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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>
72 #if defined(SCTP) || defined(SCTP_SUPPORT)
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;
125 static int div_output_inbound(int fmaily, struct socket *so, struct mbuf *m,
126 struct sockaddr_in *sin);
127 static int div_output_outbound(int family, struct socket *so, struct mbuf *m);
130 * Initialize divert connection block queue.
133 div_zone_change(void *tag)
136 uma_zone_set_max(V_divcbinfo.ipi_zone, maxsockets);
140 div_inpcb_init(void *mem, int size, int flags)
142 struct inpcb *inp = mem;
144 INP_LOCK_INIT(inp, "inp", "divinp");
153 * XXX We don't use the hash list for divert IP, but it's easier to
154 * allocate one-entry hash lists than it is to check all over the
155 * place for hashbase == NULL.
157 in_pcbinfo_init(&V_divcbinfo, "div", &V_divcb, 1, 1, "divcb",
158 div_inpcb_init, IPI_HASHFIELDS_NONE);
162 div_destroy(void *unused __unused)
165 in_pcbinfo_destroy(&V_divcbinfo);
167 VNET_SYSUNINIT(divert, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
171 * IPPROTO_DIVERT is not in the real IP protocol number space; this
172 * function should never be called. Just in case, drop any packets.
175 div_input(struct mbuf **mp, int *offp, int proto)
177 struct mbuf *m = *mp;
179 KMOD_IPSTAT_INC(ips_noproto);
181 return (IPPROTO_DONE);
185 * Divert a packet by passing it up to the divert socket at port 'port'.
187 * Setup generic address and protocol structures for div_input routine,
188 * then pass them along with mbuf chain.
191 divert_packet(struct mbuf *m, bool incoming)
197 struct sockaddr_in divsrc;
202 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
208 if (m->m_len < sizeof(struct ip) &&
209 (m = m_pullup(m, sizeof(struct ip))) == NULL)
211 ip = mtod(m, struct ip *);
213 /* Delayed checksums are currently not compatible with divert. */
214 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
215 m = mb_unmapped_to_ext(m);
219 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
221 #if defined(SCTP) || defined(SCTP_SUPPORT)
222 if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
223 m = mb_unmapped_to_ext(m);
226 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
227 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
230 bzero(&divsrc, sizeof(divsrc));
231 divsrc.sin_len = sizeof(divsrc);
232 divsrc.sin_family = AF_INET;
233 /* record matching rule, in host format */
234 divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
236 * Record receive interface address, if any.
237 * But only for incoming packets.
246 /* Find IP address for receive interface */
247 ifp = m->m_pkthdr.rcvif;
248 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
249 if (ifa->ifa_addr->sa_family != AF_INET)
252 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
257 * Record the incoming interface name whenever we have one.
259 if (m->m_pkthdr.rcvif) {
261 * Hide the actual interface name in there in the
262 * sin_zero array. XXX This needs to be moved to a
263 * different sockaddr type for divert, e.g.
264 * sockaddr_div with multiple fields like
265 * sockaddr_dl. Presently we have only 7 bytes
266 * but that will do for now as most interfaces
267 * are 4 or less + 2 or less bytes for unit.
268 * There is probably a faster way of doing this,
269 * possibly taking it from the sockaddr_dl on the iface.
270 * This solves the problem of a P2P link and a LAN interface
271 * having the same address, which can result in the wrong
272 * interface being assigned to the packet when fed back
273 * into the divert socket. Theoretically if the daemon saves
274 * and re-uses the sockaddr_in as suggested in the man pages,
275 * this iface name will come along for the ride.
276 * (see div_output for the other half of this.)
