efi/random: Treat EFI_RNG_PROTOCOL output as bootloader randomness

Commit 428826f5358c ("fdt: add support for rng-seed") introduced
add_bootloader_randomness(), permitting randomness provided by the
bootloader or firmware to be credited as entropy. However, the fact
that the UEFI support code was already wired into the RNG subsystem
via a call to add_device_randomness() was overlooked, and so it was
not converted at the same time.

Note that this UEFI (v2.4 or newer) feature is currently only
implemented for EFI stub booting on ARM, and further note that
CONFIG_RANDOM_TRUST_BOOTLOADER must be enabled, and this should be
done only if there indeed is sufficient trust in the bootloader
_and_ its source of randomness.

[ ardb: update commit log ]

Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20191029173755.27149-4-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 69f00f7453a34c386237f4b2344f66a05f3c67fc..e98bbf8e56d9b07e7c609fb614e2105decd99175 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -554,7 +554,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
                                              sizeof(*seed) + size);
                        if (seed != NULL) {
                                pr_notice("seeding entropy pool\n");
-                               add_device_randomness(seed->bits, seed->size);
+                               add_bootloader_randomness(seed->bits, seed->size);
                                early_memunmap(seed, sizeof(*seed) + size);
                        } else {
                                pr_err("Could not map UEFI random seed!\n");