vpn: merge branch 'th/vpn-route-bgo787370'

Fix and improve determining the route to the external VPN gateway.

https://bugzilla.gnome.org/show_bug.cgi?id=787370

6 files changed, 97 insertions, 72 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 8001e74b0..55ad6c323 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -10038,6 +10038,11 @@ nm_device_replace_vpn4_config (NMDevice *self, NMIP4Config *old, NMIP4Config *co
 {
 	NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE (self);
 
+	nm_assert (!old || NM_IS_IP4_CONFIG (old));
+	nm_assert (!config || NM_IS_IP4_CONFIG (config));
+	nm_assert (!old || nm_ip4_config_get_ifindex (old) == nm_device_get_ip_ifindex (self));
+	nm_assert (!config || nm_ip4_config_get_ifindex (config) == nm_device_get_ip_ifindex (self));
+
 	if (!_replace_vpn_config_in_list (&priv->vpn4_configs, (GObject *) old, (GObject *) config))
 		return;
 
@@ -10167,6 +10172,11 @@ nm_device_replace_vpn6_config (NMDevice *self, NMIP6Config *old, NMIP6Config *co
 {
 	NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE (self);
 
+	nm_assert (!old || NM_IS_IP6_CONFIG (old));
+	nm_assert (!config || NM_IS_IP6_CONFIG (config));
+	nm_assert (!old || nm_ip6_config_get_ifindex (old) == nm_device_get_ip_ifindex (self));
+	nm_assert (!config || nm_ip6_config_get_ifindex (config) == nm_device_get_ip_ifindex (self));
+
 	if (!_replace_vpn_config_in_list (&priv->vpn6_configs, (GObject *) old, (GObject *) config))
 		return;
 
diff --git a/src/platform/nm-linux-platform.c b/src/platform/nm-linux-platform.c
index a018f6b70..5c952a0b2 100644
--- a/src/platform/nm-linux-platform.c
+++ b/src/platform/nm-linux-platform.c
@@ -6033,6 +6033,7 @@ static NMPlatformError
 ip_route_get (NMPlatform *platform,
               int addr_family,
               gconstpointer address,
+              int oif_ifindex,
               NMPObject **out_route)
 {
 	const gboolean is_v4 = (addr_family == AF_INET);
@@ -6066,6 +6067,13 @@ ip_route_get (NMPlatform *platform,
 		if (!_nl_addattr_l (&req.n, sizeof (req), RTA_DST, address, addr_len))
 			nm_assert_not_reached ();
 
+		if (oif_ifindex > 0) {
+			gint32 ii = oif_ifindex;
+
+			if (!_nl_addattr_l (&req.n, sizeof (req), RTA_OIF, &ii, sizeof (ii)))
+				nm_assert_not_reached ();
+		}
+
 		seq_result = WAIT_FOR_NL_RESPONSE_RESULT_UNKNOWN;
 		nle = _nl_send_nlmsghdr (platform, &req.n, &seq_result, DELAYED_ACTION_RESPONSE_TYPE_ROUTE_GET, &route);
 		if (nle < 0) {
diff --git a/src/platform/nm-platform.c b/src/platform/nm-platform.c
index 8542c945b..7e91b7547 100644
--- a/src/platform/nm-platform.c
+++ b/src/platform/nm-platform.c
@@ -3888,12 +3888,14 @@ NMPlatformError
 nm_platform_ip_route_get (NMPlatform *self,
                           int addr_family,
                           gconstpointer address /* in_addr_t or struct in6_addr */,
+                          int oif_ifindex,
                           NMPObject **out_route)
 {
 	nm_auto_nmpobj NMPObject *route = NULL;
 	NMPlatformError result;
 	char buf[NM_UTILS_INET_ADDRSTRLEN];
 	char buf_err[200];
+	char buf_oif[64];
 
 	_CHECK_SELF (self, klass, FALSE);
 
@@ -3901,9 +3903,10 @@ nm_platform_ip_route_get (NMPlatform *self,
 	g_return_val_if_fail (NM_IN_SET (addr_family, AF_INET,
 	                                              AF_INET6), NM_PLATFORM_ERROR_BUG);
 
