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
32 #include <sys/cdefs.h>
33 #include "opt_inet.h"
34 #include "opt_inet6.h"
35
36 /* For debugging we want counters and BB logging */
37 /* #define TCP_REASS_COUNTERS 1 */
38 /* #define TCP_REASS_LOGGING 1 */
39
40 #include <sys/param.h>
41 #include <sys/kernel.h>
42 #include <sys/eventhandler.h>
43 #include <sys/malloc.h>
44 #include <sys/mbuf.h>
45 #include <sys/socket.h>
46 #include <sys/socketvar.h>
47 #include <sys/sysctl.h>
48 #include <sys/syslog.h>
49 #include <sys/systm.h>
50
51 #include <vm/uma.h>
52
53 #include <net/if.h>
54 #include <net/if_var.h>
55 #include <net/route.h>
56 #include <net/vnet.h>
57
58 #include <netinet/in.h>
59 #include <netinet/in_pcb.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/in_var.h>
62 #include <netinet/ip.h>
63 #include <netinet/ip_var.h>
64 #include <netinet/ip_options.h>
65 #include <netinet/ip6.h>
66 #include <netinet6/in6_pcb.h>
67 #include <netinet6/ip6_var.h>
68 #include <netinet6/nd6.h>
69 #include <netinet/tcp.h>
70 #include <netinet/tcp_fsm.h>
71 #include <netinet/tcp_seq.h>
72 #include <netinet/tcp_timer.h>
73 #include <netinet/tcp_var.h>
74 #ifdef TCP_REASS_LOGGING
75 #include <netinet/tcp_log_buf.h>
76 #include <netinet/tcp_hpts.h>
77 #endif
78 #include <netinet/tcpip.h>
79
80 #define TCP_R_LOG_ADD 1
81 #define TCP_R_LOG_LIMIT_REACHED 2
82 #define TCP_R_LOG_APPEND 3
83 #define TCP_R_LOG_PREPEND 4
84 #define TCP_R_LOG_REPLACE 5
85 #define TCP_R_LOG_MERGE_INTO 6
86 #define TCP_R_LOG_NEW_ENTRY 7
87 #define TCP_R_LOG_READ 8
88 #define TCP_R_LOG_ZERO 9
89 #define TCP_R_LOG_DUMP 10
90 #define TCP_R_LOG_TRIM 11
91
92 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass,
93 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
94 "TCP Segment Reassembly Queue");
95
96 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats,
97 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
98 "TCP Segment Reassembly stats");
99
100 static int tcp_reass_maxseg = 0;
101 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
102 &tcp_reass_maxseg, 0,
103 "Global maximum number of TCP Segments in Reassembly Queue");
104
105 static uma_zone_t tcp_reass_zone;
106 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
107 &tcp_reass_zone,
108 "Global number of TCP Segments currently in Reassembly Queue");
109
110 static u_int tcp_reass_maxqueuelen = 100;
111 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
112 &tcp_reass_maxqueuelen, 0,
113 "Maximum number of TCP Segments per Reassembly Queue");
114
115 static int tcp_new_limits = 0;
116 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
117 &tcp_new_limits, 0,
118 "Do we use the new limit method we are discussing?");
119
120 static u_int tcp_reass_queue_guard = 16;
121 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
122 &tcp_reass_queue_guard, 16,
123 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
124
125 #ifdef TCP_REASS_COUNTERS
126
127 counter_u64_t reass_entry;
128 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
129 &reass_entry, "A segment entered reassembly ");
130
131 counter_u64_t reass_path1;
132 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
133 &reass_path1, "Took path 1");
134
135 counter_u64_t reass_path2;
136 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
137 &reass_path2, "Took path 2");
138
139 counter_u64_t reass_path3;
140 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
141 &reass_path3, "Took path 3");
142
143 counter_u64_t reass_path4;
144 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
145 &reass_path4, "Took path 4");
146
147 counter_u64_t reass_path5;
148 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
149 &reass_path5, "Took path 5");
150
151 counter_u64_t reass_path6;
152 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
153 &reass_path6, "Took path 6");
154
155 counter_u64_t reass_path7;
156 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
157 &reass_path7, "Took path 7");
158
159 counter_u64_t reass_fullwalk;
160 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
161 &reass_fullwalk, "Took a full walk ");
