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 /* For debugging we want counters and BB logging */ 42 /* #define TCP_REASS_COUNTERS 1 */ 43 /* #define TCP_REASS_LOGGING 1 */ 44 45 #include <sys/param.h> 46 #include <sys/kernel.h> 47 #include <sys/eventhandler.h> 48 #include <sys/malloc.h> 49 #include <sys/mbuf.h> 50 #include <sys/socket.h> 51 #include <sys/socketvar.h> 52 #include <sys/sysctl.h> 53 #include <sys/syslog.h> 54 #include <sys/systm.h> 55 56 #include <vm/uma.h> 57 58 #include <net/if.h> 59 #include <net/if_var.h> 60 #include <net/route.h> 61 #include <net/vnet.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_pcb.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/in_var.h> 67 #include <netinet/ip.h> 68 #include <netinet/ip_var.h> 69 #include <netinet/ip_options.h> 70 #include <netinet/ip6.h> 71 #include <netinet6/in6_pcb.h> 72 #include <netinet6/ip6_var.h> 73 #include <netinet6/nd6.h> 74 #include <netinet/tcp.h> 75 #include <netinet/tcp_fsm.h> 76 #include <netinet/tcp_seq.h> 77 #include <netinet/tcp_timer.h> 78 #include <netinet/tcp_var.h> 79 #ifdef TCP_REASS_LOGGING 80 #include <netinet/tcp_log_buf.h> 81 #include <netinet/tcp_hpts.h> 82 #endif 83 #include <netinet6/tcp6_var.h> 84 #include <netinet/tcpip.h> 85 #ifdef TCPDEBUG 86 #include <netinet/tcp_debug.h> 87 #endif /* TCPDEBUG */ 88 89 #define TCP_R_LOG_ADD 1 90 #define TCP_R_LOG_LIMIT_REACHED 2 91 #define TCP_R_LOG_APPEND 3 92 #define TCP_R_LOG_PREPEND 4 93 #define TCP_R_LOG_REPLACE 5 94 #define TCP_R_LOG_MERGE_INTO 6 95 #define TCP_R_LOG_NEW_ENTRY 7 96 #define TCP_R_LOG_READ 8 97 #define TCP_R_LOG_ZERO 9 98 #define TCP_R_LOG_DUMP 10 99 #define TCP_R_LOG_TRIM 11 100 101 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, 102 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 103 "TCP Segment Reassembly Queue"); 104 105 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, 106 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 107 "TCP Segment Reassembly stats"); 108 109 110 static int tcp_reass_maxseg = 0; 111 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 112 &tcp_reass_maxseg, 0, 113 "Global maximum number of TCP Segments in Reassembly Queue"); 114 115 static uma_zone_t tcp_reass_zone; 116 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 117 &tcp_reass_zone, 118 "Global number of TCP Segments currently in Reassembly Queue"); 119 120 static u_int tcp_reass_maxqueuelen = 100; 121 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 122 &tcp_reass_maxqueuelen, 0, 123 "Maximum number of TCP Segments per Reassembly Queue"); 124 125 static int tcp_new_limits = 0; 126 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 127 &tcp_new_limits, 0, 128 "Do we use the new limit method we are discussing?"); 129 130 static u_int tcp_reass_queue_guard = 16; 131 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 132 &tcp_reass_queue_guard, 16, 133 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 134 135 #ifdef TCP_REASS_COUNTERS 136 137 counter_u64_t reass_entry; 138 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 139 &reass_entry, "A segment entered reassembly "); 140 141 counter_u64_t reass_path1; 142 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 143 &reass_path1, "Took path 1"); 144 145 counter_u64_t reass_path2; 146 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 147 &reass_path2, "Took path 2"); 148 149 counter_u64_t reass_path3; 150 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 151 &reass_path3, "Took path 3"); 152 153 counter_u64_t reass_path4; 154 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 155 &reass_path4, "Took path 4"); 156 157 counter_u64_t reass_path5; 158 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 159 &reass_path5, "Took path 5"); 160 161 counter_u64_t reass_path6; 162 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 