#define TCP_R_LOG_NEW_ENTRY 7 87#define TCP_R_LOG_READ 8 88#define TCP_R_LOG_ZERO 9 89#define TCP_R_LOG_DUMP 10 90#define TCP_R_LOG_TRIM 11 91 92static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, 93 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 94 "TCP Segment Reassembly Queue"); 95 96static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, 97 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 98 "TCP Segment Reassembly stats"); 99 100static int tcp_reass_maxseg = 0; 101SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 102 &tcp_reass_maxseg, 0, 103 "Global maximum number of TCP Segments in Reassembly Queue"); 104 105static uma_zone_t tcp_reass_zone; 106SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 107 &tcp_reass_zone, 108 "Global number of TCP Segments currently in Reassembly Queue"); 109 110static u_int tcp_reass_maxqueuelen = 100; 111SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 112 &tcp_reass_maxqueuelen, 0, 113 "Maximum number of TCP Segments per Reassembly Queue"); 114 115static int tcp_new_limits = 0; 116SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 117 &tcp_new_limits, 0, 118 "Do we use the new limit method we are discussing?"); 119 120static u_int tcp_reass_queue_guard = 16; 121SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 122 &tcp_reass_queue_guard, 16, 123 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 124 125#ifdef TCP_REASS_COUNTERS 126 127counter_u64_t reass_entry; 128SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 129 &reass_entry, "A segment entered reassembly "); 130 131counter_u64_t reass_path1; 132SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 133 &reass_path1, "Took path 1"); 134 135counter_u64_t reass_path2; 136SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 137 &reass_path2, "Took path 2"); 138 139counter_u64_t reass_path3; 140SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 141 &reass_path3, "Took path 3"); 142 143counter_u64_t reass_path4; 144SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 145 &reass_path4, "Took path 4"); 146 147counter_u64_t reass_path5; 148SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 149 &reass_path5, "Took path 5"); 150 151counter_u64_t reass_path6; 152SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 153 &reass_path6, "Took path 6"); 154 155counter_u64_t reass_path7; 156SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 157 &reass_path7, "Took path 7"); 158 159counter_u64_t reass_fullwalk; 160SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 161 &reass_fullwalk, "Took a full walk "); 162 163counter_u64_t reass_nospace; 164SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 165 &reass_nospace, "Had no mbuf capacity "); 166 167counter_u64_t merge_fwd; 168SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 169 &merge_fwd, "Ran merge fwd"); 170 171counter_u64_t merge_into; 172SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 173 &merge_into, "Ran merge into"); 174 175counter_u64_t tcp_zero_input; 176SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 177 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 178 179#endif 180 181/* Initialize TCP reassembly queue */ 182static void 183tcp_reass_zone_change(void *tag) 184{ 185 186 /* Set the zone limit and read back the effective value. */ 187 tcp_reass_maxseg = nmbclusters / 16; 188 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 189 tcp_reass_maxseg); 190} 191 192#ifdef TCP_REASS_LOGGING 193 194static void 195tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 196 tcp_seq seq, int len, uint8_t action, int instance) 197{ 198 struct socket *so = tptosocket(tp); 199 uint32_t cts; 200 struct timeval tv; 201 202 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 203 union tcp_log_stackspecific log; 204 205 memset(&log, 0, sizeof(log)); 206 cts = tcp_get_usecs(&tv); 207 log.u_bbr.flex1 = seq; 208 log.u_bbr.cur_del_rate = (uint64_t)q; 209 log.u_bbr.delRate = (uint64_t)p; 210 if (q != NULL) { 211 log.u_bbr.flex2 = q->tqe_start; 212 log.u_bbr.flex3 = q->tqe_len; 213 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 214 log.u_bbr.hptsi_gain = q->tqe_flags; 215 } 216 if (p != NULL) { 217 log.u_bbr.flex5 = p->tqe_start; 218 log.u_bbr.pkts_out = p->tqe_len; 219 log.u_bbr.epoch = p->tqe_mbuf_cnt; 220 log.u_bbr.cwnd_gain = p->tqe_flags; 221 } 222 log.u_bbr.flex6 = tp->t_segqmbuflen; 223 log.u_bbr.flex7 = instance; 224 log.u_bbr.flex8 = action; 225 log.u_bbr.timeStamp = cts; 226 TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd, 227 TCP_LOG_REASS, 0, 228 len, &log, false, &tv); 229 } 230} 231 232static void 233tcp_reass_log_dump(struct tcpcb *tp) 234{ 235 struct tseg_qent *q; 236 237 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 238 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 239 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 240 } 241 }; 242} 243 244static void 245tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 246 int logval, struct tseg_qent *q) 247{ 248 int cnt; 249 struct mbuf *t; 250 251 cnt = 0; 252 t = m; 253 while (t) { 254 cnt += t->m_len; 255 t = t->m_next; 256 } 257 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 258} 259 260#endif 261 262void 263tcp_reass_global_init(void) 264{ 265 266 tcp_reass_maxseg = nmbclusters / 16; 267 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 268 &tcp_reass_maxseg); 269 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 270 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 271 /* Set the zone limit and read back the effective value. */ 272 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 273 tcp_reass_maxseg); 274#ifdef TCP_REASS_COUNTERS 275 reass_path1 = counter_u64_alloc(M_WAITOK); 276 reass_path2 = counter_u64_alloc(M_WAITOK); 277 reass_path3 = counter_u64_alloc(M_WAITOK); 278 reass_path4 = counter_u64_alloc(M_WAITOK); 279 reass_path5 = counter_u64_alloc(M_WAITOK); 280 reass_path6 = counter_u64_alloc(M_WAITOK); 281 reass_path7 = counter_u64_alloc(M_WAITOK); 282 reass_fullwalk = counter_u64_alloc(M_WAITOK); 283 reass_nospace = counter_u64_alloc(M_WAITOK); 284 reass_entry = counter_u64_alloc(M_WAITOK); 285 merge_fwd = counter_u64_alloc(M_WAITOK); 286 merge_into = counter_u64_alloc(M_WAITOK); 287 tcp_zero_input = counter_u64_alloc(M_WAITOK); 288#endif 289 EVENTHANDLER_REGISTER(nmbclusters_change, 290 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 291 292} 293 294void 295tcp_reass_flush(struct tcpcb *tp) 296{ 297 struct tseg_qent *qe; 298 299 INP_WLOCK_ASSERT(tptoinpcb(tp)); 300 301 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 302 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 303 m_freem(qe->tqe_m); 304 uma_zfree(tcp_reass_zone, qe); 305 tp->t_segqlen--; 306 } 307 tp->t_segqmbuflen = 0; 308 KASSERT((tp->t_segqlen == 0), 309 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 310 tp, tp->t_segqlen)); 311} 312 313static void 314tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 315 struct mbuf *m, struct tcphdr *th, int tlen, 316 struct mbuf *mlast, int lenofoh) 317{ 318 319#ifdef TCP_REASS_LOGGING 320 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 321#endif 322 last->tqe_len += tlen; 323 last->tqe_m->m_pkthdr.len += tlen; 324 /* Preserve the FIN bit if its there */ 325 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN); 326 last->tqe_last->m_next = m; 327 last->tqe_last = mlast; 328 last->tqe_mbuf_cnt += lenofoh; 329 tp->t_rcvoopack++; 330 TCPSTAT_INC(tcps_rcvoopack); 331 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 332#ifdef TCP_REASS_LOGGING 333 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 334 TCP_R_LOG_APPEND, 335 last); 336#endif 337} 338 339static void 340tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 341 int tlen, struct mbuf *mlast, int lenofoh) 342{ 343 int i; 344 345#ifdef TCP_REASS_LOGGING 346 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 347#endif 348 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 349 /* The new data overlaps into the old */ 350 i = (th->th_seq + tlen) - first->tqe_start; 351#ifdef TCP_REASS_LOGGING 352 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 353#endif 354 m_adj(first->tqe_m, i); 355 first->tqe_len -= i; 356 first->tqe_start += i; 357 } 358 /* Ok now setup our chain to point to the old first */ 359 mlast->m_next = first->tqe_m; 360 first->tqe_m = m; 361 first->tqe_len += tlen; 362 first->tqe_start = th->th_seq; 363 first->tqe_m->m_pkthdr.len = first->tqe_len; 364 first->tqe_mbuf_cnt += lenofoh; 365 tp->t_rcvoopack++; 366 TCPSTAT_INC(tcps_rcvoopack); 367 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 368#ifdef TCP_REASS_LOGGING 369 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 370 TCP_R_LOG_PREPEND, 371 first); 372#endif 373} 374 375static void 376tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 377 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags) 378{ 379 /* 380 * Free the data in q, and replace 381 * it with the new segment. 