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30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #if !defined(KLD_MODULE)
37 #error "IPDIVERT requires INET."
40 #include "opt_inet6.h"
42 #include <sys/param.h>
43 #include <sys/kernel.h>
45 #include <sys/malloc.h>
47 #include <sys/module.h>
48 #include <sys/kernel.h>
51 #include <sys/protosw.h>
52 #include <sys/socket.h>
53 #include <sys/socketvar.h>
54 #include <sys/sysctl.h>
58 #include <net/netisr.h>
60 #include <netinet/in.h>
61 #include <netinet/in_pcb.h>
62 #include <netinet/in_systm.h>
63 #include <netinet/in_var.h>
64 #include <netinet/ip.h>
65 #include <netinet/ip_var.h>
67 #include <netinet/ip6.h>
68 #include <netinet6/ip6_var.h>
71 #include <netinet/sctp_crc32.h>
74 #include <security/mac/mac_framework.h>
81 * Allocate enough space to hold a full IP packet
83 #define DIVSNDQ (65536 + 100)
84 #define DIVRCVQ (65536 + 100)
87 * Divert sockets work in conjunction with ipfw or other packet filters,
88 * see the divert(4) manpage for features.
89 * Packets are selected by the packet filter and tagged with an
90 * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
91 * the packet filter) and information on the matching filter rule for
92 * subsequent reinjection. The divert_port is used to put the packet
93 * on the corresponding divert socket, while the rule number is passed
94 * up (at least partially) as the sin_port in the struct sockaddr.
96 * Packets written to the divert socket carry in sin_addr a
97 * destination address, and in sin_port the number of the filter rule
98 * after which to continue processing.
99 * If the destination address is INADDR_ANY, the packet is treated as
100 * as outgoing and sent to ip_output(); otherwise it is treated as
101 * incoming and sent to ip_input().
102 * Further, sin_zero carries some information on the interface,
103 * which can be used in the reinject -- see comments in the code.
105 * On reinjection, processing in ip_input() and ip_output()
106 * will be exactly the same as for the original packet, except that
107 * packet filter processing will start at the rule number after the one
108 * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
109 * will apply the entire ruleset to the packet).
112 /* Internal variables. */
113 static VNET_DEFINE(struct inpcbhead, divcb);
114 static VNET_DEFINE(struct inpcbinfo, divcbinfo);
116 #define V_divcb VNET(divcb)
117 #define V_divcbinfo VNET(divcbinfo)
119 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
120 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
122 static eventhandler_tag ip_divert_event_tag;
125 * Initialize divert connection block queue.
128 div_zone_change(void *tag)
131 uma_zone_set_max(V_divcbinfo.ipi_zone, maxsockets);
135 div_inpcb_init(void *mem, int size, int flags)
137 struct inpcb *inp = mem;
139 INP_LOCK_INIT(inp, "inp", "divinp");
144 div_inpcb_fini(void *mem, int size)
146 struct inpcb *inp = mem;
148 INP_LOCK_DESTROY(inp);
156 * XXX We don't use the hash list for divert IP, but it's easier to
157 * allocate one-entry hash lists than it is to check all over the
158 * place for hashbase == NULL.
160 in_pcbinfo_init(&V_divcbinfo, "div", &V_divcb, 1, 1, "divcb",
161 div_inpcb_init, div_inpcb_fini, UMA_ZONE_NOFREE,
162 IPI_HASHFIELDS_NONE);
169 in_pcbinfo_destroy(&V_divcbinfo);
173 * IPPROTO_DIVERT is not in the real IP protocol number space; this
174 * function should never be called. Just in case, drop any packets.
177 div_input(struct mbuf *m, int off)
180 KMOD_IPSTAT_INC(ips_noproto);
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, int incoming)
197 struct sockaddr_in divsrc;
200 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
206 if (m->m_len < sizeof(struct ip) &&
207 (m = m_pullup(m, sizeof(struct ip))) == 0)
209 ip = mtod(m, struct ip *);
211 /* Delayed checksums are currently not compatible with divert. */
212 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
213 ip->ip_len = ntohs(ip->ip_len);
215 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
216 ip->ip_len = htons(ip->ip_len);
219 if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
220 ip->ip_len = ntohs(ip->ip_len);
221 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
222 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
223 ip->ip_len = htons(ip->ip_len);
226 bzero(&divsrc, sizeof(divsrc));
227 divsrc.sin_len = sizeof(divsrc);
228 divsrc.sin_family = AF_INET;
229 /* record matching rule, in host format */
230 divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
232 * Record receive interface address, if any.
233 * But only for incoming packets.
