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| author | Laura Abbott <labbott@redhat.com> | 2016-10-27 09:27:34 -0700 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-07 18:15:04 +0000 |
| commit | 1404d6f13e47c42f155e3c6a611b1bf4dd35dde9 (patch) | |
| tree | f6bf9d56920d2c3d7346cd925781b071075c810b /arch/arm64/Kconfig.debug | |
| parent | cfd69e9551a1b1d20a7ba030a0990aa370817f54 (diff) | |
| download | linux-1404d6f13e47c42f155e3c6a611b1bf4dd35dde9.tar.gz linux-1404d6f13e47c42f155e3c6a611b1bf4dd35dde9.tar.xz | |
arm64: dump: Add checking for writable and exectuable pages
Page mappings with full RWX permissions are a security risk. x86
has an option to walk the page tables and dump any bad pages.
(See e1a58320a38d ("x86/mm: Warn on W^X mappings")). Add a similar
implementation for arm64.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[catalin.marinas@arm.com: folded fix for KASan out of bounds from Mark Rutland]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig.debug')
| -rw-r--r-- | arch/arm64/Kconfig.debug | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 21a5b7409641..d1ebd46872fd 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -42,6 +42,35 @@ config ARM64_RANDOMIZE_TEXT_OFFSET of TEXT_OFFSET and platforms must not require a specific value. +config DEBUG_WX + bool "Warn on W+X mappings at boot" + select ARM64_PTDUMP_CORE + ---help--- + Generate a warning if any W+X mappings are found at boot. + + This is useful for discovering cases where the kernel is leaving + W+X mappings after applying NX, as such mappings are a security risk. + This check also includes UXN, which should be set on all kernel + mappings. + + Look for a message in dmesg output like this: + + arm64/mm: Checked W+X mappings: passed, no W+X pages found. + + or like this, if the check failed: + + arm64/mm: Checked W+X mappings: FAILED, <N> W+X pages found. + + Note that even if the check fails, your kernel is possibly + still fine, as W+X mappings are not a security hole in + themselves, what they do is that they make the exploitation + of other unfixed kernel bugs easier. + + There is no runtime or memory usage effect of this option + once the kernel has booted up - it's a one time check. + + If in doubt, say "Y". + config DEBUG_SET_MODULE_RONX bool "Set loadable kernel module data as NX and text as RO" depends on MODULES |