[kernel-hardening] Re: [PATCH] kernel: escape non-ASCII and control characters in printk()

Vasiliy Kulikov
2011-06-22T19:07:39Z

Hi Alan,

On Wed, Jun 22, 2011 at 19:10 +0100, Alan Cox wrote:
> If that is set you shouldn't be filtering out unicode, just control codes.

OK.

> Minor other nit is that you might want to allow BEL through and you
> certainly want to allow tab through.

In what situation do you think BEL makes sense in kernel log? I cannot
image the situation. Alarms should use KERN_EMERG/KERN_ALERT log level.

> The core code should not be hardcoding policy assumptions about symbol
> sets and ASCII, for an awful lot of consoles today that assumption is
> just plain wrong, for others it makes sense

No problem, I don't insist.

> So with tty maintainer hat on - NAK to the current approach but a good
> idea to do it properly.

The final check should be:

if (iscntrl(c) && (c != '\n') && (c != '\t'))

Any comments against this variant?

Thanks,

--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments