Fix a bug where existing CARP alias addresses cannot be changed.

When a existent address is delete with carp_detach() if it is the last address for that CARP vhid, the CARP vhid will be destroyed and the subsequent carp_attach() to add the new IP will fail.

Ticket #6892

sys/net/if.c

@@ -144,7 +144,7 @@ int	(*carp_output_p)(struct ifnet *ifp, struct mbuf *m,
     const struct sockaddr *sa);
 int	(*carp_ioctl_p)(struct ifreq *, u_long, struct thread *);   
 int	(*carp_attach_p)(struct ifaddr *, int);
-void	(*carp_detach_p)(struct ifaddr *);
+void	(*carp_detach_p)(struct ifaddr *, bool);
 #endif
 #ifdef INET
 int	(*carp_iamatch_p)(struct ifaddr *, uint8_t **);

sys/netinet/in.c

@@ -71,7 +71,7 @@ __FBSDID("$FreeBSD$");
 #include <netinet/udp_var.h>
 
 static int in_aifaddr_ioctl(u_long, caddr_t, struct ifnet *, struct thread *);
-static int in_difaddr_ioctl(caddr_t, struct ifnet *, struct thread *);
+static int in_difaddr_ioctl(u_long, caddr_t, struct ifnet *, struct thread *);
 
 static void	in_socktrim(struct sockaddr_in *);
 static void	in_purgemaddrs(struct ifnet *);
@@ -245,7 +245,7 @@ in_control(struct socket *so, u_long cmd, caddr_t data, struct ifnet *ifp,
 		break;
 	case SIOCDIFADDR:
 		sx_xlock(&in_control_sx);
-		error = in_difaddr_ioctl(data, ifp, td);
+		error = in_difaddr_ioctl(cmd, data, ifp, td);
 		sx_xunlock(&in_control_sx);
 		return (error);
 	case OSIOCAIFADDR:	/* 9.x compat */
@@ -390,7 +390,7 @@ in_aifaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct thread *td)
 	IF_ADDR_RUNLOCK(ifp);
 
 	if (ia != NULL)
-		(void )in_difaddr_ioctl(data, ifp, td);
+		(void )in_difaddr_ioctl(cmd, data, ifp, td);
 
 	ifa = ifa_alloc(sizeof(struct in_ifaddr), M_WAITOK);
 	ia = (struct in_ifaddr *)ifa;
@@ -526,7 +526,7 @@ in_aifaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct thread *td)
 
 fail1:
 	if (ia->ia_ifa.ifa_carp)
-		(*carp_detach_p)(&ia->ia_ifa);
+		(*carp_detach_p)(&ia->ia_ifa, true);
 
 	IF_ADDR_WLOCK(ifp);
 	TAILQ_REMOVE(&ifp->if_addrhead, &ia->ia_ifa, ifa_link);
@@ -543,7 +543,7 @@ in_aifaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct thread *td)
 }
 
 static int
-in_difaddr_ioctl(caddr_t data, struct ifnet *ifp, struct thread *td)
+in_difaddr_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp, struct thread *td)
 {
 	const struct ifreq *ifr = (struct ifreq *)data;
 	const struct sockaddr_in *addr = (const struct sockaddr_in *)
@@ -616,7 +616,8 @@ in_difaddr_ioctl(caddr_t data, struct ifnet *ifp, struct thread *td)
 	in_ifadown(&ia->ia_ifa, 1);
 
 	if (ia->ia_ifa.ifa_carp)
-		(*carp_detach_p)(&ia->ia_ifa);
+		(*carp_detach_p)(&ia->ia_ifa,
+		    (cmd == SIOCDIFADDR) ? true : false);
 
 	/*
 	 * If this is the last IPv4 address configured on this

sys/netinet/ip_carp.c

@@ -1880,7 +1880,7 @@ carp_attach(struct ifaddr *ifa, int vhid)
 }
 
 void
-carp_detach(struct ifaddr *ifa)
+carp_detach(struct ifaddr *ifa, bool destroy)
 {
 	struct ifnet *ifp = ifa->ifa_ifp;
 	struct carp_if *cif = ifp->if_carp;
@@ -1926,12 +1926,13 @@ carp_detach(struct ifaddr *ifa)
 	carp_hmac_prepare(sc);
 	carp_sc_state(sc);
 
-	if (sc->sc_naddrs == 0 && sc->sc_naddrs6 == 0)
+	if (destroy && sc->sc_naddrs == 0 && sc->sc_naddrs6 == 0)
 		carp_destroy(sc);
 	else
 		CARP_UNLOCK(sc);
 
-	CIF_FREE(cif);
+	if (destroy)
+		CIF_FREE(cif);
 
 	sx_xunlock(&carp_sx);
 }

sys/netinet/ip_carp.h

@@ -138,7 +138,7 @@ struct carpreq {
 #ifdef _KERNEL
 int		carp_ioctl(struct ifreq *, u_long, struct thread *);
 int		carp_attach(struct ifaddr *, int);
-void		carp_detach(struct ifaddr *);
+void		carp_detach(struct ifaddr *, bool);
 void		carp_carpdev_state(struct ifnet *);
 int		carp_input(struct mbuf **, int *, int);
 int		carp6_input (struct mbuf **, int *, int);
@@ -154,7 +154,7 @@ int		carp_forus(struct ifnet *, u_char *);
 /* net/if.c */
 extern int (*carp_ioctl_p)(struct ifreq *, u_long, struct thread *);
 extern int (*carp_attach_p)(struct ifaddr *, int);
-extern void (*carp_detach_p)(struct ifaddr *);
+extern void (*carp_detach_p)(struct ifaddr *, bool);
 extern void (*carp_linkstate_p)(struct ifnet *);
 extern void (*carp_demote_adj_p)(int, char *);
 extern int (*carp_master_p)(struct ifaddr *);

sys/netinet6/in6.c

@@ -622,7 +622,7 @@ in6_control(struct socket *so, u_long cmd, caddr_t data,
 			 */
 			if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0) {
 				if (carp_attached)
-					(*carp_detach_p)(&ia->ia_ifa);
+					(*carp_detach_p)(&ia->ia_ifa, false);
 				goto out;
 			}
 		}
@@ -1238,7 +1238,7 @@ in6_purgeaddr(struct ifaddr *ifa)
 	int plen, error;
 
 	if (ifa->ifa_carp)
-		(*carp_detach_p)(ifa);
+		(*carp_detach_p)(ifa, true);
 
 	/*
 	 * Remove the loopback route to the interface address.