On 10/02/2018 09:54 AM, Kees Cook wrote:
> On Tue, Oct 2, 2018 at 9:33 AM, Jordan Glover
> <Golden_Miller83@xxxxxxxxxxxxx> wrote:
>> It's always documented as: "selinux=1 security=selinux" so security= should
>> still do the job and selinux=1 become no-op, no?
>
> The v3 patch set worked this way, yes. (The per-LSM enable defaults
> were set by the LSM. Only in the case of "lsm.disable=selinux" would
> the above stop working.)
>
> John did not like the separation of having two CONFIG and two
still don't
> bootparams mixing the controls. The v3 resolution rules were:
>
> SECURITY_SELINUX_BOOTPARAM_VALUE overrides CONFIG_LSM_ENABLE.
> SECURITY_APPARMOR_BOOTPARAM_VALUE overrides CONFIG_LSM_ENABLE.
> selinux= overrides SECURITY_SELINUX_BOOTPARAM_VALUE.
> apparmor.enabled= overrides SECURITY_APPARMOR_BOOTPARAM_VALUE.
> apparmor= overrides apparmor.enabled=.
> lsm.enable= overrides selinux=.
> lsm.enable= overrides apparmor=.
> lsm.disable= overrides lsm.enable=.
> major LSM _omission_ from security= (if present) overrides lsm.enable.
>
Yeah I would really like to remove the potential confusion for the
user. The user now has 4 kernel options to play with, and get confused
by
LSM= (I'll count apparmor.enabled= here as well)
security=
lsm.enabled=
lsm.disabled=
I really don't like this, it will be very confusing for users. I also
think an authoritative list of what is enabled is easier for users
than mixing a list of whats enabled with kernel config default
settings.
Under the current scheme
lsm.enabled=selinux
could actually mean selinux,yama,loadpin,something_else are
enabled. If we extend this behavior to when full stacking lands
lsm.enabled=selinux,yama
might mean selinux,yama,apparmor,loadpin,something_else
and what that list is will vary from kernel to kernel, which I think
is harder for the user than the lsm.enabled list being what is
actually enabled at boot
If we have to have multiple kernel parameter, I prefer a behvior where
if you hav conflicting kernel parameters specified
apparmor=0 lsm.enabled=apparmor
that the conflict is logged and the lsm is left disabled, as I think
it is easier for users to understand than the overrides scheme of v3,
and sans logging of the conflict is effectively what we had in the
past
apparmor=0 security=apparmor
or
apparmor=1 security=selinux
would result in apparmor being disabed
That being said I get we have a mess currently, and there really
doesn't seem to be a good way to fix it. I think getting this right
for the user is important enough that I am willing to break current
apparmor userspace api. While apparmor=0 is documented we have also
documented security=X for years and apparmor=0 isn't used too often
so I think we can drop it to help clean this mess up abit.
I am not going to Nak, or block on v3 behavior if that is considered
the best path forward after this discussion/rant.
> v4 removed the per-LSM boot params and CONFIGs at John's request, but
> Paul and Stephen don't want this for SELinux.
>
> The pieces for reducing conflict with CONFIG_LSM_ENABLE and
> lsm.{enable,disable}= were:
>
> 1- Remove SECURITY_APPARMOR_BOOTPARAM_VALUE.
> 2- Remove apparmor= and apparmor.enabled=.
> 3- Remove SECURITY_SELINUX_BOOTPARAM_VALUE.
> 4- Remove selinux=.
>
> v4 used all of 1-4 above. SELinux says "4" cannot happen as it's too
> commonly used. Would 3 be okay for SELinux?
>
> John, with 4 not happening, do you prefer to not have 2 happen?
>
> With CONFIGs removed, then the boot time defaults are controlled by
> CONFIG_LSM_ENABLE, but the boot params continue to work as before.
> Only the use of the new lsm.enable= and lsm.disable= would override
> the per-LSM boot params. This would clean up the build-time CONFIG
> weirdness, and leave the existing boot params as before (putting us
> functionally in between the v3 and v4 series).
>
I'm ambivalent. I really want to clean this up but atm it doesn't
really look like 2 is going to provide much of a benefit. If you
think it helps clean this up, do it. Regardless 1 is going to
happen, and I will start updating documentation and try to get
users moving away from using the apparmor= kernel parameter.
