linux-toradex.git/include/linux/kasan.h, branch v6.2-rc8

mm: kasan: Extend kasan_metadata_size() to also cover in-object size

2022-11-10T15:27:46+00:00

When kasan is enabled for slab/slub, it may save kasan' free_meta
data in the former part of slab object data area in slab object's
free path, which works fine.

There is ongoing effort to extend slub's debug function which will
redzone the latter part of kmalloc object area, and when both of
the debug are enabled, there is possible conflict, especially when
the kmalloc object has small size, as caught by 0Day bot [1].

To solve it, slub code needs to know the in-object kasan's meta
data size. Currently, there is existing kasan_metadata_size()
which returns the kasan's metadata size inside slub's metadata
area, so extend it to also cover the in-object meta size by
adding a boolean flag 'in_object'.

There is no functional change to existing code logic.

[1]. https://lore.kernel.org/lkml/YuYm3dWwpZwH58Hu@xsang-OptiPlex-9020/

Reported-by: kernel test robot 
Suggested-by: Andrey Konovalov 
Signed-off-by: Feng Tang 
Reviewed-by: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Alexander Potapenko 
Cc: Dmitry Vyukov 
Cc: Vincenzo Frascino 
Signed-off-by: Vlastimil Babka

kasan: only define kasan_cache_create for Generic mode

2022-10-03T21:02:59+00:00

Right now, kasan_cache_create() assigns SLAB_KASAN for all KASAN modes and
then sets up metadata-related cache parameters for the Generic mode.

SLAB_KASAN is used in two places:

1. In slab_ksize() to account for per-object metadata when
   calculating the size of the accessible memory within the object.
2. In slab_common.c via kasan_never_merge() to prevent merging of
   caches with per-object metadata.

Both cases are only relevant when per-object metadata is present, which is
only the case with the Generic mode.

Thus, assign SLAB_KASAN and define kasan_cache_create() only for the
Generic mode.

Also update the SLAB_KASAN-related comment.

Link: https://lkml.kernel.org/r/61faa2aa1906e2d02c97d00ddf99ce8911dda095.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reviewed-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Peter Collingbourne 
Signed-off-by: Andrew Morton

kasan: only define metadata offsets for Generic mode

2022-10-03T21:02:59+00:00

Hide the definitions of alloc_meta_offset and free_meta_offset under an
ifdef CONFIG_KASAN_GENERIC check, as these fields are now only used when
the Generic mode is enabled.

Link: https://lkml.kernel.org/r/d4bafa0534facafd1a23c465a94261e64f366493.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reviewed-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Peter Collingbourne 
Signed-off-by: Andrew Morton

kasan: only define kasan_never_merge for Generic mode

2022-10-03T21:02:58+00:00

KASAN prevents merging of slab caches whose objects have per-object
metadata stored in redzones.

As now only the Generic mode uses per-object metadata, define
kasan_never_merge() only for this mode.

Link: https://lkml.kernel.org/r/81ed01f29ff3443580b7e2fe362a8b47b1e8006d.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reviewed-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Peter Collingbourne 
Signed-off-by: Andrew Morton

kasan: only define kasan_metadata_size for Generic mode

2022-10-03T21:02:58+00:00

KASAN provides a helper for calculating the size of per-object metadata
stored in the redzone.

As now only the Generic mode uses per-object metadata, only define
kasan_metadata_size() for this mode.

Link: https://lkml.kernel.org/r/8f81d4938b80446bc72538a08217009f328a3e23.1662411799.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reviewed-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Peter Collingbourne 
Signed-off-by: Andrew Morton

kasan: mark KASAN_VMALLOC flags as kasan_vmalloc_flags_t

2022-04-29T21:36:58+00:00

Fix sparse warning:

mm/kasan/shadow.c:496:15: warning: restricted kasan_vmalloc_flags_t degrades to integer

Link: https://lkml.kernel.org/r/52d8fccdd3a48d4bdfd0ff522553bac2a13f1579.1649351254.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reported-by: kernel test robot 
Cc: Andrey Konovalov 
Cc: Marco Elver 
Cc: Alexander Potapenko 
Cc: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton

kasan: move and hide kasan_save_enable/restore_multi_shot

2022-03-25T02:06:50+00:00

 - Move kasan_save_enable/restore_multi_shot() declarations to
   mm/kasan/kasan.h, as there is no need for them to be visible outside
   of KASAN implementation.

 - Only define and export these functions when KASAN tests are enabled.

 - Move their definitions closer to other test-related code in report.c.

Link: https://lkml.kernel.org/r/6ba637333b78447f027d775f2d55ab1a40f63c99.1646237226.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Marco Elver 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kasan: test: support async (again) and asymm modes for HW_TAGS

2022-03-25T02:06:48+00:00

Async mode support has already been implemented in commit e80a76aa1a91
("kasan, arm64: tests supports for HW_TAGS async mode") but then got
accidentally broken in commit 99734b535d9b ("kasan: detect false-positives
in tests").

Restore the changes removed by the latter patch and adapt them for asymm
mode: add a sync_fault flag to kunit_kasan_expectation that only get set
if the MTE fault was synchronous, and reenable MTE on such faults in
tests.

Also rename kunit_kasan_expectation to kunit_kasan_status and move its
definition to mm/kasan/kasan.h from include/linux/kasan.h, as this
structure is only internally used by KASAN.  Also put the structure
definition under IS_ENABLED(CONFIG_KUNIT).

Link: https://lkml.kernel.org/r/133970562ccacc93ba19d754012c562351d4a8c8.1645033139.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Cc: Marco Elver 
Cc: Alexander Potapenko 
Cc: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: Vincenzo Frascino 
Cc: Catalin Marinas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kasan, vmalloc: only tag normal vmalloc allocations

2022-03-25T02:06:48+00:00

The kernel can use to allocate executable memory.  The only supported
way to do that is via __vmalloc_node_range() with the executable bit set
in the prot argument.  (vmap() resets the bit via pgprot_nx()).

Once tag-based KASAN modes start tagging vmalloc allocations, executing
code from such allocations will lead to the PC register getting a tag,
which is not tolerated by the kernel.

Only tag the allocations for normal kernel pages.

[andreyknvl@google.com: pass KASAN_VMALLOC_PROT_NORMAL to kasan_unpoison_vmalloc()]
  Link: https://lkml.kernel.org/r/9230ca3d3e40ffca041c133a524191fd71969a8d.1646233925.git.andreyknvl@google.com
[andreyknvl@google.com: support tagged vmalloc mappings]
  Link: https://lkml.kernel.org/r/2f6605e3a358cf64d73a05710cb3da356886ad29.1646233925.git.andreyknvl@google.com
[andreyknvl@google.com: don't unintentionally disabled poisoning]
  Link: https://lkml.kernel.org/r/de4587d6a719232e83c760113e46ed2d4d8da61e.1646757322.git.andreyknvl@google.com

Link: https://lkml.kernel.org/r/fbfd9939a4dc375923c9a5c6b9e7ab05c26b8c6b.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Acked-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Catalin Marinas 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Mark Rutland 
Cc: Peter Collingbourne 
Cc: Vincenzo Frascino 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kasan, vmalloc: add vmalloc tagging for HW_TAGS

2022-03-25T02:06:48+00:00

Add vmalloc tagging support to HW_TAGS KASAN.

The key difference between HW_TAGS and the other two KASAN modes when it
comes to vmalloc: HW_TAGS KASAN can only assign tags to physical memory.
The other two modes have shadow memory covering every mapped virtual
memory region.

Make __kasan_unpoison_vmalloc() for HW_TAGS KASAN:

 - Skip non-VM_ALLOC mappings as HW_TAGS KASAN can only tag a single
   mapping of normal physical memory; see the comment in the function.

 - Generate a random tag, tag the returned pointer and the allocation,
   and initialize the allocation at the same time.

 - Propagate the tag into the page stucts to allow accesses through
   page_address(vmalloc_to_page()).

The rest of vmalloc-related KASAN hooks are not needed:

 - The shadow-related ones are fully skipped.

 - __kasan_poison_vmalloc() is kept as a no-op with a comment.

Poisoning and zeroing of physical pages that are backing vmalloc()
allocations are skipped via __GFP_SKIP_KASAN_UNPOISON and
__GFP_SKIP_ZERO: __kasan_unpoison_vmalloc() does that instead.

Enabling CONFIG_KASAN_VMALLOC with HW_TAGS is not yet allowed.

Link: https://lkml.kernel.org/r/d19b2e9e59a9abc59d05b72dea8429dcaea739c6.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Co-developed-by: Vincenzo Frascino 
Signed-off-by: Vincenzo Frascino 
Acked-by: Marco Elver 
Cc: Alexander Potapenko 
Cc: Andrey Ryabinin 
Cc: Catalin Marinas 
Cc: Dmitry Vyukov 
Cc: Evgenii Stepanov 
Cc: Mark Rutland 
Cc: Peter Collingbourne 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds