[v7,00/11] arm64: Branch Target Identification support
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Message ID 20200226155714.43937-1-broonie@kernel.org
State New
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Pull-request

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc.git arm64-bti

Message

Mark Brown Feb. 26, 2020, 3:57 p.m. UTC
This patch series implements support for ARMv8.5-A Branch Target
Identification (BTI), which is a control flow integrity protection
feature introduced as part of the ARMv8.5-A extensions.

Changes:

v7:
 - Rebase onto v5.6-rc3.
 - Move comment about keeping NT_GNU_PROPERTY_TYPE_0 internal into first
   patch.
 - Add an explicit check for system_supports_bti() when parsing BTI ELF
   property for improved robustness.
v6:
 - Rebase onto v5.6-rc1.
 - Fix typos s/BYTPE/BTYPE/ in commit log for "arm64: BTI: Decode BYTPE
   bits when printing PSTATE".
v5:
 - Changed a bunch of -EIO to -ENOEXEC in the ELF parsing code.
 - Move PSR_BTYPE defines to UAPI.
 - Use compat_user_mode() rather than open coding.
 - Fix a typo s/BYTPE/BTYPE/ in syscall.c
v4:
 - Dropped patch fixing existing documentation as it has already been merged.
 - Convert WARN_ON() to WARN_ON_ONCE() in "ELF: Add ELF program property
   parsing support".
 - Added display of guarded pages to ptdump.
 - Updated for conversion of exception handling from assembler to C.

Notes:

 * GCC 9 can compile backwards-compatible BTI-enabled code with
   -mbranch-protection=bti or -mbranch-protection=standard.

 * Binutils trunk supports the new ELF note, but this wasn't in a release
   the last time I posted this series.  (The situation _might_ have changed
   in the meantime...)

   Creation of a BTI-enabled binary requires _everything_ linked in to
   be BTI-enabled.  For now ld --force-bti can be used to override this,
   but some things may break until the required C library support is in
   place.

   There is no straightforward way to mark a .s file as BTI-enabled:
   scraping the output from gcc -S works as a quick hack for now.

   readelf -n can be used to examing the program properties in an ELF
   file.

 * Runtime mmap() and mprotect() can be used to enable BTI on a
   page-by-page basis using the new PROT_BTI, but the code in the
   affected pages still needs to be written or compiled to contain the
   appopriate BTI landing pads.

The following changes since commit f8788d86ab28f61f7b46eb6be375f8a726783636:

  Linux 5.6-rc3 (2020-02-23 16:17:42 -0800)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc.git arm64-bti

for you to fetch changes up to d6897bb309fc4ef374e1de8242eb94d1fb97c13b:

  arm64: mm: Display guarded pages in ptdump (2020-02-26 12:12:31 +0000)

Dave Martin (10):
  ELF: UAPI and Kconfig additions for ELF program properties
  ELF: Add ELF program property parsing support
  arm64: Basic Branch Target Identification support
  elf: Allow arch to tweak initial mmap prot flags
  arm64: elf: Enable BTI at exec based on ELF program properties
  arm64: BTI: Decode BYTPE bits when printing PSTATE
  arm64: unify native/compat instruction skipping
  arm64: traps: Shuffle code to eliminate forward declarations
  arm64: BTI: Reset BTYPE when skipping emulated instructions
  KVM: arm64: BTI: Reset BTYPE when skipping emulated instructions

Mark Brown (1):
  arm64: mm: Display guarded pages in ptdump

 Documentation/arm64/cpu-feature-registers.rst |   2 +
 Documentation/arm64/elf_hwcaps.rst            |   5 +
 arch/arm64/Kconfig                            |  25 +++
 arch/arm64/include/asm/cpucaps.h              |   3 +-
 arch/arm64/include/asm/cpufeature.h           |   6 +
 arch/arm64/include/asm/elf.h                  |  51 ++++++
 arch/arm64/include/asm/esr.h                  |   2 +-
 arch/arm64/include/asm/exception.h            |   1 +
 arch/arm64/include/asm/hwcap.h                |   1 +
 arch/arm64/include/asm/kvm_emulate.h          |   6 +-
 arch/arm64/include/asm/mman.h                 |  37 +++++
 arch/arm64/include/asm/pgtable-hwdef.h        |   1 +
 arch/arm64/include/asm/pgtable.h              |   2 +-
 arch/arm64/include/asm/ptrace.h               |   1 +
 arch/arm64/include/asm/sysreg.h               |   4 +
 arch/arm64/include/uapi/asm/hwcap.h           |   1 +
 arch/arm64/include/uapi/asm/mman.h            |   9 ++
 arch/arm64/include/uapi/asm/ptrace.h          |   9 ++
 arch/arm64/kernel/cpufeature.c                |  33 ++++
 arch/arm64/kernel/cpuinfo.c                   |   1 +
 arch/arm64/kernel/entry-common.c              |  11 ++
 arch/arm64/kernel/process.c                   |  36 ++++-
 arch/arm64/kernel/ptrace.c                    |   2 +-
 arch/arm64/kernel/signal.c                    |  16 ++
 arch/arm64/kernel/syscall.c                   |  18 +++
 arch/arm64/kernel/traps.c                     | 127 +++++++--------
 arch/arm64/mm/dump.c                          |   5 +
 fs/Kconfig.binfmt                             |   6 +
 fs/binfmt_elf.c                               | 145 +++++++++++++++++-
 fs/compat_binfmt_elf.c                        |   4 +
 include/linux/elf.h                           |  43 ++++++
 include/linux/mm.h                            |   3 +
 include/uapi/linux/elf.h                      |  11 ++
 33 files changed, 552 insertions(+), 75 deletions(-)
 create mode 100644 arch/arm64/include/asm/mman.h
 create mode 100644 arch/arm64/include/uapi/asm/mman.h

Comments

Kees Cook Feb. 26, 2020, 9:44 p.m. UTC | #1
On Wed, Feb 26, 2020 at 03:57:03PM +0000, Mark Brown wrote:
> This patch series implements support for ARMv8.5-A Branch Target
> Identification (BTI), which is a control flow integrity protection
> feature introduced as part of the ARMv8.5-A extensions.
> 
> Changes:
> 
> v7:
>  - Rebase onto v5.6-rc3.
>  - Move comment about keeping NT_GNU_PROPERTY_TYPE_0 internal into first
>    patch.
>  - Add an explicit check for system_supports_bti() when parsing BTI ELF
>    property for improved robustness.

Looks good. I sent a few more Reviewed-bys where I could. Who is
expected to pick this up? Catalin? Will?

I'm excited to have both the ELF parser and BTI landed. :)

-Kees
Mark Brown Feb. 27, 2020, 1:13 p.m. UTC | #2
On Wed, Feb 26, 2020 at 01:44:59PM -0800, Kees Cook wrote:

> Looks good. I sent a few more Reviewed-bys where I could. Who is
> expected to pick this up? Catalin? Will?

Thanks, I'm expecting it'll go through the arm64 tree.