Re: Avoid doing IPv6 SLAAC for prefixes with preferred lifetime of zero

[Mike Belopuhov]

On 9 March 2015 at 16:37, Stuart Henderson st...@openbsd.org wrote:

 whitespace nit here (5 char indent), otherwise OK

done on purpose.

Re: Avoid doing IPv6 SLAAC for prefixes with preferred lifetime of zero

[Stuart Henderson]

On 2015/03/09 16:21, Mike Belopuhov wrote:
 index de23248..d7f59de 100644
 --- sys/netinet6/nd6_rtr.c
 +++ sys/netinet6/nd6_rtr.c
 @@ -1374,16 +1374,17 @@ prelist_update(struct nd_prefix *new, struct 
 nd_defrouter *dr, struct mbuf *m)
   ia6-ia6_lifetime = lt6_tmp;
   ia6-ia6_updatetime = time_second;
   }
  
   if ((!autoconf || ((ifp-if_xflags  IFXF_INET6_NOPRIVACY) == 0 
 - !tempaddr_preferred))  new-ndpr_vltime != 0 
 +  !tempaddr_preferred)) 

whitespace nit here (5 char indent), otherwise OK

 + new-ndpr_vltime != 0  new-ndpr_pltime != 0 
   !((ifp-if_xflags  IFXF_INET6_NOPRIVACY)  statique)) {
   /*
* There is no SLAAC address and/or there is no preferred RFC
 -  * 4941 temporary address. And the valid prefix lifetime is
 -  * non-zero. And there is no static address in the same prefix.
 +  * 4941 temporary address. And prefix lifetimes are non-zero.
 +  * And there is no static address in the same prefix.
* Create new addresses in process context.
* Increment prefix refcount to ensure the prefix is not
* removed before the task is done.
*/
   pr-ndpr_refcnt++;
 

Avoid doing IPv6 SLAAC for prefixes with preferred lifetime of zero

[Mike Belopuhov]

Hi,

It looks like Mac OS X puts some IPv6 garbage on the wire and
our cheap consumer router starts happily advertising routes
like this:

 4006:16e1:ac17:189::/64 if=re0
 flags=LAO vltime=6401, pltime=0, expire=1h46m34s, ref=0
   advertised by
 fe80::9ec7:a6ff:fe86:a3f4%re0 (reachable)

This makes us generate autoconf and privacy addresses which
immediately become deprecated (pltime=0 translates to a zero
preferred lifetime for these addresses).  Within minutes on
an active network you end up with hundreds of dead IPv6
addresses.

RFC 4941 says in 3.3.5:

 In particular, an implementation MUST NOT create a temporary
  address with a zero Preferred Lifetime.

Which means we have to strengthen the lifetime check.  OK?

This also raises the question whether we should memorize such
prefixes at all -- but I haven't found a straight answer just
yet.


diff --git sys/netinet6/nd6_rtr.c sys/netinet6/nd6_rtr.c
index de23248..d7f59de 100644
--- sys/netinet6/nd6_rtr.c
+++ sys/netinet6/nd6_rtr.c
@@ -1374,16 +1374,17 @@ prelist_update(struct nd_prefix *new, struct 
nd_defrouter *dr, struct mbuf *m)
ia6-ia6_lifetime = lt6_tmp;
ia6-ia6_updatetime = time_second;
}
 
if ((!autoconf || ((ifp-if_xflags  IFXF_INET6_NOPRIVACY) == 0 
-   !tempaddr_preferred))  new-ndpr_vltime != 0 
+!tempaddr_preferred)) 
+   new-ndpr_vltime != 0  new-ndpr_pltime != 0 
!((ifp-if_xflags  IFXF_INET6_NOPRIVACY)  statique)) {
/*
 * There is no SLAAC address and/or there is no preferred RFC
-* 4941 temporary address. And the valid prefix lifetime is
-* non-zero. And there is no static address in the same prefix.
+* 4941 temporary address. And prefix lifetimes are non-zero.
+* And there is no static address in the same prefix.
 * Create new addresses in process context.
 * Increment prefix refcount to ensure the prefix is not
 * removed before the task is done.
 */
pr-ndpr_refcnt++;