Automatically add a IPv6 link-local address to carp interfaces when the

virtual MAC address is set. Among other things, this makes route6d work
correctly on systems with carp interfaces.

In order to ensure backwards compatibility, we do not include IPv6
link-local addresses in generating the HMAC, but we accept HMACs with AND
without the link-local addresses. They will be added to the HMAC in a future
release.

In short: this change should only affect backwards compatibility for
IPv6 users who are manually adding link-local addresses on carp interfaces.

testing mtu@ todd@
ok mpf@ henning@ deraadt@

1 files changed, 64 insertions, 23 deletions

diff --git a/sys/netinet/ip_carp.c b/sys/netinet/ip_carp.c
index 8a69b658aac..2d23fa9fb9e 100644
--- a/sys/netinet/ip_carp.c
+++ b/sys/netinet/ip_carp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_carp.c,v 1.129 2006/08/28 17:29:53 mcbride Exp $	*/
+/*	$OpenBSD: ip_carp.c,v 1.130 2006/08/31 12:37:31 mcbride Exp $	*/
 
 /*
  * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
@@ -83,6 +83,7 @@
 #include <netinet/ip6.h>
 #include <netinet6/ip6_var.h>
 #include <netinet6/nd6.h>
+#include <netinet6/in6_ifattach.h>
 #endif
 
 #include "bpfilter.h"
@@ -101,6 +102,8 @@ struct carp_mc_entry {
 };
 #define	mc_enm	mc_u.mcu_enm
 
+enum { HMAC_ORIG=0, HMAC_NOV6LL=1, HMAC_MAX=2 };
+
 struct carp_softc {
 	struct arpcom sc_ac;
 #define	sc_if		sc_ac.ac_if
@@ -135,7 +138,8 @@ struct carp_softc {
 #define CARP_HMAC_PAD	64
 	unsigned char sc_key[CARP_KEY_LEN];
 	unsigned char sc_pad[CARP_HMAC_PAD];
-	SHA1_CTX sc_sha1;
+
+	SHA1_CTX sc_sha1[HMAC_MAX];
 	u_int32_t sc_hashkey[2];
 
 	struct timeout sc_ad_tmo;	/* advertisement timeout */
@@ -168,8 +172,9 @@ struct carp_if {
 	}
 
 void	carp_hmac_prepare(struct carp_softc *);
+void	carp_hmac_prepare_ctx(struct carp_softc *, u_int8_t);
 void	carp_hmac_generate(struct carp_softc *, u_int32_t *,
-	    unsigned char *);
+	    unsigned char *, u_int8_t);
 int	carp_hmac_verify(struct carp_softc *, u_int32_t *,
 	    unsigned char *);
 void	carp_setroute(struct carp_softc *, int);
@@ -221,6 +226,15 @@ carp_cksum(struct mbuf *m, int len)
 void
 carp_hmac_prepare(struct carp_softc *sc)
 {
+	u_int8_t i;
+
+	for (i=0; i < HMAC_MAX; i++)
+		carp_hmac_prepare_ctx(sc, i);
+}
+
+void
+carp_hmac_prepare_ctx(struct carp_softc *sc, u_int8_t ctx)
+{
 	u_int8_t version = CARP_VERSION, type = CARP_ADVERTISEMENT;
 	u_int8_t vhid = sc->sc_vhid & 0xff;
 	SHA1_CTX sha1ctx;
@@ -239,19 +253,19 @@ carp_hmac_prepare(struct carp_softc *sc)
 		sc->sc_pad[i] ^= 0x36;
 
 	/* precompute first part of inner hash */
-	SHA1Init(&sc->sc_sha1);
-	SHA1Update(&sc->sc_sha1, sc->sc_pad, sizeof(sc->sc_pad));
-	SHA1Update(&sc->sc_sha1, (void *)&version, sizeof(version));
-	SHA1Update(&sc->sc_sha1, (void *)&type, sizeof(type));
+	SHA1Init(&sc->sc_sha1[ctx]);
+	SHA1Update(&sc->sc_sha1[ctx], sc->sc_pad, sizeof(sc->sc_pad));
+	SHA1Update(&sc->sc_sha1[ctx], (void *)&version, sizeof(version));
+	SHA1Update(&sc->sc_sha1[ctx], (void *)&type, sizeof(type));
 
 	/* generate a key for the arpbalance hash, before the vhid is hashed */
-	bcopy(&sc->sc_sha1, &sha1ctx, sizeof(sha1ctx));
+	bcopy(&sc->sc_sha1[ctx], &sha1ctx, sizeof(sha1ctx));
 	SHA1Final((unsigned char *)kmd, &sha1ctx);
 	sc->sc_hashkey[0] = kmd[0] ^ kmd[1];
 	sc->sc_hashkey[1] = kmd[2] ^ kmd[3];
 
 	/* the rest of the precomputation */
-	SHA1Update(&sc->sc_sha1, (void *)&vhid, sizeof(vhid));
+	SHA1Update(&sc->sc_sha1[ctx], (void *)&vhid, sizeof(vhid));
 
