From: Arnd Bergmann <arnd@arndb.de>
To: Kees Cook <keescook@chromium.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Eric Biggers <ebiggers@google.com>,
Alasdair Kergon <agk@redhat.com>,
Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
Lars Persson <larper@axis.com>, Mike Snitzer <snitzer@redhat.com>,
Rabin Vincent <rabinv@axis.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
qat-linux@intel.com, dm-devel@redhat.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK
Date: Mon, 16 Jul 2018 09:24:06 +0200 [thread overview]
Message-ID: <CAK8P3a0Y82-zxiC4L1v3B20fTgP=AwfFT7sogZZBH5+v0uToHw@mail.gmail.com> (raw)
In-Reply-To: <CAGXu5jKQV+qiLjbDoS=8QYfG_hdiYeRqeDdov_of5wn5Sek0KA@mail.gmail.com>
On Mon, Jul 16, 2018 at 5:39 AM, Kees Cook <keescook@chromium.org> wrote:
> On Sun, Jul 15, 2018 at 5:01 PM, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>> On Sat, Jul 14, 2018 at 07:59:09PM -0700, Kees Cook wrote:
>>> On Sat, Jul 14, 2018 at 7:44 PM, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>>> > On Fri, Jul 13, 2018 at 08:07:10PM -0700, Kees Cook wrote:
>>> >>
>>> >> On a plane today I started converting all these to shash. IIUC, it
>>> >> just looks like this (apologies for whitespace damage):
>>> >
>>> > Yes if it doesn't actually make use of SGs then shash would be
>>> > the way to go. However, for SG users ahash is the best interface.
>>>
>>> Nearly all of them artificially build an sg explicitly to use the
>>> ahash interface. :P
>>>
>>> So, I'll take that as a "yes, do these conversions." :) Thanks!
>>
>> Yeah anything that's doing a single-element SG list should just
>> be converted.
>
> There are a few that are multiple element SG list, but it's a locally
> allocated array of SGs, and filled with data. All easily replaced with
> just calls to ..._update() instead of sg helpers. For example
> net/wireless/lib80211_crypt_tkip.c:
>
> - sg_init_table(sg, 2);
> - sg_set_buf(&sg[0], hdr, 16);
> - sg_set_buf(&sg[1], data, data_len);
> ...
> - ahash_request_set_tfm(req, tfm_michael);
> - ahash_request_set_callback(req, 0, NULL, NULL);
> - ahash_request_set_crypt(req, sg, mic, data_len + 16);
> - err = crypto_ahash_digest(req);
> - ahash_request_zero(req);
> + err = crypto_shash_init(desc);
> + if (err)
> + goto out;
> + err = crypto_shash_update(desc, hdr, 16);
> + if (err)
> + goto out;
> + err = crypto_shash_update(desc, data, data_len);
> + if (err)
> + goto out;
> + err = crypto_shash_final(desc, mic);
> +
> +out:
> + shash_desc_zero(desc);
> return err;
There may be a little overhead in calling crypto_shash_update()/
crypto_shash_final() repeatedly compared to calling
crypto_ahash_digest() once. It's probably no worse (or maybe
better) in this case, since we call only three times and there
is less indirection, but if there are any cases with a long sglist,
it would be good to measure the performance difference.
Arnd
next prev parent reply other threads:[~2018-07-16 7:52 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 20:36 [PATCH v4 00/14] crypto: Remove VLA usage Kees Cook
2018-07-11 20:36 ` [PATCH v4 01/14] crypto: xcbc: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 02/14] crypto: cbc: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 03/14] crypto: shash: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 04/14] dm integrity: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 05/14] crypto: ahash: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 06/14] dm verity fec: " Kees Cook
2018-07-11 20:36 ` [PATCH v4 07/14] crypto alg: Introduce generic max blocksize and alignmask Kees Cook
2018-07-11 20:36 ` [PATCH v4 08/14] crypto: qat: Remove VLA usage Kees Cook
2018-07-11 20:36 ` [PATCH v4 09/14] crypto: shash: Remove VLA usage in unaligned hashing Kees Cook
2018-07-11 20:36 ` [PATCH v4 10/14] kbuild: Introduce FRAME_WARN_BUMP_FLAG Kees Cook
2018-07-11 20:36 ` [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK Kees Cook
2018-07-12 16:02 ` Arnd Bergmann
2018-07-12 20:17 ` Kees Cook
2018-07-12 21:38 ` Arnd Bergmann
2018-07-13 0:40 ` Herbert Xu
2018-07-13 3:33 ` Kees Cook
2018-07-13 3:44 ` Herbert Xu
2018-07-13 5:17 ` Kees Cook
2018-07-13 5:20 ` Herbert Xu
2018-07-13 6:00 ` Kees Cook
2018-07-13 10:14 ` Arnd Bergmann
2018-07-15 4:28 ` Kees Cook
2018-07-17 20:59 ` Arnd Bergmann
2018-07-18 14:50 ` Ard Biesheuvel
2018-07-18 15:19 ` Ard Biesheuvel
2018-07-18 15:33 ` Arnd Bergmann
2018-07-18 15:33 ` Ard Biesheuvel
2018-07-19 2:51 ` Kees Cook
2018-07-19 2:55 ` Ard Biesheuvel
2018-07-19 3:09 ` Kees Cook
2018-07-19 3:13 ` Ard Biesheuvel
2018-07-19 14:54 ` Ard Biesheuvel
2018-07-19 18:44 ` Kees Cook
2018-07-13 6:16 ` Kees Cook
2018-07-13 6:22 ` Herbert Xu
2018-07-14 3:07 ` Kees Cook
2018-07-15 2:44 ` Herbert Xu
2018-07-15 2:59 ` Kees Cook
2018-07-16 0:01 ` Herbert Xu
2018-07-16 3:39 ` Kees Cook
2018-07-16 7:24 ` Arnd Bergmann [this message]
2018-07-11 20:36 ` [PATCH v4 12/14] crypto: ahash: Remove " Kees Cook
2018-07-11 20:36 ` [PATCH v4 13/14] rxrpc: Prepare to remove VLA usage for SKCIPHER_REQUEST_ON_STACK Kees Cook
2018-07-12 15:11 ` Arnd Bergmann
2018-07-12 20:23 ` Kees Cook
2018-07-12 20:30 ` Kees Cook
2018-07-12 21:15 ` Arnd Bergmann
2018-07-12 21:38 ` Kees Cook
2018-07-12 21:28 ` David Howells
2018-07-12 21:34 ` Kees Cook
2018-07-12 22:05 ` David Howells
2018-07-11 20:36 ` [PATCH v4 14/14] crypto: skcipher: Remove " Kees Cook
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