From: Dave Martin <Dave.Martin@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org,
linux-media@vger.kernel.org, kvm@vger.kernel.org,
linux-kselftest@vger.kernel.org,
Mark Rutland <mark.rutland@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Kostya Serebryany <kcc@google.com>,
Khalid Aziz <khalid.aziz@oracle.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Jacob Bramley <Jacob.Bramley@arm.com>,
Leon Romanovsky <leon@kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
Evgeniy Stepanov <eugenis@google.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Kees Cook <keescook@chromium.org>,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Yishai Hadas <yishaih@mellanox.com>,
Jens Wiklander <jens.wiklander@linaro.org>,
Lee Smith <Lee.Smith@arm.com>,
Alexander Deucher <Alexander.Deucher@amd.com>,
Andrew Morton <akpm@linux-foundation.org>, enh <enh@google.com>,
Robin Murphy <robin.murphy@arm.com>,
Christian Koenig <Christian.Koenig@amd.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: Re: [PATCH v17 03/15] arm64: Introduce prctl() options to control the tagged user addresses ABI
Date: Thu, 13 Jun 2019 12:16:59 +0100 [thread overview]
Message-ID: <20190613111659.GX28398@e103592.cambridge.arm.com> (raw)
In-Reply-To: <a7a2933bea5fe57e504891b7eec7e9432e5e1c1a.1560339705.git.andreyknvl@google.com>
On Wed, Jun 12, 2019 at 01:43:20PM +0200, Andrey Konovalov wrote:
> From: Catalin Marinas <catalin.marinas@arm.com>
>
> It is not desirable to relax the ABI to allow tagged user addresses into
> the kernel indiscriminately. This patch introduces a prctl() interface
> for enabling or disabling the tagged ABI with a global sysctl control
> for preventing applications from enabling the relaxed ABI (meant for
> testing user-space prctl() return error checking without reconfiguring
> the kernel). The ABI properties are inherited by threads of the same
> application and fork()'ed children but cleared on execve().
>
> The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
> MTE-specific settings like imprecise vs precise exceptions.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
> arch/arm64/include/asm/processor.h | 6 +++
> arch/arm64/include/asm/thread_info.h | 1 +
> arch/arm64/include/asm/uaccess.h | 3 +-
> arch/arm64/kernel/process.c | 67 ++++++++++++++++++++++++++++
> include/uapi/linux/prctl.h | 5 +++
> kernel/sys.c | 16 +++++++
> 6 files changed, 97 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fcd0e691b1ea..fee457456aa8 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -307,6 +307,12 @@ extern void __init minsigstksz_setup(void);
> /* PR_PAC_RESET_KEYS prctl */
> #define PAC_RESET_KEYS(tsk, arg) ptrauth_prctl_reset_keys(tsk, arg)
>
> +/* PR_TAGGED_ADDR prctl */
(A couple of comments I missed in my last reply:)
Name mismatch?
> +long set_tagged_addr_ctrl(unsigned long arg);
> +long get_tagged_addr_ctrl(void);
> +#define SET_TAGGED_ADDR_CTRL(arg) set_tagged_addr_ctrl(arg)
> +#define GET_TAGGED_ADDR_CTRL() get_tagged_addr_ctrl()
> +
[...]
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 3767fb21a5b8..69d0be1fc708 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -30,6 +30,7 @@
> #include <linux/kernel.h>
> #include <linux/mm.h>
> #include <linux/stddef.h>
> +#include <linux/sysctl.h>
> #include <linux/unistd.h>
> #include <linux/user.h>
> #include <linux/delay.h>
> @@ -323,6 +324,7 @@ void flush_thread(void)
> fpsimd_flush_thread();
> tls_thread_flush();
> flush_ptrace_hw_breakpoint(current);
> + clear_thread_flag(TIF_TAGGED_ADDR);
> }
>
> void release_thread(struct task_struct *dead_task)
> @@ -552,3 +554,68 @@ void arch_setup_new_exec(void)
>
> ptrauth_thread_init_user(current);
> }
> +
> +/*
> + * Control the relaxed ABI allowing tagged user addresses into the kernel.
> + */
> +static unsigned int tagged_addr_prctl_allowed = 1;
> +
> +long set_tagged_addr_ctrl(unsigned long arg)
> +{
> + if (!tagged_addr_prctl_allowed)
> + return -EINVAL;
So, tagging can actually be locked on by having a process enable it and
then some possibly unrelated process clearing tagged_addr_prctl_allowed.
That feels a bit weird.
Do we want to allow a process that has tagging on to be able to turn
it off at all? Possibly things like CRIU might want to do that.
> + if (is_compat_task())
> + return -EINVAL;
> + if (arg & ~PR_TAGGED_ADDR_ENABLE)
> + return -EINVAL;
How do we expect this argument to be extended in the future?
I'm wondering whether this is really a bitmask or an enum, or a mixture
of the two. Maybe it doesn't matter.
> +
> + if (arg & PR_TAGGED_ADDR_ENABLE)
> + set_thread_flag(TIF_TAGGED_ADDR);
> + else
> + clear_thread_flag(TIF_TAGGED_ADDR);
I think update_thread_flag() could be used here.
[...]
