Commit a1ee38ab authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by Geert Uytterhoeven
Browse files

m68k: virt: Use RNG seed from bootinfo block 



Other virt VMs can pass RNG seeds via the "rng-seed" device tree
property or via UEFI, but m68k doesn't have either. Instead it has its
own bootinfo protocol. So this commit adds support for receiving a RNG
seed from it, which will be used at the earliest possible time in boot,
just like device tree.

Reviewed-by: default avatarLaurent Vivier <laurent@vivier.eu>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20220626111509.330159-1-Jason@zx2c4.com


Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 6f08e51c

arch/m68k/include/uapi/asm/bootinfo-virt.h

+8 −0
Original line number Diff line number Diff line
@@ -13,6 +13,14 @@ 
#define BI_VIRT_VIRTIO_BASE	0x8004

#define BI_VIRT_CTRL_BASE	0x8005



/*

 * A random seed used to initialize the RNG. Record format:

 *

 *   - length       [ 2 bytes, 16-bit big endian ]

 *   - seed data    [ `length` bytes, padded to preserve 2-byte alignment ]

 */

#define BI_VIRT_RNG_SEED	0x8006



#define VIRT_BOOTI_VERSION	MK_BI_VERSION(2, 0)



#endif /* _UAPI_ASM_M68K_BOOTINFO_MAC_H */

arch/m68k/virt/config.c

+11 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


#include <linux/reboot.h>

#include <linux/serial_core.h>

#include <linux/random.h>

#include <clocksource/timer-goldfish.h>



#include <asm/bootinfo.h>
@@ -92,6 +93,16 @@ int __init virt_parse_bootinfo(const struct bi_record *record) 
		data += 4;

		virt_bi_data.virtio.irq = be32_to_cpup(data);

		break;

	case BI_VIRT_RNG_SEED: {

		u16 len = be16_to_cpup(data);

		add_bootloader_randomness(data + 2, len);

		/*

		 * Zero the data to preserve forward secrecy, and zero the

		 * length to prevent kexec from using it.

		 */

		memzero_explicit((void *)data, len + 2);

		break;

	}

	default:

		unknown = 1;

		break;