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 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_inet.h" 38 #include "opt_inet6.h" 39 #include "opt_tcpdebug.h" 40 41 #include <sys/param.h> 42 #include <sys/kernel.h> 43 #include <sys/eventhandler.h> 44 #include <sys/malloc.h> 45 #include <sys/mbuf.h> 46 #include <sys/socket.h> 47 #include <sys/socketvar.h> 48 #include <sys/sysctl.h> 49 #include <sys/syslog.h> 50 #include <sys/systm.h> 51 52 #include <vm/uma.h> 53 54 #include <net/if.h> 55 #include <net/if_var.h> 56 #include <net/route.h> 57 #include <net/vnet.h> 58 59 #include <netinet/in.h> 60 #include <netinet/in_pcb.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/in_var.h> 63 #include <netinet/ip.h> 64 #include <netinet/ip_var.h> 65 #include <netinet/ip_options.h> 66 #include <netinet/ip6.h> 67 #include <netinet6/in6_pcb.h> 68 #include <netinet6/ip6_var.h> 69 #include <netinet6/nd6.h> 70 #include <netinet/tcp.h> 71 #include <netinet/tcp_fsm.h> 72 #include <netinet/tcp_seq.h> 73 #include <netinet/tcp_timer.h> 74 #include <netinet/tcp_var.h> 75 #include <netinet/tcp_log_buf.h> 76 #include <netinet/tcp_hpts.h> 77 #include <netinet6/tcp6_var.h> 78 #include <netinet/tcpip.h> 79 #ifdef TCPDEBUG 80 #include <netinet/tcp_debug.h> 81 #endif /* TCPDEBUG */ 82 83 #define TCP_R_LOG_ADD 1 84 #define TCP_R_LOG_LIMIT_REACHED 2 85 #define TCP_R_LOG_APPEND 3 86 #define TCP_R_LOG_PREPEND 4 87 #define TCP_R_LOG_REPLACE 5 88 #define TCP_R_LOG_MERGE_INTO 6 89 #define TCP_R_LOG_NEW_ENTRY 7 90 #define TCP_R_LOG_READ 8 91 #define TCP_R_LOG_ZERO 9 92 #define TCP_R_LOG_DUMP 10 93 #define TCP_R_LOG_TRIM 11 94 95 /* For debugging we want counters and BB logging */ 96 /* #define TCP_REASS_COUNTERS 1 */ 97 /* #define TCP_REASS_LOGGING 1 */ 98 99 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 100 "TCP Segment Reassembly Queue"); 101 102 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, CTLFLAG_RW, 0, 103 "TCP Segment Reassembly stats"); 104 105 106 static int tcp_reass_maxseg = 0; 107 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 108 &tcp_reass_maxseg, 0, 109 "Global maximum number of TCP Segments in Reassembly Queue"); 110 111 static uma_zone_t tcp_reass_zone; 112 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 113 &tcp_reass_zone, 114 "Global number of TCP Segments currently in Reassembly Queue"); 115 116 static u_int tcp_reass_maxqueuelen = 100; 117 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 118 &tcp_reass_maxqueuelen, 0, 119 "Maximum number of TCP Segments per Reassembly Queue"); 120 121 static int tcp_new_limits = 0; 122 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 123 &tcp_new_limits, 0, 124 "Do we use the new limit method we are discussing?"); 125 126 static u_int tcp_reass_queue_guard = 16; 127 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 128 &tcp_reass_queue_guard, 16, 129 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 130 131 #ifdef TCP_REASS_COUNTERS 132 133 counter_u64_t reass_entry; 134 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 135 &reass_entry, "A segment entered reassembly "); 136 137 counter_u64_t reass_path1; 138 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 139 &reass_path1, "Took path 1"); 140 141 counter_u64_t reass_path2; 142 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 143 &reass_path2, "Took path 2"); 144 145 counter_u64_t reass_path3; 146 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 147 &reass_path3, "Took path 3"); 148 149 counter_u64_t reass_path4; 150 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 151 &reass_path4, "Took path 4"); 152 153 counter_u64_t reass_path5; 154 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 