162
163 counter_u64_t reass_nospace;
164 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
165 &reass_nospace, "Had no mbuf capacity ");
166
167 counter_u64_t merge_fwd;
168 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
169 &merge_fwd, "Ran merge fwd");
170
171 counter_u64_t merge_into;
172 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
173 &merge_into, "Ran merge into");
174
175 counter_u64_t tcp_zero_input;
176 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
177 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
178
179 #endif
180
181 /* Initialize TCP reassembly queue */
182 static void
tcp_reass_zone_change(void * tag)183 tcp_reass_zone_change(void *tag)
184 {
185
186 /* Set the zone limit and read back the effective value. */
187 tcp_reass_maxseg = nmbclusters / 16;
188 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
189 tcp_reass_maxseg);
190 }
191
192 #ifdef TCP_REASS_LOGGING
193
194 static void
tcp_log_reassm(struct tcpcb * tp,struct tseg_qent * q,struct tseg_qent * p,tcp_seq seq,int len,uint8_t action,int instance)195 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
196 tcp_seq seq, int len, uint8_t action, int instance)
197 {
198 struct socket *so = tptosocket(tp);
199 uint32_t cts;
200 struct timeval tv;
201
202 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
203 union tcp_log_stackspecific log;
204
205 memset(&log, 0, sizeof(log));
206 cts = tcp_get_usecs(&tv);
207 log.u_bbr.flex1 = seq;
208 log.u_bbr.cur_del_rate = (uint64_t)q;
209 log.u_bbr.delRate = (uint64_t)p;
210 if (q != NULL) {
211 log.u_bbr.flex2 = q->tqe_start;
212 log.u_bbr.flex3 = q->tqe_len;
213 log.u_bbr.flex4 = q->tqe_mbuf_cnt;
214 log.u_bbr.hptsi_gain = q->tqe_flags;
215 }
216 if (p != NULL) {
217 log.u_bbr.flex5 = p->tqe_start;
218 log.u_bbr.pkts_out = p->tqe_len;
219 log.u_bbr.epoch = p->tqe_mbuf_cnt;
220 log.u_bbr.cwnd_gain = p->tqe_flags;
221 }
222 log.u_bbr.flex6 = tp->t_segqmbuflen;
223 log.u_bbr.flex7 = instance;
224 log.u_bbr.flex8 = action;
225 log.u_bbr.timeStamp = cts;
226 TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd,
227 TCP_LOG_REASS, 0,
228 len, &log, false, &tv);
229 }
230 }
231
232 static void
tcp_reass_log_dump(struct tcpcb * tp)233 tcp_reass_log_dump(struct tcpcb *tp)
234 {
235 struct tseg_qent *q;
236
237 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
238 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
239 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
240 }
241 };
242 }
243
244 static void
tcp_reass_log_new_in(struct tcpcb * tp,tcp_seq seq,int len,struct mbuf * m,int logval,struct tseg_qent * q)245 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
246 int logval, struct tseg_qent *q)
247 {
248 int cnt;
249 struct mbuf *t;
250
251 cnt = 0;
252 t = m;
253 while (t) {
254 cnt += t->m_len;
255 t = t->m_next;
256 }
257 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
258 }
259
260 #endif
261
262 void
tcp_reass_global_init(void)263 tcp_reass_global_init(void)
264 {
265
266 tcp_reass_maxseg = nmbclusters / 16;
267 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
268 &tcp_reass_maxseg);
269 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
270 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
271 /* Set the zone limit and read back the effective value. */
272 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
273 tcp_reass_maxseg);
274 #ifdef TCP_REASS_COUNTERS
275 reass_path1 = counter_u64_alloc(M_WAITOK);
276 reass_path2 = counter_u64_alloc(M_WAITOK);
277 reass_path3 = counter_u64_alloc(M_WAITOK);
278 reass_path4 = counter_u64_alloc(M_WAITOK);
279 reass_path5 = counter_u64_alloc(M_WAITOK);
280 reass_path6 = counter_u64_alloc(M_WAITOK);
281 reass_path7 = counter_u64_alloc(M_WAITOK);
282 reass_fullwalk = counter_u64_alloc(M_WAITOK);
283 reass_nospace = counter_u64_alloc(M_WAITOK);
284 reass_entry = counter_u64_alloc(M_WAITOK);
285 merge_fwd = counter_u64_alloc(M_WAITOK);
286 merge_into = counter_u64_alloc(M_WAITOK);
287 tcp_zero_input = counter_u64_alloc(M_WAITOK);
288 #endif
289 EVENTHANDLER_REGISTER(nmbclusters_change,
