From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
kvm@vger.kernel.org, Christian Koenig <Christian.Koenig@amd.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Will Deacon <will.deacon@arm.com>,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
Khalid Aziz <khalid.aziz@oracle.com>,
Lee Smith <Lee.Smith@arm.com>,
linux-kselftest@vger.kernel.org,
Jacob Bramley <Jacob.Bramley@arm.com>,
Leon Romanovsky <leon@kernel.org>,
linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org,
Christoph Hellwig <hch@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
linux-arm-kernel@lists.infradead.org,
Dave Martin <Dave.Martin@arm.com>,
Evgeniy Stepanov <eugenis@google.com>,
linux-media@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
Andrey Konovalov <andreyknvl@google.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Kostya Serebryany <kcc@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Felix Kuehling <Felix.Kuehling@amd.com>,
linux-kernel@vger.kernel.org,
Jens Wiklander <jens.wiklander@linaro.org>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
Alexander Deucher <Alexander.Deucher@amd.com>,
Andrew Morton <akpm@linux-foundation.org>, enh <enh@google.com>,
Robin Murphy <robin.murphy@arm.com>,
Yishai Hadas <yishaih@mellanox.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr
Date: Wed, 12 Jun 2019 12:52:49 +0100 [thread overview]
Message-ID: <c760f34a-1b99-17bb-8cc8-ea8b0d63fe90@arm.com> (raw)
In-Reply-To: <20190612093158.GG10165@c02tf0j2hf1t.cambridge.arm.com>
Hi Catalin,
On 12/06/2019 10:32, Catalin Marinas wrote:
> Hi Vincenzo,
>
> On Tue, Jun 11, 2019 at 06:09:10PM +0100, Vincenzo Frascino wrote:
>>> 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);
>>
>> Nit: in line we the other functions in thread_flush we could have something like
>> "tagged_addr_thread_flush", maybe inlined.
>
> The other functions do a lot more than clearing a TIF flag, so they
> deserved their own place. We could do this when adding MTE support. I
> think we also need to check what other TIF flags we may inadvertently
> pass on execve(), maybe have a mask clearing.
>
Agreed. All the comments I provided are meant to simplify the addition of MTE
support.
>>> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
>>> index 094bb03b9cc2..2e927b3e9d6c 100644
>>> --- a/include/uapi/linux/prctl.h
>>> +++ b/include/uapi/linux/prctl.h
>>> @@ -229,4 +229,9 @@ struct prctl_mm_map {
>>> # define PR_PAC_APDBKEY (1UL << 3)
>>> # define PR_PAC_APGAKEY (1UL << 4)
>>>
>>> +/* Tagged user address controls for arm64 */
>>> +#define PR_SET_TAGGED_ADDR_CTRL 55
>>> +#define PR_GET_TAGGED_ADDR_CTRL 56
>>> +# define PR_TAGGED_ADDR_ENABLE (1UL << 0)
>>> +
>>> #endif /* _LINUX_PRCTL_H */
>>> diff --git a/kernel/sys.c b/kernel/sys.c
>>> index 2969304c29fe..ec48396b4943 100644
>>> --- a/kernel/sys.c
>>> +++ b/kernel/sys.c
>>> @@ -124,6 +124,12 @@
>>> #ifndef PAC_RESET_KEYS
>>> # define PAC_RESET_KEYS(a, b) (-EINVAL)
>>> #endif
>>> +#ifndef SET_TAGGED_ADDR_CTRL
>>> +# define SET_TAGGED_ADDR_CTRL(a) (-EINVAL)
>>> +#endif
>>> +#ifndef GET_TAGGED_ADDR_CTRL
>>> +# define GET_TAGGED_ADDR_CTRL() (-EINVAL)
>>> +#endif
>>>
>>> /*
>>> * this is where the system-wide overflow UID and GID are defined, for
>>> @@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>>> return -EINVAL;
>>> error = PAC_RESET_KEYS(me, arg2);
>>> break;
>>> + case PR_SET_TAGGED_ADDR_CTRL:
>>> + if (arg3 || arg4 || arg5)
>>> + return -EINVAL;
>>> + error = SET_TAGGED_ADDR_CTRL(arg2);
>>> + break;
>>> + case PR_GET_TAGGED_ADDR_CTRL:
>>> + if (arg2 || arg3 || arg4 || arg5)
>>> + return -EINVAL;
>>> + error = GET_TAGGED_ADDR_CTRL();
>>> + break;
>>
>> Why do we need two prctl here? We could have only one and use arg2 as set/get
>> and arg3 as a parameter. What do you think?
>
> This follows the other PR_* options, e.g. PR_SET_VL/GET_VL,
> PR_*_FP_MODE. We will use other bits in arg2, for example to set the
> precise vs imprecise MTE trapping.
