| From: |
| Andrey Konovalov <andreyknvl-AT-google.com> |
| To: |
| Catalin Marinas <catalin.marinas-AT-arm.com>, Will Deacon <will.deacon-AT-arm.com>, Mark Rutland <mark.rutland-AT-arm.com>, Robin Murphy <robin.murphy-AT-arm.com>, Al Viro <viro-AT-zeniv.linux.org.uk>, Andrey Konovalov <andreyknvl-AT-google.com>, Kees Cook <keescook-AT-chromium.org>, Kate Stewart <kstewart-AT-linuxfoundation.org>, Greg Kroah-Hartman <gregkh-AT-linuxfoundation.org>, Andrew Morton <akpm-AT-linux-foundation.org>, Ingo Molnar <mingo-AT-kernel.org>, "Kirill A . Shutemov" <kirill.shutemov-AT-linux.intel.com>, Shuah Khan <shuah-AT-kernel.org>, linux-arm-kernel-AT-lists.infradead.org, linux-doc-AT-vger.kernel.org, linux-mm-AT-kvack.org, linux-arch-AT-vger.kernel.org, linux-kselftest-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org |
| Subject: |
| [PATCH v4 0/7] arm64: untag user pointers passed to the kernel |
| Date: |
| Wed, 20 Jun 2018 17:24:19 +0200 |
| Message-ID: |
| <cover.1529507994.git.andreyknvl@google.com> |
| Cc: |
| Dmitry Vyukov <dvyukov-AT-google.com>, Kostya Serebryany <kcc-AT-google.com>, Evgeniy Stepanov <eugenis-AT-google.com>, Lee Smith <Lee.Smith-AT-arm.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan-AT-arm.com>, Jacob Bramley <Jacob.Bramley-AT-arm.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan-AT-arm.com>, Chintan Pandya <cpandya-AT-codeaurora.org> |
| Archive-link: |
| Article |
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/HardwareAssistedAddressSanitiz...
Changes in v4:
- Added a selftest for checking that passing tagged pointers to the
kernel succeeds.
- Rebased onto 81e97f013 (4.18-rc1+).
Changes in v3:
- Rebased onto e5c51f30 (4.17-rc6+).
- Added linux-arch@ to the list of recipients.
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 (7):
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
selftests, arm64: add a selftest for passing tagged pointers to kernel
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 ++++
tools/testing/selftests/arm64/.gitignore | 1 +
tools/testing/selftests/arm64/Makefile | 11 +++++++++++
.../testing/selftests/arm64/run_tags_test.sh | 12 ++++++++++++
tools/testing/selftests/arm64/tags_test.c | 19 +++++++++++++++++++
10 files changed, 67 insertions(+), 7 deletions(-)
create mode 100644 tools/testing/selftests/arm64/.gitignore
create mode 100644 tools/testing/selftests/arm64/Makefile
create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
create mode 100644 tools/testing/selftests/arm64/tags_test.c
--
2.18.0.rc1.244.gcf134e6275-goog
