On 10/01/2018 03:29 PM, Kees Cook wrote:
> On Mon, Oct 1, 2018 at 3:20 PM, John Johansen
> <john.johansen@xxxxxxxxxxxxx> wrote:
>> On 10/01/2018 02:56 PM, Kees Cook wrote:
>>> On Mon, Oct 1, 2018 at 2:47 PM, James Morris <jmorris@xxxxxxxxx> 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@xxxxxxxxxxxx>
>>>>> ---
>>>>> 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...
>>>
>> fwiw the apparmor.enabled config is really only a meant to be used to
>> disable apparmor. I'd drop it entirely except its part of the userspace
>> api now and needs to show up in
>>
>> /sys/module/apparmor/parameters/enabled
>
> Showing the enabled-ness there can be wired up. What should happen if
> someone sets apparmor.enabled=0/1 in new-series-world? (See other
> thread...)
>
I am open to either just making apparmor=0/apparmor.enabled=0 a means
of only disabling apparmor, thats how it is currently used. Or even
potentially getting rid of it as an available kernel boot config
parameter and running with just lsm.enabled/disabled.
The important bit that applications are relying on is having
/sys/module/apparmor/parameters/enabled
set to the the correct value.
