On 10/02/2018 09:54 AM, Kees Cook wrote:

On Tue, Oct 2, 2018 at 9:33 AM, Jordan Glover
[off-list ref] wrote:

quoted

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.