242 /* Find IP address for receive interface */
243 ifp = m->m_pkthdr.rcvif;
245 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
246 if (ifa->ifa_addr->sa_family != AF_INET)
249 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
252 if_addr_runlock(ifp);
255 * Record the incoming interface name whenever we have one.
257 if (m->m_pkthdr.rcvif) {
259 * Hide the actual interface name in there in the
260 * sin_zero array. XXX This needs to be moved to a
261 * different sockaddr type for divert, e.g.
262 * sockaddr_div with multiple fields like
263 * sockaddr_dl. Presently we have only 7 bytes
264 * but that will do for now as most interfaces
265 * are 4 or less + 2 or less bytes for unit.
266 * There is probably a faster way of doing this,
267 * possibly taking it from the sockaddr_dl on the iface.
268 * This solves the problem of a P2P link and a LAN interface
269 * having the same address, which can result in the wrong
270 * interface being assigned to the packet when fed back
271 * into the divert socket. Theoretically if the daemon saves
272 * and re-uses the sockaddr_in as suggested in the man pages,
273 * this iface name will come along for the ride.
274 * (see div_output for the other half of this.)
276 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
277 sizeof(divsrc.sin_zero));
280 /* Put packet on socket queue, if any */
282 nport = htons((u_int16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
283 INP_INFO_RLOCK(&V_divcbinfo);
284 LIST_FOREACH(inp, &V_divcb, inp_list) {
285 /* XXX why does only one socket match? */
286 if (inp->inp_lport == nport) {
288 sa = inp->inp_socket;
289 SOCKBUF_LOCK(&sa->so_rcv);
290 if (sbappendaddr_locked(&sa->so_rcv,
291 (struct sockaddr *)&divsrc, m,
292 (struct mbuf *)0) == 0) {
293 SOCKBUF_UNLOCK(&sa->so_rcv);
294 sa = NULL; /* force mbuf reclaim below */
296 sorwakeup_locked(sa);
301 INP_INFO_RUNLOCK(&V_divcbinfo);
304 KMOD_IPSTAT_INC(ips_noproto);
305 KMOD_IPSTAT_DEC(ips_delivered);
310 * Deliver packet back into the IP processing machinery.
312 * If no address specified, or address is 0.0.0.0, send to ip_output();
313 * otherwise, send to ip_input() and mark as having been received on
314 * the interface with that address.
317 div_output(struct socket *so, struct mbuf *m, struct sockaddr_in *sin,
318 struct mbuf *control)
320 struct ip *const ip = mtod(m, struct ip *);
322 struct ipfw_rule_ref *dt;
326 * An mbuf may hasn't come from userland, but we pretend
329 m->m_pkthdr.rcvif = NULL;
331 M_SETFIB(m, so->so_fibnum);
334 m_freem(control); /* XXX */
336 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
338 /* this should be normal */
339 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
340 sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
345 m_tag_prepend(m, mtag);
347 dt = (struct ipfw_rule_ref *)(mtag+1);
349 /* Loopback avoidance and state recovery */
353 /* set the starting point. We provide a non-zero slot,
354 * but a non_matching chain_id to skip that info and use
355 * the rulenum/rule_id.
357 dt->slot = 1; /* dummy, chain_id is invalid */
359 dt->rulenum = sin->sin_port+1; /* host format ? */
362 * Find receive interface with the given name, stuffed
363 * (if it exists) in the sin_zero[] field.
364 * The name is user supplied data so don't trust its size
365 * or that it is zero terminated.
367 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
369 if ( i > 0 && i < sizeof(sin->sin_zero))
370 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
373 /* Reinject packet into the system as incoming or outgoing */
374 if (!sin || sin->sin_addr.s_addr == 0) {
375 struct mbuf *options = NULL;
378 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
384 * Don't allow both user specified and setsockopt
385 * options, and don't allow packet length sizes that
388 if ((((ip->ip_hl << 2) != sizeof(struct ip)) &&
389 inp->inp_options != NULL) ||
390 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
396 /* Convert fields to host order for ip_output() */
397 ip->ip_len = ntohs(ip->ip_len);
398 ip->ip_off = ntohs(ip->ip_off);
401 case IPV6_VERSION >> 4:
403 struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
405 /* Don't allow packet length sizes that will crash */
406 if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
412 ip6->ip6_plen = ntohs(ip6->ip6_plen);
422 /* Send packet to output processing */
423 KMOD_IPSTAT_INC(ips_rawout); /* XXX */
426 mac_inpcb_create_mbuf(inp, m);
429 * Get ready to inject the packet into ip_output().
430 * Just in case socket options were specified on the
431 * divert socket, we duplicate them. This is done
432 * to avoid having to hold the PCB locks over the call
433 * to ip_output(), as doing this results in a number of
434 * lock ordering complexities.
