Re: [patch V4 part 1 21/36] kprobes: Prevent probes in .noinstr.text section

Masami Hiramatsu
2020-05-08T06:30:13Z

On Tue, 05 May 2020 15:16:23 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:

> Instrumentation is forbidden in the .noinstr.text section. Make kprobes
> respect this.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

This looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you!

> ---
> include/linux/module.h | 2 ++
> kernel/kprobes.c | 18 ++++++++++++++++++
> kernel/module.c | 3 +++
> 3 files changed, 23 insertions(+)
>
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -458,6 +458,8 @@ struct module {
> void __percpu *percpu;
> unsigned int percpu_size;
> #endif
> + void *noinstr_text_start;
> + unsigned int noinstr_text_size;
>
> #ifdef CONFIG_TRACEPOINTS
> unsigned int num_tracepoints;
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2229,6 +2229,12 @@ static int __init populate_kprobe_blackl
> /* Symbols in __kprobes_text are blacklisted */
> ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
> (unsigned long)__kprobes_text_end);
> + if (ret)
> + return ret;
> +
> + /* Symbols in noinstr section are blacklisted */
> + ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
> + (unsigned long)__noinstr_text_end);
>
> return ret ? : arch_populate_kprobe_blacklist();
> }
> @@ -2248,6 +2254,12 @@ static void add_module_kprobe_blacklist(
> end = start + mod->kprobes_text_size;
> kprobe_add_area_blacklist(start, end);
> }
> +
> + start = (unsigned long)mod->noinstr_text_start;
> + if (start) {
> + end = start + mod->noinstr_text_size;
> + kprobe_add_area_blacklist(start, end);
> + }
> }
>
> static void remove_module_kprobe_blacklist(struct module *mod)
> @@ -2265,6 +2277,12 @@ static void remove_module_kprobe_blackli
> end = start + mod->kprobes_text_size;
> kprobe_remove_area_blacklist(start, end);
> }
> +
> + start = (unsigned long)mod->noinstr_text_start;
> + if (start) {
> + end = start + mod->noinstr_text_size;
> + kprobe_remove_area_blacklist(start, end);
> + }
> }
>
> /* Module notifier call back, checking kprobes on the module */
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3150,6 +3150,9 @@ static int find_module_sections(struct m
> }
> #endif
>
> + mod->noinstr_text_start = section_objs(info, ".noinstr.text", 1,
> + &mod->noinstr_text_size);
> +
> #ifdef CONFIG_TRACEPOINTS
> mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
> sizeof(*mod->tracepoints_ptrs),
>

--
Masami Hiramatsu <mhiramat@kernel.org>