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
40 /* For debugging we want counters and BB logging */
41 /* #define TCP_REASS_COUNTERS 1 */
42 /* #define TCP_REASS_LOGGING 1 */
43
44 #include <sys/param.h>
45 #include <sys/kernel.h>
46 #include <sys/eventhandler.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/socket.h>
50 #include <sys/socketvar.h>
51 #include <sys/sysctl.h>
52 #include <sys/syslog.h>
53 #include <sys/systm.h>
54
55 #include <vm/uma.h>
56
57 #include <net/if.h>
58 #include <net/if_var.h>
59 #include <net/route.h>
60 #include <net/vnet.h>
61
62 #include <netinet/in.h>
63 #include <netinet/in_pcb.h>
64 #include <netinet/in_systm.h>
65 #include <netinet/in_var.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_var.h>
68 #include <netinet/ip_options.h>
69 #include <netinet/ip6.h>
70 #include <netinet6/in6_pcb.h>
71 #include <netinet6/ip6_var.h>
72 #include <netinet6/nd6.h>
73 #include <netinet/tcp.h>
74 #include <netinet/tcp_fsm.h>
75 #include <netinet/tcp_seq.h>
76 #include <netinet/tcp_timer.h>
77 #include <netinet/tcp_var.h>
78 #ifdef TCP_REASS_LOGGING
79 #include <netinet/tcp_log_buf.h>
80 #include <netinet/tcp_hpts.h>
81 #endif
82 #include <netinet/tcpip.h>
83
84 #define TCP_R_LOG_ADD 1
85 #define TCP_R_LOG_LIMIT_REACHED 2
86 #define TCP_R_LOG_APPEND 3
87 #define TCP_R_LOG_PREPEND 4
88 #define TCP_R_LOG_REPLACE 5
89 #define TCP_R_LOG_MERGE_INTO 6
90 #define TCP_R_LOG_NEW_ENTRY 7
91 #define TCP_R_LOG_READ 8
92 #define TCP_R_LOG_ZERO 9
93 #define TCP_R_LOG_DUMP 10
94 #define TCP_R_LOG_TRIM 11
95
96 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass,
97 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
98 "TCP Segment Reassembly Queue");
99
100 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats,
101 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
102 "TCP Segment Reassembly stats");
103
104 static int tcp_reass_maxseg = 0;
105 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
106 &tcp_reass_maxseg, 0,
107 "Global maximum number of TCP Segments in Reassembly Queue");
108
109 static uma_zone_t tcp_reass_zone;
110 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
111 &tcp_reass_zone,
112 "Global number of TCP Segments currently in Reassembly Queue");
113
114 static u_int tcp_reass_maxqueuelen = 100;
115 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
116 &tcp_reass_maxqueuelen, 0,
117 "Maximum number of TCP Segments per Reassembly Queue");
118
119 static int tcp_new_limits = 0;
120 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
121 &tcp_new_limits, 0,
122 "Do we use the new limit method we are discussing?");
123
124 static u_int tcp_reass_queue_guard = 16;
125 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
126 &tcp_reass_queue_guard, 16,
127 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
128
129 #ifdef TCP_REASS_COUNTERS
130
131 counter_u64_t reass_entry;
132 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
133 &reass_entry, "A segment entered reassembly ");
134
135 counter_u64_t reass_path1;
136 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
137 &reass_path1, "Took path 1");
138
139 counter_u64_t reass_path2;
140 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
141 &reass_path2, "Took path 2");
142
143 counter_u64_t reass_path3;
144 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
145 &reass_path3, "Took path 3");
146
147 counter_u64_t reass_path4;
148 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
149 &reass_path4, "Took path 4");
150
151 counter_u64_t reass_path5;
152 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
153 &reass_path5, "Took path 5");
154
155 counter_u64_t reass_path6;
156 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
157 &reass_path6, "Took path 6");
158
159 counter_u64_t reass_path7;
160 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
161 &reass_path7, "Took path 7");
162
163 counter_u64_t reass_fullwalk;
164 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
165 &reass_fullwalk, "Took a full walk ");
166
