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arm64: always enable DEBUG_RODATA and remove the Kconfig option

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Follow the example set by x86 in commit 9ccaf77cf0 ("x86/mm:
Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option"), and
make these protections a fundamental security feature rather than an
opt-in. This also results in a minor code simplification.

For those rare cases when users wish to disable this protection (e.g.
for debugging), this can be done by passing 'rodata=off' on the command
line.

As DEBUG_RODATA_ALIGN is only intended to address a performance/memory
tradeoff, and does not affect correctness, this is left user-selectable.
DEBUG_MODULE_RONX is also left user-selectable until the core code
provides a boot-time option to disable the protection for debugging
use-cases.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2016-08-25 17:23:23 +01:00 committed by Will Deacon
parent e7cd190385
commit 40982fd6b9
3 changed files with 4 additions and 11 deletions
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3
arch/arm64/Kconfig
View file

@ -122,6 +122,9 @@ config ARCH_PHYS_ADDR_T_64BIT
config MMU
def_bool y
config DEBUG_RODATA
def_bool y
config ARM64_PAGE_SHIFT
int
default 16 if ARM64_64K_PAGES

10
arch/arm64/Kconfig.debug
View file

@ -49,16 +49,6 @@ config DEBUG_SET_MODULE_RONX
If in doubt, say Y.
config DEBUG_RODATA
bool "Make kernel text and rodata read-only"
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.
If in doubt, say Y.
config DEBUG_ALIGN_RODATA
depends on DEBUG_RODATA
bool "Align linker sections up to SECTION_SIZE"

2
arch/arm64/kernel/insn.c
View file

@ -96,7 +96,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
page = vmalloc_to_page(addr);
else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
else if (!module)
page = pfn_to_page(PHYS_PFN(__pa(addr)));
else
return addr;