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[46.53.201.92]) by smtp.gmail.com with ESMTPSA id x15sm6306508wrs.27.2018.12.14.07.44.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Dec 2018 07:44:39 -0800 (PST) Date: Fri, 14 Dec 2018 18:44:36 +0300 From: Alexey Dobriyan To: =?utf-8?B?56iL5rSL?= Cc: Andrew Morton , David Howells , "Peter Zijlstra (Intel)" , Al Viro , Johannes Weiner , Davidlohr Bueso , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: > [PATCH] Security: Handle hidepid option correctly Message-ID: <20181214154436.GA16772@avx2> References: <18d54cd3edbf4fd3a7c01962f41ead58@cnbox5.mioffice.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 05, 2018 at 03:26:04PM +0800, 程洋 wrote: > Anyone who can review my patch? > > 程洋 于2018年11月30日周五 上午10:34写道： > > > > Here is an article illustrates the details. > > https://medium.com/@topjohnwu/from-anime-game-to-android-system-security-vulnerability-9b955a182f20 > > > > And There is a similar fix on kernel-4.4: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=99663be772c827b8f5f594fe87eb4807be1994e5 > > > > Q: Other filesystems parse the options from fill_super(). Is proc special in some fashion? > > A: According to my research, start_kernel will call proc_mount first, and initialize sb->s_root before any userspace process runs. If others want to mount it, all options will be ignored. > > AOSP change here: https://android-review.googlesource.com/c/platform/system/core/+/181345/4/init/init.cpp > > At first I though we should mount it with MS_REMOUNT flag. But kernel will crash if we did this. This is not true: /proc is mounted by userspace (and it is easy to see from the fact that proc_mount() is not called from kernel anywhere). hidepid= in its current form is misdesigned, so might as well not bother changing anything. IIRC there were(?) patches to make it per-mount.