From 551b2bcb7e7a9219f176a5abc56c6d981d8068cf Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 24 Mar 2022 18:11:47 -0700 Subject: kasan: add kasan.vmalloc command line flag Allow disabling vmalloc() tagging for HW_TAGS KASAN via a kasan.vmalloc command line switch. This is a fail-safe switch intended for production systems that enable HW_TAGS KASAN. In case vmalloc() tagging ends up having an issue not detected during testing but that manifests in production, kasan.vmalloc allows to turn vmalloc() tagging off while leaving page_alloc/slab tagging on. Link: https://lkml.kernel.org/r/904f6d4dfa94870cc5fc2660809e093fd0d27c3b.1643047180.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Mark Rutland Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/hw_tags.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- mm/kasan/kasan.h | 6 ++++++ 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 6a3146d1ccc5..fad1887e54c0 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -32,6 +32,12 @@ enum kasan_arg_mode { KASAN_ARG_MODE_ASYMM, }; +enum kasan_arg_vmalloc { + KASAN_ARG_VMALLOC_DEFAULT, + KASAN_ARG_VMALLOC_OFF, + KASAN_ARG_VMALLOC_ON, +}; + enum kasan_arg_stacktrace { KASAN_ARG_STACKTRACE_DEFAULT, KASAN_ARG_STACKTRACE_OFF, @@ -40,6 +46,7 @@ enum kasan_arg_stacktrace { static enum kasan_arg kasan_arg __ro_after_init; static enum kasan_arg_mode kasan_arg_mode __ro_after_init; +static enum kasan_arg_vmalloc kasan_arg_vmalloc __initdata; static enum kasan_arg_stacktrace kasan_arg_stacktrace __initdata; /* @@ -56,6 +63,9 @@ EXPORT_SYMBOL(kasan_flag_enabled); enum kasan_mode kasan_mode __ro_after_init; EXPORT_SYMBOL_GPL(kasan_mode); +/* Whether to enable vmalloc tagging. */ +DEFINE_STATIC_KEY_TRUE(kasan_flag_vmalloc); + /* Whether to collect alloc/free stack traces. */ DEFINE_STATIC_KEY_TRUE(kasan_flag_stacktrace); @@ -95,6 +105,23 @@ static int __init early_kasan_mode(char *arg) } early_param("kasan.mode", early_kasan_mode); +/* kasan.vmalloc=off/on */ +static int __init early_kasan_flag_vmalloc(char *arg) +{ + if (!arg) + return -EINVAL; + + if (!strcmp(arg, "off")) + kasan_arg_vmalloc = KASAN_ARG_VMALLOC_OFF; + else if (!strcmp(arg, "on")) + kasan_arg_vmalloc = KASAN_ARG_VMALLOC_ON; + else + return -EINVAL; + + return 0; +} +early_param("kasan.vmalloc", early_kasan_flag_vmalloc); + /* kasan.stacktrace=off/on */ static int __init early_kasan_flag_stacktrace(char *arg) { @@ -179,6 +206,18 @@ void __init kasan_init_hw_tags(void) break; } + switch (kasan_arg_vmalloc) { + case KASAN_ARG_VMALLOC_DEFAULT: + /* Default is specified by kasan_flag_vmalloc definition. */ + break; + case KASAN_ARG_VMALLOC_OFF: + static_branch_disable(&kasan_flag_vmalloc); + break; + case KASAN_ARG_VMALLOC_ON: + static_branch_enable(&kasan_flag_vmalloc); + break; + } + switch (kasan_arg_stacktrace) { case KASAN_ARG_STACKTRACE_DEFAULT: /* Default is specified by kasan_flag_stacktrace definition. */ @@ -194,8 +233,9 @@ void __init kasan_init_hw_tags(void) /* KASAN is now initialized, enable it. */ static_branch_enable(&kasan_flag_enabled); - pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, stacktrace=%s)\n", + pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, vmalloc=%s, stacktrace=%s)\n", kasan_mode_info(), + kasan_vmalloc_enabled() ? "on" : "off", kasan_stack_collection_enabled() ? "on" : "off"); } @@ -228,6 +268,9 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, u8 tag; unsigned long redzone_start, redzone_size; + if (!kasan_vmalloc_enabled()) + return (void *)start; + if (!is_vmalloc_or_module_addr(start)) return (void *)start; diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index efda13a9ce6a..4d67408e8407 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -12,6 +12,7 @@ #include #include "../slab.h" +DECLARE_STATIC_KEY_TRUE(kasan_flag_vmalloc); DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace); enum kasan_mode { @@ -22,6 +23,11 @@ enum kasan_mode { extern enum kasan_mode kasan_mode __ro_after_init; +static inline bool kasan_vmalloc_enabled(void) +{ + return static_branch_likely(&kasan_flag_vmalloc); +} + static inline bool kasan_stack_collection_enabled(void) { return static_branch_unlikely(&kasan_flag_stacktrace); -- cgit v1.2.3