155 &reass_path5, "Took path 5"); 156 157 counter_u64_t reass_path6; 158 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 159 &reass_path6, "Took path 6"); 160 161 counter_u64_t reass_path7; 162 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 163 &reass_path7, "Took path 7"); 164 165 counter_u64_t reass_fullwalk; 166 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 167 &reass_fullwalk, "Took a full walk "); 168 169 counter_u64_t reass_nospace; 170 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 171 &reass_nospace, "Had no mbuf capacity "); 172 173 counter_u64_t merge_fwd; 174 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 175 &merge_fwd, "Ran merge fwd"); 176 177 counter_u64_t merge_into; 178 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 179 &merge_into, "Ran merge into"); 180 181 counter_u64_t tcp_zero_input; 182 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 183 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 184 185 #endif 186 187 /* Initialize TCP reassembly queue */ 188 static void 189 tcp_reass_zone_change(void *tag) 190 { 191 192 /* Set the zone limit and read back the effective value. */ 193 tcp_reass_maxseg = nmbclusters / 16; 194 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 195 tcp_reass_maxseg); 196 } 197 198 #ifdef TCP_REASS_LOGGING 199 200 static void 201 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 202 tcp_seq seq, int len, uint8_t action, int instance) 203 { 204 uint32_t cts; 205 struct timeval tv; 206 207 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 208 union tcp_log_stackspecific log; 209 210 memset(&log, 0, sizeof(log)); 211 cts = tcp_get_usecs(&tv); 212 log.u_bbr.flex1 = seq; 213 log.u_bbr.cur_del_rate = (uint64_t)q; 214 log.u_bbr.delRate = (uint64_t)p; 215 if (q != NULL) { 216 log.u_bbr.flex2 = q->tqe_start; 217 log.u_bbr.flex3 = q->tqe_len; 218 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 219 log.u_bbr.hptsi_gain = q->tqe_flags; 220 } 221 if (p != NULL) { 222 log.u_bbr.flex5 = p->tqe_start; 223 log.u_bbr.pkts_out = p->tqe_len; 224 log.u_bbr.epoch = p->tqe_mbuf_cnt; 225 log.u_bbr.cwnd_gain = p->tqe_flags; 226 } 227 log.u_bbr.flex6 = tp->t_segqmbuflen; 228 log.u_bbr.flex7 = instance; 229 log.u_bbr.flex8 = action; 230 log.u_bbr.timeStamp = cts; 231 TCP_LOG_EVENTP(tp, NULL, 232 &tp->t_inpcb->inp_socket->so_rcv, 233 &tp->t_inpcb->inp_socket->so_snd, 234 TCP_LOG_REASS, 0, 235 len, &log, false, &tv); 236 } 237 } 238 239 static void 240 tcp_reass_log_dump(struct tcpcb *tp) 241 { 242 struct tseg_qent *q; 243 244 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 245 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 246 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 247 } 248 }; 249 } 250 251 static void 252 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 253 int logval, struct tseg_qent *q) 254 { 255 int cnt; 256 struct mbuf *t; 257 258 cnt = 0; 259 t = m; 260 while (t) { 261 cnt += t->m_len; 262 t = t->m_next; 263 } 264 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 265 } 266 267 #endif 268 269 void 270 tcp_reass_global_init(void) 271 { 272 273 tcp_reass_maxseg = nmbclusters / 16; 274 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 275 &tcp_reass_maxseg); 276 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 277 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 278 /* Set the zone limit and read back the effective value. */ 279 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 280 tcp_reass_maxseg); 281 #ifdef TCP_REASS_COUNTERS 282 reass_path1 = counter_u64_alloc(M_WAITOK); 283 reass_path2 = counter_u64_alloc(M_WAITOK); 284 reass_path3 = counter_u64_alloc(M_WAITOK); 285 