Date: Thu, 4 Jun 1998 23:01:22 -0700 (PDT) From: Doug White <dwhite@gdi.uoregon.edu> To: "Brian O'Connor" <boc@ironbark.bendigo.latrobe.edu.au> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: what happens to daemon processes when password file is zeroed Message-ID: <Pine.BSF.3.96.980604230006.26356I-100000@gdi.uoregon.edu> In-Reply-To: <199806050427.OAA05884@ironbark.bendigo.latrobe.edu.au>
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On Fri, 5 Jun 1998, Brian O'Connor wrote:
> Hello,
> I have an aversion to NIS, and am trying to roll my own with
> ssh and other such tools. I have already had the delightfull experience of
> deleting the password file(I got my + < and > the wrong way around in perl).
> It occured to me that if the password file was deleted, or of zero length
> how do running daemons handle permissions? ie, processes seemed to continue
> to run, I just couldn't log in.
They compare uid's. The system stores user and group perms by ID, not by
name. Even though the name->number mapping is gone the numbers are still
around.
> What I want to try is to write a daemon that checks to see if the passwd
> file exists, and is of non zero size(i could put other tests here, but this
> will do for a start). If this test fails, it copies a fail safe copy over
> and then reports the error, of course this will fail if the daemon does
> not have permission to write to /etc (since there is no user root)
Yeah there is, UID 0 still exists. Don't try to setuid("root"), but you
can do setuid(0).
Doug White | University of Oregon
Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant
http://gladstone.uoregon.edu/~dwhite | Computer Science Major
NOTICE: gdi.uoregon.edu is going down, please use dwhite@resnet!
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