Date: Thu, 26 May 2011 11:34:16 -0700 (PDT)
From: david@lang.hm
To: Linus Torvalds <torvalds@linux-foundation.org>
cc: Will Drewry <wad@chromium.org>, Colin Walters <walters@verbum.org>,
        Kees Cook <kees.cook@canonical.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>, linux-kernel@vger.kernel.org,
        James Morris <jmorris@namei.org>
Subject: Re: [PATCH 3/5] v2 seccomp_filters: Enable ftrace-based system call
 filtering
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On Thu, 26 May 2011, Linus Torvalds wrote:
> 
> On Thu, May 26, 2011 at 9:33 AM, Will Drewry <wad@chromium.org> wrote:
>>
>> FWIW, none of the patches deal with privilege escalation via setuid
>> files or file capabilities.
>
> That is NOT AT ALL what I'm talking about.
>
> I'm talking about the "setuid()" system call (and all its cousins:
> setgit/setreuid etc). And the whole thread has been about filtering
> system calls, no?
>
> Do a google code search for setuid.
>
> In good code, it will look something like
>
>  uid = getuid();
>
>  if (setuid(uid)) {
>    fprintf(stderr, "Unable to drop provileges\n");
>    exit(1);
>  }
>
> but I guarantee you that there are cases where people just blindly
> drop privileges. google code search found me at least the "heirloom"
> source code doing exactly that.

I believe that sendmail had this exact vunerability when capibilities were 
used to control setuid a couple of years ago.

David Lang
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