Re: [RFC 1/7] crypto: Add GHASH digest algorithm for GCM

[Sebastian Andrzej Siewior <linux-crypto@ml.breakpoint.cc>]

* 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@intel.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@iki.fi>
>+ * Copyright (c) 2009 Intel Corp.
>+ *   Author: Huang Ying <ying.huang@intel.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?

>+
>+#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

>+	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

>+	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().

>+	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

> 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?

>+obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o
> 
> #
> # generic algorithms and the async_tx api
>
>

Sebastian