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

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Date:	Mon, 21 Sep 2015 23:19:59 +0200
From:	Andreas Gruenbacher <agruenba@...hat.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
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

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.

Thanks,
Andreas
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