436 * Note that we set the multicast options argument for
437 * ip_output() to NULL since it should be invariant that
438 * they are not present.
440 KASSERT(inp->inp_moptions == NULL,
441 ("multicast options set on a divert socket"));
443 * XXXCSJP: It is unclear to me whether or not it makes
444 * sense for divert sockets to have options. However,
445 * for now we will duplicate them with the INP locks
446 * held so we can use them in ip_output() without
447 * requring a reference to the pcb.
449 if (inp->inp_options != NULL) {
450 options = m_dup(inp->inp_options, M_NOWAIT);
451 if (options == NULL) {
461 error = ip_output(m, options, NULL,
462 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
463 | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
466 case IPV6_VERSION >> 4:
467 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
474 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
475 if (m->m_pkthdr.rcvif == NULL) {
477 * No luck with the name, check by IP address.
478 * Clear the port and the ifname to make sure
479 * there are no distractions for ifa_ifwithaddr.
483 bzero(sin->sin_zero, sizeof(sin->sin_zero));
485 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
487 error = EADDRNOTAVAIL;
490 m->m_pkthdr.rcvif = ifa->ifa_ifp;
494 mac_socket_create_mbuf(so, m);
496 /* Send packet to input processing via netisr */
499 netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
502 case IPV6_VERSION >> 4:
503 netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
520 div_attach(struct socket *so, int proto, struct thread *td)
526 KASSERT(inp == NULL, ("div_attach: inp != NULL"));
528 error = priv_check(td, PRIV_NETINET_DIVERT);
532 error = soreserve(so, div_sendspace, div_recvspace);
535 INP_INFO_WLOCK(&V_divcbinfo);
536 error = in_pcballoc(so, &V_divcbinfo);
538 INP_INFO_WUNLOCK(&V_divcbinfo);
541 inp = (struct inpcb *)so->so_pcb;
542 INP_INFO_WUNLOCK(&V_divcbinfo);
543 inp->inp_ip_p = proto;
544 inp->inp_vflag |= INP_IPV4;
545 inp->inp_flags |= INP_HDRINCL;
551 div_detach(struct socket *so)
556 KASSERT(inp != NULL, ("div_detach: inp == NULL"));
557 INP_INFO_WLOCK(&V_divcbinfo);
561 INP_INFO_WUNLOCK(&V_divcbinfo);
565 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
571 KASSERT(inp != NULL, ("div_bind: inp == NULL"));
572 /* in_pcbbind assumes that nam is a sockaddr_in
573 * and in_pcbbind requires a valid address. Since divert
574 * sockets don't we need to make sure the address is
575 * filled in properly.
576 * XXX -- divert should not be abusing in_pcbind
577 * and should probably have its own family.
579 if (nam->sa_family != AF_INET)
581 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
582 INP_INFO_WLOCK(&V_divcbinfo);
584 INP_HASH_WLOCK(&V_divcbinfo);
585 error = in_pcbbind(inp, nam, td->td_ucred);
586 INP_HASH_WUNLOCK(&V_divcbinfo);
588 INP_INFO_WUNLOCK(&V_divcbinfo);
593 div_shutdown(struct socket *so)
598 KASSERT(inp != NULL, ("div_shutdown: inp == NULL"));
606 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
607 struct mbuf *control, struct thread *td)
610 /* Packet must have a header (but that's about it) */
611 if (m->m_len < sizeof (struct ip) &&
612 (m = m_pullup(m, sizeof (struct ip))) == 0) {
613 KMOD_IPSTAT_INC(ips_toosmall);
619 return div_output(so, m, (struct sockaddr_in *)nam, control);
623 div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
625 struct in_addr faddr;
627 faddr = ((struct sockaddr_in *)sa)->sin_addr;
628 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
630 if (PRC_IS_REDIRECT(cmd))
635 div_pcblist(SYSCTL_HANDLER_ARGS)
638 struct inpcb *inp, **inp_list;
643 * The process of preparing the TCB list is too time-consuming and
644 * resource-intensive to repeat twice on every request.
646 if (req->oldptr == 0) {
647 n = V_divcbinfo.ipi_count;
648 n += imax(n / 8, 10);
649 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
653 if (req->newptr != 0)
657 * OK, now we're committed to doing something.