reass_path4 = counter_u64_alloc(M_WAITOK); 286 reass_path5 = counter_u64_alloc(M_WAITOK); 287 reass_path6 = counter_u64_alloc(M_WAITOK); 288 reass_path7 = counter_u64_alloc(M_WAITOK); 289 reass_fullwalk = counter_u64_alloc(M_WAITOK); 290 reass_nospace = counter_u64_alloc(M_WAITOK); 291 reass_entry = counter_u64_alloc(M_WAITOK); 292 merge_fwd = counter_u64_alloc(M_WAITOK); 293 merge_into = counter_u64_alloc(M_WAITOK); 294 tcp_zero_input = counter_u64_alloc(M_WAITOK); 295 #endif 296 EVENTHANDLER_REGISTER(nmbclusters_change, 297 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 298 299 } 300 301 void 302 tcp_reass_flush(struct tcpcb *tp) 303 { 304 struct tseg_qent *qe; 305 306 INP_WLOCK_ASSERT(tp->t_inpcb); 307 308 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 309 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 310 m_freem(qe->tqe_m); 311 uma_zfree(tcp_reass_zone, qe); 312 tp->t_segqlen--; 313 } 314 tp->t_segqmbuflen = 0; 315 KASSERT((tp->t_segqlen == 0), 316 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 317 tp, tp->t_segqlen)); 318 } 319 320 static void 321 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 322 struct mbuf *m, struct tcphdr *th, int tlen, 323 struct mbuf *mlast, int lenofoh) 324 { 325 326 #ifdef TCP_REASS_LOGGING 327 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 328 #endif 329 last->tqe_len += tlen; 330 last->tqe_m->m_pkthdr.len += tlen; 331 /* Preserve the FIN bit if its there */ 332 last->tqe_flags |= (th->th_flags & TH_FIN); 333 last->tqe_last->m_next = m; 334 last->tqe_last = mlast; 335 last->tqe_mbuf_cnt += lenofoh; 336 tp->t_rcvoopack++; 337 TCPSTAT_INC(tcps_rcvoopack); 338 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 339 #ifdef TCP_REASS_LOGGING 340 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 341 TCP_R_LOG_APPEND, 342 last); 343 #endif 344 } 345 346 static void 347 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 348 int tlen, struct mbuf *mlast, int lenofoh) 349 { 350 int i; 351 352 #ifdef TCP_REASS_LOGGING 353 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 354 #endif 355 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 356 /* The new data overlaps into the old */ 357 i = (th->th_seq + tlen) - first->tqe_start; 358 #ifdef TCP_REASS_LOGGING 359 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 360 #endif 361 m_adj(first->tqe_m, i); 362 first->tqe_len -= i; 363 first->tqe_start += i; 364 } 365 /* Ok now setup our chain to point to the old first */ 366 mlast->m_next = first->tqe_m; 367 first->tqe_m = m; 368 first->tqe_len += tlen; 369 first->tqe_start = th->th_seq; 370 first->tqe_m->m_pkthdr.len = first->tqe_len; 371 first->tqe_mbuf_cnt += lenofoh; 372 tp->t_rcvoopack++; 373 TCPSTAT_INC(tcps_rcvoopack); 374 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 375 #ifdef TCP_REASS_LOGGING 376 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 377 TCP_R_LOG_PREPEND, 378 first); 379 #endif 380 } 381 382 static void 383 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 384 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags) 385 { 386 /* 387 * Free the data in q, and replace 388 * it with the new segment. 