linux-kernel - Re: TTY: tty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 25 Mar 2012 17:14:37 +0200
From:	Richard Weinberger <richard@....at>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Al Viro <viro@...IV.linux.org.uk>, Jiri Slaby <jslaby@...e.cz>,
	linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
	Jiri Slaby <jirislaby@...il.com>
Subject: Re: TTY: tty_port questions

Am 25.03.2012 16:51, schrieb Alan Cox:
> On Sat, 24 Mar 2012 23:20:01 +0000
> Al Viro <viro@...IV.linux.org.uk> wrote:
> 
>> On Mon, Mar 12, 2012 at 11:48:32AM +0000, Alan Cox wrote:
>>
>>>>> It will be. In order to fix the tty locking mess we need to shove a lot
>>>>> of stuff whose lifetime is the lifetime of the physical port somewhere
>>>>> else - the tty_port is that structure.
>>>>>
>>>>
>>>> "It will be" in terms of "not now"? ;-)
>>>
>>> As in, it's the very next step on.
>>
>> FWIW, uml console in default config is basically "start xterm for each VC".
>> What do you suggest to do on vhangup() on one of those?
> 
> What posix says must happen. Which is that the running processes get a
> hangup. So a vhangup() would ensure there were no old apps on the UML
> guess talking to the xterm (eg stealing login credentials, or abusing
> TIOCSTI etc).

Looks like Debian's /bin/login is violating POSIX. AFACT it does not
call vhangup() at all.

> The fact it's an xterm isn't really relevant. That's just the physical
> interface and vhangup is about breaking the logical link. The xterm would
> continue, no reason for it to do otherwise I can see ?
> 

As I wrote in my very first mail, if I implement tty_operations->hangup()
a vhangup() closes the current TTY and the shiny new login shell dies because
read/write() returns EIO.

So, the question is whether tty_port is not suitable for consoles or my driver
(see first mail in thread) is broken.

Thanks,
//richard



Download attachment "signature.asc" of type "application/pgp-signature" (491 bytes)