On Mon, May 17, 2021 at 4:49 PM Christophe Leroy
[off-list ref] wrote:
Le 17/05/2021 à 05:28, Jordan Niethe a écrit :
quoted
From: Russell Currey <redacted>
To enable strict module RWX on powerpc, set:
CONFIG_STRICT_MODULE_RWX=y
You should also have CONFIG_STRICT_KERNEL_RWX=y set to have any real
security benefit.
ARCH_HAS_STRICT_MODULE_RWX is set to require ARCH_HAS_STRICT_KERNEL_RWX.
This is due to a quirk in arch/Kconfig and arch/powerpc/Kconfig that
makes STRICT_MODULE_RWX *on by default* in configurations where
STRICT_KERNEL_RWX is *unavailable*.
Since this doesn't make much sense, and module RWX without kernel RWX
doesn't make much sense, having the same dependencies as kernel RWX
works around this problem.
Book32s/32 processors with a hash mmu (i.e. 604 core) can not set memory
^^^^^^
Book32s ==> Book3s
Thanks.
quoted
protection on a page by page basis so do not enable.
It is not exactly that. The problem on 604 is for _exec_ protection.
Right.
Note that on book3s/32, on both 603 and 604 core, it is not possible to write protect kernel pages.
So maybe it would make sense to disable ARCH_HAS_STRICT_MODULE_RWX on CONFIG_PPC_BOOK3S_32
completely, I'm not sure.
Yeah, that does seem like it would make sense to disable it.
quoted
Signed-off-by: Russell Currey <redacted>
[jpn: - predicate on !PPC_BOOK3S_604
- make module_alloc() use PAGE_KERNEL protection]
Signed-off-by: Jordan Niethe <redacted>
Reviewed-by: Christophe Leroy <redacted>
quoted
---
v10: - Predicate on !PPC_BOOK3S_604
- Make module_alloc() use PAGE_KERNEL protection
v11: - Neaten up
v13: Use strict_kernel_rwx_enabled()
v14: Make changes to module_alloc() its own commit
---
arch/powerpc/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index cce0a137b046..cb5d9d862c35 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -140,6 +140,7 @@ config PPC
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !HIBERNATION)
+ select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX && !PPC_BOOK3S_604
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE
select ARCH_HAS_COPY_MC if PPC64