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BACKPORT: arm64: mm: Mark .rodata as RO

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Currently the .rodata section is actually still executable when DEBUG_RODATA
is enabled. This changes that so the .rodata is actually read only, no execute.
It also adds the .rodata section to the mem_init banner.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
[catalin.marinas@arm.com: added vm_struct vmlinux_rodata in map_kernel()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 31374226
Change-Id: I6fd95beaf814fc91805da12c5329a57ce9008fd7
(cherry picked from commit 2f39b5f91e)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Jeremy Linton
2016-02-19 11:50:32 -06:00
committed by Sami Tolvanen
parent 8fd31d5a2c
commit 1a6c07cf6f
3 changed files with 21 additions and 12 deletions
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6
arch/arm64/kernel/vmlinux.lds.S
View File

@@ -114,14 +114,14 @@ SECTIONS
*(.got) /* Global offset table */
}
ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
_etext = .; /* End of text section */
RO_DATA(PAGE_SIZE)
EXCEPTION_TABLE(8)
RO_DATA(PAGE_SIZE) /* everything from this point to */
EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
NOTES
ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
_etext = .; /* End of text and rodata section */
__init_begin = .;
INIT_TEXT_SECTION(8)

2
arch/arm64/mm/init.c
View File

@@ -376,6 +376,7 @@ void __init mem_init(void)
" vmalloc : 0x%16lx - 0x%16lx (%6ld GB)\n"
" .init : 0x%p" " - 0x%p" " (%6ld KB)\n"
" .text : 0x%p" " - 0x%p" " (%6ld KB)\n"
" .rodata : 0x%p" " - 0x%p" " (%6ld KB)\n"
" .data : 0x%p" " - 0x%p" " (%6ld KB)\n"
#ifdef CONFIG_SPARSEMEM_VMEMMAP
" vmemmap : 0x%16lx - 0x%16lx (%6ld GB maximum)\n"
@@ -391,6 +392,7 @@ void __init mem_init(void)
MLG(VMALLOC_START, VMALLOC_END),
MLK_ROUNDUP(__init_begin, __init_end),
MLK_ROUNDUP(_text, _etext),
MLK_ROUNDUP(__start_rodata, __init_begin),
MLK_ROUNDUP(_sdata, _edata),
#ifdef CONFIG_SPARSEMEM_VMEMMAP
MLG(VMEMMAP_START,

25
arch/arm64/mm/mmu.c
View File

@@ -386,14 +386,14 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
{
unsigned long kernel_start = __pa(_stext);
unsigned long kernel_end = __pa(_etext);
unsigned long kernel_end = __pa(__init_begin);
/*
* Take care not to create a writable alias for the
* read-only text and rodata sections of the kernel image.
*/
/* No overlap with the kernel text */
/* No overlap with the kernel text/rodata */
if (end < kernel_start || start >= kernel_end) {
__create_pgd_mapping(pgd, start, __phys_to_virt(start),
end - start, PAGE_KERNEL,
@@ -402,7 +402,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
}
/*
* This block overlaps the kernel text mapping.
* This block overlaps the kernel text/rodata mapping.
* Map the portion(s) which don't overlap.
*/
if (start < kernel_start)
@@ -417,7 +417,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
early_pgtable_alloc);
/*
* Map the linear alias of the [_stext, _etext) interval as
* Map the linear alias of the [_stext, __init_begin) interval as
* read-only/non-executable. This makes the contents of the
* region accessible to subsystems such as hibernate, but
* protects it from inadvertent modification or execution.
@@ -447,12 +447,18 @@ static void __init map_mem(pgd_t *pgd)
void mark_rodata_ro(void)
{
if (!IS_ENABLED(CONFIG_DEBUG_RODATA))
return;
unsigned long section_size;
section_size = (unsigned long)_etext - (unsigned long)_stext;
create_mapping_late(__pa(_stext), (unsigned long)_stext,
(unsigned long)__init_begin - (unsigned long)_stext,
PAGE_KERNEL_ROX);
section_size, PAGE_KERNEL_ROX);
/*
* mark .rodata as read only. Use __init_begin rather than __end_rodata
* to cover NOTES and EXCEPTION_TABLE.
*/
section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);
}
void fixup_init(void)
@@ -491,9 +497,10 @@ static void __init map_kernel_chunk(pgd_t *pgd, void *va_start, void *va_end,
*/
static void __init map_kernel(pgd_t *pgd)
{
static struct vm_struct vmlinux_text, vmlinux_init, vmlinux_data;
static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
map_kernel_chunk(pgd, _stext, _etext, PAGE_KERNEL_EXEC, &vmlinux_text);
map_kernel_chunk(pgd, __start_rodata, __init_begin, PAGE_KERNEL, &vmlinux_rodata);
map_kernel_chunk(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC,
&vmlinux_init);
map_kernel_chunk(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data);