[PATCH v3 2/3] m68k: virt: generate new RNG seed on reboot

Jason A. Donenfeld
2022-09-23T17:03:57Z

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>
---
arch/m68k/virt/config.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/m68k/virt/config.c b/arch/m68k/virt/config.c
index 4ab22946ff68..d4627840e35b 100644
--- a/arch/m68k/virt/config.c
+++ b/arch/m68k/virt/config.c
@@ -45,10 +45,18 @@ static void virt_halt(void)
;
}

+static const struct bi_record *rng_seed_record;
+
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 = cpu_to_be16(len);
+ }
+
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 = record;
break;
}
default:
--
2.37.3