0b7d76327b
Increase rng-seed size to make Linux happy and initialize rng pool instantly.
Linux 5.19+ requires 32 bytes of entropy to initialize random pool, but u-boot
currently provides only 8 bytes.
Boot with 8 byte rng-seed (Linux 6.11):
# dmesg | grep crng
[ 12.089286] random: crng init done
Boot with 32 byte rng-seed (Linux 6.11):
# dmesg | grep crng
[ 0.000000] random: crng init done
Link: https://lore.kernel.org/u-boot/20241016100203.629713-1-alexthreed@gmail.com/
Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
136 lines
4.7 KiB
Diff
136 lines
4.7 KiB
Diff
From: Alex Shumsky <alexthreed@gmail.com>
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To: u-boot@lists.denx.de
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Cc: Alex Shumsky <alexthreed@gmail.com>,
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Dragan Simic <dsimic@manjaro.org>, Marek Vasut <marex@denx.de>,
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Ben Wolsieffer <benwolsieffer@gmail.com>,
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Caleb Connolly <caleb.connolly@linaro.org>,
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Chris Morgan <macromorgan@hotmail.com>,
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Devarsh Thakkar <devarsht@ti.com>,
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Jagan Teki <jagan@amarulasolutions.com>,
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Janne Grunau <j@jannau.net>,
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Jerome Forissier <jerome.forissier@linaro.org>,
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Jiaxun Yang <jiaxun.yang@flygoat.com>,
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Jonas Karlman <jonas@kwiboo.se>,
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Joshua Watt <jpewhacker@gmail.com>,
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Kever Yang <kever.yang@rock-chips.com>,
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Mattijs Korpershoek <mkorpershoek@baylibre.com>,
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Neal Gompa <neal@gompa.dev>,
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Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
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Philipp Tomsich <philipp.tomsich@vrull.eu>,
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Quentin Schulz <quentin.schulz@cherry.de>,
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Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
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Simon Glass <sjg@chromium.org>, Stefan Roese <sr@denx.de>,
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Tim Harvey <tharvey@gateworks.com>, Tom Rini <trini@konsulko.com>
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Subject: [PATCH v6] rockchip: board: Increase rng-seed size to make it sufficient for modern Linux
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Date: Wed, 16 Oct 2024 13:02:03 +0300 [thread overview]
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Message-ID: <20241016100203.629713-1-alexthreed@gmail.com> (raw)
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Increase rng-seed size to make Linux happy and initialize rng pool instantly.
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Linux 5.19+ requires 32 bytes of entropy to initialize random pool, but u-boot
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currently provides only 8 bytes.
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Linux 5.18 and probably some versions before it used to require 64 bytes.
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Bump min value to 64 bytes to be on a safe side.
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Boot with 8 byte rng-seed (Linux 6.11):
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# dmesg | grep crng
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[ 12.089286] random: crng init done
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Boot with 32 byte rng-seed (Linux 6.11):
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# dmesg | grep crng
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[ 0.000000] random: crng init done
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Linux source references:
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c?h=v5.19#n551
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c?h=v5.18#n236
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Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
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Fixes: d2048bafae40 ("rockchip: board: Add board_rng_seed() for all Rockchip devices")
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Reviewed-by: Dragan Simic <dsimic@manjaro.org>
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Reviewed-by: Marek Vasut <marex@denx.de>
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---
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Changes in v6:
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- fix wording in docs and debug message
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Changes in v5:
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- add docs
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Changes in v4:
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- fix typos and code style
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Changes in v3:
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- reword warning
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- increase default rng_seed_size to support older linux as well
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- reword commit message
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Changes in v2:
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- add env config knob rng_seed_size
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- add warning for small rng_seed_size
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- 12-character commit SHA in Fixes
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arch/arm/mach-rockchip/board.c | 11 ++++++++++-
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common/Kconfig | 3 +++
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doc/usage/environment.rst | 5 +++++
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include/fdt_support.h | 3 ++-
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4 files changed, 20 insertions(+), 2 deletions(-)
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--- a/arch/arm/mach-rockchip/board.c
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+++ b/arch/arm/mach-rockchip/board.c
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@@ -480,9 +480,18 @@ __weak int misc_init_r(void)
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__weak int board_rng_seed(struct abuf *buf)
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{
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struct udevice *dev;
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- size_t len = 0x8;
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+ ulong len = env_get_ulong("rng_seed_size", 10, 64);
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u64 *data;
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+ if (len < 64) {
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+ /*
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+ * rng_seed_size should be at least 32 bytes for Linux 5.19+,
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+ * or 64 for older Linux kernel versions
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+ */
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+ log_warning("Value for rng_seed_size (%lu) too low, Linux kernel RNG may fail to initialize early\n",
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+ len);
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+ }
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+
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data = malloc(len);
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if (!data) {
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printf("Out of memory\n");
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--- a/common/Kconfig
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+++ b/common/Kconfig
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@@ -927,6 +927,9 @@ config BOARD_RNG_SEED
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new seed for use on subsequent boots, and whether or not the
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kernel should account any entropy from the given seed.
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+ Default seed size (64 bytes) can be overridden by a decimal
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+ environment variable rng_seed_size.
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+
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endmenu
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menu "Update support"
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--- a/doc/usage/environment.rst
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+++ b/doc/usage/environment.rst
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@@ -323,6 +323,11 @@ netretry
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Useful on scripts which control the retry operation
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themselves.
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+rng_seed_size
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+ Size of random value added to device-tree node /chosen/rng-seed.
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+ This variable is given as a decimal number.
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+ If unset, 64 bytes is used as the default.
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+
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silent_linux
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If set then Linux will be told to boot silently, by
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adding 'console=' to its command line. If "yes" it will be
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--- a/include/fdt_support.h
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+++ b/include/fdt_support.h
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@@ -202,7 +202,8 @@ int ft_board_setup(void *blob, struct bd
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*
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* This function is called if CONFIG_BOARD_RNG_SEED is set, and must
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* be provided by the board. It should return, via @buf, some suitable
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- * seed value to pass to the kernel.
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+ * seed value to pass to the kernel. Seed size could be set in a decimal
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+ * environment variable rng_seed_size and it defaults to 64 bytes.
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*
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* @param buf A struct abuf for returning the seed and its size.
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* @return 0 if ok, negative on error.
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