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    SubjectRe: caps in elf headers: use the sticky bit!
    Hi David,

    On Fri, 16 Apr 1999, David Lang wrote:

    > On Thu, 15 Apr 1999, Theodore Y. Ts'o wrote:
    > >
    > > Date: Thu, 15 Apr 1999 16:07:35 -0700 (PDT)
    > > From: David Lang <>
    > >
    > > As for the NFS issue, there are situations where NFS can be used in a
    > > (at least semi)secure environment. If the NFS traffic is on a dedicated
    > > LAN (often done for performance anyway) then the only way that NFS can be
    > > a problem is if one of your machines in hacked into anyway. The ability to
    > > use capabilities on NFS mounted files would significantly help in server
    > > farm situations.
    > >
    > > So if I can manage to hack into one of your machines, (say, the one
    > > which is running the sendmail that didn't get updated to fix the
    > > sendmail security bug of the week) I get to break into all of the
    > > rest?!?
    > >
    > > This is real security? I think not.
    > But if we are using capabilities on all the machines, hacking into
    > sendmail won't give you this sort of access (or am I misunderstanding what
    > we are after here?)

    Well, I certainly am not in favor of trying to hack capabilities to work
    in a heterogenous environment. I see no reason why nfs can't be hacked so
    that two Linux machines can use capabilities over nfs. As far as IRIX,
    Linux 2.0 nfs servers, ... I just don't see this as an absolute necessity,
    especially when it adds what I consider unneeded bloat and complexity to
    our implementation.

    Of course, at least one gentleman from SGI has been very helpful in this
    thread; perhaps IRIX will get patched for this. ;-)

    > > A real world example. you setup a web server farm with the common
    > > files/binarys NFS mounted.
    > >
    > > Disk space is cheap these days. $300 USD will buy you 20 gigabytes of
    > > space; a complete Linux system worth of binaries is maybe 1, 2 gigs tops
    > > for a fully loaded system. If you're not willing to pay $15-30 extra
    > > per server so that each system can have its own copy of its system
    > > software, you're not serious about your system security.
    > >
    > > Besides, running your server farm with standalone disk increases your
    > > performance and your robustness, since you remove a single point of
    > > failure. (If your NFS server crashs, your entire server farm goes out.)
    > >
    > The reason to use the NFS server is not cost (A good, redundant NFS server
    > can be very expensive) the reason is ease of management, if you only have
    > one copy of the data the possibility that different servers have different
    > info just isn't there.

    For binaries, hack rdist; for _data_, just use nfs as is w/o caps.


    - --
    David L. Parsley
    Network Specialist
    City of Salem Schools

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