On Oct 14 20:23, Corinna Vinschen wrote: > On Oct 14 11:18, Andrew Schulman wrote: > > So the difference AFAICT is the membership in the Administrators group. > > Notice also in the two listings below, that by password authentication, > > backup gets > > > > Mandatory Label\High Mandatory Level > > > > while by pubkey, he gets > > > > Mandatory Label\Medium Mandatory Level > > > > whatever those are. > > That's an UAC thingy. Keep in mind that Cygwin has to create the user > token from scratch here, given that you are using passwored-less setuid > method 1 > (per http://cygwin.com/cygwin-ug-net/ntsec.html#ntsec-setuid-overview). > I'm not aware of a method to fetch the mandatory level SID a user is > supposed to get, so what Cygwin does is simply to base the mandatory > level SID on the membership in the admins group. > > As for the missing privileges, they are not missing in the user token, > they are just disabled: > [...] > But even then, if the backup/restore privileges are disabled, it shouldn't > matter in Cygwin. Cygwin enables both privileges right at process startup. > > Having said that, I have no idea why the privileges are disabled in your > token. The good news is that I can reproduce the behaviour on a Windows > 2008 R2 box with a normal domain user account, which got explicit backup > and restore rights. > > I don't know why this occurs when using password-less setui method 1, > this is something which I have to debug yet.
I just debugged this and now I know why this happens. The problem is the aforementioned Mandatory Label. A user token which has medium mandatory level can not enable these privileges, even if they are in the user token. If I create the token with high mandatory level, it's no problem to enable the backup/restore permissions at process startup. However, I don't think it's a good idea to set the high mandatory level on a token unconditionally. This should only be done if the token contains certain privileges. The problem now is to find out which permissions are affected by this. I don't see any list of privileges on MSDN in terms of UAC restriction. Oh well, no pain, no gain. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
