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authorLaura Abbott <lauraa@codeaurora.org>2015-01-21 17:36:06 -0800
committerCatalin Marinas <catalin.marinas@arm.com>2015-01-22 14:54:29 +0000
commitda141706aea52c1a9fbd28cb8d289b78819f5436 (patch)
tree6fb0fb5a11c98030393c5915802c9ec891b6df51 /arch/arm64/Kconfig.debug
parentarm64: use fixmap for text patching (diff)
downloadlinux-dev-da141706aea52c1a9fbd28cb8d289b78819f5436.tar.xz
linux-dev-da141706aea52c1a9fbd28cb8d289b78819f5436.zip
arm64: add better page protections to arm64
Add page protections for arm64 similar to those in arm. This is for security reasons to prevent certain classes of exploits. The current method: - Map all memory as either RWX or RW. We round to the nearest section to avoid creating page tables before everything is mapped - Once everything is mapped, if either end of the RWX section should not be X, we split the PMD and remap as necessary - When initmem is to be freed, we change the permissions back to RW (using stop machine if necessary to flush the TLB) - If CONFIG_DEBUG_RODATA is set, the read only sections are set read only. Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Tested-by: Kees Cook <keescook@chromium.org> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Laura Abbott <lauraa@codeaurora.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig.debug')
-rw-r--r--arch/arm64/Kconfig.debug23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 5fdd6dce8061..4a8741073c90 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -66,4 +66,27 @@ config DEBUG_SET_MODULE_RONX
against certain classes of kernel exploits.
If in doubt, say "N".
+config DEBUG_RODATA
+ bool "Make kernel text and rodata read-only"
+ 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.
+
+ If in doubt, say Y
+
+config DEBUG_ALIGN_RODATA
+ depends on DEBUG_RODATA && !ARM64_64K_PAGES
+ bool "Align linker sections up to SECTION_SIZE"
+ help
+ If this option is enabled, sections that may potentially be marked as
+ read only or non-executable will be aligned up to the section size of
+ the kernel. This prevents sections from being split into pages and
+ avoids a potential TLB penalty. The downside is an increase in
+ alignment and potentially wasted space. Turn on this option if
+ performance is more important than memory pressure.
+
+ If in doubt, say N
+
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