167 counter_u64_t reass_nospace;
168 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
169 &reass_nospace, "Had no mbuf capacity ");
170
171 counter_u64_t merge_fwd;
172 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
173 &merge_fwd, "Ran merge fwd");
174
175 counter_u64_t merge_into;
176 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
177 &merge_into, "Ran merge into");
178
179 counter_u64_t tcp_zero_input;
180 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
181 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
182
183 #endif
184
185 /* Initialize TCP reassembly queue */
186 static void
187 tcp_reass_zone_change(void *tag)
188 {
189
190 /* Set the zone limit and read back the effective value. */
191 tcp_reass_maxseg = nmbclusters / 16;
192 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
193 tcp_reass_maxseg);
194 }
195
196 #ifdef TCP_REASS_LOGGING
197
198 static void
199 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
200 tcp_seq seq, int len, uint8_t action, int instance)
201 {
202 struct socket *so = tptosocket(tp);
203 uint32_t cts;
204 struct timeval tv;
205
206 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
207 union tcp_log_stackspecific log;
208
209 memset(&log, 0, sizeof(log));
210 cts = tcp_get_usecs(&tv);
211 log.u_bbr.flex1 = seq;
212 log.u_bbr.cur_del_rate = (uint64_t)q;
213 log.u_bbr.delRate = (uint64_t)p;
214 if (q != NULL) {
215 log.u_bbr.flex2 = q->tqe_start;
216 log.u_bbr.flex3 = q->tqe_len;
217 log.u_bbr.flex4 = q->tqe_mbuf_cnt;
218 log.u_bbr.hptsi_gain = q->tqe_flags;
219 }
220 if (p != NULL) {
221 log.u_bbr.flex5 = p->tqe_start;
222 log.u_bbr.pkts_out = p->tqe_len;
223 log.u_bbr.epoch = p->tqe_mbuf_cnt;
224 log.u_bbr.cwnd_gain = p->tqe_flags;
225 }
226 log.u_bbr.flex6 = tp->t_segqmbuflen;
227 log.u_bbr.flex7 = instance;
228 log.u_bbr.flex8 = action;
229 log.u_bbr.timeStamp = cts;
230 TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd,
231 TCP_LOG_REASS, 0,
232 len, &log, false, &tv);
233 }
234 }
235
236 static void
237 tcp_reass_log_dump(struct tcpcb *tp)
238 {
239 struct tseg_qent *q;
240
241 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
242 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
243 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
244 }
245 };
246 }
247
248 static void
249 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
250 int logval, struct tseg_qent *q)
251 {
252 int cnt;
253 struct mbuf *t;
254
255 cnt = 0;
256 t = m;
257 while (t) {
258 cnt += t->m_len;
259 t = t->m_next;
260 }
261 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
262 }
263
264 #endif
265
266 void
267 tcp_reass_global_init(void)
268 {
269
270 tcp_reass_maxseg = nmbclusters / 16;
271 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
272 &tcp_reass_maxseg);
273 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
274 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
275 /* Set the zone limit and read back the effective value. */
276 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
277 tcp_reass_maxseg);
278 #ifdef TCP_REASS_COUNTERS
279 reass_path1 = counter_u64_alloc(M_WAITOK);
280 reass_path2 = counter_u64_alloc(M_WAITOK);
281 reass_path3 = counter_u64_alloc(M_WAITOK);
282 reass_path4 = counter_u64_alloc(M_WAITOK);
283 reass_path5 = counter_u64_alloc(M_WAITOK);
284 reass_path6 = counter_u64_alloc(M_WAITOK);
285 reass_path7 = counter_u64_alloc(M_WAITOK);
286 reass_fullwalk = counter_u64_alloc(M_WAITOK);
287 reass_nospace = counter_u64_alloc(M_WAITOK);
288 reass_entry = counter_u64_alloc(M_WAITOK);
289 merge_fwd = counter_u64_alloc(M_WAITOK);
290 merge_into = counter_u64_alloc(M_WAITOK);
291 tcp_zero_input = counter_u64_alloc(M_WAITOK);
292 #endif
293 EVENTHANDLER_REGISTER(nmbclusters_change,
294 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
295
296 }
297
298 void
299 tcp_reass_flush(struct tcpcb *tp)
300 {
301 struct tseg_qent *qe;
302
303 INP_WLOCK_ASSERT(tptoinpcb(tp));
304
305 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
306 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
