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    SubjectRe: [PATCH security-next v3 14/29] LSM: Plumb visibility into optional "enabled" state
    On Mon, Oct 1, 2018 at 2:47 PM, James Morris <jmorris@namei.org> wrote:
    > On Mon, 24 Sep 2018, Kees Cook wrote:
    >
    >> In preparation for lifting the "is this LSM enabled?" logic out of the
    >> individual LSMs, pass in any special enabled state tracking (as needed
    >> for SELinux, AppArmor, and LoadPin). This should be an "int" to include
    >> handling any future cases where "enabled" is exposed via sysctl which
    >> has no "bool" type.
    >>
    >> Signed-off-by: Kees Cook <keescook@chromium.org>
    >> ---
    >> include/linux/lsm_hooks.h | 1 +
    >> security/apparmor/lsm.c | 5 +++--
    >> security/selinux/hooks.c | 1 +
    >> 3 files changed, 5 insertions(+), 2 deletions(-)
    >>
    >> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
    >> index 5056f7374b3d..2a41e8e6f6e5 100644
    >> --- a/include/linux/lsm_hooks.h
    >> +++ b/include/linux/lsm_hooks.h
    >> @@ -2044,6 +2044,7 @@ extern void security_add_hooks(struct security_hook_list *hooks, int count,
    >> struct lsm_info {
    >> const char *name; /* Populated automatically. */
    >> unsigned long flags; /* Optional: flags describing LSM */
    >> + int *enabled; /* Optional: NULL means enabled. */
    >
    > This seems potentially confusing.
    >
    > Perhaps initialize 'enabled' to a default int pointer, like:
    >
    > static int lsm_default_enabled = 1;
    >
    > Then,
    >
    > DEFINE_LSM(foobar)
    > flags = LSM_FLAG_LEGACY_MAJOR,
    > .enabled = &lsm_default_enabled,
    > .init = foobar_init,
    > END_LSM;

    The reason I didn't do this is because there are only two LSMs that
    expose this "enabled" variable, so I didn't like making the other LSMs
    have to declare this. Internally, though, this is exactly what the
    infrastructure does: if it finds a NULL, it aims it at
    &lsm_default_enabled (in a later patch).

    However, it seems more discussion is needed on the "enable" bit of
    this, so I'll reply to John in a moment...

    -Kees

    --
    Kees Cook
    Pixel Security

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