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>
This commit is contained in:
Matthieu Castet
Ingo Molnar
Родитель
64edc8ed5f
Коммит
5bd5a45266
|
|
@ -65,6 +65,7 @@ extern unsigned long pci_mem_start;
|
|||
|
||||
#define PCIBIOS_MIN_CARDBUS_IO 0x4000
|
||||
|
||||
extern int pcibios_enabled;
|
||||
void pcibios_config_init(void);
|
||||
struct pci_bus *pcibios_scan_root(int bus);
|
||||
|
||||
|
|
|
|||
|
|
@ -69,7 +69,7 @@ jiffies_64 = jiffies;
|
|||
|
||||
PHDRS {
|
||||
text PT_LOAD FLAGS(5); /* R_E */
|
||||
data PT_LOAD FLAGS(7); /* RWE */
|
||||
data PT_LOAD FLAGS(6); /* RW_ */
|
||||
#ifdef CONFIG_X86_64
|
||||
user PT_LOAD FLAGS(5); /* R_E */
|
||||
#ifdef CONFIG_SMP
|
||||
|
|
@ -116,6 +116,10 @@ SECTIONS
|
|||
|
||||
EXCEPTION_TABLE(16) :text = 0x9090
|
||||
|
||||
#if defined(CONFIG_DEBUG_RODATA)
|
||||
/* .text should occupy whole number of pages */
|
||||
. = ALIGN(PAGE_SIZE);
|
||||
#endif
|
||||
X64_ALIGN_DEBUG_RODATA_BEGIN
|
||||
RO_DATA(PAGE_SIZE)
|
||||
X64_ALIGN_DEBUG_RODATA_END
|
||||
|
|
@ -335,7 +339,7 @@ SECTIONS
|
|||
__bss_start = .;
|
||||
*(.bss..page_aligned)
|
||||
*(.bss)
|
||||
. = ALIGN(4);
|
||||
. = ALIGN(PAGE_SIZE);
|
||||
__bss_stop = .;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -364,8 +364,9 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
|
|||
/*
|
||||
* We just marked the kernel text read only above, now that
|
||||
* we are going to free part of that, we need to make that
|
||||
* writeable first.
|
||||
* writeable and non-executable first.
|
||||
*/
|
||||
set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
|
||||
set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
|
||||
|
||||
printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
|
||||
|
|
|
|||
|
|
@ -226,7 +226,7 @@ page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
|
|||
|
||||
static inline int is_kernel_text(unsigned long addr)
|
||||
{
|
||||
if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
|
||||
if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
|
||||
return 1;
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -912,6 +912,23 @@ void set_kernel_text_ro(void)
|
|||
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
|
||||
}
|
||||
|
||||
static void mark_nxdata_nx(void)
|
||||
{
|
||||
/*
|
||||
* When this called, init has already been executed and released,
|
||||
* so everything past _etext sould be NX.
|
||||
*/
|
||||
unsigned long start = PFN_ALIGN(_etext);
|
||||
/*
|
||||
* This comes from is_kernel_text upper limit. Also HPAGE where used:
|
||||
*/
|
||||
unsigned long size = (((unsigned long)__init_end + HPAGE_SIZE) & HPAGE_MASK) - start;
|
||||
|
||||
if (__supported_pte_mask & _PAGE_NX)
|
||||
printk(KERN_INFO "NX-protecting the kernel data: %luk\n", size >> 10);
|
||||
set_pages_nx(virt_to_page(start), size >> PAGE_SHIFT);
|
||||
}
|
||||
|
||||
void mark_rodata_ro(void)
|
||||
{
|
||||
unsigned long start = PFN_ALIGN(_text);
|
||||
|
|
@ -946,6 +963,7 @@ void mark_rodata_ro(void)
|
|||
printk(KERN_INFO "Testing CPA: write protecting again\n");
|
||||
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
|
||||
#endif
|
||||
mark_nxdata_nx();
|
||||
}
|
||||
#endif
|
||||
|
||||
|
|
|
|||
|
|
@ -788,6 +788,7 @@ void mark_rodata_ro(void)
|
|||
unsigned long rodata_start =
|
||||
((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
|
||||
unsigned long end = (unsigned long) &__end_rodata_hpage_align;
|
||||
unsigned long kernel_end = (((unsigned long)&__init_end + HPAGE_SIZE) & HPAGE_MASK);
|
||||
unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
|
||||
unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
|
||||
unsigned long data_start = (unsigned long) &_sdata;
|
||||
|
|
@ -802,7 +803,7 @@ void mark_rodata_ro(void)
|
|||
* The rodata section (but not the kernel text!) should also be
|
||||
* not-executable.
|
||||
*/
|
||||
set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
|
||||
set_memory_nx(rodata_start, (kernel_end - rodata_start) >> PAGE_SHIFT);
|
||||
|
||||
rodata_test();
|
||||
|
||||
|
|
|
|||
|
|
@ -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
|
||||
|
|
|
|||
|
|
@ -9,6 +9,7 @@
|
|||
#include <linux/uaccess.h>
|
||||
#include <asm/pci_x86.h>
|
||||
#include <asm/pci-functions.h>
|
||||
#include <asm/cacheflush.h>
|
||||
|
||||
/* BIOS32 signature: "_32_" */
|
||||
#define BIOS32_SIGNATURE (('_' << 0) + ('3' << 8) + ('2' << 16) + ('_' << 24))
|
||||
|
|
@ -25,6 +26,27 @@
|
|||
#define PCIBIOS_HW_TYPE1_SPEC 0x10
|
||||
#define PCIBIOS_HW_TYPE2_SPEC 0x20
|
||||
|
||||
int pcibios_enabled;
|
||||
|
||||
/* According to the BIOS specification at:
|
||||
* http://members.datafast.net.au/dft0802/specs/bios21.pdf, we could
|
||||
* restrict the x zone to some pages and make it ro. But this may be
|
||||
* broken on some bios, complex to handle with static_protections.
|
||||
* We could make the 0xe0000-0x100000 range rox, but this can break
|
||||
* some ISA mapping.
|
||||
*
|
||||
* So we let's an rw and x hole when pcibios is used. This shouldn't
|
||||
* happen for modern system with mmconfig, and if you don't want it
|
||||
* you could disable pcibios...
|
||||
*/
|
||||
static inline void set_bios_x(void)
|
||||
{
|
||||
pcibios_enabled = 1;
|
||||
set_memory_x(PAGE_OFFSET + BIOS_BEGIN, (BIOS_END - BIOS_BEGIN) >> PAGE_SHIFT);
|
||||
if (__supported_pte_mask & _PAGE_NX)
|
||||
printk(KERN_INFO "PCI : PCI BIOS aera is rw and x. Use pci=nobios if you want it NX.\n");
|
||||
}
|
||||
|
||||
/*
|
||||
* This is the standard structure used to identify the entry point
|
||||
* to the BIOS32 Service Directory, as documented in
|
||||
|
|
@ -332,6 +354,7 @@ static struct pci_raw_ops * __devinit pci_find_bios(void)
|
|||
DBG("PCI: BIOS32 Service Directory entry at 0x%lx\n",
|
||||
bios32_entry);
|
||||
bios32_indirect.address = bios32_entry + PAGE_OFFSET;
|
||||
set_bios_x();
|
||||
if (check_pcibios())
|
||||
return &pci_bios_access;
|
||||
}
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче