Register a notifier so that when the RNG is initialized, the EFI
variable containing the random seed can be refreshed.
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
drivers/firmware/efi/efi.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index a46df5d1d094..db247a52d3c2 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -337,6 +337,19 @@ static void __init efi_debugfs_init(void)
static inline void efi_debugfs_init(void) {}
#endif
+static int refresh_nv_rng_seed(struct notifier_block *nb, unsigned long action, void *data)
+{
+ u8 seed[EFI_RANDOM_SEED_SIZE];
+
+ get_random_bytes(seed, sizeof(seed));
+ efi.set_variable(LINUX_EFI_RANDOM_NV_SEED_VAR, &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));
+ return 0;
+}
+static struct notifier_block refresh_nv_rng_seed_nb = { .notifier_call = refresh_nv_rng_seed };
+
/*
* 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 +426,7 @@ static int __init efisubsys_init(void)
platform_device_register_simple("efi_secret", 0, NULL, 0);
#endif
+ notify_on_rng_initialized(&refresh_nv_rng_seed_nb);
return 0;
err_remove_group:
--
2.38.1
