Commit 3b270fac authored by Linus Walleij's avatar Linus Walleij Committed by Miquel Raynal
Browse files

mtd: otp: Put factory OTP/NVRAM into the entropy pool 



The factory OTP, if supported, contains factory-programmed
information such as typically the serial number or production
week for the chip.

As this is device-unique information, submit it into the
system entropy pool.

This does not count as improvement of the entropy as such
but in practice it makes it a bit more random to mix in these
numbers.

Cc: Michael Walle <michael@walle.cc>
Acked-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230606142931.3721374-1-linus.walleij@linaro.org
parent 6db02fdf

drivers/mtd/mtdcore.c

+19 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/idr.h>

#include <linux/backing-dev.h>

#include <linux/gfp.h>

#include <linux/random.h>

#include <linux/slab.h>

#include <linux/reboot.h>

#include <linux/leds.h>
@@ -966,6 +967,24 @@ static int mtd_otp_nvmem_add(struct mtd_info *mtd) 
		}



		if (size > 0) {

			/*

			 * The factory OTP contains thing such as a unique serial

			 * number and is small, so let's read it out and put it

			 * into the entropy pool.

			 */

			void *otp;



			otp = kmalloc(size, GFP_KERNEL);

			if (!otp)

				return -ENOMEM;

			err = mtd_nvmem_fact_otp_reg_read(mtd, 0, otp, size);

			if (err < 0) {

				kfree(otp);

				return err;

			}

			add_device_randomness(otp, err);

			kfree(otp);



			nvmem = mtd_otp_nvmem_register(mtd, "factory-otp", size,

						       mtd_nvmem_fact_otp_reg_read);

			if (IS_ERR(nvmem)) {