140 lines
3.9 KiB
C
140 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539)
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*
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* Copyright (C) 2015 Martin Willi
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* Copyright (C) 2018 Google LLC
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*/
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#include <linux/unaligned.h>
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#include <crypto/algapi.h>
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#include <crypto/internal/chacha.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/module.h>
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static int chacha_stream_xor(struct skcipher_request *req,
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const struct chacha_ctx *ctx, const u8 *iv)
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{
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struct skcipher_walk walk;
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u32 state[16];
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int err;
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err = skcipher_walk_virt(&walk, req, false);
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chacha_init_generic(state, ctx->key, iv);
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while (walk.nbytes > 0) {
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unsigned int nbytes = walk.nbytes;
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if (nbytes < walk.total)
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nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
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chacha_crypt_generic(state, walk.dst.virt.addr,
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walk.src.virt.addr, nbytes, ctx->nrounds);
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err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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}
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return err;
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}
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static int crypto_chacha_crypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
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return chacha_stream_xor(req, ctx, req->iv);
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}
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static int crypto_xchacha_crypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct chacha_ctx subctx;
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u32 state[16];
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u8 real_iv[16];
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/* Compute the subkey given the original key and first 128 nonce bits */
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chacha_init_generic(state, ctx->key, req->iv);
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hchacha_block_generic(state, subctx.key, ctx->nrounds);
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subctx.nrounds = ctx->nrounds;
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/* Build the real IV */
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memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
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memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
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/* Generate the stream and XOR it with the data */
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return chacha_stream_xor(req, &subctx, real_iv);
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}
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static struct skcipher_alg algs[] = {
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{
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.base.cra_name = "chacha20",
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.base.cra_driver_name = "chacha20-generic",
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.base.cra_priority = 100,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA_KEY_SIZE,
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.max_keysize = CHACHA_KEY_SIZE,
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.ivsize = CHACHA_IV_SIZE,
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.chunksize = CHACHA_BLOCK_SIZE,
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.setkey = chacha20_setkey,
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.encrypt = crypto_chacha_crypt,
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.decrypt = crypto_chacha_crypt,
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}, {
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.base.cra_name = "xchacha20",
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.base.cra_driver_name = "xchacha20-generic",
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.base.cra_priority = 100,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA_KEY_SIZE,
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.max_keysize = CHACHA_KEY_SIZE,
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.ivsize = XCHACHA_IV_SIZE,
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.chunksize = CHACHA_BLOCK_SIZE,
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.setkey = chacha20_setkey,
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.encrypt = crypto_xchacha_crypt,
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.decrypt = crypto_xchacha_crypt,
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}, {
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.base.cra_name = "xchacha12",
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.base.cra_driver_name = "xchacha12-generic",
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.base.cra_priority = 100,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA_KEY_SIZE,
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.max_keysize = CHACHA_KEY_SIZE,
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.ivsize = XCHACHA_IV_SIZE,
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.chunksize = CHACHA_BLOCK_SIZE,
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.setkey = chacha12_setkey,
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.encrypt = crypto_xchacha_crypt,
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.decrypt = crypto_xchacha_crypt,
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}
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};
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static int __init chacha_generic_mod_init(void)
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{
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return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
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}
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static void __exit chacha_generic_mod_fini(void)
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{
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crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
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}
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subsys_initcall(chacha_generic_mod_init);
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module_exit(chacha_generic_mod_fini);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
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MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)");
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MODULE_ALIAS_CRYPTO("chacha20");
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MODULE_ALIAS_CRYPTO("chacha20-generic");
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MODULE_ALIAS_CRYPTO("xchacha20");
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MODULE_ALIAS_CRYPTO("xchacha20-generic");
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MODULE_ALIAS_CRYPTO("xchacha12");
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MODULE_ALIAS_CRYPTO("xchacha12-generic");
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