163 &reass_path6, "Took path 6"); 164 165 counter_u64_t reass_path7; 166 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 167 &reass_path7, "Took path 7"); 168 169 counter_u64_t reass_fullwalk; 170 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 171 &reass_fullwalk, "Took a full walk "); 172 173 counter_u64_t reass_nospace; 174 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 175 &reass_nospace, "Had no mbuf capacity "); 176 177 counter_u64_t merge_fwd; 178 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 179 &merge_fwd, "Ran merge fwd"); 180 181 counter_u64_t merge_into; 182 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 183 &merge_into, "Ran merge into"); 184 185 counter_u64_t tcp_zero_input; 186 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 187 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 188 189 #endif 190 191 /* Initialize TCP reassembly queue */ 192 static void 193 tcp_reass_zone_change(void *tag) 194 { 195 196 /* Set the zone limit and read back the effective value. */ 197 tcp_reass_maxseg = nmbclusters / 16; 198 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 199 tcp_reass_maxseg); 200 } 201 202 #ifdef TCP_REASS_LOGGING 203 204 static void 205 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 206 tcp_seq seq, int len, uint8_t action, int instance) 207 { 208 uint32_t cts; 209 struct timeval tv; 210 211 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 212 union tcp_log_stackspecific log; 213 214 memset(&log, 0, sizeof(log)); 215 cts = tcp_get_usecs(&tv); 216 log.u_bbr.flex1 = seq; 217 log.u_bbr.cur_del_rate = (uint64_t)q; 218 log.u_bbr.delRate = (uint64_t)p; 219 if (q != NULL) { 220 log.u_bbr.flex2 = q->tqe_start; 221 log.u_bbr.flex3 = q->tqe_len; 222 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 223 log.u_bbr.hptsi_gain = q->tqe_flags; 224 } 225 if (p != NULL) { 226 log.u_bbr.flex5 = p->tqe_start; 227 log.u_bbr.pkts_out = p->tqe_len; 228 log.u_bbr.epoch = p->tqe_mbuf_cnt; 229 log.u_bbr.cwnd_gain = p->tqe_flags; 230 } 231 log.u_bbr.flex6 = tp->t_segqmbuflen; 232 log.u_bbr.flex7 = instance; 233 log.u_bbr.flex8 = action; 234 log.u_bbr.timeStamp = cts; 235 TCP_LOG_EVENTP(tp, NULL, 236 &tp->t_inpcb->inp_socket->so_rcv, 237 &tp->t_inpcb->inp_socket->so_snd, 238 TCP_LOG_REASS, 0, 239 len, &log, false, &tv); 240 } 241 } 242 243 static void 244 tcp_reass_log_dump(struct tcpcb *tp) 245 { 246 struct tseg_qent *q; 247 248 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 249 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 250 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 251 } 252 }; 253 } 254 255 static void 256 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 257 int logval, struct tseg_qent *q) 258 { 259 int cnt; 260 struct mbuf *t; 261 262 cnt = 0; 263 t = m; 264 while (t) { 265 cnt += t->m_len; 266 t = t->m_next; 267 } 268 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 269 } 270 271 #endif 272 273 void 274 tcp_reass_global_init(void) 275 { 276 277 tcp_reass_maxseg = nmbclusters / 16; 278 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 279 &tcp_reass_maxseg); 280 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 281 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 282 /* Set the zone limit and read back the effective value. */ 283 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 284 tcp_reass_maxseg); 285 #ifdef TCP_REASS_COUNTERS 286 reass_path1 = counter_u64_alloc(M_WAITOK); 287 reass_path2 = counter_u64_alloc(M_WAITOK); 288 reass_path3 = counter_u64_alloc(M_WAITOK); 289 reass_path4 = counter_u64_alloc(M_WAITOK); 290 reass_path5 = counter_u64_alloc(M_WAITOK); 291 reass_path6 = counter_u64_alloc(M_WAITOK); 292 reass_path7 = counter_u64_alloc(M_WAITOK); 293 reass_fullwalk = counter_u64_alloc(M_WAITOK); 294 reass_nospace = counter_u64_alloc(M_WAITOK); 