From: Herbert Xu Subject: Re: crypto: zeroization of sensitive data in af_alg Date: Tue, 11 Nov 2014 10:53:14 +0800 Message-ID: <20141111025314.GA14173@gondor.apana.org.au> References: <1979092.odOtqL46qU@tachyon.chronox.de> <20141110140518.GD8578@gondor.apana.org.au> <1533864.71MuF2upah@tachyon.chronox.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org To: Stephan Mueller Return-path: Content-Disposition: inline In-Reply-To: <1533864.71MuF2upah@tachyon.chronox.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Tue, Nov 11, 2014 at 03:06:32AM +0100, Stephan Mueller wrote: > Am Montag, 10. November 2014, 22:05:18 schrieb Herbert Xu: > > Hi Herbert, > > > On Sun, Nov 09, 2014 at 11:33:52PM +0100, Stephan Mueller wrote: > > > while working on the AF_ALG interface, I saw no active zeroizations of > > > memory that may hold sensitive data that is maintained outside the kernel > > > crypto API cipher handles. I think the following memory segments fall > > > under that > > > category: > > Are you talking about temporary data that we generate as part of > > the processing? If so they should be zeroed by the entity that > > generates them. > > I currently see that the IV buffer (owned by skcipher) and the message digest > buffer (owned by hash) are not memset(0) before freeing them. I agree that > both are not really sensitive data. But wouldn't it be prudent to memset(0) > them nonetheless in the skcipher_sock_destruct and hash_sock_destruct > functions, respectively? Yes please submit your patches. > Apologies, my bad as I did not check get_user_pages_fast well enough. I see > now that we operate on the pages in user space directly without copy_from_user > that would imply a kernel-internal copy. Please disregard my comment. OK. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt