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-rw-r--r--arch/arm/mm/Kconfig36
1 files changed, 19 insertions, 17 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 549f6d3ae..55347662e 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1037,24 +1037,26 @@ config ARCH_SUPPORTS_BIG_ENDIAN
This option specifies the architecture can support big endian
operation.
-config ARM_KERNMEM_PERMS
- bool "Restrict kernel memory permissions"
- depends on MMU
- help
- If this is set, kernel memory other than kernel text (and rodata)
- will be made non-executable. The tradeoff is that each region is
- padded to section-size (1MiB) boundaries (because their permissions
- are different and splitting the 1M pages into 4K ones causes TLB
- performance problems), wasting memory.
-
config DEBUG_RODATA
bool "Make kernel text and rodata read-only"
- depends on ARM_KERNMEM_PERMS
+ depends on MMU && !XIP_KERNEL
+ default y if CPU_V7
+ help
+ If this is set, kernel text and rodata memory will be made
+ read-only, and non-text kernel memory will be made non-executable.
+ The tradeoff is that each region is padded to section-size (1MiB)
+ boundaries (because their permissions are different and splitting
+ the 1M pages into 4K ones causes TLB performance problems), which
+ can waste memory.
+
+config DEBUG_ALIGN_RODATA
+ bool "Make rodata strictly non-executable"
+ depends on DEBUG_RODATA
default y
help
- If this is set, kernel text and rodata will be made read-only. This
- is to help catch accidental or malicious attempts to change the
- kernel's executable code. Additionally splits rodata from kernel
- text so it can be made explicitly non-executable. This creates
- another section-size padded region, so it can waste more memory
- space while gaining the read-only protections.
+ If this is set, rodata will be made explicitly non-executable. This
+ provides protection on the rare chance that attackers might find and
+ use ROP gadgets that exist in the rodata section. This adds an
+ additional section-aligned split of rodata from kernel text so it
+ can be made explicitly non-executable. This padding may waste memory
+ space to gain the additional protection.