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Date: Thu, 18 Jun 2009 10:08:27 +0800
From: Huang Ying <ying.huang@...el.com>
To: Sebastian Andrzej Siewior <linux-crypto@...breakpoint.cc>
Cc: Herbert Xu <herbert@...dor.apana.org.au>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [RFC 1/7] crypto: Add GHASH digest algorithm for GCM
On Thu, 2009-06-18 at 04:04 +0800, Sebastian Andrzej Siewior wrote:
> * Huang Ying | 2009-06-11 15:10:26 [+0800]:
>
> >GHASH is implemented as a shash algorithm. The actual implementation
> >is copied from gcm.c. This makes it possible to add
> >architecture/hardware accelerated GHASH implementation.
> >
> >Signed-off-by: Huang Ying <ying.huang@...el.com>
> >
> >---
> > crypto/Kconfig | 7 +
> > crypto/Makefile | 2
> > crypto/ghash-generic.c | 179 +++++++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 188 insertions(+)
> >
> >--- /dev/null
> >+++ b/crypto/ghash-generic.c
> >@@ -0,0 +1,179 @@
> >+/*
> >+ * GHASH: digest algorithm for GCM (Galois/Counter Mode).
> >+ *
> >+ * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@....fi>
> >+ * Copyright (c) 2009 Intel Corp.
> >+ * Author: Huang Ying <ying.huang@...el.com>
> >+ *
> >+ * The algorithm implementation is copied from gcm.c.
> >+ *
> >+ * This program is free software; you can redistribute it and/or modify it
> >+ * under the terms of the GNU General Public License version 2 as published
> >+ * by the Free Software Foundation.
> >+ */
> >+
> >+#include <linux/module.h>
> >+#include <linux/init.h>
> >+#include <linux/kernel.h>
> >+#include <linux/crypto.h>
> >+#include <crypto/gf128mul.h>
> >+#include <crypto/algapi.h>
> >+#include <crypto/internal/hash.h>
> Do you mind to sort them?
Sorry, can you tell me what is the better order?
> >+
> >+#define GHASH_BLOCK_SIZE 16
> >+#define GHASH_DIGEST_SIZE 16
> >+
> >+struct ghash_ctx {
> >+ struct gf128mul_4k *gf128;
> >+};
> >+
> >+struct ghash_desc_ctx {
> >+ u8 buffer[16];
> >+ u32 bytes;
> >+};
> >+
> >+static int ghash_init(struct shash_desc *desc)
> >+{
> >+ struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
> >+
> >+ dctx->bytes = 0;
> >+ memset(dctx->buffer, 0, 16);
> >+
> you could memset() the whole struct at once
Yes. That is better, you are right.
> >+ return 0;
> >+}
> >+
> >+static int ghash_setkey(struct crypto_shash *tfm,
> >+ const u8 *key, unsigned int keylen)
> >+{
> >+ struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
> >+
> >+ if (keylen != 16) {
> >+ crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
> >+ return -EINVAL;
> >+ }
> >+
> >+ if (ctx->gf128)
> >+ gf128mul_free_4k(ctx->gf128);
> >+ ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
> >+ if (!ctx->gf128)
> >+ return -ENOMEM;
> >+
> >+ return 0;
> >+}
> >+
> >+static int ghash_update(struct shash_desc *desc,
> >+ const u8 *src, unsigned int srclen)
> >+{
> >+ struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
> >+ struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
> >+ u8 *dst = dctx->buffer;
> >+
> >+ if (dctx->bytes) {
> >+ int n = min(srclen, dctx->bytes);
> >+ u8 *pos = dst + (16 - dctx->bytes);
> >+
> >+ dctx->bytes -= n;
> >+ srclen -= n;
> >+
> >+ while (n--)
> >+ *pos++ ^= *src++;
> >+
> >+ if (!dctx->bytes)
> >+ gf128mul_4k_lle((be128 *)dst, ctx->gf128);
> >+ }
> >+
> >+ while (srclen >= 16) {
> >+ crypto_xor(dst, src, 16);
> >+ gf128mul_4k_lle((be128 *)dst, ctx->gf128);
> >+ src += 16;
> >+ srclen -= 16;
> >+ }
> >+
> >+ if (srclen) {
> >+ dctx->bytes = 16 - srclen;
> >+ while (srclen--)
> >+ *dst++ ^= *src++;
> >+ }
> >+
> 16 here looks like GHASH_BLOCK_SIZE to me
Yes. I will change most 16 to corresponding symbol name.
