From owner-freebsd-current@FreeBSD.ORG Tue Sep 16 20:08:30 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 069E71065750; Tue, 16 Sep 2008 20:08:30 +0000 (UTC) (envelope-from ache@nagual.pp.ru) Received: from nagual.pp.ru (nagual.pp.ru [194.87.13.69]) by mx1.freebsd.org (Postfix) with ESMTP id 6CB8C8FC23; Tue, 16 Sep 2008 20:08:29 +0000 (UTC) (envelope-from ache@nagual.pp.ru) Received: from nagual.pp.ru (ache@localhost [127.0.0.1]) by nagual.pp.ru (8.14.3/8.14.3) with ESMTP id m8GK8RHA044659; Wed, 17 Sep 2008 00:08:27 +0400 (MSD) (envelope-from ache@nagual.pp.ru) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nagual.pp.ru; s=default; t=1221595707; bh=IDgAkqB8B86LmWh65eVIfioJSg9y/C/uETGrdgv DZow=; l=1267; h=Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=uXW4GwbG2cUPrjubpL+XIV1rZ 5X7zyLgj4FWELbNc6tdPHYrGIJYZHqN+6QntTqDSCFbSSgi13OIO/loHh0Q5SWRvoPo oudQaZJP7u3Upz41thtcdGZgc/YQYMiFmV3AODGvZrYX0JvLfm0meUsydnSiKm1+HI7 nLmwgqo95Mdc= Received: (from ache@localhost) by nagual.pp.ru (8.14.3/8.14.3/Submit) id m8GK8PK7044657; Wed, 17 Sep 2008 00:08:25 +0400 (MSD) (envelope-from ache) Date: Wed, 17 Sep 2008 00:08:23 +0400 From: Andrey Chernov To: Max Laier Message-ID: <20080916200822.GA44273@nagual.pp.ru> Mail-Followup-To: Andrey Chernov , Max Laier , freebsd-current@freebsd.org, Daniel Eischen References: <20080916140319.GA34447@nagual.pp.ru> <200809161827.07627.max@love2party.net> <20080916164558.GA41258@nagual.pp.ru> <200809162148.24090.max@love2party.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200809162148.24090.max@love2party.net> User-Agent: Mutt/1.5.18 (2008-05-17) Cc: Daniel Eischen , freebsd-current@freebsd.org Subject: Re: Is fork() hook ever possible? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Sep 2008 20:08:30 -0000 On Tue, Sep 16, 2008 at 09:48:23PM +0200, Max Laier wrote: > Slow down here. You haven't answered my question. What exactly is the issue > this is supposed to fix? Do we want to prevent a child from knowing what the > next few arc4random outputs of its parent will be? Or are we only concerned > that the next few arc4random of the parent and child should not be the same? The child and the parent should have different arc4random() states to produce different returns, say, for mktemp() they both called after fork() (or for any other function inside libs which use arc4random()). To achieve that it is enough to re-stir in the child only. > > Could you add a new interface, arc4random_setstir() or something, > > to set a flag that indicates a stir should be done at the next > > opportunity? > > ... this certainly is the right solution. arc4random() should not care about > pids and such - IMHO, of course. Perhaps clearing rs_stired flag just for arc4random() instead of general getpid() speedup will be the right solution, because we have an edge case: vfork() for which there is no sense to re-stir at all because both the parent and the child will be re-stired at the same time in any case. -- http://ache.pp.ru/