crypto: rng - FIPS 140-3 compliance for random number generation

This patch series implements FIPS 140-3 compliance requirements for random number generation in the Linux kernel 6.12 stable. The changes ensure that when the kernel is operating in FIPS mode, FIPS-compliant random number generators from the Crypto API are used to override the default /dev/random implementation.

The series consists of two patches:

1. "random: Add hook to override device reads and getrandom(2)" - This patch introduces the infrastructure to allow external RNGs to override the default random number generation. Originally authored by Herbert Xu, this has been adapted for kernel 6.12.

2. "crypto: rng - Override drivers/char/random only after FIPS RNGs available" - This patch implements the actual FIPS mode override using a workqueue-based approach to ensure proper initialization timing. It addresses timing issues in a previous commit "crypto: rng - Override drivers/char/random only after FIPS RNGs available" where the crypto RNG would attempt to override before dependencies were ready, preventing potential boot failures.

These patches are required for FIPS 140-3 certification and compliance in government and enterprise environments where cryptographic standards must be strictly enforced.

Herbert Xu (1):
random: Add hook to override device reads and getrandom(2)

Jay Wang (1):
crypto: rng - Override drivers/char/random only after FIPS RNGs
available

 crypto/rng.c           |  92 +++++++++++++++++++++++++++++++++
 drivers/char/random.c  | 114 +++++++++++++++++++++++++++++++++++++++++
 include/linux/random.h |   7 +++
 3 files changed, 213 insertions(+)

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2.47.1