-	_LOGT ("route: get IPv%c route for: %s",
+	_LOGT ("route: get IPv%c route for: %s%s",
 	       addr_family == AF_INET ? '4' : '6',
-	       inet_ntop (addr_family, address, buf, sizeof (buf)));
+	       inet_ntop (addr_family, address, buf, sizeof (buf)),
+	       oif_ifindex > 0 ? nm_sprintf_buf (buf_oif, " oif %d", oif_ifindex) : "");
 
 	if (!klass->ip_route_get)
 		result = NM_PLATFORM_ERROR_OPNOTSUPP;
@@ -3911,6 +3914,7 @@ nm_platform_ip_route_get (NMPlatform *self,
 		result = klass->ip_route_get (self,
 		                              addr_family,
 		                              address,
+		                              oif_ifindex,
 		                              &route);
 	}
 
diff --git a/src/platform/nm-platform.h b/src/platform/nm-platform.h
index e14c71512..b29e6668d 100644
--- a/src/platform/nm-platform.h
+++ b/src/platform/nm-platform.h
@@ -823,6 +823,7 @@ typedef struct {
 	NMPlatformError (*ip_route_get) (NMPlatform *self,
 	                                 int addr_family,
 	                                 gconstpointer address,
+	                                 int oif_ifindex,
 	                                 NMPObject **out_route);
 
 	gboolean (*check_support_kernel_extended_ifa_flags) (NMPlatform *);
@@ -1186,6 +1187,7 @@ gboolean nm_platform_ip_route_flush (NMPlatform *self,
 NMPlatformError nm_platform_ip_route_get (NMPlatform *self,
                                           int addr_family,
                                           gconstpointer address,
+                                          int oif_ifindex,
                                           NMPObject **out_route);
 
 const char *nm_platform_link_to_string (const NMPlatformLink *link, char *buf, gsize len);
diff --git a/src/platform/tests/test-route.c b/src/platform/tests/test-route.c
index f749d7514..2c00fadaa 100644
--- a/src/platform/tests/test-route.c
+++ b/src/platform/tests/test-route.c
@@ -409,6 +409,7 @@ test_ip_route_get (void)
 	result = nm_platform_ip_route_get (NM_PLATFORM_GET,
 	                                   AF_INET,
 	                                   &a,
+	                                   nmtst_get_rand_int () % 2 ? 0 : ifindex,
 	                                   &route);
 
 	g_assert (result == NM_PLATFORM_ERROR_SUCCESS);
@@ -417,6 +418,7 @@ test_ip_route_get (void)
 	g_assert (route->parent._ref_count == 1);
 	r = NMP_OBJECT_CAST_IP4_ROUTE (route);
 	g_assert (r->rt_cloned);
+	g_assert (r->ifindex == ifindex);
 	g_assert (r->network == a);
 	g_assert (r->plen == 32);
 
diff --git a/src/vpn/nm-vpn-connection.c b/src/vpn/nm-vpn-connection.c
index 11eb9a495..bd86007ac 100644
--- a/src/vpn/nm-vpn-connection.c
+++ b/src/vpn/nm-vpn-connection.c
@@ -710,47 +710,51 @@ add_ip4_vpn_gateway_route (NMIP4Config *config,
                            in_addr_t vpn_gw,
                            NMPlatform *platform)
 {
-	NMIP4Config *parent_config;
-	guint32 parent_gw;
+	guint32 parent_gw = 0;
+	gboolean has_parent_gw = FALSE;
 	NMPlatformIP4Route route;
+	int ifindex;
 	guint32 route_metric;
 	nm_auto_nmpobj const NMPObject *route_resolved = NULL;
 
 	g_return_if_fail (NM_IS_IP4_CONFIG (config));
 	g_return_if_fail (NM_IS_DEVICE (parent_device));
 	g_return_if_fail (vpn_gw != 0);
-	nm_assert (nm_ip4_config_get_ifindex (config) > 0);
 
-	/* Set up a route to the VPN gateway's public IP address through the default
-	 * network device if the VPN gateway is on a different subnet.
-	 */
-	parent_config = nm_device_get_ip4_config (parent_device);
-	g_return_if_fail (parent_config != NULL);
+	ifindex = nm_ip4_config_get_ifindex (config);
 
-	parent_gw = nm_ip4_config_get_gateway (parent_config);
+	nm_assert (ifindex > 0);
+	nm_assert (ifindex == nm_device_get_ip_ifindex (parent_device));
 
-	/* If the VPN gateway is in the same subnet as one of the parent device's
-	 * IP addresses, don't add the host route to it, but a route through the
-	 * parent device.
-	 */
-	if (nm_ip4_config_destination_is_direct (parent_config, vpn_gw, 32))
-		parent_gw = 0;
-
-	/* actually, let's ask kernel how to reach @vpn_gw. If (and only if)
-	 * the destination is on @parent_device, then we take that @parent_gw. */
+	/* Ask kernel how to reach @vpn_gw. We can only inject the route in
+	 * @parent_device, so whatever we resolve, it can only be on @ifindex. */
 	if (nm_platform_ip_route_get (platform,
 	                              AF_INET,
 	                              &vpn_gw,
+	                              ifindex,
 	                              (NMPObject **) &route_resolved) == NM_PLATFORM_ERROR_SUCCESS) {
 		const NMPlatformIP4Route *r = NMP_OBJECT_CAST_IP4_ROUTE (route_resolved);
 
