[PATCH] arm: ftrace: work with CONFIG_DEBUG_SET_MODULE_RONX

[Kees Cook]

On Wed, Apr 2, 2014 at 3:10 PM, Rabin Vincent <rabin at rab.in> wrote:
> Make ftrace work with CONFIG_DEBUG_SET_MODULE_RONX by making module text
> writable around the place where ftrace does its work, like it is done on
> x86 in the patch which introduced CONFIG_DEBUG_SET_MODULE_RONX,
> 84e1c6bb38eb ("x86: Add RO/NX protection for loadable kernel modules").
>
> Signed-off-by: Rabin Vincent <rabin at rab.in>

This works for me as well. Thanks!

Tested-by: Kees Cook <keescook at chromium.org>

-Kees

> ---
>  arch/arm/kernel/ftrace.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
> index 34e5664..70ce654 100644
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -14,6 +14,7 @@
>
>  #include <linux/ftrace.h>
>  #include <linux/uaccess.h>
> +#include <linux/module.h>
>
>  #include <asm/cacheflush.h>
>  #include <asm/opcodes.h>
> @@ -63,6 +64,18 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
>  }
>  #endif
>
> +int ftrace_arch_code_modify_prepare(void)
> +{
> +       set_all_modules_text_rw();
> +       return 0;
> +}
> +
> +int ftrace_arch_code_modify_post_process(void)
> +{
> +       set_all_modules_text_ro();
> +       return 0;
> +}
> +
>  static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
>  {
>         return arm_gen_branch_link(pc, addr);
> --
> 1.9.1
>
>
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-- 
Kees Cook
Chrome OS Security