Hi BTRFS folks: In my organization, many use cases exist for a time-based honoring field for FS ACLs. I''ve done some brief research regarding this topic, but I was unable to find any reference to such a thing in any file system. I understand that a feature like time-based honoring for ACLs may arguably be something that should exist in higher layers (E.G. some document management system), but on the other hand, I see no real reason that an extra ACL field that would allow for time-based granting/removing of permissions to some user would be a problem. * The logic would go something like this (ACE means Access control Entry): If ACE.time = 0 or ACE.time > current_time; then Honor ACE Elif Ace.time < 0 and (current.time+ACE.time) > 0; then Honor ACE Else not honor ACE fi for uses like company-wide file servers, etc, a little feature like that could go very far in long-term management of file system permissions. You could easily and non-hackeshly temporarily grant access to file system objects, without having to makemodifications to applications, system utilities,or system libraries. The behavior could be easily controled by mount options (could be off by default) and a small utility or function of the standard file system''s utilities could allow for easy management of the value in the time fields (change, expire, etc). Of course, acurit time would then be crutial to system security, but today acurit time is crytical on servers anyway in most situations. Besides, it would definitly be an optional feature, enabled at the user''s choice. If we add a second field, then both expire time and activation time could be set for a given access control entry at the same time. In that case, negative values for the fields could indicate things like restrict access to ---, r-x, etc, regardless of the ACE''s actual content. Basically, it would be something like XFS''s mask entry, but applying to the ACE itself not the entire list. Any thoughts, suggestions, ideas? Am I just plain crazy? Thanks for the great work you''re doing. David Bruzos (Systems Administrator) 2831 Talleyrand Ave. Jacksonville, FL 32206 Office: (904) 357-3069 ________________________________________________________________________________________________ Please note that under Florida''s public records law (F.S. 668.6076), most written communications to or from the Jacksonville Port Authority are public records, available to the public and media upon request. Your email communications may therefore be subject to public disclosure. If you have received this email in error, please notify the sender by return email and delete immediately without forwarding to others. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Apr 26, 2012 at 03:30:39PM -0400, David Bruzos wrote:> Hi BTRFS folks: In my organization, many use cases exist for a > time-based honoring field for FS ACLs. I''ve done some brief research > regarding this topic, but I was unable to find any reference to such a > thing in any file system. I understand that a feature like time-based > honoring for ACLs may arguably be something that should exist in > higher layers (E.G. some document management system), but on the other > hand, I see no real reason that an extra ACL field that would allow > for time-based granting/removing of permissions to some user would be > a problem.One of the interesting thing about linux acls is the filesystems don''t really implement acls. We implement xattrs, and the higher layers stuff acls into them. In a few key spots we tell the higher layers how to do that, and we also call back into the higher layers for permission checks. This is a long way of saying the changes would have to happen in the generic acl code. This is a good thing, it will get much more review that way. I''d suggest posting this to linux-fsdevel. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Chris: Thank you for your very informative response. I will post the message to linux-fsdevel and see what they have to say about it. Any comments you would like to share regarding why something like what I suggested has apparently never been implemented? Again, thanks! David Bruzos (Systems Administrator) -----Original Message----- From: Chris Mason [mailto:chris.mason@oracle.com] Sent: Thursday, April 26, 2012 4:04 PM To: David Bruzos Cc: linux-btrfs@vger.kernel.org Subject: Re: Optionally enforced time-based ACLs for BTRFS On Thu, Apr 26, 2012 at 03:30:39PM -0400, David Bruzos wrote:> Hi BTRFS folks: In my organization, many use cases exist for a > time-based honoring field for FS ACLs. I''ve done some brief research > regarding this topic, but I was unable to find any reference to such a > thing in any file system. I understand that a feature like time-based > honoring for ACLs may arguably be something that should exist in > higher layers (E.G. some document management system), but on the other > hand, I see no real reason that an extra ACL field that would allow > for time-based granting/removing of permissions to some user would be > a problem.One of the interesting thing about linux acls is the filesystems don''t really implement acls. We implement xattrs, and the higher layers stuff acls into them. In a few key spots we tell the higher layers how to do that, and we also call back into the higher layers for permission checks. This is a long way of saying the changes would have to happen in the generic acl code. This is a good thing, it will get much more review that way. I''d suggest posting this to linux-fsdevel. -chris ________________________________________________________________________________________________ Please note that under Florida''s public records law (F.S. 668.6076), most written communications to or from the Jacksonville Port Authority are public records, available to the public and media upon request. Your email communications may therefore be subject to public disclosure. If you have received this email in error, please notify the sender by return email and delete immediately without forwarding to others. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Apr 26, 2012 at 05:27:12PM -0400, David Bruzos wrote:> Hi Chris: > Thank you for your very informative response. I will post the message to linux-fsdevel and see what they have to say about it. > > Any comments you would like to share regarding why something like what I suggested has apparently never been implemented?Most features in the kernel are based on customer demand. I think we just haven''t had enough people asking for it ;) -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html