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authorLinus Walleij <[email protected]>2023-06-06 16:29:31 +0200
committerMiquel Raynal <[email protected]>2023-06-09 17:27:16 +0200
commit3b270fac84439cbd036c98e189d17f2bc3c85494 (patch)
tree6fb481a0c389f65bd66745929bb91936028dd446
parent6db02fdfdca0cf39b4d66950451d7f22b72a9031 (diff)
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 <[email protected]> Acked-by: Jason A. Donenfeld <[email protected]> Signed-off-by: Linus Walleij <[email protected]> Signed-off-by: Miquel Raynal <[email protected]> Link: https://lore.kernel.org/linux-mtd/[email protected]
-rw-r--r--drivers/mtd/mtdcore.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 60670b2f70b9..abf4cb58a8ab 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -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)) {