278 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
279 sizeof(divsrc.sin_zero));
282 /* Put packet on socket queue, if any */
284 nport = htons((u_int16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
285 CK_LIST_FOREACH(inp, &V_divcb, inp_list) {
286 /* XXX why does only one socket match? */
287 if (inp->inp_lport == nport) {
289 if (__predict_false(inp->inp_flags2 & INP_FREED)) {
293 sa = inp->inp_socket;
294 SOCKBUF_LOCK(&sa->so_rcv);
295 if (sbappendaddr_locked(&sa->so_rcv,
296 (struct sockaddr *)&divsrc, m,
297 (struct mbuf *)0) == 0) {
298 SOCKBUF_UNLOCK(&sa->so_rcv);
299 sa = NULL; /* force mbuf reclaim below */
301 sorwakeup_locked(sa);
308 KMOD_IPSTAT_INC(ips_noproto);
309 KMOD_IPSTAT_DEC(ips_delivered);
314 * Deliver packet back into the IP processing machinery.
316 * If no address specified, or address is 0.0.0.0, send to ip_output();
317 * otherwise, send to ip_input() and mark as having been received on
318 * the interface with that address.
321 div_output(struct socket *so, struct mbuf *m, struct sockaddr_in *sin,
322 struct mbuf *control)
324 struct epoch_tracker et;
327 struct ipfw_rule_ref *dt;
331 * An mbuf may hasn't come from userland, but we pretend
334 m->m_pkthdr.rcvif = NULL;
336 M_SETFIB(m, so->so_fibnum);
339 m_freem(control); /* XXX */
341 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
343 /* this should be normal */
344 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
345 sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
350 m_tag_prepend(m, mtag);
352 dt = (struct ipfw_rule_ref *)(mtag+1);
354 /* Loopback avoidance and state recovery */
358 /* set the starting point. We provide a non-zero slot,
359 * but a non_matching chain_id to skip that info and use
360 * the rulenum/rule_id.
362 dt->slot = 1; /* dummy, chain_id is invalid */
364 dt->rulenum = sin->sin_port+1; /* host format ? */
366 /* XXX: broken for IPv6 */
368 * Find receive interface with the given name, stuffed
369 * (if it exists) in the sin_zero[] field.
370 * The name is user supplied data so don't trust its size
371 * or that it is zero terminated.
373 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
375 if ( i > 0 && i < sizeof(sin->sin_zero))
376 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
379 ip = mtod(m, struct ip *);
385 case IPV6_VERSION >> 4:
391 return (EAFNOSUPPORT);
394 /* Reinject packet into the system as incoming or outgoing */
396 if (!sin || sin->sin_addr.s_addr == 0) {
397 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
398 error = div_output_outbound(family, so, m);
400 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
401 error = div_output_inbound(family, so, m, sin);
412 * Sends mbuf @m to the wire via ip[6]_output().
414 * Returns 0 on success, @m is consumed.
415 * On failure, returns error code. It is caller responsibility to free @m.
418 div_output_outbound(int family, struct socket *so, struct mbuf *m)
420 struct ip *const ip = mtod(m, struct ip *);
421 struct mbuf *options;
430 * Don't allow both user specified and setsockopt
431 * options, and don't allow packet length sizes that
434 if ((((ip->ip_hl << 2) != sizeof(struct ip)) &&
435 inp->inp_options != NULL) ||
436 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
444 struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
446 /* Don't allow packet length sizes that will crash */
447 if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
456 /* Send packet to output processing */
457 KMOD_IPSTAT_INC(ips_rawout); /* XXX */
460 mac_inpcb_create_mbuf(inp, m);
463 * Get ready to inject the packet into ip_output().
464 * Just in case socket options were specified on the
465 * divert socket, we duplicate them. This is done
466 * to avoid having to hold the PCB locks over the call
467 * to ip_output(), as doing this results in a number of
468 * lock ordering complexities.
470 * Note that we set the multicast options argument for
471 * ip_output() to NULL since it should be invariant that
472 * they are not present.
474 KASSERT(inp->inp_moptions == NULL,
475 ("multicast options set on a divert socket"));
477 * XXXCSJP: It is unclear to me whether or not it makes
478 * sense for divert sockets to have options. However,
479 * for now we will duplicate them with the INP locks
480 * held so we can use them in ip_output() without
481 * requring a reference to the pcb.
