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

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Message-ID: <20150922015146.GA15960@fieldses.org>
Date:	Mon, 21 Sep 2015 21:51:46 -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 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....

--b.
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