freebsd-skq/sbin/ifconfig/af_nd6.c

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/*
* Copyright (c) 2009 Hiroki Sato. All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#ifndef lint
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/route.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <net/if_var.h>
#include <netinet/in_var.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet6/nd6.h>
#include "ifconfig.h"
#define MAX_SYSCTL_TRY 5
#define ND6BITS "\020\001PERFORMNUD\002ACCEPT_RTADV\003PREFER_SOURCE" \
"\004IFDISABLED\005DONT_SET_IFROUTE\006AUTO_LINKLOCAL" \
- Accept Router Advertisement messages even when net.inet6.ip6.forwarding=1. - A new per-interface knob IFF_ND6_NO_RADR and sysctl IPV6CTL_NO_RADR. This controls if accepting a route in an RA message as the default route. The default value for each interface can be set by net.inet6.ip6.no_radr. The system wide default value is 0. - A new sysctl: net.inet6.ip6.norbit_raif. This controls if setting R-bit in NA on RA accepting interfaces. The default is 0 (R-bit is set based on net.inet6.ip6.forwarding). Background: IPv6 host/router model suggests a router sends an RA and a host accepts it for router discovery. Because of that, KAME implementation does not allow accepting RAs when net.inet6.ip6.forwarding=1. Accepting RAs on a router can make the routing table confused since it can change the default router unintentionally. However, in practice there are cases where we cannot distinguish a host from a router clearly. For example, a customer edge router often works as a host against the ISP, and as a router against the LAN at the same time. Another example is a complex network configurations like an L2TP tunnel for IPv6 connection to Internet over an Ethernet link with another native IPv6 subnet. In this case, the physical interface for the native IPv6 subnet works as a host, and the pseudo-interface for L2TP works as the default IP forwarding route. Problem: Disabling processing RA messages when net.inet6.ip6.forwarding=1 and accepting them when net.inet6.ip6.forward=0 cause the following practical issues: - A router cannot perform SLAAC. It becomes a problem if a box has multiple interfaces and you want to use SLAAC on some of them, for example. A customer edge router for IPv6 Internet access service using an IPv6-over-IPv6 tunnel sometimes needs SLAAC on the physical interface for administration purpose; updating firmware and so on (link-local addresses can be used there, but GUAs by SLAAC are often used for scalability). - When a host has multiple IPv6 interfaces and it receives multiple RAs on them, controlling the default route is difficult. Router preferences defined in RFC 4191 works only when the routers on the links are under your control. Details of Implementation Changes: Router Advertisement messages will be accepted even when net.inet6.ip6.forwarding=1. More precisely, the conditions are as follow: (ACCEPT_RTADV && !NO_RADR && !ip6.forwarding) => Normal RA processing on that interface. (as IPv6 host) (ACCEPT_RTADV && (NO_RADR || ip6.forwarding)) => Accept RA but add the router to the defroute list with rtlifetime=0 unconditionally. This effectively prevents from setting the received router address as the box's default route. (!ACCEPT_RTADV) => No RA processing on that interface. ACCEPT_RTADV and NO_RADR are per-interface knob. In short, all interface are classified as "RA-accepting" or not. An RA-accepting interface always processes RA messages regardless of ip6.forwarding. The difference caused by NO_RADR or ip6.forwarding is whether the RA source address is considered as the default router or not. R-bit in NA on the RA accepting interfaces is set based on net.inet6.ip6.forwarding. While RFC 6204 W-1 rule (for CPE case) suggests a router should disable the R-bit completely even when the box has net.inet6.ip6.forwarding=1, I believe there is no technical reason with doing so. This behavior can be set by a new sysctl net.inet6.ip6.norbit_raif (the default is 0). Usage: # ifconfig fxp0 inet6 accept_rtadv => accept RA on fxp0 # ifconfig fxp0 inet6 accept_rtadv no_radr => accept RA on fxp0 but ignore default route information in it. # sysctl net.inet6.ip6.norbit_no_radr=1 => R-bit in NAs on RA accepting interfaces will always be set to 0.
2011-06-06 02:14:23 +00:00
"\007NO_RADR\020DEFAULTIF"
static int isnd6defif(int);
void setnd6flags(const char *, int, int, const struct afswtch *);
void setnd6defif(const char *, int, int, const struct afswtch *);
void nd6_status(int);
void
setnd6flags(const char *dummyaddr __unused,
int d, int s,
const struct afswtch *afp)
{
struct in6_ndireq nd;
int error;
memset(&nd, 0, sizeof(nd));
strncpy(nd.ifname, ifr.ifr_name, sizeof(nd.ifname));
error = ioctl(s, SIOCGIFINFO_IN6, &nd);
if (error) {
warn("ioctl(SIOCGIFINFO_IN6)");
return;
}
if (d < 0)
nd.ndi.flags &= ~(-d);
else
nd.ndi.flags |= d;
error = ioctl(s, SIOCSIFINFO_IN6, (caddr_t)&nd);
if (error)
warn("ioctl(SIOCSIFINFO_IN6)");
}
void
setnd6defif(const char *dummyaddr __unused,
int d, int s,
const struct afswtch *afp)
{
struct in6_ndifreq ndifreq;
int ifindex;
int error;
memset(&ndifreq, 0, sizeof(ndifreq));
strncpy(ndifreq.ifname, ifr.ifr_name, sizeof(ndifreq.ifname));
if (d < 0) {
if (isnd6defif(s)) {
/* ifindex = 0 means to remove default if */
ifindex = 0;
} else
return;
} else if ((ifindex = if_nametoindex(ndifreq.ifname)) == 0) {
warn("if_nametoindex(%s)", ndifreq.ifname);
return;
}
ndifreq.ifindex = ifindex;
error = ioctl(s, SIOCSDEFIFACE_IN6, (caddr_t)&ndifreq);
if (error)
warn("ioctl(SIOCSDEFIFACE_IN6)");
}
static int
isnd6defif(int s)
{
struct in6_ndifreq ndifreq;
unsigned int ifindex;
int error;
memset(&ndifreq, 0, sizeof(ndifreq));
strncpy(ndifreq.ifname, ifr.ifr_name, sizeof(ndifreq.ifname));
ifindex = if_nametoindex(ndifreq.ifname);
error = ioctl(s, SIOCGDEFIFACE_IN6, (caddr_t)&ndifreq);
if (error) {
warn("ioctl(SIOCGDEFIFACE_IN6)");
return (error);
}
return (ndifreq.ifindex == ifindex);
}
void
nd6_status(int s)
{
struct in6_ndireq nd;
int s6;
int error;
int isdefif;
memset(&nd, 0, sizeof(nd));
strncpy(nd.ifname, ifr.ifr_name, sizeof(nd.ifname));
if ((s6 = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
if (errno != EAFNOSUPPORT)
warn("socket(AF_INET6, SOCK_DGRAM)");
return;
}
error = ioctl(s6, SIOCGIFINFO_IN6, &nd);
if (error) {
if (errno != EPFNOSUPPORT)
warn("ioctl(SIOCGIFINFO_IN6)");
close(s6);
return;
}
isdefif = isnd6defif(s6);
close(s6);
if (nd.ndi.flags == 0 && !isdefif)
return;
printb("\tnd6 options",
(unsigned int)(nd.ndi.flags | (isdefif << 15)), ND6BITS);
putchar('\n');
}