xref: /freebsd/sys/netinet/tcp_subr.c (revision d9f0ce31900a48d1a2bfc1c8c86f79d1e831451a)
1 /*-
2  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)tcp_subr.c	8.2 (Berkeley) 5/24/95
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include "opt_compat.h"
36 #include "opt_inet.h"
37 #include "opt_inet6.h"
38 #include "opt_ipsec.h"
39 #include "opt_tcpdebug.h"
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/callout.h>
44 #include <sys/eventhandler.h>
45 #include <sys/hhook.h>
46 #include <sys/kernel.h>
47 #include <sys/khelp.h>
48 #include <sys/sysctl.h>
49 #include <sys/jail.h>
50 #include <sys/malloc.h>
51 #include <sys/refcount.h>
52 #include <sys/mbuf.h>
53 #ifdef INET6
54 #include <sys/domain.h>
55 #endif
56 #include <sys/priv.h>
57 #include <sys/proc.h>
58 #include <sys/sdt.h>
59 #include <sys/socket.h>
60 #include <sys/socketvar.h>
61 #include <sys/protosw.h>
62 #include <sys/random.h>
63 
64 #include <vm/uma.h>
65 
66 #include <net/route.h>
67 #include <net/if.h>
68 #include <net/if_var.h>
69 #include <net/vnet.h>
70 
71 #include <netinet/in.h>
72 #include <netinet/in_fib.h>
73 #include <netinet/in_kdtrace.h>
74 #include <netinet/in_pcb.h>
75 #include <netinet/in_systm.h>
76 #include <netinet/in_var.h>
77 #include <netinet/ip.h>
78 #include <netinet/ip_icmp.h>
79 #include <netinet/ip_var.h>
80 #ifdef INET6
81 #include <netinet/ip6.h>
82 #include <netinet6/in6_fib.h>
83 #include <netinet6/in6_pcb.h>
84 #include <netinet6/ip6_var.h>
85 #include <netinet6/scope6_var.h>
86 #include <netinet6/nd6.h>
87 #endif
88 
89 #ifdef TCP_RFC7413
90 #include <netinet/tcp_fastopen.h>
91 #endif
92 #include <netinet/tcp.h>
93 #include <netinet/tcp_fsm.h>
94 #include <netinet/tcp_seq.h>
95 #include <netinet/tcp_timer.h>
96 #include <netinet/tcp_var.h>
97 #include <netinet/tcp_syncache.h>
98 #include <netinet/cc/cc.h>
99 #ifdef INET6
100 #include <netinet6/tcp6_var.h>
101 #endif
102 #include <netinet/tcpip.h>
103 #ifdef TCPPCAP
104 #include <netinet/tcp_pcap.h>
105 #endif
106 #ifdef TCPDEBUG
107 #include <netinet/tcp_debug.h>
108 #endif
109 #ifdef INET6
110 #include <netinet6/ip6protosw.h>
111 #endif
112 #ifdef TCP_OFFLOAD
113 #include <netinet/tcp_offload.h>
114 #endif
115 
116 #ifdef IPSEC
117 #include <netipsec/ipsec.h>
118 #include <netipsec/xform.h>
119 #ifdef INET6
120 #include <netipsec/ipsec6.h>
121 #endif
122 #include <netipsec/key.h>
123 #include <sys/syslog.h>
124 #endif /*IPSEC*/
125 
126 #include <machine/in_cksum.h>
127 #include <sys/md5.h>
128 
129 #include <security/mac/mac_framework.h>
130 
131 VNET_DEFINE(int, tcp_mssdflt) = TCP_MSS;
132 #ifdef INET6
133 VNET_DEFINE(int, tcp_v6mssdflt) = TCP6_MSS;
134 #endif
135 
136 struct rwlock tcp_function_lock;
137 
138 static int
139 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS)
140 {
141 	int error, new;
142 
143 	new = V_tcp_mssdflt;
144 	error = sysctl_handle_int(oidp, &new, 0, req);
145 	if (error == 0 && req->newptr) {
146 		if (new < TCP_MINMSS)
147 			error = EINVAL;
148 		else
149 			V_tcp_mssdflt = new;
150 	}
151 	return (error);
152 }
153 
154 SYSCTL_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
155     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, &VNET_NAME(tcp_mssdflt), 0,
156     &sysctl_net_inet_tcp_mss_check, "I",
157     "Default TCP Maximum Segment Size");
158 
159 #ifdef INET6
160 static int
161 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS)
162 {
163 	int error, new;
164 
165 	new = V_tcp_v6mssdflt;
166 	error = sysctl_handle_int(oidp, &new, 0, req);
167 	if (error == 0 && req->newptr) {
168 		if (new < TCP_MINMSS)
169 			error = EINVAL;
170 		else
171 			V_tcp_v6mssdflt = new;
172 	}
173 	return (error);
174 }
175 
176 SYSCTL_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
177     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, &VNET_NAME(tcp_v6mssdflt), 0,
178     &sysctl_net_inet_tcp_mss_v6_check, "I",
179    "Default TCP Maximum Segment Size for IPv6");
180 #endif /* INET6 */
181 
182 /*
183  * Minimum MSS we accept and use. This prevents DoS attacks where
184  * we are forced to a ridiculous low MSS like 20 and send hundreds
185  * of packets instead of one. The effect scales with the available
186  * bandwidth and quickly saturates the CPU and network interface
187  * with packet generation and sending. Set to zero to disable MINMSS
188  * checking. This setting prevents us from sending too small packets.
189  */
190 VNET_DEFINE(int, tcp_minmss) = TCP_MINMSS;
191 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_VNET | CTLFLAG_RW,
192      &VNET_NAME(tcp_minmss), 0,
193     "Minimum TCP Maximum Segment Size");
194 
195 VNET_DEFINE(int, tcp_do_rfc1323) = 1;
196 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_VNET | CTLFLAG_RW,
197     &VNET_NAME(tcp_do_rfc1323), 0,
198     "Enable rfc1323 (high performance TCP) extensions");
199 
200 static int	tcp_log_debug = 0;
201 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
202     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
203 
204 static int	tcp_tcbhashsize;
205 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
206     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
207 
208 static int	do_tcpdrain = 1;
209 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
210     "Enable tcp_drain routine for extra help when low on mbufs");
211 
212 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_VNET | CTLFLAG_RD,
213     &VNET_NAME(tcbinfo.ipi_count), 0, "Number of active PCBs");
214 
215 static VNET_DEFINE(int, icmp_may_rst) = 1;
216 #define	V_icmp_may_rst			VNET(icmp_may_rst)
217 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_VNET | CTLFLAG_RW,
218     &VNET_NAME(icmp_may_rst), 0,
219     "Certain ICMP unreachable messages may abort connections in SYN_SENT");
220 
221 static VNET_DEFINE(int, tcp_isn_reseed_interval) = 0;
222 #define	V_tcp_isn_reseed_interval	VNET(tcp_isn_reseed_interval)
223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_VNET | CTLFLAG_RW,
224     &VNET_NAME(tcp_isn_reseed_interval), 0,
225     "Seconds between reseeding of ISN secret");
226 
227 static int	tcp_soreceive_stream;
228 SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
229     &tcp_soreceive_stream, 0, "Using soreceive_stream for TCP sockets");
230 
231 #ifdef TCP_SIGNATURE
232 static int	tcp_sig_checksigs = 1;
233 SYSCTL_INT(_net_inet_tcp, OID_AUTO, signature_verify_input, CTLFLAG_RW,
234     &tcp_sig_checksigs, 0, "Verify RFC2385 digests on inbound traffic");
235 #endif
236 
237 VNET_DEFINE(uma_zone_t, sack_hole_zone);
238 #define	V_sack_hole_zone		VNET(sack_hole_zone)
239 
240 VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
241 
242 static struct inpcb *tcp_notify(struct inpcb *, int);
243 static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
244 static void tcp_mtudisc(struct inpcb *, int);
245 static char *	tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
246 		    void *ip4hdr, const void *ip6hdr);
247 static void	tcp_timer_discard(struct tcpcb *, uint32_t);
248 
249 
250 static struct tcp_function_block tcp_def_funcblk = {
251 	"default",
252 	tcp_output,
253 	tcp_do_segment,
254 	tcp_default_ctloutput,
255 	NULL,
256 	NULL,
257 	NULL,
258 	NULL,
259 	NULL,
260 	NULL,
261 	NULL,
262 	0,
263 	0
264 };
265 
266 int t_functions_inited = 0;
267 struct tcp_funchead t_functions;
268 static struct tcp_function_block *tcp_func_set_ptr = &tcp_def_funcblk;
269 
270 static void
271 init_tcp_functions(void)
272 {
273 	if (t_functions_inited == 0) {
274 		TAILQ_INIT(&t_functions);
275 		rw_init_flags(&tcp_function_lock, "tcp_func_lock" , 0);
276 		t_functions_inited = 1;
277 	}
278 }
279 
280 static struct tcp_function_block *
281 find_tcp_functions_locked(struct tcp_function_set *fs)
282 {
283 	struct tcp_function *f;
284 	struct tcp_function_block *blk=NULL;
285 
286 	TAILQ_FOREACH(f, &t_functions, tf_next) {
287 		if (strcmp(f->tf_fb->tfb_tcp_block_name, fs->function_set_name) == 0) {
288 			blk = f->tf_fb;
289 			break;
290 		}
291 	}
292 	return(blk);
293 }
294 
295 static struct tcp_function_block *
296 find_tcp_fb_locked(struct tcp_function_block *blk, struct tcp_function **s)
297 {
298 	struct tcp_function_block *rblk=NULL;
299 	struct tcp_function *f;
300 
301 	TAILQ_FOREACH(f, &t_functions, tf_next) {
302 		if (f->tf_fb == blk) {
303 			rblk = blk;
304 			if (s) {
305 				*s = f;
306 			}
307 			break;
308 		}
309 	}
310 	return (rblk);
311 }
312 
313 struct tcp_function_block *
314 find_and_ref_tcp_functions(struct tcp_function_set *fs)
315 {
316 	struct tcp_function_block *blk;
317 
318 	rw_rlock(&tcp_function_lock);
319 	blk = find_tcp_functions_locked(fs);
320 	if (blk)
321 		refcount_acquire(&blk->tfb_refcnt);
322 	rw_runlock(&tcp_function_lock);
323 	return(blk);
324 }
325 
326 struct tcp_function_block *
327 find_and_ref_tcp_fb(struct tcp_function_block *blk)
328 {
329 	struct tcp_function_block *rblk;
330 
331 	rw_rlock(&tcp_function_lock);
332 	rblk = find_tcp_fb_locked(blk, NULL);
333 	if (rblk)
334 		refcount_acquire(&rblk->tfb_refcnt);
335 	rw_runlock(&tcp_function_lock);
336 	return(rblk);
337 }
338 
339 
340 static int
341 sysctl_net_inet_default_tcp_functions(SYSCTL_HANDLER_ARGS)
342 {
343 	int error=ENOENT;
344 	struct tcp_function_set fs;
345 	struct tcp_function_block *blk;
346 
347 	memset(&fs, 0, sizeof(fs));
348 	rw_rlock(&tcp_function_lock);
349 	blk = find_tcp_fb_locked(tcp_func_set_ptr, NULL);
350 	if (blk) {
351 		/* Found him */
352 		strcpy(fs.function_set_name, blk->tfb_tcp_block_name);
353 		fs.pcbcnt = blk->tfb_refcnt;
354 	}
355 	rw_runlock(&tcp_function_lock);
356 	error = sysctl_handle_string(oidp, fs.function_set_name,
357 				     sizeof(fs.function_set_name), req);
358 
359 	/* Check for error or no change */
360 	if (error != 0 || req->newptr == NULL)
361 		return(error);
362 
363 	rw_wlock(&tcp_function_lock);
364 	blk = find_tcp_functions_locked(&fs);
365 	if ((blk == NULL) ||
366 	    (blk->tfb_flags & TCP_FUNC_BEING_REMOVED)) {
367 		error = ENOENT;
368 		goto done;
369 	}
370 	tcp_func_set_ptr = blk;
371 done:
372 	rw_wunlock(&tcp_function_lock);
373 	return (error);
374 }
375 
376 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_default,
377 	    CTLTYPE_STRING | CTLFLAG_RW,
378 	    NULL, 0, sysctl_net_inet_default_tcp_functions, "A",
379 	    "Set/get the default TCP functions");
380 
381 static int
382 sysctl_net_inet_list_available(SYSCTL_HANDLER_ARGS)
383 {
384 	int error, cnt, linesz;
385 	struct tcp_function *f;
386 	char *buffer, *cp;
387 	size_t bufsz, outsz;
388 
389 	cnt = 0;
390 	rw_rlock(&tcp_function_lock);
391 	TAILQ_FOREACH(f, &t_functions, tf_next) {
392 		cnt++;
393 	}
394 	rw_runlock(&tcp_function_lock);
395 
396 	bufsz = (cnt+2) * (TCP_FUNCTION_NAME_LEN_MAX + 12) + 1;
397 	buffer = malloc(bufsz, M_TEMP, M_WAITOK);
398 
399 	error = 0;
400 	cp = buffer;
401 
402 	linesz = snprintf(cp, bufsz, "\n%-32s%c %s\n", "Stack", 'D', "PCB count");
403 	cp += linesz;
404 	bufsz -= linesz;
405 	outsz = linesz;
406 
407 	rw_rlock(&tcp_function_lock);
408 	TAILQ_FOREACH(f, &t_functions, tf_next) {
409 		linesz = snprintf(cp, bufsz, "%-32s%c %u\n",
410 		    f->tf_fb->tfb_tcp_block_name,
411 		    (f->tf_fb == tcp_func_set_ptr) ? '*' : ' ',
412 		    f->tf_fb->tfb_refcnt);
413 		if (linesz >= bufsz) {
414 			error = EOVERFLOW;
415 			break;
416 		}
417 		cp += linesz;
418 		bufsz -= linesz;
419 		outsz += linesz;
420 	}
421 	rw_runlock(&tcp_function_lock);
422 	if (error == 0)
423 		error = sysctl_handle_string(oidp, buffer, outsz + 1, req);
424 	free(buffer, M_TEMP);
425 	return (error);
426 }
427 
428 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_available,
429 	    CTLTYPE_STRING|CTLFLAG_RD,
430 	    NULL, 0, sysctl_net_inet_list_available, "A",
431 	    "list available TCP Function sets");
432 
433 /*
434  * Target size of TCP PCB hash tables. Must be a power of two.
