[PATCH v7 1/1] selftests/landlock: skip overlayfs test when kernel not support it

[Mickaël Salaün]

Please refresh with clang-format-14.

You might want to update the subject to:
selftests/landlock: Skip overlayfs tests when not supported


On 29/12/2022 22:41, Guenter Roeck wrote:
> On Thu, Dec 29, 2022 at 1:02 PM <jeffxu at chromium.org> wrote:
>>
>> From: Jeff Xu <jeffxu at google.com>
>>
>> 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 <jeffxu at google.com>
> 
> Reviewed-by: Guenter Roeck <groeck at chromium.org>
> 
>> ---
>>   tools/testing/selftests/landlock/fs_test.c | 51 ++++++++++++++++++++++
>>   1 file changed, 51 insertions(+)
>>
>> diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
>> index 21a2ce8fa739..34095fe2419b 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";

You can inline this string in the fopen() call for now.


>>   /*
>>    * layout1 hierarchy:
>>    *
>> @@ -169,6 +171,43 @@ 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)

You can move this two functions just before mkdir_parents().


>> +{
>> +       bool res;
>> +       FILE *inf = fopen(proc_filesystems, "r");
>> +
>> +       /*
>> +        * If fopen failed, return supported.
>> +        * This help detect missing file (shall not
>> +        * happen).

You can make this comment fit in two lines, with 80 columns.

>> +        */
>> +       if (!inf)
>> +               return true;
>> +
>> +       res = fgrep(inf, "nodev\toverlay\n");
>> +       fclose(inf);
>> +
>> +       return res;
>> +}
>> +
>> +
>>   static void prepare_layout(struct __test_metadata *const _metadata)
>>   {
>>          disable_caps(_metadata);
>> @@ -3404,6 +3443,9 @@ FIXTURE(layout2_overlay) {};
>>
>>   FIXTURE_SETUP(layout2_overlay)
>>   {
>> +       if (!supports_overlayfs())
>> +               SKIP(return, "overlayfs is not supported");
>> +
>>          prepare_layout(_metadata);
>>
>>          create_directory(_metadata, LOWER_BASE);
>> @@ -3440,6 +3482,9 @@ FIXTURE_SETUP(layout2_overlay)
>>
>>   FIXTURE_TEARDOWN(layout2_overlay)
>>   {
>> +       if (!supports_overlayfs())
>> +               SKIP(return, "overlayfs is not supported");

This looks good to me except the multiple supports_overlayfs() calls. 
Only the FIXTURE_SETUP() should be required. I guess some modifications 
of kselftest_harness.h are need to support that. I'd like to avoid 
touching TEST_F_FORK() which should be part of kselftest_harness.h


>> +
>>          EXPECT_EQ(0, remove_path(lower_do1_fl3));
>>          EXPECT_EQ(0, remove_path(lower_dl1_fl2));
>>          EXPECT_EQ(0, remove_path(lower_fl1));
>> @@ -3471,6 +3516,9 @@ 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));
>> @@ -3634,6 +3682,9 @@ 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);
>> --
>> 2.39.0.314.g84b9a713c41-goog
>>