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_mac.h"
40 #include "opt_tcpdebug.h"
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/callout.h>
45 #include <sys/kernel.h>
46 #include <sys/sysctl.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #ifdef INET6
50 #include <sys/domain.h>
51 #endif
52 #include <sys/priv.h>
53 #include <sys/proc.h>
54 #include <sys/socket.h>
55 #include <sys/socketvar.h>
56 #include <sys/protosw.h>
57 #include <sys/random.h>
58
59 #include <vm/uma.h>
60
61 #include <net/route.h>
62 #include <net/if.h>
63
64 #include <netinet/in.h>
65 #include <netinet/in_systm.h>
66 #include <netinet/ip.h>
67 #ifdef INET6
68 #include <netinet/ip6.h>
69 #endif
70 #include <netinet/in_pcb.h>
71 #ifdef INET6
72 #include <netinet6/in6_pcb.h>
73 #endif
74 #include <netinet/in_var.h>
75 #include <netinet/ip_var.h>
76 #ifdef INET6
77 #include <netinet6/ip6_var.h>
78 #include <netinet6/scope6_var.h>
79 #include <netinet6/nd6.h>
80 #endif
81 #include <netinet/ip_icmp.h>
82 #include <netinet/tcp.h>
83 #include <netinet/tcp_fsm.h>
84 #include <netinet/tcp_seq.h>
85 #include <netinet/tcp_timer.h>
86 #include <netinet/tcp_var.h>
87 #include <netinet/tcp_syncache.h>
88 #ifdef INET6
89 #include <netinet6/tcp6_var.h>
90 #endif
91 #include <netinet/tcpip.h>
92 #ifdef TCPDEBUG
93 #include <netinet/tcp_debug.h>
94 #endif
95 #include <netinet6/ip6protosw.h>
96
97 #ifdef IPSEC
98 #include <netipsec/ipsec.h>
99 #include <netipsec/xform.h>
100 #ifdef INET6
101 #include <netipsec/ipsec6.h>
102 #endif
103 #include <netipsec/key.h>
104 #endif /*IPSEC*/
105
106 #include <machine/in_cksum.h>
107 #include <sys/md5.h>
108
109 #include <security/mac/mac_framework.h>
110
111 int tcp_mssdflt = TCP_MSS;
112 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
113 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size");
114
115 #ifdef INET6
116 int tcp_v6mssdflt = TCP6_MSS;
117 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
118 CTLFLAG_RW, &tcp_v6mssdflt , 0,
119 "Default TCP Maximum Segment Size for IPv6");
120 #endif
121
122 /*
123 * Minimum MSS we accept and use. This prevents DoS attacks where
124 * we are forced to a ridiculous low MSS like 20 and send hundreds
125 * of packets instead of one. The effect scales with the available
126 * bandwidth and quickly saturates the CPU and network interface
127 * with packet generation and sending. Set to zero to disable MINMSS
128 * checking. This setting prevents us from sending too small packets.
129 */
130 int tcp_minmss = TCP_MINMSS;
131 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
132 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size");
133
134 int tcp_do_rfc1323 = 1;
135 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
136 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions");
137
138 static int tcp_log_debug = 0;
139 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
140 &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
141
142 static int tcp_tcbhashsize = 0;
143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN,
144 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
145
146 static int do_tcpdrain = 1;
147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW,
148 &do_tcpdrain, 0,
149 "Enable tcp_drain routine for extra help when low on mbufs");
150
151 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
152 &tcbinfo.ipi_count, 0, "Number of active PCBs");
153
154 static int icmp_may_rst = 1;
155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW,
156 &icmp_may_rst, 0,
157 "Certain ICMP unreachable messages may abort connections in SYN_SENT");
158
159 static int tcp_isn_reseed_interval = 0;
160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
161 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
162
163 /*
164 * TCP bandwidth limiting sysctls. Note that the default lower bound of
165 * 1024 exists only for debugging. A good production default would be
166 * something like 6100.
167 */
168 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0,
169 "TCP inflight data limiting");
170
171 static int tcp_inflight_enable = 1;
172 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW,
173 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
174
175 static int tcp_inflight_debug = 0;
176 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW,
177 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
178
179 static int tcp_inflight_rttthresh;
180 SYSCTL_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh, CTLTYPE_INT|CTLFLAG_RW,
181 &tcp_inflight_rttthresh, 0, sysctl_msec_to_ticks, "I",
182 "RTT threshold below which inflight will deactivate itself");
183
184 static int tcp_inflight_min = 6144;
185 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW,
186 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
187
188 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
189 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW,
190 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window");
191
192 static int tcp_inflight_stab = 20;
193 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW,
194 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets");
195
196 uma_zone_t sack_hole_zone;
197
198 static struct inpcb *tcp_notify(struct inpcb *, int);
199 static void tcp_isn_tick(void *);
200
201 /*
202 * Target size of TCP PCB hash tables. Must be a power of two.
203 *
204 * Note that this can be overridden by the kernel environment
205 * variable net.inet.tcp.tcbhashsize
206 */
207 #ifndef TCBHASHSIZE
208 #define TCBHASHSIZE 512
209 #endif
210
211 /*
212 * XXX
213 * Callouts should be moved into struct tcp directly. They are currently
214 * separate because the tcpcb structure is exported to userland for sysctl
215 * parsing purposes, which do not know about callouts.
216 */
217 struct tcpcb_mem {
218 struct tcpcb tcb;
219 struct tcp_timer tt;
220 };
221
222 static uma_zone_t tcpcb_zone;
223 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
224 struct callout isn_callout;
225 static struct mtx isn_mtx;
226
227 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
228 #define ISN_LOCK() mtx_lock(&isn_mtx)
229 #define ISN_UNLOCK() mtx_unlock(&isn_mtx)
230
231 /*
232 * TCP initialization.
233 */
234 static void
235 tcp_zone_change(void *tag)
236 {
237
238 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets);
239 uma_zone_set_max(tcpcb_zone, maxsockets);
240 tcp_tw_zone_change();
241 }
242
243 static int
244 tcp_inpcb_init(void *mem, int size, int flags)
245 {
246 struct inpcb *inp = mem;
247
248 INP_LOCK_INIT(inp, "inp", "tcpinp");
249 return (0);
250 }
251
252 void
253 tcp_init(void)
254 {
255
256 int hashsize = TCBHASHSIZE;
257 tcp_delacktime = TCPTV_DELACK;
258 tcp_keepinit = TCPTV_KEEP_INIT;
259 tcp_keepidle = TCPTV_KEEP_IDLE;
260 tcp_keepintvl = TCPTV_KEEPINTVL;
261 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
262 tcp_msl = TCPTV_MSL;
263 tcp_rexmit_min = TCPTV_MIN;
264 if (tcp_rexmit_min < 1)
265 tcp_rexmit_min = 1;
266 tcp_rexmit_slop = TCPTV_CPU_VAR;
267 tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH;
268 tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
269
270 INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
271 LIST_INIT(&tcb);
272 tcbinfo.ipi_listhead = &tcb;
273 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
274 if (!powerof2(hashsize)) {
275 printf("WARNING: TCB hash size not a power of 2\n");
276 hashsize = 512; /* safe default */
277 }
278 tcp_tcbhashsize = hashsize;
279 tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB,
280 &tcbinfo.ipi_hashmask);
281 tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB,
282 &tcbinfo.ipi_porthashmask);
283 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb),
284 NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
285 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets);
286 #ifdef INET6
287 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
288 #else /* INET6 */
289 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
290 #endif /* INET6 */
291 if (max_protohdr < TCP_MINPROTOHDR)
292 max_protohdr = TCP_MINPROTOHDR;
293 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
294 panic("tcp_init");
295 #undef TCP_MINPROTOHDR
296 /*
297 * These have to be type stable for the benefit of the timers.
298 */
299 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
300 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
301 uma_zone_set_max(tcpcb_zone, maxsockets);
302 tcp_tw_init();
303 syncache_init();
304 tcp_hc_init();
305 tcp_reass_init();
306 ISN_LOCK_INIT();
307 callout_init(&isn_callout, CALLOUT_MPSAFE);
308 tcp_isn_tick(NULL);
309 EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
310 SHUTDOWN_PRI_DEFAULT);
311 sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
312 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
313 EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
314 EVENTHANDLER_PRI_ANY);
315 }
316
317 void
318 tcp_fini(void *xtp)
319 {
320
321 callout_stop(&isn_callout);
322 }
323
324 /*
325 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
326 * tcp_template used to store this data in mbufs, but we now recopy it out
327 * of the tcpcb each time to conserve mbufs.
328 */
329 void
330 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
331 {
332 struct tcphdr *th = (struct tcphdr *)tcp_ptr;
333
334 INP_LOCK_ASSERT(inp);
335
336 #ifdef INET6
337 if ((inp->inp_vflag & INP_IPV6) != 0) {
338 struct ip6_hdr *ip6;
339
340 ip6 = (struct ip6_hdr *)ip_ptr;
341 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
342 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
343 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
344 (IPV6_VERSION & IPV6_VERSION_MASK);
345 ip6->ip6_nxt = IPPROTO_TCP;
346 ip6->ip6_plen = sizeof(struct tcphdr);
347 ip6->ip6_src = inp->in6p_laddr;
348 ip6->ip6_dst = inp->in6p_faddr;
349 } else
350 #endif
351 {
352 struct ip *ip;
353
354 ip = (struct ip *)ip_ptr;
355 ip->ip_v = IPVERSION;
356 ip->ip_hl = 5;
357 ip->ip_tos = inp->inp_ip_tos;
358 ip->ip_len = 0;
359 ip->ip_id = 0;
360 ip->ip_off = 0;
361 ip->ip_ttl = inp->inp_ip_ttl;
362 ip->ip_sum = 0;
363 ip->ip_p = IPPROTO_TCP;
364 ip->ip_src = inp->inp_laddr;
365 ip->ip_dst = inp->inp_faddr;
366 }
367 th->th_sport = inp->inp_lport;
368 th->th_dport = inp->inp_fport;
369 th->th_seq = 0;
370 th->th_ack = 0;
371 th->th_x2 = 0;
372 th->th_off = 5;
373 th->th_flags = 0;
374 th->th_win = 0;
375 th->th_urp = 0;
376 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */
377 }
378
379 /*
380 * Create template to be used to send tcp packets on a connection.
381 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only
382 * use for this function is in keepalives, which use tcp_respond.
383 */
384 struct tcptemp *
385 tcpip_maketemplate(struct inpcb *inp)
386 {
387 struct mbuf *m;
388 struct tcptemp *n;
389
390 m = m_get(M_DONTWAIT, MT_DATA);
391 if (m == NULL)
392 return (0);
393 m->m_len = sizeof(struct tcptemp);
394 n = mtod(m, struct tcptemp *);
395
396 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t);
397 return (n);
398 }
399
400 /*
401 * Send a single message to the TCP at address specified by
402 * the given TCP/IP header. If m == NULL, then we make a copy
403 * of the tcpiphdr at ti and send directly to the addressed host.
404 * This is used to force keep alive messages out using the TCP
405 * template for a connection. If flags are given then we send
406 * a message back to the TCP which originated the * segment ti,
407 * and discard the mbuf containing it and any other attached mbufs.
408 *
409 * In any case the ack and sequence number of the transmitted
410 * segment are as specified by the parameters.
411 *
412 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
413 */
414 void
415 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
416 tcp_seq ack, tcp_seq seq, int flags)
417 {
418 int tlen;
419 int win = 0;
420 struct ip *ip;
421 struct tcphdr *nth;
422 #ifdef INET6
423 struct ip6_hdr *ip6;
424 int isipv6;
425 #endif /* INET6 */
426 int ipflags = 0;
427 struct inpcb *inp;
428
429 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
430
431 #ifdef INET6
432 isipv6 = ((struct ip *)ipgen)->ip_v == 6;
433 ip6 = ipgen;
434 #endif /* INET6 */
435 ip = ipgen;
436
437 if (tp != NULL) {
438 inp = tp->t_inpcb;
439 KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
440 INP_LOCK_ASSERT(inp);
441 } else
442 inp = NULL;
443
444 if (tp != NULL) {
445 if (!(flags & TH_RST)) {
446 win = sbspace(&inp->inp_socket->so_rcv);
447 if (win > (long)TCP_MAXWIN << tp->rcv_scale)
448 win = (long)TCP_MAXWIN << tp->rcv_scale;
449 }
450 }
451 if (m == NULL) {
452 m = m_gethdr(M_DONTWAIT, MT_DATA);
453 if (m == NULL)
454 return;
455 tlen = 0;
456 m->m_data += max_linkhdr;
457 #ifdef INET6
458 if (isipv6) {
459 bcopy((caddr_t)ip6, mtod(m, caddr_t),
460 sizeof(struct ip6_hdr));
461 ip6 = mtod(m, struct ip6_hdr *);
462 nth = (struct tcphdr *)(ip6 + 1);
463 } else
464 #endif /* INET6 */
465 {
466 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
467 ip = mtod(m, struct ip *);
468 nth = (struct tcphdr *)(ip + 1);
469 }
470 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
471 flags = TH_ACK;
472 } else {
473 m_freem(m->m_next);
474 m->m_next = NULL;
475 m->m_data = (caddr_t)ipgen;
476 /* m_len is set later */
477 tlen = 0;
478 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
479 #ifdef INET6
480 if (isipv6) {
481 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
482 nth = (struct tcphdr *)(ip6 + 1);
483 } else
484 #endif /* INET6 */
485 {
486 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
487 nth = (struct tcphdr *)(ip + 1);
488 }
489 if (th != nth) {
490 /*
491 * this is usually a case when an extension header
492 * exists between the IPv6 header and the
493 * TCP header.
494 */
495 nth->th_sport = th->th_sport;
496 nth->th_dport = th->th_dport;
497 }
498 xchg(nth->th_dport, nth->th_sport, n_short);
499 #undef xchg
500 }
501 #ifdef INET6
502 if (isipv6) {
503 ip6->ip6_flow = 0;
504 ip6->ip6_vfc = IPV6_VERSION;
505 ip6->ip6_nxt = IPPROTO_TCP;
506 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
507 tlen));
508 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
509 } else
510 #endif
511 {
512 tlen += sizeof (struct tcpiphdr);
513 ip->ip_len = tlen;
514 ip->ip_ttl = ip_defttl;
515 if (path_mtu_discovery)
516 ip->ip_off |= IP_DF;
517 }
518 m->m_len = tlen;
519 m->m_pkthdr.len = tlen;
520 m->m_pkthdr.rcvif = NULL;
521 #ifdef MAC
522 if (inp != NULL) {
523 /*
524 * Packet is associated with a socket, so allow the
525 * label of the response to reflect the socket label.
526 */
527 INP_LOCK_ASSERT(inp);
528 mac_create_mbuf_from_inpcb(inp, m);
529 } else {
530 /*
531 * Packet is not associated with a socket, so possibly
532 * update the label in place.
533 */
534 mac_reflect_mbuf_tcp(m);
535 }
536 #endif
537 nth->th_seq = htonl(seq);
538 nth->th_ack = htonl(ack);
539 nth->th_x2 = 0;
540 nth->th_off = sizeof (struct tcphdr) >> 2;
541 nth->th_flags = flags;
542 if (tp != NULL)
543 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
544 else
545 nth->th_win = htons((u_short)win);
546 nth->th_urp = 0;
547 #ifdef INET6
548 if (isipv6) {
549 nth->th_sum = 0;
550 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
551 sizeof(struct ip6_hdr),
552 tlen - sizeof(struct ip6_hdr));
553 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
554 NULL, NULL);
555 } else
556 #endif /* INET6 */
557 {
558 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
559 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
560 m->m_pkthdr.csum_flags = CSUM_TCP;
561 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
562 }
563 #ifdef TCPDEBUG
564 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
565 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
566 #endif
567 #ifdef INET6
568 if (isipv6)
569 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp);
570 else
571 #endif /* INET6 */
572 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp);
573 }
574
575 /*
576 * Create a new TCP control block, making an
577 * empty reassembly queue and hooking it to the argument
578 * protocol control block. The `inp' parameter must have
579 * come from the zone allocator set up in tcp_init().
580 */
581 struct tcpcb *
582 tcp_newtcpcb(struct inpcb *inp)
583 {
584 struct tcpcb_mem *tm;
585 struct tcpcb *tp;
586 #ifdef INET6
587 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
588 #endif /* INET6 */
589
590 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO);
591 if (tm == NULL)
592 return (NULL);
593 tp = &tm->tcb;
594 tp->t_timers = &tm->tt;
595 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */
596 tp->t_maxseg = tp->t_maxopd =
597 #ifdef INET6
598 isipv6 ? tcp_v6mssdflt :
599 #endif /* INET6 */
600 tcp_mssdflt;
601
602 /* Set up our timeouts. */
603 callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE);
604 callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE);
605 callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE);
606 callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE);
607 callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE);
608
609 if (tcp_do_rfc1323)
610 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
611 if (tcp_do_sack)
612 tp->t_flags |= TF_SACK_PERMIT;
613 TAILQ_INIT(&tp->snd_holes);
614 tp->t_inpcb = inp; /* XXX */
615 /*
616 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
617 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
618 * reasonable initial retransmit time.
619 */
620 tp->t_srtt = TCPTV_SRTTBASE;
621 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
622 tp->t_rttmin = tcp_rexmit_min;
623 tp->t_rxtcur = TCPTV_RTOBASE;
624 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
625 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
626 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
627 tp->t_rcvtime = ticks;
628 tp->t_bw_rtttime = ticks;
629 /*
630 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
631 * because the socket may be bound to an IPv6 wildcard address,
632 * which may match an IPv4-mapped IPv6 address.
