platform: add nmp_netns_bind_to_path() helper function

Based-on-patch-by: Stjepan Gros <stjepan.gros@gmail.com>

src/platform/nmp-netns.c

@@ -24,6 +24,8 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #include "NetworkManagerUtils.h"
 
@@ -579,6 +581,84 @@ nmp_netns_is_initial (void)
 
 /*********************************************************************************************/
 
+gboolean
+nmp_netns_bind_to_path (NMPNetns *self, const char *filename, int *out_fd)
+{
+	gs_free char *dirname = NULL;
+	int errsv;
+	int fd;
+	nm_auto_pop_netns NMPNetns *netns_pop = NULL;
+
+	g_return_val_if_fail (NMP_IS_NETNS (self), FALSE);
+	g_return_val_if_fail (filename && filename[0] == '/', FALSE);
+
+	if (!nmp_netns_push_type (self, CLONE_NEWNET))
+		return FALSE;
+	netns_pop = self;
+
+	dirname = g_path_get_dirname (filename);
+	if (mkdir (dirname, 0) != 0) {
+		errsv = errno;
+		if (errsv != EEXIST) {
+			_LOGE (self, "bind: failed to create directory %s: %s",
+			       dirname, g_strerror (errsv));
+			return FALSE;
+		}
+	}
+
+	if ((fd = creat (filename, S_IRUSR | S_IRGRP | S_IROTH)) == -1) {
+		errsv = errno;
+		_LOGE (self, "bind: failed to create %s: %s",
+		       filename, g_strerror (errsv));
+		return FALSE;
+	}
+	close (fd);
+
+	if (mount (PROC_SELF_NS_NET, filename, "none", MS_BIND, NULL) != 0) {
+		errsv = errno;
+		_LOGE (self, "bind: failed to mount %s to %s: %s",
+		       PROC_SELF_NS_NET, filename, g_strerror (errsv));
+		unlink (filename);
+		return FALSE;
+	}
+
+	if (out_fd) {
+		if ((fd = open (filename, O_RDONLY)) == -1) {
+			errsv = errno;
+			_LOGE (self, "bind: failed to open %s: %s", filename, g_strerror (errsv));
+			umount2 (filename, MNT_DETACH);
+			unlink (filename);
+			return FALSE;
+		}
+		*out_fd = fd;
+	}
+
+	return TRUE;
+}
+
+gboolean
+nmp_netns_bind_to_path_destroy (NMPNetns *self, const char *filename)
+{
+	int errsv;
+
+	g_return_val_if_fail (NMP_IS_NETNS (self), FALSE);
+	g_return_val_if_fail (filename && filename[0] == '/', FALSE);
+
+	if (umount2 (filename, MNT_DETACH) != 0) {
+		errsv = errno;
+		_LOGE (self, "bind: failed to unmount2 %s: %s", filename, g_strerror (errsv));
+		return FALSE;
+	}
+	if (unlink (filename) != 0) {
+		errsv = errno;
+		_LOGE (self, "bind: failed to unlink %s: %s", filename, g_strerror (errsv));
+		return FALSE;
+	}
+	return TRUE;
+}
+
+/******************************************************************************/
+
 static void
 set_property (GObject *object, guint prop_id,
               const GValue *value, GParamSpec *pspec)

src/platform/nmp-netns.h

@@ -68,4 +68,7 @@ _nm_auto_pop_netns (NMPNetns **p)
 
 #define nm_auto_pop_netns __attribute__((cleanup(_nm_auto_pop_netns)))
 
+gboolean nmp_netns_bind_to_path (NMPNetns *self, const char *filename, int *out_fd);
+gboolean nmp_netns_bind_to_path_destroy (NMPNetns *self, const char *filename);
+
 #endif /* __NMP_NETNS_UTILS_H__ */

src/platform/tests/test-link.c

@@ -21,6 +21,9 @@
 #include "nm-default.h"
 
 #include <sched.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #include "nmp-object.h"
 #include "nmp-netns.h"
@@ -2236,6 +2239,59 @@ test_netns_push (gpointer fixture, gconstpointer test_data)
 
