diff options
| -rw-r--r-- | drivers/firmware/efi/efi.c | 4 | ||||
| -rw-r--r-- | drivers/firmware/efi/libstub/efistub.h | 2 | ||||
| -rw-r--r-- | drivers/firmware/efi/libstub/random.c | 42 | ||||
| -rw-r--r-- | include/linux/efi.h | 2 |
4 files changed, 40 insertions, 10 deletions
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index dfdbbc702da0..297bf3fd9acc 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -613,7 +613,7 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, seed = early_memremap(efi_rng_seed, sizeof(*seed)); if (seed != NULL) { - size = min(seed->size, EFI_RANDOM_SEED_SIZE); + size = min_t(u32, seed->size, SZ_1K); // sanity check early_memunmap(seed, sizeof(*seed)); } else { pr_err("Could not map UEFI random seed!\n"); @@ -622,8 +622,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, seed = early_memremap(efi_rng_seed, sizeof(*seed) + size); if (seed != NULL) { - pr_notice("seeding entropy pool\n"); add_bootloader_randomness(seed->bits, size); + memzero_explicit(seed->bits, size); early_memunmap(seed, sizeof(*seed) + size); } else { pr_err("Could not map UEFI random seed!\n"); diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index 5615ad6f2958..ed405f8d09a8 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -933,6 +933,8 @@ efi_status_t efi_random_alloc(unsigned long size, unsigned long align, unsigned long *addr, unsigned long random_seed, int memory_type); +efi_status_t efi_random_get_seed(void); + efi_status_t check_platform_features(void); void *get_efi_config_table(efi_guid_t guid); diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index 33ab56769595..f85d2c066877 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -67,8 +67,9 @@ efi_status_t efi_random_get_seed(void) efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; + struct linux_efi_random_seed *prev_seed, *seed = NULL; + int prev_seed_size = 0, seed_size = EFI_RANDOM_SEED_SIZE; efi_rng_protocol_t *rng = NULL; - struct linux_efi_random_seed *seed = NULL; efi_status_t status; status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); @@ -76,18 +77,33 @@ efi_status_t efi_random_get_seed(void) return status; /* + * Check whether a seed was provided by a prior boot stage. In that + * case, instead of overwriting it, let's create a new buffer that can + * hold both, and concatenate the existing and the new seeds. + * Note that we should read the seed size with caution, in case the + * table got corrupted in memory somehow. + */ + prev_seed = get_efi_config_table(LINUX_EFI_RANDOM_SEED_TABLE_GUID); + if (prev_seed && prev_seed->size <= 512U) { + prev_seed_size = prev_seed->size; + seed_size += prev_seed_size; + } + + /* * Use EFI_ACPI_RECLAIM_MEMORY here so that it is guaranteed that the * allocation will survive a kexec reboot (although we refresh the seed * beforehand) */ status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY, - sizeof(*seed) + EFI_RANDOM_SEED_SIZE, + struct_size(seed, bits, seed_size), (void **)&seed); - if (status != EFI_SUCCESS) - return status; + if (status != EFI_SUCCESS) { + efi_warn("Failed to allocate memory for RNG seed.\n"); + goto err_warn; + } status = efi_call_proto(rng, get_rng, &rng_algo_raw, - EFI_RANDOM_SEED_SIZE, seed->bits); + EFI_RANDOM_SEED_SIZE, seed->bits); if (status == EFI_UNSUPPORTED) /* @@ -100,14 +116,28 @@ efi_status_t efi_random_get_seed(void) if (status != EFI_SUCCESS) goto err_freepool; - seed->size = EFI_RANDOM_SEED_SIZE; + seed->size = seed_size; + if (prev_seed_size) + memcpy(seed->bits + EFI_RANDOM_SEED_SIZE, prev_seed->bits, + prev_seed_size); + status = efi_bs_call(install_configuration_table, &rng_table_guid, seed); if (status != EFI_SUCCESS) goto err_freepool; + if (prev_seed_size) { + /* wipe and free the old seed if we managed to install the new one */ + memzero_explicit(prev_seed->bits, prev_seed_size); + efi_bs_call(free_pool, prev_seed); + } return EFI_SUCCESS; err_freepool: + memzero_explicit(seed, struct_size(seed, bits, seed_size)); efi_bs_call(free_pool, seed); + efi_warn("Failed to obtain seed from EFI_RNG_PROTOCOL\n"); +err_warn: + if (prev_seed) + efi_warn("Retaining bootloader-supplied seed only"); return status; } diff --git a/include/linux/efi.h b/include/linux/efi.h index 400edf77bb12..4b27519143f5 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1133,8 +1133,6 @@ void efi_check_for_embedded_firmwares(void); static inline void efi_check_for_embedded_firmwares(void) { } #endif -efi_status_t efi_random_get_seed(void); - #define arch_efi_call_virt(p, f, args...) ((p)->f(args)) /* |