On Tue, Oct 2, 2018 at 11:33 AM, Stephen Smalley [off-list ref] wrote:

On 10/02/2018 12:54 PM, Kees Cook wrote:

quoted

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
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.

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?

Let's say a user/packager/distro has been building kernels for the past 14
years (*) with a config that has SECURITY_SELINUX_BOOTPARAM_VALUE=0, and now
they build a new kernel that includes these patches using that same config.
Won't SELinux be enabled by default because SECURITY_SELINUX_BOOTPARAM_VALUE
is now ignored and LSM_ENABLE defaults to all?  Is it ok to require them to
specify a new config option to preserve old behavior?

Yes, I think that's fine -- kernel CONFIGs change all the time. System
builders are used to examining these changes.

-Kees

-- 
Kees Cook
Pixel Security