435  *
436  * Note that this can be overridden by the kernel environment
437  * variable net.inet.tcp.tcbhashsize
438  */
439 #ifndef TCBHASHSIZE
440 #define TCBHASHSIZE	0
441 #endif
442 
443 /*
444  * XXX
445  * Callouts should be moved into struct tcp directly.  They are currently
446  * separate because the tcpcb structure is exported to userland for sysctl
447  * parsing purposes, which do not know about callouts.
448  */
449 struct tcpcb_mem {
450 	struct	tcpcb		tcb;
451 	struct	tcp_timer	tt;
452 	struct	cc_var		ccv;
453 	struct	osd		osd;
454 };
455 
456 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
457 #define	V_tcpcb_zone			VNET(tcpcb_zone)
458 
459 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
460 MALLOC_DEFINE(M_TCPFUNCTIONS, "tcpfunc", "TCP function set memory");
461 
462 static struct mtx isn_mtx;
463 
464 #define	ISN_LOCK_INIT()	mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
465 #define	ISN_LOCK()	mtx_lock(&isn_mtx)
466 #define	ISN_UNLOCK()	mtx_unlock(&isn_mtx)
467 
468 /*
469  * TCP initialization.
470  */
471 static void
472 tcp_zone_change(void *tag)
473 {
474 
475 	uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
476 	uma_zone_set_max(V_tcpcb_zone, maxsockets);
477 	tcp_tw_zone_change();
478 }
479 
480 static int
481 tcp_inpcb_init(void *mem, int size, int flags)
482 {
483 	struct inpcb *inp = mem;
484 
485 	INP_LOCK_INIT(inp, "inp", "tcpinp");
486 	return (0);
487 }
488 
489 /*
490  * Take a value and get the next power of 2 that doesn't overflow.
491  * Used to size the tcp_inpcb hash buckets.
492  */
493 static int
494 maketcp_hashsize(int size)
495 {
496 	int hashsize;
497 
498 	/*
499 	 * auto tune.
500 	 * get the next power of 2 higher than maxsockets.
501 	 */
502 	hashsize = 1 << fls(size);
503 	/* catch overflow, and just go one power of 2 smaller */
504 	if (hashsize < size) {
505 		hashsize = 1 << (fls(size) - 1);
506 	}
507 	return (hashsize);
508 }
509 
510 int
511 register_tcp_functions(struct tcp_function_block *blk, int wait)
512 {
513 	struct tcp_function_block *lblk;
514 	struct tcp_function *n;
515 	struct tcp_function_set fs;
516 
517 	if (t_functions_inited == 0) {
518 		init_tcp_functions();
519 	}
520 	if ((blk->tfb_tcp_output == NULL) ||
521 	    (blk->tfb_tcp_do_segment == NULL) ||
522 	    (blk->tfb_tcp_ctloutput == NULL) ||
523 	    (strlen(blk->tfb_tcp_block_name) == 0)) {
524 		/*
525 		 * These functions are required and you
526 		 * need a name.
527 		 */
528 		return (EINVAL);
529 	}
530 	if (blk->tfb_tcp_timer_stop_all ||
531 	    blk->tfb_tcp_timers_left ||
532 	    blk->tfb_tcp_timer_activate ||
533 	    blk->tfb_tcp_timer_active ||
534 	    blk->tfb_tcp_timer_stop) {
535 		/*
536 		 * If you define one timer function you
537 		 * must have them all.
538 		 */
539 		if ((blk->tfb_tcp_timer_stop_all == NULL) ||
540 		    (blk->tfb_tcp_timers_left  == NULL) ||
541 		    (blk->tfb_tcp_timer_activate == NULL) ||
542 		    (blk->tfb_tcp_timer_active == NULL) ||
543 		    (blk->tfb_tcp_timer_stop == NULL)) {
544 			return (EINVAL);
545 		}
546 	}
547 	n = malloc(sizeof(struct tcp_function), M_TCPFUNCTIONS, wait);
548 	if (n == NULL) {
549 		return (ENOMEM);
550 	}
551 	n->tf_fb = blk;
552 	strcpy(fs.function_set_name, blk->tfb_tcp_block_name);
553 	rw_wlock(&tcp_function_lock);
554 	lblk = find_tcp_functions_locked(&fs);
555 	if (lblk) {
556 		/* Duplicate name space not allowed */
557 		rw_wunlock(&tcp_function_lock);
558 		free(n, M_TCPFUNCTIONS);
559 		return (EALREADY);
560 	}
561 	refcount_init(&blk->tfb_refcnt, 0);
562 	blk->tfb_flags = 0;
563 	TAILQ_INSERT_TAIL(&t_functions, n, tf_next);
564 	rw_wunlock(&tcp_function_lock);
565 	return(0);
566 }
567 
568 int
569 deregister_tcp_functions(struct tcp_function_block *blk)
570 {
571 	struct tcp_function_block *lblk;
572 	struct tcp_function *f;
573 	int error=ENOENT;
574 
575 	if (strcmp(blk->tfb_tcp_block_name, "default") == 0) {
576 		/* You can't un-register the default */
577 		return (EPERM);
578 	}
579 	rw_wlock(&tcp_function_lock);
580 	if (blk == tcp_func_set_ptr) {
581 		/* You can't free the current default */
582 		rw_wunlock(&tcp_function_lock);
583 		return (EBUSY);
584 	}
585 	if (blk->tfb_refcnt) {
586 		/* Still tcb attached, mark it. */
587 		blk->tfb_flags |= TCP_FUNC_BEING_REMOVED;
588 		rw_wunlock(&tcp_function_lock);
589 		return (EBUSY);
590 	}
591 	lblk = find_tcp_fb_locked(blk, &f);
592 	if (lblk) {
593 		/* Found */
594 		TAILQ_REMOVE(&t_functions, f, tf_next);
595 		f->tf_fb = NULL;
596 		free(f, M_TCPFUNCTIONS);
597 		error = 0;
598 	}
599 	rw_wunlock(&tcp_function_lock);
600 	return (error);
601 }
602 
603 void
604 tcp_init(void)
605 {
606 	const char *tcbhash_tuneable;
607 	int hashsize;
608 
609 	tcbhash_tuneable = "net.inet.tcp.tcbhashsize";
610 
611 	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
612 	    &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
613 		printf("%s: WARNING: unable to register helper hook\n", __func__);
614 	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
615 	    &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
616 		printf("%s: WARNING: unable to register helper hook\n", __func__);
617 	hashsize = TCBHASHSIZE;
618 	TUNABLE_INT_FETCH(tcbhash_tuneable, &hashsize);
619 	if (hashsize == 0) {
620 		/*
621 		 * Auto tune the hash size based on maxsockets.
622 		 * A perfect hash would have a 1:1 mapping
623 		 * (hashsize = maxsockets) however it's been
624 		 * suggested that O(2) average is better.
625 		 */
626 		hashsize = maketcp_hashsize(maxsockets / 4);
627 		/*
628 		 * Our historical default is 512,
629 		 * do not autotune lower than this.
630 		 */
631 		if (hashsize < 512)
632 			hashsize = 512;
633 		if (bootverbose && IS_DEFAULT_VNET(curvnet))
634 			printf("%s: %s auto tuned to %d\n", __func__,
635 			    tcbhash_tuneable, hashsize);
636 	}
637 	/*
638 	 * We require a hashsize to be a power of two.
639 	 * Previously if it was not a power of two we would just reset it
640 	 * back to 512, which could be a nasty surprise if you did not notice
641 	 * the error message.
642 	 * Instead what we do is clip it to the closest power of two lower
643 	 * than the specified hash value.
644 	 */
645 	if (!powerof2(hashsize)) {
646 		int oldhashsize = hashsize;
647 
648 		hashsize = maketcp_hashsize(hashsize);
649 		/* prevent absurdly low value */
650 		if (hashsize < 16)
651 			hashsize = 16;
652 		printf("%s: WARNING: TCB hash size not a power of 2, "
653 		    "clipped from %d to %d.\n", __func__, oldhashsize,
654 		    hashsize);
655 	}
656 	in_pcbinfo_init(&V_tcbinfo, "tcp", &V_tcb, hashsize, hashsize,
657 	    "tcp_inpcb", tcp_inpcb_init, NULL, 0, IPI_HASHFIELDS_4TUPLE);
658 
659 	/*
660 	 * These have to be type stable for the benefit of the timers.
661 	 */
662 	V_tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
663 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
664 	uma_zone_set_max(V_tcpcb_zone, maxsockets);
665 	uma_zone_set_warning(V_tcpcb_zone, "kern.ipc.maxsockets limit reached");
666 
667 	tcp_tw_init();
668 	syncache_init();
669 	tcp_hc_init();
670 
671 	TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
672 	V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
673 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
674 
675 	/* Skip initialization of globals for non-default instances. */
676 	if (!IS_DEFAULT_VNET(curvnet))
677 		return;
678 
679 	tcp_reass_global_init();
680 
681 	/* XXX virtualize those bellow? */
682 	tcp_delacktime = TCPTV_DELACK;
683 	tcp_keepinit = TCPTV_KEEP_INIT;
684 	tcp_keepidle = TCPTV_KEEP_IDLE;
685 	tcp_keepintvl = TCPTV_KEEPINTVL;
686 	tcp_maxpersistidle = TCPTV_KEEP_IDLE;
687 	tcp_msl = TCPTV_MSL;
688 	tcp_rexmit_min = TCPTV_MIN;
689 	if (tcp_rexmit_min < 1)
690 		tcp_rexmit_min = 1;
691 	tcp_persmin = TCPTV_PERSMIN;
692 	tcp_persmax = TCPTV_PERSMAX;
693 	tcp_rexmit_slop = TCPTV_CPU_VAR;
694 	tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
695 	tcp_tcbhashsize = hashsize;
696 	/* Setup the tcp function block list */
697 	init_tcp_functions();
698 	register_tcp_functions(&tcp_def_funcblk, M_WAITOK);
699 
700 	if (tcp_soreceive_stream) {
701 #ifdef INET
702 		tcp_usrreqs.pru_soreceive = soreceive_stream;
703 #endif
704 #ifdef INET6
705 		tcp6_usrreqs.pru_soreceive = soreceive_stream;
706 #endif /* INET6 */
707 	}
708 
709 #ifdef INET6
710 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
711 #else /* INET6 */
712 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
713 #endif /* INET6 */
714 	if (max_protohdr < TCP_MINPROTOHDR)
715 		max_protohdr = TCP_MINPROTOHDR;
716 	if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
717 		panic("tcp_init");
718 #undef TCP_MINPROTOHDR
719 
720 	ISN_LOCK_INIT();
721 	EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
722 		SHUTDOWN_PRI_DEFAULT);
723 	EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
724 		EVENTHANDLER_PRI_ANY);
725 #ifdef TCPPCAP
726 	tcp_pcap_init();
727 #endif
728 
729 #ifdef TCP_RFC7413
730 	tcp_fastopen_init();
731 #endif
732 }
733 
734 #ifdef VIMAGE
735 void
736 tcp_destroy(void)
737 {
738 	int error;
739 
740 	/*
741 	 * All our processes are gone, all our sockets should be cleaned
742 	 * up, which means, we should be past the tcp_discardcb() calls.
743 	 * Sleep to let all tcpcb timers really disappear and then cleanup.
744 	 * Timewait will cleanup its queue and will be ready to go.
745 	 * XXX-BZ In theory a few ticks should be good enough to make sure
746 	 * the timers are all really gone.  We should see if we could use a
747 	 * better metric here and, e.g., check a tcbcb count as an optimization?
748 	 */
749 	DELAY(1000000 / hz);
750 	tcp_hc_destroy();
751 	syncache_destroy();
752 	tcp_tw_destroy();
753 	in_pcbinfo_destroy(&V_tcbinfo);
754 	/* tcp_discardcb() clears the sack_holes up. */
755 	uma_zdestroy(V_sack_hole_zone);
756 	uma_zdestroy(V_tcpcb_zone);
757 
758 #ifdef TCP_RFC7413
759 	/*
760 	 * Cannot free the zone until all tcpcbs are released as we attach
761 	 * the allocations to them.
762 	 */
763 	tcp_fastopen_destroy();
764 #endif
765 
766 	error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_IN]);
767 	if (error != 0) {
768 		printf("%s: WARNING: unable to deregister helper hook "
769 		    "type=%d, id=%d: error %d returned\n", __func__,
770 		    HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN, error);
771 	}
772 	error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_OUT]);
773 	if (error != 0) {
774 		printf("%s: WARNING: unable to deregister helper hook "
775 		    "type=%d, id=%d: error %d returned\n", __func__,
776 		    HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT, error);
777 	}
778 }
779 #endif
780 
781 void
782 tcp_fini(void *xtp)
783 {
784 
785 }
786 
787 /*
788  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
789  * tcp_template used to store this data in mbufs, but we now recopy it out
790  * of the tcpcb each time to conserve mbufs.
