1 /* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $ */
5 * Copyright (c) 1998 The NetBSD Foundation, Inc.
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Heiko W.Rupp <hwr@pilhuhn.de>
11 * IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the NetBSD
24 * Foundation, Inc. and its contributors.
25 * 4. Neither the name of The NetBSD Foundation nor the names of its
26 * contributors may be used to endorse or promote products derived
27 * from this software without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
30 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
31 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
32 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
33 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
34 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
35 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
36 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
37 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
39 * POSSIBILITY OF SUCH DAMAGE.
43 * Encapsulate L3 protocols into IP
44 * See RFC 2784 (successor of RFC 1701 and 1702) for more details.
45 * If_gre is compatible with Cisco GRE tunnels, so you can
46 * have a NetBSD box as the other end of a tunnel interface of a Cisco
47 * router. See gre(4) for more details.
48 * Also supported: IP in IP encaps (proto 55) as of RFC 2004
51 #include "opt_atalk.h"
53 #include "opt_inet6.h"
55 #include <sys/param.h>
56 #include <sys/kernel.h>
57 #include <sys/malloc.h>
58 #include <sys/module.h>
62 #include <sys/protosw.h>
63 #include <sys/socket.h>
64 #include <sys/sockio.h>
65 #include <sys/sysctl.h>
66 #include <sys/systm.h>
68 #include <net/ethernet.h>
70 #include <net/if_clone.h>
71 #include <net/if_types.h>
72 #include <net/route.h>
75 #include <netinet/in.h>
76 #include <netinet/in_systm.h>
77 #include <netinet/in_var.h>
78 #include <netinet/ip.h>
79 #include <netinet/ip_gre.h>
80 #include <netinet/ip_var.h>
81 #include <netinet/ip_encap.h>
83 #error "Huh? if_gre without inet?"
88 #include <net/if_gre.h>
91 * It is not easy to calculate the right value for a GRE MTU.
92 * We leave this task to the admin and use the same default that
100 * gre_mtx protects all global variables in if_gre.c.
101 * XXX: gre_softc data not protected yet.
104 static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
106 struct gre_softc_head gre_softc_list;
108 static int gre_clone_create(struct if_clone *, int, caddr_t);
109 static void gre_clone_destroy(struct ifnet *);
110 static int gre_ioctl(struct ifnet *, u_long, caddr_t);
111 static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
114 IFC_SIMPLE_DECLARE(gre, 0);
116 static int gre_compute_route(struct gre_softc *sc);
118 static void greattach(void);
121 extern struct domain inetdomain;
122 static const struct protosw in_gre_protosw = {
124 .pr_domain = &inetdomain,
125 .pr_protocol = IPPROTO_GRE,
126 .pr_flags = PR_ATOMIC|PR_ADDR,
127 .pr_input = gre_input,
128 .pr_output = (pr_output_t *)rip_output,
129 .pr_ctlinput = rip_ctlinput,
130 .pr_ctloutput = rip_ctloutput,
131 .pr_usrreqs = &rip_usrreqs
133 static const struct protosw in_mobile_protosw = {
135 .pr_domain = &inetdomain,
136 .pr_protocol = IPPROTO_MOBILE,
137 .pr_flags = PR_ATOMIC|PR_ADDR,
138 .pr_input = gre_mobile_input,
139 .pr_output = (pr_output_t *)rip_output,
140 .pr_ctlinput = rip_ctlinput,
141 .pr_ctloutput = rip_ctloutput,
142 .pr_usrreqs = &rip_usrreqs
146 SYSCTL_DECL(_net_link);
147 SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
148 "Generic Routing Encapsulation");
151 * This macro controls the default upper limitation on nesting of gre tunnels.
152 * Since, setting a large value to this macro with a careless configuration
153 * may introduce system crash, we don't allow any nestings by default.
154 * If you need to configure nested gre tunnels, you can define this macro
155 * in your kernel configuration file. However, if you do so, please be
156 * careful to configure the tunnels so that it won't make a loop.
