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da141706ae
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>
93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
menu "Kernel hacking"
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source "lib/Kconfig.debug"
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config FRAME_POINTER
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bool
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default y
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config ARM64_PTDUMP
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bool "Export kernel pagetable layout to userspace via debugfs"
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depends on DEBUG_KERNEL
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select DEBUG_FS
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help
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Say Y here if you want to show the kernel pagetable layout in a
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debugfs file. This information is only useful for kernel developers
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who are working in architecture specific areas of the kernel.
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It is probably not a good idea to enable this feature in a production
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kernel.
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If in doubt, say "N"
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config STRICT_DEVMEM
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bool "Filter access to /dev/mem"
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depends on MMU
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help
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If this option is disabled, you allow userspace (root) access to all
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of memory, including kernel and userspace memory. Accidental
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access to this is obviously disastrous, but specific access can
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be used by people debugging the kernel.
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If this option is switched on, the /dev/mem file only allows
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userspace access to memory mapped peripherals.
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If in doubt, say Y.
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config PID_IN_CONTEXTIDR
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bool "Write the current PID to the CONTEXTIDR register"
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help
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Enabling this option causes the kernel to write the current PID to
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the CONTEXTIDR register, at the expense of some additional
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instructions during context switch. Say Y here only if you are
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planning to use hardware trace tools with this kernel.
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config ARM64_RANDOMIZE_TEXT_OFFSET
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bool "Randomize TEXT_OFFSET at build time"
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help
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Say Y here if you want the image load offset (AKA TEXT_OFFSET)
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of the kernel to be randomized at build-time. When selected,
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this option will cause TEXT_OFFSET to be randomized upon any
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build of the kernel, and the offset will be reflected in the
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text_offset field of the resulting Image. This can be used to
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fuzz-test bootloaders which respect text_offset.
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This option is intended for bootloader and/or kernel testing
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only. Bootloaders must make no assumptions regarding the value
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of TEXT_OFFSET and platforms must not require a specific
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value.
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config DEBUG_SET_MODULE_RONX
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bool "Set loadable kernel module data as NX and text as RO"
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depends on MODULES
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help
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This option helps catch unintended modifications to loadable
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kernel module's text and read-only data. It also prevents execution
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of module data. Such protection may interfere with run-time code
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patching and dynamic kernel tracing - and they might also protect
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against certain classes of kernel exploits.
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If in doubt, say "N".
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config DEBUG_RODATA
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bool "Make kernel text and rodata read-only"
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help
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If this is set, kernel text and rodata will be made read-only. This
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is to help catch accidental or malicious attempts to change the
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kernel's executable code. Additionally splits rodata from kernel
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text so it can be made explicitly non-executable.
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If in doubt, say Y
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config DEBUG_ALIGN_RODATA
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depends on DEBUG_RODATA && !ARM64_64K_PAGES
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bool "Align linker sections up to SECTION_SIZE"
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help
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If this option is enabled, sections that may potentially be marked as
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read only or non-executable will be aligned up to the section size of
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the kernel. This prevents sections from being split into pages and
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avoids a potential TLB penalty. The downside is an increase in
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alignment and potentially wasted space. Turn on this option if
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performance is more important than memory pressure.
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If in doubt, say N
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endmenu
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