>
Indeed. I was not questioning the pre-existing interface definition, but trying
more to reduce the changes to the ABI to the minimum since:
- prctl does not mandate how to use the arg[2-5]
- prctl interface is flexible enough for the problem to be solved with only one
PR_ command.
I agree on reusing the interface for MTE for the purposes you specified.
--
Regards,
Vincenzo
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next prev parent reply other threads:[~2019-06-12 11:53 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-03 16:55 [PATCH v16 00/16] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches Andrey Konovalov
2019-06-03 17:02 ` Khalid Aziz
2019-06-03 17:06 ` Andrey Konovalov
2019-06-03 17:24 ` Khalid Aziz
2019-06-03 17:29 ` Christoph Hellwig
2019-06-03 18:17 ` Khalid Aziz
2019-06-04 11:45 ` Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Andrey Konovalov
2019-06-08 3:51 ` Kees Cook
2019-06-10 17:53 ` Catalin Marinas
2019-06-10 18:07 ` Kees Cook
2019-06-10 18:53 ` Catalin Marinas
2019-06-10 20:36 ` Kees Cook
2019-06-11 14:57 ` Catalin Marinas
2019-06-11 17:09 ` Vincenzo Frascino
2019-06-12 9:32 ` Catalin Marinas
2019-06-12 11:52 ` Vincenzo Frascino [this message]
2019-06-11 17:09 ` Andrey Konovalov
2019-06-11 17:39 ` Catalin Marinas
2019-06-12 11:03 ` Andrey Konovalov
2019-06-12 11:04 ` Catalin Marinas
2019-06-03 16:55 ` [PATCH v16 03/16] lib, arm64: untag user pointers in strn*_user Andrey Konovalov
2019-06-08 3:48 ` Kees Cook
2019-06-11 20:06 ` Khalid Aziz
2019-06-03 16:55 ` [PATCH v16 04/16] mm: untag user pointers in do_pages_move Andrey Konovalov
2019-06-08 3:49 ` Kees Cook
2019-06-11 20:18 ` Khalid Aziz
2019-06-12 11:08 ` Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls Andrey Konovalov
2019-06-08 3:51 ` Kees Cook
2019-06-10 14:28 ` Catalin Marinas
2019-06-11 15:35 ` Andrey Konovalov
2019-06-11 17:44 ` Catalin Marinas
2019-06-12 11:13 ` Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 06/16] mm, arm64: untag user pointers in mm/gup.c Andrey Konovalov
2019-06-08 3:59 ` Kees Cook
2019-06-03 16:55 ` [PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-06-08 4:00 ` Kees Cook
2019-06-10 14:29 ` Catalin Marinas
2019-06-03 16:55 ` [PATCH v16 08/16] fs, arm64: untag user pointers in copy_mount_options Andrey Konovalov
2019-06-08 4:02 ` Kees Cook
2019-06-11 14:38 ` Andrey Konovalov
2019-06-12 11:36 ` Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 09/16] fs, arm64: untag user pointers in fs/userfaultfd.c Andrey Konovalov
2019-06-08 4:03 ` Kees Cook
2019-06-12 10:45 ` Catalin Marinas
2019-06-03 16:55 ` [PATCH v16 10/16] drm/amdgpu, arm64: untag user pointers Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 11/16] drm/radeon, arm64: untag user pointers in radeon_gem_userptr_ioctl Andrey Konovalov
2019-06-03 16:55 ` [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr() Andrey Konovalov
2019-06-03 17:46 ` Jason Gunthorpe
2019-06-04 12:18 ` Andrey Konovalov
2019-06-04 12:27 ` Jason Gunthorpe
2019-06-04 12:45 ` Andrey Konovalov
2019-06-04 13:02 ` Jason Gunthorpe
2019-06-04 13:09 ` Andrey Konovalov
2019-06-12 11:01 ` Catalin Marinas
2019-06-03 16:55 ` [PATCH v16 13/16] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-06-08 3:52 ` Kees Cook
2019-06-03 16:55 ` [PATCH v16 14/16] tee, arm64: untag user pointers in tee_shm_register Andrey Konovalov
2019-06-07 5:33 ` Jens Wiklander
2019-06-08 4:05 ` Kees Cook
2019-06-03 16:55 ` [PATCH v16 15/16] vfio/type1, arm64: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-06-08 3:58 ` Kees Cook
2019-06-12 10:38 ` Catalin Marinas
2019-06-03 16:55 ` [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2019-06-08 3:56 ` Kees Cook
2019-06-10 22:08 ` shuah
2019-06-11 15:01 ` Catalin Marinas
2019-06-11 17:18 ` Andrey Konovalov
2019-06-11 17:50 ` Catalin Marinas
2019-06-12 11:14 ` Andrey Konovalov
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