lkml.org 
[lkml]   [2011]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 3/5] v2 seccomp_filters: Enable ftrace-based system call filtering
On Thu, May 26, 2011 at 10:02 AM, Will Drewry <wad@chromium.org> wrote:
>
> Absolutely - that was what I meant :/  The patches do not currently
> check creds at creation or again at use, which would lead to
> unprivileged filters being used in a privileged context.  Right now,
> though, if setuid() is not allowed by the seccomp-filter, the process
> will be immediately killed with do_exit(SIGKILL) on call -- thus
> avoiding a silent failure.

Umm.

You do realize that there is a reason we don't allow random kill()
system calls to succeed without privileges either?

So no, "we kill it with sigkill" is not safe *either*. It now is
potentially a way to kill privileged processes that you didn't have
permission to kill.

My point is that it all sounds designed for well-behaved processes.
"kill it if it does something bad" sounds like a *wonderful* idea if
you're doing a sandbox.

But it is suddenly potentially deadly if that capability is used by a
malicious user for a process that isn't ready for it.

One option is to just not ever allow execve() from inside a restricted
environment.

Linus
--
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: 2011-05-26 19:21    [W:0.142 / U:0.524 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site