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Re: [PATCH v8 00/41] Richacls

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  Re: [PATCH v8 00/41] Richacls Christoph Hellwig <hch@infradead.org> - 2015-10-06 12:00 +0200
    Re: [PATCH v8 00/41] Richacls Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-06 15:20 +0200
      Re: [PATCH v8 00/41] Richacls Andreas Dilger <adilger@dilger.ca> - 2015-10-06 22:30 +0200
        Re: [PATCH v8 00/41] Richacls Steve French <smfrench@gmail.com> - 2015-10-06 23:00 +0200
        Re: [PATCH v8 00/41] Richacls Christoph Hellwig <hch@infradead.org> - 2015-10-07 10:00 +0200
          Re: [PATCH v8 00/41] Richacls Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-07 15:40 +0200
            Re: [PATCH v8 00/41] Richacls Steve French <smfrench@gmail.com> - 2015-10-07 17:20 +0200

#1240332 — Re: [PATCH v8 00/41] Richacls

On Mon, Oct 05, 2015 at 02:58:36PM -0400, Austin S Hemmelgarn wrote:
> I think the point is that a new VFS feature that is easy to integrate in
> multiple filesystems should have support for those filesystems.  A decade
> ago, just having ext* support would probably have been fine, but these days,
> XFS, BTRFS, and F2FS are used just as much (if not more) on production
> systems as ext4, and having support for them right from the start would
> significantly help with adoption of richacls.

That's one reason.  The other is that actually wiring it up for more
than a single consumer shows its actually reasonable generic.  I don't
want to end up with a situration like Posix ACLs again where different
file systems using different on disk formats again.
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#1240430

On Tue, Oct 6, 2015 at 11:49 AM, Christoph Hellwig <hch@infradead.org> wrote:
> On Mon, Oct 05, 2015 at 02:58:36PM -0400, Austin S Hemmelgarn wrote:
>> I think the point is that a new VFS feature that is easy to integrate in
>> multiple filesystems should have support for those filesystems.  A decade
>> ago, just having ext* support would probably have been fine, but these days,
>> XFS, BTRFS, and F2FS are used just as much (if not more) on production
>> systems as ext4, and having support for them right from the start would
>> significantly help with adoption of richacls.
>
> That's one reason.  The other is that actually wiring it up for more
> than a single consumer shows its actually reasonable generic.

The filesystem interface now is the same as for POSIX ACLs, used by a
dozen or so filesystems already.

>  I don't want to end up with a situration like Posix ACLs again where
> different file systems using different on disk formats again.

Any file system could choose a different on-disk format than the one
that ext4 currently uses, but I don't see a reason why any should.
Apart from uid / gid mappings that is the same as the user-space xattr
format. Network file systems like NFSv4 and CIFS with their predefined
over-the-wire formats obviously are another story.

Thanks,
Andreas
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#1240970

[Multipart message — attachments visible in raw view] — view raw

On Oct 6, 2015, at 7:12 AM, Andreas Gruenbacher <agruenba@redhat.com> wrote:
> 
> On Tue, Oct 6, 2015 at 11:49 AM, Christoph Hellwig <hch@infradead.org> wrote:
>> On Mon, Oct 05, 2015 at 02:58:36PM -0400, Austin S Hemmelgarn wrote:
>>> I think the point is that a new VFS feature that is easy to integrate in
>>> multiple filesystems should have support for those filesystems.  A decade
>>> ago, just having ext* support would probably have been fine, but these days,
>>> XFS, BTRFS, and F2FS are used just as much (if not more) on production
>>> systems as ext4, and having support for them right from the start would
>>> significantly help with adoption of richacls.
>> 
>> That's one reason.  The other is that actually wiring it up for more
>> than a single consumer shows its actually reasonable generic.
> 
> The filesystem interface now is the same as for POSIX ACLs, used by a
> dozen or so filesystems already.
> 
>> I don't want to end up with a situration like Posix ACLs again where
>> different file systems using different on disk formats again.
> 
> Any file system could choose a different on-disk format than the one
> that ext4 currently uses, but I don't see a reason why any should.
> Apart from uid / gid mappings that is the same as the user-space xattr
> format. Network file systems like NFSv4 and CIFS with their predefined
> over-the-wire formats obviously are another story.

And any disk filesystems that have their own non-POSIX ACLs, such as HFS, NTFS, ZFS would presumably also need to map the in-kernel Richacl format to their on-disk format.

