RESEND: security: keys: Making key_type_lookup() public

RESEND: security: keys: Making key_type_lookup() public

[Douglas Miller]

I'd like to explore the possibility of making key_type_lookup() 
available to other kernel components, the same way that 
[un]register_key_type() is available. I'm wondering if there is a reason 
that this function shouldn't be available for use.


The reason we would like to use this function is for support of SED-OPAL 
drives using block/sed-opal.c. On certain PowerPC platforms there is a 
Platform Key Store (PKS) available and we want to use that as a
repository for SED-OPAL PEKs.


Rather than add platform-specific code to block/sed-opal.c, we are 
looking at using the Linux keyring facility, and then providing a 
special key_type, for the PKS driver, on platforms that support it. We 
would like to have block/sed-opal.c simply call key_type_lookup() for 
the PKS key type, and then (if found) instantiate the keys into the 
keyring. On platforms without a PKS, the same keyring can be used to 
instantiate keys of other types, manually or automatically. These keys 
can then be used directly in SED-OPAL commands without the need to read 
them into userland process memory and pass them in system calls. Any 
platform (non-PowerPC) that might have a Platform Key Store could 
implement this PKS key type as well.


Please let us know if this acceptable. It seems that key_type_lookup() 
is a natural companion to [un]register_key_type() - which are already 
exported symbols.

Thanks,
Doug