2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1993
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32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
36 #include "opt_inet6.h"
39 #include <sys/param.h>
40 #include <sys/eventhandler.h>
41 #include <sys/kernel.h>
43 #include <sys/malloc.h>
45 #include <sys/module.h>
46 #include <sys/kernel.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>
57 #include <net/if_var.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>
66 #include <netinet/ip_divert.h>
68 #include <netinet/ip6.h>
69 #include <netinet6/ip6_var.h>
71 #if defined(SCTP) || defined(SCTP_SUPPORT)
72 #include <netinet/sctp_crc32.h>
75 #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 * Usually a system has very few divert ports. Previous implementation
90 #define DIVHASHSIZE (1 << 3) /* 8 entries, one cache line. */
91 #define DIVHASH(port) (port % DIVHASHSIZE)
92 #define DCBHASH(dcb) ((dcb)->dcb_port % DIVHASHSIZE)
95 * Divert sockets work in conjunction with ipfw or other packet filters,
96 * see the divert(4) manpage for features.
97 * Packets are selected by the packet filter and tagged with an
98 * MTAG_IPFW_RULE tag carrying the 'divert port' number (as set by
99 * the packet filter) and information on the matching filter rule for
100 * subsequent reinjection. The divert_port is used to put the packet
101 * on the corresponding divert socket, while the rule number is passed
102 * up (at least partially) as the sin_port in the struct sockaddr.
104 * Packets written to the divert socket carry in sin_addr a
105 * destination address, and in sin_port the number of the filter rule
106 * after which to continue processing.
107 * If the destination address is INADDR_ANY, the packet is treated as
108 * as outgoing and sent to ip_output(); otherwise it is treated as
109 * incoming and sent to ip_input().
110 * Further, sin_zero carries some information on the interface,
111 * which can be used in the reinject -- see comments in the code.
113 * On reinjection, processing in ip_input() and ip_output()
114 * will be exactly the same as for the original packet, except that
115 * packet filter processing will start at the rule number after the one
116 * written in the sin_port (ipfw does not allow a rule #0, so sin_port=0
117 * will apply the entire ruleset to the packet).
119 static SYSCTL_NODE(_net_inet, OID_AUTO, divert, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
122 VNET_PCPUSTAT_DEFINE_STATIC(struct divstat, divstat);
123 VNET_PCPUSTAT_SYSINIT(divstat);
125 VNET_PCPUSTAT_SYSUNINIT(divstat);
127 SYSCTL_VNET_PCPUSTAT(_net_inet_divert, OID_AUTO, stats, struct divstat,
128 divstat, "divert(4) socket statistics");
129 #define DIVSTAT_INC(name) \
130 VNET_PCPUSTAT_ADD(struct divstat, divstat, div_ ## name, 1)
132 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
133 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
135 static int div_output_inbound(int fmaily, struct socket *so, struct mbuf *m,
136 struct sockaddr_in *sin);
137 static int div_output_outbound(int family, struct socket *so, struct mbuf *m);
141 SLIST_ENTRY(divcb) dcb_next;
143 #define DCB_UNBOUND ((intptr_t)-1)
145 struct socket *dcb_socket;
148 struct epoch_context dcb_epochctx;
151 SLIST_HEAD(divhashhead, divcb);
153 VNET_DEFINE_STATIC(struct divhashhead, divhash[DIVHASHSIZE]) = {};
154 #define V_divhash VNET(divhash)
155 VNET_DEFINE_STATIC(uint64_t, dcb_count) = 0;
156 #define V_dcb_count VNET(dcb_count)
157 VNET_DEFINE_STATIC(uint64_t, dcb_gencnt) = 0;
158 #define V_dcb_gencnt VNET(dcb_gencnt)
160 static struct mtx divert_mtx;
161 MTX_SYSINIT(divert, &divert_mtx, "divert(4) socket pcb lists", MTX_DEF);
162 #define DIVERT_LOCK() mtx_lock(&divert_mtx)
163 #define DIVERT_UNLOCK() mtx_unlock(&divert_mtx)
166 * Divert a packet by passing it up to the divert socket at port 'port'.
169 divert_packet(struct mbuf *m, bool incoming)
173 struct sockaddr_in divsrc;
178 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
184 if (m->m_len < sizeof(struct ip) &&
185 (m = m_pullup(m, sizeof(struct ip))) == NULL)
188 /* Delayed checksums are currently not compatible with divert. */
189 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
191 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
193 #if defined(SCTP) || defined(SCTP_SUPPORT)
194 if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
197 ip = mtod(m, struct ip *);
198 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
199 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
204 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
205 in6_delayed_cksum(m, m->m_pkthdr.len -
206 sizeof(struct ip6_hdr), sizeof(struct ip6_hdr));
207 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
209 #if defined(SCTP) || defined(SCTP_SUPPORT)
210 if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
211 sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
212 m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
216 bzero(&divsrc, sizeof(divsrc));
217 divsrc.sin_len = sizeof(divsrc);
218 divsrc.sin_family = AF_INET;
219 /* record matching rule, in host format */
220 divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
222 * Record receive interface address, if any.
223 * But only for incoming packets.
232 /* Find IP address for receive interface */
233 ifp = m->m_pkthdr.rcvif;
234 CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
235 if (ifa->ifa_addr->sa_family != AF_INET)
238 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
243 * Record the incoming interface name whenever we have one.
245 if (m->m_pkthdr.rcvif) {
247 * Hide the actual interface name in there in the
248 * sin_zero array. XXX This needs to be moved to a
249 * different sockaddr type for divert, e.g.
250 * sockaddr_div with multiple fields like
251 * sockaddr_dl. Presently we have only 7 bytes
252 * but that will do for now as most interfaces
253 * are 4 or less + 2 or less bytes for unit.
254 * There is probably a faster way of doing this,
255 * possibly taking it from the sockaddr_dl on the iface.
256 * This solves the problem of a P2P link and a LAN interface
257 * having the same address, which can result in the wrong
258 * interface being assigned to the packet when fed back
259 * into the divert socket. Theoretically if the daemon saves
260 * and re-uses the sockaddr_in as suggested in the man pages,
261 * this iface name will come along for the ride.
262 * (see div_output for the other half of this.)
264 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
265 sizeof(divsrc.sin_zero));
268 /* Put packet on socket queue, if any */
269 nport = htons((uint16_t)(((struct ipfw_rule_ref *)(mtag+1))->info));
270 SLIST_FOREACH(dcb, &V_divhash[DIVHASH(nport)], dcb_next)
271 if (dcb->dcb_port == nport)
275 struct socket *sa = dcb->dcb_socket;
277 SOCKBUF_LOCK(&sa->so_rcv);
278 if (sbappendaddr_locked(&sa->so_rcv,
279 (struct sockaddr *)&divsrc, m, NULL) == 0) {
280 soroverflow_locked(sa);
283 sorwakeup_locked(sa);
284 DIVSTAT_INC(diverted);
293 * Deliver packet back into the IP processing machinery.
295 * If no address specified, or address is 0.0.0.0, send to ip_output();
296 * otherwise, send to ip_input() and mark as having been received on
297 * the interface with that address.
300 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
301 struct mbuf *control, struct thread *td)
303 struct epoch_tracker et;
304 struct sockaddr_in *sin = (struct sockaddr_in *)nam;
307 struct ipfw_rule_ref *dt;
313 /* Packet must have a header (but that's about it) */
314 if (m->m_len < sizeof (struct ip) &&
315 (m = m_pullup(m, sizeof (struct ip))) == NULL) {
321 if (sin->sin_family != AF_INET) {
323 return (EAFNOSUPPORT);
325 if (sin->sin_len != sizeof(*sin)) {
332 * An mbuf may hasn't come from userland, but we pretend
335 m->m_pkthdr.rcvif = NULL;
337 M_SETFIB(m, so->so_fibnum);
339 mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
341 /* this should be normal */
342 mtag = m_tag_alloc(MTAG_IPFW_RULE, 0,
343 sizeof(struct ipfw_rule_ref), M_NOWAIT | M_ZERO);
348 m_tag_prepend(m, mtag);
350 dt = (struct ipfw_rule_ref *)(mtag+1);
352 /* Loopback avoidance and state recovery */
356 /* set the starting point. We provide a non-zero slot,
357 * but a non_matching chain_id to skip that info and use
358 * the rulenum/rule_id.
