xref: /freebsd/sys/netinet/ip_divert.c (revision d9a42747950146bf03cda7f6e25d219253f8a57a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1982, 1986, 1988, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_sctp.h"
38 
39 #include <sys/param.h>
40 #include <sys/eventhandler.h>
41 #include <sys/kernel.h>
42 #include <sys/lock.h>
43 #include <sys/malloc.h>
44 #include <sys/mbuf.h>
45 #include <sys/module.h>
46 #include <sys/kernel.h>
47 #include <sys/priv.h>
48 #include <sys/proc.h>
49 #include <sys/domain.h>
50 #include <sys/protosw.h>
51 #include <sys/socket.h>
52 #include <sys/socketvar.h>
53 #include <sys/sysctl.h>
54 #include <net/vnet.h>
55 
56 #include <net/if.h>
57 #include <net/if_var.h>
58 #include <net/if_private.h>
59 #include <net/netisr.h>
60 
61 #include <netinet/in.h>
62 #include <netinet/in_pcb.h>
63 #include <netinet/in_systm.h>
64 #include <netinet/in_var.h>
65 #include <netinet/ip.h>
66 #include <netinet/ip_var.h>
67 #include <netinet/ip_divert.h>
68 #ifdef INET6
69 #include <netinet/ip6.h>
70 #include <netinet6/ip6_var.h>
71 #endif
72 #if defined(SCTP) || defined(SCTP_SUPPORT)
73 #include <netinet/sctp_crc32.h>
74 #endif
75 
76 #include <security/mac/mac_framework.h>
77 /*
78  * Divert sockets
79  */
80 
81 /*
82  * Allocate enough space to hold a full IP packet
83  */
84 #define	DIVSNDQ		(65536 + 100)
85 #define	DIVRCVQ		(65536 + 100)
86 
87 /*
88  * Usually a system has very few divert ports.  Previous implementation
89  * used a linked list.
90  */
91 #define	DIVHASHSIZE	(1 << 3)	/* 8 entries, one cache line. */
92 #define	DIVHASH(port)	(port % DIVHASHSIZE)
93 #define	DCBHASH(dcb)	((dcb)->dcb_port % DIVHASHSIZE)
94 
95 /*
96  * Divert sockets work in conjunction with ipfw or other packet filters,
97  * see the divert(4) manpage for features.
98  * Packets are selected by the packet filter and tagged with an
99  * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
100  * the packet filter) and information on the matching filter rule for
101  * subsequent reinjection. The divert_port is used to put the packet
102  * on the corresponding divert socket, while the rule number is passed
103  * up (at least partially) as the sin_port in the struct sockaddr.
104  *
105  * Packets written to the divert socket carry in sin_addr a
106  * destination address, and in sin_port the number of the filter rule
107  * after which to continue processing.
108  * If the destination address is INADDR_ANY, the packet is treated as
109  * as outgoing and sent to ip_output(); otherwise it is treated as
110  * incoming and sent to ip_input().
111  * Further, sin_zero carries some information on the interface,
112  * which can be used in the reinject -- see comments in the code.
113  *
114  * On reinjection, processing in ip_input() and ip_output()
115  * will be exactly the same as for the original packet, except that
116  * packet filter processing will start at the rule number after the one
117  * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
118  * will apply the entire ruleset to the packet).
119  */
120 static SYSCTL_NODE(_net_inet, OID_AUTO, divert, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
121     "divert(4)");
122 
123 VNET_PCPUSTAT_DEFINE_STATIC(struct divstat, divstat);
124 VNET_PCPUSTAT_SYSINIT(divstat);
125 #ifdef VIMAGE
126 VNET_PCPUSTAT_SYSUNINIT(divstat);
127 #endif
128 SYSCTL_VNET_PCPUSTAT(_net_inet_divert, OID_AUTO, stats, struct divstat,
129     divstat, "divert(4) socket statistics");
130 #define	DIVSTAT_INC(name)	\
131     VNET_PCPUSTAT_ADD(struct divstat, divstat, div_ ## name, 1)
132 
133 static u_long	div_sendspace = DIVSNDQ;	/* XXX sysctl ? */
134 static u_long	div_recvspace = DIVRCVQ;	/* XXX sysctl ? */
135 
136 static int div_output_inbound(int fmaily, struct socket *so, struct mbuf *m,
137     struct sockaddr_in *sin);
138 static int div_output_outbound(int family, struct socket *so, struct mbuf *m);
139 
140 struct divcb {
141 	union {
142 		SLIST_ENTRY(divcb)	dcb_next;
143 		intptr_t		dcb_bound;
144 #define	DCB_UNBOUND	((intptr_t)-1)
145 	};
146 	struct socket		*dcb_socket;
147 	uint16_t		 dcb_port;
148 	uint64_t		 dcb_gencnt;
149 	struct epoch_context	 dcb_epochctx;
150 };
151 
152 SLIST_HEAD(divhashhead, divcb);
153 
154 VNET_DEFINE_STATIC(struct divhashhead, divhash[DIVHASHSIZE]) = {};
155 #define	V_divhash	VNET(divhash)
156 VNET_DEFINE_STATIC(uint64_t, dcb_count) = 0;
157 #define	V_dcb_count	VNET(dcb_count)
158 VNET_DEFINE_STATIC(uint64_t, dcb_gencnt) = 0;
159 #define	V_dcb_gencnt	VNET(dcb_gencnt)
160 
161 static struct mtx divert_mtx;
162 MTX_SYSINIT(divert, &divert_mtx, "divert(4) socket pcb lists", MTX_DEF);
163 #define	DIVERT_LOCK()	mtx_lock(&divert_mtx)
164 #define	DIVERT_UNLOCK()	mtx_unlock(&divert_mtx)
165 
166 /*
167  * Divert a packet by passing it up to the divert socket at port 'port'.
168  */
169 static void
170 divert_packet(struct mbuf *m, bool incoming)
171 {
172 	struct divcb *dcb;
173 	u_int16_t nport;
174 	struct sockaddr_in divsrc;
175 	struct m_tag *mtag;
176 
177 	NET_EPOCH_ASSERT();
178 
179 	mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
180 	if (mtag == NULL) {
181 		m_freem(m);
182 		return;
183 	}
184 	/* Assure header */
185 	if (m->m_len < sizeof(struct ip) &&
186 	    (m = m_pullup(m, sizeof(struct ip))) == NULL)
187 		return;
188 #ifdef INET
189 	/* Delayed checksums are currently not compatible with divert. */
190 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
191 		in_delayed_cksum(m);
192 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
193 	}
194 #if defined(SCTP) || defined(SCTP_SUPPORT)
195 	if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
196 		struct ip *ip;
197 
198 		ip = mtod(m, struct ip *);
199 		sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
200 		m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
201 	}
202 #endif
203 #endif
204 #ifdef INET6
205 	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
206 		in6_delayed_cksum(m, m->m_pkthdr.len -
207 		    sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
208 		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
209 	}
210 #if defined(SCTP) || defined(SCTP_SUPPORT)
211 	if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
212 		sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
213 		m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
214 	}
215 #endif
216 #endif /* INET6 */
217 	bzero(&divsrc, sizeof(divsrc));
218 	divsrc.sin_len = sizeof(divsrc);
219 	divsrc.sin_family = AF_INET;
220 	/* record matching rule, in host format */
221 	divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
222 	/*
223 	 * Record receive interface address, if any.
224 	 * But only for incoming packets.
225 	 */
226 	if (incoming) {
227 		struct ifaddr *ifa;
228 		struct ifnet *ifp;
229 
230 		/* Sanity check */
231 		M_ASSERTPKTHDR(m);
232 
233 		/* Find IP address for receive interface */
234 		ifp = m->m_pkthdr.rcvif;
235 		CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
236 			if (ifa->ifa_addr->sa_family != AF_INET)
237 				continue;
238 			divsrc.sin_addr =
239 			    ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
240 			break;
241 		}
242 	}
243 	/*
244 	 * Record the incoming interface name whenever we have one.
245 	 */
246 	if (m->m_pkthdr.rcvif) {
247 		/*
248 		 * Hide the actual interface name in there in the
249 		 * sin_zero array. XXX This needs to be moved to a
250 		 * different sockaddr type for divert, e.g.
