Hi Andi,
On Wed, Jun 23, 2010 at 01:43:41PM +0200, Andi Kleen wrote:
> Kees Cook <kees.cook@xxxxxxxxxxxxx> writes:
> > +
> > +config SECURITY_YAMA_SYMLINKS
> > + bool "Yama: protect symlink following in sticky world-writable
> > dirs"
>
> IMHO it's bad style to have CONFIGs that just set defaults,
> if that can be done at runtime too. Especially as in your case if it's
> a lot of settings. Is it that bad to have a init script and drop these
> CONFIGs?
Oh, er, I actually added these configs because Eric Paris recommended them
as handy for distributions. I'm fine with dropping them, but will I be
asked to add them back later? And what about the case of CONFIG_SYSCTL
being unset?
> However the help texts are useful, these should be in the sysctl
> documentatin in Documentation instead.
I documented the sysctls in Documentation/Yama.txt (where SELinux.txt and
Smack.txt live) should I create an additional file in Documentation/sysctl/
with that information (moved from Yama.txt) or move Yama.txt there?
> > + if (rc) {
> > + printk_ratelimited(KERN_INFO "ptrace of non-child"
> > + " pid %d was attempted by: %s (pid %d)\n",
> > + child->pid, get_task_comm(name, current),
> > + current->pid);
>
> It's probably obscure and other kernel code has this too, but at some point
> there were attacks to use terminal ESC sequences to attack root's
> terminal when they dmesg. Couldn't that be done through "comm" here?
I actually think this is a flaw in get_task_comm. (Though actually it's
the fault of terminals if they process dangerous escape sequences. Worst
case tends to just be confusing output, but that's not important --
nothing should spew non-printables regardless.) Would a patch to
get_task_comm be accepted to replace non-printables with "?" or something
when filling the buffer?
Thanks,
-Kees
--
Kees Cook
Ubuntu Security Team
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