From: Woody Lin <woodylin@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Woody Lin <woodylin@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/dev-tools/kasan.rst | 13 +++++--- mm/kasan/hw_tags.c | 43 ---------------------------- mm/kasan/kasan.h | 1 mm/kasan/report.c | 29 ++++++++++++++++-- 4 files changed, 34 insertions(+), 52 deletions(-) --- a/Documentation/dev-tools/kasan.rst~mm-kasan-move-kasanfault-to-mm-kasan-reportc +++ a/Documentation/dev-tools/kasan.rst @@ -181,9 +181,16 @@ By default, KASAN prints a bug report on 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 KAS - ``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 ---------------------- --- a/mm/kasan/hw_tags.c~mm-kasan-move-kasanfault-to-mm-kasan-reportc +++ a/mm/kasan/hw_tags.c @@ -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_stack } 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"); } --- a/mm/kasan/kasan.h~mm-kasan-move-kasanfault-to-mm-kasan-reportc +++ a/mm/kasan/kasan.h @@ -37,7 +37,6 @@ static inline bool kasan_async_mode_enab #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) --- a/mm/kasan/report.c~mm-kasan-move-kasanfault-to-mm-kasan-reportc +++ a/mm/kasan/report.c @@ -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 *fl 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(); } _