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From: Jann Horn <jannh@google.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-ext4@vger.kernel.org, Linux API <linux-api@vger.kernel.org>,
	linux-man@vger.kernel.org
Subject: Re: [PATCH] ioctl_getfsmap.2: document the GETFSMAP ioctl
Date: Mon, 8 May 2017 20:47:56 +0200	[thread overview]
Message-ID: <CAG48ez3e+2VuvjtEfJuMujEo6PWBO3z8oM-otN2juq96jKdjCw@mail.gmail.com> (raw)
In-Reply-To: <20170508184112.GJ5973@birch.djwong.org>

On Mon, May 8, 2017 at 8:41 PM, Darrick J. Wong <darrick.wong@oracle.com> wrote:
> On Mon, May 08, 2017 at 12:17:53AM +0200, Jann Horn wrote:
>> On Sun, May 7, 2017 at 5:58 PM, Darrick J. Wong <darrick.wong@oracle.com> wrote:
>> > Document the new GETFSMAP ioctl that returns the physical layout of a
>> > (disk-based) filesystem.
[...]
>> Also: From a quick glance at the XFS implementation, I don't see any
>> privilege checks. Am I missing something, or does this API permit an
>> unprivileged user to determine the number of physical blocks allocated
>> for any inode, even for inodes the user can't ordinarily see in any
>> way?
>
> Correct.

What's your reasoning for why this doesn't create any new potential
security issues? For example, as far as I can tell, this would permit
an unprivileged user to determine with high probability whether a set
of large files with known sizes is stored anywhere in the filesystem, even
across containers or so.

  reply	other threads:[~2017-05-08 18:48 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-07 15:58 [PATCH] ioctl_getfsmap.2: document the GETFSMAP ioctl Darrick J. Wong
2017-05-07 22:17 ` Jann Horn
2017-05-08 18:41   ` Darrick J. Wong
2017-05-08 18:41     ` Darrick J. Wong
2017-05-08 18:47     ` Jann Horn [this message]
2017-05-08 20:47       ` Darrick J. Wong
2017-05-08 20:47         ` Darrick J. Wong
2017-05-08 22:54         ` Jann Horn
2017-05-09  1:53           ` Darrick J. Wong
2017-05-09  1:53             ` Darrick J. Wong
2017-05-09 21:17             ` Eric Biggers
2017-05-09 21:17               ` Eric Biggers
2017-05-10 16:38               ` Theodore Ts'o
2017-05-10 19:27                 ` Eric W. Biederman
2017-05-10 20:14                   ` Darrick J. Wong
2017-05-10 20:14                     ` Darrick J. Wong
2017-05-11  5:10                     ` Eric Biggers
2017-05-11  5:10                       ` Eric Biggers
2017-05-14  1:41                       ` Andreas Dilger
2017-05-14  4:25                         ` Darrick J. Wong
2017-05-14  4:25                           ` Darrick J. Wong
2017-05-14 13:56                         ` Andy Lutomirski
2017-05-14 13:56                           ` Andy Lutomirski
2017-05-18  2:04                           ` Darrick J. Wong
2017-05-18  2:04                             ` Darrick J. Wong
  -- strict thread matches above, loose matches on Subject: below --
2017-02-18  1:17 [RFC PATCH v6 0/8] vfs/xfs/ext4: GETFSMAP support Darrick J. Wong
2017-02-21 22:14 ` [PATCH] ioctl_getfsmap.2: document the GETFSMAP ioctl Darrick J. Wong

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