On Wed, 2 Apr 2014, Linus Torvalds wrote:
> > Which doesn't really protect you from tasks that do open()/write()/close()
> > cycle for /dev/kmsg write every 2ms though.
>
> I don't think we should try to protect against wilful bad behavior
> unless that is shown to be necessary. Yeah, if it turns out that
> systemd really does that just to mess with us, we'd need to extend it,
> but in the absence of proof to the contrary, maybe this simple
> attached patch works?
>
> TOTALLY UNTESTED. But it really isn't complex.
[ ... snip ... [
@@ -483,6 +484,8 @@ static ssize_t devkmsg_read(struct file *file, char __user
*buf,
if (!user)
return -EBADF;
+ if (!___ratelimit(&user->rs, current->comm))
+ return 0;
I am admittedly rather new to this 'abuse the hell out of kernel
ringbuffer' thing, but shouldn't we better be limiting the
devkmsg_writev()?
--
Jiri Kosina
SUSE Labs
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