From: David Herrmann <dh.herrmann@gmail.com>
To: Michael Tirado <mtirado418@gmail.com>
Cc: linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] mm/shmem.c: Add new seal to memfd: F_SEAL_WRITE_NONCREATOR
Date: Fri, 17 Apr 2015 12:48:44 +0200 [thread overview]
Message-ID: <CANq1E4RebX=feEtgpHa4v_C_PkKwDmDWG+jm98kUUj5yYV4ipg@mail.gmail.com> (raw)
In-Reply-To: <20150417002847.1f5febf7@yak.slack>
Hi
On Fri, Apr 17, 2015 at 6:28 AM, Michael Tirado <mtirado418@gmail.com> wrote:
> On Thu, 16 Apr 2015 14:01:07 +0200
> David Herrmann <dh.herrmann@gmail.com> wrote:
>> The same functionality of F_SEAL_WRITE_NONCREATOR can be achieved by
>> opening /proc/self/fd/<num> with O_RDONLY. Just pass that read-only FD
>> to your peers but retain the writable one. But note that you must
>> verify your peers do not have the same uid as you do, otherwise they
>> can just gain a writable descriptor by opening /proc/self/fd/<num>
>> themselves.
>
> My peers may be any uid,
Where's the problem? Just pass the read-only file-descriptor to your
peers and make sure the access-mode of the memfd is 0600. No other
user will be able to gain a writable file-descriptor, but you.
Thanks
David
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next prev parent reply other threads:[~2015-04-17 10:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-16 7:23 Michael Tirado
2015-04-16 8:14 ` Konstantin Khlebnikov
2015-04-16 12:01 ` David Herrmann
2015-04-17 4:28 ` Michael Tirado
2015-04-17 10:48 ` David Herrmann [this message]
2015-04-17 22:45 ` Michael Tirado
2015-04-18 12:13 ` David Herrmann
2015-04-17 4:18 ` Michael Tirado
2015-04-28 13:28 ` [PATCH] mm/shmem.c: Add new seal to memfd: F_SEAL_WRITE_PEER Michael Tirado
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