[PATCH v1 32/54] efi: loader: protocol: add random number generator protocol

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Make available the default random number generator in barebox to EFI
applications during boot time.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 efi/loader/protocols/Kconfig  |   8 ++
 efi/loader/protocols/Makefile |   1 +
 efi/loader/protocols/rng.c    | 165 ++++++++++++++++++++++++++++++++++
 3 files changed, 174 insertions(+)
 create mode 100644 efi/loader/protocols/rng.c

diff --git a/efi/loader/protocols/Kconfig b/efi/loader/protocols/Kconfig
index 8c8bfabd7c0f..7d5e203d121a 100644
--- a/efi/loader/protocols/Kconfig
+++ b/efi/loader/protocols/Kconfig
@@ -31,4 +31,12 @@ config EFI_LOADER_UNICODE_CAPITALIZATION
 	  set, only the the correct handling of the letters of the codepage
 	  used by the FAT file system is ensured.
 
+config EFI_LOADER_RNG
+	bool "EFI_RNG_PROTOCOL support"
+	depends on HWRNG
+	default y
+	help
+	  Provide a EFI_RNG_PROTOCOL implementation using the hardware random
+	  number generator of the platform.
+
 endmenu
diff --git a/efi/loader/protocols/Makefile b/efi/loader/protocols/Makefile
index b6e39b0666da..ecc0fc392856 100644
--- a/efi/loader/protocols/Makefile
+++ b/efi/loader/protocols/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_VIDEO) += gop.o
 obj-$(CONFIG_CONSOLE_FULL) += console.o
 obj-$(CONFIG_EFI_LOADER_HII) += hii.o hii_config.o
 obj-$(CONFIG_EFI_LOADER_UNICODE_COLLATION_PROTOCOL2) += unicode_collation.o
+obj-$(CONFIG_EFI_LOADER_RNG) += rng.o
diff --git a/efi/loader/protocols/rng.c b/efi/loader/protocols/rng.c
new file mode 100644
index 000000000000..9c3caa82f884
--- /dev/null
+++ b/efi/loader/protocols/rng.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0+
+// SPDX-Comment: Origin-URL: https://github.com/u-boot/u-boot/blob/58da850c87240c397242ebd47341c69aa6278119/lib/efi_loader/efi_rng.c
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#include <linux/hw_random.h>
+#include <stdlib.h>
+#include <efi/loader.h>
+#include <efi/protocol/rng.h>
+#include <efi/devicepath.h>
+#include <efi/loader/devicepath.h>
+#include <efi/loader/object.h>
+#include <efi/loader/trace.h>
+#include <efi/guid.h>
+#include <efi/error.h>
+#include <xfuncs.h>
+
+struct efi_rng_obj {
+	struct efi_object header;
+	struct hwrng *hwrng;
+	struct efi_rng_protocol ops;
+};
+
+#define to_efi_rng_obj(this) container_of(this, struct efi_rng_obj, ops)
+
+/**
+ * rng_getinfo() - get information about random number generation
+ *
+ * This function implement the GetInfo() service of the EFI random number
+ * generator protocol. See the UEFI spec for details.
+ *
+ * @this:			random number generator protocol instance
+ * @rng_algorithm_list_size:	number of random number generation algorithms
+ * @rng_algorithm_list:		descriptions of random number generation
+ *				algorithms
+ * Return:			status code
+ */
+static efi_status_t EFIAPI rng_getinfo(struct efi_rng_protocol *this,
+				       efi_uintn_t *rng_algorithm_list_size,
+				       efi_guid_t *rng_algorithm_list)
+{
+	efi_status_t ret = EFI_SUCCESS;
