From 568bc4e87033d232c5fd00d5b0cd22a2ccc04944 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 12 Nov 2016 21:32:33 +0000 Subject: efi/arm*/libstub: Invoke EFI_RNG_PROTOCOL to seed the UEFI RNG table Invoke the EFI_RNG_PROTOCOL protocol in the context of the stub and install the Linux-specific RNG seed UEFI config table. This will be picked up by the EFI routines in the core kernel to seed the kernel entropy pool. Signed-off-by: Ard Biesheuvel Signed-off-by: Matt Fleming Reviewed-by: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20161112213237.8804-6-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- drivers/firmware/efi/libstub/arm-stub.c | 2 ++ drivers/firmware/efi/libstub/efistub.h | 2 ++ drivers/firmware/efi/libstub/random.c | 48 +++++++++++++++++++++++++++++++++ 3 files changed, 52 insertions(+) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 993aa56755f6..b4f7d78f9e8b 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -340,6 +340,8 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, if (status != EFI_SUCCESS) pr_efi_err(sys_table, "Failed initrd from command line!\n"); + efi_random_get_seed(sys_table); + new_fdt_addr = fdt_addr; status = allocate_new_fdt_and_exit_boot(sys_table, handle, &new_fdt_addr, dram_base + MAX_FDT_OFFSET, diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index fe1f22584c69..b98824e3800a 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -71,4 +71,6 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, efi_status_t check_platform_features(efi_system_table_t *sys_table_arg); +efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg); + #endif diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index f8e2e5ae6872..3a3feacc329f 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -143,3 +143,51 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, return status; } + +#define RANDOM_SEED_SIZE 32 + +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_algo_raw = EFI_RNG_ALGORITHM_RAW; + efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; + struct efi_rng_protocol *rng; + struct linux_efi_random_seed *seed; + efi_status_t status; + + status = efi_call_early(locate_protocol, &rng_proto, NULL, + (void **)&rng); + if (status != EFI_SUCCESS) + return status; + + status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA, + sizeof(*seed) + RANDOM_SEED_SIZE, + (void **)&seed); + if (status != EFI_SUCCESS) + return status; + + status = rng->get_rng(rng, &rng_algo_raw, RANDOM_SEED_SIZE, + seed->bits); + if (status == EFI_UNSUPPORTED) + /* + * Use whatever algorithm we have available if the raw algorithm + * is not implemented. + */ + status = rng->get_rng(rng, NULL, RANDOM_SEED_SIZE, + seed->bits); + + if (status != EFI_SUCCESS) + goto err_freepool; + + seed->size = RANDOM_SEED_SIZE; + status = efi_call_early(install_configuration_table, &rng_table_guid, + seed); + if (status != EFI_SUCCESS) + goto err_freepool; + + return EFI_SUCCESS; + +err_freepool: + efi_call_early(free_pool, seed); + return status; +} -- cgit v1.2.3