[PATCH 09/11] sandbox: Implement fuzzing engine driver

[Simon Glass]

Hi Andrew,

On Thu, 7 Apr 2022 at 03:41, Andrew Scull <ascull at google.com> wrote:
>
> 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 at google.com>
> ---
>  arch/Kconfig                                  |  2 ++
>  arch/sandbox/dts/test.dts                     |  4 +++
>  drivers/fuzzing_engine/Kconfig                | 11 ++++++
>  drivers/fuzzing_engine/Makefile               |  1 +
>  .../fuzzing_engine/sandbox_fuzzing_engine.c   | 35 +++++++++++++++++++
>  5 files changed, 53 insertions(+)
>  create mode 100644 drivers/fuzzing_engine/sandbox_fuzzing_engine.c
>

Reviewed-by: Simon Glass <sjg at chromium.org>

Thoughts below

> diff --git a/arch/Kconfig b/arch/Kconfig
> index e6191446a3..6320a98db6 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 48ca3e1e47..848329fda5 100644
> --- a/arch/sandbox/dts/test.dts
> +++ b/arch/sandbox/dts/test.dts
> @@ -71,6 +71,10 @@
>                 };
>         };
>
> +       fuzzing-engine {
> +               compatible = "sandbox,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/fuzzing_engine/Kconfig b/drivers/fuzzing_engine/Kconfig
> index f405fc75e8..6311385222 100644
> --- a/drivers/fuzzing_engine/Kconfig
> +++ b/drivers/fuzzing_engine/Kconfig
> @@ -4,3 +4,14 @@ config DM_FUZZING_ENGINE
>         help
>           Enable driver model for fuzzing engine devices. This interface is
>           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/fuzzing_engine/Makefile b/drivers/fuzzing_engine/Makefile
> index acd894999c..073743ba94 100644
> --- a/drivers/fuzzing_engine/Makefile
> +++ b/drivers/fuzzing_engine/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/fuzzing_engine/sandbox_fuzzing_engine.c b/drivers/fuzzing_engine/sandbox_fuzzing_engine.c
> new file mode 100644
> index 0000000000..4d187deaa4
> --- /dev/null
> +++ b/drivers/fuzzing_engine/sandbox_fuzzing_engine.c
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (c) 2022 Google, Inc.
> + * Written by Andrew Scull <ascull at 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[] = {

In the interests of brevity, perhaps sb_fuzz_engine as the prefix, or
sbfuzz_engine?

> +       {
> +               .compatible = "sandbox,sandbox-fuzzing-engine",

Do you need the second 'sandbox-' ?

> +       },
> +       {},
> +};
> +
> +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,
> +};
> --
> 2.35.1.1094.g7c7d902a7c-goog
>

Regards,
Simon