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32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
36 #include "opt_inet6.h"
39 #error "IPDIVERT requires INET"
42 #include <sys/param.h>
43 #include <sys/eventhandler.h>
44 #include <sys/kernel.h>
46 #include <sys/malloc.h>
48 #include <sys/module.h>
49 #include <sys/kernel.h>
52 #include <sys/protosw.h>
53 #include <sys/socket.h>
54 #include <sys/socketvar.h>
55 #include <sys/sysctl.h>
59 #include <net/if_var.h>
60 #include <net/netisr.h>
62 #include <netinet/in.h>
63 #include <netinet/in_pcb.h>
64 #include <netinet/in_systm.h>
65 #include <netinet/in_var.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_var.h>
69 #include <netinet/ip6.h>
70 #include <netinet6/ip6_var.h>
73 #include <netinet/sctp_crc32.h>
76 #include <security/mac/mac_framework.h>
82 * Allocate enough space to hold a full IP packet
84 #define DIVSNDQ (65536 + 100)
85 #define DIVRCVQ (65536 + 100)
88 * Divert sockets work in conjunction with ipfw or other packet filters,
89 * see the divert(4) manpage for features.
90 * Packets are selected by the packet filter and tagged with an
91 * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
92 * the packet filter) and information on the matching filter rule for
93 * subsequent reinjection. The divert_port is used to put the packet
94 * on the corresponding divert socket, while the rule number is passed
95 * up (at least partially) as the sin_port in the struct sockaddr.
97 * Packets written to the divert socket carry in sin_addr a
98 * destination address, and in sin_port the number of the filter rule
99 * after which to continue processing.
100 * If the destination address is INADDR_ANY, the packet is treated as
101 * as outgoing and sent to ip_output(); otherwise it is treated as
102 * incoming and sent to ip_input().
103 * Further, sin_zero carries some information on the interface,
104 * which can be used in the reinject -- see comments in the code.
106 * On reinjection, processing in ip_input() and ip_output()
107 * will be exactly the same as for the original packet, except that
108 * packet filter processing will start at the rule number after the one
109 * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
110 * will apply the entire ruleset to the packet).
113 /* Internal variables. */
114 VNET_DEFINE_STATIC(struct inpcbhead, divcb);
115 VNET_DEFINE_STATIC(struct inpcbinfo, divcbinfo);
117 #define V_divcb VNET(divcb)
118 #define V_divcbinfo VNET(divcbinfo)
120 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
121 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
123 static eventhandler_tag ip_divert_event_tag;
126 * Initialize divert connection block queue.
129 div_zone_change(void *tag)
132 uma_zone_set_max(V_divcbinfo.ipi_zone, maxsockets);
136 div_inpcb_init(void *mem, int size, int flags)
138 struct inpcb *inp = mem;
140 INP_LOCK_INIT(inp, "inp", "divinp");
149 * XXX We don't use the hash list for divert IP, but it's easier to
150 * allocate one-entry hash lists than it is to check all over the
151 * place for hashbase == NULL.
153 in_pcbinfo_init(&V_divcbinfo, "div", &V_divcb, 1, 1, "divcb",
154 div_inpcb_init, IPI_HASHFIELDS_NONE);
158 div_destroy(void *unused __unused)
161 in_pcbinfo_destroy(&V_divcbinfo);
163 VNET_SYSUNINIT(divert, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
167 * IPPROTO_DIVERT is not in the real IP protocol number space; this
168 * function should never be called. Just in case, drop any packets.
171 div_input(struct mbuf **mp, int *offp, int proto)
173 struct mbuf *m = *mp;
175 KMOD_IPSTAT_INC(ips_noproto);
177 return (IPPROTO_DONE);
181 * Divert a packet by passing it up to the divert socket at port 'port'.
183 * Setup generic address and protocol structures for div_input routine,
184 * then pass them along with mbuf chain.
187 divert_packet(struct mbuf *m, bool incoming)
193 struct sockaddr_in divsrc;
198 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
204 if (m->m_len < sizeof(struct ip) &&
205 (m = m_pullup(m, sizeof(struct ip))) == NULL)
207 ip = mtod(m, struct ip *);
209 /* Delayed checksums are currently not compatible with divert. */
210 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
212 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
215 if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
216 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
217 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
220 bzero(&divsrc, sizeof(divsrc));
221 divsrc.sin_len = sizeof(divsrc);
222 divsrc.sin_family = AF_INET;
223 /* record matching rule, in host format */
224 divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
226 * Record receive interface address, if any.