382 */ 383 int len_dif; 384 385#ifdef TCP_REASS_LOGGING 386 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 387#endif 388 m_freem(q->tqe_m); 389 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 390 ("Tp:%p seg queue goes negative", tp)); 391 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 392 q->tqe_mbuf_cnt = mbufoh; 393 q->tqe_m = m; 394 q->tqe_last = mlast; 395 q->tqe_start = seq; 396 if (len > q->tqe_len) 397 len_dif = len - q->tqe_len; 398 else 399 len_dif = 0; 400 tp->t_rcvoopack++; 401 TCPSTAT_INC(tcps_rcvoopack); 402 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 403 q->tqe_len = len; 404 q->tqe_flags = (flags & TH_FIN); 405 q->tqe_m->m_pkthdr.len = q->tqe_len; 406 tp->t_segqmbuflen += mbufoh; 407 408} 409 410static void 411tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 412 struct tseg_qent *q) 413{ 414 /* 415 * Merge q into ent and free q from the list. 416 */ 417#ifdef TCP_REASS_LOGGING 418 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 419#endif 420#ifdef TCP_REASS_COUNTERS 421 counter_u64_add(merge_into, 1); 422#endif 423 ent->tqe_last->m_next = q->tqe_m; 424 ent->tqe_last = q->tqe_last; 425 ent->tqe_len += q->tqe_len; 426 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 427 ent->tqe_m->m_pkthdr.len += q->tqe_len; 428 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 429 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 430 uma_zfree(tcp_reass_zone, q); 431 tp->t_segqlen--; 432 433} 434 435static void 436tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 437{ 438 struct tseg_qent *q, *qtmp; 439 int i; 440 tcp_seq max; 441 /* 442 * Given an entry merge forward anyplace 443 * that ent overlaps forward. 444 */ 445 446 max = ent->tqe_start + ent->tqe_len; 447 q = TAILQ_NEXT(ent, tqe_q); 448 if (q == NULL) { 449 /* Nothing left */ 450 return; 451 } 452 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 453 if (SEQ_GT(q->tqe_start, max)) { 454 /* Beyond q */ 455 break; 456 } 457 /* We have some or all that are overlapping */ 458 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 459 /* It consumes it all */ 460 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 461 m_freem(q->tqe_m); 462 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 463 uma_zfree(tcp_reass_zone, q); 464 tp->t_segqlen--; 465 continue; 466 } 467 /* 468 * Trim the q entry to dovetail to this one 469 * and then merge q into ent updating max 470 * in the process. 471 */ 472 i = max - q->tqe_start; 473#ifdef TCP_REASS_LOGGING 474 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 475#endif 476 m_adj(q->tqe_m, i); 477 q->tqe_len -= i; 478 q->tqe_start += i; 479 tcp_reass_merge_into(tp, ent, q); 480 max = ent->tqe_start + ent->tqe_len; 481 } 482#ifdef TCP_REASS_COUNTERS 483 counter_u64_add(merge_fwd, 1); 484#endif 485} 486 487static int 488tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 489{ 490 int len = MSIZE; 491 492 if (m->m_flags & M_EXT) 493 len += m->m_ext.ext_size; 494 while (m->m_next != NULL) { 495 m = m->m_next; 496 len += MSIZE; 497 if (m->m_flags & M_EXT) 498 len += m->m_ext.ext_size; 499 } 500 *mlast = m; 501 return (len); 502} 503 504/* 505 * NOTE!!! the new tcp-reassembly code *must not* use 506 * m_adj() with a negative index. That alters the chain 507 * of mbufs (by possibly chopping trailing mbufs). At 508 * the front of tcp_reass we count the mbuf overhead 509 * and setup the tail pointer. If we use m_adj(m, -5) 510 * we could corrupt the tail pointer. Currently the 511 * code only uses m_adj(m, postive-num). If this 512 * changes appropriate changes to update mlast would 513 * be needed. 