Cheers, Andreas

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#1240995

On Tue, Oct 6, 2015 at 3:26 PM, Andreas Dilger <adilger@dilger.ca> wrote:
> On Oct 6, 2015, at 7:12 AM, Andreas Gruenbacher <agruenba@redhat.com> wrote:
>>
>> On Tue, Oct 6, 2015 at 11:49 AM, Christoph Hellwig <hch@infradead.org> wrote:
>>> On Mon, Oct 05, 2015 at 02:58:36PM -0400, Austin S Hemmelgarn wrote:
>>>> I think the point is that a new VFS feature that is easy to integrate in
>>>> multiple filesystems should have support for those filesystems.  A decade
>>>> ago, just having ext* support would probably have been fine, but these days,
>>>> XFS, BTRFS, and F2FS are used just as much (if not more) on production
>>>> systems as ext4, and having support for them right from the start would
>>>> significantly help with adoption of richacls.
>>>
>>> That's one reason.  The other is that actually wiring it up for more
>>> than a single consumer shows its actually reasonable generic.
>>
>> The filesystem interface now is the same as for POSIX ACLs, used by a
>> dozen or so filesystems already.
>>
>>> I don't want to end up with a situration like Posix ACLs again where
>>> different file systems using different on disk formats again.
>>
>> Any file system could choose a different on-disk format than the one
>> that ext4 currently uses, but I don't see a reason why any should.
>> Apart from uid / gid mappings that is the same as the user-space xattr
>> format. Network file systems like NFSv4 and CIFS with their predefined
>> over-the-wire formats obviously are another story.
>
> And any disk filesystems that have their own non-POSIX ACLs, such as HFS, NTFS, ZFS would presumably also need to map the in-kernel Richacl format to their on-disk format.

Will be interesting to see whether in the long run can have some
common code in NTFS, CIFS/SMB3 (and even NFSv4.x) ACL parsing since
their formats are quite closely related



-- 
Thanks,

Steve
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#1241213

On Tue, Oct 06, 2015 at 02:26:09PM -0600, Andreas Dilger wrote:
> And any disk filesystems that have their own non-POSIX ACLs, such as HFS, NTFS, ZFS would presumably also need to map the in-kernel Richacl format to their on-disk format.

No, we did this mistake with Posix ACLs, and we're not going to repeat
it here.  Filesystems with their own slightly different ACLs must not
reuse the interface.
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#1241498

On Wed, Oct 7, 2015 at 9:50 AM, Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Oct 06, 2015 at 02:26:09PM -0600, Andreas Dilger wrote:
>> And any disk filesystems that have their own non-POSIX ACLs, such as HFS, NTFS, ZFS would presumably also need to map the in-kernel Richacl format to their on-disk format.
>
> No, we did this mistake with Posix ACLs, and we're not going to repeat
> it here.  Filesystems with their own slightly different ACLs must not
> reuse the interface.

Well, things may not be quite as clearly delineated. We currently have
code in nfsd for mapping between NFSv4 ACLs on the wire and POSIX ACLs
on local file systems. This mapping is problematic because of the
semantic differences between NFSv4 ACLs and POSIX ACLs (different sets
of permissions, access and default acl vs. inheritance flags,
different permission check algorithm). I wish we could have avoided
that.

Richacls are designed to support NFSv4 ACLs on top of POSIX systems.
This means that they should obviously be supported by the NFSv4 server
and client (see the patches) and by the common local filesystems.

ACLs on NTFS and ZFS mostly fit into the same model. The big remaining
difference there is how users and groups are identified: NTFS used
SIDs (https://en.wikipedia.org/wiki/Security_Identifier); ZFS could be
said to use a hybrid UID / GID / SID model. Exposing those ACLs as
richacls would make sense if we can find a clean way of handling this
aspect.

HFS ACLs have sufficiently different semantics (the user.group tuples)
that representing them as richacls wouldn't make sense.

Thanks,
Andreas
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#1241589

On Wed, Oct 7, 2015 at 8:38 AM, Andreas Gruenbacher <agruenba@redhat.com> wrote:
> On Wed, Oct 7, 2015 at 9:50 AM, Christoph Hellwig <hch@infradead.org> wrote:
>> On Tue, Oct 06, 2015 at 02:26:09PM -0600, Andreas Dilger wrote:
>>> And any disk filesystems that have their own non-POSIX ACLs, such as HFS, NTFS, ZFS would presumably also need to map the in-kernel Richacl format to their on-disk format.
>>
>> No, we did this mistake with Posix ACLs, and we're not going to repeat
>> it here.  Filesystems with their own slightly different ACLs must not
>> reuse the interface.
>
> Well, things may not be quite as clearly delineated. We currently have
> code in nfsd for mapping between NFSv4 ACLs on the wire and POSIX ACLs
> on local file systems. This mapping is problematic because of the
> semantic differences between NFSv4 ACLs and POSIX ACLs (different sets
> of permissions, access and default acl vs. inheritance flags,
> different permission check algorithm). I wish we could have avoided
> that.
>
> Richacls are designed to support NFSv4 ACLs on top of POSIX systems.
> This means that they should obviously be supported by the NFSv4 server
> and client (see the patches) and by the common local filesystems.
>
> ACLs on NTFS and ZFS mostly fit into the same model. The big remaining
> difference there is how users and groups are identified: NTFS used
> SIDs (https://en.wikipedia.org/wiki/Security_Identifier); ZFS could be
> said to use a hybrid UID / GID / SID model. Exposing those ACLs as
> richacls would make sense if we can find a clean way of handling this
> aspect.

Samba (e.g. winbind service) has mapping libraries for mapping SIDs to
UIDs (CIFS ACLs already have the same issue of SID to UID mapping
which we handle with upcalls) and Samba has various pluggable ways to
handle UID mapping and is easily extensible.  Similarly NFSv4 ACLs,
although closely related to CIFS/NTFS ACLs have to be map usernames to
uids.

-- 
Thanks,

Steve
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