158 #define MAX_GRE_NEST 1
160 static int max_gre_nesting = MAX_GRE_NEST;
161 SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
162 &max_gre_nesting, 0, "Max nested tunnels");
169 mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
170 LIST_INIT(&gre_softc_list);
171 if_clone_attach(&gre_cloner);
175 gre_clone_create(ifc, unit, params)
176 struct if_clone *ifc;
180 struct gre_softc *sc;
182 sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
184 GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
185 if (GRE2IFP(sc) == NULL) {
190 GRE2IFP(sc)->if_softc = sc;
191 if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
193 GRE2IFP(sc)->if_snd.ifq_maxlen = IFQ_MAXLEN;
194 GRE2IFP(sc)->if_addrlen = 0;
195 GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
196 GRE2IFP(sc)->if_mtu = GREMTU;
197 GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
198 GRE2IFP(sc)->if_output = gre_output;
199 GRE2IFP(sc)->if_ioctl = gre_ioctl;
200 sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
201 sc->g_proto = IPPROTO_GRE;
202 GRE2IFP(sc)->if_flags |= IFF_LINK0;
205 sc->gre_fibnum = curthread->td_proc->p_fibnum;
206 sc->wccp_ver = WCCP_V1;
207 if_attach(GRE2IFP(sc));
208 bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
210 LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
211 mtx_unlock(&gre_mtx);
216 gre_clone_destroy(ifp)
219 struct gre_softc *sc = ifp->if_softc;
222 LIST_REMOVE(sc, sc_list);
223 mtx_unlock(&gre_mtx);
226 if (sc->encap != NULL)
227 encap_detach(sc->encap);
236 * The output routine. Takes a packet and encapsulates it in the protocol
237 * given by sc->g_proto. See also RFC 1701 and RFC 2004
240 gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
244 struct gre_softc *sc = ifp->if_softc;
250 struct mobile_h mob_h;
254 * gre may cause infinite recursion calls when misconfigured.
255 * We'll prevent this by introducing upper limit.
257 if (++(sc->called) > max_gre_nesting) {
258 printf("%s: gre_output: recursively called too many "
259 "times(%d)\n", if_name(GRE2IFP(sc)), sc->called);
261 error = EIO; /* is there better errno? */
265 if (!((ifp->if_flags & IFF_UP) &&
266 (ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
267 sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
276 /* BPF writes need to be handled specially. */
277 if (dst->sa_family == AF_UNSPEC) {
278 bcopy(dst->sa_data, &af, sizeof(af));
282 if (bpf_peers_present(ifp->if_bpf)) {
284 bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
287 m->m_flags &= ~(M_BCAST|M_MCAST);
289 if (sc->g_proto == IPPROTO_MOBILE) {
290 if (dst->sa_family == AF_INET) {
294 ip = mtod(m, struct ip *);
297 * RFC2004 specifies that fragmented diagrams shouldn't
300 if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
301 _IF_DROP(&ifp->if_snd);
303 error = EINVAL; /* is there better errno? */
306 memset(&mob_h, 0, MOB_H_SIZ_L);
307 mob_h.proto = (ip->ip_p) << 8;
308 mob_h.odst = ip->ip_dst.s_addr;
309 ip->ip_dst.s_addr = sc->g_dst.s_addr;
312 * If the packet comes from our host, we only change
313 * the destination address in the IP header.
