@@ -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:
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. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- drivers/firmware/efi/efi.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)