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 static int tcp_reass_maxseg = 0; 110 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 111 &tcp_reass_maxseg, 0, 112 "Global maximum number of TCP Segments in Reassembly Queue"); 113 114 static uma_zone_t tcp_reass_zone; 115 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 116 &tcp_reass_zone, 117 "Global number of TCP Segments currently in Reassembly Queue"); 118 119 static u_int tcp_reass_maxqueuelen = 100; 120 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 121 &tcp_reass_maxqueuelen, 0, 122 "Maximum number of TCP Segments per Reassembly Queue"); 123 124 static int tcp_new_limits = 0; 125 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 126 &tcp_new_limits, 0, 127 "Do we use the new limit method we are discussing?"); 128 129 static u_int tcp_reass_queue_guard = 16; 130 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 131 &tcp_reass_queue_guard, 16, 132 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 133 134 #ifdef TCP_REASS_COUNTERS 135 136 counter_u64_t reass_entry; 137 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 138 &reass_entry, "A segment entered reassembly "); 139 140 counter_u64_t reass_path1; 141 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 142 &reass_path1, "Took path 1"); 143 144 counter_u64_t reass_path2; 145 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 146 &reass_path2, "Took path 2"); 147 148 counter_u64_t reass_path3; 149 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 150 &reass_path3, "Took path 3"); 151 152 counter_u64_t reass_path4; 153 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 154 &reass_path4, "Took path 4"); 155 156 counter_u64_t reass_path5; 157 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 158 &reass_path5, "Took path 5"); 159 160 counter_u64_t reass_path6; 161 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 162 &reass_path6, "Took path 6"); 163 164 counter_u64_t reass_path7; 165 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 166 &reass_path7, "Took path 7"); 167 168 counter_u64_t reass_fullwalk; 169 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 170 &reass_fullwalk, "Took a full walk "); 171 172 counter_u64_t reass_nospace; 173 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 174 &reass_nospace, "Had no mbuf capacity "); 175 176 counter_u64_t merge_fwd; 177 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 178 &merge_fwd, "Ran merge fwd"); 179 180 counter_u64_t merge_into; 181 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 182 &merge_into, "Ran merge into"); 183 184 counter_u64_t tcp_zero_input; 185 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 186 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 187 188 #endif 189 190 /* Initialize TCP reassembly queue */ 191 static void 192 tcp_reass_zone_change(void *tag) 193 { 194 195 /* Set the zone limit and read back the effective value. */ 196 tcp_reass_maxseg = nmbclusters / 16; 197 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 198 tcp_reass_maxseg); 199 } 200 201 #ifdef TCP_REASS_LOGGING 202 203 static void 204 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 205 tcp_seq seq, int len, uint8_t action, int instance) 206 { 207 uint32_t cts; 208 struct timeval tv; 209 210 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 211 union tcp_log_stackspecific log; 212 213 memset(&log, 0, sizeof(log)); 214 cts = tcp_get_usecs(&tv); 215 log.u_bbr.flex1 = seq; 216 log.u_bbr.cur_del_rate = (uint64_t)q; 217 log.u_bbr.delRate = (uint64_t)p; 218 if (q != NULL) { 219 log.u_bbr.flex2 = q->tqe_start; 220 log.u_bbr.flex3 = q->tqe_len; 221 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 222 log.u_bbr.hptsi_gain = q->tqe_flags; 223 } 224 if (p != NULL) { 225 log.u_bbr.flex5 = p->tqe_start; 226 log.u_bbr.pkts_out = p->tqe_len; 227 log.u_bbr.epoch = p->tqe_mbuf_cnt; 228 log.u_bbr.cwnd_gain = p->tqe_flags; 229 } 230 log.u_bbr.flex6 = tp->t_segqmbuflen; 231 log.u_bbr.flex7 = instance; 232 log.u_bbr.flex8 = action; 233 log.u_bbr.timeStamp = cts; 234 TCP_LOG_EVENTP(tp, NULL, 235 &tp->t_inpcb->inp_socket->so_rcv, 236 &tp->t_inpcb->inp_socket->so_snd, 237 