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

[Jeff Xu]

> 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 <groeck at google.com> wrote:
>
> On Mon, Aug 22, 2022 at 9:25 AM <jeffxu at google.com> 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 chromium.org>
> > Change-Id: Ica94d677d6c11e8f2460e07d1b432be077946324
>
> No Change-Id in upstream patches
>
> > ---
> >  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.
>
> > +
> > +       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
> >