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-rw-r--r--drivers/char/Kconfig50
1 files changed, 31 insertions, 19 deletions
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 69fd31ffb847..0b6c03643ddc 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -429,28 +429,40 @@ config ADI
driver include crash and makedumpfile.
config RANDOM_TRUST_CPU
- bool "Trust the CPU manufacturer to initialize Linux's CRNG"
+ bool "Initialize RNG using CPU RNG instructions"
+ default y
depends on ARCH_RANDOM
- default n
help
- Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or
- RDRAND, IBM for the S390 and Power PC architectures) is trustworthy
- for the purposes of initializing Linux's CRNG. Since this is not
- something that can be independently audited, this amounts to trusting
- that CPU manufacturer (perhaps with the insistence or mandate
- of a Nation State's intelligence or law enforcement agencies)
- has not installed a hidden back door to compromise the CPU's
- random number generation facilities. This can also be configured
- at boot with "random.trust_cpu=on/off".
+ Initialize the RNG using random numbers supplied by the CPU's
+ RNG instructions (e.g. RDRAND), if supported and available. These
+ random numbers are never used directly, but are rather hashed into
+ the main input pool, and this happens regardless of whether or not
+ this option is enabled. Instead, this option controls whether the
+ they are credited and hence can initialize the RNG. Additionally,
+ other sources of randomness are always used, regardless of this
+ setting. Enabling this implies trusting that the CPU can supply high
+ quality and non-backdoored random numbers.
+
+ Say Y here unless you have reason to mistrust your CPU or believe
+ its RNG facilities may be faulty. This may also be configured at
+ boot time with "random.trust_cpu=on/off".
config RANDOM_TRUST_BOOTLOADER
- bool "Trust the bootloader to initialize Linux's CRNG"
- help
- Some bootloaders can provide entropy to increase the kernel's initial
- device randomness. Say Y here to assume the entropy provided by the
- booloader is trustworthy so it will be added to the kernel's entropy
- pool. Otherwise, say N here so it will be regarded as device input that
- only mixes the entropy pool. This can also be configured at boot with
- "random.trust_bootloader=on/off".
+ bool "Initialize RNG using bootloader-supplied seed"
+ default y
+ help
+ Initialize the RNG using a seed supplied by the bootloader or boot
+ environment (e.g. EFI or a bootloader-generated device tree). This
+ seed is not used directly, but is rather hashed into the main input
+ pool, and this happens regardless of whether or not this option is
+ enabled. Instead, this option controls whether the seed is credited
+ and hence can initialize the RNG. Additionally, other sources of
+ randomness are always used, regardless of this setting. Enabling
+ this implies trusting that the bootloader can supply high quality and
+ non-backdoored seeds.
+
+ Say Y here unless you have reason to mistrust your bootloader or
+ believe its RNG facilities may be faulty. This may also be configured
+ at boot time with "random.trust_bootloader=on/off".
endmenu