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Message-Id: <8db2d46b0e2c54aa7eaade18e39f68c0d9d09945.1658189199.git.andreyknvl@google.com>
Date: Tue, 19 Jul 2022 02:10:11 +0200
From: andrey.konovalov@...ux.dev
To: Marco Elver <elver@...gle.com>,
Alexander Potapenko <glider@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
kasan-dev@...glegroups.com, Peter Collingbourne <pcc@...gle.com>,
Evgenii Stepanov <eugenis@...gle.com>,
Florian Mayer <fmayer@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm v2 31/33] kasan: support kasan.stacktrace for SW_TAGS
From: Andrey Konovalov <andreyknvl@...gle.com>
Add support for the kasan.stacktrace command-line argument for Software
Tag-Based KASAN.
The following patch adds a command-line argument for selecting the stack
ring size, and, as the stack ring is supported by both the Software and
the Hardware Tag-Based KASAN modes, it is natural that both of them have
support for kasan.stacktrace too.
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
Changes v1->v2:
- This is a new patch.
---
Documentation/dev-tools/kasan.rst | 15 ++++++-----
mm/kasan/hw_tags.c | 39 +---------------------------
mm/kasan/kasan.h | 36 +++++++++++++++++---------
mm/kasan/sw_tags.c | 5 +++-
mm/kasan/tags.c | 43 +++++++++++++++++++++++++++++++
5 files changed, 81 insertions(+), 57 deletions(-)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 1772fd457fed..7bd38c181018 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -111,9 +111,15 @@ parameter can be used to control panic and reporting behaviour:
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
-additional boot parameters that allow disabling KASAN or controlling features:
+Software and Hardware Tag-Based KASAN modes (see the section about various
+modes below) support disabling stack trace collection:
+
+- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
+ traces collection (default: ``on``).
+
+Hardware Tag-Based KASAN mode is intended for use in production as a security
+mitigation. Therefore, it supports additional boot parameters that allow
+disabling KASAN altogether or controlling its features:
- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
@@ -132,9 +138,6 @@ additional boot parameters that allow disabling KASAN or controlling features:
- ``kasan.vmalloc=off`` or ``=on`` disables or enables tagging of vmalloc
allocations (default: ``on``).
-- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
- traces collection (default: ``on``).
-
Error reports
~~~~~~~~~~~~~
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 9ad8eff71b28..b22c4f461cb0 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -38,16 +38,9 @@ enum kasan_arg_vmalloc {
KASAN_ARG_VMALLOC_ON,
};
-enum kasan_arg_stacktrace {
- KASAN_ARG_STACKTRACE_DEFAULT,
- KASAN_ARG_STACKTRACE_OFF,
- KASAN_ARG_STACKTRACE_ON,
-};
-
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;
/*
* Whether KASAN is enabled at all.
@@ -66,9 +59,6 @@ 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);
-
/* kasan=off/on */
static int __init early_kasan_flag(char *arg)
{
@@ -122,23 +112,6 @@ static int __init early_kasan_flag_vmalloc(char *arg)
}
early_param("kasan.vmalloc", early_kasan_flag_vmalloc);
-/* kasan.stacktrace=off/on */
-static int __init early_kasan_flag_stacktrace(char *arg)
-{
- if (!arg)
- return -EINVAL;
-
- if (!strcmp(arg, "off"))
- kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
- else if (!strcmp(arg, "on"))
- kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
- else
- return -EINVAL;
-
- return 0;
-}
-early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
-
static inline const char *kasan_mode_info(void)
{
if (kasan_mode == KASAN_MODE_ASYNC)
@@ -213,17 +186,7 @@ void __init kasan_init_hw_tags(void)
break;
}
- switch (kasan_arg_stacktrace) {
- case KASAN_ARG_STACKTRACE_DEFAULT:
- /* Default is specified by kasan_flag_stacktrace definition. */
- break;