295 reass_entry = counter_u64_alloc(M_WAITOK); 296 merge_fwd = counter_u64_alloc(M_WAITOK); 297 merge_into = counter_u64_alloc(M_WAITOK); 298 tcp_zero_input = counter_u64_alloc(M_WAITOK); 299 #endif 300 EVENTHANDLER_REGISTER(nmbclusters_change, 301 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 302 303 } 304 305 void 306 tcp_reass_flush(struct tcpcb *tp) 307 { 308 struct tseg_qent *qe; 309 310 INP_WLOCK_ASSERT(tp->t_inpcb); 311 312 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 313 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 314 m_freem(qe->tqe_m); 315 uma_zfree(tcp_reass_zone, qe); 316 tp->t_segqlen--; 317 } 318 tp->t_segqmbuflen = 0; 319 KASSERT((tp->t_segqlen == 0), 320 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 321 tp, tp->t_segqlen)); 322 } 323 324 static void 325 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 326 struct mbuf *m, struct tcphdr *th, int tlen, 327 struct mbuf *mlast, int lenofoh) 328 { 329 330 #ifdef TCP_REASS_LOGGING 331 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 332 #endif 333 last->tqe_len += tlen; 334 last->tqe_m->m_pkthdr.len += tlen; 335 /* Preserve the FIN bit if its there */ 336 last->tqe_flags |= (th->th_flags & TH_FIN); 337 last->tqe_last->m_next = m; 338 last->tqe_last = mlast; 339 last->tqe_mbuf_cnt += lenofoh; 340 tp->t_rcvoopack++; 341 TCPSTAT_INC(tcps_rcvoopack); 342 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 343 #ifdef TCP_REASS_LOGGING 344 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 345 TCP_R_LOG_APPEND, 346 last); 347 #endif 348 } 349 350 static void 351 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 352 int tlen, struct mbuf *mlast, int lenofoh) 353 { 354 int i; 355 356 #ifdef TCP_REASS_LOGGING 357 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 358 #endif 359 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 360 /* The new data overlaps into the old */ 361 i = (th->th_seq + tlen) - first->tqe_start; 362 #ifdef TCP_REASS_LOGGING 363 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 364 #endif 365 m_adj(first->tqe_m, i); 366 first->tqe_len -= i; 367 first->tqe_start += i; 368 } 369 /* Ok now setup our chain to point to the old first */ 370 mlast->m_next = first->tqe_m; 371 first->tqe_m = m; 372 first->tqe_len += tlen; 373 first->tqe_start = th->th_seq; 374 first->tqe_m->m_pkthdr.len = first->tqe_len; 375 first->tqe_mbuf_cnt += lenofoh; 376 tp->t_rcvoopack++; 377 TCPSTAT_INC(tcps_rcvoopack); 378 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 379 #ifdef TCP_REASS_LOGGING 380 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 381 TCP_R_LOG_PREPEND, 382 first); 383 #endif 384 } 385 386 static void 387 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 388 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags) 389 { 390 /* 391 * Free the data in q, and replace 392 * it with the new segment. 393 */ 394 int len_dif; 395 396 #ifdef TCP_REASS_LOGGING 397 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 398 #endif 399 m_freem(q->tqe_m); 400 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 401 ("Tp:%p seg queue goes negative", tp)); 402 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 403 q->tqe_mbuf_cnt = mbufoh; 404 q->tqe_m = m; 405 q->tqe_last = mlast; 406 q->tqe_start = seq; 407 if (len > q->tqe_len) 408 len_dif = len - q->tqe_len; 409 else 410 len_dif = 0; 411 tp->t_rcvoopack++; 412 TCPSTAT_INC(tcps_rcvoopack); 413 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 414 q->tqe_len = len; 415 q->tqe_flags = (flags & TH_FIN); 416 q->tqe_m->m_pkthdr.len = q->tqe_len; 417 tp->t_segqmbuflen += mbufoh; 418 419 } 420 421 static void 422 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 423 struct tseg_qent *q) 424 { 425 /* 426 * Merge q into ent and free q from the list. 427 */ 428 #ifdef TCP_REASS_LOGGING 429 