2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1993
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32 #include <sys/cdefs.h>
34 #include "opt_inet6.h"
37 #include <sys/param.h>
38 #include <sys/eventhandler.h>
39 #include <sys/kernel.h>
41 #include <sys/malloc.h>
43 #include <sys/module.h>
44 #include <sys/kernel.h>
47 #include <sys/domain.h>
48 #include <sys/protosw.h>
49 #include <sys/socket.h>
50 #include <sys/socketvar.h>
51 #include <sys/sysctl.h>
55 #include <net/if_var.h>
56 #include <net/if_private.h>
57 #include <net/netisr.h>
59 #include <netinet/in.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/in_systm.h>
62 #include <netinet/in_var.h>
63 #include <netinet/ip.h>
64 #include <netinet/ip_var.h>
65 #include <netinet/ip_divert.h>
67 #include <netinet/ip6.h>
68 #include <netinet6/ip6_var.h>
70 #if defined(SCTP) || defined(SCTP_SUPPORT)
71 #include <netinet/sctp_crc32.h>
74 #include <security/mac/mac_framework.h>
80 * Allocate enough space to hold a full IP packet
82 #define DIVSNDQ (65536 + 100)
83 #define DIVRCVQ (65536 + 100)
86 * Usually a system has very few divert ports. Previous implementation
89 #define DIVHASHSIZE (1 << 3) /* 8 entries, one cache line. */
90 #define DIVHASH(port) (port % DIVHASHSIZE)
91 #define DCBHASH(dcb) ((dcb)->dcb_port % DIVHASHSIZE)
94 * Divert sockets work in conjunction with ipfw or other packet filters,
95 * see the divert(4) manpage for features.
96 * Packets are selected by the packet filter and tagged with an
97 * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
98 * the packet filter) and information on the matching filter rule for
99 * subsequent reinjection. The divert_port is used to put the packet
100 * on the corresponding divert socket, while the rule number is passed
101 * up (at least partially) as the sin_port in the struct sockaddr.
103 * Packets written to the divert socket carry in sin_addr a
104 * destination address, and in sin_port the number of the filter rule
105 * after which to continue processing.
106 * If the destination address is INADDR_ANY, the packet is treated as
107 * as outgoing and sent to ip_output(); otherwise it is treated as
108 * incoming and sent to ip_input().
109 * Further, sin_zero carries some information on the interface,
110 * which can be used in the reinject -- see comments in the code.
112 * On reinjection, processing in ip_input() and ip_output()
113 * will be exactly the same as for the original packet, except that
114 * packet filter processing will start at the rule number after the one
115 * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
116 * will apply the entire ruleset to the packet).
118 static SYSCTL_NODE(_net_inet, OID_AUTO, divert, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
121 VNET_PCPUSTAT_DEFINE_STATIC(struct divstat, divstat);
122 VNET_PCPUSTAT_SYSINIT(divstat);
124 VNET_PCPUSTAT_SYSUNINIT(divstat);
126 SYSCTL_VNET_PCPUSTAT(_net_inet_divert, OID_AUTO, stats, struct divstat,
127 divstat, "divert(4) socket statistics");
128 #define DIVSTAT_INC(name) \
129 VNET_PCPUSTAT_ADD(struct divstat, divstat, div_ ## name, 1)
131 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
132 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
134 static int div_output_inbound(int fmaily, struct socket *so, struct mbuf *m,
135 struct sockaddr_in *sin);
136 static int div_output_outbound(int family, struct socket *so, struct mbuf *m);
140 SLIST_ENTRY(divcb) dcb_next;
142 #define DCB_UNBOUND ((intptr_t)-1)
144 struct socket *dcb_socket;
147 struct epoch_context dcb_epochctx;
150 SLIST_HEAD(divhashhead, divcb);
152 VNET_DEFINE_STATIC(struct divhashhead, divhash[DIVHASHSIZE]) = {};
153 #define V_divhash VNET(divhash)
154 VNET_DEFINE_STATIC(uint64_t, dcb_count) = 0;
155 #define V_dcb_count VNET(dcb_count)
156 VNET_DEFINE_STATIC(uint64_t, dcb_gencnt) = 0;
157 #define V_dcb_gencnt VNET(dcb_gencnt)
159 static struct mtx divert_mtx;
160 MTX_SYSINIT(divert, &divert_mtx, "divert(4) socket pcb lists", MTX_DEF);
161 #define DIVERT_LOCK() mtx_lock(&divert_mtx)
162 #define DIVERT_UNLOCK() mtx_unlock(&divert_mtx)
165 * Divert a packet by passing it up to the divert socket at port 'port'.
168 divert_packet(struct mbuf *m, bool incoming)
172 struct sockaddr_in divsrc;
177 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
183 if (m->m_len < sizeof(struct ip) &&
184 (m = m_pullup(m, sizeof(struct ip))) == NULL)
187 /* Delayed checksums are currently not compatible with divert. */
188 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
190 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
192 #if defined(SCTP) || defined(SCTP_SUPPORT)
193 if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
196 ip = mtod(m, struct ip *);
197 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
198 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
203 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
204 in6_delayed_cksum(m, m->m_pkthdr.len -
205 sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
206 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
208 #if defined(SCTP) || defined(SCTP_SUPPORT)
209 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
210 sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
211 m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
215 bzero(&divsrc, sizeof(divsrc));
216 divsrc.sin_len = sizeof(divsrc);
217 divsrc.sin_family = AF_INET;
218 /* record matching rule, in host format */
219 divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
221 * Record receive interface address, if any.
222 * But only for incoming packets.
231 /* Find IP address for receive interface */
232 ifp = m->m_pkthdr.rcvif;
233 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
234 if (ifa->ifa_addr->sa_family != AF_INET)
237 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
242 * Record the incoming interface name whenever we have one.
244 if (m->m_pkthdr.rcvif) {
246 * Hide the actual interface name in there in the
247 * sin_zero array. XXX This needs to be moved to a
248 * different sockaddr type for divert, e.g.
249 * sockaddr_div with multiple fields like
250 * sockaddr_dl. Presently we have only 7 bytes
251 * but that will do for now as most interfaces
252 * are 4 or less + 2 or less bytes for unit.
253 * There is probably a faster way of doing this,
254 * possibly taking it from the sockaddr_dl on the iface.
255 * This solves the problem of a P2P link and a LAN interface
256 * having the same address, which can result in the wrong
257 * interface being assigned to the packet when fed back
258 * into the divert socket. Theoretically if the daemon saves
259 * and re-uses the sockaddr_in as suggested in the man pages,
260 * this iface name will come along for the ride.
261 * (see div_output for the other half of this.)
263 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
264 sizeof(divsrc.sin_zero));
267 /* Put packet on socket queue, if any */
268 nport = htons((uint16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
269 SLIST_FOREACH(dcb, &V_divhash[DIVHASH(nport)], dcb_next)
270 if (dcb->dcb_port == nport)
274 struct socket *sa = dcb->dcb_socket;
276 SOCKBUF_LOCK(&sa->so_rcv);
277 if (sbappendaddr_locked(&sa->so_rcv,
278 (struct sockaddr *)&divsrc, m, NULL) == 0) {
279 soroverflow_locked(sa);
282 sorwakeup_locked(sa);
283 DIVSTAT_INC(diverted);
292 * Deliver packet back into the IP processing machinery.
294 * If no address specified, or address is 0.0.0.0, send to ip_output();
295 * otherwise, send to ip_input() and mark as having been received on
296 * the interface with that address.
299 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
300 struct mbuf *control, struct thread *td)
302 struct epoch_tracker et;
303 struct sockaddr_in *sin = (struct sockaddr_in *)nam;
306 struct ipfw_rule_ref *dt;
312 /* Packet must have a header (but that's about it) */
313 if (m->m_len < sizeof (struct ip) &&
314 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
320 if (sin->sin_family != AF_INET) {
322 return (EAFNOSUPPORT);
324 if (sin->sin_len != sizeof(*sin)) {
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);
338 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
340 /* this should be normal */
341 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
342 sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
347 m_tag_prepend(m, mtag);
349 dt = (struct ipfw_rule_ref *)(mtag+1);
351 /* Loopback avoidance and state recovery */
355 /* set the starting point. We provide a non-zero slot,
356 * but a non_matching chain_id to skip that info and use
357 * the rulenum/rule_id.
359 dt->slot = 1; /* dummy, chain_id is invalid */
361 dt->rulenum = sin->sin_port+1; /* host format ? */
363 /* XXX: broken for IPv6 */
365 * Find receive interface with the given name, stuffed
366 * (if it exists) in the sin_zero[] field.
367 * The name is user supplied data so don't trust its size
368 * or that it is zero terminated.
370 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
372 if ( i > 0 && i < sizeof(sin->sin_zero))
373 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
376 ip = mtod(m, struct ip *);
384 case IPV6_VERSION >> 4:
390 return (EAFNOSUPPORT);
393 /* Reinject packet into the system as incoming or outgoing */
395 if (!sin || sin->sin_addr.s_addr == 0) {
396 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_OUT;
397 error = div_output_outbound(family, so, m);
399 dt->info |= IPFW_IS_DIVERT | IPFW_INFO_IN;
400 error = div_output_inbound(family, so, m, sin);
408 * Sends mbuf @m to the wire via ip[6]_output().
410 * Returns 0 on success or an errno value on failure. @m is always consumed.
413 div_output_outbound(int family, struct socket *so, struct mbuf *m)
421 struct ip *const ip = mtod(m, struct ip *);
423 /* Don't allow packet length sizes that will crash. */
424 if (((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
434 struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
436 /* Don't allow packet length sizes that will crash */
437 if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
447 mac_socket_create_mbuf(so, m);
454 error = ip_output(m, NULL, NULL,
455 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
456 | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
461 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
466 DIVSTAT_INC(outbound);
472 * Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
474 * Returns 0 on success or an errno value on failure. @m is always consumed.
477 div_output_inbound(int family, struct socket *so, struct mbuf *m,
478 struct sockaddr_in *sin)
482 if (m->m_pkthdr.rcvif == NULL) {
484 * No luck with the name, check by IP address.
485 * Clear the port and the ifname to make sure
486 * there are no distractions for ifa_ifwithaddr.
489 /* XXX: broken for IPv6 */
490 bzero(sin->sin_zero, sizeof(sin->sin_zero));
492 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
495 return (EADDRNOTAVAIL);
497 m->m_pkthdr.rcvif = ifa->ifa_ifp;
500 mac_socket_create_mbuf(so, m);
502 /* Send packet to input processing via netisr */
509 ip = mtod(m, struct ip *);
511 * Restore M_BCAST flag when destination address is
512 * broadcast. It is expected by ip_tryforward().