791  */
792 void
793 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
794 {
795 	struct tcphdr *th = (struct tcphdr *)tcp_ptr;
796 
797 	INP_WLOCK_ASSERT(inp);
798 
799 #ifdef INET6
800 	if ((inp->inp_vflag & INP_IPV6) != 0) {
801 		struct ip6_hdr *ip6;
802 
803 		ip6 = (struct ip6_hdr *)ip_ptr;
804 		ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
805 			(inp->inp_flow & IPV6_FLOWINFO_MASK);
806 		ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
807 			(IPV6_VERSION & IPV6_VERSION_MASK);
808 		ip6->ip6_nxt = IPPROTO_TCP;
809 		ip6->ip6_plen = htons(sizeof(struct tcphdr));
810 		ip6->ip6_src = inp->in6p_laddr;
811 		ip6->ip6_dst = inp->in6p_faddr;
812 	}
813 #endif /* INET6 */
814 #if defined(INET6) && defined(INET)
815 	else
816 #endif
817 #ifdef INET
818 	{
819 		struct ip *ip;
820 
821 		ip = (struct ip *)ip_ptr;
822 		ip->ip_v = IPVERSION;
823 		ip->ip_hl = 5;
824 		ip->ip_tos = inp->inp_ip_tos;
825 		ip->ip_len = 0;
826 		ip->ip_id = 0;
827 		ip->ip_off = 0;
828 		ip->ip_ttl = inp->inp_ip_ttl;
829 		ip->ip_sum = 0;
830 		ip->ip_p = IPPROTO_TCP;
831 		ip->ip_src = inp->inp_laddr;
832 		ip->ip_dst = inp->inp_faddr;
833 	}
834 #endif /* INET */
835 	th->th_sport = inp->inp_lport;
836 	th->th_dport = inp->inp_fport;
837 	th->th_seq = 0;
838 	th->th_ack = 0;
839 	th->th_x2 = 0;
840 	th->th_off = 5;
841 	th->th_flags = 0;
842 	th->th_win = 0;
843 	th->th_urp = 0;
844 	th->th_sum = 0;		/* in_pseudo() is called later for ipv4 */
845 }
846 
847 /*
848  * Create template to be used to send tcp packets on a connection.
849  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
850  * use for this function is in keepalives, which use tcp_respond.
851  */
852 struct tcptemp *
853 tcpip_maketemplate(struct inpcb *inp)
854 {
855 	struct tcptemp *t;
856 
857 	t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
858 	if (t == NULL)
859 		return (NULL);
860 	tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t);
861 	return (t);
862 }
863 
864 /*
865  * Send a single message to the TCP at address specified by
866  * the given TCP/IP header.  If m == NULL, then we make a copy
867  * of the tcpiphdr at th and send directly to the addressed host.
868  * This is used to force keep alive messages out using the TCP
869  * template for a connection.  If flags are given then we send
870  * a message back to the TCP which originated the segment th,
871  * and discard the mbuf containing it and any other attached mbufs.
872  *
873  * In any case the ack and sequence number of the transmitted
874  * segment are as specified by the parameters.
875  *
876  * NOTE: If m != NULL, then th must point to *inside* the mbuf.
877  */
878 void
879 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
880     tcp_seq ack, tcp_seq seq, int flags)
881 {
882 	struct tcpopt to;
883 	struct inpcb *inp;
884 	struct ip *ip;
885 	struct mbuf *optm;
886 	struct tcphdr *nth;
887 	u_char *optp;
888 #ifdef INET6
889 	struct ip6_hdr *ip6;
890 	int isipv6;
891 #endif /* INET6 */
892 	int optlen, tlen, win;
893 	bool incl_opts;
894 
895 	KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
896 
897 #ifdef INET6
898 	isipv6 = ((struct ip *)ipgen)->ip_v == (IPV6_VERSION >> 4);
899 	ip6 = ipgen;
900 #endif /* INET6 */
901 	ip = ipgen;
902 
903 	if (tp != NULL) {
904 		inp = tp->t_inpcb;
905 		KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
906 		INP_WLOCK_ASSERT(inp);
907 	} else
908 		inp = NULL;
909 
910 	incl_opts = false;
911 	win = 0;
912 	if (tp != NULL) {
913 		if (!(flags & TH_RST)) {
914 			win = sbspace(&inp->inp_socket->so_rcv);
915 			if (win > (long)TCP_MAXWIN << tp->rcv_scale)
916 				win = (long)TCP_MAXWIN << tp->rcv_scale;
917 		}
918 		if ((tp->t_flags & TF_NOOPT) == 0)
919 			incl_opts = true;
920 	}
921 	if (m == NULL) {
922 		m = m_gethdr(M_NOWAIT, MT_DATA);
923 		if (m == NULL)
924 			return;
925 		m->m_data += max_linkhdr;
926 #ifdef INET6
927 		if (isipv6) {
928 			bcopy((caddr_t)ip6, mtod(m, caddr_t),
929 			      sizeof(struct ip6_hdr));
930 			ip6 = mtod(m, struct ip6_hdr *);
931 			nth = (struct tcphdr *)(ip6 + 1);
932 		} else
933 #endif /* INET6 */
934 		{
935 			bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
936 			ip = mtod(m, struct ip *);
937 			nth = (struct tcphdr *)(ip + 1);
938 		}
939 		bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
940 		flags = TH_ACK;
941 	} else {
942 		/*
943 		 *  reuse the mbuf.
944 		 * XXX MRT We inherrit the FIB, which is lucky.
945 		 */
946 		m_freem(m->m_next);
947 		m->m_next = NULL;
948 		m->m_data = (caddr_t)ipgen;
949 		/* m_len is set later */
950 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
951 #ifdef INET6
952 		if (isipv6) {
953 			xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
954 			nth = (struct tcphdr *)(ip6 + 1);
955 		} else
956 #endif /* INET6 */
957 		{
958 			xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
959 			nth = (struct tcphdr *)(ip + 1);
960 		}
961 		if (th != nth) {
962 			/*
963 			 * this is usually a case when an extension header
964 			 * exists between the IPv6 header and the
965 			 * TCP header.
966 			 */
967 			nth->th_sport = th->th_sport;
968 			nth->th_dport = th->th_dport;
969 		}
970 		xchg(nth->th_dport, nth->th_sport, uint16_t);
971 #undef xchg
972 	}
973 	tlen = 0;
974 #ifdef INET6
975 	if (isipv6)
976 		tlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
977 #endif
978 #if defined(INET) && defined(INET6)
979 	else
980 #endif
981 #ifdef INET
982 		tlen = sizeof (struct tcpiphdr);
983 #endif
984 #ifdef INVARIANTS
985 	m->m_len = 0;
986 	KASSERT(M_TRAILINGSPACE(m) >= tlen,
987 	    ("Not enough trailing space for message (m=%p, need=%d, have=%ld)",
988 	    m, tlen, (long)M_TRAILINGSPACE(m)));
989 #endif
990 	m->m_len = tlen;
991 	to.to_flags = 0;
992 	if (incl_opts) {
993 		/* Make sure we have room. */
994 		if (M_TRAILINGSPACE(m) < TCP_MAXOLEN) {
995 			m->m_next = m_get(M_NOWAIT, MT_DATA);
996 			if (m->m_next) {
997 				optp = mtod(m->m_next, u_char *);
998 				optm = m->m_next;
999 			} else
1000 				incl_opts = false;
1001 		} else {
1002 			optp = (u_char *) (nth + 1);
1003 			optm = m;
1004 		}
1005 	}
1006 	if (incl_opts) {
1007 		/* Timestamps. */
1008 		if (tp->t_flags & TF_RCVD_TSTMP) {
1009 			to.to_tsval = tcp_ts_getticks() + tp->ts_offset;
1010 			to.to_tsecr = tp->ts_recent;
1011 			to.to_flags |= TOF_TS;
1012 		}
1013 #ifdef TCP_SIGNATURE
1014 		/* TCP-MD5 (RFC2385). */
1015 		if (tp->t_flags & TF_SIGNATURE)
1016 			to.to_flags |= TOF_SIGNATURE;
1017 #endif
1018 
1019 		/* Add the options. */
1020 		tlen += optlen = tcp_addoptions(&to, optp);
1021 
1022 		/* Update m_len in the correct mbuf. */
1023 		optm->m_len += optlen;
1024 	} else
1025 		optlen = 0;
1026 #ifdef INET6
1027 	if (isipv6) {
1028 		ip6->ip6_flow = 0;
1029 		ip6->ip6_vfc = IPV6_VERSION;
1030 		ip6->ip6_nxt = IPPROTO_TCP;
1031 		ip6->ip6_plen = htons(tlen - sizeof(*ip6));
1032 	}
1033 #endif
1034 #if defined(INET) && defined(INET6)
1035 	else
1036 #endif
1037 #ifdef INET
1038 	{
1039 		ip->ip_len = htons(tlen);
1040 		ip->ip_ttl = V_ip_defttl;
1041 		if (V_path_mtu_discovery)
1042 			ip->ip_off |= htons(IP_DF);
1043 	}
1044 #endif
1045 	m->m_pkthdr.len = tlen;
1046 	m->m_pkthdr.rcvif = NULL;
1047 #ifdef MAC
1048 	if (inp != NULL) {
1049 		/*
1050 		 * Packet is associated with a socket, so allow the
1051 		 * label of the response to reflect the socket label.
1052 		 */
1053 		INP_WLOCK_ASSERT(inp);
1054 		mac_inpcb_create_mbuf(inp, m);
1055 	} else {
1056 		/*
1057 		 * Packet is not associated with a socket, so possibly
1058 		 * update the label in place.
1059 		 */
1060 		mac_netinet_tcp_reply(m);
1061 	}
1062 #endif
1063 	nth->th_seq = htonl(seq);
1064 	nth->th_ack = htonl(ack);
1065 	nth->th_x2 = 0;
1066 	nth->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
1067 	nth->th_flags = flags;
1068 	if (tp != NULL)
1069 		nth->th_win = htons((u_short) (win >> tp->rcv_scale));
1070 	else
1071 		nth->th_win = htons((u_short)win);
1072 	nth->th_urp = 0;
1073 
1074 #ifdef TCP_SIGNATURE
1075 	if (to.to_flags & TOF_SIGNATURE) {
1076 		tcp_signature_compute(m, 0, 0, optlen, to.to_signature,
1077 		    IPSEC_DIR_OUTBOUND);
1078 	}
1079 #endif
1080 
1081 	m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1082 #ifdef INET6
1083 	if (isipv6) {
1084 		m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
1085 		nth->th_sum = in6_cksum_pseudo(ip6,
1086 		    tlen - sizeof(struct ip6_hdr), IPPROTO_TCP, 0);
1087 		ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
1088 		    NULL, NULL);
1089 	}
1090 #endif /* INET6 */
1091 #if defined(INET6) && defined(INET)
1092 	else
1093 #endif
1094 #ifdef INET
1095 	{
1096 		m->m_pkthdr.csum_flags = CSUM_TCP;
1097 		nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1098 		    htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
1099 	}
1100 #endif /* INET */
1101 #ifdef TCPDEBUG
1102 	if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
1103 		tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
1104 #endif
1105 	TCP_PROBE3(debug__output, tp, th, mtod(m, const char *));
1106 	if (flags & TH_RST)
1107 		TCP_PROBE5(accept__refused, NULL, NULL, mtod(m, const char *),
1108 		    tp, nth);
1109 
1110 	TCP_PROBE5(send, NULL, tp, mtod(m, const char *), tp, nth);
1111 #ifdef INET6
1112 	if (isipv6)
1113 		(void) ip6_output(m, NULL, NULL, 0, NULL, NULL, inp);
1114 #endif /* INET6 */
1115 #if defined(INET) && defined(INET6)
1116 	else
1117 #endif
1118 #ifdef INET
1119 		(void) ip_output(m, NULL, NULL, 0, NULL, inp);
1120 #endif
1121 }
1122 
1123 /*
1124  * Create a new TCP control block, making an
1125  * empty reassembly queue and hooking it to the argument
1126  * protocol control block.  The `inp' parameter must have
1127  * come from the zone allocator set up in tcp_init().
1128  */
1129 struct tcpcb *
1130 tcp_newtcpcb(struct inpcb *inp)
1131 {
1132 	struct tcpcb_mem *tm;
1133 	struct tcpcb *tp;
1134 #ifdef INET6
1135 	int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
1136 #endif /* INET6 */
1137 
1138 	tm = uma_zalloc(V_tcpcb_zone, M_NOWAIT | M_ZERO);
1139 	if (tm == NULL)
1140 		return (NULL);
1141 	tp = &tm->tcb;
1142 
1143 	/* Initialise cc_var struct for this tcpcb. */
1144 	tp->ccv = &tm->ccv;
1145 	tp->ccv->type = IPPROTO_TCP;
1146 	tp->ccv->ccvc.tcp = tp;
1147 	rw_rlock(&tcp_function_lock);
1148 	tp->t_fb = tcp_func_set_ptr;
1149 	refcount_acquire(&tp->t_fb->tfb_refcnt);
1150 	rw_runlock(&tcp_function_lock);
1151 	if (tp->t_fb->tfb_tcp_fb_init) {
1152 		(*tp->t_fb->tfb_tcp_fb_init)(tp);
1153 	}
1154 	/*
1155 	 * Use the current system default CC algorithm.
1156 	 */
1157 	CC_LIST_RLOCK();
1158 	KASSERT(!STAILQ_EMPTY(&cc_list), ("cc_list is empty!"));
1159 	CC_ALGO(tp) = CC_DEFAULT();
1160 	CC_LIST_RUNLOCK();
1161 
1162 	if (CC_ALGO(tp)->cb_init != NULL)
1163 		if (CC_ALGO(tp)->cb_init(tp->ccv) > 0) {
1164 			if (tp->t_fb->tfb_tcp_fb_fini)
1165 				(*tp->t_fb->tfb_tcp_fb_fini)(tp);
1166 			refcount_release(&tp->t_fb->tfb_refcnt);
1167 			uma_zfree(V_tcpcb_zone, tm);
1168 			return (NULL);
1169 		}
1170 
1171 	tp->osd = &tm->osd;
1172 	if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
1173 		if (tp->t_fb->tfb_tcp_fb_fini)
1174 			(*tp->t_fb->tfb_tcp_fb_fini)(tp);
1175 		refcount_release(&tp->t_fb->tfb_refcnt);
1176 		uma_zfree(V_tcpcb_zone, tm);
1177 		return (NULL);
1178 	}
1179 
1180 #ifdef VIMAGE
1181 	tp->t_vnet = inp->inp_vnet;
1182 #endif
1183 	tp->t_timers = &tm->tt;
1184 	/*	LIST_INIT(&tp->t_segq); */	/* XXX covered by M_ZERO */
1185 	tp->t_maxseg =
1186 #ifdef INET6
1187 		isipv6 ? V_tcp_v6mssdflt :
1188 #endif /* INET6 */
1189 		V_tcp_mssdflt;
1190 
1191 	/* Set up our timeouts. */
1192 	callout_init(&tp->t_timers->tt_rexmt, 1);
1193 	callout_init(&tp->t_timers->tt_persist, 1);
1194 	callout_init(&tp->t_timers->tt_keep, 1);
1195 	callout_init(&tp->t_timers->tt_2msl, 1);
1196 	callout_init(&tp->t_timers->tt_delack, 1);
1197 
1198 	if (V_tcp_do_rfc1323)
1199 		tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
1200 	if (V_tcp_do_sack)
1201 		tp->t_flags |= TF_SACK_PERMIT;
1202 	TAILQ_INIT(&tp->snd_holes);
1203 	/*
1204 	 * The tcpcb will hold a reference on its inpcb until tcp_discardcb()
1205 	 * is called.
