Patch "selftests/landlock: Skip overlayfs tests when not supported" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/landlock: Skip overlayfs tests when not supported

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-landlock-skip-overlayfs-tests-when-not-sup.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 54bbaa4518388e88b866567125ccc67d87b9a423
Author: Jeff Xu <jeffxu@xxxxxxxxxx>
Date:   Fri Jan 13 05:32:29 2023 +0000

    selftests/landlock: Skip overlayfs tests when not supported
    
    [ Upstream commit 366617a69e60610912836570546f118006ebc7cb ]
    
    overlayfs may be disabled in the kernel configuration, causing related
    tests to fail.  Check that overlayfs is supported at runtime, so we can
    skip layout2_overlay.* accordingly.
    
    Signed-off-by: Jeff Xu <jeffxu@xxxxxxxxxx>
    Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
    Cc: stable@xxxxxxxxxxxxxxx
    Link: https://lore.kernel.org/r/20230113053229.1281774-2-jeffxu@xxxxxxxxxx
    [mic: Reword comments and constify variables]
    Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 10c9a1e4ebd9b..db153452b110a 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -11,6 +11,7 @@
 #include <fcntl.h>
 #include <linux/landlock.h>
 #include <sched.h>
+#include <stdio.h>
 #include <string.h>
 #include <sys/capability.h>
 #include <sys/mount.h>
@@ -74,6 +75,40 @@ static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";
  *         └── s3d3
  */
 
+static bool fgrep(FILE *const inf, const char *const str)
+{
+	char line[32];
+	const int slen = strlen(str);
+
+	while (!feof(inf)) {
+		if (!fgets(line, sizeof(line), inf))
+			break;
+		if (strncmp(line, str, slen))
+			continue;
+
+		return true;
+	}
+
+	return false;
+}
+
+static bool supports_overlayfs(void)
+{
+	bool res;
+	FILE *const inf = fopen("/proc/filesystems", "r");
+
+	/*
+	 * Consider that the filesystem is supported if we cannot get the
+	 * supported ones.
+	 */
+	if (!inf)
+		return true;
+
+	res = fgrep(inf, "nodev\toverlay\n");
+	fclose(inf);
+	return res;
+}
+
 static void mkdir_parents(struct __test_metadata *const _metadata,
 		const char *const path)
 {
@@ -2416,6 +2451,9 @@ FIXTURE(layout2_overlay) {
 
 FIXTURE_SETUP(layout2_overlay)
 {
+	if (!supports_overlayfs())
+		SKIP(return, "overlayfs is not supported");
+
 	prepare_layout(_metadata);
 
 	create_directory(_metadata, LOWER_BASE);
@@ -2453,6 +2491,9 @@ FIXTURE_SETUP(layout2_overlay)
 
 FIXTURE_TEARDOWN(layout2_overlay)
 {
+	if (!supports_overlayfs())
+		SKIP(return, "overlayfs is not supported");
+
 	EXPECT_EQ(0, remove_path(lower_do1_fl3));
 	EXPECT_EQ(0, remove_path(lower_dl1_fl2));
 	EXPECT_EQ(0, remove_path(lower_fl1));
@@ -2484,6 +2525,9 @@ FIXTURE_TEARDOWN(layout2_overlay)
 
 TEST_F_FORK(layout2_overlay, no_restriction)
 {
+	if (!supports_overlayfs())
+		SKIP(return, "overlayfs is not supported");
+
 	ASSERT_EQ(0, test_open(lower_fl1, O_RDONLY));
 	ASSERT_EQ(0, test_open(lower_dl1, O_RDONLY));
 	ASSERT_EQ(0, test_open(lower_dl1_fl2, O_RDONLY));
@@ -2647,6 +2691,9 @@ TEST_F_FORK(layout2_overlay, same_content_different_file)
 	size_t i;
 	const char *path_entry;
 
+	if (!supports_overlayfs())
+		SKIP(return, "overlayfs is not supported");
+
 	/* Sets rules on base directories (i.e. outside overlay scope). */
 	ruleset_fd = create_ruleset(_metadata, ACCESS_RW, layer1_base);
 	ASSERT_LE(0, ruleset_fd);