Re: [PATCH v2 33/37] kasan, arm64: implement HW_TAGS runtime
From: Marco Elver <elver@google.com>
Date: 2020-09-18 12:52:27
Also in:
linux-mm, lkml
[ Sorry for the additional email on this patch; trying to consolidate comments now. ] On Tue, Sep 15, 2020 at 11:16PM +0200, Andrey Konovalov wrote:
Provide implementation of KASAN functions required for the hardware tag-based mode. Those include core functions for memory and pointer tagging (tags_hw.c) and bug reporting (report_tags_hw.c). Also adapt common KASAN code to support the new mode. Signed-off-by: Andrey Konovalov <redacted> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- Change-Id: I8a8689ba098174a4d0ef3f1d008178387c80ee1c --- arch/arm64/include/asm/memory.h | 4 +- arch/arm64/kernel/setup.c | 1 - include/linux/kasan.h | 6 +-- include/linux/mm.h | 2 +- include/linux/page-flags-layout.h | 2 +- mm/kasan/Makefile | 5 ++ mm/kasan/common.c | 14 +++--- mm/kasan/kasan.h | 17 +++++-- mm/kasan/report_tags_hw.c | 47 +++++++++++++++++++ mm/kasan/report_tags_sw.c | 2 +- mm/kasan/shadow.c | 2 +- mm/kasan/tags_hw.c | 78 +++++++++++++++++++++++++++++++ mm/kasan/tags_sw.c | 2 +- 13 files changed, 162 insertions(+), 20 deletions(-) create mode 100644 mm/kasan/report_tags_hw.c create mode 100644 mm/kasan/tags_hw.c
[...]
quoted hunk ↗ jump to hunk
diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 41c7f1105eaa..412a23d1546b 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c@@ -118,7 +118,7 @@ void kasan_free_pages(struct page *page, unsigned int order) */ static inline unsigned int optimal_redzone(unsigned int object_size) { - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) + if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) return 0; return@@ -183,14 +183,14 @@ size_t kasan_metadata_size(struct kmem_cache *cache) struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, const void *object) { - return (void *)object + cache->kasan_info.alloc_meta_offset; + return (void *)reset_tag(object) + cache->kasan_info.alloc_meta_offset; } struct kasan_free_meta *get_free_info(struct kmem_cache *cache, const void *object) { BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32); - return (void *)object + cache->kasan_info.free_meta_offset; + return (void *)reset_tag(object) + cache->kasan_info.free_meta_offset; } void kasan_poison_slab(struct page *page)@@ -272,7 +272,8 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache, alloc_info = get_alloc_info(cache, object); __memset(alloc_info, 0, sizeof(*alloc_info));
Suggested edit below (assuming the line-break wasn't intentional; this should still be within checkpatch.pl's 100 col limit): ------ - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || - IS_ENABLED(CONFIG_KASAN_HW_TAGS)) + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS)) object = set_tag(object, assign_tag(cache, object, true, false));
@@ -343,8 +342,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, redzone_end = round_up((unsigned long)object + cache->object_size, KASAN_GRANULE_SIZE); - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || - IS_ENABLED(CONFIG_KASAN_HW_TAGS)) + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS)) tag = assign_tag(cache, object, false, keep_tag); ------
quoted hunk ↗ jump to hunk
- if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || + IS_ENABLED(CONFIG_KASAN_HW_TAGS)) object = set_tag(object, assign_tag(cache, object, true, false));@@ -342,10 +343,11 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, redzone_end = round_up((unsigned long)object + cache->object_size, KASAN_GRANULE_SIZE); - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || + IS_ENABLED(CONFIG_KASAN_HW_TAGS)) tag = assign_tag(cache, object, false, keep_tag); - /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */ + /* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */ kasan_unpoison_memory(set_tag(object, tag), size); kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start, KASAN_KMALLOC_REDZONE);
[...]
quoted hunk ↗ jump to hunk
diff --git a/mm/kasan/report_tags_hw.c b/mm/kasan/report_tags_hw.c new file mode 100644 index 000000000000..c2f73c46279a --- /dev/null +++ b/mm/kasan/report_tags_hw.c@@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file contains hardware tag-based KASAN specific error reporting code. + * + * Copyright (c) 2020 Google, Inc. + * Author: Andrey Konovalov <andreyknvl@google.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + *
I do not think we put the "This program is ..." preamble in new files anymore. It should be covered by SPDX tag above.
+ */ + +#include <linux/kasan.h> +#include <linux/kernel.h> +#include <linux/memory.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/types.h>
[...]
quoted hunk ↗ jump to hunk
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 4888084ecdfc..ca69726adf8f 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c@@ -111,7 +111,7 @@ void kasan_unpoison_memory(const void *address, size_t size) if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) *shadow = tag; - else + else /* CONFIG_KASAN_GENERIC */ *shadow = size & KASAN_GRANULE_MASK; } }diff --git a/mm/kasan/tags_hw.c b/mm/kasan/tags_hw.c new file mode 100644 index 000000000000..c93d43379e39 --- /dev/null +++ b/mm/kasan/tags_hw.c@@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file contains core hardware tag-based KASAN code. + * + * Copyright (c) 2020 Google, Inc. + * Author: Andrey Konovalov <andreyknvl@google.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + *
I do not think we put the "This program is ..." preamble in new files anymore. It should be covered by SPDX tag above.
+ */
+
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "kasan.h"
+
+void kasan_init_tags(void)
+{
+ init_tags(KASAN_TAG_MAX);
+}
+
+void *kasan_reset_tag(const void *addr)
+{
+ return reset_tag(addr);
+}
+
To help readability, would this edit be ok?
------
void kasan_poison_memory(const void *address, size_t size, u8 value)
{
- set_mem_tag_range(reset_tag(address),
- round_up(size, KASAN_GRANULE_SIZE), value);
+ set_mem_tag_range(reset_tag(address), round_up(size, KASAN_GRANULE_SIZE), value);
}
void kasan_unpoison_memory(const void *address, size_t size)
{
- set_mem_tag_range(reset_tag(address),
- round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
+ set_mem_tag_range(reset_tag(address), round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
}
------
+void kasan_poison_memory(const void *address, size_t size, u8 value)
+{
+ set_mem_tag_range(reset_tag(address),
+ round_up(size, KASAN_GRANULE_SIZE), value);
+}
+
+void kasan_unpoison_memory(const void *address, size_t size)
+{
+ set_mem_tag_range(reset_tag(address),
+ round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
+}
+
+u8 random_tag(void)
+{
+ return get_random_tag();
+}
+
+bool check_invalid_free(void *addr)
+{
+ u8 ptr_tag = get_tag(addr);
+ u8 mem_tag = get_mem_tag(addr);
+Why not just: ------ - if (shadow_byte == KASAN_TAG_INVALID) - return true; - if (tag != KASAN_TAG_KERNEL && tag != shadow_byte) - return true; - return false; + return shadow_byte == KASAN_TAG_INVALID || + (tag != KASAN_TAG_KERNEL && tag != shadow_byte); } ------
+ if (mem_tag == KASAN_TAG_INVALID) + return true; + if (ptr_tag != KASAN_TAG_KERNEL && ptr_tag != mem_tag) + return true; + return false; +} +
Thanks, -- Marco _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel