Re: cp: when are ACLs copied?

[Pádraig Brady]

On 11/23/2012 09:02 AM, Bernhard Voelker wrote:
> As far as I understand the texi documentation, "cp -p" and "cp --preserve"
> copy the ACLs (because they belong to the 'mode' which is included in the
> default 'mode,owner,timestamps'):
>
>    ‘mode’
>    Preserve the file mode bits and access control lists.
>
> But reading further, this becomes unclear again:
>
>    ‘xattr’
>    Preserve extended attributes of the file, or fail with full diagnostics.
>    If cp is built without xattr support, ignore this option. If SELinux context,
>    ACLs or Capabilities are implemented using xattrs, they are preserved by this
>    option as well.
>
> Does that mean, that ACLs are not copied with "cp -p" on SELinux systems,

no...

> and that you'd need either "cp --pres=owner,mode,timestamps,xattr" or
> "cp --pres=all" on such systems? Doesn't sound much consistent ...

It means that since xattrs are often used to store ACLs, SELinux contexts
and capabilities etc., by specifying --preserve=xattr you may be implicitly
copying those, even if you didn't specify --preserve=mode or --preserve=context

> And finally, what does the condition "If SELinux context" mean exactly?
> a) if SELinux support is compiled into cp, or
> b) if the system has SELinux enabled?

c) There are SElinux xattrs present.

thanks,
Pádraig.