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From: Cyrill Gorcunov <gorcunov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: "Kirill A. Shutemov"
	<kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>,
	Calvin Owens <calvinowens-b10kYP2dOMg@public.gmane.org>,
	Alexey Dobriyan
	<adobriyan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"Eric W. Biederman"
	<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
	Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	"Kirill A. Shutemov"
	<kirill.shutemov-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	Peter Feiner <pfeiner-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Grant Likely
	<grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>,
	Siddhesh Poyarekar
	<siddhesh.poyarekar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	kernel-team-b10kYP2dOMg@public.gmane.org,
	Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Subject: Re: [RFC][PATCH v2] procfs: Always expose /proc/<pid>/map_files/ and make it readable
Date: Tue, 27 Jan 2015 10:23:23 +0300	[thread overview]
Message-ID: <20150127072323.GI651@moon> (raw)
In-Reply-To: <20150126225023.df63f6ca.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>

On Mon, Jan 26, 2015 at 10:50:23PM -0800, Andrew Morton wrote:
> On Tue, 27 Jan 2015 09:46:47 +0300 Cyrill Gorcunov <gorcunov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> > > There's one other problem here: we're assuming that the map_files
> > > implementation doesn't have bugs.  If it does have bugs then relaxing
> > > permissions like this will create new vulnerabilities.  And the
> > > map_files implementation is surprisingly complex.  Is it bug-free?
> > 
> > I didn't find any bugs in map-files (and we use it for long time already)
> > so I think it is safe.
> 
> You've been using map_files the way it was supposed to be used so no,
> any bugs won't show up.  What happens if you don your evil black hat
> and use map_files in ways that weren't anticipated?  Attack it?

Hard to say, Andrew. If I found a way to exploit this feature for
bad purpose for sure I would patch it out. At the moment I don't
see any. Touching another process memory via file descriptor
allows one to modify its contents but you have to be granted
ptrace-may-access which i consider as enough for security.

  parent reply	other threads:[~2015-01-27  7:23 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1421194829-28696-1-git-send-email-calvinowens@fb.com>
     [not found] ` <20150114152501.GB9820@node.dhcp.inet.fi>
     [not found]   ` <20150114153323.GF2253@moon>
     [not found]     ` <20150114204653.GA26698@mail.thefacebook.com>
     [not found]       ` <20150114211613.GH2253@moon>
     [not found]         ` <20150122024554.GB23762@mail.thefacebook.com>
     [not found]           ` <20150124031544.GA1992748@mail.thefacebook.com>
2015-01-26 12:47             ` [RFC][PATCH v2] procfs: Always expose /proc/<pid>/map_files/ and make it readable Kirill A. Shutemov
     [not found]               ` <20150126124731.GA26916-nhfs4B5ZimeFUdmeq17FyvUpdFzICT1y@public.gmane.org>
2015-01-26 21:00                 ` Cyrill Gorcunov
2015-01-26 23:43                   ` Andrew Morton
     [not found]                     ` <20150126154346.c63c512e5821e9e0ea31f759-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-01-27  0:15                       ` Kees Cook
     [not found]                         ` <CAGXu5jLDkg0hJSMm3CdoO-77yiK5GQWHSe3+1h7mq76LERpNBA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-27  7:37                           ` Cyrill Gorcunov
2015-01-27 19:53                             ` Kees Cook
     [not found]                               ` <CAGXu5jJFFib7F7uKYgvX4ecyMnbincd22FaO_bFy=VRVKdFbvA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-27 21:35                                 ` Cyrill Gorcunov
2015-01-27 21:46                               ` Pavel Emelyanov
2015-01-27  0:19                       ` Kirill A. Shutemov
2015-01-27  6:46                       ` Cyrill Gorcunov
2015-01-27  6:50                         ` Andrew Morton
     [not found]                           ` <20150126225023.df63f6ca.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-01-27  7:23                             ` Cyrill Gorcunov [this message]
2015-01-28  4:38                     ` Calvin Owens
     [not found]                       ` <20150128043832.GA2266262-ZEWhMxyTXSP95iwofa7G/laTQe2KTcn/@public.gmane.org>
2015-01-30  1:30                         ` Kees Cook
     [not found]                           ` <CAGXu5j+wa2-CCGaktPzDec=HF0CizP__HVVjZKcjGuJJOvLFyg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-31  1:58                             ` Calvin Owens
2015-02-02 14:01                               ` Austin S Hemmelgarn
     [not found]                                 ` <54CF832A.7010707-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-02-04  3:53                                   ` Calvin Owens
2015-02-02 20:16                               ` Andy Lutomirski
     [not found]                                 ` <CALCETrUufe3USocUDpkBdwx6SyGKVgVUTh4rg2H9Xn91u+6iHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-02-04  3:28                                   ` Calvin Owens

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