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 #include "opt_inet.h" 36 #include "opt_inet6.h" 37 38 /* For debugging we want counters and BB logging */ 39 /* #define TCP_REASS_COUNTERS 1 */ 40 /* #define TCP_REASS_LOGGING 1 */ 41 42 #include <sys/param.h> 43 #include <sys/kernel.h> 44 #include <sys/eventhandler.h> 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/socket.h> 48 #include <sys/socketvar.h> 49 #include <sys/sysctl.h> 50 #include <sys/syslog.h> 51 #include <sys/systm.h> 52 53 #include <vm/uma.h> 54 55 #include <net/if.h> 56 #include <net/if_var.h> 57 #include <net/route.h> 58 #include <net/vnet.h> 59 60 #include <netinet/in.h> 61 #include <netinet/in_pcb.h> 62 #include <netinet/in_systm.h> 63 #include <netinet/in_var.h> 64 #include <netinet/ip.h> 65 #include <netinet/ip_var.h> 66 #include <netinet/ip_options.h> 67 #include <netinet/ip6.h> 68 #include <netinet6/in6_pcb.h> 69 #include <netinet6/ip6_var.h> 70 #include <netinet6/nd6.h> 71 #include <netinet/tcp.h> 72 #include <netinet/tcp_fsm.h> 73 #include <netinet/tcp_seq.h> 74 #include <netinet/tcp_timer.h> 75 #include <netinet/tcp_var.h> 76 #ifdef TCP_REASS_LOGGING 77 #include <netinet/tcp_log_buf.h> 78 #include <netinet/tcp_hpts.h> 79 #endif 80 #include <netinet/tcpip.h> 81 82 #define TCP_R_LOG_ADD 1 83 #define TCP_R_LOG_LIMIT_REACHED 2 84 #define TCP_R_LOG_APPEND 3 85 #define TCP_R_LOG_PREPEND 4 86 #define TCP_R_LOG_REPLACE 5 87 #define TCP_R_LOG_MERGE_INTO 6 88 #define TCP_R_LOG_NEW_ENTRY 7 89 #define TCP_R_LOG_READ 8 90 #define TCP_R_LOG_ZERO 9 91 #define TCP_R_LOG_DUMP 10 92 #define TCP_R_LOG_TRIM 11 93 94 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, 95 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 96 "TCP Segment Reassembly Queue"); 97 98 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, 99 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 100 "TCP Segment Reassembly stats"); 101 102 static int tcp_reass_maxseg = 0; 103 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 104 &tcp_reass_maxseg, 0, 105 "Global maximum number of TCP Segments in Reassembly Queue"); 106 107 static uma_zone_t tcp_reass_zone; 108 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 109 &tcp_reass_zone, 110 "Global number of TCP Segments currently in Reassembly Queue"); 111 112 static u_int tcp_reass_maxqueuelen = 100; 113 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 114 &tcp_reass_maxqueuelen, 0, 115 "Maximum number of TCP Segments per Reassembly Queue"); 116 117 static int tcp_new_limits = 0; 118 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 119 &tcp_new_limits, 0, 120 "Do we use the new limit method we are discussing?"); 121 122 static u_int tcp_reass_queue_guard = 16; 123 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 124 &tcp_reass_queue_guard, 16, 125 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 126 127 #ifdef TCP_REASS_COUNTERS 128 129 counter_u64_t reass_entry; 130 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 131 &reass_entry, "A segment entered reassembly "); 132 133 counter_u64_t reass_path1; 134 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 135 &reass_path1, "Took path 1"); 136 137 counter_u64_t reass_path2; 138 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 139 &reass_path2, "Took path 2"); 140 141 counter_u64_t reass_path3; 142 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 143 &reass_path3, "Took path 3"); 144 145 counter_u64_t reass_path4; 146 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 147 &reass_path4, "Took path 4"); 148 149 counter_u64_t reass_path5; 150 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 151 &reass_path5, "Took path 5"); 152 153 counter_u64_t reass_path6; 154 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 155 &reass_path6, "Took path 6"); 156 157 counter_u64_t reass_path7; 158 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 159 &reass_path7, "Took path 7"); 160 161 counter_u64_t reass_fullwalk; 162 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 163 &reass_fullwalk, "Took a full walk "); 164 165 counter_u64_t reass_nospace; 166 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 167 &reass_nospace, "Had no mbuf capacity "); 168 169 counter_u64_t merge_fwd; 170 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 171 &merge_fwd, "Ran merge fwd"); 172 173 counter_u64_t merge_into; 174 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 175 &merge_into, "Ran merge into"); 176 177 counter_u64_t tcp_zero_input; 178 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 179 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 180 181 #endif 182 183 /* Initialize TCP reassembly queue */ 184 static void 185 tcp_reass_zone_change(void *tag) 186 { 187 188 /* Set the zone limit and read back the effective value. */ 189 tcp_reass_maxseg = nmbclusters / 16; 190 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 191 tcp_reass_maxseg); 192 } 193 194 #ifdef TCP_REASS_LOGGING 195 196 static void 197 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 198 tcp_seq seq, int len, uint8_t action, int instance) 199 { 200 struct socket *so = tptosocket(tp); 201 uint32_t cts; 202 struct timeval tv; 203 204 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 205 union tcp_log_stackspecific log; 206 207 memset(&log, 0, sizeof(log)); 208 cts = tcp_get_usecs(&tv); 209 log.u_bbr.flex1 = seq; 210 log.u_bbr.cur_del_rate = (uint64_t)q; 211 log.u_bbr.delRate = (uint64_t)p; 212 if (q != NULL) { 213 log.u_bbr.flex2 = q->tqe_start; 214 log.u_bbr.flex3 = q->tqe_len; 215 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 216 log.u_bbr.hptsi_gain = q->tqe_flags; 217 } 218 if (p != NULL) { 219 log.u_bbr.flex5 = p->tqe_start; 220 log.u_bbr.pkts_out = p->tqe_len; 221 log.u_bbr.epoch = p->tqe_mbuf_cnt; 222 log.u_bbr.cwnd_gain = p->tqe_flags; 223 } 224 log.u_bbr.flex6 = tp->t_segqmbuflen; 225 log.u_bbr.flex7 = instance; 226 log.u_bbr.flex8 = action; 227 log.u_bbr.timeStamp = cts; 228 TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd, 229 TCP_LOG_REASS, 0, 230 len, &log, false, &tv); 231 } 232 } 233 234 static void 235 tcp_reass_log_dump(struct tcpcb *tp) 236 { 237 struct tseg_qent *q; 238 239 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 240 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 241 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 242 } 243 }; 244 } 245 246 static void 247 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 248 int logval, struct tseg_qent *q) 249 { 250 int cnt; 251 struct mbuf *t; 252 253 cnt = 0; 254 t = m; 255 while (t) { 256 cnt += t->m_len; 257 t = t->m_next; 258 } 259 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 260 } 261 262 #endif 263 264 void 265 tcp_reass_global_init(void) 266 { 267 268 tcp_reass_maxseg = nmbclusters / 16; 269 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 270 &tcp_reass_maxseg); 271 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 272 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 273 /* Set the zone limit and read back the effective value. */ 274 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 275 tcp_reass_maxseg); 276 #ifdef TCP_REASS_COUNTERS 277 reass_path1 = counter_u64_alloc(M_WAITOK); 278 reass_path2 = counter_u64_alloc(M_WAITOK); 279 reass_path3 = counter_u64_alloc(M_WAITOK); 280 reass_path4 = counter_u64_alloc(M_WAITOK); 281 reass_path5 = counter_u64_alloc(M_WAITOK); 282 reass_path6 = counter_u64_alloc(M_WAITOK); 283 reass_path7 = counter_u64_alloc(M_WAITOK); 284 reass_fullwalk = counter_u64_alloc(M_WAITOK); 285 reass_nospace = counter_u64_alloc(M_WAITOK); 286 reass_entry = counter_u64_alloc(M_WAITOK); 287 merge_fwd = counter_u64_alloc(M_WAITOK); 288 merge_into = counter_u64_alloc(M_WAITOK); 289 tcp_zero_input = counter_u64_alloc(M_WAITOK); 290 #endif 291 EVENTHANDLER_REGISTER(nmbclusters_change, 292 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 293 294 } 295 296 void 297 tcp_reass_flush(struct tcpcb *tp) 298 { 299 struct tseg_qent *qe; 300 301 INP_WLOCK_ASSERT(tptoinpcb(tp)); 302 303 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 304 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 305 m_freem(qe->tqe_m); 306 uma_zfree(tcp_reass_zone, qe); 307 tp->t_segqlen--; 308 } 309 tp->t_segqmbuflen = 0; 310 KASSERT((tp->t_segqlen == 0), 311 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 312 tp, tp->t_segqlen)); 313 } 314 315 static void 316 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 317 struct mbuf *m, struct tcphdr *th, int tlen, 318 struct mbuf *mlast, int lenofoh) 319 { 320 321 #ifdef TCP_REASS_LOGGING 322 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 323 #endif 324 last->tqe_len += tlen; 325 last->tqe_m->m_pkthdr.len += tlen; 326 /* Preserve the FIN bit if its there */ 327 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN); 328 last->tqe_last->m_next = m; 329 last->tqe_last = mlast; 330 last->tqe_mbuf_cnt += lenofoh; 331 tp->t_rcvoopack++; 332 TCPSTAT_INC(tcps_rcvoopack); 333 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 334 #ifdef TCP_REASS_LOGGING 335 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 336 TCP_R_LOG_APPEND, 337 last); 338 #endif 339 } 340 341 static void 342 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 343 int tlen, struct mbuf *mlast, int lenofoh) 344 { 345 int i; 346 347 #ifdef TCP_REASS_LOGGING 348 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 349 #endif 350 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 351 /* The new data overlaps into the old */ 352 i = (th->th_seq + tlen) - first->tqe_start; 353 #ifdef TCP_REASS_LOGGING 354 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 355 #endif 356 m_adj(first->tqe_m, i); 357 first->tqe_len -= i; 358 first->tqe_start += i; 359 } 360 /* Ok now setup our chain to point to the old first */ 361 mlast->m_next = first->tqe_m; 362 first->tqe_m = m; 363 first->tqe_len += tlen; 364 first->tqe_start = th->th_seq; 365 first->tqe_m->m_pkthdr.len = first->tqe_len; 366 first->tqe_mbuf_cnt += lenofoh; 367 tp->t_rcvoopack++; 368 TCPSTAT_INC(tcps_rcvoopack); 369 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 370 #ifdef TCP_REASS_LOGGING 371 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 372 TCP_R_LOG_PREPEND, 373 first); 374 #endif 375 } 376 377 static void 378 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 379 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags) 380 { 381 /* 382 * Free the data in q, and replace 383 * it with the new segment. 384 */ 385 int len_dif; 386 387 #ifdef TCP_REASS_LOGGING 388 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 389 #endif 390 m_freem(q->tqe_m); 391 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 392 ("Tp:%p seg queue goes negative", tp)); 393 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 394 q->tqe_mbuf_cnt = mbufoh; 395 q->tqe_m = m; 396 q->tqe_last = mlast; 397 q->tqe_start = seq; 398 if (len > q->tqe_len) 399 len_dif = len - q->tqe_len; 400 else 401 len_dif = 0; 402 tp->t_rcvoopack++; 403 TCPSTAT_INC(tcps_rcvoopack); 404 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 405 q->tqe_len = len; 406 q->tqe_flags = (flags & TH_FIN); 407 q->tqe_m->m_pkthdr.len = q->tqe_len; 408 tp->t_segqmbuflen += mbufoh; 409 410 } 411 412 static void 413 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 414 struct tseg_qent *q) 415 { 416 /* 417 * Merge q into ent and free q from the list. 418 */ 419 #ifdef TCP_REASS_LOGGING 420 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 421 #endif 422 #ifdef TCP_REASS_COUNTERS 423 counter_u64_add(merge_into, 1); 424 #endif 425 ent->tqe_last->m_next = q->tqe_m; 426 ent->tqe_last = q->tqe_last; 427 ent->tqe_len += q->tqe_len; 428 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 429 ent->tqe_m->m_pkthdr.len += q->tqe_len; 430 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 431 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 432 uma_zfree(tcp_reass_zone, q); 433 tp->t_segqlen--; 434 435 } 436 437 static void 438 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 439 { 440 struct tseg_qent *q, *qtmp; 441 int i; 442 tcp_seq max; 443 /* 444 * Given an entry merge forward anyplace 445 * that ent overlaps forward. 446 */ 447 448 max = ent->tqe_start + ent->tqe_len; 449 q = TAILQ_NEXT(ent, tqe_q); 450 if (q == NULL) { 451 /* Nothing left */ 452 return; 453 } 454 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 455 if (SEQ_GT(q->tqe_start, max)) { 456 /* Beyond q */ 457 break; 458 } 459 /* We have some or all that are overlapping */ 460 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 461 /* It consumes it all */ 462 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 463 m_freem(q->tqe_m); 464 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 465 uma_zfree(tcp_reass_zone, q); 466 tp->t_segqlen--; 467 continue; 468 } 469 /* 470 * Trim the q entry to dovetail to this one 471 * and then merge q into ent updating max 472 * in the process. 473 */ 474 i = max - q->tqe_start; 475 #ifdef TCP_REASS_LOGGING 476 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 477 #endif 478 m_adj(q->tqe_m, i); 479 q->tqe_len -= i; 480 q->tqe_start += i; 481 tcp_reass_merge_into(tp, ent, q); 482 max = ent->tqe_start + ent->tqe_len; 483 } 484 #ifdef TCP_REASS_COUNTERS 485 counter_u64_add(merge_fwd, 1); 486 #endif 487 } 488 489 static int 490 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 491 { 492 int len = MSIZE; 493 494 if (m->m_flags & M_EXT) 495 len += m->m_ext.ext_size; 496 while (m->m_next != NULL) { 497 m = m->m_next; 498 len += MSIZE; 499 if (m->m_flags & M_EXT) 500 len += m->m_ext.ext_size; 501 } 502 *mlast = m; 503 return (len); 504 } 505 506 /* 507 * NOTE!!! the new tcp-reassembly code *must not* use 508 * m_adj() with a negative index. That alters the chain 509 * of mbufs (by possibly chopping trailing mbufs). At 510 * the front of tcp_reass we count the mbuf overhead 511 * and setup the tail pointer. If we use m_adj(m, -5) 512 * we could corrupt the tail pointer. Currently the 513 * code only uses m_adj(m, postive-num). If this 514 * changes appropriate changes to update mlast would 515 * be needed. 516 */ 517 int 518 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 519 int *tlenp, struct mbuf *m) 520 { 521 struct tseg_qent *q, *last, *first; 522 struct tseg_qent *p = NULL; 523 struct tseg_qent *nq = NULL; 524 struct tseg_qent *te = NULL; 525 struct mbuf *mlast = NULL; 526 struct inpcb *inp = tptoinpcb(tp); 527 struct socket *so = tptosocket(tp); 528 struct sockbuf *sb = &so->so_rcv; 529 char *s = NULL; 530 int flags, i, lenofoh; 531 532 INP_WLOCK_ASSERT(inp); 533 /* 534 * XXX: tcp_reass() is rather inefficient with its data structures 535 * and should be rewritten (see NetBSD for optimizations). 536 */ 537 538 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), 539 ("tcp_reass called with illegal parameter combination " 540 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", 541 tp, th, seq_start, tlenp, m)); 542 /* 543 * Call with th==NULL after become established to 544 * force pre-ESTABLISHED data up to user socket. 545 */ 546 if (th == NULL) 547 goto present; 548 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 549 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 550 th, tp)); 551 #ifdef TCP_REASS_LOGGING 552 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 553 #endif 554 #ifdef TCP_REASS_COUNTERS 555 counter_u64_add(reass_entry, 1); 556 #endif 557 /* 558 * Check for zero length data. 559 */ 560 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) { 561 /* 562 * A zero length segment does no 563 * one any good. We could check 564 * the rcv_nxt <-> rcv_wnd but thats 565 * already done for us by the caller. 