389 */ 390 int len_dif; 391 392 #ifdef TCP_REASS_LOGGING 393 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 394 #endif 395 m_freem(q->tqe_m); 396 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 397 ("Tp:%p seg queue goes negative", tp)); 398 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 399 q->tqe_mbuf_cnt = mbufoh; 400 q->tqe_m = m; 401 q->tqe_last = mlast; 402 q->tqe_start = seq; 403 if (len > q->tqe_len) 404 len_dif = len - q->tqe_len; 405 else 406 len_dif = 0; 407 tp->t_rcvoopack++; 408 TCPSTAT_INC(tcps_rcvoopack); 409 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 410 q->tqe_len = len; 411 q->tqe_flags = (flags & TH_FIN); 412 q->tqe_m->m_pkthdr.len = q->tqe_len; 413 tp->t_segqmbuflen += mbufoh; 414 415 } 416 417 static void 418 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 419 struct tseg_qent *q) 420 { 421 /* 422 * Merge q into ent and free q from the list. 423 */ 424 #ifdef TCP_REASS_LOGGING 425 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 426 #endif 427 #ifdef TCP_REASS_COUNTERS 428 counter_u64_add(merge_into, 1); 429 #endif 430 ent->tqe_last->m_next = q->tqe_m; 431 ent->tqe_last = q->tqe_last; 432 ent->tqe_len += q->tqe_len; 433 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 434 ent->tqe_m->m_pkthdr.len += q->tqe_len; 435 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 436 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 437 uma_zfree(tcp_reass_zone, q); 438 tp->t_segqlen--; 439 440 } 441 442 static void 443 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 444 { 445 struct tseg_qent *q, *qtmp; 446 int i; 447 tcp_seq max; 448 /* 449 * Given an entry merge forward anyplace 450 * that ent overlaps forward. 451 */ 452 453 max = ent->tqe_start + ent->tqe_len; 454 q = TAILQ_NEXT(ent, tqe_q); 455 if (q == NULL) { 456 /* Nothing left */ 457 return; 458 } 459 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 460 if (SEQ_GT(q->tqe_start, max)) { 461 /* Beyond q */ 462 break; 463 } 464 /* We have some or all that are overlapping */ 465 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 466 /* It consumes it all */ 467 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 468 m_freem(q->tqe_m); 469 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 470 uma_zfree(tcp_reass_zone, q); 471 tp->t_segqlen--; 472 continue; 473 } 474 /* 475 * Trim the q entry to dovetail to this one 476 * and then merge q into ent updating max 477 * in the process. 478 */ 479 i = max - q->tqe_start; 480 #ifdef TCP_REASS_LOGGING 481 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 482 #endif 483 m_adj(q->tqe_m, i); 484 q->tqe_len -= i; 485 q->tqe_start += i; 486 tcp_reass_merge_into(tp, ent, q); 487 max = ent->tqe_start + ent->tqe_len; 488 } 489 #ifdef TCP_REASS_COUNTERS 490 counter_u64_add(merge_fwd, 1); 491 #endif 492 } 493 494 static int 495 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 496 { 497 int len = MSIZE; 498 499 if (m->m_flags & M_EXT) 500 len += m->m_ext.ext_size; 501 while (m->m_next != NULL) { 502 m = m->m_next; 503 len += MSIZE; 504 if (m->m_flags & M_EXT) 505 len += m->m_ext.ext_size; 506 } 507 *mlast = m; 508 return (len); 509 } 510 511 512 /* 513 * NOTE!!! the new tcp-reassembly code *must not* use 514 * m_adj() with a negative index. That alters the chain 515 * of mbufs (by possibly chopping trailing mbufs). At 516 * the front of tcp_reass we count the mbuf overhead 517 * and setup the tail pointer. If we use m_adj(m, -5) 518 * we could corrupt the tail pointer. Currently the 519 * code only uses m_adj(m, postive-num). If this 520 * changes appropriate changes to update mlast would 521 * be needed. 522 */ 523 int 524 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 525 int *tlenp, struct mbuf *m) 526 { 527 struct tseg_qent *q, *last, *first; 528 struct tseg_qent *p = NULL; 529 struct tseg_qent *nq = NULL; 530 struct tseg_qent *te = NULL; 531 struct mbuf *mlast = NULL; 532 struct sockbuf *sb; 533 struct socket *so = tp->t_inpcb->inp_socket; 534 char *s = NULL; 535 int flags, i, lenofoh; 536 537 INP_WLOCK_ASSERT(tp->t_inpcb); 538 /* 539 * XXX: tcp_reass() is rather inefficient with its data structures 540 * and should be rewritten (see NetBSD for optimizations). 