linux-kernel - Re: [RFC v7 15/41] richacl: Automatic Inheritance

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Message-ID: <20150923135544.GA27083@fieldses.org>
Date:	Wed, 23 Sep 2015 09:55:44 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Andreas Gruenbacher <agruenba@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-nfs@...r.kernel.org, linux-api@...r.kernel.org,
	linux-cifs@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [RFC v7 15/41] richacl: Automatic Inheritance

On Mon, Sep 21, 2015 at 09:51:46PM -0400, J. Bruce Fields wrote:
> On Mon, Sep 21, 2015 at 11:19:59PM +0200, Andreas Gruenbacher wrote:
> > 2015-09-18 20:40 GMT+02:00 J. Bruce Fields <bfields@...ldses.org>:
> > > On Sat, Sep 05, 2015 at 12:27:10PM +0200, Andreas Gruenbacher wrote:
> > >> Automatic Inheritance (AI) allows changes to the acl of a directory to
> > > In the above "file" sometimes means "any object" and somethings "a
> > > non-directory".  I can sort it out, but more consistent terminology
> > > would help.
> > 
> > Okay, I'll fix it.
> > 
> > >> Linux does not have a way of creating files without setting the file
> > >> permission bits, so all files created inside a directory with
> > >> RICHACL_AUTO_INHERIT set will have the RICHACL_PROTECTED flag set.  This
> > >> effectively disables Automatic Inheritance.
> > >>
> > >> Protocols which support creating files without specifying permissions
> > >> can explicitly clear the RICHACL_PROTECTED flag after creating a file
> > >> and reset the file masks to "undo" applying the create mode; see
> > >> richacl_compute_max_masks().  They should set the RICHACL_DEFAULTED
> > >> flag.  This is a workaround; a mechanism that would allow a process to
> > >> indicate to the kernel to ignore the create mode when there are
> > >> inherited permissions would fix this problem.
> > >
> > > Also, as you know: current nfsd has no way to create files without
> > > setting permissions.  And if we were to implement that it's unclear how
> > > many clients would actually use it (Windows clients are rare).  And of
> > > course Samba doesn't have the interfaces it would need.
> > >
> > > I think we should just drop this for now.  The rest of the richacl stuff
> > > is still useful without it.
> > 
> > Samba will hack around it and adjust the ACL after the create; that's
> > still better than not having Automatic Inheritance. Windows uses AI
> > all the time so AI is more important for Samba than for NFSv4.
> 
> Oh, OK, that makes sense.  Even just giving them a place to store the
> bits would be better than nothing.  So, ignore my objection there....

Oh, and

	Reviewed-by: J. Bruce Fields <bfields@...hat.com>

--b.
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