On Mon, Feb 11, 2019 at 07:30:33PM +0200, janne.karhunen@gmail.com wrote:

From: Janne Karhunen <redacted>

Current kernel key subsystem only supports tpm to implement
trusted keys. This is fine, but the tpm is poorly supported
in the embedded world that primarily use custom trust roots,
TEEs or even white box crypto. Problem with these setups is
that they are extremely diverse, complex, proprietary and
in some cases for valid reasons (white box).

This patch provides trial plumbing to enable declaration
of new trust sources via tiny user mode helpers baked as
part of the kernel image. If the hardware based trust source
is available, the provided um helper can read the given
device node and act as a translator for the kernel key
requests and the actual device node can be kept out of the
'regular' userland. In the case of white box crypto, the
um helper is free to perform any sort of software magic
required to mangle the keys within the kernel keyring.

The kernel built-in usermode helper key operations are made
available via new key type named 'ext-trusted' that is
compatible with the existing userland utilities:
keyctl add ext-trusted foo "new_umh 32" @u
keyctl pipe `keyctl search @u ext-trusted foo` > foo.key
keyctl add ext-trusted bar "load `cat foo.key`" @u
...

Signed-off-by: Janne Karhunen <redacted>
Reviewed-by: Pekka Honkanen <redacted>

I guess this misses an actual workload to look at.

/Jarkko