541 */ 542 543 /* 544 * Call with th==NULL after become established to 545 * force pre-ESTABLISHED data up to user socket. 546 */ 547 if (th == NULL) 548 goto present; 549 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 550 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 551 th, tp)); 552 #ifdef TCP_REASS_LOGGING 553 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 554 #endif 555 #ifdef TCP_REASS_COUNTERS 556 counter_u64_add(reass_entry, 1); 557 #endif 558 /* 559 * Check for zero length data. 560 */ 561 if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) { 562 /* 563 * A zero length segment does no 564 * one any good. We could check 565 * the rcv_nxt <-> rcv_wnd but thats 566 * already done for us by the caller. 567 */ 568 #ifdef TCP_REASS_COUNTERS 569 counter_u64_add(tcp_zero_input, 1); 570 #endif 571 m_freem(m); 572 #ifdef TCP_REASS_LOGGING 573 tcp_reass_log_dump(tp); 574 #endif 575 return (0); 576 } 577 /* 578 * Will it fit? 579 */ 580 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 581 sb = &tp->t_inpcb->inp_socket->so_rcv; 582 if ((sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 583 /* No room */ 584 TCPSTAT_INC(tcps_rcvreassfull); 585 #ifdef TCP_REASS_COUNTERS 586 counter_u64_add(reass_nospace, 1); 587 #endif 588 #ifdef TCP_REASS_LOGGING 589 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 590 #endif 591 m_freem(m); 592 *tlenp = 0; 593 #ifdef TCP_REASS_LOGGING 594 tcp_reass_log_dump(tp); 595 #endif 596 return (0); 597 } 598 /* 599 * First lets deal with two common cases, the 600 * segment appends to the back of our collected 601 * segments. Or the segment is the next in line. 602 */ 603 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 604 if (last != NULL) { 605 if ((th->th_flags & TH_FIN) && 606 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 607 /* 608 * Someone is trying to game us, dump 609 * the segment. 610 */ 611 *tlenp = 0; 612 m_freem(m); 613 return (0); 614 } 615 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 616 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 617 /* Common case, trailing segment is added */ 618 /** 619 * +--last 620 * v 621 * reassembly buffer |---| |---| |---| 622 * new segment |---| 623 */ 624 #ifdef TCP_REASS_COUNTERS 625 counter_u64_add(reass_path1, 1); 626 #endif 627 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 628 i = (last->tqe_start + last->tqe_len) - th->th_seq; 629 if (i < *tlenp) { 630 #ifdef TCP_REASS_LOGGING 631 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 632 th->th_seq += i; 633 #endif 634 m_adj(m, i); 635 *tlenp -= i; 636 } else { 637 /* Complete overlap */ 638 TCPSTAT_INC(tcps_rcvduppack); 639 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 640 m_freem(m); 641 *tlenp = last->tqe_len; 642 *seq_start = last->tqe_start; 643 return (0); 644 } 645 } 646 if (last->tqe_flags & TH_FIN) { 647 /* 648 * We have data after the FIN on the last? 649 */ 650 *tlenp = 0; 651 m_freem(m); 652 return(0); 653 } 654 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 655 tp->t_segqmbuflen += lenofoh; 656 *seq_start = last->tqe_start; 657 *tlenp = last->tqe_len; 658 return (0); 659 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 660 /* 661 * Second common case, we missed 662 * another one and have something more 663 * for the end. 664 */ 665 /** 666 * +--last 667 * v 668 * reassembly buffer |---| |---| |---| 669 * new segment |---| 670 */ 671 if (last->tqe_flags & TH_FIN) { 672 /* 673 * We have data after the FIN on the last? 674 */ 675 *tlenp = 0; 676 m_freem(m); 677 return(0); 678 } 679 #ifdef TCP_REASS_COUNTERS 680 counter_u64_add(reass_path2, 1); 681 #endif 682 p = last; 683 goto new_entry; 684 } 