Re: 8250 serial console fixes -- issue

[Glen Turner <glen.turner@aarnet.edu.au>]

Russell King wrote:

> My point stands - if the user can provide an arbitary string to printk,
> they can fake any kernel message.  That in itself is a security bug.
> If there is an instance of that, then that's the real bug which would
> need fixing.
>
> Once those bugs have been fixed, your claimed bug is also magically
> fixed.

Hi Russell,

Thanks for the explanation of where the kernel should handle
covert channels.

How about the other bugs reported by people who have used
the Remote-Serial-Console-HOWTO:

  - writing any text to an idle (DCD not asserted) modem still
    causes incoming calls to be hung up on.  That's not good
    as sysadmins can't connect to systems with failing hardware.

    [Note that modems really need the 'r' option, so it's
     fine to continue to write with DCD unasserted without
     the 'r' option.]

  - the huge boot times with the 'r' option and an idle/
    unconnected modem/terminal server.  This is caused by
    the CTS timing out per character even when CTS is
    floating (CTS is not defined unless DSR is asserted).
    This basically makes the 'r' option impossible to
    use on production systems.  Not using the 'r' option
    with a terminal server brings other problems (notably
    character loss problems when people paste a large
    number of characters into the SSH session through
    the terminal server to the remote host).

  - writing LF CR rather than CR LF unfortunately causes
    issues with some terminals.

I'm really only the messenger here.  I've collected bug reports
from readers of the HOWTO and written a patch to address their
experiences.  I'm sure people with much more familiarity with
the kernel can do it better.

Thanks,
Glen

--
 Glen Turner         Tel: (08) 8303 3936 or +61 8 8303 3936
 Australia's Academic & Research Network  www.aarnet.edu.au
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