+	efi_guid_t rng_algo_guid = EFI_RNG_ALGORITHM_RAW;
+
+	EFI_ENTRY("%p, %p, %p", this, rng_algorithm_list_size,
+		  rng_algorithm_list);
+
+	if (!this || !rng_algorithm_list_size) {
+		ret = EFI_INVALID_PARAMETER;
+		goto back;
+	}
+
+	if (!rng_algorithm_list ||
+	    *rng_algorithm_list_size < sizeof(*rng_algorithm_list)) {
+		*rng_algorithm_list_size = sizeof(*rng_algorithm_list);
+		ret = EFI_BUFFER_TOO_SMALL;
+		goto back;
+	}
+
+	/*
+	 * For now, use EFI_RNG_ALGORITHM_RAW as the default
+	 * algorithm. If a new algorithm gets added in the
+	 * future through a Kconfig, rng_algo_guid will be set
+	 * based on that Kconfig option
+	 */
+	*rng_algorithm_list_size = sizeof(*rng_algorithm_list);
+	*rng_algorithm_list = rng_algo_guid;
+
+back:
+	return EFI_EXIT(ret);
+}
+
+/**
+ * rng_getval() - get random value
+ *
+ * This function implement the GetRng() service of the EFI random number
+ * generator protocol. See the UEFI spec for details.
+ *
+ * @this:		random number generator protocol instance
+ * @rng_algorithm:	random number generation algorithm
+ * @rng_value_length:	number of random bytes to generate, buffer length
+ * @rng_value:		buffer to receive random bytes
+ * Return:		status code
+ */
+static efi_status_t EFIAPI rng_getval(struct efi_rng_protocol *this,
+				  efi_guid_t *rng_algorithm,
+				  efi_uintn_t rng_value_length,
+				  uint8_t *rng_value)
+{
+	int ret;
+	efi_status_t status = EFI_SUCCESS;
+	const efi_guid_t rng_raw_guid = EFI_RNG_ALGORITHM_RAW;
+	struct efi_rng_obj *rngobj = to_efi_rng_obj(this);
+
+	EFI_ENTRY("%p, %p, %zu, %p", this, rng_algorithm, rng_value_length,
+		  rng_value);
+
+	if (!this || !rng_value || !rng_value_length) {
+		status = EFI_INVALID_PARAMETER;
+		goto back;
+	}
+
+	if (rng_algorithm) {
+		EFI_PRINT("RNG algorithm %pUl\n", rng_algorithm);
+		if (efi_guidcmp(*rng_algorithm, rng_raw_guid)) {
+			status = EFI_UNSUPPORTED;
+			goto back;
+		}
+	}
+
+	ret = hwrng_get_crypto_bytes(rngobj->hwrng, rng_value, rng_value_length);
+	if (ret < 0) {
+		EFI_PRINT("Rng device read failed\n");
+		status = EFI_DEVICE_ERROR;
+		goto back;
+	}
+
+back:
+	return EFI_EXIT(status);
+}
+
+/**
+ * efi_rng_register() - register EFI_RNG_PROTOCOL
+ *
+ * If a HWRNG device is available, the Random Number Generator Protocol is
+ * registered.
+ *
+ * Return:	An EFI error status
+ */
+static efi_status_t efi_rng_register(void *data)
+{
+	struct efi_rng_obj *rngobj;
+	struct hwrng *rng;
+	struct efi_device_path *dp;
+	efi_handle_t handle;
+
+	rng = hwrng_get_first();
+	if (IS_ERR(rng))
+		return EFI_UNSUPPORTED;
+
+	rngobj = xzalloc(sizeof(*rngobj));
+
+	rngobj->hwrng = rng;
+	rngobj->ops.get_info = rng_getinfo;
+	rngobj->ops.get_rng = rng_getval;
+
+	dp = efi_dp_from_cdev(&rng->cdev, true);
+
+	efi_add_handle(&rngobj->header);
+
+	handle = &rngobj->header;
+
+	return efi_install_multiple_protocol_interfaces(&handle,
+							&efi_device_path_protocol_guid, dp,
+							&efi_rng_protocol_guid, &rngobj->ops,
+							NULL);
+}
+
+static int efi_rng_init(void)
+{
+	efi_register_deferred_init(efi_rng_register, NULL);
+	return 0;
+}
+device_initcall(efi_rng_init);
-- 
2.47.3