633 */
634 inp->inp_ip_ttl = ip_defttl;
635 inp->inp_ppcb = tp;
636 return (tp); /* XXX */
637 }
638
639 /*
640 * Drop a TCP connection, reporting
641 * the specified error. If connection is synchronized,
642 * then send a RST to peer.
643 */
644 struct tcpcb *
645 tcp_drop(struct tcpcb *tp, int errno)
646 {
647 struct socket *so = tp->t_inpcb->inp_socket;
648
649 INP_INFO_WLOCK_ASSERT(&tcbinfo);
650 INP_LOCK_ASSERT(tp->t_inpcb);
651
652 if (TCPS_HAVERCVDSYN(tp->t_state)) {
653 tp->t_state = TCPS_CLOSED;
654 (void) tcp_output(tp);
655 tcpstat.tcps_drops++;
656 } else
657 tcpstat.tcps_conndrops++;
658 if (errno == ETIMEDOUT && tp->t_softerror)
659 errno = tp->t_softerror;
660 so->so_error = errno;
661 return (tcp_close(tp));
662 }
663
664 void
665 tcp_discardcb(struct tcpcb *tp)
666 {
667 struct tseg_qent *q;
668 struct inpcb *inp = tp->t_inpcb;
669 struct socket *so = inp->inp_socket;
670 #ifdef INET6
671 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
672 #endif /* INET6 */
673
674 INP_LOCK_ASSERT(inp);
675
676 /*
677 * Make sure that all of our timers are stopped before we
678 * delete the PCB.
679 */
680 callout_stop(&tp->t_timers->tt_rexmt);
681 callout_stop(&tp->t_timers->tt_persist);
682 callout_stop(&tp->t_timers->tt_keep);
683 callout_stop(&tp->t_timers->tt_2msl);
684 callout_stop(&tp->t_timers->tt_delack);
685
686 /*
687 * If we got enough samples through the srtt filter,
688 * save the rtt and rttvar in the routing entry.
689 * 'Enough' is arbitrarily defined as 4 rtt samples.
690 * 4 samples is enough for the srtt filter to converge
691 * to within enough % of the correct value; fewer samples
692 * and we could save a bogus rtt. The danger is not high
693 * as tcp quickly recovers from everything.
694 * XXX: Works very well but needs some more statistics!
695 */
696 if (tp->t_rttupdated >= 4) {
697 struct hc_metrics_lite metrics;
698 u_long ssthresh;
699
700 bzero(&metrics, sizeof(metrics));
701 /*
702 * Update the ssthresh always when the conditions below
703 * are satisfied. This gives us better new start value
704 * for the congestion avoidance for new connections.
705 * ssthresh is only set if packet loss occured on a session.
706 *
707 * XXXRW: 'so' may be NULL here, and/or socket buffer may be
708 * being torn down. Ideally this code would not use 'so'.
709 */
710 ssthresh = tp->snd_ssthresh;
711 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
712 /*
713 * convert the limit from user data bytes to
714 * packets then to packet data bytes.
715 */
716 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
717 if (ssthresh < 2)
718 ssthresh = 2;
719 ssthresh *= (u_long)(tp->t_maxseg +
720 #ifdef INET6
721 (isipv6 ? sizeof (struct ip6_hdr) +
722 sizeof (struct tcphdr) :
723 #endif
724 sizeof (struct tcpiphdr)
725 #ifdef INET6
726 )
727 #endif
728 );
729 } else
730 ssthresh = 0;
731 metrics.rmx_ssthresh = ssthresh;
732
733 metrics.rmx_rtt = tp->t_srtt;
734 metrics.rmx_rttvar = tp->t_rttvar;
735 /* XXX: This wraps if the pipe is more than 4 Gbit per second */
736 metrics.rmx_bandwidth = tp->snd_bandwidth;
737 metrics.rmx_cwnd = tp->snd_cwnd;
738 metrics.rmx_sendpipe = 0;
739 metrics.rmx_recvpipe = 0;
740
741 tcp_hc_update(&inp->inp_inc, &metrics);
742 }
743
744 /* free the reassembly queue, if any */
745 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) {
746 LIST_REMOVE(q, tqe_q);
747 m_freem(q->tqe_m);
748 uma_zfree(tcp_reass_zone, q);
749 tp->t_segqlen--;
750 tcp_reass_qsize--;
751 }
752 tcp_free_sackholes(tp);
753 inp->inp_ppcb = NULL;
754 tp->t_inpcb = NULL;
755 uma_zfree(tcpcb_zone, tp);
756 }
757
758 /*
759 * Attempt to close a TCP control block, marking it as dropped, and freeing
760 * the socket if we hold the only reference.
761 */
762 struct tcpcb *
763 tcp_close(struct tcpcb *tp)
764 {
765 struct inpcb *inp = tp->t_inpcb;
766 struct socket *so;
767
768 INP_INFO_WLOCK_ASSERT(&tcbinfo);
769 INP_LOCK_ASSERT(inp);
770
771 in_pcbdrop(inp);
772 tcpstat.tcps_closed++;
773 KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
774 so = inp->inp_socket;
775 soisdisconnected(so);
776 if (inp->inp_vflag & INP_SOCKREF) {
777 KASSERT(so->so_state & SS_PROTOREF,
778 ("tcp_close: !SS_PROTOREF"));
779 inp->inp_vflag &= ~INP_SOCKREF;
780 INP_UNLOCK(inp);
781 ACCEPT_LOCK();
782 SOCK_LOCK(so);
783 so->so_state &= ~SS_PROTOREF;
784 sofree(so);
785 return (NULL);
786 }
787 return (tp);
788 }
789
790 void
791 tcp_drain(void)
792 {
793
794 if (do_tcpdrain) {
795 struct inpcb *inpb;
796 struct tcpcb *tcpb;
797 struct tseg_qent *te;
798
799 /*
800 * Walk the tcpbs, if existing, and flush the reassembly queue,
801 * if there is one...
802 * XXX: The "Net/3" implementation doesn't imply that the TCP
803 * reassembly queue should be flushed, but in a situation
804 * where we're really low on mbufs, this is potentially
805 * usefull.
806 */
807 INP_INFO_RLOCK(&tcbinfo);
808 LIST_FOREACH(inpb, tcbinfo.ipi_listhead, inp_list) {
809 if (inpb->inp_vflag & INP_TIMEWAIT)
810 continue;
811 INP_LOCK(inpb);
812 if ((tcpb = intotcpcb(inpb)) != NULL) {
813 while ((te = LIST_FIRST(&tcpb->t_segq))
814 != NULL) {
815 LIST_REMOVE(te, tqe_q);
816 m_freem(te->tqe_m);
817 uma_zfree(tcp_reass_zone, te);
818 tcpb->t_segqlen--;
819 tcp_reass_qsize--;
820 }
821 tcp_clean_sackreport(tcpb);
822 }
823 INP_UNLOCK(inpb);
824 }
825 INP_INFO_RUNLOCK(&tcbinfo);
826 }
827 }
828
829 /*
830 * Notify a tcp user of an asynchronous error;
831 * store error as soft error, but wake up user
832 * (for now, won't do anything until can select for soft error).
833 *
834 * Do not wake up user since there currently is no mechanism for
835 * reporting soft errors (yet - a kqueue filter may be added).
836 */
837 static struct inpcb *
838 tcp_notify(struct inpcb *inp, int error)
839 {
840 struct tcpcb *tp;
841
842 INP_INFO_WLOCK_ASSERT(&tcbinfo);
843 INP_LOCK_ASSERT(inp);
844
845 if ((inp->inp_vflag & INP_TIMEWAIT) ||
846 (inp->inp_vflag & INP_DROPPED))
847 return (inp);
848
849 tp = intotcpcb(inp);
850 KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
851
852 /*
853 * Ignore some errors if we are hooked up.
854 * If connection hasn't completed, has retransmitted several times,
855 * and receives a second error, give up now. This is better
856 * than waiting a long time to establish a connection that
857 * can never complete.
858 */
859 if (tp->t_state == TCPS_ESTABLISHED &&
860 (error == EHOSTUNREACH || error == ENETUNREACH ||
861 error == EHOSTDOWN)) {
862 return (inp);
863 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
864 tp->t_softerror) {
865 tp = tcp_drop(tp, error);
866 if (tp != NULL)
867 return (inp);
868 else
869 return (NULL);
870 } else {
871 tp->t_softerror = error;
872 return (inp);
873 }
874 #if 0
875 wakeup( &so->so_timeo);
876 sorwakeup(so);
877 sowwakeup(so);
878 #endif
879 }
880
881 static int
882 tcp_pcblist(SYSCTL_HANDLER_ARGS)
883 {
884 int error, i, m, n, pcb_count;
885 struct inpcb *inp, **inp_list;
886 inp_gen_t gencnt;
887 struct xinpgen xig;
888
889 /*
890 * The process of preparing the TCB list is too time-consuming and
891 * resource-intensive to repeat twice on every request.
