[email protected] wrote:
- Allow a fastpath where we don't even have the user space portion
and the HW drivers just feed the entropy pool directly. While
this bypasses the FIPS tests and such, there are some applications
where this is OK or where we really don't want the extra proccess
context switching. This is specially true on ARM. I'll have to add
IRQ driven support to the drivers to that, but that's trivial. There
is also some HW (MPC8xxx for example) that does periodic self-tests
in HW and lists itself as "FIPs-compliant" and will trigger an error if
data should no longer be trusted and in that case doing a software
test might also be undesirable. But...we should let the user decide
at build time (or runtime?).
Not interesting in pursuing this path. This has been discussed
endlessly, check the archives.
We want the FIPS tests. Hardware (especially cheap hardware) is often
known to go haywire. Trusting hardware to do the FIPS tests is pretty
silly, since you're trusting the piece that might go haywire to tell you
its OK. RNGs have a history of suddenly providing non-random data, for
a variety of reasons (usually poor board wiring).
We also want the userspace daemon because that gives the sysadmin far
more control over how much entropy is added to the system. 99.9% of the
cases in the real world, we don't want the RNG pumping entropy into the
pool at full speed. That will likely pump in more data than a system
needs, chewing CPU. The admin can't even kill the daemon to reclaim his
CPU, if its all in-kernel.
It's not brain surgery, to concoct a method by which an interrupt-driven
device is used from userspace.
Jeff
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