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* [PATCH v2 0/6] arm64: untag user pointers passed to the kernel
@ 2018-05-03 14:15 Andrey Konovalov
  2018-05-03 14:15 ` [PATCH v2 1/6] arm64: add type casts to untagged_addr macro Andrey Konovalov
                   ` (5 more replies)
  0 siblings, 6 replies; 7+ messages in thread
From: Andrey Konovalov @ 2018-05-03 14:15 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Jonathan Corbet, Mark Rutland,
	Robin Murphy, Al Viro, Andrey Konovalov, James Morse, Kees Cook,
	Bart Van Assche, Kate Stewart, Greg Kroah-Hartman,
	Thomas Gleixner, Philippe Ombredanne, Andrew Morton, Ingo Molnar,
	Kirill A . Shutemov, Dan Williams, Aneesh Kumar K . V, Zi Yan,
	linux-arm-kernel, linux-doc, linux-kernel, linux-mm
  Cc: Dmitry Vyukov, Kostya Serebryany, Evgeniy Stepanov, Lee Smith,
	Ramana Radhakrishnan, Jacob Bramley, Ruben Ayrapetyan,
	Chintan Pandya

Hi!

arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [1]) might use this feature and pass
tagged user pointers to the kernel through syscalls or other interfaces.

This patch makes a few of the kernel interfaces accept tagged user
pointers. The kernel is already able to handle user faults with tagged
pointers and has the untagged_addr macro, which this patchset reuses.

We're not trying to cover all possible ways the kernel accepts user
pointers in one patchset, so this one should be considered as a start.

Thanks!

[1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html

Changes in v2:
- Rebased onto 2d618bdf (4.17-rc3+).
- Removed excessive untagging in gup.c.
- Removed untagging pointers returned from __uaccess_mask_ptr.

Changes in v1:
- Rebased onto 4.17-rc1.

Changes in RFC v2:
- Added "#ifndef untagged_addr..." fallback in linux/uaccess.h instead of
  defining it for each arch individually.
- Updated Documentation/arm64/tagged-pointers.txt.
- Dropped “mm, arm64: untag user addresses in memory syscalls”.
- Rebased onto 3eb2ce82 (4.16-rc7).

Andrey Konovalov (6):
  arm64: add type casts to untagged_addr macro
  uaccess: add untagged_addr definition for other arches
  arm64: untag user addresses in access_ok and __uaccess_mask_ptr
  mm, arm64: untag user addresses in mm/gup.c
  lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user
  arm64: update Documentation/arm64/tagged-pointers.txt

 Documentation/arm64/tagged-pointers.txt |  5 +++--
 arch/arm64/include/asm/uaccess.h        | 14 +++++++++-----
 include/linux/uaccess.h                 |  4 ++++
 lib/strncpy_from_user.c                 |  2 ++
 lib/strnlen_user.c                      |  2 ++
 mm/gup.c                                |  4 ++++
 6 files changed, 24 insertions(+), 7 deletions(-)

-- 
2.17.0.441.gb46fe60e1d-goog

^ permalink raw reply	[flat|nested] 7+ messages in thread

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-- links below jump to the message on this page --
2018-05-03 14:15 [PATCH v2 0/6] arm64: untag user pointers passed to the kernel Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 1/6] arm64: add type casts to untagged_addr macro Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 2/6] uaccess: add untagged_addr definition for other arches Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 3/6] arm64: untag user addresses in access_ok and __uaccess_mask_ptr Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 4/6] mm, arm64: untag user addresses in mm/gup.c Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 5/6] lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user Andrey Konovalov
2018-05-03 14:15 ` [PATCH v2 6/6] arm64: update Documentation/arm64/tagged-pointers.txt Andrey Konovalov

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