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authorJinbum Park <jinb.park7@gmail.com>2017-12-12 01:43:57 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2018-01-21 15:32:20 +0000
commita8e53c151fe7ac52a1c13a6ace0c9e8e0f61260c (patch)
treebdd795b97c9311d45e626e5b90814afcd78567a0 /arch/arm/Kconfig.debug
parentd02ca6d76ba7f089706db555ee19f3775bc42740 (diff)
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.debug27
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