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author | Jinbum Park <jinb.park7@gmail.com> | 2017-12-12 01:43:57 +0100 |
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committer | Russell King <rmk+kernel@armlinux.org.uk> | 2018-01-21 16:32:20 +0100 |
commit | a8e53c151fe7ac52a1c13a6ace0c9e8e0f61260c (patch) | |
tree | bdd795b97c9311d45e626e5b90814afcd78567a0 /arch/arm/Kconfig.debug | |
parent | ARM: 8736/1: mm: dump: make the page table dumping seq_file (diff) | |
download | linux-a8e53c151fe7ac52a1c13a6ace0c9e8e0f61260c.tar.xz linux-a8e53c151fe7ac52a1c13a6ace0c9e8e0f61260c.zip |
ARM: 8737/1: mm: dump: add checking for writable and executable
Page mappings with full RWX permissions are a security risk.
x86, arm64 has an option to walk the page tables
and dump any bad pages.
(1404d6f13e47
("arm64: dump: Add checking for writable and exectuable pages"))
Add a similar implementation for arm.
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/Kconfig.debug')
-rw-r--r-- | arch/arm/Kconfig.debug | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index e7b94dbae78e..78a647080ebc 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -20,6 +20,33 @@ config ARM_PTDUMP_DEBUGFS kernel. If in doubt, say "N" +config DEBUG_WX + bool "Warn on W+X mappings at boot" + select ARM_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. + + Look for a message in dmesg output like this: + + arm/mm: Checked W+X mappings: passed, no W+X pages found. + + or like this, if the check failed: + + arm/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". + # RMK wants arm kernels compiled with frame pointers or stack unwinding. # If you know what you are doing and are willing to live without stack # traces, you can get a slightly smaller kernel by setting this option to |