This is a note to let you know that I've just added the patch titled
random: add arch_get_random_*long_early()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
random-add-arch_get_random_-long_early.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Jun 17 08:58:56 AM CEST 2022
From: Mark Rutland <mark.rutland@xxxxxxx>
Date: Mon, 10 Feb 2020 13:00:13 +0000
Subject: random: add arch_get_random_*long_early()
From: Mark Rutland <mark.rutland@xxxxxxx>
commit 253d3194c2b58152fe830fd27c2fd83ebc6fe5ee upstream.
Some architectures (e.g. arm64) can have heterogeneous CPUs, and the
boot CPU may be able to provide entropy while secondary CPUs cannot. On
such systems, arch_get_random_long() and arch_get_random_seed_long()
will fail unless support for RNG instructions has been detected on all
CPUs. This prevents the boot CPU from being able to provide
(potentially) trusted entropy when seeding the primary CRNG.
To make it possible to seed the primary CRNG from the boot CPU without
adversely affecting the runtime versions of arch_get_random_long() and
arch_get_random_seed_long(), this patch adds new early versions of the
functions used when initializing the primary CRNG.
Default implementations are provided atop of the existing
arch_get_random_long() and arch_get_random_seed_long() so that only
architectures with such constraints need to provide the new helpers.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Link: https://lore.kernel.org/r/20200210130015.17664-3-mark.rutland@xxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/random.c | 20 +++++++++++++++++++-
include/linux/random.h | 22 ++++++++++++++++++++++
2 files changed, 41 insertions(+), 1 deletion(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -801,6 +801,24 @@ static bool crng_init_try_arch(struct cr
return arch_init;
}
+static bool __init crng_init_try_arch_early(struct crng_state *crng)
+{
+ int i;
+ bool arch_init = true;
+ unsigned long rv;
+
+ for (i = 4; i < 16; i++) {
+ if (!arch_get_random_seed_long_early(&rv) &&
+ !arch_get_random_long_early(&rv)) {
+ rv = random_get_entropy();
+ arch_init = false;
+ }
+ crng->state[i] ^= rv;
+ }
+
+ return arch_init;
+}
+
static void __maybe_unused crng_initialize_secondary(struct crng_state *crng)
{
memcpy(&crng->state[0], "expand 32-byte k", 16);
@@ -813,7 +831,7 @@ static void __init crng_initialize_prima
{
memcpy(&crng->state[0], "expand 32-byte k", 16);
_extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0);
- if (crng_init_try_arch(crng) && trust_cpu) {
+ if (crng_init_try_arch_early(crng) && trust_cpu) {
invalidate_batched_entropy();
numa_crng_init();
crng_init = 2;
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -7,6 +7,8 @@
#ifndef _LINUX_RANDOM_H
#define _LINUX_RANDOM_H
+#include <linux/bug.h>
+#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/once.h>
@@ -136,4 +138,24 @@ static inline bool __must_check arch_get
}
#endif
+/*
+ * Called from the boot CPU during startup; not valid to call once
+ * secondary CPUs are up and preemption is possible.
+ */
+#ifndef arch_get_random_seed_long_early
+static inline bool __init arch_get_random_seed_long_early(unsigned long *v)
+{
+ WARN_ON(system_state != SYSTEM_BOOTING);
+ return arch_get_random_seed_long(v);
+}
+#endif
+
+#ifndef arch_get_random_long_early
+static inline bool __init arch_get_random_long_early(unsigned long *v)
+{
+ WARN_ON(system_state != SYSTEM_BOOTING);
+ return arch_get_random_long(v);
+}
+#endif
+
#endif /* _LINUX_RANDOM_H */
Patches currently in stable-queue which might be from mark.rutland@xxxxxxx are
queue-4.19/random-split-primary-secondary-crng-init-paths.patch
queue-4.19/random-add-arch_get_random_-long_early.patch
queue-4.19/random-avoid-warnings-for-config_numa-builds.patch