307 m_freem(qe->tqe_m);
308 uma_zfree(tcp_reass_zone, qe);
309 tp->t_segqlen--;
310 }
311 tp->t_segqmbuflen = 0;
312 KASSERT((tp->t_segqlen == 0),
313 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
314 tp, tp->t_segqlen));
315 }
316
317 static void
318 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
319 struct mbuf *m, struct tcphdr *th, int tlen,
320 struct mbuf *mlast, int lenofoh)
321 {
322
323 #ifdef TCP_REASS_LOGGING
324 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
325 #endif
326 last->tqe_len += tlen;
327 last->tqe_m->m_pkthdr.len += tlen;
328 /* Preserve the FIN bit if its there */
329 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN);
330 last->tqe_last->m_next = m;
331 last->tqe_last = mlast;
332 last->tqe_mbuf_cnt += lenofoh;
333 tp->t_rcvoopack++;
334 TCPSTAT_INC(tcps_rcvoopack);
335 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
336 #ifdef TCP_REASS_LOGGING
337 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
338 TCP_R_LOG_APPEND,
339 last);
340 #endif
341 }
342
343 static void
344 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
345 int tlen, struct mbuf *mlast, int lenofoh)
346 {
347 int i;
348
349 #ifdef TCP_REASS_LOGGING
350 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
351 #endif
352 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
353 /* The new data overlaps into the old */
354 i = (th->th_seq + tlen) - first->tqe_start;
355 #ifdef TCP_REASS_LOGGING
356 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
357 #endif
358 m_adj(first->tqe_m, i);
359 first->tqe_len -= i;
360 first->tqe_start += i;
361 }
362 /* Ok now setup our chain to point to the old first */
363 mlast->m_next = first->tqe_m;
364 first->tqe_m = m;
365 first->tqe_len += tlen;
366 first->tqe_start = th->th_seq;
367 first->tqe_m->m_pkthdr.len = first->tqe_len;
368 first->tqe_mbuf_cnt += lenofoh;
369 tp->t_rcvoopack++;
370 TCPSTAT_INC(tcps_rcvoopack);
371 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
372 #ifdef TCP_REASS_LOGGING
373 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
374 TCP_R_LOG_PREPEND,
375 first);
376 #endif
377 }
378
379 static void
380 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
381 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags)
382 {
383 /*
384 * Free the data in q, and replace
385 * it with the new segment.
386 */
387 int len_dif;
388
389 #ifdef TCP_REASS_LOGGING
390 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
391 #endif
392 m_freem(q->tqe_m);
393 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
394 ("Tp:%p seg queue goes negative", tp));
395 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
396 q->tqe_mbuf_cnt = mbufoh;
397 q->tqe_m = m;
398 q->tqe_last = mlast;
399 q->tqe_start = seq;
400 if (len > q->tqe_len)
401 len_dif = len - q->tqe_len;
402 else
403 len_dif = 0;
404 tp->t_rcvoopack++;
405 TCPSTAT_INC(tcps_rcvoopack);
406 TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
407 q->tqe_len = len;
408 q->tqe_flags = (flags & TH_FIN);
409 q->tqe_m->m_pkthdr.len = q->tqe_len;
410 tp->t_segqmbuflen += mbufoh;
411
412 }
413
414 static void
415 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
416 struct tseg_qent *q)
417 {
418 /*
419 * Merge q into ent and free q from the list.
420 */
421 #ifdef TCP_REASS_LOGGING
422 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
423 #endif
424 #ifdef TCP_REASS_COUNTERS
425 counter_u64_add(merge_into, 1);
426 #endif
427 ent->tqe_last->m_next = q->tqe_m;
428 ent->tqe_last = q->tqe_last;
429 ent->tqe_len += q->tqe_len;
430 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
431 ent->tqe_m->m_pkthdr.len += q->tqe_len;
432 ent->tqe_flags |= (q->tqe_flags & TH_FIN);
433 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
434 uma_zfree(tcp_reass_zone, q);
435 tp->t_segqlen--;
436
437 }
438
439 static void
440 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
441 {
442 struct tseg_qent *q, *qtmp;
443 int i;
444 tcp_seq max;
445 /*
446 * Given an entry merge forward anyplace
447 * that ent overlaps forward.