360 dt->slot = 1; /* dummy, chain_id is invalid */
362 dt->rulenum = sin->sin_port+1; /* host format ? */
364 /* XXX: broken for IPv6 */
366 * Find receive interface with the given name, stuffed
367 * (if it exists) in the sin_zero[] field.
368 * The name is user supplied data so don't trust its size
369 * or that it is zero terminated.
371 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
373 if ( i > 0 && i < sizeof(sin->sin_zero))
374 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
377 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);
409 * Sends mbuf @m to the wire via ip[6]_output().
411 * Returns 0 on success or an errno value on failure. @m is always consumed.
414 div_output_outbound(int family, struct socket *so, struct mbuf *m)
422 struct ip *const ip = mtod(m, struct ip *);
424 /* Don't allow packet length sizes that will crash. */
425 if (((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
435 struct ip6_hdr *const ip6 = mtod(m, struct ip6_hdr *);
437 /* Don't allow packet length sizes that will crash */
438 if (((u_short)ntohs(ip6->ip6_plen) > m->m_pkthdr.len)) {
448 mac_socket_create_mbuf(so, m);
455 error = ip_output(m, NULL, NULL,
456 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0)
457 | IP_ALLOWBROADCAST | IP_RAWOUTPUT, NULL, NULL);
462 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
467 DIVSTAT_INC(outbound);
473 * Schedules mbuf @m for local processing via IPv4/IPv6 netisr queue.
475 * Returns 0 on success or an errno value on failure. @m is always consumed.
478 div_output_inbound(int family, struct socket *so, struct mbuf *m,
479 struct sockaddr_in *sin)
483 if (m->m_pkthdr.rcvif == NULL) {
485 * No luck with the name, check by IP address.
486 * Clear the port and the ifname to make sure
487 * there are no distractions for ifa_ifwithaddr.
490 /* XXX: broken for IPv6 */
491 bzero(sin->sin_zero, sizeof(sin->sin_zero));
493 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
496 return (EADDRNOTAVAIL);
498 m->m_pkthdr.rcvif = ifa->ifa_ifp;
501 mac_socket_create_mbuf(so, m);
503 /* Send packet to input processing via netisr */
510 ip = mtod(m, struct ip *);
512 * Restore M_BCAST flag when destination address is
513 * broadcast. It is expected by ip_tryforward().
