Filtered tokens

[Patrick Julien]

On Tue, Apr 27, 2010 at 9:58 AM, Corinna Vinschen
<corinna-cygwin@cygwin.com> wrote:
> On Apr 27 09:33, Patrick Julien wrote:
>> On Tue, Apr 27, 2010 at 9:26 AM, Corinna Vinschen
>> <corinna-cygwin@cygwin.com> wrote:
>> > On Apr 27 08:39, Patrick Julien wrote:
>> >> OK, I understand why it's the privileged token but why is it still in session 0?
>> >
>> > Because it's started in session 0.  Creating our own session for each user
>> > could result in an enormous memory leak.
>>
>> That's how the regular logon does it, don't see why it has to leak.
>
> I meant in case of an error but, never mind.
>
> The basic problem is that Cygwin doesn't constitute a remote desktop
> logon server.  A session can only be created by a trusted logon process.
> There isn;'t a simple API to request a new session ID.  Additionally,
> on client machines RDP only allows one user RDP session.  If, say, an
> ssh login would request a session, the request would either be refused,
> or it would lock the console window.  Only on real RDP servers you can
> have multiple sessions.


I am going to research this a bit and see if anything can be done.
When UAC prompts the user, you have switched session so there has to
be a way to do it.

>
>> > That's because setup works that way.  If you want the ownership of the
>> > files being administrator, start setup as administrator.
>>
>> Gee thanks, yeah, I got that, I still think it's a security issue,
>> that is, a bug.  See the original post, any program can read/write to
>> any executable in cygwin without escalation because I'm the owner.
>
> No, it isn't.  If you're admin you have this right anyway and non-admin
> users still have restricted access to the files.  Just because UAC
> exists, it's not automatically a good concept.
>

I don't want to start debating the good or bad of UAC, but if setup
would just assign the owner to be 'system' instead of the admin user
who started setup, when I run a command line as that user, I wouldn't
have write access from inside cygwin.  I would need to start the
cygwin environment elevated to do that.

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