1206 	 */
1207 	in_pcbref(inp);	/* Reference for tcpcb */
1208 	tp->t_inpcb = inp;
1209 
1210 	/*
1211 	 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
1212 	 * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
1213 	 * reasonable initial retransmit time.
1214 	 */
1215 	tp->t_srtt = TCPTV_SRTTBASE;
1216 	tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
1217 	tp->t_rttmin = tcp_rexmit_min;
1218 	tp->t_rxtcur = TCPTV_RTOBASE;
1219 	tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1220 	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1221 	tp->t_rcvtime = ticks;
1222 	/*
1223 	 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
1224 	 * because the socket may be bound to an IPv6 wildcard address,
1225 	 * which may match an IPv4-mapped IPv6 address.
1226 	 */
1227 	inp->inp_ip_ttl = V_ip_defttl;
1228 	inp->inp_ppcb = tp;
1229 #ifdef TCPPCAP
1230 	/*
1231 	 * Init the TCP PCAP queues.
1232 	 */
1233 	tcp_pcap_tcpcb_init(tp);
1234 #endif
1235 	return (tp);		/* XXX */
1236 }
1237 
1238 /*
1239  * Switch the congestion control algorithm back to NewReno for any active
1240  * control blocks using an algorithm which is about to go away.
1241  * This ensures the CC framework can allow the unload to proceed without leaving
1242  * any dangling pointers which would trigger a panic.
1243  * Returning non-zero would inform the CC framework that something went wrong
1244  * and it would be unsafe to allow the unload to proceed. However, there is no
1245  * way for this to occur with this implementation so we always return zero.
1246  */
1247 int
1248 tcp_ccalgounload(struct cc_algo *unload_algo)
1249 {
1250 	struct cc_algo *tmpalgo;
1251 	struct inpcb *inp;
1252 	struct tcpcb *tp;
1253 	VNET_ITERATOR_DECL(vnet_iter);
1254 
1255 	/*
1256 	 * Check all active control blocks across all network stacks and change
1257 	 * any that are using "unload_algo" back to NewReno. If "unload_algo"
1258 	 * requires cleanup code to be run, call it.
1259 	 */
1260 	VNET_LIST_RLOCK();
1261 	VNET_FOREACH(vnet_iter) {
1262 		CURVNET_SET(vnet_iter);
1263 		INP_INFO_WLOCK(&V_tcbinfo);
1264 		/*
1265 		 * New connections already part way through being initialised
1266 		 * with the CC algo we're removing will not race with this code
1267 		 * because the INP_INFO_WLOCK is held during initialisation. We
1268 		 * therefore don't enter the loop below until the connection
1269 		 * list has stabilised.
1270 		 */
1271 		LIST_FOREACH(inp, &V_tcb, inp_list) {
1272 			INP_WLOCK(inp);
1273 			/* Important to skip tcptw structs. */
1274 			if (!(inp->inp_flags & INP_TIMEWAIT) &&
1275 			    (tp = intotcpcb(inp)) != NULL) {
1276 				/*
1277 				 * By holding INP_WLOCK here, we are assured
1278 				 * that the connection is not currently
1279 				 * executing inside the CC module's functions
1280 				 * i.e. it is safe to make the switch back to
1281 				 * NewReno.
1282 				 */
1283 				if (CC_ALGO(tp) == unload_algo) {
1284 					tmpalgo = CC_ALGO(tp);
1285 					/* NewReno does not require any init. */
1286 					CC_ALGO(tp) = &newreno_cc_algo;
1287 					if (tmpalgo->cb_destroy != NULL)
1288 						tmpalgo->cb_destroy(tp->ccv);
1289 				}
1290 			}
1291 			INP_WUNLOCK(inp);
1292 		}
1293 		INP_INFO_WUNLOCK(&V_tcbinfo);
1294 		CURVNET_RESTORE();
1295 	}
1296 	VNET_LIST_RUNLOCK();
1297 
1298 	return (0);
1299 }
1300 
1301 /*
1302  * Drop a TCP connection, reporting
1303  * the specified error.  If connection is synchronized,
1304  * then send a RST to peer.
1305  */
1306 struct tcpcb *
1307 tcp_drop(struct tcpcb *tp, int errno)
1308 {
1309 	struct socket *so = tp->t_inpcb->inp_socket;
1310 
1311 	INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1312 	INP_WLOCK_ASSERT(tp->t_inpcb);
1313 
1314 	if (TCPS_HAVERCVDSYN(tp->t_state)) {
1315 		tcp_state_change(tp, TCPS_CLOSED);
1316 		(void) tp->t_fb->tfb_tcp_output(tp);
1317 		TCPSTAT_INC(tcps_drops);
1318 	} else
1319 		TCPSTAT_INC(tcps_conndrops);
1320 	if (errno == ETIMEDOUT && tp->t_softerror)
1321 		errno = tp->t_softerror;
1322 	so->so_error = errno;
1323 	return (tcp_close(tp));
1324 }
1325 
1326 void
1327 tcp_discardcb(struct tcpcb *tp)
1328 {
1329 	struct inpcb *inp = tp->t_inpcb;
1330 	struct socket *so = inp->inp_socket;
1331 #ifdef INET6
1332 	int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
1333 #endif /* INET6 */
1334 	int released;
1335 
1336 	INP_WLOCK_ASSERT(inp);
1337 
1338 	/*
1339 	 * Make sure that all of our timers are stopped before we delete the
1340 	 * PCB.
1341 	 *
1342 	 * If stopping a timer fails, we schedule a discard function in same
1343 	 * callout, and the last discard function called will take care of
1344 	 * deleting the tcpcb.
1345 	 */
1346 	tcp_timer_stop(tp, TT_REXMT);
1347 	tcp_timer_stop(tp, TT_PERSIST);
1348 	tcp_timer_stop(tp, TT_KEEP);
1349 	tcp_timer_stop(tp, TT_2MSL);
1350 	tcp_timer_stop(tp, TT_DELACK);
1351 	if (tp->t_fb->tfb_tcp_timer_stop_all) {
1352 		/* Call the stop-all function of the methods */
1353 		tp->t_fb->tfb_tcp_timer_stop_all(tp);
1354 	}
1355 
1356 	/*
1357 	 * If we got enough samples through the srtt filter,
1358 	 * save the rtt and rttvar in the routing entry.
1359 	 * 'Enough' is arbitrarily defined as 4 rtt samples.
1360 	 * 4 samples is enough for the srtt filter to converge
1361 	 * to within enough % of the correct value; fewer samples
1362 	 * and we could save a bogus rtt. The danger is not high
1363 	 * as tcp quickly recovers from everything.
1364 	 * XXX: Works very well but needs some more statistics!
1365 	 */
1366 	if (tp->t_rttupdated >= 4) {
1367 		struct hc_metrics_lite metrics;
1368 		u_long ssthresh;
1369 
1370 		bzero(&metrics, sizeof(metrics));
1371 		/*
1372 		 * Update the ssthresh always when the conditions below
1373 		 * are satisfied. This gives us better new start value
1374 		 * for the congestion avoidance for new connections.
1375 		 * ssthresh is only set if packet loss occured on a session.
1376 		 *
1377 		 * XXXRW: 'so' may be NULL here, and/or socket buffer may be
1378 		 * being torn down.  Ideally this code would not use 'so'.
1379 		 */
1380 		ssthresh = tp->snd_ssthresh;
1381 		if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
1382 			/*
1383 			 * convert the limit from user data bytes to
1384 			 * packets then to packet data bytes.
1385 			 */
1386 			ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
1387 			if (ssthresh < 2)
1388 				ssthresh = 2;
1389 			ssthresh *= (u_long)(tp->t_maxseg +
1390 #ifdef INET6
1391 			    (isipv6 ? sizeof (struct ip6_hdr) +
1392 				sizeof (struct tcphdr) :
1393 #endif
1394 				sizeof (struct tcpiphdr)
1395 #ifdef INET6
1396 			    )
1397 #endif
1398 			    );
1399 		} else
1400 			ssthresh = 0;
1401 		metrics.rmx_ssthresh = ssthresh;
1402 
1403 		metrics.rmx_rtt = tp->t_srtt;
1404 		metrics.rmx_rttvar = tp->t_rttvar;
1405 		metrics.rmx_cwnd = tp->snd_cwnd;
1406 		metrics.rmx_sendpipe = 0;
1407 		metrics.rmx_recvpipe = 0;
1408 
1409 		tcp_hc_update(&inp->inp_inc, &metrics);
1410 	}
1411 
1412 	/* free the reassembly queue, if any */
1413 	tcp_reass_flush(tp);
1414 
1415 #ifdef TCP_OFFLOAD
1416 	/* Disconnect offload device, if any. */
1417 	if (tp->t_flags & TF_TOE)
1418 		tcp_offload_detach(tp);
1419 #endif
1420 
1421 	tcp_free_sackholes(tp);
1422 
1423 #ifdef TCPPCAP
1424 	/* Free the TCP PCAP queues. */
1425 	tcp_pcap_drain(&(tp->t_inpkts));
1426 	tcp_pcap_drain(&(tp->t_outpkts));
1427 #endif
1428 
1429 	/* Allow the CC algorithm to clean up after itself. */
1430 	if (CC_ALGO(tp)->cb_destroy != NULL)
1431 		CC_ALGO(tp)->cb_destroy(tp->ccv);
1432 
1433 	khelp_destroy_osd(tp->osd);
1434 
1435 	CC_ALGO(tp) = NULL;
1436 	inp->inp_ppcb = NULL;
1437 	if ((tp->t_timers->tt_flags & TT_MASK) == 0) {
1438 		/* We own the last reference on tcpcb, let's free it. */
1439 		if ((tp->t_fb->tfb_tcp_timers_left) &&
1440 		    (tp->t_fb->tfb_tcp_timers_left(tp))) {
1441 			    /* Some fb timers left running! */
1442 			    return;
1443 		}
1444 		if (tp->t_fb->tfb_tcp_fb_fini)
1445 			(*tp->t_fb->tfb_tcp_fb_fini)(tp);
1446 		refcount_release(&tp->t_fb->tfb_refcnt);
1447 		tp->t_inpcb = NULL;
1448 		uma_zfree(V_tcpcb_zone, tp);
1449 		released = in_pcbrele_wlocked(inp);
1450 		KASSERT(!released, ("%s: inp %p should not have been released "
1451 			"here", __func__, inp));
1452 	}
1453 }
1454 
1455 void
1456 tcp_timer_2msl_discard(void *xtp)
1457 {
1458 
1459 	tcp_timer_discard((struct tcpcb *)xtp, TT_2MSL);
1460 }
1461 
1462 void
1463 tcp_timer_keep_discard(void *xtp)
1464 {
1465 
1466 	tcp_timer_discard((struct tcpcb *)xtp, TT_KEEP);
1467 }
1468 
1469 void
1470 tcp_timer_persist_discard(void *xtp)
1471 {
1472 
1473 	tcp_timer_discard((struct tcpcb *)xtp, TT_PERSIST);
1474 }
1475 
1476 void
1477 tcp_timer_rexmt_discard(void *xtp)
1478 {
1479 
1480 	tcp_timer_discard((struct tcpcb *)xtp, TT_REXMT);
1481 }
1482 
1483 void
1484 tcp_timer_delack_discard(void *xtp)
1485 {
1486 
1487 	tcp_timer_discard((struct tcpcb *)xtp, TT_DELACK);
1488 }
1489 
1490 void
1491 tcp_timer_discard(struct tcpcb *tp, uint32_t timer_type)
1492 {
1493 	struct inpcb *inp;
1494 
1495 	CURVNET_SET(tp->t_vnet);
1496 	INP_INFO_RLOCK(&V_tcbinfo);
1497 	inp = tp->t_inpcb;
1498 	KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL",
1499 		__func__, tp));
1500 	INP_WLOCK(inp);
1501 	KASSERT((tp->t_timers->tt_flags & TT_STOPPED) != 0,
1502 		("%s: tcpcb has to be stopped here", __func__));
1503 	KASSERT((tp->t_timers->tt_flags & timer_type) != 0,
1504 		("%s: discard callout should be running", __func__));
1505 	tp->t_timers->tt_flags &= ~timer_type;
1506 	if ((tp->t_timers->tt_flags & TT_MASK) == 0) {
1507 		/* We own the last reference on this tcpcb, let's free it. */
1508 		if ((tp->t_fb->tfb_tcp_timers_left) &&
1509 		    (tp->t_fb->tfb_tcp_timers_left(tp))) {
1510 			    /* Some fb timers left running! */
1511 			    goto leave;
1512 		}
1513 		if (tp->t_fb->tfb_tcp_fb_fini)
1514 			(*tp->t_fb->tfb_tcp_fb_fini)(tp);
1515 		refcount_release(&tp->t_fb->tfb_refcnt);
1516 		tp->t_inpcb = NULL;
1517 		uma_zfree(V_tcpcb_zone, tp);
1518 		if (in_pcbrele_wlocked(inp)) {
1519 			INP_INFO_RUNLOCK(&V_tcbinfo);
1520 			CURVNET_RESTORE();
1521 			return;
1522 		}
1523 	}
1524 leave:
1525 	INP_WUNLOCK(inp);
1526 	INP_INFO_RUNLOCK(&V_tcbinfo);
1527 	CURVNET_RESTORE();
1528 }
1529 
1530 /*
1531  * Attempt to close a TCP control block, marking it as dropped, and freeing
1532  * the socket if we hold the only reference.