Cheers
---Dave
next prev parent reply other threads:[~2019-06-13 11:17 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 11:43 [PATCH v17 00/15] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 01/15] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Andrey Konovalov
2019-06-12 14:26 ` Vincenzo Frascino
2019-06-12 11:43 ` [PATCH v17 02/15] lib, arm64: untag user pointers in strn*_user Andrey Konovalov
2019-06-12 14:28 ` Vincenzo Frascino
2019-06-12 11:43 ` [PATCH v17 03/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Andrey Konovalov
2019-06-12 14:30 ` Vincenzo Frascino
2019-06-12 14:55 ` Catalin Marinas
2019-06-13 11:02 ` Dave Martin
2019-06-13 15:26 ` Catalin Marinas
2019-06-14 5:13 ` Kees Cook
2019-06-18 9:18 ` Dave Martin
2019-06-13 11:16 ` Dave Martin [this message]
2019-06-13 15:35 ` Catalin Marinas
2019-06-13 15:45 ` Vincenzo Frascino
2019-06-13 15:57 ` Catalin Marinas
2019-06-13 16:15 ` Vincenzo Frascino
2019-06-17 13:56 ` Catalin Marinas
2019-06-17 16:56 ` Szabolcs Nagy
2019-06-17 16:57 ` Evgenii Stepanov
2019-06-17 17:18 ` Catalin Marinas
2019-06-17 21:59 ` Evgenii Stepanov
2019-06-19 14:45 ` Andrey Konovalov
2019-06-19 15:29 ` Catalin Marinas
2019-06-12 11:43 ` [PATCH v17 04/15] mm, arm64: untag user pointers passed to memory syscalls Andrey Konovalov
2019-06-12 14:31 ` Vincenzo Frascino
2019-06-19 15:55 ` Khalid Aziz
2019-06-19 16:46 ` Khalid Aziz
2019-06-24 14:22 ` Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 05/15] mm, arm64: untag user pointers in mm/gup.c Andrey Konovalov
2019-06-12 14:33 ` Vincenzo Frascino
2019-06-19 16:41 ` Khalid Aziz
2019-06-12 11:43 ` [PATCH v17 06/15] mm, arm64: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-06-12 14:34 ` Vincenzo Frascino
2019-06-19 16:48 ` Khalid Aziz
2019-06-12 11:43 ` [PATCH v17 07/15] fs, arm64: untag user pointers in copy_mount_options Andrey Konovalov
2019-06-12 14:35 ` Vincenzo Frascino
2019-06-19 20:01 ` Khalid Aziz
2019-06-12 11:43 ` [PATCH v17 08/15] userfaultfd, arm64: untag user pointers Andrey Konovalov
2019-06-12 14:40 ` Vincenzo Frascino
2019-06-12 11:43 ` [PATCH v17 09/15] drm/amdgpu, " Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 10/15] drm/radeon, arm64: untag user pointers in radeon_gem_userptr_ioctl Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 11/15] IB/mlx4, arm64: untag user pointers in mlx4_get_umem_mr Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 12/15] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-06-19 20:05 ` Khalid Aziz
2019-06-12 11:43 ` [PATCH v17 13/15] tee/shm, arm64: untag user pointers in tee_shm_register Andrey Konovalov
2019-06-12 11:43 ` [PATCH v17 14/15] vfio/type1, arm64: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-06-12 14:41 ` Vincenzo Frascino
2019-06-12 15:58 ` Auger Eric
2019-06-12 11:43 ` [PATCH v17 15/15] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2019-06-12 12:30 ` Szabolcs Nagy
2019-06-12 15:00 ` Catalin Marinas
2019-06-19 14:42 ` Andrey Konovalov
2019-06-12 14:21 ` [PATCH v4 0/2] arm64 relaxed ABI Vincenzo Frascino
2019-06-12 14:21 ` [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Vincenzo Frascino
2019-06-12 15:35 ` Catalin Marinas
2019-06-13 10:15 ` Vincenzo Frascino
2019-06-13 11:37 ` Dave Martin
2019-06-13 12:28 ` Catalin Marinas
2019-06-13 13:23 ` Dave Martin
2019-06-13 15:39 ` Catalin Marinas
2019-06-12 16:30 ` Szabolcs Nagy
2019-06-13 9:20 ` Catalin Marinas
2019-06-13 10:14 ` Szabolcs Nagy
2019-06-13 11:16 ` Vincenzo Frascino
2019-06-13 12:28 ` Szabolcs Nagy
2019-06-13 14:03 ` Vincenzo Frascino
2019-06-13 15:32 ` Szabolcs Nagy
2019-06-13 15:35 ` Vincenzo Frascino
2019-06-12 14:21 ` [PATCH v4 2/2] arm64: Relax Documentation/arm64/tagged-pointers.txt Vincenzo Frascino
2019-06-12 15:56 ` Catalin Marinas
2019-06-12 16:37 ` Szabolcs Nagy
2019-06-13 15:51 ` [PATCH v5 0/2] arm64 relaxed ABI Vincenzo Frascino
2019-06-13 15:51 ` [PATCH v5 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Vincenzo Frascino
2019-06-18 11:02 ` Szabolcs Nagy
2019-06-18 13:13 ` Kevin Brodsky
2019-06-21 15:16 ` Catalin Marinas
2019-06-13 15:51 ` [PATCH v5 2/2] arm64: Relax Documentation/arm64/tagged-pointers.txt Vincenzo Frascino
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