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freebsd-dev/sys/net/if_gre.c
Christian S.J. Peron 16d878cc99 Fix the following bpf(4) race condition which can result in a panic: 
(1) bpf peer attaches to interface netif0
	(2) Packet is received by netif0
	(3) ifp->if_bpf pointer is checked and handed off to bpf
	(4) bpf peer detaches from netif0 resulting in ifp->if_bpf being
	    initialized to NULL.
	(5) ifp->if_bpf is dereferenced by bpf machinery
	(6) Kaboom

This race condition likely explains the various different kernel panics
reported around sending SIGINT to tcpdump or dhclient processes. But really
this race can result in kernel panics anywhere you have frequent bpf attach
and detach operations with high packet per second load.

Summary of changes:

- Remove the bpf interface's "driverp" member
- When we attach bpf interfaces, we now set the ifp->if_bpf member to the
  bpf interface structure. Once this is done, ifp->if_bpf should never be
  NULL. [1]
- Introduce bpf_peers_present function, an inline operation which will do
  a lockless read bpf peer list associated with the interface. It should
  be noted that the bpf code will pickup the bpf_interface lock before adding
  or removing bpf peers. This should serialize the access to the bpf descriptor
  list, removing the race.
- Expose the bpf_if structure in bpf.h so that the bpf_peers_present function
  can use it. This also removes the struct bpf_if; hack that was there.
- Adjust all consumers of the raw if_bpf structure to use bpf_peers_present

Now what happens is:

	(1) Packet is received by netif0
	(2) Check to see if bpf descriptor list is empty
	(3) Pickup the bpf interface lock
	(4) Hand packet off to process

From the attach/detach side:

	(1) Pickup the bpf interface lock
	(2) Add/remove from bpf descriptor list

Now that we are storing the bpf interface structure with the ifnet, there is
is no need to walk the bpf interface list to locate the correct bpf interface.
We now simply look up the interface, and initialize the pointer. This has a
nice side effect of changing a bpf interface attach operation from O(N) (where
N is the number of bpf interfaces), to O(1).

[1] From now on, we can no longer check ifp->if_bpf to tell us whether or
    not we have any bpf peers that might be interested in receiving packets.