314 * Else we also need to save and change the source
316 if (in_hosteq(ip->ip_src, sc->g_src)) {
319 mob_h.proto |= MOB_H_SBIT;
320 mob_h.osrc = ip->ip_src.s_addr;
321 ip->ip_src.s_addr = sc->g_src.s_addr;
324 mob_h.proto = htons(mob_h.proto);
325 mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
327 if ((m->m_data - msiz) < m->m_pktdat) {
329 MGETHDR(m0, M_DONTWAIT, MT_DATA);
331 _IF_DROP(&ifp->if_snd);
337 m->m_data += sizeof(struct ip);
338 m->m_len -= sizeof(struct ip);
339 m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
340 m0->m_len = msiz + sizeof(struct ip);
341 m0->m_data += max_linkhdr;
342 memcpy(mtod(m0, caddr_t), (caddr_t)ip,
345 } else { /* we have some space left in the old one */
348 m->m_pkthdr.len += msiz;
349 bcopy(ip, mtod(m, caddr_t),
352 ip = mtod(m, struct ip *);
353 memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
354 ip->ip_len = ntohs(ip->ip_len) + msiz;
355 } else { /* AF_INET */
356 _IF_DROP(&ifp->if_snd);
361 } else if (sc->g_proto == IPPROTO_GRE) {
362 switch (dst->sa_family) {
364 ip = mtod(m, struct ip *);
367 etype = ETHERTYPE_IP;
372 etype = ETHERTYPE_IPV6;
377 etype = ETHERTYPE_ATALK;
381 _IF_DROP(&ifp->if_snd);
383 error = EAFNOSUPPORT;
386 M_PREPEND(m, sizeof(struct greip), M_DONTWAIT);
388 _IF_DROP(&ifp->if_snd);
394 if (m == NULL) { /* mbuf allocation failed */
395 _IF_DROP(&ifp->if_snd);
400 M_SETFIB(m, sc->gre_fibnum); /* The envelope may use a different FIB */
402 gh = mtod(m, struct greip *);
403 if (sc->g_proto == IPPROTO_GRE) {
404 /* we don't have any GRE flags for now */
405 memset((void *)gh, 0, sizeof(struct greip));
406 gh->gi_ptype = htons(etype);
409 gh->gi_pr = sc->g_proto;
410 if (sc->g_proto != IPPROTO_MOBILE) {
411 gh->gi_src = sc->g_src;
412 gh->gi_dst = sc->g_dst;
413 ((struct ip*)gh)->ip_v = IPPROTO_IPV4;
414 ((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
415 ((struct ip*)gh)->ip_ttl = GRE_TTL;
416 ((struct ip*)gh)->ip_tos = ip_tos;
417 ((struct ip*)gh)->ip_id = ip_id;
418 gh->gi_len = m->m_pkthdr.len;
422 ifp->if_obytes += m->m_pkthdr.len;
424 * Send it off and with IP_FORWARD flag to prevent it from
425 * overwriting the ip_id again. ip_id is already set to the
426 * ip_id of the encapsulated packet.
428 error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
429 (struct ip_moptions *)NULL, (struct inpcb *)NULL);
438 gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
440 struct ifreq *ifr = (struct ifreq *)data;
441 struct if_laddrreq *lifr = (struct if_laddrreq *)data;
442 struct in_aliasreq *aifr = (struct in_aliasreq *)data;
443 struct gre_softc *sc = ifp->if_softc;
445 struct sockaddr_in si;
446 struct sockaddr *sa = NULL;
448 struct sockaddr_in sp, sm, dp, dm;
455 ifp->if_flags |= IFF_UP;
461 * XXXRW: Isn't this priv_check() redundant to the ifnet
464 if ((error = priv_check(curthread, PRIV_NET_SETIFFLAGS)) != 0)
466 if ((ifr->ifr_flags & IFF_LINK0) != 0)
467 sc->g_proto = IPPROTO_GRE;
469 sc->g_proto = IPPROTO_MOBILE;
470 if ((ifr->ifr_flags & IFF_LINK2) != 0)
471 sc->wccp_ver = WCCP_V2;
473 sc->wccp_ver = WCCP_V1;
477 * XXXRW: Isn't this priv_check() redundant to the ifnet
480 if ((error = priv_check(curthread, PRIV_NET_SETIFMTU)) != 0)
482 if (ifr->ifr_mtu < 576) {
486 ifp->if_mtu = ifr->ifr_mtu;
489 ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
493 * XXXRW: Isn't this priv_checkr() redundant to the ifnet
496 if ((error = priv_check(curthread, PRIV_NET_ADDMULTI)) != 0)