227 * But only for incoming packets.
236 /* Find IP address for receive interface */
237 ifp = m->m_pkthdr.rcvif;
238 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
239 if (ifa->ifa_addr->sa_family != AF_INET)
242 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
247 * Record the incoming interface name whenever we have one.
249 if (m->m_pkthdr.rcvif) {
251 * Hide the actual interface name in there in the
252 * sin_zero array. XXX This needs to be moved to a
253 * different sockaddr type for divert, e.g.
254 * sockaddr_div with multiple fields like
255 * sockaddr_dl. Presently we have only 7 bytes
256 * but that will do for now as most interfaces
257 * are 4 or less + 2 or less bytes for unit.
258 * There is probably a faster way of doing this,
259 * possibly taking it from the sockaddr_dl on the iface.
260 * This solves the problem of a P2P link and a LAN interface
261 * having the same address, which can result in the wrong
262 * interface being assigned to the packet when fed back
263 * into the divert socket. Theoretically if the daemon saves
264 * and re-uses the sockaddr_in as suggested in the man pages,
265 * this iface name will come along for the ride.
266 * (see div_output for the other half of this.)
268 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
269 sizeof(divsrc.sin_zero));
272 /* Put packet on socket queue, if any */
274 nport = htons((u_int16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
275 CK_LIST_FOREACH(inp, &V_divcb, inp_list) {
276 /* XXX why does only one socket match? */
277 if (inp->inp_lport == nport) {
279 sa = inp->inp_socket;
280 SOCKBUF_LOCK(&sa->so_rcv);
281 if (sbappendaddr_locked(&sa->so_rcv,
282 (struct sockaddr *)&divsrc, m,
283 (struct mbuf *)0) == 0) {
284 SOCKBUF_UNLOCK(&sa->so_rcv);
285 sa = NULL; /* force mbuf reclaim below */
287 sorwakeup_locked(sa);
294 KMOD_IPSTAT_INC(ips_noproto);
295 KMOD_IPSTAT_DEC(ips_delivered);
300 * Deliver packet back into the IP processing machinery.
302 * If no address specified, or address is 0.0.0.0, send to ip_output();
303 * otherwise, send to ip_input() and mark as having been received on
304 * the interface with that address.
307 div_output(struct socket *so, struct mbuf *m, struct sockaddr_in *sin,
308 struct mbuf *control)
310 struct ip *const ip = mtod(m, struct ip *);
312 struct ipfw_rule_ref *dt;
316 * An mbuf may hasn't come from userland, but we pretend
319 m->m_pkthdr.rcvif = NULL;
321 M_SETFIB(m, so->so_fibnum);
324 m_freem(control); /* XXX */
326 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
328 /* this should be normal */
329 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
330 sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
335 m_tag_prepend(m, mtag);
337 dt = (struct ipfw_rule_ref *)(mtag+1);
339 /* Loopback avoidance and state recovery */
343 /* set the starting point. We provide a non-zero slot,
344 * but a non_matching chain_id to skip that info and use
345 * the rulenum/rule_id.
347 dt->slot = 1; /* dummy, chain_id is invalid */
349 dt->rulenum = sin->sin_port+1; /* host format ? */
352 * Find receive interface with the given name, stuffed
353 * (if it exists) in the sin_zero[] field.
354 * The name is user supplied data so don't trust its size
355 * or that it is zero terminated.
357 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
359 if ( i > 0 && i < sizeof(sin->sin_zero))
360 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
363 /* Reinject packet into the system as incoming or outgoing */
364 if (!sin || sin->sin_addr.s_addr == 0) {
365 struct mbuf *options = NULL;
368 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
374 * Don't allow both user specified and setsockopt
375 * options, and don't allow packet length sizes that
378 if ((((ip->ip_hl << 2) != sizeof(struct ip)) &&
379 inp->inp_options != NULL) ||
380 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
387 case IPV6_VERSION >> 4:
389 struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
391 /* Don't allow packet length sizes that will crash */
392 if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
406 /* Send packet to output processing */
407 KMOD_IPSTAT_INC(ips_rawout); /* XXX */
410 mac_inpcb_create_mbuf(inp, m);
413 * Get ready to inject the packet into ip_output().
