RFC 4941bis suggests lowering the time for IPv6 temporary addresses.

This is an implmentation based on patches contributed from
Fernando Gont, Loganden Velvindron and Marek Zarychta for FreeBSD.

(FreeBSD bug 245103)

sys/netinet6/in6_ifattach.c

@@ -86,7 +86,6 @@ VNET_DECLARE(struct inpcbinfo, ripcbinfo);
 #define	V_ripcbinfo			VNET(ripcbinfo)
 
 static int get_rand_ifid(struct ifnet *, struct in6_addr *);
-static int generate_tmp_ifid(u_int8_t *, const u_int8_t *, u_int8_t *);
 static int get_ifid(struct ifnet *, struct ifnet *, struct in6_addr *);
 static int in6_ifattach_linklocal(struct ifnet *, struct ifnet *);
 static int in6_ifattach_loopback(struct ifnet *);
@@ -151,84 +150,6 @@ get_rand_ifid(struct ifnet *ifp, struct in6_addr *in6)
 	return 0;
 }
 
-static int
-generate_tmp_ifid(u_int8_t *seed0, const u_int8_t *seed1, u_int8_t *ret)
-{
-	MD5_CTX ctxt;
-	u_int8_t seed[16], digest[16], nullbuf[8];
-	u_int32_t val32;
-
-	/* If there's no history, start with a random seed. */
-	bzero(nullbuf, sizeof(nullbuf));
-	if (bcmp(nullbuf, seed0, sizeof(nullbuf)) == 0) {
-		int i;
-
-		for (i = 0; i < 2; i++) {
-			val32 = arc4random();
-			bcopy(&val32, seed + sizeof(val32) * i, sizeof(val32));
-		}
-	} else
-		bcopy(seed0, seed, 8);
-
-	/* copy the right-most 64-bits of the given address */
-	/* XXX assumption on the size of IFID */
-	bcopy(seed1, &seed[8], 8);
-
-	if (0) {		/* for debugging purposes only */
-		int i;
-
-		printf("generate_tmp_ifid: new randomized ID from: ");
-		for (i = 0; i < 16; i++)
-			printf("%02x", seed[i]);
-		printf(" ");
-	}
-
-	/* generate 16 bytes of pseudo-random value. */
-	bzero(&ctxt, sizeof(ctxt));
-	MD5Init(&ctxt);
-	MD5Update(&ctxt, seed, sizeof(seed));
-	MD5Final(digest, &ctxt);
-
-	/*
-	 * RFC 3041 3.2.1. (3)
-	 * Take the left-most 64-bits of the MD5 digest and set bit 6 (the
-	 * left-most bit is numbered 0) to zero.
-	 */
-	bcopy(digest, ret, 8);
-	ret[0] &= ~EUI64_UBIT;
-
-	/*
-	 * XXX: we'd like to ensure that the generated value is not zero
-	 * for simplicity.  If the caclculated digest happens to be zero,
-	 * use a random non-zero value as the last resort.
-	 */
-	if (bcmp(nullbuf, ret, sizeof(nullbuf)) == 0) {
-		nd6log((LOG_INFO,
-		    "generate_tmp_ifid: computed MD5 value is zero.\n"));
-
-		val32 = arc4random();
-		val32 = 1 + (val32 % (0xffffffff - 1));
-	}
-
-	/*
-	 * RFC 3041 3.2.1. (4)
-	 * Take the rightmost 64-bits of the MD5 digest and save them in
-	 * stable storage as the history value to be used in the next
-	 * iteration of the algorithm.
-	 */
-	bcopy(&digest[8], seed0, 8);
-
-	if (0) {		/* for debugging purposes only */
-		int i;
-
-		printf("to: ");
-		for (i = 0; i < 16; i++)
-			printf("%02x", digest[i]);
-		printf("\n");
-	}
-
-	return 0;
-}
 
 /*
  * Get interface identifier for the specified interface.
@@ -804,58 +725,15 @@ in6_ifdetach_destroy(struct ifnet *ifp)
 	_in6_ifdetach(ifp, 0);
 }
 
-int
-in6_get_tmpifid(struct ifnet *ifp, u_int8_t *retbuf,
-    const u_int8_t *baseid, int generate)
-{
-	u_int8_t nullbuf[8];
-	struct nd_ifinfo *ndi = ND_IFINFO(ifp);
-
-	bzero(nullbuf, sizeof(nullbuf));
-	if (bcmp(ndi->randomid, nullbuf, sizeof(nullbuf)) == 0) {
-		/* we've never created a random ID.  Create a new one. */
-		generate = 1;
-	}
-
-	if (generate) {
-		bcopy(baseid, ndi->randomseed1, sizeof(ndi->randomseed1));
-
-		/* generate_tmp_ifid will update seedn and buf */
-		(void)generate_tmp_ifid(ndi->randomseed0, ndi->randomseed1,
-		    ndi->randomid);
-	}
-	bcopy(ndi->randomid, retbuf, 8);
-
-	return (0);
-}
-
 void
 in6_tmpaddrtimer(void *arg)
 {
 	CURVNET_SET((struct vnet *) arg);
-	struct nd_ifinfo *ndi;
-	u_int8_t nullbuf[8];
-	struct ifnet *ifp;
 
 	callout_reset(&V_in6_tmpaddrtimer_ch,
 	    (V_ip6_temp_preferred_lifetime - V_ip6_desync_factor -
 	    V_ip6_temp_regen_advance) * hz, in6_tmpaddrtimer, curvnet);
 
-	bzero(nullbuf, sizeof(nullbuf));
-	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
-		if (ifp->if_afdata[AF_INET6] == NULL)
-			continue;
-		ndi = ND_IFINFO(ifp);
-		if (bcmp(ndi->randomid, nullbuf, sizeof(nullbuf)) != 0) {
-			/*
-			 * We've been generating a random ID on this interface.
-			 * Create a new one.
-			 */
-			(void)generate_tmp_ifid(ndi->randomseed0,
-			    ndi->randomseed1, ndi->randomid);
-		}
-	}
-
 	CURVNET_RESTORE();
 }
 

sys/netinet6/in6_ifattach.h

@@ -39,7 +39,6 @@ void in6_ifattach(struct ifnet *, struct ifnet *);
 void in6_ifattach_destroy(void);
 void in6_ifdetach(struct ifnet *);
 void in6_ifdetach_destroy(struct ifnet *);
-int in6_get_tmpifid(struct ifnet *, u_int8_t *, const u_int8_t *, int);
 void in6_tmpaddrtimer(void *);
 int in6_get_hw_ifid(struct ifnet *, struct in6_addr *);
 int in6_nigroup(struct ifnet *, const char *, int, struct in6_addr *);

sys/netinet6/nd6.h

@@ -224,7 +224,7 @@ struct	in6_ndifreq {
 #define RETRANS_TIMER			1000	/* msec */
 #define MIN_RANDOM_FACTOR		512	/* 1024 * 0.5 */
 #define MAX_RANDOM_FACTOR		1536	/* 1024 * 1.5 */
-#define DEF_TEMP_VALID_LIFETIME		604800	/* 1 week */
+#define DEF_TEMP_VALID_LIFETIME		172800	/* 2 days */
 #define DEF_TEMP_PREFERRED_LIFETIME	86400	/* 1 day */
 #define TEMPADDR_REGEN_ADVANCE		5	/* sec */
 #define MAX_TEMP_DESYNC_FACTOR		600	/* 10 min */

sys/netinet6/nd6_rtr.c

@@ -52,6 +52,7 @@
 #include <sys/sysctl.h>
 #include <sys/syslog.h>
 #include <sys/queue.h>
+#include <sys/random.h>
 
 #include <net/if.h>
 #include <net/if_var.h>
@@ -103,6 +104,8 @@ SYSCTL_DECL(_net_inet6_icmp6);
 #define RTPREF_RESERVED	(-2)
 #define RTPREF_INVALID	(-3)	/* internal */
 
+static int in6_get_tmp_ifid(struct in6_aliasreq *);
+
 void
 defrouter_ref(struct nd_defrouter *dr)
 {
@@ -2195,6 +2198,51 @@ nd6_prefix_offlink(struct nd_prefix *pr)
 	return (error);
 }
 
