* [PATCH v5 2/2] m68k: rework BI_VIRT_RNG_SEED as BI_RNG_SEED
2022-09-27 13:08 [PATCH v5 1/2] m68k: process bootinfo records before saving them Jason A. Donenfeld
@ 2022-09-27 13:08 ` Jason A. Donenfeld
2022-09-28 20:19 ` Geert Uytterhoeven
2022-09-28 20:19 ` [PATCH v5 1/2] m68k: process bootinfo records before saving them Geert Uytterhoeven
1 sibling, 1 reply; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-09-27 13:08 UTC (permalink / raw)
To: Geert Uytterhoeven, linux-m68k, linux-kernel
Cc: Jason A. Donenfeld, Laurent Vivier
This is useful on !virt platforms for kexec, so change things from
BI_VIRT_RNG_SEED to be BI_RNG_SEED, and simply remove BI_VIRT_RNG_SEED
because it only ever lasted one release, and nothing is broken by not
having it. At the same time, keep a comment noting that it's been
removed, so that ID isn't reused. In addition, we previously documented
2-byte alignment, but 4-byte alignment is actually necessary, so update
that comment.
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Laurent Vivier <laurent@vivier.eu>
Fixes: a1ee38ab1a75 ("m68k: virt: Use RNG seed from bootinfo block")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
arch/m68k/include/uapi/asm/bootinfo-virt.h | 9 ++-------
arch/m68k/include/uapi/asm/bootinfo.h | 8 +++++++-
arch/m68k/kernel/setup_mm.c | 12 ++++++++++++
arch/m68k/virt/config.c | 11 -----------
4 files changed, 21 insertions(+), 19 deletions(-)
diff --git a/arch/m68k/include/uapi/asm/bootinfo-virt.h b/arch/m68k/include/uapi/asm/bootinfo-virt.h
index b091ee9b06e0..7dbcd7bec103 100644
--- a/arch/m68k/include/uapi/asm/bootinfo-virt.h
+++ b/arch/m68k/include/uapi/asm/bootinfo-virt.h
@@ -13,13 +13,8 @@
#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
+/* No longer used -- replaced with BI_RNG_SEED -- but don't reuse this index:
+ * #define BI_VIRT_RNG_SEED 0x8006 */
#define VIRT_BOOTI_VERSION MK_BI_VERSION(2, 0)
diff --git a/arch/m68k/include/uapi/asm/bootinfo.h b/arch/m68k/include/uapi/asm/bootinfo.h
index 95ecf3ae4c49..6ce7644ab3d6 100644
--- a/arch/m68k/include/uapi/asm/bootinfo.h
+++ b/arch/m68k/include/uapi/asm/bootinfo.h
@@ -64,7 +64,13 @@ struct mem_info {
/* (struct mem_info) */
#define BI_COMMAND_LINE 0x0007 /* kernel command line parameters */
/* (string) */
-
+/*
+ * A random seed used to initialize the RNG. Record format:
+ *
+ * - length [ 2 bytes, 16-bit big endian ]
+ * - seed data [ `length` bytes, padded to preserve 4-byte struct alignment ]
+ */
+#define BI_RNG_SEED 0x0008
/*
* Linux/m68k Architectures (BI_MACHTYPE)
diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
index 7e7ef67cff8b..e45cc9923703 100644
--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/nvram.h>
#include <linux/initrd.h>
+#include <linux/random.h>
#include <asm/bootinfo.h>
#include <asm/byteorder.h>
@@ -151,6 +152,17 @@ static void __init m68k_parse_bootinfo(const struct bi_record *record)
sizeof(m68k_command_line));
break;
+ case BI_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:
if (MACH_IS_AMIGA)
unknown = amiga_parse_bootinfo(record);
diff --git a/arch/m68k/virt/config.c b/arch/m68k/virt/config.c
index 4ab22946ff68..632ba200ad42 100644
--- a/arch/m68k/virt/config.c
+++ b/arch/m68k/virt/config.c
@@ -2,7 +2,6 @@
#include <linux/reboot.h>
#include <linux/serial_core.h>
-#include <linux/random.h>
#include <clocksource/timer-goldfish.h>
#include <asm/bootinfo.h>
@@ -93,16 +92,6 @@ 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;
--
2.37.3
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v5 1/2] m68k: process bootinfo records before saving them
2022-09-27 13:08 [PATCH v5 1/2] m68k: process bootinfo records before saving them Jason A. Donenfeld
2022-09-27 13:08 ` [PATCH v5 2/2] m68k: rework BI_VIRT_RNG_SEED as BI_RNG_SEED Jason A. Donenfeld
@ 2022-09-28 20:19 ` Geert Uytterhoeven
1 sibling, 0 replies; 4+ messages in thread
From: Geert Uytterhoeven @ 2022-09-28 20:19 UTC (permalink / raw)
To: Jason A. Donenfeld; +Cc: linux-m68k, linux-kernel
On Tue, Sep 27, 2022 at 3:09 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> The RNG seed boot record is memzeroed after processing, in order to
> preserve forward secrecy. By saving the bootinfo for procfs prior to
> that, forward secrecy is violated, since it becomes possible to recover
> past states. So, save the bootinfo block only after first processing
> them.
>
> Fixes: a1ee38ab1a75 ("m68k: virt: Use RNG seed from bootinfo block")
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
i.e. will queue in the m68k for-v6.1 branch.
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
^ permalink raw reply [flat|nested] 4+ messages in thread