From: Pavel Emelyanov <xemul@parallels.com>
To: Vasiliy Kulikov <segoon@openwall.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>, Pavel Machek <pavel@ucw.cz>,
Andrew Morton <akpm00@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"containers@lists.osdl.org" <containers@lists.osdl.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Kirill Shutemov <kirill@shutemov.name>,
James Bottomley <jbottomley@parallels.com>,
Nathan Lynch <ntl@pobox.com>, Zan Lynx <zlynx@acm.org>,
Daniel Lezcano <dlezcano@fr.ibm.com>, Tejun Heo <tj@kernel.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v12
Date: Wed, 14 Sep 2011 20:13:17 +0400 [thread overview]
Message-ID: <4E70D29D.20104@parallels.com> (raw)
In-Reply-To: <20110914160724.GA10612@albatros>
> No, I mean something else. Assume you have a task, which does the
> steps:
>
> 1) opens some sensitive file as root. This file is e.g. 0700.
>
> 2) mmaps the file via opened fd, either RO or RW.
>
> 3) closes fd.
>
> 4) drops root.
>
> Now it has a mapping of a privileged file, but cannot get fd of it
> anyhow. With map_files/ he may open his own /proc/$$/map_files/, pass
> ptrace() check, and get fd of the privileged file. He cannot explicitly
> open it as it is 0700, but he may open it via map_files/ and get RO/RW
> fd.
>
What is the problem here - the fact that we have some file considered to
be private be open-able by somebody else, or the fact that we can truncate
the file being mapped?
If the fist issue stands, then it also stands for /proc/pid/fd and thus we
don't introduce the new problem.
If the second, then it's not a problem as mm can handle this already.
Thanks,
Pavel
next prev parent reply other threads:[~2011-09-14 16:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-13 21:13 [patch 0/2] symlinks for mapped files in proc Cyrill Gorcunov
2011-09-13 21:14 ` [patch 1/2] fs, proc: Make proc_get_link to use dentry instead of inode Cyrill Gorcunov
2011-09-14 1:37 ` Kirill A. Shutemov
2011-09-13 21:14 ` [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v12 Cyrill Gorcunov
[not found] ` <20110914023428.GA4034@shutemov.name>
2011-09-14 5:54 ` Cyrill Gorcunov
2011-09-14 6:52 ` Andrew Morton
2011-09-14 10:56 ` Cyrill Gorcunov
2011-09-14 11:14 ` Pavel Machek
2011-09-14 11:39 ` Cyrill Gorcunov
2011-09-14 13:44 ` Cyrill Gorcunov
2011-09-14 14:48 ` Vasiliy Kulikov
2011-09-14 14:57 ` Vasiliy Kulikov
2011-09-14 16:00 ` Cyrill Gorcunov
2011-09-14 16:07 ` Vasiliy Kulikov
2011-09-14 16:13 ` Pavel Emelyanov [this message]
2011-09-14 16:21 ` Vasiliy Kulikov
2011-09-15 9:14 ` Cyrill Gorcunov
2011-09-15 9:27 ` Vasiliy Kulikov
2011-09-15 10:29 ` Cyrill Gorcunov
2011-09-15 10:56 ` Vasiliy Kulikov
2011-09-15 11:00 ` Cyrill Gorcunov
2011-09-15 20:19 ` Cyrill Gorcunov
2011-09-16 17:56 ` Vasiliy Kulikov
2011-09-16 18:07 ` Cyrill Gorcunov
2011-09-16 18:11 ` Vasiliy Kulikov
2011-09-16 18:26 ` Cyrill Gorcunov
2011-09-16 18:31 ` Kirill A. Shutemov
2011-09-16 18:40 ` Cyrill Gorcunov
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