From: Kees Cook <keescook@chromium.org>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Deepak Saxena <dsaxena@linaro.org>,
"arndb@arndb.de" <arndb@arndb.de>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 1/6] arm64: ptrace: add PTRACE_SET_SYSCALL
Date: Wed, 3 Sep 2014 11:34:41 -0700 [thread overview]
Message-ID: <CAGXu5j+FNa36EdLeZ16TMeGNmgw7F7A06MZZMhFQSKFNfQWrhg@mail.gmail.com> (raw)
In-Reply-To: <53FD6D7C.8030700@linaro.org>
On Tue, Aug 26, 2014 at 10:32 PM, AKASHI Takahiro
<takahiro.akashi@linaro.org> wrote:
> Kees,
>
>
> On 08/27/2014 02:46 AM, Will Deacon wrote:
>>
>> On Fri, Aug 22, 2014 at 01:19:13AM +0100, AKASHI Takahiro wrote:
>>>
>>> On 08/22/2014 01:47 AM, Kees Cook wrote:
>>>>
>>>> On Thu, Aug 21, 2014 at 3:56 AM, AKASHI Takahiro
>>>> <takahiro.akashi@linaro.org> wrote:
>>>>>
>>>>> To allow tracer to be able to change/skip a system call by re-writing
>>>>> a syscall number, there are several approaches:
>>>>>
>>>>> (1) modify x8 register with ptrace(PTRACE_SETREGSET), and handle this
>>>>> case
>>>>> later on in syscall_trace_enter(), or
>>>>> (2) support ptrace(PTRACE_SET_SYSCALL) as on arm
>>>>>
>>>>> Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to
>>>>> tracer as well as that secure_computing() expects a changed syscall
>>>>> number
>>>>> to be visible, especially case of -1, before this function returns in
>>>>> syscall_trace_enter(), we'd better take (2).
>>>>>
>>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>>>>
>>>>
>>>> Thanks, I like having this on both arm and arm64.
>>>
>>>
>>> Yeah, having this simplified the code of syscall_trace_enter() a bit, but
>>> also imposes some restriction on arm64, too.
>>>
>>> > I wonder if other archs should add this option too.
>>>
>>> Do you think so? I assumed that SET_SYSCALL is to be avoided if possible.
>>>
>>> I also think that SET_SYSCALL should take an extra argument for a return
>>> value
>>> just in case of -1 (or we have SKIP_SYSCALL?).
>>
>>
>> I think we should propose this as a new request in the generic ptrace
>> code.
>> We can have an architecture-hook for actually setting the syscall, and
>> allow
>> architectures to define their own implementation of the request so they
>> can
>> be moved over one by one.
>
>
> What do you think about this request?
That sounds fine -- it doesn't need to be part of this series. I was
just noticing this was a common issue across multiple architectures.
-Kees
--
Kees Cook
Chrome OS Security
next prev parent reply other threads:[~2014-09-03 18:34 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-21 8:56 [PATCH v6 0/6] arm64: add seccomp support AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 1/6] arm64: ptrace: add PTRACE_SET_SYSCALL AKASHI Takahiro
2014-08-21 16:47 ` Kees Cook
2014-08-22 0:19 ` AKASHI Takahiro
2014-08-26 17:46 ` Will Deacon
2014-08-27 5:32 ` AKASHI Takahiro
2014-09-03 18:34 ` Kees Cook [this message]
2014-08-21 8:56 ` [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call AKASHI Takahiro
2014-08-21 17:08 ` Kees Cook
2014-08-22 0:35 ` AKASHI Takahiro
2014-08-26 17:51 ` Will Deacon
2014-08-27 5:55 ` AKASHI Takahiro
2014-09-01 11:37 ` Will Deacon
2014-09-02 7:58 ` AKASHI Takahiro
2014-09-01 11:47 ` Russell King - ARM Linux
2014-09-02 8:47 ` AKASHI Takahiro
2014-09-02 9:16 ` Russell King - ARM Linux
2014-09-02 9:31 ` Russell King - ARM Linux
2014-09-05 10:08 ` AKASHI Takahiro
2014-10-01 11:08 ` AKASHI Takahiro
2014-10-03 15:23 ` Will Deacon
2014-10-06 8:04 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 3/6] asm-generic: add generic seccomp.h for secure computing mode 1 AKASHI Takahiro
2014-08-21 17:51 ` Kees Cook
2014-08-22 0:38 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 4/6] arm64: add seccomp syscall for compat task AKASHI Takahiro
2014-08-21 17:52 ` Kees Cook
2014-08-22 0:39 ` AKASHI Takahiro
2014-08-26 17:53 ` Will Deacon
2014-08-27 5:57 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 5/6] arm64: add SIGSYS siginfo " AKASHI Takahiro
2014-08-21 17:54 ` Kees Cook
2014-08-22 0:44 ` AKASHI Takahiro
2014-08-26 17:55 ` Will Deacon
2014-08-27 5:58 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 6/6] arm64: add seccomp support AKASHI Takahiro
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