892 */
893 if (req->oldptr == NULL) {
894 m = syncache_pcbcount();
895 n = tcbinfo.ipi_count;
896 req->oldidx = 2 * (sizeof xig)
897 + ((m + n) + n/8) * sizeof(struct xtcpcb);
898 return (0);
899 }
900
901 if (req->newptr != NULL)
902 return (EPERM);
903
904 /*
905 * OK, now we're committed to doing something.
906 */
907 INP_INFO_RLOCK(&tcbinfo);
908 gencnt = tcbinfo.ipi_gencnt;
909 n = tcbinfo.ipi_count;
910 INP_INFO_RUNLOCK(&tcbinfo);
911
912 m = syncache_pcbcount();
913
914 error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
915 + (n + m) * sizeof(struct xtcpcb));
916 if (error != 0)
917 return (error);
918
919 xig.xig_len = sizeof xig;
920 xig.xig_count = n + m;
921 xig.xig_gen = gencnt;
922 xig.xig_sogen = so_gencnt;
923 error = SYSCTL_OUT(req, &xig, sizeof xig);
924 if (error)
925 return (error);
926
927 error = syncache_pcblist(req, m, &pcb_count);
928 if (error)
929 return (error);
930
931 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
932 if (inp_list == NULL)
933 return (ENOMEM);
934
935 INP_INFO_RLOCK(&tcbinfo);
936 for (inp = LIST_FIRST(tcbinfo.ipi_listhead), i = 0; inp != NULL && i
937 < n; inp = LIST_NEXT(inp, inp_list)) {
938 INP_LOCK(inp);
939 if (inp->inp_gencnt <= gencnt) {
940 /*
941 * XXX: This use of cr_cansee(), introduced with
942 * TCP state changes, is not quite right, but for
943 * now, better than nothing.
944 */
945 if (inp->inp_vflag & INP_TIMEWAIT) {
946 if (intotw(inp) != NULL)
947 error = cr_cansee(req->td->td_ucred,
948 intotw(inp)->tw_cred);
949 else
950 error = EINVAL; /* Skip this inp. */
951 } else
952 error = cr_canseesocket(req->td->td_ucred,
953 inp->inp_socket);
954 if (error == 0)
955 inp_list[i++] = inp;
956 }
957 INP_UNLOCK(inp);
958 }
959 INP_INFO_RUNLOCK(&tcbinfo);
960 n = i;
961
962 error = 0;
963 for (i = 0; i < n; i++) {
964 inp = inp_list[i];
965 INP_LOCK(inp);
966 if (inp->inp_gencnt <= gencnt) {
967 struct xtcpcb xt;
968 void *inp_ppcb;
969
970 bzero(&xt, sizeof(xt));
971 xt.xt_len = sizeof xt;
972 /* XXX should avoid extra copy */
973 bcopy(inp, &xt.xt_inp, sizeof *inp);
974 inp_ppcb = inp->inp_ppcb;
975 if (inp_ppcb == NULL)
976 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
977 else if (inp->inp_vflag & INP_TIMEWAIT) {
978 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
979 xt.xt_tp.t_state = TCPS_TIME_WAIT;
980 } else
981 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
982 if (inp->inp_socket != NULL)
983 sotoxsocket(inp->inp_socket, &xt.xt_socket);
984 else {
985 bzero(&xt.xt_socket, sizeof xt.xt_socket);
986 xt.xt_socket.xso_protocol = IPPROTO_TCP;
987 }
988 xt.xt_inp.inp_gencnt = inp->inp_gencnt;
989 INP_UNLOCK(inp);
990 error = SYSCTL_OUT(req, &xt, sizeof xt);
991 } else
992 INP_UNLOCK(inp);
993
994 }
995 if (!error) {
996 /*
997 * Give the user an updated idea of our state.
998 * If the generation differs from what we told
999 * her before, she knows that something happened
1000 * while we were processing this request, and it
1001 * might be necessary to retry.
1002 */
1003 INP_INFO_RLOCK(&tcbinfo);
1004 xig.xig_gen = tcbinfo.ipi_gencnt;
1005 xig.xig_sogen = so_gencnt;
1006 xig.xig_count = tcbinfo.ipi_count + pcb_count;
1007 INP_INFO_RUNLOCK(&tcbinfo);
1008 error = SYSCTL_OUT(req, &xig, sizeof xig);
1009 }
1010 free(inp_list, M_TEMP);
1011 return (error);
1012 }
1013
1014 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
1015 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1016
1017 static int
1018 tcp_getcred(SYSCTL_HANDLER_ARGS)
1019 {
1020 struct xucred xuc;
1021 struct sockaddr_in addrs[2];
1022 struct inpcb *inp;
1023 int error;
1024
1025 error = priv_check(req->td, PRIV_NETINET_GETCRED);
1026 if (error)
1027 return (error);
1028 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1029 if (error)
1030 return (error);
1031 INP_INFO_RLOCK(&tcbinfo);
1032 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
1033 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
1034 if (inp == NULL) {
1035 error = ENOENT;
1036 goto outunlocked;
1037 }
1038 INP_LOCK(inp);
1039 if (inp->inp_socket == NULL) {
1040 error = ENOENT;
1041 goto out;
1042 }
1043 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1044 if (error)
1045 goto out;
1046 cru2x(inp->inp_socket->so_cred, &xuc);
1047 out:
1048 INP_UNLOCK(inp);
1049 outunlocked:
1050 INP_INFO_RUNLOCK(&tcbinfo);
1051 if (error == 0)
1052 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1053 return (error);
1054 }
1055
1056 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
1057 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1058 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
1059
1060 #ifdef INET6
1061 static int
1062 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1063 {
1064 struct xucred xuc;
1065 struct sockaddr_in6 addrs[2];
1066 struct inpcb *inp;
1067 int error, mapped = 0;
1068
1069 error = priv_check(req->td, PRIV_NETINET_GETCRED);
1070 if (error)
1071 return (error);
1072 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1073 if (error)
1074 return (error);
1075 if ((error = sa6_embedscope(&addrs[0], ip6_use_defzone)) != 0 ||
1076 (error = sa6_embedscope(&addrs[1], ip6_use_defzone)) != 0) {
1077 return (error);
1078 }
1079 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1080 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1081 mapped = 1;
1082 else
1083 return (EINVAL);
1084 }
1085
1086 INP_INFO_RLOCK(&tcbinfo);
1087 if (mapped == 1)
1088 inp = in_pcblookup_hash(&tcbinfo,
1089 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1090 addrs[1].sin6_port,
1091 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1092 addrs[0].sin6_port,
1093 0, NULL);
1094 else
1095 inp = in6_pcblookup_hash(&tcbinfo,
1096 &addrs[1].sin6_addr, addrs[1].sin6_port,
1097 &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL);
1098 if (inp == NULL) {
1099 error = ENOENT;
1100 goto outunlocked;
1101 }
1102 INP_LOCK(inp);
1103 if (inp->inp_socket == NULL) {
1104 error = ENOENT;
1105 goto out;
1106 }
1107 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1108 if (error)
1109 goto out;
1110 cru2x(inp->inp_socket->so_cred, &xuc);
1111 out:
1112 INP_UNLOCK(inp);
1113 outunlocked:
1114 INP_INFO_RUNLOCK(&tcbinfo);
1115 if (error == 0)
1116 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1117 return (error);
1118 }
1119
1120 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
1121 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1122 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
1123 #endif
1124
1125
1126 void
1127 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
1128 {
1129 struct ip *ip = vip;
1130 struct tcphdr *th;
1131 struct in_addr faddr;
1132 struct inpcb *inp;
1133 struct tcpcb *tp;
1134 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1135 struct icmp *icp;
1136 struct in_conninfo inc;
1137 tcp_seq icmp_tcp_seq;
1138 int mtu;
1139
1140 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1141 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1142 return;
1143
1144 if (cmd == PRC_MSGSIZE)
1145 notify = tcp_mtudisc;
1146 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1147 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
1148 notify = tcp_drop_syn_sent;
1149 /*
1150 * Redirects don't need to be handled up here.
1151 */
1152 else if (PRC_IS_REDIRECT(cmd))
1153 return;
1154 /*
1155 * Source quench is depreciated.
1156 */
1157 else if (cmd == PRC_QUENCH)
1158 return;
1159 /*
1160 * Hostdead is ugly because it goes linearly through all PCBs.
1161 * XXX: We never get this from ICMP, otherwise it makes an
1162 * excellent DoS attack on machines with many connections.
1163 */
1164 else if (cmd == PRC_HOSTDEAD)
1165 ip = NULL;
1166 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
1167 return;
1168 if (ip != NULL) {
1169 icp = (struct icmp *)((caddr_t)ip
1170 - offsetof(struct icmp, icmp_ip));
1171 th = (struct tcphdr *)((caddr_t)ip
1172 + (ip->ip_hl << 2));
1173 INP_INFO_WLOCK(&tcbinfo);
1174 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport,
1175 ip->ip_src, th->th_sport, 0, NULL);
1176 if (inp != NULL) {
1177 INP_LOCK(inp);
1178 if (!(inp->inp_vflag & INP_TIMEWAIT) &&
1179 !(inp->inp_vflag & INP_DROPPED) &&
1180 !(inp->inp_socket == NULL)) {
1181 icmp_tcp_seq = htonl(th->th_seq);
1182 tp = intotcpcb(inp);
1183 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
1184 SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
1185 if (cmd == PRC_MSGSIZE) {
1186 /*
1187 * MTU discovery:
1188 * If we got a needfrag set the MTU
1189 * in the route to the suggested new
1190 * value (if given) and then notify.
1191 */
1192 bzero(&inc, sizeof(inc));
1193 inc.inc_flags = 0; /* IPv4 */
1194 inc.inc_faddr = faddr;
1195
1196 mtu = ntohs(icp->icmp_nextmtu);
1197 /*
1198 * If no alternative MTU was
1199 * proposed, try the next smaller
1200 * one. ip->ip_len has already
1201 * been swapped in icmp_input().
1202 */
1203 if (!mtu)
1204 mtu = ip_next_mtu(ip->ip_len,
1205 1);
1206 if (mtu < max(296, (tcp_minmss)
1207 + sizeof(struct tcpiphdr)))
1208 mtu = 0;
1209 if (!mtu)
1210 mtu = tcp_mssdflt
1211 + sizeof(struct tcpiphdr);
1212 /*
1213 * Only cache the the MTU if it
1214 * is smaller than the interface
1215 * or route MTU. tcp_mtudisc()
1216 * will do right thing by itself.
1217 */
1218 if (mtu <= tcp_maxmtu(&inc, NULL))
1219 tcp_hc_updatemtu(&inc, mtu);
1220 }
1221
1222 inp = (*notify)(inp, inetctlerrmap[cmd]);
1223 }
1224 }
1225 if (inp != NULL)
1226 INP_UNLOCK(inp);
1227 } else {
1228 inc.inc_fport = th->th_dport;
1229 inc.inc_lport = th->th_sport;
1230 inc.inc_faddr = faddr;
1231 inc.inc_laddr = ip->ip_src;
1232 #ifdef INET6
1233 inc.inc_isipv6 = 0;
1234 #endif
1235 syncache_unreach(&inc, th);
1236 }
1237 INP_INFO_WUNLOCK(&tcbinfo);
1238 } else
1239 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify);
1240 }
1241
1242 #ifdef INET6
1243 void
1244 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
1245 {
1246 struct tcphdr th;
1247 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1248 struct ip6_hdr *ip6;
1249 struct mbuf *m;
1250 struct ip6ctlparam *ip6cp = NULL;
1251 const struct sockaddr_in6 *sa6_src = NULL;
1252 int off;
1253 struct tcp_portonly {
1254 u_int16_t th_sport;
1255 u_int16_t th_dport;
1256 } *thp;
1257
1258 if (sa->sa_family != AF_INET6 ||
1259 sa->sa_len != sizeof(struct sockaddr_in6))
1260 return;
1261
1262 if (cmd == PRC_MSGSIZE)
1263 notify = tcp_mtudisc;
1264 else if (!PRC_IS_REDIRECT(cmd) &&
1265 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
1266 return;
1267 /* Source quench is depreciated. */
1268 else if (cmd == PRC_QUENCH)
1269 return;
1270
1271 /* if the parameter is from icmp6, decode it. */
1272 if (d != NULL) {
1273 ip6cp = (struct ip6ctlparam *)d;
1274 m = ip6cp->ip6c_m;
1275 ip6 = ip6cp->ip6c_ip6;
1276 off = ip6cp->ip6c_off;
1277 sa6_src = ip6cp->ip6c_src;
1278 } else {
1279 m = NULL;
1280 ip6 = NULL;
1281 off = 0; /* fool gcc */
1282 sa6_src = &sa6_any;
1283 }
1284
1285 if (ip6 != NULL) {
1286 struct in_conninfo inc;
1287 /*
1288 * XXX: We assume that when IPV6 is non NULL,
1289 * M and OFF are valid.
1290 */
1291
1292 /* check if we can safely examine src and dst ports */
1293 if (m->m_pkthdr.len < off + sizeof(*thp))
1294 return;
1295
1296 bzero(&th, sizeof(th));
1297 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
1298
1299 in6_pcbnotify(&tcbinfo, sa, th.th_dport,
1300 (struct sockaddr *)ip6cp->ip6c_src,
1301 th.th_sport, cmd, NULL, notify);
1302
1303 inc.inc_fport = th.th_dport;
1304 inc.inc_lport = th.th_sport;
1305 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
1306 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
1307 inc.inc_isipv6 = 1;
1308 INP_INFO_WLOCK(&tcbinfo);
1309 syncache_unreach(&inc, &th);
1310 INP_INFO_WUNLOCK(&tcbinfo);
1311 } else
1312 in6_pcbnotify(&tcbinfo, sa, 0, (const struct sockaddr *)sa6_src,
1313 0, cmd, NULL, notify);
1314 }
1315 #endif /* INET6 */
1316
1317
1318 /*
1319 * Following is where TCP initial sequence number generation occurs.
1320 *
1321 * There are two places where we must use initial sequence numbers:
1322 * 1. In SYN-ACK packets.
1323 * 2. In SYN packets.
1324 *
1325 * All ISNs for SYN-ACK packets are generated by the syncache. See
1326 * tcp_syncache.c for details.
1327 *
1328 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
1329 * depends on this property. In addition, these ISNs should be
1330 * unguessable so as to prevent connection hijacking. To satisfy
1331 * the requirements of this situation, the algorithm outlined in
1332 * RFC 1948 is used, with only small modifications.
1333 *
1334 * Implementation details:
1335 *
1336 * Time is based off the system timer, and is corrected so that it
1337 * increases by one megabyte per second. This allows for proper
1338 * recycling on high speed LANs while still leaving over an hour
1339 * before rollover.
1340 *
1341 * As reading the *exact* system time is too expensive to be done
1342 * whenever setting up a TCP connection, we increment the time
1343 * offset in two ways. First, a small random positive increment
1344 * is added to isn_offset for each connection that is set up.
1345 * Second, the function tcp_isn_tick fires once per clock tick
1346 * and increments isn_offset as necessary so that sequence numbers
1347 * are incremented at approximately ISN_BYTES_PER_SECOND. The
1348 * random positive increments serve only to ensure that the same
1349 * exact sequence number is never sent out twice (as could otherwise
1350 * happen when a port is recycled in less than the system tick
1351 * interval.)
1352 *
1353 * net.inet.tcp.isn_reseed_interval controls the number of seconds
1354 * between seeding of isn_secret. This is normally set to zero,
1355 * as reseeding should not be necessary.
1356 *
1357 * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
1358 * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock. In
1359 * general, this means holding an exclusive (write) lock.
1360 */
1361
1362 #define ISN_BYTES_PER_SECOND 1048576
1363 #define ISN_STATIC_INCREMENT 4096
1364 #define ISN_RANDOM_INCREMENT (4096 - 1)
1365
1366 static u_char isn_secret[32];
1367 static int isn_last_reseed;
1368 static u_int32_t isn_offset, isn_offset_old;
1369 static MD5_CTX isn_ctx;
1370
1371 tcp_seq
1372 tcp_new_isn(struct tcpcb *tp)
1373 {
1374 u_int32_t md5_buffer[4];
1375 tcp_seq new_isn;
1376
1377 INP_LOCK_ASSERT(tp->t_inpcb);
1378
1379 ISN_LOCK();
1380 /* Seed if this is the first use, reseed if requested. */
1381 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) &&
1382 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
1383 < (u_int)ticks))) {
1384 read_random(&isn_secret, sizeof(isn_secret));
1385 isn_last_reseed = ticks;
1386 }
1387
1388 /* Compute the md5 hash and return the ISN. */
1389 MD5Init(&isn_ctx);
1390 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
1391 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
1392 #ifdef INET6
1393 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
1394 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
1395 sizeof(struct in6_addr));
1396 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
1397 sizeof(struct in6_addr));
1398 } else
1399 #endif
1400 {
1401 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
1402 sizeof(struct in_addr));
1403 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
1404 sizeof(struct in_addr));
1405 }
1406 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
1407 MD5Final((u_char *) &md5_buffer, &isn_ctx);
1408 new_isn = (tcp_seq) md5_buffer[0];
1409 isn_offset += ISN_STATIC_INCREMENT +
1410 (arc4random() & ISN_RANDOM_INCREMENT);
1411 new_isn += isn_offset;
1412 ISN_UNLOCK();
1413 return (new_isn);
1414 }
1415
1416 /*
1417 * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary
1418 * to keep time flowing at a relatively constant rate. If the random
1419 * increments have already pushed us past the projected offset, do nothing.
1420 */
1421 static void
1422 tcp_isn_tick(void *xtp)
1423 {
1424 u_int32_t projected_offset;
1425
1426 ISN_LOCK();
1427 projected_offset = isn_offset_old + ISN_BYTES_PER_SECOND / 100;
1428
1429 if (SEQ_GT(projected_offset, isn_offset))
1430 isn_offset = projected_offset;
1431
1432 isn_offset_old = isn_offset;
1433 callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL);
1434 ISN_UNLOCK();
1435 }
1436
1437 /*
1438 * When a specific ICMP unreachable message is received and the
1439 * connection state is SYN-SENT, drop the connection. This behavior
1440 * is controlled by the icmp_may_rst sysctl.
