[PATCH v5] selftests/landlock: Skip overlayfs tests not supported

[Jeff Xu]

On Thu, Aug 25, 2022 at 1:23 AM Mickaël Salaün <mic at digikod.net> wrote:
>
> As discussed for the v4, the next version of this patch needs a
> TEST_F_FORK() fix.
>
I can make TEST_F_FORK() to be skipped when SKIP() is called
in FIXTURE_SETUP(), but this makes FIXTURE_TEARDOWN()
complicated, because SKIP() can be called after any resource
creation failure in the FIXTURE_SETUP().

Another (better) option:  add generic FIXTURE_CONFIG_CHECK()
FIXTURE_CONFIG_CHECK() checks the runtime configuration for
current FIXTURE, if the configuration is not met, the whole test will be
skipped, including FIXTURE_SETUP()/TEARDOWN(), TEST_F_FORK(),
so there is no resource clear up issue after test.

> Please add a link to the previous patch (lore.kernel.org) for each new
> version.
>
>
> On 24/08/2022 03:58, jeffxu at chromium.org wrote:
> > From: Jeff Xu <jeffxu at chromium.org>
> >
> > overlayfs can be disabled in the kernel configuration (which is the case
> > for chromeOS), causing related tests to fail.  Skip such tests when an
> > overlayfs mount operation failed because the running kernel doesn't
> > support this file system.
> >
> > Signed-off-by: Jeff Xu <jeffxu at chromium.org>
> > Reviewed-by: Guenter Roeck <groeck at chromium.org>
> > ---
> >   tools/testing/selftests/landlock/fs_test.c | 54 ++++++++++++++++++++--
> >   1 file changed, 51 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
> > index 21a2ce8fa739..645304d9fe98 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>
> > @@ -169,6 +170,42 @@ static int remove_path(const char *const path)
> >       return err;
> >   }
> >
> > +static bool fgrep(FILE *file, const char *str)
> > +{
> > +     char line[32];
> > +     int str_len = strlen(str);
> > +
> > +     while (!feof(file)) {
> > +             if (!fgets(line, sizeof(line), file))
> > +                     break;
> > +             if (strncmp(line, str, str_len))
> > +                     continue;
> > +
> > +             return true;
> > +     }
> > +
> > +     return false;
> > +}
> > +
> > +static bool supports_overlayfs(void)
> > +{
> > +     bool ret;
> > +     FILE *file = fopen("/proc/filesystems", "r");
> > +
> > +     /*
> > +      * A failed attempt to open /proc/filesystems
> > +      * implies that the file system is supported (default
> > +      * behavior). This can help detect such unattended issue
> > +      * (which should not happen)."
> > +      */
> > +     if (!file)
> > +             return true;
> > +
> > +     ret = fgrep(file, "nodev\toverlay\n");
> > +     fclose(file);
> > +     return ret;
> > +}
> > +
> >   static void prepare_layout(struct __test_metadata *const _metadata)
> >   {
> >       disable_caps(_metadata);
> > @@ -3404,6 +3441,8 @@ FIXTURE(layout2_overlay) {};
> >
> >   FIXTURE_SETUP(layout2_overlay)
> >   {
> > +     int ret, err;
> > +
> >       prepare_layout(_metadata);
> >
> >       create_directory(_metadata, LOWER_BASE);
> > @@ -3431,11 +3470,20 @@ 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));
> > +
> > +     ret = mount("overlay", MERGE_DATA, "overlay", 0,
> > +                "lowerdir=" LOWER_DATA ",upperdir=" UPPER_DATA
> > +                ",workdir=" UPPER_WORK);
> > +     err = errno;
> >       clear_cap(_metadata, CAP_DAC_OVERRIDE);
> >       clear_cap(_metadata, CAP_SYS_ADMIN);
> > +
> > +     if (ret == -1) {
> > +             ASSERT_EQ(ENODEV, err);
> > +             ASSERT_FALSE(supports_overlayfs());
> > +             SKIP(return, "overlayfs is not supported");
> > +     }
> > +     ASSERT_EQ(0, ret);
> >   }
> >
> >   FIXTURE_TEARDOWN(layout2_overlay)
> >
> > base-commit: 50cd95ac46548429e5bba7ca75cc97d11a697947