Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in s_user_ns

From	Theodore Ts'o <tytso@mit.edu>
Newsgroups	linux.kernel
Subject	Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in s_user_ns
Date	2015-12-05 00:20 +0100
Message-ID	<qC7NT-MQ-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <qBhPl-FC-53@gated-at.bofh.it> <qC43D-6Pk-11@gated-at.bofh.it> <qC4Q2-7mV-17@gated-at.bofh.it> <qC4Q2-7mV-15@gated-at.bofh.it> <qC5sK-7Aa-7@gated-at.bofh.it>
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On Fri, Dec 04, 2015 at 02:45:32PM -0600, Seth Forshee wrote:
> On Fri, Dec 04, 2015 at 02:07:36PM -0600, Serge E. Hallyn wrote:
> > Heh, I was looking over http://www.gossamer-threads.com/lists/linux/kernel/103611
> > a little while ago :)  The same question was asked 16 years ago.  Apparently
> > the answer then was that it was easier than fixing the code.
> 
> So it seems then that either it still isn't safe and so unprivileged
> users shouldn't be allowed to do it at all, or else it's safe and we
> should drop the requirement completely. I can't say which is right,
> unfortunately.

It may not have been safe 16 years agoo, but giving invalid arguments
to FIBMAP is safe for ext4 and ext2.  This is the sort of thing that
tools like trinity should and does test for, so I think it should be
fine to remove the root check for FIBMAP.

							- Ted
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Thread

[PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in s_user_ns Seth Forshee <seth.forshee@canonical.com> - 2015-12-02 16:50 +0100
  Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns "Serge E. Hallyn" <serge@hallyn.com> - 2015-12-04 21:10 +0100
    Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns Seth Forshee <seth.forshee@canonical.com> - 2015-12-04 21:50 +0100
      Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns Theodore Ts'o <tytso@mit.edu> - 2015-12-05 00:20 +0100
        Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns "Serge E. Hallyn" <serge.hallyn@ubuntu.com> - 2015-12-05 00:50 +0100
          Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns Seth Forshee <seth.forshee@canonical.com> - 2015-12-05 07:20 +0100
        Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in s_user_ns Andreas Dilger <adilger@dilger.ca> - 2015-12-05 01:10 +0100
  Re: [PATCH 14/19] fs: Permit FIBMAP for users with CAP_SYS_RAWIO in  s_user_ns Theodore Ts'o <tytso@mit.edu> - 2015-12-04 21:10 +0100

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