TCP_LOG_REASS, 0, 238 len, &log, false, &tv); 239 } 240 } 241 242 static void 243 tcp_reass_log_dump(struct tcpcb *tp) 244 { 245 struct tseg_qent *q; 246 247 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 248 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 249 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 250 } 251 }; 252 } 253 254 static void 255 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 256 int logval, struct tseg_qent *q) 257 { 258 int cnt; 259 struct mbuf *t; 260 261 cnt = 0; 262 t = m; 263 while (t) { 264 cnt += t->m_len; 265 t = t->m_next; 266 } 267 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 268 } 269 270 #endif 271 272 void 273 tcp_reass_global_init(void) 274 { 275 276 tcp_reass_maxseg = nmbclusters / 16; 277 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 278 &tcp_reass_maxseg); 279 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 280 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 281 /* Set the zone limit and read back the effective value. */ 282 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 283 tcp_reass_maxseg); 284 #ifdef TCP_REASS_COUNTERS 285 reass_path1 = counter_u64_alloc(M_WAITOK); 286 reass_path2 = counter_u64_alloc(M_WAITOK); 287 reass_path3 = counter_u64_alloc(M_WAITOK); 288 reass_path4 = counter_u64_alloc(M_WAITOK); 289 reass_path5 = counter_u64_alloc(M_WAITOK); 290 reass_path6 = counter_u64_alloc(M_WAITOK); 291 reass_path7 = counter_u64_alloc(M_WAITOK); 292 reass_fullwalk = counter_u64_alloc(M_WAITOK); 293 reass_nospace = counter_u64_alloc(M_WAITOK); 294 reass_entry = counter_u64_alloc(M_WAITOK); 295 merge_fwd = counter_u64_alloc(M_WAITOK); 296 merge_into = counter_u64_alloc(M_WAITOK); 297 tcp_zero_input = counter_u64_alloc(M_WAITOK); 298 #endif 299 EVENTHANDLER_REGISTER(nmbclusters_change, 300 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 301 302 } 303 304 void 305 tcp_reass_flush(struct tcpcb *tp) 306 { 307 struct tseg_qent *qe; 308 309 INP_WLOCK_ASSERT(tp->t_inpcb); 310 311 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 312 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 313 m_freem(qe->tqe_m); 314 uma_zfree(tcp_reass_zone, qe); 315 tp->t_segqlen--; 316 } 317 tp->t_segqmbuflen = 0; 318 KASSERT((tp->t_segqlen == 0), 319 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 320 tp, tp->t_segqlen)); 321 } 322 323 static void 324 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 325 struct mbuf *m, struct tcphdr *th, int tlen, 326 struct mbuf *mlast, int lenofoh) 327 { 328 329 #ifdef TCP_REASS_LOGGING 330 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 331 #endif 332 last->tqe_len += tlen; 333 last->tqe_m->m_pkthdr.len += tlen; 334 /* Preserve the FIN bit if its there */ 335 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN); 336 last->tqe_last->m_next = m; 337 last->tqe_last = mlast; 338 last->tqe_mbuf_cnt += lenofoh; 339 tp->t_rcvoopack++; 340 TCPSTAT_INC(tcps_rcvoopack); 341 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 342 #ifdef TCP_REASS_LOGGING 343 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 344 TCP_R_LOG_APPEND, 345 last); 346 #endif 347 } 348 349 static void 350 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 351 int tlen, struct mbuf *mlast, int lenofoh) 352 { 353 int i; 354 355 #ifdef TCP_REASS_LOGGING 356 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 357 #endif 358 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 359 /* The new data overlaps into the old */ 360 i = (th->th_seq + tlen) - first->tqe_start; 361 #ifdef TCP_REASS_LOGGING 362 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 363 #endif 364 m_adj(first->tqe_m, i); 365 first->tqe_len -= i; 366 first->tqe_start += i; 367 } 368 /* Ok now setup our chain to point to the old first */ 369 mlast->m_next = first->tqe_m; 370 first->tqe_m = m; 371 first->tqe_len += tlen; 372 first->tqe_start = th->th_seq; 373 first->tqe_m->m_pkthdr.len = first->tqe_len; 374 first->tqe_mbuf_cnt += lenofoh; 375 tp->t_rcvoopack++; 376 TCPSTAT_INC(tcps_rcvoopack); 377 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 378 #ifdef TCP_REASS_LOGGING 379 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 380 TCP_R_LOG_PREPEND, 381 first); 382 #endif 383 } 384 385 static void 386 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 387 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags) 388 { 389 /* 390 * Free the data in q, and replace 391 * it with the new segment. 