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 430 #endif 431 #ifdef TCP_REASS_COUNTERS 432 counter_u64_add(merge_into, 1); 433 #endif 434 ent->tqe_last->m_next = q->tqe_m; 435 ent->tqe_last = q->tqe_last; 436 ent->tqe_len += q->tqe_len; 437 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 438 ent->tqe_m->m_pkthdr.len += q->tqe_len; 439 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 440 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 441 uma_zfree(tcp_reass_zone, q); 442 tp->t_segqlen--; 443 444 } 445 446 static void 447 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 448 { 449 struct tseg_qent *q, *qtmp; 450 int i; 451 tcp_seq max; 452 /* 453 * Given an entry merge forward anyplace 454 * that ent overlaps forward. 455 */ 456 457 max = ent->tqe_start + ent->tqe_len; 458 q = TAILQ_NEXT(ent, tqe_q); 459 if (q == NULL) { 460 /* Nothing left */ 461 return; 462 } 463 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 464 if (SEQ_GT(q->tqe_start, max)) { 465 /* Beyond q */ 466 break; 467 } 468 /* We have some or all that are overlapping */ 469 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 470 /* It consumes it all */ 471 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 472 m_freem(q->tqe_m); 473 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 474 uma_zfree(tcp_reass_zone, q); 475 tp->t_segqlen--; 476 continue; 477 } 478 /* 479 * Trim the q entry to dovetail to this one 480 * and then merge q into ent updating max 481 * in the process. 482 */ 483 i = max - q->tqe_start; 484 #ifdef TCP_REASS_LOGGING 485 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 486 #endif 487 m_adj(q->tqe_m, i); 488 q->tqe_len -= i; 489 q->tqe_start += i; 490 tcp_reass_merge_into(tp, ent, q); 491 max = ent->tqe_start + ent->tqe_len; 492 } 493 #ifdef TCP_REASS_COUNTERS 494 counter_u64_add(merge_fwd, 1); 495 #endif 496 } 497 498 static int 499 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 500 { 501 int len = MSIZE; 502 503 if (m->m_flags & M_EXT) 504 len += m->m_ext.ext_size; 505 while (m->m_next != NULL) { 506 m = m->m_next; 507 len += MSIZE; 508 if (m->m_flags & M_EXT) 509 len += m->m_ext.ext_size; 510 } 511 *mlast = m; 512 return (len); 513 } 514 515 516 /* 517 * NOTE!!! the new tcp-reassembly code *must not* use 518 * m_adj() with a negative index. That alters the chain 519 * of mbufs (by possibly chopping trailing mbufs). At 520 * the front of tcp_reass we count the mbuf overhead 521 * and setup the tail pointer. If we use m_adj(m, -5) 522 * we could corrupt the tail pointer. Currently the 523 * code only uses m_adj(m, postive-num). If this 524 * changes appropriate changes to update mlast would 525 * be needed. 526 */ 527 int 528 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 529 int *tlenp, struct mbuf *m) 530 { 531 struct tseg_qent *q, *last, *first; 532 struct tseg_qent *p = NULL; 533 struct tseg_qent *nq = NULL; 534 struct tseg_qent *te = NULL; 535 struct mbuf *mlast = NULL; 536 struct sockbuf *sb; 537 struct socket *so = tp->t_inpcb->inp_socket; 538 char *s = NULL; 539 int flags, i, lenofoh; 540 541 INP_WLOCK_ASSERT(tp->t_inpcb); 542 /* 543 * XXX: tcp_reass() is rather inefficient with its data structures 544 * and should be rewritten (see NetBSD for optimizations). 545 */ 546 547 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), 548 ("tcp_reass called with illegal parameter combination " 549 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", 550 tp, th, seq_start, tlenp, m)); 551 /* 552 * Call with th==NULL after become established to 553 * force pre-ESTABLISHED data up to user socket. 