1533  */
1534 struct tcpcb *
1535 tcp_close(struct tcpcb *tp)
1536 {
1537 	struct inpcb *inp = tp->t_inpcb;
1538 	struct socket *so;
1539 
1540 	INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1541 	INP_WLOCK_ASSERT(inp);
1542 
1543 #ifdef TCP_OFFLOAD
1544 	if (tp->t_state == TCPS_LISTEN)
1545 		tcp_offload_listen_stop(tp);
1546 #endif
1547 #ifdef TCP_RFC7413
1548 	/*
1549 	 * This releases the TFO pending counter resource for TFO listen
1550 	 * sockets as well as passively-created TFO sockets that transition
1551 	 * from SYN_RECEIVED to CLOSED.
1552 	 */
1553 	if (tp->t_tfo_pending) {
1554 		tcp_fastopen_decrement_counter(tp->t_tfo_pending);
1555 		tp->t_tfo_pending = NULL;
1556 	}
1557 #endif
1558 	in_pcbdrop(inp);
1559 	TCPSTAT_INC(tcps_closed);
1560 	TCPSTATES_DEC(tp->t_state);
1561 	KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
1562 	so = inp->inp_socket;
1563 	soisdisconnected(so);
1564 	if (inp->inp_flags & INP_SOCKREF) {
1565 		KASSERT(so->so_state & SS_PROTOREF,
1566 		    ("tcp_close: !SS_PROTOREF"));
1567 		inp->inp_flags &= ~INP_SOCKREF;
1568 		INP_WUNLOCK(inp);
1569 		ACCEPT_LOCK();
1570 		SOCK_LOCK(so);
1571 		so->so_state &= ~SS_PROTOREF;
1572 		sofree(so);
1573 		return (NULL);
1574 	}
1575 	return (tp);
1576 }
1577 
1578 void
1579 tcp_drain(void)
1580 {
1581 	VNET_ITERATOR_DECL(vnet_iter);
1582 
1583 	if (!do_tcpdrain)
1584 		return;
1585 
1586 	VNET_LIST_RLOCK_NOSLEEP();
1587 	VNET_FOREACH(vnet_iter) {
1588 		CURVNET_SET(vnet_iter);
1589 		struct inpcb *inpb;
1590 		struct tcpcb *tcpb;
1591 
1592 	/*
1593 	 * Walk the tcpbs, if existing, and flush the reassembly queue,
1594 	 * if there is one...
1595 	 * XXX: The "Net/3" implementation doesn't imply that the TCP
1596 	 *      reassembly queue should be flushed, but in a situation
1597 	 *	where we're really low on mbufs, this is potentially
1598 	 *	useful.
1599 	 */
1600 		INP_INFO_WLOCK(&V_tcbinfo);
1601 		LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) {
1602 			if (inpb->inp_flags & INP_TIMEWAIT)
1603 				continue;
1604 			INP_WLOCK(inpb);
1605 			if ((tcpb = intotcpcb(inpb)) != NULL) {
1606 				tcp_reass_flush(tcpb);
1607 				tcp_clean_sackreport(tcpb);
1608 			}
1609 			INP_WUNLOCK(inpb);
1610 		}
1611 		INP_INFO_WUNLOCK(&V_tcbinfo);
1612 		CURVNET_RESTORE();
1613 	}
1614 	VNET_LIST_RUNLOCK_NOSLEEP();
1615 }
1616 
1617 /*
1618  * Notify a tcp user of an asynchronous error;
1619  * store error as soft error, but wake up user
1620  * (for now, won't do anything until can select for soft error).
1621  *
1622  * Do not wake up user since there currently is no mechanism for
1623  * reporting soft errors (yet - a kqueue filter may be added).
1624  */
1625 static struct inpcb *
1626 tcp_notify(struct inpcb *inp, int error)
1627 {
1628 	struct tcpcb *tp;
1629 
1630 	INP_INFO_LOCK_ASSERT(&V_tcbinfo);
1631 	INP_WLOCK_ASSERT(inp);
1632 
1633 	if ((inp->inp_flags & INP_TIMEWAIT) ||
1634 	    (inp->inp_flags & INP_DROPPED))
1635 		return (inp);
1636 
1637 	tp = intotcpcb(inp);
1638 	KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
1639 
1640 	/*
1641 	 * Ignore some errors if we are hooked up.
1642 	 * If connection hasn't completed, has retransmitted several times,
1643 	 * and receives a second error, give up now.  This is better
1644 	 * than waiting a long time to establish a connection that
1645 	 * can never complete.
1646 	 */
1647 	if (tp->t_state == TCPS_ESTABLISHED &&
1648 	    (error == EHOSTUNREACH || error == ENETUNREACH ||
1649 	     error == EHOSTDOWN)) {
1650 		if (inp->inp_route.ro_rt) {
1651 			RTFREE(inp->inp_route.ro_rt);
1652 			inp->inp_route.ro_rt = (struct rtentry *)NULL;
1653 		}
1654 		return (inp);
1655 	} else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
1656 	    tp->t_softerror) {
1657 		tp = tcp_drop(tp, error);
1658 		if (tp != NULL)
1659 			return (inp);
1660 		else
1661 			return (NULL);
1662 	} else {
1663 		tp->t_softerror = error;
1664 		return (inp);
1665 	}
1666 #if 0
1667 	wakeup( &so->so_timeo);
1668 	sorwakeup(so);
1669 	sowwakeup(so);
1670 #endif
1671 }
1672 
1673 static int
1674 tcp_pcblist(SYSCTL_HANDLER_ARGS)
1675 {
1676 	int error, i, m, n, pcb_count;
1677 	struct inpcb *inp, **inp_list;
1678 	inp_gen_t gencnt;
1679 	struct xinpgen xig;
1680 
1681 	/*
1682 	 * The process of preparing the TCB list is too time-consuming and
1683 	 * resource-intensive to repeat twice on every request.
1684 	 */
1685 	if (req->oldptr == NULL) {
1686 		n = V_tcbinfo.ipi_count +
1687 		    counter_u64_fetch(VNET(tcps_states)[TCPS_SYN_RECEIVED]);
1688 		n += imax(n / 8, 10);
1689 		req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
1690 		return (0);
1691 	}
1692 
1693 	if (req->newptr != NULL)
1694 		return (EPERM);
1695 
1696 	/*
1697 	 * OK, now we're committed to doing something.
1698 	 */
1699 	INP_LIST_RLOCK(&V_tcbinfo);
1700 	gencnt = V_tcbinfo.ipi_gencnt;
1701 	n = V_tcbinfo.ipi_count;
1702 	INP_LIST_RUNLOCK(&V_tcbinfo);
1703 
1704 	m = counter_u64_fetch(VNET(tcps_states)[TCPS_SYN_RECEIVED]);
1705 
1706 	error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
1707 		+ (n + m) * sizeof(struct xtcpcb));
1708 	if (error != 0)
1709 		return (error);
1710 
1711 	xig.xig_len = sizeof xig;
1712 	xig.xig_count = n + m;
1713 	xig.xig_gen = gencnt;
1714 	xig.xig_sogen = so_gencnt;
1715 	error = SYSCTL_OUT(req, &xig, sizeof xig);
1716 	if (error)
1717 		return (error);
1718 
1719 	error = syncache_pcblist(req, m, &pcb_count);
1720 	if (error)
1721 		return (error);
1722 
1723 	inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
1724 
1725 	INP_INFO_WLOCK(&V_tcbinfo);
1726 	for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0;
1727 	    inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) {
1728 		INP_WLOCK(inp);
1729 		if (inp->inp_gencnt <= gencnt) {
1730 			/*
1731 			 * XXX: This use of cr_cansee(), introduced with
1732 			 * TCP state changes, is not quite right, but for
1733 			 * now, better than nothing.
1734 			 */
1735 			if (inp->inp_flags & INP_TIMEWAIT) {
1736 				if (intotw(inp) != NULL)
1737 					error = cr_cansee(req->td->td_ucred,
1738 					    intotw(inp)->tw_cred);
1739 				else
1740 					error = EINVAL;	/* Skip this inp. */
1741 			} else
1742 				error = cr_canseeinpcb(req->td->td_ucred, inp);
1743 			if (error == 0) {
1744 				in_pcbref(inp);
1745 				inp_list[i++] = inp;
1746 			}
1747 		}
1748 		INP_WUNLOCK(inp);
1749 	}
1750 	INP_INFO_WUNLOCK(&V_tcbinfo);
1751 	n = i;
1752 
1753 	error = 0;
1754 	for (i = 0; i < n; i++) {
1755 		inp = inp_list[i];
1756 		INP_RLOCK(inp);
1757 		if (inp->inp_gencnt <= gencnt) {
1758 			struct xtcpcb xt;
1759 			void *inp_ppcb;
1760 
1761 			bzero(&xt, sizeof(xt));
1762 			xt.xt_len = sizeof xt;
1763 			/* XXX should avoid extra copy */
1764 			bcopy(inp, &xt.xt_inp, sizeof *inp);
1765 			inp_ppcb = inp->inp_ppcb;
1766 			if (inp_ppcb == NULL)
1767 				bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
1768 			else if (inp->inp_flags & INP_TIMEWAIT) {
1769 				bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
1770 				xt.xt_tp.t_state = TCPS_TIME_WAIT;
1771 			} else {
1772 				bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
1773 				if (xt.xt_tp.t_timers)
1774 					tcp_timer_to_xtimer(&xt.xt_tp, xt.xt_tp.t_timers, &xt.xt_timer);
1775 			}
1776 			if (inp->inp_socket != NULL)
1777 				sotoxsocket(inp->inp_socket, &xt.xt_socket);
1778 			else {
1779 				bzero(&xt.xt_socket, sizeof xt.xt_socket);
1780 				xt.xt_socket.xso_protocol = IPPROTO_TCP;
1781 			}
1782 			xt.xt_inp.inp_gencnt = inp->inp_gencnt;
1783 			INP_RUNLOCK(inp);
1784 			error = SYSCTL_OUT(req, &xt, sizeof xt);
1785 		} else
1786 			INP_RUNLOCK(inp);
1787 	}
1788 	INP_INFO_RLOCK(&V_tcbinfo);
1789 	for (i = 0; i < n; i++) {
1790 		inp = inp_list[i];
1791 		INP_RLOCK(inp);
1792 		if (!in_pcbrele_rlocked(inp))
1793 			INP_RUNLOCK(inp);
1794 	}
1795 	INP_INFO_RUNLOCK(&V_tcbinfo);
1796 
1797 	if (!error) {
1798 		/*
1799 		 * Give the user an updated idea of our state.
1800 		 * If the generation differs from what we told
1801 		 * her before, she knows that something happened
1802 		 * while we were processing this request, and it
1803 		 * might be necessary to retry.
1804 		 */
1805 		INP_LIST_RLOCK(&V_tcbinfo);
1806 		xig.xig_gen = V_tcbinfo.ipi_gencnt;
1807 		xig.xig_sogen = so_gencnt;
1808 		xig.xig_count = V_tcbinfo.ipi_count + pcb_count;
1809 		INP_LIST_RUNLOCK(&V_tcbinfo);
1810 		error = SYSCTL_OUT(req, &xig, sizeof xig);
1811 	}
1812 	free(inp_list, M_TEMP);
1813 	return (error);
1814 }
1815 
1816 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
1817     CTLTYPE_OPAQUE | CTLFLAG_RD, NULL, 0,
1818     tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1819 
1820 #ifdef INET
1821 static int
1822 tcp_getcred(SYSCTL_HANDLER_ARGS)
1823 {
1824 	struct xucred xuc;
1825 	struct sockaddr_in addrs[2];
1826 	struct inpcb *inp;
1827 	int error;
1828 
1829 	error = priv_check(req->td, PRIV_NETINET_GETCRED);
1830 	if (error)
1831 		return (error);
1832 	error = SYSCTL_IN(req, addrs, sizeof(addrs));
1833 	if (error)
1834 		return (error);
1835 	inp = in_pcblookup(&V_tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
1836 	    addrs[0].sin_addr, addrs[0].sin_port, INPLOOKUP_RLOCKPCB, NULL);
1837 	if (inp != NULL) {
1838 		if (inp->inp_socket == NULL)
1839 			error = ENOENT;
1840 		if (error == 0)
1841 			error = cr_canseeinpcb(req->td->td_ucred, inp);
1842 		if (error == 0)
1843 			cru2x(inp->inp_cred, &xuc);
1844 		INP_RUNLOCK(inp);
1845 	} else
1846 		error = ENOENT;
1847 	if (error == 0)
1848 		error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1849 	return (error);
1850 }
1851 
1852 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
1853     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1854     tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
1855 #endif /* INET */
1856 
1857 #ifdef INET6
1858 static int
1859 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1860 {
1861 	struct xucred xuc;
1862 	struct sockaddr_in6 addrs[2];
1863 	struct inpcb *inp;
1864 	int error;
1865 #ifdef INET
1866 	int mapped = 0;
1867 #endif
1868 
1869 	error = priv_check(req->td, PRIV_NETINET_GETCRED);
1870 	if (error)
1871 		return (error);
1872 	error = SYSCTL_IN(req, addrs, sizeof(addrs));
1873 	if (error)
1874 		return (error);
1875 	if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
1876 	    (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
1877 		return (error);
1878 	}
1879 	if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1880 #ifdef INET
1881 		if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1882 			mapped = 1;
1883 		else
1884 #endif
1885 			return (EINVAL);
1886 	}
1887 
1888 #ifdef INET
1889 	if (mapped == 1)
1890 		inp = in_pcblookup(&V_tcbinfo,
1891 			*(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1892 			addrs[1].sin6_port,
1893 			*(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1894 			addrs[0].sin6_port, INPLOOKUP_RLOCKPCB, NULL);
1895 	else
1896 #endif
1897 		inp = in6_pcblookup(&V_tcbinfo,
1898 			&addrs[1].sin6_addr, addrs[1].sin6_port,
1899 			&addrs[0].sin6_addr, addrs[0].sin6_port,
1900 			INPLOOKUP_RLOCKPCB, NULL);
1901 	if (inp != NULL) {
1902 		if (inp->inp_socket == NULL)
1903 			error = ENOENT;
1904 		if (error == 0)
1905 			error = cr_canseeinpcb(req->td->td_ucred, inp);
1906 		if (error == 0)
1907 			cru2x(inp->inp_cred, &xuc);
1908 		INP_RUNLOCK(inp);
1909 	} else
1910 		error = ENOENT;
1911 	if (error == 0)
1912 		error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1913 	return (error);
1914 }
1915 
1916 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
1917     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1918     tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
1919 #endif /* INET6 */
1920 
1921 
1922 #ifdef INET
1923 void
1924 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
1925 {
1926 	struct ip *ip = vip;
1927 	struct tcphdr *th;
1928 	struct in_addr faddr;
1929 	struct inpcb *inp;
1930 	struct tcpcb *tp;
1931 	struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1932 	struct icmp *icp;
1933 	struct in_conninfo inc;
1934 	tcp_seq icmp_tcp_seq;
1935 	int mtu;
1936 
1937 	faddr = ((struct sockaddr_in *)sa)->sin_addr;
1938 	if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1939 		return;
1940 
1941 	if (cmd == PRC_MSGSIZE)
1942 		notify = tcp_mtudisc_notify;
1943 	else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1944 		cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
1945 		notify = tcp_drop_syn_sent;
1946 	else if (PRC_IS_REDIRECT(cmd)) {
1947 		/* signal EHOSTDOWN, as it flushes the cached route */
1948 		in_pcbnotifyall(&V_tcbinfo, faddr, EHOSTDOWN, notify);
1949 		return;
1950 	}
1951 	/*
1952 	 * Hostdead is ugly because it goes linearly through all PCBs.