- case KASAN_ARG_STACKTRACE_OFF:
- static_branch_disable(&kasan_flag_stacktrace);
- break;
- case KASAN_ARG_STACKTRACE_ON:
- static_branch_enable(&kasan_flag_stacktrace);
- break;
- }
+ kasan_init_tags();
/* KASAN is now initialized, enable it. */
static_branch_enable(&kasan_flag_enabled);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cfff81139d67..447baf1a7a2e 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -8,13 +8,31 @@
#include <linux/kfence.h>
#include <linux/stackdepot.h>
-#ifdef CONFIG_KASAN_HW_TAGS
+#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
#include <linux/static_key.h>
+
+DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
+
+static inline bool kasan_stack_collection_enabled(void)
+{
+ return static_branch_unlikely(&kasan_flag_stacktrace);
+}
+
+#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
+
+static inline bool kasan_stack_collection_enabled(void)
+{
+ return true;
+}
+
+#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
+
+#ifdef CONFIG_KASAN_HW_TAGS
+
#include "../slab.h"
DECLARE_STATIC_KEY_TRUE(kasan_flag_vmalloc);
-DECLARE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
enum kasan_mode {
KASAN_MODE_SYNC,
@@ -29,11 +47,6 @@ 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);
-}
-
static inline bool kasan_async_fault_possible(void)
{
return kasan_mode == KASAN_MODE_ASYNC || kasan_mode == KASAN_MODE_ASYMM;
@@ -46,11 +59,6 @@ static inline bool kasan_sync_fault_possible(void)
#else /* CONFIG_KASAN_HW_TAGS */
-static inline bool kasan_stack_collection_enabled(void)
-{
- return true;
-}
-
static inline bool kasan_async_fault_possible(void)
{
return false;
@@ -410,6 +418,10 @@ static inline void kasan_enable_tagging(void) { }
#endif /* CONFIG_KASAN_HW_TAGS */
+#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
+void __init kasan_init_tags(void);
+#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
+
#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
void kasan_force_async_fault(void);
diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
index 77f13f391b57..a3afaf2ad1b1 100644
--- a/mm/kasan/sw_tags.c
+++ b/mm/kasan/sw_tags.c
@@ -42,7 +42,10 @@ void __init kasan_init_sw_tags(void)
for_each_possible_cpu(cpu)
per_cpu(prng_state, cpu) = (u32)get_cycles();
- pr_info("KernelAddressSanitizer initialized (sw-tags)\n");
+ kasan_init_tags();
+
+ pr_info("KernelAddressSanitizer initialized (sw-tags, stacktrace=%s)\n",
+ kasan_stack_collection_enabled() ? "on" : "off");
}
/*
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 07828021c1f5..0eb6cf6717db 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -19,11 +19,54 @@
#include "kasan.h"
#include "../slab.h"
+enum kasan_arg_stacktrace {
+ KASAN_ARG_STACKTRACE_DEFAULT,
+ KASAN_ARG_STACKTRACE_OFF,
+ KASAN_ARG_STACKTRACE_ON,
+};
+
+static enum kasan_arg_stacktrace kasan_arg_stacktrace __initdata;
+
+/* Whether to collect alloc/free stack traces. */
+DEFINE_STATIC_KEY_TRUE(kasan_flag_stacktrace);
+
/* Non-zero, as initial pointer values are 0. */
#define STACK_RING_BUSY_PTR ((void *)1)
struct kasan_stack_ring stack_ring;
+/* kasan.stacktrace=off/on */
+static int __init early_kasan_flag_stacktrace(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (!strcmp(arg, "off"))
+ kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
+ else if (!strcmp(arg, "on"))
+ kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
+
+void __init kasan_init_tags(void)
+{
+ switch (kasan_arg_stacktrace) {
+ case KASAN_ARG_STACKTRACE_DEFAULT:
+ /* Default is specified by kasan_flag_stacktrace definition. */
+ break;
+ case KASAN_ARG_STACKTRACE_OFF:
+ static_branch_disable(&kasan_flag_stacktrace);
+ break;
+ case KASAN_ARG_STACKTRACE_ON:
+ static_branch_enable(&kasan_flag_stacktrace);
+ break;
+ }
+}
+
static void save_stack_info(struct kmem_cache *cache, void *object,
gfp_t gfp_flags, bool is_free)
{
--
2.25.1
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