[PATCH RFC v2 14/21] kasan: add and integrate kasan boot parameters
From: Andrey Konovalov
Date: Thu Oct 22 2020 - 09:20:43 EST
TODO: no meaningful description here yet, please see the cover letter
for this RFC series.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Link: https://linux-review.googlesource.com/id/If7d37003875b2ed3e0935702c8015c223d6416a4
---
mm/kasan/common.c | 92 +++++++++++++-----------
mm/kasan/generic.c | 5 ++
mm/kasan/hw_tags.c | 169 ++++++++++++++++++++++++++++++++++++++++++++-
mm/kasan/kasan.h | 9 +++
mm/kasan/report.c | 14 +++-
mm/kasan/sw_tags.c | 5 ++
6 files changed, 250 insertions(+), 44 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 1a5e6c279a72..cc129ef62ab1 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -129,35 +129,37 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
unsigned int redzone_size;
int redzone_adjust;
- /* Add alloc meta. */
- cache->kasan_info.alloc_meta_offset = *size;
- *size += sizeof(struct kasan_alloc_meta);
-
- /* Add free meta. */
- if (IS_ENABLED(CONFIG_KASAN_GENERIC) &&
- (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
- cache->object_size < sizeof(struct kasan_free_meta))) {
- cache->kasan_info.free_meta_offset = *size;
- *size += sizeof(struct kasan_free_meta);
- }
-
- redzone_size = optimal_redzone(cache->object_size);
- redzone_adjust = redzone_size - (*size - cache->object_size);
- if (redzone_adjust > 0)
- *size += redzone_adjust;
-
- *size = min_t(unsigned int, KMALLOC_MAX_SIZE,
- max(*size, cache->object_size + redzone_size));
+ if (static_branch_unlikely(&kasan_stack)) {
+ /* Add alloc meta. */
+ cache->kasan_info.alloc_meta_offset = *size;
+ *size += sizeof(struct kasan_alloc_meta);
+
+ /* Add free meta. */
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+ (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
+ cache->object_size < sizeof(struct kasan_free_meta))) {
+ cache->kasan_info.free_meta_offset = *size;
+ *size += sizeof(struct kasan_free_meta);
+ }
- /*
- * If the metadata doesn't fit, don't enable KASAN at all.
- */
- if (*size <= cache->kasan_info.alloc_meta_offset ||
- *size <= cache->kasan_info.free_meta_offset) {
- cache->kasan_info.alloc_meta_offset = 0;
- cache->kasan_info.free_meta_offset = 0;
- *size = orig_size;
- return;
+ redzone_size = optimal_redzone(cache->object_size);
+ redzone_adjust = redzone_size - (*size - cache->object_size);
+ if (redzone_adjust > 0)
+ *size += redzone_adjust;
+
+ *size = min_t(unsigned int, KMALLOC_MAX_SIZE,
+ max(*size, cache->object_size + redzone_size));
+
+ /*
+ * If the metadata doesn't fit, don't enable KASAN at all.
+ */
+ if (*size <= cache->kasan_info.alloc_meta_offset ||
+ *size <= cache->kasan_info.free_meta_offset) {
+ cache->kasan_info.alloc_meta_offset = 0;
+ cache->kasan_info.free_meta_offset = 0;
+ *size = orig_size;
+ return;
+ }
}
*flags |= SLAB_KASAN;
@@ -165,10 +167,12 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
size_t kasan_metadata_size(struct kmem_cache *cache)
{
- return (cache->kasan_info.alloc_meta_offset ?
- sizeof(struct kasan_alloc_meta) : 0) +
- (cache->kasan_info.free_meta_offset ?
- sizeof(struct kasan_free_meta) : 0);
+ if (static_branch_unlikely(&kasan_stack))
+ return (cache->kasan_info.alloc_meta_offset ?
+ sizeof(struct kasan_alloc_meta) : 0) +
+ (cache->kasan_info.free_meta_offset ?
+ sizeof(struct kasan_free_meta) : 0);
+ return 0;
}
struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
@@ -270,8 +274,10 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
if (!(cache->flags & SLAB_KASAN))
return (void *)object;
- alloc_meta = kasan_get_alloc_meta(cache, object);
- __memset(alloc_meta, 0, sizeof(*alloc_meta));
+ if (static_branch_unlikely(&kasan_stack)) {
+ alloc_meta = kasan_get_alloc_meta(cache, object);
+ __memset(alloc_meta, 0, sizeof(*alloc_meta));
+ }
if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
object = set_tag(object, assign_tag(cache, object, true, false));
@@ -308,15 +314,19 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE);
kasan_poison_memory(object, rounded_up_size, KASAN_KMALLOC_FREE);
- if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
- unlikely(!(cache->flags & SLAB_KASAN)))
- return false;
+ if (static_branch_unlikely(&kasan_stack)) {
+ if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
+ unlikely(!(cache->flags & SLAB_KASAN)))
+ return false;
+
+ kasan_set_free_info(cache, object, tag);
- kasan_set_free_info(cache, object, tag);
+ quarantine_put(cache, object);
- quarantine_put(cache, object);
+ return IS_ENABLED(CONFIG_KASAN_GENERIC);
+ }
- return IS_ENABLED(CONFIG_KASAN_GENERIC);
+ return false;
}
bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
@@ -355,7 +365,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start,
KASAN_KMALLOC_REDZONE);
- if (cache->flags & SLAB_KASAN)
+ if (static_branch_unlikely(&kasan_stack) && (cache->flags & SLAB_KASAN))
set_alloc_info(cache, (void *)object, flags);
return set_tag(object, tag);
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index d259e4c3aefd..20a1e753e0c5 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -33,6 +33,11 @@
#include "kasan.h"
#include "../slab.h"
+/* See the comments in hw_tags.c */
+DEFINE_STATIC_KEY_TRUE_RO(kasan_enabled);
+EXPORT_SYMBOL(kasan_enabled);
+DEFINE_STATIC_KEY_TRUE_RO(kasan_stack);
+
/*
* All functions below always inlined so compiler could
* perform better optimizations in each of __asan_loadX/__assn_storeX
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 915142da6b57..bccd781011ad 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -8,6 +8,8 @@
#define pr_fmt(fmt) "kasan: " fmt
+#include <linux/init.h>
+#include <linux/jump_label.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memory.h>
@@ -17,10 +19,175 @@
#include "kasan.h"
+enum kasan_arg_mode {
+ KASAN_ARG_MODE_OFF,
+ KASAN_ARG_MODE_PROD,
+ KASAN_ARG_MODE_FULL,
+};
+
+enum kasan_arg_stack {
+ KASAN_ARG_STACK_DEFAULT,
+ KASAN_ARG_STACK_OFF,
+ KASAN_ARG_STACK_ON,
+};
+
+enum kasan_arg_trap {
+ KASAN_ARG_TRAP_DEFAULT,
+ KASAN_ARG_TRAP_ASYNC,
+ KASAN_ARG_TRAP_SYNC,
+};
+
+enum kasan_arg_fault {
+ KASAN_ARG_FAULT_DEFAULT,
+ KASAN_ARG_FAULT_REPORT,
+ KASAN_ARG_FAULT_PANIC,
+};
+
+static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
+static enum kasan_arg_stack kasan_arg_stack __ro_after_init;
+static enum kasan_arg_fault kasan_arg_fault __ro_after_init;
+static enum kasan_arg_trap kasan_arg_trap __ro_after_init;
+
+/* Whether KASAN is enabled at all. */
+DEFINE_STATIC_KEY_FALSE_RO(kasan_enabled);
+EXPORT_SYMBOL(kasan_enabled);
+
+/* Whether to collect alloc/free stack traces. */
+DEFINE_STATIC_KEY_FALSE_RO(kasan_stack);
+
+/* Whether to use synchronous or asynchronous tag checking. */
+static bool kasan_sync __ro_after_init;
+
+/* Whether panic or disable tag checking on fault. */
+bool kasan_panic __ro_after_init;
+
+/* kasan.mode=off/prod/full */
+static int __init early_kasan_mode(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (!strcmp(arg, "off"))
+ kasan_arg_mode = KASAN_ARG_MODE_OFF;
+ else if (!strcmp(arg, "prod"))
+ kasan_arg_mode = KASAN_ARG_MODE_PROD;
+ else if (!strcmp(arg, "full"))
+ kasan_arg_mode = KASAN_ARG_MODE_FULL;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+early_param("kasan.mode", early_kasan_mode);
+
+/* kasan.stack=off/on */
+static int __init early_kasan_stack(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (!strcmp(arg, "off"))