515 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)))
516 m->m_flags |= M_MCAST;
517 else if (in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
518 m->m_flags |= M_BCAST;
519 netisr_queue_src(NETISR_IP, (uintptr_t)so, m);
520 DIVSTAT_INC(inbound);
526 netisr_queue_src(NETISR_IPV6, (uintptr_t)so, m);
527 DIVSTAT_INC(inbound);
539 div_attach(struct socket *so, int proto, struct thread *td)
545 error = priv_check(td, PRIV_NETINET_DIVERT);
549 error = soreserve(so, div_sendspace, div_recvspace);
552 dcb = malloc(sizeof(*dcb), M_PCB, M_WAITOK);
553 dcb->dcb_bound = DCB_UNBOUND;
554 dcb->dcb_socket = so;
557 dcb->dcb_gencnt = ++V_dcb_gencnt;
565 div_free(epoch_context_t ctx)
567 struct divcb *dcb = __containerof(ctx, struct divcb, dcb_epochctx);
573 div_detach(struct socket *so)
575 struct divcb *dcb = so->so_pcb;
579 if (dcb->dcb_bound != DCB_UNBOUND)
580 SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
584 NET_EPOCH_CALL(div_free, &dcb->dcb_epochctx);
588 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
593 if (nam->sa_family != AF_INET)
595 if (nam->sa_len != sizeof(struct sockaddr_in))
597 port = ((struct sockaddr_in *)nam)->sin_port;
599 SLIST_FOREACH(dcb, &V_divhash[DIVHASH(port)], dcb_next)
600 if (dcb->dcb_port == port) {
605 if (dcb->dcb_bound != DCB_UNBOUND)
606 SLIST_REMOVE(&V_divhash[DCBHASH(dcb)], dcb, divcb, dcb_next);
607 dcb->dcb_port = port;
608 SLIST_INSERT_HEAD(&V_divhash[DIVHASH(port)], dcb, dcb_next);
615 div_shutdown(struct socket *so)
623 div_pcblist(SYSCTL_HANDLER_ARGS)
629 if (req->newptr != 0)
632 if (req->oldptr == 0) {
636 n += imax(n / 8, 10);
637 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xinpcb);
641 if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
644 bzero(&xig, sizeof(xig));
645 xig.xig_len = sizeof xig;
646 xig.xig_count = V_dcb_count;
647 xig.xig_gen = V_dcb_gencnt;
648 xig.xig_sogen = so_gencnt;
649 error = SYSCTL_OUT(req, &xig, sizeof xig);
654 for (int i = 0; i < DIVHASHSIZE; i++)
655 SLIST_FOREACH(dcb, &V_divhash[i], dcb_next) {
656 if (dcb->dcb_gencnt <= xig.xig_gen) {
659 bzero(&xi, sizeof(xi));
660 xi.xi_len = sizeof(struct xinpcb);
661 sotoxsocket(dcb->dcb_socket, &xi.xi_socket);
662 xi.inp_gencnt = dcb->dcb_gencnt;
663 xi.inp_vflag = INP_IPV4; /* XXX: netstat(1) */
664 xi.inp_inc.inc_ie.ie_lport = dcb->dcb_port;
665 error = SYSCTL_OUT(req, &xi, sizeof xi);
672 * Give the user an updated idea of our state.
673 * If the generation differs from what we told
674 * her before, she knows that something happened
675 * while we were processing this request, and it
676 * might be necessary to retry.
678 xig.xig_gen = V_dcb_gencnt;
679 xig.xig_sogen = so_gencnt;
680 xig.xig_count = V_dcb_count;
681 error = SYSCTL_OUT(req, &xig, sizeof xig);
688 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist,
689 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, div_pcblist,
690 "S,xinpcb", "List of active divert sockets");
692 static struct protosw div_protosw = {
694 .pr_flags = PR_ATOMIC|PR_ADDR,
695 .pr_attach = div_attach,
697 .pr_detach = div_detach,
699 .pr_shutdown = div_shutdown,
702 static struct domain divertdomain = {
703 .dom_family = PF_DIVERT,
704 .dom_name = "divert",
706 .dom_protosw = { &div_protosw },
710 div_modevent(module_t mod, int type, void *unused)
716 domain_add(&divertdomain);
717 ip_divert_ptr = divert_packet;
721 * IPDIVERT may normally not be unloaded because of the
722 * potential race conditions. Tell kldunload we can't be
723 * unloaded unless the unload is forced.
731 * Module ipdivert can only be unloaded if no sockets are
732 * connected. Maybe this can be changed later to forcefully
733 * disconnect any open sockets.
735 * XXXRW: Note that there is a slight race here, as a new
736 * socket open request could be spinning on the lock and then
737 * we destroy the lock.
739 * XXXGL: One more reason this code is incorrect is that it
740 * checks only the current vnet.
743 if (V_dcb_count != 0) {
749 ip_divert_ptr = NULL;
750 domain_remove(&divertdomain);
759 static moduledata_t ipdivertmod = {
765 DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_FIREWALL, SI_ORDER_ANY);
766 MODULE_VERSION(ipdivert, 1);