290 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
291
292 }
293
294 void
tcp_reass_flush(struct tcpcb * tp)295 tcp_reass_flush(struct tcpcb *tp)
296 {
297 struct tseg_qent *qe;
298
299 INP_WLOCK_ASSERT(tptoinpcb(tp));
300
301 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
302 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
303 m_freem(qe->tqe_m);
304 uma_zfree(tcp_reass_zone, qe);
305 tp->t_segqlen--;
306 }
307 tp->t_segqmbuflen = 0;
308 KASSERT((tp->t_segqlen == 0),
309 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
310 tp, tp->t_segqlen));
311 }
312
313 static void
tcp_reass_append(struct tcpcb * tp,struct tseg_qent * last,struct mbuf * m,struct tcphdr * th,int tlen,struct mbuf * mlast,int lenofoh)314 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
315 struct mbuf *m, struct tcphdr *th, int tlen,
316 struct mbuf *mlast, int lenofoh)
317 {
318
319 #ifdef TCP_REASS_LOGGING
320 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
321 #endif
322 last->tqe_len += tlen;
323 last->tqe_m->m_pkthdr.len += tlen;
324 /* Preserve the FIN bit if its there */
325 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN);
326 last->tqe_last->m_next = m;
327 last->tqe_last = mlast;
328 last->tqe_mbuf_cnt += lenofoh;
329 tp->t_rcvoopack++;
330 TCPSTAT_INC(tcps_rcvoopack);
331 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
332 #ifdef TCP_REASS_LOGGING
333 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
334 TCP_R_LOG_APPEND,
335 last);
336 #endif
337 }
338
339 static void
tcp_reass_prepend(struct tcpcb * tp,struct tseg_qent * first,struct mbuf * m,struct tcphdr * th,int tlen,struct mbuf * mlast,int lenofoh)340 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
341 int tlen, struct mbuf *mlast, int lenofoh)
342 {
343 int i;
344
345 #ifdef TCP_REASS_LOGGING
346 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
347 #endif
348 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
349 /* The new data overlaps into the old */
350 i = (th->th_seq + tlen) - first->tqe_start;
351 #ifdef TCP_REASS_LOGGING
352 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
353 #endif
354 m_adj(first->tqe_m, i);
355 first->tqe_len -= i;
356 first->tqe_start += i;
357 }
358 /* Ok now setup our chain to point to the old first */
359 mlast->m_next = first->tqe_m;
360 first->tqe_m = m;
361 first->tqe_len += tlen;
362 first->tqe_start = th->th_seq;
363 first->tqe_m->m_pkthdr.len = first->tqe_len;
364 first->tqe_mbuf_cnt += lenofoh;
365 tp->t_rcvoopack++;
366 TCPSTAT_INC(tcps_rcvoopack);
367 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
368 #ifdef TCP_REASS_LOGGING
369 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
370 TCP_R_LOG_PREPEND,
371 first);
372 #endif
373 }
374
375 static void
tcp_reass_replace(struct tcpcb * tp,struct tseg_qent * q,struct mbuf * m,tcp_seq seq,int len,struct mbuf * mlast,int mbufoh,uint16_t flags)376 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
377 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags)
378 {
379 /*
380 * Free the data in q, and replace
381 * it with the new segment.
382 */
383 int len_dif;
384
385 #ifdef TCP_REASS_LOGGING
386 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
387 #endif
388 m_freem(q->tqe_m);
389 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
390 ("Tp:%p seg queue goes negative", tp));
391 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
392 q->tqe_mbuf_cnt = mbufoh;
393 q->tqe_m = m;
394 q->tqe_last = mlast;
395 q->tqe_start = seq;
396 if (len > q->tqe_len)
397 len_dif = len - q->tqe_len;
398 else
399 len_dif = 0;
400 tp->t_rcvoopack++;
401 TCPSTAT_INC(tcps_rcvoopack);
402 TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
403 q->tqe_len = len;
404 q->tqe_flags = (flags & TH_FIN);
405 q->tqe_m->m_pkthdr.len = q->tqe_len;
406 tp->t_segqmbuflen += mbufoh;
407
408 }
409
410 static void
tcp_reass_merge_into(struct tcpcb * tp,struct tseg_qent * ent,struct tseg_qent * q)411 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
412 struct tseg_qent *q)
413 {
414 /*
415 * Merge q into ent and free q from the list.