In collaboration with:	sam@
MFC after:	1 month
2006-06-02 19:59:33 +00:00

808 lines
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/* $NetBSD: if_gre.c,v 1.49 2003/12/11 00:22:29 itojun Exp $ */
/* $FreeBSD$ */
/*-
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Heiko W.Rupp <hwr@pilhuhn.de>
*
* IPv6-over-GRE contributed by Gert Doering <gert@greenie.muc.de>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Encapsulate L3 protocols into IP
* See RFC 2784 (successor of RFC 1701 and 1702) for more details.
* If_gre is compatible with Cisco GRE tunnels, so you can
* have a NetBSD box as the other end of a tunnel interface of a Cisco
* router. See gre(4) for more details.
* Also supported: IP in IP encaps (proto 55) as of RFC 2004
*/
#include "opt_atalk.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_clone.h>
#include <net/if_types.h>
#include <net/route.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_gre.h>
#include <netinet/ip_var.h>
#include <netinet/ip_encap.h>
#else
#error "Huh? if_gre without inet?"
#endif
#include <net/bpf.h>
#include <net/net_osdep.h>
#include <net/if_gre.h>
/*
* It is not easy to calculate the right value for a GRE MTU.
* We leave this task to the admin and use the same default that
* other vendors use.
*/
#define GREMTU 1476
#define GRENAME "gre"
/*
* gre_mtx protects all global variables in if_gre.c.
* XXX: gre_softc data not protected yet.
*/
struct mtx gre_mtx;
static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
struct gre_softc_head gre_softc_list;
static int gre_clone_create(struct if_clone *, int);
static void gre_clone_destroy(struct ifnet *);
static int gre_ioctl(struct ifnet *, u_long, caddr_t);
static int gre_output(struct ifnet *, struct mbuf *, struct sockaddr *,
struct rtentry *rt);
IFC_SIMPLE_DECLARE(gre, 0);
static int gre_compute_route(struct gre_softc *sc);
static void greattach(void);
#ifdef INET
extern struct domain inetdomain;
static const struct protosw in_gre_protosw = {
.pr_type = SOCK_RAW,
.pr_domain = &inetdomain,
.pr_protocol = IPPROTO_GRE,
.pr_flags = PR_ATOMIC|PR_ADDR,
.pr_input = gre_input,
.pr_output = (pr_output_t *)rip_output,
.pr_ctlinput = rip_ctlinput,
.pr_ctloutput = rip_ctloutput,
.pr_usrreqs = &rip_usrreqs
};
static const struct protosw in_mobile_protosw = {
.pr_type = SOCK_RAW,
.pr_domain = &inetdomain,
.pr_protocol = IPPROTO_MOBILE,
.pr_flags = PR_ATOMIC|PR_ADDR,
.pr_input = gre_mobile_input,
.pr_output = (pr_output_t *)rip_output,
.pr_ctlinput = rip_ctlinput,
.pr_ctloutput = rip_ctloutput,
.pr_usrreqs = &rip_usrreqs
};
#endif
SYSCTL_DECL(_net_link);
SYSCTL_NODE(_net_link, IFT_TUNNEL, gre, CTLFLAG_RW, 0,
"Generic Routing Encapsulation");
#ifndef MAX_GRE_NEST
/*
* This macro controls the default upper limitation on nesting of gre tunnels.
* Since, setting a large value to this macro with a careless configuration
* may introduce system crash, we don't allow any nestings by default.
* If you need to configure nested gre tunnels, you can define this macro
* in your kernel configuration file. However, if you do so, please be
* careful to configure the tunnels so that it won't make a loop.
*/
#define MAX_GRE_NEST 1
#endif
static int max_gre_nesting = MAX_GRE_NEST;
SYSCTL_INT(_net_link_gre, OID_AUTO, max_nesting, CTLFLAG_RW,
&max_gre_nesting, 0, "Max nested tunnels");
/* ARGSUSED */
static void
greattach(void)
{
mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
LIST_INIT(&gre_softc_list);
if_clone_attach(&gre_cloner);
}
static int
gre_clone_create(ifc, unit)
struct if_clone *ifc;
int unit;
{
struct gre_softc *sc;
sc = malloc(sizeof(struct gre_softc), M_GRE, M_WAITOK | M_ZERO);
GRE2IFP(sc) = if_alloc(IFT_TUNNEL);
if (GRE2IFP(sc) == NULL) {
free(sc, M_GRE);
return (ENOSPC);
}
GRE2IFP(sc)->if_softc = sc;
if_initname(GRE2IFP(sc), ifc->ifc_name, unit);
GRE2IFP(sc)->if_snd.ifq_maxlen = IFQ_MAXLEN;
GRE2IFP(sc)->if_addrlen = 0;
GRE2IFP(sc)->if_hdrlen = 24; /* IP + GRE */
GRE2IFP(sc)->if_mtu = GREMTU;
GRE2IFP(sc)->if_flags = IFF_POINTOPOINT|IFF_MULTICAST;
GRE2IFP(sc)->if_output = gre_output;
GRE2IFP(sc)->if_ioctl = gre_ioctl;
sc->g_dst.s_addr = sc->g_src.s_addr = INADDR_ANY;
sc->g_proto = IPPROTO_GRE;
GRE2IFP(sc)->if_flags |= IFF_LINK0;
sc->encap = NULL;
sc->called = 0;
sc->wccp_ver = WCCP_V1;
if_attach(GRE2IFP(sc));
bpfattach(GRE2IFP(sc), DLT_NULL, sizeof(u_int32_t));
mtx_lock(&gre_mtx);
LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
mtx_unlock(&gre_mtx);
return (0);
}
static void
gre_clone_destroy(ifp)
struct ifnet *ifp;
{
struct gre_softc *sc = ifp->if_softc;
mtx_lock(&gre_mtx);
LIST_REMOVE(sc, sc_list);
mtx_unlock(&gre_mtx);
#ifdef INET
if (sc->encap != NULL)
encap_detach(sc->encap);
#endif
bpfdetach(ifp);
if_detach(ifp);
if_free(ifp);
free(sc, M_GRE);
}
/*
* The output routine. Takes a packet and encapsulates it in the protocol
* given by sc->g_proto. See also RFC 1701 and RFC 2004
*/
static int
gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
struct rtentry *rt)
{
int error = 0;
struct gre_softc *sc = ifp->if_softc;
struct greip *gh;
struct ip *ip;
u_short ip_id = 0;
uint8_t ip_tos = 0;
u_int16_t etype = 0;
struct mobile_h mob_h;
u_int32_t af;
/*
* gre may cause infinite recursion calls when misconfigured.
* We'll prevent this by introducing upper limit.
*/
if (++(sc->called) > max_gre_nesting) {
printf("%s: gre_output: recursively called too many "
"times(%d)\n", if_name(GRE2IFP(sc)), sc->called);
m_freem(m);
error = EIO; /* is there better errno? */
goto end;
}
if (!((ifp->if_flags & IFF_UP) &&
(ifp->if_drv_flags & IFF_DRV_RUNNING)) ||
sc->g_src.s_addr == INADDR_ANY || sc->g_dst.s_addr == INADDR_ANY) {
m_freem(m);
error = ENETDOWN;
goto end;
}
gh = NULL;
ip = NULL;
/* BPF writes need to be handled specially. */
if (dst->sa_family == AF_UNSPEC) {
bcopy(dst->sa_data, &af, sizeof(af));
dst->sa_family = af;
}
if (bpf_peers_present(ifp->if_bpf)) {
af = dst->sa_family;
bpf_mtap2(ifp->if_bpf, &af, sizeof(af), m);
}
m->m_flags &= ~(M_BCAST|M_MCAST);
if (sc->g_proto == IPPROTO_MOBILE) {
if (dst->sa_family == AF_INET) {
struct mbuf *m0;
int msiz;
ip = mtod(m, struct ip *);
/*
* RFC2004 specifies that fragmented diagrams shouldn't
* be encapsulated.
*/
if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
_IF_DROP(&ifp->if_snd);
m_freem(m);
error = EINVAL; /* is there better errno? */
goto end;
}
memset(&mob_h, 0, MOB_H_SIZ_L);
mob_h.proto = (ip->ip_p) << 8;
mob_h.odst = ip->ip_dst.s_addr;
ip->ip_dst.s_addr = sc->g_dst.s_addr;
/*
* If the packet comes from our host, we only change
* the destination address in the IP header.
* Else we also need to save and change the source
*/
if (in_hosteq(ip->ip_src, sc->g_src)) {
msiz = MOB_H_SIZ_S;
} else {
mob_h.proto |= MOB_H_SBIT;
mob_h.osrc = ip->ip_src.s_addr;
ip->ip_src.s_addr = sc->g_src.s_addr;
msiz = MOB_H_SIZ_L;
}
mob_h.proto = htons(mob_h.proto);
mob_h.hcrc = gre_in_cksum((u_int16_t *)&mob_h, msiz);
if ((m->m_data - msiz) < m->m_pktdat) {
/* need new mbuf */
MGETHDR(m0, M_DONTWAIT, MT_DATA);
if (m0 == NULL) {
