Messages in this thread Patch in this message | | | From | Geert Uytterhoeven <> | Date | Fri, 23 Sep 2022 13:30:06 +0200 | Subject | Re: [PATCH 2/2] m68k: virt: generate new RNG seed on reboot |
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Hi Jason,
On Wed, Sep 21, 2022 at 8:52 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote: > Rather than rebooting into a system with no entropy, regenerate the RNG > seed before rebooting, so that the new system has a fresh seed. > > Fixes: a1ee38ab1a75 ("m68k: virt: Use RNG seed from bootinfo block") > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Thanks for your patch!
> --- a/arch/m68k/virt/config.c > +++ b/arch/m68k/virt/config.c > @@ -45,10 +45,18 @@ static void virt_halt(void) > ; > } > > +static struct bi_record *rng_seed_record;
This can be const...
> + > static void virt_reset(void) > { > void __iomem *base = (void __iomem *)virt_bi_data.ctrl.mmio; > > + if (rng_seed_record && rng_seed_record->size > sizeof(*rng_seed_record) + 2) { > + u16 len = rng_seed_record->size - sizeof(*rng_seed_record) - 2; > + get_random_bytes((u8 *)rng_seed_record->data + 2, len); > + *(u16 *)rng_seed_record->data = len;
Wouldn't it be simpler to just use the existing length?
if (rnd_seed_record) { u16 len = be16_to_cpup(data); get_random_bytes((u8 *)rng_seed_record->data + 2, len); }
However, I have my doubts this will actually work. Was this tested? The bootinfo is passed from userspace, usually by reading /proc/bootinfo, and adapting it where needed. So I think you should implement this in kexec-tools instead.
> + } > + > iowrite32be(CMD_RESET, base + VIRT_CTRL_REG_CMD); > local_irq_disable(); > while (1) > @@ -101,6 +109,8 @@ int __init virt_parse_bootinfo(const struct bi_record *record) > * length to prevent kexec from using it. > */ > memzero_explicit((void *)data, len + 2); > + /* Store a reference to be filled in on reboot. */ > + rng_seed_record = (void *)record;
... so this cast can be dropped.
> break; > } > default:
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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