566 */ 567 strip_fin: 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 } else if ((*tlenp == 0) && 577 (tcp_get_flags(th) & TH_FIN) && 578 !TCPS_HAVEESTABLISHED(tp->t_state)) { 579 /* 580 * We have not established, and we 581 * have a FIN and no data. Lets treat 582 * this as the same as if the FIN were 583 * not present. We don't want to save 584 * the FIN bit in a reassembly buffer 585 * we want to get established first before 586 * we do that (the peer will retransmit). 587 */ 588 goto strip_fin; 589 } 590 /* 591 * Will it fit? 592 */ 593 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 594 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 595 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 596 /* No room */ 597 TCPSTAT_INC(tcps_rcvreassfull); 598 #ifdef TCP_REASS_COUNTERS 599 counter_u64_add(reass_nospace, 1); 600 #endif 601 #ifdef TCP_REASS_LOGGING 602 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 603 #endif 604 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 605 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " 606 "segment dropped\n", s, __func__); 607 free(s, M_TCPLOG); 608 } 609 m_freem(m); 610 *tlenp = 0; 611 #ifdef TCP_REASS_LOGGING 612 tcp_reass_log_dump(tp); 613 #endif 614 return (0); 615 } 616 /* 617 * First lets deal with two common cases, the 618 * segment appends to the back of our collected 619 * segments. Or the segment is the next in line. 620 */ 621 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 622 if (last != NULL) { 623 if ((tcp_get_flags(th) & TH_FIN) && 624 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 625 /* 626 * Someone is trying to game us, dump 627 * the segment. 628 */ 629 *tlenp = 0; 630 m_freem(m); 631 return (0); 632 } 633 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 634 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 635 /* Common case, trailing segment is added */ 636 /** 637 * +--last 638 * v 639 * reassembly buffer |---| |---| |---| 640 * new segment |---| 641 */ 642 #ifdef TCP_REASS_COUNTERS 643 counter_u64_add(reass_path1, 1); 644 #endif 645 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 646 i = (last->tqe_start + last->tqe_len) - th->th_seq; 647 if (i < *tlenp) { 648 #ifdef TCP_REASS_LOGGING 649 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 650 th->th_seq += i; 651 #endif 652 m_adj(m, i); 653 *tlenp -= i; 654 } else { 655 /* Complete overlap */ 656 TCPSTAT_INC(tcps_rcvduppack); 657 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 658 m_freem(m); 659 *tlenp = last->tqe_len; 660 *seq_start = last->tqe_start; 661 return (0); 662 } 663 } 664 if (last->tqe_flags & TH_FIN) { 665 /* 666 * We have data after the FIN on the last? 667 */ 668 *tlenp = 0; 669 m_freem(m); 670 return(0); 671 } 672 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 673 tp->t_segqmbuflen += lenofoh; 674 *seq_start = last->tqe_start; 675 *tlenp = last->tqe_len; 676 return (0); 677 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 678 /* 679 * Second common case, we missed 680 * another one and have something more 681 * for the end. 682 */ 683 /** 684 * +--last 685 * v 686 * reassembly buffer |---| |---| |---| 687 * new segment |---| 688 */ 689 if (last->tqe_flags & TH_FIN) { 690 /* 691 * We have data after the FIN on the last? 692 */ 693 *tlenp = 0; 694 m_freem(m); 695 return(0); 696 } 697 #ifdef TCP_REASS_COUNTERS 698 counter_u64_add(reass_path2, 1); 699 #endif 700 p = last; 701 goto new_entry; 702 } 703 } else { 704 /* First segment (it's NULL). */ 705 goto new_entry; 706 } 707 first = TAILQ_FIRST(&tp->t_segq); 708 if (SEQ_LT(th->th_seq, first->tqe_start) && 709 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 710 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 711 /* 712 * The head of the queue is prepended by this and 713 * it may be the one I want most. 714 */ 715 /** 716 * first-------+ 717 * v 718 * rea: |---| |---| |---| 719 * new: |---| 720 * Note the case we do not deal with here is: 721 * rea= |---| |---| |---| 722 * new= |----| 723 * Due to the fact that it could be 724 * new |--------------------| 725 * And we might need to merge forward. 726 */ 727 #ifdef INVARIANTS 728 struct mbuf *firstmbuf; 729 #endif 730 731 #ifdef TCP_REASS_COUNTERS 732 counter_u64_add(reass_path3, 1); 733 #endif 734 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 735 /* 736 * The resend was even before 737 * what we have. We need to trim it. 738 * Note TSNH (it should be trimmed 739 * before the call to tcp_reass()). 740 */ 741 #ifdef INVARIANTS 742 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 743 th->th_seq, tp->rcv_nxt, tp); 744 #else 745 i = tp->rcv_nxt - th->th_seq; 746 #ifdef TCP_REASS_LOGGING 747 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 748 #endif 749 m_adj(m, i); 750 th->th_seq += i; 751 *tlenp -= i; 752 #endif 753 } 754 #ifdef INVARIANTS 755 firstmbuf = first->tqe_m; 756 #endif 757 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 758 #ifdef INVARIANTS 759 if (firstmbuf == first->tqe_m) { 760 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 761 m, firstmbuf, first->tqe_m, tp, first); 762 } else if (first->tqe_m != m) { 763 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 764 m, firstmbuf, first->tqe_m, tp, first); 765 } 766 #endif 767 tp->t_segqmbuflen += lenofoh; 768 *seq_start = first->tqe_start; 769 *tlenp = first->tqe_len; 770 goto present; 771 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 772 /* New segment is before our earliest segment. */ 773 /** 774 * first---->+ 775 * v 776 * rea= |---| .... 777 * new" |---| 778 * 779 */ 780 goto new_entry; 781 } 782 /* 783 * Find a segment which begins after this one does. 784 */ 785 #ifdef TCP_REASS_COUNTERS 786 counter_u64_add(reass_fullwalk, 1); 787 #endif 788 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 789 if (SEQ_GT(q->tqe_start, th->th_seq)) 790 break; 791 } 792 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 793 /** 794 * Now is this fit just in-between only? 795 * i.e.: 796 * p---+ +----q 797 * v v 798 * res= |--| |--| |--| 799 * nee |-| 800 */ 801 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 802 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 803 /* Yep no overlap */ 804 goto new_entry; 805 } 806 /** 807 * If we reach here we have some (possibly all) overlap 808 * such as: 809 * res= |--| |--| |--| 810 * new= |----| 811 * or new= |-----------------| 812 * or new= |--------| 813 * or new= |---| 814 * or new= |-----------| 815 */ 816 if ((p != NULL) && 817 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 818 /* conversion to int (in i) handles seq wraparound */ 819 820 #ifdef TCP_REASS_COUNTERS 821 counter_u64_add(reass_path4, 1); 822 #endif 823 i = p->tqe_start + p->tqe_len - th->th_seq; 824 if (i >= 0) { 825 if (i >= *tlenp) { 826 /** 827 * prev seg---->+ 828 * v 829 * reassembly buffer |---| 830 * new segment |-| 831 */ 832 TCPSTAT_INC(tcps_rcvduppack); 833 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 834 *tlenp = p->tqe_len; 835 *seq_start = p->tqe_start; 836 m_freem(m); 837 /* 838 * Try to present any queued data 839 * at the left window edge to the user. 840 * This is needed after the 3-WHS 841 * completes. Note this probably 842 * will not work and we will return. 