[PATCH v4 2/6] IMA: conditionally allow empty rule data

[Mimi Zohar]

Hi Tushar,

On Wed, 2020-09-23 at 12:20 -0700, Tushar Sugandhi wrote:
> ima_match_rule_data() permits the func to pass empty func_data.
> For instance, for the following func, the func_data keyrings= is
> optional.
>     measure func=KEY_CHECK keyrings=.ima
> 
> But a new func in future may want to constrain the func_data to
> be non-empty.  ima_match_rule_data() should support this constraint
> and it shouldn't be hard-coded in ima_match_rule_data().
> 
> Update ima_match_rule_data() to conditionally allow empty func_data
> for the func that needs it.
> 
> Signed-off-by: Tushar Sugandhi <tusharsu at linux.microsoft.com>

Policy rules may constrain what is measured, but that decision should
be left to the system owner or admin.

Mimi