On Mon, 4 Feb 2002, Chris Wright wrote:
> Extended attribute support was merged in 2.5.3. Extended attributes
> come in name:value pairs. The name is a character string representing
> the namespace for the extended attributes. The value is free form, and
> is of questionable use to the module (however is included in the patches
> below).
The value (when provided as an input parameter to the call, e.g. setxattr)
will be important to some security modules. For example, if the security
module is using extended attributes to store its own security data, then
it will likely perform a permission check based on the new value when the
name corresponds to its own attribute space. Additionally, if certain
('name', 'value') pairs are well-defined and are critical to system
security, then some security modules may choose to make use of the value
in those cases.
However, I would suggest that you only pass arguments with input data;
passing kernel buffers reserved for output data doesn't seem useful,
especially since they haven't been filled yet. This means that you would
drop the 'kvalue' and 'size' from the getxattr hook and the 'klist' and
'size' from the listxattr hook.
--
Stephen D. Smalley, NAI Labs
ssmalleyat_private
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