514 */ 515int 516tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 517 int *tlenp, struct mbuf *m) 518{ 519 struct tseg_qent *q, *last, *first; 520 struct tseg_qent *p = NULL; 521 struct tseg_qent *nq = NULL; 522 struct tseg_qent *te = NULL; 523 struct mbuf *mlast = NULL; 524 struct inpcb *inp = tptoinpcb(tp); 525 struct socket *so = tptosocket(tp); 526 struct sockbuf *sb = &so->so_rcv; 527 char *s = NULL; 528 int flags, i, lenofoh; 529 530 INP_WLOCK_ASSERT(inp); 531 /* 532 * XXX: tcp_reass() is rather inefficient with its data structures 533 * and should be rewritten (see NetBSD for optimizations). 534 */ 535 536 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), 537 ("tcp_reass called with illegal parameter combination " 538 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", 539 tp, th, seq_start, tlenp, m)); 540 /* 541 * Call with th==NULL after become established to 542 * force pre-ESTABLISHED data up to user socket. 543 */ 544 if (th == NULL) 545 goto present; 546 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 547 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 548 th, tp)); 549#ifdef TCP_REASS_LOGGING 550 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 551#endif 552#ifdef TCP_REASS_COUNTERS 553 counter_u64_add(reass_entry, 1); 554#endif 555 /* 556 * Check for zero length data. 557 */ 558 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) { 559 /* 560 * A zero length segment does no 561 * one any good. We could check 562 * the rcv_nxt <-> rcv_wnd but thats 563 * already done for us by the caller. 564 */ 565strip_fin: 566#ifdef TCP_REASS_COUNTERS 567 counter_u64_add(tcp_zero_input, 1); 568#endif 569 m_freem(m); 570#ifdef TCP_REASS_LOGGING 571 tcp_reass_log_dump(tp); 572#endif 573 return (0); 574 } else if ((*tlenp == 0) && 575 (tcp_get_flags(th) & TH_FIN) && 576 !TCPS_HAVEESTABLISHED(tp->t_state)) { 577 /* 578 * We have not established, and we 579 * have a FIN and no data. Lets treat 580 * this as the same as if the FIN were 581 * not present. We don't want to save 582 * the FIN bit in a reassembly buffer 583 * we want to get established first before 584 * we do that (the peer will retransmit). 585 */ 586 goto strip_fin; 587 } 588 /* 589 * Will it fit? 590 */ 591 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 592 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 593 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 594 /* No room */ 595 TCPSTAT_INC(tcps_rcvreassfull); 596#ifdef TCP_REASS_COUNTERS 597 counter_u64_add(reass_nospace, 1); 598#endif 599#ifdef TCP_REASS_LOGGING 600 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 601#endif 602 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 603 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " 604 "segment dropped\n", s, __func__); 605 free(s, M_TCPLOG); 606 } 607 m_freem(m); 608 *tlenp = 0; 609#ifdef TCP_REASS_LOGGING 610 tcp_reass_log_dump(tp); 611#endif 612 return (0); 613 } 614 /* 615 * First lets deal with two common cases, the 616 * segment appends to the back of our collected 617 * segments. Or the segment is the next in line. 618 */ 619 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 620 if (last != NULL) { 621 if ((tcp_get_flags(th) & TH_FIN) && 622 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 623 /* 624 * Someone is trying to game us, dump 625 * the segment. 626 */ 627 *tlenp = 0; 628 m_freem(m); 629 return (0); 630 } 631 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 632 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 633 /* Common case, trailing segment is added */ 634 /** 635 * +--last 636 * v 637 * reassembly buffer |---| |---| |---| 638 * new segment |---| 639 */ 640#ifdef TCP_REASS_COUNTERS 641 counter_u64_add(reass_path1, 1); 642#endif 643 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 644 i = (last->tqe_start + last->tqe_len) - th->th_seq; 645 if (i < *tlenp) { 646#ifdef TCP_REASS_LOGGING 647 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 648 th->th_seq += i; 649#endif 650 m_adj(m, i); 651 *tlenp -= i; 652 } else { 653 /* Complete overlap */ 654 TCPSTAT_INC(tcps_rcvduppack); 655 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 656 m_freem(m); 657 *tlenp = last->tqe_len; 658 *seq_start = last->tqe_start; 