Re: [PATCH v3 2/2] ima: move APPRAISE_BOOTPARAM dependency on ARCH_POLICY to runtime

[Mimi Zohar]

On Mon, 2020-06-29 at 20:47 -0300, Bruno Meneguele wrote:

> 
> > I'm not if the "secure_boot" flag is available prior to calling
> > default_appraise_setup(), but if it is, you could modify the test
> > there to also check if the system is booted in secure boot mode (eg.
> > IS_ENABLED(CONFIG_IMA_APPRAISE_BOOTPARAM) &&
> > !arch_ima_get_secureboot())
> > 
> 
> Well pointed. I built a custom x86 kernel with some workaround to get
> this flag status within default_appraise_setup() and as a result the
> flag is was correctly available. 
> 
> Considering the nature of this flag (platform's firmware (in all
> arches?)) can we trust that every arch supporting secure/trusted boot
> will have it available in the __setup() call time?

CallingÂdefault_appraise_setup() could be deferred.

> 
> > > +		/* In secure and/or trusted boot the appraisal must be
> > > +		 * enforced, regardless kernel parameters, preventing
> > > +		 * runtime changes */
> > 
> > Only "appraise" rules are enforced.
> > 
> 
> Hmm.. do you mean the comment wording is wrong/"could be better",
> pointing the "appraise" action explicitly?

No, it's more than just the comment. ÂLike "trusted boot", IMA-
measurement only measures files, never enforces integrity.
Â"ima_appraise" mode is only applicable to IMA-appraisal.

Mimi