843 */ 844 return (0); 845 } 846 if (i > 0) { 847 /** 848 * prev seg---->+ 849 * v 850 * reassembly buffer |---| 851 * new segment |-----| 852 */ 853 #ifdef TCP_REASS_COUNTERS 854 counter_u64_add(reass_path5, 1); 855 #endif 856 #ifdef TCP_REASS_LOGGING 857 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 858 #endif 859 m_adj(m, i); 860 *tlenp -= i; 861 th->th_seq += i; 862 } 863 } 864 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 865 /* 866 * If dovetails in with this one 867 * append it. 868 */ 869 /** 870 * prev seg---->+ 871 * v 872 * reassembly buffer |--| |---| 873 * new segment |--| 874 * (note: it was trimmed above if it overlapped) 875 */ 876 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 877 tp->t_segqmbuflen += lenofoh; 878 } else { 879 #ifdef INVARIANTS 880 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 881 th->th_seq, p->tqe_start, p->tqe_len, 882 p, tp); 883 #endif 884 *tlenp = 0; 885 m_freem(m); 886 return (0); 887 } 888 q = p; 889 } else { 890 /* 891 * The new data runs over the 892 * top of previously sack'd data (in q). 893 * It may be partially overlapping, or 894 * it may overlap the entire segment. 895 */ 896 #ifdef TCP_REASS_COUNTERS 897 counter_u64_add(reass_path6, 1); 898 #endif 899 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 900 /* It consumes it all */ 901 /** 902 * next seg---->+ 903 * v 904 * reassembly buffer |--| |---| 905 * new segment |----------| 906 */ 907 #ifdef TCP_REASS_COUNTERS 908 counter_u64_add(reass_path7, 1); 909 #endif 910 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th)); 911 } else { 912 /* 913 * We just need to prepend the data 914 * to this. It does not overrun 915 * the end. 916 */ 917 /** 918 * next seg---->+ 919 * v 920 * reassembly buffer |--| |---| 921 * new segment |----------| 922 */ 923 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 924 tp->t_segqmbuflen += lenofoh; 925 } 926 } 927 /* Now does it go further than that? */ 928 tcp_reass_merge_forward(tp, q); 929 *seq_start = q->tqe_start; 930 *tlenp = q->tqe_len; 931 goto present; 932 933 /* 934 * When we reach here we can't combine it 935 * with any existing segment. 936 * 937 * Limit the number of segments that can be queued to reduce the 938 * potential for mbuf exhaustion. For best performance, we want to be 939 * able to queue a full window's worth of segments. The size of the 940 * socket receive buffer determines our advertised window and grows 941 * automatically when socket buffer autotuning is enabled. Use it as the 942 * basis for our queue limit. 943 * 944 * However, allow the user to specify a ceiling for the number of 945 * segments in each queue. 946 * 947 * Always let the missing segment through which caused this queue. 948 * NB: Access to the socket buffer is left intentionally unlocked as we 949 * can tolerate stale information here. 950 * 951 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 952 * should work but causes packets to be dropped when they shouldn't. 953 * Investigate why and re-evaluate the below limit after the behaviour 954 * is understood. 955 */ 956 new_entry: 957 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { 958 tp->rcv_nxt += *tlenp; 959 flags = tcp_get_flags(th) & TH_FIN; 960 TCPSTAT_INC(tcps_rcvoopack); 961 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 962 SOCKBUF_LOCK(&so->so_rcv); 963 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 964 m_freem(m); 965 } else { 966 sbappendstream_locked(&so->so_rcv, m, 0); 967 } 968 tp->t_flags |= TF_WAKESOR; 969 return (flags); 970 } 971 if (tcp_new_limits) { 972 if ((tp->t_segqlen > tcp_reass_queue_guard) && 973 (*tlenp < MSIZE)) { 974 /* 975 * This is really a lie, we are not full but 976 * are getting a segment that is above 977 * guard threshold. If it is and its below 978 * a mbuf size (256) we drop it if it 979 * can't fill in some place. 