Re: [PATCH] arm64: kasan: instrument user memory access API

Path	csiph.com!feeder.erje.net!1.us.feeder.erje.net!newsfeed.fsmpi.rwth-aachen.de!newsfeed.straub-nv.de!news.unit0.net!news.panservice.it!bofh.it!news.nic.it!robomod
From	"Shi, Yang" <yang.shi@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] arm64: kasan: instrument user memory access API
Date	Fri, 27 May 2016 18:40:02 +0200
Message-ID	<rDsXM-5NX-31@gated-at.bofh.it> (permalink)
References	<rD8Z3-1RG-7@gated-at.bofh.it> <rDnOq-2G0-17@gated-at.bofh.it>
Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding; bh=hJR0DuQHC0ayCxD4nEuPwwCNrNHs586oE/HYZNlalAs=; b=NY2LpA2L0RGecrUlx3A2F8UkNk+8R+Qfm+bvE8Wr4A74T7rD7ptioGgCCmF1R3hPBF xbX8NUDRn5i35WxzRmsKuC/QUsDhvE6b/L6DW7qH8y1AzkD9xR3OSRHtFXQvPAcIesWU KHtf8yrqAD5JFFemC9VQaKj/KanDTkzMPxz2c=
X-Google-Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=hJR0DuQHC0ayCxD4nEuPwwCNrNHs586oE/HYZNlalAs=; b=Ep69kIN8OEBPKEboyKi+Ec6msbD2fz+O8T+XbIUxtwcv3/dFKE5VN/a8BU27XXmTDe YyDOicWXBH03svNPCYOX89pE4ndW7WqVLj/lM4APha579adpZvEXUSzbTKhnKXygzcqK TRxtUFRF5xPfNV0i9JIg4BVSdydM3OkzVtwsh+x7lxEFWxslJiSqhq8moonyx4Dy4hnH ED7eFn9CNkQ5BfnPxh69yQBM5gJD1NXXBKfbbcSig4ME2PMDuoX1SQQ10Y7uBtbyGOyU Q36hEI57mfE1Z1tKFj3J1aPXPug5ZYE91ERIpxrqy4dkb6R8z9jZ4NvAWBAF5nkAuBSn 1zow==
X-Gm-Message-State	ALyK8tI1dVVRQeLS3KmXfVv1VQ2vFW0xESrmEWQqO9XtiU7jP4DcNUfBVIleyEsiqcTtNQ4o
X-Received	by 10.66.54.35 with SMTP id g3mr24234921pap.30.1464366845313; Fri, 27 May 2016 09:34:05 -0700 (PDT)
User-Agent	Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0
MIME-Version	1.0
Content-Type	text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding	7bit
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	45
Organization	linux.* mail to news gateway
X-Original-Cc	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linaro-kernel@lists.linaro.org
X-Original-Date	Fri, 27 May 2016 09:34:03 -0700
X-Original-Message-ID	<cea39367-65b6-62df-7e4c-57ae1ce36dcc@linaro.org>
X-Original-References	<1464288231-11304-1-git-send-email-yang.shi@linaro.org> <57482930.6020608@virtuozzo.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1408175

Show key headers only | View raw

On 5/27/2016 4:02 AM, Andrey Ryabinin wrote:
>
>
> On 05/26/2016 09:43 PM, Yang Shi wrote:
>> The upstream commit 1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef
>> ("x86/kasan: instrument user memory access API") added KASAN instrument to
>> x86 user memory access API, so added such instrument to ARM64 too.
>>
>> Tested by test_kasan module.
>>
>> Signed-off-by: Yang Shi <yang.shi@linaro.org>
>> ---
>>  arch/arm64/include/asm/uaccess.h | 18 ++++++++++++++++--
>>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> Please, cover __copy_from_user() and __copy_to_user() too.
> Unlike x86, your patch doesn't instrument these two.

I should elaborated this in my review. Yes, I did think about it, but 
unlike x86, __copy_to/from_user are implemented by asm code on ARM64. If 
I add kasan_check_read/write into them, I have to move the registers 
around to prepare the parameters for kasan calls, then restore them 
after the call, for example the below code for __copy_to_user:

         mov     x9, x0
         mov     x10, x1
         mov     x11, x2
         mov     x0, x10
         mov     x1, x11
         bl      kasan_check_read
         mov     x0, x9
         mov     x1, x10

So, I'm wondering if it is worth or not since __copy_to/from_user are 
just called at a couple of places, i.e. sctp, a couple of drivers, etc 
and not used too much. Actually, I think some of them could be replaced 
by __copy_to/from_user_inatomic.

Any idea is appreciated.

Thanks,
Yang

>

Thread

[PATCH] arm64: kasan: instrument user memory access API Yang Shi <yang.shi@linaro.org> - 2016-05-26 21:20 +0200
  Re: [PATCH] arm64: kasan: instrument user memory access API Andrey Ryabinin <aryabinin@virtuozzo.com> - 2016-05-27 13:10 +0200
    Re: [PATCH] arm64: kasan: instrument user memory access API "Shi, Yang" <yang.shi@linaro.org> - 2016-05-27 18:40 +0200
      Re: [PATCH] arm64: kasan: instrument user memory access API Mark Rutland <mark.rutland@arm.com> - 2016-05-27 19:50 +0200
        Re: [PATCH] arm64: kasan: instrument user memory access API "Shi, Yang" <yang.shi@linaro.org> - 2016-05-27 20:10 +0200
  Re: [PATCH] arm64: kasan: instrument user memory access API Mark Rutland <mark.rutland@arm.com> - 2016-05-27 14:40 +0200

csiph-web