499 error = EAFNOSUPPORT;
502 switch (ifr->ifr_addr.sa_family) {
512 error = EAFNOSUPPORT;
518 * XXXRW: Isn't this priv_check() redundant to the ifnet
521 if ((error = priv_check(curthread, PRIV_NET_DELIFGROUP)) != 0)
524 error = EAFNOSUPPORT;
527 switch (ifr->ifr_addr.sa_family) {
537 error = EAFNOSUPPORT;
543 * XXXRW: Isn't this priv_check() redundant to the ifnet
546 if ((error = priv_check(curthread, PRIV_NET_GRE)) != 0)
548 sc->g_proto = ifr->ifr_flags;
549 switch (sc->g_proto) {
551 ifp->if_flags |= IFF_LINK0;
554 ifp->if_flags &= ~IFF_LINK0;
557 error = EPROTONOSUPPORT;
562 ifr->ifr_flags = sc->g_proto;
566 error = priv_check(curthread, PRIV_NET_GRE);
570 * set tunnel endpoints, compute a less specific route
571 * to the remote end and mark if as up
574 if (cmd == GRESADDRS)
575 sc->g_src = (satosin(sa))->sin_addr;
576 if (cmd == GRESADDRD)
577 sc->g_dst = (satosin(sa))->sin_addr;
580 if (sc->encap != NULL) {
581 encap_detach(sc->encap);
585 if ((sc->g_src.s_addr != INADDR_ANY) &&
586 (sc->g_dst.s_addr != INADDR_ANY)) {
587 bzero(&sp, sizeof(sp));
588 bzero(&sm, sizeof(sm));
589 bzero(&dp, sizeof(dp));
590 bzero(&dm, sizeof(dm));
591 sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
592 sizeof(struct sockaddr_in);
593 sp.sin_family = sm.sin_family = dp.sin_family =
594 dm.sin_family = AF_INET;
595 sp.sin_addr = sc->g_src;
596 dp.sin_addr = sc->g_dst;
597 sm.sin_addr.s_addr = dm.sin_addr.s_addr =
600 sc->encap = encap_attach(AF_INET, sc->g_proto,
601 sintosa(&sp), sintosa(&sm), sintosa(&dp),
602 sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
603 &in_gre_protosw : &in_mobile_protosw, sc);
604 if (sc->encap == NULL)
605 printf("%s: unable to attach encap\n",
606 if_name(GRE2IFP(sc)));
608 if (sc->route.ro_rt != 0) /* free old route */
609 RTFREE(sc->route.ro_rt);
610 if (gre_compute_route(sc) == 0)
611 ifp->if_drv_flags |= IFF_DRV_RUNNING;
613 ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
617 memset(&si, 0, sizeof(si));
618 si.sin_family = AF_INET;
619 si.sin_len = sizeof(struct sockaddr_in);
620 si.sin_addr.s_addr = sc->g_src.s_addr;
625 memset(&si, 0, sizeof(si));
626 si.sin_family = AF_INET;
627 si.sin_len = sizeof(struct sockaddr_in);
628 si.sin_addr.s_addr = sc->g_dst.s_addr;
634 * XXXRW: Isn't this priv_check() redundant to the ifnet
637 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
639 if (aifr->ifra_addr.sin_family != AF_INET ||
640 aifr->ifra_dstaddr.sin_family != AF_INET) {
641 error = EAFNOSUPPORT;
644 if (aifr->ifra_addr.sin_len != sizeof(si) ||
645 aifr->ifra_dstaddr.sin_len != sizeof(si)) {
649 sc->g_src = aifr->ifra_addr.sin_addr;
650 sc->g_dst = aifr->ifra_dstaddr.sin_addr;
652 case SIOCSLIFPHYADDR:
654 * XXXRW: Isn't this priv_check() redundant to the ifnet
657 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
659 if (lifr->addr.ss_family != AF_INET ||
660 lifr->dstaddr.ss_family != AF_INET) {
661 error = EAFNOSUPPORT;
664 if (lifr->addr.ss_len != sizeof(si) ||
665 lifr->dstaddr.ss_len != sizeof(si)) {
669 sc->g_src = (satosin(&lifr->addr))->sin_addr;
671 (satosin(&lifr->dstaddr))->sin_addr;
675 * XXXRW: Isn't this priv_check() redundant to the ifnet
678 if ((error = priv_check(curthread, PRIV_NET_SETIFPHYS)) != 0)
680 sc->g_src.s_addr = INADDR_ANY;
681 sc->g_dst.s_addr = INADDR_ANY;
683 case SIOCGLIFPHYADDR:
684 if (sc->g_src.s_addr == INADDR_ANY ||
685 sc->g_dst.s_addr == INADDR_ANY) {