448 */
449
450 max = ent->tqe_start + ent->tqe_len;
451 q = TAILQ_NEXT(ent, tqe_q);
452 if (q == NULL) {
453 /* Nothing left */
454 return;
455 }
456 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
457 if (SEQ_GT(q->tqe_start, max)) {
458 /* Beyond q */
459 break;
460 }
461 /* We have some or all that are overlapping */
462 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
463 /* It consumes it all */
464 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
465 m_freem(q->tqe_m);
466 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
467 uma_zfree(tcp_reass_zone, q);
468 tp->t_segqlen--;
469 continue;
470 }
471 /*
472 * Trim the q entry to dovetail to this one
473 * and then merge q into ent updating max
474 * in the process.
475 */
476 i = max - q->tqe_start;
477 #ifdef TCP_REASS_LOGGING
478 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
479 #endif
480 m_adj(q->tqe_m, i);
481 q->tqe_len -= i;
482 q->tqe_start += i;
483 tcp_reass_merge_into(tp, ent, q);
484 max = ent->tqe_start + ent->tqe_len;
485 }
486 #ifdef TCP_REASS_COUNTERS
487 counter_u64_add(merge_fwd, 1);
488 #endif
489 }
490
491 static int
492 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
493 {
494 int len = MSIZE;
495
496 if (m->m_flags & M_EXT)
497 len += m->m_ext.ext_size;
498 while (m->m_next != NULL) {
499 m = m->m_next;
500 len += MSIZE;
501 if (m->m_flags & M_EXT)
502 len += m->m_ext.ext_size;
503 }
504 *mlast = m;
505 return (len);
506 }
507
508 /*
509 * NOTE!!! the new tcp-reassembly code *must not* use
510 * m_adj() with a negative index. That alters the chain
511 * of mbufs (by possibly chopping trailing mbufs). At
512 * the front of tcp_reass we count the mbuf overhead
513 * and setup the tail pointer. If we use m_adj(m, -5)
514 * we could corrupt the tail pointer. Currently the
515 * code only uses m_adj(m, postive-num). If this
516 * changes appropriate changes to update mlast would
517 * be needed.
518 */
519 int
520 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
521 int *tlenp, struct mbuf *m)
522 {
523 struct tseg_qent *q, *last, *first;
524 struct tseg_qent *p = NULL;
525 struct tseg_qent *nq = NULL;
526 struct tseg_qent *te = NULL;
527 struct mbuf *mlast = NULL;
528 struct inpcb *inp = tptoinpcb(tp);
529 struct socket *so = tptosocket(tp);
530 struct sockbuf *sb = &so->so_rcv;
531 char *s = NULL;
532 int flags, i, lenofoh;
533
534 INP_WLOCK_ASSERT(inp);
535 /*
536 * XXX: tcp_reass() is rather inefficient with its data structures
537 * and should be rewritten (see NetBSD for optimizations).
538 */
539
540 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL),
541 ("tcp_reass called with illegal parameter combination "
542 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)",
543 tp, th, seq_start, tlenp, m));
544 /*
545 * Call with th==NULL after become established to
546 * force pre-ESTABLISHED data up to user socket.
547 */
548 if (th == NULL)
549 goto present;
550 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
551 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
552 th, tp));
553 #ifdef TCP_REASS_LOGGING
554 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
555 #endif
556 #ifdef TCP_REASS_COUNTERS
557 counter_u64_add(reass_entry, 1);
558 #endif
559 /*
560 * Check for zero length data.
561 */
562 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) {
563 /*
564 * A zero length segment does no
565 * one any good. We could check
566 * the rcv_nxt <-> rcv_wnd but thats
567 * already done for us by the caller.