1953 	 * XXX: We never get this from ICMP, otherwise it makes an
1954 	 * excellent DoS attack on machines with many connections.
1955 	 */
1956 	else if (cmd == PRC_HOSTDEAD)
1957 		ip = NULL;
1958 	else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
1959 		return;
1960 
1961 	if (ip == NULL) {
1962 		in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify);
1963 		return;
1964 	}
1965 
1966 	icp = (struct icmp *)((caddr_t)ip - offsetof(struct icmp, icmp_ip));
1967 	th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2));
1968 	INP_INFO_RLOCK(&V_tcbinfo);
1969 	inp = in_pcblookup(&V_tcbinfo, faddr, th->th_dport, ip->ip_src,
1970 	    th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
1971 	if (inp != NULL)  {
1972 		if (!(inp->inp_flags & INP_TIMEWAIT) &&
1973 		    !(inp->inp_flags & INP_DROPPED) &&
1974 		    !(inp->inp_socket == NULL)) {
1975 			icmp_tcp_seq = ntohl(th->th_seq);
1976 			tp = intotcpcb(inp);
1977 			if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
1978 			    SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
1979 				if (cmd == PRC_MSGSIZE) {
1980 					/*
1981 					 * MTU discovery:
1982 					 * If we got a needfrag set the MTU
1983 					 * in the route to the suggested new
1984 					 * value (if given) and then notify.
1985 					 */
1986 				    	mtu = ntohs(icp->icmp_nextmtu);
1987 					/*
1988 					 * If no alternative MTU was
1989 					 * proposed, try the next smaller
1990 					 * one.
1991 					 */
1992 					if (!mtu)
1993 						mtu = ip_next_mtu(
1994 						    ntohs(ip->ip_len), 1);
1995 					if (mtu < V_tcp_minmss +
1996 					    sizeof(struct tcpiphdr))
1997 						mtu = V_tcp_minmss +
1998 						    sizeof(struct tcpiphdr);
1999 					/*
2000 					 * Only process the offered MTU if it
2001 					 * is smaller than the current one.
2002 					 */
2003 					if (mtu < tp->t_maxseg +
2004 					    sizeof(struct tcpiphdr)) {
2005 						bzero(&inc, sizeof(inc));
2006 						inc.inc_faddr = faddr;
2007 						inc.inc_fibnum =
2008 						    inp->inp_inc.inc_fibnum;
2009 						tcp_hc_updatemtu(&inc, mtu);
2010 						tcp_mtudisc(inp, mtu);
2011 					}
2012 				} else
2013 					inp = (*notify)(inp,
2014 					    inetctlerrmap[cmd]);
2015 			}
2016 		}
2017 		if (inp != NULL)
2018 			INP_WUNLOCK(inp);
2019 	} else {
2020 		bzero(&inc, sizeof(inc));
2021 		inc.inc_fport = th->th_dport;
2022 		inc.inc_lport = th->th_sport;
2023 		inc.inc_faddr = faddr;
2024 		inc.inc_laddr = ip->ip_src;
2025 		syncache_unreach(&inc, th);
2026 	}
2027 	INP_INFO_RUNLOCK(&V_tcbinfo);
2028 }
2029 #endif /* INET */
2030 
2031 #ifdef INET6
2032 void
2033 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
2034 {
2035 	struct tcphdr th;
2036 	struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
2037 	struct ip6_hdr *ip6;
2038 	struct mbuf *m;
2039 	struct ip6ctlparam *ip6cp = NULL;
2040 	const struct sockaddr_in6 *sa6_src = NULL;
2041 	int off;
2042 	struct tcp_portonly {
2043 		u_int16_t th_sport;
2044 		u_int16_t th_dport;
2045 	} *thp;
2046 
2047 	if (sa->sa_family != AF_INET6 ||
2048 	    sa->sa_len != sizeof(struct sockaddr_in6))
2049 		return;
2050 
2051 	if (cmd == PRC_MSGSIZE)
2052 		notify = tcp_mtudisc_notify;
2053 	else if (!PRC_IS_REDIRECT(cmd) &&
2054 		 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
2055 		return;
2056 
2057 	/* if the parameter is from icmp6, decode it. */
2058 	if (d != NULL) {
2059 		ip6cp = (struct ip6ctlparam *)d;
2060 		m = ip6cp->ip6c_m;
2061 		ip6 = ip6cp->ip6c_ip6;
2062 		off = ip6cp->ip6c_off;
2063 		sa6_src = ip6cp->ip6c_src;
2064 	} else {
2065 		m = NULL;
2066 		ip6 = NULL;
2067 		off = 0;	/* fool gcc */
2068 		sa6_src = &sa6_any;
2069 	}
2070 
2071 	if (ip6 != NULL) {
2072 		struct in_conninfo inc;
2073 		/*
2074 		 * XXX: We assume that when IPV6 is non NULL,
2075 		 * M and OFF are valid.
2076 		 */
2077 
2078 		/* check if we can safely examine src and dst ports */
2079 		if (m->m_pkthdr.len < off + sizeof(*thp))
2080 			return;
2081 
2082 		bzero(&th, sizeof(th));
2083 		m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
2084 
2085 		in6_pcbnotify(&V_tcbinfo, sa, th.th_dport,
2086 		    (struct sockaddr *)ip6cp->ip6c_src,
2087 		    th.th_sport, cmd, NULL, notify);
2088 
2089 		bzero(&inc, sizeof(inc));
2090 		inc.inc_fport = th.th_dport;
2091 		inc.inc_lport = th.th_sport;
2092 		inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
2093 		inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
2094 		inc.inc_flags |= INC_ISIPV6;
2095 		INP_INFO_RLOCK(&V_tcbinfo);
2096 		syncache_unreach(&inc, &th);
2097 		INP_INFO_RUNLOCK(&V_tcbinfo);
2098 	} else
2099 		in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src,
2100 			      0, cmd, NULL, notify);
2101 }
2102 #endif /* INET6 */
2103 
2104 
2105 /*
2106  * Following is where TCP initial sequence number generation occurs.
2107  *
2108  * There are two places where we must use initial sequence numbers:
2109  * 1.  In SYN-ACK packets.
2110  * 2.  In SYN packets.
2111  *
2112  * All ISNs for SYN-ACK packets are generated by the syncache.  See
2113  * tcp_syncache.c for details.
2114  *
2115  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
2116  * depends on this property.  In addition, these ISNs should be
2117  * unguessable so as to prevent connection hijacking.  To satisfy
2118  * the requirements of this situation, the algorithm outlined in
2119  * RFC 1948 is used, with only small modifications.
2120  *
2121  * Implementation details:
2122  *
2123  * Time is based off the system timer, and is corrected so that it
2124  * increases by one megabyte per second.  This allows for proper
2125  * recycling on high speed LANs while still leaving over an hour
2126  * before rollover.
2127  *
2128  * As reading the *exact* system time is too expensive to be done
2129  * whenever setting up a TCP connection, we increment the time
2130  * offset in two ways.  First, a small random positive increment
2131  * is added to isn_offset for each connection that is set up.
2132  * Second, the function tcp_isn_tick fires once per clock tick
2133  * and increments isn_offset as necessary so that sequence numbers
2134  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
2135  * random positive increments serve only to ensure that the same
2136  * exact sequence number is never sent out twice (as could otherwise
2137  * happen when a port is recycled in less than the system tick
2138  * interval.)
2139  *
2140  * net.inet.tcp.isn_reseed_interval controls the number of seconds
2141  * between seeding of isn_secret.  This is normally set to zero,
2142  * as reseeding should not be necessary.
2143  *
2144  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
2145  * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock.  In
2146  * general, this means holding an exclusive (write) lock.
2147  */
2148 
2149 #define ISN_BYTES_PER_SECOND 1048576
2150 #define ISN_STATIC_INCREMENT 4096
2151 #define ISN_RANDOM_INCREMENT (4096 - 1)
2152 
2153 static VNET_DEFINE(u_char, isn_secret[32]);
2154 static VNET_DEFINE(int, isn_last);
2155 static VNET_DEFINE(int, isn_last_reseed);
2156 static VNET_DEFINE(u_int32_t, isn_offset);
2157 static VNET_DEFINE(u_int32_t, isn_offset_old);
2158 
2159 #define	V_isn_secret			VNET(isn_secret)
2160 #define	V_isn_last			VNET(isn_last)
2161 #define	V_isn_last_reseed		VNET(isn_last_reseed)
2162 #define	V_isn_offset			VNET(isn_offset)
2163 #define	V_isn_offset_old		VNET(isn_offset_old)
2164 
2165 tcp_seq
2166 tcp_new_isn(struct tcpcb *tp)
2167 {
2168 	MD5_CTX isn_ctx;
2169 	u_int32_t md5_buffer[4];
2170 	tcp_seq new_isn;
2171 	u_int32_t projected_offset;
2172 
2173 	INP_WLOCK_ASSERT(tp->t_inpcb);
2174 
2175 	ISN_LOCK();
2176 	/* Seed if this is the first use, reseed if requested. */
2177 	if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
2178 	     (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
2179 		< (u_int)ticks))) {
2180 		read_random(&V_isn_secret, sizeof(V_isn_secret));
2181 		V_isn_last_reseed = ticks;
2182 	}
2183 
2184 	/* Compute the md5 hash and return the ISN. */
2185 	MD5Init(&isn_ctx);
2186 	MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
2187 	MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
2188 #ifdef INET6
2189 	if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
2190 		MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
2191 			  sizeof(struct in6_addr));
2192 		MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
2193 			  sizeof(struct in6_addr));
2194 	} else
2195 #endif
2196 	{
2197 		MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
2198 			  sizeof(struct in_addr));
2199 		MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
2200 			  sizeof(struct in_addr));
2201 	}
2202 	MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret));
2203 	MD5Final((u_char *) &md5_buffer, &isn_ctx);
2204 	new_isn = (tcp_seq) md5_buffer[0];
2205 	V_isn_offset += ISN_STATIC_INCREMENT +
2206 		(arc4random() & ISN_RANDOM_INCREMENT);
2207 	if (ticks != V_isn_last) {
2208 		projected_offset = V_isn_offset_old +
2209 		    ISN_BYTES_PER_SECOND / hz * (ticks - V_isn_last);
2210 		if (SEQ_GT(projected_offset, V_isn_offset))
2211 			V_isn_offset = projected_offset;
2212 		V_isn_offset_old = V_isn_offset;
2213 		V_isn_last = ticks;
2214 	}
2215 	new_isn += V_isn_offset;
2216 	ISN_UNLOCK();
2217 	return (new_isn);
2218 }
2219 
2220 /*
2221  * When a specific ICMP unreachable message is received and the
2222  * connection state is SYN-SENT, drop the connection.  This behavior
2223  * is controlled by the icmp_may_rst sysctl.
2224  */
2225 struct inpcb *
2226 tcp_drop_syn_sent(struct inpcb *inp, int errno)
2227 {
2228 	struct tcpcb *tp;
2229 
2230 	INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
2231 	INP_WLOCK_ASSERT(inp);
2232 
2233 	if ((inp->inp_flags & INP_TIMEWAIT) ||
2234 	    (inp->inp_flags & INP_DROPPED))
2235 		return (inp);
2236 
2237 	tp = intotcpcb(inp);
2238 	if (tp->t_state != TCPS_SYN_SENT)
2239 		return (inp);
2240 
2241 	tp = tcp_drop(tp, errno);
2242 	if (tp != NULL)
2243 		return (inp);
2244 	else
2245 		return (NULL);
2246 }
2247 
2248 /*
2249  * When `need fragmentation' ICMP is received, update our idea of the MSS
2250  * based on the new value. Also nudge TCP to send something, since we
2251  * know the packet we just sent was dropped.
2252  * This duplicates some code in the tcp_mss() function in tcp_input.c.
