Commit c9d1af2b authored by Woody Lin's avatar Woody Lin Committed by Linus Torvalds
Browse files

mm/kasan: move kasan.fault to mm/kasan/report.c 

Move the boot parameter 'kasan.fault' from hw_tags.c to report.c, so it
can support all KASAN modes - generic, and both tag-based.

Link: https://lkml.kernel.org/r/20210713010536.3161822-1-woodylin@google.com


Signed-off-by: default avatarWoody Lin <woodylin@google.com>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f181234a

Documentation/dev-tools/kasan.rst

+8 −5
Original line number Diff line number Diff line
@@ -181,9 +181,16 @@ By default, KASAN prints a bug report only for the first invalid memory access. 
With ``kasan_multi_shot``, KASAN prints a report on every invalid access. This

effectively disables ``panic_on_warn`` for KASAN reports.



Alternatively, independent of ``panic_on_warn`` the ``kasan.fault=`` boot

parameter can be used to control panic and reporting behaviour:



- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN

  report or also panic the kernel (default: ``report``). The panic happens even

  if ``kasan_multi_shot`` is enabled.



Hardware tag-based KASAN mode (see the section about various modes below) is

intended for use in production as a security mitigation. Therefore, it supports

boot parameters that allow disabling KASAN or controlling its features.

additional boot parameters that allow disabling KASAN or controlling features:



- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
@@ -199,10 +206,6 @@ boot parameters that allow disabling KASAN or controlling its features. 
- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack

  traces collection (default: ``on``).



- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN

  report or also panic the kernel (default: ``report``). The panic happens even

  if ``kasan_multi_shot`` is enabled.



Implementation details

----------------------

mm/kasan/hw_tags.c

+0 −43
Original line number Diff line number Diff line
@@ -37,16 +37,9 @@ enum kasan_arg_stacktrace { 
	KASAN_ARG_STACKTRACE_ON,

};



enum kasan_arg_fault {

	KASAN_ARG_FAULT_DEFAULT,

	KASAN_ARG_FAULT_REPORT,

	KASAN_ARG_FAULT_PANIC,

};



static enum kasan_arg kasan_arg __ro_after_init;

static enum kasan_arg_mode kasan_arg_mode __ro_after_init;

static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;

static enum kasan_arg_fault kasan_arg_fault __ro_after_init;



/* Whether KASAN is enabled at all. */

DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
@@ -59,9 +52,6 @@ EXPORT_SYMBOL_GPL(kasan_flag_async); 
/* Whether to collect alloc/free stack traces. */

DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace);



/* Whether to panic or print a report and disable tag checking on fault. */

bool kasan_flag_panic __ro_after_init;



/* kasan=off/on */

static int __init early_kasan_flag(char *arg)

{
@@ -113,23 +103,6 @@ static int __init early_kasan_flag_stacktrace(char *arg) 
}

early_param("kasan.stacktrace", early_kasan_flag_stacktrace);



/* kasan.fault=report/panic */

static int __init early_kasan_fault(char *arg)

{

	if (!arg)

		return -EINVAL;



	if (!strcmp(arg, "report"))

		kasan_arg_fault = KASAN_ARG_FAULT_REPORT;

	else if (!strcmp(arg, "panic"))

		kasan_arg_fault = KASAN_ARG_FAULT_PANIC;

	else

		return -EINVAL;



	return 0;

}

early_param("kasan.fault", early_kasan_fault);



/* kasan_init_hw_tags_cpu() is called for each CPU. */

void kasan_init_hw_tags_cpu(void)

{
@@ -197,22 +170,6 @@ void __init kasan_init_hw_tags(void) 
		break;

	}



	switch (kasan_arg_fault) {

	case KASAN_ARG_FAULT_DEFAULT:

		/*

		 * Default to no panic on report.

		 * Do nothing, kasan_flag_panic keeps its default value.

		 */

		break;

	case KASAN_ARG_FAULT_REPORT:

		/* Do nothing, kasan_flag_panic keeps its default value. */

		break;

	case KASAN_ARG_FAULT_PANIC:

		/* Enable panic on report. */

		kasan_flag_panic = true;

		break;

	}



	pr_info("KernelAddressSanitizer initialized\n");

}

mm/kasan/kasan.h

+0 −1
Original line number Diff line number Diff line
@@ -37,7 +37,6 @@ static inline bool kasan_async_mode_enabled(void) 


#endif



extern bool kasan_flag_panic __ro_after_init;

extern bool kasan_flag_async __ro_after_init;



#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)

mm/kasan/report.c

+26 −3
Original line number Diff line number Diff line
@@ -39,6 +39,31 @@ static unsigned long kasan_flags; 
#define KASAN_BIT_REPORTED	0

#define KASAN_BIT_MULTI_SHOT	1



enum kasan_arg_fault {

	KASAN_ARG_FAULT_DEFAULT,

	KASAN_ARG_FAULT_REPORT,

	KASAN_ARG_FAULT_PANIC,

};



static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT;



/* kasan.fault=report/panic */

static int __init early_kasan_fault(char *arg)

{

	if (!arg)

		return -EINVAL;



	if (!strcmp(arg, "report"))

		kasan_arg_fault = KASAN_ARG_FAULT_REPORT;

	else if (!strcmp(arg, "panic"))

		kasan_arg_fault = KASAN_ARG_FAULT_PANIC;

	else

		return -EINVAL;



	return 0;

}

early_param("kasan.fault", early_kasan_fault);



bool kasan_save_enable_multi_shot(void)

{

	return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
@@ -102,10 +127,8 @@ static void end_report(unsigned long *flags, unsigned long addr) 
		panic_on_warn = 0;

		panic("panic_on_warn set ...\n");

	}

#ifdef CONFIG_KASAN_HW_TAGS

	if (kasan_flag_panic)

	if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC)

		panic("kasan.fault=panic set ...\n");

#endif

	kasan_enable_current();

}