_IF_DROP(&ifp->if_snd);
m_freem(m);
error = ENOBUFS;
goto end;
}
m0->m_next = m;
m->m_data += sizeof(struct ip);
m->m_len -= sizeof(struct ip);
m0->m_pkthdr.len = m->m_pkthdr.len + msiz;
m0->m_len = msiz + sizeof(struct ip);
m0->m_data += max_linkhdr;
memcpy(mtod(m0, caddr_t), (caddr_t)ip,
sizeof(struct ip));
m = m0;
} else { /* we have some space left in the old one */
m->m_data -= msiz;
m->m_len += msiz;
m->m_pkthdr.len += msiz;
bcopy(ip, mtod(m, caddr_t),
sizeof(struct ip));
}
ip = mtod(m, struct ip *);
memcpy((caddr_t)(ip + 1), &mob_h, (unsigned)msiz);
ip->ip_len = ntohs(ip->ip_len) + msiz;
} else { /* AF_INET */
_IF_DROP(&ifp->if_snd);
m_freem(m);
error = EINVAL;
goto end;
}
} else if (sc->g_proto == IPPROTO_GRE) {
switch (dst->sa_family) {
case AF_INET:
ip = mtod(m, struct ip *);
ip_tos = ip->ip_tos;
ip_id = ip->ip_id;
etype = ETHERTYPE_IP;
break;
#ifdef INET6
case AF_INET6:
ip_id = ip_newid();
etype = ETHERTYPE_IPV6;
break;
#endif
#ifdef NETATALK
case AF_APPLETALK:
etype = ETHERTYPE_ATALK;
break;
#endif
default:
_IF_DROP(&ifp->if_snd);
m_freem(m);
error = EAFNOSUPPORT;
goto end;
}
M_PREPEND(m, sizeof(struct greip), M_DONTWAIT);
} else {
_IF_DROP(&ifp->if_snd);
m_freem(m);
error = EINVAL;
goto end;
}
if (m == NULL) { /* mbuf allocation failed */
_IF_DROP(&ifp->if_snd);
error = ENOBUFS;
goto end;
}
gh = mtod(m, struct greip *);
if (sc->g_proto == IPPROTO_GRE) {
/* we don't have any GRE flags for now */
memset((void *)gh, 0, sizeof(struct greip));
gh->gi_ptype = htons(etype);
}
gh->gi_pr = sc->g_proto;
if (sc->g_proto != IPPROTO_MOBILE) {
gh->gi_src = sc->g_src;
gh->gi_dst = sc->g_dst;
((struct ip*)gh)->ip_v = IPPROTO_IPV4;
((struct ip*)gh)->ip_hl = (sizeof(struct ip)) >> 2;
((struct ip*)gh)->ip_ttl = GRE_TTL;
((struct ip*)gh)->ip_tos = ip_tos;
((struct ip*)gh)->ip_id = ip_id;
gh->gi_len = m->m_pkthdr.len;
}
ifp->if_opackets++;
ifp->if_obytes += m->m_pkthdr.len;
/*
* Send it off and with IP_FORWARD flag to prevent it from
* overwriting the ip_id again. ip_id is already set to the
* ip_id of the encapsulated packet.
*/
error = ip_output(m, NULL, &sc->route, IP_FORWARDING,
(struct ip_moptions *)NULL, (struct inpcb *)NULL);
end:
sc->called = 0;
if (error)
ifp->if_oerrors++;
return (error);
}
static int
gre_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
struct ifreq *ifr = (struct ifreq *)data;
struct if_laddrreq *lifr = (struct if_laddrreq *)data;
struct in_aliasreq *aifr = (struct in_aliasreq *)data;
struct gre_softc *sc = ifp->if_softc;
int s;
struct sockaddr_in si;
struct sockaddr *sa = NULL;
int error;
struct sockaddr_in sp, sm, dp, dm;
error = 0;
s = splnet();
switch (cmd) {
case SIOCSIFADDR:
ifp->if_flags |= IFF_UP;
break;
case SIOCSIFDSTADDR:
break;
case SIOCSIFFLAGS:
if ((error = suser(curthread)) != 0)
break;
if ((ifr->ifr_flags & IFF_LINK0) != 0)
sc->g_proto = IPPROTO_GRE;
else
sc->g_proto = IPPROTO_MOBILE;
if ((ifr->ifr_flags & IFF_LINK2) != 0)
sc->wccp_ver = WCCP_V2;
else
sc->wccp_ver = WCCP_V1;
goto recompute;
case SIOCSIFMTU:
if ((error = suser(curthread)) != 0)
break;
if (ifr->ifr_mtu < 576) {
error = EINVAL;
break;
}
ifp->if_mtu = ifr->ifr_mtu;
break;
case SIOCGIFMTU:
ifr->ifr_mtu = GRE2IFP(sc)->if_mtu;
break;
case SIOCADDMULTI:
case SIOCDELMULTI:
if ((error = suser(curthread)) != 0)
break;
if (ifr == 0) {
error = EAFNOSUPPORT;
break;
}
switch (ifr->ifr_addr.sa_family) {
#ifdef INET
case AF_INET:
break;
#endif
#ifdef INET6
case AF_INET6:
break;
#endif
default:
error = EAFNOSUPPORT;
break;
}
break;
case GRESPROTO:
if ((error = suser(curthread)) != 0)
break;
sc->g_proto = ifr->ifr_flags;
switch (sc->g_proto) {
case IPPROTO_GRE:
ifp->if_flags |= IFF_LINK0;
break;
case IPPROTO_MOBILE:
ifp->if_flags &= ~IFF_LINK0;
break;
default:
error = EPROTONOSUPPORT;
break;
}
goto recompute;
case GREGPROTO:
ifr->ifr_flags = sc->g_proto;
break;
case GRESADDRS:
case GRESADDRD:
if ((error = suser(curthread)) != 0)
break;
/*
* set tunnel endpoints, compute a less specific route
* to the remote end and mark if as up
*/
sa = &ifr->ifr_addr;
if (cmd == GRESADDRS)
sc->g_src = (satosin(sa))->sin_addr;
if (cmd == GRESADDRD)
sc->g_dst = (satosin(sa))->sin_addr;
recompute:
#ifdef INET
if (sc->encap != NULL) {
encap_detach(sc->encap);
sc->encap = NULL;
}
#endif
if ((sc->g_src.s_addr != INADDR_ANY) &&
(sc->g_dst.s_addr != INADDR_ANY)) {
bzero(&sp, sizeof(sp));
bzero(&sm, sizeof(sm));
bzero(&dp, sizeof(dp));
bzero(&dm, sizeof(dm));
sp.sin_len = sm.sin_len = dp.sin_len = dm.sin_len =
sizeof(struct sockaddr_in);
sp.sin_family = sm.sin_family = dp.sin_family =
dm.sin_family = AF_INET;
sp.sin_addr = sc->g_src;
dp.sin_addr = sc->g_dst;
sm.sin_addr.s_addr = dm.sin_addr.s_addr =
INADDR_BROADCAST;
#ifdef INET
sc->encap = encap_attach(AF_INET, sc->g_proto,
sintosa(&sp), sintosa(&sm), sintosa(&dp),
sintosa(&dm), (sc->g_proto == IPPROTO_GRE) ?
&in_gre_protosw : &in_mobile_protosw, sc);
if (sc->encap == NULL)
printf("%s: unable to attach encap\n",
if_name(GRE2IFP(sc)));
#endif
if (sc->route.ro_rt != 0) /* free old route */
RTFREE(sc->route.ro_rt);
if (gre_compute_route(sc) == 0)
ifp->if_drv_flags |= IFF_DRV_RUNNING;
else
ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
}
break;
case GREGADDRS:
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_len = sizeof(struct sockaddr_in);
si.sin_addr.s_addr = sc->g_src.s_addr;
sa = sintosa(&si);
ifr->ifr_addr = *sa;
break;
case GREGADDRD:
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_len = sizeof(struct sockaddr_in);
si.sin_addr.s_addr = sc->g_dst.s_addr;
sa = sintosa(&si);
ifr->ifr_addr = *sa;
break;
case SIOCSIFPHYADDR:
if ((error = suser(curthread)) != 0)
break;
if (aifr->ifra_addr.sin_family != AF_INET ||
aifr->ifra_dstaddr.sin_family != AF_INET) {
error = EAFNOSUPPORT;
break;
}
if (aifr->ifra_addr.sin_len != sizeof(si) ||
aifr->ifra_dstaddr.sin_len != sizeof(si)) {
error = EINVAL;
break;
}
sc->g_src = aifr->ifra_addr.sin_addr;
sc->g_dst = aifr->ifra_dstaddr.sin_addr;
goto recompute;
case SIOCSLIFPHYADDR:
if ((error = suser(curthread)) != 0)
break;
if (lifr->addr.ss_family != AF_INET ||
lifr->dstaddr.ss_family != AF_INET) {
error = EAFNOSUPPORT;
break;
}
if (lifr->addr.ss_len != sizeof(si) ||
lifr->dstaddr.ss_len != sizeof(si)) {
error = EINVAL;
break;
}
sc->g_src = (satosin(&lifr->addr))->sin_addr;
sc->g_dst =
(satosin(&lifr->dstaddr))->sin_addr;
goto recompute;
case SIOCDIFPHYADDR:
if ((error = suser(curthread)) != 0)
break;
sc->g_src.s_addr = INADDR_ANY;
sc->g_dst.s_addr = INADDR_ANY;
goto recompute;
case SIOCGLIFPHYADDR:
if (sc->g_src.s_addr == INADDR_ANY ||
sc->g_dst.s_addr == INADDR_ANY) {
error = EADDRNOTAVAIL;
break;
}
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_len = sizeof(struct sockaddr_in);
si.sin_addr.s_addr = sc->g_src.s_addr;
memcpy(&lifr->addr, &si, sizeof(si));
si.sin_addr.s_addr = sc->g_dst.s_addr;
memcpy(&lifr->dstaddr, &si, sizeof(si));
break;
case SIOCGIFPSRCADDR:
#ifdef INET6
case SIOCGIFPSRCADDR_IN6:
#endif
if (sc->g_src.s_addr == INADDR_ANY) {
error = EADDRNOTAVAIL;
break;
}
