linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Eric Biggers <ebiggers@kernel.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
	<linux-crypto@vger.kernel.org>,
	"Jason A . Donenfeld" <Jason@zx2c4.com>,
	Greg Kaiser <gkaiser@google.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Samuel Neves <samuel.c.p.neves@gmail.com>,
	Michael Halcrow <mhalcrow@google.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fscrypt@vger.kernel.org,
	Tomer Ashur <tomer.ashur@esat.kuleuven.be>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Paul Crowley <paulcrowley@google.com>
Subject: Re: [RFC PATCH v2 04/12] crypto: chacha - add XChaCha12 support
Date: Fri, 19 Oct 2018 11:28:05 -0700	[thread overview]
Message-ID: <20181019182804.GA246441@gmail.com> (raw)
In-Reply-To: <CAKv+Gu_wVmnEND3MGTG7bqqynbBqyzmE_gTmqZfrT551_n9Hmw@mail.gmail.com>

Hi Ard,

On Fri, Oct 19, 2018 at 10:34:41PM +0800, Ard Biesheuvel wrote:
> > diff --git a/include/crypto/chacha.h b/include/crypto/chacha.h
> > index ae79e9983c72f..3d261f5cd156d 100644
> > --- a/include/crypto/chacha.h
> > +++ b/include/crypto/chacha.h
> > @@ -5,6 +5,11 @@
> >   * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's
> >   * security.  Here they share the same key size, tfm context, and setkey
> >   * function; only their IV size and encrypt/decrypt function differ.
> > + *
> > + * The ChaCha paper specifies 20, 12, and 8-round variants.  In general, it is
> > + * recommended to use the 20-round variant ChaCha20.  However, the other
> > + * variants can be needed in some performance-sensitive scenarios.  The generic
> > + * ChaCha code currently allows only the 20 and 12-round variants.
> >   */
> >
> >  #ifndef _CRYPTO_CHACHA_H
> > @@ -39,6 +44,8 @@ void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, u8 *iv);
> >
> >  int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
> >                            unsigned int keysize);
> > +int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
> > +                          unsigned int keysize);
> >
> >  int crypto_chacha_crypt(struct skcipher_request *req);
> >  int crypto_xchacha_crypt(struct skcipher_request *req);
> > diff --git a/lib/chacha.c b/lib/chacha.c
> > index 0a2c2e5b7b84d..c4d69a83fcd2d 100644
> > --- a/lib/chacha.c
> > +++ b/lib/chacha.c
> > @@ -21,7 +21,7 @@ static void chacha_permute(u32 *x, int nrounds)
> >         int i;
> >
> >         /* whitelist the allowed round counts */
> > -       BUG_ON(nrounds != 20);
> > +       BUG_ON(nrounds != 20 && nrounds != 12);
> >
> 
> I didn't spot this until this patch, but BUG_ON() may bring down the
> kernel, and so it should really only be used as a last resort. (i.e.,
> if this is called from non-process context things may explode rather
> painfully)
> 
> I didn't look at the entire file [which is a bit cumbersome while
> reviewing incremental changes like this] and so I don't really have
> another suggestion right now, but please try to come up with something
> better if you can.
> 

I'll change it to WARN_ON_ONCE(), I guess.  I do still want it to be very noisy
if something fishy is going on with the round count.

- Eric

  reply	other threads:[~2018-10-19 18:28 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-15 17:54 [RFC PATCH v2 00/12] crypto: Adiantum support Eric Biggers
2018-10-15 17:54 ` [RFC PATCH v2 01/12] crypto: chacha20-generic - add HChaCha20 library function Eric Biggers
2018-10-19 14:13   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 02/12] crypto: chacha20-generic - add XChaCha20 support Eric Biggers
2018-10-19 14:24   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 03/12] crypto: chacha20-generic - refactor to allow varying number of rounds Eric Biggers
2018-10-19 14:25   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 04/12] crypto: chacha - add XChaCha12 support Eric Biggers
2018-10-19 14:34   ` Ard Biesheuvel
2018-10-19 18:28     ` Eric Biggers [this message]
2018-10-15 17:54 ` [RFC PATCH v2 05/12] crypto: arm/chacha20 - add XChaCha20 support Eric Biggers
2018-10-20  2:29   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 06/12] crypto: arm/chacha20 - refactor to allow varying number of rounds Eric Biggers
2018-10-20  3:35   ` Ard Biesheuvel
2018-10-20  5:26     ` Eric Biggers
2018-10-15 17:54 ` [RFC PATCH v2 07/12] crypto: arm/chacha - add XChaCha12 support Eric Biggers
2018-10-20  3:36   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 08/12] crypto: poly1305 - add Poly1305 core API Eric Biggers
2018-10-20  3:45   ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 09/12] crypto: nhpoly1305 - add NHPoly1305 support Eric Biggers
2018-10-20  4:00   ` Ard Biesheuvel
2018-10-20  5:38     ` Eric Biggers
2018-10-20 15:06       ` Ard Biesheuvel
2018-10-22 18:42         ` Eric Biggers
2018-10-22 22:25           ` Ard Biesheuvel
2018-10-22 22:40             ` Eric Biggers
2018-10-22 22:43               ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 10/12] crypto: arm/nhpoly1305 - add NEON-accelerated NHPoly1305 Eric Biggers
2018-10-20  4:12   ` Ard Biesheuvel
2018-10-20  5:51     ` Eric Biggers
2018-10-20 15:00       ` Ard Biesheuvel
2018-10-15 17:54 ` [RFC PATCH v2 11/12] crypto: adiantum - add Adiantum support Eric Biggers
2018-10-20  4:17   ` Ard Biesheuvel
2018-10-20  7:12     ` Eric Biggers
2018-10-23 10:40       ` Ard Biesheuvel
2018-10-24 22:06         ` Eric Biggers
2018-10-30  8:17           ` Herbert Xu
2018-10-15 17:54 ` [RFC PATCH v2 12/12] fscrypt: " Eric Biggers
2018-10-19 15:58 ` [RFC PATCH v2 00/12] crypto: " Jason A. Donenfeld
2018-10-19 18:19   ` Paul Crowley
2018-10-20  3:24     ` Ard Biesheuvel
2018-10-20  5:22       ` Eric Biggers
     [not found]     ` <2395454e-a0dc-408f-4138-9d15ab5f20b8@esat.kuleuven.be>
2018-10-22 11:20       ` Tomer Ashur
2018-10-19 19:04   ` Eric Biggers
2018-10-20 10:26     ` Milan Broz
2018-10-20 13:47       ` Jason A. Donenfeld
2018-11-16 21:52       ` Eric Biggers
2018-11-17 10:29         ` Milan Broz
2018-11-19 19:28           ` Eric Biggers
2018-11-19 20:05             ` Milan Broz
2018-11-19 20:30               ` Jason A. Donenfeld
2018-10-21 22:23     ` Eric Biggers
2018-10-21 22:51       ` Jason A. Donenfeld
2018-10-22 17:17         ` Paul Crowley

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20181019182804.GA246441@gmail.com \
    --to=ebiggers@kernel.org \
    --cc=Jason@zx2c4.com \
    --cc=ard.biesheuvel@linaro.org \
    --cc=gkaiser@google.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=linux-fscrypt@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhalcrow@google.com \
    --cc=paulcrowley@google.com \
    --cc=samuel.c.p.neves@gmail.com \
    --cc=tomer.ashur@esat.kuleuven.be \
    --subject='Re: [RFC PATCH v2 04/12] crypto: chacha - add XChaCha12 support' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).