Commit 7e606c31 authored by Théo Lebrun's avatar Théo Lebrun Committed by Greg Kroah-Hartman
Browse files

nvmem: rmem: add CRC validation for Mobileye EyeQ5 NVMEM 



Mobileye EyeQ5 has a non-volatile memory region which
gets used to store MAC addresses. Its format includes
a prefix 12-byte header and a suffix 4-byte CRC.

Add an optional ->checksum() callback inside match data;
it runs CRC32 onto the content.

Signed-off-by: default avatarThéo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20241230143035.265518-7-srinivas.kandagatla@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e44f5a61

drivers/nvmem/rmem.c

+82 −0
Original line number Diff line number Diff line
@@ -3,11 +3,13 @@ 
 * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

 */



#include <linux/crc32.h>

#include <linux/io.h>

#include <linux/module.h>

#include <linux/nvmem-provider.h>

#include <linux/of_reserved_mem.h>

#include <linux/platform_device.h>

#include <linux/slab.h>



struct rmem {

	struct device *dev;
@@ -15,6 +17,18 @@ struct rmem { 
	struct reserved_mem *mem;

};



struct rmem_match_data {

	int (*checksum)(struct rmem *priv);

};



struct __packed rmem_eyeq5_header {

	u32 magic;

	u32 version;

	u32 size;

};



#define RMEM_EYEQ5_MAGIC	((u32)0xDABBAD00)



static int rmem_read(void *context, unsigned int offset,

		     void *val, size_t bytes)

{
@@ -47,10 +61,66 @@ static int rmem_read(void *context, unsigned int offset, 
	return 0;

}



static int rmem_eyeq5_checksum(struct rmem *priv)

{

	void *buf __free(kfree) = NULL;

	struct rmem_eyeq5_header header;

	u32 computed_crc, *target_crc;

	size_t data_size;

	int ret;



	ret = rmem_read(priv, 0, &header, sizeof(header));

	if (ret)

		return ret;



	if (header.magic != RMEM_EYEQ5_MAGIC)

		return -EINVAL;



	/*

	 * Avoid massive kmalloc() if header read is invalid;

	 * the check would be done by the next rmem_read() anyway.

	 */

	if (header.size > priv->mem->size)

		return -EINVAL;



	/*

	 *           0 +-------------------+

	 *             | Header (12 bytes) | \

	 *             +-------------------+ |

	 *             |                   | | data to be CRCed

	 *             |        ...        | |

	 *             |                   | /

	 *   data_size +-------------------+

	 *             |   CRC (4 bytes)   |

	 * header.size +-------------------+

	 */



	buf = kmalloc(header.size, GFP_KERNEL);

	if (!buf)

		return -ENOMEM;



	ret = rmem_read(priv, 0, buf, header.size);

	if (ret)

		return ret;



	data_size = header.size - sizeof(*target_crc);

	target_crc = buf + data_size;

	computed_crc = crc32(U32_MAX, buf, data_size) ^ U32_MAX;



	if (computed_crc == *target_crc)

		return 0;



	dev_err(priv->dev,

		"checksum failed: computed %#x, expected %#x, header (%#x, %#x, %#x)\n",

		computed_crc, *target_crc, header.magic, header.version, header.size);

	return -EINVAL;

}



static int rmem_probe(struct platform_device *pdev)

{

	struct nvmem_config config = { };

	struct device *dev = &pdev->dev;

	const struct rmem_match_data *match_data = device_get_match_data(dev);

	struct reserved_mem *mem;

	struct rmem *priv;
@@ -73,10 +143,22 @@ static int rmem_probe(struct platform_device *pdev) 
	config.size = mem->size;

	config.reg_read = rmem_read;



	if (match_data && match_data->checksum) {

		int ret = match_data->checksum(priv);



		if (ret)

			return ret;

	}



	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));

}



static const struct rmem_match_data rmem_eyeq5_match_data = {

	.checksum = rmem_eyeq5_checksum,

};



static const struct of_device_id rmem_match[] = {

	{ .compatible = "mobileye,eyeq5-bootloader-config", .data = &rmem_eyeq5_match_data },

	{ .compatible = "nvmem-rmem", },

	{ /* sentinel */ },

};