Re: Linux Firmware Signing

[Mimi Zohar <zohar@linux.vnet.ibm.com>]

On Wed, 2015-09-02 at 02:09 +0200, Luis R. Rodriguez wrote:
> On Tue, Sep 01, 2015 at 01:20:37PM -0700, Kees Cook wrote:
> > On Thu, Aug 27, 2015 at 2:29 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> > As long as the LSM know what kind of file it's loading, and has access
> > to the fd (and for IMA, the blob loaded from that fd), that should be
> > everything it needs. IMA has the name and blob, loadpin has the fd,
> > and a future signature-checking LSM could be able to look up signature
> > type from the load type, and split the key off (or fetch the key file)
> > itself.

I assume "and for IMA, the blob loaded from that fd"  is referring to
the file signature stored in the xattr.

> OK great, I think that instead of passing the actual routine name we should
> instead pass an enum type for to the LSM, that'd be easier to parse and we'd
> then have each case well documented. Each LSM then could add its own
> documetnation for this and can switch on it. If we went with a name we'd have
> to to use something like __func__ and then parse that, its not clear if we need
> to get that specific.

Agreed.  IMA already defines an enumeration.

/* IMA policy related functions */
enum ima_hooks { FILE_CHECK = 1, MMAP_CHECK, BPRM_CHECK, MODULE_CHECK,
                 FIRMWARE_CHECK, POLICY_CHECK, POST_SETATTR };

Mimi