crypto: powerpc/md5 - glue

Glue code for crypto infrastructure. Call the assembler
code where required. Take a little care about small input
data. Kick out early for input chunks < 64 bytes and replace
memset for context cleanup with simple loop.
Signed-off-by: NMarkus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/powerpc/crypto/md5_glue.c

+/*
+ * Glue code for MD5 implementation for PPC assembler
+ *
+ * Based on generic implementation.
+ *
+ * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/cryptohash.h>
+#include <linux/types.h>
+#include <crypto/md5.h>
+#include <asm/byteorder.h>
+
+extern void ppc_md5_transform(u32 *state, const u8 *src, u32 blocks);
+
+static inline void ppc_md5_clear_context(struct md5_state *sctx)
+{
+	int count = sizeof(struct md5_state) >> 2;
+	u32 *ptr = (u32 *)sctx;
+
+	/* make sure we can clear the fast way */
+	BUILD_BUG_ON(sizeof(struct md5_state) % 4);
+	do { *ptr++ = 0; } while (--count);
+}
+
+static int ppc_md5_init(struct shash_desc *desc)
+{
+	struct md5_state *sctx = shash_desc_ctx(desc);
+
+	sctx->hash[0] = 0x67452301;
+	sctx->hash[1] = 0xefcdab89;
+	sctx->hash[2] = 0x98badcfe;
+	sctx->hash[3] =	0x10325476;
+	sctx->byte_count = 0;
+
+	return 0;
+}
+
+static int ppc_md5_update(struct shash_desc *desc, const u8 *data,
+			unsigned int len)
+{
+	struct md5_state *sctx = shash_desc_ctx(desc);
+	const unsigned int offset = sctx->byte_count & 0x3f;
+	unsigned int avail = 64 - offset;
+	const u8 *src = data;
+
+	sctx->byte_count += len;
+
+	if (avail > len) {
+		memcpy((char *)sctx->block + offset, src, len);
+		return 0;
+	}
+
+	if (offset) {
+		memcpy((char *)sctx->block + offset, src, avail);
+		ppc_md5_transform(sctx->hash, (const u8 *)sctx->block, 1);
+		len -= avail;
+		src += avail;
+	}
+
+	if (len > 63) {
+		ppc_md5_transform(sctx->hash, src, len >> 6);
+		src += len & ~0x3f;
+		len &= 0x3f;
+	}
+
+	memcpy((char *)sctx->block, src, len);
+	return 0;
+}
+
+static int ppc_md5_final(struct shash_desc *desc, u8 *out)
+{
+	struct md5_state *sctx = shash_desc_ctx(desc);
+	const unsigned int offset = sctx->byte_count & 0x3f;
+	const u8 *src = (const u8 *)sctx->block;
+	u8 *p = (u8 *)src + offset;
+	int padlen = 55 - offset;
+	__le64 *pbits = (__le64 *)((char *)sctx->block + 56);
+	__le32 *dst = (__le32 *)out;
+
+	*p++ = 0x80;
+
+	if (padlen < 0) {
+		memset(p, 0x00, padlen + sizeof (u64));
+		ppc_md5_transform(sctx->hash, src, 1);
+		p = (char *)sctx->block;
+		padlen = 56;
+	}
+
+	memset(p, 0, padlen);
+	*pbits = cpu_to_le64(sctx->byte_count << 3);
+	ppc_md5_transform(sctx->hash, src, 1);
+
+	dst[0] = cpu_to_le32(sctx->hash[0]);
+	dst[1] = cpu_to_le32(sctx->hash[1]);
+	dst[2] = cpu_to_le32(sctx->hash[2]);
+	dst[3] = cpu_to_le32(sctx->hash[3]);
+
+	ppc_md5_clear_context(sctx);
+	return 0;
+}
+
+static int ppc_md5_export(struct shash_desc *desc, void *out)
+{
+	struct md5_state *sctx = shash_desc_ctx(desc);
+
+	memcpy(out, sctx, sizeof(*sctx));
+	return 0;
+}
+
+static int ppc_md5_import(struct shash_desc *desc, const void *in)
+{
+	struct md5_state *sctx = shash_desc_ctx(desc);
+
+	memcpy(sctx, in, sizeof(*sctx));
+	return 0;
+}
+
+static struct shash_alg alg = {
+	.digestsize	=	MD5_DIGEST_SIZE,
+	.init		=	ppc_md5_init,
+	.update		=	ppc_md5_update,
+	.final		=	ppc_md5_final,
+	.export		=	ppc_md5_export,
+	.import		=	ppc_md5_import,
+	.descsize	=	sizeof(struct md5_state),
+	.statesize	=	sizeof(struct md5_state),
+	.base		=	{
+		.cra_name	=	"md5",
+		.cra_driver_name=	"md5-ppc",
+		.cra_priority	=	200,
+		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
+		.cra_blocksize	=	MD5_HMAC_BLOCK_SIZE,
+		.cra_module	=	THIS_MODULE,
+	}
+};
+
+static int __init ppc_md5_mod_init(void)
+{
+	return crypto_register_shash(&alg);
+}
+
+static void __exit ppc_md5_mod_fini(void)
+{
+	crypto_unregister_shash(&alg);
+}
+
+module_init(ppc_md5_mod_init);
+module_exit(ppc_md5_mod_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MD5 Secure Hash Algorithm, PPC assembler");
+
+MODULE_ALIAS_CRYPTO("md5");
+MODULE_ALIAS_CRYPTO("md5-ppc");