[LEDE-DEV] [PATCH 1/2 netifd] interface-ip: fix race condition in IPv6 prefix address generation

[Hans Dedecker]

Don't generate an IPv6 prefix address without taking into account the
interface state. In case eui64 is configured to generate the ifaceid this
could fail as the layer3 device mac address could not yet be available if
the interface is not yet in setup or up state.
While at it remove the interface metric assignment as this is already done
by the function interface_set_route_info.

Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
---
 interface-ip.c | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/interface-ip.c b/interface-ip.c
index 1490ca4..716a093 100644
--- a/interface-ip.c
+++ b/interface-ip.c
@@ -761,15 +761,7 @@ interface_set_prefix_address(struct device_prefix_assignment *assignment,
 	memset(&addr, 0, sizeof(addr));
 	memset(&route, 0, sizeof(route));
 
-	if (IN6_IS_ADDR_UNSPECIFIED(&assignment->addr)) {
-		addr.addr.in6 = prefix->addr;
-		addr.addr.in6.s6_addr32[1] |= htonl(assignment->assigned);
-		generate_ifaceid(iface, &addr.addr.in6);
-		assignment->addr = addr.addr.in6;
-	}
-	else
-		addr.addr.in6 = assignment->addr;
-
+	addr.addr.in6 = assignment->addr;
 	addr.mask = assignment->length;
 	addr.flags = DEVADDR_INET6 | DEVADDR_OFFLINK;
 	addr.preferred_until = prefix->preferred_until;
@@ -778,11 +770,10 @@ interface_set_prefix_address(struct device_prefix_assignment *assignment,
 	route.flags = DEVADDR_INET6;
 	route.mask = addr.mask < 64 ? 64 : addr.mask;
 	route.addr = addr.addr;
-	clear_if_addr(&route.addr, route.mask);
-	interface_set_route_info(iface, &route);
 
 	if (!add && assignment->enabled) {
 		time_t now = system_get_rtime();
+
 		addr.preferred_until = now;
 		if (!addr.valid_until || addr.valid_until - now > 7200)
 			addr.valid_until = now + 7200;
@@ -800,12 +791,24 @@ interface_set_prefix_address(struct device_prefix_assignment *assignment,
 							addr.mask, 0, iface, "unreachable", true);
 		}
 
+		clear_if_addr(&route.addr, route.mask);
+		interface_set_route_info(iface, &route);
+
 		system_del_route(l3_downlink, &route);
 		system_add_address(l3_downlink, &addr);
 
 		assignment->enabled = false;
-	} else if (add && (iface->state == IFS_UP || iface->state == IFS_SETUP) &&
-			!system_add_address(l3_downlink, &addr)) {
+	} else if (add && (iface->state == IFS_UP || iface->state == IFS_SETUP)) {
+		if (IN6_IS_ADDR_UNSPECIFIED(&addr.addr.in6)) {
+			addr.addr.in6 = prefix->addr;
+			addr.addr.in6.s6_addr32[1] |= htonl(assignment->assigned);
+			generate_ifaceid(iface, &addr.addr.in6);
+			assignment->addr = addr.addr.in6;
+			route.addr = addr.addr;
+		}
+
+		if (system_add_address(l3_downlink, &addr))
+			return;
 
 		if (!assignment->enabled) {
 			if (iface->ip6table)
@@ -822,7 +825,9 @@ interface_set_prefix_address(struct device_prefix_assignment *assignment,
 			}
 		}
 
-		route.metric = iface->metric;
+		clear_if_addr(&route.addr, route.mask);
+		interface_set_route_info(iface, &route);
+
 		system_add_route(l3_downlink, &route);
 
 		if (uplink && uplink->l3_dev.dev && !(l3_downlink->settings.flags & DEV_OPT_MTU6)) {
-- 
1.9.1