392 */ 393 int len_dif; 394 395 #ifdef TCP_REASS_LOGGING 396 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 397 #endif 398 m_freem(q->tqe_m); 399 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 400 ("Tp:%p seg queue goes negative", tp)); 401 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 402 q->tqe_mbuf_cnt = mbufoh; 403 q->tqe_m = m; 404 q->tqe_last = mlast; 405 q->tqe_start = seq; 406 if (len > q->tqe_len) 407 len_dif = len - q->tqe_len; 408 else 409 len_dif = 0; 410 tp->t_rcvoopack++; 411 TCPSTAT_INC(tcps_rcvoopack); 412 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 413 q->tqe_len = len; 414 q->tqe_flags = (flags & TH_FIN); 415 q->tqe_m->m_pkthdr.len = q->tqe_len; 416 tp->t_segqmbuflen += mbufoh; 417 418 } 419 420 static void 421 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 422 struct tseg_qent *q) 423 { 424 /* 425 * Merge q into ent and free q from the list. 426 */ 427 #ifdef TCP_REASS_LOGGING 428 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 429 #endif 430 #ifdef TCP_REASS_COUNTERS 431 counter_u64_add(merge_into, 1); 432 #endif 433 ent->tqe_last->m_next = q->tqe_m; 434 ent->tqe_last = q->tqe_last; 435 ent->tqe_len += q->tqe_len; 436 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 437 ent->tqe_m->m_pkthdr.len += q->tqe_len; 438 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 439 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 440 uma_zfree(tcp_reass_zone, q); 441 tp->t_segqlen--; 442 443 } 444 445 static void 446 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 447 { 448 struct tseg_qent *q, *qtmp; 449 int i; 450 tcp_seq max; 451 /* 452 * Given an entry merge forward anyplace 453 * that ent overlaps forward. 454 */ 455 456 max = ent->tqe_start + ent->tqe_len; 457 q = TAILQ_NEXT(ent, tqe_q); 458 if (q == NULL) { 459 /* Nothing left */ 460 return; 461 } 462 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 463 if (SEQ_GT(q->tqe_start, max)) { 464 /* Beyond q */ 465 break; 466 } 467 /* We have some or all that are overlapping */ 468 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 469 /* It consumes it all */ 470 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 471 m_freem(q->tqe_m); 472 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 473 uma_zfree(tcp_reass_zone, q); 474 tp->t_segqlen--; 475 continue; 476 } 477 /* 478 * Trim the q entry to dovetail to this one 479 * and then merge q into ent updating max 480 * in the process. 481 */ 482 i = max - q->tqe_start; 483 #ifdef TCP_REASS_LOGGING 484 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 485 #endif 486 m_adj(q->tqe_m, i); 487 q->tqe_len -= i; 488 q->tqe_start += i; 489 tcp_reass_merge_into(tp, ent, q); 490 max = ent->tqe_start + ent->tqe_len; 491 } 492 #ifdef TCP_REASS_COUNTERS 493 counter_u64_add(merge_fwd, 1); 494 #endif 495 } 496 497 static int 498 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 499 { 500 int len = MSIZE; 501 502 if (m->m_flags & M_EXT) 503 len += m->m_ext.ext_size; 504 while (m->m_next != NULL) { 505 m = m->m_next; 506 len += MSIZE; 507 if (m->m_flags & M_EXT) 508 len += m->m_ext.ext_size; 509 } 510 *mlast = m; 511 return (len); 512 } 513 514 /* 515 * NOTE!!! the new tcp-reassembly code *must not* use 516 * m_adj() with a negative index. That alters the chain 517 * of mbufs (by possibly chopping trailing mbufs). At 518 * the front of tcp_reass we count the mbuf overhead 519 * and setup the tail pointer. If we use m_adj(m, -5) 520 * we could corrupt the tail pointer. Currently the 521 * code only uses m_adj(m, postive-num). If this 522 * changes appropriate changes to update mlast would 523 * be needed. 