efi_selftest: unit test for EFI_RNG_PROTOCOL

Provide a unit test for the EFI_RNG_PROTOCOL.

The list of algorithms is read. Two random numbers are generated. The test
checks that the two numbers differ.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

lib/efi_selftest/Makefile

@@ -47,6 +47,7 @@ efi_selftest_unicode_collation.o
 
 obj-$(CONFIG_CPU_V7) += efi_selftest_unaligned.o
 obj-$(CONFIG_EFI_LOADER_HII) += efi_selftest_hii.o
+obj-$(CONFIG_EFI_RNG_PROTOCOL) += efi_selftest_rng.o
 obj-$(CONFIG_EFI_GET_TIME) += efi_selftest_rtc.o
 
 ifeq ($(CONFIG_GENERATE_ACPI_TABLE),)

lib/efi_selftest/efi_selftest_rng.c

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * efi_selftest_rng
+ *
+ * Copyright (c) 2019 Heinrich Schuchardt <xypron.glpk@gmx.de>
+ *
+ * Test the random number generator service.
+ */
+
+#include <efi_selftest.h>
+#include <efi_rng.h>
+
+#define RNG_LEN 9
+
+static struct efi_boot_services *boottime;
+static efi_guid_t efi_rng_guid = EFI_RNG_PROTOCOL_GUID;
+
+/*
+ * Setup unit test.
+ *
+ * @handle:	handle of the loaded image
+ * @systable:	system table
+ * @return:	EFI_ST_SUCCESS for success
+ */
+static int setup(const efi_handle_t handle,
+		 const struct efi_system_table *systable)
+{
+	boottime = systable->boottime;
+	return EFI_ST_SUCCESS;
+}
+
+/*
+ * Execute unit test.
+ *
+ * Retrieve available RNG algorithms.
+ * Retrieve two random values and compare them.
+ *
+ * @return:	EFI_ST_SUCCESS for success
+ */
+static int execute(void)
+{
+	efi_status_t ret;
+	efi_uintn_t size;
+	struct efi_rng_protocol *rng;
+	efi_guid_t *algo_list;
+	u8 rnd1[RNG_LEN] __aligned(4), rnd2[RNG_LEN] __aligned(4);
+	int r;
+
+	/* Get random number generator protocol */
+	ret = boottime->locate_protocol(&efi_rng_guid, NULL, (void **)&rng);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error(
+			"Random number generator protocol not available\n");
+		return EFI_ST_FAILURE;
+	}
+
+	ret = rng->get_info(rng, &size, NULL);
+	if (ret != EFI_BUFFER_TOO_SMALL) {
+		efi_st_error("Could not retrieve alorithm list size\n");
+		return EFI_ST_FAILURE;
+	}
+	if (size < sizeof(efi_guid_t)) {
+		efi_st_error("Empty alorithm list\n");
+		return EFI_ST_FAILURE;
+	}
+
+	ret = boottime->allocate_pool(EFI_LOADER_DATA, size,
+				      (void **)&algo_list);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("Could not allocate pool memory\n");
+		return EFI_ST_FAILURE;
+	}
+
+	ret = rng->get_info(rng, &size, algo_list);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("Could not get info\n");
+		return EFI_ST_FAILURE;
+	}
+	if (size < sizeof(efi_guid_t)) {
+		efi_st_error("Empty alorithm list\n");
+		return EFI_ST_FAILURE;
+	}
+
+	memset(rnd1, 0, RNG_LEN);
+	memset(rnd2, 0, RNG_LEN);
+
+	ret = rng->get_rng(rng, NULL, RNG_LEN - 1, &rnd1[1]);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("Could not get random value\n");
+		return EFI_ST_FAILURE;
+	}
+	ret = rng->get_rng(rng, algo_list, RNG_LEN - 1, &rnd2[1]);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("Could not get random value\n");
+		return EFI_ST_FAILURE;
+	}
+	r = memcmp(rnd1, rnd2, RNG_LEN);
+	if (!r) {
+		efi_st_error("Two equal consecutive random numbers\n");
+		return EFI_ST_FAILURE;
+	}
+
+	ret = boottime->free_pool(algo_list);
+	if (ret != EFI_SUCCESS) {
+		efi_st_error("Could not free pool memory\n");
+		return EFI_ST_FAILURE;
+	}
+
+	return EFI_ST_SUCCESS;
+}
+
+EFI_UNIT_TEST(rng) = {
+	.name = "random number generator",
+	.phase = EFI_EXECUTE_BEFORE_BOOTTIME_EXIT,
+	.setup = setup,
+	.execute = execute,
+};