diff options
| author | Matthieu Castet <castet.matthieu@free.fr> | 2010-11-16 22:31:26 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-11-18 12:52:04 +0100 |
| commit | 5bd5a452662bc37c54fb6828db1a3faf87e6511c (patch) | |
| tree | bf9aa794fc6d69315b01c17f00ba619cf20191c3 /arch/x86/mm/pageattr.c | |
| parent | 64edc8ed5ffae999d8d413ba006850e9e34166cb (diff) | |
| download | lwn-5bd5a452662bc37c54fb6828db1a3faf87e6511c.tar.gz lwn-5bd5a452662bc37c54fb6828db1a3faf87e6511c.zip | |
x86: Add NX protection for kernel data
This patch expands functionality of CONFIG_DEBUG_RODATA to set main
(static) kernel data area as NX.
The following steps are taken to achieve this:
1. Linker script is adjusted so .text always starts and ends on a page bound
2. Linker script is adjusted so .rodata always start and end on a page boundary
3. NX is set for all pages from _etext through _end in mark_rodata_ro.
4. free_init_pages() sets released memory NX in arch/x86/mm/init.c
5. bios rom is set to x when pcibios is used.
The results of patch application may be observed in the diff of kernel page
table dumps:
pcibios:
-- data_nx_pt_before.txt 2009-10-13 07:48:59.000000000 -0400
++ data_nx_pt_after.txt 2009-10-13 07:26:46.000000000 -0400
0x00000000-0xc0000000 3G pmd
---[ Kernel Mapping ]---
-0xc0000000-0xc0100000 1M RW GLB x pte
+0xc0000000-0xc00a0000 640K RW GLB NX pte
+0xc00a0000-0xc0100000 384K RW GLB x pte
-0xc0100000-0xc03d7000 2908K ro GLB x pte
+0xc0100000-0xc0318000 2144K ro GLB x pte
+0xc0318000-0xc03d7000 764K ro GLB NX pte
-0xc03d7000-0xc0600000 2212K RW GLB x pte
+0xc03d7000-0xc0600000 2212K RW GLB NX pte
0xc0600000-0xf7a00000 884M RW PSE GLB NX pmd
0xf7a00000-0xf7bfe000 2040K RW GLB NX pte
0xf7bfe000-0xf7c00000 8K pte
No pcibios:
-- data_nx_pt_before.txt 2009-10-13 07:48:59.000000000 -0400
++ data_nx_pt_after.txt 2009-10-13 07:26:46.000000000 -0400
0x00000000-0xc0000000 3G pmd
---[ Kernel Mapping ]---
-0xc0000000-0xc0100000 1M RW GLB x pte
+0xc0000000-0xc0100000 1M RW GLB NX pte
-0xc0100000-0xc03d7000 2908K ro GLB x pte
+0xc0100000-0xc0318000 2144K ro GLB x pte
+0xc0318000-0xc03d7000 764K ro GLB NX pte
-0xc03d7000-0xc0600000 2212K RW GLB x pte
+0xc03d7000-0xc0600000 2212K RW GLB NX pte
0xc0600000-0xf7a00000 884M RW PSE GLB NX pmd
0xf7a00000-0xf7bfe000 2040K RW GLB NX pte
0xf7bfe000-0xf7c00000 8K pte
The patch has been originally developed for Linux 2.6.34-rc2 x86 by
Siarhei Liakh <sliakh.lkml@gmail.com> and Xuxian Jiang <jiang@cs.ncsu.edu>.
-v1: initial patch for 2.6.30
-v2: patch for 2.6.31-rc7
-v3: moved all code into arch/x86, adjusted credits
-v4: fixed ifdef, removed credits from CREDITS
-v5: fixed an address calculation bug in mark_nxdata_nx()
-v6: added acked-by and PT dump diff to commit log
-v7: minor adjustments for -tip
-v8: rework with the merge of "Set first MB as RW+NX"
Signed-off-by: Siarhei Liakh <sliakh.lkml@gmail.com>
Signed-off-by: Xuxian Jiang <jiang@cs.ncsu.edu>
Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: James Morris <jmorris@namei.org>
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: <4CE2F82E.60601@free.fr>
[ minor cleanliness edits ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/pageattr.c')
| -rw-r--r-- | arch/x86/mm/pageattr.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 6f2a6b6deb6b..8b830ca14ac4 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -13,6 +13,7 @@ #include <linux/pfn.h> #include <linux/percpu.h> #include <linux/gfp.h> +#include <linux/pci.h> #include <asm/e820.h> #include <asm/processor.h> @@ -261,8 +262,10 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address, * The BIOS area between 640k and 1Mb needs to be executable for * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support. */ - if (within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT)) +#ifdef CONFIG_PCI_BIOS + if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT)) pgprot_val(forbidden) |= _PAGE_NX; +#endif /* * The kernel text needs to be executable for obvious reasons |