kernel.git/mm/kasan/init.c, branch linux-5.19.y

kasan: use MAX_PTRS_PER_* for early shadow tables

2021-06-29T17:53:53Z

powerpc has a variable number of PTRS_PER_*, set at runtime based on the MMU that the kernel is booted under. This means the PTRS_PER_* are no longer constants, and therefore breaks the build. Switch to using MAX_PTRS_PER_*, which are constant. Link: https://lkml.kernel.org/r/20210624034050.511391-5-dja@axtens.net Signed-off-by: Daniel Axtens Suggested-by: Christophe Leroy Suggested-by: Balbir Singh Reviewed-by: Christophe Leroy Reviewed-by: Balbir Singh Reviewed-by: Marco Elver Reviewed-by: Andrey Konovalov Cc: Aneesh Kumar K.V Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/kasan/init.c: fix doc warning

2021-06-05T15:58:11Z

Fix gcc W=1 warning: mm/kasan/init.c:228: warning: Function parameter or member 'shadow_start' not described in 'kasan_populate_early_shadow' mm/kasan/init.c:228: warning: Function parameter or member 'shadow_end' not described in 'kasan_populate_early_shadow' Link: https://lkml.kernel.org/r/20210603140700.3045298-1-yukuai3@huawei.com Signed-off-by: Yu Kuai Acked-by: Andrey Ryabinin Cc: Zhang Yi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: fix incorrect arguments passing in kasan_add_zero_shadow

2021-01-24T18:34:52Z

kasan_remove_zero_shadow() shall use original virtual address, start and size, instead of shadow address. Link: https://lkml.kernel.org/r/20210103063847.5963-1-lecopzer@gmail.com Fixes: 0207df4fa1a86 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN") Signed-off-by: Lecopzer Chen Reviewed-by: Andrey Konovalov Cc: Andrey Ryabinin Cc: Dan Williams Cc: Dmitry Vyukov Cc: Alexander Potapenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: fix unaligned address is unhandled in kasan_remove_zero_shadow

2021-01-24T18:34:52Z

During testing kasan_populate_early_shadow and kasan_remove_zero_shadow, if the shadow start and end address in kasan_remove_zero_shadow() is not aligned to PMD_SIZE, the remain unaligned PTE won't be removed. In the test case for kasan_remove_zero_shadow(): shadow_start: 0xffffffb802000000, shadow end: 0xffffffbfbe000000 3-level page table: PUD_SIZE: 0x40000000 PMD_SIZE: 0x200000 PAGE_SIZE: 4K 0xffffffbf80000000 ~ 0xffffffbfbdf80000 will not be removed because in kasan_remove_pud_table(), kasan_pmd_table(*pud) is true but the next address is 0xffffffbfbdf80000 which is not aligned to PUD_SIZE. In the correct condition, this should fallback to the next level kasan_remove_pmd_table() but the condition flow always continue to skip the unaligned part. Fix by correcting the condition when next and addr are neither aligned. Link: https://lkml.kernel.org/r/20210103135621.83129-1-lecopzer@gmail.com Fixes: 0207df4fa1a86 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN") Signed-off-by: Lecopzer Chen Cc: Andrey Ryabinin Cc: Dan Williams Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: YJ Chiang Cc: Andrey Konovalov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arm/kasan: fix the array size of kasan_early_shadow_pte[]

2021-01-13T02:12:54Z

The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to 512 for arm. This means that it only covers the prev Linux pte entries, but not the HWTABLE pte entries for arm. The reason it currently works is that the symbol kasan_early_shadow_page immediately following kasan_early_shadow_pte in memory is page aligned, which makes kasan_early_shadow_pte look like a 4KB size array. But we can't ensure the order is always right with different compiler/linker, or if more bss symbols are introduced. We had a test with QEMU + vexpress：put a 512KB-size symbol with attribute __section(".bss..page_aligned") after kasan_early_shadow_pte, and poisoned it after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. Link: https://lkml.kernel.org/r/20210109044622.8312-1-hailongliiu@yeah.net Signed-off-by: Hailong Liu Signed-off-by: Ziliang Guo Reviewed-by: Linus Walleij Cc: Andrey Ryabinin Cc: Russell King Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Ard Biesheuvel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: define KASAN_MEMORY_PER_SHADOW_PAGE

2020-12-22T20:55:06Z

Define KASAN_MEMORY_PER_SHADOW_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is the same as (KASAN_GRANULE_SIZE * PAGE_SIZE) for software modes that use shadow memory, and use it across KASAN code to simplify it. Link: https://lkml.kernel.org/r/8329391cfe14b5cffd3decf3b5c535b6ce21eef6.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Tested-by: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Vasily Gorbik Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: only build init.c for software modes

2020-12-22T20:55:06Z

This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. The new mode won't be using shadow memory, so only build init.c that contains shadow initialization code for software modes. No functional changes for software modes. Link: https://lkml.kernel.org/r/bae0a6a35b7a9b1a443803c1a55e6e3fecc311c9.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Tested-by: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Vasily Gorbik Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_*

2020-12-22T20:55:06Z

This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. The new mode won't be using shadow memory, but will still use the concept of memory granules. Each memory granule maps to a single metadata entry: 8 bytes per one shadow byte for generic mode, 16 bytes per one shadow byte for software tag-based mode, and 16 bytes per one allocation tag for hardware tag-based mode. Rename KASAN_SHADOW_SCALE_SIZE to KASAN_GRANULE_SIZE, and KASAN_SHADOW_MASK to KASAN_GRANULE_MASK. Also use MASK when used as a mask, otherwise use SIZE. No functional changes. Link: https://lkml.kernel.org/r/939b5754e47f528a6e6a6f28ffc5815d8d128033.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Tested-by: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Vasily Gorbik Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: drop unnecessary GPL text from comment headers

2020-12-22T20:55:06Z

Patch series "kasan: add hardware tag-based mode for arm64", v11. This patchset adds a new hardware tag-based mode to KASAN [1]. The new mode is similar to the existing software tag-based KASAN, but relies on arm64 Memory Tagging Extension (MTE) [2] to perform memory and pointer tagging (instead of shadow memory and compiler instrumentation). This patchset is co-developed and tested by Vincenzo Frascino . This patchset is available here: https://github.com/xairy/linux/tree/up-kasan-mte-v11 For testing in QEMU hardware tag-based KASAN requires: 1. QEMU built from master [4] (use "-machine virt,mte=on -cpu max" arguments to run). 2. GCC version 10. [1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html [2] https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/enhancing-memory-safety [3] git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux for-next/mte [4] https://github.com/qemu/qemu ====== Overview The underlying ideas of the approach used by hardware tag-based KASAN are: 1. By relying on the Top Byte Ignore (TBI) arm64 CPU feature, pointer tags are stored in the top byte of each kernel pointer. 2. With the Memory Tagging Extension (MTE) arm64 CPU feature, memory tags for kernel memory allocations are stored in a dedicated memory not accessible via normal instuctions. 3. On each memory allocation, a random tag is generated, embedded it into the returned pointer, and the corresponding memory is tagged with the same tag value. 4. With MTE the CPU performs a check on each memory access to make sure that the pointer tag matches the memory tag. 5. On a tag mismatch the CPU generates a tag fault, and a KASAN report is printed. Same as other KASAN modes, hardware tag-based KASAN is intended as a debugging feature at this point. ====== Rationale There are two main reasons for this new hardware tag-based mode: 1. Previously implemented software tag-based KASAN is being successfully used on dogfood testing devices due to its low memory overhead (as initially planned). The new hardware mode keeps the same low memory overhead, and is expected to have significantly lower performance impact, due to the tag checks being performed by the hardware. Therefore the new mode can be used as a better alternative in dogfood testing for hardware that supports MTE. 2. The new mode lays the groundwork for the planned in-kernel MTE-based memory corruption mitigation to be used in production. ====== Technical details Considering the implementation perspective, hardware tag-based KASAN is almost identical to the software mode. The key difference is using MTE for assigning and checking tags. Compared to the software mode, the hardware mode uses 4 bits per tag, as dictated by MTE. Pointer tags are stored in bits [56:60), the top 4 bits have the normal value 0xF. Having less distict tags increases the probablity of false negatives (from ~1/256 to ~1/16) in certain cases. Only synchronous exceptions are set up and used by hardware tag-based KASAN. ====== Benchmarks Note: all measurements have been performed with software emulation of Memory Tagging Extension, performance numbers for hardware tag-based KASAN on the actual hardware are expected to be better. Boot time [1]: * 2.8 sec for clean kernel * 5.7 sec for hardware tag-based KASAN * 11.8 sec for software tag-based KASAN * 11.6 sec for generic KASAN Slab memory usage after boot [2]: * 7.0 kb for clean kernel * 9.7 kb for hardware tag-based KASAN * 9.7 kb for software tag-based KASAN * 41.3 kb for generic KASAN Measurements have been performed with: * defconfig-based configs * Manually built QEMU master * QEMU arguments: -machine virt,mte=on -cpu max * CONFIG_KASAN_STACK_ENABLE disabled * CONFIG_KASAN_INLINE enabled * clang-10 as the compiler and gcc-10 as the assembler [1] Time before the ext4 driver is initialized. [2] Measured as `cat /proc/meminfo | grep Slab`. ====== Notes The cover letter for software tag-based KASAN patchset can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0116523cfffa62aeb5aa3b85ce7419f3dae0c1b8 ===== Tags Tested-by: Vincenzo Frascino This patch (of 41): Don't mention "GNU General Public License version 2" text explicitly, as it's already covered by the SPDX-License-Identifier. Link: https://lkml.kernel.org/r/cover.1606161801.git.andreyknvl@google.com Link: https://lkml.kernel.org/r/6ea9f5f4aa9dbbffa0d0c0a780b37699a4531034.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Tested-by: Vincenzo Frascino Cc: Catalin Marinas Cc: Will Deacon Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Evgenii Stepanov Cc: Branislav Rankov Cc: Kevin Brodsky Cc: Vasily Gorbik Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove __ARCH_HAS_5LEVEL_HACK and include/asm-generic/5level-fixup.h

2020-06-05T02:06:21Z

There are no architectures that use include/asm-generic/5level-fixup.h therefore it can be removed along with __ARCH_HAS_5LEVEL_HACK define and the code it surrounds Signed-off-by: Mike Rapoport Signed-off-by: Andrew Morton Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Brian Cain Cc: Catalin Marinas Cc: Christophe Leroy Cc: Fenghua Yu Cc: Geert Uytterhoeven Cc: Guan Xuetao Cc: James Morse Cc: Jonas Bonn Cc: Julien Thierry Cc: Ley Foon Tan Cc: Marc Zyngier Cc: Michael Ellerman Cc: Paul Mackerras Cc: Rich Felker Cc: Russell King Cc: Stafford Horne Cc: Stefan Kristiansson Cc: Suzuki K Poulose Cc: Tony Luck Cc: Will Deacon Cc: Yoshinori Sato Link: http://lkml.kernel.org/r/20200414153455.21744-15-rppt@kernel.org Signed-off-by: Linus Torvalds