Date: Thu, 19 Jan 2023 21:38:49 +0100
To: cygwin@cygwin.com
Subject: Re: Feature request: sudo
Message-ID: <Y8mqWfPrLYwA+MZi@calimero.vinschen.de>
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From: Corinna Vinschen via Cygwin <cygwin@cygwin.com>
Reply-To: cygwin@cygwin.com
Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>
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On Jan 19 20:17, Jochen Wiedmann via Cygwin wrote:
> Hi,
> 
> as someone who is quite used to typing
> 
>   sudo do something
> 
> I would really like to do the same in my CygWin bash.In my opinion,
> this could be implemented
> relatively simply, and straightforward as follows:
> 
>   - Accept an array of strings with the command, that is being
> executed with administrator
>     privileges.
>   - Use the standard Windows API to execute some functionality with
> admin privileges.
>     In the current case, that functionality would be a simple exec
> with the above command line.

Assuming you already are running an administrative account and you just
want to elevate a process, rather than actually switching the user
context to, say, "Administrator".

- The underlying Win32 system calls implementing fork/execve, i.e.
  CreateProcess and CreateProcessAsUser, don't allow to start an
  elevated process from a non-elevated process, unless you already have
  access to your elevated token.  While you can actually access that
  token, this token is not suitable for CreateProcessAsUser, unless you
  access it with TCB privileges... which only an already elevated
  process has.
  
- Windows doesn't provide SUID/SGID bits.  They are just faked in Cygwin
  using some bits in a NULL SID.  Thus, a sudo tool with SUID bit set is
  not workable on Windows, unless you control running an executable from
  an already privileged process which creates the user token.  This
  could be done by cygserver, but nobody implemented that yet.
  https://cygwin.com/acronyms/#SHTDI

Having said that, you can kind of do it yourself:

- Install and run Cygwin's sshd as a service.
- Create a public key pair.
- alias sudo='ssh localhost'


Corinna

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