416 */
417 #ifdef TCP_REASS_LOGGING
418 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
419 #endif
420 #ifdef TCP_REASS_COUNTERS
421 counter_u64_add(merge_into, 1);
422 #endif
423 ent->tqe_last->m_next = q->tqe_m;
424 ent->tqe_last = q->tqe_last;
425 ent->tqe_len += q->tqe_len;
426 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
427 ent->tqe_m->m_pkthdr.len += q->tqe_len;
428 ent->tqe_flags |= (q->tqe_flags & TH_FIN);
429 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
430 uma_zfree(tcp_reass_zone, q);
431 tp->t_segqlen--;
432
433 }
434
435 static void
tcp_reass_merge_forward(struct tcpcb * tp,struct tseg_qent * ent)436 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
437 {
438 struct tseg_qent *q, *qtmp;
439 int i;
440 tcp_seq max;
441 /*
442 * Given an entry merge forward anyplace
443 * that ent overlaps forward.
444 */
445
446 max = ent->tqe_start + ent->tqe_len;
447 q = TAILQ_NEXT(ent, tqe_q);
448 if (q == NULL) {
449 /* Nothing left */
450 return;
451 }
452 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
453 if (SEQ_GT(q->tqe_start, max)) {
454 /* Beyond q */
455 break;
456 }
457 /* We have some or all that are overlapping */
458 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
459 /* It consumes it all */
460 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
461 m_freem(q->tqe_m);
462 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
463 uma_zfree(tcp_reass_zone, q);
464 tp->t_segqlen--;
465 continue;
466 }
467 /*
468 * Trim the q entry to dovetail to this one
469 * and then merge q into ent updating max
470 * in the process.
471 */
472 i = max - q->tqe_start;
473 #ifdef TCP_REASS_LOGGING
474 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
475 #endif
476 m_adj(q->tqe_m, i);
477 q->tqe_len -= i;
478 q->tqe_start += i;
479 tcp_reass_merge_into(tp, ent, q);
480 max = ent->tqe_start + ent->tqe_len;
481 }
482 #ifdef TCP_REASS_COUNTERS
483 counter_u64_add(merge_fwd, 1);
484 #endif
485 }
486
487 static int
tcp_reass_overhead_of_chain(struct mbuf * m,struct mbuf ** mlast)488 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
489 {
490 int len = MSIZE;
491
492 if (m->m_flags & M_EXT)
493 len += m->m_ext.ext_size;
494 while (m->m_next != NULL) {
495 m = m->m_next;
496 len += MSIZE;
497 if (m->m_flags & M_EXT)
498 len += m->m_ext.ext_size;
499 }
500 *mlast = m;
501 return (len);
502 }
503
504 /*
505 * NOTE!!! the new tcp-reassembly code *must not* use
506 * m_adj() with a negative index. That alters the chain
507 * of mbufs (by possibly chopping trailing mbufs). At
508 * the front of tcp_reass we count the mbuf overhead
509 * and setup the tail pointer. If we use m_adj(m, -5)
510 * we could corrupt the tail pointer. Currently the
511 * code only uses m_adj(m, postive-num). If this
512 * changes appropriate changes to update mlast would
513 * be needed.
514 */
515 int
tcp_reass(struct tcpcb * tp,struct tcphdr * th,tcp_seq * seq_start,int * tlenp,struct mbuf * m)516 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
517 int *tlenp, struct mbuf *m)
518 {
519 struct tseg_qent *q, *last, *first;
520 struct tseg_qent *p = NULL;
521 struct tseg_qent *nq = NULL;
522 struct tseg_qent *te = NULL;
523 struct mbuf *mlast = NULL;
524 struct inpcb *inp = tptoinpcb(tp);
525 struct socket *so = tptosocket(tp);
526 struct sockbuf *sb = &so->so_rcv;
527 char *s = NULL;
528 int flags, i, lenofoh;
529
530 INP_WLOCK_ASSERT(inp);
531 /*
532 * XXX: tcp_reass() is rather inefficient with its data structures
533 * and should be rewritten (see NetBSD for optimizations).