251 		 * sockaddr_div with multiple fields like
252 		 * sockaddr_dl. Presently we have only 7 bytes
253 		 * but that will do for now as most interfaces
254 		 * are 4 or less + 2 or less bytes for unit.
255 		 * There is probably a faster way of doing this,
256 		 * possibly taking it from the sockaddr_dl on the iface.
257 		 * This solves the problem of a P2P link and a LAN interface
258 		 * having the same address, which can result in the wrong
259 		 * interface being assigned to the packet when fed back
260 		 * into the divert socket. Theoretically if the daemon saves
261 		 * and re-uses the sockaddr_in as suggested in the man pages,
262 		 * this iface name will come along for the ride.
263 		 * (see div_output for the other half of this.)
264 		 */
265 		strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
266 		    sizeof(divsrc.sin_zero));
267 	}
268 
269 	/* Put packet on socket queue, if any */
270 	nport = htons((uint16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
271 	SLIST_FOREACH(dcb, &V_divhash[DIVHASH(nport)], dcb_next)
272 		if (dcb->dcb_port == nport)
273 			break;
274 
275 	if (dcb != NULL) {
276 		struct socket *sa = dcb->dcb_socket;
277 
278 		SOCKBUF_LOCK(&sa->so_rcv);
279 		if (sbappendaddr_locked(&sa->so_rcv,
280 		    (struct sockaddr *)&divsrc, m, NULL) == 0) {
281 			soroverflow_locked(sa);
282 			m_freem(m);
283 		} else {
284 			sorwakeup_locked(sa);
285 			DIVSTAT_INC(diverted);
286 		}
287 	} else {
288 		DIVSTAT_INC(noport);
289 		m_freem(m);
290 	}
291 }
292 
293 /*
294  * Deliver packet back into the IP processing machinery.
295  *
296  * If no address specified, or address is 0.0.0.0, send to ip_output();
297  * otherwise, send to ip_input() and mark as having been received on
298  * the interface with that address.
299  */
300 static int
301 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
302     struct mbuf *control, struct thread *td)
303 {
304 	struct epoch_tracker et;
305 	struct sockaddr_in *sin = (struct sockaddr_in *)nam;
306 	const struct ip *ip;
307 	struct m_tag *mtag;
308 	struct ipfw_rule_ref *dt;
309 	int error, family;
310 
311 	if (control)
312 		m_freem(control);
313 
314 	/* Packet must have a header (but that's about it) */
315 	if (m->m_len < sizeof (struct ip) &&
316 	    (m = m_pullup(m, sizeof (struct ip))) == NULL) {
317 		m_freem(m);
318 		return (EINVAL);
319 	}
320 
321 	if (sin != NULL) {
322 		if (sin->sin_family != AF_INET) {
323 			m_freem(m);
324 			return (EAFNOSUPPORT);
325 		}
326 		if (sin->sin_len != sizeof(*sin)) {
327 			m_freem(m);
328 			return (EINVAL);
329 		}
330 	}
331 
332 	/*
333 	 * An mbuf may hasn't come from userland, but we pretend
334 	 * that it has.
335 	 */
336 	m->m_pkthdr.rcvif = NULL;
337 	m->m_nextpkt = NULL;
338 	M_SETFIB(m, so->so_fibnum);
339 
340 	mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
341 	if (mtag == NULL) {
342 		/* this should be normal */
343 		mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
344 		    sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
345 		if (mtag == NULL) {
346 			m_freem(m);
347 			return (ENOBUFS);
348 		}
349 		m_tag_prepend(m, mtag);
350 	}
351 	dt = (struct ipfw_rule_ref *)(mtag+1);
352 
353 	/* Loopback avoidance and state recovery */
354 	if (sin) {
355 		int i;
356 
357 		/* set the starting point. We provide a non-zero slot,
358 		 * but a non_matching chain_id to skip that info and use
359 		 * the rulenum/rule_id.
360 		 */
361 		dt->slot = 1; /* dummy, chain_id is invalid */
362 		dt->chain_id = 0;
363 		dt->rulenum = sin->sin_port+1; /* host format ? */
364 		dt->rule_id = 0;
365 		/* XXX: broken for IPv6 */
366 		/*
367 		 * Find receive interface with the given name, stuffed
368 		 * (if it exists) in the sin_zero[] field.
