On Fri, 2018-01-05 at 13:15 -0800, Matthew Garrett wrote:

The existing BPRM_CHECK functionality in IMA validates against the
credentials of the existing process, not any new credentials that the
child process may transition to. Add an additional CREDS_CHECK target
and refactor IMA to pass the appropriate creds structure. In
ima_bprm_check(), check with both the existing process credentials and
the credentials that will be committed when the new process is started.
This will not change behaviour unless the system policy is extended to
include CREDS_CHECK targets - BPRM_CHECK will continue to check the same
credentials that it did previously.

Refactoring IMA to pass the creds structure all the way down is a
generic solution, but if the CREDS_CHECK rule is only being called
from ima_bprm_check(), "container_of" the bprm->file returns a pointer
to the bprm structure. ?Perhaps you could limit the amount of
refactoring needed based on the func.

I would prefer new arguments be added to process_measurement() only as
a last resort.

Could you include in the patch description a simple method for testing
this change?

thanks,

Mimi

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