659 return (0); 660 } 661 } 662 if (last->tqe_flags & TH_FIN) { 663 /* 664 * We have data after the FIN on the last? 665 */ 666 *tlenp = 0; 667 m_freem(m); 668 return(0); 669 } 670 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 671 tp->t_segqmbuflen += lenofoh; 672 *seq_start = last->tqe_start; 673 *tlenp = last->tqe_len; 674 return (0); 675 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 676 /* 677 * Second common case, we missed 678 * another one and have something more 679 * for the end. 680 */ 681 /** 682 * +--last 683 * v 684 * reassembly buffer |---| |---| |---| 685 * new segment |---| 686 */ 687 if (last->tqe_flags & TH_FIN) { 688 /* 689 * We have data after the FIN on the last? 690 */ 691 *tlenp = 0; 692 m_freem(m); 693 return(0); 694 } 695#ifdef TCP_REASS_COUNTERS 696 counter_u64_add(reass_path2, 1); 697#endif 698 p = last; 699 goto new_entry; 700 } 701 } else { 702 /* First segment (it's NULL). */ 703 goto new_entry; 704 } 705 first = TAILQ_FIRST(&tp->t_segq); 706 if (SEQ_LT(th->th_seq, first->tqe_start) && 707 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 708 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 709 /* 710 * The head of the queue is prepended by this and 711 * it may be the one I want most. 712 */ 713 /** 714 * first-------+ 715 * v 716 * rea: |---| |---| |---| 717 * new: |---| 718 * Note the case we do not deal with here is: 719 * rea= |---| |---| |---| 720 * new= |----| 721 * Due to the fact that it could be 722 * new |--------------------| 723 * And we might need to merge forward. 724 */ 725#ifdef INVARIANTS 726 struct mbuf *firstmbuf; 727#endif 728 729#ifdef TCP_REASS_COUNTERS 730 counter_u64_add(reass_path3, 1); 731#endif 732 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 733 /* 734 * The resend was even before 735 * what we have. We need to trim it. 736 * Note TSNH (it should be trimmed 737 * before the call to tcp_reass()). 738 */ 739#ifdef INVARIANTS 740 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 741 th->th_seq, tp->rcv_nxt, tp); 742#else 743 i = tp->rcv_nxt - th->th_seq; 744#ifdef TCP_REASS_LOGGING 745 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 746#endif 747 m_adj(m, i); 748 th->th_seq += i; 749 *tlenp -= i; 750#endif 751 } 752#ifdef INVARIANTS 753 firstmbuf = first->tqe_m; 754#endif 755 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 756#ifdef INVARIANTS 757 if (firstmbuf == first->tqe_m) { 758 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 759 m, firstmbuf, first->tqe_m, tp, first); 760 } else if (first->tqe_m != m) { 761 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 762 m, firstmbuf, first->tqe_m, tp, first); 763 } 764#endif 765 tp->t_segqmbuflen += lenofoh; 766 *seq_start = first->tqe_start; 767 *tlenp = first->tqe_len; 768 goto present; 769 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 770 /* New segment is before our earliest segment. */ 771 /** 772 * first---->+ 773 * v 774 * rea= |---| .... 775 * new" |---| 776 * 777 */ 778 goto new_entry; 779 } 780 /* 781 * Find a segment which begins after this one does. 782 */ 783#ifdef TCP_REASS_COUNTERS 784 counter_u64_add(reass_fullwalk, 1); 785#endif 786 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 787 if (SEQ_GT(q->tqe_start, th->th_seq)) 788 break; 789 } 790 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 791 /** 792 * Now is this fit just in-between only? 793 * i.e.: 794 * p---+ +----q 795 * v v 796 * res= |--| |--| |--| 797 * nee |-| 798 */ 799 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 800 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 801 /* Yep no overlap */ 802 goto new_entry; 803 } 804 /** 805 * If we reach here we have some (possibly all) overlap 806 * such as: 807 * res= |--| |--| |--| 808 * new= |----| 809 * or new= |-----------------| 810 * or new= |--------| 811 * or new= |---| 812 * or new= |-----------| 813 */ 814 if ((p != NULL) && 815 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 816 /* conversion to int (in i) handles seq wraparound */ 817 818#ifdef TCP_REASS_COUNTERS 819 counter_u64_add(reass_path4, 1); 820#endif 821 i = p->tqe_start + p->tqe_len - th->th_seq; 822 if (i >= 0) { 823 if (i >= *tlenp) { 824 /** 825 * prev seg---->+ 826 * v 827 * reassembly buffer |---| 828 * new segment |-| 829 */ 830 TCPSTAT_INC(tcps_rcvduppack); 831 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 832 *tlenp = p->tqe_len; 833 *seq_start = p->tqe_start; 834 m_freem(m); 835 /* 836 * Try to present any queued data 837 * at the left window edge to the user. 838 * This is needed after the 3-WHS 839 * completes. Note this probably 840 * will not work and we will return. 