Messages in this thread | | | Date | Thu, 7 Apr 2005 16:50:32 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: Linux-2.6.11 can't disable CAD |
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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/
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