> >+ return 0;
> >+}
> >+
> >+static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
> >+{
> >+ u8 *dst = dctx->buffer;
> >+
> >+ if (dctx->bytes) {
> >+ u8 *tmp = dst + (16 - dctx->bytes);
> >+
> >+ while (dctx->bytes--)
> >+ *tmp++ ^= 0;
> >+
> >+ gf128mul_4k_lle((be128 *)dst, ctx->gf128);
> >+ }
> >+
> >+ dctx->bytes = 0;
> >+}
> >+
> >+static int ghash_final(struct shash_desc *desc, u8 *dst)
> >+{
> >+ struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
> >+ struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
> >+ u8 *buf = dctx->buffer;
> >+
> >+ ghash_flush(ctx, dctx);
> >+ memcpy(dst, buf, 16);
> >+
> >+ return 0;
> >+}
> >+
> >+static int ghash_init_tfm(struct crypto_tfm *tfm)
> >+{
> >+ struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
> >+ ctx->gf128 = NULL;
>
> Unless I'm mistaken, this is called once on allocation and this ctx is
> allocated via kzalloc().
Yes. it is alloced via kzalloc. Can we just rely on this? Should we add
that assumption to somewhere such as document of comments.
> >+ return 0;
> >+}
> >+
> >+static void ghash_exit_tfm(struct crypto_tfm *tfm)
> >+{
> >+ struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
> >+ if (ctx->gf128)
> >+ gf128mul_free_4k(ctx->gf128);
> >+}
> >+
> >+static struct shash_alg ghash_alg = {
> >+ .digestsize = GHASH_DIGEST_SIZE,
> >+ .init = ghash_init,
> >+ .update = ghash_update,
> >+ .final = ghash_final,
> >+ .setkey = ghash_setkey,
> >+ .descsize = sizeof(struct ghash_desc_ctx),
> >+ .base = {
> >+ .cra_name = "ghash",
> >+ .cra_driver_name = "ghash-generic",
> >+ .cra_priority = 100,
> >+ .cra_flags = CRYPTO_ALG_TYPE_SHASH,
> >+ .cra_blocksize = GHASH_BLOCK_SIZE,
> >+ .cra_ctxsize = sizeof(struct ghash_ctx),
> >+ .cra_module = THIS_MODULE,
> >+ .cra_list = LIST_HEAD_INIT(ghash_alg.base.cra_list),
> >+ .cra_init = ghash_init_tfm,
> >+ .cra_exit = ghash_exit_tfm,
> >+ },
> >+};
> >+
> >+static int __init ghash_mod_init(void)
> >+{
> >+ return crypto_register_shash(&ghash_alg);
> >+}
> >+
> >+static void __exit ghash_mod_exit(void)
> >+{
> >+ crypto_unregister_shash(&ghash_alg);
> >+}
> >+
> >+module_init(ghash_mod_init);
> >+module_exit(ghash_mod_exit);
> >+
> >+MODULE_LICENSE("GPL");
> >+MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
> >+MODULE_ALIAS("ghash");
> >--- a/crypto/Kconfig
> >+++ b/crypto/Kconfig
> >@@ -419,6 +419,13 @@ config CRYPTO_WP512
> > See also:
> > <http://planeta.terra.com.br/informatica/paulobarreto/WhirlpoolPage.html>
> >
> >+config CRYPTO_GHASH
> >+ tristate "GHASH digest algorithm"
> >+ select CRYPTO_SHASH
> >+ select CRYPTO_GF128MUL
> >+ help
> >+ GHASH is message digest algorithm for GCM (Galois/Counter Mode).
> >+
> Could you please move it to the 'G' section
OK. I will do this.
> > comment "Ciphers"
> >
> > config CRYPTO_AES
> >--- a/crypto/Makefile
> >+++ b/crypto/Makefile
> >@@ -83,6 +83,8 @@ obj-$(CONFIG_CRYPTO_RNG2) += rng.o
> > obj-$(CONFIG_CRYPTO_RNG2) += krng.o
> > obj-$(CONFIG_CRYPTO_ANSI_CPRNG) += ansi_cprng.o
> > obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o
> >+obj-$(CONFIG_CRYPTO_MD5) += md5.o
> md5?
Sorry, I will remove this, and move GHASH line to appropriate position.
> >+obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o
> >
> > #
> > # generic algorithms and the async_tx api
> >
> >
Best Regards,
Huang Ying
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