[PATCH] LSM: Ignore "security=" when "lsm=" is specified

[Tetsuo Handa]

Kees Cook wrote:
> On Mon, Feb 11, 2019 at 4:21 PM Tetsuo Handa
> <penguin-kernel at i-love.sakura.ne.jp> wrote:
> >
> > Kees Cook wrote:
> > > To avoid potential confusion, explicitly ignore "security=" when "lsm=" is
> > > used on the command line, and report that it is happening.
> >
> > To maintain the existing behavior of CONFIG_DEFAULT_SECURITY, I also suggest this change.
> > This saves e.g. Ubuntu users who are using only AppArmor from explicitly specifying
> > security=apparmor when they don't want to enable other LSM_FLAG_LEGACY_MAJOR modules.
> 
> No, this completely disables the purpose of lsm=
> 
> I don't understand the use-case you're concerned about?

The purpose of lsm= remains.

I worry that distro users who don't explicitly specify security= parameter
suddenly find TOMOYO messages because TOMOYO is no longer exclusive.
There are two ways for avoiding it. One is to explicitly specify security=
parameter. The other is to remove tomoyo from CONFIG_LSM. This change adds
the third way; preserve current security= behavior until they start explicitly
specifying lsm= parameter.