 	/* Hash the addresses from smallest to largest, not interface order */
 #ifdef INET
@@ -270,7 +284,8 @@ carp_hmac_prepare(struct carp_softc *sc)
 			}
 		}
 		if (found)
-			SHA1Update(&sc->sc_sha1, (void *)&cur, sizeof(cur));
+			SHA1Update(&sc->sc_sha1[ctx],
+			    (void *)&cur, sizeof(cur));
 	} while (found);
 #endif /* INET */
 #ifdef INET6
@@ -281,8 +296,11 @@ carp_hmac_prepare(struct carp_softc *sc)
 		memset(&cur6, 0xff, sizeof(cur6));
 		TAILQ_FOREACH(ifa, &sc->sc_if.if_addrlist, ifa_list) {
 			in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
-			if (IN6_IS_ADDR_LINKLOCAL(&in6))
+			if (IN6_IS_ADDR_LINKLOCAL(&in6)) {
+				if (ctx == HMAC_NOV6LL)
+					continue;
 				in6.s6_addr16[1] = 0;
+			}
 			if (ifa->ifa_addr->sa_family == AF_INET6 &&
 			    memcmp(&in6, &last6, sizeof(in6)) > 0 &&
 			    memcmp(&in6, &cur6, sizeof(in6)) < 0) {
@@ -291,7 +309,8 @@ carp_hmac_prepare(struct carp_softc *sc)
 			}
 		}
 		if (found)
-			SHA1Update(&sc->sc_sha1, (void *)&cur6, sizeof(cur6));
+			SHA1Update(&sc->sc_sha1[ctx],
+			    (void *)&cur6, sizeof(cur6));
 	} while (found);
 #endif /* INET6 */
 
@@ -302,12 +321,12 @@ carp_hmac_prepare(struct carp_softc *sc)
 
 void
 carp_hmac_generate(struct carp_softc *sc, u_int32_t counter[2],
-    unsigned char md[20])
+    unsigned char md[20], u_int8_t ctx)
 {
 	SHA1_CTX sha1ctx;
 
 	/* fetch first half of inner hash */
-	bcopy(&sc->sc_sha1, &sha1ctx, sizeof(sha1ctx));
+	bcopy(&sc->sc_sha1[ctx], &sha1ctx, sizeof(sha1ctx));
 
 	SHA1Update(&sha1ctx, (void *)counter, sizeof(sc->sc_counter));
 	SHA1Final(md, &sha1ctx);
@@ -324,10 +343,14 @@ carp_hmac_verify(struct carp_softc *sc, u_int32_t counter[2],
     unsigned char md[20])
 {
 	unsigned char md2[20];
+	u_int8_t i;
 
-	carp_hmac_generate(sc, counter, md2);
-
-	return (bcmp(md, md2, sizeof(md2)));
+	for (i=0; i < HMAC_MAX; i++) { 
+		carp_hmac_generate(sc, counter, md2, i);
+		if (!bcmp(md, md2, sizeof(md2)))
+			return (0);
+	}
+	return (1);
 }
 
 void
@@ -891,7 +914,11 @@ carp_prepare_ad(struct mbuf *m, struct carp_softc *sc, struct carp_header *ch)
 	ch->carp_counter[0] = htonl((sc->sc_counter>>32)&0xffffffff);
 	ch->carp_counter[1] = htonl(sc->sc_counter&0xffffffff);
 
-	carp_hmac_generate(sc, ch->carp_counter, ch->carp_md);
+	/*
+	 * For the time being, do not include the IPv6 linklayer addresses
+	 * in the HMAC.
+	 */
+	carp_hmac_generate(sc, ch->carp_counter, ch->carp_md, HMAC_NOV6LL);
 
 	return (0);
 }
@@ -1596,8 +1623,9 @@ carp_set_ifp(struct carp_softc *sc, struct ifnet *ifp)
 void
 carp_set_enaddr(struct carp_softc *sc)
 {
-	if (sc->sc_vhid == -1) {
+	if (sc->sc_vhid == -1 || !sc->sc_carpdev) {
 		bzero(&sc->sc_ac.ac_enaddr, sizeof (sc->sc_ac.ac_enaddr));
+		/* XXX detach ipv6 link-local address? */
 	} else if (sc->sc_carpdev && sc->sc_carpdev->if_type == IFT_ISO88025) {
 		sc->sc_ac.ac_enaddr[0] = 3;
 		sc->sc_ac.ac_enaddr[1] = 0;
@@ -1614,8 +1642,20 @@ carp_set_enaddr(struct carp_softc *sc)
 		sc->sc_ac.ac_enaddr[5] = sc->sc_vhid;
 	}
 
-	bcopy(&sc->sc_ac.ac_enaddr,
-	    LLADDR(sc->sc_if.if_sadl), sc->sc_if.if_addrlen);
+	/* Make sure the enaddr has changed before further twiddling. */
+	if (bcmp(&sc->sc_ac.ac_enaddr, LLADDR(sc->sc_if.if_sadl),
+	    sc->sc_if.if_addrlen) != 0) {
+		bcopy(&sc->sc_ac.ac_enaddr,
+		    LLADDR(sc->sc_if.if_sadl), sc->sc_if.if_addrlen);
+
+#ifdef INET6
+		/*
+		 * (re)attach a link-local address which matches
+		 * our new MAC address.
+		 */
+		in6_ifattach_linklocal(&sc->sc_if, NULL);
+#endif
+	}
 }
 
 void
@@ -1808,8 +1848,9 @@ carp_set_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
 	if (sc->sc_naddrs6 == 0 && (error = carp_join_multicast6(sc)) != 0)
 		return (error);
 
-	sc->sc_naddrs6++;
-	if (sc->sc_carpdev != NULL)
+	if (!IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr))
+		sc->sc_naddrs6++;
+	if (sc->sc_carpdev != NULL && sc->sc_naddrs6)
 		sc->sc_if.if_flags |= IFF_UP;
 	carp_set_state(sc, INIT);
 	carp_setrun(sc, 0);