[PATCH v2] selftests/landlock: skip overlayfs test when kernel not support it

From: Jeff Xu <redacted>

Overlayfs can be disabled in kernel config, causing related tests to fail.
Add check for overlayfs’s supportability at runtime, so we can call SKIP()
when needed.

Signed-off-by: Jeff Xu <redacted>
Change-Id: Ica94d677d6c11e8f2460e07d1b432be077946324
---
 tools/testing/selftests/landlock/fs_test.c | 62 ++++++++++++++++++++--
 1 file changed, 58 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 21a2ce8fa739..3a4c52619b46 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>

@@ -62,6 +63,7 @@ static const char dir_s3d1[] = TMP_DIR "/s3d1";
 static const char dir_s3d2[] = TMP_DIR "/s3d1/s3d2";
 static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";
 
+static const char proc_filesystems[] = "/proc/filesystems";
 /*
  * layout1 hierarchy:
  *

@@ -169,6 +171,49 @@ static int remove_path(const char *const path)
 	return err;
 }
 
+static bool fgrep(FILE *inf, const char *str)
+{
+	char line[32];
+	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)
+{
+	char *res;
+	bool ret = false;
+	FILE *inf = fopen(proc_filesystems, "r");
+
+	/*
+	 * If fopen failed, return supported.
+	 * This help detect missing file (shall not
+	 * happen).
+	 */
+	if (!inf)
+		return true;
+
+	ret = fgrep(inf, "nodev\toverlay\n");
+
+	if (res) {
+		free(res);
+	}
+
+	fclose(inf);
+
+	return ret;
+}
+
+
 static void prepare_layout(struct __test_metadata *const _metadata)
 {
 	disable_caps(_metadata);

@@ -3397,13 +3442,14 @@ static const char (*merge_sub_files[])[] = {
  *     └── work
  *         └── work
  */
-
 /* clang-format off */
 FIXTURE(layout2_overlay) {};
 /* clang-format on */
 
 FIXTURE_SETUP(layout2_overlay)
 {
+	int rc;
+
 	prepare_layout(_metadata);
 
 	create_directory(_metadata, LOWER_BASE);

@@ -3431,11 +3477,19 @@ FIXTURE_SETUP(layout2_overlay)
 	create_directory(_metadata, MERGE_DATA);
 	set_cap(_metadata, CAP_SYS_ADMIN);
 	set_cap(_metadata, CAP_DAC_OVERRIDE);
-	ASSERT_EQ(0, mount("overlay", MERGE_DATA, "overlay", 0,
-			   "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
-			   ",workdir=" UPPER_WORK));
+
+	rc = mount("overlay", MERGE_DATA, "overlay", 0,
+		   "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
+		   ",workdir=" UPPER_WORK);
 	clear_cap(_metadata, CAP_DAC_OVERRIDE);
 	clear_cap(_metadata, CAP_SYS_ADMIN);
+
+	if (rc < 0) {
+		ASSERT_EQ(ENODEV, errno);
+		ASSERT_FALSE(supports_overlayfs());
+		SKIP(return, "overlayfs is not supported");
+	}
+
 }
 
 FIXTURE_TEARDOWN(layout2_overlay)

base-commit: 50cd95ac46548429e5bba7ca75cc97d11a697947
-- 
2.37.1.595.g718a3a8f04-goog

On Mon, Aug 22, 2022 at 9:25 AM [off-list ref] wrote:

From: Jeff Xu <redacted>

Overlayfs can be disabled in kernel config, causing related tests to fail.
Add check for overlayfs’s supportability at runtime, so we can call SKIP()
when needed.

Signed-off-by: Jeff Xu <redacted>
Change-Id: Ica94d677d6c11e8f2460e07d1b432be077946324

No Change-Id in upstream patches

I don't see where res is allocated or used.

No Change-Id in upstream patches

I don't see where res is allocated or used.

Thank you for catching this. Sent out V3 patch


On Mon, Aug 22, 2022 at 9:37 AM Guenter Roeck [off-list ref] wrote:

On Mon, Aug 22, 2022 at 9:25 AM [off-list ref] wrote:

quoted

From: Jeff Xu <redacted>

Overlayfs can be disabled in kernel config, causing related tests to fail.
Add check for overlayfs’s supportability at runtime, so we can call SKIP()
when needed.

Signed-off-by: Jeff Xu <redacted>
Change-Id: Ica94d677d6c11e8f2460e07d1b432be077946324

No Change-Id in upstream patches

quoted

---
 tools/testing/selftests/landlock/fs_test.c | 62 ++++++++++++++++++++--
 1 file changed, 58 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 21a2ce8fa739..3a4c52619b46 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>

@@ -62,6 +63,7 @@ static const char dir_s3d1[] = TMP_DIR "/s3d1";
 static const char dir_s3d2[] = TMP_DIR "/s3d1/s3d2";
 static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3";

+static const char proc_filesystems[] = "/proc/filesystems";
 /*
  * layout1 hierarchy:
  *

@@ -169,6 +171,49 @@ static int remove_path(const char *const path)
        return err;
 }

+static bool fgrep(FILE *inf, const char *str)
+{
+       char line[32];
+       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)
+{
+       char *res;
+       bool ret = false;
+       FILE *inf = fopen(proc_filesystems, "r");
+
+       /*
+        * If fopen failed, return supported.
+        * This help detect missing file (shall not
+        * happen).
+        */
+       if (!inf)
+               return true;
+
+       ret = fgrep(inf, "nodev\toverlay\n");
+
+       if (res) {
+               free(res);
+       }

I don't see where res is allocated or used.

quoted

+
+       fclose(inf);
+
+       return ret;
+}
+
+
 static void prepare_layout(struct __test_metadata *const _metadata)
 {
        disable_caps(_metadata);

@@ -3397,13 +3442,14 @@ static const char (*merge_sub_files[])[] = {
  *     └── work
  *         └── work
  */
-
 /* clang-format off */
 FIXTURE(layout2_overlay) {};
 /* clang-format on */

 FIXTURE_SETUP(layout2_overlay)
 {
+       int rc;
+
        prepare_layout(_metadata);

        create_directory(_metadata, LOWER_BASE);

@@ -3431,11 +3477,19 @@ FIXTURE_SETUP(layout2_overlay)
        create_directory(_metadata, MERGE_DATA);
        set_cap(_metadata, CAP_SYS_ADMIN);
        set_cap(_metadata, CAP_DAC_OVERRIDE);
-       ASSERT_EQ(0, mount("overlay", MERGE_DATA, "overlay", 0,
-                          "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
-                          ",workdir=" UPPER_WORK));
+
+       rc = mount("overlay", MERGE_DATA, "overlay", 0,
+                  "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
+                  ",workdir=" UPPER_WORK);
        clear_cap(_metadata, CAP_DAC_OVERRIDE);
        clear_cap(_metadata, CAP_SYS_ADMIN);
+
+       if (rc < 0) {
+               ASSERT_EQ(ENODEV, errno);
+               ASSERT_FALSE(supports_overlayfs());
+               SKIP(return, "overlayfs is not supported");
+       }
+
 }

 FIXTURE_TEARDOWN(layout2_overlay)

base-commit: 50cd95ac46548429e5bba7ca75cc97d11a697947
--
2.37.1.595.g718a3a8f04-goog