2253  */
2254 static struct inpcb *
2255 tcp_mtudisc_notify(struct inpcb *inp, int error)
2256 {
2257 
2258 	tcp_mtudisc(inp, -1);
2259 	return (inp);
2260 }
2261 
2262 static void
2263 tcp_mtudisc(struct inpcb *inp, int mtuoffer)
2264 {
2265 	struct tcpcb *tp;
2266 	struct socket *so;
2267 
2268 	INP_WLOCK_ASSERT(inp);
2269 	if ((inp->inp_flags & INP_TIMEWAIT) ||
2270 	    (inp->inp_flags & INP_DROPPED))
2271 		return;
2272 
2273 	tp = intotcpcb(inp);
2274 	KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
2275 
2276 	tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
2277 
2278 	so = inp->inp_socket;
2279 	SOCKBUF_LOCK(&so->so_snd);
2280 	/* If the mss is larger than the socket buffer, decrease the mss. */
2281 	if (so->so_snd.sb_hiwat < tp->t_maxseg)
2282 		tp->t_maxseg = so->so_snd.sb_hiwat;
2283 	SOCKBUF_UNLOCK(&so->so_snd);
2284 
2285 	TCPSTAT_INC(tcps_mturesent);
2286 	tp->t_rtttime = 0;
2287 	tp->snd_nxt = tp->snd_una;
2288 	tcp_free_sackholes(tp);
2289 	tp->snd_recover = tp->snd_max;
2290 	if (tp->t_flags & TF_SACK_PERMIT)
2291 		EXIT_FASTRECOVERY(tp->t_flags);
2292 	tp->t_fb->tfb_tcp_output(tp);
2293 }
2294 
2295 #ifdef INET
2296 /*
2297  * Look-up the routing entry to the peer of this inpcb.  If no route
2298  * is found and it cannot be allocated, then return 0.  This routine
2299  * is called by TCP routines that access the rmx structure and by
2300  * tcp_mss_update to get the peer/interface MTU.
2301  */
2302 u_long
2303 tcp_maxmtu(struct in_conninfo *inc, struct tcp_ifcap *cap)
2304 {
2305 	struct nhop4_extended nh4;
2306 	struct ifnet *ifp;
2307 	u_long maxmtu = 0;
2308 
2309 	KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
2310 
2311 	if (inc->inc_faddr.s_addr != INADDR_ANY) {
2312 
2313 		if (fib4_lookup_nh_ext(inc->inc_fibnum, inc->inc_faddr,
2314 		    NHR_REF, 0, &nh4) != 0)
2315 			return (0);
2316 
2317 		ifp = nh4.nh_ifp;
2318 		maxmtu = nh4.nh_mtu;
2319 
2320 		/* Report additional interface capabilities. */
2321 		if (cap != NULL) {
2322 			if (ifp->if_capenable & IFCAP_TSO4 &&
2323 			    ifp->if_hwassist & CSUM_TSO) {
2324 				cap->ifcap |= CSUM_TSO;
2325 				cap->tsomax = ifp->if_hw_tsomax;
2326 				cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
2327 				cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
2328 			}
2329 		}
2330 		fib4_free_nh_ext(inc->inc_fibnum, &nh4);
2331 	}
2332 	return (maxmtu);
2333 }
2334 #endif /* INET */
2335 
2336 #ifdef INET6
2337 u_long
2338 tcp_maxmtu6(struct in_conninfo *inc, struct tcp_ifcap *cap)
2339 {
2340 	struct nhop6_extended nh6;
2341 	struct in6_addr dst6;
2342 	uint32_t scopeid;
2343 	struct ifnet *ifp;
2344 	u_long maxmtu = 0;
2345 
2346 	KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
2347 
2348 	if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
2349 		in6_splitscope(&inc->inc6_faddr, &dst6, &scopeid);
2350 		if (fib6_lookup_nh_ext(inc->inc_fibnum, &dst6, scopeid, 0,
2351 		    0, &nh6) != 0)
2352 			return (0);
2353 
2354 		ifp = nh6.nh_ifp;
2355 		maxmtu = nh6.nh_mtu;
2356 
2357 		/* Report additional interface capabilities. */
2358 		if (cap != NULL) {
2359 			if (ifp->if_capenable & IFCAP_TSO6 &&
2360 			    ifp->if_hwassist & CSUM_TSO) {
2361 				cap->ifcap |= CSUM_TSO;
2362 				cap->tsomax = ifp->if_hw_tsomax;
2363 				cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
2364 				cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
2365 			}
2366 		}
2367 		fib6_free_nh_ext(inc->inc_fibnum, &nh6);
2368 	}
2369 
2370 	return (maxmtu);
2371 }
2372 #endif /* INET6 */
2373 
2374 /*
2375  * Calculate effective SMSS per RFC5681 definition for a given TCP
2376  * connection at its current state, taking into account SACK and etc.
2377  */
2378 u_int
2379 tcp_maxseg(const struct tcpcb *tp)
2380 {
2381 	u_int optlen;
2382 
2383 	if (tp->t_flags & TF_NOOPT)
2384 		return (tp->t_maxseg);
2385 
2386 	/*
2387 	 * Here we have a simplified code from tcp_addoptions(),
2388 	 * without a proper loop, and having most of paddings hardcoded.
2389 	 * We might make mistakes with padding here in some edge cases,
2390 	 * but this is harmless, since result of tcp_maxseg() is used
2391 	 * only in cwnd and ssthresh estimations.
2392 	 */
2393 #define	PAD(len)	((((len) / 4) + !!((len) % 4)) * 4)
2394 	if (TCPS_HAVEESTABLISHED(tp->t_state)) {
2395 		if (tp->t_flags & TF_RCVD_TSTMP)
2396 			optlen = TCPOLEN_TSTAMP_APPA;
2397 		else
2398 			optlen = 0;
2399 #ifdef TCP_SIGNATURE
2400 		if (tp->t_flags & TF_SIGNATURE)
2401 			optlen += PAD(TCPOLEN_SIGNATURE);
2402 #endif
2403 		if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks > 0) {
2404 			optlen += TCPOLEN_SACKHDR;
2405 			optlen += tp->rcv_numsacks * TCPOLEN_SACK;
2406 			optlen = PAD(optlen);
2407 		}
2408 	} else {
2409 		if (tp->t_flags & TF_REQ_TSTMP)
2410 			optlen = TCPOLEN_TSTAMP_APPA;
2411 		else
2412 			optlen = PAD(TCPOLEN_MAXSEG);
2413 		if (tp->t_flags & TF_REQ_SCALE)
2414 			optlen += PAD(TCPOLEN_WINDOW);
2415 #ifdef TCP_SIGNATURE
2416 		if (tp->t_flags & TF_SIGNATURE)
2417 			optlen += PAD(TCPOLEN_SIGNATURE);
2418 #endif
2419 		if (tp->t_flags & TF_SACK_PERMIT)
2420 			optlen += PAD(TCPOLEN_SACK_PERMITTED);
2421 	}
2422 #undef PAD
2423 	optlen = min(optlen, TCP_MAXOLEN);
2424 	return (tp->t_maxseg - optlen);
2425 }
2426 
2427 #ifdef IPSEC
2428 /* compute ESP/AH header size for TCP, including outer IP header. */
2429 size_t
2430 ipsec_hdrsiz_tcp(struct tcpcb *tp)
2431 {
2432 	struct inpcb *inp;
2433 	struct mbuf *m;
2434 	size_t hdrsiz;
2435 	struct ip *ip;
2436 #ifdef INET6
2437 	struct ip6_hdr *ip6;
2438 #endif
2439 	struct tcphdr *th;
2440 
2441 	if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL) ||
2442 		(!key_havesp(IPSEC_DIR_OUTBOUND)))
2443 		return (0);
2444 	m = m_gethdr(M_NOWAIT, MT_DATA);
2445 	if (!m)
2446 		return (0);
2447 
2448 #ifdef INET6
2449 	if ((inp->inp_vflag & INP_IPV6) != 0) {
2450 		ip6 = mtod(m, struct ip6_hdr *);
2451 		th = (struct tcphdr *)(ip6 + 1);
2452 		m->m_pkthdr.len = m->m_len =
2453 			sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
2454 		tcpip_fillheaders(inp, ip6, th);
2455 		hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
2456 	} else
2457 #endif /* INET6 */
2458 	{
2459 		ip = mtod(m, struct ip *);
2460 		th = (struct tcphdr *)(ip + 1);
2461 		m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
2462 		tcpip_fillheaders(inp, ip, th);
2463 		hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
2464 	}
2465 
2466 	m_free(m);
2467 	return (hdrsiz);
2468 }
2469 #endif /* IPSEC */
2470 
2471 #ifdef TCP_SIGNATURE
2472 /*
2473  * Callback function invoked by m_apply() to digest TCP segment data
2474  * contained within an mbuf chain.
2475  */
2476 static int
2477 tcp_signature_apply(void *fstate, void *data, u_int len)
2478 {
2479 
2480 	MD5Update(fstate, (u_char *)data, len);
2481 	return (0);
2482 }
2483 
2484 /*
2485  * XXX The key is retrieved from the system's PF_KEY SADB, by keying a
2486  * search with the destination IP address, and a 'magic SPI' to be
2487  * determined by the application. This is hardcoded elsewhere to 1179
2488 */
2489 struct secasvar *
2490 tcp_get_sav(struct mbuf *m, u_int direction)
2491 {
2492 	union sockaddr_union dst;
2493 	struct secasvar *sav;
2494 	struct ip *ip;
2495 #ifdef INET6
2496 	struct ip6_hdr *ip6;
2497 	char ip6buf[INET6_ADDRSTRLEN];
2498 #endif
2499 
2500 	/* Extract the destination from the IP header in the mbuf. */
2501 	bzero(&dst, sizeof(union sockaddr_union));
2502 	ip = mtod(m, struct ip *);
2503 #ifdef INET6
2504 	ip6 = NULL;	/* Make the compiler happy. */
2505 #endif
2506 	switch (ip->ip_v) {
2507 #ifdef INET
2508 	case IPVERSION:
2509 		dst.sa.sa_len = sizeof(struct sockaddr_in);
2510 		dst.sa.sa_family = AF_INET;
2511 		dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ?
2512 		    ip->ip_src : ip->ip_dst;
2513 		break;
2514 #endif
2515 #ifdef INET6
2516 	case (IPV6_VERSION >> 4):
2517 		ip6 = mtod(m, struct ip6_hdr *);
2518 		dst.sa.sa_len = sizeof(struct sockaddr_in6);
2519 		dst.sa.sa_family = AF_INET6;
2520 		dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ?
2521 		    ip6->ip6_src : ip6->ip6_dst;
2522 		break;
2523 #endif
2524 	default:
2525 		return (NULL);
2526 		/* NOTREACHED */
2527 		break;
2528 	}
2529 
2530 	/* Look up an SADB entry which matches the address of the peer. */
2531 	sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI));
2532 	if (sav == NULL) {
2533 		ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__,
2534 		    (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) :
2535 #ifdef INET6
2536 			(ip->ip_v == (IPV6_VERSION >> 4)) ?
2537 			    ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) :
2538 #endif
2539 			"(unsupported)"));
2540 	}
2541 
2542 	return (sav);
2543 }
2544 
2545 /*
2546  * Compute TCP-MD5 hash of a TCP segment. (RFC2385)
2547  *
2548  * Parameters:
2549  * m		pointer to head of mbuf chain
2550  * len		length of TCP segment data, excluding options
2551  * optlen	length of TCP segment options
2552  * buf		pointer to storage for computed MD5 digest
2553  * sav		pointer to security assosiation
2554  *
2555  * We do this over ip, tcphdr, segment data, and the key in the SADB.
2556  * When called from tcp_input(), we can be sure that th_sum has been
2557  * zeroed out and verified already.
2558  *
2559  * Releases reference to SADB key before return.
2560  *
2561  * Return 0 if successful, otherwise return -1.
2562  *
2563  */
2564 int
2565 tcp_signature_do_compute(struct mbuf *m, int len, int optlen,
2566     u_char *buf, struct secasvar *sav)
2567 {
2568 #ifdef INET
2569 	struct ippseudo ippseudo;
2570 #endif
2571 	MD5_CTX ctx;
2572 	int doff;
2573 	struct ip *ip;
2574 #ifdef INET
2575 	struct ipovly *ipovly;
2576 #endif
2577 	struct tcphdr *th;
2578 #ifdef INET6
2579 	struct ip6_hdr *ip6;
2580 	struct in6_addr in6;
2581 	uint32_t plen;
2582 	uint16_t nhdr;
2583 #endif
2584 	u_short savecsum;
2585 
2586 	KASSERT(m != NULL, ("NULL mbuf chain"));
2587 	KASSERT(buf != NULL, ("NULL signature pointer"));
2588 
2589 	/* Extract the destination from the IP header in the mbuf. */
2590 	ip = mtod(m, struct ip *);
2591 #ifdef INET6
2592 	ip6 = NULL;	/* Make the compiler happy. */
2593 #endif
2594 
2595 	MD5Init(&ctx);
2596 	/*
2597 	 * Step 1: Update MD5 hash with IP(v6) pseudo-header.
2598 	 *
2599 	 * XXX The ippseudo header MUST be digested in network byte order,
2600 	 * or else we'll fail the regression test. Assume all fields we've
2601 	 * been doing arithmetic on have been in host byte order.
2602 	 * XXX One cannot depend on ipovly->ih_len here. When called from
2603 	 * tcp_output(), the underlying ip_len member has not yet been set.
2604 	 */
2605 	switch (ip->ip_v) {
2606 #ifdef INET
2607 	case IPVERSION:
2608 		ipovly = (struct ipovly *)ip;
2609 		ippseudo.ippseudo_src = ipovly->ih_src;
2610 		ippseudo.ippseudo_dst = ipovly->ih_dst;
2611 		ippseudo.ippseudo_pad = 0;
2612 		ippseudo.ippseudo_p = IPPROTO_TCP;
2613 		ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) +
2614 		    optlen);
2615 		MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo));
2616 
2617 		th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip));
2618 		doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen;
2619 		break;
2620 #endif
2621 #ifdef INET6
2622 	/*
2623 	 * RFC 2385, 2.0  Proposal
2624 	 * For IPv6, the pseudo-header is as described in RFC 2460, namely the
2625 	 * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero-
2626 	 * extended next header value (to form 32 bits), and 32-bit segment
2627 	 * length.