534 */
535
536 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL),
537 ("tcp_reass called with illegal parameter combination "
538 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)",
539 tp, th, seq_start, tlenp, m));
540 /*
541 * Call with th==NULL after become established to
542 * force pre-ESTABLISHED data up to user socket.
543 */
544 if (th == NULL)
545 goto present;
546 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
547 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
548 th, tp));
549 #ifdef TCP_REASS_LOGGING
550 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
551 #endif
552 #ifdef TCP_REASS_COUNTERS
553 counter_u64_add(reass_entry, 1);
554 #endif
555 /*
556 * Check for zero length data.
557 */
558 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) {
559 /*
560 * A zero length segment does no
561 * one any good. We could check
562 * the rcv_nxt <-> rcv_wnd but thats
563 * already done for us by the caller.
564 */
565 strip_fin:
566 #ifdef TCP_REASS_COUNTERS
567 counter_u64_add(tcp_zero_input, 1);
568 #endif
569 m_freem(m);
570 #ifdef TCP_REASS_LOGGING
571 tcp_reass_log_dump(tp);
572 #endif
573 return (0);
574 } else if ((*tlenp == 0) &&
575 (tcp_get_flags(th) & TH_FIN) &&
576 !TCPS_HAVEESTABLISHED(tp->t_state)) {
577 /*
578 * We have not established, and we
579 * have a FIN and no data. Lets treat
580 * this as the same as if the FIN were
581 * not present. We don't want to save
582 * the FIN bit in a reassembly buffer
583 * we want to get established first before
584 * we do that (the peer will retransmit).
585 */
586 goto strip_fin;
587 }
588 /*
589 * Will it fit?
590 */
591 lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
592 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
593 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
594 /* No room */
595 TCPSTAT_INC(tcps_rcvreassfull);
596 #ifdef TCP_REASS_COUNTERS
597 counter_u64_add(reass_nospace, 1);
598 #endif
599 #ifdef TCP_REASS_LOGGING
600 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
601 #endif
602 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
603 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, "
604 "segment dropped\n", s, __func__);
605 free(s, M_TCPLOG);
606 }
607 m_freem(m);
608 *tlenp = 0;
609 #ifdef TCP_REASS_LOGGING
610 tcp_reass_log_dump(tp);
611 #endif
612 return (0);
613 }
614 /*
615 * First lets deal with two common cases, the
616 * segment appends to the back of our collected
617 * segments. Or the segment is the next in line.
618 */
619 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
620 if (last != NULL) {
621 if ((tcp_get_flags(th) & TH_FIN) &&
622 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
623 /*
624 * Someone is trying to game us, dump
625 * the segment.
626 */
627 *tlenp = 0;
628 m_freem(m);
629 return (0);
630 }
631 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
632 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
633 /* Common case, trailing segment is added */
634 /**
635 * +--last
636 * v
637 * reassembly buffer |---| |---| |---|
638 * new segment |---|
639 */
640 #ifdef TCP_REASS_COUNTERS
641 counter_u64_add(reass_path1, 1);
642 #endif
643 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
644 i = (last->tqe_start + last->tqe_len) - th->th_seq;
645 if (i < *tlenp) {
646 #ifdef TCP_REASS_LOGGING
647 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
648 th->th_seq += i;
649 #endif
650 m_adj(m, i);
651 *tlenp -= i;
652 } else {
653 /* Complete overlap */
654 TCPSTAT_INC(tcps_rcvduppack);
655 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
656 m_freem(m);
657 *tlenp = last->tqe_len;
658 *seq_start = last->tqe_start;
659 return (0);
660 }
661 }
662 if (last->tqe_flags & TH_FIN) {
663 /*
664 * We have data after the FIN on the last?
665 */
666 *tlenp = 0;
667 m_freem(m);
668 return(0);
669 }
670 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
671 tp->t_segqmbuflen += lenofoh;
672 *seq_start = last->tqe_start;
673 *tlenp = last->tqe_len;
674 return (0);
675 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
676 /*
677 * Second common case, we missed
678 * another one and have something more
679 * for the end.
680 */
681 /**
682 * +--last
683 * v
684 * reassembly buffer |---| |---| |---|
685 * new segment |---|
686 */
687 if (last->tqe_flags & TH_FIN) {
688 /*
689 * We have data after the FIN on the last?
