On Mon, Jan 10, 2022 at 9:18 PM Theodore Ts'o [off-list ref] wrote:

In general, you need FIPS
certification for some specific use cases / application.  For example,
if you're going for PCI compliance, then you might only need FIPS
compliance for your OpenSSL library.  What the FIPS certification lab
might consider acceptable for its entropy for its DRBG is an
interesting question.  For some, simply having the OpenSSL library use
RDSEED or RDRAND might be sufficient.  Or it could talk to an actual
physical RNG device.

So disabling getrandom() is probably not necessary, just so long as
you can demonstrate that the FIPS cryptographic module --- i.e., the
OpenSSL library --- is getting its entropy from an acceptable source.

I don't know exactly what these people think they want, but what you
say seems probably correct.

I suspect what's actually going on is that some enterprise customers
have FIPS complaince on a check-off list, and they aren't actually
getting a formal FIPS certification.  Or they only need something to
wave under the noses of their PCI certification company, and so the
question is what makes them happy.

Right.

And this is why some FIPS certification have gotten by just *fine*
with a pure userspace OpenSSL library as their FIPS cryptographic
module.  Where you draw the line between a "blessed" entropy source
and one that's just hand-waving is really at the discretion of the
certification lab.

Hah, probably correct.

So, seen this way, and combined with the solution provided at [1] (or
similar) for people who think they need something there, it seems like
the FIPS people can likely get what they need without really needing
to involve the kernel anyway.

Jason

[1] https://lore.kernel.org/lkml/YdynXjhhuQfbYuSb@zx2c4.com/ (local)