From: Andy Lutomirski Subject: Re: Doing crypto in small stack buffers (bluetooth vs vmalloc-stack crash, etc) Date: Wed, 22 Jun 2016 16:45:46 -0700 Message-ID: References: <20160622004214.GA27134@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Andy Lutomirski , linux-bluetooth@vger.kernel.org, Johan Hedberg , Gustavo Padovan , Marcel Holtmann , linux-crypto@vger.kernel.org, "David S. Miller" , "linux-kernel@vger.kernel.org" , Linus Torvalds To: Herbert Xu Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Wed, Jun 22, 2016 at 2:48 PM, Andy Lutomirski wrote: > On Tue, Jun 21, 2016 at 5:52 PM, Andy Lutomirski wrote: >> On Tue, Jun 21, 2016 at 5:42 PM, Herbert Xu wrote: >>> On Tue, Jun 21, 2016 at 10:43:40AM -0700, Andy Lutomirski wrote: >>>> >>>> Is there a straightforward way that bluetooth and, potentially, other >>>> drivers can just do synchronous crypto in a small buffer specified by >>>> its virtual address? The actual cryptography part of the crypto code >>>> already works this way, but I can't find an API for it. >>> >>> Yes, single block users should use crypto_cipher_encrypt_one, an >>> example would be drivers/md/dm-crypt.c. >>> >> >> Aha! I expected something like that to exist, but I couldn't find it. >> I'll change the two offenders I've found so far to use it. >> > > Before I do this, can you explain what the difference is between > crypto_cipher and crypto_skcipher? net/bluetooth/smp.c currently uses > crypto_alloc_skcipher, which you added in: > > commit 71af2f6bb22a4bf42663e10f1d8913d4967ed07f > Author: Herbert Xu > Date: Sun Jan 24 21:18:30 2016 +0800 > > Bluetooth: Use skcipher and hash > > Am I just supposed to replace "skcipher" with "cipher" everywhere? It looks like I'm supposed to that and to use "aes" instead of "ebc(aes)". *However*, the other offender I've found (net/rxrpc/rxkad.c) uses "pcbc(fcrypt)", which doesn't appear to be usable with this API. Is there no way to say "I want synchronous crypto on this VA range" using the skcipher API? --Andy -- Andy Lutomirski AMA Capital Management, LLC