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| author | Zong Li <zong.li@sifive.com> | 2020-06-03 16:03:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-03 20:09:49 -0700 |
| commit | 375d315cbfdb50e1eda099d4d004f7f401285111 (patch) | |
| tree | 2d94b3c7be1f65cbf82c2cc10e92a4dd6b497ca2 /mm/Kconfig.debug | |
| parent | 4fb6eabf1037cfbef90a26412492aeae5580cf0a (diff) | |
| download | linux-375d315cbfdb50e1eda099d4d004f7f401285111.tar.bz2 | |
mm: add DEBUG_WX support
Patch series "Extract DEBUG_WX to shared use".
Some architectures support DEBUG_WX function, it's verbatim from each
others, so extract to mm/Kconfig.debug for shared use.
PPC and ARM ports don't support generic page dumper yet, so we only
refine x86 and arm64 port in this patch series.
For RISC-V port, the DEBUG_WX support depends on other patches which
be merged already:
- RISC-V page table dumper
- Support strict kernel memory permissions for security
This patch (of 4):
Some architectures support DEBUG_WX function, it's verbatim from each
others. Extract to mm/Kconfig.debug for shared use.
[akpm@linux-foundation.org: reword text, per Will Deacon & Zong Li]
Link: http://lkml.kernel.org/r/20200427194245.oxRJKj3fn%25akpm@linux-foundation.org
[zong.li@sifive.com: remove the specific name of arm64]
Link: http://lkml.kernel.org/r/3a6a92ecedc54e1d0fc941398e63d504c2cd5611.1589178399.git.zong.li@sifive.com
[zong.li@sifive.com: add MMU dependency for DEBUG_WX]
Link: http://lkml.kernel.org/r/4a674ac7863ff39ca91847b10e51209771f99416.1589178399.git.zong.li@sifive.com
Suggested-by: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/cover.1587455584.git.zong.li@sifive.com
Link: http://lkml.kernel.org/r/23980cd0f0e5d79e24a92169116407c75bcc650d.1587455584.git.zong.li@sifive.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/Kconfig.debug')
| -rw-r--r-- | mm/Kconfig.debug | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 0271b22e063f..2409f7fc1567 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -118,6 +118,38 @@ config DEBUG_RODATA_TEST ---help--- This option enables a testcase for the setting rodata read-only. +config ARCH_HAS_DEBUG_WX + bool + +config DEBUG_WX + bool "Warn on W+X mappings at boot" + depends on ARCH_HAS_DEBUG_WX + depends on MMU + select 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: + + <arch>/mm: Checked W+X mappings: passed, no W+X pages found. + + or like this, if the check failed: + + <arch>/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 GENERIC_PTDUMP bool |