From: Ard Biesheuvel <ard.biesheu...@linaro.org>
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.
Cc: Matt Fleming <m...@codeblueprint.co.uk>
Reviewed-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
drivers/firmware/efi/libstub/arm-stub.c | 2 ++
drivers/firmware/efi/libstub/efistub.h | 2 ++
drivers/firmware/efi/libstub/random.c | 48 +++++++++++++++++++++++++++++++++
include/linux/efi.h | 1 +
4 files changed, 53 insertions(+)
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;
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 85e28b138cdd..f5a821d9b90c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -589,6 +589,7 @@ void efi_native_runtime_setup(void);
#define DEVICE_TREE_GUID EFI_GUID(0xb1b621d5, 0xf19c,
0x41a5, 0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0)
#define EFI_PROPERTIES_TABLE_GUID EFI_GUID(0x880aaca3, 0x4adc,
0x4a04, 0x90, 0x79, 0xb7, 0x47, 0x34, 0x08, 0x25, 0xe5)
#define EFI_RNG_PROTOCOL_GUID EFI_GUID(0x3152bca5, 0xeade,
0x433d, 0x86, 0x2e, 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44)
+#define EFI_RNG_ALGORITHM_RAW EFI_GUID(0xe43176d7, 0xb6e8,
0x4827, 0xb7, 0x84, 0x7f, 0xfd, 0xc4, 0xb6, 0x85, 0x61)
#define EFI_MEMORY_ATTRIBUTES_TABLE_GUID EFI_GUID(0xdcfa911d, 0x26eb,
0x469f, 0xa2, 0x20, 0x38, 0xb7, 0xdc, 0x46, 0x12, 0x20)
#define EFI_CONSOLE_OUT_DEVICE_GUID EFI_GUID(0xd3b36f2c, 0xd551,
0x11d4, 0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
--
2.10.0