+ kasan_arg_stack = KASAN_ARG_STACK_OFF;
+ else if (!strcmp(arg, "on"))
+ kasan_arg_stack = KASAN_ARG_STACK_ON;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+early_param("kasan.stack", early_kasan_stack);
+
+/* kasan.trap=sync/async */
+static int __init early_kasan_trap(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (!strcmp(arg, "ASYNC"))
+ kasan_arg_trap = KASAN_ARG_TRAP_ASYNC;
+ else if (!strcmp(arg, "sync"))
+ kasan_arg_trap = KASAN_ARG_TRAP_SYNC;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+early_param("kasan.trap", early_kasan_trap);
+
+/* 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);
+
void __init kasan_init_tags(void)
{
- init_tags(KASAN_TAG_MAX);
+ if (!cpu_supports_tags())
+ return;
+
+ /* First, preset values based on the mode. */
+
+ switch (kasan_arg_mode) {
+ case KASAN_ARG_MODE_OFF:
+ return;
+ case KASAN_ARG_MODE_PROD:
+ static_branch_enable(&kasan_enabled);
+ break;
+ case KASAN_ARG_MODE_FULL:
+ static_branch_enable(&kasan_enabled);
+ static_branch_enable(&kasan_stack);
+ kasan_sync = true;
+ break;
+ }
+
+ /* Now, optionally override the presets. */
+ switch (kasan_arg_stack) {
+ case KASAN_ARG_STACK_OFF:
+ static_branch_disable(&kasan_stack);
+ break;
+ case KASAN_ARG_STACK_ON:
+ static_branch_enable(&kasan_stack);
+ break;
+ default:
+ break;
+ }
+
+ switch (kasan_arg_trap) {
+ case KASAN_ARG_TRAP_ASYNC:
+ kasan_sync = false;
+ break;
+ case KASAN_ARG_TRAP_SYNC:
+ kasan_sync = true;
+ break;
+ default:
+ break;
+ }
+
+ switch (kasan_arg_fault) {
+ case KASAN_ARG_FAULT_REPORT:
+ kasan_panic = false;
+ break;
+ case KASAN_ARG_FAULT_PANIC:
+ kasan_panic = true;
+ break;
+ default:
+ break;
+ }
+
+ /* TODO: choose between sync and async based on kasan_sync. */
+ init_tags(KASAN_TAG_MAX);
pr_info("KernelAddressSanitizer initialized\n");
}
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index f7ae0c23f023..00b47bc753aa 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -2,9 +2,18 @@
#ifndef __MM_KASAN_KASAN_H
#define __MM_KASAN_KASAN_H
+#include <linux/jump_label.h>
#include <linux/kasan.h>
#include <linux/stackdepot.h>
+#ifdef CONFIG_KASAN_HW_TAGS
+DECLARE_STATIC_KEY_FALSE(kasan_stack);
+#else
+DECLARE_STATIC_KEY_TRUE(kasan_stack);
+#endif
+
+extern bool kasan_panic __ro_after_init;
+
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
#define KASAN_GRANULE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
#else
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index dee5350b459c..426dd1962d3c 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -97,6 +97,10 @@ static void end_report(unsigned long *flags)
panic_on_warn = 0;
panic("panic_on_warn set ...\n");
}
+#ifdef CONFIG_KASAN_HW_TAGS
+ if (kasan_panic)
+ panic("kasan.fault=panic set ...\n");
+#endif
kasan_enable_current();
}
@@ -159,8 +163,8 @@ static void describe_object_addr(struct kmem_cache *cache, void *object,
(void *)(object_addr + cache->object_size));
}
-static void describe_object(struct kmem_cache *cache, void *object,
- const void *addr, u8 tag)
+static void describe_object_stacks(struct kmem_cache *cache, void *object,
+ const void *addr, u8 tag)
{
struct kasan_alloc_meta *alloc_meta = kasan_get_alloc_meta(cache, object);
@@ -188,7 +192,13 @@ static void describe_object(struct kmem_cache *cache, void *object,
}
#endif
}
+}
+static void describe_object(struct kmem_cache *cache, void *object,
+ const void *addr, u8 tag)
+{
+ if (static_branch_unlikely(&kasan_stack))
+ describe_object_stacks(cache, object, addr, tag);
describe_object_addr(cache, object, addr);
}
diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
index 4db41f274702..b6d185adf2c5 100644
--- a/mm/kasan/sw_tags.c
+++ b/mm/kasan/sw_tags.c
@@ -33,6 +33,11 @@
#include "kasan.h"
#include "../slab.h"
+/* See the comments in hw_tags.c */
+DEFINE_STATIC_KEY_TRUE_RO(kasan_enabled);
+EXPORT_SYMBOL(kasan_enabled);
+DEFINE_STATIC_KEY_TRUE_RO(kasan_stack);
+
static DEFINE_PER_CPU(u32, prng_state);
void __init kasan_init_tags(void)
--
2.29.0.rc1.297.gfa9743e501-goog