 /*****************************************************************************/
 
+static void
+test_netns_bind_to_path (gpointer fixture, gconstpointer test_data)
+{
+#define P_VAR_RUN                "/var/run"
+#define P_VAR_RUN_NETNS          "/var/run/netns"
+#define P_VAR_RUN_NETNS_BINDNAME "/var/run/netns/"P_NETNS_BINDNAME
+#define P_NETNS_BINDNAME         "nmtst-iproute2-netns"
+	gs_unref_object NMPlatform *platform_0 = NULL;
+	gs_unref_object NMPlatform *platform_1 = NULL;
+	gs_unref_object NMPlatform *platform_2 = NULL;
+	nm_auto_pop_netns NMPNetns *netns_pop = NULL;
+	NMPlatform *platforms[3];
+	NMPNetns *netns;
+	int i;
+
+	if (_test_netns_check_skip ())
+		return;
+
+	g_assert_cmpint (mount ("tmpfs", P_VAR_RUN, "tmpfs", MS_NOATIME | MS_NODEV | MS_NOSUID, "mode=0755,size=32K"), ==, 0);
+	g_assert_cmpint (mkdir (P_VAR_RUN_NETNS, 755), ==, 0);
+
+	platforms[0] = platform_0 = g_object_new (NM_TYPE_LINUX_PLATFORM, NM_PLATFORM_NETNS_SUPPORT, TRUE, NULL);
+	platforms[1] = platform_1 = _test_netns_create_platform ();
+	platforms[2] = platform_2 = _test_netns_create_platform ();
+
+	i = nmtst_get_rand_int () % 4;
+	if (i != 3)
+		g_assert (nm_platform_netns_push (platforms[i], &netns_pop));
+
+	i = (nmtst_get_rand_int () % 2) + 1;
+	netns = nm_platform_netns_get (platforms[i]);
+
+	_ADD_DUMMY (platforms[i], "dummy2b");
+
+	g_assert (!g_file_test (P_VAR_RUN_NETNS_BINDNAME, G_FILE_TEST_EXISTS));
+	g_assert_cmpint (nmtstp_run_command ("ip netns exec "P_NETNS_BINDNAME" true 2>/dev/null"), !=, 0);
+
+	g_assert (nmp_netns_bind_to_path (netns, P_VAR_RUN_NETNS_BINDNAME, NULL));
+
+	g_assert (g_file_test (P_VAR_RUN_NETNS_BINDNAME, G_FILE_TEST_EXISTS));
+	g_assert_cmpint (nmtstp_run_command ("ip netns exec "P_NETNS_BINDNAME" true"), ==, 0);
+	g_assert_cmpint (nmtstp_run_command ("ip netns exec "P_NETNS_BINDNAME" ip link show dummy2b 1>/dev/null"), ==, 0);
+
+	g_assert (nmp_netns_bind_to_path_destroy (netns, P_VAR_RUN_NETNS_BINDNAME));
+
+	g_assert (!g_file_test (P_VAR_RUN_NETNS_BINDNAME, G_FILE_TEST_EXISTS));
+	g_assert_cmpint (nmtstp_run_command ("ip netns exec "P_NETNS_BINDNAME" true 2>/dev/null"), !=, 0);
+
+	g_assert_cmpint (umount (P_VAR_RUN), ==, 0);
+}
+
+/*****************************************************************************/
+
 void
 init_tests (int *argc, char ***argv)
 {
@@ -2286,5 +2342,6 @@ setup_tests (void)
 		g_test_add_vtable ("/general/netns/general", 0, NULL, _test_netns_setup, test_netns_general, _test_netns_teardown);
 		g_test_add_vtable ("/general/netns/set-netns", 0, NULL, _test_netns_setup, test_netns_set_netns, _test_netns_teardown);
 		g_test_add_vtable ("/general/netns/push", 0, NULL, _test_netns_setup, test_netns_push, _test_netns_teardown);
+		g_test_add_vtable ("/general/netns/bind-to-path", 0, NULL, _test_netns_setup, test_netns_bind_to_path, _test_netns_teardown);
 	}
 }