484 if (inp->inp_options != NULL) {
485 options = m_dup(inp->inp_options, M_NOWAIT);
486 if (options == NULL) {
496 error = ip_output(m, options, NULL,
497 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
498 | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
502 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
513 * Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
515 * Returns 0 on success, @m is consumed.
516 * Returns error code on failure. It is caller responsibility to free @m.
519 div_output_inbound(int family, struct socket *so, struct mbuf *m,
520 struct sockaddr_in *sin)
525 if (m->m_pkthdr.rcvif == NULL) {
527 * No luck with the name, check by IP address.
528 * Clear the port and the ifname to make sure
529 * there are no distractions for ifa_ifwithaddr.
532 /* XXX: broken for IPv6 */
533 bzero(sin->sin_zero, sizeof(sin->sin_zero));
535 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
537 return (EADDRNOTAVAIL);
538 m->m_pkthdr.rcvif = ifa->ifa_ifp;
541 mac_socket_create_mbuf(so, m);
543 /* Send packet to input processing via netisr */
546 ip = mtod(m, struct ip *);
548 * Restore M_BCAST flag when destination address is
549 * broadcast. It is expected by ip_tryforward().
551 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
552 m->m_flags |= M_MCAST;
553 else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
554 m->m_flags |= M_BCAST;
555 netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
559 netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
570 div_attach(struct socket *so, int proto, struct thread *td)
576 KASSERT(inp == NULL, ("div_attach: inp != NULL"));
578 error = priv_check(td, PRIV_NETINET_DIVERT);
582 error = soreserve(so, div_sendspace, div_recvspace);
585 INP_INFO_WLOCK(&V_divcbinfo);
586 error = in_pcballoc(so, &V_divcbinfo);
588 INP_INFO_WUNLOCK(&V_divcbinfo);
591 inp = (struct inpcb *)so->so_pcb;
592 INP_INFO_WUNLOCK(&V_divcbinfo);
593 inp->inp_ip_p = proto;
594 inp->inp_vflag |= INP_IPV4;
595 inp->inp_flags |= INP_HDRINCL;
601 div_detach(struct socket *so)
606 KASSERT(inp != NULL, ("div_detach: inp == NULL"));
607 INP_INFO_WLOCK(&V_divcbinfo);
611 INP_INFO_WUNLOCK(&V_divcbinfo);
615 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
621 KASSERT(inp != NULL, ("div_bind: inp == NULL"));
622 /* in_pcbbind assumes that nam is a sockaddr_in
623 * and in_pcbbind requires a valid address. Since divert
624 * sockets don't we need to make sure the address is
625 * filled in properly.
626 * XXX -- divert should not be abusing in_pcbind
627 * and should probably have its own family.
629 if (nam->sa_family != AF_INET)
631 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
632 INP_INFO_WLOCK(&V_divcbinfo);
634 INP_HASH_WLOCK(&V_divcbinfo);
635 error = in_pcbbind(inp, nam, td->td_ucred);
636 INP_HASH_WUNLOCK(&V_divcbinfo);
638 INP_INFO_WUNLOCK(&V_divcbinfo);
643 div_shutdown(struct socket *so)
648 KASSERT(inp != NULL, ("div_shutdown: inp == NULL"));
656 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
657 struct mbuf *control, struct thread *td)
660 /* Packet must have a header (but that's about it) */
661 if (m->m_len < sizeof (struct ip) &&
662 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
663 KMOD_IPSTAT_INC(ips_toosmall);
669 return div_output(so, m, (struct sockaddr_in *)nam, control);
673 div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
675 struct in_addr faddr;
677 faddr = ((struct sockaddr_in *)sa)->sin_addr;
678 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
680 if (PRC_IS_REDIRECT(cmd))
685 div_pcblist(SYSCTL_HANDLER_ARGS)
688 struct epoch_tracker et;
692 if (req->newptr != 0)
695 if (req->oldptr == 0) {
698 n = V_divcbinfo.ipi_count;
699 n += imax(n / 8, 10);
700 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
704 if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
707 bzero(&xig, sizeof(xig));
708 xig.xig_len = sizeof xig;
709 xig.xig_count = V_divcbinfo.ipi_count;
710 xig.xig_gen = V_divcbinfo.ipi_gencnt;
711 xig.xig_sogen = so_gencnt;
712 error = SYSCTL_OUT(req, &xig, sizeof xig);
717 for (inp = CK_LIST_FIRST(V_divcbinfo.ipi_listhead);
719 inp = CK_LIST_NEXT(inp, inp_list)) {
721 if (inp->inp_gencnt <= xig.xig_gen) {
724 in_pcbtoxinpcb(inp, &xi);
726 error = SYSCTL_OUT(req, &xi, sizeof xi);
734 * Give the user an updated idea of our state.
