From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [PATCH 13/15] SUNRPC: RPC buffer size estimates are too large Date: Wed, 24 Jan 2007 15:51:34 -0500 Message-ID: <20070124205134.GC6587@fieldses.org> References: <20070124191704.31133.12713.stgit@localhost.localdomain> <20070124192020.31133.78494.stgit@localhost.localdomain> <20070124203739.GA6587@fieldses.org> <45B7C482.9090807@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: nfs@lists.sourceforge.net, trond.myklebust@fys.uio.no To: Chuck Lever Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list2-new.sourceforge.net with esmtp (Exim 4.43) id 1H9p5k-00027F-1A for nfs@lists.sourceforge.net; Wed, 24 Jan 2007 12:51:36 -0800 Received: from mail.fieldses.org ([66.93.2.214] helo=fieldses.org) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1H9p5k-0002Ir-LI for nfs@lists.sourceforge.net; Wed, 24 Jan 2007 12:51:38 -0800 In-Reply-To: <45B7C482.9090807@oracle.com> List-Id: "Discussion of NFS under Linux development, interoperability, and testing." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfs-bounces@lists.sourceforge.net Errors-To: nfs-bounces@lists.sourceforge.net On Wed, Jan 24, 2007 at 03:41:38PM -0500, Chuck Lever wrote: > J. Bruce Fields wrote: > >On Wed, Jan 24, 2007 at 02:20:20PM -0500, Chuck Lever wrote: > >>+ req->rq_callsize = RPC_CALLHDRSIZE + (slack << 1) + proc->p_arglen; > >>+ req->rq_callsize <<= 2; > >>+ req->rq_rcvsize = RPC_REPHDRSIZE + slack + proc->p_replen; > >>+ req->rq_rcvsize <<= 2; > > > >What happened to rslack? The callsize calculation should be using > >cslack and the rcvsize calculation rslack, I think, right? > > As far as I understood it, cslack is the size of the authentication > verifier for that flavor. Shouldn't that be the same for calls and replies? No--it can even vary from one call or reply to the next, and we can't necessarily exactly predict the size of the reply verifier (though we should be able to give a fairly tight upper bound). Also the call has a credential in addition to the verifier, and the credential size also depends on the security flavor. > >In the krb5p case there's an extra annoyance: rslack is used to decide > >where to expect page data to start, so it can only take into account > >extra space needed at the beginning. But krb5p has to add padding, for > >example, to the end of each request. > > That padding has to follow XDR rules, though, correct? This is padding at a different level--the plaintext usually has to be padded to the nearest block size (at least 8 bytes) before encryption. --b. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs