net: adjust randomized address bits

Give devices that need a MAC a 16-bit allocation out of the FreeBSD
Foundation OUI range. Change the name ether_fakeaddr to ether_gen_addr now
that we're dealing real MAC addresses with a real OUI rather than random
locally-administered addresses.

Reviewed by:	bz, rgrimes
Differential Revision:	https://reviews.freebsd.org/D19587

sys/net/ethernet.h

@@ -422,7 +422,7 @@ void	ether_vlan_mtap(struct bpf_if *, struct mbuf *,
 struct mbuf  *ether_vlanencap(struct mbuf *, uint16_t);
 bool	ether_8021q_frame(struct mbuf **mp, struct ifnet *ife, struct ifnet *p,
 	    uint16_t vid, uint8_t pcp);
-void	ether_fakeaddr(struct ether_addr *hwaddr);
+void	ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr);
 
 #ifdef _SYS_EVENTHANDLER_H_
 /* new ethernet interface attached event */

sys/net/ieee_oui.h

@@ -67,3 +67,14 @@
 /* Allocate 20 bits to bhyve */
 #define OUI_FREEBSD_BHYVE_LOW	OUI_FREEBSD(0x000001)
 #define OUI_FREEBSD_BHYVE_HIGH	OUI_FREEBSD(0x0fffff)
+
+/*
+ * Allocate 16 bits for a pool to give to various interfaces that need a
+ * generated address, but don't quite need to slice off a whole section of
+ * the OUI (e.g. cloned interfaces, one-off NICs of various vendors).
+ *
+ * ether_gen_addr should be used to generate an address from this pool.
+ */
+#define	OUI_FREEBSD_GENERATED_MASK	0x10ffff
+#define	OUI_FREEBSD_GENERATED_LOW	OUI_FREEBSD(0x100000)
+#define	OUI_FREEBSD_GENERATED_HIGH	OUI_FREEBSD(OU_FREEBSD_GENERATED_MASK)

sys/net/if_bridge.c

@@ -671,7 +671,7 @@ bridge_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 	getcredhostid(curthread->td_ucred, &hostid);
 	do {
 		if (fb || hostid == 0) {
-			ether_fakeaddr(&sc->sc_defaddr);
+			ether_gen_addr(ifp, &sc->sc_defaddr);
 		} else {
 			sc->sc_defaddr.octet[0] = 0x2;
 			sc->sc_defaddr.octet[1] = (hostid >> 24) & 0xff;

sys/net/if_ethersubr.c

@@ -42,11 +42,13 @@
 #include <sys/systm.h>
 #include <sys/bus.h>
 #include <sys/eventhandler.h>
+#include <sys/jail.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
 #include <sys/mbuf.h>
+#include <sys/proc.h>
 #include <sys/priv.h>
 #include <sys/random.h>
 #include <sys/socket.h>
@@ -54,6 +56,7 @@
 #include <sys/sysctl.h>
 #include <sys/uuid.h>
 
+#include <net/ieee_oui.h>
 #include <net/if.h>
 #include <net/if_var.h>
 #include <net/if_arp.h>
@@ -85,6 +88,8 @@
 #endif
 #include <security/mac/mac_framework.h>
 
+#include <crypto/sha1.h>
+
 #ifdef CTASSERT
 CTASSERT(sizeof (struct ether_header) == ETHER_ADDR_LEN * 2 + 2);
 CTASSERT(sizeof (struct ether_addr) == ETHER_ADDR_LEN);
@@ -1401,19 +1406,37 @@ ether_8021q_frame(struct mbuf **mp, struct ifnet *ife, struct ifnet *p,
 	return (true);
 }
 
+/*
+ * Allocate an address from the FreeBSD Foundation OUI.  This uses a
+ * cryptographic hash function on the containing jail's UUID and the interface
+ * name to attempt to provide a unique but stable address.  Pseudo-interfaces
+ * which require a MAC address should use this function to allocate
+ * non-locally-administered addresses.
+ */
 void
-ether_fakeaddr(struct ether_addr *hwaddr)
+ether_gen_addr(struct ifnet *ifp, struct ether_addr *hwaddr)
 {
+#define	ETHER_GEN_ADDR_BUFSIZ	HOSTUUIDLEN + IFNAMSIZ + 2
+	SHA1_CTX ctx;
+	char buf[ETHER_GEN_ADDR_BUFSIZ];
+	char uuid[HOSTUUIDLEN + 1];
+	uint64_t addr;
+	int i, sz;
+	char digest[SHA1_RESULTLEN];
 
-	/*
-	 * Generate a convenient locally administered address,
-	 * 'bsd' + random 24 low-order bits.  'b' is 0x62, which has the locally
-	 * assigned bit set, and the broadcast/multicast bit clear.
-	 */
-	arc4rand(hwaddr->octet, ETHER_ADDR_LEN, 1);
-	hwaddr->octet[0] = 'b';
-	hwaddr->octet[1] = 's';
-	hwaddr->octet[2] = 'd';
+	getcredhostuuid(curthread->td_ucred, uuid, sizeof(uuid));
+	sz = snprintf(buf, ETHER_GEN_ADDR_BUFSIZ, "%s-%s", uuid, ifp->if_xname);
+	SHA1Init(&ctx);
+	SHA1Update(&ctx, buf, sz);
+	SHA1Final(digest, &ctx);
+
+	addr = ((digest[0] << 16) | (digest[1] << 8) | digest[2]) &
+	    OUI_FREEBSD_GENERATED_MASK;
+	addr = OUI_FREEBSD(addr);
+	for (i = 0; i < ETHER_ADDR_LEN; ++i) {
+		hwaddr->octet[i] = addr >> ((ETHER_ADDR_LEN - i - 1) * 8) &
+		    0xFF;
+	}
 }
 
 DECLARE_MODULE(ether, ether_mod, SI_SUB_INIT_IF, SI_ORDER_ANY);

sys/net/if_vxlan.c

@@ -2754,7 +2754,7 @@ vxlan_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 	ifmedia_add(&sc->vxl_media, IFM_ETHER | IFM_AUTO, 0, NULL);
 	ifmedia_set(&sc->vxl_media, IFM_ETHER | IFM_AUTO);
 
-	ether_fakeaddr(&sc->vxl_hwaddr);
+	ether_gen_addr(ifp, &sc->vxl_hwaddr);
 	ether_ifattach(ifp, sc->vxl_hwaddr.octet);
 
 	ifp->if_baudrate = 0;