-		if (r->ifindex == nm_ip4_config_get_ifindex (config))
-			parent_gw = r->gateway;
+		if (r->ifindex == ifindex) {
+			/* `ip route get` always resolves the route, even if the destination is unreachable.
+			 * In which case, it pretends the destination is directly reachable.
+			 *
+			 * So, only accept direct routes, if @vpn_gw is a private network. */
+			if (   r->gateway
+			    || nm_utils_ip_is_site_local (AF_INET, &vpn_gw)) {
+				parent_gw = r->gateway;
+				has_parent_gw = TRUE;
+			}
+		}
 	}
 
+	if (!has_parent_gw)
+		return;
+
 	route_metric = nm_device_get_ip4_route_metric (parent_device);
 
 	memset (&route, 0, sizeof (route));
+	route.ifindex = ifindex;
 	route.network = vpn_gw;
 	route.plen = 32;
 	route.gateway = parent_gw;
@@ -779,51 +783,55 @@ add_ip6_vpn_gateway_route (NMIP6Config *config,
                            const struct in6_addr *vpn_gw,
                            NMPlatform *platform)
 {
-	NMIP6Config *parent_config;
-	const struct in6_addr *parent_gw;
+	const struct in6_addr *parent_gw = NULL;
+	gboolean has_parent_gw = FALSE;
 	NMPlatformIP6Route route;
+	int ifindex;
 	guint32 route_metric;
 	nm_auto_nmpobj const NMPObject *route_resolved = NULL;
 
 	g_return_if_fail (NM_IS_IP6_CONFIG (config));
 	g_return_if_fail (NM_IS_DEVICE (parent_device));
 	g_return_if_fail (vpn_gw != NULL);
-	nm_assert (nm_ip6_config_get_ifindex (config) > 0);
-
-	parent_config = nm_device_get_ip6_config (parent_device);
-	g_return_if_fail (parent_config != NULL);
 
-	/* we add a direct route to the VPN gateway, but we only do that
-	 * on the @parent_device. That is probably not correct in every case... */
-	parent_gw = nm_ip6_config_get_gateway (parent_config);
-	if (!parent_gw)
-		return;
+	ifindex = nm_ip6_config_get_ifindex (config);
 
-	/* If the VPN gateway is in the same subnet as one of the parent device's
-	 * IP addresses, don't add the host route to it, but a route through the
-	 * parent device.
-	 */
-	if (nm_ip6_config_destination_is_direct (parent_config, vpn_gw, 128))
-		parent_gw = &in6addr_any;
+	nm_assert (ifindex > 0);
+	nm_assert (ifindex == nm_device_get_ip_ifindex (parent_device));
 
-	/* actually, let's ask kernel how to reach @vpn_gw. If (and only if)
-	 * the destination is on @parent_device, then we take that @parent_gw. */
+	/* Ask kernel how to reach @vpn_gw. We can only inject the route in
+	 * @parent_device, so whatever we resolve, it can only be on @ifindex. */
 	if (nm_platform_ip_route_get (platform,
 	                              AF_INET6,
 	                              vpn_gw,
+	                              ifindex,
 	                              (NMPObject **) &route_resolved) == NM_PLATFORM_ERROR_SUCCESS) {
 		const NMPlatformIP6Route *r = NMP_OBJECT_CAST_IP6_ROUTE (route_resolved);
 
-		if (r->ifindex == nm_ip6_config_get_ifindex (config))
-			parent_gw = &r->gateway;
+		if (r->ifindex == ifindex) {
+			/* `ip route get` always resolves the route, even if the destination is unreachable.
+			 * In which case, it pretends the destination is directly reachable.
+			 *
+			 * So, only accept direct routes, if @vpn_gw is a private network. */
+			if (   !IN6_IS_ADDR_UNSPECIFIED (&r->gateway)
+			    || nm_utils_ip_is_site_local (AF_INET6, &vpn_gw)) {
+				parent_gw = &r->gateway;
+				has_parent_gw = TRUE;
+			}
+		}
 	}
 
