| Message ID | 20230603183159.3566505-1-linus.walleij@linaro.org |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v2] mtd: otp: Put factory OTP/NVRAM into the entropy pool | expand |
On Sat, Jun 3, 2023 at 8:32 PM Linus Walleij <linus.walleij@linaro.org> wrote: > > 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: Jason A. Donenfeld <Jason@zx2c4.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > ChangeLog v1->v2: > - Drop the conditional to return as many bytes as requested > to add the OTP to the entropy pool: it doesn't matter > whatsoever in this case. > - Collected Jason's ACK. > > This is similar to the patch I made to add MMC/SD-card serial > numbers to randomness, just with raw NOR flash. > --- > drivers/mtd/mtdcore.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > index 60670b2f70b9..d03412a82549 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, size); My suggestion was to use `err` here, not `size`. But it's not like it really matters much either way.
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 60670b2f70b9..d03412a82549 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, size); + kfree(otp); + nvmem = mtd_otp_nvmem_register(mtd, "factory-otp", size, mtd_nvmem_fact_otp_reg_read); if (IS_ERR(nvmem)) {