From: Mark Rutland mark.rutland@arm.com
mainline inclusion from mainline-v5.6 commit 253d3194c2b58152fe830fd27c2fd83ebc6fe5ee category:bugfix bugzilla:NA CVE:NA
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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@arm.com Cc: Mark Brown broonie@kernel.org Cc: Theodore Ts'o tytso@mit.edu Link: https://lore.kernel.org/r/20200210130015.17664-3-mark.rutland@arm.com Signed-off-by: Theodore Ts'o tytso@mit.edu
Conflicts: drivers/char/random.c include/linux/random.h
Signed-off-by: Chen Jun chenjun102@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- include/linux/random.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/include/linux/random.h b/include/linux/random.h index 37209b3b22ae..efcbf8de6bfb 100644 --- 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>
@@ -142,4 +144,24 @@ static inline bool arch_has_random_seed(void) } #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 */