554 */ 555 if (th == NULL) 556 goto present; 557 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 558 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 559 th, tp)); 560 #ifdef TCP_REASS_LOGGING 561 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 562 #endif 563 #ifdef TCP_REASS_COUNTERS 564 counter_u64_add(reass_entry, 1); 565 #endif 566 /* 567 * Check for zero length data. 568 */ 569 if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) { 570 /* 571 * A zero length segment does no 572 * one any good. We could check 573 * the rcv_nxt <-> rcv_wnd but thats 574 * already done for us by the caller. 575 */ 576 #ifdef TCP_REASS_COUNTERS 577 counter_u64_add(tcp_zero_input, 1); 578 #endif 579 m_freem(m); 580 #ifdef TCP_REASS_LOGGING 581 tcp_reass_log_dump(tp); 582 #endif 583 return (0); 584 } 585 /* 586 * Will it fit? 587 */ 588 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 589 sb = &tp->t_inpcb->inp_socket->so_rcv; 590 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 591 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 592 /* No room */ 593 TCPSTAT_INC(tcps_rcvreassfull); 594 #ifdef TCP_REASS_COUNTERS 595 counter_u64_add(reass_nospace, 1); 596 #endif 597 #ifdef TCP_REASS_LOGGING 598 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 599 #endif 600 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 601 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " 602 "segment dropped\n", s, __func__); 603 free(s, M_TCPLOG); 604 } 605 m_freem(m); 606 *tlenp = 0; 607 #ifdef TCP_REASS_LOGGING 608 tcp_reass_log_dump(tp); 609 #endif 610 return (0); 611 } 612 /* 613 * First lets deal with two common cases, the 614 * segment appends to the back of our collected 615 * segments. Or the segment is the next in line. 616 */ 617 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 618 if (last != NULL) { 619 if ((th->th_flags & TH_FIN) && 620 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 621 /* 622 * Someone is trying to game us, dump 623 * the segment. 624 */ 625 *tlenp = 0; 626 m_freem(m); 627 return (0); 628 } 629 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 630 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 631 /* Common case, trailing segment is added */ 632 /** 633 * +--last 634 * v 635 * reassembly buffer |---| |---| |---| 636 * new segment |---| 637 */ 638 #ifdef TCP_REASS_COUNTERS 639 counter_u64_add(reass_path1, 1); 640 #endif 641 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 642 i = (last->tqe_start + last->tqe_len) - th->th_seq; 643 if (i < *tlenp) { 644 #ifdef TCP_REASS_LOGGING 645 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 646 th->th_seq += i; 647 #endif 648 m_adj(m, i); 649 *tlenp -= i; 650 } else { 651 /* Complete overlap */ 652 TCPSTAT_INC(tcps_rcvduppack); 653 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 654 m_freem(m); 655 *tlenp = last->tqe_len; 656 *seq_start = last->tqe_start; 657 return (0); 658 } 659 } 660 if (last->tqe_flags & TH_FIN) { 661 /* 662 * We have data after the FIN on the last? 663 */ 664 *tlenp = 0; 665 m_freem(m); 666 return(0); 667 } 668 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 669 tp->t_segqmbuflen += lenofoh; 670 *seq_start = last->tqe_start; 671 *tlenp = last->tqe_len; 672 return (0); 673 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 674 /* 675 * Second common case, we missed 676 * another one and have something more 677 * for the end. 678 */ 679 /** 680 * +--last 681 * v 682 * reassembly buffer |---| |---| |---| 683 * new segment |---| 684 */ 685 if (last->tqe_flags & TH_FIN) { 686 /* 687 * We have data after the FIN on the last? 688 */ 689 *tlenp = 0; 690 m_freem(m); 691 return(0); 692 } 693 #ifdef TCP_REASS_COUNTERS 694 counter_u64_add(reass_path2, 1); 695 #endif 696 p = last; 697 goto new_entry; 698 } 699 } else { 700 /* First segment (it's NULL). */ 701 goto new_entry; 702 } 703 first = TAILQ_FIRST(&tp->t_segq); 704 if (SEQ_LT(th->th_seq, first->tqe_start) && 705 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 706 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 707 /* 708 * The head of the queue is prepended by this and 709 * it may be the one I want most. 710 */ 711 /** 712 * first-------+ 713 * v 714 * rea: |---| |---| |---| 715 * new: |---| 716 * Note the case we do not deal with here is: 717 * rea= |---| |---| |---| 718 * new= |----| 719 * Due to the fact that it could be 720 * new |--------------------| 721 * And we might need to merge forward. 