From: Mark Brown <broonie@kernel.org>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Mark Brown <broonie@kernel.org>,
Richard Henderson <richard.henderson@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v8 3/3] arm64: Use v8.5-RNG entropy for KASLR seed
Date: Tue, 7 Jan 2020 18:35:40 +0000 [thread overview]
Message-ID: <20200107183540.54794-4-broonie@kernel.org> (raw)
In-Reply-To: <20200107183540.54794-1-broonie@kernel.org>
When seeding KALSR on a system where we have architecture level random
number generation make use of that entropy, mixing it in with the seed
passed by the bootloader. Since this is run very early in init before
feature detection is complete we open code rather than use archrandom.h.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kernel/kaslr.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 2a11a962e571..fc38c4c25eb6 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -81,7 +81,8 @@ static __init const u8 *kaslr_get_cmdline(void *fdt)
u64 __init kaslr_early_init(u64 dt_phys)
{
void *fdt;
- u64 seed, offset, mask, module_range;
+ u64 seed, offset, mask, module_range, ftr;
+ unsigned long raw;
const u8 *cmdline, *str;
int size;
@@ -120,6 +121,18 @@ u64 __init kaslr_early_init(u64 dt_phys)
return 0;
}
+ /*
+ * Mix in any entropy obtainable architecturally, open coded
+ * since this runs extremely early.
+ */
+ if (IS_ENABLED(CONFIG_ARCH_RANDOM)) {
+ ftr = read_sysreg_s(SYS_ID_AA64ISAR0_EL1);
+ if ((ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf) {
+ if (__arm64_rndr(&raw))
+ seed += raw;
+ }
+ }
+
if (!seed) {
kaslr_status = KASLR_DISABLED_NO_SEED;
return 0;
--
2.20.1
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next prev parent reply other threads:[~2020-01-07 18:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 18:35 [PATCH v8 0/3] ARMv8.5-RNG support Mark Brown
2020-01-07 18:35 ` [PATCH v8 1/3] arm64: Implement archrandom.h for ARMv8.5-RNG Mark Brown
2020-01-08 17:18 ` Mark Rutland
2020-01-07 18:35 ` [PATCH v8 2/3] arm64: random: Add data to pool from setup_arch() Mark Brown
2020-01-08 17:20 ` Mark Rutland
2020-01-08 17:36 ` Mark Brown
2020-01-07 18:35 ` Mark Brown [this message]
2020-01-08 17:21 ` [PATCH v8 3/3] arm64: Use v8.5-RNG entropy for KASLR seed Mark Rutland
2020-01-08 17:38 ` Ard Biesheuvel
2020-01-08 17:44 ` Mark Brown
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