568 */
569 strip_fin:
570 #ifdef TCP_REASS_COUNTERS
571 counter_u64_add(tcp_zero_input, 1);
572 #endif
573 m_freem(m);
574 #ifdef TCP_REASS_LOGGING
575 tcp_reass_log_dump(tp);
576 #endif
577 return (0);
578 } else if ((*tlenp == 0) &&
579 (tcp_get_flags(th) & TH_FIN) &&
580 !TCPS_HAVEESTABLISHED(tp->t_state)) {
581 /*
582 * We have not established, and we
583 * have a FIN and no data. Lets treat
584 * this as the same as if the FIN were
585 * not present. We don't want to save
586 * the FIN bit in a reassembly buffer
587 * we want to get established first before
588 * we do that (the peer will retransmit).
589 */
590 goto strip_fin;
591 }
592 /*
593 * Will it fit?
594 */
595 lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
596 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
597 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
598 /* No room */
599 TCPSTAT_INC(tcps_rcvreassfull);
600 #ifdef TCP_REASS_COUNTERS
601 counter_u64_add(reass_nospace, 1);
602 #endif
603 #ifdef TCP_REASS_LOGGING
604 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
605 #endif
606 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
607 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, "
608 "segment dropped\n", s, __func__);
609 free(s, M_TCPLOG);
610 }
611 m_freem(m);
612 *tlenp = 0;
613 #ifdef TCP_REASS_LOGGING
614 tcp_reass_log_dump(tp);
615 #endif
616 return (0);
617 }
618 /*
619 * First lets deal with two common cases, the
620 * segment appends to the back of our collected
621 * segments. Or the segment is the next in line.
622 */
623 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
624 if (last != NULL) {
625 if ((tcp_get_flags(th) & TH_FIN) &&
626 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
627 /*
628 * Someone is trying to game us, dump
629 * the segment.
630 */
631 *tlenp = 0;
632 m_freem(m);
633 return (0);
634 }
635 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
636 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
637 /* Common case, trailing segment is added */
638 /**
639 * +--last
640 * v
641 * reassembly buffer |---| |---| |---|
642 * new segment |---|
643 */
644 #ifdef TCP_REASS_COUNTERS
645 counter_u64_add(reass_path1, 1);
646 #endif
647 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
648 i = (last->tqe_start + last->tqe_len) - th->th_seq;
649 if (i < *tlenp) {
650 #ifdef TCP_REASS_LOGGING
651 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
652 th->th_seq += i;
653 #endif
654 m_adj(m, i);
655 *tlenp -= i;
656 } else {
657 /* Complete overlap */
658 TCPSTAT_INC(tcps_rcvduppack);
659 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
660 m_freem(m);
661 *tlenp = last->tqe_len;
662 *seq_start = last->tqe_start;
663 return (0);
664 }
665 }
666 if (last->tqe_flags & TH_FIN) {
667 /*
668 * We have data after the FIN on the last?
669 */
670 *tlenp = 0;
671 m_freem(m);
672 return(0);
673 }
674 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
675 tp->t_segqmbuflen += lenofoh;
676 *seq_start = last->tqe_start;
677 *tlenp = last->tqe_len;
678 return (0);
679 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
680 /*
681 * Second common case, we missed
682 * another one and have something more
683 * for the end.
684 */
685 /**
686 * +--last
687 * v
688 * reassembly buffer |---| |---| |---|
689 * new segment |---|
690 */
691 if (last->tqe_flags & TH_FIN) {
692 /*
693 * We have data after the FIN on the last?
694 */
695 *tlenp = 0;
696 m_freem(m);
697 return(0);
698 }
699 #ifdef TCP_REASS_COUNTERS
700 counter_u64_add(reass_path2, 1);
701 #endif
702 p = last;
703 goto new_entry;
704 }
705 } else {
706 /* First segment (it's NULL). */
707 goto new_entry;
708 }
709 first = TAILQ_FIRST(&tp->t_segq);
710 if (SEQ_LT(th->th_seq, first->tqe_start) &&
711 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
712 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
713 /*
714 * The head of the queue is prepended by this and
715 * it may be the one I want most.
716 */
717 /**
718 * first-------+
719 * v
720 * rea: |---| |---| |---|
721 * new: |---|
722 * Note the case we do not deal with here is:
723 * rea= |---| |---| |---|
724 * new= |----|
725 * Due to the fact that it could be
726 * new |--------------------|
727 * And we might need to merge forward.
728 */
729 #ifdef INVARIANTS
730 struct mbuf *firstmbuf;
731 #endif
732
733 #ifdef TCP_REASS_COUNTERS
734 counter_u64_add(reass_path3, 1);
735 #endif
736 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
737 /*
738 * The resend was even before
739 * what we have. We need to trim it.
740 * Note TSNH (it should be trimmed
741 * before the call to tcp_reass()).
742 */
743 #ifdef INVARIANTS
744 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
745 th->th_seq, tp->rcv_nxt, tp);
746 #else
747 i = tp->rcv_nxt - th->th_seq;
748 #ifdef TCP_REASS_LOGGING
749 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
750 #endif
751 m_adj(m, i);
752 th->th_seq += i;
753 *tlenp -= i;
754 #endif
755 }
756 #ifdef INVARIANTS
757 firstmbuf = first->tqe_m;
758 #endif
759 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
760 #ifdef INVARIANTS
761 if (firstmbuf == first->tqe_m) {
762 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
763 m, firstmbuf, first->tqe_m, tp, first);
764 } else if (first->tqe_m != m) {
765 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
766 m, firstmbuf, first->tqe_m, tp, first);
767 }
768 #endif
769 tp->t_segqmbuflen += lenofoh;
770 *seq_start = first->tqe_start;
771 *tlenp = first->tqe_len;
772 goto present;
773 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
774 /* New segment is before our earliest segment. */
775 /**
776 * first---->+
777 * v
778 * rea= |---| ....
779 * new" |---|
780 *
781 */
782 goto new_entry;
783 }
784 /*
785 * Find a segment which begins after this one does.
786 */
787 #ifdef TCP_REASS_COUNTERS
788 counter_u64_add(reass_fullwalk, 1);
789 #endif
790 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
791 if (SEQ_GT(q->tqe_start, th->th_seq))
792 break;
793 }
794 p = TAILQ_PREV(q, tsegqe_head, tqe_q);
795 /**
796 * Now is this fit just in-between only?
797 * i.e.:
798 * p---+ +----q
799 * v v
800 * res= |--| |--| |--|
801 * nee |-|
802 */
803 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
804 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
805 /* Yep no overlap */
806 goto new_entry;
807 }
808 /**
809 * If we reach here we have some (possibly all) overlap
810 * such as:
811 * res= |--| |--| |--|
812 * new= |----|
813 * or new= |-----------------|
814 * or new= |--------|
815 * or new= |---|
816 * or new= |-----------|
817 */
818 if ((p != NULL) &&
819 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
820 /* conversion to int (in i) handles seq wraparound */
821
822 #ifdef TCP_REASS_COUNTERS
823 counter_u64_add(reass_path4, 1);
824 #endif
825 i = p->tqe_start + p->tqe_len - th->th_seq;
826 if (i >= 0) {
827 if (i >= *tlenp) {
828 /**
829 * prev seg---->+
830 * v
831 * reassembly buffer |---|
832 * new segment |-|
833 */
834 TCPSTAT_INC(tcps_rcvduppack);
835 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
836 *tlenp = p->tqe_len;
837 *seq_start = p->tqe_start;
838 m_freem(m);
839 /*
840 * Try to present any queued data
841 * at the left window edge to the user.
842 * This is needed after the 3-WHS
843 * completes. Note this probably
844 * will not work and we will return.
845 */
846 return (0);
847 }
848 if (i > 0) {
849 /**
850 * prev seg---->+
851 * v
852 * reassembly buffer |---|
853 * new segment |-----|
854 */
855 #ifdef TCP_REASS_COUNTERS
856 counter_u64_add(reass_path5, 1);
857 #endif
858 #ifdef TCP_REASS_LOGGING
859 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
860 #endif
861 m_adj(m, i);
862 *tlenp -= i;
863 th->th_seq += i;
864 }
865 }
866 if (th->th_seq == (p->tqe_start + p->tqe_len)) {
867 /*
868 * If dovetails in with this one
869 * append it.