690 */
691 *tlenp = 0;
692 m_freem(m);
693 return(0);
694 }
695 #ifdef TCP_REASS_COUNTERS
696 counter_u64_add(reass_path2, 1);
697 #endif
698 p = last;
699 goto new_entry;
700 }
701 } else {
702 /* First segment (it's NULL). */
703 goto new_entry;
704 }
705 first = TAILQ_FIRST(&tp->t_segq);
706 if (SEQ_LT(th->th_seq, first->tqe_start) &&
707 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
708 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
709 /*
710 * The head of the queue is prepended by this and
711 * it may be the one I want most.
712 */
713 /**
714 * first-------+
715 * v
716 * rea: |---| |---| |---|
717 * new: |---|
718 * Note the case we do not deal with here is:
719 * rea= |---| |---| |---|
720 * new= |----|
721 * Due to the fact that it could be
722 * new |--------------------|
723 * And we might need to merge forward.
724 */
725 #ifdef INVARIANTS
726 struct mbuf *firstmbuf;
727 #endif
728
729 #ifdef TCP_REASS_COUNTERS
730 counter_u64_add(reass_path3, 1);
731 #endif
732 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
733 /*
734 * The resend was even before
735 * what we have. We need to trim it.
736 * Note TSNH (it should be trimmed
737 * before the call to tcp_reass()).
738 */
739 #ifdef INVARIANTS
740 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
741 th->th_seq, tp->rcv_nxt, tp);
742 #else
743 i = tp->rcv_nxt - th->th_seq;
744 #ifdef TCP_REASS_LOGGING
745 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
746 #endif
747 m_adj(m, i);
748 th->th_seq += i;
749 *tlenp -= i;
750 #endif
751 }
752 #ifdef INVARIANTS
753 firstmbuf = first->tqe_m;
754 #endif
755 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
756 #ifdef INVARIANTS
757 if (firstmbuf == first->tqe_m) {
758 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
759 m, firstmbuf, first->tqe_m, tp, first);
760 } else if (first->tqe_m != m) {
761 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
762 m, firstmbuf, first->tqe_m, tp, first);
763 }
764 #endif
765 tp->t_segqmbuflen += lenofoh;
766 *seq_start = first->tqe_start;
767 *tlenp = first->tqe_len;
768 goto present;
769 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
770 /* New segment is before our earliest segment. */
771 /**
772 * first---->+
773 * v
774 * rea= |---| ....
775 * new" |---|
776 *
777 */
778 goto new_entry;
779 }
780 /*
781 * Find a segment which begins after this one does.
782 */
783 #ifdef TCP_REASS_COUNTERS
784 counter_u64_add(reass_fullwalk, 1);
785 #endif
786 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
787 if (SEQ_GT(q->tqe_start, th->th_seq))
788 break;
789 }
790 p = TAILQ_PREV(q, tsegqe_head, tqe_q);
791 /**
792 * Now is this fit just in-between only?
793 * i.e.:
794 * p---+ +----q
795 * v v
796 * res= |--| |--| |--|
797 * nee |-|
798 */
799 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
800 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
801 /* Yep no overlap */
802 goto new_entry;
803 }
804 /**
805 * If we reach here we have some (possibly all) overlap
806 * such as:
807 * res= |--| |--| |--|
808 * new= |----|
809 * or new= |-----------------|
810 * or new= |--------|
811 * or new= |---|
812 * or new= |-----------|
813 */
814 if ((p != NULL) &&
815 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
816 /* conversion to int (in i) handles seq wraparound */
817
818 #ifdef TCP_REASS_COUNTERS
819 counter_u64_add(reass_path4, 1);
820 #endif
821 i = p->tqe_start + p->tqe_len - th->th_seq;
822 if (i >= 0) {
823 if (i >= *tlenp) {
824 /**
825 * prev seg---->+
826 * v
827 * reassembly buffer |---|
828 * new segment |-|
829 */
830 TCPSTAT_INC(tcps_rcvduppack);
831 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
832 *tlenp = p->tqe_len;
833 *seq_start = p->tqe_start;
834 m_freem(m);
835 /*
836 * Try to present any queued data
837 * at the left window edge to the user.
838 * This is needed after the 3-WHS
839 * completes. Note this probably
840 * will not work and we will return.
