Re: [v9.2] Add GUC sepgsql.client_label

2012/3/12 Robert Haas <robertmhaas@gmail.com>:
> On Mon, Mar 12, 2012 at 10:58 AM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
>> It is a practical reason. In case when httpd open the connection to PG and
>> set a suitable security label according to the given credential prior to launch
>> of user application, then keep this connection for upcoming request, it is
>> worthwhile to reset security label of the client.
>
> But wait a minute - how is that any good?  That allows the client to
> pretty trivially circumvent the security restriction that we were
> trying to impose by doing sepgsql_setcon() in the first place.  It
> doesn't matter how convenient it is if it's flagrantly insecure.
>
> Am I missing something here?
>
It is a practical reason. If we would not support the reset feature,
the application has to know the security label of itself, as a target
label to be reverted. However, I'm not certain the status of script-
language binding of libselinux feature to obtain the self label,
although it is supported on Perl, Ruby and PHP (with extension
by myself) at least.

It seems to me a reasonable cost to track the original label to
eliminate a restriction of application side that tries to revert
the security label once switched.

Thanks,
--
KaiGai Kohei <kaigai@kaigai.gr.jp>