369 		 * The name is user supplied data so don't trust its size
370 		 * or that it is zero terminated.
371 		 */
372 		for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
373 			;
374 		if ( i > 0 && i < sizeof(sin->sin_zero))
375 			m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
376 	}
377 
378 	ip = mtod(m, struct ip *);
379 	switch (ip->ip_v) {
380 #ifdef INET
381 	case IPVERSION:
382 		family = AF_INET;
383 		break;
384 #endif
385 #ifdef INET6
386 	case IPV6_VERSION >> 4:
387 		family = AF_INET6;
388 		break;
389 #endif
390 	default:
391 		m_freem(m);
392 		return (EAFNOSUPPORT);
393 	}
394 
395 	/* Reinject packet into the system as incoming or outgoing */
396 	NET_EPOCH_ENTER(et);
397 	if (!sin || sin->sin_addr.s_addr == 0) {
398 		dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
399 		error = div_output_outbound(family, so, m);
400 	} else {
401 		dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
402 		error = div_output_inbound(family, so, m, sin);
403 	}
404 	NET_EPOCH_EXIT(et);
405 
406 	return (error);
407 }
408 
409 /*
410  * Sends mbuf @m to the wire via ip[6]_output().
411  *
412  * Returns 0 on success or an errno value on failure.  @m is always consumed.
413  */
414 static int
415 div_output_outbound(int family, struct socket *so, struct mbuf *m)
416 {
417 	int error;
418 
419 	switch (family) {
420 #ifdef INET
421 	case AF_INET:
422 	    {
423 		struct ip *const ip = mtod(m, struct ip *);
424 
425 		/* Don't allow packet length sizes that will crash. */
426 		if (((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
427 			m_freem(m);
428 			return (EINVAL);
429 		}
430 		break;
431 	    }
432 #endif
433 #ifdef INET6
434 	case AF_INET6:
435 	    {
436 		struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
437 
438 		/* Don't allow packet length sizes that will crash */
439 		if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
440 			m_freem(m);
441 			return (EINVAL);
442 		}
443 		break;
444 	    }
445 #endif
446 	}
447 
448 #ifdef MAC
449 	mac_socket_create_mbuf(so, m);
450 #endif
451 
452 	error = 0;
453 	switch (family) {
454 #ifdef INET
455 	case AF_INET:
456 		error = ip_output(m, NULL, NULL,
457 		    ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
458 		    | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
459 		break;
460 #endif
461 #ifdef INET6
462 	case AF_INET6:
463 		error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
464 		break;
465 #endif
466 	}
467 	if (error == 0)
468 		DIVSTAT_INC(outbound);
469 
470 	return (error);
471 }
472 
473 /*
474  * Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
475  *
476  * Returns 0 on success or an errno value on failure.  @m is always consumed.
477  */
478 static int
479 div_output_inbound(int family, struct socket *so, struct mbuf *m,
480     struct sockaddr_in *sin)
481 {
482 	struct ifaddr *ifa;
483 
484 	if (m->m_pkthdr.rcvif == NULL) {
485 		/*
486 		 * No luck with the name, check by IP address.
487 		 * Clear the port and the ifname to make sure
488 		 * there are no distractions for ifa_ifwithaddr.
489 		 */
490 
491 		/* XXX: broken for IPv6 */
492 		bzero(sin->sin_zero, sizeof(sin->sin_zero));
493 		sin->sin_port = 0;
494 		ifa = ifa_ifwithaddr((struct sockaddr *) sin);
495 		if (ifa == NULL) {
496 			m_freem(m);
497 			return (EADDRNOTAVAIL);
498 		}
499 		m->m_pkthdr.rcvif = ifa->ifa_ifp;
500 	}
501 #ifdef MAC
502 	mac_socket_create_mbuf(so, m);
503 #endif
504 	/* Send packet to input processing via netisr */
505 	switch (family) {
506 #ifdef INET
507 	case AF_INET:
508 	    {
509 		const struct ip *ip;
510 
511 		ip = mtod(m, struct ip *);
512 		/*
513 		 * Restore M_BCAST flag when destination address is
514 		 * broadcast. It is expected by ip_tryforward().
515 		 */
516 		if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
517 			m->m_flags |= M_MCAST;
518 		else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
519 			m->m_flags |= M_BCAST;
520 		netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
521 		DIVSTAT_INC(inbound);
522 		break;
523 	    }
524 #endif
525 #ifdef INET6
526 	case AF_INET6:
527 		netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
528 		DIVSTAT_INC(inbound);
529 		break;
530 #endif
531 	default:
532 		m_freem(m);
533 		return (EINVAL);
534 	}
535 
536 	return (0);
537 }
538 
539 static int
540 div_attach(struct socket *so, int proto, struct thread *td)
541 {
542 	struct divcb *dcb;
543 	int error;
544 
545 	if (td != NULL) {
546 		error = priv_check(td, PRIV_NETINET_DIVERT);
547 		if (error)
548 			return (error);
549 	}
550 	error = soreserve(so, div_sendspace, div_recvspace);
551 	if (error)
552 		return error;
553 	dcb = malloc(sizeof(*dcb), M_PCB, M_WAITOK);
554 	dcb->dcb_bound = DCB_UNBOUND;
555 	dcb->dcb_socket = so;
556 	DIVERT_LOCK();
557 	V_dcb_count++;
558 	dcb->dcb_gencnt = ++V_dcb_gencnt;
559 	DIVERT_UNLOCK();
560 	so->so_pcb = dcb;
561 
562 	return (0);
563 }
564 
565 static void
566 div_free(epoch_context_t ctx)
567 {
568 	struct divcb *dcb = __containerof(ctx, struct divcb, dcb_epochctx);
569 
570 	free(dcb, M_PCB);
571 }
572 
573 static void
574 div_detach(struct socket *so)
575 {
576 	struct divcb *dcb = so->so_pcb;
577 
578 	so->so_pcb = NULL;
579 	DIVERT_LOCK();
580 	if (dcb->dcb_bound != DCB_UNBOUND)
581 		SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
582 	V_dcb_count--;
583 	V_dcb_gencnt++;
584 	DIVERT_UNLOCK();
585 	NET_EPOCH_CALL(div_free, &dcb->dcb_epochctx);
586 }
587 
588 static int
589 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
590 {
591 	struct divcb *dcb;
592 	uint16_t port;
593 
594 	if (nam->sa_family != AF_INET)
595 		return EAFNOSUPPORT;
596 	if (nam->sa_len != sizeof(struct sockaddr_in))
597 		return EINVAL;
598 	port = ((struct sockaddr_in *)nam)->sin_port;
599 	DIVERT_LOCK();
600 	SLIST_FOREACH(dcb, &V_divhash[DIVHASH(port)], dcb_next)
601 		if (dcb->dcb_port == port) {
602 			DIVERT_UNLOCK();
603 			return (EADDRINUSE);
604 		}
605 	dcb = so->so_pcb;
606 	if (dcb->dcb_bound != DCB_UNBOUND)
607 		SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
608 	dcb->dcb_port = port;
609 	SLIST_INSERT_HEAD(&V_divhash[DIVHASH(port)], dcb, dcb_next);
610 	DIVERT_UNLOCK();
611 
612 	return (0);
613 }
614 
615 static int
616 div_shutdown(struct socket *so)
617 {
618 
619 	socantsendmore(so);
620 	return 0;
621 }
622 
623 static int
624 div_pcblist(SYSCTL_HANDLER_ARGS)
625 {
626 	struct xinpgen xig;
627 	struct divcb *dcb;
628 	int error;
629 
630 	if (req->newptr != 0)
631 		return EPERM;
632 
633 	if (req->oldptr == 0) {
634 		u_int n;
635 
636 		n = V_dcb_count;
637 		n += imax(n / 8, 10);
638 		req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
639 		return 0;
640 	}
641 
642 	if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
643 		return (error);
644 
645 	bzero(&xig, sizeof(xig));
646 	xig.xig_len = sizeof xig;
647 	xig.xig_count = V_dcb_count;
648 	xig.xig_gen = V_dcb_gencnt;
649 	xig.xig_sogen = so_gencnt;
650 	error = SYSCTL_OUT(req, &xig, sizeof xig);
651 	if (error)
652 		return error;
653 
654 	DIVERT_LOCK();
655 	for (int i = 0; i < DIVHASHSIZE; i++)
656 		SLIST_FOREACH(dcb, &V_divhash[i], dcb_next) {
657 			if (dcb->dcb_gencnt <= xig.xig_gen) {
658 				struct xinpcb xi;
659 
660 				bzero(&xi, sizeof(xi));
661 				xi.xi_len = sizeof(struct xinpcb);
662 				sotoxsocket(dcb->dcb_socket, &xi.xi_socket);
663 				xi.inp_gencnt = dcb->dcb_gencnt;
664 				xi.inp_vflag = INP_IPV4; /* XXX: netstat(1) */
665 				xi.inp_inc.inc_ie.ie_lport = dcb->dcb_port;
666 				error = SYSCTL_OUT(req, &xi, sizeof xi);
667 				if (error)
668 					goto errout;
669 			}
670 		}
671 
672 	/*
673 	 * Give the user an updated idea of our state.