524 */ 525 int 526 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 527 int *tlenp, struct mbuf *m) 528 { 529 struct tseg_qent *q, *last, *first; 530 struct tseg_qent *p = NULL; 531 struct tseg_qent *nq = NULL; 532 struct tseg_qent *te = NULL; 533 struct mbuf *mlast = NULL; 534 struct sockbuf *sb; 535 struct socket *so = tp->t_inpcb->inp_socket; 536 char *s = NULL; 537 int flags, i, lenofoh; 538 539 INP_WLOCK_ASSERT(tp->t_inpcb); 540 /* 541 * XXX: tcp_reass() is rather inefficient with its data structures 542 * and should be rewritten (see NetBSD for optimizations). 543 */ 544 545 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), 546 ("tcp_reass called with illegal parameter combination " 547 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", 548 tp, th, seq_start, tlenp, m)); 549 /* 550 * Call with th==NULL after become established to 551 * force pre-ESTABLISHED data up to user socket. 552 */ 553 if (th == NULL) 554 goto present; 555 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 556 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 557 th, tp)); 558 #ifdef TCP_REASS_LOGGING 559 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 560 #endif 561 #ifdef TCP_REASS_COUNTERS 562 counter_u64_add(reass_entry, 1); 563 #endif 564 /* 565 * Check for zero length data. 566 */ 567 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) { 568 /* 569 * A zero length segment does no 570 * one any good. We could check 571 * the rcv_nxt <-> rcv_wnd but thats 572 * already done for us by the caller. 573 */ 574 strip_fin: 575 #ifdef TCP_REASS_COUNTERS 576 counter_u64_add(tcp_zero_input, 1); 577 #endif 578 m_freem(m); 579 #ifdef TCP_REASS_LOGGING 580 tcp_reass_log_dump(tp); 581 #endif 582 return (0); 583 } else if ((*tlenp == 0) && 584 (tcp_get_flags(th) & TH_FIN) && 585 !TCPS_HAVEESTABLISHED(tp->t_state)) { 586 /* 587 * We have not established, and we 588 * have a FIN and no data. Lets treat 589 * this as the same as if the FIN were 590 * not present. We don't want to save 591 * the FIN bit in a reassembly buffer 592 * we want to get established first before 593 * we do that (the peer will retransmit). 594 */ 595 goto strip_fin; 596 } 597 /* 598 * Will it fit? 599 */ 600 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 601 sb = &tp->t_inpcb->inp_socket->so_rcv; 602 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 603 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 604 /* No room */ 605 TCPSTAT_INC(tcps_rcvreassfull); 606 #ifdef TCP_REASS_COUNTERS 607 counter_u64_add(reass_nospace, 1); 608 #endif 609 #ifdef TCP_REASS_LOGGING 610 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 611 #endif 612 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 613 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " 614 "segment dropped\n", s, __func__); 615 free(s, M_TCPLOG); 616 } 617 m_freem(m); 618 *tlenp = 0; 619 #ifdef TCP_REASS_LOGGING 620 tcp_reass_log_dump(tp); 621 #endif 622 return (0); 623 } 624 /* 625 * First lets deal with two common cases, the 626 * segment appends to the back of our collected 627 * segments. Or the segment is the next in line. 628 */ 629 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 630 if (last != NULL) { 631 if ((tcp_get_flags(th) & TH_FIN) && 632 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 633 /* 634 * Someone is trying to game us, dump 635 * the segment. 636 */ 637 *tlenp = 0; 638 m_freem(m); 639 return (0); 640 } 641 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 642 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 643 /* Common case, trailing segment is added */ 644 /** 645 * +--last 646 * v 647 * reassembly buffer |---| |---| |---| 648 * new segment |---| 649 */ 650 #ifdef TCP_REASS_COUNTERS 651 counter_u64_add(reass_path1, 1); 652 #endif 653 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 654 i = (last->tqe_start + last->tqe_len) - th->th_seq; 655 if (i < *tlenp) { 656 #ifdef TCP_REASS_LOGGING 657 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 658 th->th_seq += i; 659 #endif 660 m_adj(m, i); 661 *tlenp -= i; 662 } else { 663 /* Complete overlap */ 664 TCPSTAT_INC(tcps_rcvduppack); 665 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 666 m_freem(m); 667 *tlenp = last->tqe_len; 668 *seq_start = last->tqe_start; 669 return (0); 670 } 671 } 672 if (last->tqe_flags & TH_FIN) { 673 /* 674 * We have data after the FIN on the last? 675 */ 676 *tlenp = 0; 677 m_freem(m); 678 