[RFC] POSIX ACL kernel infrastructure

[Andreas Gruenbacher <agruen@suse.de>]

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Hello,

I want to propose adding some infrastructure to the VFS for POSIX ACL 
ssupport. There are already implementations for XFS and Ext2/Ext3; ReiserFS 
is to follow soon.

The design is as follows: POSIX ACLs are passed between the kernel and user 
space as Extended Attributes. The patches I've mentioned are doing exactly 
that. The filesystems are responsible for handling ACLs; they are not limited 
to POSIX ACLs.
   Filesystems may choose to cache/manipulate ACLs in the kernel internal 
format that this patch implements, or differently. In any case they should 
implement the get_posix_acl and set_posix_acl inode operations if mapping 
between native filesystem ACLs and POSIX ACLs makes sense.
   Other parts of the kernel (such as nfsd) can use the get_posix_acl and 
set_posix_acl inode operations to manipulate POSIX ACLs. This is currently 
required for nfsd, since nfsd must mask off permissions depending on the 
protocol and client version (a module parameter controls this behavior).

(This patch also requires the ENOTSUP and MS_NOUMASK issues to be resolved.
I've posted messages on these topics to linux-kernel before, and I will send 
copies to linux-fsdevel.)

Regards,
Andreas.

------------------------------------------------------------------
 Andreas Gruenbacher                                SuSE Linux AG
 mailto:agruen@suse.de                     Deutschherrnstr. 15-19
 http://www.suse.de/                   D-90429 Nuernberg, Germany

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