From: keescook@chromium.org (Kees Cook)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3] arm64: mm: Mark .rodata as RO
Date: Fri, 19 Feb 2016 11:05:17 -0800 [thread overview]
Message-ID: <CAGXu5jJi9174OGM_xc2qriRrfajZ4UNgiTCODkhreRck_Q9NAQ@mail.gmail.com> (raw)
In-Reply-To: <1455904232-24053-1-git-send-email-jeremy.linton@arm.com>
On Fri, Feb 19, 2016 at 9:50 AM, Jeremy Linton <jeremy.linton@arm.com> wrote:
> 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>
-Kees
> ---
> arch/arm64/kernel/vmlinux.lds.S | 5 +++--
> arch/arm64/mm/init.c | 4 +++-
> arch/arm64/mm/mmu.c | 17 +++++++++++++----
> 3 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index 8f4fc2c..9208f53 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -114,8 +114,9 @@ SECTIONS
> *(.got) /* Global offset table */
> }
>
> - RO_DATA(PAGE_SIZE)
> - EXCEPTION_TABLE(8)
> + ALIGN_DEBUG_RO_MIN(0)
> + RO_DATA(PAGE_SIZE) /* everything from this point to */
> + EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
> NOTES
>
> ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 5dd0831..41be7db 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -325,6 +325,7 @@ void __init mem_init(void)
> " memory : 0x%16lx - 0x%16lx (%6ld MB)\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_KASAN
> MLG(KASAN_SHADOW_START, KASAN_SHADOW_END),
> @@ -341,7 +342,8 @@ void __init mem_init(void)
> MLM(MODULES_VADDR, MODULES_END),
> MLM(PAGE_OFFSET, (unsigned long)high_memory),
> MLK_ROUNDUP(__init_begin, __init_end),
> - MLK_ROUNDUP(_text, _etext),
> + MLK_ROUNDUP(_text, __start_rodata),
> + MLK_ROUNDUP(__start_rodata, _etext),
> MLK_ROUNDUP(_sdata, _edata));
>
> #undef MLK
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index ab69a99..a18dfd0 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -453,10 +453,18 @@ static void __init map_mem(pgd_t *pgd)
> #ifdef CONFIG_DEBUG_RODATA
> void mark_rodata_ro(void)
> {
> - create_mapping_late(__pa(_stext), (unsigned long)_stext,
> - (unsigned long)_etext - (unsigned long)_stext,
> - PAGE_KERNEL_ROX);
> + unsigned long section_size;
>
> + section_size = (unsigned long)__start_rodata - (unsigned long)_stext;
> + create_mapping_late(__pa(_stext), (unsigned long)_stext,
> + section_size, PAGE_KERNEL_ROX);
> + /*
> + * mark .rodata as read only. Use _etext rather than __end_rodata to
> + * cover NOTES and EXCEPTION_TABLE.
> + */
> + section_size = (unsigned long)_etext - (unsigned long)__start_rodata;
> + create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
> + section_size, PAGE_KERNEL_RO);
> }
> #endif
>
> @@ -486,7 +494,8 @@ static void __init map_kernel_chunk(pgd_t *pgd, void *va_start, void *va_end,
> static void __init map_kernel(pgd_t *pgd)
> {
>
> - map_kernel_chunk(pgd, _stext, _etext, PAGE_KERNEL_EXEC);
> + map_kernel_chunk(pgd, _stext, __start_rodata, PAGE_KERNEL_EXEC);
> + map_kernel_chunk(pgd, __start_rodata, _etext, PAGE_KERNEL);
> map_kernel_chunk(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC);
> map_kernel_chunk(pgd, _data, _end, PAGE_KERNEL);
>
> --
> 2.4.3
>
--
Kees Cook
Chrome OS & Brillo Security
next prev parent reply other threads:[~2016-02-19 19:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 17:50 [PATCH v3] arm64: mm: Mark .rodata as RO Jeremy Linton
2016-02-19 19:05 ` Kees Cook [this message]
2016-02-26 14:44 ` Catalin Marinas
2016-02-26 14:55 ` Mark Rutland
2016-02-26 14:59 ` Jeremy Linton
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