crypto: chacha20-generic - refactor to allow varying number of rounds

In preparation for adding XChaCha12 support, rename/refactor
chacha20-generic to support different numbers of rounds.  The
justification for needing XChaCha12 support is explained in more detail
in the patch "crypto: chacha - add XChaCha12 support".

The only difference between ChaCha{8,12,20} are the number of rounds
itself; all other parts of the algorithm are the same.  Therefore,
remove the "20" from all definitions, structures, functions, files, etc.
that will be shared by all ChaCha versions.

Also make ->setkey() store the round count in the chacha_ctx (previously
chacha20_ctx).  The generic code then passes the round count through to
chacha_block().  There will be a ->setkey() function for each explicitly
allowed round count; the encrypt/decrypt functions will be the same.  I
decided not to do it the opposite way (same ->setkey() function for all
round counts, with different encrypt/decrypt functions) because that
would have required more boilerplate code in architecture-specific
implementations of ChaCha and XChaCha.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 185 deletions

diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c
deleted file mode 100644
index 4305b1b62b16..000000000000
--- a/crypto/chacha20_generic.c
+++ /dev/null
@@ -1,185 +0,0 @@
-/*
- * ChaCha20 (RFC7539) and XChaCha20 stream cipher algorithms
- *
- * Copyright (C) 2015 Martin Willi
- * Copyright (C) 2018 Google LLC
- *
- * 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 <asm/unaligned.h>
-#include <crypto/algapi.h>
-#include <crypto/chacha20.h>
-#include <crypto/internal/skcipher.h>
-#include <linux/module.h>
-
-static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
-			     unsigned int bytes)
-{
-	/* aligned to potentially speed up crypto_xor() */
-	u8 stream[CHACHA20_BLOCK_SIZE] __aligned(sizeof(long));
-
-	if (dst != src)
-		memcpy(dst, src, bytes);
-
-	while (bytes >= CHACHA20_BLOCK_SIZE) {
-		chacha20_block(state, stream);
-		crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
-		bytes -= CHACHA20_BLOCK_SIZE;
-		dst += CHACHA20_BLOCK_SIZE;
-	}
-	if (bytes) {
-		chacha20_block(state, stream);
-		crypto_xor(dst, stream, bytes);
-	}
-}
-
-static int chacha20_stream_xor(struct skcipher_request *req,
-			       struct chacha20_ctx *ctx, u8 *iv)
-{
-	struct skcipher_walk walk;
-	u32 state[16];
-	int err;
-
-	err = skcipher_walk_virt(&walk, req, false);
-
-	crypto_chacha20_init(state, ctx, iv);
-
-	while (walk.nbytes > 0) {
-		unsigned int nbytes = walk.nbytes;
-
-		if (nbytes < walk.total)
-			nbytes = round_down(nbytes, walk.stride);
-
-		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
-				 nbytes);
-		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
-	}
-
-	return err;
-}
-
-void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
-{
-	state[0]  = 0x61707865; /* "expa" */
-	state[1]  = 0x3320646e; /* "nd 3" */
-	state[2]  = 0x79622d32; /* "2-by" */
-	state[3]  = 0x6b206574; /* "te k" */
-	state[4]  = ctx->key[0];
-	state[5]  = ctx->key[1];
-	state[6]  = ctx->key[2];
-	state[7]  = ctx->key[3];
-	state[8]  = ctx->key[4];
-	state[9]  = ctx->key[5];
-	state[10] = ctx->key[6];
-	state[11] = ctx->key[7];
-	state[12] = get_unaligned_le32(iv +  0);
-	state[13] = get_unaligned_le32(iv +  4);
-	state[14] = get_unaligned_le32(iv +  8);
-	state[15] = get_unaligned_le32(iv + 12);
-}
-EXPORT_SYMBOL_GPL(crypto_chacha20_init);
-
-int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
-			   unsigned int keysize)
-{
-	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
-	int i;
-
-	if (keysize != CHACHA20_KEY_SIZE)
-		return -EINVAL;
-
-	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
-		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
-
-int crypto_chacha20_crypt(struct skcipher_request *req)
-{
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
-
-	return chacha20_stream_xor(req, ctx, req->iv);
-}
-EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
-
-int crypto_xchacha20_crypt(struct skcipher_request *req)
-{
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
-	struct chacha20_ctx subctx;
-	u32 state[16];
-	u8 real_iv[16];
-
-	/* Compute the subkey given the original key and first 128 nonce bits */
-	crypto_chacha20_init(state, ctx, req->iv);
-	hchacha20_block(state, subctx.key);
-
-	/* Build the real IV */
-	memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
-	memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
-
-	/* Generate the stream and XOR it with the data */
-	return chacha20_stream_xor(req, &subctx, real_iv);
-}
-EXPORT_SYMBOL_GPL(crypto_xchacha20_crypt);
-
-static struct skcipher_alg algs[] = {
-	{
-		.base.cra_name		= "chacha20",
-		.base.cra_driver_name	= "chacha20-generic",
-		.base.cra_priority	= 100,
-		.base.cra_blocksize	= 1,
-		.base.cra_ctxsize	= sizeof(struct chacha20_ctx),
-		.base.cra_module	= THIS_MODULE,
-
-		.min_keysize		= CHACHA20_KEY_SIZE,
-		.max_keysize		= CHACHA20_KEY_SIZE,
-		.ivsize			= CHACHA20_IV_SIZE,
-		.chunksize		= CHACHA20_BLOCK_SIZE,
-		.setkey			= crypto_chacha20_setkey,
-		.encrypt		= crypto_chacha20_crypt,
-		.decrypt		= crypto_chacha20_crypt,
-	}, {
-		.base.cra_name		= "xchacha20",
-		.base.cra_driver_name	= "xchacha20-generic",
-		.base.cra_priority	= 100,
-		.base.cra_blocksize	= 1,
-		.base.cra_ctxsize	= sizeof(struct chacha20_ctx),
-		.base.cra_module	= THIS_MODULE,
-
-		.min_keysize		= CHACHA20_KEY_SIZE,
-		.max_keysize		= CHACHA20_KEY_SIZE,
-		.ivsize			= XCHACHA20_IV_SIZE,
-		.chunksize		= CHACHA20_BLOCK_SIZE,
-		.setkey			= crypto_chacha20_setkey,
-		.encrypt		= crypto_xchacha20_crypt,
-		.decrypt		= crypto_xchacha20_crypt,
-	}
-};
-
-static int __init chacha20_generic_mod_init(void)
-{
-	return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
-}
-
-static void __exit chacha20_generic_mod_fini(void)
-{
-	crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
-}
-
-module_init(chacha20_generic_mod_init);
-module_exit(chacha20_generic_mod_fini);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
-MODULE_DESCRIPTION("ChaCha20 and XChaCha20 stream ciphers (generic)");
-MODULE_ALIAS_CRYPTO("chacha20");
-MODULE_ALIAS_CRYPTO("chacha20-generic");
-MODULE_ALIAS_CRYPTO("xchacha20");
-MODULE_ALIAS_CRYPTO("xchacha20-generic");