514 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
515 m->m_flags |= M_MCAST;
516 else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
517 m->m_flags |= M_BCAST;
518 netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
519 DIVSTAT_INC(inbound);
525 netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
526 DIVSTAT_INC(inbound);
538 div_attach(struct socket *so, int proto, struct thread *td)
544 error = priv_check(td, PRIV_NETINET_DIVERT);
548 error = soreserve(so, div_sendspace, div_recvspace);
551 dcb = malloc(sizeof(*dcb), M_PCB, M_WAITOK);
552 dcb->dcb_bound = DCB_UNBOUND;
553 dcb->dcb_socket = so;
556 dcb->dcb_gencnt = ++V_dcb_gencnt;
564 div_free(epoch_context_t ctx)
566 struct divcb *dcb = __containerof(ctx, struct divcb, dcb_epochctx);
572 div_detach(struct socket *so)
574 struct divcb *dcb = so->so_pcb;
578 if (dcb->dcb_bound != DCB_UNBOUND)
579 SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
583 NET_EPOCH_CALL(div_free, &dcb->dcb_epochctx);
587 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
592 if (nam->sa_family != AF_INET)
594 if (nam->sa_len != sizeof(struct sockaddr_in))
596 port = ((struct sockaddr_in *)nam)->sin_port;
598 SLIST_FOREACH(dcb, &V_divhash[DIVHASH(port)], dcb_next)
599 if (dcb->dcb_port == port) {
604 if (dcb->dcb_bound != DCB_UNBOUND)
605 SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
606 dcb->dcb_port = port;
607 SLIST_INSERT_HEAD(&V_divhash[DIVHASH(port)], dcb, dcb_next);
614 div_shutdown(struct socket *so)
622 div_pcblist(SYSCTL_HANDLER_ARGS)
628 if (req->newptr != 0)
631 if (req->oldptr == 0) {
635 n += imax(n / 8, 10);
636 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
640 if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
643 bzero(&xig, sizeof(xig));
644 xig.xig_len = sizeof xig;
645 xig.xig_count = V_dcb_count;
646 xig.xig_gen = V_dcb_gencnt;
647 xig.xig_sogen = so_gencnt;
648 error = SYSCTL_OUT(req, &xig, sizeof xig);
653 for (int i = 0; i < DIVHASHSIZE; i++)
654 SLIST_FOREACH(dcb, &V_divhash[i], dcb_next) {
655 if (dcb->dcb_gencnt <= xig.xig_gen) {
658 bzero(&xi, sizeof(xi));
659 xi.xi_len = sizeof(struct xinpcb);
660 sotoxsocket(dcb->dcb_socket, &xi.xi_socket);
661 xi.inp_gencnt = dcb->dcb_gencnt;
662 xi.inp_vflag = INP_IPV4; /* XXX: netstat(1) */
663 xi.inp_inc.inc_ie.ie_lport = dcb->dcb_port;
664 error = SYSCTL_OUT(req, &xi, sizeof xi);
671 * Give the user an updated idea of our state.
672 * If the generation differs from what we told
673 * her before, she knows that something happened
674 * while we were processing this request, and it
675 * might be necessary to retry.
677 xig.xig_gen = V_dcb_gencnt;
678 xig.xig_sogen = so_gencnt;
679 xig.xig_count = V_dcb_count;
680 error = SYSCTL_OUT(req, &xig, sizeof xig);
687 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist,
688 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, div_pcblist,
689 "S,xinpcb", "List of active divert sockets");
691 static struct protosw div_protosw = {
693 .pr_flags = PR_ATOMIC|PR_ADDR,
694 .pr_attach = div_attach,
696 .pr_detach = div_detach,
698 .pr_shutdown = div_shutdown,
701 static struct domain divertdomain = {
702 .dom_family = PF_DIVERT,
703 .dom_name = "divert",
705 .dom_protosw = { &div_protosw },
709 div_modevent(module_t mod, int type, void *unused)
715 domain_add(&divertdomain);
716 ip_divert_ptr = divert_packet;
720 * IPDIVERT may normally not be unloaded because of the
721 * potential race conditions. Tell kldunload we can't be
722 * unloaded unless the unload is forced.
730 * Module ipdivert can only be unloaded if no sockets are
731 * connected. Maybe this can be changed later to forcefully
732 * disconnect any open sockets.
734 * XXXRW: Note that there is a slight race here, as a new
735 * socket open request could be spinning on the lock and then
736 * we destroy the lock.
738 * XXXGL: One more reason this code is incorrect is that it
739 * checks only the current vnet.
742 if (V_dcb_count != 0) {
748 ip_divert_ptr = NULL;
749 domain_remove(&divertdomain);
758 static moduledata_t ipdivertmod = {
764 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
765 MODULE_VERSION(ipdivert, 1);