device: track used shared-ips via NMNetnsth/device-track-shared-ips

Note that when NetworkManager tries to allocate more than 256 networks,
then previously the allocation would fail. We no longer fail, but log an
error and reuse the last address (10.42.255.1/24).

It's simpler to have code that cannot fail, because it's often hard to
handle failure properly. Also, if the user would configure two shared
profiles that explicitly use the same subnet, we also wouldn't fail. Why
not? Is that not a problem as well? If it is not, there is no need to
fail in this case. If it is a problem, then it would be much more
important to handle this case otherwise -- since it's more likely to
activate two profiles that accidentally use the same subnet than
activating 257+ shared profiles.

1 files changed, 13 insertions, 37 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index c1a2bab12b..f0fe5a0385 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -327,6 +327,8 @@ typedef struct _NMDevicePrivate {
 
 	const NML3ConfigData *l3cds[_L3_CONFIG_DATA_TYPE_NUM];
 
+	NMNetnsSharedIPHandle *shared_ip_handle;
+
 	int parent_ifindex;
 
 	int auth_retries;
@@ -9649,21 +9651,11 @@ nm_device_dhcp4_renew (NMDevice *self, gboolean release)
 
 /*****************************************************************************/
 
-static GHashTable *shared_ips = NULL;
-
-static void
-shared_ip_release (gpointer data)
-{
-	g_hash_table_remove (shared_ips, data);
-	if (!g_hash_table_size (shared_ips))
-		nm_clear_pointer (&shared_ips, g_hash_table_unref);
-}
-
 static NMIP4Config *
 shared4_new_config (NMDevice *self, NMConnection *connection)
 {
-	NMIP4Config *config = NULL;
-	gboolean is_generated = FALSE;
+	NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE (self);
+	NMIP4Config *config;
 	NMSettingIPConfig *s_ip4;
 	NMPlatformIP4Address address = {
 		.addr_source = NM_IP_CONFIG_SOURCE_SHARED,
@@ -9673,42 +9665,24 @@ shared4_new_config (NMDevice *self, NMConnection *connection)
 	g_return_val_if_fail (connection, NULL);
 
 	s_ip4 = nm_connection_get_setting_ip4_config (connection);
-	if (s_ip4 && nm_setting_ip_config_get_num_addresses (s_ip4)) {
+	if (   s_ip4
+	    && nm_setting_ip_config_get_num_addresses (s_ip4) > 0) {
 		/* Use the first user-supplied address */
 		NMIPAddress *user = nm_setting_ip_config_get_address (s_ip4, 0);
 		in_addr_t a;
 
 		nm_ip_address_get_address_binary (user, &a);
 		nm_platform_ip4_address_set_addr (&address, a, nm_ip_address_get_prefix (user));
+		nm_clear_pointer (&priv->shared_ip_handle, nm_netns_shared_ip_release);
 	} else {
-		/* Find an unused address in the 10.42.x.x range */
-		guint32 start = (guint32) ntohl (0x0a2a0001); /* 10.42.0.1 */
-		guint32 count = 0;
-
-		if (G_UNLIKELY (!shared_ips))
-			shared_ips = g_hash_table_new (nm_direct_hash, NULL);
-		else {
-			while (g_hash_table_lookup (shared_ips, GUINT_TO_POINTER (start + count))) {
-				count += ntohl (0x100);
-				if (count > ntohl (0xFE00)) {
-					_LOGE (LOGD_SHARING, "ran out of shared IP addresses!");
-					return FALSE;
-				}
-			}
-		}
-		nm_platform_ip4_address_set_addr (&address, start + count, 24);
-		g_hash_table_add (shared_ips, GUINT_TO_POINTER (address.address));
-		is_generated = TRUE;
+		if (!priv->shared_ip_handle)
+			priv->shared_ip_handle = nm_netns_shared_ip_reserve (nm_device_get_netns (self));
+		nm_platform_ip4_address_set_addr (&address, priv->shared_ip_handle->addr, 24);
 	}
 
 	config = nm_device_ip4_config_new (self);
 	nm_ip4_config_add_address (config, &address);
-	if (is_generated) {
-		/* Remove the address lock when the object gets disposed */
-		g_object_set_qdata_full (G_OBJECT (config), NM_CACHED_QUARK ("shared-ip"),
-		                         GUINT_TO_POINTER (address.address),
-		                         shared_ip_release);
-	}
+
 	return config;
 }
 
@@ -15936,6 +15910,8 @@ _cleanup_generic_pre (NMDevice *self, CleanupType cleanup_type)
 
 	queued_state_clear (self);
 
+	nm_clear_pointer (&priv->shared_ip_handle, nm_netns_shared_ip_release);
+
 	_cleanup_ip_pre (self, AF_INET, cleanup_type);
 	_cleanup_ip_pre (self, AF_INET6, cleanup_type);
 }