From: Mark Brown <broonie@kernel.org>
To: Deepak Gupta <debug@rivosinc.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Arnd Bergmann <arnd@arndb.de>, Oleg Nesterov <oleg@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
Kees Cook <keescook@chromium.org>, Shuah Khan <shuah@kernel.org>,
"Rick P. Edgecombe" <rick.p.edgecombe@intel.com>,
Ard Biesheuvel <ardb@kernel.org>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"H.J. Lu" <hjl.tools@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Florian Weimer <fweimer@redhat.com>,
Christian Brauner <brauner@kernel.org>,
Thiago Jung Bauermann <thiago.bauermann@linaro.org>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH v7 02/39] prctl: arch-agnostic prctl for shadow stack
Date: Wed, 13 Dec 2023 13:37:32 +0000 [thread overview]
Message-ID: <0d0d8802-09e3-4ea5-a0b4-b3a08c8a282e@sirena.org.uk> (raw)
In-Reply-To: <CAKC1njSQPO8ja7AkTzQ724hhSsGjchH9dLbbH9LXP0ZiKj-zPQ@mail.gmail.com>
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On Tue, Dec 12, 2023 at 04:50:38PM -0800, Deepak Gupta wrote:
> A theoretical scenario (no current workloads should've this case
> because no shadow stack)
> - User mode did _ENABLE on the main thread. Shadow stack was allocated
> for the current
> thread.
> - User mode created a bunch worker threads to run untrusted contained
> code. They shadow
> stack too.
> - main thread had to do dlopen and now need to disable shadow stack on
> itself due to
> incompatibility of incoming object in address space.
> - main thread controls worker threads and knows they're contained and
> should still be running
> with a shadow stack. Although once in a while the main thread needs
> to perform writes to a shadow
> stack of worker threads for some fixup (in the same addr space).
> main thread doesn't want to delegate
> this responsibility of ss writes to worker threads because they're untrusted.
> How will it do that (currently _ENABLE is married to _WRITE and _PUSH) ?
That's feeling moderately firmly into "don't do that" territory to be
honest, the problems of trying to modify the stack of another running
thread while it's active just don't seem worth it - if you're
coordinating enough to do the modifications it's probably possible to
just ask the thread who's stack is being modified to do the modification
itself and having an unprotected thread writing into shadow stack memory
doesn't feel great.
That said in terms of the API there would be nothing stopping us saying
that _WRITE by itself is a valid combination of flags, in which case the
thread would have permission to write to any shadow stack memory it
could get to. For arm64 I think we can implement that, I'm not sure
about x86. _PUSH without _ENABLE is a lot less clear, you would at the
very least at some point have had a stack enabled to have a stack
pointer.
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next prev parent reply other threads:[~2023-12-13 13:37 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 9:42 [PATCH v7 00/39] arm64/gcs: Provide support for GCS in userspace Mark Brown
2023-11-22 9:42 ` [PATCH v7 01/39] arm64/mm: Restructure arch_validate_flags() for extensibility Mark Brown
2023-11-22 9:42 ` [PATCH v7 02/39] prctl: arch-agnostic prctl for shadow stack Mark Brown
2023-12-12 19:17 ` Deepak Gupta
2023-12-12 19:22 ` Mark Brown
2023-12-13 0:50 ` Deepak Gupta
2023-12-13 13:37 ` Mark Brown [this message]
2023-12-13 19:43 ` Deepak Gupta
2023-12-13 19:48 ` Mark Brown
2023-12-12 20:17 ` Edgecombe, Rick P
2023-12-12 20:26 ` Mark Brown
2023-12-12 21:22 ` Edgecombe, Rick P
2023-12-13 13:49 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 03/39] mman: Add map_shadow_stack() flags Mark Brown
2023-11-22 9:42 ` [PATCH v7 04/39] arm64: Document boot requirements for Guarded Control Stacks Mark Brown
2023-11-22 9:42 ` [PATCH v7 05/39] arm64/gcs: Document the ABI " Mark Brown
2023-11-22 9:42 ` [PATCH v7 06/39] arm64/sysreg: Add new system registers for GCS Mark Brown
