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random: use random.trust_{bootloader,cpu} command line option only

Browse source 
It's very unusual to have both a command line option and a compile time
option, and apparently that's confusing to people. Also, basically
everybody enables the compile time option now, which means people who
want to disable this wind up having to use the command line option to
ensure that anyway. So just reduce the number of moving pieces and nix
the compile time option in favor of the more versatile command line
option.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2022-11-01 13:03:55 +01:00
parent 622754e84b
commit b9b01a5625
8 changed files with 13 additions and 59 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
Documentation/admin-guide/kernel-parameters.txt
View file

@ -4566,17 +4566,15 @@
ramdisk_start= [RAM] RAM disk image start address
random.trust_cpu={on,off}
[KNL] Enable or disable trusting the use of the
CPU's random number generator (if available) to
fully seed the kernel's CRNG. Default is controlled
by CONFIG_RANDOM_TRUST_CPU.
random.trust_cpu=off
[KNL] Disable trusting the use of the CPU's
random number generator (if available) to
initialize the kernel's RNG.
random.trust_bootloader={on,off}
[KNL] Enable or disable trusting the use of a
seed passed by the bootloader (if available) to
fully seed the kernel's CRNG. Default is controlled
by CONFIG_RANDOM_TRUST_BOOTLOADER.
random.trust_bootloader=off
[KNL] Disable trusting the use of the a seed
passed by the bootloader (if available) to
initialize the kernel's RNG.
randomize_kstack_offset=
[KNL] Enable or disable kernel stack offset

1
arch/powerpc/configs/microwatt_defconfig
View file

@ -68,7 +68,6 @@ CONFIG_SERIAL_8250_CONSOLE=y
CONFIG_SERIAL_OF_PLATFORM=y
CONFIG_SERIAL_NONSTANDARD=y
# CONFIG_NVRAM is not set
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_SPI=y
CONFIG_SPI_DEBUG=y
CONFIG_SPI_BITBANG=y

2
arch/s390/configs/debug_defconfig
View file

@ -573,8 +573,6 @@ CONFIG_VIRTIO_CONSOLE=m
CONFIG_HW_RANDOM_VIRTIO=m
CONFIG_HANGCHECK_TIMER=m
CONFIG_TN3270_FS=y
# CONFIG_RANDOM_TRUST_CPU is not set
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
CONFIG_PPS=m
# CONFIG_PTP_1588_CLOCK is not set
# CONFIG_HWMON is not set

2
arch/s390/configs/defconfig
View file

@ -563,8 +563,6 @@ CONFIG_VIRTIO_CONSOLE=m
CONFIG_HW_RANDOM_VIRTIO=m
CONFIG_HANGCHECK_TIMER=m
CONFIG_TN3270_FS=y
# CONFIG_RANDOM_TRUST_CPU is not set
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
# CONFIG_PTP_1588_CLOCK is not set
# CONFIG_HWMON is not set
CONFIG_WATCHDOG=y

1
arch/s390/configs/zfcpdump_defconfig
View file

@ -58,7 +58,6 @@ CONFIG_ZFCP=y
# CONFIG_VMCP is not set
# CONFIG_MONWRITER is not set
# CONFIG_S390_VMUR is not set
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
# CONFIG_HID is not set
# CONFIG_VIRTIO_MENU is not set
# CONFIG_VHOST_MENU is not set

36
drivers/char/Kconfig
View file

@ -423,40 +423,4 @@ config ADI
and SSM (Silicon Secured Memory). Intended consumers of this
driver include crash and makedumpfile.
config RANDOM_TRUST_CPU
bool "Initialize RNG using CPU RNG instructions"
default y
help
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 "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

10
drivers/char/random.c
View file

@ -748,7 +748,7 @@ static void __cold _credit_init_bits(size_t bits)
*
* add_bootloader_randomness() is called by bootloader drivers, such as EFI
* and device tree, and credits its input depending on whether or not the
* configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
* command line option 'random.trust_bootloader'.
*
* add_vmfork_randomness() adds a unique (but not necessarily secret) ID
* representing the current instance of a VM to the pool, without crediting,
@ -774,8 +774,8 @@ static void __cold _credit_init_bits(size_t bits)
*
**********************************************************************/
static bool trust_cpu __initdata = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
static bool trust_bootloader __initdata = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
static bool trust_cpu __initdata = true;
static bool trust_bootloader __initdata = true;
static int __init parse_trust_cpu(char *arg)
{
return kstrtobool(arg, &trust_cpu);
@ -926,8 +926,8 @@ void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy)
EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
/*
* Handle random seed passed by bootloader, and credit it if
* CONFIG_RANDOM_TRUST_BOOTLOADER is set.
* Handle random seed passed by bootloader, and credit it depending
* on the command line option 'random.trust_bootloader'.
*/
void __init add_bootloader_randomness(const void *buf, size_t len)
{

2
tools/testing/selftests/wireguard/qemu/kernel.config
View file

@ -64,8 +64,6 @@ CONFIG_PROC_FS=y
CONFIG_PROC_SYSCTL=y
CONFIG_SYSFS=y
CONFIG_TMPFS=y
CONFIG_RANDOM_TRUST_CPU=y
CONFIG_RANDOM_TRUST_BOOTLOADER=y
CONFIG_CONSOLE_LOGLEVEL_DEFAULT=15
CONFIG_LOG_BUF_SHIFT=18
CONFIG_PRINTK_TIME=y