685 } else { 686 /* First segment (it's NULL). */ 687 goto new_entry; 688 } 689 first = TAILQ_FIRST(&tp->t_segq); 690 if (SEQ_LT(th->th_seq, first->tqe_start) && 691 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 692 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 693 /* 694 * The head of the queue is prepended by this and 695 * it may be the one I want most. 696 */ 697 /** 698 * first-------+ 699 * v 700 * rea: |---| |---| |---| 701 * new: |---| 702 * Note the case we do not deal with here is: 703 * rea= |---| |---| |---| 704 * new= |----| 705 * Due to the fact that it could be 706 * new |--------------------| 707 * And we might need to merge forward. 708 */ 709 #ifdef INVARIANTS 710 struct mbuf *firstmbuf; 711 #endif 712 713 #ifdef TCP_REASS_COUNTERS 714 counter_u64_add(reass_path3, 1); 715 #endif 716 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 717 /* 718 * The resend was even before 719 * what we have. We need to trim it. 720 * Note TSNH (it should be trimmed 721 * before the call to tcp_reass()). 722 */ 723 #ifdef INVARIANTS 724 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 725 th->th_seq, tp->rcv_nxt, tp); 726 #else 727 i = tp->rcv_nxt - th->th_seq; 728 #ifdef TCP_REASS_LOGGING 729 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 730 #endif 731 m_adj(m, i); 732 th->th_seq += i; 733 *tlenp -= i; 734 #endif 735 } 736 #ifdef INVARIANTS 737 firstmbuf = first->tqe_m; 738 #endif 739 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 740 #ifdef INVARIANTS 741 if (firstmbuf == first->tqe_m) { 742 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 743 m, firstmbuf, first->tqe_m, tp, first); 744 } else if (first->tqe_m != m) { 745 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 746 m, firstmbuf, first->tqe_m, tp, first); 747 } 748 #endif 749 tp->t_segqmbuflen += lenofoh; 750 *seq_start = first->tqe_start; 751 *tlenp = first->tqe_len; 752 goto present; 753 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 754 /* New segment is before our earliest segment. */ 755 /** 756 * first---->+ 757 * v 758 * rea= |---| .... 759 * new" |---| 760 * 761 */ 762 goto new_entry; 763 } 764 /* 765 * Find a segment which begins after this one does. 766 */ 767 #ifdef TCP_REASS_COUNTERS 768 counter_u64_add(reass_fullwalk, 1); 769 #endif 770 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 771 if (SEQ_GT(q->tqe_start, th->th_seq)) 772 break; 773 } 774 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 775 /** 776 * Now is this fit just in-between only? 777 * i.e.: 778 * p---+ +----q 779 * v v 780 * res= |--| |--| |--| 781 * nee |-| 782 */ 783 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 784 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 785 /* Yep no overlap */ 786 goto new_entry; 787 } 788 /** 789 * If we reach here we have some (possibly all) overlap 790 * such as: 791 * res= |--| |--| |--| 792 * new= |----| 793 * or new= |-----------------| 794 * or new= |--------| 795 * or new= |---| 796 * or new= |-----------| 797 */ 798 if ((p != NULL) && 799 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 800 /* conversion to int (in i) handles seq wraparound */ 801 802 #ifdef TCP_REASS_COUNTERS 803 counter_u64_add(reass_path4, 1); 804 #endif 805 i = p->tqe_start + p->tqe_len - th->th_seq; 806 if (i >= 0) { 807 if (i >= *tlenp) { 808 /** 809 * prev seg---->+ 810 * v 811 * reassembly buffer |---| 812 * new segment |-| 813 */ 814 TCPSTAT_INC(tcps_rcvduppack); 815 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 816 *tlenp = p->tqe_len; 817 *seq_start = p->tqe_start; 818 m_freem(m); 819 /* 820 * Try to present any queued data 821 * at the left window edge to the user. 822 * This is needed after the 3-WHS 823 * completes. Note this probably 824 * will not work and we will return. 