From: Hans Dedecker <dedeckeh@gmail.com>
Date: Thu, 14 Dec 2017 13:13:34 +0000 (+0100)
Subject: interface-ip: fix race condition in IPv6 prefix address generation
X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fnetifd.git;a=commitdiff_plain;h=81ff6d120e8c247b7c714daefd45ae7b90e3b643

interface-ip: fix race condition in IPv6 prefix address generation

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@gmail.com>
---

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)) {