Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!ukma!david From: david@ms.uky.edu (David Herron -- Resident E-mail Hack) Newsgroups: comp.unix.wizards Subject: Re: NFS and many thousands of user-id's Message-ID: <7623@e.ms.uky.edu> Date: Mon, 2-Nov-87 22:07:29 EST Article-I.D.: e.7623 Posted: Mon Nov 2 22:07:29 1987 Date-Received: Fri, 6-Nov-87 02:07:51 EST References: <7605@g.ms.uky.edu> Organization: U of Ky, Math. Sciences, Lexington KY Lines: 58 A lot of people have become confused over the following paragraph ... it's a shame too, 'cause it was simply a side comment and not the main point of the posting. In article <7605@g.ms.uky.edu>, I wrote: > (As does security problems like -- if you're root on one nfs machine > you can instantly become root on any other nfs machine -- professors > who're accustomed to students NOT being on these machines, so they > write their exams here ...) Many people have told me that root -> uid -2 across NFS. I already am very very familiar with this (thank you), and that is NOT what I had meant. Rather ... Consider the following situation. You're root on a machine that serves part of it's filesystem. You put a /bin/sh somewhere and make it setuid to root etc. Then you go over to another machine and execute that /bin/sh. Voila you're root over there. Here this can happen because one of our professors requires root access to his workstation and part of his workstations filesystem is globally mounted. Fortunately he's a good guy and recently became part of the support group so it doesn't matter. I've since read through the NFS Protocol Description which came along with our Mt Xinu manuals ... Everybody please read section 2.2.2. where it talks about what I said in the previous paragraph. But within the time frame of our brainstorming session (2 years) we could easily have our instructional lab full of machines running something which'll be doing NFS. But we hadn't thought through the consequences of AT&T and Sun merging the many-varied threads of Unix into one. Part of this means a merging of NFS and RFS. (Will they meet halfway and call it PFS???) :-) Since RFS has some of the proper security features, and the NFS people know the problems already, then this will probably be fixed around SysVr10. The main thrust of my article had been to cause thought on what a large distributed system would mean. Right now our system is fairly limited. We've got 5 vaxen and a sun serving about 20 vax workstations and 5 sun workstations. But in a couple of years there could be many many departments owning systems capable of operating with NFS (PFS?). Especially with diskless workstations being so cheap nowadays ... they'd just have to find some machine to serve them disk blocks... The nearer to the client machines the better. Anyway, what would this system be like? A common file system serving large parts of this University? It's sort of mind boggling. I don't know if we'd do something so mundane as running out of user-id's. 64000 is a large number still. But there are somewhat more people than that on campus, and if we ever got to a situation where *everybody* had accounts ... and they all had to be in one filesystem and the filesystem were as it is now ... -- <---- David Herron, Local E-Mail Hack, david@ms.uky.edu, david@ms.uky.csnet <---- {rutgers,uunet,cbosgd}!ukma!david, david@UKMA.BITNET <---- "The market doesn't drop hundreds of points on a normal day..." -- <---- Fidelity Investments Corporation