linux-hardening - [PATCH v2 0/6] LoongArch: Add kernel address sanitizer support

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Date:   Tue,  4 Apr 2023 16:41:42 +0800
From:   Qing Zhang <zhangqing@...ngson.cn>
To:     Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Huacai Chen <chenhuacai@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        WANG Xuerui <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        kasan-dev@...glegroups.com, linux-doc@...r.kernel.org,
        linux-mm@...ck.org, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH v2 0/6] LoongArch: Add kernel address sanitizer support 

Kernel Address Sanitizer (KASAN) is a dynamic memory safety error detector
designed to find out-of-bounds and use-after-free bugs, Generic KASAN is
supported on LoongArch now.

1/8 of kernel addresses reserved for shadow memory. But for LoongArch,
There are a lot of holes between different segments and valid address
space(256T available) is insufficient to map all these segments to kasan
shadow memory with the common formula provided by kasan core, saying
addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET

So LoongArch has a ARCH specific mapping formula,different segments
are mapped individually, and only limited length of space of that
specific segment is mapped to shadow.

At early boot stage the whole shadow region populated with just
one physical page (kasan_early_shadow_page). Later, this page is
reused as readonly zero shadow for some memory that Kasan currently
don't track.
After mapping the physical memory, pages for shadow memory are
allocated and mapped.

Functions like memset/memmove/memcpy do a lot of memory accesses.
If bad pointer passed to one of these function it is important
to catch this. Compiler's instrumentation cannot do this since
these functions are written in assembly.
KASan replaces memory functions with manually instrumented variants.
Original functions declared as weak symbols so strong definitions
in mm/kasan/kasan.c could replace them. Original functions have aliases
with '__' prefix in name, so we could call non-instrumented variant
if needed.

Changes v1 -> v2:
Suggested by Andrey:
- Make two separate patches for changes to public files.
- Removes unnecessary judgments in check_region_inline.
- Add pud/pmd_init __weak define.
- Add Empty function kasan_(early)_init when CONFIG_KASAN turned off.
Suggested by Huacai:
- Split the simplified relocation patch.
Suggested by Youling:
- Add ARCH_HAS_FORTIFY_SOURCE in Kconfig and split into separate patches.
- update `Documentation/translations/zh_CN/dev-tools/kasan.rst`.
- Use macros to avoid using magic values directly.
- Modify patch sequence.
- Remove redundant tab.
- Modify submission information.

Qing Zhang (6):
  LoongArch: Simplified randomization layout after jump new kernel
    processing
  LoongArch: Fix _CONST64_(x) as unsigned
  LoongArch: Add kernel address sanitizer support
  kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping
  kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate
    process
  LoongArch: Add ARCH_HAS_FORTIFY_SOURCE

 Documentation/dev-tools/kasan.rst             |   4 +-
 .../features/debug/KASAN/arch-support.txt     |   2 +-
 .../translations/zh_CN/dev-tools/kasan.rst    |   2 +-
 arch/loongarch/Kconfig                        |   8 +
 arch/loongarch/include/asm/addrspace.h        |   4 +-
 arch/loongarch/include/asm/kasan.h            | 125 +++++++++
 arch/loongarch/include/asm/pgtable.h          |   7 +
 arch/loongarch/include/asm/setup.h            |   2 +-
 arch/loongarch/include/asm/string.h           |  20 ++
 arch/loongarch/kernel/Makefile                |   3 +
 arch/loongarch/kernel/head.S                  |  12 +-
 arch/loongarch/kernel/relocate.c              |   8 +-
 arch/loongarch/kernel/setup.c                 |   4 +
 arch/loongarch/lib/memcpy.S                   |   4 +-
 arch/loongarch/lib/memmove.S                  |  13 +-
 arch/loongarch/lib/memset.S                   |   4 +-
 arch/loongarch/mm/Makefile                    |   2 +
 arch/loongarch/mm/kasan_init.c                | 255 ++++++++++++++++++
 arch/loongarch/vdso/Makefile                  |   4 +
 include/linux/kasan.h                         |   2 +
 mm/kasan/init.c                               |  18 +-
 mm/kasan/kasan.h                              |   6 +
 22 files changed, 481 insertions(+), 28 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kasan.h
 create mode 100644 arch/loongarch/mm/kasan_init.c

-- 
2.20.1