870 */
871 /**
872 * prev seg---->+
873 * v
874 * reassembly buffer |--| |---|
875 * new segment |--|
876 * (note: it was trimmed above if it overlapped)
877 */
878 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
879 tp->t_segqmbuflen += lenofoh;
880 } else {
881 #ifdef INVARIANTS
882 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
883 th->th_seq, p->tqe_start, p->tqe_len,
884 p, tp);
885 #endif
886 *tlenp = 0;
887 m_freem(m);
888 return (0);
889 }
890 q = p;
891 } else {
892 /*
893 * The new data runs over the
894 * top of previously sack'd data (in q).
895 * It may be partially overlapping, or
896 * it may overlap the entire segment.
897 */
898 #ifdef TCP_REASS_COUNTERS
899 counter_u64_add(reass_path6, 1);
900 #endif
901 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
902 /* It consumes it all */
903 /**
904 * next seg---->+
905 * v
906 * reassembly buffer |--| |---|
907 * new segment |----------|
908 */
909 #ifdef TCP_REASS_COUNTERS
910 counter_u64_add(reass_path7, 1);
911 #endif
912 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th));
913 } else {
914 /*
915 * We just need to prepend the data
916 * to this. It does not overrun
917 * the end.
918 */
919 /**
920 * next seg---->+
921 * v
922 * reassembly buffer |--| |---|
923 * new segment |----------|
924 */
925 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
926 tp->t_segqmbuflen += lenofoh;
927 }
928 }
929 /* Now does it go further than that? */
930 tcp_reass_merge_forward(tp, q);
931 *seq_start = q->tqe_start;
932 *tlenp = q->tqe_len;
933 goto present;
934
935 /*
936 * When we reach here we can't combine it
937 * with any existing segment.
938 *
939 * Limit the number of segments that can be queued to reduce the
940 * potential for mbuf exhaustion. For best performance, we want to be
941 * able to queue a full window's worth of segments. The size of the
942 * socket receive buffer determines our advertised window and grows
943 * automatically when socket buffer autotuning is enabled. Use it as the
944 * basis for our queue limit.
945 *
946 * However, allow the user to specify a ceiling for the number of
947 * segments in each queue.
948 *
949 * Always let the missing segment through which caused this queue.
950 * NB: Access to the socket buffer is left intentionally unlocked as we
951 * can tolerate stale information here.
952 *
953 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
954 * should work but causes packets to be dropped when they shouldn't.
955 * Investigate why and re-evaluate the below limit after the behaviour
956 * is understood.
957 */
958 new_entry:
959 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) {
960 tp->rcv_nxt += *tlenp;
961 flags = tcp_get_flags(th) & TH_FIN;
962 TCPSTAT_INC(tcps_rcvoopack);
963 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
964 SOCKBUF_LOCK(&so->so_rcv);
965 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
966 m_freem(m);
967 } else {
968 sbappendstream_locked(&so->so_rcv, m, 0);
969 }
970 tp->t_flags |= TF_WAKESOR;
971 return (flags);
972 }
973 if (tcp_new_limits) {
974 if ((tp->t_segqlen > tcp_reass_queue_guard) &&
975 (*tlenp < MSIZE)) {
976 /*
977 * This is really a lie, we are not full but
978 * are getting a segment that is above
979 * guard threshold. If it is and its below
980 * a mbuf size (256) we drop it if it
981 * can't fill in some place.
982 */
983 TCPSTAT_INC(tcps_rcvreassfull);
984 *tlenp = 0;
985 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
986 log(LOG_DEBUG, "%s; %s: queue limit reached, "
987 "segment dropped\n", s, __func__);
988 free(s, M_TCPLOG);
989 }
990 m_freem(m);
991 #ifdef TCP_REASS_LOGGING
992 tcp_reass_log_dump(tp);
993 #endif
994 return (0);
995 }
996 } else {
997 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
998 tcp_reass_maxqueuelen)) {
999 TCPSTAT_INC(tcps_rcvreassfull);
1000 *tlenp = 0;
1001 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
1002 log(LOG_DEBUG, "%s; %s: queue limit reached, "
1003 "segment dropped\n", s, __func__);
1004 free(s, M_TCPLOG);
1005 }
1006 m_freem(m);
1007 #ifdef TCP_REASS_LOGGING
1008 tcp_reass_log_dump(tp);
1009 #endif
1010 return (0);
1011 }
1012 }
1013 /*
1014 * Allocate a new queue entry. If we can't, or hit the zone limit
1015 * just drop the pkt.
1016 */
1017 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
1018 if (te == NULL) {
1019 TCPSTAT_INC(tcps_rcvmemdrop);
1020 m_freem(m);
1021 *tlenp = 0;
1022 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
1023 log(LOG_DEBUG, "%s; %s: global zone limit "
1024 "reached, segment dropped\n", s, __func__);
1025 free(s, M_TCPLOG);
1026 }
1027 return (0);
1028 }
1029 tp->t_segqlen++;
1030 tp->t_rcvoopack++;
1031 TCPSTAT_INC(tcps_rcvoopack);
1032 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
1033 /* Insert the new segment queue entry into place. */
1034 te->tqe_m = m;
1035 te->tqe_flags = tcp_get_flags(th);
1036 te->tqe_len = *tlenp;
1037 te->tqe_start = th->th_seq;
1038 te->tqe_last = mlast;
1039 te->tqe_mbuf_cnt = lenofoh;
1040 tp->t_segqmbuflen += te->tqe_mbuf_cnt;
1041 if (p == NULL) {
1042 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
1043 } else {
1044 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
1045 }
1046 #ifdef TCP_REASS_LOGGING
1047 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
1048 #endif
1049 present:
1050 /*
1051 * Present data to user, advancing rcv_nxt through
1052 * completed sequence space.
1053 */
1054 if (!TCPS_HAVEESTABLISHED(tp->t_state))
1055 return (0);
1056 q = TAILQ_FIRST(&tp->t_segq);
1057 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
1058 ("Reassembly queue for %p has stale entry at head", tp));
1059 if (!q || q->tqe_start != tp->rcv_nxt) {
1060 #ifdef TCP_REASS_LOGGING
1061 tcp_reass_log_dump(tp);
1062 #endif
1063 return (0);
1064 }
1065 SOCKBUF_LOCK(&so->so_rcv);
1066 do {
1067 tp->rcv_nxt += q->tqe_len;
1068 flags = q->tqe_flags & TH_FIN;
1069 nq = TAILQ_NEXT(q, tqe_q);
1070 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
1071 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
1072 m_freem(q->tqe_m);
1073 } else {
1074 #ifdef TCP_REASS_LOGGING
1075 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
1076 if (th != NULL) {
1077 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
1078 } else {
1079 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1);
1080 }
1081 #endif
1082 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
1083 }
1084 #ifdef TCP_REASS_LOGGING
1085 if (th != NULL) {
1086 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
1087 } else {
1088 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2);
1089 }
1090 #endif
1091 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
1092 ("tp:%p seg queue goes negative", tp));
1093 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
1094 uma_zfree(tcp_reass_zone, q);
1095 tp->t_segqlen--;
1096 q = nq;
1097 } while (q && q->tqe_start == tp->rcv_nxt);
1098 if (TAILQ_EMPTY(&tp->t_segq) &&
1099 (tp->t_segqmbuflen != 0)) {
1100 #ifdef INVARIANTS
1101 panic("tp:%p segq:%p len:%d queue empty",
1102 tp, &tp->t_segq, tp->t_segqmbuflen);
1103 #else
1104 #ifdef TCP_REASS_LOGGING
1105 if (th != NULL) {
1106 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
1107 } else {
1108 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0);
1109 }
1110 #endif
1111 tp->t_segqmbuflen = 0;
1112 #endif
1113 }
1114 #ifdef TCP_REASS_LOGGING
1115 tcp_reass_log_dump(tp);
1116 #endif
1117 tp->t_flags |= TF_WAKESOR;
1118 return (flags);
1119 }
Cache object: a05433b718cb617e1fee31dcea486f7e
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