722 */ 723 #ifdef INVARIANTS 724 struct mbuf *firstmbuf; 725 #endif 726 727 #ifdef TCP_REASS_COUNTERS 728 counter_u64_add(reass_path3, 1); 729 #endif 730 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 731 /* 732 * The resend was even before 733 * what we have. We need to trim it. 734 * Note TSNH (it should be trimmed 735 * before the call to tcp_reass()). 736 */ 737 #ifdef INVARIANTS 738 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 739 th->th_seq, tp->rcv_nxt, tp); 740 #else 741 i = tp->rcv_nxt - th->th_seq; 742 #ifdef TCP_REASS_LOGGING 743 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 744 #endif 745 m_adj(m, i); 746 th->th_seq += i; 747 *tlenp -= i; 748 #endif 749 } 750 #ifdef INVARIANTS 751 firstmbuf = first->tqe_m; 752 #endif 753 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 754 #ifdef INVARIANTS 755 if (firstmbuf == first->tqe_m) { 756 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 757 m, firstmbuf, first->tqe_m, tp, first); 758 } else if (first->tqe_m != m) { 759 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 760 m, firstmbuf, first->tqe_m, tp, first); 761 } 762 #endif 763 tp->t_segqmbuflen += lenofoh; 764 *seq_start = first->tqe_start; 765 *tlenp = first->tqe_len; 766 goto present; 767 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 768 /* New segment is before our earliest segment. */ 769 /** 770 * first---->+ 771 * v 772 * rea= |---| .... 773 * new" |---| 774 * 775 */ 776 goto new_entry; 777 } 778 /* 779 * Find a segment which begins after this one does. 780 */ 781 #ifdef TCP_REASS_COUNTERS 782 counter_u64_add(reass_fullwalk, 1); 783 #endif 784 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 785 if (SEQ_GT(q->tqe_start, th->th_seq)) 786 break; 787 } 788 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 789 /** 790 * Now is this fit just in-between only? 791 * i.e.: 792 * p---+ +----q 793 * v v 794 * res= |--| |--| |--| 795 * nee |-| 796 */ 797 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 798 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 799 /* Yep no overlap */ 800 goto new_entry; 801 } 802 /** 803 * If we reach here we have some (possibly all) overlap 804 * such as: 805 * res= |--| |--| |--| 806 * new= |----| 807 * or new= |-----------------| 808 * or new= |--------| 809 * or new= |---| 810 * or new= |-----------| 811 */ 812 if ((p != NULL) && 813 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 814 /* conversion to int (in i) handles seq wraparound */ 815 816 #ifdef TCP_REASS_COUNTERS 817 counter_u64_add(reass_path4, 1); 818 #endif 819 i = p->tqe_start + p->tqe_len - th->th_seq; 820 if (i >= 0) { 821 if (i >= *tlenp) { 822 /** 823 * prev seg---->+ 824 * v 825 * reassembly buffer |---| 826 * new segment |-| 827 */ 828 TCPSTAT_INC(tcps_rcvduppack); 829 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 830 *tlenp = p->tqe_len; 831 *seq_start = p->tqe_start; 832 m_freem(m); 833 /* 834 * Try to present any queued data 835 * at the left window edge to the user. 836 * This is needed after the 3-WHS 837 * completes. Note this probably 838 * will not work and we will return. 