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Re: setup-x86_64: postinstall errors: Package bash 1, Package a2ps 2 and xinit 134


On Jul 23 15:08, Charles Wilson wrote:
> On 7/23/2013 2:46 PM, Corinna Vinschen wrote:
> >On Jul 23 14:14, Charles Wilson wrote:
> >>>I believe your report has to do with error handling when attempting
> >>>to modify the All User's Desktop, when you don't actually retain the
> >>>elevated permissions necessary to do so.
> 
> >>Is there are way for setup.exe to
> >>delegate its elevated credentials down to /bin/bash, and thence to
> >>mkshortcut.exe? Otherwise, even the *fix* for this bug will just
> >>make it not hang or crash; it will still fail to modify the
> >>all-users start menu/desktop.
> >
> >Setup does not give up any of it's permissions when starting the
> >postinstall scripts via CreateProcess.  The scripts have the same
> >permissions as setup itself, which makes a lot of sense if you think
> >about it.  Missing permissions to change system dirs should only occur
> >if setup has been started as non-admin, or if the UAC installer
> >recognition has been switched off (affects only the 32 bit version).
> 
> But even if /bin/bash is elevated, it doesn't follow that any of the
> tools launched within a script -- via cygwin's fork/exec method --
> ALSO retain that elevation.
> 
> Does it?

Yes, it does.  CreateProcess propagates its own user token untouched.

Weird question.  Did you ever start an elevated shell and lost your
admin permissions in a child process?  If that would occur, nothing
would work right in an admin shell.  Even the `id' call would not show
the admins group in your supplementary group list.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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