414 * Just in case socket options were specified on the
415 * divert socket, we duplicate them. This is done
416 * to avoid having to hold the PCB locks over the call
417 * to ip_output(), as doing this results in a number of
418 * lock ordering complexities.
420 * Note that we set the multicast options argument for
421 * ip_output() to NULL since it should be invariant that
422 * they are not present.
424 KASSERT(inp->inp_moptions == NULL,
425 ("multicast options set on a divert socket"));
427 * XXXCSJP: It is unclear to me whether or not it makes
428 * sense for divert sockets to have options. However,
429 * for now we will duplicate them with the INP locks
430 * held so we can use them in ip_output() without
431 * requring a reference to the pcb.
433 if (inp->inp_options != NULL) {
434 options = m_dup(inp->inp_options, M_NOWAIT);
435 if (options == NULL) {
445 error = ip_output(m, options, NULL,
446 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
447 | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
450 case IPV6_VERSION >> 4:
451 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
458 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
459 if (m->m_pkthdr.rcvif == NULL) {
461 * No luck with the name, check by IP address.
462 * Clear the port and the ifname to make sure
463 * there are no distractions for ifa_ifwithaddr.
465 struct epoch_tracker et;
468 bzero(sin->sin_zero, sizeof(sin->sin_zero));
471 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
473 error = EADDRNOTAVAIL;
477 m->m_pkthdr.rcvif = ifa->ifa_ifp;
481 mac_socket_create_mbuf(so, m);
483 /* Send packet to input processing via netisr */
487 * Restore M_BCAST flag when destination address is
488 * broadcast. It is expected by ip_tryforward().
490 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
491 m->m_flags |= M_MCAST;
492 else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
493 m->m_flags |= M_BCAST;
494 netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
497 case IPV6_VERSION >> 4:
498 netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
515 div_attach(struct socket *so, int proto, struct thread *td)
521 KASSERT(inp == NULL, ("div_attach: inp != NULL"));
523 error = priv_check(td, PRIV_NETINET_DIVERT);
527 error = soreserve(so, div_sendspace, div_recvspace);
530 INP_INFO_WLOCK(&V_divcbinfo);
531 error = in_pcballoc(so, &V_divcbinfo);
533 INP_INFO_WUNLOCK(&V_divcbinfo);
536 inp = (struct inpcb *)so->so_pcb;
537 INP_INFO_WUNLOCK(&V_divcbinfo);
538 inp->inp_ip_p = proto;
539 inp->inp_vflag |= INP_IPV4;
540 inp->inp_flags |= INP_HDRINCL;
546 div_detach(struct socket *so)
551 KASSERT(inp != NULL, ("div_detach: inp == NULL"));
552 INP_INFO_WLOCK(&V_divcbinfo);
556 INP_INFO_WUNLOCK(&V_divcbinfo);
560 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
566 KASSERT(inp != NULL, ("div_bind: inp == NULL"));
567 /* in_pcbbind assumes that nam is a sockaddr_in
568 * and in_pcbbind requires a valid address. Since divert
569 * sockets don't we need to make sure the address is
570 * filled in properly.
571 * XXX -- divert should not be abusing in_pcbind
572 * and should probably have its own family.