1441 */
1442 struct inpcb *
1443 tcp_drop_syn_sent(struct inpcb *inp, int errno)
1444 {
1445 struct tcpcb *tp;
1446
1447 INP_INFO_WLOCK_ASSERT(&tcbinfo);
1448 INP_LOCK_ASSERT(inp);
1449
1450 if ((inp->inp_vflag & INP_TIMEWAIT) ||
1451 (inp->inp_vflag & INP_DROPPED))
1452 return (inp);
1453
1454 tp = intotcpcb(inp);
1455 if (tp->t_state != TCPS_SYN_SENT)
1456 return (inp);
1457
1458 tp = tcp_drop(tp, errno);
1459 if (tp != NULL)
1460 return (inp);
1461 else
1462 return (NULL);
1463 }
1464
1465 /*
1466 * When `need fragmentation' ICMP is received, update our idea of the MSS
1467 * based on the new value in the route. Also nudge TCP to send something,
1468 * since we know the packet we just sent was dropped.
1469 * This duplicates some code in the tcp_mss() function in tcp_input.c.
1470 */
1471 struct inpcb *
1472 tcp_mtudisc(struct inpcb *inp, int errno)
1473 {
1474 struct tcpcb *tp;
1475 struct socket *so = inp->inp_socket;
1476 u_int maxmtu;
1477 u_int romtu;
1478 int mss;
1479 #ifdef INET6
1480 int isipv6;
1481 #endif /* INET6 */
1482
1483 INP_LOCK_ASSERT(inp);
1484 if ((inp->inp_vflag & INP_TIMEWAIT) ||
1485 (inp->inp_vflag & INP_DROPPED))
1486 return (inp);
1487
1488 tp = intotcpcb(inp);
1489 KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
1490
1491 #ifdef INET6
1492 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
1493 #endif
1494 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */
1495 romtu =
1496 #ifdef INET6
1497 isipv6 ? tcp_maxmtu6(&inp->inp_inc, NULL) :
1498 #endif /* INET6 */
1499 tcp_maxmtu(&inp->inp_inc, NULL);
1500 if (!maxmtu)
1501 maxmtu = romtu;
1502 else
1503 maxmtu = min(maxmtu, romtu);
1504 if (!maxmtu) {
1505 tp->t_maxopd = tp->t_maxseg =
1506 #ifdef INET6
1507 isipv6 ? tcp_v6mssdflt :
1508 #endif /* INET6 */
1509 tcp_mssdflt;
1510 return (inp);
1511 }
1512 mss = maxmtu -
1513 #ifdef INET6
1514 (isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1515 #endif /* INET6 */
1516 sizeof(struct tcpiphdr)
1517 #ifdef INET6
1518 )
1519 #endif /* INET6 */
1520 ;
1521
1522 /*
1523 * XXX - The above conditional probably violates the TCP
1524 * spec. The problem is that, since we don't know the
1525 * other end's MSS, we are supposed to use a conservative
1526 * default. But, if we do that, then MTU discovery will
1527 * never actually take place, because the conservative
1528 * default is much less than the MTUs typically seen
1529 * on the Internet today. For the moment, we'll sweep
1530 * this under the carpet.
1531 *
1532 * The conservative default might not actually be a problem
1533 * if the only case this occurs is when sending an initial
1534 * SYN with options and data to a host we've never talked
1535 * to before. Then, they will reply with an MSS value which
1536 * will get recorded and the new parameters should get
1537 * recomputed. For Further Study.
1538 */
1539 if (tp->t_maxopd <= mss)
1540 return (inp);
1541 tp->t_maxopd = mss;
1542
1543 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
1544 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
1545 mss -= TCPOLEN_TSTAMP_APPA;
1546 #if (MCLBYTES & (MCLBYTES - 1)) == 0
1547 if (mss > MCLBYTES)
1548 mss &= ~(MCLBYTES-1);
1549 #else
1550 if (mss > MCLBYTES)
1551 mss = mss / MCLBYTES * MCLBYTES;
1552 #endif
1553 if (so->so_snd.sb_hiwat < mss)
1554 mss = so->so_snd.sb_hiwat;
1555
1556 tp->t_maxseg = mss;
1557
1558 tcpstat.tcps_mturesent++;
1559 tp->t_rtttime = 0;
1560 tp->snd_nxt = tp->snd_una;
1561 tcp_free_sackholes(tp);
1562 tp->snd_recover = tp->snd_max;
1563 if (tp->t_flags & TF_SACK_PERMIT)
1564 EXIT_FASTRECOVERY(tp);
1565 tcp_output(tp);
1566 return (inp);
1567 }
1568
1569 /*
1570 * Look-up the routing entry to the peer of this inpcb. If no route
1571 * is found and it cannot be allocated, then return NULL. This routine
1572 * is called by TCP routines that access the rmx structure and by tcp_mss
1573 * to get the interface MTU.
1574 */
1575 u_long
1576 tcp_maxmtu(struct in_conninfo *inc, int *flags)
1577 {
1578 struct route sro;
1579 struct sockaddr_in *dst;
1580 struct ifnet *ifp;
1581 u_long maxmtu = 0;
1582
1583 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
1584
1585 bzero(&sro, sizeof(sro));
1586 if (inc->inc_faddr.s_addr != INADDR_ANY) {
1587 dst = (struct sockaddr_in *)&sro.ro_dst;
1588 dst->sin_family = AF_INET;
1589 dst->sin_len = sizeof(*dst);
1590 dst->sin_addr = inc->inc_faddr;
1591 rtalloc_ign(&sro, RTF_CLONING);
1592 }
1593 if (sro.ro_rt != NULL) {
1594 ifp = sro.ro_rt->rt_ifp;
1595 if (sro.ro_rt->rt_rmx.rmx_mtu == 0)
1596 maxmtu = ifp->if_mtu;
1597 else
1598 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
1599
1600 /* Report additional interface capabilities. */
1601 if (flags != NULL) {
1602 if (ifp->if_capenable & IFCAP_TSO4 &&
1603 ifp->if_hwassist & CSUM_TSO)
1604 *flags |= CSUM_TSO;
1605 }
1606 RTFREE(sro.ro_rt);
1607 }
1608 return (maxmtu);
1609 }
1610
1611 #ifdef INET6
1612 u_long
1613 tcp_maxmtu6(struct in_conninfo *inc, int *flags)
1614 {
1615 struct route_in6 sro6;
1616 struct ifnet *ifp;
1617 u_long maxmtu = 0;
1618
1619 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
1620
1621 bzero(&sro6, sizeof(sro6));
1622 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
1623 sro6.ro_dst.sin6_family = AF_INET6;
1624 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
1625 sro6.ro_dst.sin6_addr = inc->inc6_faddr;
1626 rtalloc_ign((struct route *)&sro6, RTF_CLONING);
1627 }
1628 if (sro6.ro_rt != NULL) {
1629 ifp = sro6.ro_rt->rt_ifp;
1630 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0)
1631 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp);
1632 else
1633 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu,
1634 IN6_LINKMTU(sro6.ro_rt->rt_ifp));
1635
1636 /* Report additional interface capabilities. */
1637 if (flags != NULL) {
1638 if (ifp->if_capenable & IFCAP_TSO6 &&
1639 ifp->if_hwassist & CSUM_TSO)
1640 *flags |= CSUM_TSO;
1641 }
1642 RTFREE(sro6.ro_rt);
1643 }
1644
1645 return (maxmtu);
1646 }
1647 #endif /* INET6 */
1648
1649 #ifdef IPSEC
1650 /* compute ESP/AH header size for TCP, including outer IP header. */
1651 size_t
1652 ipsec_hdrsiz_tcp(struct tcpcb *tp)
1653 {
1654 struct inpcb *inp;
1655 struct mbuf *m;
1656 size_t hdrsiz;
1657 struct ip *ip;
1658 #ifdef INET6
1659 struct ip6_hdr *ip6;
1660 #endif
1661 struct tcphdr *th;
1662
1663 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1664 return (0);
1665 MGETHDR(m, M_DONTWAIT, MT_DATA);
1666 if (!m)
1667 return (0);
1668
1669 #ifdef INET6
1670 if ((inp->inp_vflag & INP_IPV6) != 0) {
1671 ip6 = mtod(m, struct ip6_hdr *);
1672 th = (struct tcphdr *)(ip6 + 1);
1673 m->m_pkthdr.len = m->m_len =
1674 sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1675 tcpip_fillheaders(inp, ip6, th);
1676 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1677 } else
1678 #endif /* INET6 */
1679 {
1680 ip = mtod(m, struct ip *);
1681 th = (struct tcphdr *)(ip + 1);
1682 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
1683 tcpip_fillheaders(inp, ip, th);
1684 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1685 }
1686
1687 m_free(m);
1688 return (hdrsiz);
1689 }
1690 #endif /* IPSEC */
1691
1692 /*
1693 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
1694 *
1695 * This code attempts to calculate the bandwidth-delay product as a
1696 * means of determining the optimal window size to maximize bandwidth,
1697 * minimize RTT, and avoid the over-allocation of buffers on interfaces and
1698 * routers. This code also does a fairly good job keeping RTTs in check
1699 * across slow links like modems. We implement an algorithm which is very
1700 * similar (but not meant to be) TCP/Vegas. The code operates on the
1701 * transmitter side of a TCP connection and so only effects the transmit
1702 * side of the connection.
1703 *
1704 * BACKGROUND: TCP makes no provision for the management of buffer space
1705 * at the end points or at the intermediate routers and switches. A TCP
1706 * stream, whether using NewReno or not, will eventually buffer as
1707 * many packets as it is able and the only reason this typically works is
1708 * due to the fairly small default buffers made available for a connection
1709 * (typicaly 16K or 32K). As machines use larger windows and/or window
1710 * scaling it is now fairly easy for even a single TCP connection to blow-out
1711 * all available buffer space not only on the local interface, but on
1712 * intermediate routers and switches as well. NewReno makes a misguided
1713 * attempt to 'solve' this problem by waiting for an actual failure to occur,
1714 * then backing off, then steadily increasing the window again until another
1715 * failure occurs, ad-infinitum. This results in terrible oscillation that
1716 * is only made worse as network loads increase and the idea of intentionally
1717 * blowing out network buffers is, frankly, a terrible way to manage network
1718 * resources.
1719 *
1720 * It is far better to limit the transmit window prior to the failure
1721 * condition being achieved. There are two general ways to do this: First
1722 * you can 'scan' through different transmit window sizes and locate the
1723 * point where the RTT stops increasing, indicating that you have filled the
1724 * pipe, then scan backwards until you note that RTT stops decreasing, then
1725 * repeat ad-infinitum. This method works in principle but has severe
1726 * implementation issues due to RTT variances, timer granularity, and
1727 * instability in the algorithm which can lead to many false positives and
1728 * create oscillations as well as interact badly with other TCP streams
1729 * implementing the same algorithm.
1730 *
1731 * The second method is to limit the window to the bandwidth delay product
1732 * of the link. This is the method we implement. RTT variances and our
1733 * own manipulation of the congestion window, bwnd, can potentially
1734 * destabilize the algorithm. For this reason we have to stabilize the
1735 * elements used to calculate the window. We do this by using the minimum
1736 * observed RTT, the long term average of the observed bandwidth, and
1737 * by adding two segments worth of slop. It isn't perfect but it is able
1738 * to react to changing conditions and gives us a very stable basis on
1739 * which to extend the algorithm.
1740 */
1741 void
1742 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1743 {
1744 u_long bw;
1745 u_long bwnd;
1746 int save_ticks;
1747
1748 INP_LOCK_ASSERT(tp->t_inpcb);
1749
1750 /*
1751 * If inflight_enable is disabled in the middle of a tcp connection,
1752 * make sure snd_bwnd is effectively disabled.
1753 */
1754 if (tcp_inflight_enable == 0 || tp->t_rttlow < tcp_inflight_rttthresh) {
1755 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1756 tp->snd_bandwidth = 0;
1757 return;
1758 }
1759
1760 /*
1761 * Figure out the bandwidth. Due to the tick granularity this
1762 * is a very rough number and it MUST be averaged over a fairly
1763 * long period of time. XXX we need to take into account a link
1764 * that is not using all available bandwidth, but for now our
1765 * slop will ramp us up if this case occurs and the bandwidth later
1766 * increases.
1767 *
1768 * Note: if ticks rollover 'bw' may wind up negative. We must
1769 * effectively reset t_bw_rtttime for this case.
1770 */
1771 save_ticks = ticks;
1772 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
1773 return;
1774
1775 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz /
1776 (save_ticks - tp->t_bw_rtttime);
1777 tp->t_bw_rtttime = save_ticks;
1778 tp->t_bw_rtseq = ack_seq;
1779 if (tp->t_bw_rtttime == 0 || (int)bw < 0)
1780 return;
1781 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1782
1783 tp->snd_bandwidth = bw;
1784
1785 /*
1786 * Calculate the semi-static bandwidth delay product, plus two maximal
1787 * segments. The additional slop puts us squarely in the sweet
1788 * spot and also handles the bandwidth run-up case and stabilization.
1789 * Without the slop we could be locking ourselves into a lower
1790 * bandwidth.
1791 *
1792 * Situations Handled:
1793 * (1) Prevents over-queueing of packets on LANs, especially on
1794 * high speed LANs, allowing larger TCP buffers to be
1795 * specified, and also does a good job preventing
1796 * over-queueing of packets over choke points like modems
1797 * (at least for the transmit side).
1798 *
1799 * (2) Is able to handle changing network loads (bandwidth
1800 * drops so bwnd drops, bandwidth increases so bwnd
1801 * increases).
1802 *
1803 * (3) Theoretically should stabilize in the face of multiple
1804 * connections implementing the same algorithm (this may need
1805 * a little work).
1806 *
1807 * (4) Stability value (defaults to 20 = 2 maximal packets) can
1808 * be adjusted with a sysctl but typically only needs to be
1809 * on very slow connections. A value no smaller then 5
1810 * should be used, but only reduce this default if you have
1811 * no other choice.
1812 */
1813 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2)
1814 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10;
1815 #undef USERTT
1816
1817 if (tcp_inflight_debug > 0) {
1818 static int ltime;
1819 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
1820 ltime = ticks;
1821 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
1822 tp,
1823 bw,
1824 tp->t_rttbest,
1825 tp->t_srtt,
1826 bwnd
1827 );
1828 }
1829 }
1830 if ((long)bwnd < tcp_inflight_min)
1831 bwnd = tcp_inflight_min;
1832 if (bwnd > tcp_inflight_max)
1833 bwnd = tcp_inflight_max;
1834 if ((long)bwnd < tp->t_maxseg * 2)
1835 bwnd = tp->t_maxseg * 2;
1836 tp->snd_bwnd = bwnd;
1837 }
1838
1839 #ifdef TCP_SIGNATURE
1840 /*
1841 * Callback function invoked by m_apply() to digest TCP segment data
1842 * contained within an mbuf chain.
1843 */
1844 static int
1845 tcp_signature_apply(void *fstate, void *data, u_int len)
1846 {
1847
1848 MD5Update(fstate, (u_char *)data, len);
1849 return (0);
1850 }
1851
1852 /*
1853 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385)
1854 *
1855 * Parameters:
1856 * m pointer to head of mbuf chain
1857 * off0 offset to TCP header within the mbuf chain
1858 * len length of TCP segment data, excluding options
1859 * optlen length of TCP segment options
1860 * buf pointer to storage for computed MD5 digest
1861 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
1862 *
1863 * We do this over ip, tcphdr, segment data, and the key in the SADB.
1864 * When called from tcp_input(), we can be sure that th_sum has been
1865 * zeroed out and verified already.
1866 *
1867 * This function is for IPv4 use only. Calling this function with an
1868 * IPv6 packet in the mbuf chain will yield undefined results.
1869 *
1870 * Return 0 if successful, otherwise return -1.
1871 *
1872 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a
1873 * search with the destination IP address, and a 'magic SPI' to be
1874 * determined by the application. This is hardcoded elsewhere to 1179
1875 * right now. Another branch of this code exists which uses the SPD to
1876 * specify per-application flows but it is unstable.
1877 */
1878 int
1879 tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen,
1880 u_char *buf, u_int direction)
1881 {
1882 union sockaddr_union dst;
1883 struct ippseudo ippseudo;
1884 MD5_CTX ctx;
1885 int doff;
1886 struct ip *ip;
1887 struct ipovly *ipovly;
1888 struct secasvar *sav;
1889 struct tcphdr *th;
1890 u_short savecsum;
1891
1892 KASSERT(m != NULL, ("NULL mbuf chain"));
1893 KASSERT(buf != NULL, ("NULL signature pointer"));
1894
1895 /* Extract the destination from the IP header in the mbuf. */
1896 ip = mtod(m, struct ip *);
1897 bzero(&dst, sizeof(union sockaddr_union));
1898 dst.sa.sa_len = sizeof(struct sockaddr_in);
1899 dst.sa.sa_family = AF_INET;
1900 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ?
1901 ip->ip_src : ip->ip_dst;
1902
1903 /* Look up an SADB entry which matches the address of the peer. */
1904 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI));
1905 if (sav == NULL) {
1906 printf("%s: SADB lookup failed for %s\n", __func__,
1907 inet_ntoa(dst.sin.sin_addr));
1908 return (EINVAL);
1909 }
1910
1911 MD5Init(&ctx);
1912 ipovly = (struct ipovly *)ip;
1913 th = (struct tcphdr *)((u_char *)ip + off0);
1914 doff = off0 + sizeof(struct tcphdr) + optlen;
1915
1916 /*
1917 * Step 1: Update MD5 hash with IP pseudo-header.
1918 *
1919 * XXX The ippseudo header MUST be digested in network byte order,
1920 * or else we'll fail the regression test. Assume all fields we've
1921 * been doing arithmetic on have been in host byte order.
1922 * XXX One cannot depend on ipovly->ih_len here. When called from
1923 * tcp_output(), the underlying ip_len member has not yet been set.
1924 */
1925 ippseudo.ippseudo_src = ipovly->ih_src;
1926 ippseudo.ippseudo_dst = ipovly->ih_dst;
1927 ippseudo.ippseudo_pad = 0;
1928 ippseudo.ippseudo_p = IPPROTO_TCP;
1929 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen);
1930 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo));
1931
1932 /*
1933 * Step 2: Update MD5 hash with TCP header, excluding options.
1934 * The TCP checksum must be set to zero.
1935 */
1936 savecsum = th->th_sum;
1937 th->th_sum = 0;
1938 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
1939 th->th_sum = savecsum;
1940
1941 /*
1942 * Step 3: Update MD5 hash with TCP segment data.
1943 * Use m_apply() to avoid an early m_pullup().
1944 */
1945 if (len > 0)
1946 m_apply(m, doff, len, tcp_signature_apply, &ctx);
1947
1948 /*
1949 * Step 4: Update MD5 hash with shared secret.
1950 */
1951 MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
1952 MD5Final(buf, &ctx);
1953
1954 key_sa_recordxfer(sav, m);
1955 KEY_FREESAV(&sav);
1956 return (0);
1957 }
1958 #endif /* TCP_SIGNATURE */
1959
1960 static int
1961 sysctl_drop(SYSCTL_HANDLER_ARGS)
1962 {
1963 /* addrs[0] is a foreign socket, addrs[1] is a local one. */
1964 struct sockaddr_storage addrs[2];
1965 struct inpcb *inp;
1966 struct tcpcb *tp;
1967 struct tcptw *tw;
1968 struct sockaddr_in *fin, *lin;
1969 #ifdef INET6
1970 struct sockaddr_in6 *fin6, *lin6;
1971 struct in6_addr f6, l6;
1972 #endif
1973 int error;
1974
1975 inp = NULL;
1976 fin = lin = NULL;
1977 #ifdef INET6
1978 fin6 = lin6 = NULL;
1979 #endif
1980 error = 0;
1981
1982 if (req->oldptr != NULL || req->oldlen != 0)
1983 return (EINVAL);
1984 if (req->newptr == NULL)
1985 return (EPERM);
1986 if (req->newlen < sizeof(addrs))
1987 return (ENOMEM);
1988 error = SYSCTL_IN(req, &addrs, sizeof(addrs));
1989 if (error)
1990 return (error);
1991
1992 switch (addrs[0].ss_family) {
1993 #ifdef INET6
1994 case AF_INET6:
1995 fin6 = (struct sockaddr_in6 *)&addrs[0];
1996 lin6 = (struct sockaddr_in6 *)&addrs[1];
1997 if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
1998 lin6->sin6_len != sizeof(struct sockaddr_in6))
1999 return (EINVAL);
2000 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
2001 if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
2002 return (EINVAL);
2003 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
2004 in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
2005 fin = (struct sockaddr_in *)&addrs[0];
2006 lin = (struct sockaddr_in *)&addrs[1];
2007 break;
2008 }
2009 error = sa6_embedscope(fin6, ip6_use_defzone);
2010 if (error)
2011 return (error);
2012 error = sa6_embedscope(lin6, ip6_use_defzone);
2013 if (error)
2014 return (error);
2015 break;
2016 #endif
2017 case AF_INET:
2018 fin = (struct sockaddr_in *)&addrs[0];
2019 lin = (struct sockaddr_in *)&addrs[1];
2020 if (fin->sin_len != sizeof(struct sockaddr_in) ||
2021 lin->sin_len != sizeof(struct sockaddr_in))
2022 return (EINVAL);
2023 break;
2024 default:
2025 return (EINVAL);
2026 }
2027 INP_INFO_WLOCK(&tcbinfo);
2028 switch (addrs[0].ss_family) {
2029 #ifdef INET6
2030 case AF_INET6:
2031 inp = in6_pcblookup_hash(&tcbinfo, &f6, fin6->sin6_port,
2032 &l6, lin6->sin6_port, 0, NULL);
2033 break;
2034 #endif
2035 case AF_INET:
2036 inp = in_pcblookup_hash(&tcbinfo, fin->sin_addr, fin->sin_port,
2037 lin->sin_addr, lin->sin_port, 0, NULL);
2038 break;
2039 }
2040 if (inp != NULL) {
2041 INP_LOCK(inp);
2042 if (inp->inp_vflag & INP_TIMEWAIT) {
2043 /*
2044 * XXXRW: There currently exists a state where an
2045 * inpcb is present, but its timewait state has been
2046 * discarded. For now, don't allow dropping of this
2047 * type of inpcb.
2048 */
2049 tw = intotw(inp);
2050 if (tw != NULL)
2051 tcp_twclose(tw, 0);
2052 else
2053 INP_UNLOCK(inp);
2054 } else if (!(inp->inp_vflag & INP_DROPPED) &&
2055 !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
2056 tp = intotcpcb(inp);
2057 tp = tcp_drop(tp, ECONNABORTED);
2058 if (tp != NULL)
2059 INP_UNLOCK(inp);
2060 } else
2061 INP_UNLOCK(inp);
2062 } else
2063 error = ESRCH;
2064 INP_INFO_WUNLOCK(&tcbinfo);
2065 return (error);
2066 }
2067
2068 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
2069 CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL,
2070 0, sysctl_drop, "", "Drop TCP connection");
2071
2072 /*
2073 * Generate a standardized TCP log line for use throughout the
2074 * tcp subsystem. Memory allocation is done with M_NOWAIT to
2075 * allow use in the interrupt context.
2076 *
2077 * NB: The caller MUST free(s, M_TCPLOG) the returned string.
2078 * NB: The function may return NULL if memory allocation failed.
2079 *
2080 * Due to header inclusion and ordering limitations the struct ip
2081 * and ip6_hdr pointers have to be passed as void pointers.
2082 */
2083 char *
2084 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
2085 const void *ip6hdr)
2086 {
2087 char *s, *sp;
2088 size_t size;
2089 struct ip *ip;
2090 #ifdef INET6
2091 const struct ip6_hdr *ip6;
2092
2093 ip6 = (const struct ip6_hdr *)ip6hdr;
2094 #endif /* INET6 */
2095 ip = (struct ip *)ip4hdr;
2096
2097 /*
2098 * The log line looks like this:
2099 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
2100 */
2101 size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
2102 sizeof(PRINT_TH_FLAGS) + 1 +
2103 #ifdef INET6
2104 2 * INET6_ADDRSTRLEN;
2105 #else
2106 2 * INET_ADDRSTRLEN;
2107 #endif /* INET6 */
2108
2109 /* Is logging enabled? */
2110 if (tcp_log_debug == 0 && tcp_log_in_vain == 0)
2111 return (NULL);
2112
2113 s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
2114 if (s == NULL)
2115 return (NULL);
2116
2117 strcat(s, "TCP: [");
2118 sp = s + strlen(s);
2119
2120 if (inc && inc->inc_isipv6 == 0) {
2121 inet_ntoa_r(inc->inc_faddr, sp);
2122 sp = s + strlen(s);
2123 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2124 sp = s + strlen(s);
2125 inet_ntoa_r(inc->inc_laddr, sp);
2126 sp = s + strlen(s);
2127 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2128 #ifdef INET6
2129 } else if (inc) {
2130 ip6_sprintf(sp, &inc->inc6_faddr);
2131 sp = s + strlen(s);
2132 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
2133 sp = s + strlen(s);
2134 ip6_sprintf(sp, &inc->inc6_laddr);
2135 sp = s + strlen(s);
2136 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
2137 } else if (ip6 && th) {
2138 ip6_sprintf(sp, &ip6->ip6_src);
2139 sp = s + strlen(s);
2140 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2141 sp = s + strlen(s);
2142 ip6_sprintf(sp, &ip6->ip6_dst);
2143 sp = s + strlen(s);
2144 sprintf(sp, "]:%i", ntohs(th->th_dport));
2145 #endif /* INET6 */
2146 } else if (ip && th) {
2147 inet_ntoa_r(ip->ip_src, sp);
2148 sp = s + strlen(s);
2149 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
2150 sp = s + strlen(s);
2151 inet_ntoa_r(ip->ip_dst, sp);
2152 sp = s + strlen(s);
2153 sprintf(sp, "]:%i", ntohs(th->th_dport));
2154 } else {
2155 free(s, M_TCPLOG);
2156 return (NULL);
2157 }
2158 sp = s + strlen(s);
2159 if (th)
2160 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
2161 if (*(s + size - 1) != '\0')
2162 panic("%s: string too long", __func__);
2163 return (s);
2164 }
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