diff options
| author | Matthieu Castet <castet.matthieu@free.fr> | 2010-11-16 16:31:26 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-11-18 06:52:04 -0500 |
| commit | 5bd5a452662bc37c54fb6828db1a3faf87e6511c (patch) | |
| tree | bf9aa794fc6d69315b01c17f00ba619cf20191c3 /arch/x86/mm/init.c | |
| parent | 64edc8ed5ffae999d8d413ba006850e9e34166cb (diff) | |
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/init.c')
| -rw-r--r-- | arch/x86/mm/init.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index c0e28a13de7d..947f42abe820 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c | |||
| @@ -364,8 +364,9 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end) | |||
| 364 | /* | 364 | /* |
| 365 | * We just marked the kernel text read only above, now that | 365 | * We just marked the kernel text read only above, now that |
| 366 | * we are going to free part of that, we need to make that | 366 | * we are going to free part of that, we need to make that |
| 367 | * writeable first. | 367 | * writeable and non-executable first. |
| 368 | */ | 368 | */ |
| 369 | set_memory_nx(begin, (end - begin) >> PAGE_SHIFT); | ||
| 369 | set_memory_rw(begin, (end - begin) >> PAGE_SHIFT); | 370 | set_memory_rw(begin, (end - begin) >> PAGE_SHIFT); |
| 370 | 371 | ||
| 371 | printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10); | 372 | printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10); |