return(0); 679 } 680 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 681 tp->t_segqmbuflen += lenofoh; 682 *seq_start = last->tqe_start; 683 *tlenp = last->tqe_len; 684 return (0); 685 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 686 /* 687 * Second common case, we missed 688 * another one and have something more 689 * for the end. 690 */ 691 /** 692 * +--last 693 * v 694 * reassembly buffer |---| |---| |---| 695 * new segment |---| 696 */ 697 if (last->tqe_flags & TH_FIN) { 698 /* 699 * We have data after the FIN on the last? 700 */ 701 *tlenp = 0; 702 m_freem(m); 703 return(0); 704 } 705 #ifdef TCP_REASS_COUNTERS 706 counter_u64_add(reass_path2, 1); 707 #endif 708 p = last; 709 goto new_entry; 710 } 711 } else { 712 /* First segment (it's NULL). */ 713 goto new_entry; 714 } 715 first = TAILQ_FIRST(&tp->t_segq); 716 if (SEQ_LT(th->th_seq, first->tqe_start) && 717 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 718 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 719 /* 720 * The head of the queue is prepended by this and 721 * it may be the one I want most. 722 */ 723 /** 724 * first-------+ 725 * v 726 * rea: |---| |---| |---| 727 * new: |---| 728 * Note the case we do not deal with here is: 729 * rea= |---| |---| |---| 730 * new= |----| 731 * Due to the fact that it could be 732 * new |--------------------| 733 * And we might need to merge forward. 734 */ 735 #ifdef INVARIANTS 736 struct mbuf *firstmbuf; 737 #endif 738 739 #ifdef TCP_REASS_COUNTERS 740 counter_u64_add(reass_path3, 1); 741 #endif 742 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 743 /* 744 * The resend was even before 745 * what we have. We need to trim it. 746 * Note TSNH (it should be trimmed 747 * before the call to tcp_reass()). 748 */ 749 #ifdef INVARIANTS 750 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 751 th->th_seq, tp->rcv_nxt, tp); 752 #else 753 i = tp->rcv_nxt - th->th_seq; 754 #ifdef TCP_REASS_LOGGING 755 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 756 #endif 757 m_adj(m, i); 758 th->th_seq += i; 759 *tlenp -= i; 760 #endif 761 } 762 #ifdef INVARIANTS 763 firstmbuf = first->tqe_m; 764 #endif 765 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 766 #ifdef INVARIANTS 767 if (firstmbuf == first->tqe_m) { 768 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 769 m, firstmbuf, first->tqe_m, tp, first); 770 } else if (first->tqe_m != m) { 771 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 772 m, firstmbuf, first->tqe_m, tp, first); 773 } 774 #endif 775 tp->t_segqmbuflen += lenofoh; 776 *seq_start = first->tqe_start; 777 *tlenp = first->tqe_len; 778 goto present; 779 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 780 /* New segment is before our earliest segment. */ 781 /** 782 * first---->+ 783 * v 784 * rea= |---| .... 785 * new" |---| 786 * 787 */ 788 goto new_entry; 789 } 790 /* 791 * Find a segment which begins after this one does. 792 */ 793 #ifdef TCP_REASS_COUNTERS 794 counter_u64_add(reass_fullwalk, 1); 795 #endif 796 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 797 if (SEQ_GT(q->tqe_start, th->th_seq)) 798 break; 799 } 800 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 801 /** 802 * Now is this fit just in-between only? 803 * i.e.: 804 * p---+ +----q 805 * v v 806 * res= |--| |--| |--| 807 * nee |-| 808 */ 809 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 810 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 811 /* Yep no overlap */ 812 goto new_entry; 813 } 814 /** 815 * If we reach here we have some (possibly all) overlap 816 * such as: 817 * res= |--| |--| |--| 818 * new= |----| 819 * or new= |-----------------| 820 * or new= |--------| 821 * or new= |---| 822 * or new= |-----------| 823 */ 824 if ((p != NULL) && 825 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 826 /* conversion to int (in i) handles seq wraparound */ 827 828 #ifdef TCP_REASS_COUNTERS 829 counter_u64_add(reass_path4, 1); 830 #endif 831 i = p->tqe_start + p->tqe_len - th->th_seq; 832 if (i >= 0) { 833 if (i >= *tlenp) { 834 /** 835 * prev seg---->+ 836 * v 837 * reassembly buffer |---| 838 * new segment |-| 839 */ 840 TCPSTAT_INC(tcps_rcvduppack); 841 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 842 *tlenp = p->tqe_len; 843 *seq_start = p->tqe_start; 844 m_freem(m); 845 /* 846 * Try to present any queued data 847 * at the left window edge to the user. 848 * This is needed after the 3-WHS 849 * completes. Note this probably 850 * will not work and we will return. 