Commit c2ceb5fd authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar

efi/random: Increase size of firmware supplied randomness

The crng code requires at least 64 bytes (2 * CHACHA20_BLOCK_SIZE)
to complete the fast boot-time init, so provide that many bytes
when invoking UEFI protocols to seed the entropy pool. Also, add
a notice so we can tell from the boot log when the seeding actually
took place.
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170825155019.6740-3-ard.biesheuvel@linaro.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ccc829ba
...@@ -541,6 +541,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz, ...@@ -541,6 +541,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
if (seed != NULL) { if (seed != NULL) {
add_device_randomness(seed->bits, seed->size); add_device_randomness(seed->bits, seed->size);
early_memunmap(seed, sizeof(*seed) + size); early_memunmap(seed, sizeof(*seed) + size);
pr_notice("seeding entropy pool\n");
} else { } else {
pr_err("Could not map UEFI random seed!\n"); pr_err("Could not map UEFI random seed!\n");
} }
...@@ -900,7 +901,7 @@ static int update_efi_random_seed(struct notifier_block *nb, ...@@ -900,7 +901,7 @@ static int update_efi_random_seed(struct notifier_block *nb,
seed = memremap(efi.rng_seed, sizeof(*seed), MEMREMAP_WB); seed = memremap(efi.rng_seed, sizeof(*seed), MEMREMAP_WB);
if (seed != NULL) { if (seed != NULL) {
size = min(seed->size, 32U); size = min(seed->size, EFI_RANDOM_SEED_SIZE);
memunmap(seed); memunmap(seed);
} else { } else {
pr_err("Could not map UEFI random seed!\n"); pr_err("Could not map UEFI random seed!\n");
......
...@@ -145,8 +145,6 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, ...@@ -145,8 +145,6 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
return status; return status;
} }
#define RANDOM_SEED_SIZE 32
efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg) efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
{ {
efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
...@@ -162,25 +160,25 @@ efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg) ...@@ -162,25 +160,25 @@ efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
return status; return status;
status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA, status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
sizeof(*seed) + RANDOM_SEED_SIZE, sizeof(*seed) + EFI_RANDOM_SEED_SIZE,
(void **)&seed); (void **)&seed);
if (status != EFI_SUCCESS) if (status != EFI_SUCCESS)
return status; return status;
status = rng->get_rng(rng, &rng_algo_raw, RANDOM_SEED_SIZE, status = rng->get_rng(rng, &rng_algo_raw, EFI_RANDOM_SEED_SIZE,
seed->bits); seed->bits);
if (status == EFI_UNSUPPORTED) if (status == EFI_UNSUPPORTED)
/* /*
* Use whatever algorithm we have available if the raw algorithm * Use whatever algorithm we have available if the raw algorithm
* is not implemented. * is not implemented.
*/ */
status = rng->get_rng(rng, NULL, RANDOM_SEED_SIZE, status = rng->get_rng(rng, NULL, EFI_RANDOM_SEED_SIZE,
seed->bits); seed->bits);
if (status != EFI_SUCCESS) if (status != EFI_SUCCESS)
goto err_freepool; goto err_freepool;
seed->size = RANDOM_SEED_SIZE; seed->size = EFI_RANDOM_SEED_SIZE;
status = efi_call_early(install_configuration_table, &rng_table_guid, status = efi_call_early(install_configuration_table, &rng_table_guid,
seed); seed);
if (status != EFI_SUCCESS) if (status != EFI_SUCCESS)
......
...@@ -1571,6 +1571,8 @@ efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table, ...@@ -1571,6 +1571,8 @@ efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table,
void *priv, void *priv,
efi_exit_boot_map_processing priv_func); efi_exit_boot_map_processing priv_func);
#define EFI_RANDOM_SEED_SIZE 64U
struct linux_efi_random_seed { struct linux_efi_random_seed {
u32 size; u32 size;
u8 bits[]; u8 bits[];
......
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