From: Neil Horman Subject: [PATCH] crypto: extend ansi_cprng to allow resetting of DT value Date: Mon, 3 Nov 2008 16:22:40 -0500 Message-ID: <20081103212240.GB24888@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: nhorman@tuxdriver.com, jarod@redhat.com To: herbert@gondor.apana.org.au, davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:51676 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754118AbYKCVYr (ORCPT ); Mon, 3 Nov 2008 16:24:47 -0500 Content-Disposition: inline Sender: linux-crypto-owner@vger.kernel.org List-ID: Hey all- This is a patch that was sent to me by Jarod Wilson, marking off my outstanding todo to allow the ansi cprng to set/reset the DT counter value in a cprng instance. Currently crytpo_rng_reset accepts a seed byte array which is interpreted by the ansi_cprng as a {V key} tuple. This patch extends that tuple to now be {V key DT}, with DT an optional value during reset. This patch also fixes a bug we noticed in which the offset of the key area of the seed is started at DEFAULT_PRNG_KSZ rather than DEFAULT_BLK_SZ as it should be. Regards Neil Signed-off-by: Neil Horman ansi_cprng.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c index 72db0fd..486aa93 100644 --- a/crypto/ansi_cprng.c +++ b/crypto/ansi_cprng.c @@ -349,15 +349,25 @@ static int cprng_get_random(struct crypto_rng *tfm, u8 *rdata, return get_prng_bytes(rdata, dlen, prng); } +/* + * This is the cprng_registered reset method the seed value is + * interpreted as the tuple { V KEY DT} + * V and KEY are required during reset, and DT is optional, detected + * as being present by testing the length of the seed + */ static int cprng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen) { struct prng_context *prng = crypto_rng_ctx(tfm); - u8 *key = seed + DEFAULT_PRNG_KSZ; + u8 *key = seed + DEFAULT_BLK_SZ; + u8 *dt = NULL; if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ) return -EINVAL; - reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, NULL); + if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ)) + dt = key + DEFAULT_PRNG_KSZ; + + reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt); if (prng->flags & PRNG_NEED_RESET) return -EINVAL; @@ -379,7 +389,7 @@ static struct crypto_alg rng_alg = { .rng = { .rng_make_random = cprng_get_random, .rng_reset = cprng_reset, - .seedsize = DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ, + .seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ, } } }; -- /**************************************************** * Neil Horman * Software Engineer, Red Hat ****************************************************/