push problem

Matt Mackall mpm at selenic.com
Mon Aug 8 17:43:35 CDT 2005


On Tue, Aug 09, 2005 at 12:02:57AM +0200, Vadim Lebedev wrote:
> >
> >Eh? You know you can be a member of multiple groups at a time. There's
> >a "default" group id and a bunch of supplementary ones.
> >
> Yes,
> but at the moment of the file access the kernel verifies the access only 
> for your effective group (and user) id...
> To change effective user id you have to use newgrp and sg  commands or 
> setgid syscall....
> Actually the kernel is completely unaware of the fact that you are a 
> member of multiple groups...
> only nwgrp or sg commands are accessing the /etc/group file to verify 
> that you can execute newgrp or sg commands with given argument .

I'm afraid you're mistaken.

You can in fact be a member of any number of groups, though older
systems have a limit of 32.

In Linux, see the call to in_group_p in generic_permission in
fs/namei.c to convince yourself.

-- 
Mathematics is the supreme nostalgia of our time.


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