674 	 * If the generation differs from what we told
675 	 * her before, she knows that something happened
676 	 * while we were processing this request, and it
677 	 * might be necessary to retry.
678 	 */
679 	xig.xig_gen = V_dcb_gencnt;
680 	xig.xig_sogen = so_gencnt;
681 	xig.xig_count = V_dcb_count;
682 	error = SYSCTL_OUT(req, &xig, sizeof xig);
683 
684 errout:
685 	DIVERT_UNLOCK();
686 
687 	return (error);
688 }
689 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist,
690     CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, div_pcblist,
691     "S,xinpcb", "List of active divert sockets");
692 
693 static struct protosw div_protosw = {
694 	.pr_type =		SOCK_RAW,
695 	.pr_flags =		PR_ATOMIC|PR_ADDR,
696 	.pr_attach =		div_attach,
697 	.pr_bind =		div_bind,
698 	.pr_detach =		div_detach,
699 	.pr_send =		div_send,
700 	.pr_shutdown =		div_shutdown,
701 };
702 
703 static struct domain divertdomain = {
704 	.dom_family =	PF_DIVERT,
705 	.dom_name =	"divert",
706 	.dom_nprotosw =	1,
707 	.dom_protosw =	{ &div_protosw },
708 };
709 
710 static int
711 div_modevent(module_t mod, int type, void *unused)
712 {
713 	int err = 0;
714 
715 	switch (type) {
716 	case MOD_LOAD:
717 		domain_add(&divertdomain);
718 		ip_divert_ptr = divert_packet;
719 		break;
720 	case MOD_QUIESCE:
721 		/*
722 		 * IPDIVERT may normally not be unloaded because of the
723 		 * potential race conditions.  Tell kldunload we can't be
724 		 * unloaded unless the unload is forced.
725 		 */
726 		err = EPERM;
727 		break;
728 	case MOD_UNLOAD:
729 		/*
730 		 * Forced unload.
731 		 *
732 		 * Module ipdivert can only be unloaded if no sockets are
733 		 * connected.  Maybe this can be changed later to forcefully
734 		 * disconnect any open sockets.
735 		 *
736 		 * XXXRW: Note that there is a slight race here, as a new
737 		 * socket open request could be spinning on the lock and then
738 		 * we destroy the lock.
739 		 *
740 		 * XXXGL: One more reason this code is incorrect is that it
741 		 * checks only the current vnet.
742 		 */
743 		DIVERT_LOCK();
744 		if (V_dcb_count != 0) {
745 			DIVERT_UNLOCK();
746 			err = EBUSY;
747 			break;
748 		}
749 		DIVERT_UNLOCK();
750 		ip_divert_ptr = NULL;
751 		domain_remove(&divertdomain);
752 		break;
753 	default:
754 		err = EOPNOTSUPP;
755 		break;
756 	}
757 	return err;
758 }
759 
760 static moduledata_t ipdivertmod = {
761         "ipdivert",
762         div_modevent,
763         0
764 };
765 
766 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
767 MODULE_VERSION(ipdivert, 1);
768