[PATCH v6 00/39] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS

andrey.konovalov
2022-01-24T18:34:15Z

Hi,

This patchset adds vmalloc tagging support for SW_TAGS and HW_TAGS
KASAN modes.

The tree with patches is available here:

https://github.com/xairy/linux/tree/up-kasan-vmalloc-tags-v6

About half of patches are cleanups I went for along the way. None of
them seem to be important enough to go through stable, so I decided
not to split them out into separate patches/series.

The patchset is partially based on an early version of the HW_TAGS
patchset by Vincenzo that had vmalloc support. Thus, I added a
Co-developed-by tag into a few patches.

SW_TAGS vmalloc tagging support is straightforward. It reuses all of
the generic KASAN machinery, but uses shadow memory to store tags
instead of magic values. Naturally, vmalloc tagging requires adding
a few kasan_reset_tag() annotations to the vmalloc code.

HW_TAGS vmalloc tagging support stands out. HW_TAGS KASAN is based on
Arm MTE, which can only assigns tags to physical memory. As a result,
HW_TAGS KASAN only tags vmalloc() allocations, which are backed by
page_alloc memory. It ignores vmap() and others.

Thanks!

Changes in v5->v6:
- Rebased onto mainline/5.17-rc1.
- Drop unnecessary explicit checks for software KASAN modes from
should_skip_init().

Changes in v4->v5:
- Rebase onto fresh mm.
- Mention optimization intention in the comment for __GFP_ZEROTAGS.
- Replace "kasan: simplify kasan_init_hw_tags" with "kasan: clean up
feature flags for HW_TAGS mode".
- Use true as kasan_flag_vmalloc static key default.
- Cosmetic changes to __def_gfpflag_names_kasan and __GFP_BITS_SHIFT.

Changes in v3->v4:
- Rebase onto fresh mm.
- Rename KASAN_VMALLOC_NOEXEC to KASAN_VMALLOC_PROT_NORMAL.
- Compare prot with PAGE_KERNEL instead of using pgprot_nx() to
indentify normal non-executable mappings.
- Rename arch_vmalloc_pgprot_modify() to arch_vmap_pgprot_tagged().
- Move checks from arch_vmap_pgprot_tagged() to __vmalloc_node_range()
as the same condition is used for other things in subsequent patches.
- Use proper kasan_hw_tags_enabled() checks instead of
IS_ENABLED(CONFIG_KASAN_HW_TAGS).
- Set __GFP_SKIP_KASAN_UNPOISON and __GFP_SKIP_ZERO flags instead of
resetting.
- Only define KASAN GFP flags when when HW_TAGS KASAN is enabled.
- Move setting KASAN GFP flags to __vmalloc_node_range() and do it
only for normal non-executable mapping when HW_TAGS KASAN is enabled.
- Add new GFP flags to include/trace/events/mmflags.h.
- Don't forget to save tagged addr to vm_struct->addr for VM_ALLOC
so that find_vm_area(addr)->addr == addr for vmalloc().
- Reset pointer tag in change_memory_common().
- Add test checks for set_memory_*() on vmalloc() allocations.
- Minor patch descriptions and comments fixes.

Changes in v2->v3:
- Rebase onto mm.
- New patch: "kasan, arm64: reset pointer tags of vmapped stacks".
- New patch: "kasan, vmalloc: don't tag executable vmalloc allocations".
- New patch: "kasan, arm64: don't tag executable vmalloc allocations".
- Allowing enabling KASAN_VMALLOC with SW/HW_TAGS is moved to
"kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS", as this can only
be done once executable allocations are no longer tagged.
- Minor fixes, see patches for lists of changes.

Changes in v1->v2:
- Move memory init for vmalloc() into vmalloc code for HW_TAGS KASAN.
- Minor fixes and code reshuffling, see patches for lists of changes.

Acked-by: Marco Elver <elver@google.com>

Andrey Konovalov (39):
kasan, page_alloc: deduplicate should_skip_kasan_poison
kasan, page_alloc: move tag_clear_highpage out of
kernel_init_free_pages
kasan, page_alloc: merge kasan_free_pages into free_pages_prepare
kasan, page_alloc: simplify kasan_poison_pages call site
kasan, page_alloc: init memory of skipped pages on free
kasan: drop skip_kasan_poison variable in free_pages_prepare
mm: clarify __GFP_ZEROTAGS comment
kasan: only apply __GFP_ZEROTAGS when memory is zeroed
kasan, page_alloc: refactor init checks in post_alloc_hook
kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook
kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook
kasan, page_alloc: move SetPageSkipKASanPoison in post_alloc_hook
kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook
kasan, page_alloc: rework kasan_unpoison_pages call site
kasan: clean up metadata byte definitions
kasan: define KASAN_VMALLOC_INVALID for SW_TAGS
kasan, x86, arm64, s390: rename functions for modules shadow
kasan, vmalloc: drop outdated VM_KASAN comment
kasan: reorder vmalloc hooks
kasan: add wrappers for vmalloc hooks
kasan, vmalloc: reset tags in vmalloc functions
kasan, fork: reset pointer tags of vmapped stacks
kasan, arm64: reset pointer tags of vmapped stacks
kasan, vmalloc: add vmalloc tagging for SW_TAGS
kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged
kasan, vmalloc: unpoison VM_ALLOC pages after mapping
kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS
kasan, page_alloc: allow skipping unpoisoning for HW_TAGS
kasan, page_alloc: allow skipping memory init for HW_TAGS
kasan, vmalloc: add vmalloc tagging for HW_TAGS
kasan, vmalloc: only tag normal vmalloc allocations
kasan, arm64: don't tag executable vmalloc allocations
kasan: mark kasan_arg_stacktrace as __initdata
kasan: clean up feature flags for HW_TAGS mode
kasan: add kasan.vmalloc command line flag
kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS
arm64: select KASAN_VMALLOC for SW/HW_TAGS modes
kasan: documentation updates
kasan: improve vmalloc tests

Documentation/dev-tools/kasan.rst | 17 ++-
arch/arm64/Kconfig | 2 +-
arch/arm64/include/asm/vmalloc.h | 6 +
arch/arm64/include/asm/vmap_stack.h | 5 +-
arch/arm64/kernel/module.c | 5 +-
arch/arm64/mm/pageattr.c | 2 +-
arch/arm64/net/bpf_jit_comp.c | 3 +-
arch/s390/kernel/module.c | 2 +-
arch/x86/kernel/module.c | 2 +-
include/linux/gfp.h | 35 +++--
include/linux/kasan.h | 97 +++++++++-----
include/linux/vmalloc.h | 18 +--
include/trace/events/mmflags.h | 14 +-
kernel/fork.c | 1 +
kernel/scs.c | 4 +-
lib/Kconfig.kasan | 20 +--
lib/test_kasan.c | 189 ++++++++++++++++++++++++++-
mm/kasan/common.c | 4 +-
mm/kasan/hw_tags.c | 193 ++++++++++++++++++++++------
mm/kasan/kasan.h | 18 ++-
mm/kasan/shadow.c | 63 +++++----
mm/page_alloc.c | 152 +++++++++++++++-------
mm/vmalloc.c | 99 +++++++++++---
23 files changed, 731 insertions(+), 220 deletions(-)