Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965082AbVI0VRc (ORCPT ); Tue, 27 Sep 2005 17:17:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965148AbVI0VRc (ORCPT ); Tue, 27 Sep 2005 17:17:32 -0400 Received: from mother.openwall.net ([195.42.179.200]:39642 "HELO mother.openwall.net") by vger.kernel.org with SMTP id S965082AbVI0VRc (ORCPT ); Tue, 27 Sep 2005 17:17:32 -0400 Date: Wed, 28 Sep 2005 01:16:24 +0400 From: Solar Designer To: Linus Torvalds Cc: Alan Cox , Sergey Vlasov , vendor-sec@lst.de, linux-kernel@vger.kernel.org, security@linux.kernel.org Subject: Re: PID reuse safety for userspace apps (Re: [linux-usb-devel] Re: [Security] [vendor-sec] [BUG/PATCH/RFC] Oops while completing async USB via usbdevio) Message-ID: <20050927211624.GA4947@openwall.com> References: <20050925151330.GL731@sunbeam.de.gnumonks.org> <20050927160029.GA20466@master.mivlgu.local> <20050927165206.GB20466@master.mivlgu.local> <20050927172048.GA3423@openwall.com> <1127853252.10674.9.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 926 Lines: 22 On Tue, Sep 27, 2005 at 01:42:44PM -0700, Linus Torvalds wrote: > Note that for at least signal sending, the security aspect is _not_ about > whether the pid has been re-used, but about whether the _user_ matches. That's true. And, changing topic to userspace apps, killall(1) currently has no race-free way to check whether the user still matches. There's also the reliability aspect: killing one's own process, but other than the intended one, is a reliability issue. What I have proposed is a way to deal with both of these. killall is just an example. A GUI point-and-click task manager would have the same problem and the same solution would work for it. -- Alexander - 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/