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author | matthieu castet <castet.matthieu@free.fr> | 2010-11-16 21:35:16 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2010-11-18 12:32:56 (GMT) |
commit | 84e1c6bb38eb318e456558b610396d9f1afaabf0 (patch) | |
tree | 8051a29e2364446dc1e24bbd5f3b7693d1a454fa /arch/x86/Kconfig.debug | |
parent | 5bd5a452662bc37c54fb6828db1a3faf87e6511c (diff) | |
download | linux-84e1c6bb38eb318e456558b610396d9f1afaabf0.tar.xz |
x86: Add RO/NX protection for loadable kernel modules
This patch is a logical extension of the protection provided by
CONFIG_DEBUG_RODATA to LKMs. The protection is provided by
splitting module_core and module_init into three logical parts
each and setting appropriate page access permissions for each
individual section:
1. Code: RO+X
2. RO data: RO+NX
3. RW data: RW+NX
In order to achieve proper protection, layout_sections() have
been modified to align each of the three parts mentioned above
onto page boundary. Next, the corresponding page access
permissions are set right before successful exit from
load_module(). Further, free_module() and sys_init_module have
been modified to set module_core and module_init as RW+NX right
before calling module_free().
By default, the original section layout and access flags are
preserved. When compiled with CONFIG_DEBUG_SET_MODULE_RONX=y,
the patch will page-align each group of sections to ensure that
each page contains only one type of content and will enforce
RO/NX for each group of pages.
-v1: Initial proof-of-concept patch.
-v2: The patch have been re-written to reduce the number of #ifdefs
and to make it architecture-agnostic. Code formatting has also
been corrected.
-v3: Opportunistic RO/NX protection is now unconditional. Section
page-alignment is enabled when CONFIG_DEBUG_RODATA=y.
-v4: Removed most macros and improved coding style.
-v5: Changed page-alignment and RO/NX section size calculation
-v6: Fixed comments. Restricted RO/NX enforcement to x86 only
-v7: Introduced CONFIG_DEBUG_SET_MODULE_RONX, added
calls to set_all_modules_text_rw() and set_all_modules_text_ro()
in ftrace
-v8: updated for compatibility with linux 2.6.33-rc5
-v9: coding style fixes
-v10: more coding style fixes
-v11: minor adjustments for -tip
-v12: minor adjustments for v2.6.35-rc2-tip
-v13: minor adjustments for v2.6.37-rc1-tip
Signed-off-by: Siarhei Liakh <sliakh.lkml@gmail.com>
Signed-off-by: Xuxian Jiang <jiang@cs.ncsu.edu>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dave Jones <davej@redhat.com>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <4CE2F914.9070106@free.fr>
[ minor cleanliness edits, -v14: build failure fix ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/Kconfig.debug')
-rw-r--r-- | arch/x86/Kconfig.debug | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index b59ee76..45143bb 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -117,6 +117,17 @@ config DEBUG_RODATA_TEST feature as well as for the change_page_attr() infrastructure. If in doubt, say "N" +config DEBUG_SET_MODULE_RONX + bool "Set loadable kernel module data as NX and text as RO" + depends on MODULES + ---help--- + This option helps catch unintended modifications to loadable + kernel module's text and read-only data. It also prevents execution + of module data. Such protection may interfere with run-time code + patching and dynamic kernel tracing - and they might also protect + against certain classes of kernel exploits. + If in doubt, say "N". + config DEBUG_NX_TEST tristate "Testcase for the NX non-executable stack feature" depends on DEBUG_KERNEL && m |