diff options
| author | Stephen Smalley <sds@tycho.nsa.gov> | 2015-10-05 12:55:20 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-06 11:11:48 +0200 |
| commit | e1a58320a38dfa72be48a0f1a3a92273663ba6db (patch) | |
| tree | 1ff867a83c601546e0910c009c96f4e1c1cd43b6 /arch/x86/mm/init_32.c | |
| parent | 38a413cbc2b2834683b21823d964bc2d2f0abb82 (diff) | |
x86/mm: Warn on W^X mappings
Warn on any residual W+X mappings after setting NX
if DEBUG_WX is enabled. Introduce a separate
X86_PTDUMP_CORE config that enables the code for
dumping the page tables without enabling the debugfs
interface, so that DEBUG_WX can be enabled without
exposing the debugfs interface. Switch EFI_PGT_DUMP
to using X86_PTDUMP_CORE so that it also does not require
enabling the debugfs interface.
On success it prints this to the kernel log:
x86/mm: Checked W+X mappings: passed, no W+X pages found.
On failure it prints a warning and a count of the failed pages:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 1 at arch/x86/mm/dump_pagetables.c:226 note_page+0x610/0x7b0()
x86/mm: Found insecure W+X mapping at address ffffffff81755000/__stop___ex_table+0xfa8/0xabfa8
[...]
Call Trace:
[<ffffffff81380a5f>] dump_stack+0x44/0x55
[<ffffffff8109d3f2>] warn_slowpath_common+0x82/0xc0
[<ffffffff8109d48c>] warn_slowpath_fmt+0x5c/0x80
[<ffffffff8106cfc9>] ? note_page+0x5c9/0x7b0
[<ffffffff8106d010>] note_page+0x610/0x7b0
[<ffffffff8106d409>] ptdump_walk_pgd_level_core+0x259/0x3c0
[<ffffffff8106d5a7>] ptdump_walk_pgd_level_checkwx+0x17/0x20
[<ffffffff81063905>] mark_rodata_ro+0xf5/0x100
[<ffffffff817415a0>] ? rest_init+0x80/0x80
[<ffffffff817415bd>] kernel_init+0x1d/0xe0
[<ffffffff8174cd1f>] ret_from_fork+0x3f/0x70
[<ffffffff817415a0>] ? rest_init+0x80/0x80
---[ end trace a1f23a1e42a2ac76 ]---
x86/mm: Checked W+X mappings: FAILED, 171 W+X pages found.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1444064120-11450-1-git-send-email-sds@tycho.nsa.gov
[ Improved the Kconfig help text and made the new option default-y
if CONFIG_DEBUG_RODATA=y, because it already found buggy mappings,
so we really want people to have this on by default. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm/init_32.c')
| -rw-r--r-- | arch/x86/mm/init_32.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 7562f42914b4..cb4ef3de61f9 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -957,6 +957,8 @@ void mark_rodata_ro(void) set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT); #endif mark_nxdata_nx(); + if (__supported_pte_mask & _PAGE_NX) + debug_checkwx(); } #endif |