574 if (nam->sa_family != AF_INET)
576 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
577 INP_INFO_WLOCK(&V_divcbinfo);
579 INP_HASH_WLOCK(&V_divcbinfo);
580 error = in_pcbbind(inp, nam, td->td_ucred);
581 INP_HASH_WUNLOCK(&V_divcbinfo);
583 INP_INFO_WUNLOCK(&V_divcbinfo);
588 div_shutdown(struct socket *so)
593 KASSERT(inp != NULL, ("div_shutdown: inp == NULL"));
601 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
602 struct mbuf *control, struct thread *td)
605 /* Packet must have a header (but that's about it) */
606 if (m->m_len < sizeof (struct ip) &&
607 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
608 KMOD_IPSTAT_INC(ips_toosmall);
614 return div_output(so, m, (struct sockaddr_in *)nam, control);
618 div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
620 struct in_addr faddr;
622 faddr = ((struct sockaddr_in *)sa)->sin_addr;
623 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
625 if (PRC_IS_REDIRECT(cmd))
630 div_pcblist(SYSCTL_HANDLER_ARGS)
633 struct epoch_tracker et;
637 if (req->newptr != 0)
640 if (req->oldptr == 0) {
643 n = V_divcbinfo.ipi_count;
644 n += imax(n / 8, 10);
645 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
649 if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
652 bzero(&xig, sizeof(xig));
653 xig.xig_len = sizeof xig;
654 xig.xig_count = V_divcbinfo.ipi_count;
655 xig.xig_gen = V_divcbinfo.ipi_gencnt;
656 xig.xig_sogen = so_gencnt;
657 error = SYSCTL_OUT(req, &xig, sizeof xig);
662 for (inp = CK_LIST_FIRST(V_divcbinfo.ipi_listhead);
664 inp = CK_LIST_NEXT(inp, inp_list)) {
666 if (inp->inp_gencnt <= xig.xig_gen) {
669 in_pcbtoxinpcb(inp, &xi);
671 error = SYSCTL_OUT(req, &xi, sizeof xi);
679 * Give the user an updated idea of our state.
680 * If the generation differs from what we told
681 * her before, she knows that something happened
682 * while we were processing this request, and it
683 * might be necessary to retry.
685 xig.xig_gen = V_divcbinfo.ipi_gencnt;
686 xig.xig_sogen = so_gencnt;
687 xig.xig_count = V_divcbinfo.ipi_count;
688 error = SYSCTL_OUT(req, &xig, sizeof xig);
695 static SYSCTL_NODE(_net_inet, IPPROTO_DIVERT, divert, CTLFLAG_RW, 0,
697 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLTYPE_OPAQUE | CTLFLAG_RD,
698 NULL, 0, div_pcblist, "S,xinpcb", "List of active divert sockets");
701 struct pr_usrreqs div_usrreqs = {
702 .pru_attach = div_attach,
703 .pru_bind = div_bind,
704 .pru_control = in_control,
705 .pru_detach = div_detach,
706 .pru_peeraddr = in_getpeeraddr,
707 .pru_send = div_send,
708 .pru_shutdown = div_shutdown,
709 .pru_sockaddr = in_getsockaddr,
710 .pru_sosetlabel = in_pcbsosetlabel
713 struct protosw div_protosw = {
715 .pr_protocol = IPPROTO_DIVERT,
716 .pr_flags = PR_ATOMIC|PR_ADDR,
717 .pr_input = div_input,
718 .pr_ctlinput = div_ctlinput,
719 .pr_ctloutput = ip_ctloutput,
721 .pr_usrreqs = &div_usrreqs
725 div_modevent(module_t mod, int type, void *unused)
732 * Protocol will be initialized by pf_proto_register().
733 * We don't have to register ip_protox because we are not
734 * a true IP protocol that goes over the wire.
736 err = pf_proto_register(PF_INET, &div_protosw);
739 ip_divert_ptr = divert_packet;
740 ip_divert_event_tag = EVENTHANDLER_REGISTER(maxsockets_change,
741 div_zone_change, NULL, EVENTHANDLER_PRI_ANY);
745 * IPDIVERT may normally not be unloaded because of the
746 * potential race conditions. Tell kldunload we can't be
747 * unloaded unless the unload is forced.
755 * Module ipdivert can only be unloaded if no sockets are
756 * connected. Maybe this can be changed later to forcefully
757 * disconnect any open sockets.
759 * XXXRW: Note that there is a slight race here, as a new
760 * socket open request could be spinning on the lock and then
761 * we destroy the lock.
763 INP_INFO_WLOCK(&V_divcbinfo);
764 if (V_divcbinfo.ipi_count != 0) {
766 INP_INFO_WUNLOCK(&V_divcbinfo);
769 ip_divert_ptr = NULL;
770 err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
771 INP_INFO_WUNLOCK(&V_divcbinfo);
775 EVENTHANDLER_DEREGISTER(maxsockets_change, ip_divert_event_tag);
784 static moduledata_t ipdivertmod = {
790 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
791 MODULE_DEPEND(ipdivert, ipfw, 3, 3, 3);
792 MODULE_VERSION(ipdivert, 1);