980 */ 981 TCPSTAT_INC(tcps_rcvreassfull); 982 *tlenp = 0; 983 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 984 log(LOG_DEBUG, "%s; %s: queue limit reached, " 985 "segment dropped\n", s, __func__); 986 free(s, M_TCPLOG); 987 } 988 m_freem(m); 989 #ifdef TCP_REASS_LOGGING 990 tcp_reass_log_dump(tp); 991 #endif 992 return (0); 993 } 994 } else { 995 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 996 tcp_reass_maxqueuelen)) { 997 TCPSTAT_INC(tcps_rcvreassfull); 998 *tlenp = 0; 999 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 1000 log(LOG_DEBUG, "%s; %s: queue limit reached, " 1001 "segment dropped\n", s, __func__); 1002 free(s, M_TCPLOG); 1003 } 1004 m_freem(m); 1005 #ifdef TCP_REASS_LOGGING 1006 tcp_reass_log_dump(tp); 1007 #endif 1008 return (0); 1009 } 1010 } 1011 /* 1012 * Allocate a new queue entry. If we can't, or hit the zone limit 1013 * just drop the pkt. 1014 */ 1015 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 1016 if (te == NULL) { 1017 TCPSTAT_INC(tcps_rcvmemdrop); 1018 m_freem(m); 1019 *tlenp = 0; 1020 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 1021 log(LOG_DEBUG, "%s; %s: global zone limit " 1022 "reached, segment dropped\n", s, __func__); 1023 free(s, M_TCPLOG); 1024 } 1025 return (0); 1026 } 1027 tp->t_segqlen++; 1028 tp->t_rcvoopack++; 1029 TCPSTAT_INC(tcps_rcvoopack); 1030 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1031 /* Insert the new segment queue entry into place. */ 1032 te->tqe_m = m; 1033 te->tqe_flags = tcp_get_flags(th); 1034 te->tqe_len = *tlenp; 1035 te->tqe_start = th->th_seq; 1036 te->tqe_last = mlast; 1037 te->tqe_mbuf_cnt = lenofoh; 1038 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1039 if (p == NULL) { 1040 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1041 } else { 1042 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1043 } 1044 #ifdef TCP_REASS_LOGGING 1045 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1046 #endif 1047 present: 1048 /* 1049 * Present data to user, advancing rcv_nxt through 1050 * completed sequence space. 1051 */ 1052 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1053 return (0); 1054 q = TAILQ_FIRST(&tp->t_segq); 1055 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1056 ("Reassembly queue for %p has stale entry at head", tp)); 1057 if (!q || q->tqe_start != tp->rcv_nxt) { 1058 #ifdef TCP_REASS_LOGGING 1059 tcp_reass_log_dump(tp); 1060 #endif 1061 return (0); 1062 } 1063 SOCKBUF_LOCK(&so->so_rcv); 1064 do { 1065 tp->rcv_nxt += q->tqe_len; 1066 flags = q->tqe_flags & TH_FIN; 1067 nq = TAILQ_NEXT(q, tqe_q); 1068 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1069 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1070 m_freem(q->tqe_m); 1071 } else { 1072 #ifdef TCP_REASS_LOGGING 1073 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1074 if (th != NULL) { 1075 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1076 } else { 1077 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); 1078 } 1079 #endif 1080 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1081 } 1082 #ifdef TCP_REASS_LOGGING 1083 if (th != NULL) { 1084 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1085 } else { 1086 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); 1087 } 1088 #endif 1089 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1090 ("tp:%p seg queue goes negative", tp)); 1091 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1092 uma_zfree(tcp_reass_zone, q); 1093 tp->t_segqlen--; 1094 q = nq; 1095 } while (q && q->tqe_start == tp->rcv_nxt); 1096 if (TAILQ_EMPTY(&tp->t_segq) && 1097 (tp->t_segqmbuflen != 0)) { 1098 #ifdef INVARIANTS 1099 panic("tp:%p segq:%p len:%d queue empty", 1100 tp, &tp->t_segq, tp->t_segqmbuflen); 1101 #else 1102 #ifdef TCP_REASS_LOGGING 1103 if (th != NULL) { 1104 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1105 } else { 1106 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); 1107 } 1108 #endif 1109 tp->t_segqmbuflen = 0; 1110 #endif 1111 } 1112 #ifdef TCP_REASS_LOGGING 1113 tcp_reass_log_dump(tp); 1114 #endif 1115 tp->t_flags |= TF_WAKESOR; 1116 return (flags); 1117 } 1118