diff options
| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-11-16 17:16:42 +0100 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-11-22 14:53:36 +0100 |
| commit | e7b813b32a42a3a6281a4fd9ae7700a0257c1d50 (patch) | |
| tree | 495840781b62b3861c3857eac2b3d67944509f7e /drivers/firmware/efi/efi.c | |
| parent | 898f1e5c3741ccabda5653f180051cd4aeff3794 (diff) | |
efi: random: refresh non-volatile random seed when RNG is initialized
EFI has a rather unique benefit that it has access to some limited
non-volatile storage, where the kernel can store a random seed. Register
a notification for when the RNG is initialized, and at that point, store
a new random seed.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'drivers/firmware/efi/efi.c')
| -rw-r--r-- | drivers/firmware/efi/efi.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index a46df5d1d094..16dae588f0e3 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -337,6 +337,24 @@ static void __init efi_debugfs_init(void) static inline void efi_debugfs_init(void) {} #endif +static void refresh_nv_rng_seed(struct work_struct *work) +{ + u8 seed[EFI_RANDOM_SEED_SIZE]; + + get_random_bytes(seed, sizeof(seed)); + efi.set_variable(L"RandomSeed", &LINUX_EFI_RANDOM_SEED_TABLE_GUID, + EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, sizeof(seed), seed); + memzero_explicit(seed, sizeof(seed)); +} +static int refresh_nv_rng_seed_notification(struct notifier_block *nb, unsigned long action, void *data) +{ + static DECLARE_WORK(work, refresh_nv_rng_seed); + schedule_work(&work); + return NOTIFY_DONE; +} +static struct notifier_block refresh_nv_rng_seed_nb = { .notifier_call = refresh_nv_rng_seed_notification }; + /* * We register the efi subsystem with the firmware subsystem and the * efivars subsystem with the efi subsystem, if the system was booted with @@ -413,6 +431,7 @@ static int __init efisubsys_init(void) platform_device_register_simple("efi_secret", 0, NULL, 0); #endif + execute_with_initialized_rng(&refresh_nv_rng_seed_nb); return 0; err_remove_group: |