841 */
842 return (0);
843 }
844 if (i > 0) {
845 /**
846 * prev seg---->+
847 * v
848 * reassembly buffer |---|
849 * new segment |-----|
850 */
851 #ifdef TCP_REASS_COUNTERS
852 counter_u64_add(reass_path5, 1);
853 #endif
854 #ifdef TCP_REASS_LOGGING
855 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
856 #endif
857 m_adj(m, i);
858 *tlenp -= i;
859 th->th_seq += i;
860 }
861 }
862 if (th->th_seq == (p->tqe_start + p->tqe_len)) {
863 /*
864 * If dovetails in with this one
865 * append it.
866 */
867 /**
868 * prev seg---->+
869 * v
870 * reassembly buffer |--| |---|
871 * new segment |--|
872 * (note: it was trimmed above if it overlapped)
873 */
874 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
875 tp->t_segqmbuflen += lenofoh;
876 } else {
877 #ifdef INVARIANTS
878 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
879 th->th_seq, p->tqe_start, p->tqe_len,
880 p, tp);
881 #endif
882 *tlenp = 0;
883 m_freem(m);
884 return (0);
885 }
886 q = p;
887 } else {
888 /*
889 * The new data runs over the
890 * top of previously sack'd data (in q).
891 * It may be partially overlapping, or
892 * it may overlap the entire segment.
893 */
894 #ifdef TCP_REASS_COUNTERS
895 counter_u64_add(reass_path6, 1);
896 #endif
897 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
898 /* It consumes it all */
899 /**
900 * next seg---->+
901 * v
902 * reassembly buffer |--| |---|
903 * new segment |----------|
904 */
905 #ifdef TCP_REASS_COUNTERS
906 counter_u64_add(reass_path7, 1);
907 #endif
908 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th));
909 } else {
910 /*
911 * We just need to prepend the data
912 * to this. It does not overrun
913 * the end.
914 */
915 /**
916 * next seg---->+
917 * v
918 * reassembly buffer |--| |---|
919 * new segment |----------|
920 */
921 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
922 tp->t_segqmbuflen += lenofoh;
923 }
924 }
925 /* Now does it go further than that? */
926 tcp_reass_merge_forward(tp, q);
927 *seq_start = q->tqe_start;
928 *tlenp = q->tqe_len;
929 goto present;
930
931 /*
932 * When we reach here we can't combine it
933 * with any existing segment.
934 *
935 * Limit the number of segments that can be queued to reduce the
936 * potential for mbuf exhaustion. For best performance, we want to be
937 * able to queue a full window's worth of segments. The size of the
938 * socket receive buffer determines our advertised window and grows
939 * automatically when socket buffer autotuning is enabled. Use it as the
940 * basis for our queue limit.
941 *
942 * However, allow the user to specify a ceiling for the number of
943 * segments in each queue.
944 *
945 * Always let the missing segment through which caused this queue.
946 * NB: Access to the socket buffer is left intentionally unlocked as we
947 * can tolerate stale information here.
948 *
949 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
950 * should work but causes packets to be dropped when they shouldn't.
951 * Investigate why and re-evaluate the below limit after the behaviour
952 * is understood.
953 */
954 new_entry:
955 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) {
956 tp->rcv_nxt += *tlenp;
957 flags = tcp_get_flags(th) & TH_FIN;
958 TCPSTAT_INC(tcps_rcvoopack);
959 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
960 SOCKBUF_LOCK(&so->so_rcv);
961 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
962 m_freem(m);
963 } else {
964 sbappendstream_locked(&so->so_rcv, m, 0);
965 }
966 tp->t_flags |= TF_WAKESOR;
967 return (flags);
968 }
969 if (tcp_new_limits) {
970 if ((tp->t_segqlen > tcp_reass_queue_guard) &&
971 (*tlenp < MSIZE)) {
972 /*
973 * This is really a lie, we are not full but
974 * are getting a segment that is above
975 * guard threshold. If it is and its below
976 * a mbuf size (256) we drop it if it
977 * can't fill in some place.
