On Tue, Jul 17, 2018 at 9:51 PM, Theodore Y. Ts'o <tytso@xxxxxxx> wrote: > On Tue, Jul 17, 2018 at 09:43:44PM -0400, Theodore Ts'o wrote: >> This gives the user building their own kernel (or a Linux >> distribution) the option of deciding whether or not to trust the CPU's >> hardware random number generator (e.g., RDRAND for x86 CPU's) as being >> correctly implemented and not having a back door introduced (perhaps >> courtesy of a Nation State's law enforcement or intelligence >> agencies). >> >> This will prevent getrandom(2) from blocking, if there is a >> willingness to trust the CPU manufacturer. >> >> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> > > Note, I had meant to tag this with an RFC. I'm not sure I really want > to push this to Linus yet. If you have an opinion, let me know. I had something like this in patches I suggested as RFC a couple of years back. Those patches were rejected for other reasons, quite likely valid ones. My version was not binary like this: >> +config RANDOM_TRUST_CPU >> + bool "Trust the CPU manufacturer to initialize Linux's CRNG" Instead, I had a compile-time option to choose a number 0-32 for how much entropy to assume a 32-bit value from the HWRNG contains. Default was something less than 32. I debated values in the 24-30 range, don't recall what I chose & don't think it Matters hugely. Is that a better approach than the binary choice?
