lkml.org 
[lkml]   [2005]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Linux-2.6.11 can't disable CAD
On Thu, 7 Apr 2005, Jan Harkes wrote:

> On Thu, Apr 07, 2005 at 11:16:14AM -0400, Richard B. Johnson wrote:
>> In the not-too distant past, one could disable Ctl-Alt-DEL.
>> Can't do it anymore.
> ...
>> Observe that reboot() returns 0 and `strace` understands what
>> parameters were passed. The result is that, if I hit Ctl-Alt-Del,
>> `init` will still execute the shutdown-order (INIT 0).
>
> Actually, if CAD is enabled in the kernel, it will just reboot.
> If CAD is disabled in the kernel a SIGINT is sent to pid 1 (/sbin/init).
>

No, that's not how it ever worked. There are parameters that are
available in the reboot-system call that define the operation that
will occur when the 3-finger salute occurs.

Execute man 2 reboot.

> So what you probably had in the not-too-distant past was a disabled CAD
> in the kernel _and_ you had modified the following line in /etc/inittab,
>

The systems to which I refer do not, and never even had a file-system,
much-less any inittab. That's SYS-V init stuff for interactive access.

> # What to do when CTRL-ALT-DEL is pressed.
> ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
>
> AFAIK this hasn't ever really changed.
>
> Jan
>

The kernel's response (or the 'C' runtime-library interface) has
changed so that it is now possible for somebody at the keyboard
of a machine to destroy the machine's operation by executing
Ctl-Alt-Del. I don't know how long this potential catastrophe
has existed, but when the machine(s) were initially certified
there was no possible way for a user to kill the machine from
the keyboard.

It is possible that a 'C' runtime library was changed in the
tarket so it's not a kernel problem. I'm checking it out now.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
Notice : All mail here is now cached for review by Dictator Bush.
98.36% of all statistics are fiction.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-04-07 22:55    [W:0.052 / U:8.784 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site