+	if (!has_parent_gw)
+		return;
+
 	route_metric = nm_device_get_ip6_route_metric (parent_device);
 
 	memset (&route, 0, sizeof (route));
+	route.ifindex = ifindex;
 	route.network = *vpn_gw;
 	route.plen = 128;
-	route.gateway = *parent_gw;
+	if (parent_gw)
+		route.gateway = *parent_gw;
 	route.rt_source = NM_IP_CONFIG_SOURCE_VPN;
 	route.metric = route_metric;
 	nm_ip6_config_add_route (config, &route);
@@ -833,7 +841,7 @@ add_ip6_vpn_gateway_route (NMIP6Config *config,
 	 * routes include a subnet that matches the parent device's subnet,
 	 * the parent device's gateway would get routed through the VPN and fail.
 	 */
-	if (!IN6_IS_ADDR_UNSPECIFIED (parent_gw)) {
+	if (parent_gw && !IN6_IS_ADDR_UNSPECIFIED (parent_gw)) {
 		memset (&route, 0, sizeof (route));
 		route.network = *parent_gw;
 		route.plen = 128;
@@ -1075,40 +1083,31 @@ apply_parent_device_config (NMVpnConnection *self)
 {
 	NMVpnConnectionPrivate *priv = NM_VPN_CONNECTION_GET_PRIVATE (self);
 	NMDevice *parent_dev = nm_active_connection_get_device (NM_ACTIVE_CONNECTION (self));
+	int ifindex;
 	NMIP4Config *vpn4_parent_config = NULL;
 	NMIP6Config *vpn6_parent_config = NULL;
 
-	if (priv->ip_ifindex > 0) {
-		if (priv->ip4_config) {
-			vpn4_parent_config = nm_ip4_config_new (nm_netns_get_multi_idx (priv->netns),
-			                                        priv->ip_ifindex);
-		}
-		if (priv->ip6_config) {
-			vpn6_parent_config = nm_ip6_config_new (nm_netns_get_multi_idx (priv->netns),
-			                                        priv->ip_ifindex);
-		}
-	} else {
-		int ifindex;
-
+	ifindex = nm_device_get_ip_ifindex (parent_dev);
+	if (ifindex > 0) {
 		/* If the VPN didn't return a network interface, it is a route-based
 		 * VPN (like kernel IPSec) and all IP addressing and routing should
 		 * be done on the parent interface instead.
 		 */
-
-		/* Also clear the gateway. We don't configure the gateway as part of the
-		 * vpn-config. Instead we tell NMDefaultRouteManager directly about the
-		 * default route. */
-		ifindex = nm_device_get_ip_ifindex (parent_dev);
-		if (ifindex > 0) {
-			if (priv->ip4_config) {
-				vpn4_parent_config = nm_ip4_config_new (nm_netns_get_multi_idx (priv->netns),
-				                                        ifindex);
+		if (priv->ip4_config) {
+			vpn4_parent_config = nm_ip4_config_new (nm_netns_get_multi_idx (priv->netns),
+			                                        ifindex);
+			if (priv->ip_ifindex <= 0)
 				nm_ip4_config_merge (vpn4_parent_config, priv->ip4_config, NM_IP_CONFIG_MERGE_NO_DNS);
-			}
-			if (priv->ip6_config) {
-				vpn6_parent_config = nm_ip6_config_new (nm_netns_get_multi_idx (priv->netns),
-				                                        ifindex);
+		}
+		if (priv->ip6_config) {
+			vpn6_parent_config = nm_ip6_config_new (nm_netns_get_multi_idx (priv->netns),
+			                                        ifindex);
+			if (priv->ip_ifindex <= 0) {
 				nm_ip6_config_merge (vpn6_parent_config, priv->ip6_config, NM_IP_CONFIG_MERGE_NO_DNS);
+
+				/* Also clear the gateway. We don't configure the gateway as part of the
+				 * vpn-config. Instead we tell NMDefaultRouteManager directly about the
+				 * default route. */
 				nm_ip6_config_set_gateway (vpn6_parent_config, NULL);
 			}
 		}
@@ -1144,6 +1143,8 @@ nm_vpn_connection_apply_config (NMVpnConnection *self)
 {
 	NMVpnConnectionPrivate *priv = NM_VPN_CONNECTION_GET_PRIVATE (self);
 
+	apply_parent_device_config (self);
+
 	if (priv->ip_ifindex > 0) {
 		nm_platform_link_set_up (nm_netns_get_platform (priv->netns), priv->ip_ifindex, NULL);
 
@@ -1166,8 +1167,6 @@ nm_vpn_connection_apply_config (NMVpnConnection *self)
 			nm_platform_link_set_mtu (nm_netns_get_platform (priv->netns), priv->ip_ifindex, priv->mtu);
 	}
 
-	apply_parent_device_config (self);
-
 	nm_default_route_manager_ip4_update_default_route (nm_netns_get_default_route_manager (priv->netns), self);
 	nm_default_route_manager_ip6_update_default_route (nm_netns_get_default_route_manager (priv->netns), self);