735 * If the generation differs from what we told
736 * her before, she knows that something happened
737 * while we were processing this request, and it
738 * might be necessary to retry.
740 xig.xig_gen = V_divcbinfo.ipi_gencnt;
741 xig.xig_sogen = so_gencnt;
742 xig.xig_count = V_divcbinfo.ipi_count;
743 error = SYSCTL_OUT(req, &xig, sizeof xig);
750 static SYSCTL_NODE(_net_inet, IPPROTO_DIVERT, divert,
751 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
753 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist,
754 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE,
755 NULL, 0, div_pcblist, "S,xinpcb",
756 "List of active divert sockets");
759 struct pr_usrreqs div_usrreqs = {
760 .pru_attach = div_attach,
761 .pru_bind = div_bind,
762 .pru_control = in_control,
763 .pru_detach = div_detach,
764 .pru_peeraddr = in_getpeeraddr,
765 .pru_send = div_send,
766 .pru_shutdown = div_shutdown,
767 .pru_sockaddr = in_getsockaddr,
768 .pru_sosetlabel = in_pcbsosetlabel
771 struct protosw div_protosw = {
773 .pr_protocol = IPPROTO_DIVERT,
774 .pr_flags = PR_ATOMIC|PR_ADDR,
775 .pr_input = div_input,
776 .pr_ctlinput = div_ctlinput,
777 .pr_ctloutput = ip_ctloutput,
779 .pr_usrreqs = &div_usrreqs
783 div_modevent(module_t mod, int type, void *unused)
790 * Protocol will be initialized by pf_proto_register().
791 * We don't have to register ip_protox because we are not
792 * a true IP protocol that goes over the wire.
794 err = pf_proto_register(PF_INET, &div_protosw);
797 ip_divert_ptr = divert_packet;
798 ip_divert_event_tag = EVENTHANDLER_REGISTER(maxsockets_change,
799 div_zone_change, NULL, EVENTHANDLER_PRI_ANY);
803 * IPDIVERT may normally not be unloaded because of the
804 * potential race conditions. Tell kldunload we can't be
805 * unloaded unless the unload is forced.
813 * Module ipdivert can only be unloaded if no sockets are
814 * connected. Maybe this can be changed later to forcefully
815 * disconnect any open sockets.
817 * XXXRW: Note that there is a slight race here, as a new
818 * socket open request could be spinning on the lock and then
819 * we destroy the lock.
821 INP_INFO_WLOCK(&V_divcbinfo);
822 if (V_divcbinfo.ipi_count != 0) {
824 INP_INFO_WUNLOCK(&V_divcbinfo);
827 ip_divert_ptr = NULL;
828 err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
829 INP_INFO_WUNLOCK(&V_divcbinfo);
833 EVENTHANDLER_DEREGISTER(maxsockets_change, ip_divert_event_tag);
842 static moduledata_t ipdivertmod = {
848 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
849 MODULE_DEPEND(ipdivert, ipfw, 3, 3, 3);
850 MODULE_VERSION(ipdivert, 1);