686 error = EADDRNOTAVAIL;
689 memset(&si, 0, sizeof(si));
690 si.sin_family = AF_INET;
691 si.sin_len = sizeof(struct sockaddr_in);
692 si.sin_addr.s_addr = sc->g_src.s_addr;
693 memcpy(&lifr->addr, &si, sizeof(si));
694 si.sin_addr.s_addr = sc->g_dst.s_addr;
695 memcpy(&lifr->dstaddr, &si, sizeof(si));
697 case SIOCGIFPSRCADDR:
699 case SIOCGIFPSRCADDR_IN6:
701 if (sc->g_src.s_addr == INADDR_ANY) {
702 error = EADDRNOTAVAIL;
705 memset(&si, 0, sizeof(si));
706 si.sin_family = AF_INET;
707 si.sin_len = sizeof(struct sockaddr_in);
708 si.sin_addr.s_addr = sc->g_src.s_addr;
709 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
711 case SIOCGIFPDSTADDR:
713 case SIOCGIFPDSTADDR_IN6:
715 if (sc->g_dst.s_addr == INADDR_ANY) {
716 error = EADDRNOTAVAIL;
719 memset(&si, 0, sizeof(si));
720 si.sin_family = AF_INET;
721 si.sin_len = sizeof(struct sockaddr_in);
722 si.sin_addr.s_addr = sc->g_dst.s_addr;
723 bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
735 * computes a route to our destination that is not the one
736 * which would be taken by ip_output(), as this one will loop back to
737 * us. If the interface is p2p as a--->b, then a routing entry exists
738 * If we now send a packet to b (e.g. ping b), this will come down here
739 * gets src=a, dst=b tacked on and would from ip_output() sent back to
741 * Goal here is to compute a route to b that is less specific than
742 * a-->b. We know that this one exists as in normal operation we have
743 * at least a default route which matches.
746 gre_compute_route(struct gre_softc *sc)
752 memset(ro, 0, sizeof(struct route));
753 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
754 ro->ro_dst.sa_family = AF_INET;
755 ro->ro_dst.sa_len = sizeof(ro->ro_dst);
758 * toggle last bit, so our interface is not found, but a less
759 * specific route. I'd rather like to specify a shorter mask,
760 * but this is not possible. Should work though. XXX
761 * XXX MRT Use a different FIB for the tunnel to solve this problem.
763 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
764 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr ^=
769 printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
770 inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
773 rtalloc_fib(ro, sc->gre_fibnum);
776 * check if this returned a route at all and this route is no
777 * recursion to ourself
779 if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
781 if (ro->ro_rt == NULL)
782 printf(" - no route found!\n");
784 printf(" - route loops back to ourself!\n");
786 return EADDRNOTAVAIL;
790 * now change it back - else ip_output will just drop
791 * the route and search one to this interface ...
793 if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
794 ((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
797 printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
798 inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
806 * do a checksum of a buffer - much like in_cksum, which operates on
810 gre_in_cksum(u_int16_t *p, u_int len)
813 int nwords = len >> 1;
815 while (nwords-- != 0)
823 u.c[0] = *(u_char *)p;
828 /* end-around-carry */
829 sum = (sum >> 16) + (sum & 0xffff);
835 gremodevent(module_t mod, int type, void *data)
843 if_clone_detach(&gre_cloner);
844 mtx_destroy(&gre_mtx);
852 static moduledata_t gre_mod = {
858 DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
859 MODULE_VERSION(if_gre, 1);