Le 17/05/2021 à 13:01, Michael Ellerman a écrit :
Jordan Niethe <jniet...@gmail.com> writes:
On Mon, May 17, 2021 at 4:37 PM Christophe Leroy
<christophe.le...@csgroup.eu> wrote:
Le 17/05/2021 à 05:28, Jordan Niethe a écrit :
Make module_alloc() use PAGE_KERNEL protections instead of
PAGE_KERNEL_EXEX if Strict Module RWX is enabled.
Signed-off-by: Jordan Niethe <jniet...@gmail.com>
---
v14: - Split out from powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
- Add and use strict_module_rwx_enabled() helper
---
arch/powerpc/include/asm/mmu.h | 5 +++++
arch/powerpc/kernel/module.c | 4 +++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 607168b1aef4..7710bf0cbf8a 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -357,6 +357,11 @@ static inline bool strict_kernel_rwx_enabled(void)
return false;
}
#endif
+
+static inline bool strict_module_rwx_enabled(void)
+{
+ return IS_ENABLED(CONFIG_STRICT_MODULE_RWX) &&
strict_kernel_rwx_enabled();
+}
Looking at arch/Kconfig, I have the feeling that it is possible to select
CONFIG_STRICT_MODULE_RWX
without selecting CONFIG_STRICT_KERNEL_RWX.
In that case, strict_kernel_rwx_enabled() will return false.
Ok, if someone did that currently it would break things, e.g. code
patching. I think it should it be made impossible to
CONFIG_STRICT_MODULE_RWX without CONFIG_STRICT_KERNEL_RWX?
Yeah I don't see any reason to support that combination.
We should be moving to a world where both are on by default, or in fact
are always enabled.
Would it work if we add the following in arch/powerpc/Kconfig ? :
select STRICT_KERNEL_RWX if STRICT_MODULE_RWX
There should be no dependency issue as powerpc only selects ARCH_HAS_STRICT_MODULE_RWX when
ARCH_HAS_STRICT_KERNEL_RWX is also selected.
Christophe
