tree e99c70203695fe178387016697c04f05d9dad8c0
parent 4ca15d5dcbe6e8051a4654df7c971ea8307abfe0
author Adam Langley <agl@google.com> 1571167874 -0700
committer Adam Langley <agl@google.com> 1571171180 -0700

Fix GRND_NONBLOCK flag when calling getrandom.

I screwed up in 56b6c714c9 and got the direction of this condition
backwards. This doesn't cause a security problem because:
  a) wait_for_entropy will ensure that the pool is initialised.
  b) if GRNG_NONBLOCK is set when not expected, any EAGAIN will
     cause an abort anyway.

However, when coupled with opportunistic entropy collection on platforms
with RDRAND, this could cause an unexpected blocking getrandom call.

This this change, `strace -e getrandom bssl rand 1` shows two getrandom
calls with GRNG_NONBLOCK set, as expected. (The first being the probe to
check whether the kernel supports getrandom, and the second being the
opportunistic entropy gathering to augment RDRAND.)

Change-Id: I98ed1cef90df510f24cf2df1fba9b886fcbf3355