[PATCH v3 12/13] sandbox: Implement fuzzing engine driver

[Andrew Scull <ascull@google.com>]

Add a fuzzing engine driver for the sandbox to take inputs from
libfuzzer and expose them to the fuzz tests.

Signed-off-by: Andrew Scull <ascull@google.com>
---
 arch/Kconfig                          |  2 ++
 arch/sandbox/dts/test.dts             |  4 +++
 drivers/fuzz/Kconfig                  | 16 +++++++++---
 drivers/fuzz/Makefile                 |  1 +
 drivers/fuzz/sandbox_fuzzing_engine.c | 35 +++++++++++++++++++++++++++
 5 files changed, 54 insertions(+), 4 deletions(-)
 create mode 100644 drivers/fuzz/sandbox_fuzzing_engine.c

diff --git a/arch/Kconfig b/arch/Kconfig
index 12de8a1165..8eaf853e4d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -135,6 +135,7 @@ config SANDBOX
 	select BZIP2
 	select CMD_POWEROFF
 	select DM
+	select DM_FUZZING_ENGINE
 	select DM_GPIO
 	select DM_I2C
 	select DM_KEYBOARD
@@ -170,6 +171,7 @@ config SANDBOX
 	imply CRC32_VERIFY
 	imply FAT_WRITE
 	imply FIRMWARE
+	imply FUZZING_ENGINE_SANDBOX
 	imply HASH_VERIFY
 	imply LZMA
 	imply TEE
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 8f93775ff4..8662017d17 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -89,6 +89,10 @@
 		};
 	};
 
+	fuzzing-engine {
+		compatible = "sandbox,fuzzing-engine";
+	};
+
 	reboot-mode0 {
 		compatible = "reboot-mode-gpio";
 		gpios = <&gpio_c 0 GPIO_ACTIVE_HIGH>, <&gpio_c 1 GPIO_ACTIVE_HIGH>;
diff --git a/drivers/fuzz/Kconfig b/drivers/fuzz/Kconfig
index a03120f63a..6311385222 100644
--- a/drivers/fuzz/Kconfig
+++ b/drivers/fuzz/Kconfig
@@ -3,7 +3,15 @@ config DM_FUZZING_ENGINE
 	depends on DM
 	help
 	  Enable driver model for fuzzing engine devices. This interface is
-	  used to get successive inputs from a fuzzing engine that aims to
-	  explore different code paths in a fuzz test. The fuzzing engine may
-	  be instrumenting the execution in order to more effectively generate
-	  inputs that explore different code paths.
+	  used to get fuzzing inputs from a fuzzing engine.
+
+if DM_FUZZING_ENGINE
+
+config FUZZING_ENGINE_SANDBOX
+	bool "Sanbox fuzzing engine"
+	depends on SANDBOX
+	default y
+	help
+	  Enable fuzzing engine for sandbox.
+
+endif
diff --git a/drivers/fuzz/Makefile b/drivers/fuzz/Makefile
index acd894999c..073743ba94 100644
--- a/drivers/fuzz/Makefile
+++ b/drivers/fuzz/Makefile
@@ -5,3 +5,4 @@
 #
 
 obj-$(CONFIG_DM_FUZZING_ENGINE) += fuzzing_engine-uclass.o
+obj-$(CONFIG_FUZZING_ENGINE_SANDBOX) += sandbox_fuzzing_engine.o
diff --git a/drivers/fuzz/sandbox_fuzzing_engine.c b/drivers/fuzz/sandbox_fuzzing_engine.c
new file mode 100644
index 0000000000..ebb938e5ba
--- /dev/null
+++ b/drivers/fuzz/sandbox_fuzzing_engine.c
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2022 Google, Inc.
+ * Written by Andrew Scull <ascull@google.com>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fuzzing_engine.h>
+#include <asm/fuzzing_engine.h>
+
+static int get_input(struct udevice *dev,
+		     const uint8_t **data,
+		     size_t *size)
+{
+	return sandbox_fuzzing_engine_get_input(data, size);
+}
+
+static const struct dm_fuzzing_engine_ops sandbox_fuzzing_engine_ops = {
+	.get_input = get_input,
+};
+
+static const struct udevice_id sandbox_fuzzing_engine_match[] = {
+	{
+		.compatible = "sandbox,fuzzing-engine",
+	},
+	{},
+};
+
+U_BOOT_DRIVER(sandbox_fuzzing_engine) = {
+	.name = "sandbox-fuzzing-engine",
+	.id = UCLASS_FUZZING_ENGINE,
+	.of_match = sandbox_fuzzing_engine_match,
+	.ops = &sandbox_fuzzing_engine_ops,
+};
-- 
2.36.1.124.g0e6072fb45-goog