2023-11-22 9:42 ` [PATCH v7 07/39] arm64/sysreg: Add definitions for architected GCS caps Mark Brown
2023-11-22 9:42 ` [PATCH v7 08/39] arm64/gcs: Add manual encodings of GCS instructions Mark Brown
2023-11-22 9:42 ` [PATCH v7 09/39] arm64/gcs: Provide put_user_gcs() Mark Brown
2023-11-22 9:42 ` [PATCH v7 10/39] arm64/cpufeature: Runtime detection of Guarded Control Stack (GCS) Mark Brown
2023-11-22 9:42 ` [PATCH v7 11/39] arm64/mm: Allocate PIE slots for EL0 guarded control stack Mark Brown
2023-11-22 9:42 ` [PATCH v7 12/39] mm: Define VM_SHADOW_STACK for arm64 when we support GCS Mark Brown
2023-11-22 9:42 ` [PATCH v7 13/39] arm64/mm: Map pages for guarded control stack Mark Brown
2023-12-04 3:01 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 14/39] KVM: arm64: Manage GCS registers for guests Mark Brown
2023-11-22 9:42 ` [PATCH v7 15/39] arm64/gcs: Allow GCS usage at EL0 and EL1 Mark Brown
2023-11-22 9:42 ` [PATCH v7 16/39] arm64/idreg: Add overrride for GCS Mark Brown
2023-11-22 9:42 ` [PATCH v7 17/39] arm64/hwcap: Add hwcap " Mark Brown
2023-11-22 9:42 ` [PATCH v7 18/39] arm64/traps: Handle GCS exceptions Mark Brown
2023-11-22 9:42 ` [PATCH v7 19/39] arm64/mm: Handle GCS data aborts Mark Brown
2023-11-22 9:42 ` [PATCH v7 20/39] arm64/gcs: Context switch GCS state for EL0 Mark Brown
2023-12-13 19:59 ` Deepak Gupta
2023-12-13 20:02 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 21/39] arm64/gcs: Allocate a new GCS for threads with GCS enabled Mark Brown
2023-12-06 20:22 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 22/39] arm64/gcs: Implement shadow stack prctl() interface Mark Brown
2023-12-06 21:27 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 23/39] arm64/mm: Implement map_shadow_stack() Mark Brown
2023-12-06 21:44 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 24/39] arm64/signal: Set up and restore the GCS context for signal handlers Mark Brown
2023-12-09 3:15 ` Thiago Jung Bauermann
2023-12-09 13:09 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 25/39] arm64/signal: Expose GCS state in signal frames Mark Brown
2023-12-09 22:28 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 26/39] arm64/ptrace: Expose GCS via ptrace and core files Mark Brown
2023-12-09 23:49 ` Thiago Jung Bauermann
2023-12-10 14:22 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 27/39] arm64: Add Kconfig for Guarded Control Stack (GCS) Mark Brown
2023-11-22 9:42 ` [PATCH v7 28/39] kselftest/arm64: Verify the GCS hwcap Mark Brown
2023-11-22 9:42 ` [PATCH v7 29/39] kselftest/arm64: Add GCS as a detected feature in the signal tests Mark Brown
2023-11-22 9:42 ` [PATCH v7 30/39] kselftest/arm64: Add framework support for GCS to signal handling tests Mark Brown
2023-11-22 9:42 ` [PATCH v7 31/39] kselftest/arm64: Allow signals tests to specify an expected si_code Mark Brown
2023-11-22 9:42 ` [PATCH v7 32/39] kselftest/arm64: Always run signals tests with GCS enabled Mark Brown
2023-11-22 9:42 ` [PATCH v7 33/39] kselftest/arm64: Add very basic GCS test program Mark Brown
2023-11-22 9:42 ` [PATCH v7 34/39] kselftest/arm64: Add a GCS test program built with the system libc Mark Brown
2023-12-15 2:50 ` Thiago Jung Bauermann
2023-12-15 14:59 ` Mark Brown
2023-12-17 2:18 ` Thiago Jung Bauermann
2024-01-18 19:58 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 35/39] kselftest/arm64: Add test coverage for GCS mode locking Mark Brown
2023-11-22 9:42 ` [PATCH v7 36/39] selftests/arm64: Add GCS signal tests Mark Brown
2023-12-17 2:12 ` Thiago Jung Bauermann
2024-01-18 21:10 ` Mark Brown
2023-11-22 9:42 ` [PATCH v7 37/39] kselftest/arm64: Add a GCS stress test Mark Brown
2023-12-13 2:45 ` Thiago Jung Bauermann
2023-11-22 9:42 ` [PATCH v7 38/39] kselftest/arm64: Enable GCS for the FP stress tests Mark Brown
2023-11-22 9:42 ` [PATCH v7 39/39] kselftest/clone3: Enable GCS in the clone3 selftests Mark Brown
2023-12-20 4:13 ` [PATCH v7 00/39] arm64/gcs: Provide support for GCS in userspace Thiago Jung Bauermann
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