Introduce a facility to generate unpredictable 32 bit numbers with

near maximal (2^32) cycle times. These are useful for network
IDs in cases where there are negative consequences to ID prediction
and/or reuse.

Use the idgen32() functions to generate IPv6 IDs and NFS client/server
XIDs.

Pseudorandom permutation code in crypto/idgen.c based on public
domain skip32.c from Greg Rose.

feedback & ok thib@ deraadt@

4 files changed, 26 insertions, 24 deletions

diff --git a/sys/netinet6/ip6_id.c b/sys/netinet6/ip6_id.c
index db562454533..580d1b72062 100644
--- a/sys/netinet6/ip6_id.c
+++ b/sys/netinet6/ip6_id.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_id.c,v 1.6 2008/04/18 06:42:20 djm Exp $	*/
+/*	$OpenBSD: ip6_id.c,v 1.7 2008/06/09 22:47:42 djm Exp $	*/
 /*	$NetBSD: ip6_id.c,v 1.7 2003/09/13 21:32:59 itojun Exp $	*/
 /*	$KAME: ip6_id.c,v 1.8 2003/09/06 13:41:06 itojun Exp $	*/
 
@@ -113,17 +113,6 @@ struct randomtab {
 	long ru_reseed;
 };
 
-static struct randomtab randomtab_32 = {
-	32,			/* resulting bits */
-	180,			/* Time after wich will be reseeded */
-	1000000000,		/* Uniq cycle, avoid blackjack prediction */
-	2,			/* Starting generator */
-	2147483629,		/* RU_N-1 = 2^2*3^2*59652323 */
-	7,			/* determine ru_a as RU_AGEN^(2*rand) */
-	1836660096,		/* RU_M = 2^7*3^15 - don't change */
-	{ 2, 3, 59652323, 0 },	/* factors of ru_n */
-};
-
 static struct randomtab randomtab_20 = {
 	20,			/* resulting bits */
 	180,			/* Time after wich will be reseeded */
@@ -239,15 +228,8 @@ randomid(struct randomtab *p)
 }
 
 u_int32_t
-ip6_randomid(void)
-{
-
-	return randomid(&randomtab_32);
-}
-
-u_int32_t
 ip6_randomflowlabel(void)
 {
-
 	return randomid(&randomtab_20) & 0xfffff;
 }
+
diff --git a/sys/netinet6/ip6_input.c b/sys/netinet6/ip6_input.c
index 0e645ad416b..fb99a69a989 100644
--- a/sys/netinet6/ip6_input.c
+++ b/sys/netinet6/ip6_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_input.c,v 1.84 2008/05/15 19:40:38 markus Exp $	*/
+/*	$OpenBSD: ip6_input.c,v 1.85 2008/06/09 22:47:42 djm Exp $	*/
 /*	$KAME: ip6_input.c,v 1.188 2001/03/29 05:34:31 itojun Exp $	*/
 
 /*
@@ -160,6 +160,7 @@ ip6_init()
 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
 			ip6_protox[pr->pr_protocol] = pr - inet6sw;
 	ip6intrq.ifq_maxlen = ip6qmaxlen;
+	ip6_randomid_init();
 	nd6_init();
 	frag6_init();
 	ip6_init2((void *)0);
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index cca6865818d..d8faf8bbabf 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_output.c,v 1.100 2008/03/31 21:15:20 deraadt Exp $	*/
+/*	$OpenBSD: ip6_output.c,v 1.101 2008/06/09 22:47:42 djm Exp $	*/
 /*	$KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $	*/
 
 /*
@@ -88,6 +88,8 @@
 #include <netinet6/nd6.h>
 #include <netinet6/ip6protosw.h>
 
+#include <crypto/idgen.h>
+
 #if NPF > 0
 #include <net/pfvar.h>
 #endif
@@ -132,6 +134,9 @@ static int ip6_getpmtu(struct route_in6 *, struct route_in6 *,
 	struct ifnet *, struct in6_addr *, u_long *, int *);
 static int copypktopts(struct ip6_pktopts *, struct ip6_pktopts *, int);
 
+/* Context for non-repeating IDs */
+struct idgen32_ctx ip6_id_ctx;
+
 /*
  * IP6 output. The packet in mbuf chain m contains a skeletal IP6
  * header (with pri, len, nxt, hlim, src, dst).
@@ -3225,3 +3230,16 @@ ip6_optlen(inp)
 	return len;
 #undef elen
 }
+
+u_int32_t
+ip6_randomid(void)
+{
+	return idgen32(&ip6_id_ctx);
+}
+
+void
+ip6_randomid_init(void)
+{
+	idgen32_init(&ip6_id_ctx);
+}
+
diff --git a/sys/netinet6/ip6_var.h b/sys/netinet6/ip6_var.h
index b560d21ee74..33f35df951d 100644
--- a/sys/netinet6/ip6_var.h
+++ b/sys/netinet6/ip6_var.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_var.h,v 1.32 2007/12/14 18:33:41 deraadt Exp $	*/
+/*	$OpenBSD: ip6_var.h,v 1.33 2008/06/09 22:47:42 djm Exp $	*/
 /*	$KAME: ip6_var.h,v 1.33 2000/06/11 14:59:20 jinmei Exp $	*/
 
 /*
@@ -297,6 +297,8 @@ int	ip6_setpktopts(struct mbuf *, struct ip6_pktopts *,
 void	ip6_clearpktopts(struct ip6_pktopts *, int);
 struct ip6_pktopts *ip6_copypktopts(struct ip6_pktopts *, int);
 int	ip6_optlen(struct inpcb *);
+void	ip6_randomid_init(void);
+u_int32_t ip6_randomid(void);
 
 int	route6_input(struct mbuf **, int *, int);
 
@@ -324,7 +326,6 @@ int	in6_selectroute(struct sockaddr_in6 *, struct ip6_pktopts *,
 	    struct ip6_moptions *, struct route_in6 *, struct ifnet **,
 	    struct rtentry **);
 
-u_int32_t ip6_randomid(void);
 u_int32_t ip6_randomflowlabel(void);
 #endif /* _KERNEL */