Date: Mon, 6 Jun 2011 02:14:23 +0000 (UTC) From: Hiroki Sato <hrs@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r222728 - in head: sbin/ifconfig sys/netinet6 Message-ID: <201106060214.p562EN5G007040@svn.freebsd.org>
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Author: hrs Date: Mon Jun 6 02:14:23 2011 New Revision: 222728 URL: http://svn.freebsd.org/changeset/base/222728 Log: - 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. Modified: head/sbin/ifconfig/af_inet6.c head/sbin/ifconfig/af_nd6.c head/sys/netinet6/in6.h head/sys/netinet6/in6_proto.c head/sys/netinet6/ip6_var.h head/sys/netinet6/nd6.c head/sys/netinet6/nd6.h head/sys/netinet6/nd6_nbr.c head/sys/netinet6/nd6_rtr.c Modified: head/sbin/ifconfig/af_inet6.c ============================================================================== --- head/sbin/ifconfig/af_inet6.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sbin/ifconfig/af_inet6.c Mon Jun 6 02:14:23 2011 (r222728) @@ -499,6 +499,8 @@ static struct cmd inet6_cmds[] = { DEF_CMD("-autoconf", -IN6_IFF_AUTOCONF, setip6flags), DEF_CMD("accept_rtadv", ND6_IFF_ACCEPT_RTADV, setnd6flags), DEF_CMD("-accept_rtadv",-ND6_IFF_ACCEPT_RTADV, setnd6flags), + DEF_CMD("no_radr", ND6_IFF_NO_RADR, setnd6flags), + DEF_CMD("-no_radr", -ND6_IFF_NO_RADR, setnd6flags), DEF_CMD("defaultif", 1, setnd6defif), DEF_CMD("-defaultif", -1, setnd6defif), DEF_CMD("ifdisabled", ND6_IFF_IFDISABLED, setnd6flags), Modified: head/sbin/ifconfig/af_nd6.c ============================================================================== --- head/sbin/ifconfig/af_nd6.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sbin/ifconfig/af_nd6.c Mon Jun 6 02:14:23 2011 (r222728) @@ -58,7 +58,7 @@ static const char rcsid[] = #define MAX_SYSCTL_TRY 5 #define ND6BITS "\020\001PERFORMNUD\002ACCEPT_RTADV\003PREFER_SOURCE" \ "\004IFDISABLED\005DONT_SET_IFROUTE\006AUTO_LINKLOCAL" \ - "\020DEFAULTIF" + "\007NO_RADR\020DEFAULTIF" static int isnd6defif(int); void setnd6flags(const char *, int, int, const struct afswtch *); Modified: head/sys/netinet6/in6.h ============================================================================== --- head/sys/netinet6/in6.h Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/in6.h Mon Jun 6 02:14:23 2011 (r222728) @@ -611,7 +611,10 @@ struct ip6_mtuinfo { #define IPV6CTL_STEALTH 45 #define ICMPV6CTL_ND6_ONLINKNSRFC4861 47 -#define IPV6CTL_MAXID 48 +#define IPV6CTL_NO_RADR 48 /* No defroute from RA */ +#define IPV6CTL_NORBIT_RAIF 49 /* Disable R-bit in NA on RA + * receiving IF. */ +#define IPV6CTL_MAXID 50 #endif /* __BSD_VISIBLE */ /* Modified: head/sys/netinet6/in6_proto.c ============================================================================== --- head/sys/netinet6/in6_proto.