825 */ 826 return (0); 827 } 828 if (i > 0) { 829 /** 830 * prev seg---->+ 831 * v 832 * reassembly buffer |---| 833 * new segment |-----| 834 */ 835 #ifdef TCP_REASS_COUNTERS 836 counter_u64_add(reass_path5, 1); 837 #endif 838 #ifdef TCP_REASS_LOGGING 839 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 840 #endif 841 m_adj(m, i); 842 *tlenp -= i; 843 th->th_seq += i; 844 } 845 } 846 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 847 /* 848 * If dovetails in with this one 849 * append it. 850 */ 851 /** 852 * prev seg---->+ 853 * v 854 * reassembly buffer |--| |---| 855 * new segment |--| 856 * (note: it was trimmed above if it overlapped) 857 */ 858 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 859 tp->t_segqmbuflen += lenofoh; 860 } else { 861 #ifdef INVARIANTS 862 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 863 th->th_seq, p->tqe_start, p->tqe_len, 864 p, tp); 865 #endif 866 *tlenp = 0; 867 m_freem(m); 868 return (0); 869 } 870 q = p; 871 } else { 872 /* 873 * The new data runs over the 874 * top of previously sack'd data (in q). 875 * It may be partially overlapping, or 876 * it may overlap the entire segment. 877 */ 878 #ifdef TCP_REASS_COUNTERS 879 counter_u64_add(reass_path6, 1); 880 #endif 881 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 882 /* It consumes it all */ 883 /** 884 * next seg---->+ 885 * v 886 * reassembly buffer |--| |---| 887 * new segment |----------| 888 */ 889 #ifdef TCP_REASS_COUNTERS 890 counter_u64_add(reass_path7, 1); 891 #endif 892 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags); 893 } else { 894 /* 895 * We just need to prepend the data 896 * to this. It does not overrun 897 * the end. 898 */ 899 /** 900 * next seg---->+ 901 * v 902 * reassembly buffer |--| |---| 903 * new segment |----------| 904 */ 905 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 906 tp->t_segqmbuflen += lenofoh; 907 } 908 } 909 /* Now does it go further than that? */ 910 tcp_reass_merge_forward(tp, q); 911 *seq_start = q->tqe_start; 912 *tlenp = q->tqe_len; 913 goto present; 914 915 /* 916 * When we reach here we can't combine it 917 * with any existing segment. 918 * 919 * Limit the number of segments that can be queued to reduce the 920 * potential for mbuf exhaustion. For best performance, we want to be 921 * able to queue a full window's worth of segments. The size of the 922 * socket receive buffer determines our advertised window and grows 923 * automatically when socket buffer autotuning is enabled. Use it as the 924 * basis for our queue limit. 925 * 926 * However, allow the user to specify a ceiling for the number of 927 * segments in each queue. 928 * 929 * Always let the missing segment through which caused this queue. 930 * NB: Access to the socket buffer is left intentionally unlocked as we 931 * can tolerate stale information here. 932 * 933 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 934 * should work but causes packets to be dropped when they shouldn't. 935 * Investigate why and re-evaluate the below limit after the behaviour 936 * is understood. 937 */ 938 new_entry: 939 if (tcp_new_limits) { 940 if ((tp->t_segqlen > tcp_reass_queue_guard) && 941 (*tlenp < MSIZE)) { 942 /* 943 * This is really a lie, we are not full but 944 * are getting a segment that is above 945 * guard threshold. If it is and its below 946 * a mbuf size (256) we drop it if it 947 * can't fill in some place. 