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    From
    SubjectRe: boot parameters, init= and security issues
    Date
    In article <m2afyk3ic3.fsf@cortex.corpus.uni-muenster.de>,
    Markus Gutschke <gutschk@uni-muenster.de> wrote:
    >miquels@cistron.nl (Miquel van Smoorenburg) writes:
    >> Alas, Linus rejected it. This normally means he thinks it
    >> was not a good idea. Hence the request for comment here.
    >> Would something like this be useful? Or isn't it because there
    >> are other boot options that can be abused to achieve the
    >> same effect (and turning them all off would be unacceptable) ?
    >
    >Off-hand the possibility of using a different root filesystem on a
    >removeable medium (floppy disk) springs to mind as yet another obvious
    >security threat, but this can probably be avoided, by compiling the
    >floppy driver as a module and not allowing for NFS mounted root
    >filesystems. Most of the other boot time options probably result in
    >making the system rather unreliable and prone to crashes but I am not
    >aware of obvious exploits.
    >
    >Generally, though I am in favor of your proposal. Providing as many
    >boot-time security measures as possible sounds like a *very* good idea
    >--- but maybe I am just a little bit paranoid :-)

    I talked with Linus today about these patches, but he thinks the
    idea is broken; you should just put a password on the LILO
    configuration. I responded that most people do not do this, and
    I just wanted to make reasonably sure that a Linux box somewhere
    in a university cannot be broken into just by rebooting it (as
    long as the sysadm has set the boot sequence to C: A: and put a
    password on the BIOS). Most people don't know anything about
    LILO configuration.

    But well, the real problem still is the root= parameter. Put in
    an emergency floppy, boot from harddisk with on the command line
    "root=/dev/fd0" and you're in. You really don't want to
    disallow the "root=" parameter :)

    The only way around this is to disallow root= setting to a floppy
    disk when you've booted from harddisk, but as far as I can see
    there is no easy way to find out the bootdevice. Well you could
    find it out in linux/arch/i386/kernel/setup.c I think, but that'd
    only work for the PC architecture.

    I'm still thinking about this. But is sure isn't as easy as
    I though it would be.

    Mike.
    --
    + Miquel van Smoorenburg + Cistron Internet Services + Living is a |
    | miquels@cistron.nl (SP6) | Independent Dutch ISP | horizontal |
    + miquels@drinkel.ow.org + http://www.cistron.nl/ + fall +



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