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/in6_proto.c Mon Jun 6 02:14:23 2011 (r222728) @@ -409,6 +409,8 @@ VNET_DEFINE(int, ip6_sendredirects) = IP VNET_DEFINE(int, ip6_defhlim) = IPV6_DEFHLIM; VNET_DEFINE(int, ip6_defmcasthlim) = IPV6_DEFAULT_MULTICAST_HOPS; VNET_DEFINE(int, ip6_accept_rtadv) = 0; +VNET_DEFINE(int, ip6_no_radr) = 0; +VNET_DEFINE(int, ip6_norbit_raif) = 0; VNET_DEFINE(int, ip6_maxfragpackets); /* initialized in frag6.c:frag6_init() */ VNET_DEFINE(int, ip6_maxfrags); /* initialized in frag6.c:frag6_init() */ VNET_DEFINE(int, ip6_log_interval) = 5; @@ -537,6 +539,15 @@ SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_ CTLFLAG_RW, &VNET_NAME(ip6_accept_rtadv), 0, "Default value of per-interface flag for accepting ICMPv6 Router" "Advertisement messages"); +SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_NO_RADR, no_radr, + CTLFLAG_RW, &VNET_NAME(ip6_no_radr), 0, + "Default value of per-interface flag to control whether routers " + "sending ICMPv6 RA messages on that interface are added into the " + "default router list."); +SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_NORBIT_RAIF, norbit_raif, CTLFLAG_RW, + &VNET_NAME(ip6_norbit_raif), 0, + "Always set 0 to R flag in ICMPv6 NA messages when accepting RA" + " on the interface."); SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_KEEPFAITH, keepfaith, CTLFLAG_RW, &VNET_NAME(ip6_keepfaith), 0, ""); SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_LOG_INTERVAL, log_interval, Modified: head/sys/netinet6/ip6_var.h ============================================================================== --- head/sys/netinet6/ip6_var.h Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/ip6_var.h Mon Jun 6 02:14:23 2011 (r222728) @@ -316,6 +316,9 @@ VNET_DECLARE(int, ip6_maxfragpackets); / VNET_DECLARE(int, ip6_maxfrags); /* Maximum fragments in reassembly * queue */ VNET_DECLARE(int, ip6_accept_rtadv); /* Acts as a host not a router */ +VNET_DECLARE(int, ip6_no_radr); /* No defroute from RA */ +VNET_DECLARE(int, ip6_norbit_raif); /* Disable R-bit in NA on RA + * receiving IF. */ VNET_DECLARE(int, ip6_keepfaith); /* Firewall Aided Internet Translator */ VNET_DECLARE(int, ip6_log_interval); VNET_DECLARE(time_t, ip6_log_time); @@ -327,6 +330,8 @@ VNET_DECLARE(int, ip6_dad_count); /* Dup #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets) #define V_ip6_maxfrags VNET(ip6_maxfrags) #define V_ip6_accept_rtadv VNET(ip6_accept_rtadv) +#define V_ip6_no_radr VNET(ip6_no_radr) +#define V_ip6_norbit_raif VNET(ip6_norbit_raif) #define V_ip6_keepfaith VNET(ip6_keepfaith) #define V_ip6_log_interval VNET(ip6_log_interval) #define V_ip6_log_time VNET(ip6_log_time) Modified: head/sys/netinet6/nd6.c ============================================================================== --- head/sys/netinet6/nd6.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/nd6.c Mon Jun 6 02:14:23 2011 (r222728) @@ -193,6 +193,8 @@ nd6_ifattach(struct ifnet *ifp) /* A loopback interface does not need to accept RTADV. */ if (V_ip6_accept_rtadv && !(ifp->if_flags & IFF_LOOPBACK)) nd->flags |= ND6_IFF_ACCEPT_RTADV; + if (V_ip6_no_radr && !(ifp->if_flags & IFF_LOOPBACK)) + nd->flags |= ND6_IFF_NO_RADR; /* XXX: we cannot call nd6_setmtu since ifp is not fully initialized */ nd6_setmtu0(ifp, nd); @@ -825,7 +827,7 @@ nd6_purge(struct ifnet *ifp) if (V_nd6_defifindex == ifp->if_index) nd6_setdefaultiface(0); - if (!V_ip6_forwarding && ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) { + if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) { /* Refresh default router list. */ defrouter_select(); } @@ -958,10 +960,9 @@ nd6_is_new_addr_neighbor(struct sockaddr /* * If the default router list is empty, all addresses are regarded * as on-link, and thus, as a neighbor. - * XXX: we restrict the condition to hosts, because routers usually do - * not have the "default router list". */ - if (!V_ip6_forwarding && TAILQ_FIRST(&V_nd_defrouter) == NULL && + if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV && + TAILQ_FIRST(&V_nd_defrouter) == NULL && V_nd6_defifindex == ifp->if_index) { return (1); } @@ -1022,8 +1023,7 @@ nd6_free(struct llentry *ln, int gc) ifp = ln->lle_tbl->llt_ifp; - if (!V_ip6_forwarding) { - + if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) { dr = defrouter_lookup(&L3_ADDR_SIN6(ln)->sin6_addr, ifp); if (dr != NULL && dr->expire && @@ -1340,7 +1340,7 @@ nd6_ioctl(u_long cmd, caddr_t data, stru continue; ia = (struct in6_ifaddr *)ifa; if ((ia->ia6_flags & IN6_IFF_DUPLICATED) && - IN6_IS_ADDR_LINKLOCAL(&ia->ia_addr.sin6_addr)) { + IN6_IS_ADDR_LINKLOCAL(IA6_IN6(ia))) { duplicated_linklocal = 1; break; } @@ -1718,7 +1718,7 @@ nd6_cache_lladdr(struct ifnet *ifp, stru * for those are not autoconfigured hosts, we explicitly avoid such * cases for safety. */ - if (do_update && router && !V_ip6_forwarding && + if (do_update && router && ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) { /* * guaranteed recursion Modified: head/sys/netinet6/nd6.h ============================================================================== --- head/sys/netinet6/nd6.h Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/nd6.h Mon Jun 6 02:14:23 2011 (r222728) @@ -85,6 +85,7 @@ struct nd_ifinfo { */ #define ND6_IFF_DONT_SET_IFROUTE 0x10 #define ND6_IFF_AUTO_LINKLOCAL 0x20 +#define ND6_IFF_NO_RADR 0x40 #define ND6_CREATE LLE_CREATE #define ND6_EXCLUSIVE LLE_EXCLUSIVE Modified: head/sys/netinet6/nd6_nbr.c ============================================================================== --- head/sys/netinet6/nd6_nbr.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/nd6_nbr.c Mon Jun 6 02:14:23 2011 (r222728) @@ -112,10 +112,14 @@ nd6_ns_input(struct mbuf *m, int off, in int lladdrlen = 0; int anycast = 0, proxy = 0, tentative = 0; int tlladdr; + int rflag; union nd_opts ndopts; struct sockaddr_dl proxydl; char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN]; + rflag = (V_ip6_forwarding) ? ND_NA_FLAG_ROUTER : 0; + if (ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV && V_ip6_norbit_raif) + rflag = 0; #ifndef PULLDOWN_TEST IP6_EXTHDR_CHECK(m, off, icmp6len,); nd_ns = (struct nd_neighbor_solicit *)((caddr_t)ip6 + off); @@ -339,8 +343,7 @@ nd6_ns_input(struct mbuf *m, int off, in goto bad; nd6_na_output(ifp, &in6_all, &taddr6, ((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) | - (V_ip6_forwarding ? ND_NA_FLAG_ROUTER : 0), - tlladdr, proxy ? (struct sockaddr *)&proxydl : NULL); + rflag, tlladdr, proxy ? (struct sockaddr *)&proxydl : NULL); goto freeit; } @@ -349,8 +352,8 @@ nd6_ns_input(struct mbuf *m, int off, in nd6_na_output(ifp, &saddr6, &taddr6, ((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) | - (V_ip6_forwarding ? ND_NA_FLAG_ROUTER : 0) | ND_NA_FLAG_SOLICITED, - tlladdr, proxy ? (struct sockaddr *)&proxydl : NULL); + rflag | ND_NA_FLAG_SOLICITED, tlladdr, + proxy ? (struct sockaddr *)&proxydl : NULL); freeit: if (ifa != NULL) ifa_free(ifa); @@ -862,7 +865,8 @@ nd6_na_input(struct mbuf *m, int off, in dr = defrouter_lookup(in6, ln->lle_tbl->llt_ifp); if (dr) defrtrlist_del(dr); - else if (!V_ip6_forwarding) { + else if (ND_IFINFO(ln->lle_tbl->llt_ifp)->flags & + ND6_IFF_ACCEPT_RTADV) { /* * Even if the neighbor is not in the default * router list, the neighbor may be used Modified: head/sys/netinet6/nd6_rtr.c ============================================================================== --- head/sys/netinet6/nd6_rtr.c Mon Jun 6 01:53:31 2011 (r222727) +++ head/sys/netinet6/nd6_rtr.c Mon Jun 6 02:14:23 2011 (r222728) @@ -127,8 +127,11 @@ nd6_rs_input(struct mbuf *m, int off, in union nd_opts ndopts; char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN]; - /* If I'm not a router, ignore it. */ - if (!V_ip6_forwarding) + /* + * Accept RS only when V_ip6_forwarding=1 and the interface has + * no ND6_IFF_ACCEPT_RTADV. + */ + if (!V_ip6_forwarding || ND_IFINFO(ifp)->flags & ND6_IFF_ACCEPT_RTADV) goto freeit; /* Sanity checks */ @@ -213,11 +216,10 @@ nd6_ra_input(struct mbuf *m, int off, in char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN]; /* - * We only accept RAs only when - * the node is not a router and - * per-interface variable allows RAs on the receiving interface. + * We only accept RAs only when the per-interface flag + * ND6_IFF_ACCEPT_RTADV is on the receiving interface. */ - if (V_ip6_forwarding || !(ndi->flags & ND6_IFF_ACCEPT_RTADV)) + if (!(ndi->flags & ND6_IFF_ACCEPT_RTADV)) goto freeit; if (ip6->ip6_hlim != 255) { @@ -266,7 +268,15 @@ nd6_ra_input(struct mbuf *m, int off, in bzero(&dr0, sizeof(dr0)); dr0.rtaddr = saddr6; dr0.flags = nd_ra->nd_ra_flags_reserved; - dr0.rtlifetime = ntohs(nd_ra->nd_ra_router_lifetime); + /* + * Effectively-disable the route in the RA packet + * when ND6_IFF_NO_RADR on the receiving interface or + * ip6.forwarding=1. + */ + if (ndi->flags & ND6_IFF_NO_RADR || V_ip6_forwarding) + dr0.rtlifetime = 0; + else + dr0.rtlifetime = ntohs(nd_ra->nd_ra_router_lifetime); dr0.expire = time_second + dr0.rtlifetime; dr0.ifp = ifp; /* unspecified or not? (RFC 2461 6.3.4) */ @@ -557,7 +567,7 @@ defrtrlist_del(struct nd_defrouter *dr) * Flush all the routing table entries that use the router * as a next hop. */ - if (!V_ip6_forwarding) + if (ND_IFINFO(dr->ifp)->flags & ND6_IFF_ACCEPT_RTADV) rt6_flush(&dr->rtaddr, dr->ifp); if (dr->installed) { @@ -616,20 +626,6 @@ defrouter_select(void) struct llentry *ln = NULL; /* - * This function should be called only when acting as an autoconfigured - * host. Although the remaining part of this function is not effective - * if the node is not an autoconfigured host, we explicitly exclude - * such cases here for safety. - */ - if (V_ip6_forwarding) { - nd6log((LOG_WARNING, - "defrouter_select: called unexpectedly (forwarding=%d)\n", - V_ip6_forwarding)); - splx(s); - return; - } - - /* * Let's handle easy case (3) first: * If default router list is empty, there's nothing to be done. */
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