2628 	 * Note: Upper-Layer Packet Length comes before Next Header.
2629 	 */
2630 	case (IPV6_VERSION >> 4):
2631 		in6 = ip6->ip6_src;
2632 		in6_clearscope(&in6);
2633 		MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
2634 		in6 = ip6->ip6_dst;
2635 		in6_clearscope(&in6);
2636 		MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
2637 		plen = htonl(len + sizeof(struct tcphdr) + optlen);
2638 		MD5Update(&ctx, (char *)&plen, sizeof(uint32_t));
2639 		nhdr = 0;
2640 		MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
2641 		MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
2642 		MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
2643 		nhdr = IPPROTO_TCP;
2644 		MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
2645 
2646 		th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr));
2647 		doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen;
2648 		break;
2649 #endif
2650 	default:
2651 		KEY_FREESAV(&sav);
2652 		return (-1);
2653 		/* NOTREACHED */
2654 		break;
2655 	}
2656 
2657 
2658 	/*
2659 	 * Step 2: Update MD5 hash with TCP header, excluding options.
2660 	 * The TCP checksum must be set to zero.
2661 	 */
2662 	savecsum = th->th_sum;
2663 	th->th_sum = 0;
2664 	MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
2665 	th->th_sum = savecsum;
2666 
2667 	/*
2668 	 * Step 3: Update MD5 hash with TCP segment data.
2669 	 *         Use m_apply() to avoid an early m_pullup().
2670 	 */
2671 	if (len > 0)
2672 		m_apply(m, doff, len, tcp_signature_apply, &ctx);
2673 
2674 	/*
2675 	 * Step 4: Update MD5 hash with shared secret.
2676 	 */
2677 	MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
2678 	MD5Final(buf, &ctx);
2679 
2680 	key_sa_recordxfer(sav, m);
2681 	KEY_FREESAV(&sav);
2682 	return (0);
2683 }
2684 
2685 /*
2686  * Compute TCP-MD5 hash of a TCP segment. (RFC2385)
2687  *
2688  * Return 0 if successful, otherwise return -1.
2689  */
2690 int
2691 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen,
2692     u_char *buf, u_int direction)
2693 {
2694 	struct secasvar *sav;
2695 
2696 	if ((sav = tcp_get_sav(m, direction)) == NULL)
2697 		return (-1);
2698 
2699 	return (tcp_signature_do_compute(m, len, optlen, buf, sav));
2700 }
2701 
2702 /*
2703  * Verify the TCP-MD5 hash of a TCP segment. (RFC2385)
2704  *
2705  * Parameters:
2706  * m		pointer to head of mbuf chain
2707  * len		length of TCP segment data, excluding options
2708  * optlen	length of TCP segment options
2709  * buf		pointer to storage for computed MD5 digest
2710  * direction	direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
2711  *
2712  * Return 1 if successful, otherwise return 0.
2713  */
2714 int
2715 tcp_signature_verify(struct mbuf *m, int off0, int tlen, int optlen,
2716     struct tcpopt *to, struct tcphdr *th, u_int tcpbflag)
2717 {
2718 	char tmpdigest[TCP_SIGLEN];
2719 
2720 	if (tcp_sig_checksigs == 0)
2721 		return (1);
2722 	if ((tcpbflag & TF_SIGNATURE) == 0) {
2723 		if ((to->to_flags & TOF_SIGNATURE) != 0) {
2724 
2725 			/*
2726 			 * If this socket is not expecting signature but
2727 			 * the segment contains signature just fail.
2728 			 */
2729 			TCPSTAT_INC(tcps_sig_err_sigopt);
2730 			TCPSTAT_INC(tcps_sig_rcvbadsig);
2731 			return (0);
2732 		}
2733 
2734 		/* Signature is not expected, and not present in segment. */
2735 		return (1);
2736 	}
2737 
2738 	/*
2739 	 * If this socket is expecting signature but the segment does not
2740 	 * contain any just fail.
2741 	 */
2742 	if ((to->to_flags & TOF_SIGNATURE) == 0) {
2743 		TCPSTAT_INC(tcps_sig_err_nosigopt);
2744 		TCPSTAT_INC(tcps_sig_rcvbadsig);
2745 		return (0);
2746 	}
2747 	if (tcp_signature_compute(m, off0, tlen, optlen, &tmpdigest[0],
2748 	    IPSEC_DIR_INBOUND) == -1) {
2749 		TCPSTAT_INC(tcps_sig_err_buildsig);
2750 		TCPSTAT_INC(tcps_sig_rcvbadsig);
2751 		return (0);
2752 	}
2753 
2754 	if (bcmp(to->to_signature, &tmpdigest[0], TCP_SIGLEN) != 0) {
2755 		TCPSTAT_INC(tcps_sig_rcvbadsig);
2756 		return (0);
2757 	}
2758 	TCPSTAT_INC(tcps_sig_rcvgoodsig);
2759 	return (1);
2760 }
2761 #endif /* TCP_SIGNATURE */
2762 
2763 static int
2764 sysctl_drop(SYSCTL_HANDLER_ARGS)
2765 {
2766 	/* addrs[0] is a foreign socket, addrs[1] is a local one. */
2767 	struct sockaddr_storage addrs[2];
2768 	struct inpcb *inp;
2769 	struct tcpcb *tp;
2770 	struct tcptw *tw;
2771 	struct sockaddr_in *fin, *lin;
2772 #ifdef INET6
2773 	struct sockaddr_in6 *fin6, *lin6;
2774 #endif
2775 	int error;
2776 
2777 	inp = NULL;
2778 	fin = lin = NULL;
2779 #ifdef INET6
2780 	fin6 = lin6 = NULL;
2781 #endif
2782 	error = 0;
2783 
2784 	if (req->oldptr != NULL || req->oldlen != 0)
2785 		return (EINVAL);
2786 	if (req->newptr == NULL)
2787 		return (EPERM);
2788 	if (req->newlen < sizeof(addrs))
2789 		return (ENOMEM);
2790 	error = SYSCTL_IN(req, &addrs, sizeof(addrs));
2791 	if (error)
2792 		return (error);
2793 
2794 	switch (addrs[0].ss_family) {
2795 #ifdef INET6
2796 	case AF_INET6:
2797 		fin6 = (struct sockaddr_in6 *)&addrs[0];
2798 		lin6 = (struct sockaddr_in6 *)&addrs[1];
2799 		if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
2800 		    lin6->sin6_len != sizeof(struct sockaddr_in6))
2801 			return (EINVAL);
2802 		if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
2803 			if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
2804 				return (EINVAL);
2805 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
2806 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
2807 			fin = (struct sockaddr_in *)&addrs[0];
2808 			lin = (struct sockaddr_in *)&addrs[1];
2809 			break;
2810 		}
2811 		error = sa6_embedscope(fin6, V_ip6_use_defzone);
2812 		if (error)
2813 			return (error);
2814 		error = sa6_embedscope(lin6, V_ip6_use_defzone);
2815 		if (error)
2816 			return (error);
2817 		break;
2818 #endif
2819 #ifdef INET
2820 	case AF_INET:
2821 		fin = (struct sockaddr_in *)&addrs[0];
2822 		lin = (struct sockaddr_in *)&addrs[1];
2823 		if (fin->sin_len != sizeof(struct sockaddr_in) ||
2824 		    lin->sin_len != sizeof(struct sockaddr_in))
2825 			return (EINVAL);
2826 		break;
2827 #endif
2828 	default:
2829 		return (EINVAL);
2830 	}
2831 	INP_INFO_RLOCK(&V_tcbinfo);
2832 	switch (addrs[0].ss_family) {
2833 #ifdef INET6
2834 	case AF_INET6:
2835 		inp = in6_pcblookup(&V_tcbinfo, &fin6->sin6_addr,
2836 		    fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port,
2837 		    INPLOOKUP_WLOCKPCB, NULL);
2838 		break;
2839 #endif
2840 #ifdef INET
2841 	case AF_INET:
2842 		inp = in_pcblookup(&V_tcbinfo, fin->sin_addr, fin->sin_port,
2843 		    lin->sin_addr, lin->sin_port, INPLOOKUP_WLOCKPCB, NULL);
2844 		break;
2845 #endif
2846 	}
2847 	if (inp != NULL) {
2848 		if (inp->inp_flags & INP_TIMEWAIT) {
2849 			/*
2850 			 * XXXRW: There currently exists a state where an
2851 			 * inpcb is present, but its timewait state has been
2852 			 * discarded.  For now, don't allow dropping of this
2853 			 * type of inpcb.
2854 			 */
2855 			tw = intotw(inp);
2856 			if (tw != NULL)
2857 				tcp_twclose(tw, 0);
2858 			else
2859 				INP_WUNLOCK(inp);
2860 		} else if (!(inp->inp_flags & INP_DROPPED) &&
2861 			   !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
2862 			tp = intotcpcb(inp);
2863 			tp = tcp_drop(tp, ECONNABORTED);
2864 			if (tp != NULL)
2865 				INP_WUNLOCK(inp);
2866 		} else
2867 			INP_WUNLOCK(inp);
2868 	} else
2869 		error = ESRCH;
2870 	INP_INFO_RUNLOCK(&V_tcbinfo);
2871 	return (error);
2872 }
2873 
2874 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
2875     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP, NULL,
2876     0, sysctl_drop, "", "Drop TCP connection");
2877 
2878 /*
2879  * Generate a standardized TCP log line for use throughout the
2880  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
2881  * allow use in the interrupt context.
2882  *
2883  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
2884  * NB: The function may return NULL if memory allocation failed.
2885  *
2886  * Due to header inclusion and ordering limitations the struct ip
2887  * and ip6_hdr pointers have to be passed as void pointers.
2888  */
2889 char *
2890 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2891     const void *ip6hdr)
2892 {
2893 
2894 	/* Is logging enabled? */
2895 	if (tcp_log_in_vain == 0)
2896 		return (NULL);
2897 
2898 	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
2899 }
2900 
2901 char *
2902 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2903     const void *ip6hdr)
2904 {
2905 
2906 	/* Is logging enabled? */
2907 	if (tcp_log_debug == 0)
2908 		return (NULL);
2909 
2910 	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
2911 }
2912 
2913 static char *
2914 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2915     const void *ip6hdr)
2916 {
2917 	char *s, *sp;
2918 	size_t size;
2919 	struct ip *ip;
2920 #ifdef INET6
2921 	const struct ip6_hdr *ip6;
2922 
2923 	ip6 = (const struct ip6_hdr *)ip6hdr;
2924 #endif /* INET6 */
2925 	ip = (struct ip *)ip4hdr;
2926 
2927 	/*
2928 	 * The log line looks like this:
2929 	 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
2930 	 */
2931 	size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
2932 	    sizeof(PRINT_TH_FLAGS) + 1 +
2933 #ifdef INET6
2934 	    2 * INET6_ADDRSTRLEN;
2935 #else
2936 	    2 * INET_ADDRSTRLEN;
2937 #endif /* INET6 */
2938 
2939 	s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
2940 	if (s == NULL)
2941 		return (NULL);
2942 
2943 	strcat(s, "TCP: [");
2944 	sp = s + strlen(s);
2945 
2946 	if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
2947 		inet_ntoa_r(inc->inc_faddr, sp);
2948 		sp = s + strlen(s);
2949 		sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2950 		sp = s + strlen(s);
2951 		inet_ntoa_r(inc->inc_laddr, sp);
2952 		sp = s + strlen(s);
2953 		sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2954 #ifdef INET6
2955 	} else if (inc) {
2956 		ip6_sprintf(sp, &inc->inc6_faddr);
2957 		sp = s + strlen(s);
2958 		sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2959 		sp = s + strlen(s);
2960 		ip6_sprintf(sp, &inc->inc6_laddr);
2961 		sp = s + strlen(s);
2962 		sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2963 	} else if (ip6 && th) {
2964 		ip6_sprintf(sp, &ip6->ip6_src);
2965 		sp = s + strlen(s);
2966 		sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2967 		sp = s + strlen(s);
2968 		ip6_sprintf(sp, &ip6->ip6_dst);
2969 		sp = s + strlen(s);
2970 		sprintf(sp, "]:%i", ntohs(th->th_dport));
2971 #endif /* INET6 */
2972 #ifdef INET
2973 	} else if (ip && th) {
2974 		inet_ntoa_r(ip->ip_src, sp);
2975 		sp = s + strlen(s);
2976 		sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2977 		sp = s + strlen(s);
2978 		inet_ntoa_r(ip->ip_dst, sp);
2979 		sp = s + strlen(s);
2980 		sprintf(sp, "]:%i", ntohs(th->th_dport));
2981 #endif /* INET */
2982 	} else {
2983 		free(s, M_TCPLOG);
2984 		return (NULL);
2985 	}
2986 	sp = s + strlen(s);
2987 	if (th)
2988 		sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
2989 	if (*(s + size - 1) != '\0')
2990 		panic("%s: string too long", __func__);
2991 	return (s);
2992 }
2993 
2994 /*
2995  * A subroutine which makes it easy to track TCP state changes with DTrace.
2996  * This function shouldn't be called for t_state initializations that don't
2997  * correspond to actual TCP state transitions.
2998  */
2999 void
3000 tcp_state_change(struct tcpcb *tp, int newstate)
3001 {
3002 #if defined(KDTRACE_HOOKS)
3003 	int pstate = tp->t_state;
3004 #endif
3005 
3006 	TCPSTATES_DEC(tp->t_state);
3007 	TCPSTATES_INC(newstate);
3008 	tp->t_state = newstate;
3009 	TCP_PROBE6(state__change, NULL, tp, NULL, tp, NULL, pstate);
3010 }
3011