Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags

From	Jeremy Allison <jra@samba.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags
Date	2016-12-06 22:40 +0100
Message-ID	<sLvCW-7rL-13@gated-at.bofh.it> (permalink)
References	(1 earlier) <sr4OZ-6OW-9@gated-at.bofh.it> <sJSNj-29y-21@gated-at.bofh.it> <sLunw-6LC-53@gated-at.bofh.it> <sLvtf-7oy-35@gated-at.bofh.it> <sLvtf-7oy-33@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Dec 06, 2016 at 10:25:22PM +0100, Miklos Szeredi wrote:
> On Tue, Dec 6, 2016 at 10:13 PM, Jeremy Allison <jra@samba.org> wrote:
> > On Tue, Dec 06, 2016 at 03:15:29PM -0500, J. Bruce Fields wrote:
> >> On Fri, Dec 02, 2016 at 10:57:42AM +0100, Miklos Szeredi wrote:
> >> > On Tue, Oct 11, 2016 at 2:50 PM, Andreas Gruenbacher
> >> > <agruenba@redhat.com> wrote:
> >> > > Normally, deleting a file requires MAY_WRITE access to the parent
> >> > > directory.  With richacls, a file may be deleted with MAY_DELETE_CHILD access
> >> > > to the parent directory or with MAY_DELETE_SELF access to the file.
> >> > >
> >> > > To support that, pass the MAY_DELETE_CHILD mask flag to inode_permission()
> >> > > when checking for delete access inside a directory, and MAY_DELETE_SELF
> >> > > when checking for delete access to a file itself.
> >> > >
> >> > > The MAY_DELETE_SELF permission overrides the sticky directory check.
> >> >
> >> > And MAY_DELETE_SELF seems totally inappropriate to any kind of rename,
> >> > since from the point of view of the inode we are not doing anything at
> >> > all.  The modifications are all in the parent(s), and that's where the
> >> > permission checks need to be.
> >>
> >> I'm having a hard time finding an authoritative reference here (Samba
> >> people might be able to help), but my understanding is that Windows
> >> gives this a meaning something like "may I delete a link to this file".
> >>
> >> (And not even "may I delete the *last* link to this file", which might
> >> also sound more logical.)
> >
> > I just did a recent patch here. In Samba we now check for
> > SEC_DIR_ADD_FILE/SEC_DIR_ADD_SUBDIR on the target directory
> > (depending on if the object being moved is a file or dir).
> 
> And MAY_DELETE_SELF as well, for rename?  That's really counterintuitive for me.

Yeah on the source handle we insist on DELETE_ACCESS|FILE_WRITE_ATTRIBUTES
permissions also.

Thread

Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD  permission flags Miklos Szeredi <miklos@szeredi.hu> - 2016-12-02 11:00 +0100
  Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD  permission flags "J. Bruce Fields" <bfields@fieldses.org> - 2016-12-06 21:20 +0100
    Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD  permission flags Miklos Szeredi <miklos@szeredi.hu> - 2016-12-06 22:30 +0100
      Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD  permission flags Jeremy Allison <jra@samba.org> - 2016-12-06 22:40 +0100
    Re: [PATCH v27 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD  permission flags Jeremy Allison <jra@samba.org> - 2016-12-06 22:40 +0100

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