948 */ 949 TCPSTAT_INC(tcps_rcvreassfull); 950 *tlenp = 0; 951 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 952 log(LOG_DEBUG, "%s; %s: queue limit reached, " 953 "segment dropped\n", s, __func__); 954 free(s, M_TCPLOG); 955 } 956 m_freem(m); 957 #ifdef TCP_REASS_LOGGING 958 tcp_reass_log_dump(tp); 959 #endif 960 return (0); 961 } 962 } else { 963 964 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 965 tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 966 tcp_reass_maxqueuelen)) { 967 TCPSTAT_INC(tcps_rcvreassfull); 968 *tlenp = 0; 969 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 970 log(LOG_DEBUG, "%s; %s: queue limit reached, " 971 "segment dropped\n", s, __func__); 972 free(s, M_TCPLOG); 973 } 974 m_freem(m); 975 #ifdef TCP_REASS_LOGGING 976 tcp_reass_log_dump(tp); 977 #endif 978 return (0); 979 } 980 } 981 /* 982 * Allocate a new queue entry. If we can't, or hit the zone limit 983 * just drop the pkt. 984 */ 985 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 986 if (te == NULL) { 987 TCPSTAT_INC(tcps_rcvmemdrop); 988 m_freem(m); 989 *tlenp = 0; 990 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 991 NULL))) { 992 log(LOG_DEBUG, "%s; %s: global zone limit " 993 "reached, segment dropped\n", s, __func__); 994 free(s, M_TCPLOG); 995 } 996 return (0); 997 } 998 tp->t_segqlen++; 999 tp->t_rcvoopack++; 1000 TCPSTAT_INC(tcps_rcvoopack); 1001 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1002 /* Insert the new segment queue entry into place. */ 1003 te->tqe_m = m; 1004 te->tqe_flags = th->th_flags; 1005 te->tqe_len = *tlenp; 1006 te->tqe_start = th->th_seq; 1007 te->tqe_last = mlast; 1008 te->tqe_mbuf_cnt = lenofoh; 1009 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1010 if (p == NULL) { 1011 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1012 } else { 1013 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1014 } 1015 #ifdef TCP_REASS_LOGGING 1016 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1017 #endif 1018 present: 1019 /* 1020 * Present data to user, advancing rcv_nxt through 1021 * completed sequence space. 1022 */ 1023 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1024 return (0); 1025 q = TAILQ_FIRST(&tp->t_segq); 1026 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1027 ("Reassembly queue for %p has stale entry at head", tp)); 1028 if (!q || q->tqe_start != tp->rcv_nxt) { 1029 #ifdef TCP_REASS_LOGGING 1030 tcp_reass_log_dump(tp); 1031 #endif 1032 return (0); 1033 } 1034 SOCKBUF_LOCK(&so->so_rcv); 1035 do { 1036 tp->rcv_nxt += q->tqe_len; 1037 flags = q->tqe_flags & TH_FIN; 1038 nq = TAILQ_NEXT(q, tqe_q); 1039 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1040 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1041 m_freem(q->tqe_m); 1042 } else { 1043 #ifdef TCP_REASS_LOGGING 1044 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1045 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1046 #endif 1047 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1048 } 1049 #ifdef TCP_REASS_LOGGING 1050 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1051 #endif 1052 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1053 ("tp:%p seg queue goes negative", tp)); 1054 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1055 uma_zfree(tcp_reass_zone, q); 1056 tp->t_segqlen--; 1057 q = nq; 1058 } while (q && q->tqe_start == tp->rcv_nxt); 1059 if (TAILQ_EMPTY(&tp->t_segq) && 1060 (tp->t_segqmbuflen != 0)) { 1061 #ifdef INVARIANTS 1062 panic("tp:%p segq:%p len:%d queue empty", 1063 tp, &tp->t_segq, tp->t_segqmbuflen); 1064 #else 1065 #ifdef TCP_REASS_LOGGING 1066 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1067 #endif 1068 tp->t_segqmbuflen = 0; 1069 #endif 1070 } 1071 #ifdef TCP_REASS_LOGGING 1072 tcp_reass_log_dump(tp); 1073 #endif 1074 sorwakeup_locked(so); 1075 return (flags); 1076 } 1077