851 */ 852 return (0); 853 } 854 if (i > 0) { 855 /** 856 * prev seg---->+ 857 * v 858 * reassembly buffer |---| 859 * new segment |-----| 860 */ 861 #ifdef TCP_REASS_COUNTERS 862 counter_u64_add(reass_path5, 1); 863 #endif 864 #ifdef TCP_REASS_LOGGING 865 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 866 #endif 867 m_adj(m, i); 868 *tlenp -= i; 869 th->th_seq += i; 870 } 871 } 872 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 873 /* 874 * If dovetails in with this one 875 * append it. 876 */ 877 /** 878 * prev seg---->+ 879 * v 880 * reassembly buffer |--| |---| 881 * new segment |--| 882 * (note: it was trimmed above if it overlapped) 883 */ 884 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 885 tp->t_segqmbuflen += lenofoh; 886 } else { 887 #ifdef INVARIANTS 888 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 889 th->th_seq, p->tqe_start, p->tqe_len, 890 p, tp); 891 #endif 892 *tlenp = 0; 893 m_freem(m); 894 return (0); 895 } 896 q = p; 897 } else { 898 /* 899 * The new data runs over the 900 * top of previously sack'd data (in q). 901 * It may be partially overlapping, or 902 * it may overlap the entire segment. 903 */ 904 #ifdef TCP_REASS_COUNTERS 905 counter_u64_add(reass_path6, 1); 906 #endif 907 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 908 /* It consumes it all */ 909 /** 910 * next seg---->+ 911 * v 912 * reassembly buffer |--| |---| 913 * new segment |----------| 914 */ 915 #ifdef TCP_REASS_COUNTERS 916 counter_u64_add(reass_path7, 1); 917 #endif 918 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th)); 919 } else { 920 /* 921 * We just need to prepend the data 922 * to this. It does not overrun 923 * the end. 924 */ 925 /** 926 * next seg---->+ 927 * v 928 * reassembly buffer |--| |---| 929 * new segment |----------| 930 */ 931 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 932 tp->t_segqmbuflen += lenofoh; 933 } 934 } 935 /* Now does it go further than that? */ 936 tcp_reass_merge_forward(tp, q); 937 *seq_start = q->tqe_start; 938 *tlenp = q->tqe_len; 939 goto present; 940 941 /* 942 * When we reach here we can't combine it 943 * with any existing segment. 944 * 945 * Limit the number of segments that can be queued to reduce the 946 * potential for mbuf exhaustion. For best performance, we want to be 947 * able to queue a full window's worth of segments. The size of the 948 * socket receive buffer determines our advertised window and grows 949 * automatically when socket buffer autotuning is enabled. Use it as the 950 * basis for our queue limit. 951 * 952 * However, allow the user to specify a ceiling for the number of 953 * segments in each queue. 954 * 955 * Always let the missing segment through which caused this queue. 956 * NB: Access to the socket buffer is left intentionally unlocked as we 957 * can tolerate stale information here. 958 * 959 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 960 * should work but causes packets to be dropped when they shouldn't. 961 * Investigate why and re-evaluate the below limit after the behaviour 962 * is understood. 963 */ 964 new_entry: 965 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { 966 tp->rcv_nxt += *tlenp; 967 flags = tcp_get_flags(th) & TH_FIN; 968 TCPSTAT_INC(tcps_rcvoopack); 969 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 970 SOCKBUF_LOCK(&so->so_rcv); 971 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 972 m_freem(m); 973 } else { 974 sbappendstream_locked(&so->so_rcv, m, 0); 975 } 976 tp->t_flags |= TF_WAKESOR; 977 return (flags); 978 } 979 if (tcp_new_limits) { 980 if ((tp->t_segqlen > tcp_reass_queue_guard) && 981 (*tlenp < MSIZE)) { 982 /* 983 * This is really a lie, we are not full but 984 * are getting a segment that is above 985 * guard threshold. If it is and its below 986 * a mbuf size (256) we drop it if it 987 * can't fill in some place. 