839 */ 840 return (0); 841 } 842 if (i > 0) { 843 /** 844 * prev seg---->+ 845 * v 846 * reassembly buffer |---| 847 * new segment |-----| 848 */ 849 #ifdef TCP_REASS_COUNTERS 850 counter_u64_add(reass_path5, 1); 851 #endif 852 #ifdef TCP_REASS_LOGGING 853 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 854 #endif 855 m_adj(m, i); 856 *tlenp -= i; 857 th->th_seq += i; 858 } 859 } 860 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 861 /* 862 * If dovetails in with this one 863 * append it. 864 */ 865 /** 866 * prev seg---->+ 867 * v 868 * reassembly buffer |--| |---| 869 * new segment |--| 870 * (note: it was trimmed above if it overlapped) 871 */ 872 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 873 tp->t_segqmbuflen += lenofoh; 874 } else { 875 #ifdef INVARIANTS 876 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 877 th->th_seq, p->tqe_start, p->tqe_len, 878 p, tp); 879 #endif 880 *tlenp = 0; 881 m_freem(m); 882 return (0); 883 } 884 q = p; 885 } else { 886 /* 887 * The new data runs over the 888 * top of previously sack'd data (in q). 889 * It may be partially overlapping, or 890 * it may overlap the entire segment. 891 */ 892 #ifdef TCP_REASS_COUNTERS 893 counter_u64_add(reass_path6, 1); 894 #endif 895 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 896 /* It consumes it all */ 897 /** 898 * next seg---->+ 899 * v 900 * reassembly buffer |--| |---| 901 * new segment |----------| 902 */ 903 #ifdef TCP_REASS_COUNTERS 904 counter_u64_add(reass_path7, 1); 905 #endif 906 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags); 907 } else { 908 /* 909 * We just need to prepend the data 910 * to this. It does not overrun 911 * the end. 912 */ 913 /** 914 * next seg---->+ 915 * v 916 * reassembly buffer |--| |---| 917 * new segment |----------| 918 */ 919 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 920 tp->t_segqmbuflen += lenofoh; 921 } 922 } 923 /* Now does it go further than that? */ 924 tcp_reass_merge_forward(tp, q); 925 *seq_start = q->tqe_start; 926 *tlenp = q->tqe_len; 927 goto present; 928 929 /* 930 * When we reach here we can't combine it 931 * with any existing segment. 932 * 933 * Limit the number of segments that can be queued to reduce the 934 * potential for mbuf exhaustion. For best performance, we want to be 935 * able to queue a full window's worth of segments. The size of the 936 * socket receive buffer determines our advertised window and grows 937 * automatically when socket buffer autotuning is enabled. Use it as the 938 * basis for our queue limit. 939 * 940 * However, allow the user to specify a ceiling for the number of 941 * segments in each queue. 942 * 943 * Always let the missing segment through which caused this queue. 944 * NB: Access to the socket buffer is left intentionally unlocked as we 945 * can tolerate stale information here. 946 * 947 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 948 * should work but causes packets to be dropped when they shouldn't. 949 * Investigate why and re-evaluate the below limit after the behaviour 950 * is understood. 951 */ 952 new_entry: 953 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { 954 tp->rcv_nxt += *tlenp; 955 flags = th->th_flags & TH_FIN; 956 TCPSTAT_INC(tcps_rcvoopack); 957 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 958 SOCKBUF_LOCK(&so->so_rcv); 959 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 960 m_freem(m); 961 } else { 962 sbappendstream_locked(&so->so_rcv, m, 0); 963 } 964 sorwakeup_locked(so); 965 return (flags); 966 } 967 if (tcp_new_limits) { 968 if ((tp->t_segqlen > tcp_reass_queue_guard) && 969 (*tlenp < MSIZE)) { 970 /* 971 * This is really a lie, we are not full but 972 * are getting a segment that is above 973 * guard threshold. If it is and its below 974 * a mbuf size (256) we drop it if it 975 * can't fill in some place. 