[PATCH 06/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond

[Mimi Zohar]

On Mon, 2020-06-22 at 19:32 -0500, Tyler Hicks wrote:
> The KEXEC_CMDLINE hook function only supports the pcr conditional. Make
> this clear at policy load so that IMA policy authors don't assume that
> other conditionals are supported.
> 
> Since KEXEC_CMDLINE's inception, ima_match_rules() has always returned
> true on any loaded KEXEC_CMDLINE rule without any consideration for
> other conditionals present in the rule. Make it clear that pcr is the
> only supported KEXEC_CMDLINE conditional by returning an error during
> policy load.
> 
> An example of why this is a problem can be explained with the following
> rule:
> 
>  dont_measure func=KEXEC_CMDLINE obj_type=foo_t
> 
> An IMA policy author would have assumed that rule is valid because the
> parser accepted it but the result was that measurements for all
> KEXEC_CMDLINE operations would be disabled.
> 
> Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments")
> Signed-off-by: Tyler Hicks <tyhicks at linux.microsoft.com>

Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>