978 */
979 TCPSTAT_INC(tcps_rcvreassfull);
980 *tlenp = 0;
981 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
982 log(LOG_DEBUG, "%s; %s: queue limit reached, "
983 "segment dropped\n", s, __func__);
984 free(s, M_TCPLOG);
985 }
986 m_freem(m);
987 #ifdef TCP_REASS_LOGGING
988 tcp_reass_log_dump(tp);
989 #endif
990 return (0);
991 }
992 } else {
993 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
994 tcp_reass_maxqueuelen)) {
995 TCPSTAT_INC(tcps_rcvreassfull);
996 *tlenp = 0;
997 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
998 log(LOG_DEBUG, "%s; %s: queue limit reached, "
999 "segment dropped\n", s, __func__);
1000 free(s, M_TCPLOG);
1001 }
1002 m_freem(m);
1003 #ifdef TCP_REASS_LOGGING
1004 tcp_reass_log_dump(tp);
1005 #endif
1006 return (0);
1007 }
1008 }
1009 /*
1010 * Allocate a new queue entry. If we can't, or hit the zone limit
1011 * just drop the pkt.
1012 */
1013 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
1014 if (te == NULL) {
1015 TCPSTAT_INC(tcps_rcvmemdrop);
1016 m_freem(m);
1017 *tlenp = 0;
1018 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
1019 log(LOG_DEBUG, "%s; %s: global zone limit "
1020 "reached, segment dropped\n", s, __func__);
1021 free(s, M_TCPLOG);
1022 }
1023 return (0);
1024 }
1025 tp->t_segqlen++;
1026 tp->t_rcvoopack++;
1027 TCPSTAT_INC(tcps_rcvoopack);
1028 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
1029 /* Insert the new segment queue entry into place. */
1030 te->tqe_m = m;
1031 te->tqe_flags = tcp_get_flags(th);
1032 te->tqe_len = *tlenp;
1033 te->tqe_start = th->th_seq;
1034 te->tqe_last = mlast;
1035 te->tqe_mbuf_cnt = lenofoh;
1036 tp->t_segqmbuflen += te->tqe_mbuf_cnt;
1037 if (p == NULL) {
1038 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
1039 } else {
1040 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
1041 }
1042 #ifdef TCP_REASS_LOGGING
1043 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
1044 #endif
1045 present:
1046 /*
1047 * Present data to user, advancing rcv_nxt through
1048 * completed sequence space.
1049 */
1050 if (!TCPS_HAVEESTABLISHED(tp->t_state))
1051 return (0);
1052 q = TAILQ_FIRST(&tp->t_segq);
1053 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
1054 ("Reassembly queue for %p has stale entry at head", tp));
1055 if (!q || q->tqe_start != tp->rcv_nxt) {
1056 #ifdef TCP_REASS_LOGGING
1057 tcp_reass_log_dump(tp);
1058 #endif
1059 return (0);
1060 }
1061 SOCKBUF_LOCK(&so->so_rcv);
1062 do {
1063 tp->rcv_nxt += q->tqe_len;
1064 flags = q->tqe_flags & TH_FIN;
1065 nq = TAILQ_NEXT(q, tqe_q);
1066 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
1067 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
1068 m_freem(q->tqe_m);
1069 } else {
1070 #ifdef TCP_REASS_LOGGING
1071 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
1072 if (th != NULL) {
1073 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
1074 } else {
1075 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1);
1076 }
1077 #endif
1078 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
1079 }
1080 #ifdef TCP_REASS_LOGGING
1081 if (th != NULL) {
1082 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
1083 } else {
1084 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2);
1085 }
1086 #endif
1087 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
1088 ("tp:%p seg queue goes negative", tp));
1089 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
1090 uma_zfree(tcp_reass_zone, q);
1091 tp->t_segqlen--;
1092 q = nq;
1093 } while (q && q->tqe_start == tp->rcv_nxt);
1094 if (TAILQ_EMPTY(&tp->t_segq) &&
1095 (tp->t_segqmbuflen != 0)) {
1096 #ifdef INVARIANTS
1097 panic("tp:%p segq:%p len:%d queue empty",
1098 tp, &tp->t_segq, tp->t_segqmbuflen);
1099 #else
1100 #ifdef TCP_REASS_LOGGING
1101 if (th != NULL) {
1102 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
1103 } else {
1104 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0);
1105 }
1106 #endif
1107 tp->t_segqmbuflen = 0;
1108 #endif
1109 }
1110 #ifdef TCP_REASS_LOGGING
1111 tcp_reass_log_dump(tp);
1112 #endif
1113 tp->t_flags |= TF_WAKESOR;
1114 return (flags);
1115 }
1116