976 */ 977 TCPSTAT_INC(tcps_rcvreassfull); 978 *tlenp = 0; 979 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 980 log(LOG_DEBUG, "%s; %s: queue limit reached, " 981 "segment dropped\n", s, __func__); 982 free(s, M_TCPLOG); 983 } 984 m_freem(m); 985 #ifdef TCP_REASS_LOGGING 986 tcp_reass_log_dump(tp); 987 #endif 988 return (0); 989 } 990 } else { 991 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 992 tcp_reass_maxqueuelen)) { 993 TCPSTAT_INC(tcps_rcvreassfull); 994 *tlenp = 0; 995 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 996 log(LOG_DEBUG, "%s; %s: queue limit reached, " 997 "segment dropped\n", s, __func__); 998 free(s, M_TCPLOG); 999 } 1000 m_freem(m); 1001 #ifdef TCP_REASS_LOGGING 1002 tcp_reass_log_dump(tp); 1003 #endif 1004 return (0); 1005 } 1006 } 1007 /* 1008 * Allocate a new queue entry. If we can't, or hit the zone limit 1009 * just drop the pkt. 1010 */ 1011 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 1012 if (te == NULL) { 1013 TCPSTAT_INC(tcps_rcvmemdrop); 1014 m_freem(m); 1015 *tlenp = 0; 1016 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 1017 NULL))) { 1018 log(LOG_DEBUG, "%s; %s: global zone limit " 1019 "reached, segment dropped\n", s, __func__); 1020 free(s, M_TCPLOG); 1021 } 1022 return (0); 1023 } 1024 tp->t_segqlen++; 1025 tp->t_rcvoopack++; 1026 TCPSTAT_INC(tcps_rcvoopack); 1027 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1028 /* Insert the new segment queue entry into place. */ 1029 te->tqe_m = m; 1030 te->tqe_flags = th->th_flags; 1031 te->tqe_len = *tlenp; 1032 te->tqe_start = th->th_seq; 1033 te->tqe_last = mlast; 1034 te->tqe_mbuf_cnt = lenofoh; 1035 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1036 if (p == NULL) { 1037 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1038 } else { 1039 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1040 } 1041 #ifdef TCP_REASS_LOGGING 1042 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1043 #endif 1044 present: 1045 /* 1046 * Present data to user, advancing rcv_nxt through 1047 * completed sequence space. 1048 */ 1049 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1050 return (0); 1051 q = TAILQ_FIRST(&tp->t_segq); 1052 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1053 ("Reassembly queue for %p has stale entry at head", tp)); 1054 if (!q || q->tqe_start != tp->rcv_nxt) { 1055 #ifdef TCP_REASS_LOGGING 1056 tcp_reass_log_dump(tp); 1057 #endif 1058 return (0); 1059 } 1060 SOCKBUF_LOCK(&so->so_rcv); 1061 do { 1062 tp->rcv_nxt += q->tqe_len; 1063 flags = q->tqe_flags & TH_FIN; 1064 nq = TAILQ_NEXT(q, tqe_q); 1065 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1066 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1067 m_freem(q->tqe_m); 1068 } else { 1069 #ifdef TCP_REASS_LOGGING 1070 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1071 if (th != NULL) { 1072 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1073 } else { 1074 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); 1075 } 1076 #endif 1077 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1078 } 1079 #ifdef TCP_REASS_LOGGING 1080 if (th != NULL) { 1081 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1082 } else { 1083 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); 1084 } 1085 #endif 1086 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1087 ("tp:%p seg queue goes negative", tp)); 1088 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1089 uma_zfree(tcp_reass_zone, q); 1090 tp->t_segqlen--; 1091 q = nq; 1092 } while (q && q->tqe_start == tp->rcv_nxt); 1093 if (TAILQ_EMPTY(&tp->t_segq) && 1094 (tp->t_segqmbuflen != 0)) { 1095 #ifdef INVARIANTS 1096 panic("tp:%p segq:%p len:%d queue empty", 1097 tp, &tp->t_segq, tp->t_segqmbuflen); 1098 #else 1099 #ifdef TCP_REASS_LOGGING 1100 if (th != NULL) { 1101 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1102 } else { 1103 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); 1104 } 1105 #endif 1106 tp->t_segqmbuflen = 0; 1107 #endif 1108 } 1109 #ifdef TCP_REASS_LOGGING 1110 tcp_reass_log_dump(tp); 1111 #endif 1112 sorwakeup_locked(so); 1113 return (flags); 1114 } 1115