841 */ 842 return (0); 843 } 844 if (i > 0) { 845 /** 846 * prev seg---->+ 847 * v 848 * reassembly buffer |---| 849 * new segment |-----| 850 */ 851#ifdef TCP_REASS_COUNTERS 852 counter_u64_add(reass_path5, 1); 853#endif 854#ifdef TCP_REASS_LOGGING 855 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 856#endif 857 m_adj(m, i); 858 *tlenp -= i; 859 th->th_seq += i; 860 } 861 } 862 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 863 /* 864 * If dovetails in with this one 865 * append it. 866 */ 867 /** 868 * prev seg---->+ 869 * v 870 * reassembly buffer |--| |---| 871 * new segment |--| 872 * (note: it was trimmed above if it overlapped) 873 */ 874 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 875 tp->t_segqmbuflen += lenofoh; 876 } else { 877#ifdef INVARIANTS 878 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 879 th->th_seq, p->tqe_start, p->tqe_len, 880 p, tp); 881#endif 882 *tlenp = 0; 883 m_freem(m); 884 return (0); 885 } 886 q = p; 887 } else { 888 /* 889 * The new data runs over the 890 * top of previously sack'd data (in q). 891 * It may be partially overlapping, or 892 * it may overlap the entire segment. 893 */ 894#ifdef TCP_REASS_COUNTERS 895 counter_u64_add(reass_path6, 1); 896#endif 897 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 898 /* It consumes it all */ 899 /** 900 * next seg---->+ 901 * v 902 * reassembly buffer |--| |---| 903 * new segment |----------| 904 */ 905#ifdef TCP_REASS_COUNTERS 906 counter_u64_add(reass_path7, 1); 907#endif 908 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th)); 909 } else { 910 /* 911 * We just need to prepend the data 912 * to this. It does not overrun 913 * the end. 914 */ 915 /** 916 * next seg---->+ 917 * v 918 * reassembly buffer |--| |---| 919 * new segment |----------| 920 */ 921 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 922 tp->t_segqmbuflen += lenofoh; 923 } 924 } 925 /* Now does it go further than that? */ 926 tcp_reass_merge_forward(tp, q); 927 *seq_start = q->tqe_start; 928 *tlenp = q->tqe_len; 929 goto present; 930 931 /* 932 * When we reach here we can't combine it 933 * with any existing segment. 934 * 935 * Limit the number of segments that can be queued to reduce the 936 * potential for mbuf exhaustion. For best performance, we want to be 937 * able to queue a full window's worth of segments. The size of the 938 * socket receive buffer determines our advertised window and grows 939 * automatically when socket buffer autotuning is enabled. Use it as the 940 * basis for our queue limit. 941 * 942 * However, allow the user to specify a ceiling for the number of 943 * segments in each queue. 944 * 945 * Always let the missing segment through which caused this queue. 946 * NB: Access to the socket buffer is left intentionally unlocked as we 947 * can tolerate stale information here. 948 * 949 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 950 * should work but causes packets to be dropped when they shouldn't. 951 * Investigate why and re-evaluate the below limit after the behaviour 952 * is understood. 953 */ 954new_entry: 955 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { 956 tp->rcv_nxt += *tlenp; 957 flags = tcp_get_flags(th) & TH_FIN; 958 TCPSTAT_INC(tcps_rcvoopack); 959 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 960 SOCKBUF_LOCK(&so->so_rcv); 961 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 962 m_freem(m); 963 } else { 964 sbappendstream_locked(&so->so_rcv, m, 0); 965 } 966 tp->t_flags |= TF_WAKESOR; 967 return (flags); 968 } 969 if (tcp_new_limits) { 970 if ((tp->t_segqlen > tcp_reass_queue_guard) && 971 (*tlenp < MSIZE)) { 972 /* 973 * This is really a lie, we are not full but 974 * are getting a segment that is above 975 * guard threshold. If it is and its below 976 * a mbuf size (256) we drop it if it 977 * can't fill in some place. 