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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Richard Weinberger <richard@nod.at>
Cc: user-mode-linux-devel@lists.sourceforge.net,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	viro@zeniv.linux.org.uk, jslaby@suse.cz, alan@linux.intel.com
Subject: Re: [uml-devel] um: TTY fixes (?)
Date: Thu, 7 Jun 2012 11:52:27 +0100	[thread overview]
Message-ID: <20120607115227.6643d1ad@pyramind.ukuu.org.uk> (raw)
In-Reply-To: <4FD0802A.1020203@nod.at>

> > I really don't get it. You have not broken anything new. Only
> > not fixed all of the problems. Current code does not work for "non-tty0
> > terminals" as well right?
> 
> No, it works fine.

Not really. You happen to be lucky. Anyway with no tty port the UML code
will soon cease to function completely so a solution of some sort is
needed.
 
> > I don't see Alan's comment at all. This is not a regression it was always
> > like that. Ever since Fedora was working on UML, But these fixes are real
> > live regression crashes.
> > 
> > And I don't see the all "leaving other vendors systems insecure". It just
> > a freaking UML tty. You need to be root 5 times before you have access
> > to all these, and it's only the UML that's compromised not the "all system"
> > And surely the current plain tty0 crash is much less secure then this thing.
> 
> The "TTY problem" is not UML specific.

That one is. The console driver handles stuff its own way and
differently. It's eventually got to tackle the same problem.

I still think we ought to be able to solve it cleanly. It's a case of
getting the tests right so that we allow for the misbehaviour util-linux
does.

As of itself util-linux behaviour doesn't appear to be something we can't
permit as the 

	open
	vhangup

sequence means the file handle that is left from before the vhangup due
to util-linux misbehaving is a hung-up fd so cannot affect the tty.

UML is a good test case for fixing this properly because it's got almost
no users, and those it has are fairly technical 8)


Alan

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  parent reply	other threads:[~2012-06-07 10:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-04 20:27 um: TTY fixes (?) Richard Weinberger
2012-06-04 20:27 ` [uml-devel] [PATCH 1/6] TTY: um/line, add tty_port Richard Weinberger
2012-06-04 20:27 ` [uml-devel] [PATCH 2/6] TTY: um/line, use tty from tty_port Richard Weinberger
2012-06-04 20:27 ` [uml-devel] [PATCH 3/6] um: remove line_ioctl() Richard Weinberger
2012-06-04 20:27 ` [uml-devel] [PATCH 4/6] um: Remove dead code Richard Weinberger
2012-06-04 20:27 ` [uml-devel] [PATCH 5/6] um: fully use tty_port Richard Weinberger
2012-06-04 20:47   ` Jiri Slaby
2012-06-04 20:27 ` [uml-devel] [PATCH 6/6] um: remove count_lock Richard Weinberger
2012-06-04 21:17 ` [uml-devel] um: TTY fixes (?) Alan Cox
2012-06-04 23:14   ` Richard Weinberger
2012-06-05 10:41     ` Karel Zak
2012-06-05 11:15       ` [uml-devel] " Alan Cox
2012-06-05 12:20         ` Richard Weinberger
2012-06-05 15:17           ` [uml-devel] " Karel Zak
2012-07-12 14:49             ` Karel Zak
2012-07-12 15:01               ` Richard Weinberger
2012-06-06 23:17   ` Richard Weinberger
2012-06-07  9:19     ` Alan Cox
2012-06-07  9:06       ` Richard Weinberger
2012-06-06 14:20 ` [uml-devel] " Boaz Harrosh
2012-06-07  7:35   ` Boaz Harrosh
2012-06-07  7:43     ` Boaz Harrosh
2012-06-07  8:45     ` Richard Weinberger
2012-06-07  9:22       ` Alan Cox
2012-06-07 10:14       ` Boaz Harrosh
2012-06-07 10:19         ` Richard Weinberger
2012-06-07 10:35           ` Boaz Harrosh
2012-06-07 10:52           ` Alan Cox [this message]
2012-06-07 13:41             ` Boaz Harrosh
2012-06-07 15:18             ` Richard Weinberger
2012-06-07 16:37               ` Alan Cox
2012-06-07 16:32                 ` Richard Weinberger
2012-06-07 16:50                   ` Alan Cox
2012-06-07 16:41                     ` Richard Weinberger
2012-06-07 17:26                       ` Alan Cox

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