From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 79F536B0025 for ; Fri, 2 Mar 2018 14:45:11 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id y11so1396455wmd.5 for ; Fri, 02 Mar 2018 11:45:11 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id z62sor625899wmb.39.2018.03.02.11.45.10 for (Google Transport Security); Fri, 02 Mar 2018 11:45:10 -0800 (PST) From: Andrey Konovalov Subject: [RFC PATCH 07/14] khwasan: add tag related helper functions Date: Fri, 2 Mar 2018 20:44:26 +0100 Message-Id: <226055ec7c1a01dd8211ca9a8b34c07162be37fa.1520017438.git.andreyknvl@google.com> In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Jonathan Corbet , Catalin Marinas , Will Deacon , Theodore Ts'o , Jan Kara , Christopher Li , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Masahiro Yamada , Michal Marek , Mark Rutland , Ard Biesheuvel , Yury Norov , Nick Desaulniers , Marc Zyngier , Bob Picco , Suzuki K Poulose , Kristina Martsenko , Punit Agrawal , Dave Martin , James Morse , Julien Thierry , Michael Weiser , Steve Capper , Ingo Molnar , Thomas Gleixner , Sandipan Das , Paul Lawrence , David Woodhouse , Kees Cook , Geert Uytterhoeven , Josh Poimboeuf , Arnd Bergmann , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ext4@vger.kernel.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Kees Cook , Jann Horn , Mark Brand Cc: Andrey Konovalov This commit add a few helper functions, that are meant to be used to work with tags embedded in the top byte of kernel pointers: to set, to get or to reset (set to 0xff) the top byte. --- arch/arm64/mm/kasan_init.c | 2 ++ include/linux/kasan.h | 23 ++++++++++++++++++++++ mm/kasan/kasan.h | 23 ++++++++++++++++++++++ mm/kasan/khwasan.c | 39 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 87 insertions(+) diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index d4bceba60010..7fd9aee88069 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -247,6 +247,8 @@ void __init kasan_init(void) memset(kasan_zero_page, KASAN_SHADOW_INIT, PAGE_SIZE); cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); + khwasan_init(); + /* At this point kasan is fully initialized. Enable error messages */ init_task.kasan_depth = 0; pr_info("KernelAddressSanitizer initialized\n"); diff --git a/include/linux/kasan.h b/include/linux/kasan.h index c34f413b0eac..4c656ad5762a 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -155,6 +155,29 @@ static inline void kasan_cache_shutdown(struct kmem_cache *cache) {} #define KASAN_SHADOW_INIT 0xff +void khwasan_init(void); + +void *khwasan_set_tag(const void *addr, u8 tag); +u8 khwasan_get_tag(void *addr); +void *khwasan_reset_tag(void *ptr); + +#else /* CONFIG_KASAN_TAGS */ + +static inline void khwasan_init(void) { } + +static inline void *khwasan_set_tag(const void *addr, u8 tag) +{ + return (void *)addr; +} +static inline u8 khwasan_get_tag(void *addr) +{ + return 0xff; +} +static inline void *khwasan_reset_tag(void *ptr) +{ + return ptr; +} + #endif /* CONFIG_KASAN_TAGS */ #endif /* LINUX_KASAN_H */ diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 2be31754278e..64459efbd44d 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -113,6 +113,29 @@ void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); void kasan_report_invalid_free(void *object, unsigned long ip); +#define KHWASAN_TAG_SHIFT 56 +#define KHWASAN_TAG_MASK ((u64)0xFF << KHWASAN_TAG_SHIFT) + +static inline void *set_tag(const void *addr, u8 tag) +{ + u64 a = (u64)addr; + + a &= ~KHWASAN_TAG_MASK; + a |= ((u64)tag << KHWASAN_TAG_SHIFT); + + return (void *)a; +} + +static inline u8 get_tag(const void *addr) +{ + return (u8)((u64)addr >> KHWASAN_TAG_SHIFT); +} + +static inline void *reset_tag(const void *addr) +{ + return set_tag(addr, 0xFF); +} + #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB) void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache); void quarantine_reduce(void); diff --git a/mm/kasan/khwasan.c b/mm/kasan/khwasan.c index 24d75245e9d0..21a2221e3368 100644 --- a/mm/kasan/khwasan.c +++ b/mm/kasan/khwasan.c @@ -39,6 +39,45 @@ #include "kasan.h" #include "../slab.h" +int khwasan_enabled; + +static DEFINE_PER_CPU(u32, prng_state); + +void khwasan_init(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + per_cpu(prng_state, cpu) = get_random_u32(); + } + WRITE_ONCE(khwasan_enabled, 1); +} + +static inline u8 khwasan_random_tag(void) +{ + u32 state = this_cpu_read(prng_state); + + state = 1664525 * state + 1013904223; + this_cpu_write(prng_state, state); + + return (u8)state; +} + +void *khwasan_set_tag(const void *addr, u8 tag) +{ + return set_tag(addr, tag); +} + +u8 khwasan_get_tag(void *addr) +{ + return get_tag(addr); +} + +void *khwasan_reset_tag(void *addr) +{ + return reset_tag(addr); +} + void kasan_unpoison_shadow(const void *address, size_t size) { } -- 2.16.2.395.g2e18187dfd-goog -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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