978 */ 979 TCPSTAT_INC(tcps_rcvreassfull); 980 *tlenp = 0; 981 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 982 log(LOG_DEBUG, "%s; %s: queue limit reached, " 983 "segment dropped\n", s, __func__); 984 free(s, M_TCPLOG); 985 } 986 m_freem(m); 987#ifdef TCP_REASS_LOGGING 988 tcp_reass_log_dump(tp); 989#endif 990 return (0); 991 } 992 } else { 993 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 994 tcp_reass_maxqueuelen)) { 995 TCPSTAT_INC(tcps_rcvreassfull); 996 *tlenp = 0; 997 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 998 log(LOG_DEBUG, "%s; %s: queue limit reached, " 999 "segment dropped\n", s, __func__); 1000 free(s, M_TCPLOG); 1001 } 1002 m_freem(m); 1003#ifdef TCP_REASS_LOGGING 1004 tcp_reass_log_dump(tp); 1005#endif 1006 return (0); 1007 } 1008 } 1009 /* 1010 * Allocate a new queue entry. If we can't, or hit the zone limit 1011 * just drop the pkt. 1012 */ 1013 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 1014 if (te == NULL) { 1015 TCPSTAT_INC(tcps_rcvmemdrop); 1016 m_freem(m); 1017 *tlenp = 0; 1018 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 1019 log(LOG_DEBUG, "%s; %s: global zone limit " 1020 "reached, segment dropped\n", s, __func__); 1021 free(s, M_TCPLOG); 1022 } 1023 return (0); 1024 } 1025 tp->t_segqlen++; 1026 tp->t_rcvoopack++; 1027 TCPSTAT_INC(tcps_rcvoopack); 1028 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1029 /* Insert the new segment queue entry into place. */ 1030 te->tqe_m = m; 1031 te->tqe_flags = tcp_get_flags(th); 1032 te->tqe_len = *tlenp; 1033 te->tqe_start = th->th_seq; 1034 te->tqe_last = mlast; 1035 te->tqe_mbuf_cnt = lenofoh; 1036 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1037 if (p == NULL) { 1038 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1039 } else { 1040 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1041 } 1042#ifdef TCP_REASS_LOGGING 1043 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1044#endif 1045present: 1046 /* 1047 * Present data to user, advancing rcv_nxt through 1048 * completed sequence space. 1049 */ 1050 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1051 return (0); 1052 q = TAILQ_FIRST(&tp->t_segq); 1053 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1054 ("Reassembly queue for %p has stale entry at head", tp)); 1055 if (!q || q->tqe_start != tp->rcv_nxt) { 1056#ifdef TCP_REASS_LOGGING 1057 tcp_reass_log_dump(tp); 1058#endif 1059 return (0); 1060 } 1061 SOCKBUF_LOCK(&so->so_rcv); 1062 do { 1063 tp->rcv_nxt += q->tqe_len; 1064 flags = q->tqe_flags & TH_FIN; 1065 nq = TAILQ_NEXT(q, tqe_q); 1066 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1067 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1068 m_freem(q->tqe_m); 1069 } else { 1070#ifdef TCP_REASS_LOGGING 1071 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1072 if (th != NULL) { 1073 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1074 } else { 1075 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); 1076 } 1077#endif 1078 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1079 } 1080#ifdef TCP_REASS_LOGGING 1081 if (th != NULL) { 1082 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1083 } else { 1084 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); 1085 } 1086#endif 1087 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1088 ("tp:%p seg queue goes negative", tp)); 1089 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1090 uma_zfree(tcp_reass_zone, q); 1091 tp->t_segqlen--; 1092 q = nq; 1093 } while (q && q->tqe_start == tp->rcv_nxt); 1094 if (TAILQ_EMPTY(&tp->t_segq) && 1095 (tp->t_segqmbuflen != 0)) { 1096#ifdef INVARIANTS 1097 panic("tp:%p segq:%p len:%d queue empty", 1098 tp, &tp->t_segq, tp->t_segqmbuflen); 1099#else 1100#ifdef TCP_REASS_LOGGING 1101 if (th != NULL) { 1102 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1103 } else { 1104 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); 1105 } 1106#endif 1107 tp->t_segqmbuflen = 0; 1108#endif 1109 } 1110#ifdef TCP_REASS_LOGGING 1111 tcp_reass_log_dump(tp); 1112#endif 1113 tp->t_flags |= TF_WAKESOR; 1114 return (flags); 1115} 1116