+/*
+ * Get a randomized interface identifier for a temporary address
+ * <draft-ietf-6man-rfc4941bis-08.txt>, Section 3.3.1.
+ */
+static int
+in6_get_tmp_ifid(struct in6_aliasreq *ifra)
+{
+	struct in6_addr *addr;
+
+	if(!is_random_seeded()){
+		return 1;
+	}
+
+	addr = &(ifra->ifra_addr.sin6_addr);
+regen:
+	ifra->ifra_addr.sin6_addr.s6_addr32[2] |=
+	    (arc4random() & ~(ifra->ifra_prefixmask.sin6_addr.s6_addr32[2]));
+	ifra->ifra_addr.sin6_addr.s6_addr32[3] |=
+	    (arc4random() & ~(ifra->ifra_prefixmask.sin6_addr.s6_addr32[3]));
+
+	/*
+	 *  check if generated address is not inappropriate:
+	 *
+	 *  - Reserved IPv6 Interface Identifers
+	 *   (http://www.iana.org/assignments/ipv6-interface-ids/ipv6-interface-ids.xhtml)
+	 */
+
+	/* Subnet-router anycast: 0000:0000:0000:0000 */
+	if (!(addr->s6_addr32[2] | addr->s6_addr32[3]))
+		goto regen;
+
+	/* IANA Ethernet block: 0200:5EFF:FE00:0000-0200:5EFF:FE00:5212
+	   Proxy Mobile IPv6:   0200:5EFF:FE00:5213
+	   IANA Ethernet block: 0200:5EFF:FE00:5214-0200:5EFF:FEFF:FFFF
+	*/
+	if (ntohl(addr->s6_addr32[2]) == 0x02005eff && (ntohl(addr->s6_addr32[3]) & 0Xff000000) == 0xfe000000)
+		goto regen;
+
+	/* Reserved subnet anycast addresses */
+	if (ntohl(addr->s6_addr32[2]) == 0xfdffffff && ntohl(addr->s6_addr32[3]) >= 0Xffffff80)
+		goto regen;
+
+	return 0;
+}
+
 /*
  * ia0 - corresponding public address
  */
@@ -2207,7 +2255,6 @@ in6_tmpifadd(const struct in6_ifaddr *ia0, int forcegen, int delay)
 	int error;
 	int trylimit = 3;	/* XXX: adhoc value */
 	int updateflags;
-	u_int32_t randid[2];
 	time_t vltime0, pltime0;
 
 	in6_prepare_ifra(&ifra, &ia0->ia_addr.sin6_addr,
@@ -2219,24 +2266,18 @@ in6_tmpifadd(const struct in6_ifaddr *ia0, int forcegen, int delay)
 	    &ifra.ifra_prefixmask.sin6_addr);
 
   again:
-	if (in6_get_tmpifid(ifp, (u_int8_t *)randid,
-	    (const u_int8_t *)&ia0->ia_addr.sin6_addr.s6_addr[8], forcegen)) {
+	if (in6_get_tmp_ifid(&ifra) != 0) {
 		nd6log((LOG_NOTICE, "%s: failed to find a good random IFID\n",
 		    __func__));
 		return (EINVAL);
 	}
-	ifra.ifra_addr.sin6_addr.s6_addr32[2] |=
-	    (randid[0] & ~(ifra.ifra_prefixmask.sin6_addr.s6_addr32[2]));
-	ifra.ifra_addr.sin6_addr.s6_addr32[3] |=
-	    (randid[1] & ~(ifra.ifra_prefixmask.sin6_addr.s6_addr32[3]));
 
 	/*
 	 * in6_get_tmpifid() quite likely provided a unique interface ID.
 	 * However, we may still have a chance to see collision, because
 	 * there may be a time lag between generation of the ID and generation
 	 * of the address.  So, we'll do one more sanity check.
 	 */
-
 	if (in6_localip(&ifra.ifra_addr.sin6_addr) != 0) {
 		if (trylimit-- > 0) {
 			forcegen = 1;