Modify most routines returning 'struct ifaddr *' to return references

rather than pointers, requiring callers to properly dispose of those
references.  The following routines now return references:

  ifaddr_byindex
  ifa_ifwithaddr
  ifa_ifwithbroadaddr
  ifa_ifwithdstaddr
  ifa_ifwithnet
  ifaof_ifpforaddr
  ifa_ifwithroute
  ifa_ifwithroute_fib
  rt_getifa
  rt_getifa_fib
  IFP_TO_IA
  ip_rtaddr
  in6_ifawithifp
  in6ifa_ifpforlinklocal
  in6ifa_ifpwithaddr
  in6_ifadd
  carp_iamatch6
  ip6_getdstifaddr

Remove unused macro which didn't have required referencing:

  IFP_TO_IA6

This closes many small races in which changes to interface
or address lists while an ifaddr was in use could lead to use of freed
memory (etc).  In a few cases, add missing if_addr_list locking
required to safely acquire references.

Because of a lack of deep copying support, we accept a race in which
an in6_ifaddr pointed to by mbuf tags and extracted with
ip6_getdstifaddr() doesn't hold a reference while in transmit.  Once
we have mbuf tag deep copy support, this can be fixed.

Reviewed by:	bz
Obtained from:	Apple, Inc. (portions)
MFC after:	6 weeks (portions)

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
index ab38557..532070d 100644
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -683,6 +683,13 @@ route_output(struct mbuf *m, struct socket *so)
 				RT_UNLOCK(rt);
 				RADIX_NODE_HEAD_LOCK(rnh);
 				error = rt_getifa_fib(&info, rt->rt_fibnum);
+				/*
+				 * XXXRW: Really we should release this
+				 * reference later, but this maintains
+				 * historical behavior.
+				 */
+				if (info.rti_ifa != NULL)
+					ifa_free(info.rti_ifa);
 				RADIX_NODE_HEAD_UNLOCK(rnh);
 				if (error != 0)
 					senderr(error);