// SPDX-License-Identifier: GPL-2.0-or-later/* * Crypto API wrappers for the ChaCha20, XChaCha20, and XChaCha12 stream ciphers * * Copyright (C) 2015 Martin Willi * Copyright (C) 2018 Google LLC */ #include <linux/unaligned.h>#include <crypto/algapi.h>#include <crypto/chacha.h>#include <crypto/internal/skcipher.h>#include <linux/module.h> struct chacha_ctx {	u32 key[8];	int nrounds;}; static int chacha_setkey(struct crypto_skcipher *tfm,			 const u8 *key, unsigned int keysize, int nrounds){	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);	int i; 	if (keysize != CHACHA_KEY_SIZE)		return -EINVAL; 	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32)); 	ctx->nrounds = nrounds;	return 0;} static int chacha20_setkey(struct crypto_skcipher *tfm,			   const u8 *key, unsigned int keysize){	return chacha_setkey(tfm, key, keysize, 20);} static int chacha12_setkey(struct crypto_skcipher *tfm,			   const u8 *key, unsigned int keysize){	return chacha_setkey(tfm, key, keysize, 12);} static int chacha_stream_xor(struct skcipher_request *req,			     const struct chacha_ctx *ctx,			     const u8 iv[CHACHA_IV_SIZE]){	struct skcipher_walk walk;	struct chacha_state state;	int err; 	err = skcipher_walk_virt(&walk, req, false); 	chacha_init(&state, ctx->key, iv); 	while (walk.nbytes > 0) {		unsigned int nbytes = walk.nbytes; 		if (nbytes < walk.total)			nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE); 		chacha_crypt(&state, walk.dst.virt.addr, walk.src.virt.addr,			     nbytes, ctx->nrounds);		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);	} 	return err;} static int crypto_chacha_crypt(struct skcipher_request *req){	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);	const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); 	return chacha_stream_xor(req, ctx, req->iv);} static int crypto_xchacha_crypt(struct skcipher_request *req){	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);	const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);	struct chacha_ctx subctx;	struct chacha_state state;	u8 real_iv[16]; 	/* Compute the subkey given the original key and first 128 nonce bits */	chacha_init(&state, ctx->key, req->iv);	hchacha_block(&state, subctx.key, ctx->nrounds);	subctx.nrounds = ctx->nrounds; 	/* 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 chacha_stream_xor(req, &subctx, real_iv);} static struct skcipher_alg algs[] = {	{		.base.cra_name		= "chacha20",		.base.cra_driver_name	= "chacha20-lib",		.base.cra_priority	= 300,		.base.cra_blocksize	= 1,		.base.cra_ctxsize	= sizeof(struct chacha_ctx),		.base.cra_module	= THIS_MODULE, 		.min_keysize		= CHACHA_KEY_SIZE,		.max_keysize		= CHACHA_KEY_SIZE,		.ivsize			= CHACHA_IV_SIZE,		.chunksize		= CHACHA_BLOCK_SIZE,		.setkey			= chacha20_setkey,		.encrypt		= crypto_chacha_crypt,		.decrypt		= crypto_chacha_crypt,	},	{		.base.cra_name		= "xchacha20",		.base.cra_driver_name	= "xchacha20-lib",		.base.cra_priority	= 300,		.base.cra_blocksize	= 1,		.base.cra_ctxsize	= sizeof(struct chacha_ctx),		.base.cra_module	= THIS_MODULE, 		.min_keysize		= CHACHA_KEY_SIZE,		.max_keysize		= CHACHA_KEY_SIZE,		.ivsize			= XCHACHA_IV_SIZE,		.chunksize		= CHACHA_BLOCK_SIZE,		.setkey			= chacha20_setkey,		.encrypt		= crypto_xchacha_crypt,		.decrypt		= crypto_xchacha_crypt,	},	{		.base.cra_name		= "xchacha12",		.base.cra_driver_name	= "xchacha12-lib",		.base.cra_priority	= 300,		.base.cra_blocksize	= 1,		.base.cra_ctxsize	= sizeof(struct chacha_ctx),		.base.cra_module	= THIS_MODULE, 		.min_keysize		= CHACHA_KEY_SIZE,		.max_keysize		= CHACHA_KEY_SIZE,		.ivsize			= XCHACHA_IV_SIZE,		.chunksize		= CHACHA_BLOCK_SIZE,		.setkey			= chacha12_setkey,		.encrypt		= crypto_xchacha_crypt,		.decrypt		= crypto_xchacha_crypt,	}}; static int __init crypto_chacha_mod_init(void){	return crypto_register_skciphers(algs, ARRAY_SIZE(algs));} static void __exit crypto_chacha_mod_fini(void){	crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));} module_init(crypto_chacha_mod_init);module_exit(crypto_chacha_mod_fini); MODULE_LICENSE("GPL");MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");MODULE_DESCRIPTION("Crypto API wrappers for the ChaCha20, XChaCha20, and XChaCha12 stream ciphers");MODULE_ALIAS_CRYPTO("chacha20");MODULE_ALIAS_CRYPTO("chacha20-lib");MODULE_ALIAS_CRYPTO("xchacha20");MODULE_ALIAS_CRYPTO("xchacha20-lib");MODULE_ALIAS_CRYPTO("xchacha12");MODULE_ALIAS_CRYPTO("xchacha12-lib");