988 */ 989 TCPSTAT_INC(tcps_rcvreassfull); 990 *tlenp = 0; 991 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 992 log(LOG_DEBUG, "%s; %s: queue limit reached, " 993 "segment dropped\n", s, __func__); 994 free(s, M_TCPLOG); 995 } 996 m_freem(m); 997 #ifdef TCP_REASS_LOGGING 998 tcp_reass_log_dump(tp); 999 #endif 1000 return (0); 1001 } 1002 } else { 1003 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 1004 tcp_reass_maxqueuelen)) { 1005 TCPSTAT_INC(tcps_rcvreassfull); 1006 *tlenp = 0; 1007 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 1008 log(LOG_DEBUG, "%s; %s: queue limit reached, " 1009 "segment dropped\n", s, __func__); 1010 free(s, M_TCPLOG); 1011 } 1012 m_freem(m); 1013 #ifdef TCP_REASS_LOGGING 1014 tcp_reass_log_dump(tp); 1015 #endif 1016 return (0); 1017 } 1018 } 1019 /* 1020 * Allocate a new queue entry. If we can't, or hit the zone limit 1021 * just drop the pkt. 1022 */ 1023 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 1024 if (te == NULL) { 1025 TCPSTAT_INC(tcps_rcvmemdrop); 1026 m_freem(m); 1027 *tlenp = 0; 1028 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 1029 NULL))) { 1030 log(LOG_DEBUG, "%s; %s: global zone limit " 1031 "reached, segment dropped\n", s, __func__); 1032 free(s, M_TCPLOG); 1033 } 1034 return (0); 1035 } 1036 tp->t_segqlen++; 1037 tp->t_rcvoopack++; 1038 TCPSTAT_INC(tcps_rcvoopack); 1039 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1040 /* Insert the new segment queue entry into place. */ 1041 te->tqe_m = m; 1042 te->tqe_flags = tcp_get_flags(th); 1043 te->tqe_len = *tlenp; 1044 te->tqe_start = th->th_seq; 1045 te->tqe_last = mlast; 1046 te->tqe_mbuf_cnt = lenofoh; 1047 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1048 if (p == NULL) { 1049 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1050 } else { 1051 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1052 } 1053 #ifdef TCP_REASS_LOGGING 1054 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1055 #endif 1056 present: 1057 /* 1058 * Present data to user, advancing rcv_nxt through 1059 * completed sequence space. 1060 */ 1061 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1062 return (0); 1063 q = TAILQ_FIRST(&tp->t_segq); 1064 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1065 ("Reassembly queue for %p has stale entry at head", tp)); 1066 if (!q || q->tqe_start != tp->rcv_nxt) { 1067 #ifdef TCP_REASS_LOGGING 1068 tcp_reass_log_dump(tp); 1069 #endif 1070 return (0); 1071 } 1072 SOCKBUF_LOCK(&so->so_rcv); 1073 do { 1074 tp->rcv_nxt += q->tqe_len; 1075 flags = q->tqe_flags & TH_FIN; 1076 nq = TAILQ_NEXT(q, tqe_q); 1077 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1078 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1079 m_freem(q->tqe_m); 1080 } else { 1081 #ifdef TCP_REASS_LOGGING 1082 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1083 if (th != NULL) { 1084 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1085 } else { 1086 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); 1087 } 1088 #endif 1089 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1090 } 1091 #ifdef TCP_REASS_LOGGING 1092 if (th != NULL) { 1093 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1094 } else { 1095 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); 1096 } 1097 #endif 1098 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1099 ("tp:%p seg queue goes negative", tp)); 1100 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1101 uma_zfree(tcp_reass_zone, q); 1102 tp->t_segqlen--; 1103 q = nq; 1104 } while (q && q->tqe_start == tp->rcv_nxt); 1105 if (TAILQ_EMPTY(&tp->t_segq) && 1106 (tp->t_segqmbuflen != 0)) { 1107 #ifdef INVARIANTS 1108 panic("tp:%p segq:%p len:%d queue empty", 1109 tp, &tp->t_segq, tp->t_segqmbuflen); 1110 #else 1111 #ifdef TCP_REASS_LOGGING 1112 if (th != NULL) { 1113 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1114 } else { 1115 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); 1116 } 1117 #endif 1118 tp->t_segqmbuflen = 0; 1119 #endif 1120 } 1121 #ifdef TCP_REASS_LOGGING 1122 tcp_reass_log_dump(tp); 1123 #endif 1124 tp->t_flags |= TF_WAKESOR; 1125 return (flags); 1126 } 1127