linux/arch
Jason A. Donenfeld 0b9ba6135d um: seed rng using host OS rng
UML generally does not provide access to special CPU instructions like
RDRAND, and execution tends to be rather deterministic, with no real
hardware interrupts, making good randomness really very hard, if not
all together impossible. Not only is this a security eyebrow raiser, but
it's also quite annoying when trying to do various pieces of UML-based
automation that takes a long time to boot, if ever.

Fix this by trivially calling getrandom() in the host and using that
seed as "bootloader randomness", which initializes the rng immediately
at UML boot.

The old behavior can be restored the same way as on any other arch, by
way of CONFIG_TRUST_BOOTLOADER_RANDOMNESS=n or
random.trust_bootloader=0. So seen from that perspective, this just
makes UML act like other archs, which is positive in its own right.

Additionally, wire up arch_get_random_{int,long}() in the same way, so
that reseeds can also make use of the host RNG, controllable by
CONFIG_TRUST_CPU_RANDOMNESS and random.trust_cpu, per usual.

Cc: stable@vger.kernel.org
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-07-18 15:04:04 +02:00
..
alpha Cleanups (and one fix) around struct mount handling. 2022-06-04 19:00:05 -07:00
arc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
arm random: remove CONFIG_ARCH_RANDOM 2022-07-18 15:03:37 +02:00
arm64 random: remove CONFIG_ARCH_RANDOM 2022-07-18 15:03:37 +02:00
csky This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
hexagon
ia64 Bitmap patches for 5.19-rc1 2022-06-04 14:04:27 -07:00
loongarch LoongArch: Fix section mismatch warning 2022-07-07 17:41:01 +08:00
m68k This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
microblaze This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
mips mips: lantiq: Add missing of_node_put() in irq.c 2022-06-21 22:34:03 +02:00
nios2 This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
openrisc openrisc: unwinder: Fix grammar issue in comment 2022-06-28 17:31:24 +09:00
parisc parisc: Fix vDSO signal breakage on 32-bit kernel 2022-07-02 18:36:58 +02:00
powerpc random: remove CONFIG_ARCH_RANDOM 2022-07-18 15:03:37 +02:00
riscv RISC-V Fixes for 5.19-rc7 2022-07-15 10:40:50 -07:00
s390 random: remove CONFIG_ARCH_RANDOM 2022-07-18 15:03:37 +02:00
sh sh: convert nommu io{re,un}map() to static inline functions 2022-07-03 15:42:32 -07:00
sparc This set of changes updates init and user mode helper tasks to be 2022-06-03 16:03:05 -07:00
um um: seed rng using host OS rng 2022-07-18 15:04:04 +02:00
x86 x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu" 2022-07-18 15:04:04 +02:00
xtensa xtensa: change '.bss' to '.section .bss' 2022-06-20 02:50:34 -07:00
.gitignore
Kconfig A set of objtool fixes: 2022-06-05 09:45:27 -07:00