[LTP] [PATCH 2/3] ima_setup.sh: Allow to load predefined policy

[Mimi Zohar]

On Wed, 2024-12-11 at 20:48 +0100, Petr Vorel wrote:
> Hi Mimi, all,
> 
> > On Tue, 2024-11-26 at 18:38 +0100, Petr Vorel wrote:
> > > environment variable LTP_IMA_LOAD_POLICY=1 tries to load example policy
> > > if available. This should be used only if tooling running LTP tests
> > > allows to reboot afterwards (because policy may be writable only once,
> > > e.g. missing CONFIG_IMA_WRITE_POLICY=y, or policies can influence each
> > > other).
> 
> > Thanks, Petr.  Allowing the policy to be updated only if permitted is a good
> > idea.  Even with the LTP_IMA_LOAD_POLICY=1 environment variable, the policy
> > might not be loaded.  For example, when secure boot is enabled and the kernel is
> > configured with CONFIG_IMA_ARCH_POLICY enabled, an "appraise func=POLICY_CHECK
> > appraise_type=imasig" rule is loaded, requiring the IMA policy itself to be
> > signed.
> 
> Yes, it's an attempt, which can fail for various reasons. I'll add this example
> of failure to load the policy to the commit message and to the docs.
> 
> I'd like to detect if policy got updated to avoid wasting time with SUT reboot
> when policy was not updated. But this probably will not be always possible
> (e.g. (CONFIG_IMA_READ_POLICY not set).

Why do you actually need to be able to read the policy, after updating it?
Either the policy update succeeded or failed.  For example in the signed policy
case, writing a valid policy rule via 'cat' on a system requiring the policy to
be signed always fails.

> 
> > On failure to load a policy, the ima_conditionals.sh and ima_policy.sh tests say
> > "TINFO: SELinux enabled in enforcing mode, this may affect test results".  We
> > should stop blaming SELinux. :)
> 
> This info was added for LTP shell tests, which got often affected by
> SELinux/Apparmor. Because IMA is written in LTP shell API it gets this.
> Error message is printed on TBROK, TFAIL, TWARN. Is this the only part where you
> would like to avoid the message? Or do you want to remove SELinux/Apparmor
> warning from all IMA tests?

You have a better feel than me as to whether SELinux/Apparmor could interfere
with these tests.  Unless we have some reason to blame SELinux/Apparmor, I would
remove it.

Mimi