659 INP_INFO_RLOCK(&V_divcbinfo);
660 gencnt = V_divcbinfo.ipi_gencnt;
661 n = V_divcbinfo.ipi_count;
662 INP_INFO_RUNLOCK(&V_divcbinfo);
664 error = sysctl_wire_old_buffer(req,
665 2 * sizeof(xig) + n*sizeof(struct xinpcb));
669 xig.xig_len = sizeof xig;
671 xig.xig_gen = gencnt;
672 xig.xig_sogen = so_gencnt;
673 error = SYSCTL_OUT(req, &xig, sizeof xig);
677 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
681 INP_INFO_RLOCK(&V_divcbinfo);
682 for (inp = LIST_FIRST(V_divcbinfo.ipi_listhead), i = 0; inp && i < n;
683 inp = LIST_NEXT(inp, inp_list)) {
685 if (inp->inp_gencnt <= gencnt &&
686 cr_canseeinpcb(req->td->td_ucred, inp) == 0) {
692 INP_INFO_RUNLOCK(&V_divcbinfo);
696 for (i = 0; i < n; i++) {
699 if (inp->inp_gencnt <= gencnt) {
701 bzero(&xi, sizeof(xi));
702 xi.xi_len = sizeof xi;
703 /* XXX should avoid extra copy */
704 bcopy(inp, &xi.xi_inp, sizeof *inp);
706 sotoxsocket(inp->inp_socket, &xi.xi_socket);
708 error = SYSCTL_OUT(req, &xi, sizeof xi);
712 INP_INFO_WLOCK(&V_divcbinfo);
713 for (i = 0; i < n; i++) {
716 if (!in_pcbrele_rlocked(inp))
719 INP_INFO_WUNLOCK(&V_divcbinfo);
723 * Give the user an updated idea of our state.
724 * If the generation differs from what we told
725 * her before, she knows that something happened
726 * while we were processing this request, and it
727 * might be necessary to retry.
729 INP_INFO_RLOCK(&V_divcbinfo);
730 xig.xig_gen = V_divcbinfo.ipi_gencnt;
731 xig.xig_sogen = so_gencnt;
732 xig.xig_count = V_divcbinfo.ipi_count;
733 INP_INFO_RUNLOCK(&V_divcbinfo);
734 error = SYSCTL_OUT(req, &xig, sizeof xig);
736 free(inp_list, M_TEMP);
741 static SYSCTL_NODE(_net_inet, IPPROTO_DIVERT, divert, CTLFLAG_RW, 0,
743 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLTYPE_OPAQUE | CTLFLAG_RD,
744 NULL, 0, div_pcblist, "S,xinpcb", "List of active divert sockets");
747 struct pr_usrreqs div_usrreqs = {
748 .pru_attach = div_attach,
749 .pru_bind = div_bind,
750 .pru_control = in_control,
751 .pru_detach = div_detach,
752 .pru_peeraddr = in_getpeeraddr,
753 .pru_send = div_send,
754 .pru_shutdown = div_shutdown,
755 .pru_sockaddr = in_getsockaddr,
756 .pru_sosetlabel = in_pcbsosetlabel
759 struct protosw div_protosw = {
761 .pr_protocol = IPPROTO_DIVERT,
762 .pr_flags = PR_ATOMIC|PR_ADDR,
763 .pr_input = div_input,
764 .pr_ctlinput = div_ctlinput,
765 .pr_ctloutput = ip_ctloutput,
768 .pr_destroy = div_destroy,
770 .pr_usrreqs = &div_usrreqs
774 div_modevent(module_t mod, int type, void *unused)
784 * Protocol will be initialized by pf_proto_register().
785 * We don't have to register ip_protox because we are not
786 * a true IP protocol that goes over the wire.
788 err = pf_proto_register(PF_INET, &div_protosw);
791 ip_divert_ptr = divert_packet;
792 ip_divert_event_tag = EVENTHANDLER_REGISTER(maxsockets_change,
793 div_zone_change, NULL, EVENTHANDLER_PRI_ANY);
797 * IPDIVERT may normally not be unloaded because of the
798 * potential race conditions. Tell kldunload we can't be
799 * unloaded unless the unload is forced.
811 * Module ipdivert can only be unloaded if no sockets are
812 * connected. Maybe this can be changed later to forcefully
813 * disconnect any open sockets.
815 * XXXRW: Note that there is a slight race here, as a new
816 * socket open request could be spinning on the lock and then
817 * we destroy the lock.
819 INP_INFO_WLOCK(&V_divcbinfo);
820 n = V_divcbinfo.ipi_count;
823 INP_INFO_WUNLOCK(&V_divcbinfo);
826 ip_divert_ptr = NULL;
827 err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
828 INP_INFO_WUNLOCK(&V_divcbinfo);
830 EVENTHANDLER_DEREGISTER(maxsockets_change, ip_divert_event_tag);
840 static moduledata_t ipdivertmod = {
846 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
847 MODULE_DEPEND(ipdivert, ipfw, 2, 2, 2);
848 MODULE_VERSION(ipdivert, 1);