* [PATCH v4 2/3] m68k: rework BI_VIRT_RNG_SEED as BI_RNG_SEED
2022-09-26 11:37 [PATCH v4 1/3] m68k: process bootinfo records before saving them Jason A. Donenfeld
@ 2022-09-26 11:37 ` Jason A. Donenfeld
2022-09-26 11:37 ` [PATCH v4 3/3] m68k: generate new RNG seed on reboot Jason A. Donenfeld
1 sibling, 0 replies; 5+ messages in thread
From: Jason A. Donenfeld @ 2022-09-26 11:37 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] 5+ messages in thread* [PATCH v4 3/3] m68k: generate new RNG seed on reboot
2022-09-26 11:37 [PATCH v4 1/3] m68k: process bootinfo records before saving them Jason A. Donenfeld
2022-09-26 11:37 ` [PATCH v4 2/3] m68k: rework BI_VIRT_RNG_SEED as BI_RNG_SEED Jason A. Donenfeld
@ 2022-09-26 11:37 ` Jason A. Donenfeld
2022-09-26 13:13 ` Jason A. Donenfeld
1 sibling, 1 reply; 5+ messages in thread
From: Jason A. Donenfeld @ 2022-09-26 11:37 UTC (permalink / raw)
To: Geert Uytterhoeven, linux-m68k, linux-kernel; +Cc: Jason A. Donenfeld
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/include/asm/bootinfo.h | 2 ++
arch/m68k/kernel/process.c | 11 +++++++++++
arch/m68k/kernel/setup_mm.c | 2 ++
3 files changed, 15 insertions(+)
diff --git a/arch/m68k/include/asm/bootinfo.h b/arch/m68k/include/asm/bootinfo.h
index 81c91af8ec6c..71103530839a 100644
--- a/arch/m68k/include/asm/bootinfo.h
+++ b/arch/m68k/include/asm/bootinfo.h
@@ -28,6 +28,8 @@ void process_uboot_commandline(char *commandp, int size);
static inline void process_uboot_commandline(char *commandp, int size) {}
#endif
+extern const struct bi_record *rng_seed_record;
+
#endif /* __ASSEMBLY__ */
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 2cb4a61bcfac..c2b20d5d51e2 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -29,6 +29,7 @@
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
+#include <linux/random.h>
#include <linux/rcupdate.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
@@ -36,6 +37,7 @@
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>
+#include <asm/bootinfo.h>
asmlinkage void ret_from_fork(void);
@@ -51,8 +53,17 @@ void arch_cpu_idle(void)
#endif
}
+const struct bi_record *rng_seed_record;
+
void machine_restart(char * __unused)
{
+ if (rng_seed_record && rng_seed_record->size > sizeof(*rng_seed_record) + 2) {
+ u16 len = rounddown_pow_of_two(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);
+ }
+
if (mach_reset)
mach_reset();
for (;;);
diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
index e45cc9923703..eacf734bea0e 100644
--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c
@@ -160,6 +160,8 @@ static void __init m68k_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;
}
--
2.37.3
^ permalink raw reply related [flat|nested] 5+ messages in thread