| Message ID | 20220817094618.67063-1-andrea.righi@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: head: rely on CONFIG_RANDOM_TRUST_CPU | expand |
On Wed, Aug 17, 2022 at 11:46:18AM +0200, Andrea Righi wrote: > The CONFIG_ARCH_RANDOM .config option has been removed by > commit 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM"). > > Depend on CONFIG_RANDOM_TRUST_CPU to determine whether we can rely on > __arm64_rndr() to initialize the seed for kaslr. > > Fixes: 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM") > -#ifdef CONFIG_ARCH_RANDOM > +#ifdef CONFIG_RANDOM_TRUST_CPU > if (!__early_cpu_has_rndr() || > !__arm64_rndr((unsigned long *)&seed)) > #endif I think the sense here would be more that we should just unconditionally use RNDR if it's present - previously we'd use the result even if we didn't have strong trust in the CPU implementation and I don't see why we'd want to change that.
On Wed, Aug 17, 2022 at 11:46:18AM +0200, Andrea Righi wrote: > The CONFIG_ARCH_RANDOM .config option has been removed by > commit 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM"). > > Depend on CONFIG_RANDOM_TRUST_CPU to determine whether we can rely on > __arm64_rndr() to initialize the seed for kaslr. > > Fixes: 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM") > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > --- > arch/arm64/kernel/pi/kaslr_early.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c > index 6c3855e69395..a1e6f90cb6e2 100644 > --- a/arch/arm64/kernel/pi/kaslr_early.c > +++ b/arch/arm64/kernel/pi/kaslr_early.c > @@ -94,7 +94,7 @@ asmlinkage u64 kaslr_early_init(void *fdt) > > seed = get_kaslr_seed(fdt); > if (!seed) { > -#ifdef CONFIG_ARCH_RANDOM > +#ifdef CONFIG_RANDOM_TRUST_CPU > if (!__early_cpu_has_rndr() || > !__arm64_rndr((unsigned long *)&seed)) > #endif There was another patch sent for this which just removed the guard altogether: https://lore.kernel.org/r/20220721100433.18286-1-lukas.bulwahn@gmail.com I was planning to pick that one up as a fix for -rc2 as Ard was happy with it and it matches what Broonie was after as well. Will
On Wed, Aug 17, 2022 at 02:16:28PM +0100, Mark Brown wrote: > On Wed, Aug 17, 2022 at 11:46:18AM +0200, Andrea Righi wrote: > > The CONFIG_ARCH_RANDOM .config option has been removed by > > commit 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM"). > > > > Depend on CONFIG_RANDOM_TRUST_CPU to determine whether we can rely on > > __arm64_rndr() to initialize the seed for kaslr. > > > > Fixes: 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM") > > > -#ifdef CONFIG_ARCH_RANDOM > > +#ifdef CONFIG_RANDOM_TRUST_CPU > > if (!__early_cpu_has_rndr() || > > !__arm64_rndr((unsigned long *)&seed)) > > #endif > > I think the sense here would be more that we should just unconditionally > use RNDR if it's present - previously we'd use the result even if we > didn't have strong trust in the CPU implementation and I don't see why > we'd want to change that. Makes sense, in that case it'd be better to just remove the guard completely, as mentioned by Will. Thanks, -Andrea
diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c index 6c3855e69395..a1e6f90cb6e2 100644 --- a/arch/arm64/kernel/pi/kaslr_early.c +++ b/arch/arm64/kernel/pi/kaslr_early.c @@ -94,7 +94,7 @@ asmlinkage u64 kaslr_early_init(void *fdt) seed = get_kaslr_seed(fdt); if (!seed) { -#ifdef CONFIG_ARCH_RANDOM +#ifdef CONFIG_RANDOM_TRUST_CPU if (!__early_cpu_has_rndr() || !__arm64_rndr((unsigned long *)&seed)) #endif
The CONFIG_ARCH_RANDOM .config option has been removed by commit 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM"). Depend on CONFIG_RANDOM_TRUST_CPU to determine whether we can rely on __arm64_rndr() to initialize the seed for kaslr. Fixes: 9592eef7c16e ("random: remove CONFIG_ARCH_RANDOM") Signed-off-by: Andrea Righi <andrea.righi@canonical.com> --- arch/arm64/kernel/pi/kaslr_early.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)