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_len = sizeof(struct sockaddr_in);
si.sin_addr.s_addr = sc->g_src.s_addr;
bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
break;
case SIOCGIFPDSTADDR:
#ifdef INET6
case SIOCGIFPDSTADDR_IN6:
#endif
if (sc->g_dst.s_addr == INADDR_ANY) {
error = EADDRNOTAVAIL;
break;
}
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_len = sizeof(struct sockaddr_in);
si.sin_addr.s_addr = sc->g_dst.s_addr;
bcopy(&si, &ifr->ifr_addr, sizeof(ifr->ifr_addr));
break;
default:
error = EINVAL;
break;
}
splx(s);
return (error);
}
/*
* computes a route to our destination that is not the one
* which would be taken by ip_output(), as this one will loop back to
* us. If the interface is p2p as a--->b, then a routing entry exists
* If we now send a packet to b (e.g. ping b), this will come down here
* gets src=a, dst=b tacked on and would from ip_output() sent back to
* if_gre.
* Goal here is to compute a route to b that is less specific than
* a-->b. We know that this one exists as in normal operation we have
* at least a default route which matches.
*/
static int
gre_compute_route(struct gre_softc *sc)
{
struct route *ro;
u_int32_t a, b, c;
ro = &sc->route;
memset(ro, 0, sizeof(struct route));
((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
ro->ro_dst.sa_family = AF_INET;
ro->ro_dst.sa_len = sizeof(ro->ro_dst);
/*
* toggle last bit, so our interface is not found, but a less
* specific route. I'd rather like to specify a shorter mask,
* but this is not possible. Should work though. XXX
* there is a simpler way ...
*/
if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0) {
a = ntohl(sc->g_dst.s_addr);
b = a & 0x01;
c = a & 0xfffffffe;
b = b ^ 0x01;
a = b | c;
((struct sockaddr_in *)&ro->ro_dst)->sin_addr.s_addr
= htonl(a);
}
#ifdef DIAGNOSTIC
printf("%s: searching for a route to %s", if_name(GRE2IFP(sc)),
inet_ntoa(((struct sockaddr_in *)&ro->ro_dst)->sin_addr));
#endif
rtalloc(ro);
/*
* check if this returned a route at all and this route is no
* recursion to ourself
*/
if (ro->ro_rt == NULL || ro->ro_rt->rt_ifp->if_softc == sc) {
#ifdef DIAGNOSTIC
if (ro->ro_rt == NULL)
printf(" - no route found!\n");
else
printf(" - route loops back to ourself!\n");
#endif
return EADDRNOTAVAIL;
}
/*
* now change it back - else ip_output will just drop
* the route and search one to this interface ...
*/
if ((GRE2IFP(sc)->if_flags & IFF_LINK1) == 0)
((struct sockaddr_in *)&ro->ro_dst)->sin_addr = sc->g_dst;
#ifdef DIAGNOSTIC
printf(", choosing %s with gateway %s", if_name(ro->ro_rt->rt_ifp),
inet_ntoa(((struct sockaddr_in *)(ro->ro_rt->rt_gateway))->sin_addr));
printf("\n");
#endif
return 0;
}
/*
* do a checksum of a buffer - much like in_cksum, which operates on
* mbufs.
*/
u_int16_t
gre_in_cksum(u_int16_t *p, u_int len)
{
u_int32_t sum = 0;
int nwords = len >> 1;
while (nwords-- != 0)
sum += *p++;
if (len & 1) {
union {
u_short w;
u_char c[2];
} u;
u.c[0] = *(u_char *)p;
u.c[1] = 0;
sum += u.w;
}
/* end-around-carry */
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return (~sum);
}
static int
gremodevent(module_t mod, int type, void *data)
{
switch (type) {
case MOD_LOAD:
greattach();
break;
case MOD_UNLOAD:
if_clone_detach(&gre_cloner);
mtx_destroy(&gre_mtx);
break;
default:
return EOPNOTSUPP;
}
return 0;
}
static moduledata_t gre_mod = {
"if_gre",
gremodevent,
0
};
DECLARE_MODULE(if_gre, gre_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(if_gre, 1);
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